[Objectives]To study the phosphorus removal performance of phosphate accumulating organisms(PAOs).[Methods]Activated sludge from domestic sewage treatment plant was used as the strain source,and phosphate accumulating...[Objectives]To study the phosphorus removal performance of phosphate accumulating organisms(PAOs).[Methods]Activated sludge from domestic sewage treatment plant was used as the strain source,and phosphate accumulating organisms were screened by plate streaking method and dilution coating plate method.Six kinds of excellent phosphate accumulating organisms were obtained by metachromatic granule staining experiment,total phosphorus experiment and simulated sewage phosphorus removal experiment to assist the observation of bac-terial morphology and experiment of phosphorus removal capacity.In addition,the influencing factors of phosphorus removal capacity(nitrogen source,trace metal ions)were analyzed.[Results]In the case of simulated sewage,the phosphorus removal rate of strain b was the highest,reaching 66.25%,while the phosphorus removal rate of strain e and f was about 10%lower than that of the phosphorus uptake experiment.[Conclusions]This study is expected to provide a theoretical reference for the gradual optimization of the screening method of phosphorus re-moval bacteria in domestic sewage treatment.展开更多
A better understanding of genetic bases of growth regulation is essential for bivalve breeding,which is helpful to improve the yield of the commercially important bivalves.While previous studies have identified some c...A better understanding of genetic bases of growth regulation is essential for bivalve breeding,which is helpful to improve the yield of the commercially important bivalves.While previous studies have identified some candidate genes accounting for variation in growth-related traits through genotype-phenotype association analyses,seldom of them have verified the functions of these putative,growth-related genes beyond the genomic level due to the difficulty of culturing commercial bivalves under laboratory conditions.Fortunately,dwarf surf clam Mulinia lateralis can serve as a model organism for studying marine bivalves given its short generation time,the feasibility of being grown under experimental conditions and the availability of genetic and biological information.Using dwarf surf clam as a model bivalve,we characterize E2F3,a gene that has been found to account for variation in growth in scallops by a previous genome-wide association study,and verify its function in growth regulation through RNA interference(RNAi)experiments.For the first time,E2F3 in dwarf surf clam,which is termed as MulE2F3,is characterized.The results reveal that dwarf surf clams with MulE2F3 knocked down exhibit a reduction in both shell size and soft-tissue weight,indicating the functions of MulE2F3 in positively regulating bivalve growth.More importantly,we demonstrate how dwarf surf clam can be used as a model organism to investigate gene functions in commercial bivalves,shedding light on genetic causes for variation in growth to enhance the efficiency of bivalve farming.展开更多
This study explored the concurrent scheduling of machines, tools, and tool transporter(TT) with alternative machines in a multi-machine flexible manufacturing system(FMS), taking into mind the tool transfer durations ...This study explored the concurrent scheduling of machines, tools, and tool transporter(TT) with alternative machines in a multi-machine flexible manufacturing system(FMS), taking into mind the tool transfer durations for minimization of the makespan(MSN). When tools are expensive, just a single copy of every tool kind is made available for use in the FMS system. Because the tools are housed in a central tool magazine(CTM), which then distributes and delivers them to many machines, because there is no longer a need to duplicate the tools in each machine, the associated costs are avoided. Choosing alternative machines for job operations(jb-ons), assigning tools to jb-ons, sequencing jb-ons on machines, and arranging allied trip activities, together with the TT’s loaded trip times and deadheading periods, are all challenges that must be overcome to achieve the goal of minimizing MSN. In addition to a mixed nonlinear integer programming(MNLIP) formulation for this simultaneous scheduling problem, this paper suggests a symbiotic organisms search algorithm(SOSA) for the problem’s solution. This algorithm relies on organisms’ symbiotic interaction strategies to keep living in an ecosystem. The findings demonstrate that SOSA is superior to the Jaya algorithm in providing solutions and that using alternative machines for operations helps bring down MSN.展开更多
Background:Coronavirus disease 2019(COVID-19)has now spread to most countries and regions of the world.Risk factors associated with multi-drug resistant organism(MDRO)infections in patients with COVID-19 have not been...Background:Coronavirus disease 2019(COVID-19)has now spread to most countries and regions of the world.Risk factors associated with multi-drug resistant organism(MDRO)infections in patients with COVID-19 have not been well studied yet.In the present study,we aimed to identify the risk factors associated with the MDRO infections and their impact on in-hospital mortality of COVID-19 patients.Methods:This retrospective cohort study was conducted between December 2019 and April 2020 at two tertiary hospitals in Wuhan,China.Data of cases were collected through electronic medical records system.This study was focused on cases with bacterial culture records.Risk factors and outcomes associated with MDRO infections were analyzed using logistic regression model.Results:Of the 2891 patients,370 patients have bacterial culture results,and MDROs were isolated in 38 patients.Respiratory tract infections(67.3%)were the most common hospital acquired infections.Variables independently associated with MDRO infections were dyspnea at admission(odds ratio(OR)4.74;95%confidence interval(CI)2.06-10.88;P<0.001),intensive care unit(ICU)admission(OR 5.02;95%CI 1.99-12.63;P<0.01),and invasive mechanical ventilation(OR 5.13;95%CI 2.15-12.27;P<0.001),adjusted for age and gender.MDROs infection was also a significant risk factor of death for the patients,adjusted for age,gender,severity of illness,ICU admission and mechanical ventilation(OR 1.12,95%CI:0.43-2.96,P=0.817).Conclusion:In our study,dyspnea at admission,ICU admission and invasive mechanical ventilation were associated with the presence of MDRO infections,and clinicians should be alert in MDRO infections in COVID-19 hospitalized patients.展开更多
