Seminal Proteins Research Articles

Correlation of IGF2 levels with sperm quality, inflammation, and DNA damage in infertile patients.

Insulin-like growth factor 2 (IGF2) is a critical endocrine mediator implicated in male reproductive physiology. To investigate the correlation between IGF2 protein levels and various aspects of male infertility, specifically focusing on sperm quality, inflammation, and DNA damage, a cohort of 320 male participants was recruited from the Women's Hospital, Zhejiang University School of Medicine (Hangzhou, China) between 1st January 2024 and 1st March 2024. The relationship between IGF2 protein concentrations and sperm parameters was assessed, and Spearman correlation and linear regression analysis were employed to evaluate the independent associations between IGF2 protein levels and risk factors for infertility. Enzyme-linked immunosorbent assay (ELISA) was used to measure IGF2 protein levels in seminal plasma, alongside markers of inflammation (tumor necrosis factor-alpha [TNF-α] and interleukin-1β [IL-1β]). The relationship between seminal plasma IGF2 protein levels and DNA damage marker phosphorylated histone H2AX (γ-H2AX) was also explored. Our findings reveal that IGF2 protein expression decreased notably in patients with asthenospermia and teratospermia. Correlation analysis revealed nuanced associations between IGF2 protein levels and specific sperm parameters, and low IGF2 protein concentrations correlated with increased inflammation and DNA damage in sperm. The observed correlations between IGF2 protein levels and specific sperm parameters, along with its connection to inflammation and DNA damage, underscore the importance of IGF2 in the broader context of male reproductive health. These findings lay the groundwork for future research and potential therapeutic interventions targeting IGF2-related pathways to enhance male fertility.

Seminal plasma TEX101 protein as a spermatogenesis biomarker in male infertility.

Male infertility may be results from reduced sperm production, or oligozoospermia and azoospermia. Testis-expressed 101 (TEX101) is a glycoprotein that is associated with male fertility, and the disruption of TEX101 results in abnormal semen parameters and sperm function. A case-control study was done to measure seminal plasma TEX101 in 184 volunteers by enzyme-linked immunosorbent assay (ELISA). Significant differences in the mean of TEX101 values were estimated between fertile men (9.64 ng/ml, N= 40), normozoospermic infertile men (8.57 ng/ml, N= 28), and infertile men with oligospermia (5.35 ng/ml, N= 76), and azoospermia (3.19 ng/ml, N= 40). Significant differences between the mean of TEX101 values were estimated in azoospermic infertile men according to the presence of spermatids as no-spermatid (0.66 ng/ml, N=12), few spermatids (3.05 ng/ml, N=16), and moderate spermatids (5.88 ng/ml, N=12). In addition, a significant correlation in oligozoospermia infertile men was found between TEX101 with seminogram. Clinical assay for TEX101 has the potential to diagnose male infertility. And as a biomarker for the seminal fluid quality and as a differential diagnosis of non-obstructive azoospermia.

Male condition and seminal fluid affect female host-marking behavior in the Mexican fruit fly

Mating and the transfer of seminal fluid components including male accessory glands (MAGs) proteins can affect oviposition behavior in insects. After oviposition, some species of fruit flies deposit a host-marking pheromone (HMP) on the fruit that discourages oviposition by other females of the same or different species or genus and reduces competition between larvae. However, we know very little about how mating, receiving seminal fluid, or male condition can affect female host marking behavior. Here, we tested how the physiological state of females (mated or unmated), the receipt of seminal fluid, and the condition of the male (wild or sterile) affect oviposition and host-marking behavior (HMB) in Anastrepha ludens (Diptera: Tephritidae). We also determined the efficiency of the host-marking pheromone from mated or unmated females in deterring oviposition. In a further examination of how seminal fluid may be affecting HMB we assessed if there were differences in the size of wild or sterile MAGs and the protein quantity transferred during mating. Our results indicate that receiving seminal fluid increased egg laying and increased time invested in host-marking (HM). Unmated females laid fewer eggs than mated females but invested the same amount of time in depositing host-marking pheromone, which had similar effectiveness in deterring oviposition as that of mated females. Females that mated with sterile males laid the same number of eggs as females that mated with wild males but spent less time depositing host-marking pheromone, which suggests that females detect the condition of the male and invest less in marking hosts. Finally, sterile males had larger accessory glands and transferred more MAGs proteins during mating compared to wild males. Seminal proteins could be manipulating HM behavior and female investment into their current reproductive effort. We are only beginning to understand how male condition and seminal fluid can affect female physiology and maternal investment in HMP.

