Sex Peptide Research Articles

Mated Drosophila melanogaster females consume more amino acids during the dark phase.

To maintain homeostasis, animals must ingest appropriate quantities, determined by their internal nutritional state, of suitable nutrients. In the fruit fly Drosophila melanogaster, an amino acid deficit induces a specific appetite for amino acids and thus results in their increased consumption. Although multiple processes of physiology, metabolism, and behavior are under circadian control in many organisms, it is unclear whether the circadian clock also modulates such motivated behavior driven by an internal need. Differences in levels of amino acid consumption by flies between the light and dark phases of the day:night cycle were examined using a capillary feeder assay following amino acid deprivation. Female flies exhibited increased consumption of amino acids during the dark phase compared with the light phase. Investigation of mutants lacking a functional period gene (per0), a well-characterized clock gene in Drosophila, found no difference between the light and dark phases in amino acid consumption by per0 flies. Furthermore, increased consumption of amino acids during the dark phase was observed in mated but not in virgin females, which strongly suggested that mating is involved in the rhythmic modulation of amino acid intake. Egg production, which is induced by mating, did not affect the rhythmic change in amino acid consumption, although egg-laying behavior showed a per0-dependent change in rhythm. Elevated consumption of amino acids during the dark phase was partly induced by the action of a seminal protein, sex peptide (SP), on the sex peptide receptor (SPR) in females. Moreover, we showed that the increased consumption of amino acids during the dark phase is induced in mated females independently of their internal level of amino acids. These results suggest that a post-mating SP/SPR signal elevates amino acid consumption during the dark phase via the circadian clock.

Juvenile Hormone Suppresses Resistance to Infection in Mated Female Drosophila melanogaster

Hormonal signaling provides metazoans with the ability to regulate development, growth, metabolism, immune defense, and reproduction in response to internal and external stimuli. The use of hormones as central regulators of physiology makes them prime candidates for mediating allocation of resources to competing biological functions (i.e., hormonal pleiotropy) [1]. In animals, reproductive effort often results in weaker immune responses (e.g., [2-4]), and this reduction is sometimes linked to hormone signaling (see [5-7]). In the fruit fly, Drosophila melanogaster, mating and the receipt of male seminal fluid proteins results in reduced resistance to a systemic bacterial infection [8, 9]. Here, we evaluate whether the immunosuppressive effect of reproduction in female D.melanogaster is attributable to the endocrine signal juvenile hormone (JH), which promotes the development of oocytes and the synthesis and deposition of yolk protein [10, 11]. Previous work has implicated JH as immunosuppressive [12, 13], and the male seminal fluid protein Sex Peptide (SP) activates JH biosynthesis in female D.melanogaster after mating [14]. We find that transfer of SP activates synthesis of JH in the mated female, which in turn suppresses resistance to infection through the receptor germ cell expressed (gce). We find that mated females are more likely to die from infection, suffer higher pathogen burdens, and are less able to induce their immune responses. All of these deficiencies are rescued when JH signaling is blocked. We argue that hormonal signaling is important for regulating immune system activity and, more generally, for governing trade-offs between physiological processes.

Abstract TP200: Urinary Albumin/creatinine Ratio Should Be Associated With White Matter Lesion Severity in First-ever Stroke Patients

