Implications of the differing roles of the beta 1 and beta 3 transmembrane and cytosplasmic domains for integrin function

Integrins are transmembrane receptors composed of alpha and beta subunits. Although most integrins contain beta 1, canonical activation mechanisms are based on studies of the platelet integrin, allb beta 3. Its inactive conformation is characterized by the association of the alpha llb transmembrane and cytosolic domain (TM/CT) with a tilted beta 3 TM/CT that leads to activation when disrupted. We show significant structural differences between beta 1 and beta 3 TM/CT in bicelles. Moreover, the 'snorkeling' lysine at the TM/CT interface of beta subunits, previously proposed to regulate alpha llb beta 3 activation by ion pairing with nearby lipids, plays opposite roles in beta 1 and beta 3 integrin function and in neither case is responsible for TM tilt. A range of affinities from almost no interaction to the relatively high avidity that characterizes alpha llb beta 3 is seen between various alpha subunits and beta 1 TM/CTs. The alpha llb beta 3-based canonical model for the roles of the TM/CT in integrin activation and function clearly does not extend to all mammalian integrins

Distinct roles of the RasGAP family proteins in C. elegans associative learning and memory

The Ras GTPase activating proteins (RasGAPs) are regulators of the conserved Ras/MAPK pathway. Various roles of some of the RasGAPs in learning and memory have been reported in different model systems, yet, there is no comprehensive study to characterize all gap genes in any organism. Here, using reverse genetics and neurobehavioural tests, we studied the role of all known genes of the rasgap family in C. elegans in associative learning and memory. We demonstrated that their proteins are implicated in different parts of the learning and memory processes. We show that gap-1 contribute redundantly with gap-3 to the chemosensation of volatile compounds, gap-1 plays a major role in associative learning, while gap-2 and gap-3 are predominantly required for short- and long-term associative memory. Our results also suggest that the C. elegans Ras orthologue let-60 is involved in multiple processes during learning and memory. Thus, we show that the different classes of RasGAP proteins are all involved in cognitive function and their complex interplay ensures the proper formation and storage of novel information in C. elegans

Lifestyle impact and the biology of the human scrotum

The possession of a scrotum to contain the male gonads is a characteristic feature of almost all mammals, and appears to have evolved to allow the testes and epididymis to be exposed to a temperature a few degrees below that of core body temperature. Analysis of cryptorchid patients, and those with varicocele suggest that mild scrotal warming can be detrimental to sperm production, partly by effects on the stem cell population, and partly by effects on later stages of spermatogenesis and sperm maturation. Recent studies on the effects of clothing and lifestyle emphasize that these can also lead to chronically elevated scrotal temperatures. In particular, the wearing of nappies by infants is a cause for concern in this regard. Together all of the evidence indirectly supports the view that lifestyle factors in addition to other genetic and environmental influences could be contributing to the secular trend in declining male reproductive parameters. The challenge will be to provide relevant and targeted experimental results to support or refute the currently circumstantial evidence.Richard Ivel

Shared Pattern of Endocranial Shape Asymmetries among Great Apes, Anatomically Modern Humans, and Fossil Hominins

Anatomical asymmetries of the human brain are a topic of major interest because of their link with handedness and cognitive functions. Their emergence and occurrence have been extensively explored in human fossil records to document the evolution of brain capacities and behaviour. We quantified for the first time antero-posterior endocranial shape asymmetries in large samples of great apes, modern humans and fossil hominins through analysis of “virtual” 3D models of skull and endocranial cavity and we statistically test for departures from symmetry. Once based on continuous variables, we show that the analysis of these brain asymmetries gives original results that build upon previous analysis based on discrete traits. In particular, it emerges that the degree of petalial asymmetries differs between great apes and hominins without modification of their pattern. We indeed demonstrate the presence of shape asymmetries in great apes, with a pattern similar to modern humans but with a lower variation and a lower degree of fluctuating asymmetry. More importantly, variations in the position of the frontal and occipital poles on the right and left hemispheres would be expected to show some degree of antisymmetry when population distribution is considered, but the observed pattern of variation among the samples is related to fluctuating asymmetry for most of the components of the petalias. Moreover, the presence of a common pattern of significant directional asymmetry for two components of the petalias in hominids implicates that the observed traits were probably inherited from the last common ancestor of extant African great apes and Homo sapiens