The Seminal plasma TEX101 protein as a spermatogenesis biomarker in male infertility.

The Seminal plasma TEX101 protein as a spermatogenesis biomarker in male infertility.

Exploring correlations: Human seminal plasma and blood serum biochemistry in relation to semen quality.

Male infertility is a pressing global issue, prompting the need for biomarkers correlating with seminal parameters for diagnosis. Our study investigated 10 biochemical and energetic parameters in the seminal plasma and blood sera of fertile (25 subjects) and infertile (88 subjects) Polish men, correlations between their levels in seminal plasma and semen quality, and correlations between blood sera and seminal plasma levels of examined parameters. Infertile men displayed elevated seminal plasma glucose and fructose but reduced HDL levels compared to fertile men. We observed also weak negative correlations between seminal plasma triglycerides and sperm concentration in both groups. Moreover, infertile men exhibited positive correlations between seminal plasma HDL/LDL concentrations and sperm concentration. Fertile men showed moderate negative correlations between glucose/triglycerides concentrations and sperm count and between seminal plasma triglycerides levels and sperm vitality. Semen volume correlated with triglycerides (negative) and fructose (positive) concentrations in infertile men. Sperm motility correlated negatively with total cholesterol, LDL, and triglycerides concentrations in fertile men, and weakly with AMP-activated protein kinase in infertile men. Weak negative correlations between seminal plasma fructose/AMP-activated protein kinase concentrations and sperm progressive motility were observed in infertile men, whereas in fertile men seminal plasma AMP-activated protein kinase levels were positively correlated with progressive motility. Correlation analysis between blood serum and seminal plasma parameters revealed intriguing connections, notably regarding LDL, AMP-activated protein kinase, and carnitine, suggesting systemic influences on seminal plasma composition. These findings emphasize the complex interplay between metabolic factors and sperm parameters, offering promising directions for future research in male infertility diagnostics and therapeutics.

Integrative Assessment of Seminal Plasma Biomarkers: A Narrative Review Bridging the Gap between Infertility Research and Clinical Practice.

Infertility represents a significant global health challenge impacting millions of couples worldwide. Approximately half of all infertile couples exhibit compromised semen quality, indicative of diminished male fertility. While the diagnosis of male infertility traditionally relies on semen analysis, its limitations in providing a comprehensive assessment of male reproductive health have spurred efforts to identify novel biomarkers. Seminal plasma, a complex fluid containing proteins, lipids, and metabolites, has emerged as a rich source of such indicators. Reproduction depends heavily on seminal plasma, the primary transporter of chemicals from male reproductive glands. It provides a non-invasive sample for urogenital diagnostics and has demonstrated potential in the identification of biomarkers linked to illnesses of the male reproductive system. The abundance of seminal proteins has enabled a deeper understanding of their biological functions, origins, and differential expression in various conditions associated with male infertility, including azoospermia, asthenozoospermia, oligozoospermia, teratozoospermia, among others. The true prevalence of male infertility is understated due to the limitations of the current diagnostic techniques. This review critically evaluates the current landscape of seminal plasma biomarkers and their utility in assessing male infertility. Βy bridging the gap between research and clinical practice, the integrative assessment of seminal plasma biomarkers offers a multimodal approach to comprehensively evaluate male infertility.

