The premetastatic niches(PMN)formed by primary tumor-derived molecules regulate distant organs and tissues to further favor tumor colonization.Targeted PMN therapy may prevent tumor metastasis in the early stages,whic...The premetastatic niches(PMN)formed by primary tumor-derived molecules regulate distant organs and tissues to further favor tumor colonization.Targeted PMN therapy may prevent tumor metastasis in the early stages,which is becoming increasingly important.At present,there is a lack of in-depth understanding of the cellular and molecular characteristics of the PMN.Here,we summarize current research advances on the cellular and molecular characteristics of the PMN.We emphasize that PMN intervention is a potential therapeutic strategy for early prevention of tumor metastasis,which provides a promising basis for future research and clinical application.展开更多
Stem cell microterritories(niches),as a specialized part of the extracellular matrix(ECM),are considered an important target and tool for the development of new materials,medical implants,and devices.However,tissue bi...Stem cell microterritories(niches),as a specialized part of the extracellular matrix(ECM),are considered an important target and tool for the development of new materials,medical implants,and devices.However,tissue bioengineering products that have stem cell niches of known size on the surface or in the bulk structure of artificial materials are practically unknown.This brief review attempts to draw attention to the problematic aspects of niches as specific parts of the ECM,such as their hierarchy and size for mesenchymal stromal/stem cells(MSCs).These parameters arise directly from numerous definitions of stem cell niches as specialized morphological microterritories found in various tissues.The authors of this review analyze the known information on the hierarchy of MSC microterritories by analogy with that of hematopoietic stem cells.Occasional reports on the size of artificial MSC niches compared to natural niche candidates are summarized.A consensus on a hierarchy and optimal range of niche sizes for MSCs and other stem cells is needed to accelerate the development of prototyping technologies and additive manufacturing in applications to precise tissue bioengineering and regenerative medicine.展开更多
Background:Diet has a profound impact on the rumen microbiota,and the impact can vary among the different rumen ecological niches(REN).This study investigated the effects of dietary replacement of soybean meal(SBM)wit...Background:Diet has a profound impact on the rumen microbiota,and the impact can vary among the different rumen ecological niches(REN).This study investigated the effects of dietary replacement of soybean meal(SBM)with dried distillers grains with solubles(DDGS)on the rumen microbiota occupying different REN of growing Hu lambs.After a 9-week feeding trial,6 lambs from each dietary treatment(SBM vs.DDGS-based diets)were slaughtered for sample collection.The microbiota of the rumen solid,liquid,and epithelium fractions was examined using amplicon sequencing analysis of bacterial 16S rRNA gene,functional prediction,and qPCR.Results:No interaction of dietary protein source(PS)and REN were detected for virtually all the measurements made in this study.The DDGS substitution resulted in very limited influence on bacterial community structure.However,the metabolic pathways predicted from 16S rRNA gene sequences varied greatly between SBM-and DDGS-based diets.The populations of rumen total bacteria,fungi,sulfate-reducing bacteria(SRB),and methanogens were not influenced by DDGS substitution,but the population of protozoa was reduced.The bacterial communities in rumen solid(RS)and liquid(RL)were similar in taxonomic composition but were different in relative abundance of some taxa.In contrast,the bacterial composition and relative abundance of rumen epithelium(RE)were greatly distinct from those of the RS and the RL.In alignment with the bacterial relative abundance,the metabolic pathways predicted from 16S rRNA genes also varied greatly among the different REN.The populations of total bacteria,protozoa,and methanogens attached to the RE were smaller than those in the RS and RL,and the fungal population on the rumen epitheliumwas smaller than that in the RS but similar to that in the RL.On the contrary,the SRB population on the RE was greater than that in the RS and RL.Conclusions:Substitution of SBM with DDGS had greater impact to the protozoa than to the other microbes,and the microbial community structure and functions at different REN are distinct and niche-adapted.展开更多
Adult neural stem cells are neurogenesis progenitor cells that play an important role in neurogenesis.Therefore,neural regeneration may be a promising target for treatment of many neurological illnesses.The regenerati...Adult neural stem cells are neurogenesis progenitor cells that play an important role in neurogenesis.Therefore,neural regeneration may be a promising target for treatment of many neurological illnesses.The regenerative capacity of adult neural stem cells can be chara cterized by two states:quiescent and active.Quiescent adult neural stem cells are more stable and guarantee the quantity and quality of the adult neural stem cell pool.Active adult neural stem cells are chara cterized by rapid proliferation and differentiation into neurons which allow for integration into neural circuits.This review focuses on diffe rences between quiescent and active adult neural stem cells in nutrition metabolism and protein homeostasis.Furthermore,we discuss the physiological significance and underlying advantages of these diffe rences.Due to the limited number of adult neural stem cells studies,we refe rred to studies of embryonic adult neural stem cells or non-mammalian adult neural stem cells to evaluate specific mechanisms.展开更多
Exosomes are cup-shaped extracellular vesicles with a lipid bilayer that is approximately 30 to 200 nm in thickness.Exosomes are widely distributed in a range of body fluids,including urine,blood,milk,and saliva.Exoso...Exosomes are cup-shaped extracellular vesicles with a lipid bilayer that is approximately 30 to 200 nm in thickness.Exosomes are widely distributed in a range of body fluids,including urine,blood,milk,and saliva.Exosomes exert biological function by transporting factors between different cells and by regulating biological pathways in recipient cells.As an important form of intercellular communication,exosomes are increasingly being investigated due to their ability to transfer bioactive molecules such as lipids,proteins,mRNAs,and microRNAs between cells,and because they can regulate physiological and pathological processes in the central nervous system.Adult neurogenesis is a multistage process by which new neurons are generated and migrate to be integrated into existing neuronal circuits.In the adult brain,neurogenesis is mainly localized in two specialized niches:the subventricular zone adjacent to the lateral ventricles and the subgranular zone of the dentate gyrus.An increasing body of evidence indicates that adult neurogenesis is tightly controlled by environmental conditions with the niches.In recent studies,exosomes released from different sources of cells were shown to play an active role in regulating neurogenesis both in vitro and in vivo,thereby participating in the progression of neurodegenerative disorders in patients and in various disease models.Here,we provide a state-of-the-art synopsis of existing research that aimed to identify the diverse components of exosome cargoes and elucidate the therapeutic potential of exosomal contents in the regulation of neurogenesis in several neurodegenerative diseases.We emphasize that exosomal cargoes could serve as a potential biomarker to monitor functional neurogenesis in adults.In addition,exosomes can also be considered as a novel therapeutic approach to treat various neurodegenerative disorders by improving endogenous neurogenesis to mitigate neuronal loss in the central nervous system.展开更多
