PDI is a molecular chaperone and plays an important role in Endoplasmic Reticulum quality control (ERQC).PDI participates in the refolding of the misfolded/unfolded proteins to maintain cellular homeostasis under diff...PDI is a molecular chaperone and plays an important role in Endoplasmic Reticulum quality control (ERQC).PDI participates in the refolding of the misfolded/unfolded proteins to maintain cellular homeostasis under differentstresses. However, bioinformatic characteristics and potential functions of PDIs in diatom Phaeodactylumtricornutum (Pt) are still unknown so far. Hence, the genome-wide characteristics of PtPDI proteins in P. tricornutumwere first studied via bioinformatic and transcriptomic methods. 42 PtPDI genes were identified from thegenome of P. tricornutum. The motif, protein structure, classification, number of introns, phylogenetic relationship,and the expression level of 42 PtPDI genes under the tunicamycin stress were analyzed. A pair of tandemduplicated genes (PtPDI15 and PtPDI18) was observed in P. tricornutum. The 42 PtPDIs with different genecharacteristics were divided into three independent clades, indicating different evolutional relationships and functionsof these PtPDIs. The 14 up-regulated PtPDI genes under the tunicamycin treatment might have a positiveeffect on the ER quality control of the unfolded/misfolded proteins, while the 7 down-regulated PtPDIs mightnegatively affect the ERQC. The characteristics of all 42 PtPDIs and their proposed working model here providea comprehensive understanding of the PtPDIs gene family. The differential expression of 21 PtPDIs will be usefulfor further functional study in the ERQC.展开更多
Light regulates important metabolic processes in microalgal cells, which can further impact the metabolism and the accumulation of biomolecules such as lipids, carbohydrates, and proteins. Different characteristics of...Light regulates important metabolic processes in microalgal cells, which can further impact the metabolism and the accumulation of biomolecules such as lipids, carbohydrates, and proteins. Different characteristics of light have been studied on various strains of the model diatom Phaeodactylum tricornutum, but not on transconjugant cells and information on wild-type strains is still limited. Therefore, we studied the impact of different light characteristics such as spectral quality, light intensity and light shift on the growth, and the composition in lipids and fatty acids of P. tricornutum cells to provide a comprehensive context for future applications. Initially, we tested the impact of spectral quality and light intensity on P. tricornutum transformed with an episomal vector (Ptev), harboring the resistance gene Sh ble. Results indicated that Ptev cells accumulated more biomass and overall lipids in spectral quality Red 1 (R1: 34% > 600 nm > 66%) more effectively as compared to Red 2 (R2: 8% > 600 nm > 92%). It was also detected that cell granularity was higher in R1 as compared to R2. Furthermore, by testing two light intensities 65 μmol·m<sup>-2</sup>·s<sup>-1</sup> and 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> light, it was observed that 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> led to an increase in growth trend, total biomass and lipid content. Combining spectral qualities and light intensities, we show that the lipid accumulation raised by 2.8-fold. Studying the light intensity and spectral quality allowed us to optimize the light conditions to R1 spectral quality and light intensity 145 μmol·m<sup>-2</sup>·s<sup>-1</sup>. These initial results showed that red light R1 at 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> was the best condition for biomass and total lipids accumulation in Ptev cells. Next, we further combined these two-light optimizations with a third light characteristics, i.e. light shift, where the cultures were shifted during the early stationary phase to a different light environment. We studied Red light shift (Rs) to investigate how light condition variations impacted P. tricornutum transconjugants Ptev and with an episomal vector containing the reporter gene YFP (PtYFP). We observed that Rs induced growth and fatty acid eicosapentaenoic acid (EPA) in Ptev as compared to PtYFP. Altogether, the study shows that red light shift of R1 at 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> promoted biomass and total lipids accumulation in Ptev and PtYFP cells. The study provides a comprehensive approach to using different light characteristics with the aim to optimize growth and lipids, as well as to fatty acid production.展开更多
