Male reproductive health has deteriorated in many countries during the last few decades.In the 1990s, declining semen quality has been reported from Belgium, Denmark, France, and Great Britain.The incidence of testicular cancer has increased during the same time.Incidences of hypospadias and cryptorchidism also appear to be increasing.Similar reproductive problems occur in many wildlife species.There are marked geographic differences in the prevalence of male reproductive disorders.While the reasons for these differences are currently unknown, both clinical and laboratory research suggest that the adverse changes may be inter-related and have a common origin in fetal life or childhood.Exposure of the male fetus to supranormal levels of estrogens, such as diethlylstilbestrol, can result in the above-mentioned reproductive defects.The growing number of reports demonstrating that common environmental contaminants and natural factors possess estrogenic activity presents the working hypothesis that the adverse trends in male reproductive health may be, at least in part, associated with exposure to estro- genic or other hormonally active (e.g., antiandrogenic) environmental chemicals during fetal and childhood development.An extensive research program is needed to understand the extent of the problem, its underlying etiology, and the development of a strategy for prevention and inter- vention.
Amniotes, mammals, reptiles, and birds form common extraembryonic membranes during development to perform essential functions, such as protection, nutrient transfer, gas exchange, and waste removal. Together with the maternal uterus, extraembryonic membranes of viviparous (live-bearing) amniotes develop as an endocrine placenta that synthesizes and responds to steroid hormones critical for development. The ability of these membranes to synthesize and respond to steroid hormone signaling has traditionally been considered an innovation of placental amniotes. However, our laboratory recently demonstrated that this ability extends to the chorioallantoic membrane (CAM) of an oviparous (egg-laying) amniote, the domestic chicken, and we hypothesized that steroidogenic extraembryonic membranes could be an evolutionarily conserved characteristic of all amniotes because of similarities in basic structure, function, and shared evolutionary ancestry. In this study, we examined steroid hormone synthesis and signaling in the CAM of another oviparous amniote, the American alligator (Alligator mississippiensis). We quantified mRNA expression of a steroidogenic factor involved in the regulation of steroidogenesis (NR5A1), the key steroidogenic enzymes involved in the synthesis of progestins (HSD3B1), androgens (CYP17A1), and estrogens (CYP19A1), and the receptors involved in the signaling of progestins (PR), androgens (AR), estrogens (ESR1 and ESR2), and glucocorticoids (GR). Furthermore, we performed protein immunolocalization for PR and ESR1. Collectively, our findings indicate that the alligator CAM has the capability to regulate, synthesize, and respond to steroid hormone signaling, thus, supporting our hypothesis that the extraembryonic membranes of Amniota share a unifying characteristic, that is, the ability to synthesize and respond to steroid hormones.
Metal contamination from Space Shuttle launch activity was examined using inductively coupled plasma-atomic emission spectroscopy in a two-tier study sampling surface water collected from several sites at the Kennedy Space Center (KSC) and associated Merritt Island National Wildlife Refuge in east central Florida. The primary study examined both temporal changes in baseline metal concentrations (19 metals) in surface water (1996 to 2009, 11 sites) samples collected at specific long-term monitoring sites and metal deposition directly associated with Space Shuttle launch activity at two Launch Complexes (LC39A and LC39B). A secondary study examined metal concentrations at additional sites and increased the amount of elements measured to 48 elements. Our examination places a heavy focus on those metals commonly associated with launch operations (e.g., Al, Fe, Mn, and Zn), but a brief discussion of other metals (As, Cu, Mo, Ni, and Pb) is also included. While no observable accumulation of metals occurred during the time period of the study, the data obtained postlaunch demonstrated a dramatic increase for Al, Fe, Mn, and Zn. Comparing overall trends between the primary and secondary baseline surface water concentrations, elevated concentrations were generally observed at sampling stations located near the launch complexes and from sites isolated from major water systems. While there could be several natural and anthropogenic sources for metal deposition at KSC, the data in this report indicate that shuttle launch events are a significant source.
Stress responses to numerous environmental conditions have been studied in a wide range of fish species. Defining the relationship between stress and endocrine function is particularly critical to long-lived species such as sturgeons, whose economic viability relies heavily on proper endocrine function for the production of caviar. In this study, we examined the induced stress response, defined by plasma cortisol and glucose concentrations, and its relationship to plasma 17beta-estradiol, testosterone and 11-ketotestosterone concentrations in cultured female Siberian sturgeon (Acipenser baeri). Fish were acutely stressed using capture and confinement for a period of 4 h, and blood samples were drawn according to four treatment regimens: treatment 1, fish were bled at 0 h; treatment 2, fish were serially bled at 0 h, 1 h and 4 h; treatment 3, fish were bled at 1 h and 4 h; treatment 4, fish were bled at 4 h only. Fish were surgically sexed immediately after drawing blood at 0 h. After 1 h of acute stress, fish demonstrated a marked increase in plasma cortisol concentration, which remained elevated throughout the 4-h sampling period. The plasma concentration of sex steroids did not exhibit an inverse relationship with plasma cortisol concentration. Plasma testosterone concentration was significantly elevated during the periods of greatest stress. Plasma estradiol and 11-ketotestosterone (11-KT) concentrations were not affected by the acute stressors in this experiment. Serial bleedings, however, affected the associated stress response, which is an important consideration for future studies with this species. This is the first study to define the relationship between stress and possible changes in sex steroid concentration in this threatened and commercially important species.
We investigated ovary and testis development of Alligator mississippiensis during the first 5 months posthatch. To better describe follicle assembly and seminiferous cord development, we used histochemical techniques to detect carbohydrate-rich extracellular matrix components in 1-week, 1-month, 3-month, and 5-month-old gonads. We found profound morphological changes in both ovary and testis. During this time, oogenesis progressed up to diplotene arrest and meiotic germ cells increasingly interacted with follicular cells. Concomitant with follicles becoming invested with full complements of granulosa cells, a periodic acid Schiff's (PAS)-positive basement membrane formed. As follicles enlarged and thecal layers were observed, basement membranes and thecal compartments gained periodic acid-methionine silver (PAMS)-reactive fibers. The ovarian medulla increased first PAS- and then PAMS reactivity as it fragmented into wide lacunae lined with low cuboidal to squamous epithelia. During this same period, testicular germ cells found along the tubule margins were observed progressing from spermatogonia to round spermatids located within the center of tubules. Accompanying this meiotic development, interstitial Leydig cell clusters become more visible and testicular capsules thickened. During the observed testis development, the thickening tunica albuginea and widening interstitial tissues showed increasing PAS- and PAMS reactivity. We observed putative intersex structures in both ovary and testis. On the coelomic aspect of testes were cell clusters with germ cell morphology and at the posterior end of ovaries, we observed "medullary rests" resembling immature testis cords. We hypothesize laboratory conditions accelerated gonad maturation due to optimum conditions, including nutrients and temperature. Laboratory alligators grew more rapidly and with increased body conditions compared with previous measured, field-caught animals. Additionally, we predict the morphological maturation observed in these gonads is concomitant with increased endocrine activities.
