Whole-genome shotgun assembly and analysis of the genome of Fugu rubripes

The compact genome of Fugu rubripes has been sequenced to over 95% coverage, and more than 80% of the assembly is in multigene-sized scaffolds. In this 365-megabase vertebrate genome, repetitive DNA accounts for less than one-sixth of the sequence, and gene loci occupy about one-third of the genome. As with the human genome, gene loci are not evenly distributed, but are clustered into sparse and dense regions. Some "giant" genes were observed that had average coding sequence sizes but were spread over genomic lengths significantly larger than those of their human orthologs. Although three-quarters of predicted human proteins have a strong match to Fugu, approximately a quarter of the human proteins had highly diverged from or had no pufferfish homologs, highlighting the extent of protein evolution in the 450 million years since teleosts and mammals diverged. Conserved linkages between Fugu and human genes indicate the preservation of chromosomal segments from the common vertebrate ancestor, but with considerable scrambling of gene order.     

一株猪丹毒丝菌的全基因组测序及SpaA基因分析

本研究测定猪丹毒丝菌临床毒株SG7的全基因组序列,并运用生物信息学方法对测定的全基因组序列及猪丹毒丝菌表面保护性抗原A基因(SpaA)进行分析.SG7菌株的基因组全长为1834291.00 bp,G+C含量为36.3％,基因总数1846个.将SG7菌株与GenBank中8条完整的猪丹毒丝菌全基因组序列进行比较,发现国内...     

转Bt基因对水稻内生原核微生物定殖数量效应分析

为探讨转Bt基因对水稻内生原核微生物定殖的数量效应,首先确定水稻根、茎、叶表面微生物的消毒时间和条件;其次,在有效排除水稻植株表面微生物干扰的条件下,应用纯培养方法对转Bt基因及其亲本水稻各组织的内生原核微生物定殖数量进行检测分析,初步评估各亲本水稻在引入外源Bt基因后,给水稻植株内生原核微生物数量带来的影响。结果显示,水稻根际微生物以70%乙醇浸泡7 min,茎和叶表面微生物以70%乙醇浸泡2 min,以无菌水漂洗2次,可达到杀灭表面微生物的效果。本次试验中,ZJ-22和明恢63两个水稻品系亲本植株根、茎的内生原核微生物定殖数量,在苗期和分蘖期时均高于对应的转Bt基因植株(ZJ-22Bt和TT51-1);苗期时两个品系亲本水稻叶片内生微生物数量同样高于转Bt基因水稻,分裂期转Bt水稻TT51-1叶片内生原核微生物数量则多于其亲本植株明恢63。以上结果表明,两个品系亲本水稻插入外源基因后,在苗期和分裂期对亲本植株各部位的内生原核微生物定殖情况均产生了一定的影响。     

解脂耶氏酵母合成萜烯的进展: 见微知著的改造策略

目的比较酿酒酵母和解脂耶氏酵母对不同酚酸的耐受性。方法以酿酒酵母和解脂耶氏酵母为材料,通过加入不同浓度的对羟基苯丙酸、咖啡酸、对香豆酸、阿魏酸和肉桂酸测定2种酵母的生长情况。结果2种酵母对不同酚酸的耐受性趋势一致,耐受性表现为对羟基苯丙酸=咖啡酸>对香豆酸>阿魏酸>肉桂酸;解脂耶氏酵母对酚酸的耐受性大于酿酒酵母,更适合用于生产芳香氨基酸衍生物,尤其是肉桂酸类衍生物的生物合成。结论解脂耶氏酵母对酚酸的耐受性更大,为应用酵母合成黄酮类化合物以及从苯丙氨酸和酪氨酸衍生生物碱提供了理论依据。     

一株牦牛源产细菌素植物乳杆菌SWUN5815全基因组测序及序列分析

旨在分析一株牦牛源植物乳杆菌SWUN5815的全基因组序列测序,并对该菌株的功能特性基因进行挖掘.基于PacBio RSII测序平台对乳杆菌SWUN5815进行全基因组测序分析和GO、KEGG、COG和NR数据库进行基因组基本功能注释.结果 表明:1)植物乳杆菌SWUN5815的基因组大小为3.27 Mb,GC含量44...     

