DNA methylation of fly genes and transposons

The use of anti-5-methylcytosine antibodies in affinity columns allowed the identification of methylated sequences in the genome of Drosophila melanogaster adults. In view of the presence of transposable elements amongst the identified sequences, it has been suggested that DNA methylation is involved in transposon control in the fly genome. On the contrary, a reanalysis of these data furnishes several intriguing elements that could raise new questions about the role that DNA methylation plays in the fly genome. The aim of the present paper is to discuss some features that emerge from the analysis of the identified methylated sequences. Received 26 January 2006; received after revision 8 May 2006; accepted 2 June 2006     

果蝇幼虫神经肌肉突触电位反应的研究

实验采用电生理微电极胞内记录技术，研究了果蝇三龄幼虫腹纵肌细胞的静息电位与微兴奋性接点电位、神经－肌肉兴奋性接点电位的特点。研究结果显示：１、果蝇三龄幼虫的静息电位为－５３±５ｍＶ２．微兴奋性接点电位的波形与正常兴奋性接点电位相同，平均值为０．６ｍＶ．３．兴奋性接点电位在不同的刺激强度下有不同的值。     

Analysis of the relationship between age of larvae at mutagen treatment and frequency and size of spots in the wing somatic mutation and recombination test inDrosophila melanogaster

The relationship between the induction of mutant clones and the time of mutagen treatment was studied in the somatic mutation and recombination test (SMART) in wing cells ofDrosophila melanogaster. Larvae trans-heterozygous for the recessive marker mutations multiple wing hairs (mwh) and flare (flr) were produced. Batches of these larvae were then treated with mutagen at different ages spanning all three larval instars. Methyl methanesulfonate was fed acutely for 2 h by immersing the larvae in a solution of the mutagen mixed with powdered cellulose. Wings of the surviving adult flies were mounted and scored for the presence of spots. The frequency and size of single and twin spots were recorded separately. Twin spots are produced exclusively by mitotic recombination, whereas single spots can results from various types of mutational and exchange events. There exists a clear correlation between time of induction and frequency as well as size of the single spots. In young larvae only few but very large spots are induced, whereas in older larvae the frequencies are considerably increased but the sizes are smaller. The twin spots show a different relationship. Practically no twin spots are found in very young and in very old larvae. The results demonstrate that in the wing spot test the optimal age of the larvae for mutagen treatment is 72 h.     

雌激素影响果蝇性比机制的研究

本文以果蝇的红白眼色为遗传标记性状,利用红眼雄蝇与白眼雌蝇杂交的方法,研究了乙烯雌酚影响果蝇性比的机制。研究结果表明,在本试验浓度条件下,乙烯雌酚未能使y类型的合子发生性反转,而是对其存在致死作用或是降低了含y染色体的精子的受精机会。     

Sexual isolation betweenDrosophila melanogaster females andD. simulans males. Male mating propensities versus success in hybridization

Genetic variation has been found in males of aD. simulans population for their eagerness to hybridize withD. melanogaster females. In a search for traits involved in this hybridization, males ofD. simulans were tested for mating speed and sexual vigour. Between-male differences were detected in both sexual traits, but no relationship was noticed between them, nor with the frequency of hybridization. Thus male mating propensities appear to be unrelated to the breakdown of sexual isolation between these sibling species.     

Postembryonic sensory axon guidance in Drosophila

The peripheral sensory system of the Drosophila adult has been used for the genetic analysis of axon guidance because of its accessibility for experimental manipulation and mutant screens. Wing, leg, antenna, or eye sensory axons are able to pathfind normally under different perturbations, indicating that sensory axon guidance is a highly canalized process. Similarly to other model systems, sensory growth cones seem to use multiple, simultaneous cues for guidance. In addition, sensory axons from peripheral structures seem to be capable of using alternative substrates for pathfinding. Developmental regulation could account for the high stability of axon guidance under experimental and natural perturbation conditions. Despite this flexibility, functional characterization of genes involved in sensory axon guidance is being carried out in situations where there appears to be less system redundancy.     

Supernumerary chromosomes inDrosophila nasuta albomicana

Summary Supernumerary chromosomes have been detected in the karyotype ofD.n. albomicana. Their number varies from one to three. They are the smallest elements in the karyotype. Karyotypes ofD.n. albomicana with and without supernumerary chromosomes have been presented.     

果蝇内含子和编码序列的信息参数D_2沿染色体分布

本文以果蝇染色体的内含子和编码序列作为研究对象,用信息参数D2分析两类序列沿着染色体的分布规律,并用多项式拟合分析染色体各类序列沿染色体的统计分布特征,分析D2参数的平均值在不同的染色体臂的分布特征.     

郑州黑腹果蝇自然群体P—M细胞型多态性研究

应用性腺败育频率的遗传分析方法，对郑州黑腹果蝇自然群体的Ｐ因子活性和细胞型进行了较详尽的剖析。结果发现，该群体的Ｐ因子活性是单态的；而细胞型在群体、单雌系内和个体间皆表现出多态现象；该群体为缺乏完整Ｐ因子的Ｍ′品系。提出了Ｑ因子调控模型，以解释在缺乏完整Ｐ因子的Ｍ′品系中细胞型决定和多态现象产生的机理，并对细胞型的频率分布规律与平均ＧＤ（性腺）不育频率之间的内在联系进行了讨论。     

避孕药对不同糖质量浓度下雌性黑腹果蝇寿命的影响

低糖是引起女运动员三联征的主要原因之一,避孕药对运动成绩的影响也存在争议.本文选用模式生物雌性黑腹果蝇作为女运动员研究的模型,通过研究不同白砂糖和避孕药质量浓度对黑腹果蝇寿命的影响,为女运动员健康维护提供理论依据.结果表明雌性黑腹果蝇的寿命与白砂糖浓度成倒U字型相关,在正常糖质量浓度(40.5 mg/mL)条件下雌性黑腹果蝇的寿命显著延长,与此相比,无糖组和高糖组寿命显著降低.在低糖模型(糖质量浓度13.5 mg/mL)和正常糖模型(40.5 mg/mL)下,一定质量浓度的避孕药(0.25 mg/mL)均显著地延长果蝇寿命,而无避孕药和高避孕药质量浓度都不利于雌性黑腹果蝇的生长.在高糖模型下果蝇的寿命随避孕药质量浓度变化不再出现明显的倒U型曲线,寿命最高点的质量浓度出现在4号(0.20 mg/mL)药物质量浓度点.研究结果表明适当服用避孕药可以延长低糖组、正糖组和高糖组条件下雌性黑腹果蝇寿命.