Breast cancer cells may disseminate early, before tumor diagnosis. Disseminated tumor cells, or DTCs, reside in the bone marrow, and may persist for years or even decades. Some of these cells may be re-activated to re...Breast cancer cells may disseminate early, before tumor diagnosis. Disseminated tumor cells, or DTCs, reside in the bone marrow, and may persist for years or even decades. Some of these cells may be re-activated to resume aggressive growth, and eventually become overt bone metastases. Recent studies have begun to shed light on this complicated process and revealed multiple steps and intermediate states of colonizing DTCs. However, how cancer-host interactions evolve during this process needs to be further understood. Most of our current knowledge of the bone microenvironment is obtained through studies looking for the hematopoietic stem cell(HSC) niche. Although this long-standing question has not yet been resolved, our search for the HSC niche has resulted in a detailed map of various cell types in the bone marrow. Furthermore, various techniques used to find the HSC niche may also be adapted for finding the cancer cell niche. In this article, we will review the recent progress in both the DTC and HSC areas with a focus on their potential microenvironment niches. We will also discuss how to apply what we have learned from HSC studies to map DTCs in the bone context. We hope to stimulate thoughts and ideas to further elucidate the bone colonization process, and develop potential therapeutic interventions.展开更多
Dear Editor,Three dimensional(3D)bioprinted extracellular matrix(ECM)can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells(MSCs)differentiation,and then differentiated cells wer...Dear Editor,Three dimensional(3D)bioprinted extracellular matrix(ECM)can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells(MSCs)differentiation,and then differentiated cells were isolated for implantation in vivo using surgical procedures.However,the reduced cell activity after cell isolation from 3D constructs and low cell retention in injured sites limit its application[1].Methacrylated gelatin(GelMA)hydrogel has the advantage of fast crosslinking,which could resemble complex architectures of tissue construct in vivo[2].Here,we adopted a noninvasive bioprinting procedure to imitate the regenerative microenvironment that could simultaneously direct the sweat gland(SG)and vascular differentiation from MSCs and ultimately promote the replacement of glandular tissue in situ(Fig.1a).展开更多
Brain injuries due to trauma or stroke are major causes of adult death and disability.Unfortunately,few interventions are effective for post-injury repair of brain tissue.After a long debate on whether endogenous neur...Brain injuries due to trauma or stroke are major causes of adult death and disability.Unfortunately,few interventions are effective for post-injury repair of brain tissue.After a long debate on whether endogenous neurogenesis actually happens in the adult human brain,there is now substantial evidence to support its occurrence.Although neurogenesis is usually significantly stimulated by injury,the reparative potential of endogenous differentiation from neural stem/progenitor cells is usually insufficient.Alternatively,exogenous stem cell transplantation has shown promising results in animal models,but limitations such as poor long-term survival and inefficient neuronal differentiation make it still challenging for clinical use.Recently,a high focus was placed on glia-to-neuron conversion under single-factor regulation.Despite some inspiring results,the validity of this strategy is still controversial.In this review,we summarize historical findings and recent advances on neurogenesis strategies for neurorepair after brain injury.We also discuss their advantages and drawbacks,as to provide a comprehensive account of their potentials for further studies.展开更多
Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic ins...Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.展开更多
Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a p...Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.展开更多
BACKGROUND Osteoporosis(OP)has become a major public health problem worldwide.Most OP treatments are based on the inhibition of bone resorption,and it is necessary to identify additional treatments aimed at enhancing ...BACKGROUND Osteoporosis(OP)has become a major public health problem worldwide.Most OP treatments are based on the inhibition of bone resorption,and it is necessary to identify additional treatments aimed at enhancing osteogenesis.In the bone marrow(BM)niche,bone mesenchymal stem cells(BMSCs)are exposed to a hypoxic environment.Recently,a few studies have demonstrated that hypoxiainducible factor 2alpha(HIF-2α)is involved in BMSC osteogenic differentiation,but the molecular mechanism involved has not been determined.AIM To investigate the effect of HIF-2αon the osteogenic and adipogenic differentiation of BMSCs and the hematopoietic function of hematopoietic stem cells(HSCs)in the BM niche on the progression of OP.METHODS Mice with BMSC-specific HIF-2αknockout(Prx1-Cre;Hif-2αfl/fl mice)were used for in vivo experiments.Bone quantification was performed on mice of two genotypes with three interventions:Bilateral ovariectomy,semilethal irradiation,and dexamethasone treatment.Moreover,the hematopoietic function of HSCs in the BM niche was compared between the two mouse genotypes.In vitro,the HIF-2αagonist roxadustat and the HIF-2αinhibitor PT2399 were used to investigate the function of HIF-2αin BMSC osteogenic and adipogenic differentiation.Finally,we investigated the effect of HIF-2αon BMSCs via treatment with the mechanistic target of rapamycin(mTOR)agonist MHY1485 and the mTOR inhibitor rapamycin.RESULTS The quantitative index determined by microcomputed tomography indicated that the femoral bone density of Prx1-Cre;Hif-2αfl/fl mice was lower than that of Hif-2αfl/fl mice under the three intervention conditions.In vitro,Hif-2αfl/fl mouse BMSCs were cultured and treated with the HIF-2αagonist roxadustat,and after 7 d of BMSC adipogenic differentiation,the oil red O staining intensity and mRNA expression levels of adipogenesis-related genes in BMSCs treated with roxadustat were decreased;in addition,after 14 d of osteogenic differentiation,BMSCs treated with roxadustat exhibited increased expression of osteogenesis-related genes.The opposite effects were shown for mouse BMSCs treated with the HIF-2αinhibitor PT2399.The mTOR inhibitor rapamycin was used to confirm that HIF-2αregulated BMSC osteogenic and adipogenic differentiation by inhibiting the mTOR pathway.Consequently,there was no significant difference in the hematopoietic function of HSCs between Prx1-Cre;Hif-2αfl/fl and Hif-2αfl/fl mice.CONCLUSION Our study showed that inhibition of HIF-2αdecreases bone mass by inhibiting the osteogenic differentiation and increasing the adipogenic differentiation of BMSCs through inhibition of mTOR signaling in the BM niche.展开更多