Specific bacterial communities interact with phytoplankton in laboratory algal cultures. These communities influence phytoplankton physiology and metabolism by transforming and exchanging phytoplankton-derived organic...Specific bacterial communities interact with phytoplankton in laboratory algal cultures. These communities influence phytoplankton physiology and metabolism by transforming and exchanging phytoplankton-derived organic matter. Functional bacterial groups may participate in various critical nutrients fluxes within these associations, including nitrogen(N) metabolism. However, it is unclear how bacterial communities and the associated algae respond to changes of phycosphere N conditions. This response may have far-reaching implications for global nutrient cycling, algal bloom formation, and ecosystem function. Here, we identified changes in the bacterial communities associated with Phaeodactylum tricornutum when co-cultured with different forms and concentrations of N based on the Illumina HiSeq sequencing of 16 S rRNA amplicons.Phylogenetic analysis identified Proteobacteria and Bacteroidetes as the dominant phyla, accounting for 99.5% of all sequences. Importantly, bacterial abundance and community structure were more affected by algal abundance than by the form or concentration of inorganic N. The relative abundance of three gammaproteobacterial genera(Marinobacter, Algiphilus and Methylophaga) markedly increased in N-deficient cultures. Thus, some bacterial groups may play a role in the regulation of N metabolism when co-cultured with P.tricornutum.展开更多
A bstract Cadmium(Cd) is one of the most common and widespread heavy metals in the environment. Cd has adverse effects on photosynthesis that are countered by photosystem I(PSI) and photosystem II(PSII); however, the ...A bstract Cadmium(Cd) is one of the most common and widespread heavy metals in the environment. Cd has adverse effects on photosynthesis that are countered by photosystem I(PSI) and photosystem II(PSII); however, the protective responses of these photosystems to heavy metal stress remain unclear. Using the model diatom P haeodactylum tricornutum, a biological indicator that is widely used to assess the impact of environmental toxins, we simultaneously measured the effects of Cd on PSI and PSII and examined the levels of pigments in response to high light treatments before and after Cd exposure. Cd significantly reduced the quantum yield and electron transport rates of PSI and PSII. The quantum yield of non-photochemical energy dissipation in PSI due to donor side limitation increased faster than the quantum yield due to acceptor side limitation. The Cd treatment activated the P. tricornutum xanthophyll cycle under artificial light conditions, as indicated by an increased diatoxanthin content. Xanthophyll is important for photoprotection; therefore, the accumulation of diatoxanthin may down-regulate PSII activities to reduce oxidative damage. Together, our results suggest that the rapid reduction in PSII activities following Cd exposure is an adaptive response to heavy metal stress that reflects the variable exposure to external stressors in the native P. tricornutum environment.展开更多
Diatoms are important contributors to global net primary productivity,and play a crucial role in the biogeochemical cycles of carbon,phosphorus,nitrogen,iron,and silicon.Currently in some regions in the ocean,there’s...Diatoms are important contributors to global net primary productivity,and play a crucial role in the biogeochemical cycles of carbon,phosphorus,nitrogen,iron,and silicon.Currently in some regions in the ocean,there’s a trend that carbon content is high while oxygen concentration is low,and the underlying mechanisms of diatoms’response to low oxygen environments are worth investigating.Phaeodactylum tricornutum is a model diatom whose genome has been sequenced;it provides a universal molecular toolbox and a stable transgenic expression system.Therefore,the study of the responses of P.tricornutum to low oxygen has not only fundamental research significance but also important ecologic al significance.In this study,growth rates were determined and proteomic analysis and metabolomic analysis were performed to examine P.tricornutum responses under different oxygen concentrations(2%oxygen concentration for hypoxic condition and 21%oxygen concentration for the normal condition(sterilized air)).Results show that the hypoxic environment inhibited the growth of P.tricornutum.In the hypoxic conditions,P.tricornutum could reset its metabolism pathways,including enhancement in lipid utilization,replenishment of tricarboxylic acid(TCA)cycle through the glyoxylic acid cycle,and down-regulation of photorespiration to reduce energy waste.Additionally,the stress resistance mechanism was activated to facilitate the adaptation to low oxygen conditions.This study helps to reveal the different metabolic changes to hypoxia of diatom from that of higher plants,which might be ascribed to their different habitats and needs further exploration in the future.展开更多
Phaeodactylum tricornutum is a potential livestock for the combined production of eicosapentaenoic acid(EPA) and fucoxanthin. In this study, six marine diatom strains identified as P. tricornutum were cultured and the...Phaeodactylum tricornutum is a potential livestock for the combined production of eicosapentaenoic acid(EPA) and fucoxanthin. In this study, six marine diatom strains identified as P. tricornutum were cultured and their total lipid, fatty acid composition and major photosynthetic pigments determined. It was found that the cell dry weight concentration and mean growth rate ranged between 0.24–0.36 g/L and 0.31–0.33/d, respectively. Among the strains, SCSIO771 presented the highest total lipid content, followed by SCSIO828, and the prominent fatty acids in all strains were C16:0, C16:1, C18:1, and C20:5(EPA). Polyunsaturated fatty acids, including C16:2, C18:2, and EPA, comprised a significant proportion of the total fatty acids. EPA was markedly high in all strains, with the highest in SCSIO828 at 25.65% of total fatty acids. Fucoxanthin was the most abundant pigment in all strains, with the highest in SCSIO828 as well, at 5.50 mg/g. The collective results suggested that strain SCSIO828 could be considered a good candidate for the concurrent production of EPA and fucoxanthin.展开更多