The pervasive presence of microplastics in marine environments has raised significant concerns. This review addresses the pressing issue of microplastic pollution in marine ecosystems and its potential implications fo...The pervasive presence of microplastics in marine environments has raised significant concerns. This review addresses the pressing issue of microplastic pollution in marine ecosystems and its potential implications for both the environment and human health. It outlines the current state of microplastic occurrence, distribution, and extraction methods within marine organisms. Microplastics have emerged as a significant environmental concern due to their harmful effects on ecosystems and their potential human health risks. These particles infiltrate marine environments through runoff and atmospheric deposition, ultimately contaminating beaches and posing threats to marine life. Despite the gravity of this issue, there has been limited research on the presence and distribution of microplastics in marine organisms. This review aims to bridge this knowledge gap by comprehensively examining the occurrence, distribution, and various extraction methods used to detect microplastics in marine organisms. It emphasizes the urgent need for targeted measures to manage microplastic pollution, highlights the significant role of human activities in contributing to this problem, and underscores the importance of reducing human-induced pollution to safeguard marine ecosystems. While this paper contributes to the understanding of microplastic pollution in marine environments and underscores the critical importance of taking action to protect marine organisms and preserve our oceans for future generations, it also emphasizes that, in effectively tackling the microplastic problem, a well-coordinated approach is essential, involving research initiatives, policy adjustments, public involvement, and innovative technologies. Crucially, prompt and resolute responses must exist to counteract the escalating peril posed by microplastics to the oceans and the global environment.展开更多
The abattoir is one of the important sectors in the food industry, therefore the need for close monitoring of everything concerning it to minimize microbial contamination. The aim of the study is to identify bacteria ...The abattoir is one of the important sectors in the food industry, therefore the need for close monitoring of everything concerning it to minimize microbial contamination. The aim of the study is to identify bacteria listed as WHO priority organisms associated with meat from Kwata abattoir in Awka, Anambra state. The study was carried out over a three (3) months period from September to December 2022. Thirteen samples were collected from the floor, table, water, meat, knife and soil in the abattoir. The samples were cultured using streak and spread plate methods on MacConkey and Cetrimide agar. The isolates were identified with the following biochemical tests: catalase, oxidase, citrate and indole tests. Ampiclox levofloxacin, gentamicin, ofloxacin impenem ceftraixone, cefixime, cefuroxime and nitrofurantoin were used for sensitivity test following Kirby Bauer disc diffusion method and biofilm formation was determined using the tube method. The 75 isolates obtained were identified as follows;29.3% E. coli, 26.7% Klebsiella spp., 16% Proteus spp., and 28% Pseudomonas spp. The result of antibiotics sensitivity test interpreted using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints showed that (98%) of the isolates were resistant to the antibiotics used. Test for biofilm formation with 52 isolates showed 31 strong, 12 moderate and 9 weak biofilm formers. The result of this study confirms the presence of bacteria contaminants within the WHO priority list in the abattoir, as such there is need for improved handling of animals. Slaughtering, cleaning and distribution of meat should be done using aseptic procedures. .展开更多
Objective:To determine the clinical distribution of multi-drug resistant organism(MDRO)in Jiangyan Hospital and the monitoring and warning of drug-resistance bacteria to provide an important basis for guiding the appl...Objective:To determine the clinical distribution of multi-drug resistant organism(MDRO)in Jiangyan Hospital and the monitoring and warning of drug-resistance bacteria to provide an important basis for guiding the application of broad-spectrum antibiotics in clinical treatment and reducing the occurrence of nosocomial infection.Methods:Retrospective screening and analysis were conducted on the pathogenic strains of hospitalized patients in our hospital in 2022.Results:A total of 2,769 strains of pathogenic bacteria and 390 strains of MDRO were detected and isolated in our hospital in 2022;the detection rate of MDRO was 14.08%.A total of 516 strains(18.64%)Klebsiella pneumoniae(KP)and 62 strains(12.02%)of carbapenem-resistant Klebsiella pneumoniae(CR-KP)were detected;436 strains(15.75%)of Escherichia coli(ECO)were detected,including 8 strains(1.83%)of CR-ECO;342 strains(12.35%)of Pseudomonas aeruginosa(PA)and 116 strains(33.92%)of CR-PA were detected;there were 194 strains(7.01%)of Acinetobacter baumannii(AB),among which 125 strains(64.43%)were CR-AB;there were 291 strains(10.51%)of Staphylococcus aureus,among which 79 strains(27.15%)of methicillin-resistant Staphylococcus aureus(MRSA)were detected;78 strains(2.82%)of Enterococcus faecalis were detected,and vancomycin-resistant enterococcus(VRE)was not detected.The first five MDROs were CR-AB,CR-PA,MRSA,CR-KP,and CR-ECO.The top five departments with the highest MDRO detection rate in 2022 were the ICU(37.44%),the Pulmonology Department(ward 13;31.03%),the Department of Rehabilitation(ward 5;6.67%),the Department of Neurosurgery(ward 11;4.62%),and the Department of General Surgery(ward 10;3.59 The resistance rate of antibacterial drugs is divided into four levels for early warning:30%to 40%,41%to 50%,51%to 75%,and 75%or more.Conclusion:Our hospital should strengthen the monitoring of antimicrobial resistance warning related to MDRO and the abuse of antimicrobial drugs.Based on the results of drug sensitivity and antimicrobial resistance warning,the use of antibiotics should be standardized in clinical practice to reduce nosocomial infection。展开更多
In the Niger Delta region of Nigeria, oil explorations and exploitations abound, causing environmental pollution with serious consequences on soil ecosystem and its biodiversity. In spite of the relationship between m...In the Niger Delta region of Nigeria, oil explorations and exploitations abound, causing environmental pollution with serious consequences on soil ecosystem and its biodiversity. In spite of the relationship between microbes and fauna in soil ecosystem, such that both organisms can metabolize certain range of petroleum hydrocarbon substrates with the fauna influencing the remediation potentials of bacteria, yet soil fauna is still not fully considered in bioremediation. The influence of earthworm;Lumbricus terrestris on the remediating potentials of soil bacteria in petroleum hydrocarbon contaminated soils was investigated. Eighteen pots were filled with 700 g of soil each, with nine treated with mixture of 3 levels crude oil and remediated with earthworm, while the other nine had no earthworm. The total petroleum hydrocarbon (TPH), soil physical, nutrient compositions, and TPH degrading bacteria biodiversity were determined before contamination or commencement of study and thirty days after. The results showed a decrease in TPH concentration of 55.58%, 62.57% and 67.07% in 1 ml, 2 ml and 3 ml crude oil contaminated soil, respectively. Species richness and abundance of bacteria organisms increased with high relative abundance in soils remediated with earthworms, hydrocarbon utilizing bacteria increased from less than 0.1 cfu/g to 0.4 cfu/g, and total heterotrophic bacteria 1.6 cfu/g at the end of the study. Earthworms increased rate of remediation potentials of bacteria, such that within 30 days post remediation treatment, 34.14% of reduced concentration was achieved over soil samples without earthworms at 3 ml, and 25.14% at 2 ml concentration. Reduction in pH levels in remediated soils was between 6.39 to 6.17 and 6.74 to 6.72 in unremediated soils, while moisture content was 6.73% to 6.77% unremediated and 5.85% to 6.62% in earthworm remediated soils. Total organic carbon, nitrates in soils inoculated with earthworms were lower in concentration than those without earthworms. Reverse was the case with potassium, phosphate and phosphorous concentrations which were above those without earthworms. Results indicate statistically, significant difference between reduction in TPH in earthworm remediated soils and unremediated soils, pointing out that earthworm is a good candidate for facilitation of bacteria remediation-petroleum hydrocarbon contamination.展开更多
