Identification of a new gene mutated in Fraser syndrome and mouse myelencephalic blebs

Fraser syndrome is a recessive, multisystem disorder presenting with cryptophthalmos, syndactyly and renal defects and associated with loss-of-function mutations of the extracellular matrix protein FRAS1. Fras1 mutant mice have a blebbed phenotype characterized by intrauterine epithelial fragility generating serous and, later, hemorrhagic blisters. The myelencephalic blebs (my) strain has a similar phenotype. We mapped my to Frem2, a gene related to Fras1 and Frem1, and showed that a Frem2 gene-trap mutation was allelic to my. Expression of Frem2 in adult kidneys correlated with cyst formation in my homozygotes, indicating that the gene is required for maintaining the differentiated state of renal epithelia. Two individuals with Fraser syndrome were homozygous with respect to the same missense mutation of FREM2, confirming genetic heterogeneity. This is the only missense mutation reported in any blebbing mutant or individual with Fraser syndrome, suggesting that calcium binding in the CALXbeta-cadherin motif is important for normal functioning of FREM2.     

Increase in neuronal nitric oxide synthase content of the gastroduodenal tract of diabetic rats

This study examined the changes occurring in the pattern of distribution and expression of neuronal nitric oxide synthase (nNOS)-positive nerves in the gastroduodenal tract of streptozotocin-induced diabetic rats. The ganglion cells of the myenteric plexus of the gastric antrum of normal rats contain nNOS. We also observed nNOS-positive neurons and fibres in the myenteric plexus of the duodenum of normal rats. After the onset of diabetes, the number and intensity of staining of nNOS-positive nerve profiles in the gastric antrum and duodenum did not change significantly. However, Western blotting showed a significant increase in the expression of nNOS after the onset of diabetes. In conclusion, diabetes of 4 and 32 weeks duration induced an increase in the tissue content of nNOS in the gastroduodenum of rat. The increase in the level of nNOS in the gastroduodenum of diabetic rats may explain why impaired gastric emptying is common in patients with diabetes.     

基因测试探查尼安德特人的起源

一项新的研究发现 :一项能辨别ＤＮＡ样品相似性的技术支持早期关于尼安德特人是一种灭绝末期的人种的遗传传学说法 .　　芝加哥田野博物馆的科学家ＬｕｔｓＢａｃｈｍａｎｎ在 6月份的ＡｍｅｒｉｃａｎＪｏｕｒｎａｌｏｆＨｕｍａｎＧｅｎｅｔｉｃｓ上报道 ,尼安德特人的ＤＮＡ与古代Ｈｏｍｏｓａｐｉｅｎｓ人以及现代人的ＤＮＡ相比 ,存在着重要的遗传差异 .他们断言 ,这些数据支持了尼安德特人在解剖学上并非是现代人的祖先的假说 .研究者取 110 0 0 0年前与 5 0 0 0 0年前的尼安德特人与 35 0 0 0年前的Ｈ .ｓａｐｉｅｎｓ人的化石中的…     

肿瘤细胞反击免疫系统

对付癌症的最大难题之一是为什么患者的免疫系统几乎总是不能消除癌细胞。研究者猜想肿瘤细胞的幸存是靠它能逃避免疫监察或是能阻抑免疫反应。而本期Science报道说，至少有一种癌细胞具有比单是逃避免疫监察更为高明的策略：它们杀灭了攻击它们的免疫细胞。瑞士有一个研究组表明黑素瘤细胞表面载有一个分子，它导致免疫细胞通过称为细胞凋谢的过程发生细胞自杀。比利时首都布鲁塞尔的路德维希研究院的肿瘤免疫学家西尔利·布恩（ThierryBoon）说：这个发现很有趣，也很重要。”正如研究者之一，瑞士洛桑大学的生物化学家容格·肖帕（Jurg…     

调动机体自身的治愈力—肿瘤的免疫疗法

调动机体自身的治愈力──肿瘤的免疫疗法ＤａｒｒｅｌｌＥ．Ｗａｒｄ著李潇译国家癌症研究院外科主任史蒂文·罗森伯格的写字台上面悬挂着一幅１８世纪的外科医师约翰·亨特的语录：＂外科就象武装的原始人，他们企图用武力取得的东西，文明人则总是用计谋取得。＂这条警...     

固氮细菌找到新寄主

研究人员促成了固氮根瘤菌到包括稻子在内的非豆科植物的根际安家结瘤.固氮根瘤菌是一种极其特别的细菌.除个别例外,它们只能在豆科植物例如大豆,苜蓿和刺槐的根部结瘤固氮.这种细菌,摄取在空气中无用的氮气,并将其转化成氨和植物的其他营养成份.实际上,细菌是为     

基于微生物燃料电池技术的生物传感器及其应用进展

简要介绍微生物燃料电池型生物传感器的工作原理,概述各种基于微生物燃料电池技术开发的生物传感器及其应用领域。分析影响微生物燃料电池型生物传感器性能的因素,讨论提高传感器性能的方法,以期为研究和开发高性能的微生物燃料电池型生物传感器提供参考。