Phaeodactylum tricornutum is one of the important marine diatoms for oceanic primary production. Its reproduction has profound significance in the life cycle; however, the nuclear behavior during its sexual reproducti...Phaeodactylum tricornutum is one of the important marine diatoms for oceanic primary production. Its reproduction has profound significance in the life cycle; however, the nuclear behavior during its sexual reproduction was not clear. In this study, we observed the nuclear transition and determined its correlation with cell conjunction. It was found that two cells jointed at their apices first and swung and aligned each other immediately, and nucleus from one cell was able to transfer into another one during cell conjugation. The cell pairs conjugated for nuclear transition were different from those formed in mitosis in hypovalve thickness and cellular arrangement. Our findings proved the existence of sexual reproduction in P. tricornutum.展开更多
Phaeodactylum tricornutum is a diatom that is rich in lipids.Recently,it has received much attention as a feedstock for biodiesel production.Nitrogen defi ciency is widely known to increase the content of neutral lipi...Phaeodactylum tricornutum is a diatom that is rich in lipids.Recently,it has received much attention as a feedstock for biodiesel production.Nitrogen defi ciency is widely known to increase the content of neutral lipids(mainly triacylglycerides,or TAGs)of microalgae,including P.tricornutum,but the mechanism is unclear.In this study,we deciphered the correlations between TAG content and nine key enzymatic genes involved in lipid synthesis in P.tricornutum.After being cultured under nitrogen-free conditions for 0,4,24,48,72,120,and 168 h,the TAG contents of P.tricornutum cells were assayed and the transcript abundances of the target genes were monitored by quantitative real-time PCR.The results show that the abundances of four target gene transcripts(LACS3,G3PDH2,G3PDH3,and G3PDH5)were positively correlated with TAG content,indicating that these genes may be involved in TAG synthesis in P.tricornutum.The fi ndings improve our understanding of the metabolic network and regulation of lipid synthesis and will guide the future genetic improvement of the TAG content of P.tricornutum.展开更多
Background: Cosmetic formulations, and particularly solar products which contain mineral and chemical UV-filters, are often suspected of causing harmful effects on marine fauna and flora. After the publication of our ...Background: Cosmetic formulations, and particularly solar products which contain mineral and chemical UV-filters, are often suspected of causing harmful effects on marine fauna and flora. After the publication of our work in 2019 concerning the ecotoxicological effects of such formulations on corals (Seriatopora hystrix), we here provide some new information about the biodegradability and the ecotoxicological effects of these products on marine zoo- and phytoplankton. Therefore, we choose to realize in silico and in vitro studies of the biodegradability of several solar products but also to evaluate the ecotoxicological effects of these products on one phytoplankton, i.e. Phaeodactylum tricornutum, and one zooplankton, i.e. Acartia tonsa, of a great importance for sea species survival (notably as sources of food). Materials and methods: Two different approaches were used to study the biodegradability of the tested products: One in silico method and an in vitro one. 2 solar products were involved in the in silico study which consisted in the determination of the degradation factor (DF) of each ingredient of the tested formulas in order to finally obtain their estimated biodegradability percentage. Already available data concerning each ingredient coupled to a computer model developed with one of our partners were used to achieve this study. The in vitro study involved 8 formulas containing UV-filters and was led by following the OECD 301 F guidelines. Ecotoxicological studies of 7 of the formulas containing UV-filters were for their part realized by following the ISO 10253 guidelines for the experiments led with Phaeodactylum tricornutum, and the ISO 14669 guidelines for the experiments led with Acartia tonsa. In these studies, the effect of each tested product on crustaceans’ mortality and algal growth inhibition was assessed. Results: The in silico study predicted that formulas containing chemical UV-filters display a high biodegradability (superior to the threshold value of 60% given by the OECD 301 F guidelines). In the in vitro part of our work, the 8 tested formulas showed a biodegradability slightly inferior to the one predicted in the in silico experiments. Therefore, in order to evaluate if these calculated biodegradability value could have significant harmful effects on zoo- or phytoplankton, we studied the effect of our products regarding the growth inhibition on Phaeodactylum tricornutum and the mortality on Acartia tonsa. In this last part of the study, all the tested products were classified as “non ecotoxic” following an internal classification based on Part 4 entitled “Environmental Hazards” of Globally Harmonized System of Classification and Labelling of Chemicals (GHS), 9<sup>th</sup> edition (2021). Conclusions: These results are notably in line with those published by our teams in 2019 on the effects of solar cosmetic products on corals and seem to confirm that formulas containing mineral and chemical UV-filters can be daily used without displaying significant noxious effects on marine fauna and flora. .展开更多