Fibroblast growth factor 13(FGF13)is aberrantly expressed in multiple cancer types,suggesting its essential role in tumorigenesis.Hence,we aimed to explore its definite role in the development of acute myeloid leukemi...Fibroblast growth factor 13(FGF13)is aberrantly expressed in multiple cancer types,suggesting its essential role in tumorigenesis.Hence,we aimed to explore its definite role in the development of acute myeloid leukemia(AML)and emphasize its associations with bone marrow niches.Results showed that FGF13 was lowly expressed in patients with AML and that its elevated expression was related to prolonged overall survival(OS).Univariate and multivariate Cox regression analyses identified FGF13 as an independent prognostic factor.A prognostic nomogram integrating FGF13 and clinicopathologic variables was constructed to predict 1-,3-,and 5-year OS.Gene mutation and functional analyses indicated that FGF13 was not associated with AML driver mutations but was related to bone marrow niches.As for immunity,FGF13 was remarkably associated with T cell count,immune checkpoint genes,and cytokines.In addition,FGF13 overexpression substantially inhibited the growth and significantly induced the early apoptosis of AML cells.The xenograft study indicated that FGF13 overexpression prolonged the survival of recipient mice.Overall,FGF13 could serve as an independent prognostic factor for AML,and it was closely related to the bone marrow microenvironment.展开更多
Genetic and epigenetic lesions within hematopoietic cell populations drive diverse hematological malignancies.Myelodysplastic syndromes(MDS)are a group of myeloid neoplasms affecting the hematopoietic stem cells chara...Genetic and epigenetic lesions within hematopoietic cell populations drive diverse hematological malignancies.Myelodysplastic syndromes(MDS)are a group of myeloid neoplasms affecting the hematopoietic stem cells characterized by recurrent genetic abnormalities,myelodysplasia(a pathological definition of abnormal bone marrow structure),ineffective hematopoiesis resulting in blood cytopenia,and a propensity to evolve into acute myelogenous leukemia.Although there is evidence that the accumulation of a set of genetic mutations is an essential event in MDS,there is an increased appreciation of the contribution of specific microenvironments,niches,in the pathogenesis of MDS and response to treatment.In physiologic hematopoiesis,niches are critical functional units that maintain hematopoietic stem and progenitor cells and regulate their maturation into mature blood cells.In MDS and other hematological malignancies,altered bone marrow niches can promote the survival and expansion of mutant hematopoietic clones and provide a shield from therapy.In this review,we focus on our understanding of the composition and function of hematopoietic niches and their role in the evolution of myeloid malignancies,with an emphasis on MDS.展开更多
Background:Sand fly Phlebotomus chinensis is a principle vector for the visceral leishmaniasis(VL)in China with a wide geographic distribution.Jiuzhaigou,Sichuan is a mountain type endemic area of VL in China.Long ter...Background:Sand fly Phlebotomus chinensis is a principle vector for the visceral leishmaniasis(VL)in China with a wide geographic distribution.Jiuzhaigou,Sichuan is a mountain type endemic area of VL in China.Long term effective control efforts in the region have successfully reduced VL transmission.To assess the current status of the sand flies and their ecological aspects in the region,a survey was conducted in the summer of 2014 and 2015.Methods:Sand fly specimens were collected by light traps in a village and blood sources were identified by PCR and sequencing of the mitochondrial cytochrome b gene.Results:In a rock cave,65.2%–79.8%of collected sand flies were male.On a rabbit farm,92.9%–98.8%of specimens were female.In pig pens,61.1%of specimens were female.Some females had visible blood residues.The feeding rate was 49.4%from the pig pens,12.3%from the cave,and only 1.7%from the rabbit farm.Pig,rabbit,chicken,dog,and human blood were detected in the fed specimens.Swine blood,present in all tested samples,was a preferred blood source,while chicken and dog blood were present in a third of the samples.Conclusions:In Jiuzhaigou County,Sichuan Province of China,the considerable sandfly density and the peridomestic feeding behavior all increases the risk of VL transmission,and insecticide spraying in animal sheds could be exploited to reduce sand fly populations in human surroundings.展开更多
Resource depletion exerts opposing pressures on co-occurring consumers to expand diets while limiting overlap with competitors.Using foraging theory as a framework,we tested the effects of prey availability on diet sp...Resource depletion exerts opposing pressures on co-occurring consumers to expand diets while limiting overlap with competitors.Using foraging theory as a framework,we tested the effects of prey availability on diet spe-cialization and overlap among competing Asian predators:dhole,leopard,and tiger.We used scat analysis from a prey-poor site,combined with a quantitative synthesis of 40 other diet studies,to determine biomass of different prey types consumed by each predator.We then assessed diet composition in relation to prey density,and compared diet breadth and overlap between prey-poor and prey-rich sites.In prey rich areas,all three predators specialized on energetically profitable medium and large ungulates(>30 kg),resulting in narrow,overlapping niches.Each predator shifted toward less profitable small-bodied prey(≤30 kg)as preferred ungulates declined,whereas con-sumption of preferred ungulates was unrelated to small prey abundance,as predicted by foraging theory.Diet breadths doubled under prey depletion(except leopard),but overlap declined as diets diverged via species-specific traits that facilitated capture of different types of alternative prey.Asia’s apex predators adapt similarly to depletion of mutually preferred ungulates by switching to more numerous but less profitable small prey.Yet they can also partition a depleted prey base through intrinsic niche differences,thereby avoiding competitive exclusion.Our find-ings illuminate the stabilizing properties of adaptive foraging and niche differences in ecological communities,and provide insights into the behavior and resilience of Asia’s endangered apex predators in response to prey depletion in the heavily poached forests of this region.展开更多
Aims Probabilistic models of species co-occurrences predict aggre-gated intraspecific spatial distributions that might decrease the degree of joint species occurrences and increase community rich-ness.Yet,little is kn...Aims Probabilistic models of species co-occurrences predict aggre-gated intraspecific spatial distributions that might decrease the degree of joint species occurrences and increase community rich-ness.Yet,little is known about the influence of intraspecific aggre-gation on the co-occurrence of species in natural,species-rich communities.Here,we focus on early plant succession and ask how changes in intraspecific aggregation of colonizing plant spe-cies influence the pattern of species co-existence,richness and turnover.Methods We studied the early vegetation succession in a six ha constructed catchment within the abandoned part of a lignite mine in NE Germany.At two spatial scales(1-and 25-m2 plots),we compared for each pair of species the intraspecific degree of aggregation and the pattern of co-occurrence and compared observed rela-tionships with temporal changes in important species functional traits.Important Findings The majority of species occurred in an aggregated manner,particu-larly in the first 2 years of succession.In pairwise comparisons,we found an excess of segregated species occurrences leading to a posi-tive link between intraspecific aggregation and pairwise species seg-regation as predicted by the aggregation hypothesis,particularly at the lower spatial resolution.The degree of intraspecific aggregation was negatively correlated with the community-wide level of species spatial turnover and with plot species richness.Our results are the first direct confirmation that increasing intraspecific aggregation and interspecific competitive interactions counteract in shaping plant community structure during succession.The respective effects of aggregation were strongest at intermediate states of early succession.展开更多
