The consequences of genetic variation in sex peptide expression levels for egg laying and retention in females

The accessory gland proteins (Acps) that male Drosophila melanogaster produce and transfer to females during copulation are key to male and female fitness. One Acp, the sex peptide (SP), is largely responsible for a dramatic increase in female egg laying and decrease in female receptivity after copulation. While genetic variation in male SP expression levels correlate with refractory period duration in females, it is unknown whether male SP expression influences female egg laying or if any effect of SP is mediated by SP retention in the female reproductive tract. Here we measured the amount of SP retained in the female reproductive tract after mating and female egg laying after copulating with virgin males. We found no correlation between male SP expression levels and egg laying, or the amount of SP in the female reproductive tract after mating. Additionally, the amount of SP retained in the female did not influence egg laying. These finding suggests that additional factors, such as variation in other Acps, are important for the retention of SP in females and its quantitative effects on egg laying. It also shows that egg laying and refractory period response to SP is at least partially uncoupled.     

Inhibition of female mating by male accessory gland substances in the ground beetle Leptocarabus procerulus

The ground beetle Leptocarabus procerulus (Chaudoir) possesses seminal substances that have a physical function to form mating plugs and a physiological function to induce female refractory behaviour, which act together to hinder female remating. Little is known about the physiological properties of the substances inducing female refractory behaviour, especially with respect to their secretory organ, dose‐dependency, molecular characteristics and the effect of female maturity. By injecting male‐derived substances into females, substances that induce female refractory behaviour are shown to be produced in the male accessory gland but not in the testis. Injection of extracts from the accessory gland increases the female refractory period at moderate doses but not at lower or higher doses. By contrast, injection of extracts from the testis reduces the female refractory period at high doses. The lack of an effect of accessory gland substances at higher doses could be the result of an anomalous effect of unnaturally large doses of seminal products by direct injection, the toxicity of seminal substances that deter female responses, or counteraction by injected substances that promote female receptivity. The accessory gland substances lose their activity when heated, although the testis substances do not. Females without mature eggs tend to reject mating entirely, although variation in the number of mature eggs (one or more) is not associated with the female refractory period, indicating the limited effect of female reproductive maturity. These findings may help to clarify the physiological basis of the evolution of the elaborated male mating behaviour in L. procerulus.     

Sex peptide causes mating costs in female Drosophila melanogaster

Conflicts between females and males over reproductive decisions are common . In Drosophila, as in many other organisms, there is often a conflict over how often to mate. The mating frequency that maximizes male reproductive success is higher than that which maximizes female reproductive success . In addition, frequent mating reduces female lifespan and reproductive success , a cost that is mediated by male ejaculate accessory gland proteins (Acps) . We demonstrate here that a single Acp, the sex peptide (SP or Acp70A), which decreases female receptivity and stimulates egg production in the first matings of virgin females , is a major contributor to Acp-mediated mating costs in females. Females continuously exposed to SP-deficient males (which produce no detectable SP ) had significantly higher fitness and higher lifetime reproductive success than control females. Hence, rather than benefiting both sexes, receipt of SP decreases female fitness, making SP the first identified gene that is likely to play a central role in sexual conflict.     

Female Drosophila melanogaster suffer reduced defense against infection due to seminal fluid components

Reduced defense against infection is commonly observed as a consequence of reproductive activity, but little is known about how post-mating immunosuppression occurs. In this work, we use Drosophila melanogaster as a model to test the role of seminal fluid components and egg production in suppressing post-mating immune defense. We also evaluate whether systemic immune system activity is altered during infection in mated females. We find that post-mating reduction in female defense depends critically on male transfer of sperm and seminal fluid proteins, including the accessory gland protein known as "sex peptide." However, the effect of these male factors is dependent on the presence of the female germline. We find that mated females have lower antimicrobial peptide gene expression than virgin females in response to systemic infection, and that this lower expression correlates with higher systemic bacterial loads. We conclude that, upon receipt of sperm and seminal fluid proteins, females experience a germline-dependent physiological shift that directly or indirectly reduces their overall ability to defend against infection, at least in part through alteration of humoral immune system activity.     