Sperm traits and seminal plasma proteome of locally adapted hairy rams subjected to intermittent scrotal insulation

The present study evaluated the effects of heat stress on reproductive parameters of hairy rams. Six animals were subjected to scrotal insulation during four consecutive nights (6 PM – 6 AM). Day (D) 0 was the first day of insulation. Scrotal circumference increased from 30.5 ± 0.3 cm (at pre-insulation) to 31.8 ± 0.4 cm on D4, decreased 3.9 cm on D28, returning to 30.6 ± 0.6 cm on D57. Sperm concentration decreased from 3.7 ± 0.12 ×109 sperm/mL before insulation to 2.6 ± 0.1 ×109 on D23, returning to normal on D57. Sperm motility averaged 75 ± 2.9% before insulation, was undetectable on D23, and became normal on D77. Sperm with normal morphology reached 5.9 ± 2.6% on D35 but recovered (86.8 ± 2.1%) on D91. Sperm DNA integrity decreased from 86.5 ± 4.7% before insulation to 11.1 ± 3.7% on D63, returning to pre-insulation values on D120. Sperm BSP immunostaining was reduced after scrotal insulation. Variations in seminal protein abundances coincided with changes in sperm parameters. Seminal plasma superoxide dismutase, carboxypeptidase Q-precursor and NPC intracellular cholesterol transporter 2 decreased on D18, returning to normal after D28. Albumin, inhibitor of carbonic anhydrase precursor, EGF-like repeat and discoid I-like domain-containing protein 3 and polymeric immunoglobulin receptor increased after insulation. In summary, intermittent scrotal insulation drastically altered ram sperm attributes and seminal proteins, especially those associated with oxidative stress. Knowledge of animal´s response to thermal stress is vital in the scenario of climate changes.

Regression coefficient of semen characteristics of buffalo bulls on seminal plasma proteins

An experiment was carried out to explore the regression coefficients (RC) of semen characteristics on seminal proteins of buffalo bulls. SDS-PAGE resolved seminal proteins. A life sperm (LS) percentage exhibited a negative and significant RC on PF1 (111.5 ± 18.0 kDa), PF4 (36.13 ± 3.33 kDa), and PF5 (28. 88 ± 3.26 kDa) proteins, namely -0.13, -0.63 and -0.69 % / kDa respectively. A sperm acrosome integrity (SAI) percentage exhibited a pronounced negative RC on PF1 and PF2 (87.63 ± 16.5 kDa), -0.13 and -0.14 % / kDa, respectively. A negative RC was noticed in SAI percentage on PF4 (-0.61 % / kDa) and PF5 (-0.60 % / kDa) proteins. A pronounced positive RC was shown for total sperm abnormalities (TSA) on PF1 proteins (0.02 % / kDa). In conclusion, some semen attributes had a negative RC on some seminal proteins. In conclusion, some semen attributes had a negative RC on seminal proteins. These provide us with a good tool for early predicting the buffalo bull’s fertility to reduce the economic losses of male infertility and enhance the developmental sustainability of buffalo production in Iraq.

Impact of Escherichia coli, Candida non-albicans, and Trichomonas vaginalis on Semen Chemical and Functional Parameters: an In-Vitro Study.