Adult stem cells are responsible for homeostasis and repair of many tissues.Endogenous adult stem cells reside in certain regions of organs,known as the stem cell niche,which is recognized to have an important role in...Adult stem cells are responsible for homeostasis and repair of many tissues.Endogenous adult stem cells reside in certain regions of organs,known as the stem cell niche,which is recognized to have an important role in regulating tissue maintenance and repair.In wound healing and tissue repair,stem cells are mobilized and recruited to the site of wound,and participate in the repair process.Many regulatory factors are involved in the stem cell-based repair process,including stem cell niches and endogenous wound electric fields,which are present at wound tissues and proved to be important in guiding wound healing.Here we briefly review the role of stem cell niches and endogenous electric fields in tissue repair,and hypothesize that endogenous electric fields become part of stem cell niche in the wound site.展开更多
Haematopoietic microenvironmental niches have been described as the‘gatekeepers’for the blood and immune systems.These niches change during ontogeny,with the bone marrow becoming the predominant site of haematopoies...Haematopoietic microenvironmental niches have been described as the‘gatekeepers’for the blood and immune systems.These niches change during ontogeny,with the bone marrow becoming the predominant site of haematopoiesis in post-natal life under steady state conditions.To determine the structure and function of different haematopoietic microenvironmental niches,it is essential to clearly define specific haematopoietic stem and progenitor cell subsets during ontogeny and to understand their temporal appearance and anatomical positioning.A variety of haematopoietic and non-haematopoietic cells contribute to haematopoietic stem and progenitor cell niches.The latter is reported to include endothelial cells and mesenchymal stromal cells(MSCs),skeletal stem cells and/or C-X-C motif chemokine ligand 12-abundant-reticular cell populations,which form crucial components of these microenvironments under homeostatic conditions.Dysregulation or deterioration of such cells contributes to significant clinical disorders and diseases worldwide and is associated with the ageing process.A critical appraisal of these issues and of the roles of MSC/C-X-C motif chemokine ligand 12-abundant-reticular cells and the more recently identified skeletal stem cell subsets in bone marrow haematopoietic niche function under homeostatic conditions and during ageing will form the basis of this research review.In the context of haematopoiesis,clinical translation will deal with lessons learned from the vast experience garnered from the development and use of MSC therapies to treat graft versus host disease in the context of allogeneic haematopoietic transplants,the recent application of these MSC therapies to treating emerging and severe coronavirus disease 2019(COVID-19)infections,and,given that skeletal stem cell ageing is one proposed driver for haematopoietic ageing,the potential contributions of these stem cells to haematopoiesis in healthy bone marrow and the benefits and challenges of using this knowledge for rejuvenating the age-compromised bone marrow haematopoietic niches and restoring haematopoiesis.展开更多
The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relation...The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relationship between plant biodiversity and primary productivity is widely accepted for natural ecosystems, the roles of nutrient resorption and mineralization in mediating that relationship remains largely unknown. Here, we quantified the relative importance of nitrogen(N) resorption and N mineralization in driving plant community N investment and the correlation between species diversity and community productivity along an N-limited successional chronosequence of the mixed broadleaved–Korean pine(Pinus koraiensis) forest in northeastern China. Leaf N resorption efficiency(NRE) at the community level increased significantly along the successional chronosequence,whereas litter N mineralization rate decreased significantly. Leaf NRE was more important than litter N mineralization rate in driving the diversity–productivity relationship. However, higher leaf NRE led to less N mineralization as succession progressed along the chronosequence. Our results highlight the importance of the N resorption pathway rather than the N mineralization pathway for forest N acquisition with community succession,and they provide mechanistic insights into the positive effects of biodiversity on ecosystem functioning. In future forest management practices, we recommend appropriate application of N fertilizer to mitigate the adverse effects of N-poor soil on seedling regeneration during late succession and thus maintain the sustainable development of temperate forest ecosystems.展开更多
The influences of trait diversity(i.e.,the niche complementarity effect)and functional composition(i.e.,the mass ratio effect)on aboveground biomass(AGB)is a highly debated topic in forest ecology.Therefore,further st...The influences of trait diversity(i.e.,the niche complementarity effect)and functional composition(i.e.,the mass ratio effect)on aboveground biomass(AGB)is a highly debated topic in forest ecology.Therefore,further studies are needed to explore these mechanisms in unstudied forest ecosystems to enhance our understanding,and to provide guidelines for specific forest management.Here,we hypothesized that functional composition would drive AGB better than trait diversity and stem size inequality in the(sub-)tropical forests of Nepal.Using data from 101 forest plots,we tested 25 structural equation models(SEMs)to link elevation,stem DBH inequality,trait diversity(i.e.,trait richness,evenness,dispersion and divergence),functional composition[i.e.,community-weighted of maximum height mean(CWM of Hmax),specific leaf area(CWM of SLA),leaf dry matter content(CWM of LDMC),and wood density(CWM of WD)]and AGB.The best-fitted SEMs indicated that CWM of Hmax promoted AGB while overruling the impacts of trait diversity indices on AGB.However,low trait diversity indices were linked with higher AGB while overruling the effects of CWM of SLA,LDMC and WD on AGB.In addition,AGB decreased with increasing elevation,whereas stem size inequality did not influence AGB.Our results suggest that divergent species’functional strategies could shape AGB along an altitudinal gradient in tropical forests.We argue that forest management practices should include plant functional traits in the management plan for the co-benefits of biodiversity conservation and carbon sequestration that underpins human wellbeing.展开更多
基金Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences(2021-I2M-1-013)the National Key Research and Development Program of China(2021YFF0702801,2022YFF0710705)+1 种基金the Special Research Fund for Central Universities,Peking Union Medical College(No.3332022182)Seed Fund for Youth Talent Training Program of Beijing Tongren Hospital Affiliated to Capital Medical University(2020-YJJ-ZZL-034).
文摘The premetastatic niches(PMN)formed by primary tumor-derived molecules regulate distant organs and tissues to further favor tumor colonization.Targeted PMN therapy may prevent tumor metastasis in the early stages,which is becoming increasingly important.At present,there is a lack of in-depth understanding of the cellular and molecular characteristics of the PMN.Here,we summarize current research advances on the cellular and molecular characteristics of the PMN.We emphasize that PMN intervention is a potential therapeutic strategy for early prevention of tumor metastasis,which provides a promising basis for future research and clinical application.