In this paper,we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can allevia...In this paper,we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can alleviate the toxicity of Cd to P. tricornutum. Short term intracellular uptake and extracellular adsorption experiments using ICP-MS indicated that the amounts of Cd accumulated on the cell surface of P. tricornutum and inside the cell decreased along with the increase of EDTA concentration,which conformed to the prediction of the Free Ion Activity Model (FIAM). However,extracellular adsorption of Cd increased at first and then decreased along with the increase in the concentration of Cys,while intracellular uptake increased under Cys concentrations from the blank value to 4.45 μmol/L,and then tended to remain at the same level when the Cys concentration was greater than 4.45 μmol/L,and this deviated remarkably from the FIAM. The interactions of Cd with _Si_OH,_C_OH and NH2(CO) _OH on the cell wall were confirmed using FT-IR and XPS studies. The results obtained using HPLC of the phytochelatins (PCs) produced by P. tricornutum under CdCl2,Cd_EDTA and Cd_Cys stress suggested that the main reason for the different effects of EDTA and Cys on the bioaccumulation and transformation of Cd by P. tricornutum was that Cys is not only a complexing ligand to Cd,as is EDTA,but also it is a precursor of the intracellular synthesizing PCs participating in the cellular defense mechanism against Cd. Furthermore,the discovery of in vivo PCs and oxidized_PCs as well as Cd-PC2 in P. tricornutum using ESI-IT-MS provided the evidence for deactivation of Cd by the PCs,reducing Cd-toxicity to P. tricornutum.展开更多
The effects of pristine polystyrene microplastics(pMPs)without any pretreatment at different concentrations(0,10,20,50,and 100 mg/L)on Phaeodactylum tricornutum Bohlin at two initial algae densities(105 and 106 cells/...The effects of pristine polystyrene microplastics(pMPs)without any pretreatment at different concentrations(0,10,20,50,and 100 mg/L)on Phaeodactylum tricornutum Bohlin at two initial algae densities(105 and 106 cells/mL)were assessed in this study.Hormesis-like effects were found when microalgae grew with pMPs.The results showed that pMPs inhibited microalgae growth under a high concentration of microplastics tolerated by individual algal cell(low initial algae density)(up to-80.189.71%)but promoted growth when the situation was opposite(up to 15.273.66%).The contents of photosynthetic pigments including chlorophyll a,chlorophyll c and carotenoids showed resistance to pMPs stress under a low initial algae density and increased with time,but the opposite was true under a high initial algae density.Compared with the low initial algae density group,Qp received less inhibition,and NPQ(heat dissipation)also decreased under the high initial algae density.Under the low initial algae density,OJIP parameters such as Sm,N,Area,Pi Abs,ѱo,φEo,TRo/RC and ETo/RC were more perturbed initially and returned to the levels of the control group(without pMPs)over time,but they remained stable throughout the experiment at high initial algae density.These results show that microplastics in the marine environment may have different toxic effects on P.tricornutum at different growth stages,which is of great significance for understanding the impact of microplastics on marine microalgae and aquatic ecosystems.展开更多
Pseudogenes share sequence similarities with functional genes,but in general they have lost their protein-coding ability.The identification of pseudogenes is a very important step in genome annotation.Phaeodactylum tr...Pseudogenes share sequence similarities with functional genes,but in general they have lost their protein-coding ability.The identification of pseudogenes is a very important step in genome annotation.Phaeodactylum tricornutum is a marine diatom that is rich in polyunsaturated fatty acids(PUFAs).The genome of P.tricornutum has been completely sequenced.To identify pseudogenes in P.tricornutum,we developed a pipeline to discover and characterize pseudogenes.We identified a total of 1654 'true' processed pseudogenes,714 duplicated pseudogenes and 4729 pseudogene fragments.The results of the bioinformatics analysis indicated that the genome sequence of P.tricornutum contained many pseudogenes and pseudogene fragments.展开更多
基金the funding of Educational and Scientific Research Projects for Young and Middle-Aged Teachers in Fujian Province(Grant Number:2022JAT220693)Natural Science Foundation of Guangdong Province(Grant Number:2022A1515012141)+2 种基金the Program for University Innovation Team of Guangdong Province(Grant Number:2022KCXTD008)National Natural Science Foundation of China(92158201 and 42376001)the Innovation and Entrepreneurship Project of Shantou(201112176541391).
