Search

SignificanceIn species with internal fertilization, sperm spend an important part of their lives within the female. To examine the life history of the sperm during this time, we used semiquantitative proteomics and sex-specific isotopic labeling in fruit flies to determine the extent of molecular continuity between male and female reproductive tracts and provide a global catalog of sperm-associated proteins. Multiple seminal fluid proteins and female proteins associate with sperm immediately after mating. Few seminal fluid proteins remain after long-term sperm storage, whereas female-derived proteins constitute one-fifth of the postmating sperm proteome by then. Our data reveal a molecular "hand-off" from males to females, which we postulate to be an important component of sperm-female interactions.

We studied sperm displacement in two members of the Drosophila bipectinata species complex i.e., Drosophila parabipectinata and Drosophila malerkotliana by employing mutant and wild type strains. We found a significant increase in the productivity of remated females than that of once mated ones in all the crosses of the two species. The P2' values range from 0.67 to 0.70 in D. malerkotliana and 0.52 to 0.56 in D. parabipectinata. These results were compared with that of our earlier finding in D. bipectinata belonging to the same complex. We found that though the three species exhibit differences in the degree of sperm displacement, the pattern is somewhat similar in the three species. However, as far as its genetic variability and population size maintenance is considered, D. malerkotliana and D. bipectinata (P2' is 0.60-0.67) are at the forefront. Our finding is also supported by the fact that D. parabipectinata is derived from D. bipectinata and has not diverged much since its emergence as a separate species. The differences in the pattern of sperm displacement may be attributed to differences in remating latency, duration of copulation in first mating and sperm usage pattern among the members of this complex., (Published by Elsevier B.V.)

The power of sexual selection to drive changes in the mate recognition system through divergence in sexually selected traits gives it the potential to be a potent force in speciation. To know how sexual selection can bring such type of divergence in the genus Drosophila, comparative studies based on intra- and inter-sexual selection are documented in this review. The studies provide evidence that both mate choice and male-male competition can cause selection of trait and preference which thereby leads to divergence among species. In the case of intrasexual selection, various kinds of signals play significant role in affecting the species mate recognition system and hence causing divergence between the species. However, intrasexual selection can bring the intraspecific divergence at the level of pre- and post-copulatory stage. This has been better explained through Hawaiian Drosophila which has been suggested a wonderful model system in explaining the events of speciation via sexual selection. This is due to their elaborate mating displays and some kind of ethological isolation persisting among them. Similarly, the genetic basis of sexually selected variations can provide yet another path in understanding the speciation genetics via sexual selection more closely.

Significant interspecific variations in mean duration of copulation and fertility were observed in four species of the Drosophila bipectinata species complex. However, D. bipectinata showed positive correlation between duration of copulation and fertility. Similarly, D. malerkotliana showed negative correlation between mating latency and duration of copulation. Likewise, D. pseudoananassae showed positive correlation between mating latency and fertility. These results suggest that D. pseudoananassae has distant relatedness from the other three species with respect to mating latency, duration of copulation and fertility which supports the previous findings.

Intra- and interspecific variations in female and male remating frequency, latency, and duration of copulation in first and second matings were analyzed in four species of the Drosophila bipectinata complex, employing four strains of each species i.e. D. bipectinata, D. parabipectinata, D. malerkotliana and D. pseudoananassae. Chi-square test revealed significant intraspecific variation in the number of remated females and males in D. malerkotliana and D. bipectinata, whereas D. parabipectinata showed insignificant intraspecific variations in number of remated females and males. D. pseudoananassae showed significant intraspecific variation in the number of remated females, but the frequency of remating was least. One way ANOVA depicted significant intraspecific variation in female and male remating time in D. bipectinata and D. parabipectinata. D. bipectinata took the shortest time to remate and the duration of copulation in first mating was longest. However, D. pseudoananassae exhibited the longest remating time and long duration of copulation in first mating. Results of t-test depicted that all four species exhibited shorter duration of copulation in second mating as compared to the first. Our study puts D. bipectinata and D. pseudoananassae at two extremes, and D. parabipectinata and D. malerkotliana at an intermediate position in a hierarchy of remating behaviours., (Copyright © 2013 Elsevier B.V. All rights reserved.)

With the extensive usage of gold nanoparticles (AuNPs) in various industrial sectors and biomedical applications, evaluation of their possible effects on human health becomes imperative. Therefore, the present study was aimed toward assessing the dose-dependent impact of AuNPs ingestion on metabolic homeostasis using Drosophila melanogaster as a model system. We found that larval ingestion of higher dose of AuNPs significantly reduced body weight. Further analysis of the crucial energy reservoir showed selective alteration in carbohydrate levels without any change in the lipid and protein levels. Transcriptional downregulation of glycogen synthase further supported impaired glycogen metabolism in flies supplemented with higher dose of AuNPs. Additionally, ingestion of higher dose of AuNPs in larvae results in significantly increased levels of reactive oxygen species (ROS) in the peripheral tissues, suggestive of stress condition. Our findings clearly imply that supplementing higher doses of AuNPs at an early developmental stage can potentially cause weight loss, impair glycogen metabolism, and elevate ROS production. Therefore, determination of a biologically effective dose is critical for the safety of mankind and vulnerable populations at the workplace. [ABSTRACT FROM AUTHOR]

In Drosophila bipectinata female remating with respect to productivity and sperm displacement was studied by employing two mutant strains and a wild-type strain. The comparison of productivity between once-mated (control) and remated females revealed that the productivity of remated females is significantly higher than that of once-mated females in all the crosses showing increased productivity after remating. The P2' values (proportion of second male progeny produced after remating) were calculated to test sperm displacement in each cross of remated females, which range from 0.60 to 0.67 extending the evidence for sperm displacement in D. bipectinata. [ABSTRACT FROM AUTHOR]

Huntington's disease (HD) is an inherited, progressively debilitating disorder marked by prominent degeneration in striatal and cortical brain regions. HD is caused by (CAG) n repeat expansion in huntingtin (HTT) gene that translates into a mutant form of the ubiquitously present Huntingtin (HTT) protein. Extensive metabolic dysfunction coexisting with overt neuropathies has been evidenced in clinical and experimental settings of HD. Body weight loss despite normal to high caloric intake remains a critical determinant of the disease progression and a challenge for therapeutic interventions. In the present study, we intended to monitor the cellular and molecular perturbations in Drosophila, caused by pan-neuronal expression of mHTT (mutant Huntingtin) protein. We found aberrant transcription profile of key lipolytic and lipogenic genes in whole-body of the fly with disease progression. Interestingly, fatbody undergoes extensive alteration of vital cellular processes and eventually surrenders to increased apoptotic cell death in terminal stage of the disease. Extensive mitochondrial dysfunction from early disease stage along with calcium derangement at terminal stage were observed in fatbody, which contribute to its deteriorating integrity. All the mechanisms were monitored progressively, at different disease stages, and many alterations were documented in the early stage itself. Our study hence provides insight into the mechanisms through which neuronal expression of mHTT might be inflicting the profound systemic effects, specifically on lipid metabolism, and may open new therapeutic avenues for alleviation of the multidimensional disease. • Transcriptional dysregulation of brummer and lipin is evidenced in HD condition. • Fatbody undergoes apoptosis with disease progression. • Reduced mitochondrial membrane potential in fatbody contributes to its apoptosis. • Calcium derangement is evident at terminal stage in fatbody of HD flies. [ABSTRACT FROM AUTHOR]