Background and purpose: White matter lesion (WML) is an indicator of small vessel disease, however, the underlying pathological mechanisms has not been fully understood. In recent years, experimental and epidemiological studies have suggested that chronic kidney disease (CKD) is associated with endothelial dysfunction; thereby, a CKD state may initiate small vessel damage. Our aim was to investigate the association of estimated glomerular filtration rate (eGFR), urinary albumin/creatinine ratio (UACR), and WML in first-ever stroke patients. Methods: We retrospectively enrolled 284 consecutive patients (177 male; median age 72 years) admitted to our stroke center between May 2010 and January 2012. eGFR and UACR measurements were performed on admission. WML were assessed using the Fazekas classification. Severe WML was defined as Fazekas gradings of 2 or higher. The impact of the eGFR and UACR on WML was evaluated using multiple logistic regression analysis. Separate analyses were conducted according to severe WML and trichotomized eGFR level [60 mL/min ≤ eGFR (reference), 45 mL/min ≤ eGFR < 60 mL/min, and eGFR < 45 mL/min)] and UACR level [UACR < 30.0 mg/g creatinine (reference), 30.0 mg/g creatinine ≤ UACR < 300 mg/g creatinine, and 300 mg/g creatinine ≤ UACR]. Results: According to the Fazekas gradings, 91 patients (32.0%) had scale 0; 90 patients (31.7%), scale 1; 59 patients (20.8%), stage 2; and 44 patients (15.5%), scale 3. Age ( P < 0.0001), sex ( P = 0.0094), eGFR ( P = 0.0173), UACR ( P = 0.0001), hypertension ( P = 0.0436), and brain natriuretic peptide ( P = 0.0354) were significantly associated with severe WML. On multivariable logistic regression analysis, high UACR (≥ 39.6 mg/g creatinine), but not low eGFR (≤ 74 mL/min/1.73 m 2 ), was independently associated with severe WML. In comparisons between trichotomized UACR level, severe WML were more frequent in UACR ≥ 300 mg/g creatinine group than in UACR < 30.0 mg/g creatinine group after multivariate adjustment (OR, 2.25; 95% CI, 1.04-5.00; P = 0.039). On the other hand, there was no significant association with trichotomized eGFR level and severe WML (OR, 1.51; 95% CI, 0.62-3.77; P = 0.3672). Conclusions: Our data suggest that a high UACR, but not eGFR, is independently associated with severe WML.

Urinary albumin-to-creatinine ratio is associated with white matter lesions severity in first-ever stroke patients

BackgroundThe presence of white matter lesions (WML) is an indicator of small vessel disease; however, the underlying pathological mechanisms are still unclear. We aimed to investigate the association of estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (UACR) with WML severity in first-ever stroke patients. MethodsWe retrospectively enrolled 284 consecutive patients (177 male; median age 72years) admitted to our stroke center between May 2010 and January 2012. eGFR and UACR measurements were performed on admission. WML severity was assessed using the Fazekas classification. Severe WML was defined as a Fazekas grade of 2 or higher. The impact of eGFR and UACR on severe WML was evaluated using multiple logistic regression analysis. ResultsAge (P<0.0001), sex (P=0.0094), eGFR (P=0.0173), UACR (P=0.0001), hypertension (P=0.0436), and brain natriuretic peptide (P=0.0354) were significantly associated with severe WML. On multivariable logistic regression analysis, high UACR (≥39.6mg/g creatinine, P=0.039), but not low eGFR (≤74ml/min/1.73m2, P=0.3672), was independently associated with severe WML. Comparisons between the UACR levels showed that severe WML was more frequent in the UACR ≥300mg/g creatinine group than in the UACR <30.0mg/g creatinine group after multivariate adjustment (OR, 2.25; 95% CI, 1.04–5.00; P=0.039). However, there was no significant association between eGFR and severe WML. ConclusionsOur data suggest that high UACR, but not eGFR, is independently associated with severe WML.

Inflammatory Biomarkers Predict Heart Failure Severity and Prognosis in Patients With Heart Failure With Preserved Ejection Fraction