杂交水稻光合特性胞质间差异分析

为了研究不同水稻雄性不育胞质的光合特性的差异规律,以生产上广泛应用的3 种不同胞质类型不育 系及其保持系配置的二元不育系为试材,测定其净光合速率、气孔导度和光合色素的含量。结果表明院各水稻组合间 的光合色素含量、净光合速率以及气孔导度均达到显著或极显著差异水平;不同类型细胞质之间的净光合速率差异 达到极显著水平,其中冈型胞质的水稻组合的Chla、Chlb 含量和净光合速率明显高于其他水稻组合,爪哇型胞质所 配套的杂交组合中胞质效应明显优于野败型胞质和冈型胞质。     

玉米、花生叶片光合效率比较分析

在大田条件下,研究了C4作物玉米和C3作物花生的光合速率(Pn)以及荧光参数的日变化,结果表明,C3和C4作物对光照度反应的灵敏性存在一定的差异．玉米的Pn日变化呈单峰曲线,其变化和光合有效辐射变化一致;而花生的Pn日变化呈双峰曲线,中午出现了明显的下降．玉米和花生的最大光化学效率(Fv/Fm)、实际光化学效率(ФPSⅡ)、光化学猝灭系数(qP)和非光化学猝灭(NPQ)存在明显的日变化,其中Fv/Fm,ФPSⅡ,qP呈倒抛物线型日变化,而NPQ则呈抛物线型日变化．C4作物玉米和C3作物花生的Pn,Fv/Fm,ФPSⅡ,qP,NPQ变化也存在明显差异,玉米具有较高的Pn,ФPSⅡ,NPQ和较低的Fv/Fm,qP,而花生具有较低的Pn,ФPSⅡ,NPQ和较高的Fv/Fm,qP,这些差异在日变化中以中午尤为明显.     

Whole-genome shotgun sequencing of mitochondria from ancient hair shafts

Although the application of sequencing-by-synthesis techniques to DNA extracted from bones has revolutionized the study of ancient DNA, it has been plagued by large fractions of contaminating environmental DNA. The genetic analyses of hair shafts could be a solution: We present 10 previously unexamined Siberian mammoth (Mammuthus primigenius) mitochondrial genomes, sequenced with up to 48-fold coverage. The observed levels of damage-derived sequencing errors were lower than those observed in previously published frozen bone samples, even though one of the specimens was >50,000 14C years old and another had been stored for 200 years at room temperature. The method therefore sets the stage for molecular-genetic analysis of museum collections.     

Eukaryotes versus prokaryotes: an estimate of evolutionary distance

The divergence of nucleated organisms and bacteria was 2.6 times more remote in evolution than the divergences of the nucleated organisms into sparate kingdoms, as evidenced by genetic changes in cytochrome c and transfer RNA. The development of the genetic code through the differentiation of transfer RNA's for different amino acids was still more remote in evolution. The overall states of transfer RNA evolution in bacteria and nucleated organisms were comparable.     

Ongoing modification of Mediterranean Pleistocene sapropels mediated by prokaryotes

Late Pleistocene organic-rich sediments (sapropels) from the eastern Mediterranean Sea harbor unknown, metabolically active chemoorganotrophic prokaryotes. As compared to the carbon-lean intermediate layers, sapropels exhibit elevated cell numbers, increased activities of hydrolytic exoenzymes, and increased anaerobic glucose degradation rates, suggesting that microbial carbon substrates originate from sapropel layers up to 217,000 years old. 16S ribosomal RNA gene analyses revealed that as-yet-uncultured green nonsulfur bacteria constitute up to 70% of the total microbial biomass. Crenarchaeota constitute a smaller fraction (on average, 16%). A slow but significant turnover of glucose could be detected. Apparently, sapropels are still altered by the metabolic activity of green nonsulfur bacteria and crenarchaeota.     