Infertility is a worldwide medical issue in which infection is recognized to play a major role. Pathogens trigger various mechanisms that impact fertility, either directly by affecting the physiological indices of semen or indirectly by disrupting the process of spermatogenesis. In the current work, the effect of in-vitro cultivation of Escherichia coli (E. coli), Candida non-albicans (C. non-albicans), and Trichomonas vaginalis (T. vaginalis) (as the most frequently reported sexually transmitted infections) was assessed on the physiological functions of the spermatozoa and the chemical characteristics of the seminal fluid. The semen samples were exposed to cultures of E. coli, C. non-albicans, and T. vaginalis. The study analyzed the changes in motility, agglutination, viability, DNA fragmentation index (DFI%), seminal pH, and biochemical parameters at 1/2, 1, 1.5, 2, 2.5, 3.5 and 4 hours. Incubation of the semen samples with E. coli resulted in a progressive increase in agglutination, pH, and nitrite. The seminal glucose and the sperm motility, on the other hand, were reduced. The sperm vitality and seminal protein remained unaffected. C. non-albicans induced three forms of agglutination (head-to-head, tail-to-tail, and head-to-tail), lowered pH values and decreased the sperm motility, but did not alter the seminal protein, glucose, nitrite, nor the spermatozoa viability at the different tested time intervals. T. vaginalis resulted in increased seminal protein, and reduced glucose, pH, and motility. It also induced minimal agglutination and caused unchanged nitrite and sperm viability. The DFI% was increased in all pathogens with the C. non-albicans showing the highest DNA fragmentation index. Urogenital infection with E. coli, C. non-albicans, or T. vaginalis is assumed to affect the quality of semen through DNA fragmentation, agglutination and altered seminal chemical microenvironment.

Protein factors of capacitation and decapacitation in canine seminal plasma

The aim of the present study was to determine the proteins in canine seminal plasma with direct effect on specific sperm parameters during fertilisation. The influence of seminal plasma proteins was focused on three processes: capacitation, hyperactivation and decapacitation. Size exclusion chromatographic fractional separation of proteins from seminal plasma based on their molecular weights was performed. In addition, two-dimensional electrophoresis of two seminal protein fractions was done. The effect of protein molecules on the motion and kinetic parameters of the male gametes in in vitro conditions was monitored by computer-assisted sperm analysis. The activity of alkaline phosphatase, creatine kinase and alanine aminotransferase in whole seminal plasma and each chromatography fraction was measured spectrophotometrically using the BA-88A semi-automatic chemistry analyzer. The protein fractions with different molecular weights affected the in vitro motility and kinetic characteristics (curvilinear velocity, straightness, linearity and amplitude of lateral head displacement) of spermatozoa, leading to hyperactivation or initiating decapacitation kinetics changes. The detailed study of the seminal plasma proteome would add fundamental information about the processes associated with physiological changes occurring in spermatozoa before fertilisation. The study of the canine seminal plasma proteome could add relevant information about its effects on the fertilising ability of the male gametes and the changes occurring in them before fertilisation.

Seminal Vesicle-Derived Exosomes for the Regulation of Sperm Activity.

The seminal vesicle contributes to a large extent of the semen volume and composition. Removal of seminal vesicle or lack of seminal vesicle proteins leads to decreased fertility. Seminal plasma proteome revealed that seminal fluid contained a wide diversity of proteins. Many of them are known to modulate sperm capacitation and serve as capacitation inhibitors or decapacitation factors. Despite identifying secretory vesicles from the male reproductive tract, such as epididymosomes or prostasomes, isolation, identification, and characterization of seminal vesicle-derived exosomes are still unknown. This chapter aims to review the current understanding of the function of seminal vesicles on sperm physiology and male reproduction and provide ultracentrifugation-based isolation protocols for the isolation of seminal vesicle exosomes. Moreover, via proteomic analysis and functional categorization, a total of 726 proteins IDs were identified in the purified seminal vesicle exosomes fraction. Preliminary data showed seminal vesicle-derived exosomes inhibited sperm capacitation; however, more studies will be needed to reveal other functional involvements of seminal vesicle-derived exosomes on the sperm physiology and, more importantly, how these exosomes interact with sperm membrane to achieve their biological effects.

The seminal odorant binding protein Obp56g is required for mating plug formation and male fertility in Drosophila melanogaster.