文摘PDI is a molecular chaperone and plays an important role in Endoplasmic Reticulum quality control (ERQC).PDI participates in the refolding of the misfolded/unfolded proteins to maintain cellular homeostasis under differentstresses. However, bioinformatic characteristics and potential functions of PDIs in diatom Phaeodactylumtricornutum (Pt) are still unknown so far. Hence, the genome-wide characteristics of PtPDI proteins in P. tricornutumwere first studied via bioinformatic and transcriptomic methods. 42 PtPDI genes were identified from thegenome of P. tricornutum. The motif, protein structure, classification, number of introns, phylogenetic relationship,and the expression level of 42 PtPDI genes under the tunicamycin stress were analyzed. A pair of tandemduplicated genes (PtPDI15 and PtPDI18) was observed in P. tricornutum. The 42 PtPDIs with different genecharacteristics were divided into three independent clades, indicating different evolutional relationships and functionsof these PtPDIs. The 14 up-regulated PtPDI genes under the tunicamycin treatment might have a positiveeffect on the ER quality control of the unfolded/misfolded proteins, while the 7 down-regulated PtPDIs mightnegatively affect the ERQC. The characteristics of all 42 PtPDIs and their proposed working model here providea comprehensive understanding of the PtPDIs gene family. The differential expression of 21 PtPDIs will be usefulfor further functional study in the ERQC.
文摘Light regulates important metabolic processes in microalgal cells, which can further impact the metabolism and the accumulation of biomolecules such as lipids, carbohydrates, and proteins. Different characteristics of light have been studied on various strains of the model diatom Phaeodactylum tricornutum, but not on transconjugant cells and information on wild-type strains is still limited. Therefore, we studied the impact of different light characteristics such as spectral quality, light intensity and light shift on the growth, and the composition in lipids and fatty acids of P. tricornutum cells to provide a comprehensive context for future applications. Initially, we tested the impact of spectral quality and light intensity on P. tricornutum transformed with an episomal vector (Ptev), harboring the resistance gene Sh ble. Results indicated that Ptev cells accumulated more biomass and overall lipids in spectral quality Red 1 (R1: 34% > 600 nm > 66%) more effectively as compared to Red 2 (R2: 8% > 600 nm > 92%). It was also detected that cell granularity was higher in R1 as compared to R2. Furthermore, by testing two light intensities 65 μmol·m<sup>-2</sup>·s<sup>-1</sup> and 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> light, it was observed that 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> led to an increase in growth trend, total biomass and lipid content. Combining spectral qualities and light intensities, we show that the lipid accumulation raised by 2.8-fold. Studying the light intensity and spectral quality allowed us to optimize the light conditions to R1 spectral quality and light intensity 145 μmol·m<sup>-2</sup>·s<sup>-1</sup>. These initial results showed that red light R1 at 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> was the best condition for biomass and total lipids accumulation in Ptev cells. Next, we further combined these two-light optimizations with a third light characteristics, i.e. light shift, where the cultures were shifted during the early stationary phase to a different light environment. We studied Red light shift (Rs) to investigate how light condition variations impacted P. tricornutum transconjugants Ptev and with an episomal vector containing the reporter gene YFP (PtYFP). We observed that Rs induced growth and fatty acid eicosapentaenoic acid (EPA) in Ptev as compared to PtYFP. Altogether, the study shows that red light shift of R1 at 145 μmol·m<sup>-2</sup>·s<sup>-1</sup> promoted biomass and total lipids accumulation in Ptev and PtYFP cells. The study provides a comprehensive approach to using different light characteristics with the aim to optimize growth and lipids, as well as to fatty acid production.
基金The National Natural Science Foundation of China(NSFC)under contract No.31470536the National Key Research and Development Program of China under contract No.2018YFC1406403
文摘Specific bacterial communities interact with phytoplankton in laboratory algal cultures. These communities influence phytoplankton physiology and metabolism by transforming and exchanging phytoplankton-derived organic matter. Functional bacterial groups may participate in various critical nutrients fluxes within these associations, including nitrogen(N) metabolism. However, it is unclear how bacterial communities and the associated algae respond to changes of phycosphere N conditions. This response may have far-reaching implications for global nutrient cycling, algal bloom formation, and ecosystem function. Here, we identified changes in the bacterial communities associated with Phaeodactylum tricornutum when co-cultured with different forms and concentrations of N based on the Illumina HiSeq sequencing of 16 S rRNA amplicons.Phylogenetic analysis identified Proteobacteria and Bacteroidetes as the dominant phyla, accounting for 99.5% of all sequences. Importantly, bacterial abundance and community structure were more affected by algal abundance than by the form or concentration of inorganic N. The relative abundance of three gammaproteobacterial genera(Marinobacter, Algiphilus and Methylophaga) markedly increased in N-deficient cultures. Thus, some bacterial groups may play a role in the regulation of N metabolism when co-cultured with P.tricornutum.