基金This research was supported by the Grants Council of the President of the Russian Federation for Leading Scientific Schools,Grant No.NSh-2495.2020.7Siberian State Medical University Development Program Priority 2030。
文摘Stem cell microterritories(niches),as a specialized part of the extracellular matrix(ECM),are considered an important target and tool for the development of new materials,medical implants,and devices.However,tissue bioengineering products that have stem cell niches of known size on the surface or in the bulk structure of artificial materials are practically unknown.This brief review attempts to draw attention to the problematic aspects of niches as specific parts of the ECM,such as their hierarchy and size for mesenchymal stromal/stem cells(MSCs).These parameters arise directly from numerous definitions of stem cell niches as specialized morphological microterritories found in various tissues.The authors of this review analyze the known information on the hierarchy of MSC microterritories by analogy with that of hematopoietic stem cells.Occasional reports on the size of artificial MSC niches compared to natural niche candidates are summarized.A consensus on a hierarchy and optimal range of niche sizes for MSCs and other stem cells is needed to accelerate the development of prototyping technologies and additive manufacturing in applications to precise tissue bioengineering and regenerative medicine.
基金supported by the National Natural Science Foundation of China(award No:31402101)the“One Belt and One Road”Technical Cooperation Project of Jiangsu Province(award No:BZ2018055)the Jiangsu Agriculture Science and Technology Innovation Fund(award No:CX(19)3023).
文摘Background:Diet has a profound impact on the rumen microbiota,and the impact can vary among the different rumen ecological niches(REN).This study investigated the effects of dietary replacement of soybean meal(SBM)with dried distillers grains with solubles(DDGS)on the rumen microbiota occupying different REN of growing Hu lambs.After a 9-week feeding trial,6 lambs from each dietary treatment(SBM vs.DDGS-based diets)were slaughtered for sample collection.The microbiota of the rumen solid,liquid,and epithelium fractions was examined using amplicon sequencing analysis of bacterial 16S rRNA gene,functional prediction,and qPCR.Results:No interaction of dietary protein source(PS)and REN were detected for virtually all the measurements made in this study.The DDGS substitution resulted in very limited influence on bacterial community structure.However,the metabolic pathways predicted from 16S rRNA gene sequences varied greatly between SBM-and DDGS-based diets.The populations of rumen total bacteria,fungi,sulfate-reducing bacteria(SRB),and methanogens were not influenced by DDGS substitution,but the population of protozoa was reduced.The bacterial communities in rumen solid(RS)and liquid(RL)were similar in taxonomic composition but were different in relative abundance of some taxa.In contrast,the bacterial composition and relative abundance of rumen epithelium(RE)were greatly distinct from those of the RS and the RL.In alignment with the bacterial relative abundance,the metabolic pathways predicted from 16S rRNA genes also varied greatly among the different REN.The populations of total bacteria,protozoa,and methanogens attached to the RE were smaller than those in the RS and RL,and the fungal population on the rumen epitheliumwas smaller than that in the RS but similar to that in the RL.On the contrary,the SRB population on the RE was greater than that in the RS and RL.Conclusions:Substitution of SBM with DDGS had greater impact to the protozoa than to the other microbes,and the microbial community structure and functions at different REN are distinct and niche-adapted.
基金supported by the National Natural Science Foundation of China,No.82171336(to XX)。
文摘Adult neural stem cells are neurogenesis progenitor cells that play an important role in neurogenesis.Therefore,neural regeneration may be a promising target for treatment of many neurological illnesses.The regenerative capacity of adult neural stem cells can be chara cterized by two states:quiescent and active.Quiescent adult neural stem cells are more stable and guarantee the quantity and quality of the adult neural stem cell pool.Active adult neural stem cells are chara cterized by rapid proliferation and differentiation into neurons which allow for integration into neural circuits.This review focuses on diffe rences between quiescent and active adult neural stem cells in nutrition metabolism and protein homeostasis.Furthermore,we discuss the physiological significance and underlying advantages of these diffe rences.Due to the limited number of adult neural stem cells studies,we refe rred to studies of embryonic adult neural stem cells or non-mammalian adult neural stem cells to evaluate specific mechanisms.
基金supported by grants from the Department of Science and Technology of Sichuan Province,Nos.2021ZYD0093(to LY),2022YFS0597(to LY),2021YJ0480(to YT),and 2022ZYD0076(to JY)。
文摘Exosomes are cup-shaped extracellular vesicles with a lipid bilayer that is approximately 30 to 200 nm in thickness.Exosomes are widely distributed in a range of body fluids,including urine,blood,milk,and saliva.Exosomes exert biological function by transporting factors between different cells and by regulating biological pathways in recipient cells.As an important form of intercellular communication,exosomes are increasingly being investigated due to their ability to transfer bioactive molecules such as lipids,proteins,mRNAs,and microRNAs between cells,and because they can regulate physiological and pathological processes in the central nervous system.Adult neurogenesis is a multistage process by which new neurons are generated and migrate to be integrated into existing neuronal circuits.In the adult brain,neurogenesis is mainly localized in two specialized niches:the subventricular zone adjacent to the lateral ventricles and the subgranular zone of the dentate gyrus.An increasing body of evidence indicates that adult neurogenesis is tightly controlled by environmental conditions with the niches.In recent studies,exosomes released from different sources of cells were shown to play an active role in regulating neurogenesis both in vitro and in vivo,thereby participating in the progression of neurodegenerative disorders in patients and in various disease models.Here,we provide a state-of-the-art synopsis of existing research that aimed to identify the diverse components of exosome cargoes and elucidate the therapeutic potential of exosomal contents in the regulation of neurogenesis in several neurodegenerative diseases.We emphasize that exosomal cargoes could serve as a potential biomarker to monitor functional neurogenesis in adults.In addition,exosomes can also be considered as a novel therapeutic approach to treat various neurodegenerative disorders by improving endogenous neurogenesis to mitigate neuronal loss in the central nervous system.