In Drosophila melanogaster and other insects, the seminal fluid proteins (SFPs) and male sex pheromones that enter the female with sperm during mating are essential for fertility and induce profound post-mating effects on female physiology. The SFPs in D. melanogaster and other taxa include several members of the large gene family known as odorant binding proteins (Obps). Work in Drosophila has shown that some Obp genes are highly expressed in the antennae and can mediate behavioral responses to odorants, potentially by binding and carrying these molecules to odorant receptors. These observations have led to the hypothesis that the seminal Obps might act as molecular carriers for pheromones or other compounds important for male fertility, though functional evidence in any species is lacking. Here, we used functional genetics to test the role of the seven seminal Obps in D. melanogaster fertility and the post-mating response (PMR). We found that Obp56g is required for male fertility and the induction of the PMR, whereas the other six genes are dispensable. We found males lacking Obp56g fail to form a mating plug in the mated female's reproductive tract, leading to ejaculate loss and reduced sperm storage, likely due to its expression in the male ejaculatory bulb. We also examined the evolutionary history of these seminal Obp genes, as several studies have documented rapid evolution and turnover of SFP genes across taxa. We found extensive lability in gene copy number and evidence of positive selection acting on two genes, Obp22a and Obp51a. Comparative RNAseq data from the male reproductive tract of multiple Drosophila species revealed that Obp56g shows high male reproductive tract expression in a subset of taxa, though conserved head expression across the phylogeny. Together, these functional and expression data suggest that Obp56g may have been co-opted for a reproductive function over evolutionary time.

Protein Profiles in Seminal Plasma of Iraqi Buffalo Bulls (Bubalus bubalis) Associated with Fresh and Cryopreserved Semen Quality

This study was undertaken to identify some protein profiles in the seminal plasma of Iraqi buffalo bulls and their correlation to the quality of fresh and cryopreserved semen. Semen was collected from eight buffalo bulls and divided according to the percentage of sperm individual motility into two groups. The first group (n=3) included good semen quality, while the second group (n=5) included poor semen quality. Seminal plasma was extracted from each semen sample by centrifugation and seminal proteins were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Nine types of protein bands were observed in the seminal plasma of the buffalo bulls belonging to good semen quality, ranging from 10-68 kDa. The most abundant proteins in the overall presence of proteins in seminal plasma were 10 (100%), 14 (100%), 20 (100%), 26 (100%), 34 (100%), and 43 (37.5%) kDa. On the other hand, 14 types of protein bands resolved for the poor-quality semen, ranging from 10-155 kDa. The most abundant proteins in the overall presence of proteins in seminal plasma were 10 (100%), 14 (100%), 20 (100%), 26 (100%), 34 (87.5%), 130 (50%) and 155 (50%) kDa. A significant negative correlation was noticed among proteins with molecular weights of 28. 88 ± 3.26, 22.50 ± 2.85, and 12.00 ± 1.15 kDa, and the percentage of sperm individual motility and plasma membrane integrity. Moreover, there was a positive significant correlation between proteins whose molecular weight 22.50 ± 2.85 kDa and the percentages of total abnormalities and normal sperms. In conclusion, the identification of seminal proteins may be a useful tool in the future evaluation of spermatozoa and the prediction of fertility in Iraqi buffalo bulls.

Cinnamon mediated- zinc oxide nanoparticles and its cryogenic effect on SARS-CoV-2 recovered HTPI patients – An in vitro cum pilot study

Infertility affects more than 40–50% of couples, with men accounting for 20–30% of the problem. Spermatogenesis fails due to poor sperm quality. Although external factors of smoking, alcohol, heat, and metal exposure cause testicular damage, causes infertility than genetic factors. However, after infection with COVID-19, the SARS-CoV-2 virus enters the blood-testis barrier via ACE2 receptors influenced hypertension and disrupts spermatogenesis. Meanwhile, preserving sperm cells during treatment or medication and the associated freeze/thaw is difficult. As a result, the current pilot study focuses on maintaining hypertension-induced infertile subjects' sperm cells by cinnamon extender and its ameliorative effect on sperm viability (SARS-CoV-2 recovered patients after six months were identified and selected). The semen was collected with proper institutional permission from the 20–45 age group with infertility (recently recovered from COVID-19) and processed for major conventional semen parameters as per WHO, 2020. The informed consent form was obtained and kept confidential. Cinnamon NPs were synthesized, characterized, and processed for sperm preservatives at specific dosages (15, 25, and 50 ppm) and time intervals, followed by biochemical and viability analysis. Because the last two years of COVID-19 have had an impact on their lifestyle, the semen parameters (count, morphology, and motility) and biochemical parameters (Ca, Na, K, Se, Mg, and total seminal proteins) confirm that they are infertile due to high blood pressure. Cinnamon-ZnO NPs treated sperm cells, and their viability indicates that improved viability of infertile sperm cells was comparable to fertile and that further damage from infertility was avoided noticeably. Cinnamon is high in zinc and has antioxidant properties; it can be used as a cryopreservative.