The effects of nitrate concentration on the capability of phosphorus uptake in the main anoxic stage were investigated.Meanwhile, the biomass fractions — heterotrophs, phosphateaccumulating organisms( PAOs),and nitri...The effects of nitrate concentration on the capability of phosphorus uptake in the main anoxic stage were investigated.Meanwhile, the biomass fractions — heterotrophs, phosphateaccumulating organisms( PAOs),and nitrifying organisms in a pilot-scale enhanced biological phosphorus removal( EBPR) system— were both experimentally and theoretically evaluated( from the mass balance calculations of organic matter, nitrogen and phosphorus),under optimum nitrate concentration in the main anoxic stage,in which the influent chemical oxygen demand( COD)concentration was stabilized at( 290 ± 10) mg·L- 1and the influent total phosphorus( TP) concentration was stabilized at( 7. 0 ± 0. 5)mg · L- 1. In long term operations,the process exhibited high performance in removing organic matter, nitrogen, and phosphorus. Approximately 46. 41% of organic matter,57. 21% of nitrogen,and 48. 14% of phosphorus were removed from the influent in the form of carbon dioxide,nitrogen gas,and polyphosphate,respectively. XH( heterotrophs),XPAO( PAOs),and XAUT( autotrophs) were regarded as the major organisms responsible for biomass production. The yield fractions of XHgrowth in the first anoxic,the second anoxic,and the aerobic stages were 10. 24%,19. 11%,and 19. 71%,respectively; the yield fractions of XPAO growth in the second anoxic and the aerobic stages were 24. 34% and19. 86%,respectively; the yield fraction of XAUTgrowth in the aerobic stage was 6. 74%. These results showed that XHand XPAOformed the major community. Moreover,a higher amount of XPAOgrowth on stored poly-hydroxyalkanoates( PHAs) under the anoxic condition was seen in this EBPR system for municipal wastewater treatment.展开更多
Coagulation of red tide organism cells with clays is discussed in theory and the effects of some fac-tors on it are studied.A quantitative model is presented which describes how the coagulation varies withpH in soluti...Coagulation of red tide organism cells with clays is discussed in theory and the effects of some fac-tors on it are studied.A quantitative model is presented which describes how the coagulation varies withpH in solution.According to the model,within the pH-range between pH<sub>zpc<sub>a</sub></sub>and pH<sub>zpc<sub>b</sub></sub>,V<sub>R</sub> is negativeand the coagulation is strong and strongest at pH=(pH<sub>zpc<sub>a</sub></sub>+pH<sub>zpc<sub>b</sub></sub>)/2.It is also demonstrated that whenthe diameter of clay particles is close to that of cells,the collision probability is low,resulting in weakercoagulation.The model results have been corroborated by experiments and so are scientific and theoreticalbases for application.展开更多
This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montm...This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system.展开更多
Study on the coagulation of four species of red tide organisms（Nitzschia pungens,Skeletonema costatum,Prorocentrum minimum and Noctiluca scintillans）with montmorillonite,and the effect ofmontmorillonite pretreatment...Study on the coagulation of four species of red tide organisms（Nitzschia pungens,Skeletonema costatum,Prorocentrum minimum and Noctiluca scintillans）with montmorillonite,and the effect ofmontmorillonite pretreatment on the coagulation shows that the capability for montmorillonite to coagu-late with them is in the order:N.pungens】S.costatum】P.minimum】N.scintillans.Thecoagulation is discussed from the aspects of the structure,shape,size,movement,habit,etc.of differ-ent species and the results are explained theoretically.The experimental results also indicate that the treat-ment of montmorillonite with acid can enhance its coagulating capability.This is due to the fact that Al（OH<sub>2</sub>）<sub>6</sub><sup>+3</sup>,exchanged from the clay lattice by hydrogen ion H<sup>+</sup>,forms hydroxy-aluminum polymers on thesurface of the montmorillonite.The hydroxy-aluminum polymers positively charge and increase the positivecharacteristic of the clay surface,and also serves as a bridge between adjacent surfaces of particles.Thesetwo functions展开更多
BACKGROUND Intensive care unit(ICU)patients are critically ill and have low immunity.They will undergo various trauma medical procedures during diagnosis and treatment.The use of high-dose hormones and broad-spectrum ...BACKGROUND Intensive care unit(ICU)patients are critically ill and have low immunity.They will undergo various trauma medical procedures during diagnosis and treatment.The use of high-dose hormones and broad-spectrum antibiotics will increase the incidence of nosocomial infection in ICU patients.Therefore,it is necessary to explore the causes of nosocomial infection in ICU and provide basis for the prevention and control of nosocomial infection in ICU.AIM To explore major pathogens of nosocomial infection in ICUs,methods of detection and drug resistance trends.METHODS Risk factors of multidrug-resistant infection were analyzed to provide a basis for clinical rational use of antimicrobial drugs in the ICU.These findings were used to standardize rational use of antimicrobial agents.BD PhoenixTM100 automatic bacterial identification analyzer was used to for cell identification in specimens collected from the ICU between January 2016 and December 2019.Drug sensitivity tests were carried out and drug resistance trends were analyzed using the optical disc diffusion method.Odds ratios and corresponding 95%CI of independent variables were calculated using a logistic regression model.Backward elimination(trend=0.1)was used as an inclusion criterion for multivariate analysis.All data were analyzed using SPSS version 22.0,and P<0.05 was considered statistically significant.RESULTS We collected 2070 samples from ICU patients between January 2016 and December 2019.Sample types comprised sputum(1139 strains,55.02%),blood(521 strains,25.17%),and drainage fluid(117 strains,5.65%).A total of 1051 strains of major pathogens,including Acinetobacter baumannii,Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa),Klebsiella pneumoniae(K.pneumoniae)and Staphylococcus aureus,were detected,with a detection rate of 35.97%(378/1051).Most of these strains were resistant to antibiotics.Detection rate of E.coli was 21.79%(229/1051),and it was generally sensitive to many antimicrobial drugs.Detection rate of P.aeruginosa was 24.74%(260/1051),and showed low sensitivity to most antibiotics.Detection rate of K.pneumoniae was 9.42%(99/1051),which was generally resistant to multiple antimicrobial drugs and resistant forms.K.pneumoniae was resistant to imipenem for approximate 4 years,and showed a 19.9%(19/99)and 20.20%(20/99)rate of meropenem resistance.Logistic analysis showed that mechanical ventilation and ureteral intubation were risk factors for multidrug-resistant bacterial infections.CONCLUSION This study showed a high incidence of ICU infections.Mechanical ventilation and urine tube intubation were risk factors for infection with multidrug-resistant bacteria.展开更多
