黑眉锦蛇消化道6种酶的组织化学定位

目的研究黑眉锦蛇消化道酸性磷酸酶(ACP)、碱性磷酸酶(ALP)、过氧化物酶(POX)、非特异性酯酶(NSE)、腺苷三磷酸酶(ATPase)、琥珀酸脱氢酶(SDH)等酶的分布。方法消化道分8个部位取材,应用冰冻切片、石蜡切片、酶组织化学技术及光密度定量分析。结果 ACP主要分布于十二指肠至回肠的黏膜上皮,十二指肠和空肠酶活性显著较高(P<0.05);ALP分布于食管、十二指肠至回肠的黏膜上皮,十二指肠酶活性最高(P<0.05);POX和NSE在整个消化道黏膜上皮和黏膜固有层中均有分布,胃幽门和直肠酶活性较低(P<0.05);ATPase在消化道除直肠未检测到酶活性外,其它部位均有分布,以十二指肠酶活性最高(P<0.05);SDH除食管未检测到酶活性外,其它部位均有分布,胃中胃腺部酶活性较高(P<0.05)。结论黑眉锦蛇消化道黏膜酶的分布同其它动物有相似之处,也有其自身特点。不同酶的分布和消化道各部位的生理机能密切相关。     

Genetic variation of the Chinese longsnout catfish Leiocassis longirostris in the Yangtze River revealed using mitochondrial DNA cytochrome b sequences

The mitochondrial DNA cytochrome b of 132 Leiocassis longirostris collected from 12 localities in the upper to lower reaches of the Yangtze River were amplified and partially sequenced using the PCR technique. The results showed that 27 nucleotide sites were variable along 817 bp length of homologous sequence (3.3%), base substitutions happened mostly at the third codon position. A total of 22 haplotypes were identified, which were characterized with moderate haplotype diversity (h = 0.5417 ± 0.0519), but low nucleotide diversity (π = 0.0019 ± 0.0012). Median-joining network analysis revealed star-shaped patterns with one common central haplotype (H3), whereas mismatch distribution analysis found that the Chinese longsnout catfish fitted a smooth unimodal distribution, which suggested that this species underwent population expansion following bottlenecks and/or they originated from a small number of founding individuals. The time that the total population of Chinese longsnout catfish in the Yangtze River expanded was estimated 169,000–337,000 years before present. The analysis of molecular variance (AMOVA) and phylogenetic reconstructions did not detect significant geographic structure between different river sections, especially between above and below the Gezhouba Dam and the Three Gorges Dam, which suggested that these recently developed dams might have not significantly resulted in population genetic differentiation in the Chinese longsnout catfish.     

Chromosome-level wild Hevea brasiliensis genome provides new tools for genomic-assisted breeding and valuable loci to elevate rubber yield

The rubber tree (Hevea brasiliensis) is grown in tropical regions and is the major source of natural rubber. Using traditional breeding approaches, the latex yield has increased by sixfold in the last century. However, the underlying genetic basis of rubber yield improvement is largely unknown. Here, we present a high-quality, chromosome-level genome sequence of the wild rubber tree, the first report on selection signatures and a genome-wide association study (GWAS) of its yield traits. Population genomic analysis revealed a moderate population divergence between the Wickham clones and wild accessions. Interestingly, it is suggestive that H. brasiliensis and six relatives of the Hevea genus might belong to the same species. The selective sweep analysis found 361 obvious signatures in the domesticated clones associated with 245 genes. In a 15-year field trial, GWAS identified 155 marker–trait associations with latex yield, in which 326 candidate genes were found. Notably, six genes related to sugar transport and metabolism, and four genes related to ethylene biosynthesis and signalling are associated with latex yield. The homozygote frequencies of the causal nonsynonymous SNPs have been greatly increased under selection, which may have contributed to the fast latex yield improvement during the short domestication history. Our study provides insights into the genetic basis of the latex yield trait and has implications for genomic-assisted breeding by offering valuable resources in this new domesticated crop.     

Deep Sequencing Identifies Tissue-Specific MicroRNAs and Their Target Genes Involving in the Biosynthesis of Tanshinones in Salvia miltiorrhiza

Salvia miltiorrhiza is one of the most popular traditional medicinal herbs in Asian nations. Its dried root contains a number of tanshinones, protocatechuic aldehyde, salvianolic acid B and rosmarinic, and is used for the treatment of various diseases. The finding of microRNAs (miRNAs) and their target genes will help understand their biological role on the biosynthesis of tanshinones in S. miltiorrhiza. In the present study, a total of 452 known miRNAs corresponding to 589 precursor miRNAs (pre-miRNAs), and 40 novel miRNAs corresponding to 24 pre-miRNAs were identified in different tissues of S. miltiorrhiza by high-throughput sequencing, respectively. Among them, 62 miRNAs express only in root, 95 miRNAs express only in stem, 19 miRNAs express only in leaf, and 71 miRNAs express only in flower, respectively. By the degradome analysis, 69 targets potentially cleaved by 25 miRNAs were identified. Among them, acetyl-CoA C-acetyltransferase was cleaved by miR5072, and involved in the biosynthesis of tanshinones. This study provided valuable information for understanding the tissue-specific expression patterns of miRNAs in S. miltiorrhiza, and offered a foundation for future studies of the miRNA-mediated biosynthesis of tanshinones.     

