A new family of adenylyl cyclase genes in the male germline of Drosophila melanogaster

We describe the cloning and characterization of a new gene family of adenylyl cyclase related genes in Drosophila. The five adenylyl cyclase-like genes that define this family are clearly distinct from previously known adenylyl cyclases. One member forms a unique locus on chromosome 3 whereas the other four members form a tightly clustered, tandemly repeated array on chromosome 2. The genes on chromosome 2 are transcribed in the male germline in a doublesex dependent manner and are expressed in postmitotic, meiotic, and early differentiating sperm. These genes therefore provide the first evidence for a role for the cAMP signaling pathway in Drosophila spermatogenesis. Expression from this locus is under the control of the always early, cannonball, meiosis arrest, and spermatocyte arrest genes that are required for the G₂/M transition of meiosis I during spermatogenesis, implying a mechanism for the coordination of differentiation and proliferation. Evidence is also provided for positive selection at the locus on chromosome 2 which suggests this gene family is actively evolving and may play a novel role in spermatogenesis. Received: 26 September 1999 / Accepted: 27 October 1999     

Fibrogranular Material,Annulate Lamellae and Microtubules During Spermiogenesis in Drosophila melanogaster

During spermiogenesis in Drosophila melanogaster, a “perinuclear plasm’ accumulates between the fenestrated portion of the nuclear envelope and an adjacent lamella of ER in the young spermatid. Microtubules appear within the perinuclear plasm and become especially concentrated in a nuclear concavity. Cytoplasmic pores are present locally within the lamella of ER. In addition, localized or discrete bodies composed of fibrogranular material become closely associated with single pore complexes in the lamella of ER. A close association exists between pore complexes (annulate lamellae), the small granular and fibrillar subunits of the fibrogranular bodies, polyribosomes and the nuclear-associated microtubules during much of spermiogenesis. While the fibrogranular material becomes less concentrated during spermiogenesis, the number of pore complexes in a single section increases such that two, three or even four short annulate lamellae are intercalated within many longitudinally oriented microtubules which are present in the furrow of the spermatid nucleus. Structural relationships observed between cytoplasmic pores (annulate lamellae), fibrogranular bodies, polyribosomes and microtubules are discussed in relation to information about the timing of RNA and protein synthesis. This study extends previous observations about the distribution and structural variations of annulate lamellae elsewhere in the spermatid cytoplasm.     

Pax基因家族在果蝇发育过程中的调控作用

Pax是一个在进化上相当保守的基因家族, 它们编码的产物是一组极为重要的转录调控因子, 并存在于从果蝇到人类的各种生物体中, 参与细胞内信号传导通路的调控, 在胚胎发育过程中对细胞分化、更新、凋亡起重要的调控作用, 影响器官和组织的形成。果蝇中已发现10个Pax基因家族成员, 它们对果蝇胚胎发育及成虫组织器官的分化有非常重要的调控作用。文章结合最新的研究进展, 就果蝇中Pax基因的结构、表达模式和主要功能做一简要综述。     

Phenotypic inheritance induced by hairpin RNA in Drosophila

Phenotypic inheritance induced by RNA has been documented in mouse and Caenorhabditis elegans. Here we report a similar inheritance in Drosophila. Mutant phenotypes of eye defects and antenna duplication generated from the crossing of one RNA interference （RNAi） transgenic line harboring one hairpin RNA transgene with a GAL4 driver line were inherited independently of the GAL4 driver. Hairpin RNA injection experiments demonstrated that the hairpin RNA could induce heritable mutant-like phenotypes on the eye and antenna. The penetrance of mutant phenotypes was reduced when the mutants were crossed to agol and piwi mutants. Our data suggest that hairpin RNA can induce phenotypic inheritance in Drosophila.     