Low energy ions exist widely in natural world, but people pay a little attention on. the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy io...Low energy ions exist widely in natural world, but people pay a little attention on. the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy ions and the complicated organism. The discovery of bioeffect induced by ion implantation has, however, opened a new branch in the field of ion beam application in life sciences. This paper reports recent advances in research on the role of low energy ions in Chemical synthesis of the biomolecules and application in genetic modification.展开更多
Sludge dewatering and treatment may cost as much as the wastewater treatment.Usually large proportion of the pollutants in wastewater is organic.They are attacked by saprophytic microorganisms,i.e.organisms that feed ...Sludge dewatering and treatment may cost as much as the wastewater treatment.Usually large proportion of the pollutants in wastewater is organic.They are attacked by saprophytic microorganisms,i.e.organisms that feed upon dead organic matter.Activity of organisms causes decomposition of organic matter and destroys them,where the bacteria convert the organic matter or other constituents in the wastewater to new cells,water,gases and other products.Demolition activities,including renovation/remodeling works and complete or selective removal/demolishing of existing structures either by man-made processes or by natural disasters,create an extensive amount of wastes.These demolition wastes are characterized as heterogeneous mixtures of building materials that are usually contaminated with chemicals and dirt.In developing countries, it is estimated that demolition wastes comprise 20%to 30%of the total annual solid wastes.In Egypt,the daily quantity of construction and demolition(C&D) waste has been estimated as 10 000 tones.That is equivalent to one third of the total daily municipal solid wastes generated per day in Egypt.The zabbaliin have since expanded their activities and now take the waste they collect back to their garbage villages where it is sorted into recyclable components:paper,plastics, rags,glass,metal and food.The food waste is fed to pigs and the other items are sold to recycling centers.This paper summarizes the wastewater and solid wastes management in Egypt now and future.展开更多
The epidemiological investigations on the disease and death in mature eggs, embryonic de- velopmental periods and larvae populations [including oocytes, fertilized ovum, early embryonic phase larvae (6 h), D-shaped ph...The epidemiological investigations on the disease and death in mature eggs, embryonic de- velopmental periods and larvae populations [including oocytes, fertilized ovum, early embryonic phase larvae (6 h), D-shaped phase larvae (24 h), early umbo phase larvae, umbo phase larvae, post um- bo phase larvae and eyespot phase larvae] in the Luhuitou Pearl Oyster Mariculture Farm of Sanya City, Hainan Province in April 1995 showed that there were two peaks of mortality rates which occurred in early umbo phase or umbo phase and post umbo phase (Figs 3-5 and Table 1) respectively from pre- embryonic developmental periods to larvae phases. It indicated that the onset and death of Pinctada maxima larvae populations followed a pattem of outbreak. Between the prevalence, intensity of RLO infection and the mortality rates of larvae populations were of obvious positively correlations. Generally, every peak of RLO infection is always follwed by a peak of mortality rate of larvae hosts, and the mor- tality rates of larvae hosts declined with the decreased RLO infection (see Figs 3-5 ). Under the trans- mission electron microscopy (TEM), no rickettsia-like organisms were discovered in oocytes, fertilized ovum and early embryonic phase larvae (6 h). The RLO inclusions occurred first in the D-shaped phase larvae (24 h) under histological examination. Absences of RLO in transmission electron exami- nation of oocytes of RLO-infected adult females, ferilized ovum and early embryonic phase larvae (6 h) indicated that RLO may not be transmitted transovarially. But RLO for host infection may be trans- mitted by contact transmission since RLO inclusions were first identified regularly in D-shaped phase larvae (24 h), while these D-shaped phase larvae were still unable to take food during hatching 24 hours. In addition, the result of epidemiological investigation showed that no odservable death occurred in D-shaped larvae populations, but early obvious death occurred in larvae populations in the seventh day after fertilization, in a rate of about 21. 8%. It indicated that there was a incubation peried from RLO infection for host (D-shaped phase larvae) to host onset and death occurred clinically.展开更多
The death which occurred in juvenile population was a severe problem in the course ofPinctada maxima artificial culture. With the methods of field investigation, histological study andstatistic analyses, the epidemiol...The death which occurred in juvenile population was a severe problem in the course ofPinctada maxima artificial culture. With the methods of field investigation, histological study andstatistic analyses, the epidemiological study was carried out on the disease and death in juvenile popula-tions of Pinctada maxima in the Xinying Pearl Oyster Mariculture Farm of Lingao County (for the A,B and C batches of cultured juveniles hanged in the sea) and the Xincun Pearl Oyster Mariculture Farmof Lingshui County (for the D batch of cultured juvenile hanged in the pond), Hainan Province fromNovember 1993 to April 1995. The results show that the deaths which occurred in juvenile populations of Pinctada maxima pre-sented an outbreak pattern. The peak of mortality rates, in general, occurred in 4-to 6-month old pearloyster juveniles, and the mortality rates gradully declined with the extention of pearl oyster age after cul-turing 8 months. The correlation between the mortality rates of juvenile populations and mean bodylengths of juvenile populations show that the mortality rate become higher under 4 cm of mean bodylengths of juvenile population and become obvious declined over 5 cm of mean body lengths. The peak ofmortality rate occurred in 1 ～3 cm of mean body lengths. The results of histological observation showedthat rickettsia-like organism inclusions were common, histological widespread infective agent among ev-ery batches (A, B, C and D) of cultured juvenile populations. The mean severity indices (SI) of rick-ettsia-like organism (RLO) infection were positively correlated with mortality rates of juvenile popula-tions. After or within every peaks of RLO infection were all accompanied with the peaks of mortalityrates of host populations and the mortality rates declined with decreased RLO infection. So the evidencesof histological observation and epidemiology in this study indicated that rickettsia-like organism (RLO)may be as an important pathogenic organism of disease and death of cultured Pinctada maxima. In addi-tion, a few ciliates were discovered only in part of batch A of cultured juvenile population. The mortalityrates in juvenile populations were not correlated with the weekly mean temperature and salinity of seawater.展开更多
The research status and the future study prospect of salt lake organisms of Chinese salt lakes were elaborated in this paper.Many saline lakes occur widely in arid and semiarid areas of China,and more than half of the
Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially f...Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.展开更多
基金Supported by Zhaoqing University Innovation and Entrepreneurship Training Program for College Students(202310580018).
