Different forces drive the evolution of the Acp26Aa and Acp26Ab accessory gland genes in the Drosophila melanogaster species complex

The Acp26Aa and Acp26Ab genes that code for male accessory gland proteins are tandemly arranged in the species of the Drosophila melanogaster complex. An approximately 1.6-kb region encompassing both genes has been sequenced in 10, 24, and 18 lines from Spain, Ivory Coast, and Malawi, respectively; the previously studied 10 lines from North Carolina have also been included in the analyses. A total of 110 nucleotide and 4 length polymorphisms were detected. Silent variation for the whole Acp26A region was slightly higher in African than in non-African populations, while for both genes nonsynonymous variation was similar in all populations studied. Based on Fst estimates no major genetic differentiation was detected between East and West Africa, while in general non-African populations were strongly differentiated from both African populations. Comparison of polymorphism and divergence at synonymous and nonsynonymous sites revealed that directional selection acting on amino acid replacement changes has driven the evolution of the Acp26Aa protein in the last 2.5 myr.     

Quantitative and qualitative analysis of accessory gland secretory proteins in a few species of Drosophila immigrans group

Quantitative and qualitative analysis of accessory gland proteins in four species of D. immigrans group has been made. Quantitative estimation of these proteins during development of the adult male revealed that there is a gradual increase in the quantity of secretions up to 7 days. The secretions constitute 72, 70, 50 and 54.2% in D.n. nasuta, D.s. neonasuta, D. rubida and D. pararubida respectively. Mating experiments showed that more than 1/3 of this stored secretory protein is transferred into the female reproductive tract during first mating. SDS-PAGE analysis of the accessory gland secretions revealed remarkable simplicity in their patterns, including the absence of age dependent alterations. In all the 4 species analysed, only the low mol. wt. fractions are not glycosylated. It was further observed that the extent of similarity between D.n. nasuta and D.s. neonasuta is greater than between D. rubida and D. pararubida.     

New mutants of Drosophila melanogaster

Characteristics are given of 57 Drosophila melanogaster mutants catched in the South and Soeth-West Iran.     

Formation of the male pronuclear lamina in Drosophila melanogaster

E. coli homologs of the signal recognition particle (SRP) and its receptor are essential for viability, but their role in protein export is unclear. To elucidate their function, we devised a genome-wide screen to identify genes that encode SRP substrates. Inhibition of the SRP pathway sharply blocked the membrane insertion of several polytopic inner membrane proteins (IMPs) that were predicted to be SRP substrates, but had a smaller effect on the insertion of other IMPs and no significant effect on preprotein translocation. Our results suggest that whereas most E. coli preproteins and some IMPs can utilize SRP-independent targeting pathways effectively, the structural features of a subset of IMPs have required the conservation of an SRP-based targeting machinery.     

An accessory sex gland aggression-promoting chemosignal in male mice.

Exps I–IV, with 60 SJL male mice, examined whether voided urine chemosignal activity would be eliminated by removal of the vesicular and coagulating glands, Cowper's gland, the prostate gland, or the preputial gland. Only preputialectomy eliminated the aggression-promoting properties of voided urine, which provides evidence that this gland is a necessary condition for chemoactivity. Exp V, with 24 Ss, examined the efficacy of the preputial gland as sufficient for chemosignal production. Urine from males that had an intact preputial but removed vesicular, coagulating, Cowper's, and prostate glands was assessed and shown to possess the chemocue. It is concluded that the presence of a functional preputial gland is a necessary and sufficient condition for providing an accessory sex gland aggression-promoting chemosignal. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The accumulation of P-element-induced recombinants in the germline of male Drosophila melanogaster

P-element-induced recombination in Drosophila melanogaster occurs premeiotically. Recombinants are therefore expected to accumulate in the stem cells of the germline of P-element-carrying males. We show that both the recombination frequency and the incidence of "clustering" increase with the age of males carrying various P-element derivatives. The combination of end-deleted elements can lead to average recombination frequencies >50% with individual instances of 100% recombination. These elements also lowered the fertility of the carriers. We investigated these features by constructing an analytical and a computer simulation model of the course of events in the germline, incorporating the recently proposed hybrid element insertion (HEI) model of P-element activity. The model is able to predict extreme recombination levels, segregation ratio biases and lowered fertility through cell death in a single analysis.     