基金Supported by the National Natural Science Foundation of China(No.41506172)the International S&T Cooperation Program of China(No.2015DFG32160)
文摘A bstract Cadmium(Cd) is one of the most common and widespread heavy metals in the environment. Cd has adverse effects on photosynthesis that are countered by photosystem I(PSI) and photosystem II(PSII); however, the protective responses of these photosystems to heavy metal stress remain unclear. Using the model diatom P haeodactylum tricornutum, a biological indicator that is widely used to assess the impact of environmental toxins, we simultaneously measured the effects of Cd on PSI and PSII and examined the levels of pigments in response to high light treatments before and after Cd exposure. Cd significantly reduced the quantum yield and electron transport rates of PSI and PSII. The quantum yield of non-photochemical energy dissipation in PSI due to donor side limitation increased faster than the quantum yield due to acceptor side limitation. The Cd treatment activated the P. tricornutum xanthophyll cycle under artificial light conditions, as indicated by an increased diatoxanthin content. Xanthophyll is important for photoprotection; therefore, the accumulation of diatoxanthin may down-regulate PSII activities to reduce oxidative damage. Together, our results suggest that the rapid reduction in PSII activities following Cd exposure is an adaptive response to heavy metal stress that reflects the variable exposure to external stressors in the native P. tricornutum environment.
基金Supported by the National Natural Science Foundation of China(Nos.41876158,31770024)the Natural Science Foundation of Hainan Province(No.420QN219)+3 种基金the Biology and Biochemistry ESI Cultivation Discipline Open Project of Qilu University of Technology(No.ESIBBC202004)the Innovation and Development Joint Fund of Natural Science Foundation from Shandong Province(No.ZR2021LSW022)the Young Taishan Scholarship to Xuekui XIA(No.tsqn202103100)the Start-up Fund Project of Hainan University(No.KYQD(ZR)20060)。
文摘Diatoms are important contributors to global net primary productivity,and play a crucial role in the biogeochemical cycles of carbon,phosphorus,nitrogen,iron,and silicon.Currently in some regions in the ocean,there’s a trend that carbon content is high while oxygen concentration is low,and the underlying mechanisms of diatoms’response to low oxygen environments are worth investigating.Phaeodactylum tricornutum is a model diatom whose genome has been sequenced;it provides a universal molecular toolbox and a stable transgenic expression system.Therefore,the study of the responses of P.tricornutum to low oxygen has not only fundamental research significance but also important ecologic al significance.In this study,growth rates were determined and proteomic analysis and metabolomic analysis were performed to examine P.tricornutum responses under different oxygen concentrations(2%oxygen concentration for hypoxic condition and 21%oxygen concentration for the normal condition(sterilized air)).Results show that the hypoxic environment inhibited the growth of P.tricornutum.In the hypoxic conditions,P.tricornutum could reset its metabolism pathways,including enhancement in lipid utilization,replenishment of tricarboxylic acid(TCA)cycle through the glyoxylic acid cycle,and down-regulation of photorespiration to reduce energy waste.Additionally,the stress resistance mechanism was activated to facilitate the adaptation to low oxygen conditions.This study helps to reveal the different metabolic changes to hypoxia of diatom from that of higher plants,which might be ascribed to their different habitats and needs further exploration in the future.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences(No.SQ201213)the National Natural Science Foundation of China(No.31402320)+1 种基金the Guangdong Province and Chinese Academy of Science Cooperation Foundation(No.2012B091100268)the Technology Project of Ocean and Fisheries of Guangdong Province(No.A201101I04)
文摘Phaeodactylum tricornutum is a potential livestock for the combined production of eicosapentaenoic acid(EPA) and fucoxanthin. In this study, six marine diatom strains identified as P. tricornutum were cultured and their total lipid, fatty acid composition and major photosynthetic pigments determined. It was found that the cell dry weight concentration and mean growth rate ranged between 0.24–0.36 g/L and 0.31–0.33/d, respectively. Among the strains, SCSIO771 presented the highest total lipid content, followed by SCSIO828, and the prominent fatty acids in all strains were C16:0, C16:1, C18:1, and C20:5(EPA). Polyunsaturated fatty acids, including C16:2, C18:2, and EPA, comprised a significant proportion of the total fatty acids. EPA was markedly high in all strains, with the highest in SCSIO828 at 25.65% of total fatty acids. Fucoxanthin was the most abundant pigment in all strains, with the highest in SCSIO828 as well, at 5.50 mg/g. The collective results suggested that strain SCSIO828 could be considered a good candidate for the concurrent production of EPA and fucoxanthin.