烟夜蛾雄蛾性附腺因子对雌蛾性信 息素合成的抑制作用

烟夜蛾Helicoverpa assulta处女蛾在交配后1 h,其性信息素滴度即显著降低,72 h内未见恢复。生测结果表明,烟夜蛾性信息素合成抑制因子主要来源于雄蛾性附腺。不同日龄雄蛾性附腺提取物的抑制活性无显著差异。光暗期对其活性具显著影响,暗期中雄蛾的性附腺物质对雌蛾性信息素合成具有较强抑制作用,而光期中雄蛾的性附腺物质不具抑制活性。在暗期的不同时间处理,对处女蛾性信息素合成的抑制作用无显著差异。雄蛾性附腺提取物对雌蛾性信息素合成的抑制作用与注射剂量有明显的相关性,0.2 ME（雄蛾当量）是产生显著抑制作用的最小剂量。对交配雌蛾注射性信息素生物合成激活神经肽（PBAN）提取物后,其性信息素合成又可恢复,这说明雌蛾交配后,性信息素滴度降低的原因是由于缺少了PBAN的调控。     

Biosynthetic maturation of the corpus allatum of the female adult medfly,Ceratitis capitata,and its putative control

The major juvenile hormone (JH) homolog synthesized in vitro by the adult female Medfly (Ceratitis capitata) corpus allatum (CA) is JHB(3), with JH-III the minor homolog. Methyl-incorporation in vitro in post-eclosion virgin females is age-dependent. Basal activity occurs during the first four days post-eclosion and increases significantly thereafter, peaking at five days. Biosynthetic maturation of the mated female CA is delayed by one day and reduced considerably. The delayed response may be due to direct cerebral or neural inhibition. Synthetic Drosophila melanogaster sex peptide depresses JH biosynthesis by the Medfly female CA in vitro. Male-derived accessory gland peptides of the Medfly are transferred to the female during mating and a Medfly SP-analog may be responsible for down-regulation of JH synthesis by the CA in mated Medfly females. Mevinolin, an inhibitor of the mevalonate pathway, significantly reduces the biosynthesis of JHB(3), while farnesoic acid, a proximate precursor of JHIII, significantly stimulates the biosynthesis of both JHB(3) and JHIII in vitro.     

Evidence for mating plugs in the fire ant <Emphasis Type="Italic">Solenopsis invicta</Emphasis>

Summary Male inhibition of female re-mating is com-mon in many insects. Mating plugs, used by males to con-trol female re-mating, have been postulated in several ant species. Recent studies of bumblebees have described re-mating inhibition by male accessory gland secretions. Fire ants Solenopsis invicta possess accessory glands containing the same four fatty acids as do the bumblebees. Furthermore it appears that some of these acids are transferred to the female at mating. Thus, it is possible that single mating of fire ant females may be enforced by male mating plugs.     

Humoral autoimmune response to rat male accessory glands. Immunogenicity of different autoantigen moiety for male and female rats

The efficiency of autoantigen fragments (Fa and Fc) to trigger a memory autoimmune response in rats primed with chemically modified rat male accessory glands (MRAG) was assayed by reimmunizing them with the fragments coupled to human serum albumin (Fa-HSA and Fc-HSA). The humoral immune response assay by ELISA and passive hemagglutination revealed that a high level of antibodies reactive with the autoantigen of accessory glands is triggered by Fa-HSA in male and by Fc-HSA in female rats, whereas Fc in male and Fa in female rats did not stimulate appreciable levels of antibodies. Furthermore, the specificities of male and female antibodies were directed mainly to Fa and Fc epitopes, respectively. Therefore, Fa behaved like a more immunogenic fragment for male rats and Fc for female rats.     

Effects of sperm on female longevity in the bumble-bee Bombus terrestris L

The male ejaculate, particularly the accessory gland products, has been shown to affect female survival (as is best understood in Drosophila melanogaster). So far, these findings have primarily been discussed in the context of a sexual conflict and multiple mating. Here, we show that in the bumble-bee Bombus terrestris, male genotype influences female longevity even though B. terrestris generally is a singly mated species and male and female interests may thus be more convergent. In addition, the effect could not be owing to accessory gland products, as we artificially inseminated the queens with the content of the accessory testes only.     