Identification of trans-acting genes necessary for centromere function in Drosophila melanogaster using centromere-defective minichromosomes

Deletions in the Drosophila minichromosome Dp1187 were used to investigate the genetic interactions of trans-acting genes with the centromere. Mutations in several genes known to have a role in chromosome inheritance were shown to have dominant effects on the stability of minichromosomes with partially defective centromeres. Heterozygous mutations in the ncd and klp3A kinesin-like protein genes strongly reduced the transmission of minichromosomes missing portions of the genetically defined centromere but had little effect on the transmission of minichromosomes with intact centromeres. Using this approach, ncd and klp3A were shown to require only the centromeric region of the chromosome for their roles in chromosome segregation. Increased gene dosage also affected minichromosome transmission and was used to demonstrate that the nod kinesin-like protein gene interacts genetically with the centro mere, in addition to interacting with extracentromeric regions as demonstrated previously. The results presented in this study strongly suggest that dominant genetic interactions between mutations and centromere-defective minichromosomes could be used effectively to identify novel genes necessary for centromere function.     

Mutation "outbursts" of various genes in natural populations of Drosophila melanogaster

The evaluation and treatment of older men with benign prostatic hyperplasia (BPH) is complicated by the highly variable clinical presentation of men with BPH, which ranges from minor urinary symptoms to acute urinary retention. Treatment choices have expanded with recent advances in medical and surgical therapies. Surgical treatment includes open prostatectomy and transurethral prostatectomy as well as newer technologies that are less invasive and that result in fewer long-term side effects. Response to treatment depends on the patient and should be directed at symptom relief.     

Identification of genes controlling malpighian tubule and other epithelial morphogenesis in Drosophila melanogaster

The Drosophila Malpighian tubule is a model system for studying genetic mechanisms that control epithelial morphogenesis. From a screen of 1800 second chromosome lethal lines, by observing uric acid deposits in unfixed inviable embryos, we identified five previously described genes (barr, fas, flb, raw, and thr) and one novel gene, walrus (wal), that affect Malpighian tubule morphogenesis. Phenotypic analysis of these mutant embryos allows us to place these genes, along with other previously described genes, into a genetic pathway that controls Malpighian tubule development. Specifically, wal affects evagination of the Malpighian tubule buds, fas and thr affect bud extension, and barr, flb, raw, and thr affect tubule elongation. In addition, these genes were found to have different effects on development of other epithelial structures, such as foregut and hindgut morphogenesis. Finally, from the same screen, we identified a second novel gene, drumstick, that affects only foregut and hindgut morphogenesis.     

Relative paucity of genes causing inviability in hybrids between Drosophila melanogaster and D. simulans

Using deficiencies from Drosophila melanogaster, we looked for genomic regions in the sister species D. simulans that could cause lethality when hemizygous on a hybrid genetic background. Such genotypes allow hemizygous genes from one species to interact with heterozygous genes from other species and may correspond to the kinds of genotypes causing Haldane's rule, the observation that if only one gender is sterile or inviable in species hybrids, it is nearly always the heterogametic sex. A survey of roughly 50% of the D. simulans genome (114 chromosome regions) revealed only four regions causing hybrid lethality and five causing severe reductions in hybrid viability. However, the viability of all of these genotypes was at least partially restored by rearing hybrids at lower temperature or using different genetic backgrounds from D. simulans. We therefore detected no D. simulans chromosome regions causing unconditional hybrid lethality, although several regions were shown to be deleterious under most tested temperatures and genetic backgrounds. The relative paucity of "inviability genes" supports the idea, suggested by work on other species, that hybrid inviability between closely related species might be caused by interactions among relatively few genes, while hybrid sterility may involve many more loci.     

