Reproductive isolation and the period gene of Drosophila

The identification of genes of large effect on ecologically important traits is an important aim of molecular ecology. The period gene of Drosophila is a candidate for a gene with a large influence on premating isolation between Drosophila species, as it determines species specific aspects of courtship behaviour. Strains of D. melanogaster are available which have been genetically transformed with the period gene of either D. melanogaster or D. simulans. Here we show that D. melanogaster females do not discriminate between two such strains. This suggests that period may only make a small contribution to total premating isolation between these species. We discuss the use of genetically transformed strains in assessing the influence of single genes on complex traits.     

The Anopheles albimanus white gene: molecular characterization of the gene and a spontaneous white gene mutation

We have cloned and characterized the white gene of Anopheles albimanus. Comparison of the deduced amino acid sequence of this white gene with its homologs from six species of Diptera show that the An. albimanus gene is most similar to the white gene of An. gambiae (92% identity). A spontaneous white-eyed mutant An. albimanus was caused by an approximately 10 kb insertion into a CT dinucleotide repeat region of intron 2 of the white locus. The flanks of this insertion are long (at least 400 bp), nearly perfect inverted terminal repeat sequences. This cloned white gene should be useful as a marker for germ line transformation of An. albimanus. This revised version was published online in July 2006 with corrections to the Cover Date.     

黑腹果蝇white基因在H2O2影响下卷翅形成中的作用及机理

卷翅是果蝇遗传学上最常用的标记之一,但卷翅形成的具体机制还不清楚.过去的研究发现,理化刺激影响果蝇卷翅的形成.我们最近研究发现,H₂O₂处理不仅会影响果蝇的羽化率,还会使其出现卷翅现象.本研究通过改变H₂O₂浓度、果蝇培养温度和H₂O₂处理时间,探讨影响黑腹果蝇卷翅形成的具体因素,并对其超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)活力进行检测,探讨H₂O₂对果蝇抗氧化能力的影响.结果表明: 果蝇的羽化率与H₂O₂浓度成反比.温度、H₂O₂浓度和H₂O₂处理时间的改变均会影响果蝇翅的卷曲程度和卷翅果蝇所占的比例.其中white基因突变果蝇对这3种条件反应最明显,mini-white(white基因回复突变)果蝇却可以拯救该表型,它的反应与野生型OR相似.H₂O₂对含Cy基因的果蝇卷翅的形成也有一定的影响,可以加大果蝇翅的卷曲程度.对SOD、CAT和GSH-PX活力检测发现,H₂O₂处理会使果蝇的抗氧化能力降低.实时荧光定量PCR检测发现,H₂O₂处理会导致果蝇基因表达量发生改变.黑腹果蝇卷翅形成是一个十分复杂的过程,H₂O₂可能作为某种信号分子或是间接影响某种因子参与黑腹果蝇的卷翅形成过程.该卷翅形成过程可能与Cy基因导致的果蝇卷翅过程是同一个信号途径,两者也可能是通过不同的模式进行调控的.     

黑腹果蝇white基因在H_2O_2影响下卷翅形成中的作用及机理

卷翅是果蝇遗传学上最常用的标记之一,但卷翅形成的具体机制还不清楚.过去的研究发现,理化刺激影响果蝇卷翅的形成.我们最近研究发现,H_2O_2处理不仅会影响果蝇的羽化率,还会使其出现卷翅现象.本研究通过改变H_2O_2浓度、果蝇培养温度和H_2O_2处理时间,探讨影响黑腹果蝇卷翅形成的具体因素,并对其超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)活力进行检测,探讨H_2O_2对果蝇抗氧化能力的影响.结果表明:果蝇的羽化率与H_2O_2浓度成反比.温度、H_2O_2浓度和H_2O_2处理时间的改变均会影响果蝇翅的卷曲程度和卷翅果蝇所占的比例.其中white基因突变果蝇对这3种条件反应最明显,mini-white(white基因回复突变)果蝇却可以拯救该表型,它的反应与野生型OR相似.H_2O_2对含Cy基因的果蝇卷翅的形成也有一定的影响,可以加大果蝇翅的卷曲程度.对SOD、CAT和GSH-PX活力检测发现,H_2O_2处理会使果蝇的抗氧化能力降低.实时荧光定量PCR检测发现,H_2O_2处理会导致果蝇基因表达量发生改变.黑腹果蝇卷翅形成是一个十分复杂的过程,H_2O_2可能作为某种信号分子或是间接影响某种因子参与黑腹果蝇的卷翅形成过程.该卷翅形成过程可能与Cy基因导致的果蝇卷翅过程是同一个信号途径,两者也可能是通过不同的模式进行调控的.     

Developmental regulation of the Drosophila tropomyosin I (TmI) gene is controlled by a muscle activator enhancer region that contains multiple cis-elements and binding sites for multiple proteins

Developmental gene regulation in vertebrate somatic muscles involves the cooperative interaction of MEF2 (myocyte-specific enhancer-binding factor 2) and members of the b-HLH (basic helix-loop-helix) family of myogenic factors. Until recently, however, nothing was known about the factors that control the developmental regulation of muscle genes during embryogenesis in Drosophila. The Drosophila Tropomyosin I (TmI) gene contains a proximal and distal muscle enhancer within the first intron that regulates its expression in embryonic/larval and adult muscles. We have recently shown that the 355-bp proximal enhancer contains a binding site for the Drosophila homologue of vertebrate MEF2 and that MEF2 acts cooperatively with a basal level muscle activator region to direct high level muscle expression in transgenic flies. The 92-bp muscle activator region, however, does not contain any consensus E-box (CANNTG) binding site sequences for b-HLH myogenic factors, suggesting the MEF2 may interact with other factors to regulate muscle genes in Drosophila. In this study we have used mutation analysis and germ-line transformation to analyze the cis-acting elements within the muscle activator region that regulate its expression in transgenic flies. We have identified a 71-bp region that is sufficient for low basal level temporal- and muscle-specific expression in the embryo, larva, and adult. Substitution mutations within the muscle activator region have identified several cis-element regions spanning 60-bp that are required for either full or partial muscle activator function. An analysis of proteins that bind to this region by gel mobility shift assay and copper nuclease footprinting has allowed us to identify the sites in this region at which multiple proteins complex and interact. We propose that these cis-elements and the proteins that they bind regulate muscle activator function and together with MEF2 are capable of regulating high level muscle expression. Dev. Genet. 20:297–306, 1997. © 1997 Wiley-Liss, Inc.     