Drosophila males transfer antibacterial proteins from their accessory gland and ejaculatory duct to their mates

The male fruitfly, Drosophila melanogaster, transfers to his mate proteins that increase his reproductive success by causing changes in her behavior and physiology. Here we show that among the transferred proteins are ones with antibacterial activity. We performed Escherichia coli overlay assays of native PAGE or renatured SDS-PAGE of reproductive tissue extracts of wild-type or transgenic males deficient in accessory gland function. We detected a 28 kDa male accessory gland-derived protein and two ejaculatory duct-derived proteins all with antibacterial activity. Based on its gel mobility and tissue of synthesis, one of the ejaculatory duct proteins is likely to be andropin, a previously-reported 6 kDa antibacterial peptide. All three proteins are transferred to females during mating. Therefore, they could assist in protecting the male's reproductive tract and, after transfer to the female, the female's reproductive tract or eggs against bacterial infection. Since seminal fluid proteins are transferred before the sperm, these antibacterial proteins may also protect sperm from bacterial infection.     

A Novel Function for the Hox Gene Abd-B in the Male Accessory Gland Regulates the Long-Term Female Post-Mating Response in Drosophila

In insects, products of the male reproductive tract are essential for initiating and maintaining the female post-mating response (PMR). The PMR includes changes in egg laying, receptivity to courting males, and sperm storage. In Drosophila, previous studies have determined that the main cells of the male accessory gland produce some of the products required for these processes. However, nothing was known about the contribution of the gland''s other secretory cell type, the secondary cells. In the course of investigating the late functions of the homeotic gene, Abdominal-B (Abd-B), we discovered that Abd-B is specifically expressed in the secondary cells of the Drosophila male accessory gland. Using an Abd-B BAC reporter coupled with a collection of genetic deletions, we discovered an enhancer from the iab-6 regulatory domain that is responsible for Abd-B expression in these cells and that apparently works independently from the segmentally regulated chromatin domains of the bithorax complex. Removal of this enhancer results in visible morphological defects in the secondary cells. We determined that mates of iab-6 mutant males show defects in long-term egg laying and suppression of receptivity, and that products of the secondary cells are influential during sperm competition. Many of these phenotypes seem to be caused by a defect in the storage and gradual release of sex peptide in female mates of iab-6 mutant males. We also found that Abd-B expression in the secondary cells contributes to glycosylation of at least three accessory gland proteins: ovulin (Acp26Aa), CG1656, and CG1652. Our results demonstrate that long-term post-mating changes observed in mated females are not solely induced by main cell secretions, as previously believed, but that secondary cells also play an important role in male fertility by extending the female PMR. Overall, these discoveries provide new insights into how these two cell types cooperate to produce and maintain a robust female PMR.     

The Male Accessory Gland Substances of Lucilia illustris (I): Its Effect on Mating Receptivity

ABSTRACT In order to verify the physiological functions of male accessory gland (MAG) substances of the blowfly, Lucilia illustris Meigen, the growth and changes in metabolites of male accessory gland with aging, and the effect of male accessory gland extract on mating receptivity of L. illustris were examined. There was not a significant difference in length of MAG with aging, but the width of MAG was grown widely from 0 to 5-days old apparently. Changes in glycogen, total protein and lipid of male accessory gland substances showed same patterns but total protein content was higher than the others. Therefore, male nutrition affected the production of male accessory proteins. During the mating fed unmated male transferred larger amount of protein than that of starved male. When male accessory gland homogenates injected, mating receptivity of gravid female was greatly inhibited comparing to control, suggesting that the accessory gland substances of L. illustris alters female mating receptivity after mating.     