Analysis of the genes involved in organizing the tail segments of the Drosophila melanogaster embryo

The metameric organization of the Drosophila melanogaster tail is obscured by developmental events that partially suppress or fuse some of its regions. To better define the developmental origins and segmental identities in the tail of the Drosophila embryo, we documented expression patterns and mutant phenotypes of several genes that play important roles in its morphogenesis. We documented the domains of engrailed (en), Abdominal-B (Abd-B) and caudal (cad) expression in the tail region. The staining pattern of cut (ct) was used to correlate the embryonic sense organs with their respective positions on the larval cuticle. The en patterns in different Bithorax-Complex (BX-C) Abd-B morphogenetic (m) and regulatory (r) mutants demonstrated that Abd-B functions to, among other things, suppress embryonic ventral epidermal structures on the posterior side of A8 to A9. Ventral epidermal structures were not added back into the en pattern in r- or BX-C- mutants, indicating that although the BX-C functions extend through A10, other non-BX-C genes must be required for development of this segment.     

PCNA binding proteins in Drosophila melanogaster : the analysis of a conserved PCNA binding domain

The eukaryotic polymerase processivity factor, PCNA, interacts with cell cycle regulatory proteins such as p21(WAF1/Cip1) and Gadd45, as well as with proteins involved in the mechanics of DNA repair and replication. A conserved PCNA-binding motif is found in a subset of PCNA-interacting proteins, including p21, suggesting that the regulation of these interactions is important for the co-ordination of DNA replication and repair. We have identified several classes of protein which bind to Drosophila PCNA. Two of these proteins contain the consensus PCNA-binding domain: one is the Dacapo protein, a Drosophila homologue of p21(WAF1/Cip1), and the second is the transposase encoded by the Pogo DNA transposon . A conserved PCNA-binding domain is also present in a human relative of Pogo , named Tigger , suggesting that this domain has a functional role in this class of transposable element. This raises interesting possibilities for a novel method of transposition in which the transposase might be targeted to replicating DNA. Finally, we have investigated the use of this conserved PCNA-binding domain as a predictor of PCNA-binding capacity.     

Heterosis for viability, fecundity, and male fertility in Drosophila melanogaster: comparison of mutational and standing variation

If genetic variation for fitness traits in natural populations ("standing" variation) is maintained by recurrent mutation, then quantitative-genetic properties of standing variation should resemble those of newly arisen mutations. One well-known property of standing variation for fitness traits is inbreeding depression, with its converse of heterosis or hybrid vigor. We measured heterosis for three fitness traits, pre-adult viability, female fecundity, and male fertility, among a set of inbred Drosophilia melanogaster lines recently derived from the wild, and also among a set of lines that had been allowed to accumulate spontaneous mutations for over 200 generations. The inbred lines but not the mutation-accumulation (MA) lines showed heterosis for pre-adult viability. Both sets of lines showed heterosis for female fecundity, but heterosis for male fertility was weak or absent. Crosses among a subset of the MA lines showed that they were strongly differentiated for male fertility, with the differences inherited in autosomal fashion; the absence of heterosis for male fertility among the MA lines was therefore not caused by an absence of mutations affecting this trait. Crosses among the inbred lines also gave some, albeit equivocal, evidence for male fertility variation. The contrast between the results for female fecundity and those for male fertility suggests that mutations affecting different fitness traits may differ in their average dominance properties, and that such differences may be reflected in properties of standing variation. The strong differentiation among the MA lines in male fertility further suggests that mutations affecting this trait occur at a high rate.     

DNA base sequence changes induced by diethyl sulfate in postmeiotic male germ cells of Drosophila melanogaster

The DNA base sequence changes induced by diethyl sulfate (DES) were analyzed in postmeiotic male germ cells of Drosophila melanogaster. 31 transmissible vermilion mutants were recovered in F1 and F2 generations, with a frequency of 2.6 x 10(-4) for the F1, and of 1.8-13 x 10(-4) for the F2. The results show that DES induces both base pair substitutions (93%) and deletions (7%). In accord with its relatively high ability to alkylate oxygens in DNA, the most frequent type of sequence alteration among the basepair changes are GC-AT transitions, accounting for 73% of mutations, followed by transversions AT-TA (10%). DES also induced AT-GC transitions and AT-CG transversions. Both induced deletions were intralocus deletions, not occurring between basepair repeats. No influence of neighboring bases on the mutation position was found.     

