Distribution of the Receptor for Advanced Glycation End Products (RAGE) in the Human Male Reproductive Tract. Prevalence in Men with Diabetes Mellitus.

BACKGROUND: Diabetics have a significantly higher percentage of sperm with nuclear DNA (nDNA) fragmentation and increased levels of advanced glycation end products (AGEs), in their testis, epididymis and sperm. As the receptor for AGEs (RAGE) is important to oxidative stress and cell dysfunction, we hypothesise, that it may be involved in sperm nDNA damage. METHODS: Immunohistochemistry was performed to determine the presence of RAGE in the human testis and epididymis. A comparison of the receptor's incidence and localisation on sperm from 10 diabetic and 11 non-diabetic men was conducted by blind semi-quantitative assessment of the immunostaining. ELISA analysis ascertained RAGE levels in seminal plasma and sperm from 21 diabetic and 31 non-diabetic subjects. Dual labelling immunolocalisation was employed to evaluate RAGE's precise location on the sperm head. RESULTS: RAGE was found throughout the testis, caput epididymis, particularly the principle cells apical region, and on sperm acrosomes. The number of sperm displaying RAGE and the overall protein amount found in sperm and seminal plasma were significantly higher in samples from diabetic men (p

Male Infertility: A Clinical Reflection

The introduction of intracytoplasmic sperm injection (ICSI) has led to an inappropriate decrease in interest in male fertility. It is apparent that light microscopy provides limited information and molecular techniques show that DNA abnormalities need to be considered further. Abnormalities include not only Yq11 deletions but also DNA strand breaks. Increases in advanced glycation end-products in sperm from well controlled diabetics may provide a mechanism for this damage in non-diabetics. In addition, much publicity is given to decreased male fertility: this is NOT confirmed as technical variations and differences in study populations make it difficult to draw conclusions. The generation of stem cell derived germ cells provides hope for men without germ cells but this is currently only experimental.

The role of Y chromosome deletions in male infertility.

Male infertility affects approximately 2-7% of couples around the world. Over one in ten men who seek help at infertility clinics are diagnosed as severely oligospermic or azoospermic. Recent extensive molecular studies have revealed that deletions in the azoospermia factor region of the long arm of the Y chromosome are associated with severe spermatogenic impairment (absent or severely reduced germ cell development). Genetic research into male infertility, in the last 7 years, has resulted in the isolation of a great number of genes or gene families on the Y chromosome, some of which are believed to influence spermatogenesis.

Does social context influence male mating tactics in Drosophila melanogaster?

Social context, such as mate availability and perceived competition, can influence a male’s mating tactics. In Drosophila melanogaster most research has investigated how physical interactions and the perceived levels of sperm competition alter mating behaviour. I wanted to know if males would respond to the perceived social environments without the presence of physical interaction. Using a unique apparatus, I altered focal males’ social context by separating them physically from a social environment using a screen. Focal males were either in: (i) the presence of rival males and mates, (ii) the presence of potential mates only, (iii) isolation, or (iv) the presence of rival males only. I also manipulated the period the focal male was conditioned to a social environment to assess if the timing of cues is important. My findings suggest that the duration of acclimation alters male mating tactics. Regardless of social environment, the duration a male was conditioned influenced copulation latency. Males that were conditioned to their social environment for the duration of the experiment had differing copulation latencies between environments. Males held in isolation took longer to successfully court females, and transferred less sperm during mating then experimental males in the presence of rival males. Additionally, copulation duration correlated with the number of sperm transferred. Overall, my results suggest that the social environment and the perceived competition level affect mating strategies even without physical interactions. Since this apparatus may trick flies into believing they are a part of a social group, while controlling the male mating status, future work could examine behavioural, genetic and physiological phenotype effects of the social environment for both sexes.

Sexual dimorphism in amphipods: the role of male posterior gnathopods revealed in Gammarus pulex

In the mate-guarding amphipod, Gammarus pulex, the enlarged male posterior gnathopods have been variously suggested to function to grasp and subdue the female, to be used as weapons in fights between males, to signal to the female the male presence and stimulate moult accelaration, egg development or egg extrusion. These hypotheses were tested in a series of experiments, the results of which reveal an unexpected function. Ablation of the posterior gnathopods of males showed that they were neither necessary for, nor advantageous in, establishment and/ or maintenance of precopula mate guarding, with or without competition with intact males. Furthermore, these appendages do not function to advance female moult, or stimulate egg development or extrusion. However, only males with intact posterior gnathopods were able to copulate. We also show that females require a full copulation of several bouts to extrude eggs. We conclude that the function of the posterior gnathopods is to facilitate copulation and suggest future studies focus on the selective pressures acting on copulating males.

Male mating behaviour and mating systems of bees: an overview

Considerable interspecific diversity exists among bees in the rendezvous sites where males search for females and in the behaviours employed by males in their efforts to secure matings. I present an evolutionary framework in which to interpret this variation, and highlight the importance for the framework of (i) the distribution of receptive ( typically immediate post-emergence) females, which ordinarily translates into the distribution of nests, and (ii) the density of competing males. Other than the highly polyandrous honey bees ( Apis), most female bees are thought to be monandrous, though genetic data with which to support this view are generally lacking. Given the opportunity, male bees are typically polygamous. I highlight intraspecific diversity in rendezvous site, male behaviour and mating system, which is in part predicted from the conceptual framework. Finally, I suggest that inbreeding may be far more widespread among bees than has hitherto been considered the case.