文摘[Objectives]To study the phosphorus removal performance of phosphate accumulating organisms(PAOs).[Methods]Activated sludge from domestic sewage treatment plant was used as the strain source,and phosphate accumulating organisms were screened by plate streaking method and dilution coating plate method.Six kinds of excellent phosphate accumulating organisms were obtained by metachromatic granule staining experiment,total phosphorus experiment and simulated sewage phosphorus removal experiment to assist the observation of bac-terial morphology and experiment of phosphorus removal capacity.In addition,the influencing factors of phosphorus removal capacity(nitrogen source,trace metal ions)were analyzed.[Results]In the case of simulated sewage,the phosphorus removal rate of strain b was the highest,reaching 66.25%,while the phosphorus removal rate of strain e and f was about 10%lower than that of the phosphorus uptake experiment.[Conclusions]This study is expected to provide a theoretical reference for the gradual optimization of the screening method of phosphorus re-moval bacteria in domestic sewage treatment.
基金supported by the National Natural Science Foundation of China(No.U2106231)the National Key R&D Program of China(No.2022YFD2400303)the Key R&D Project of Shandong Province(No.2022 TZXD003).
文摘A better understanding of genetic bases of growth regulation is essential for bivalve breeding,which is helpful to improve the yield of the commercially important bivalves.While previous studies have identified some candidate genes accounting for variation in growth-related traits through genotype-phenotype association analyses,seldom of them have verified the functions of these putative,growth-related genes beyond the genomic level due to the difficulty of culturing commercial bivalves under laboratory conditions.Fortunately,dwarf surf clam Mulinia lateralis can serve as a model organism for studying marine bivalves given its short generation time,the feasibility of being grown under experimental conditions and the availability of genetic and biological information.Using dwarf surf clam as a model bivalve,we characterize E2F3,a gene that has been found to account for variation in growth in scallops by a previous genome-wide association study,and verify its function in growth regulation through RNA interference(RNAi)experiments.For the first time,E2F3 in dwarf surf clam,which is termed as MulE2F3,is characterized.The results reveal that dwarf surf clams with MulE2F3 knocked down exhibit a reduction in both shell size and soft-tissue weight,indicating the functions of MulE2F3 in positively regulating bivalve growth.More importantly,we demonstrate how dwarf surf clam can be used as a model organism to investigate gene functions in commercial bivalves,shedding light on genetic causes for variation in growth to enhance the efficiency of bivalve farming.
文摘This study explored the concurrent scheduling of machines, tools, and tool transporter(TT) with alternative machines in a multi-machine flexible manufacturing system(FMS), taking into mind the tool transfer durations for minimization of the makespan(MSN). When tools are expensive, just a single copy of every tool kind is made available for use in the FMS system. Because the tools are housed in a central tool magazine(CTM), which then distributes and delivers them to many machines, because there is no longer a need to duplicate the tools in each machine, the associated costs are avoided. Choosing alternative machines for job operations(jb-ons), assigning tools to jb-ons, sequencing jb-ons on machines, and arranging allied trip activities, together with the TT’s loaded trip times and deadheading periods, are all challenges that must be overcome to achieve the goal of minimizing MSN. In addition to a mixed nonlinear integer programming(MNLIP) formulation for this simultaneous scheduling problem, this paper suggests a symbiotic organisms search algorithm(SOSA) for the problem’s solution. This algorithm relies on organisms’ symbiotic interaction strategies to keep living in an ecosystem. The findings demonstrate that SOSA is superior to the Jaya algorithm in providing solutions and that using alternative machines for operations helps bring down MSN.
基金supported by Clinical Toxicology Grants from Chinese Society of Toxicology(No.CST2020CT604).
文摘Background:Coronavirus disease 2019(COVID-19)has now spread to most countries and regions of the world.Risk factors associated with multi-drug resistant organism(MDRO)infections in patients with COVID-19 have not been well studied yet.In the present study,we aimed to identify the risk factors associated with the MDRO infections and their impact on in-hospital mortality of COVID-19 patients.Methods:This retrospective cohort study was conducted between December 2019 and April 2020 at two tertiary hospitals in Wuhan,China.Data of cases were collected through electronic medical records system.This study was focused on cases with bacterial culture records.Risk factors and outcomes associated with MDRO infections were analyzed using logistic regression model.Results:Of the 2891 patients,370 patients have bacterial culture results,and MDROs were isolated in 38 patients.Respiratory tract infections(67.3%)were the most common hospital acquired infections.Variables independently associated with MDRO infections were dyspnea at admission(odds ratio(OR)4.74;95%confidence interval(CI)2.06-10.88;P<0.001),intensive care unit(ICU)admission(OR 5.02;95%CI 1.99-12.63;P<0.01),and invasive mechanical ventilation(OR 5.13;95%CI 2.15-12.27;P<0.001),adjusted for age and gender.MDROs infection was also a significant risk factor of death for the patients,adjusted for age,gender,severity of illness,ICU admission and mechanical ventilation(OR 1.12,95%CI:0.43-2.96,P=0.817).Conclusion:In our study,dyspnea at admission,ICU admission and invasive mechanical ventilation were associated with the presence of MDRO infections,and clinicians should be alert in MDRO infections in COVID-19 hospitalized patients.
