Suppression subtractive hybridization analysis reveals expression of conserved and novel genes in male accessory glands of the ant Leptothorax gredleri

Background: During mating, insect males eject accessory gland proteins (Acps) into the female genital tract. These substances are known to affect female post-mating behavior and physiology. In addition, they may harm the female, e. g., in reducing its lifespan. This is interpreted as a consequence of sexual antagonistic co-evolution. Whereas sexual conflict abounds in non-social species, the peculiar life history of social insects (ants, bees, wasps) with lifelong pair-bonding and no re-mating aligns the reproductive interests of the sexes. Harming the female during mating would negatively affect male fitness and sexual antagonism is therefore not expected. Indeed, mating appears to increase female longevity in at least one ant species. Acps are presumed to play a role in this phenomenon, but the underlying mechanisms are unknown. In this study, we investigated genes, which are preferentially expressed in male accessory glands of the ant Leptothorax gredleri, to determine which proteins might be transferred in the seminal fluid. Results: By a suppression subtractive hybridization protocol we obtained 20 unique sequences (USs). Twelve had mutual best matches with genes predicted for Apis mellifera and Nasonia vitripennis. Functional information (Gene Ontology) was available only for seven of these, including intracellular signaling, energy-dependent transport and metabolic enzyme activities. The remaining eight USs did not match sequences from other species. Six genes were further analyzed by quantitative RT-PCR in three life cycle stages of male ants. A gene with carboxy-lyase activity and one of unpredicted function were significantly overexpressed in accessory glands of sexually mature males. Conclusions: Our study is the first one to investigate differential gene expression in ants in a context related to mating. Our findings indicate that male accessory glands of L. gredleri express a series of genes that are unique to this species, possibly representing novel genes, in addition to conserved ones for which functions can be predicted. Identifying differentially expressed genes might help to better understand molecular mechanisms involved in reproductive processes in eusocial Hymenoptera. While the novel genes could account for rapidly evolving ones driven by intra-sexual conflict between males, conserved genes imply that rather beneficial traits might get fixed by a process described as inter-sexual cooperation between males and females.Deutsche Forschungsgemeinschaft - DFG[He 1623/19]CAPES/(DAAD) Deutscher Akademischer Austausch Dienst, Germany[261/07]FAPESPDSMA by CNP

Accessory gland proteins of males in the male-diphenic ant Cardiocondyla obscurior

Seminal fluid proteins are important agents in sperm competition and sexual conflict. In solitary insects, males and females may have different interests concerning the outcome of a mating episode, and males may use seminal fluid to manipulate the physiology and behaviour of the female against the latter's fitness interests. Less is known about the role of seminal fluids in social insects, where the interests of mating partners are more aligned because of life-long pair-bonding. In the male-diphenic ant Cardiocondyla obscurior, mating even with sterilized males appears to prolong the lifespan of queens, suggesting a positive role of seminal fluids. In the present study, using two approaches (two-dimensional gel electrophoresis/mass spectrometry and representational difference analysis), we analyze the seminal fluid and the male accessory glands of both winged and wingless males of C. obscurior. The results obtained reveal the presence of hundreds of proteins, of which proteases and protease inhibitors are also widespread in the seminal fluids of other insects

Selenophosphate-synthetase in the male accessory glands of an insect without selenoproteins

Selenoproteins (containing the 21st proteinogenic amino acid selenocysteine) play important roles throughout all domains of life. Surprisingly, a number of taxa have small selenoproteomes, and Hymenopteran insects appear to have fully lost selenoproteins. Nevertheless, their genomes contain genes for several proteins of the selenocysteine insertion machinery, including selenophosphate synthetase 1 (SELD/SPS1). At present, it is unknown whether this enzyme has a selenoprotein-independent function, and whether the gene is actually translated into a protein in Hymenoptera. Here, we report that SELD/SPS1 is present as a protein in the accessory glands of males of the ant Cardiocondyla obscurior. It appears to be more abundant in the glands of winged disperser males than in those of wingless, local fighter males. Mating increases the lifespan and fecundity of queens in C. obscurior, and mating with winged males has a stronger effect on queen fitness than mating with a wingless male. SELD/SPS 1 has been suggested to play an important role in oxidative stress defense, and might therefore be involved in the life-prolonging effect of mating

Empagliflozin in Patients with Chronic Kidney Disease

Background The effects of empagliflozin in patients with chronic kidney disease who are at risk for disease progression are not well understood. The EMPA-KIDNEY trial was designed to assess the effects of treatment with empagliflozin in a broad range of such patients. Methods We enrolled patients with chronic kidney disease who had an estimated glomerular filtration rate (eGFR) of at least 20 but less than 45 ml per minute per 1.73 m(2) of body-surface area, or who had an eGFR of at least 45 but less than 90 ml per minute per 1.73 m(2) with a urinary albumin-to-creatinine ratio (with albumin measured in milligrams and creatinine measured in grams) of at least 200. Patients were randomly assigned to receive empagliflozin (10 mg once daily) or matching placebo. The primary outcome was a composite of progression of kidney disease (defined as end-stage kidney disease, a sustained decrease in eGFR to < 10 ml per minute per 1.73 m(2), a sustained decrease in eGFR of & GE;40% from baseline, or death from renal causes) or death from cardiovascular causes. Results A total of 6609 patients underwent randomization. During a median of 2.0 years of follow-up, progression of kidney disease or death from cardiovascular causes occurred in 432 of 3304 patients (13.1%) in the empagliflozin group and in 558 of 3305 patients (16.9%) in the placebo group (hazard ratio, 0.72; 95% confidence interval [CI], 0.64 to 0.82; P < 0.001). Results were consistent among patients with or without diabetes and across subgroups defined according to eGFR ranges. The rate of hospitalization from any cause was lower in the empagliflozin group than in the placebo group (hazard ratio, 0.86; 95% CI, 0.78 to 0.95; P=0.003), but there were no significant between-group differences with respect to the composite outcome of hospitalization for heart failure or death from cardiovascular causes (which occurred in 4.0% in the empagliflozin group and 4.6% in the placebo group) or death from any cause (in 4.5% and 5.1%, respectively). The rates of serious adverse events were similar in the two groups. Conclusions Among a wide range of patients with chronic kidney disease who were at risk for disease progression, empagliflozin therapy led to a lower risk of progression of kidney disease or death from cardiovascular causes than placebo