Background— Underlying mechanisms in heart failure (HF) with preserved ejection fraction remain unknown. We investigated cardiovascular plasma biomarkers in HF with preserved ejection fraction and their correlation to diastolic dysfunction, functional class, pathophysiological processes, and prognosis. Methods and Results— In 86 stable patients with HF and EF ≥45% in the Karolinska Rennes (KaRen) biomarker substudy, biomarkers were quantified by a multiplex immunoassay. Orthogonal projection to latent structures by partial least square analysis was performed on 87 biomarkers and 240 clinical variables, ranking biomarkers associated with New York Heart Association (NYHA) Functional class and the composite outcome (all-cause mortality and HF hospitalization). Biomarkers significantly correlated with outcome were analyzed by multivariable Cox regression and correlations with echocardiographic measurements performed. The orthogonal partial least square outcome-predicting biomarker pattern was run against the Ingenuity Pathway Analysis (IPA) database, containing annotated data from the public domain. The orthogonal partial least square analyses identified 32 biomarkers correlated with NYHA class and 28 predicting outcomes. Among outcome-predicting biomarkers, growth/differentiation factor-15 was the strongest and an additional 7 were also significant in Cox regression analyses when adjusted for age, sex, and N-terminal probrain natriuretic peptide: adrenomedullin (hazard ratio per log increase 2.53), agouti-related protein; (1.48), chitinase-3–like protein 1 (1.35), C–C motif chemokine 20 (1.35), fatty acid–binding protein (1.33), tumor necrosis factor receptor 1 (2.29), and TNF-related apoptosis-inducing ligand (0.34). Twenty-three of them correlated with diastolic dysfunction (E/e′) and 5 with left atrial volume index. The IPA suggested that increased inflammation, immune activation with decreased necrosis and apoptosis preceded poor outcome. Conclusions— In HF with preserved ejection fraction, novel biomarkers of inflammation predict HF severity and prognosis that may complement or even outperform traditional markers, such as N-terminal probrain natriuretic peptide. These findings lend support to a hypothesis implicating global systemic inflammation in HF with preserved ejection fraction. Clinical Trial Registration— URL: http://www.clinicaltrials.gov ; Unique identifier: NCT00774709.

Reproduction regulates Drosophila nutrient intake through independent effects of egg production and sex peptide: Implications for aging.

BACKGROUND: The ratio of protein to carbohydrate (P:C) consumed influences reproduction and lifespan, outcomes that are often maximized by different P:C intake.OBJECTIVE: Determine if reproduction in female Drosophila drives elevated P:C intake. Distinguish whether such a preference is driven by egg production or from male-derived sex peptides in seminal fluid.METHODS: Intake of protein and carbohydrate was measured in a diet-choice assay. Macronutrient intake was calculated for mated and unmated fertile females, mated and unmated sterile females, and both types of female when mated to wildtype males and to males lacking sex peptide.RESULTS: Mated females have high P:C intake relative to unmated females and mated, sterile females. Fertile females mated to wildtype males and to males lacking sex peptide have high P:C intake, but sterile females have similar, low P:C intake when unmated and when mated to males lacking sex peptide.CONCLUSIONS: The metabolic demands of egg production and sex peptides are individually sufficient to drive elevated P:C intake in adult female Drosophila. Reproductive state can thus modulate how animals consume macronutrients, which in turn can impact their health and aging.

Changes in Female Drosophila Sleep following Mating Are Mediated by SPSN-SAG Neurons.

Female Drosophila melanogaster, like many other organisms, exhibit different behavioral repertoires after mating with a male. These postmating responses (PMRs) include increased egg production and laying, increased rejection behavior (avoiding further male advances), decreased longevity, altered gustation and decreased sleep. Sex Peptide (SP), a protein transferred from the male during copulation, is largely responsible for many of these behavioral responses, and acts through a specific circuit to induce rejection behavior and alter dietary preference. However, less is known about the mechanisms and neurons that influence sleep in mated females. In this study, we investigated postmating changes in female sleep across strains and ages and on different media, and report that these changes are robust and relatively consistent under a variety of conditions. We find that female sleep is reduced by male-derived SP acting through the canonical sex peptide receptor (SPR) within the same neurons responsible for altering other PMRs. This circuit includes the SPSN-SAG neurons, whose silencing by DREADD induces postmating behaviors including sleep. Our data are consistent with the idea that mating status is communicated to the central brain through a common circuit that diverges in higher brain centers to modify a collection of postmating sensorimotor processes.

A Pair of Oviduct-Born Pickpocket Neurons Important for Egg-Laying in Drosophila melanogaster.

During copulation, male Drosophila transfers Sex Peptide (SP) to females where it acts on internal sensory neurons expressing pickpocket (ppk). These neurons induce a post-mating response (PMR) that includes elevated egg-laying and refractoriness to re-mating. Exactly how ppk neurons regulate the different aspects of the PMR, however, remains unclear. Here, we identify a small subset of the ppk neurons which requires expression of a pre-mRNA splicing factor CG3542 for egg-laying, but not refractoriness to mating. We identify two CG3542-ppk expressing neurons that innervate the upper oviduct and appear to be responsible for normal egg-laying. Our results suggest specific subsets of the ppk neurons are responsible for each PMR component.

