Male accessory gland secretory proteins in nasuta subgroup of Drosophila: synthetic activity of Acp

The quantity of male accessory gland secretory proteins in relation to the number of cells in the gland, size of the gland and the duration of copulation has been studied in seven members of the nasuta subgroup of Drosophila. The study revealed that the difference in the quantity of secretions is independent of the number of secretory cells in the gland. However, a positive correlation exists between the quantity of secretions and size of the gland; while there is no correlation between the copulation duration and the quantity of secretions. Further, there is an increase in the values of all the parameters studied, with increasing distance of the species from the ancestor.     

The chromosomes of two Drosophila races: D. nasuta nasuta and D. nasuta albomicana

The microchromosomes of the totally cross fertile Drosophila races, D. nasuta nasuta and D. nasuta albomicana have been studied in nietaphase and polytene nuclei. In metaphase the microchromosome of D. n. albomicana is nearly five times longer than the homologous chromosome in D. n. nasuta. As shown by C-banding these length differences are mainly due to a massive addition of heterochromatin to the D. n. albomicana chromosome. In polytene nuclei these striking heterochromatin differences between the microchromosomes of the two Drosophila races cannot be observed. Analysis of the polytene banding pattern shows that the microchromosomes of both races differ by an inversion and by a duplication, present only in D. n, albomicana. The location and orientation of the duplicated regions in D. n. albomicana leads to a specific loop like chromosome configuration. On the basis of these differences within the Drosophila races studied it is assumed that the karyotype of D. n. albomicana is a more recent evolutionary product.     

Male accessory gland secretory protein polymorphism in natural populations of <Emphasis Type="Italic">Drosophila nasuta nasuta</Emphasis> and <Emphasis Type="Italic">Drosophila sulfurigaster neonasuta</Emphasis>

Male accessory gland secretory protein polymorphism was analysed in natural populations of Drosophila nasuta nasuta and D. sulfurigaster neonasuta for the first time, using SDS-PAGE to score polymorphism of these proteins in 2788 individuals of D. n. nasuta and 2232 individuals of D. s. neonasuta from 12 different populations from southern India. A total of 25 and 18 variant protein phenotypes were identified in D. n. nasuta and D. s. neonasuta, respectively. Protein fractions of group III were more polymorphic than those from groups I and II. The results show that accessory gland secretory proteins show high levels of polymorphism, irrespective of species or habitat. Moreover, we have used the variation in the accessory gland proteins to assess the extent of divergence between the species and to infer their population structure. The study suggests that though both D. n. nasuta and D. s. neonasuta belong to the same subgroup, they differ in population structure, as far as accessory gland protein polymorphism is concerned.     

Male accessory gland secretory proteins in nasuta subgroup of Drosophila: nature and SDS-PAGE patterns

Male accessory gland secretory proteins in seven members of Drosophila nasuta subgroup were analyzed by SDS-PAGE in combination with different staining techniques such as CBB-R250, Silver, PAS, PAS-silver and zinc-imidazole reverse staining. Based on coomassie blue patterns the protein fractions could be classified in to 3 major groups namely group I, group II as well as group III; with high molecular weight fractions falling into group I and low molecular weight fractions into group III. All the three groups of fractions are post-translationally modified by way of glycosylation and group III fractions are found to be highly glycosylated. Fractions of groups I and II when localized with silver stain and group III fractions when localized with PAS-silver stain appear yellow; suggesting that they are sialoglycoproteins. A 40 kD fraction of group II shows differential staining property with zinc-imidazole stain in closely related species namely D. n. nasuta and D. n. albomicans. Analysis of this protein fraction in F1 males of an interspecific cross revealed that it is synthesized by X-chromosomal gene.     

Hybridization and introgression of the genomes of Drosophila nasuta and Drosophila albomicans: evolution of new karyotypes.

Drosophila nasuta (2n = 8) and Drosophila albomicans (2n = 6) are cross-fertile allopatric sibling chromosomal races of the nasuta subgroup of Drosophila. Hybrids of these races can be maintained for any number of generations. Some of the introgressed hybrid lineages of D. nasuta and D. albomicans, after passing through a transient phase of karyotypic polymorphism, ended up with a stable karyotype whose composition is different from those of the parental races. Such hybrid populations were called cytoraces, in which the chromosomes of D. nasuta and D. albomicans are represented in different combinations. The karyotypic composition of 16 such cytoraces have been presented and discussed with reference to evolutionary strategies such as balancing selection, directional selection, and sex-specific effect on different components of the evolving karyotypes.     

