Plasma Sex Steroid Concentrations Research Articles

Nonlethal Tools to Identify Mass Ovarian Follicular Atresia in Burbot

AbstractSkipped spawning, or variation in spawning periodicity, occurs in many annual spawning fish species and is an important consideration for population management. We assessed plasma sex steroid concentrations and measured gonad size and ovarian follicle diameter as metrics to nonlethally identify mass ovarian follicular atresia, which may contribute to skipped spawning in Burbot Lota lota. We maintained wild fish in captivity and exposed them to increasing water temperatures during a 3-wk period before the spawning season to induce mass ovarian follicular atresia. We collected ovarian follicles, blood plasma, and gonadal sonograms from fish weekly between January 28, 2018, and March 25, 2018. We histologically analyzed ovarian follicles to confirm stage of maturity. We measured concentrations of plasma sex steroids testosterone (T) and estradiol-17β (E2) by radioimmunoassay. We measured gonad diameter and circumference by ultrasonography and ovarian follicle diameter by image analysis. Mean plasma T concentration decreased from 8.94 ng/mL during late vitellogenesis to 1.83 ng/mL during atresia, suggesting that plasma T concentrations may be used to identify mass ovarian follicular atresia. We do not recommend using plasma E2 concentrations to identify mass ovarian follicular atresia because E2 concentrations rapidly decreased during the completion of vitellogenesis and the initiation of atresia in Burbot; therefore, plasma E2 may not accurately identify mass ovarian follicular atresia. Mean gonad diameter measured by ultrasonography decreased from 4.05 cm during late vitellogenesis to 3.65 cm during atresia. Mean diameter of ovarian follicles decreased during the final week of the study, suggesting that ovarian follicle diameter may be used to identify advanced mass ovarian follicular atresia. The nonlethal tools assessed—plasma sex steroid concentrations, ultrasonography, and ovarian follicle diameter—enable fisheries biologists to determine the occurrence and frequency of mass ovarian follicular atresia among Burbot in Lake Roosevelt and may be applied to other Burbot populations.

Gonadal steroid fluctuations and reproduction results of European grayling (Thymallus thymallus L.) from broodstock farmed in a recirculation aquaculture system

The initial experiment of this study was conducted to determine whether sex steroid concentrations varied before, during and after the reproductive season of European grayling (Thymallus thymallus L.) farmed broodstock confined in a recirculation aquaculture system (RAS). The results indicated that the plasma sex steroid (testosterone - T, progesterone - P4 and estradiol - E2) concentrations varied (P < 0.05) during these reproductive periods. There were greater concentrations of T, P4 and E2 before and during the grayling reproductive season indicating there are important functions of these steroid hormones associated with gonadal maturation, gamete production and reproductive behavior during the spawning period. In the second experiment of this study, the effectiveness of European grayling controlled reproduction treatment regimens was analyzed and there were 34.69 % and 68.18 % having ovulations in the 2 and 3-year-old broodfish, respectively. Of the embryos developing to the eyed-egg stage, there were 3.70 % and 6.87 % derived from eggs of 2- and 3-year-old grayling females, respectively. Proportions of embryos developing from the eyed-egg stage to hatching were 38.1 % and 52.1 % from eggs of 2- and 3-year-old grayling females, respectively, when there was culturing in a RAS. The results indicate that with grayling broodfish there is greater efficacy in induction of reproduction when there is imposing of the controlled reproduction treatment regimen on 3- rather than 2-year-old broodfish.

Plasma estradiol and progesterone concentrations during the female reproductive cycle in a highly placentotrophic viviparous lizard, Mabuya sp.