文摘The pervasive presence of microplastics in marine environments has raised significant concerns. This review addresses the pressing issue of microplastic pollution in marine ecosystems and its potential implications for both the environment and human health. It outlines the current state of microplastic occurrence, distribution, and extraction methods within marine organisms. Microplastics have emerged as a significant environmental concern due to their harmful effects on ecosystems and their potential human health risks. These particles infiltrate marine environments through runoff and atmospheric deposition, ultimately contaminating beaches and posing threats to marine life. Despite the gravity of this issue, there has been limited research on the presence and distribution of microplastics in marine organisms. This review aims to bridge this knowledge gap by comprehensively examining the occurrence, distribution, and various extraction methods used to detect microplastics in marine organisms. It emphasizes the urgent need for targeted measures to manage microplastic pollution, highlights the significant role of human activities in contributing to this problem, and underscores the importance of reducing human-induced pollution to safeguard marine ecosystems. While this paper contributes to the understanding of microplastic pollution in marine environments and underscores the critical importance of taking action to protect marine organisms and preserve our oceans for future generations, it also emphasizes that, in effectively tackling the microplastic problem, a well-coordinated approach is essential, involving research initiatives, policy adjustments, public involvement, and innovative technologies. Crucially, prompt and resolute responses must exist to counteract the escalating peril posed by microplastics to the oceans and the global environment.
文摘The abattoir is one of the important sectors in the food industry, therefore the need for close monitoring of everything concerning it to minimize microbial contamination. The aim of the study is to identify bacteria listed as WHO priority organisms associated with meat from Kwata abattoir in Awka, Anambra state. The study was carried out over a three (3) months period from September to December 2022. Thirteen samples were collected from the floor, table, water, meat, knife and soil in the abattoir. The samples were cultured using streak and spread plate methods on MacConkey and Cetrimide agar. The isolates were identified with the following biochemical tests: catalase, oxidase, citrate and indole tests. Ampiclox levofloxacin, gentamicin, ofloxacin impenem ceftraixone, cefixime, cefuroxime and nitrofurantoin were used for sensitivity test following Kirby Bauer disc diffusion method and biofilm formation was determined using the tube method. The 75 isolates obtained were identified as follows;29.3% E. coli, 26.7% Klebsiella spp., 16% Proteus spp., and 28% Pseudomonas spp. The result of antibiotics sensitivity test interpreted using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints showed that (98%) of the isolates were resistant to the antibiotics used. Test for biofilm formation with 52 isolates showed 31 strong, 12 moderate and 9 weak biofilm formers. The result of this study confirms the presence of bacteria contaminants within the WHO priority list in the abattoir, as such there is need for improved handling of animals. Slaughtering, cleaning and distribution of meat should be done using aseptic procedures. .
文摘Objective:To determine the clinical distribution of multi-drug resistant organism(MDRO)in Jiangyan Hospital and the monitoring and warning of drug-resistance bacteria to provide an important basis for guiding the application of broad-spectrum antibiotics in clinical treatment and reducing the occurrence of nosocomial infection.Methods:Retrospective screening and analysis were conducted on the pathogenic strains of hospitalized patients in our hospital in 2022.Results:A total of 2,769 strains of pathogenic bacteria and 390 strains of MDRO were detected and isolated in our hospital in 2022;the detection rate of MDRO was 14.08%.A total of 516 strains(18.64%)Klebsiella pneumoniae(KP)and 62 strains(12.02%)of carbapenem-resistant Klebsiella pneumoniae(CR-KP)were detected;436 strains(15.75%)of Escherichia coli(ECO)were detected,including 8 strains(1.83%)of CR-ECO;342 strains(12.35%)of Pseudomonas aeruginosa(PA)and 116 strains(33.92%)of CR-PA were detected;there were 194 strains(7.01%)of Acinetobacter baumannii(AB),among which 125 strains(64.43%)were CR-AB;there were 291 strains(10.51%)of Staphylococcus aureus,among which 79 strains(27.15%)of methicillin-resistant Staphylococcus aureus(MRSA)were detected;78 strains(2.82%)of Enterococcus faecalis were detected,and vancomycin-resistant enterococcus(VRE)was not detected.The first five MDROs were CR-AB,CR-PA,MRSA,CR-KP,and CR-ECO.The top five departments with the highest MDRO detection rate in 2022 were the ICU(37.44%),the Pulmonology Department(ward 13;31.03%),the Department of Rehabilitation(ward 5;6.67%),the Department of Neurosurgery(ward 11;4.62%),and the Department of General Surgery(ward 10;3.59 The resistance rate of antibacterial drugs is divided into four levels for early warning:30%to 40%,41%to 50%,51%to 75%,and 75%or more.Conclusion:Our hospital should strengthen the monitoring of antimicrobial resistance warning related to MDRO and the abuse of antimicrobial drugs.Based on the results of drug sensitivity and antimicrobial resistance warning,the use of antibiotics should be standardized in clinical practice to reduce nosocomial infection。
文摘In the Niger Delta region of Nigeria, oil explorations and exploitations abound, causing environmental pollution with serious consequences on soil ecosystem and its biodiversity. In spite of the relationship between microbes and fauna in soil ecosystem, such that both organisms can metabolize certain range of petroleum hydrocarbon substrates with the fauna influencing the remediation potentials of bacteria, yet soil fauna is still not fully considered in bioremediation. The influence of earthworm;Lumbricus terrestris on the remediating potentials of soil bacteria in petroleum hydrocarbon contaminated soils was investigated. Eighteen pots were filled with 700 g of soil each, with nine treated with mixture of 3 levels crude oil and remediated with earthworm, while the other nine had no earthworm. The total petroleum hydrocarbon (TPH), soil physical, nutrient compositions, and TPH degrading bacteria biodiversity were determined before contamination or commencement of study and thirty days after. The results showed a decrease in TPH concentration of 55.58%, 62.57% and 67.07% in 1 ml, 2 ml and 3 ml crude oil contaminated soil, respectively. Species richness and abundance of bacteria organisms increased with high relative abundance in soils remediated with earthworms, hydrocarbon utilizing bacteria increased from less than 0.1 cfu/g to 0.4 cfu/g, and total heterotrophic bacteria 1.6 cfu/g at the end of the study. Earthworms increased rate of remediation potentials of bacteria, such that within 30 days post remediation treatment, 34.14% of reduced concentration was achieved over soil samples without earthworms at 3 ml, and 25.14% at 2 ml concentration. Reduction in pH levels in remediated soils was between 6.39 to 6.17 and 6.74 to 6.72 in unremediated soils, while moisture content was 6.73% to 6.77% unremediated and 5.85% to 6.62% in earthworm remediated soils. Total organic carbon, nitrates in soils inoculated with earthworms were lower in concentration than those without earthworms. Reverse was the case with potassium, phosphate and phosphorous concentrations which were above those without earthworms. Results indicate statistically, significant difference between reduction in TPH in earthworm remediated soils and unremediated soils, pointing out that earthworm is a good candidate for facilitation of bacteria remediation-petroleum hydrocarbon contamination.
