Molecular cloning and functional characterization of the fatty acid delta 6 desaturase (FAD6) gene in the sea cucumber Apostichopus japonicus

The sea cucumber (Apostichopus japonicus), an important echinodermata, had high value in nutrition and medicine for its rich collagen, sulphated polysaccharide, glycosides and polyunsaturated fatty acids (PUFA). The cDNA of the fatty acid desaturase gene in A. japonicus (AJFAD6) was cloned and was found to encode a desaturase with delta 6 FAD activity. Sequence analysis indicated that AJFAD6 included an open reading frame of 1392 bp, encoding 463 amino acids. AJFAD6 has all the conserved motifs found in other members of the FAD6 family, including an N‐terminal cytochrome b5 domain and three histidine‐rich regions. qRT‐PCR showed that AJFAD6 was expressed in all tissues tested during juvenile development and was mainly expressed in the respiratory tree at 150 days after adherence (150 days) and in the intestine at 100 days. Furthermore, AJFAD6 mRNA was also detected in the analysed adult tissues, with higher expression in the intestine and testis. Functional characterization of AJFAD6 in a recombinant yeast, Pichia pastoris, showed that AJFAD6 could catalyse exogenous linoleic acid (LA) and α‐linolenic acid (ALA) to produce γ‐linoleic acid (GLA) and stearidonic acid (STA), respectively, at conversion rates of 11.1% for LA to GLA and 3.4% for ALA to STA. Our results suggested that the biosynthetic pathway of PUFA existed in the sea cucumber, but endogenous production of eicosapentaenoic acid, arachidonic acid and docosahexaenoic acid from either LA or ALA precursor appeared to be limited.     

Effect of substitution of dietary fish meal by soybean meal on different sizes of gibel carp (Carassius auratus gibelio): digestive enzyme gene expressions and activities,and intestinal and hepatic histology

A 7‐week growth trial was conducted to evaluate the effects of dietary soybean meal (SBM) on digestive enzyme activity of intestinal mucosa, mRNA levels of digestive enzymes in hepatopancreas, and the mid‐intestinal and hepatopancreas histology of gibel carp CAS III (Carassius auratus gibelio). Four different growth phases of gibel carp (initial body weight: fry, 0.8 g; juvenile, 5.0 g; 1‐year‐old, 62.7 g; and broodstock, 135.6 g) were tested. Seven isonitrogenous and iso‐energetic diets were formulated to contain different SBM replacement levels (0%, 20%, 40%, 60%, 80% and 100% of dietary fish meal protein), and another diet (SBMAA) contained all SBM protein and supplied crystalline amino acids. The results showed that the activities of mid‐intestine trypsin, α‐amylase and gamma glutamyl transpeptidase reduced with increased dietary SBM, while the chymotrypsin activity increased first and then decreased. The ultrastructures of intestinal epithelial cells and hepatopancreas cells in fry and broodstock fish were distinctly affected by 200 g kg^‐1 dietary SBM. Supplementation of dietary amino acid to the highest replacement groups was not sufficient to improve digestive and absorptive capacities and growth performance. Gibel carp may be adapted to dietary SBM through increase in gene expression of hepatopancreas digestive enzymes and has potential to utilize proceeded SBM as feedstuffs.     

5种蔷薇科树种多酚氧化酶比较基因组学分析

蔷薇科植物中有多种具有重要价值的水果,如苹果、梨、桃、草莓和黑树莓等。这些水果普遍容易发生由多酚氧化酶(PPO)介导的酶促褐变而导致重大经济损失,从全基因组角度分析比较PPO基因家族,有助于加深对PPO基因家族和功能的认识。采用比较基因组学的方法,对这5种植物的PPO基因家族进行了基因鉴定、染色体定位、编码蛋白的亚细胞定位、内含子统计分析、基因系统进化、基因倍增与丢失等特征分析。从这5种植物中,共计鉴定出了42个PPO基因,其中6个基因被认定是假基因;绝大多数基因编码的蛋白定位于叶绿体,2个定位于线粒体,3个是分泌型蛋白;PPO基因在染色体上有串联重复和散布两种形式;9个基因具有内含子,聚类结果显示可以将它们分为6个类型,每个基因类型在进化过程中都发生过基因倍增和丢失;同型基因内含子的位置和大小具有相似性。这些结果揭示蔷薇科植物PPO基因内含子是伴随着基因倍增产生的,基因倍增也是推动PPO基因多样化的重要动力,PPO基因倍增和丢失差异导致PPO基因数量在不同物种之间产生差异。     

Life cycle inference and phylogeny of Ortholinea labracis n. sp. (Myxosporea: Ortholineidae), a parasite of the European seabass Dicentrarchus labrax (Teleostei: Moronidae), in a Portuguese fish farm

Ortholinea labracis n. sp. is described and its life cycle is inferred from a Southern Portuguese fish farm, with basis on microscopic and molecular procedures. This myxosporean parasite infects the urinary bladder of the European seabass Dicentrarchus labrax and the intestinal epithelium of a marine oligochaete of the genus Tectidrilus. Myxospores subspherical in valvular view and ellipsoidal in sutural view measuring 7.6 ± 0.3 (6.8–8.7) μm in length, 7.2 ± 0.2 (6.7–7.7) μm in width and 6.5 ± 0.4 (5.8–7.7) μm in thickness. Two polar capsules, 3.0 ± 0.2 (2.6–3.4) μm long and 2.4 ± 0.1 (2.0–2.9) μm wide, located at the same level, but with divergent orientation and opening to opposite sides of the suture line. Sequencing of the SSU rRNA gene revealed a similarity of 100% between the analysed myxospores and triactinomyxon actinospores. The phylogenetic setting of O. labracis n. sp. shows subgrouping in correlation with tissue tropism, but identifies this parasite as another exception to the main division of Myxosporea into the main freshwater and marine lineages.     

