α‐ketoglutarate delays age‐related fertility decline in mammals

The fecundity reduction with aging is referred as the reproductive aging which comes earlier than that of chronological aging. Since humans have postponed their childbearing age, to prolong the reproductive age becomes urgent agenda for reproductive biologists. In the current study, we examined the potential associations of α‐ketoglutarate (α‐KG) and reproductive aging in mammals including mice, swine, and humans. There is a clear tendency of reduced α‐KG level with aging in the follicle fluids of human. To explore the mechanisms, mice were selected as the convenient animal model. It is observed that a long term of α‐KG administration preserves the ovarian function, the quality and quantity of oocytes as well as the telomere maintaining system in mice. α‐KG suppresses ATP synthase and alterations of the energy metabolism trigger the nutritional sensors to down‐regulate mTOR pathway. These events not only benefit the general aging process but also maintain ovarian function and delay the reproductive decline. Considering the safety of the α‐KG as a naturally occurring molecule in energy metabolism, its utility in reproduction of large mammals including humans deserves further investigation.     

Methylation of KvDMR1 involved in regulating the imprinting of CDKN1C gene in cattle

The CDKN1C gene encodes a cyclin‐dependent kinase inhibitor and is one of the key genes involved in the development of Beckwith–Wiedemann syndrome and cancer. In this study, using a direct sequencing approach based on a single nucleotide polymorphism (SNP) at genomic DNA and cDNA levels, we show that CDKN1C exhibits monoallelic expression in all seven studied organs (heart, liver, spleen, lung, kidney, muscle and subcutaneous fat) in cattle. To investigate how methylation regulates imprinting of CDKN1C in cattle, allele‐specific methylation patterns in two putative differential methylation regions (DMRs), the CDKN1C DMR and KvDMR1, were analyzed in three tissues (liver, spleen and lung) using bisulfite sequencing PCR. Our results show that in the CDKN1C DMR both parental alleles were unmethylated in all three analyzed tissues. In contrast, KvDMR1 was differentially methylated between the two parental alleles in the same tissues. Statistical analysis showed that there is a significant difference in the methylation level between the two parental alleles (P < 0.01), confirming that this region is the DMR of KvDMR1 and that it may be correlated with CDKN1C imprinting.     

Molecular analysis of the composition of the bifidobacterial and lactobacillus microflora of humans.

The bifidobacterial and lactobacillus populations of fecal samples collected from two human subjects during a 12-month period were studied. The total numbers of bifidobacteria were stable throughout the study period in both subjects, but lactobacillus numbers were less constant. Analysis of the composition of the bifidobacterial populations by using ribotyping or pulsed-field gel electrophoresis to differentiate between bacterial strains demonstrated major differences between the subjects. Subject 1 harbored five strains of bifidobacteria throughout the 12-month period, and one strain was numerically predominant. In contrast, subject 2 harbored a more complex bifidobacterial population (five to six strains per sample) whose composition fluctuated throughout the 12 months. One lactobacillus strain was numerically predominant throughout the study in both subjects. Strains of bifidobacteria and lactobacilli common to both subjects were not detected.     

鲑鱼生长激素基因分泌型表达质粒的构建

生长激素(GH)是动物垂体前叶分泌的一种多肽类激素.应用分子重组及PCR等技术,构建了一种鲑鱼生长激素基因分泌型表达质粒pOsGH153,使编码鲑鱼生长激素成熟肽的序列克隆在大肠杆菌分泌型表达载体PIN-Ⅲ-ompA内,直接位于编码大肠杆菌外膜蛋白A信号肽序列的下游,在Lpp-Lac杂合启动子控制下,经IPTG诱导,分子量约23 000的鲑鱼生长激素在大肠杆菌中获得高效表达,该产物具有天然鲑鱼生长激素的免疫活性,直接分泌到细胞周质,而信号肽被自动剪除.     

Genomic insights into selection for heterozygous alleles and woody traits in Populus tomentosa

Heterozygous alleles are widespread in outcrossing and clonally propagated woody plants. The variation in heterozygosity that underlies population adaptive evolution and phenotypic variation, however, remains largely unknown. Here, we describe a de novo chromosome-level genome assembly of Populus tomentosa, an economic and ecologically important native tree in northern China. By resequencing 302 natural accessions, we determined that the South subpopulation (Pop_S) encompasses the ancestral strains of P. tomentosa, while the Northwest subpopulation (Pop_NW) and Northeast subpopulation (Pop_NE) experienced different selection pressures during population evolution, resulting in significant population differentiation and a decrease in the extent of heterozygosity. Analysis of heterozygous selective sweep regions (HSSR) suggested that selection for lower heterozygosity contributed to the local adaptation of P. tomentosa by dwindling gene expression and genetic load in the Pop_NW and Pop_NE subpopulations. Genome-wide association studies (GWAS) revealed that 88 single nucleotide polymorphisms (SNPs) within 63 genes are associated with nine wood composition traits. Among them, the selection for the homozygous AA allele in PtoARF8 is associated with reductions in cellulose and hemicellulose contents by attenuating PtoARF8 expression, and the increase in lignin content is attributable to the selection for decreases in exon heterozygosity in PtoLOX3 during adaptive evolution of natural populations. This study provides novel insights into allelic variations in heterozygosity associated with adaptive evolution of P. tomentosa in response to the local environment and identifies a series of key genes for wood component traits, thereby facilitating genomic-based breeding of important traits in perennial woody plants.     

牛泌乳素mRNA的分离及鉴定

本文报道了从牛脑垂体提取总RNA,经寡聚脱氧胸苷纤维素亲合层析分离获得牛脑垂体Poly(A)~+RNA。牛泌乳素mRNA经含羟甲基汞琼脂糖凝胶电泳分析,估计其长度约为1200个核苷酸。根据牛泌乳素的部分氨基酸序列推断并合成寡聚核苷酸探针,经Northern印迹杂交及放射自显影分析,证实了该mRNA中含有牛泌乳素mRNA的序列。在兔网织红细胞体外翻译体系中,牛泌乳素mRNA促进了~35S-甲硫氨酸参入,翻译合成的初级翻译产物能与兔抗羊PRL抗血清发生特异性免疫沉淀反应,SDS聚丙烯酰胺凝胶电泳及放射自显影分析结果表明,牛泌乳素前体的分子量约25000。     

Cardiac telocytes exist in the adult Xenopus tropicalis heart

Recent research has revealed that cardiac telocytes (CTs) play an important role in cardiac physiopathology and the regeneration of injured myocardium. Recently, we reported that the adult Xenopus tropicalis heart can regenerate perfectly in a nearly scar‐free manner after injury via apical resection. However, whether telocytes exist in the X tropicalis heart and are affected in the regeneration of injured X tropicalis myocardium is still unknown. The present ultrastructural and immunofluorescent double staining results clearly showed that CTs exist in the X tropicalis myocardium. CTs in the X tropicalis myocardium were mainly twined around the surface of cardiomyocyte trabeculae and linked via nanocontacts between the ends of the telopodes, forming a three‐dimensional network. CTs might play a role in the regeneration of injured myocardium.