The Drosophila genome sequence: implications for biology and medicine

The 120-megabase euchromatic portion of the Drosophila melanogaster genome has been sequenced. Because the genome is compact and many genetic tools are available, and because fly cell biology and development have much in common with mammals, this sequence may be the Rosetta stone for deciphering the human genome.     

Comparative genome and proteome analysis of Anopheles gambiae and Drosophila melanogaster

Comparison of the genomes and proteomes of the two diptera Anopheles gambiae and Drosophila melanogaster, which diverged about 250 million years ago, reveals considerable similarities. However, numerous differences are also observed; some of these must reflect the selection and subsequent adaptation associated with different ecologies and life strategies. Almost half of the genes in both genomes are interpreted as orthologs and show an average sequence identity of about 56%, which is slightly lower than that observed between the orthologs of the pufferfish and human (diverged about 450 million years ago). This indicates that these two insects diverged considerably faster than vertebrates. Aligned sequences reveal that orthologous genes have retained only half of their intron/exon structure, indicating that intron gains or losses have occurred at a rate of about one per gene per 125 million years. Chromosomal arms exhibit significant remnants of homology between the two species, although only 34% of the genes colocalize in small "microsyntenic" clusters, and major interarm transfers as well as intra-arm shuffling of gene order are detected.     

The Release 5.1 annotation of Drosophila melanogaster heterochromatin

The repetitive DNA that constitutes most of the heterochromatic regions of metazoan genomes has hindered the comprehensive analysis of gene content and other functions. We have generated a detailed computational and manual annotation of 24 megabases of heterochromatic sequence in the Release 5 Drosophila melanogaster genome sequence. The heterochromatin contains a minimum of 230 to 254 protein-coding genes, which are conserved in other Drosophilids and more diverged species, as well as 32 pseudogenes and 13 noncoding RNAs. Improved methods revealed that more than 77% of this heterochromatin sequence, including introns and intergenic regions, is composed of fragmented and nested transposable elements and other repeated DNAs. Drosophila heterochromatin contains "islands" of highly conserved genes embedded in these "oceans" of complex repeats, which may require special expression and splicing mechanisms.     

Sex peptide of Drosophila melanogaster

All tested stocks of Drosophila melanogaster exhibit a peptide in males but not in females. The failure of some investigators to demonstrate its presence is attributable to their choice of chromatographic solvents. Acid hydrolysis confirms its peptide identity. Its presence in females transformed into males by the mutant tra implicates the sex-determining loci in its formation.     

黑腹果蝇的一些生物学特性观察

在室内对危害葡萄的黑腹果蝇的一些生物学特性进行了深入观察。结果表明,黑腹果蝇在25℃下卵、幼虫、蛹的发育历期分别为（1.08±0.19）,（4.39±0.43）,（3.9±0.25）d。成虫交尾时间集中在21：30-23：00,持续5-20 min,交尾后具有梳理行为。并常将卵产在果肉边缘的坡面上,每次产2-8粒。幼虫喜在葡萄梗、器皿壁等较硬场所化蛹。羽化时间集中在4：30-7：30。成虫对不同水果的嗜好强弱程度是依次是葡萄、苹果、香蕉、桃、梨;而对巨峰、马奶、无核白、红提等葡萄品种的嗜好程度无显著性差异（P〉0.05）,但葡萄损伤时间影响其嗜好程度,对损伤3 d和4 d的葡萄嗜好程度显著高于损伤2 d的葡萄,也都极显著高于损伤1 d的（P〈0.01）。幼虫对葡萄和香蕉嗜好程度显著高于梨、桃和苹果（P〈0.05）;对红提的嗜好程度显著大于巨峰、马奶、无核白品种。     

Hybrid dysgenesis in Drosophila melanogaster

Several dysgenic traits may occur within the Drosophila melanogaster species as a result of crosses between different strains. Crossing two mutually interacting categories, named inducer and reactive, may lead, among other abnormalities, to a specific kind of female sterility that has proved useful for investigating the genetic factors involved in the interaction. The reactive state appears to result from a cytoplasmic state ultimately controlled by a chromosomal polygenic system. The inducer character is determined by a chromosomal factor that exhibits all characteristics of a transposable element. Overall, the data contribute to clarification of mutator activities in D. melanogaster and open new opportunities to investigate unusual genetic mechanisms.     

