To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine...To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine drainages obtained from sulfide mines of China.The leaching rate was set as criterion to screen the mixed culture and the metagenomic approach.Community genome array(CGA) was used for analyzing the mixed culture microbial community shift during the bioleaching process.The results indicate that the mixed culture obtained from Yinshan(YS) lead-zinc mine in Dexing of Jiangxi province in China reaches the maximum copper extraction(68.89%) during the one bioleaching period of 24 d.CGA results show that YS culture contains nine kinds of bacteria which are belong to six divisions,and the microbial community structure is changing during the bioleaching process.This provides a good way to accelerate the bioleaching process and reveals the microbial community shift during the bioleaching process.展开更多
DNA barcoding provides accurate stages. Single-gene-targeted metagenomic analysis identification of zooplankton species through all life based on DNA barcode databases can facilitate long- term monitoring of zooplankt...DNA barcoding provides accurate stages. Single-gene-targeted metagenomic analysis identification of zooplankton species through all life based on DNA barcode databases can facilitate long- term monitoring of zooplankton communities. With the help of the available zooplankton databases, the zooplankton community of the Changjiang (Yangtze) River estuary was studied using a single-gene-targeted metagenomic method to estimate the species richness of this community. A total of 856 mitocbondrial cytochrome oxidase subunit 1 (coxl) gene sequences were determined. The environmental barcodes were clustered into 70 molecular operational taxonomic units (MOTUs). Forty-two MOTUs matched barcoded marine organisms with more than 90% similarity and were assigned to either the species (similarity〉96%) or genus level (similarity〈96%). Sibling species could also be distinguished. Many species that were overlooked by morphological methods were identified by molecular methods, especially gelatinous zooplankton and merozooplankton that were likely sampled at different life history phases. Zooplankton community structures differed significantly among all of the samples. The MOTU spatial distributions were influenced by the ecological habits of the corresponding species. In conclusion, single-gene-targeted metagenomic analysis is a useful tool for zooplankton studies, with which specimens from all life history stages can be identified quickly and effectively with a comprehensive database.展开更多
Linkage disequilibrium(LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping.The feasibility and efficacy of association studies are str...Linkage disequilibrium(LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping.The feasibility and efficacy of association studies are strongly dependent on the extent of LD which determines the number and density of markers in the studied population,as well as the experimental design for an association analysis.In this study,we first characterized the extent of LD in a wild population and a cultured mass-selected line of Pacific oyster(Crassostrea gigas).A total of 88 wild and 96 cultured individuals were selected to assess the level of genome-wide LD with 53 microsatellites,respectively.For syntenic marker pairs,no significant association was observed in the wild population;however,three significant associations occurred in the cultured population,and the significant LD extended up to 12.7 c M,indicating that strong artificial selection is a key force for substantial increase of genome-wide LD in cultured population.The difference of LD between wild and cultured populations showed that association studies in Pacific oyster can be achieved with reasonable marker densities at a relatively low cost by choosing an association mapping population.Furthermore,the frequent occurrence of LD between non-syntenic loci and rare alleles encourages the joint application of linkage analysis and LD mapping when mapping genes in oyster.The information on the linkage disequilibrium in the cultured population is useful for future association mapping in oyster.展开更多
AIM:To investigate the associations between interleukin(IL)-1B and IL-1RN polymorphisms and gastric cancers among the Tibet,Hui and Han ethnicities.METHODS:Genomic DNA was extracted from peripheral blood of 210,205,an...AIM:To investigate the associations between interleukin(IL)-1B and IL-1RN polymorphisms and gastric cancers among the Tibet,Hui and Han ethnicities.METHODS:Genomic DNA was extracted from peripheral blood of 210,205,and 202 healthy volunteers and from 155,158,and 197 gastric cancer patients from the Tibet,Hui,and Han populations,respectively.Polymorphisms in IL-1B and IL-1RN were analyzed by denaturing high-performance liquid chromatography.RESULTS:Carriers of the IL-1B-31 CC genotype had an increased risk of intestinal type gastric cancer [odds ratio(OR) = 2.17,P = 0.037] in the Tibet ethnicity.Carriers of the IL-1B 2/L genotype had an increased risk of both intestinal and diffuse types of gastric cancer(OR = 2.08,2.31,P = 0.007,0.016,respectively) in the Hui ethnicity.In the Han population,carriers of the IL-1B-31 CC,IL-1B-511CT,TT genotypes had increased risk of intestinal type gastric cancer(OR = 2.51,2.74,5.66,P = 0.005,0.002,0.000,respectively).CONCLUSION:IL-1B and IL-RN genotypes may differentially contribute to gastric cancer among the Tibet,Hui,and Han ethnicities in the Qinghai area of China.展开更多
