青岛文昌鱼LIM类基因Bblim同源框区的内含子分析(英文)

ＬＩＭ类同源框基因（ｈｏｍｅｏｂｏｘｇｅｎｅ）保守性很强,在动物界广泛存在。各种ＬＩＭ类同源框基因的共同点是：在结构上,ＬＩＭ类同源框基因的编码蛋白都具有同源域和ＬＩＭ结构域;在生物学功能方面,都与早期发育中胚胎细胞谱系的决定和胚胎细胞分化有关。本实验提取青岛文昌鱼基因组ＤＮＡ,用一对简并引物对其ＬＩＭ类同源框基因Ｂｂｌｉｍ进行ＰＣＲ扩增,将所得ＤＮＡ片段克隆到ｐＢｌｕｅｓｃｒｉｐｔⅡＫＳ（＋）质粒上,经测序发现,其同源框区比大多数ＬＩＭ类基因的同源框区要长得多,其上插入有一个长度为１３８ｂｐ的内含子（Ｆｉｇ．１）。这个内含子的序列中有真核生物核基因ｍＲＮＡ内含子的典型序列。并且与该基因ｃＤＮＡ克隆的测序结果相吻合。从而,可以确认该序列中这个内含子的存在。已知绝大多数ＬＩＭ类同源框基因的同源框区无内含子。因此,有必要对其作深入研究。     

同源异型框基因与动物早期发育

同源异型框基因广泛存在于真核生物中,编码一类转录调节蛋白。同源异型框基因在动物早期发育的基因调控中起着非常重要的作用。在动物胚胎发育过程中,同源异型框基因的表达具有复杂的时空模式和调控系统。Antp族基因对于早期胚胎发育中的模式建成,器官分化等具有重要意义。     

复合同源异型结构的研究进展

含有同源异型结构（homeobox）的蛋白质是一大类DNA结合蛋白,在胚胎发育、基因表达调节、细胞分化、神经发生等方面发挥重要作用。近年来发现了同源异型框与其它结构域同时存在,如PAX、POU、LIM、OAR、CUT、ELK、bZIP、SIX、PHD-finger、Engrailed等,近来还发现它通过基因融合或基因失调控方式参与肿瘤的发生。本文对这些含有复合同源框的蛋白质和基因的类型、结构、功能等方面的研究进展进行综述。     

云南元江普通野生稻中Pi-ta和Pib同源基因的克隆和分析

用高保真PCR技术从云南元江普通野生稻中克隆了抗稻瘟病Pi-ta同源基因的编码区及Pib基因的部分同源序列。Pi-ta同源基因的编码区序列与报道的栽培稻有99.7%的同源性。根据前人的结果,从元江普通野生稻的Pi-ta基因推导的氨基酸序列中918位点为丝氨酸,属于Pi-ta~-等位基因,不能对含有AVRPita基因的稻瘟病菌产生抗性。与Pi-ta基因相比,元江普通野生稻中的Pib同源基因第一外显子与栽培稻的相应序列间存在较大差异,其中有一段87 bp的DNA序列缺失,而且不能按正常的Pib基因序列的阅读框进行翻译。因此认为,元江普通野生稻不具有基于Pi-ta和Pib基因的抗稻瘟病遗传基础。     

同源（异位）框转寻因子及其对心血管系统的调节作用

同源（异位）框转录因子是由同源框基因所编码的一种区域特异性的转录调控因子,它影响多种细胞的分化增殖和迁移过程,心血管系统组织内有某些同源框基因的表达,提示这些调控因子可能参与了心脏的正常生长发育和某些病理性细胞分化增殖的过程。     

青岛文昌鱼LIM类基因Bblim同源框区的cDNA克隆、序列分析及其在胚胎发育中的表达(英文)

不同卵裂球发育命运的特化、亦即胚胎细胞的分化是动物胚胎发育的重要特征。多数胚胎细胞尽管形态特征完全一致,却具有完全不同的发育命运。预示着：在这些细胞中存在有决定发育命运的因素———决定子。本工作克隆了青岛文昌鱼ＬＩＭ类同源框基因的同源框片段。目的在于揭示决定子的分子本质。青岛近海采集性成熟的成年青岛文昌鱼,收集未受精卵、受精卵以及各个不同时期的胚胎,液氮冻存备用。分别制备总ＲＮＡ。根据其它动物ＬＩＭ类同源框基因的序列设计引物（Ｔａｂ．１）,连续进行ＲＴＰＣＲ和ＰＣＲ两次扩增。其中,原肠胚来源的第二次ＰＣＲ产物经电泳鉴定（Ｆｉｇ．１）后,酶切、克隆入质粒、测序、将该片段所在的基因命名为Ｂｂｌｉｍ基因,该片段称为Ｂｂｌｉｍ同源框。根据Ｂｂｌｉｍ基因同源框的核苷酸序列推导出其相应的氨基酸序列（Ｆｉｇ．２）,与其它ＬＩＭ类同源框基因进行比较（Ｆｉｇ．３）后,认为：Ｂｂｌｉｍ基因可归入ｌｉｍ３类基因。比较胚胎发育各个不同时期第二次ＰＣＲ产物的含量———即Ｂｂｌｉｍ基因的转录（Ｆｉｇ．４）,提示：该基因可能在受·精·后·和·原·肠·形·成·期·前·后·两个发育阶段起作用。此外,Ｂｂｌｉｍ基因的同源域与海鞘Ｈｒｌｉｍ的     