Left ventricular diastolic dysfunction and increased left ventricular mass index related to pulmonary hypertension in patients with systemic autoimmune disease without pericardial effusion

PurposeWe investigated the relationship of left ventricular (LV) diastolic dysfunction and LV mass index (LVMI) against pulmonary hypertension (PH) in systemic autoimmune disease (SAD). MethodsA total of 84 SAD patients (68 females; 53±17years; systemic lupus erythematosus, 27%; scleroderma, 17%; vasculitis, 16%; mixed connective tissue disease, 13% and polymyositis/dermatomyositis complex, 10%) without significant pericardial effusion (PE) on TTE (Vivid E9, GE) were analyzed. On TTE, PH was defined as peak tricuspid regurgitation velocity (TRV) of ≥2.9m/s based upon 2015 ESC guideline. Left atrial volume index (LAVI) and E/E′ were measured as indicators of LV diastolic dysfunction. LVMI was also measured. ResultsSeven patients (8%) had PH. PH patients had greater LAVI (p<0.001), E/E′ (p=0.004), LVMI (p=0.009) than non-PH patients. LAVI (R=0.458), E/E′ (R=0.337), and LVMI (R=0.313) significantly and positively correlated with TRV (all p<0.05). Multiple regression analysis was performed to explore determinants of TRV. Age, female sex, and brain natriuretic peptide (BNP) were included in all the models. Three multiple regression models were generated using 1) LAVI, 2) E/E′, and 3) LVMI and included LAVI, E/E′, LVMI, and BNP as significant variables influencing TRV. Multi logistic regression analysis for predicting TRV of ≥2.9m/s showed that LAVI, and E/E′ were significant predictors (Odds ratio, 1.296, and 1.370, respectively). ConclusionIn SAD patients without PE, LV diastolic dysfunction and increment of LVMI was closely associated with PH based upon TRV. LAVI and E/E′ were independent predictors for PH. Measuring LAVI and E/E′ may be a key to determine the mechanism of PH in these patients.

Experimental evolution under hyper-promiscuity in Drosophila melanogaster.

BackgroundThe number of partners that individuals mate with over their lifetime is a defining feature of mating systems, and variation in mate number is thought to be a major driver of sexual evolution. Although previous research has investigated the evolutionary consequences of reductions in the number of mates, we know little about the costs and benefits of increased numbers of mates. Here, we use a genetic manipulation of mating frequency in Drosophila melanogaster to create a novel, highly promiscuous mating system. We generated D. melanogaster populations in which flies were deficient for the sex peptide receptor (SPR) gene – resulting in SPR- females that mated more frequently – and genetically-matched control populations, and allowed them to evolve for 55 generations. At several time-points during this experimental evolution, we assayed behavioural, morphological and transcriptional reproductive phenotypes expected to evolve in response to increased population mating frequencies.ResultsWe found that males from the high mating frequency SPR- populations evolved decreased ability to inhibit the receptivity of their mates and decreased copulation duration, in line with predictions of decreased per-mating investment with increased sperm competition. Unexpectedly, SPR- population males also evolved weakly increased sex peptide (SP) gene expression. Males from SPR- populations initially (i.e., before experimental evolution) exhibited more frequent courtship and faster time until mating relative to controls, but over evolutionary time these differences diminished or reversed.ConclusionsIn response to experimentally increased mating frequency, SPR- males evolved behavioural responses consistent with decreased male post-copulatory investment at each mating and decreased overall pre-copulatory performance. The trend towards increased SP gene expression might plausibly relate to functional differences in the two domains of the SP protein. Our study highlights the utility of genetic manipulations of animal social and sexual environments coupled with experimental evolution.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0699-8) contains supplementary material, which is available to authorized users.

Mating-Induced Increase in Germline Stem Cells via the Neuroendocrine System in Female Drosophila.