The neotropical genus Mabuya are obligate placentotrophic viviparous lizards, which have a short vitellogenesis that produces microlecithal oocytes and a prolonged time of gestation (9 to 10 months). The hormonal control of female reproductive activity during follicular growth and pregnancy has not been studied, although it is known that the corpus luteum can produce progesterone, but regresses early in pregnancy, being replaced in this function by the placenta. Through enzyme immunoassay (EIA) we measured the plasma concentrations of estradiol (E2) and progesterone (P4) in females of a population of Mabuya sp at different stages of their reproductive cycle. Previously, we confirmed the presence of P4 in plasma by high-performance liquid chromatography methods with diode-array detector ultraviolet (HPLC-DAD-UV). The average concentration values of E2 and P4 were compared among reproductive stages and their dynamics were related to what is known in other oviparous and viviparous amniotes. The plasma E2 concentrations of Mabuya sp. are below the levels found in other viviparous reptiles, probably related to the substantial reduction of its follicular growth phase. Its highest concentration was detected during vitellogenesis, related to its function in the growth and maturation of the ovarian follicles and oviduct preparation for pregnancy; lower levels were observed during pregnancy, but they increase at the end when a new vitellogenesis event begins and massive placental maternal-fetal nutrient transfer occurs. High concentrations of P4 were found during pregnancy, related to its function in the maintenance of the developing embryos within the oviduct. The highest levels of P4 were found at early gestation, then they descend from mid-gestation to the end of gestation. Although some characteristics of hormonal control related to the high level of placentotrophy were observed in this species, the changes in plasma sex steroid concentrations during the reproductive cycle in females of Mabuya sp. follow patterns seen in other viviparous amniotes.

Gametogenesis and Assessment of Nonlethal Tools to Assign Sex and Reproductive Condition in Burbot

AbstractNonlethal tools (plasma sex steroid concentrations and ultrasound) for assigning sex and reproductive condition in Burbot Lota lota from Lake Roosevelt, Washington, were assessed. Gonadal tissue, blood plasma, and gonadal sonograms were collected monthly from November 2016 to March 2018. Gametogenesis was described by gonadal histology during an entire reproductive cycle to confirm sex and reproductive condition. Plasma testosterone (T) and estradiol‐17β (E2) concentrations were measured by radioimmunoassay. Plasma 11‐ketotestosterone (11‐KT) concentrations were measured by liquid chromatography–mass spectrometry. Plasma sex steroid profiles, gonadosomatic index, and ovarian follicle diameter were also described during an entire reproductive cycle. Plasma 11‐KT concentration was used to assign sex with 82% accuracy during the entire reproductive cycle, and plasma 11‐KT and E2 concentrations were used to assign sex with 98% accuracy when fish were reproductive (i.e., November–March in Lake Roosevelt). Plasma T and E2 concentrations were used to assign reproductive condition in females with 98% accuracy, and plasma T concentration was used to assign reproductive condition in males with 90% accuracy. Ultrasound was used to assign sex with 96% accuracy but was not useful for assigning reproductive condition. Nonlethal tools to assign sex and reproductive condition will enable fisheries biologists to assess reproductive indices of the Burbot population in Lake Roosevelt to inform management decisions.

MON-118 Biochemical and Clinical Correlates of Subcutaneous Adipose mRNA Transcript Levels in Men with T2DM

Background: Altered profiles of subcutaneous adipose tissue gene expression have been independently associated with insulin sensitivity. T2DM has been associated with higher levels of adipokines, inflammatory cytokines and lower plasma sex steroid concentrations. We sought to examine the interplay between these factors, specifically with respect to their associations with mRNA transcript levels in subcutaneous adipose tissue. Methods: Cross-sectional assessment of 162 men with T2DM not treated with insulin (Median age 57 [51 - 61]). Basic anthropometric parameters (including body fat by bioimpedance) were measured. Testosterone, DHT, A4, 17-OHP, E2 and E1 measured by LCMS; TNFα, IL-6, IL-8, IL-1ß, MCP-1, leptin, FSH, LH, SHBG and insulin by ELISA (all fasting) and RT-PCR assessed a panel of 23 gene transcripts in adipose tissue (n = 115). Results: Testosterone (R -.273) & DHT (R -.352) were associated with HOMA-IR independent of BMI but not after adjustment for SHBG. No other biochemical parameters were independently associated with HOMA-IR. Waist circumference (R .351) and HbA1c (R .284) but not IL-6 (R .315) were independently associated with CYP19 expression. HbA1c (R -.222) and A4 (R .207) were independently associated with estrogen receptor α expression. FSH (R -.229) was independently associated with androgen receptor expression. Insulin (R .274) and IL-6 (R .245) were independently associated with adipose leptin expression. Associations with BMI (R .275), DHT (R -.208) and FSH (R -.211) were not significant after adjustment for confounders. Insulin receptor expression was only independently associated with fat mass (R -.378). PPARγ expression was only significantly correlated with HbA1c (R -.204) whilst, after adjustment, MCP-1 expression was only independently associated with percentage fat (R .332). Retinol binding protein 4 expression was independently associated with HbA1c (-.323), MCP-1 (R .297) and FSH (-.254). Conclusion: Circulating sex steroids were not associated with insulin resistance or differences across a wide range of adipose mRNA transcript levels in men with T2DM. Insulin or HbA1c appeared to be a stronger correlate for adipose transcript profiles than circulating adipokines or cytokines. Recent evidence suggests FSH may exert direct effects upon adipose tissue and these findings potentially support this hypothesis.