基金National Natural Science Foundation of China(No.51308253)Jilin Province Science and Technology Development Projects,China(No.20130522076JH)
文摘The effects of nitrate concentration on the capability of phosphorus uptake in the main anoxic stage were investigated.Meanwhile, the biomass fractions — heterotrophs, phosphateaccumulating organisms( PAOs),and nitrifying organisms in a pilot-scale enhanced biological phosphorus removal( EBPR) system— were both experimentally and theoretically evaluated( from the mass balance calculations of organic matter, nitrogen and phosphorus),under optimum nitrate concentration in the main anoxic stage,in which the influent chemical oxygen demand( COD)concentration was stabilized at( 290 ± 10) mg·L- 1and the influent total phosphorus( TP) concentration was stabilized at( 7. 0 ± 0. 5)mg · L- 1. In long term operations,the process exhibited high performance in removing organic matter, nitrogen, and phosphorus. Approximately 46. 41% of organic matter,57. 21% of nitrogen,and 48. 14% of phosphorus were removed from the influent in the form of carbon dioxide,nitrogen gas,and polyphosphate,respectively. XH( heterotrophs),XPAO( PAOs),and XAUT( autotrophs) were regarded as the major organisms responsible for biomass production. The yield fractions of XHgrowth in the first anoxic,the second anoxic,and the aerobic stages were 10. 24%,19. 11%,and 19. 71%,respectively; the yield fractions of XPAO growth in the second anoxic and the aerobic stages were 24. 34% and19. 86%,respectively; the yield fraction of XAUTgrowth in the aerobic stage was 6. 74%. These results showed that XHand XPAOformed the major community. Moreover,a higher amount of XPAOgrowth on stored poly-hydroxyalkanoates( PHAs) under the anoxic condition was seen in this EBPR system for municipal wastewater treatment.
基金Chinese Postdoctoral Fund and Natural Scienced Found of Shandong Province(No.93E0157)
文摘Coagulation of red tide organism cells with clays is discussed in theory and the effects of some fac-tors on it are studied.A quantitative model is presented which describes how the coagulation varies withpH in solution.According to the model,within the pH-range between pH<sub>zpc<sub>a</sub></sub>and pH<sub>zpc<sub>b</sub></sub>,V<sub>R</sub> is negativeand the coagulation is strong and strongest at pH=(pH<sub>zpc<sub>a</sub></sub>+pH<sub>zpc<sub>b</sub></sub>)/2.It is also demonstrated that whenthe diameter of clay particles is close to that of cells,the collision probability is low,resulting in weakercoagulation.The model results have been corroborated by experiments and so are scientific and theoreticalbases for application.
基金Project supported by Chinese Possteoctoral Fund Shandong Natural Science Fund No.93E0175
文摘This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system.
基金the Chinese postdoctoral fund Natural Science fund of Shandong province No 93E0157 and State Major Besearch project (PD-B6-7-2)
文摘Study on the coagulation of four species of red tide organisms（Nitzschia pungens,Skeletonema costatum,Prorocentrum minimum and Noctiluca scintillans）with montmorillonite,and the effect ofmontmorillonite pretreatment on the coagulation shows that the capability for montmorillonite to coagu-late with them is in the order:N.pungens】S.costatum】P.minimum】N.scintillans.Thecoagulation is discussed from the aspects of the structure,shape,size,movement,habit,etc.of differ-ent species and the results are explained theoretically.The experimental results also indicate that the treat-ment of montmorillonite with acid can enhance its coagulating capability.This is due to the fact that Al（OH<sub>2</sub>）<sub>6</sub><sup>+3</sup>,exchanged from the clay lattice by hydrogen ion H<sup>+</sup>,forms hydroxy-aluminum polymers on thesurface of the montmorillonite.The hydroxy-aluminum polymers positively charge and increase the positivecharacteristic of the clay surface,and also serves as a bridge between adjacent surfaces of particles.Thesetwo functions
基金Supported by Drug resistance trend analysis and prevention and control of main pathogens in tertiary hospitals of Hebei Provincial Department of health,No.20210845Analysis of drug and drug resistance trend and prevention and control of pathogens in major general hospitals of Baoding science and technology support plan project,No.17zf79.
文摘BACKGROUND Intensive care unit(ICU)patients are critically ill and have low immunity.They will undergo various trauma medical procedures during diagnosis and treatment.The use of high-dose hormones and broad-spectrum antibiotics will increase the incidence of nosocomial infection in ICU patients.Therefore,it is necessary to explore the causes of nosocomial infection in ICU and provide basis for the prevention and control of nosocomial infection in ICU.AIM To explore major pathogens of nosocomial infection in ICUs,methods of detection and drug resistance trends.METHODS Risk factors of multidrug-resistant infection were analyzed to provide a basis for clinical rational use of antimicrobial drugs in the ICU.These findings were used to standardize rational use of antimicrobial agents.BD PhoenixTM100 automatic bacterial identification analyzer was used to for cell identification in specimens collected from the ICU between January 2016 and December 2019.Drug sensitivity tests were carried out and drug resistance trends were analyzed using the optical disc diffusion method.Odds ratios and corresponding 95%CI of independent variables were calculated using a logistic regression model.Backward elimination(trend=0.1)was used as an inclusion criterion for multivariate analysis.All data were analyzed using SPSS version 22.0,and P<0.05 was considered statistically significant.RESULTS We collected 2070 samples from ICU patients between January 2016 and December 2019.Sample types comprised sputum(1139 strains,55.02%),blood(521 strains,25.17%),and drainage fluid(117 strains,5.65%).A total of 1051 strains of major pathogens,including Acinetobacter baumannii,Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa),Klebsiella pneumoniae(K.pneumoniae)and Staphylococcus aureus,were detected,with a detection rate of 35.97%(378/1051).Most of these strains were resistant to antibiotics.Detection rate of E.coli was 21.79%(229/1051),and it was generally sensitive to many antimicrobial drugs.Detection rate of P.aeruginosa was 24.74%(260/1051),and showed low sensitivity to most antibiotics.Detection rate of K.pneumoniae was 9.42%(99/1051),which was generally resistant to multiple antimicrobial drugs and resistant forms.K.pneumoniae was resistant to imipenem for approximate 4 years,and showed a 19.9%(19/99)and 20.20%(20/99)rate of meropenem resistance.Logistic analysis showed that mechanical ventilation and ureteral intubation were risk factors for multidrug-resistant bacterial infections.CONCLUSION This study showed a high incidence of ICU infections.Mechanical ventilation and urine tube intubation were risk factors for infection with multidrug-resistant bacteria.