In this study, the 454 pyrosequencing technology was used to analyze the DNA of the Microcystis aeruginosa symbiosis system from cyanobacterial algal blooms in Taihu Lake, China. We generated 183 228 reads with an ave...In this study, the 454 pyrosequencing technology was used to analyze the DNA of the Microcystis aeruginosa symbiosis system from cyanobacterial algal blooms in Taihu Lake, China. We generated 183 228 reads with an average length of 248 bp. Running the 454 assembly algorithm over our sequences yielded 22 239 significant contigs. After excluding the M. aeruginosa sequences, we obtained 1 322 assembled contigs longer than 1 000 bp. Taxonomic analysis indicated that four kingdoms were represented in the community: Archaea (n = 9; 0.01%), Bacteria (n = 98 921; 99.6%), Eukaryota (n = 373; 3.7%), and Viruses (n = 18; 0.02%). The bacterial sequences were predominantly Alphaproteobacteria (n = 41 805; 83.3%), Betaproteobacteria (n = 5 254; 10.5%) and Gammaproteobacteria (n = 1 180; 2.4%). Gene annotations and assignment of COG (clusters of orthologous groups) functional categories indicate that a large number of the predicted genes are involved in metabolic, genetic, and environmental information processes. Our results demonstrate the extraordinary diversity of a microbial community in an ectosymbiotic system and further establish the tremendous utility of pyrosequencing.展开更多
The actinomycete populations and functions in cadmium (Cd) contaminated soil were investigated by the cultivation- independent molecular methods. The genomic DNA was extracted and purified from soil adulterated with...The actinomycete populations and functions in cadmium (Cd) contaminated soil were investigated by the cultivation- independent molecular methods. The genomic DNA was extracted and purified from soil adulterated with various con- centrations of Cd in the laboratory. The partial 16S rDNA genes were amplified by polymerase chain reaction (PCR) using specific primers bound to evolutionarily conserved regions within these actinomycete genes. The diversity in PCR- amplified products, as measured by denaturing gradient gel electrophoresis (EGGE), was used as a genetic fingerprint of the population. Principle component analysis and Shannon-Weaver diversity index (H) analyses were used to analyze the DGGE results. Results showed that the two principal components accounted for only a low level of the total variance. The value H in contaminated soil was lower than that in the control at later stages of cultivation, whereas at earlier stages it was higher. Among the six sampling time points, the first, fifth and sixth weeks had the highest values of H. Significantly negative correlations between bioavallable Cd concentration and H values existed in the samples from weeks 2 (R = 0.929, P 〈 0.05) and 4 (R = 0.909, P 〈 0.05). These results may shed light on the effect of Cd on the soil environment and the chemical behavior and toxicity of Cd to actinomycetes.展开更多
The elite rice cultivar Yuejingsimiao 2 (YJ2) is characterized by a high level of grain quality and yield, and resistance against Magnaporthe oryzae. YJ2 showed 100% resistance to four fungal populations collected f...The elite rice cultivar Yuejingsimiao 2 (YJ2) is characterized by a high level of grain quality and yield, and resistance against Magnaporthe oryzae. YJ2 showed 100% resistance to four fungal populations collected from Guangdong, Sichuan, Liaoning, and Heilongjiang Provinces, which is a higher frequency than that shown by the well-known resistance (R) gene donor culti- vats such as Sanhuangzhan 2 and 28zhan. Segregation analysis for resistance with F2 and F4 populations indicated the re- sistance of YJ2 was controlled by multiple genes that are dominant or recessive. The putative R genes of YJ2 were roughly tagged by SSR markers, located on chromosomes 2, 6, 8, and 12, in a hulked-segregant analysis using genome-wide selected SSR markers with F4 lines that segregated into 3 resistant (R): 1 susceptible (S) or 1R:3S. The recessive R gene on chromosome 8 was further mapped to an interval ~1.9 cM/152 kb in length by linkage analysis with genomic position-ready markers in the mapping population derived from an F4 line that segregated into 1R:3S. Given that no major R gene was mapped to this inter- val, the novel R gene was designated as pi55(t). Out of 26 candidate genes predicted in the region based on the reference genomic sequence of the cultivar Nipponbare, two genes that encode a leucine-rich repeat-containing protein and heavy-metalassociated domain-containing protein, respectively, were suggested as the most likely candidates for pi55(t).展开更多