基金supported by the US Department of Defense DAMD W81XWH-16-1-0073 (Era of Hope Scholarship), NCI CA183878Breast Cancer Research Foundation, Susan G. Komen CCR14298445McNair Medical Institute
文摘Breast cancer cells may disseminate early, before tumor diagnosis. Disseminated tumor cells, or DTCs, reside in the bone marrow, and may persist for years or even decades. Some of these cells may be re-activated to resume aggressive growth, and eventually become overt bone metastases. Recent studies have begun to shed light on this complicated process and revealed multiple steps and intermediate states of colonizing DTCs. However, how cancer-host interactions evolve during this process needs to be further understood. Most of our current knowledge of the bone microenvironment is obtained through studies looking for the hematopoietic stem cell(HSC) niche. Although this long-standing question has not yet been resolved, our search for the HSC niche has resulted in a detailed map of various cell types in the bone marrow. Furthermore, various techniques used to find the HSC niche may also be adapted for finding the cancer cell niche. In this article, we will review the recent progress in both the DTC and HSC areas with a focus on their potential microenvironment niches. We will also discuss how to apply what we have learned from HSC studies to map DTCs in the bone context. We hope to stimulate thoughts and ideas to further elucidate the bone colonization process, and develop potential therapeutic interventions.
基金supported by the Science Fund for National Defense Distinguished Young Scholars(2022-JCJQ-ZQ-016)the Key Basic Research Projects of the Foundation Strengthening Plan(2022-JCJQZD-096-00)+2 种基金the National Key Research and Development Program of China(2022YFA1104604)the National Natural Science Foundation of China(32000969)the Key Support Program for Growth Factor Research(SZYZ-TR-03).
文摘Dear Editor,Three dimensional(3D)bioprinted extracellular matrix(ECM)can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells(MSCs)differentiation,and then differentiated cells were isolated for implantation in vivo using surgical procedures.However,the reduced cell activity after cell isolation from 3D constructs and low cell retention in injured sites limit its application[1].Methacrylated gelatin(GelMA)hydrogel has the advantage of fast crosslinking,which could resemble complex architectures of tissue construct in vivo[2].Here,we adopted a noninvasive bioprinting procedure to imitate the regenerative microenvironment that could simultaneously direct the sweat gland(SG)and vascular differentiation from MSCs and ultimately promote the replacement of glandular tissue in situ(Fig.1a).
基金supported by the SIAT Innovation Program for Excellent Young Researchers,No.E1G0241001(to XZ)。
文摘Brain injuries due to trauma or stroke are major causes of adult death and disability.Unfortunately,few interventions are effective for post-injury repair of brain tissue.After a long debate on whether endogenous neurogenesis actually happens in the adult human brain,there is now substantial evidence to support its occurrence.Although neurogenesis is usually significantly stimulated by injury,the reparative potential of endogenous differentiation from neural stem/progenitor cells is usually insufficient.Alternatively,exogenous stem cell transplantation has shown promising results in animal models,but limitations such as poor long-term survival and inefficient neuronal differentiation make it still challenging for clinical use.Recently,a high focus was placed on glia-to-neuron conversion under single-factor regulation.Despite some inspiring results,the validity of this strategy is still controversial.In this review,we summarize historical findings and recent advances on neurogenesis strategies for neurorepair after brain injury.We also discuss their advantages and drawbacks,as to provide a comprehensive account of their potentials for further studies.
文摘Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.
基金supported by the National Key Research and Development Program of China,Nos.2017YFE0122900(to BH),2019YFA0110800(to WL),2019YFA0903802(to YW),2021YFA1101604(to LW),2018YFA0108502(to LF),and 2020YFA0804003(to JW)the National Natural Science Foundation of China,Nos.31621004(to WL,BH)and 31970821(to YW)+1 种基金CAS Project for Young Scientists in Basic Research,No.YSBR-041(to YW)Joint Funds of the National Natural Science Foundation of China,No.U21A20396(to BH)。
文摘Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.
基金Supported by Basic and Applied Basic Research Foundation of Guangdong Province,No.2020A1515010123 and No.2021A1515010695Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province,No.2019A030317011.
文摘BACKGROUND Osteoporosis(OP)has become a major public health problem worldwide.Most OP treatments are based on the inhibition of bone resorption,and it is necessary to identify additional treatments aimed at enhancing osteogenesis.In the bone marrow(BM)niche,bone mesenchymal stem cells(BMSCs)are exposed to a hypoxic environment.Recently,a few studies have demonstrated that hypoxiainducible factor 2alpha(HIF-2α)is involved in BMSC osteogenic differentiation,but the molecular mechanism involved has not been determined.AIM To investigate the effect of HIF-2αon the osteogenic and adipogenic differentiation of BMSCs and the hematopoietic function of hematopoietic stem cells(HSCs)in the BM niche on the progression of OP.METHODS Mice with BMSC-specific HIF-2αknockout(Prx1-Cre;Hif-2αfl/fl mice)were used for in vivo experiments.Bone quantification was performed on mice of two genotypes with three interventions:Bilateral ovariectomy,semilethal irradiation,and dexamethasone treatment.Moreover,the hematopoietic function of HSCs in the BM niche was compared between the two mouse genotypes.In vitro,the HIF-2αagonist roxadustat and the HIF-2αinhibitor PT2399 were used to investigate the function of HIF-2αin BMSC osteogenic and adipogenic differentiation.Finally,we investigated the effect of HIF-2αon BMSCs via treatment with the mechanistic target of rapamycin(mTOR)agonist MHY1485 and the mTOR inhibitor rapamycin.RESULTS The quantitative index determined by microcomputed tomography indicated that the femoral bone density of Prx1-Cre;Hif-2αfl/fl mice was lower than that of Hif-2αfl/fl mice under the three intervention conditions.In vitro,Hif-2αfl/fl mouse BMSCs were cultured and treated with the HIF-2αagonist roxadustat,and after 7 d of BMSC adipogenic differentiation,the oil red O staining intensity and mRNA expression levels of adipogenesis-related genes in BMSCs treated with roxadustat were decreased;in addition,after 14 d of osteogenic differentiation,BMSCs treated with roxadustat exhibited increased expression of osteogenesis-related genes.The opposite effects were shown for mouse BMSCs treated with the HIF-2αinhibitor PT2399.The mTOR inhibitor rapamycin was used to confirm that HIF-2αregulated BMSC osteogenic and adipogenic differentiation by inhibiting the mTOR pathway.Consequently,there was no significant difference in the hematopoietic function of HSCs between Prx1-Cre;Hif-2αfl/fl and Hif-2αfl/fl mice.CONCLUSION Our study showed that inhibition of HIF-2αdecreases bone mass by inhibiting the osteogenic differentiation and increasing the adipogenic differentiation of BMSCs through inhibition of mTOR signaling in the BM niche.
基金supported by the National Key Research and Development Program of China(No.2019YFA0905900).