Mating and gametogenesis are two essential components of animal reproduction. Gametogenesis must be modulated by the need for gametes, yet little is known of how mating, a process that utilizes gametes, may modulate the process of gametogenesis. Here, we report that mating stimulates female germline stem cell (GSC) proliferation in Drosophila melanogaster. Mating-induced increase in GSC number is not simply owing to the indirect effect of emission of stored eggs, but rather is stimulated by a male-derived Sex Peptide (SP) and its receptor SPR, the components of a canonical neuronal pathway that induces a post-mating behavioral switch in females. We show that ecdysteroid, the major insect steroid hormone, regulates mating-induced GSC proliferation independently of insulin signaling. Ovarian ecdysteroid level increases after mating and transmits its signal directly through the ecdysone receptor expressed in the ovarian niche to increase the number of GSCs. Impairment of ovarian ecdysteroid biosynthesis disrupts mating-induced increase in GSCs as well as egg production. Importantly, feeding of ecdysteroid rescues the decrease in GSC number caused by impairment of neuronal SP signaling. Our study illustrates how female GSC activity is coordinately regulated by the neuroendocrine system to sustain reproductive success in response to mating.

Neuropeptides Modulate Female Chemosensory Processing upon Mating in Drosophila.

A female’s reproductive state influences her perception of odors and tastes along with her changed behavioral state and physiological needs. The mechanism that modulates chemosensory processing, however, remains largely elusive. Using Drosophila, we have identified a behavioral, neuronal, and genetic mechanism that adapts the senses of smell and taste, the major modalities for food quality perception, to the physiological needs of a gravid female. Pungent smelling polyamines, such as putrescine and spermidine, are essential for cell proliferation, reproduction, and embryonic development in all animals. A polyamine-rich diet increases reproductive success in many species, including flies. Using a combination of behavioral analysis and in vivo physiology, we show that polyamine attraction is modulated in gravid females through a G-protein coupled receptor, the sex peptide receptor (SPR), and its neuropeptide ligands, MIPs (myoinhibitory peptides), which act directly in the polyamine-detecting olfactory and taste neurons. This modulation is triggered by an increase of SPR expression in chemosensory neurons, which is sufficient to convert virgin to mated female olfactory choice behavior. Together, our data show that neuropeptide-mediated modulation of peripheral chemosensory neurons increases a gravid female’s preference for important nutrients, thereby ensuring optimal conditions for her growing progeny.

Homology modeling and molecular docking studies of Drosophila and Aedes sex peptide receptors

The Drosophila melanogaster sex peptide receptor (DrmSPR), which is a G protein-coupled receptor (GPCR), is known as the specific receptor for sex peptide (SP). It is responsible for the reproductive behavior in the Drosophila model system; in particular, it is involved in the post-mating responses such as the increase in egg-laying ability and decrease in receptivity in females. In a previous study, we discovered a small molecule agonist of DrmSPR for the first time, which could not, however, activate Aedes aegypti SPR (AedesSPR). To investigate the binding mechanism of the small molecule agonist of DrmSPR, the ensemble structures of low-lying packing structures of DrmSPR and AedesSPR were assembled using the GEnSeMBLE (GPCR Ensemble of Structures in Membrane BiLayer Environment) method. The generated homology models exhibited the typical pattern of inter-helical interactions of the class A GPCRs. The docking experiments of the small molecule agonist suggest that Tyr5.35 and Phe2.67 residues may be involved in a hydrophobic interaction and that Ser3.25 forms a hydrogen bond with the agonist. Additionally, we found that the docking results were consistent with the experimental data of the reference compounds with variable agonistic activities. Moreover, a potential distinction of the putative binding sites in two GPCR models of DrmSPR and AedesSPR, which was determined in this study, can explain the selective action of the agonist for DrmSPR but not for AedesSPR.

Newly identified allatostatin Bs and their receptor in the two-spotted cricket, Gryllus bimaculatus

A cDNA encoding allatostatin Bs (ASTBs) containing the W(X)6W motif was identified using a database generated by a next generation sequencer (NGS) in the two-spotted cricket, Gryllus bimaculatus. The contig sequence revealed the presence of five novel putative ASTBs (GbASTBs) in addition to GbASTBs previously identified in G. bimaculatus. MALDI-TOF MS analyses revealed the presence of these novel and previously identified GbASTBs with three missing GbASTBs. We also identified a cDNA encoding G. bimaculatus GbASTB receptor (GbASTBR) in the NGS data. Phylogenetic analysis demonstrated that this receptor was highly conserved with other insect ASTBRs, including the sex peptide receptor of Drosophila melanogaster. Calcium imaging analyses indicated that the GbASTBR heterologously expressed in HEK293 cells exhibited responses to all identified GbASTBs at a concentration range of 10−10–10−5M.

