27 research outputs found
Environmental chemicals impact dog semen quality in vitro and may be associated with a temporal decline in sperm motility and increased cryptorchidism
Adverse temporal trends in human semen quality and cryptorchidism in infants have been associated with exposure to environmental chemicals (ECs) during development. Here we report that a population of breeding dogs exhibit a 26 year (1988–2014) decline in sperm quality and a concurrent increased incidence of cryptorchidism in male offspring (1995–2014). A decline in the number of males born relative to the number of females was also observed. ECs, including diethylhexyl phthalate (DEHP) and polychlorinated biphenyl 153 (PCB153), were detected in adult dog testes and commercial dog foods at concentrations reported to perturb reproductive function in other species. Testicular concentrations of DEHP and PCB153 perturbed sperm viability, motility and DNA integrity in vitro but did not affect LH stimulated testosterone secretion from adult testis explants. The direct effects of chemicals on sperm may therefore contribute to the decline in canine semen quality that parallels that reported in the human
Proposed Role for COUP-TFII in Regulating Fetal Leydig Cell Steroidogenesis, Perturbation of Which Leads to Masculinization Disorders in Rodents
Reproductive disorders that are common/increasing in prevalence in human males may arise because of deficient androgen production/action during a fetal ‘masculinization programming window’. We identify a potentially important role for Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) in Leydig cell (LC) steroidogenesis that may partly explain this. In rats, fetal LC size and intratesticular testosterone (ITT) increased ∼3-fold between e15.5-e21.5 which associated with a progressive decrease in the percentage of LC expressing COUP-TFII. Exposure of fetuses to dibutyl phthalate (DBP), which induces masculinization disorders, dose-dependently prevented the age-related decrease in LC COUP-TFII expression and the normal increases in LC size and ITT. We show that nuclear COUP-TFII expression in fetal rat LC relates inversely to LC expression of steroidogenic factor-1 (SF-1)-dependent genes (StAR, Cyp11a1, Cyp17a1) with overlapping binding sites for SF-1 and COUP-TFII in their promoter regions, but does not affect an SF-1 dependent LC gene (3β-HSD) without overlapping sites. We also show that once COUP-TFII expression in LC has switched off, it is re-induced by DBP exposure, coincident with suppression of ITT. Furthermore, other treatments that reduce fetal ITT in rats (dexamethasone, diethylstilbestrol (DES)) also maintain/induce LC nuclear expression of COUP-TFII. In contrast to rats, in mice DBP neither causes persistence of fetal LC COUP-TFII nor reduces ITT, whereas DES-exposure of mice maintains COUP-TFII expression in fetal LC and decreases ITT, as in rats. These findings suggest that lifting of repression by COUP-TFII may be an important mechanism that promotes increased testosterone production by fetal LC to drive masculinization. As we also show an age-related decline in expression of COUP-TFII in human fetal LC, this mechanism may also be functional in humans, and its susceptibility to disruption by environmental chemicals, stress and pregnancy hormones could explain the origin of some human male reproductive disorders
Molecular cloning and in silico analysis of the duck (Anas platyrhynchos) MEF2A gene cDNA and its expression profile in muscle tissues during fetal development
Germ-line activation of the luteinizing hormone receptor directly drives spermiogenesis in a nonmammalian vertebrate
Sodium alginate supplementation modulates gut microbiota, health parameters, growth performance and growth‐related gene expression in Malaysian Mahseer Tor tambroides
Quantitative expression (Walbaum) of immunological factors in rainbow trout, Oncorhynchus mykiss (Walbaum), after infection with either Flavobacterium psychrophilum, Aeromonas salmonicida, or infectious haematopoietic necrosis virus
Fsh and Lh direct conserved and specific pathways during flatfish semicystic spermatogenesis
Porous aerosol in degassing plumes of Mt. Etna and Mt. Stromboli
Aerosols of the volcanic degassing plumes from Mt. Etna
and Mt. Stromboli were probed with in situ instruments on board the Deutsches
Zentrum für Luft- und Raumfahrt research aircraft Falcon during the
contrail, volcano, and cirrus experiment CONCERT in September 2011. Aerosol
properties were analyzed using angular-scattering intensities and particle
size distributions measured simultaneously with the Polar Nephelometer and
the Forward Scattering Spectrometer probes (FSSP series 100 and 300),
respectively. Aerosols of degassing plumes are characterized by low values
of the asymmetry parameter (between 0.6 and 0.75); the effective diameter
was within the range of 1.5–2.8 µm and the maximal diameter was
lower than 20 µm. A principal component analysis applied to the Polar
Nephelometer data indicates that scattering features of volcanic aerosols of
different crater origins are clearly distinctive from angular-scattering
intensities of cirrus and contrails. Retrievals of aerosol properties
revealed that the particles were "optically spherical" and the estimated
values of the real part of the refractive index are within the interval from
1.35 to 1.38. The interpretation of these results leads to the conclusion
that the degassing plume aerosols were porous with air voids. Our estimates
suggest that aerosol particles contained about 18 to 35 % of air voids in
terms of the total volume