文摘Fibroblast growth factor 13(FGF13)is aberrantly expressed in multiple cancer types,suggesting its essential role in tumorigenesis.Hence,we aimed to explore its definite role in the development of acute myeloid leukemia(AML)and emphasize its associations with bone marrow niches.Results showed that FGF13 was lowly expressed in patients with AML and that its elevated expression was related to prolonged overall survival(OS).Univariate and multivariate Cox regression analyses identified FGF13 as an independent prognostic factor.A prognostic nomogram integrating FGF13 and clinicopathologic variables was constructed to predict 1-,3-,and 5-year OS.Gene mutation and functional analyses indicated that FGF13 was not associated with AML driver mutations but was related to bone marrow niches.As for immunity,FGF13 was remarkably associated with T cell count,immune checkpoint genes,and cytokines.In addition,FGF13 overexpression substantially inhibited the growth and significantly induced the early apoptosis of AML cells.The xenograft study indicated that FGF13 overexpression prolonged the survival of recipient mice.Overall,FGF13 could serve as an independent prognostic factor for AML,and it was closely related to the bone marrow microenvironment.
基金supported by the Intramural Program of the Center for Cancer Research,National Cancer Institute,National Institutes of Health.
文摘Genetic and epigenetic lesions within hematopoietic cell populations drive diverse hematological malignancies.Myelodysplastic syndromes(MDS)are a group of myeloid neoplasms affecting the hematopoietic stem cells characterized by recurrent genetic abnormalities,myelodysplasia(a pathological definition of abnormal bone marrow structure),ineffective hematopoiesis resulting in blood cytopenia,and a propensity to evolve into acute myelogenous leukemia.Although there is evidence that the accumulation of a set of genetic mutations is an essential event in MDS,there is an increased appreciation of the contribution of specific microenvironments,niches,in the pathogenesis of MDS and response to treatment.In physiologic hematopoiesis,niches are critical functional units that maintain hematopoietic stem and progenitor cells and regulate their maturation into mature blood cells.In MDS and other hematological malignancies,altered bone marrow niches can promote the survival and expansion of mutant hematopoietic clones and provide a shield from therapy.In this review,we focus on our understanding of the composition and function of hematopoietic niches and their role in the evolution of myeloid malignancies,with an emphasis on MDS.
基金supported by the YM’s grant 81371848 from the National Natural Sciences Foundation of ChinaJX’s grants SC1GM109367 from the National Institute Of Allergy And Infectious Diseases of the National Institutes of Health and the DMS-1222592 from National Science Foundation.
文摘Background:Sand fly Phlebotomus chinensis is a principle vector for the visceral leishmaniasis(VL)in China with a wide geographic distribution.Jiuzhaigou,Sichuan is a mountain type endemic area of VL in China.Long term effective control efforts in the region have successfully reduced VL transmission.To assess the current status of the sand flies and their ecological aspects in the region,a survey was conducted in the summer of 2014 and 2015.Methods:Sand fly specimens were collected by light traps in a village and blood sources were identified by PCR and sequencing of the mitochondrial cytochrome b gene.Results:In a rock cave,65.2%–79.8%of collected sand flies were male.On a rabbit farm,92.9%–98.8%of specimens were female.In pig pens,61.1%of specimens were female.Some females had visible blood residues.The feeding rate was 49.4%from the pig pens,12.3%from the cave,and only 1.7%from the rabbit farm.Pig,rabbit,chicken,dog,and human blood were detected in the fed specimens.Swine blood,present in all tested samples,was a preferred blood source,while chicken and dog blood were present in a third of the samples.Conclusions:In Jiuzhaigou County,Sichuan Province of China,the considerable sandfly density and the peridomestic feeding behavior all increases the risk of VL transmission,and insecticide spraying in animal sheds could be exploited to reduce sand fly populations in human surroundings.
基金funded by Fran-cois and Sheila Brutsch,WWF Germany,WWF France,WWF US,WWF Sweden,WWF Denmark,WWF Aus-tria,The Rhino and Tiger Conservation Fund(U.S.Fish and Wildlife Service),and Keidanren Nature Conserva-tion Fund.
文摘Resource depletion exerts opposing pressures on co-occurring consumers to expand diets while limiting overlap with competitors.Using foraging theory as a framework,we tested the effects of prey availability on diet spe-cialization and overlap among competing Asian predators:dhole,leopard,and tiger.We used scat analysis from a prey-poor site,combined with a quantitative synthesis of 40 other diet studies,to determine biomass of different prey types consumed by each predator.We then assessed diet composition in relation to prey density,and compared diet breadth and overlap between prey-poor and prey-rich sites.In prey rich areas,all three predators specialized on energetically profitable medium and large ungulates(>30 kg),resulting in narrow,overlapping niches.Each predator shifted toward less profitable small-bodied prey(≤30 kg)as preferred ungulates declined,whereas con-sumption of preferred ungulates was unrelated to small prey abundance,as predicted by foraging theory.Diet breadths doubled under prey depletion(except leopard),but overlap declined as diets diverged via species-specific traits that facilitated capture of different types of alternative prey.Asia’s apex predators adapt similarly to depletion of mutually preferred ungulates by switching to more numerous but less profitable small prey.Yet they can also partition a depleted prey base through intrinsic niche differences,thereby avoiding competitive exclusion.Our find-ings illuminate the stabilizing properties of adaptive foraging and niche differences in ecological communities,and provide insights into the behavior and resilience of Asia’s endangered apex predators in response to prey depletion in the heavily poached forests of this region.
基金This study was part of the TransRegio Collaborative Research Centre 38(SFB/TR 38:ecosystem assembly and succes-sion),which was financially supported by the Deutsche Forschungsgemeinschaft(DFG,Bonn)and the Brandenburg Ministry of Science,Research and Culture(MWFK,Potsdam)The authors thank the working group Z1(monitoring)mem-bers of the SFB/TR 38,who helped us to perform this study and the Vattenfall Europe Mining AG for providing the re-search site.W.U.acknowledges funding from the Polish National Science Centre(2014/13/B/NZ8/04681)Hazel Pearson kindly improved the language.Conflict of interest statement.None declared.
