病毒衣壳结构亚单位的种类数与三角形剖分数关系的研究和探讨

本文报道了在正廿面体病毒衣壳中,当蛋白结构亚单位以“三聚体”的形式聚集在单位三角形(?)时,其亚单位的种类数应等于该病毒的三角形剖分数值。     

Myokine IL-15 regulates the crosstalk of co-cultured porcine skeletal muscle satellite cells and preadipocytes

The present study was carried out to preliminarily reveal the underlying mechanisms of the co-culture system between porcine muscle satellite cells (SCs) and stromal-vascular cells (SVs). The two cell types were co-cultured to assess both proliferation and differentiation. Desmin and Pref-1 immunofluorescence staining technique were taken to identify the two types of isolated cells. The expression of specific marker genes Myogenin was up-regulated in SCs (P < 0.05) and the differentiation of SCs could be promoted when co-cultured with preadipocytes compared with the single-cultured control, while expression of c/EBPβ in SVs was down-regulated (P < 0.05) and the differentiation of preadipocytes could be inhibited. Furthermore, secretion of myokine IL-15 was markedly increased, as well as its gene and protein expression levels in co-culture supernatants. However, the secretion of adipokine leptin was significantly decreased. These findings demonstrate that myokines like IL-15 could facilitate the SCs’ differentiation while inhibit the SVs differentiation, and act as an important regulator of co-culture between muscle cells and adipocytes.     

Allele-specific targeting of hsa-miR-657 to human IGF2R creates a potential mechanism underlying the association of ACAA-insertion/deletion polymorphism with type 2 diabetes

The biological mechanism of a recent discovered association of type 2 diabetes with the ACAA-insertion/deletion polymorphism at the 3′UTR of the IGF2R gene has remained unclear. A very recently emerging novel polymorphic control layer by microRNAs (miRNAs) makes it possible to elucidate this issue. In this study, a prediction by web tools MicroInspector and miRanda demonstrated that DNA sequence polymorphism (DSPs) ACAA-insertion/deletion in IGF2R 3′UTR is located within the hsa-miR-657 and hsa-miR-453 binding sites. And luciferase reporter assay revealed that hsa-miR-657 acts directly at the 3′UTR of the IGF2R. Furthermore, ACAA-deletion exerted a further repression compared with ACAA-insertion, indicating that hsa-miR-657 regulates IGF2R gene expression in a polymorphic control manner. Importantly, we also demonstrated that hsa-miR-657 can translationally regulate the IGF2R expression levels in Hep G2 cells. Thus, our findings testify the possibility that the ACAA-insertion/deletion polymorphism may result in the change of IGF2R expression levels at least in part by hsa-miR-657-mediated regulation, contributing to the elucidation for the pathogenesis of type 2 diabetes and raise the possibility that miRNAs or in combination with functional DNA sequence polymorphism may be valuable in the treatment of human type 2 diabetes.     

Overexpression of phosphoenolpyruvate carboxylase from Jatropha curcas increases fatty acid accumulation in Nicotiana tabacum

Jatropha curcas L. is an excellent biofuel crop, which displays a high efficiency of carbon absorption, and seed oil of Jatropha can be efficiently processed to produce high-quality biodiesel. Plant phosphoenolpyruvate carboxylases (PEPCs) play important roles not only in initial fixation of atmospheric CO₂ in C₄ and Crassulacean acid metabolism (CAM) plants, but also in fatty acid biosynthesis in seeds of oil plants by regulating carbon partitioning. Here, we identified JcPEPC1 from J. curcas L. by homology cloning, and alignment analysis of protein sequence revealed JcPEPC1 was a plant C₃-type PEPC, and shared high similarity to PEPC of castor oil plant Ricinus communis. We implemented detailed functional characterization of JcPEPC1 by expression analysis and transgenic tobacco. JcPEPC1 gene expressed in the leaves and seeds of J. curcas L., and remarkable increase of expression level was also detected at seed oil-accumulating stages. We overexpressed JcPEPC1 in tobacco, and showed the enzymatic activity of PEPC in transgenic plants was notably higher than wild type. Gas chromatography (GC) analysis elucidated the composition and total content of fatty acids were also altered. This study indicated JcPEPC1 played a fundamental role in fatty acid biosynthesis in Jatropha seeds. Our results proposed enhanced PEPC activity of Jatropha could improve biosynthesis of fatty acid, which implied critical functions in primary metabolism of non-photosynthetic PEPC.     