Highly fecund marine species with dispersive life-history stages often display large population sizes and wide geographic distribution ranges. Consequently, they are expected to experience reduced genetic drift, effic...Highly fecund marine species with dispersive life-history stages often display large population sizes and wide geographic distribution ranges. Consequently, they are expected to experience reduced genetic drift, efficient selection fueled by frequent adaptive mutations, and high migration loads. This has important consequences for understanding how local adaptation proceeds in the sea. A key issue in this regard, relates to the genetic architecture underlying fitness traits. Theory predicts that adaptation may involve many genes but with a high variance in effect size. Therefore, the effect of selection on allele frequencies may be substantial for the largest effect size loci, but insignificant for small effect genes. In such a context, the performance of population genomic methods to unravel the genetic basis of adaptation depends on the fraction of adaptive genetic variance explained by the cumulative effect of outlier loci. Here, we address some methodological challenges associated with the detection of local adaptation using molecular approaches. We provide an overview of genome scan methods to detect selection, including those assuming complex demographic models that better describe spatial population structure. We then focus on quantitative genetics approaches that search for genotype-phenotype associations at different genomic scales, including genome-wide methods evaluating the cumulative effect of variants. We argue that the limited power of single locus tests can be alleviated by the use of polygenic scores to estimate the joint contribution of candidate variants to phenotypic variation.展开更多
De novo transcriptome assembly is an important approach in RNA-Seq data analysis and it can help us to reconstruct the transcriptome and investigate gene expression profiles without reference genome sequences.We carri...De novo transcriptome assembly is an important approach in RNA-Seq data analysis and it can help us to reconstruct the transcriptome and investigate gene expression profiles without reference genome sequences.We carried out transcriptome assemblies with two RNA-Seq datasets generated from human brain and cell line,respectively.We then determined an efficient way to yield an optimal overall assembly using three different strategies.We first assembled brain and cell line transcriptome using a single k-mer length.Next we tested a range of values of k-mer length and coverage cutoff in assembling.Lastly,we combined the assembled contigs from a range of k values to generate a final assembly.By comparing these assembly results,we found that using only one k-mer value for assembly is not enough to generate good assembly results,but combining the contigs from different k-mer values could yield longer contigs and greatly improve the overall assembly.展开更多
Population genomic approaches are making rapid inroads in the study of non-model organisms, including marine taxa. To date, these marine studies have predominantly focused on rudimentary metrics describing the spatial...Population genomic approaches are making rapid inroads in the study of non-model organisms, including marine taxa. To date, these marine studies have predominantly focused on rudimentary metrics describing the spatial and environmental context of their study region (e.g., geographical distance, average sea surface temperature, average salinity). We contend that a more nuanced and considered approach to quantifying seascape dynamics and patterns can strengthen population genomic investigations and help identify spatial, temporal, and environmental factors associated with differing selective regimes or demographic histories. Nevertheless, approaches for quantifying marine landscapes are complicated. Characteristic features of the marine environment, including pelagic living in flowing water (experienced by most marine taxa at some point in their life cycle), require a well-designed spatial-temporal sampling strategy and analysis. Many genetic summary statistics used to describe populations may be inappropriate for marine species with large population sizes, large species ranges, stochastic recruitment, and asymmetrical gene flow. Finally, statistical approaches for testing associations between seascapes and population genomic patterns are still maturing with no single approach able to capture all relevant considerations. None of these issues are completely unique to marine systems and therefore similar issues and solutions will be shared for many organisms regardless of habitat. Here, we outline goals and spatial approaches for land- scape genomics with an emphasis on marine systems and review the growing empirical literature on seascape genomics. We review established tools and approaches and highlight promising new strategies to overcome select issues including a strategy to spatially optimize sampling. Despite the many challenges, we argue that marine systems may be especially well suited for identifying candidate genomic regions under environmentally mediated selection and that seascape genomic approaches are especially useful for identifying robust locus-by-environment associations.展开更多