High divergence of reproductive tract proteins and their association with postzygotic reproductive isolation in Drosophila melanogaster and Drosophila virilis group species

The possible association between gonadal protein divergence and postzygotic reproductive isolation was investigated among species of the Drosophila melanogaster and D. virilis groups. Protein divergence was scored by high-resolution two-dimensional electrophoresis (2DE). Close to 500 protein spots from gonadal tissues (testis and ovary) and nongonadal tissues (malpighian tubules and brain) were analyzed and protein divergence was calculated based on presence vs absence. Both testis and ovary proteins showed higher divergence than nongonadal proteins, and also a highly significant positive correlation with postzygotic reproductive isolation but a weaker correlation with postzygotic reproductive isolation. Particularly, a positive and significant correlation was found between proteins expressed in the testis and postzygotic reproductive isolation among closely related species such as the within-phylad species in the D. virilis group. The high levels of male-reproductive-tract protein divergence between species might be associated with F1 hybrid male sterility among closely related species. If so, a lower level of ovary protein divergence should be expected on the basis that F1 female hybrids are fully fertile. However, this is not necessarily true if relatively few genes are responsible for the reproductive isolation observed between closely related species, as recent studies seem to suggest. We suggest that the faster rate of evolution of gonadal proteins in comparison to nongonadal proteins and the association of that rate with postzygotic reproductive isolation may be the result of episodic and/or sexual selection on male and female molecular traits.     

The relation between reactive oxygen species and cytokines in andrological patients with or without male accessory gland infection

The presence of various cytokines, namely hepatocyte growth factor (HGF), interleukin-1 receptor antagonist (IL-1 RA), and interleukins (IL-1 alpha, IL-6, and IL-8), as well as the production of reactive oxygen species (ROS) was investigated in seminal plasma of fertile and infertile patients in order to evaluate the possible value of measuring these substances for the diagnosis of male accessory gland infection, and to assess the possible relationship between oxidative stress and cytokines during leucocytospermia and male accessory gland infection (MAGI). Our findings indicate that all of the measured cytokines seem to be produced locally as well as by white blood cells (WBC) and that, due to the presence of higher numbers of WBC, accessory gland infection may exert a deleterious effect on sperm quality through the production of ROS and/or of particular cytokines such as IL-1 alpha, IL-1 RA, and IL-8. The most specific marker for a sensitivity of 95% in discriminating between cases with or without MAGI is the measurement of IL-6 in seminal plasma. In the absence of WBC several cytokines are constitutively produced and correlate with sperm concentration (HGF, IL-8), alpha-glucosidase (IL-6), and gamma-glutamyltransferase activity (HGF). The measurement of these cytokines in semen may provide clinically useful information for the diagnosis of male accessory gland infection, as well as in the absence of WBC where it can provide information about certain mechanisms of male reproductive function and dysfunction.     

Geographic variations of life history strategies in Drosophila melanogaster. III. New data

A crucial assumption of evolutionary theories of aging is that age-specific differences of life history traits may have genetic causes. The present study focuses on the existence of such differences between eight freshly caught populations of Drosophila melanogaster. A highly significant differentiation of the populations is observed, yet it accounts for a relatively small part of the variance. It is also shown that large discrepancies may be found between the estimations of fitness based, on the one hand, on data for egg production and, on the other hand, on fertility data. This stresses the need for accurate measurements of fitness for the assessment of evolutionary theories. Finally, the results suggest that neither of the current evolutionary theories of aging is generally valid. Indeed, the age-specific differences that are found between the populations match either the antagonistic pleiotropy mechanism, or the concordant pleiotropy mechanism, or none of them.