Non-Invasive Diagnostics of Male Spermatogenesis from Seminal Plasma: Seminal Proteins.

The compounds of seminal plasma have great potential as biomarkers of male fertility and can be used as a diagnostic tool for types of azoospermia. Azoospermia occurs in approximately 1% of the male population, and for an effective therapy of this form of male infertility, it is important to distinguish between obstructive and non-obstructive azoospermia. Proteins in seminal plasma can serve as biomarkers for diagnosing azoospermia. Considering the various types of obstructions, a combination of multiple proteins is advisable for diagnostic purposes. In this context, testicular and epididymal proteins are particularly significant, as they are specific to these tissues and typically absent in ejaculate during most obstructions. A combination of multiple biomarkers is more effective than the analysis of a single protein. This group of markers contains TEX101 and ECM1 proteins, combined detections of these two bring a diagnostic output with a high sensitivity and specificity. Similar results were observed for combined detection of TEX101 and SPAG1. The effective using of specific biomarkers from seminal plasma can significantly improve the existing approaches to diagnosis of the causes of male infertility.

Cryptic male mate choice for high-quality females reduces male postcopulatory success in future matings.

Cryptic male mate choice occurs when males differentially allocate resources to females during or after copulation. When male resources are limited, males may benefit by strategically allocating more resources toward higher-quality females. In the fruit fly, Drosophila melanogaster, males mate for longer and may transfer more sperm and more seminal proteins when they mate with larger females compared with smaller females. It is unclear, however, whether this increased investment in large females has any impact on the males' later matings. We mated D. melanogaster males sequentially to females of large or small body size in all possible combinations to test whether cryptic male mate choice for large females is costly to the males' subsequent matings. Second matings were shorter for males compared with their first matings, but there were no differences in fecundity between females mated first or second by a male. Interestingly, male success at defensive sperm competition declined between his first and second matings only when his first mating had been with a large female. This suggests that the higher initial investment in large females reduced male postcopulatory success in their subsequent matings. Cryptic male mate choice may carry underappreciated costs to males that could limit their reproductive potential.

Supplementation of Schisandrin B in Semen Extender Improves Quality and Oxidation Resistance of Boar Spermatozoa Stored at 4 °C.