The study of human microbiota is an emerging research topic. The past efforts have mainly centered on studying the composition and genomic landscape of bacterial species within the targeted communities. The interactio...The study of human microbiota is an emerging research topic. The past efforts have mainly centered on studying the composition and genomic landscape of bacterial species within the targeted communities. The interaction between bacteria and hosts is the pivotal event in the initiation and progression of infectious diseases. There is a great need to identify and characterize the molecules that mediate the bacteria-host interaction. Bacterial surface exposed proteins play an important role in the bacteria-host interaction. Numerous surface proteins are glycosylated, and the glycosylation is crucial for their function in mediating the bacterial interaction with hosts. Here we present an overview of surface glycoproteins from bacteria that inhabit three major mucosal environments across human body: oral, gut and skin. We describe the important enzymes involved in the process of protein glycosylation, and discuss how the process impacts the bacteria-host interaction. Emerging molecular details underlying glycosylation of bacterial surface proteins may lead to new opportunities for designing anti-infective small molecules, and developing novel vaccines in order to treat or prevent bacterial infection.展开更多
Using high-throughput sequencing on metagenome to analyze marine microbial community, it is one of current main issues in the field of environmental microbe research. In this paper, we conducted the functional analysi...Using high-throughput sequencing on metagenome to analyze marine microbial community, it is one of current main issues in the field of environmental microbe research. In this paper, we conducted the functional analysis on seven samples of metagenomic data from different depth seawater in Hawaii. The results of gene prediction and function annotation indicate that there are large amounts of potential novel genes of which functions remain unknown at present. Based on the gene annotation, codon usage bias is studied on ribosomal protein-related genes and shows an evident influence by the marine extreme environment. Furthermore, focusing on the marine environmental differences such as light intensity, dissolved oxygen, temperature and pressure among various depths, comparative analysis is carried out on related genes and metabolic pathways. Thus, the understanding as well as new insights into the correlation between marine environment and microbes are proposed at molecular level. Therefore, the studies herein afford a clue to reveal the special living strategies of microbial community from sea surface to deep sea.展开更多
基金Project(50774102)supported by the National Natural Science Foundation of ChinaProject(2004CB619204)supported by the National Basic Research Program of China
文摘To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine drainages obtained from sulfide mines of China.The leaching rate was set as criterion to screen the mixed culture and the metagenomic approach.Community genome array(CGA) was used for analyzing the mixed culture microbial community shift during the bioleaching process.The results indicate that the mixed culture obtained from Yinshan(YS) lead-zinc mine in Dexing of Jiangxi province in China reaches the maximum copper extraction(68.89%) during the one bioleaching period of 24 d.CGA results show that YS culture contains nine kinds of bacteria which are belong to six divisions,and the microbial community structure is changing during the bioleaching process.This provides a good way to accelerate the bioleaching process and reveals the microbial community shift during the bioleaching process.
基金Supported by the National Natural Science Foundation of China(No.41230963)the National Basic Research Program of China(973 Program)(No.2011CB403604)+2 种基金the"135"Fund of Institute of Oceanology,Chinese Academy of Sciences(No.2012I0060102)the Innovative Research Group Funding of the National Natural Science Foundation of China(No.41121064)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA11020305)
文摘DNA barcoding provides accurate stages. Single-gene-targeted metagenomic analysis identification of zooplankton species through all life based on DNA barcode databases can facilitate long- term monitoring of zooplankton communities. With the help of the available zooplankton databases, the zooplankton community of the Changjiang (Yangtze) River estuary was studied using a single-gene-targeted metagenomic method to estimate the species richness of this community. A total of 856 mitocbondrial cytochrome oxidase subunit 1 (coxl) gene sequences were determined. The environmental barcodes were clustered into 70 molecular operational taxonomic units (MOTUs). Forty-two MOTUs matched barcoded marine organisms with more than 90% similarity and were assigned to either the species (similarity〉96%) or genus level (similarity〈96%). Sibling species could also be distinguished. Many species that were overlooked by morphological methods were identified by molecular methods, especially gelatinous zooplankton and merozooplankton that were likely sampled at different life history phases. Zooplankton community structures differed significantly among all of the samples. The MOTU spatial distributions were influenced by the ecological habits of the corresponding species. In conclusion, single-gene-targeted metagenomic analysis is a useful tool for zooplankton studies, with which specimens from all life history stages can be identified quickly and effectively with a comprehensive database.
