中国西南高山地区的四川白蛉

中国西南高山地区的四川白蛉冷延家，张玲敏暨南大学医学院医学寄生虫学教研室广州５１０６３２冷、尹￣［１］自川西北报道了四川白蛉Ｐｈｌｅｂｏｔｏｍｕｓ（Ａｄｌｅｒｉｕｓ）ｓｉｃｈｕａｎｅｎｓｉｓ冷＆尹，１９８３，此后它被指控为四川、陕西、甘肃、青海的内脏...     

甘薯杂交胚发育过程中的一些生理变化

杂交育种仍是目前甘薯（Ipomoeabatatas）育种的主要手段，而品种间不亲和性的大小和杂交结实率低是制约甘薯杂交育种效果的两个主要因素［”］。迄今已知甘薯存在着15个不同的杂交不亲和群，同群品种间杂交不结实或结实率极低（0％～5％），而异群品种间杂交给实率较高（20％～50％）［‘j。对于杂交结实率低的原因和解决途径，只有少量基干解剖学的观察［”‘’1和利用嫁接、植物生长调节剂提高结实率的报道＊－”。在生理基础方面的研究则未见报道。为此我们选择甘薯高自1号X88－3这一杂交组合（结实率为13．3士l．8％），在8月份的每天…     

科学快讯

日本调查表明多喝绿茶可大幅降低脑梗塞死亡风险新华网东京5月6日报道:日本新公布的调查结果表明,每天坚持喝绿茶:有益健康,适当多喝绿茶甚至可大幅降低脑梗塞的死亡风险。据共同社目前报道,日本东北大学公共卫生学副教授栗山进一等人从1994年起,以日本本州东北地区宫城县4万多名40岁至79岁的中老年人为对象,实施跟踪调查。研究人员按照调查对象每天喝绿茶的量,将他们分成4组进行分析。     

《昆虫知识》2010年第47卷第3期要目预告

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Developmental potency of mouse primitive ectoderm cells,embryonic ectoderm cells,embryonic ectoderm cells and primordial germ cells after blastocyst injection

Developmental potency of primitive and embryonic ectoderm cells from 4.50-day to 6.25-day post-coitum (p.c.) mouse embryos and primordial germ cells from 12.50-day p.c.male genital ridges of fetal mice were studied by direct introducing them into 3.50-day p.c.blastocysts.Sixteen (61.5) overt chimaeras out of 26(50%) offsprings were obtained after transfer of 52 blastocysts injected with 4.50-day primitive ectoderm cells;four (16.0%) overt chimaeras were obtained out of 25 (51.0%) offsprings with 4.75-day primitive ectoderm cells from 49 transferred blastocysts.However,no overt chimaera was obtained with either 5.25-day or 6.25-day embryonic ectoderm cells or 12.50-day male primordial germ cells.GPI analysis of mid-gestation conceptuses developed from injected blastocysts showedthat 5.25-day embryonic ectoderm cells could only contributed to yolk sac of conceptus.Results suggested that implantation acts as a trigger for the determination of primitive ectoderm cells,and their developmental potency becomes limited within a short period of time in normal development.