TRPM2 Channels Protect against Cardiac Ischemia-Reperfusion Injury: ROLE OF MITOCHONDRIA*

Cardiac TRPM2 channels were activated by intracellular adenosine diphosphate-ribose and blocked by flufenamic acid. In adult cardiac myocytes the ratio of G_Ca to G_Na of TRPM2 channels was 0.56 ± 0.02. To explore the cellular mechanisms by which TRPM2 channels protect against cardiac ischemia/reperfusion (I/R) injury, we analyzed proteomes from WT and TRPM2 KO hearts subjected to I/R. The canonical pathways that exhibited the largest difference between WT-I/R and KO-I/R hearts were mitochondrial dysfunction and the tricarboxylic acid cycle. Complexes I, III, and IV were down-regulated, whereas complexes II and V were up-regulated in KO-I/R compared with WT-I/R hearts. Western blots confirmed reduced expression of the Complex I subunit and other mitochondria-associated proteins in KO-I/R hearts. Bioenergetic analyses revealed that KO myocytes had a lower mitochondrial membrane potential, mitochondrial Ca²⁺ uptake, ATP levels, and O₂ consumption but higher mitochondrial superoxide levels. Additionally, mitochondrial Ca²⁺ uniporter (MCU) currents were lower in KO myocytes, indicating reduced mitochondrial Ca²⁺ uptake was likely due to both lower ψ_m and MCU activity. Similar to isolated myocytes, O₂ consumption and ATP levels were also reduced in KO hearts. Under a simulated I/R model, aberrant mitochondrial bioenergetics was exacerbated in KO myocytes. Reactive oxygen species levels were also significantly higher in KO-I/R compared with WT-I/R heart slices, consistent with mitochondrial dysfunction in KO-I/R hearts. We conclude that TRPM2 channels protect the heart from I/R injury by ameliorating mitochondrial dysfunction and reducing reactive oxygen species levels.     

Antibiotic stress-induced modulation of the endoribonucleolytic activity of RNase III and RNase G confers resistance to aminoglycoside antibiotics in Escherichia coli

Here, we report a resistance mechanism that is induced through the modulation of 16S ribosomal RNA (rRNA) processing on the exposure of Escherichia coli cells to aminoglycoside antibiotics. We observed decreased expression levels of RNase G associated with increased RNase III activity on rng mRNA in a subgroup of E. coli isolates that transiently acquired resistance to low levels of kanamycin or streptomycin. Analyses of 16S rRNA from the aminoglycoside-resistant E. coli cells, in addition to mutagenesis studies, demonstrated that the accumulation of 16S rRNA precursors containing 3–8 extra nucleotides at the 5’ terminus, which results from incomplete processing by RNase G, is responsible for the observed aminoglycoside resistance. Chemical protection, mass spectrometry analysis and cell-free translation assays revealed that the ribosomes from rng-deleted E. coli have decreased binding capacity for, and diminished sensitivity to, streptomycin and neomycin, compared with wild-type cells. It was observed that the deletion of rng had similar effects in Salmonella enterica serovar Typhimurium strain SL1344. Our findings suggest that modulation of the endoribonucleolytic activity of RNase III and RNase G constitutes a previously uncharacterized regulatory pathway for adaptive resistance in E. coli and related gram-negative bacteria to aminoglycoside antibiotics.     

海绵中石油降解微生物的分离筛选及降解特性研究

从大连湾原油污染海域生长的海绵中分离筛选到一株原油降解菌OA58,根据其生长形态、培养特征、16S rRNA序列相似性比对分析和生化指标检测,初步鉴定为脱叶链霉菌（Streptomyces exfoliatus）。同时,考察了该链霉菌对原油的降解效果,OA58能以原油为唯一碳源生长,在人工海水培养基中,14 d内对原油（初始浓度为1 g/L）的平均降解率为83%,是一株具有开发潜力的原油降解放线菌。     

AFLP analysis of genetic diversity and relationship among some Chinese domestic ducks and wild ducks

The amplified fragment length polymorphic(AFLP)technique was used to analyze the genome DNA polymorphism among 8 breeds of domestic ducks and 2 species of wild ducks.Nine of the 17 selected primers pairs gave reproducible polymorphic DNA amplification bands.The amplified bands ranged from 44 to 83 per primer pair.Of the 513 AFLP markers obtained.498 were polymorphic.The proportion of polymorphic loci was 97.1%.The genetic distance(D)and similarity coefficients(GS)were calculated based on the polymorphic data.Between domestic ducks D ranged from 0.331 to 0.589,while between domestic ducks and the wild ducks,it ranged from 0.298 to 0.520(vs.Anas Platyrhynchos)and from 0.316 to 0.522(vs.A.Poecilorhyncha),respectively.The variance analysis showed no significant difference between the two groups of data,which indicated that both mallard and spot-billed ducks made contributions to domestic duck evolution.A dendrogram was constructed according to the D value.     

小麦品种联合试验效应及理论依据──Ⅰ.试验的地点环境效应

本文利用小麦品种区域试验材料,研究了联合试验地点对品种适应性鉴定的致变能力以及对试验区域的代表性,讨论了试验的效果．