基金supported by the Shandong Seed Project and the National Natural Science Foundation of China (31372524)
文摘Linkage disequilibrium(LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping.The feasibility and efficacy of association studies are strongly dependent on the extent of LD which determines the number and density of markers in the studied population,as well as the experimental design for an association analysis.In this study,we first characterized the extent of LD in a wild population and a cultured mass-selected line of Pacific oyster(Crassostrea gigas).A total of 88 wild and 96 cultured individuals were selected to assess the level of genome-wide LD with 53 microsatellites,respectively.For syntenic marker pairs,no significant association was observed in the wild population;however,three significant associations occurred in the cultured population,and the significant LD extended up to 12.7 c M,indicating that strong artificial selection is a key force for substantial increase of genome-wide LD in cultured population.The difference of LD between wild and cultured populations showed that association studies in Pacific oyster can be achieved with reasonable marker densities at a relatively low cost by choosing an association mapping population.Furthermore,the frequent occurrence of LD between non-syntenic loci and rare alleles encourages the joint application of linkage analysis and LD mapping when mapping genes in oyster.The information on the linkage disequilibrium in the cultured population is useful for future association mapping in oyster.
基金Supported by Grants from the National Natural Science Foun dation of China,No.30860259the Youth Scientific Re search Foundation of Qinghai University,No.2008-QY-09
文摘AIM:To investigate the associations between interleukin(IL)-1B and IL-1RN polymorphisms and gastric cancers among the Tibet,Hui and Han ethnicities.METHODS:Genomic DNA was extracted from peripheral blood of 210,205,and 202 healthy volunteers and from 155,158,and 197 gastric cancer patients from the Tibet,Hui,and Han populations,respectively.Polymorphisms in IL-1B and IL-1RN were analyzed by denaturing high-performance liquid chromatography.RESULTS:Carriers of the IL-1B-31 CC genotype had an increased risk of intestinal type gastric cancer [odds ratio(OR) = 2.17,P = 0.037] in the Tibet ethnicity.Carriers of the IL-1B 2/L genotype had an increased risk of both intestinal and diffuse types of gastric cancer(OR = 2.08,2.31,P = 0.007,0.016,respectively) in the Hui ethnicity.In the Han population,carriers of the IL-1B-31 CC,IL-1B-511CT,TT genotypes had increased risk of intestinal type gastric cancer(OR = 2.51,2.74,5.66,P = 0.005,0.002,0.000,respectively).CONCLUSION:IL-1B and IL-RN genotypes may differentially contribute to gastric cancer among the Tibet,Hui,and Han ethnicities in the Qinghai area of China.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KSCX2-YW-G-073)
文摘In this study, the 454 pyrosequencing technology was used to analyze the DNA of the Microcystis aeruginosa symbiosis system from cyanobacterial algal blooms in Taihu Lake, China. We generated 183 228 reads with an average length of 248 bp. Running the 454 assembly algorithm over our sequences yielded 22 239 significant contigs. After excluding the M. aeruginosa sequences, we obtained 1 322 assembled contigs longer than 1 000 bp. Taxonomic analysis indicated that four kingdoms were represented in the community: Archaea (n = 9; 0.01%), Bacteria (n = 98 921; 99.6%), Eukaryota (n = 373; 3.7%), and Viruses (n = 18; 0.02%). The bacterial sequences were predominantly Alphaproteobacteria (n = 41 805; 83.3%), Betaproteobacteria (n = 5 254; 10.5%) and Gammaproteobacteria (n = 1 180; 2.4%). Gene annotations and assignment of COG (clusters of orthologous groups) functional categories indicate that a large number of the predicted genes are involved in metabolic, genetic, and environmental information processes. Our results demonstrate the extraordinary diversity of a microbial community in an ectosymbiotic system and further establish the tremendous utility of pyrosequencing.