文摘Aims Probabilistic models of species co-occurrences predict aggre-gated intraspecific spatial distributions that might decrease the degree of joint species occurrences and increase community rich-ness.Yet,little is known about the influence of intraspecific aggre-gation on the co-occurrence of species in natural,species-rich communities.Here,we focus on early plant succession and ask how changes in intraspecific aggregation of colonizing plant spe-cies influence the pattern of species co-existence,richness and turnover.Methods We studied the early vegetation succession in a six ha constructed catchment within the abandoned part of a lignite mine in NE Germany.At two spatial scales(1-and 25-m2 plots),we compared for each pair of species the intraspecific degree of aggregation and the pattern of co-occurrence and compared observed rela-tionships with temporal changes in important species functional traits.Important Findings The majority of species occurred in an aggregated manner,particu-larly in the first 2 years of succession.In pairwise comparisons,we found an excess of segregated species occurrences leading to a posi-tive link between intraspecific aggregation and pairwise species seg-regation as predicted by the aggregation hypothesis,particularly at the lower spatial resolution.The degree of intraspecific aggregation was negatively correlated with the community-wide level of species spatial turnover and with plot species richness.Our results are the first direct confirmation that increasing intraspecific aggregation and interspecific competitive interactions counteract in shaping plant community structure during succession.The respective effects of aggregation were strongest at intermediate states of early succession.
基金This work is supported by Key Program of National Nature Science Foundation of China(81030037)Open Fund of State Key Laboratory of Trauma,Burns and Combined Injury,Third Military Medical University(SKLZZ200804).
文摘Adult stem cells are responsible for homeostasis and repair of many tissues.Endogenous adult stem cells reside in certain regions of organs,known as the stem cell niche,which is recognized to have an important role in regulating tissue maintenance and repair.In wound healing and tissue repair,stem cells are mobilized and recruited to the site of wound,and participate in the repair process.Many regulatory factors are involved in the stem cell-based repair process,including stem cell niches and endogenous wound electric fields,which are present at wound tissues and proved to be important in guiding wound healing.Here we briefly review the role of stem cell niches and endogenous electric fields in tissue repair,and hypothesize that endogenous electric fields become part of stem cell niche in the wound site.
基金I wish to thank the Nuffield Department of Clinical Laboratory Sciences,Radcliffe Department of Medicine,University of Oxford,Oxford,UK,and the Faculty of Health and Medical Sciences,University of Adelaide,and South Australian Health and Medical Research Institute,Adelaide,Australia,for their support.
文摘Haematopoietic microenvironmental niches have been described as the‘gatekeepers’for the blood and immune systems.These niches change during ontogeny,with the bone marrow becoming the predominant site of haematopoiesis in post-natal life under steady state conditions.To determine the structure and function of different haematopoietic microenvironmental niches,it is essential to clearly define specific haematopoietic stem and progenitor cell subsets during ontogeny and to understand their temporal appearance and anatomical positioning.A variety of haematopoietic and non-haematopoietic cells contribute to haematopoietic stem and progenitor cell niches.The latter is reported to include endothelial cells and mesenchymal stromal cells(MSCs),skeletal stem cells and/or C-X-C motif chemokine ligand 12-abundant-reticular cell populations,which form crucial components of these microenvironments under homeostatic conditions.Dysregulation or deterioration of such cells contributes to significant clinical disorders and diseases worldwide and is associated with the ageing process.A critical appraisal of these issues and of the roles of MSC/C-X-C motif chemokine ligand 12-abundant-reticular cells and the more recently identified skeletal stem cell subsets in bone marrow haematopoietic niche function under homeostatic conditions and during ageing will form the basis of this research review.In the context of haematopoiesis,clinical translation will deal with lessons learned from the vast experience garnered from the development and use of MSC therapies to treat graft versus host disease in the context of allogeneic haematopoietic transplants,the recent application of these MSC therapies to treating emerging and severe coronavirus disease 2019(COVID-19)infections,and,given that skeletal stem cell ageing is one proposed driver for haematopoietic ageing,the potential contributions of these stem cells to haematopoiesis in healthy bone marrow and the benefits and challenges of using this knowledge for rejuvenating the age-compromised bone marrow haematopoietic niches and restoring haematopoiesis.
基金financially supported by the National Natural Science Foundation of China(No.32071533)the Fundamental Research Funds for the Central Universities,China(2572020AW13)。
文摘The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relationship between plant biodiversity and primary productivity is widely accepted for natural ecosystems, the roles of nutrient resorption and mineralization in mediating that relationship remains largely unknown. Here, we quantified the relative importance of nitrogen(N) resorption and N mineralization in driving plant community N investment and the correlation between species diversity and community productivity along an N-limited successional chronosequence of the mixed broadleaved–Korean pine(Pinus koraiensis) forest in northeastern China. Leaf N resorption efficiency(NRE) at the community level increased significantly along the successional chronosequence,whereas litter N mineralization rate decreased significantly. Leaf NRE was more important than litter N mineralization rate in driving the diversity–productivity relationship. However, higher leaf NRE led to less N mineralization as succession progressed along the chronosequence. Our results highlight the importance of the N resorption pathway rather than the N mineralization pathway for forest N acquisition with community succession,and they provide mechanistic insights into the positive effects of biodiversity on ecosystem functioning. In future forest management practices, we recommend appropriate application of N fertilizer to mitigate the adverse effects of N-poor soil on seedling regeneration during late succession and thus maintain the sustainable development of temperate forest ecosystems.
基金supported by the Jiangsu Science and Technology Special Project(Grant No.BX2019084)Research Startup Funding at Nanjing Forestry University(Grant No.163010230)the Faculty Startup Funding(to Arshad Ali)for establishing Forest Ecology Research Group at Hebei University(Special Project No.521100221033)。
文摘The influences of trait diversity(i.e.,the niche complementarity effect)and functional composition(i.e.,the mass ratio effect)on aboveground biomass(AGB)is a highly debated topic in forest ecology.Therefore,further studies are needed to explore these mechanisms in unstudied forest ecosystems to enhance our understanding,and to provide guidelines for specific forest management.Here,we hypothesized that functional composition would drive AGB better than trait diversity and stem size inequality in the(sub-)tropical forests of Nepal.Using data from 101 forest plots,we tested 25 structural equation models(SEMs)to link elevation,stem DBH inequality,trait diversity(i.e.,trait richness,evenness,dispersion and divergence),functional composition[i.e.,community-weighted of maximum height mean(CWM of Hmax),specific leaf area(CWM of SLA),leaf dry matter content(CWM of LDMC),and wood density(CWM of WD)]and AGB.The best-fitted SEMs indicated that CWM of Hmax promoted AGB while overruling the impacts of trait diversity indices on AGB.However,low trait diversity indices were linked with higher AGB while overruling the effects of CWM of SLA,LDMC and WD on AGB.In addition,AGB decreased with increasing elevation,whereas stem size inequality did not influence AGB.Our results suggest that divergent species’functional strategies could shape AGB along an altitudinal gradient in tropical forests.We argue that forest management practices should include plant functional traits in the management plan for the co-benefits of biodiversity conservation and carbon sequestration that underpins human wellbeing.