CRISPR provides acquired resistance against viruses in prokaryotes

Clustered regularly interspaced short palindromic repeats (CRISPR) are a distinctive feature of the genomes of most Bacteria and Archaea and are thought to be involved in resistance to bacteriophages. We found that, after viral challenge, bacteria integrated new spacers derived from phage genomic sequences. Removal or addition of particular spacers modified the phage-resistance phenotype of the cell. Thus, CRISPR, together with associated cas genes, provided resistance against phages, and resistance specificity is determined by spacer-phage sequence similarity.     

Whole-genome patterns of common DNA variation in three human populations

Individual differences in DNA sequence are the genetic basis of human variability. We have characterized whole-genome patterns of common human DNA variation by genotyping 1,586,383 single-nucleotide polymorphisms (SNPs) in 71 Americans of European, African, and Asian ancestry. Our results indicate that these SNPs capture most common genetic variation as a result of linkage disequilibrium, the correlation among common SNP alleles. We observe a strong correlation between extended regions of linkage disequilibrium and functional genomic elements. Our data provide a tool for exploring many questions that remain regarding the causal role of common human DNA variation in complex human traits and for investigating the nature of genetic variation within and between human populations.     

Intron existence predated the divergence of eukaryotes and prokaryotes

Nucleotide sequences for the nuclear genes encoding chloroplast (GapA and GapB) and cytosolic (GapC) glyceraldehyde-3-phosphate dehydrogenases (GAPDHs) from Arabidopsis thaliana were determined. Comparison of nucleotide sequences indicates that the divergence of chloroplast and cytosolic GAPDH genes preceded the divergence of prokaryotes and eukaryotes. In addition, some intron-exon junctions are conserved among GapB, GapC, and chicken GAPDH genes. These results provide evidence at the molecular level to support the idea that introns existed before the divergence of prokaryotes and eukaryotes.     

不同种源黄连木光合参数比较及聚类分析

光合参数是高光效种源选育和新品种培育的关键指标,而进行数值分类能够综合分析不同光合生理参数间的相互影响,从而有利于综合性状优良种质的选育。本试验通过用Li-6400光合仪测定18个种源黄连木的光合参数并对其进行数值分类以及主成分、聚类和判别分析,旨在筛选出黄连木综合性状优质种源。结果表明:通过对18个种源黄连木净光合速率的聚类分析,筛选出西陵、管头、坨南、绛县、临淇、原康、东姚和滁州8个高光合速率的黄连木种源;通过对净光合速率和水分利用效率2个指标进行聚类分析,发现上述8个种源亦可用于高光效和耐旱品种的培育;利用主成分分析筛选出的对不同种源黄连木光合性状分类有显著影响的3个光合参数(Pn、Tr、WUE)进行聚类分析,筛选出西陵、坨南、绛县、临淇、东姚和滁州6个综合光合性能良好的优异黄连木种质。     

阴、阳结合型温室葡萄浆果发育过程中光合作用的比较

对阴、阳结合型温室内红地球葡萄果粒生长的4个物候期的光合作用进行测定.结果表明,自然光照下,在果粒发育过程中,蒸腾速率、气孔导度和胞间CO2均表现为阴棚低于阳棚,而光合速率在不同物候期的变化不同:幼果期,阴棚呈单峰型,阳棚呈双峰型,2棚光合速率的下降均受气孔和非气孔的限制;膨大期,阴、阳棚均呈双峰型,阴棚光合速率的下降均受气孔和非气孔限制,而阳棚主要受气孔限制;转色期,阴棚呈双峰型,阳棚呈单峰型,阴棚光合速率的下降主要受非气孔限制,而阳棚均受气孔和非气孔限制;成熟期,阴、阳棚均呈单峰型,阴棚光合速率的下降受气孔和非气孔限制,而阳棚主要受非气孔限制.经方差分析,光合速率及光合参数的差异性没有达到显著水平,说明阴、阳棚对葡萄叶片的光合作用没有明显的影响.