肠道噬菌体组与人体健康

噬菌体作为肠道微生物群落的重要组成部分,自生命初期即定植于肠道,在不同生命时期均以较为稳定的状态存在于人体。目前已知的肠道噬菌体主要是DNA噬菌体,且大多以前噬菌体形式存在。肠道噬菌体可通过多种机制优化其宿主微生物群的结构和组成,并以多种方式直接或间接影响人体的生理状态,其结构变化与多种疾病相关。利用测序方法,能够直接获取噬菌体组信息。本文基于噬菌体组的相关研究,综述了肠道噬菌体组与人体健康相关的研究进展,并对该领域的研究方法和发展方向做出展望。     

Radiosynthesis and evaluation of a fluorine-18 labeled radioligand targeting vesicular acetylcholine transporter

Vesicular acetylcholine transporter (VAChT) is a reliable biomarker for assessing the loss of cholinergic neurons in the brain that is associated with cognitive impairment of patients. 5-Hydrotetralin compound (±)-5-OH-VAT is potent (K_i?=?4.64?±?0.32?nM) and selective for VAChT (>1800-fold and 398-fold for σ₁ and σ₂ receptor, respectively) with favorable hydrophilicity (LogD?=?1.78), while (?)-5-OH-VAT originally serves as the radiolabeling precursor of (?)-[¹⁸F]VAT, a promising VAChT radiotracer with a logD value of 2.56. To evaluate (?)-5-OH-[¹⁸F]VAT as a radiotracer for VAChT, we performed in vitro binding assay to determine the potency of the minus enantiomer (?)-5-OH-VAT and plus enantiomer (+)-5-OH-VAT, indicating that (?)-5-OH-VAT is a more potent VAChT enantiomer. Radiosynthesis of (?)-5-OH-[¹⁸F]VAT was explored using three strategies. (?)-5-OH-[¹⁸F]VAT was achieved with a good yield (24?±?6%) and high molar activity (～37?GBq/µmol, at the end of synthesis) using a microwave assisted two-step one-pot procedure that started with di-MOM protected nitro-containing precursor (?)-6. MicroPET studies in the brain of nonhuman primate (NHP) suggest that (?)-5-OH-[¹⁸F]VAT readily penetrated the blood brain barrier and specifically accumulated in the VAChT-enriched striatum with improved washout kinetics from striatum compared to [¹⁸F]VAT. Nevertheless, the lower target to non-target ratio may limit its use for in vivo measurement of the VAChT level in the brain.     

High-mobility-group family genes from Lampetra japonica reveal their early origin and molecular evolution in the vertebrate lineage

High-mobility group family (HMG) genes are ubiquitous in vertebrates, including mammals, birds, amphibians and fishes. To elucidate the molecular phylogeny of the HMG genes in the primitive vertebrate, we have cloned three homologues of HMG-box genes, called Lj-HMGB1, Lj-HMGB2 and Lj-HMGBX, from a cDNA library generated from lymphocyte-like cells of the Japanese lamprey (Lampetra japonica), an Agnathan that occupies a critical phylogenetic position between invertebrates and vertebrates. The open reading frames of Lj-HMGB1, Lj-HMGB2 and Lj-HMGBX contained 627 bp, 585 bp and 678 bp, respectively. The analysis of the deduced amino acid sequences indicated that these three putative Lj-HMGB proteins contain four domains: HMG-box A, HMG-box B, an acidic carboxyl-terminal tail and a linker. A phylogenetic analysis revealed that the Lj-HMGB proteins fall outside the vertebrate clade; Lj-HMGBX is descended from a gene ancestral to the mammalian HMGB1/2/3. This discovery implies that there was a gene duplication event in the HMGB1/2/3 gene family that occurred after the divergence of the vertebrates (Cyclostomata) from the Cephalochordata and Urochordata at least 450 million years ago (MYA). The Lj-HMGB1, Lj-HMGB2 and Lj-HMGBX genes were detected in most tissues of the lamprey by RT-PCR. Our findings provide insight into the phylogeny of the HMGB genes in vertebrates.     