The 1.2-megabase genome sequence of Mimivirus

We recently reported the discovery and preliminary characterization of Mimivirus, the largest known virus, with a 400-nanometer particle size comparable to mycoplasma. Mimivirus is a double-stranded DNA virus growing in amoebae. We now present its 1,181,404-base pair genome sequence, consisting of 1262 putative open reading frames, 10% of which exhibit a similarity to proteins of known functions. In addition to exceptional genome size, Mimivirus exhibits many features that distinguish it from other nucleocytoplasmic large DNA viruses. The most unexpected is the presence of numerous genes encoding central protein-translation components, including four amino-acyl transfer RNA synthetases, peptide release factor 1, translation elongation factor EF-TU, and translation initiation factor 1. The genome also exhibits six tRNAs. Other notable features include the presence of both type I and type II topoisomerases, components of all DNA repair pathways, many polysaccharide synthesis enzymes, and one intein-containing gene. The size and complexity of the Mimivirus genome challenge the established frontier between viruses and parasitic cellular organisms. This new sequence data might help shed a new light on the origin of DNA viruses and their role in the early evolution of eukaryotes.     

Drosophila melanogaster as an experimental organism

The fruit fly Drosophila melanogaster has been used as an experimental organism in studies of genetics since the early 1900s. It is now widely used not only in classical and molecular genetics but also, with many new biochemical, cell biological, and physiological techniques, to research problems requiring a multidisciplinary approach, such as those of developmental biology and neurobiology.     

Age-dependent changes in proteins of Drosophila melanogaster

Several molecular theories of aging postulate that there are age-dependent changes in gene expression and that these changes contribute to the reduction in the viability of senescent cells. High-resolution, semiautomated, quantitative two-dimensional gel electrophoresis of many soluble proteins was used to test this hypothesis in Drosophila. Two-dimensional protein gel patterns were analyzed for each of three age groups of [(35)S]methionine-labeled adult male Drosophila melanogaster, which, except for their spermatocytes, consist entirely of fixed postmitotic cells. Seven relatively abundant polypeptides expressed in middle-aged (28-day-old) flies were absent in both young(10-day-old) and old (44-day-old) flies. Quantitative analyses of an additional 100 polypeptides were carried out by computer-assisted microdensitometry of fluorograms of the gel preparations. These analyses revealed a significant age-related heterogeneity in the quantitative distribution of radiolabel in these proteins. The data indicate that the qualitative pattern of gene expression is identical in young and old flies, but that profound quantitative changes occur in the expression of proteins during the Drosophila life-span.     

Steroid control of longevity in Drosophila melanogaster

Ecdysone, the major steroid hormone of Drosophila melanogaster, is known for its role in development and reproduction. Flies that are heterozygous for mutations of the ecdysone receptor exhibit increases in life-span and resistance to various stresses, with no apparent deficit in fertility or activity. A mutant involved in the biosynthesis of ecdysone displays similar effects, which are suppressed by feeding ecdysone to the flies. These observations demonstrate the importance of the ecdysone hormonal pathway, a new player in regulating longevity.     

Esterase 6 and reproduction in Drosophila melanogaster

A nonspecific carboxylesterase (esterase 6) of Drosophila melanogaster shows greater activity in adult males than in females and is highly concentrated in the anterior ejaculatory duct of the reproductive tract of the male. Esterase 6 is depleted in males by copulation and is transferred to females early during copulation as a component of the seminal fluid. That esterase 6 may be involved in a system controlling the timing of remating is suggested by differences in the activity of this enzyme in a strain of Drosophila selected for a decrease in time to remating and by differences in the timing of remating in females initially inseminated by males lacking or having active esterase 6.     

Molecular transfer of a species-specific behavior from Drosophila simulans to Drosophila melanogaster

Drosophila males modulate the interpulse intervals produced during their courtship songs. These song cycles, which are altered by mutations in the clock gene period, exhibit a species-specific variation that facilitates mating. We have used chimeric period gene constructs from Drosophila melanogaster and Drosophila simulans in germline transformation experiments to map the genetic control of their song rhythm difference to a small segment of the amino acid encoding information within this gene.