1,721,016 research outputs found
Evolutionary consequences of producing competitive ejaculates: insights from an artificial selection study for sperm production on Poecilia reticulata
Full text linkThe aim of my study was to investigate the maintenance of variability for sperm production in the guppy, P. reticulata. Sperm number, which is the main determinant of SC outcome in the Trinidadian guppy population studied in my lab, shows high additive genetic variance despite strong directional selection and very high sire heritability and stronger condition dependence than other ejaculate traits; furthermore, multiply mated females produce higher quality offspring, suggesting that sperm c ompetition, and hence sperm number, may mediate genetic benefits to the female. To clarify the evolutionary processes associated with sperm allocation, I used bi-directional artificial selection for sperm production to 1) estimate the genetic correlations between sperm production and other sexually and naturally selected traits in both males and females; 2) investigate whether sperm production is associated with the rate of senescence and longevity; 3) estimate the contribution of partially recessive deleterious mutations to phenotypic variation in sperm productio
Water and soil pollution as determinant of water and food quality/contamination and its impact on male fertility 11 Medical and Health Sciences 1114 Paediatrics and Reproductive Medicine Rosario Pivonello
No full textAbstract Over the past two decades, public health has focused on the identification of environmental chemical factors that are able to adversely affect hormonal function, known as endocrine disruptors (EDs). EDs mimic naturally occurring hormones like estrogens and androgens which can in turn interfere with the endocrine system. As a consequence, EDs affect human reproduction as well as post and pre-natal development. In fact, infants can be affected already at prenatal level due to maternal exposure to EDs. In particular, great attention has been given to those chemicals, or their metabolites, that have estrogenic properties or antagonistic effects on the activity of androgen or even inhibiting their production. These compounds have therefore the potential of interfering with important physiological processes, such as masculinization, morphological development of the urogenital system and secondary sexual traits. Animal and in vitro studies have supported the conclusion that endocrine-disrupting chemicals affect the hormone-dependent pathways responsible for male gonadal development, either through direct interaction with hormone receptors or via epigenetic and cell-cycle regulatory modes of action. In human populations, epidemiological studies have reported an overall decline of male fertility and an increased incidence of diseases or congenital malformations of the male reproductive system. The majority of studies point towards an association between exposure to EDs and male and/or female reproductive system disorders, such as infertility, endometriosis, breast cancer, testicular cancer, poor sperm quality and/or function. Despite promising discoveries, a causal relationship between the reproductive disorders and exposure to specific toxicants has yet to be established, due to the complexity of the clinical protocols used, the degree of occupational or environmental exposure, the determination of the variables measured and the sample size of the subjects examined. Despite the lack of consistency in the results of so many studies investigating endocrine-disrupting properties of many different classes of chemicals, the overall conclusion points toward a positive association between exposure to EDs and reproductive system. Future studies should focus on a uniform systems to examine human populations with regard to the exposure to specific EDs and the direct effect on the reproductive system
Stabilizing selection on sperm number revealed by artificial selection and experimental evolution
No full textDirectional postcopulatory sexual selection is associated with female sperm storage in Trinidadian guppies
No full textFemale sperm storage (FSS) is taxonomically widespread and often associated with intense sperm competition, yet its consequences on postcopulatory sexual selection (PCSS) are poorly known. Theory predicts that FSS will reduce the strength of PCSS, because sperm characteristics favored before and after FSS may be traded-off, and opportunities for nondirectional PCSS should increase. We explored these questions in the guppy (Poecilia reticulata), by allowing females to mate multiply and by comparing the paternity pattern in two successive broods. Contrary to predictions, the variance in male fertilization success increased after FSS, driven by a change in male paternity share across broods. This change was positively associated with sperm velocity (measured before FSS) but not with the duration of FSS, indirectly suggesting that faster sperm were better in entering female storage organs, rather than in persisting within them. Other male traits, such as male size and orange color, heterozygosity, and relatedness to the female, did not influence paternity after FSS. These results indicate that processes associated with FSS tend to reinforce the strength of PCSS in guppies, rather than weaken it. Further work is necessary to test whether this pattern changes in case of more prolonged FSS
