果蝇心脏发育起调控作用的候选基因的筛选

果蝇的早期心脏发育与脊椎动物的早期发育模式具有惊人的相似,所以果蝇成为研究脊椎动物心脏发育的模式动物,通过对其心脏发育基因的研究,可加速揭示人体心脏的发育机理。为进一步筛选并克隆出新的心脏发育基因,本实验采用经化学诱变的平衡致死系的果蝇,进行心脏特异性抗体染色,观察到10个致死系表现出心脏突变表型,并将已确定遗传学部位的6个品系缩小到更小区域。 Screening of the Genes in Controlling HeartDevelopment of Drosophila YANG Yue-jun,WU Xiu-shan,LI Min College of life sciences,Hunan Normal University,Changsha 410081,China Abstract:It is becoming increasingly evident that remarkable similaries of heart development are revealed in Drosophila and vertebrate,Therefore Drosophila can be used as a prototype to explore the vertebrate.This can in accelerate to revealing of the machanisms of human heart development.In order to screen and clone new genes that control the heart development,we have established the balanced-lethal lines by chemical mutagen and performed the heart-specific antibody.Ten of lines showed mutant phenotype,of which 6 were determined the smaller genetic sites for gene location. Key words：Drosophila; heart develop; genes     

利用果蝇模型研究人类心脏早期发育的分子机理(英文)

近年来 ,果蝇心脏特化的遗传机制已初步研究清楚 ,但控制人类心脏早期发育的基因尚待鉴定。因为调控果蝇和脊椎动物早期心脏细胞命运定型的途径具有保守性 ,果蝇是一种探讨人类心脏早期发育的分子机理的理想动物模式。为此目的 ,我们采用P转座子和EMS诱变技术建立了约 3 0 0 0个隐性致死基因平衡系。通过心脏前体细胞特异性抗体免疫组化筛选 ,我们检出 2 0 0余个表现心脏突变表型的平衡致死系。我们进一步利用RNAi技术对一些基因的功能进行了初步的研究 ,证明这些基因表现RNAi的突变表型 ,该类突变表型与基因突变时表现的表型相似 ,即心管呈缺陷型或无心脏前体细胞形成。利用果蝇和人类基因组计划获得的成果 ,我们从果蝇心脏侯选基因中初步克隆和鉴定了 5 0个人类同源基因 ,其中 2 0个是新基因。Northen印迹分析表明 ,一部分人类基因在心脏组织中有表达 ,从而为研究这些基因在人类心脏早期发育中的作用提供了信息。目前 ,我们正在建立转基因果蝇 ,以此为模型研究这些基因是否对心肌细胞发生或心肌功能起调控作用。产生心肌细胞突变类型的基因如果类似于人类心脏病综合症 ,则可以作为人类心脏疾病侯选基因作进一步的分析。     

A genetic screen for zygotic embryonic lethal mutations affecting cuticular morphology in the wasp Nasonia vitripennis

We have screened for zygotic embryonic lethal mutations affecting cuticular morphology in Nasonia vitripennis (Hymenoptera; Chalcidoidea). Our broad goal was to investigate the use of Nasonia for genetically surveying conservation and change in regulatory gene systems, as a means to understand the diversity of developmental strategies that have arisen during the course of evolution. Specifically, we aim to compare anteroposterior patterning gene functions in two long germ band insects, Nasonia and Drosophila. In Nasonia, unfertilized eggs develop as haploid males while fertilized eggs develop as diploid females, so the entire genome can be screened for recessive zygotic mutations by examining the progeny of F1 females. We describe 74 of >100 lines with embryonic cuticular mutant phenotypes, including representatives of coordinate, gap, pair-rule, segment polarity, homeotic, and Polycomb group functions, as well as mutants with novel phenotypes not directly comparable to those of known Drosophila genes. We conclude that Nasonia is a tractable experimental organism for comparative developmental genetic study. The mutants isolated here have begun to outline the extent of conservation and change in the genetic programs controlling embryonic patterning in Nasonia and Drosophila.     

Identifying targets of the rough homeobox gene of Drosophila: evidence that rhomboid functions in eye development.

In order to identify potential target genes of the rough homeodomain protein, which is known to specify some aspects of the R2/R5 photoreceptor subtype in the Drosophila eye, we have carried out a search for enhancer trap lines whose expression is rough-dependent. We crossed 101 enhancer traps that are expressed in the developing eye into a rough mutant background, and have identified seven lines that have altered expression patterns. One of these putative rough target genes is rhomboid, a gene known to be required for dorsoventral patterning and development of some of the nervous system in the embryo. We have examined the role of rhomboid in eye development and find that, while mutant clones have only a subtle phenotype, ectopic expression of the gene causes the non-neuronal mystery cells to be transformed into photoreceptors. We propose that rhomboid is a part of a partially redundant network of genes that specify photoreceptor cell fate.     