Photoperiod manipulation for the reproductive management of captive wolffish populations: Anarhichas minor and A. lupus

This study provides new and practical information to implement the use of photoperiodic manipulation for the control of the sexual maturation of Canadian 6+ Atlantic wolffish (Anarhichas lupus) and 3+ first-time spawners spotted wolffish (Anarhichas minor) from Canadian and Norwegian populations. Wolffish reproductive cycle (gametogenesis and oocyte maturation and spermiation) was monitored for 23 consecutive months. Control groups were held under a 12-month simulated natural photoperiod and treatment groups under an 8-month compressed photoperiod. Plasma sex steroid concentrations (estradiol-17β and 11-ketotestosterone), oocyte diameter growth, and milt production were assessed monthly. For all groups under study, fish subjected to the compressed photoperiod spawned 2–6 months earlier than the controls. Complete out-of-shift cycle was not achieved based on the completion of two reproduction cycles, and this is briefly discussed. Photoperiod treatment induced temporal shifts in sex steroid profiles, which are the likely mediators of altered timing of ovulation/final maturation. Photoperiod has a strong influence on the timing of wolffish maturation and could be used as an efficient and inexpensive tool to secure wolffish reproduction operations (year-round supply of egg and milt and/or timing with optimal temperature regimes).

Sexual steroids in serum and prostatic tissue of human non-cancerous prostate (STERPROSER trial).

The specific involvement of the sex steroids in the growth of the prostatic tissue remains unclear. Sex steroid concentrations in plasma and in fresh surgical samples of benign central prostate were correlated to prostate volume. Monocentric prospective study performed between September 2014 and January 2017. Age, obesity parameters, and both serum and intraprostatic concentrations of sex steroids were collected complying with the latest Endocrine Society guidelines and the steroids assessed by GC/MS. Statistical calculations were adjusted for age and body mass index (BMI). Thirty-two patients, equally divided between normal- and high-volume prostate groups, were included in the analysis. High-volume prostate patients were older, heavier and had higher BMI. Comparison adjusted for age and BMI showed higher DHT concentrations in high-volume prostate. Both normal- and high-volume prostate tissues concentrate sex steroids in a similar way. Comparison of enzymatic activity surrogate marker ratios within tissue highlighted similar TT/E1 and TT/E2 ratios, and higher DHT/E1 ratio and lower DHT/PSA ratio in the high-volume prostates. STERPROSER trial provides evidence for higher DHT concentration in highvolume prostates, that could reflect either higher 5-alpha reductase expression or lower expression of downstream metabolizing enzymes such as 3a-hydoxysteroid dehydrogenase.