Mutational screening of NR5A1 gene encoding steroidogenic factor 1 in cryptorchidism and male factor infertility and functional analysis of seven undescribed mutations
No full textTo study the role of NR5A1 in cryptorchidism and male factor infertility. Mutations in NR5A1 have been initially associated with primary adrenal insufficiency and 46,XY gonadal dysgenesis and more recently with less severe phenotypes, including preliminary descriptions in severe forms of male factor infertility. Far less clear is the possible involvement of NR5A1 mutations in cryptorchidism
Osteocalcin: A Protein Hormone Connecting Metabolism, Bone and Testis Function
No full textDuring the last decade, the disclosure of systemic effects of osteocalcin (OCN) in its undercarboxylated form contributed to switch the concept of bone from a merely structural apparatus to a fully endocrine organ involved in the regulation of systemic functions. Since that time, the role of OCN as osteokine has been more and more widened appreciated and detailed by the major use of animal models, starting from the original function in the bone extracellular matrix as Gla-protein and spanning from the protective effects towards weight gain, insulin sensitivity and glucose homeostasis, to the anabolic and metabolic roles in skeletal muscle, to the stimulating effects on the testis endocrine function and male fertility, to the most recent preservation from anxious and depressive states through a direct activity on the central nervous system. In this review, experimental data supporting the inter-organ communication roles of this protein are discussed, together with the available data supporting the consistency between experimental data obtained in animals and those reported in humans. In addition, a specific session has been devoted to the possible significance the OCN as a template agonist on its receptor GPRC6A, for the development of novel therapeutic and pharmacological approaches for the treatment of dismetabolic states and male infertility
Role of vitamin D levels and vitamin D supplementation on bone mineral density in Klinefelter syndrome
No full textThis manuscript describes the role of low vitamin D in bone metabolism of Klinefelter subjects. Low vitamin D is frequent in this condition and seems to be more important than testosterone in inducing low bone mineral density (BMD) and osteoporosis. Supplementation with vitamin D restores BMD after 2 years of treatment, whereas testosterone alone seems to be ineffective
COMPOSIZIONI COMPRENDENTI UN PEPTIDE IN GRADO DI STIMOLARE LA VIA DEL SEGNALE GPRC6A-DIPENDENTE
Full text link25-Hydroxyvitamin D insufficiency discriminates cardiovascular risk factors accumulation in peri-pubertal boys undergoing overweight screening
No full textDecreases in serum PFAS are associated with decreases in serum lipids: A longitudinal study on a highly exposed population
Full text linkIntroduction: Perfluoroalkyl substances (PFAS) are widely used, ubiquitous and highly persistent man-made chemicals. Previous cross-sectional studies have consistently linked PFAS exposure to alterations in lipid profiles. However, longitudinal investigations are preferred to mitigate issues related to reverse causation and confounding. Hence, we aimed to investigate the association between changes in serum PFAS and changes in serum lipids, while shedding light on potential modifiers of the examined relationships. Methods: We used data from a health surveillance program offered to residents of a vast area of the Veneto Region (North-Eastern Italy), who had been exposed to PFAS via contaminated drinking water until 2013. We included subjects aged ≥20 years who provided two blood samples over an average 4-year interval (n = 8101). We examined the relationships between changes in PFOA, PFOS and PFHxS and changes in total cholesterol (TC), high-density lipoprotein cholesterol (HDLC) and low-density lipoprotein cholesterol (LDL-C). Linear models were fitted for change in the natural logarithm (ln) of each lipid in relation to the change in the ln of PFAS. From the estimated regression coefficients, we calculated the predicted percentage change in the response for a ln-decrease in PFAS serum concentrations. Results: Overall concentrations of PFOA, PFOS, PFHxS fell by 62.1 %, 24.4 % and 35.4 % from baseline, while small increases in lipids were observed. Declines in PFAS concentrations were associated with decreases in all lipids. For a ln-decrease in PFOA HDL-C decreased by 1.99 % (95 % CI: 1.28, 2.70), TC by 1.49 % (95 % CI: 0.88, 2.10), and LDL-C by 1.40 % (95 % CI: 0.45, 2.37). Conclusions: We found a positive association between changes in PFAS concentrations and changes in cholesterol levels, observing the most marked contrasts across sexes and age groups. Our findings support the reversibility of the associations identified in cross-sectional analyses, emphasizing the importance of water treatment measures in mitigating adverse health effects
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