Identification of a Peptidergic Pathway Critical to Satiety Responses in Drosophila

Although several neural pathways have been implicated in feeding behaviors in mammals [1-7], it remains unclear how the brain coordinates feeding motivations to maintain a constant body weight (BW). Here, we identified a neuropeptide pathway important for the satiety and BW control in Drosophila. Silencing of myoinhibitory peptide (MIP) neurons significantly increased BW through augmented food intake and fat storage. Likewise, the loss-of-function mutation of mip also increased feeding and BW. Suppressing the MIP pathway induced satiated flies to behave like starved ones, with elevated sensitivity toward food. Conversely, activating MIP neurons greatly decreased food intake and BW and markedly blunted the sensitivity of starved flies toward food. Upon terminating the activation protocol of MIP neurons, the decreased BW reverts rapidly to the normal level through a strong feeding rebound, indicating the switch-like role of MIP pathway in feeding. Surprisingly, the MIP-mediated BW decrease occurred independently of sex peptide receptor (SPR), the only known receptor for MIP, suggesting the presence of a yet-unknown MIP receptor. Together, our results reveal a novel anorexigenic pathway that controls satiety in Drosophila and provide a new avenue to study how the brain actively maintains a constant BW.

The Female Post-Mating Response Requires Genes Expressed in the Secondary Cells of the Male Accessory Gland in Drosophila melanogaster.

Seminal proteins from the Drosophila male accessory gland induce post-mating responses (PMR) in females. The PMR comprise behavioral and physiological changes that include increased egg laying, decreased receptivity to courting males, and changes in the storage and use of sperm. Many of these changes are induced by a "sex peptide" (SP) and are maintained by SP's binding to, and slow release from, sperm. The accessory gland contains two secretory cell types with distinct morphological and developmental characteristics. Products of these "main" and "secondary" cells work interdependently to induce and maintain the PMR. To identify individual genes needed for the morphology and function of secondary cells, we studied iab-6(cocu) males, whose secondary cells have abnormal morphology and fail to provide products to maintain the PMR. By RNA-seq, we identified 77 genes that are downregulated by a factor of >5× in iab-6(cocu) males. By functional assays and microscopy, we tested 20 candidate genes and found that at least 9 are required for normal storage and release of SP in mated females. Knockdown of each of these 9 genes consequently leads to a reduction in egg laying and an increase in receptivity over time, confirming a role for the secondary cells in maintaining the long-term PMR. Interestingly, only 1 of the 9 genes, CG3349, encodes a previously reported seminal fluid protein (Sfp), suggesting that secondary cells may perform essential functions beyond the production and modification of known Sfps. At least 3 of the 9 genes also regulate the size and/or abundance of secondary cell vacuoles, suggesting that the vacuoles' contents may be important for the machinery used to maintain the PMR.

High evening salivary cortisol is an independent predictor of increased mortality risk in patients with systolic heart failure

AimsSerum cortisol independently predicts mortality risk in patients with systolic heart failure. Salivary cortisol may provide advantages as it better reflects the biologically active free compound. Furthermore, sampling is non-invasive and may easily be performed in outpatients. We comparatively evaluated associations of morning (MSC) vs. evening salivary cortisol (ESC) and all-cause mortality risk. Methods and resultsMSC (8am) and ESC (9pm) were determined in 229 patients with heart failure participating in the Interdisciplinary Network for Heart Failure program (66±13years; 21% female; 37% New York Heart Association (NYHA) class III/IV, median left ventricular ejection fraction 33%). The association of cortisol with mortality risk was determined by univariate and Cox multivariable regression analyses adjusting for age, sex, NYHA class, and N-terminal pro-hormone B-type natriuretic peptide. Compared to ESC, MSC was significantly higher and exhibited a higher variance: median 0.59ng/ml (interquartile range 0.41–0.93) vs. 0.25ng/ml (0.15–0.48), p<0.001. During 18months of follow-up, 25 (11%) patients died. In univariate and multivariable models mortality risk was not increased in the highest MSC quartile: crude hazard ratio (HR) 1.81 (95% confidence interval 0.79–4.14, p=0.160), adjusted HR 1.26 (0.51–3.13, p=0.616). However, patients in the highest ESC quartile had a significantly increased mortality risk, suggesting that associations of high ESC and increased mortality were independent of disease severity: crude HR 3.33 (1.50–7.42, p=0.003), adjusted HR 2.49 (1.01–6.14, p=0.047). ESC alone proved the best predictor of mortality. ConclusionHigh ESC but not MSC levels independently predict increased mortality risk in heart failure.