基金National Science & Technology Key ProgramNational Nature Science FOundation+1 种基金Chinese Academy of Sciences FoundationAnh
文摘Low energy ions exist widely in natural world, but people pay a little attention on. the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy ions and the complicated organism. The discovery of bioeffect induced by ion implantation has, however, opened a new branch in the field of ion beam application in life sciences. This paper reports recent advances in research on the role of low energy ions in Chemical synthesis of the biomolecules and application in genetic modification.
基金Supported by a grant from Sanko Company for EM Production and its produetsa grant from JICA Agency.OIC.Okmawa.Japan
文摘Sludge dewatering and treatment may cost as much as the wastewater treatment.Usually large proportion of the pollutants in wastewater is organic.They are attacked by saprophytic microorganisms,i.e.organisms that feed upon dead organic matter.Activity of organisms causes decomposition of organic matter and destroys them,where the bacteria convert the organic matter or other constituents in the wastewater to new cells,water,gases and other products.Demolition activities,including renovation/remodeling works and complete or selective removal/demolishing of existing structures either by man-made processes or by natural disasters,create an extensive amount of wastes.These demolition wastes are characterized as heterogeneous mixtures of building materials that are usually contaminated with chemicals and dirt.In developing countries, it is estimated that demolition wastes comprise 20%to 30%of the total annual solid wastes.In Egypt,the daily quantity of construction and demolition(C&D) waste has been estimated as 10 000 tones.That is equivalent to one third of the total daily municipal solid wastes generated per day in Egypt.The zabbaliin have since expanded their activities and now take the waste they collect back to their garbage villages where it is sorted into recyclable components:paper,plastics, rags,glass,metal and food.The food waste is fed to pigs and the other items are sold to recycling centers.This paper summarizes the wastewater and solid wastes management in Egypt now and future.
基金This study was supported by the Projects under the Major State Basic Research Development Program under contractNo.G199012001,
文摘The epidemiological investigations on the disease and death in mature eggs, embryonic de- velopmental periods and larvae populations [including oocytes, fertilized ovum, early embryonic phase larvae (6 h), D-shaped phase larvae (24 h), early umbo phase larvae, umbo phase larvae, post um- bo phase larvae and eyespot phase larvae] in the Luhuitou Pearl Oyster Mariculture Farm of Sanya City, Hainan Province in April 1995 showed that there were two peaks of mortality rates which occurred in early umbo phase or umbo phase and post umbo phase (Figs 3-5 and Table 1) respectively from pre- embryonic developmental periods to larvae phases. It indicated that the onset and death of Pinctada maxima larvae populations followed a pattem of outbreak. Between the prevalence, intensity of RLO infection and the mortality rates of larvae populations were of obvious positively correlations. Generally, every peak of RLO infection is always follwed by a peak of mortality rate of larvae hosts, and the mor- tality rates of larvae hosts declined with the decreased RLO infection (see Figs 3-5 ). Under the trans- mission electron microscopy (TEM), no rickettsia-like organisms were discovered in oocytes, fertilized ovum and early embryonic phase larvae (6 h). The RLO inclusions occurred first in the D-shaped phase larvae (24 h) under histological examination. Absences of RLO in transmission electron exami- nation of oocytes of RLO-infected adult females, ferilized ovum and early embryonic phase larvae (6 h) indicated that RLO may not be transmitted transovarially. But RLO for host infection may be trans- mitted by contact transmission since RLO inclusions were first identified regularly in D-shaped phase larvae (24 h), while these D-shaped phase larvae were still unable to take food during hatching 24 hours. In addition, the result of epidemiological investigation showed that no odservable death occurred in D-shaped larvae populations, but early obvious death occurred in larvae populations in the seventh day after fertilization, in a rate of about 21. 8%. It indicated that there was a incubation peried from RLO infection for host (D-shaped phase larvae) to host onset and death occurred clinically.
基金Major State Basic Research Development Program of China under contract No. G1999012001Key Science Foundation of the Chinese Academy of Sciences contract KS85-121.
文摘The death which occurred in juvenile population was a severe problem in the course ofPinctada maxima artificial culture. With the methods of field investigation, histological study andstatistic analyses, the epidemiological study was carried out on the disease and death in juvenile popula-tions of Pinctada maxima in the Xinying Pearl Oyster Mariculture Farm of Lingao County (for the A,B and C batches of cultured juveniles hanged in the sea) and the Xincun Pearl Oyster Mariculture Farmof Lingshui County (for the D batch of cultured juvenile hanged in the pond), Hainan Province fromNovember 1993 to April 1995. The results show that the deaths which occurred in juvenile populations of Pinctada maxima pre-sented an outbreak pattern. The peak of mortality rates, in general, occurred in 4-to 6-month old pearloyster juveniles, and the mortality rates gradully declined with the extention of pearl oyster age after cul-turing 8 months. The correlation between the mortality rates of juvenile populations and mean bodylengths of juvenile populations show that the mortality rate become higher under 4 cm of mean bodylengths of juvenile population and become obvious declined over 5 cm of mean body lengths. The peak ofmortality rate occurred in 1 ～3 cm of mean body lengths. The results of histological observation showedthat rickettsia-like organism inclusions were common, histological widespread infective agent among ev-ery batches (A, B, C and D) of cultured juvenile populations. The mean severity indices (SI) of rick-ettsia-like organism (RLO) infection were positively correlated with mortality rates of juvenile popula-tions. After or within every peaks of RLO infection were all accompanied with the peaks of mortalityrates of host populations and the mortality rates declined with decreased RLO infection. So the evidencesof histological observation and epidemiology in this study indicated that rickettsia-like organism (RLO)may be as an important pathogenic organism of disease and death of cultured Pinctada maxima. In addi-tion, a few ciliates were discovered only in part of batch A of cultured juvenile population. The mortalityrates in juvenile populations were not correlated with the weekly mean temperature and salinity of seawater.
文摘The research status and the future study prospect of salt lake organisms of Chinese salt lakes were elaborated in this paper.Many saline lakes occur widely in arid and semiarid areas of China,and more than half of the
基金funded by National Natural Science Foundation of China (Grant No. U1663201, 41472099 and 41872155)the Strategic Priority Research Program of the Chinese Academy of Science (Grant No. XDA14010404)CNPC innovation Foundation (2016D-5007-0102)
文摘Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.