Physiological and fermentation properties of <Emphasis Type="Italic">Bacillus coagulans</Emphasis> and a mutant lacking fermentative lactate dehydrogenase activity

Bacillus coagulans, a sporogenic lactic acid bacterium, grows optimally at 50–55°C and produces lactic acid as the primary fermentation product from both hexoses and pentoses. The amount of fungal cellulases required for simultaneous saccharification and fermentation (SSF) at 55°C was previously reported to be three to four times lower than for SSF at the optimum growth temperature for Saccharomyces cerevisiae of 35°C. An ethanologenic B. coagulans is expected to lower the cellulase loading and production cost of cellulosic ethanol due to SSF at 55°C. As a first step towards developing B. coagulans as an ethanologenic microbial biocatalyst, activity of the primary fermentation enzyme L-lactate dehydrogenase was removed by mutation (strain Suy27). Strain Suy27 produced ethanol as the main fermentation product from glucose during growth at pH 7.0 (0.33 g ethanol per g glucose fermented). Pyruvate dehydrogenase (PDH) and alcohol dehydrogenase (ADH) acting in series contributed to about 55% of the ethanol produced by this mutant while pyruvate formate lyase and ADH were responsible for the remainder. Due to the absence of PDH activity in B. coagulans during fermentative growth at pH 5.0, the l-ldh mutant failed to grow anaerobically at pH 5.0. Strain Suy27-13, a derivative of the l-ldh mutant strain Suy27, that produced PDH activity during anaerobic growth at pH 5.0 grew at this pH and also produced ethanol as the fermentation product (0.39 g per g glucose). These results show that construction of an ethanologenic B. coagulans requires optimal expression of PDH activity in addition to the removal of the LDH activity to support growth and ethanol production.     

Evidence for a quantitative trait locus affecting low levels of apolipoprotein B and low density lipoprotein on chromosome 10 in Caucasian families

High plasma apolipoprotein B (apoB) and LDL cholesterol levels increase cardiovascular disease risk. These highly correlated measures may be partially controlled by common genetic polymorphisms. To identify chromosomal regions that contain genes causing low plasma levels of one or both parameters in Caucasian families ascertained for familial hypobetalipoproteinemia (FHBL), we conducted a whole-genome scan using 443 microsatellite markers typed in nine multigenerational families with at least two members with FHBL. Both variance components and regression-based linkage methods were used to identify regions of interest. Common linkage regions were identified for both measures on chromosomes 10q25.1-10q26.11 [maximum log of the odds (LOD) = 4.2 for LDL and 3.5 for apoB] and 6q24.3 (maximum LOD = 1.46 for LDL and 1.84 for apoB). There was also evidence for linkage to apoB on chromosome 13q13.2 (LOD = 1.97) and to LDL on chromosome 3p14.1 at 94 centimorgan (LOD = 1.52). Bivariate linkage analysis provided further evidence for loci contributing to both traits (6q24.3, LOD = 1.43; 10q25.1, LOD = 1.74). We evaluated single nucleotide polymorphisms (SNPs) in genes within our linkage regions to identify variants associated with apoB or LDL levels. The most significant finding was for rs2277205 in the 5' untranslated region of acyl-coenzyme A dehydrogenase short/branched chain and LDL (P = 10(-7)). Three additional SNPs were associated with apoB and/or LDL (P < 0.01). Although only the linkage signal on chromosome 10 reached genome-wide statistical significance, there are likely multiple chromosomal regions with variants that contribute to low levels of apoB and LDL and that may protect against coronary heart disease.     

氨肽酶N的表达及其与结石形成的关系(英文)

 为研究大鼠高胆固醇饮食时 ,肝脏氨肽酶N(APN)在实验结石形成中可能的结石发生作用 ,采用 1.2 %胆固醇饮食 4周 ,诱发新西兰兔胆囊结石形成 .根据兔APN基因cDNA序列设计引物 ,提取肝脏总RNA .利用RT PCR检测肝脏APNmRNA水平的变化 ,用组织化学方法观察肝脏毛细胆管膜上APN的表达 .观察新西兰兔胆囊结石形成过程中肝脏APN的mRNA水平的变化、APN表达及胆汁中APN活性、胆脂、总蛋白含量的变化 ,探讨APN在胆石形成中可能的作用 .经成石饲料饲养后 ,随着胆汁饱和度增加和APN活性加强 ,胆囊结石组肝脏APNmRNA水平较对照组明显增高 ,胆囊结石组胆汁中总胆固醇、CSI、总蛋白浓度及APN活性均明显高于对照组 ,且胆汁中APN活性与肝脏APN的表达及胆汁CSI增高呈正相关 .结果提示 ,当存在胆汁过饱和的情况下 ,APN很可能作为促成核因子在胆结石形成早期发挥重要作用     

