哺乳动物配子发生过程中核的印迹作用

很多无脊椎动物、部分鱼类和鸟类都可进行单性生殖。关于哺乳动物的单性生殖,长期以来人们进行了大量的研究。Pincus和shapiro报道用冷刺激法处理兔卵母细胞后,有的卵进一步发育成胚胎,超过植入期,并且获得了几例活的单性生殖个体。以后,Hoppe及Illmensee报道,他们也得到了纯合子的小鼠。但是,这些实验至今一直未能被别人所重复,故其真实性有待进一步研究。除此之外,哺乳类中至今仍未见有单性生殖的个体,其原因何在?本文将讨论与此相关的核的印迹作用     

猪原始生殖细胞的分离、培养与鉴定

Embryonic germ cells (EG cells) are pluripotential undifferentiated stem cells isolated from cultured primordial germ cells (PGCs). Like ES cells, EG cells are of importance for gene targeting, therapeutical cloning and organ trans-plantation. The aim of this study was to isolate and characterize EG cells from porcine PGCs. The genital ridges from 24- 26 days old porcine embryos were treated in 0.02% EDTA for 20 min and pricked with a needle to release PGCs. The isolated PGCs were cultured on a SNL feeder layer in an EG cell medium. The EG cell medium consisted of Dulbecco‘‘s modified Eagle‘‘ s medium (DMEM) supplemented with 20 % Buffalo rat lever (BRL) cell-conditioned medium, 15 % fe-tal bovine serum, 1 mmol L-glutamine, 0.1 mol nonessential amino acids, 10 μmol β-mercaptoethanol and antibiotics.The freshly isolated PGCs were positive for alkaline phosphatase activity and Periodic acid-Schiff‘‘ s staining. Under this culture regime, PGCs could be maintained in an undifferentiated state and used for further cultures. One strain of the cul-tured PGCs was cultured 8 times, and alkaline phosphatase activity was detected in the colony formed from this strain.These cultured PGCs could spontaneously differentiate into fibroblast-like cells. These data suggested that we had success-fully isolated EG-like cells from oorcine PGCs.     

miRNAs的表达调控机制

microRNAs(miRNAs)是一类在转录后基因调控中发挥功能的非编码小RNAs,在发育、生长和分化等过程中发挥重要作用.至今已经在动物、植物和微生物等不同生物体中鉴定出来数千种miRNAs. miRNAs可以通过降解mRNA或抑制蛋白翻译的方式调节特异基因表达.生物体内约30%的基因都受miRNAs的调节.miRNAs的表达与功能受到转录因子、表观遗传学、多核苷酸多态性及其RNA编辑等多种因素的调节.此外,特异miRNA基因敲除的成功为研究miRNAs功能提供了有力的实验模型.