A large-scale screen for mutagen-sensitive loci in Drosophila

In a screen for new DNA repair mutants, we tested 6275 Drosophila strains bearing homozygous mutagenized autosomes (obtained from C. Zuker) for hypersensitivity to methyl methanesulfonate (MMS) and nitrogen mustard (HN2). Testing of 2585 second-chromosome lines resulted in the recovery of 18 mutants, 8 of which were alleles of known genes. The remaining 10 second-chromosome mutants were solely sensitive to MMS and define 8 new mutagen-sensitive genes (mus212-mus219). Testing of 3690 third chromosomes led to the identification of 60 third-chromosome mutants, 44 of which were alleles of known genes. The remaining 16 mutants define 14 new mutagen-sensitive genes (mus314-mus327). We have initiated efforts to identify these genes at the molecular level and report here the first two identified. The HN2-sensitive mus322 mutant defines the Drosophila ortholog of the yeast snm1 gene, and the MMS- and HN2-sensitive mus301 mutant defines the Drosophila ortholog of the human HEL308 gene. We have also identified a second-chromosome mutant, mus215(ZIII-2059), that uniformly reduces the frequency of meiotic recombination to <3% of that observed in wild type and thus defines a function required for both DNA repair and meiotic recombination. At least one allele of each new gene identified in this study is available at the Bloomington Stock Center.     

The Drosophila plutonium and pan gu genes regulate entry into S phase at fertilization

Mutations in the Drosophila maternal genes plutonium (plu) and pan gu (png) have the striking phenotype that DNA replication initiates in unfertilized eggs. Fertilized eggs from plu or png mutant mothers also have a mutant phenotype; DNA replication is uncoupled from nuclear division, resulting in giant, polyploid nuclei. Analysis of multiple alleles of these genes indicates that their wild-type function is required to maintain repression of DNA replication until fertilization. The phenotype of two png alleles suggests that this gene also may play a direct role in coupling S phase and mitosis during the early cleavage divisions. We describe genetic interactions among png, plu, and the previously identified gene gnu that demonstrate these three genes regulate the same process.     

影响果蝇心脏发育的基因突变

最近的研究表明,果蝇与脊椎动物及人的心脏早期发育具有极为相似的基因控制机理,果蝇已成为研究人体心脏早期发育基因控制的理想模式动物。利用化学诱变剂甲磺酸乙酯大规模地诱变影响果蝇心脏发育的基因,利用心脏特异性抗体染色进行筛选,获得了112个有心脏突变表型的致死系,其中32个致死系的心脏畸变表型有别于目前已知心脏发育基因的突变表型。细胞遗传学定位研究表明在多线染色体的13个带纹区的某些隐性致死突变基因是目前未知的,其功能可能与发育有关的基因。     

Drosophila, an emerging model for cardiac disease

A variety of studies that are currently underway may validate the fruit fly as an in vivo model for analyzing genes involved in cardiac function. Many mutations in conserved genetic pathways have been found, including those controlling development and physiology. Because homologous genes control early developmental events as well as functional components of the Drosophila and vertebrate hearts, the fly is the simplest existing model system that can be used to assay genes involved in human congenital heart disease (CHD). The wide variety of genetic tools available to Drosophila researchers offers many technical advantages for rapidly screening through large numbers of candidate genes. Thus, an important future and long-term direction is likely to be the use of Drosophila as a vehicle for analyzing polygenic traits as an aid in human genetics. One can anticipate a time in the not too distant future when mutant lines exist for every gene in vertebrate systems, such as mice and zebrafish. However, one of the enduring problems that will not easily be addressed by such resources will be the tracking of complex traits defined by polygenic variants. For this level of genetic analysis, simple genetic model systems including yeast, Caenorhabditis elegans, and Drosophila melanogaster will undoubtedly play a crucial ongoing role. Of them, Drosophila will be critical for examining gene networks involved in organogenesis and is clearly the system of choice for studying cardiac development, function and aging, since among the simple genetic models it is the only one with a fluid pumping heart.     

Novel genomic cDNA hybrids produce effective RNA interference in adult Drosophila.

Drosophila melanogaster has been a premier genetic model system for nearly 100 years, yet lacks a simple method to disrupt gene expression. Here, we show genomic cDNA fusions predicted to form double-stranded RNA (dsRNA) following splicing, effectively silencing expression of target genes in adult transgenic animals. We targeted three Drosophila genes: lush, white, and dGq(alpha). In each case, target gene expression is dramatically reduced, and the white RNAi phenotype is indistinguishable from a deletion mutant. This technique efficiently targets genes expressed in neurons, a tissue refractory to RNAi in C. elegans. These results demonstrate a simple strategy to knock out gene function in specific cells in living adult Drosophila that can be applied to define the biological function of hundreds of orphan genes and open reading frames.     

The Drosophila tuberous sclerosis complex gene homologs restrict cell growth and cell proliferation

The inherited human disease tuberous sclerosis, characterized by hamartomatous tumors, results from mutations in either TSC1 or TSC2. We have characterized mutations in the Drosophila Tsc1 and Tsc2/gigas genes. Inactivating mutations in either gene cause an identical phenotype characterized by enhanced growth and increased cell size with no change in ploidy. Overall, mutant cells spend less time in G1. Coexpression of both Tsc1 and Tsc2 restricts tissue growth and reduces cell size and cell proliferation. This phenotype is modulated by manipulations in cyclin levels. In postmitotic mutant cells, levels of Cyclin E and Cyclin A are elevated. This correlates with a tendency for these cells to reenter the cell cycle inappropriately as is observed in the human lesions.