RNAi knockdown of Oryza sativa root meander curling gene led to altered root development and coiling which were mediated by jasmonic acid signalling in rice

Jasmonic acid (JA) is a well-known defence hormone, but its biological function and mechanism in rice root development are less understood. Here, we describe a JA-induced putative receptor-like protein (OsRLK, AAL87185) functioning in root development in rice. RNA in situ hybridization revealed that the gene was expressed largely in roots, and a fusion protein showed its localization on the plasma membrane. The primary roots in RNAi transgenic rice plants meandered and curled more easily than wild-type (WT) roots under JA treatment. Thus, this gene was renamed Oryza sativa root meander curling (OsRMC). The transgenic primary roots were shorter, the number of adventitious roots increased and the number of lateral roots decreased as compared to the WT. As well, the second sheath was reduced in length. Growth of both primary roots and second sheaths was sensitive to JA treatment. No significant change of JA level appeared in the roots between the transgenic rice line and WT. Expression of RSOsPR10, involved in the JA signalling pathway, was induced in transgenic rice. Western blotting revealed OsRMC induced by JA. Our results suggest that OsRMC of the DUF26 subfamily involved in JA signal transduction mediates root development and negatively regulates root curling in rice.     

A reliable, non-invasive PCR method for giant panda (Ailuropoda melanoleuca) sex identification

We developed an inexpensive, fast and reliable PCR method for sex identification of giant panda (Ailuropoda melanoleuca) by using one pair of primers to co-amplify homologous fragments with size polymorphism that located at amelogenin (AMEL) exon 5. In giant panda, a 63 bp deletion in exon 5 of Y-linked allele provides a significant discrimination between AMELX and AMELY, thus the amplification products can be distinguished simply by agarose gel electrophoresis, exhibiting sex-specific banding patterns (male: 237 bp, 174 bp; female: 237 bp). Both blood and feces samples from known-sex giant pandas were successfully amplified. Cross species test also revealed that this method could be applied to other Ursidae species. These authors contributed equally to this work.     

单核细胞增生李斯特菌PrfA蛋白转录调控毒力基因表达的分子机制

单核细胞增生李斯特菌 (Listeria monocytogenes LM) 属于典型的细胞内寄生革兰氏阳性菌, 是WHO公布的四大食源性致病菌之一。LM不仅是人畜共患传染病李斯特菌病 (listeriosis) 的主要病原菌, 也是研究胞内感染和细胞介导的免疫应答的模式细菌。绝大多数LM毒力基因的转录表达受到PrfA蛋白的调控。本文简单介绍了LM侵染宿主细胞必需的毒力基因及其产物; 重点对毒力基因调节蛋白PrfA的结构和功能, PrfA调节毒力基因表达的主要方式最新进展进行了综述和讨论。     

Genetic differentiation of Pseudoregma bambucicola population based on mtDNA COII gene

mtDNA COII gene sequences were identified and analyzed using different types of software, namely, MEGA5.0, DNAMAN, and DnaSP5.0 in four Chinese provinces, namely, Sichuan, Zhejiang, Guizhou and Shanghai. Analysis of molecular genetic variation and its genetic structure and differentiation, combined with NJ tree, MP tree analysis and analysis of molecular variance (AMOVA), at Fst = 0.0582 conclude that the genetic differentiation is low, gene flow is Nm = 8.0911, and gene exchange is sufficient. However, for the geographic populations of Pseudoregma bambucicola in the four provinces, their gene exchange is relatively weak at Nm = 0.8284, whereas the genetic differentiation is high at Fst = 0.3764. Based on the data, total nucleotide diversity between the populations is 0.00158 ± 0.00021. The results showed that the total population of Tajima’s D and Fu’s Fs results are D = ?0.885 and Fs = 0.226, respectively. The experimental numerical results showed that this total population is not significant (P > 0.10), indicating that nine different geographic populations are short-term. No expansion occurred in the internal population. This study provided a theoretical and practical basis for the comprehensive prevention and control of P. bambucicola.