During cold storage, boar spermatozoa undergo oxidative stress, which can impair sperm function and fertilizing capacity. The objective of the present study was to assess the effects of Schisandrin B (Sch B) in semen extenders on the quality of boar semen stored at hypothermia. Semen was collected from twelve Duroc boars and diluted in extenders supplemented with different concentrations of Sch B (0 μmol/L, 2.5 μmol/L, 5 μmol/L, 10 μmol/L, 20 μmol/L, and 40 μmol/L). Here, we demonstrated that 10 μmol/L Sch B provided the best effects on motility, plasma membrane integrity, acrosome integrity, sperm normality rate, average movement velocity, wobbility, mitochondrial membrane potential (MMP), and DNA integrity of sperm. The results of Sch B effects on antioxidant factors in boar sperm showed that Sch B significantly elevated the total antioxidant capacity (T-AOC) and markedly decreased the reactive oxygen species (ROS) and malondialdehyde (MDA) content of sperm. The expression of catalase (CAT) and superoxide dismutase (SOD) mRNA was increased, while the expression of glutathione peroxidase (GPx) mRNA demonstrated no change compared to non-treated boar sperm. Compared to the non-treated group, Sch B triggered a decrease in Ca2+/protein kinase A (PKA) and lactic acid content in boar sperm. Similarly, Sch B led to a statistically higher quantitative expression of AWN mRNA and a lower quantitative expression of porcine seminal protein I (PSP-I) and porcine seminal protein II (PSP-II) mRNA. In a further reverse validation test, no significant difference was observed in any of the parameters, including adhesion protein mRNA, calcium content, lactic acid content, PKA, and protein kinase G (PKG) activity after sperm capacitation. In conclusion, the current study indicates the efficient use of Sch B with a 10 μmol/L concentration in the treatment of boar sperm through its anti-apoptosis, antioxidative, and decapacitative mechanisms, suggesting that Sch B is a novel candidate for improving antioxidation and decapacitation factors in sperm in liquid at 4 °C.

Probing the chemical unfolding and phospholipid binding to the major protein of donkey seminal plasma, DSP-1 by fluorescence spectroscopy

Fibronectin type-II (FnII) proteins which constitute the major fraction in the seminal plasma of many mammals, bind to choline phospholipids on the spermatozoa and play a crucial role in sperm capacitation, which enables the sperm to fertilize the egg. In the current study, we have investigated the heterogeneity of microenvironment around the tryptophan residues in the major FnII protein of donkey seminal plasma, DSP-1, in the native state and upon ligand binding employing fluorescence methods. Steady-state and time-resolved fluorescence studies on the quenching of the protein intrinsic fluorescence employing neutral and ionic quenchers revealed that the environment of the tryptophan residues in DSP-1 is less heterogeneous as compared to other homologous seminal plasma FnII proteins PDC-109 (bovine) and HSP-1/2 (equine). The quenching was decreased by ligand binding with choline containing lipids, Lyso-PC and DMPC providing stronger shielding of the Trp residues than the soluble ligand, phosphorylcholine, which is most likely due to segment(s) of the protein penetrating into the hydrophobic interior of the lipid membrane/micelles. Studies on the chaotrope-induced unfolding of DSP-1 revealed that disulfide bonds in the FnII domains of the protein prevent its complete unfolding, and that cooperativity of unfolding is also modulated by polydispersity of the protein.

Female Fly Postmating Behaviors.

Upon copulation, females undergo a switch-like change in their behavior and physiology, known as "postmating responses." These strong behavioral and physiological changes are triggered by the transfer of male seminal proteins during copulation. Postmating response is associated with strong reduction in receptivity, indicated by the females kicking their legs toward the suitor and curving their abdomen downward to hide their genitalia from them and extruding their ovipositor at the tip of the abdomen, which physically prevents copulation. The transfer of male-specific pheromones, such as 11-cis-vaccenyl-acetate, during copulation further reduces female attractiveness. In addition, mated females exhibit increased ovulation, egg-laying behavior, enhanced feeding behavior, and changes in food preference. However, females increase their rate of remating when they are in social groups or in the presence of food. This protocol describes methods for measuring female postmating behaviors, such as oviposition, female sexual receptivity, and mating plug ejection.

Drosophila Arc1 is not required for male fertility or sperm competition success.

Activity-regulated cytoskeleton associated protein (Arc1), which is required for synaptic plasticity and metabolism in Drosophila , self-assembles into capsid-like structures that transport mRNAs in extracellular vesicles. In addition to expression in the brain and nervous system, Arc1 is expressed in the male accessory glands, an endothelial tissue that produces male seminal proteins and exosomes that impact male fertility. We thus hypothesized that Arc1 might impact male fertility. We measured the fertility, mating latency, mating duration, and sperm competition performance of Arc1 males relative to controls and found no evidence that Arc1 is required for any of these measures of male fertility.