Environmentally relevant concentrations of nitrate increase plasma testosterone concentrations in female American alligators (Alligator mississippiensis)

Anthropogenic nitrogen is a ubiquitous environmental contaminant that is contributing to the degradation of freshwater, estuarine, and coastal ecosystems worldwide. The effects of environmental nitrate, a principal form of nitrogen, on the health of aquatic life is of increasing concern. We exposed female American alligators to three concentrations of nitrate (0.7, 10 and 100mg/L NO3-N) for a duration of five weeks and five months from hatch. We assessed growth, plasma sex steroid and thyroid hormone concentrations, and transcription levels of key genes involved in steroidogenesis (StAR, 3β-HSD, and P450scc) and hepatic clearance (Cyp1a, Cyp3a). Exposure to 100mg/L NO3-N for both five weeks and five months resulted in significantly increased plasma testosterone (T) concentrations compared with alligators in the reference treatment. No differences in 17β-estradiol, progesterone, or thyroid hormones were observed, nor were there differences in alligator weight or the mRNA abundance of steroidogenic or hepatic genes. Plasma and urinary nitrate concentrations increased with increasing nitrate treatment levels, although relative plasma concentrations of nitrate were significantly lower in five month, versus five week old animals, possibly due to improved kidney function in older animals. These results indicate that environmentally relevant concentrations of nitrate can increase circulating concentrations of T in young female alligators.

Somatic and Neuroendocrine Changes in Response to Chronic Corticosterone Exposure During Adolescence in Male and Female Rats.

Prolonged stress and repeated activation of the hypothalamic-pituitary-adrenal axis can result in many sex-dependent behavioural and metabolic changes in rats, including alterations in feeding behaviour and reduced body weight. In adults, these effects of stress can be mimicked by corticosterone, a major output of the hypothalamic-pituitary-adrenal axis, and recapitulate the stress-induced sex difference, such that corticosterone-treated males show greater weight loss than females. Similar to adults, chronic stress during adolescence leads to reduced weight gain, particularly in males. However, it is currently unknown whether corticosterone mediates this somatic change and whether additional measures of neuroendocrine function are affected by chronic corticosterone exposure during adolescence in a sex-dependent manner. Therefore, we examined the effects of non-invasively administered corticosterone (150 or 300μg/ml) in the drinking water of male and female rats throughout adolescent development (30-58days of age). We found that adolescent animals exposed to chronic corticosterone gain significantly less weight than controls, which may be partly mediated by the effects of corticosterone on food consumption, fluid intake and gonadal hormone function. Our data further show that, despite similar circulating corticosterone levels, males demonstrate a greater sensitivity to these changes than females. We also found that Npy1 and Npy5 receptor mRNA expression, genes implicated in appetite regulation, was significantly reduced in the ventral medial hypothalamus of corticosterone-treated males and females compared to controls. Finally, parameters of gonadal function, such as plasma sex steroid concentrations and weight of reproductive tissues, were reduced by adolescent corticosterone treatment, although only in males. The data obtained in the present study indicate that chronic corticosterone exposure throughout adolescent development results in significant and sex-dependent somatic and neuroendocrine changes, and the results also provide an experimental framework for further investigating the impact of corticosterone on metabolic and neuroendocrine function during adolescence.

Effect of a brief stress on progesterone plasma levels in pregnant and non-pregnant guinea pigs

Steroid hormones are essential for vertebrate reproduction. They are involved in the regulation of major female reproductive events like ovulation, embryo implantation, or gestation. For instance, progesterone promotes foeto-maternal exchanges whereas glucocorticoids stimulate the mobilization of the required energy resources. However, glucocorticoids are key effectors of the stress response; chronic elevations of these hormones can exert negative effects on reproduction. Yet, little is known about the effects of a brief exposure to a stressor on the respective plasma concentrations of sex steroids and glucocorticoids, notably during pregnancy. We examined the impact of a brief stress (handling + 1.5 hours in a bag) on progesterone and cortisol plasma concentrations in pregnant and non-pregnant female guinea pigs. Analyses revealed that: 1) pregnant females exhibited higher baseline progesterone and cortisol concentrations compared to non-pregnant females, as expected; 2) cortisol concentrations increased rapidly following manipulation, revealing a typical hormonal stress response; and, 3) progesterone concentrations decreased on average by 50.9% following the brief stress period, both in pregnant and non-pregnant individuals. These experimental results show for the first time a drastic and rapid impact on progesterone concentration caused by a brief stress.