Comparative analysis of glue proteins in theDrosophila nasuta subgroup

The patterns of protein fractions from total salivary glands and from glue plugs were compared in seven members of the Drosophila nasuta subgroup by the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The glue protein patterns are member specific concerning the numbers and the electrophoretic mobilities of major and minor glue protein fractions. However, the major fractions of all subgroup members could be grouped into five SDS-PAGE domains according to the homologies of their electrophoretic mobilities, prominence of Coomassie blue staining, and PAS reaction. In all subgroup members, major fractions are involved in posttranslational modifications into larger protein molecules of the final glue. Quantitative estimations of the glue proteins in D. n. nasuta and D. n. albomicans reveal that they constitute between 55 and 60% of the total salivary gland proteins, whereas in D. melanogaster and in D. hydei the fraction is only 32 and 35%, respectively.     

Male accessory gland secretory proteins in a few members of the Drosophila nasuta subgroup

Male accessory gland secretory proteins in seven members of the Drosophila nasuta subgroup have been analyzed by SDS-PAGE. The study revealed remarkable simplicity in the patterns. The protein fractions, which migrate in three groups, could be categorized as major and minor. The number of major fractions varies from a maximum of eight to a minimum of four. Group I consists of high molecular weight fractions, and group III, low molecular weight fractions. Among different members analyzed, the variation with respect to pattern and the number of fractions are confined largely to group III protein fractions, while group I and II fractions are found to be conserved to a greater extent. These proteins are PAS positive and group III fractions are not sensitive to silver staining. Analysis of these tissue specific proteins in the F₁ and F₂ of interspecific crosses and backcross progeny as well as volume analysis revealed that a 26-kD fraction in D. n. nasuta follows an autosomal pattern of inheritance, while a 55-kD and a 25-kD fraction in D. n. albomicans and a 24-kD fraction in D. n. kepulauana follow an X-linked pattern of inheritance.     

Influence of mating histories and age on female remating behaviour in a few closely related species of Drosophila nasuta subgroup

Female remating with more than one male leads to coexistence of sperm from different males in the same female, thus creating a selection pressure on sperm. To understand the extent of divergence in the reproductive behaviour among closely related species, in the present study, the influence of first mating histories like mating latency, duration of copulation and age of flies have been analysed on female remating behaviour in closely related Drosophila nasuta subgroup species with varying levels of reproductive isolation. The time taken for the once mated females to remate varied from 7 days in D. s. sulfurigaster to 19 days in D. s. neonasuta after first mating. The female remating frequency varied from a minimum of 29% in D. s. neonasuta to a maximum of 95% in D. s. sulfurigaster. The younger flies, which had remating latency of three times less than aged flies, show 100% remating frequency. In addition, it was observed that the duration of copulation in the first mating influences the remating behaviour among the nasuta subgroup members. The results revealed that D. nasuta subgroup members despite being closely related differ in their reproductive behaviour.     

Accessory gland secretory proteins in relation to fitness parameters of Drosophila ananassae and D. varians

Developmental morphometry, qualitative and quantitative analysis of the accessory gland secretory proteins, fecundity and productivity in relation to protein ejected during subsequent (first to fourth-time) matings have been studied in Drosophila ananassae Doleschall and Drosophila varians Bock. In both species, size and secretion of accessory glands increases from 1 to 8 days and the stored secretion ejected from males to the female genital tract during subsequent mating varies. The maximum number of eggs and flies are produced from the females mated with bachelor males and it is a minimum when virgin females are mated with fourth-time mated males. Sodium dodecylsulfate–polyacrylamide gel electrophoresis analysis of accessory gland secretory protein patterns and their glycosylation differs in both the species. Correlation coefficient analysis between gland size and quantity of secretion, percentage of secretory protein transferred per mating, and eggs and flies that emerged showed a highly significant, positive relationship. Among different matings, the number of eggs laid and flies that emerged per female between subsequent (first to fourth-time) matings of males was found to be highly significant and the difference between fecundity and productivity between the two species was highly significant.     

Chromosomal polymorphism in Drosophila nasuta. III. Inverted gene arrangements in South Indian populations.