基金supported by the State Basic Research and Development Program of China (973 Program) (2011-CB200901)the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province(BS2010SW037)the Opening Research Project of Experimental Marine Biology Laboratory,Institute of Oceanology,Chinese Academy of Sciences
文摘Phaeodactylum tricornutum is one of the important marine diatoms for oceanic primary production. Its reproduction has profound significance in the life cycle; however, the nuclear behavior during its sexual reproduction was not clear. In this study, we observed the nuclear transition and determined its correlation with cell conjunction. It was found that two cells jointed at their apices first and swung and aligned each other immediately, and nucleus from one cell was able to transfer into another one during cell conjugation. The cell pairs conjugated for nuclear transition were different from those formed in mitosis in hypovalve thickness and cellular arrangement. Our findings proved the existence of sexual reproduction in P. tricornutum.
基金Supported by the National Basic Research Program of China(973 Program)(No.2011CB200901)the National Key Technology Research and Development Program(No.2011BAD14B01)+1 种基金the Promotive Research Fund for Excellent Young and Middle-Aged Scientists of Shandong Province(No.BS2010SW037)the National Natural Science Foundation of China(No.31270408)
文摘Phaeodactylum tricornutum is a diatom that is rich in lipids.Recently,it has received much attention as a feedstock for biodiesel production.Nitrogen defi ciency is widely known to increase the content of neutral lipids(mainly triacylglycerides,or TAGs)of microalgae,including P.tricornutum,but the mechanism is unclear.In this study,we deciphered the correlations between TAG content and nine key enzymatic genes involved in lipid synthesis in P.tricornutum.After being cultured under nitrogen-free conditions for 0,4,24,48,72,120,and 168 h,the TAG contents of P.tricornutum cells were assayed and the transcript abundances of the target genes were monitored by quantitative real-time PCR.The results show that the abundances of four target gene transcripts(LACS3,G3PDH2,G3PDH3,and G3PDH5)were positively correlated with TAG content,indicating that these genes may be involved in TAG synthesis in P.tricornutum.The fi ndings improve our understanding of the metabolic network and regulation of lipid synthesis and will guide the future genetic improvement of the TAG content of P.tricornutum.
文摘Background: Cosmetic formulations, and particularly solar products which contain mineral and chemical UV-filters, are often suspected of causing harmful effects on marine fauna and flora. After the publication of our work in 2019 concerning the ecotoxicological effects of such formulations on corals (Seriatopora hystrix), we here provide some new information about the biodegradability and the ecotoxicological effects of these products on marine zoo- and phytoplankton. Therefore, we choose to realize in silico and in vitro studies of the biodegradability of several solar products but also to evaluate the ecotoxicological effects of these products on one phytoplankton, i.e. Phaeodactylum tricornutum, and one zooplankton, i.e. Acartia tonsa, of a great importance for sea species survival (notably as sources of food). Materials and methods: Two different approaches were used to study the biodegradability of the tested products: One in silico method and an in vitro one. 2 solar products were involved in the in silico study which consisted in the determination of the degradation factor (DF) of each ingredient of the tested formulas in order to finally obtain their estimated biodegradability percentage. Already available data concerning each ingredient coupled to a computer model developed with one of our partners were used to achieve this study. The in vitro study involved 8 formulas containing UV-filters and was led by following the OECD 301 F guidelines. Ecotoxicological studies of 7 of the formulas containing UV-filters were for their part realized by following the ISO 10253 guidelines for the experiments led with Phaeodactylum tricornutum, and the ISO 14669 guidelines for the experiments led with Acartia tonsa. In these studies, the effect of each tested product on crustaceans’ mortality and algal growth inhibition was assessed. Results: The in silico study predicted that formulas containing chemical UV-filters display a high biodegradability (superior to the threshold value of 60% given by the OECD 301 F guidelines). In the in vitro part of our work, the 8 tested formulas showed a biodegradability slightly inferior to the one predicted in the in silico experiments. Therefore, in order to evaluate if these calculated biodegradability value could have significant harmful effects on zoo- or phytoplankton, we studied the effect of our products regarding the growth inhibition on Phaeodactylum tricornutum and the mortality on Acartia tonsa. In this last part of the study, all the tested products were classified as “non ecotoxic” following an internal classification based on Part 4 entitled “Environmental Hazards” of Globally Harmonized System of Classification and Labelling of Chemicals (GHS), 9<sup>th</sup> edition (2021). Conclusions: These results are notably in line with those published by our teams in 2019 on the effects of solar cosmetic products on corals and seem to confirm that formulas containing mineral and chemical UV-filters can be daily used without displaying significant noxious effects on marine fauna and flora. .