Management of cryptorchidism: a survey of clinical practice in Italy

<p>Abstract</p> <p>Background</p> <p>An evidence-based Consensus on the treatment of undescended testis (UT) was recently published, recommending to perform orchidopexy between 6 and 12 months of age, or upon diagnosis and to avoid the use of hormones. In Italy, current practices on UT management are little known. Our aim was to describe the current management of UT in a cohort of Italian children in comparison with the Consensus guidelines. As management of retractile testis (RT) differs, RT cases were described separately.</p> <p>Methods</p> <p>Ours is a retrospective, multicenter descriptive study. An online questionnaire was filled in by 140 Italian Family Paediatricians (FP) from <it>Associazione Culturale Pediatri </it>(ACP), a national professional association of FP. The questionnaire requested information on all children with cryptorchidism born between 1/01/2004 and 1/01/2006. Data on 169 children were obtained. Analyses were descriptive.</p> <p>Results</p> <p>Overall 24% of children were diagnosed with RT, 76% with UT. Among the latter, cryptorchidism resolved spontaneously in 10% of cases at a mean age of 21.6 months. Overall 70% of UT cases underwent orchidopexy at a mean age of 22.8 months (SD 10.8, range 1.2-56.4), 13% of whom before 1 year. The intervention was performed by a paediatric surgeon in 90% of cases, with a success rate of 91%. Orchidopexy was the first line treatment in 82% of cases, while preceded by hormonal treatment in the remaining 18%. Hormonal treatment was used as first line therapy in 23% of UT cases with a reported success rate of 25%. Overall, 13 children did not undergo any intervention (mean age at last follow up 39.6 months). We analyzed the data from the 5 Italian Regions with the largest number of children enrolled and found a statistically significant regional difference in the use of hormonal therapy, and in the use of and age at orchidopexy.</p> <p>Conclusions</p> <p>Our study showed an important delay in orchidopexy. A quarter of children with cryptorchidism was treated with hormonal therapy. In line with the Consensus guidelines, surgery was carried out by a paediatric surgeon in the majority of cases, with a high success rate.</p

Serum AMH concentration as a marker evaluating gonadal function in boys operated on for unilateral cryptorchidism between 1st and 4th year of life

The aim of this study was to measure the serum AMH (anti-Mullerian hormone) concentrations in a group of boys with or without cryptorchidism, evaluation of karyotypes, testicular position, morphology, and major length of the undescended testes. Fifty boys who were 1–4 years old (median = 2.4 years) with unilateral cryptorchidism were evaluated. All of them underwent orchidopexy in 2010. Prior to the procedure, all of the subjects had undergone karyotyping to exclude chromosomal abnormalities. Fifty healthy boys within the same age range (median = 2.1 years) admitted for planned inguinal hernia repair in 2010, served as controls. Blood samples were collected, while obtaining blood for standard laboratory tests routinely performed before the surgeries. Medians of AMH in boys with cryptorchidism were lower than in boys with inguinal hernia and differed significantly between two groups. Undescended testes were generally found in superficial inguinal pouch (n = 46), in two cases were noted to be in the external ring of the inguinal canal, and in another two instances, in the abdominal cavity. The major lengths of the undescended testes were smaller in comparison to the testes positioned normally (mean of 1 cm vs. a mean of 1.5 cm, respectively). In nine of the cases, the testes had turgor deficit, a drop shape, with epididymides that were small, dysplastic, and separated from the testis. The authors found that AMH was lower in boys with unilateral cryptorchidism (also found to have smaller testis) when compared with the control group

Potential biological role of poly (ADP-ribose) polymerase (PARP) in male gametes

Maintaining the integrity of sperm DNA is vital to reproduction and male fertility. Sperm contain a number of molecules and pathways for the repair of base excision, base mismatches and DNA strand breaks. The presence of Poly (ADP-ribose) polymerase (PARP), a DNA repair enzyme, and its homologues has recently been shown in male germ cells, specifically during stage VII of spermatogenesis. High PARP expression has been reported in mature spermatozoa and in proven fertile men. Whenever there are strand breaks in sperm DNA due to oxidative stress, chromatin remodeling or cell death, PARP is activated. However, the cleavage of PARP by caspase-3 inactivates it and inhibits PARP's DNA-repairing abilities. Therefore, cleaved PARP (cPARP) may be considered a marker of apoptosis. The presence of higher levels of cPARP in sperm of infertile men adds a new proof for the correlation between apoptosis and male infertility. This review describes the possible biological significance of PARP in mammalian cells with the focus on male reproduction. The review elaborates on the role played by PARP during spermatogenesis, sperm maturation in ejaculated spermatozoa and the potential role of PARP as new marker of sperm damage. PARP could provide new strategies to preserve fertility in cancer patients subjected to genotoxic stresses and may be a key to better male reproductive health