The interaction of bromodeoxyuridine with ribosomal RNA cistron redundancy in Drosophila

We demonstrate that Bromodeoxyuridine (BrdU)-induced reductions of the ribosomal RNA cistrons (rDNAs) are observed in Drosophila virilis, and Drosophila busckii, but not in karyotypically normal adults or larvae of Drosophila melanogaster. However, BrdU does reduce the redundancy of the rDNAs of XO D melanogaster males, in which a compensatory response is evidenced in the untreated XO sibling controls. These results suggest that the BrdU-rDNA interaction is specific to events which modulate rDNA redundancy. Further, both thymidine and deoxycytidine “reverse” the BrdU effect in D virilis, an observation which is inconsistent with current working hypotheses describing the mechanisms of BrdUs effects.     

Molecular phylogeny of Drosophila based on ribosomal RNA sequences

Nucleotide sequences of 72 species of Drosophilidae were determined for divergent D1 and D2 domains (representing 200 and 341 nucleotides respectively in D. melanogaster) of large ribosomal RNA, using the rRNA direct sequencing method. Molecular phylogenetic trees were reconstructed using both distance and parsimony methods and the robustness of the nodes was evaluated by the bootstrap procedure. The trees obtained by these methods revealed four main lineages or clades which do not correspond to the taxonomical hierarchy. In our results, the genus Chymomyza is associated with the subgenus Scaptodrosophila of the genus Drosophila and their cluster constitutes the most ancient clade. The two other clades are constituted of groups belonging to the subgenus Sophophora of the genus Drosophila: the so-called Neotropical clade including the willistoni and saltans groups and the obscura-melanogaster clade itself split into three lineages: (1) obscura group + ananassae subgroup, (2) montium subgroup, and (3) melanogaster + Oriental subgroups. The fourth clade, the Drosophila one, contains three lineages. D. polychaeta, D. iri, and D. fraburu are branched together and constitute the most ancient lineage; the second lineage includes the annulimana, bromeliae, dreyfusi, melanica, mesophragmatica, repleta, robusta, and virilis groups. The third lineage is composed of the immigrans and the cardini, funebris, guaramunu, guarani, histrio, pallidipennis, quinaria, and tripunctata groups. The genera Samoaia, Scaptomyza, and Zaprionus are branched within the Drosophila clade. Although these four clades appear regularly in almost all tree calculations, additional sequencing will be necessary to determine their precise relationships.Correspondence to: M. Pelandakis     

A method for assaying DNA-dependent RNA polymerase II in crude extracts of Drosophila melanogaster adults: Its use in identifying mutants with an altered RNA polymerase II

A method for assaying Drosophila melanogaster adult DNA-dependent RNA polymerase II in crude extracts from as few as two females or three males is described. Preparation of the extracts involves incubating homogenates at 25 C for 60 min and subsequent treatment with Macaloid. Eighty-five percent of the activity in the extracts is inhibited by 1 µg/ml -amanitin and this fraction is attributed to RNA polymerase II. RNA polymerase II activity in the extracts shows a good dose dependence and a partial dependence on added DNA, Mn²⁺, and all four ribonucleoside triphosphates. The kinetics of heat inactivation of RNA polymerase II in crude extracts could be reproducibly measured. Flies of different genotypes had different initial rates of RNA polymerase II heat inactivation. The isolation of Drosophila melanogaster -aminitin-resistant mutants is also reported. Using the assay described in this paper, it appears that the basis for the resistance is an altered RNA polymerase II. The mutation has been mapped to the third chromosome by chromosome replacement.Supported by Grants GM23456 from the NIH and 11259 from the City University Research Foundation.     

Expression of the PI4P 5-kinase Drosophila homologue skittles in the germline suggests a role in spermatogenesis and oogenesis

 We have isolated the Drosophila gene skittles (sktl) which shows homology to members of a novel family of phosphatidylinositol-4-phosphate 5-kinases, including the gene product encoded by the human STM-7.I gene which has been assigned to the neurodegenerative disorder Friedreichs ataxia. In situ hybridization reveals sktl expression during oogenesis and spermatogenesis. Received: 7 February1997 / Accepted: 4 April 1997