文摘In this paper,we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can alleviate the toxicity of Cd to P. tricornutum. Short term intracellular uptake and extracellular adsorption experiments using ICP-MS indicated that the amounts of Cd accumulated on the cell surface of P. tricornutum and inside the cell decreased along with the increase of EDTA concentration,which conformed to the prediction of the Free Ion Activity Model (FIAM). However,extracellular adsorption of Cd increased at first and then decreased along with the increase in the concentration of Cys,while intracellular uptake increased under Cys concentrations from the blank value to 4.45 μmol/L,and then tended to remain at the same level when the Cys concentration was greater than 4.45 μmol/L,and this deviated remarkably from the FIAM. The interactions of Cd with _Si_OH,_C_OH and NH2(CO) _OH on the cell wall were confirmed using FT-IR and XPS studies. The results obtained using HPLC of the phytochelatins (PCs) produced by P. tricornutum under CdCl2,Cd_EDTA and Cd_Cys stress suggested that the main reason for the different effects of EDTA and Cys on the bioaccumulation and transformation of Cd by P. tricornutum was that Cys is not only a complexing ligand to Cd,as is EDTA,but also it is a precursor of the intracellular synthesizing PCs participating in the cellular defense mechanism against Cd. Furthermore,the discovery of in vivo PCs and oxidized_PCs as well as Cd-PC2 in P. tricornutum using ESI-IT-MS provided the evidence for deactivation of Cd by the PCs,reducing Cd-toxicity to P. tricornutum.
基金This study was supported by the National Natural Science Foundation of China(No.52071030)Science and Technology Program of Henan Province(No.132102310498).
文摘The effects of pristine polystyrene microplastics(pMPs)without any pretreatment at different concentrations(0,10,20,50,and 100 mg/L)on Phaeodactylum tricornutum Bohlin at two initial algae densities(105 and 106 cells/mL)were assessed in this study.Hormesis-like effects were found when microalgae grew with pMPs.The results showed that pMPs inhibited microalgae growth under a high concentration of microplastics tolerated by individual algal cell(low initial algae density)(up to-80.189.71%)but promoted growth when the situation was opposite(up to 15.273.66%).The contents of photosynthetic pigments including chlorophyll a,chlorophyll c and carotenoids showed resistance to pMPs stress under a low initial algae density and increased with time,but the opposite was true under a high initial algae density.Compared with the low initial algae density group,Qp received less inhibition,and NPQ(heat dissipation)also decreased under the high initial algae density.Under the low initial algae density,OJIP parameters such as Sm,N,Area,Pi Abs,ѱo,φEo,TRo/RC and ETo/RC were more perturbed initially and returned to the levels of the control group(without pMPs)over time,but they remained stable throughout the experiment at high initial algae density.These results show that microplastics in the marine environment may have different toxic effects on P.tricornutum at different growth stages,which is of great significance for understanding the impact of microplastics on marine microalgae and aquatic ecosystems.
基金supported by the National Basic Projects for Science and Technology (SQ2012FY4910019-1)the Nonprofit Research Project for the State Oceanic Administration (201105008-2)the National Natural Science Foundation of China (41176137)
文摘Pseudogenes share sequence similarities with functional genes,but in general they have lost their protein-coding ability.The identification of pseudogenes is a very important step in genome annotation.Phaeodactylum tricornutum is a marine diatom that is rich in polyunsaturated fatty acids(PUFAs).The genome of P.tricornutum has been completely sequenced.To identify pseudogenes in P.tricornutum,we developed a pipeline to discover and characterize pseudogenes.We identified a total of 1654 'true' processed pseudogenes,714 duplicated pseudogenes and 4729 pseudogene fragments.The results of the bioinformatics analysis indicated that the genome sequence of P.tricornutum contained many pseudogenes and pseudogene fragments.
