The patterns of cell death and of macrophages in the developing forebrain of the tree shrew Tupaia belangeri

The patterns of cell death and of macrophages were investigated in the forebrain and eyes of the tree shrew Tupaia belangeri during five phases of optic cup formation. Seventeen embryos were studied. Three- dimensional reconstructions were made from one embryo of each phase. In phase 1 (V-shaped optic evagination) a midline band of cell death passes through the closing anterior neuroporus. From phases 2 (optic vesicle) to 5 (far-advanced invagination) the midline band of cell death extends in the dorsal wall of the forebrain to its rostral pole and, further, into its ventral wall. At the approximate future position of the optic chiasm this ventral pycnotic area, predicted but so far unidentified by others, is connected to a previously described second band of cell death passing through the optic anlagen. Recently, evidence has been presented that chicken embryos develop holoprosencephaly and cyclopia when ventral forebrain structures are lost secondary to experimentally induced apoptosis. Our findings in Tupaia suggest that, in cases of spontaneous malformations of this kind, such an atypical pycnotic area in the ventral telencephalon might result from the defective regulation of cell death processes during optic cup formation. In the forebrain and eyes of Tupaia, the occurrence of bands of cell death precedes the appearance of the earliest intraepithelial macrophages. From phase 3 (onset of invagination) onwards almost all of them are concentrated along the band of cell death. Accepted: 28 September 1999     

不同碘营养水平哺乳期母鼠及其仔鼠甲状腺形态观察

目的 观察碘缺乏和碘过量时哺乳期母鼠及其仔鼠甲状腺形态变化.方法 选择Wistar大鼠120只(雄性30只,雌性90只),将雌鼠接体质量随机分为5组:低碘1组、低碘2组、高碘1组、高碘2组、对照组,每组18只.低碘1组和低碘2组大鼠食用病区粮食配制的低碘饲料,分别饮用含碘0、5μg/L的去离子水;高碘1组、高碘2组和对照组大鼠食用普通饲料,分别饮用含碘3000、10000、50 μg/L的去离子水.饲养3个月后,将雌鼠与雄鼠按3∶1合笼交配,在生育的第10天时,每组处死8只母鼠及其仔鼠.称量甲状腺质量,肉眼观察其外观表现.在光镜下观察甲状腺病理学改变.结果 ①低碘1组和低碘2组母鼠甲状腺绝对质量[ (92.02±24.40)、(77.11±23.32)mg]和相对质量[(0.509±0.072)、(0.384±0.089)mg/kg]明显高于对照组[(17.41±9.25 )mg,(0.102±0.016)mg/kg,P均＜0.05];而高碘1组和高碘2组母鼠甲状腺绝对质量[(8.22±0.41)、(9.42±0.43)mg]和相对质量[(0.047±0.006)、(0.035±0.005)mg/kg]明显低于对照组(P均＜0.05);随着碘摄人的增多,母鼠甲状腺绝对质量和相对质量有逐渐减小的趋势.②肉眼观察:与对照组比较,低碘1组和低碘2组母鼠甲状腺明显肿大,高碘1组和高碘2组未见明显肿大.③光镜观察:与对照组比较,低碘1组和低碘2组母鼠及其仔鼠甲状腺上皮细胞增生,滤泡腔变小,高碘1组和高碘2组上皮细胞变形,多为扁平.结论 母鼠与其仔鼠甲状腺组织随机体碘摄入水平的不同而发生形态学变化,且母鼠与仔鼠的变化相一致.     

RNA干扰在哺乳动物病毒感染中的作用

RNA干扰(RNAi)作为高效的基因阻断技术在抗病毒研究中已取得很大成果,内源性RNAi机制在低等生物中的病毒免疫作用已经明确,但在哺乳动物病毒感染中的研究仍处于探讨阶段,病毒编码小干扰RNA(siRNA)是否存在仍有争议,而由微小RNA(miRNA)介导的RNAi在调节病毒和宿主细胞相互关系中则发挥着重要作用.     

丙型肝炎病毒结构蛋白真核表达载体的构建及其在哺乳动物细胞中的表达

目的:构建丙型肝炎病毒(HCV)结构蛋白的真核表达载体.方法:用RT-PCR方法扩增HCV结构基因,并将其克隆入真核表达载体pcDNA3中,用磷酸钙转染法将其转入Sp2/0细胞,用免疫组化法检测细胞中瞬时表达的目的蛋白.结果:克隆的基因片段全长约1.9kb,包括C及E2的全长和E1的部分.免疫组化显示表达蛋白位于细胞浆中.结论:构建的丙型肝炎病毒结构蛋白的真核表达载体能够在哺乳动物细胞中得到表达,为进一步研究HCV结构蛋白的性质及各结构蛋白相互作用下的基因免疫效果奠定了基础.     

Why REM sleep? Clues beyond the laboratory in a more challenging world

REM sleep (REM) seems more likely to prepare for ensuing wakefulness rather than provides recovery from prior wakefulness, as happens with ‘deeper’ nonREM. Many of REM's characteristics are ‘wake-like’ (unlike nonREM), including several common to feeding. These, with recent findings outside sleep, provide perspectives on REM beyond those from the laboratory. REM can interchange with a wakefulness involving motor output, indicating that REM's atonia is integral to its function. Wakefulness for ‘wild’ mammals largely comprises exploration; a complex opportunistic behaviour mostly for foraging, involving: curiosity, minimising risks, (emotional) coping, navigation, when (including circadian timing) to investigate new destinations; all linked to ‘purposeful, goal directed movement’. REM reflects these adaptive behaviours (including epigenesis), masked in laboratories having constrained, safe, unchanging, unchallenging, featureless, exploration-free environments with ad lib food. Similarly masked may be REM's functions for today's humans living safe, routine lives, with easy food accessibility. In these respects animal and human REM studies are not sufficiently ‘ecological’.