Correlated evolution of female neoteny and flightlessness with male spermatophore production in fireflies (Coleoptera: Lampyridae)

The beetle family Lampyridae (fireflies) encompasses ～100 genera worldwide with considerable diversity in life histories and signaling modes. Some lampyrid males use reproductive accessory glands to produce spermatophores, which have been shown to increase female lifetime fecundity. Sexual dimorphism in the form of neotenic and flightless females is also common in this family. A major goal of this study was to test a hypothesized link between female flight ability and male spermatophore production. We examined macroevolutionary patterns to test for correlated evolution among different levels of female neoteny (and associated loss of flight ability), male accessory gland number (and associated spermatophore production), and sexual signaling mode. Trait reconstruction on a molecular phylogeny indicated that flying females and spermatophores were ancestral traits and that female neoteny increased monotonically and led to flightlessness within multiple lineages. In addition, male spermatophore production was lost multiple times. Our evolutionary trait analysis revealed significant correlations between increased female neoteny and male accessory gland number, as well as between flightlessness and spermatophore loss. In addition, female flightlessness was positively correlated with the use of glows as female sexual signal. Transition probability analysis supported an evolutionary sequence of female flightlessness evolving first, followed by loss of male spermatophores. These results contribute to understanding how spermatophores have evolved and how this important class of seminal nuptial gifts is linked to other traits, providing new insights into sexual selection and life-history evolution.     

Isolation and identification of the AKH III precursor-related peptide from Locusta migratoria

We have isolated an 8770Da peptide from extracts of corpora cardiaca of adult male and female Locusta migratoria. The N-terminal amino-acid sequence as partially established by Edman degradation is Ala-Leu-Gly-Ala-Pro-Ala-Ala-Gly-Asp. These nine amino acids correspond to the first nine N-terminal amino acids of the adipokinetic hormone precursor-related peptide gamma-chain (APRP-gamma), a peptide that is predicted from the gene encoding the adipokinetic hormone III precursor. The APRP-gamma chain has a monoisotopic mass of 4387Da and contains two cysteine residues. It is known that both AKH I and AKH II precursors occur as dimers. After processing they give rise to the active hormones and three dimeric (two homodimers and one heterodimer) adipokinetic hormone precursor related peptides (APRPs). Based on the mass of 8770Da and the established N-terminal sequence tag, we conclude that the isolated peptide is a homodimer consisting of two APRP-gamma units, covalently linked to each other by two disulphide bounds. In analogy with the previous identified APRPs (APRP-1, APRP-2, and APRP-3), this APRP will be designated as APRP-4.     

Male‐induced costs of mating for females compensated by offspring viability benefits in an insect

Sexual conflict facilitates the evolution of traits that increase the reproductive success of males at the expense of components of female fitness. Theory suggests that indirect benefits are unlikely to offset the direct costs to females from antagonistic male adaptations, but empirical studies examining the net fitness pay‐offs of the interaction between the sexes are scarce. Here, we investigate whether matings with males that invest intrinsically more into accessory gland tissue undermine female lifetime reproductive success (LRS) in the cricket Teleogryllus oceanicus. We found that females incur a longevity cost of mating that is proportional to the partner’s absolute investment into the production of accessory gland products. However, male accessory gland weight positively influences embryo survival, and harmful ejaculate‐induced effects are cancelled out when these are put in the context of female LRS. The direct costs of mating with males that sire offspring with higher viability are thus compensated by direct and possibly indirect genetic benefits in this species.     

Peptide and protein pheromones in amphibians

Purification, characterization and biological activity of urodele and anuran sex-pheromones were reviewed. Female-attracting pheromones obtained from the abdominal gland of Cynops pyrrhogaster and C. ensicauda males are peptides consisting of 10 amino acid residues being designated sodefrin and silefrin, respectively. Each pheromone attracted only conspecific females. Molecular cloning of cDNAs encoding sodefrin and silefrin revealed that both are generated from precursor proteins. Synthesis of these pheromones is regulated by prolactin (PRL) and androgen. Responsiveness of the female vomeronasal epithelium to sodefrin is enhanced by PRL and estrogen. The submandibular gland of the male terrestrial salamander, Plethodon jardani secretes a 22-kD proteinaceous pheromone that enhances female receptivity. It was revealed that every salamander synthesizes multiple isoforms of this pheromone, Plethodontid receptivity factor. The magnificent tree frog, Litoria splendida breed in an aquatic environment. The skin glands of the male secrete a female-attracting peptide pheromone, splendipherin, comprising 25 amino acid residues. The significance of the structure of the amphibian sex-pheromone as peptide and protein is discussed in terms of their species specificity.