Nutritional Physiology: Sex Elicits a Taste for Salt in Drosophila

Increased salt intake has been found to boost egg production in Drosophila. Females develop a specific appetite for salt following mating. This is not triggered by demand for sodium from developing eggs, but by release of a Sex Peptide into the female's reproductive tract by the male during mating.

Postmating Circuitry Modulates Salt Taste Processing to Increase Reproductive Output in Drosophila

To optimize survival and reproduction, animals must match their nutrient intake to their current needs. Reproduction profoundly changes nutritional requirements, with many species showing an appetite for sodium during reproductive periods. How this internal state modifies neuronal information processing to ensure homeostasis is not understood. Here, we show that dietary sodium levels positively affect reproductive output in Drosophila melanogaster; to satisfy this requirement, females develop a strong, specific appetite for sodium following mating. We show that mating modulates gustatory processing to increase the probability of initiating feeding on salt. This postmating effect is not due to salt depletion by egg production, since abolishing egg production leaves the sodium appetite intact. Rather, the salt appetite is induced need-independently by male-derived Sex Peptide acting on the Sex Peptide Receptor in female reproductive tract neurons. Wefurther demonstrate that postmating appetites for both salt and yeast are driven by the resultant silencing of downstream SAG neurons. Surprisingly, unlike the postmating yeast appetite, the salt appetite does not require octopamine, suggesting a divergence in the postmating circuitry. These findings demonstrate that the postmating circuit supports reproduction by increasing the palatability of specific nutrients. Such a feedforward regulation of sensory processing may represent a common mechanism through which reproductive state-sensitive circuits modify complex behaviors across species.

Developmental environment mediates male seminal protein investment in Drosophila melanogaster.

Summary Males of many species fine‐tune their ejaculates in response to sperm competition risk. Resource availability and the number of competitors during development can also strongly influence sperm production. However, despite the key role of seminal proteins in mediating reproductive processes, it is unclear whether seminal protein investment is dependent on the developmental environment.We manipulated the developmental environment of Drosophila melanogaster by rearing flies at low and high density. As expected, this resulted in large and small (i.e. high and low condition) adult phenotypes, respectively.As predicted, large males produced more of two key seminal proteins, sex peptide (SP) and ovulin, and were more successful at obtaining matings with both virgin and previously mated females. However, there was only a weak and non‐significant trend for large males to transfer more absolute quantities of SP at mating, and thus, small males ejaculated proportionally more of their stored accessory gland SP resources.Males transferred more receptivity‐inhibiting SP to large females. Despite this, large females remated more quickly than small females and thus responded to their developmental environment over and above the quantity of SP they received.The results are consistent with two non‐mutually exclusive hypotheses. First, flies might respond to condition‐dependent reproductive opportunities, with (i) small males investing heavily in ejaculates when mating opportunities arise and large males strategically partitioning SP resources and (ii) small females remating at reduced rates because they have higher mating costs or need to replenish sperm less often.Second, flies may be primed by their larval environment to deal with similar adult population densities, with (i) males perceiving high density as signalling increased competition, leading small males to invest proportionally more SP resources at mating and (ii) females perceiving high density as signalling abundant potential mates, leading to a higher sexual receptivity threshold.Thus, by influencing the mating frequencies of both sexes, as well as the quantity of seminal proteins produced by males and received by females, the developmental environment is likely to have far‐reaching and sex‐specific consequences for sexual selection and sexual conflict.