Inversion polymorphism, including a total of 33 inverted gene orders, was studied in South Indian populations of D. nasuta nasuta. Of these, the X chromosome has one, chromosome 2 has 10, and chromosome 3 has 22 inversions. D. nasuta nasuta has simple, tandem, included, overlapping, and complex types of paracentrics in its polymorphic system. The phylogenetic considerations of these gene orders are discussed.     

The chromosomes of two Drosophila races: D. nasuta nasuta and D. nasuta albomicana

Interracial hybridization between Drosophila nasuta nasuta (2n=8) and D. n. albomicana (2n=6) has resulted in the evolution of two new karyotypic strains, called Cytoraces I and II. Males and females of Cytorace I have 2n=7 and 2n=6 respectively. The reconstituted karyotype is totally new in its composition, the chromosomes being drawn from both the parental races. The individuals of Cytorace II have 2n=6. Even though the chromosomes of the parental races are duly represented in the F₁, there is selective retention/elimination of certain chromosomes in the succeeding generations during which repatterning of the karyotype has taken place. Dynamics of each one of the parental chromosomes are presented and its implications re discussed.We dedicate this paper to the memory of the founder of our Department, the late Prof. M.R. Rajasekarasetty on the occasion of the Silver Jubilee of our Department     

The speciation history of the Drosophila nasuta complex

The Drosophila nasuta subgroup of the immigrans species group is widely distributed throughout the South-East Asian region, consisting of morphologically similar species with varying degrees of reproductive isolation. Here, I report nucleotide variability data for five X-linked and two mtDNA loci in eight taxa from the nasuta subgroup, with deeper sampling from D. albomicans and its sister species D. nasuta. Phylogenetic relationships among these species vary among different genomic regions, and levels of genetic differentiation suggest that this species group diversified only about one million years ago. D. albomicans and D. nasuta share nucleotide polymorphisms and are distinguished by relatively few fixed differences. Patterns of genetic differentiation between this species pair are compatible with a simple isolation model with no gene flow. Nucleotide variability levels of species in the nasuta group are comparable to those in members of the melanogaster and pseudoobscura species groups, indicating effective population sizes on the order of several million. Population genetic analyses reveal that summaries of the frequency distribution of neutral polymorphisms in both D. albomicans and D. nasuta generally fit the assumptions of the standard neutral model. D. albomicans is of particular interest for evolutionary studies because of its recently formed neo-sex chromosomes, and our phylogenetic and population genetic analyses suggest that it might be an ideal model to study the very early stages of Y chromosome evolution.     

The chromosomes of two Drosophila races: D. nasuta nasuta and D. n. albomicana

Heterochromatin distribution and differentiation in metaphase chromosomes of two morphologically identical Drosophila races, D. nasuta nasuta and D. n. albomicana, have been studied by C- and N-banding methods. — The total heterochromatin values differ only slightly between these races. However, homologous chromosomes of the two Drosophila forms show striking differences in the size of heterochromatin regions and there is an alternating pattern in D. n. nasuta and D. n. albomicana of chromosomes which contain more, or respectively less heterochromatin than their counterparts in the other race. — Three different N-banding patterns could be obtained depending on the conditions of the method employed: One banding pattern occurs which corresponds to the C-banding pattern. Another pattern is the reverse of the C-band pattern; the euchromatic chromosome regions and the centromeres are stained whereas the pericentric heterochromatin regions remain unstained. In the Y chromosomes of both races and in chromosome 4 of D. n. albomicana, however, the heterochromatin is further differentiated. In the third N-banding pattern only the centromeres are deeply stained. Furthermore, between the races, subtle staining differences in the pericentric heterochromatin regions can be observed as verified in F₁ hybrids. On the basis of C- and N-banding results specific aspects of chromosomal differences between D. n. nasuta and D. n. albomicana are discussed.Dedicated to Prof. W. Beermann on the occasion of his 60th birthday     

Metaphase chromosomes of four species of the Drosophila nasuta subgroup

Metaphase chromosomes of four species of the Drosophila nasuta subgroup, D. nasuta, D. kepulauana, D. kohkoa, and D. neveifrons, were analysed by the C banding method to clarify the chromosomal differentiation during speciation. Four species were different in heterochromatic regions of their chromosomes, especially microchromosomes of the fourth chromosomes and the Y chromosomes. Intraspecific variations of heterochromatic regions were also found among isofemale lines from various localities of D. nasuta, D. kepulauana, and D. kohkoa. Intraspecific variations of heterochromatic regions were not different from interspecific variations morphologically. From these results, the evolutionary process of heterochromatic regions was discussed.     

