非哺乳类脊椎动物性别决定的研究进展

比较了非哺乳类脊椎动物和哺乳动物性别决定的差异 ,从影响非哺乳类脊椎动物性别决定的环境因子及其机制两方面回顾了性别决定的研究进展 ,分析环境因素和类固醇激素在性别决定中的作用 ,指出了非哺乳类脊椎动物性别决定研究中需要进一步探讨的问题。

松果体昼夜节律生物钟分子机制的研究进展

在各种非哺乳类脊椎动物中 ,松果体起着中枢昼夜节律振荡器的作用。近来 ,在鸟类松果体中相继发现了几种钟基因 ,如Per、Cry、Clock和Bmal等 ,其表达的时间变化规律与哺乳类视交叉上核 (SCN)的非常相似。钟的振荡由其自身调控反馈环路的转录和翻译组成 ,鸟类松果体和哺乳类SCN似乎具有共同的钟振荡基本分子构架 ;若干钟基因产物作为正向或负向调节子影响钟的振荡 ;昼夜性的控时机制同时也需要翻译后事件的参与。这些过程对钟振荡器的稳定性和

家禽黑视蛋白对生物节律和繁殖行为的调节

哺乳动物光感受作用仅限于视锥细胞、视杆细胞和少数视网膜神经节细胞,而非哺乳类脊椎动物存在许多的眼外光感受器,但是这些眼外光感受器的确切功能及其感光色素目前仍不十分清楚[1]。家禽视网膜、松果体和视交叉上核是感受光照并参与调控生物节律和繁殖行为的主要部位。黑视蛋白（Melanopsin）是自主感光神经节细胞（Intrinsically photosensitive retinal ganglion cells,ipRGCs）表达的一种感光色素蛋白,近年来研究表明其在家禽视网膜、松果体和视交叉上核均有表达[。

幼龄鸵鸟的微孢子虫病

微孢子虫(Microsporidia)是一种专性胞内原虫寄生虫,属微孢子亚门,可以侵袭大多数非脊椎动物和所有的脊椎动物。微孢子虫病在人、实验动物都有过介绍,但在鸟类中感染和发病介绍不多。自从平胸鸟类作为肉食来源进行商品生产以来,人们已经认识到许多临床和剖检方面的异常表现。

The evolutionary foundation of genomic imprinting in lower vertebrates

In mammals,genomic imprinting confers developmental asymmetry and complementation on the parental genomes and makes both parental genomes essential for complete development.Genomic imprinting is,therefore,the first regulatory step of genome-wide gene expression of embryogenesis and thought to be the epigenetic foundation of bisexual reproduction.However,how the genomic imprinting is originated,established and maintained during vertebrate evolution remains unknown.Because no endogenous imprinting gene has been identified in non-mammalian vertebrates,genomic imprinting is thought to be a unique evolutionary event of mammals.Here,in order to study the evolutionary origin of genomic imprinting in vertebrates,we examined whether parent-specific methylation occurred in the teleost homologue of mammalian imprinting gene during gametogenesis.Bisulfate sequencing analy-sis showed that,as mammalian Igf2 CpG island,goldfish Igf2 CpG island was a parental differentially methylated region(DMR) that was hypermethylated in sperm but unmethylated in eggs.Unlike mam-malian imprinting gene DMR,however,the parent-specific methylation pattern of goldfish Igf2 DMR was not maintained during embryogenesis,suggesting that the parent-specific methylation of goldfish Igf2 DMR might be a primitive genomic imprinting in the early period of vertebrate evolution.These results indicate that the evolutionary foundation of genomic imprinting exists in lower vertebrates and genomic imprinting should not be considered as a unique evolutionary event of mammals.

Functional study of hyperpolarization activated channel (I_h) in Drosophila behavior

Hyperpolarization-activated, cyclic nucleotide-gated and cation-nonselective ion channels （lh channels, or HCN channels） are known to play important roles in mammals. Their physiological functions in invertebrate remain largely unclear. Here, we re- port our studies with lh channel in Drosophila melanogaster. Drosophila lh channel mutants are found with several defects by behavioral analyses. Their lifespan is reduced, and their chemical sensitivity is shifted. In addition, their length of sleep at light-dark condition is mildly reduced. We generated transgenic flies of lh promoter-driven Gal4 and examined its expression pattern in both larvae and adult flies. Our results suggest that Ih channel may play diverse roles in Drosophila and provide a basis to further expand our understanding of Drosophila Ih channel function in vivo.

Dynamic expression of the LAP family of genes during early development of Xenopus tropicalis

The leucine-rich repeats and PDZ (LAP) family of genes are crucial for the maintenance of cell polarity as well as for epithelial homeostasis and tumor suppression in both vertebrates and invertebrates.Four members of this gene family are known:densin,erbin,scribble and lano.Here,we identified the four members of the LAP gene family in Xenopus tropicalis and studied their expression patterns during embryonic development.The Xenopus LAP proteins show a conserved domain structure that is similar to their homologs in other vertebrates.In Xenopus embryos,these genes were detected in animal cap cells at the early gastrula stage.At later stages of development,they were widely expressed in epithelial tissues that are highly polar in nature,including the neural epithelia,optic and otic vesicles,and in the pronephros.These data suggest that the roles of the Xenopus LAP genes in the control of cell polarity and morphogenesis are conserved during early development.Erbin and lano show similar expression patterns in the developing head,suggesting potential functional interactions between the two molecules in vivo.

Environmental factors determining growth of salamander larvae： A field study

Larval growth and survival of organisms are strongly influenced by abiotic and biotic factors, as demonstrated by ex- perimental studies performed under controlled laboratory or semi-natural conditions. Even if they have many advantages, ex- periments cannot cover the full complexity of natural conditions and field studies are needed for a better understanding of how environmental variation determines growth and development rate. Fire salamander Salamandra salamandra females give birth to larvae in a variety of habitats, both epigean and subterranean. In caves, salamander larvae successfully grow and metamorphose, but their growth is more than three times longer than in epigean streams and factors determining these differences require inves- tigation. We performed a field study to understand the factors related to the growth of fire salamander larvae in different envi- ronmental conditions, evaluating the relationship between environmental features and larval growth and differences between caves and epigean spring habitats. Both caves and epigean larvae successfully grew. Capture-mark-recapture allowed to individu- ally track individuals along their whole development, and measure their performance. Growth rate was significantly affected by environmental variables： larvae grew faster in environments with abundant invertebrates and few conspeciflcs. Taking into ac- count the effect of environmental variables, larval growth was significantly lower in caves. Food availability plays a different ef- fect in the two environments. Larval growth was positively related to the availability of invertebrates in epigean sites only. The development rate of hypogeous populations of salamanders is slower because of multiple parameters, but biotic factors play a much stronger role than the abiotic ones