基金Project supported by the National Natural Science Foundation of China (Nos. 30570053 and 40501037)the National High Technology Research and Development Program (863 Program) of China (No. 2007AA10Z409)+1 种基金the National"Eleventh Five Years Plan" Key Project on Science and Technology of China (No. 2006BAJ08B01)the Research Fund of Science and Technology Bureau of Zhejiang Province,China (No. 2008C23088)
文摘The actinomycete populations and functions in cadmium (Cd) contaminated soil were investigated by the cultivation- independent molecular methods. The genomic DNA was extracted and purified from soil adulterated with various con- centrations of Cd in the laboratory. The partial 16S rDNA genes were amplified by polymerase chain reaction (PCR) using specific primers bound to evolutionarily conserved regions within these actinomycete genes. The diversity in PCR- amplified products, as measured by denaturing gradient gel electrophoresis (EGGE), was used as a genetic fingerprint of the population. Principle component analysis and Shannon-Weaver diversity index (H) analyses were used to analyze the DGGE results. Results showed that the two principal components accounted for only a low level of the total variance. The value H in contaminated soil was lower than that in the control at later stages of cultivation, whereas at earlier stages it was higher. Among the six sampling time points, the first, fifth and sixth weeks had the highest values of H. Significantly negative correlations between bioavallable Cd concentration and H values existed in the samples from weeks 2 (R = 0.929, P 〈 0.05) and 4 (R = 0.909, P 〈 0.05). These results may shed light on the effect of Cd on the soil environment and the chemical behavior and toxicity of Cd to actinomycetes.
基金supported by the National Natural Science Foundation of China (Grant No. U1131003)the National Transgenic Research Projects(Grant Nos. 2009ZX08009-023 and 2011ZX08001-002)+1 种基金the Guangdong Provincial Natural Science Foundation (Grant No. 10151064001000008)the President Science Foundation of Guangdong Academy of Agricultural Sciences (Grant No. 201101)
文摘The elite rice cultivar Yuejingsimiao 2 (YJ2) is characterized by a high level of grain quality and yield, and resistance against Magnaporthe oryzae. YJ2 showed 100% resistance to four fungal populations collected from Guangdong, Sichuan, Liaoning, and Heilongjiang Provinces, which is a higher frequency than that shown by the well-known resistance (R) gene donor culti- vats such as Sanhuangzhan 2 and 28zhan. Segregation analysis for resistance with F2 and F4 populations indicated the re- sistance of YJ2 was controlled by multiple genes that are dominant or recessive. The putative R genes of YJ2 were roughly tagged by SSR markers, located on chromosomes 2, 6, 8, and 12, in a hulked-segregant analysis using genome-wide selected SSR markers with F4 lines that segregated into 3 resistant (R): 1 susceptible (S) or 1R:3S. The recessive R gene on chromosome 8 was further mapped to an interval ~1.9 cM/152 kb in length by linkage analysis with genomic position-ready markers in the mapping population derived from an F4 line that segregated into 1R:3S. Given that no major R gene was mapped to this inter- val, the novel R gene was designated as pi55(t). Out of 26 candidate genes predicted in the region based on the reference genomic sequence of the cultivar Nipponbare, two genes that encode a leucine-rich repeat-containing protein and heavy-metalassociated domain-containing protein, respectively, were suggested as the most likely candidates for pi55(t).
文摘Highly fecund marine species with dispersive life-history stages often display large population sizes and wide geographic distribution ranges. Consequently, they are expected to experience reduced genetic drift, efficient selection fueled by frequent adaptive mutations, and high migration loads. This has important consequences for understanding how local adaptation proceeds in the sea. A key issue in this regard, relates to the genetic architecture underlying fitness traits. Theory predicts that adaptation may involve many genes but with a high variance in effect size. Therefore, the effect of selection on allele frequencies may be substantial for the largest effect size loci, but insignificant for small effect genes. In such a context, the performance of population genomic methods to unravel the genetic basis of adaptation depends on the fraction of adaptive genetic variance explained by the cumulative effect of outlier loci. Here, we address some methodological challenges associated with the detection of local adaptation using molecular approaches. We provide an overview of genome scan methods to detect selection, including those assuming complex demographic models that better describe spatial population structure. We then focus on quantitative genetics approaches that search for genotype-phenotype associations at different genomic scales, including genome-wide methods evaluating the cumulative effect of variants. We argue that the limited power of single locus tests can be alleviated by the use of polygenic scores to estimate the joint contribution of candidate variants to phenotypic variation.
