Taxonomic problems in the Drosophila melanica species group (Diptera : Drosophilidae) from southern China, with special reference to karyotypes and reproductive isolation

Karyotypes and reproductive isolation were studied in two allopatric populations of Drosophila tsigana, one from Guizhou Province in southern China and the other from Hokkaido in northern Japan, and in one population of a closely related species, D. longi

Molecular phylogeny of the Drosophila virilis section (Diptera : Drosophilidae) based on mitochondrial and nuclear sequences

Regardless of the well-documented virilis species group, most groups of the Drosophila virilis section have not been completely studied at molecular level since it was suggested. Therefore, phylogenetic relationships among and within species groups of the

Drosophila subpulchrella, a new species of the Drosophila suzukii species subgroup from Japan and China (Diptera : Drosophilidae)

Drosophila (Sophophora) subpulchrella Takamori and Watabe, sp. nov., of the D. suzukii subgroup in the D. melanogaster species group, is described from Japan and southern China, and compared with its sibling species, D. pulchrella Tan et al. distributed i

Genetic differentiation and cryptic speciation in natural populations of Drosophila lacertosa

Drosophila lacertosa, an Oriental member of the robusta species group in the virilis-repleta radiation, has a wide distribution from northern India throughout China to the Far East. Phylogenetic analyses of mitochondrial ND2 gene sequences revealed two ge

Effect of oxidation of dietary fish lipids on the quality of proteins in diet

The paper reports results of a study on the effect of oxidised fish oil in the diet on the quality of dietary fish proteins. With increased oxidation of oil, digestibility and utilization of the protein registered a decrease. Oxidation of fish oil beyond a stage was found to affect the intake of diet itself and rats lost weight rapidly.

Nucleotide variation and recombination along the fourth chromosome in Drosophila simulans

The fourth chromosome of Drosophila melanogaster and its sister species are believed to be nonrecombining and have been a model system for testing predictions of the effects of selection on linked, neutral variation. We recently examined nucleotide variat

Duplication-degeneration as a mechanism of gene fission and the origin of new genes in Drosophila species

Gene fission and fusion, the processes by which a single gene is split into two separate genes and two adjacent genes are fused into a single gene, respectively, are among the primary processes that generate new genes(1-4). Despite their seeming reversibi

Identification and characterization of insect-specific proteins by genome data analysis

Background: Insects constitute the vast majority of known species with their importance including biodiversity, agricultural, and human health concerns. It is likely that the successful adaptation of the Insecta clade depends on specific components in its

On the origin of new genes in Drosophila

Several mechanisms have been proposed to account for the origination of new genes. Despite extensive case studies, the general principles governing this fundamental process are still unclear at the whole-genome level. Here, we unveil genome-wide patterns

Repetitive element-mediated recombination as a mechanism for new gene origination in Drosophila

Previous studies of repetitive elements (REs) have implicated a mechanistic role in generating new chimerical genes. Such examples are consistent with the classic model for exon shuffling, which relies on non-homologous recombination. However, recent data

Recombination Yet Inefficient Selection along the Drosophila melanogaster Subgroup's Fourth Chromosome

A central goal of evolutionary genetics is an understanding of the forces responsible for the observed variation, both within and between species. Theoretical and empirical work have demonstrated that genetic recombination contributes to this variation by breaking down linkage between nucleotide sites, thus allowing them to behave independently and for selective forces to act efficiently on them. The Drosophila fourth chromosome, which is believed to experience no-or very low-rates of recombination has been an important model for investigating these effects. Despite previous efforts, central questions regarding the extent of recombination and the predominant modes of selection acting on it remain open. In order to more comprehensively test hypotheses regarding recombination and its potential influence on selection along the fourth chromosome, we have resequenced regions from most of its genes from Drosophila melanogaster, D. simulans, and D. yakuba. These data, along with available outgroup sequence, demonstrate that recombination is low but significantly greater than zero for the three species. Despite there being recombination, there is strong evidence that its frequency is low enough to have rendered selection relatively inefficient. The signatures of relaxed constraint can be detected at both the level of polymorphism and divergence.

Influence of dietary proteins on cholesterol levels in albino rats

Six groups of albino rats were fed identical diets, differing in their protein sources for sixty days. The protein sources used were fat free casein, defatted groundnut cake, and defatted fish powders from three species of fishes, namely, the fresh water fish Labeo rohita, the marine fishes, Rastrelliger kanagurta and Otolithus argenteus and marine prawns, Parapenaeopsis stylifera. After sixty days, the levels of cholesterol in the serum, liver and heart of the rats were estimated. The casein group recorded the highest level of cholesterol. Compared to casein, the groundnut protein was distinctly hypocholesterolemic. The fish proteins had a still greater cholesterol lowering ability. Of the proteins used in this study, the proteins of prawns had the maximum hypocholesterolemic effect. An attempt is made to correlate the behaviour of the proteins in this respect, with their respective amino acid compositions.

MITOCHONDRIAL-DNA POLYMORPHISM IN NATURAL-POPULATIONS OF DROSOPHILA-ALBOMICANS(I)

The technique of mtDNA restriction fragments length polymorphism (RFLP) was used to survey the population structure of D. albomicans. Remarkable mtDNA polymorphism has been observed in D. albomicans populations. A total of 34 nucleomorphs were detected from 82 isofemale lines assayed by only 8 restriction enzymes. The cause and the effect of this phenomenon were discussed. As a result, it is suggested that a mechanism which maintains mtDNA diversity exists in this fly, and that the high intra-populational polymorphism could numerically conceal the extent of differentiation between populations. In addition, on the base of restriction maps, it was found that the mtDNA molecule of D. albomicans might be impacted by the selection pressure during its evolution process both on the nucleotide composition and on the functional regions.