青岛文昌鱼LIM类同源模型基因反义寡核苷酸对其胚胎发育的影响

研究了青岛文昌鱼ＬＩＭ类同源框基因Ｂｂｌｉｍ反义寡核苷酸对文昌鱼胚胎发育的影响。根据已克隆的Ｂｂｌｉｍ基因序列,设计并合成了对应于该基因同源框区的两条反义寡核苷酸链,用电脉冲方法将其导入文昌鱼受精卵。结果表明：反义寡核苷酸与随机序列寡核苷酸都不影响胚胎细胞分裂,而反义寡核苷酸能掏胚胎细胞Ｂｂｌｉｍ基因的表达。还发现只存在于导入反义寡核苷酸的幼体中的两种畸形－一是在幼体的腹侧近咽部有一圆形突起的结构     

同源盒基因A10编码蛋白的靶调节基因的筛选与鉴定

目的：筛选和鉴定同源盒基因A10编码蛋白（HOXA10）的靶调节基因。方法：以人子宫内膜细胞系AN3CA为实验对象,采用染色质免疫沉淀方法筛选HOXA10靶基因;采用平端克隆方法构建HOXA10靶基因库;采用DNA序列分析结合生物信息学方法鉴定HOXA10靶基因。结果：共获得含有HOXA10结合片段的克隆197个,选取插入片段大于100bp的质粒67个进行DNA序列分析,其中含有HOXA10结合序列TTAT的基因16个。结论：初步筛选出16个HOXA10候选靶基因,为进一步研究HOXA10的基因调节机理提供了新的思路。     

植物同源异型基因及同源异型盒基因的研究进展

植物同源异型基因及同源异型盒基因是涉及植物个体发育调节的两类重要转录因子编码基因.近10年来的研究表明,这两类基因及其产物的结构与功能具有明显的差异.深入研究这两类基因的结构与功能对揭示植物的发育机制具有重要意义.     

The Caenorhabditis elegans lim-6 LIM homeobox gene regulates neurite outgrowth and function of particular GABAergic neurons

We describe here the functional analysis of the C. elegans LIM homeobox gene lim-6, the ortholog of the mammalian Lmx-1a and b genes that regulate limb, CNS, kidney and eye development. lim-6 is expressed in a small number of sensory-, inter- and motorneurons, in epithelial cells of the uterus and in the excretory system. Loss of lim-6 function affects late events in the differentiation of two classes of GABAergic motorneurons which control rhythmic enteric muscle contraction. lim-6 is required to specify the correct axon morphology of these neurons and also regulates expression of glutamic acid decarboxylase, the rate limiting enzyme of GABA synthesis in these neurons. Moreover, lim-6 gene activity and GABA signaling regulate neuroendocrine outputs of the nervous system. In the chemosensory system lim-6 regulates the asymmetric expression of a probable chemosensory receptor. lim-6 is also required in epithelial cells for uterine morphogenesis. We compare the function of lim-6 to those of other LIM homeobox genes in C. elegans and suggest that LIM homeobox genes share the common theme of controlling terminal neural differentiation steps that when disrupted lead to specific neuroanatomical and neural function defects.     

The molecular basis for the evolution of the metazoan bodyplan: extracellular matrix-mediated morphogenesis in marine demosponges

Molecular data on development/differentiation and on comparative genomics allow insights into the genetic basis of the evolution of a bodyplan. Sponges (phylum Porifera) are animals that are the (still extant) stem group with the hypothetical Urmetazoa as the earliest common ancestor of all metazoans; they possess the basic features of the characteristic metazoan bodyplan also valid for the animals of the crown taxa. Here we describe three homeobox genes from the demosponge Suberites domuncula whose deduced proteins (HOXa1_SUBDO, HOXb1_SUBDO, HOXc1_SUBDO) are to be grouped with the Antennapedia class of homeoproteins (subclasses TIx-Hox11 and NK-2). In addition, a cDNA encoding a LIM/homeobox protein has been isolated which comprises high sequence similarity to the related LIM homeodomain (HD) proteins in its LIM as well as in its HD domains. To elucidate the potential function of these proteins in the sponge a new in vitro system was developed. Primmorphs which are formed from dissociated cells were grown on a homologous galectin matrix. This galectin cDNA was cloned and the recombinant protein was used for the preparation of the matrix. The galectin/polylysine matrix induced in primmorphs the formation of channels, one major morphogenetic process in sponges. Under such conditions the expression of the gene encoding the LIM/homeobox protein is strongly upregulated, while the expression of the other homeobox genes remains unchanged or is even downregulated. Competition experiments with galactosylceramides isolated from S. domuncula were performed. They revealed that a beta-galactosylceramide, named Sdgal-1, prevented the expression of the LIM gene on the galectin matrix, while Sdgal-2, a diglycosylceramide having a terminal alpha-glycosidically linked galactose, caused no effect on the formation of channels in primmorphs or on LIM expression. This study demonstrates for the first time that an extracellular matrix molecule, galectin, induces a morphogenetic process in sponges which is very likely caused by a LIM/homeobox protein. Furthermore, a new model is introduced (galectin-caused channel formation in sponge primmorphs) to investigate basic pathways, thus allowing new insights into the functional molecular evolution of Metazoa.     

The freshwater planarian Dugesia (G.) tigrina contains a great diversity of homeobox genes

To identify potential pattern control and cell determination and/or differentiation genes in the freshwater planarian Dugesial (G.) tigrina, we searched for homeobox genes of different types in the genome of this primitive metazoan. We applied two basic approaches: 1) Screening the cDNA library with degenerate oligonucleotides corresponding to the most conserved amino acid sequence from helix-3 of the homeodomain of each family; and 2) PCR amplification of genomic DNA or cDNA, using two sets of degenerated oligonucleotides corresponding to helices 1 and 3 of the homeodomain or two specific domains of the POU family. Using the first strategy we have identified and characterized two tissue-specific cell determination and/or differentiation NK-type homeobox genes. Using the second strategy we have identified several homeobox genes that belong to the HOM/Hox, paired (prd) or POU families.