大豆PAL2-3基因的克隆及转化研究

大豆异黄酮是苯丙氨酸代谢途径中合成的一类次级代谢产物,在苯丙氨酸代谢途径中,苯丙氨酸解氨酶(PAL)是关键酶和限速酶。本课题组前期研究发现PAL基因的相对表达量与大豆异黄酮含量具有明显的协同增减趋势,并且在PAL基因家族成员时空表达模式分析中发现,PAL2-3(XM_003542493)是PAL基因家族中相对表达量较高的主要表达成员之一。本试验首先通过克隆大豆中PAL2-3基因;然后构建pCAMBIA3301-GmPAL2-3植物过表达载体,将构建好的pCAMBIA3301-GmPAL2-3表达载体重组质粒转化到根癌农杆菌EHA105中;采用农杆菌介导的大豆子叶节转化体系获得转化植株,并对T1代转化植株进行PPT检测,外源标记基因Bar检测以及荧光定量PCR检测,对转基因阳性植株进行大豆籽粒异黄酮含量的测定。结果表明T_1代转基因植株中PAL2-3基因的表达量是对照的5.11~11.24倍,总异黄酮含量最高的(2 587.63μg·g~(-1))是对照(1 616.90μg·g~(-1))的1.6倍。因此在大豆中过量表达PAL2-3基因可以提高大豆籽粒中异黄酮含量。     

A Genome-Wide Association Study Reveals Differences in the Genetic Mechanism of Control of the Two Gait Patterns of the Brazilian Mangalarga Marchador Breed

The DMRT3 gene is described as the main gene involved in the determination of gait phenotypes in horses, and the allele A of the 22999655C>A single nucleotide polymorphisms (SNP) has been reported as a causal variant of this trait. In the Mangalarga Marchador breed, which exhibits two gait patterns with well-defined characteristics, genotypes AA and CA are associated with marcha picada and genotype CC with marcha batida. In this breed, allele A of the DMRT3 gene is only related to the marcha picada gait. The objective of this study was to identify the type of control of the marcha batida gait and to investigate SNPs and genomic regions responsible for this phenotype in Mangalarga Marchador horses. Forty-eight horses belonging to the two gait groups, marcha picada with AA and CA genotypes of the 22999655C>A SNP (n = 20) and marcha batida with CC genotype (n = 28), were analyzed using the Equine SNP70 BeadChip. The genome-wide association study result shows for the first time that, in contrast to the marcha picada gait phenotype that is apparently determined by a single gene (DMRT3) in which allele A of variant g.22999655C>A controls the trait, the marcha batida gait is controlled by a larger number of genes. Because of the small number of animals used in the two groups compared, the genomic regions associated with smaller effects on the marcha batida gait could not be identified.     

斑节对虾Chitinase-2基因的克隆及其在蜕皮和幼体发育过程中的表达分析

研究以斑节对虾(Penaeus monodon)转录组获得的几丁质酶基因(Pm Chi)片段,运用RACE技术克隆了PmChi基因c DNA全长,命名为PmChi-2。PmChi-2基因c DNA全长2 050 bp,其中5'-非编码区(5'-UTR)144 bp、3'-UTR 319 bp和开放阅读框(ORF)1 587 bp,编码528个氨基酸。生物信息学分析显示,PmChi-2与其他甲壳动物Chi-2的相似性为78%~97%。实时荧光定量PCR结果显示,PmChi-2在蜕皮前期(D期)表皮中表达水平最高,在胃、鳃、腹神经节和眼柄中表达水平依次降低,在其他组织(肝胰腺、肠、肌肉、心脏)中几乎不表达。不同蜕皮阶段,PmChi-2在鳃、胃和表皮3种组织中的表达变化模式基本一致,均在蜕皮期(E期)表达量最低,而最高表达量在鳃中出现在蜕皮后期(A期),在胃和表皮中为D期。幼体不同发育阶段分析揭示PmChi-2 mRNA在幼体发育阶段的无节幼体到糠虾幼体第二期表达量维持在一个低水平,在糠虾幼体第三期PmChi-2 mRNA表达水平显著升高,在仔虾期又显著下降,推测PmChi-2 mRNA可能与斑节对虾幼体发育密切相关。研究结果表明PmChi-2基因可能在斑节对虾蜕皮以及幼体的变态发育中发挥重要作用,为深入研究斑节对虾几丁质酶发育调控提供了重要信息。