有关果蝇zip基因突变株的一些探讨

本文利用PCR技术对两个果蝇突变株zip~(ID16)、zip~(IIF107)的突变zip基因的主要结构域部分进行了扩增,并在克隆后作序列分析。排除了突变发生在这些区域的可能性,表明可能的突变位点:一是位于信号肽部分,二是处于调控区。提示在这两个区域可能有关键性的单个氨基酸或单个碱基位置的存在。     

Simulation of gene pyramiding in Drosophila melanogaster

Gene pyramiding has been successfully practiced in plant breeding for developing new breeds or lines in which favorable genes from several different lines were integrated.But it has not been used in animal breeding,and some theoretical investigation and simulation analysis with respect to its strategies,feasibility and efficiency are needed before it can be implemented in animals.In this study,we used four different pure fines of Drosophila melanogaster,each of which is homozygous at a specific mutant gene with a visible effect on phenotype,to simulate the gene pyramiding process and analyze the duration and population size required in different pyramiding strategies.We finally got the ideal individuals,which are homozygous at the four target genes simultaneously.This study demonstrates that gene pyramiding is feasible in animal breeding and the interaction between genes may affect the final results.     

The relationship between gene dosage,gene expression,and sex in Drosophila

In Drosophila, the ratio of the number of X chromosomes to sets of other chromosomes initiates a series of events which result in sexual differentiation. In addition, this ratio establishes dosage compensation, a mechanism which equalizes the products of X-linked genes in males and females. The present review discusses possible genetic entities responsible for the interpretation of chromosomal sex and subsequent sex-mediated regulation during development.     

DNA variation at the rp49 gene region in Drosophila madeirensis and D. subobscura from Madeira: inferences about the origin of an insular endemic species

An ~1.6 ‐ kb fragment spanning the rp49 gene was sequenced in 16 lines of Drosophila subobscura from Madeira and in 22 lines of the endemic species D. madeirensis. Nucleotide diversity in D. subobscura from Madeira (π=0.0081) was similar to that in lines from Spain carrying the O₃₊₄ chromosomal arrangement (π=0.0080). No significant genetic differentiation was detected between insular and continental O₃₊₄ lines of D. subobscura. These results are compatible both with a rather recent and massive colonization, and with multiple colonization events from the continent. Nucleotide diversity in D. madeirensis (π=0.0076) was similar to that in D. subobscura, which deviates from the expectation, under strict neutrality, of a lower level of variation in an insular species with a small population size. The observed numbers of shared polymorphisms and of fixed differences between D. madeirensis and D. subobscura are compatible with the isolation model of speciation, where shared polymorphisms are due to common ancestry.     

Mapping of chromosomal loci associated with lipopolysaccharide synthesis and serotype specificity in Vibrio cholerae 01 by transposon mutagenesis using Tn5 and Tn2680

Summary Vibrio cholerae strains of the 01 serotype have been classified into three subclasses, Ogawa, Inaba and Hikojima, which are associated with the O-antigen of the lipopolysaccharide (LPS). The DNA encoding the biosynthesis of the O-antigen, the rfb locus, has been cloned and analysed (Manning et al. 1986; Ward et al. 1987). Transposon mutagenesis of the Inaba and Ogawa strains of V. cholerae, using Tn5 or Tn2680 allowed the isolation of a series of independent mutants in each of these serotypes. Some of the insertions were mapped to the rfb region by Southern hybridization using the cloned rfb DNA as a probe, confirming this location to be responsible for both O-antigen production and serotype specificity. The other insertions allowed a second region to be identified which is involved in V. cholerae LPS biosynthesis.     

An approach to study the evolution of theDrosophila 5S ribosomal genes using P-element transformation

Summary The P-element-mediated gene transfer system was used to introduceDrosophila teissieri 5S genes into theDrosophila melanogaster genome. Eight transformedD. melanogaster strains that carryD. teissieri 5S mini-clusters consisting of 9–21 adjacent 5S units were characterized. No genetic exchanges betweenD. melanogaster andD. teissieri 5S clusters were detected over a 2-year survey of the eight strains. The occurrence of small rearrangements within theD. melanogaster 5S cluster was demonstrated in one of the transformed strains.     

Stage-specific regulation of actin genes in Drosophila wing cells

Extreme and rapid changes in the synthesis of messenger RNAs and proteins accompany differentiation in wing tissues of Drosophila. Of the six actin genes, at least three are expressed in wing cells, some during the most extreme changes in cell shape. However, different messages of the set appear, decay, and reappear on a regulated temporal program. These results show that actin expression is stage-specific in a single cell type.     

Simulation of gene pyramiding in Drosophila melanogaster

Gene pyramiding has been successfully practiced in plant breeding for developing new breeds or lines in which favorable genes from several different lines were integrated.But it has not been used in animal breeding,and some theoretical investigation and simulation analysis with respect to its strategies,feasibility and efficiency are needed before it can be implemented in animals.In this study,we used four different pure lines of Drosophila melanogaster,each of which is homozygous at a specific mutant gene ...