基金supported by the National Basic Research Program of China (Grant Nos. 2010CB945401, 2007CB108800)National Natural Science Foundation of China (Grant Nos. 30870575, 31071162,31000590)the Science and Technology Commission of Shanghai Municipality (Grant No. 11DZ2260300)
文摘De novo transcriptome assembly is an important approach in RNA-Seq data analysis and it can help us to reconstruct the transcriptome and investigate gene expression profiles without reference genome sequences.We carried out transcriptome assemblies with two RNA-Seq datasets generated from human brain and cell line,respectively.We then determined an efficient way to yield an optimal overall assembly using three different strategies.We first assembled brain and cell line transcriptome using a single k-mer length.Next we tested a range of values of k-mer length and coverage cutoff in assembling.Lastly,we combined the assembled contigs from a range of k values to generate a final assembly.By comparing these assembly results,we found that using only one k-mer value for assembly is not enough to generate good assembly results,but combining the contigs from different k-mer values could yield longer contigs and greatly improve the overall assembly.
文摘Population genomic approaches are making rapid inroads in the study of non-model organisms, including marine taxa. To date, these marine studies have predominantly focused on rudimentary metrics describing the spatial and environmental context of their study region (e.g., geographical distance, average sea surface temperature, average salinity). We contend that a more nuanced and considered approach to quantifying seascape dynamics and patterns can strengthen population genomic investigations and help identify spatial, temporal, and environmental factors associated with differing selective regimes or demographic histories. Nevertheless, approaches for quantifying marine landscapes are complicated. Characteristic features of the marine environment, including pelagic living in flowing water (experienced by most marine taxa at some point in their life cycle), require a well-designed spatial-temporal sampling strategy and analysis. Many genetic summary statistics used to describe populations may be inappropriate for marine species with large population sizes, large species ranges, stochastic recruitment, and asymmetrical gene flow. Finally, statistical approaches for testing associations between seascapes and population genomic patterns are still maturing with no single approach able to capture all relevant considerations. None of these issues are completely unique to marine systems and therefore similar issues and solutions will be shared for many organisms regardless of habitat. Here, we outline goals and spatial approaches for land- scape genomics with an emphasis on marine systems and review the growing empirical literature on seascape genomics. We review established tools and approaches and highlight promising new strategies to overcome select issues including a strategy to spatially optimize sampling. Despite the many challenges, we argue that marine systems may be especially well suited for identifying candidate genomic regions under environmentally mediated selection and that seascape genomic approaches are especially useful for identifying robust locus-by-environment associations.
基金supported by NIH(National Institute Of Health)/NIDCR(National Institute of Dental and Craniofacial Research)grants(R01DE017954R01DE022350)
文摘The study of human microbiota is an emerging research topic. The past efforts have mainly centered on studying the composition and genomic landscape of bacterial species within the targeted communities. The interaction between bacteria and hosts is the pivotal event in the initiation and progression of infectious diseases. There is a great need to identify and characterize the molecules that mediate the bacteria-host interaction. Bacterial surface exposed proteins play an important role in the bacteria-host interaction. Numerous surface proteins are glycosylated, and the glycosylation is crucial for their function in mediating the bacterial interaction with hosts. Here we present an overview of surface glycoproteins from bacteria that inhabit three major mucosal environments across human body: oral, gut and skin. We describe the important enzymes involved in the process of protein glycosylation, and discuss how the process impacts the bacteria-host interaction. Emerging molecular details underlying glycosylation of bacterial surface proteins may lead to new opportunities for designing anti-infective small molecules, and developing novel vaccines in order to treat or prevent bacterial infection.
基金supported by the National ‘‘Twelfth Five-Year’’ Plan for Science and Technology of China(2012BAI06B02)the National Natural Science Foundation of China(91231119, 30970667 and 11021463)the National Basic Research Program of China (2011CB707500)
文摘Using high-throughput sequencing on metagenome to analyze marine microbial community, it is one of current main issues in the field of environmental microbe research. In this paper, we conducted the functional analysis on seven samples of metagenomic data from different depth seawater in Hawaii. The results of gene prediction and function annotation indicate that there are large amounts of potential novel genes of which functions remain unknown at present. Based on the gene annotation, codon usage bias is studied on ribosomal protein-related genes and shows an evident influence by the marine extreme environment. Furthermore, focusing on the marine environmental differences such as light intensity, dissolved oxygen, temperature and pressure among various depths, comparative analysis is carried out on related genes and metabolic pathways. Thus, the understanding as well as new insights into the correlation between marine environment and microbes are proposed at molecular level. Therefore, the studies herein afford a clue to reveal the special living strategies of microbial community from sea surface to deep sea.