Molecular phylogeny of the nasuta subgroup of Drosophila based on 12S rRNA, 16S rRNA and CoI mitochondrial genes, RAPD and ISSR polymorphisms

The nasuta subgroup is a cluster of morphologically almost similar forms with a wide range of geographic distribution. During the last three decades nature of inter-relationship among the members has been investigated at different levels of organization. The phylogenetic relationships of the members of the nasuta subgroup of the immigrans species group of Drosophila was made by employing Random Amplified Polymorphic DNA (RAPD), Inter Simple Sequence Repeats-PCR (ISSR-PCR) polymorphisms, mitochondrial 12S rRNA, 16S rRNA and Cytochrome C Oxidase subunit I (CoI) gene sequences. The phylogenetic tree generated by RAPD analysis is in nearly complete congruence with the classification based on morphophenotypic characters. The 12S and 16S rRNA genes were highly conserved across the nasuta subgroup and revealed only 3 and 4 variable sites respectively, of which only one site was informative. The CoI gene, on the other hand, revealed 57 variable sites of which 25 sites were informative. All the three species of orbital sheen complex were included in a major cluster in the phylogenetic trees derived from mitochondrial gene sequence data consistent with the morphophenotypic classification. The CoI analysis placed two species of frontal sheen complex, D. n. nasuta and D. n. albomicans in two different clades and this is inconsistent with morphological classification. The molecular clock suggested that divergence between the kohkoa complex and the albomicans complex occurred approximately 2.2 MYA, indicating recent evolution of the nasuta subgroup. The higher transition bias in the mitochondrial genes reported in the present study also suggested recent evolution of the nasuta subgroup.     

Honey bee males and queens use glandular secretions to enhance sperm viability before and after storage

Internal fertilization requires live sperm to be transferred from male to female before egg fertilization. Both males and females assist the insemination process by providing sperm with glandular secretions, which have been inferred to contain subsets of proteins that maintain sperm viability. Here we show that in the honeybee (Apis mellifera) secretions of the male accessory glands, the major contributors towards seminal fluid, enhance sperm survival. We further demonstrate that the protein fraction of the male accessory gland secretion is indeed important for achieving the maximal effect on sperm survival. After sperm storage, the queens also provide sperm with secretions from spermathecal glands and we show that these secretions have a comparable positive effect on sperm viability. SDS gels show that the proteomic profiles of accessory gland secretion and spermathecal fluid secretion hardly overlap, which suggests that males and females use different proteins to enhance sperm viability during, respectively, ejaculation and final sperm storage.     

Protein profiles of Spodoptera litura (F.) male accessory reproductive gland and its secretions

Protein profiles of the male accessory reproductive glands of a polyphagous pest, Spodoptera litura (Lepidoptera: Noctuidae) and their glandular secretions were analyzed by electrophoresis under denaturing conditions. The study revealed the presence of 23 proteins in the glands and 14 in the secretions. The molecular weights of the gland proteins ranged from 163 to 3.8 KD whereas that of secretions ranged from 100 to 3.8 KD. The 9 low molecular weight proteins of the secretions are a characteristic feature. It is suggested that the secretions may contain a sex peptide that has a role in the fertility and fecundity of the females.     

Electron microscopic band-interband pattern of polytene chromosomes in Drosophila nasuta albomicans. 2. Salivary gland chromosome 2L.

The band-interband pattern (division 28-52) of salivary gland chromosome 2L in Drosophila nasuta albomicans was studied by light (LM) and electron microscopy (EM) using squash preparations and surface-spread polytene (SSP) chromosome preparations, respectively. LM and EM maps were complied. Based on the digitized EM patterns of five homologous SSP chromosomes a computerized EM chromosome map was plotted. The EM pattern analysis showed a total number of 479 chromosome bands with an almost 83% increase compared with the LM analysis of squash preparations. By extrapolation of the data from 39% of the polytene genome analysed so far in D. n. albomicans, a total number of 2,926 chromosome bands was calculated. This is almost the same number of bands as was calculated earlier for Drosophila hydei using the same SSP chromosome preparation technique. The data in the literature concerning variations in the number of chromosome bands in different Drosophila species, the various chromosome preparation techniques adopted, and the different criteria used for the EM pattern analyses, are discussed.