Analysis of variable sites between two complete South China tiger (Panthera tigris amoyensis) mitochondrial genomes

In order to investigate the mitochondrial genome of Panthera tigris amoyensis, two South China tigers (P25 and P27) were analyzed following 15 cymt-specific primer sets. The entire mtDNA sequence was found to be 16,957 bp and 17,001 bp long for P25 and P27 respectively, and this difference in length between P25 and P27 occurred in the number of tandem repeats in the RS-3 segment of the control region. The structural characteristics of complete P. t. amoyensis mitochondrial genomes were also highly similar to those of P. uncia. Additionally, the rate of point mutation was only 0.3% and a total of 59 variable sites between P25 and P27 were found. Out of the 59 variable sites, 6 were located in 6 different tRNA genes, 6 in the 2 rRNA genes, 7 in non-coding regions (one located between tRNA-Asn and tRNA-Tyr and six in the D-loop), and 40 in 10 protein-coding genes. COI held the largest amount of variable sites (9 sites) and Cytb contained the highest variable rate (0.7%) in the complete sequences. Moreover, out of the 40 variable sites located in 10 protein-coding genes, 12 sites were nonsynonymous.     

Characterization and function analysis of a cold-induced AmCIP gene encoding a dehydrin-like protein in Ammopiptanthus mongolicus.

A cDNA clone was isolated after difference screening from cotyledons of two-week cold-treated Ammopiptanthus mongolicus. The full-length cDNA sequence [designated as AmCIP (A. mongolicus cold-induced protein) gene] was 806 bp long and contained a 465 bp open reading frame (ORF) encoding a 16.6 kD protein of 154 amino acids. Bioinformatic analyses indicated that CIP belongs to dehydrin family with the features of high hydrophilicity, a helix K-segment, a long Gly-rich region and a phosphorylatable tract of Ser as well as deficiency in Cys and Trp. The expression of CIP gene increased after two weeks of cold treatment and more expression was detected in radicle than in cotyledon. And PCR amplification of the AmCIP gene from genome of A. mongolicus revealed this gene has no intron. Function prediction suggested this protein seems to protect the stabilization of membrane structure and prevent macromolecular coagulation or sequestrate calcium ions by association or disassociation with membrane under low temperature conditions.     

鸡减蛋综合征病毒（EDSV—76）末端前体蛋白的基因结构分析

从中国发病鸡群中分离的鸡减蛋综合征病毒弱毒株ＡＡ－２,经常规方法提取其病毒核酸后,组建了完整的限制性内切酶ＰｓｔＩ及ＨｉｎｇⅢ水解片段的基因文库,并对其中ＨｉｎｄⅢ,－ＳａｃⅠ进行了序列测定。同源比较分析证明：其Ｌ链含编码病毒末端前体蛋白,容量为５８０个氨基酸残基的开放读码框架。     

Isolation and characterization of a mesophilic Arthrospira maxima strain capable of producing docosahexaenoic acid

A strain of the cyanobacterium Arthrospira was isolated from Lake Chahannaoer in northern China and was characterized according to microscopic morphology, photosynthetic oxygen-evolving activity, growth rate, and nutritional profile. Compared with thermophilic Arthrospira species occurring naturally in tropical and subtropical lakes, this isolate is mesophilic and grows optimally at ~20 degreesC. The total protein, fatty acid, phycocyanin, carotenoid, and chlorophyll a contents were 67.6, 6.1, 4.32, 0.29, and 0.76 grams per 100 grams of dry weight, respectively. The strain is rich in polyunsaturated fatty acids (PUFAs). An essential omega-3 fatty acid, docosahexaenoic acid (DHA), was detected, and gamma-linolenic acid (GLA) and DHA accounted for 28.3% of the total fatty acid content. These features of this newly isolated strain make it potentially useful in commercial mass culture in local areas or as a biofuel feedstock. It is also an alternative resource for studying the metabolic PUFA pathways and mechanisms of cold stress tolerance in cyanobacteria.