Gonadal histology and plasma sex steroid concentrations in maturing and mature spring migrants of Caspian lamprey Caspiomyzon wagneri in the Shirud River, southern Caspian Sea, Iran

Maturing degree-days, gonadal histology, and changes in serum sex steroids (progesterone, P; testosterone, T; and 17β-estradiol, E2) were examined in maturing and mature spring migrant Caspian lamprey Caspiomyzon wagneri (Kessler, 1870) in the Shirud River (southern Caspian Sea). Blood and gonad samples were collected from ten fish when they first entered the river (maturing stage) and from ten fish that showed spawning readiness after being held in cages in the river (mature stage). The maturing degree-days of Caspian lamprey from the start of upstream migration to maturation was 208–470°C.day. Serum P and E2 concentrations in maturing females were significantly higher than in maturing males, but in the mature stage, serum P and E2 concentrations of females were lower than males. In both stages, there were no differences in serum concentration of T between females and males. In both males and females, P increased significantly with maturation; T levels likewise appeared to increase, but the difference was not significant. E2 increased significantly with maturation in males, but females showed a significant decrease. Maturing females had similar stage gonads with the germinal vesicle in the polar position. Maturing males had testes that primarily contained secondary spermatocytes with an occasional occurrence of spermatozoa. These results suggest that males mature earlier than females, which is a pattern similar to that found in the sea lamprey.

The reproductive cycle of the male house gecko, Hemidactylus flaviviridis, in relation to plasma steroid concentrations, progesterone receptors, and steroidogenic ultrastructural features, in Oman

The annual testicular cycle of the house gecko Hemidactylus flaviviridis in Oman was studied. Plasma testosterone (T), estradiol (E2) and progesterone (P) concentrations were measured using a sensitive HPLC-MS/MS detection technique. The ultrastructural steroidogenic features in Sertoli and Leydig cells, which were the major source of steriodogenesis, were examined, using transmission electron microscopy (TEM). In addition, progesterone receptors (PR) were examined throughout the testicular cycle, using an immunohistochemical technique. The steroidogenic ultrastructural features were characterized by the presence of smooth endoplasmic reticulum (SER) in the form of cisternal whorls and tubular cisternae, presence of swollen vesiculated mitochondria, and association between SER, mitochondria and lipid droplets. The rise in plasma steroid concentrations was closely associated with the development of the ultrastructural features and PR expression in Leydig and Sertoli cells. During the active phase (November–May), there was a significant rise in plasma steroid concentrations (P<0.05) related to well developed steroidogenic features and strongly expressed PR. During the quiescent phase (June–August) there was a significant decline in plasma steroid concentrations, undeveloped steroiodogenic features and weakly expressed PR. The Renal Sexual Segment (RSS) was fully developed during the active phase. The data provides strong evidence that these ultrastructural steroidogenic features were related to the plasma sex steroid concentrations during the testicular cycle.

A genetically female brain is required for a regular reproductive cycle in chicken brain chimeras

Sexual differentiation leads to structural and behavioural differences between males and females. Here we investigate the intrinsic sex identity of the brain by constructing chicken chimeras in which the brain primordium is switched between male and female identities before gonadal development. We find that the female chimeras with male brains display delayed sexual maturation and irregular oviposition cycles, although their behaviour, plasma concentrations of sex steroids and luteinizing hormone levels are normal. The male chimeras with female brains show phenotypes similar to typical cocks. In the perinatal period, oestrogen concentrations in the genetically male brain are higher than those in the genetically female brain. Our study demonstrates that male brain cells retain male sex identity and do not differentiate into female cells to drive the normal oestrous cycle, even when situated in the female hormonal milieu. This is clear evidence for a sex-specific feature that develops independent of gonadal steroids.

19 CHANGES IN PLASMA STEROID CONCENTRATIONS DURING GESTATION IN COWS WITH SPONTANEOUS ABORTION OF SOMATIC CELL CLONED FETUSES

Cloning of mammals by nuclear transfer frequently results in gestational failure with a variety of abnormalities that are likely due to inappropriate epigenetic reprogramming. Monitoring the placental function during gestation is important to clarify the cause of abnormalities in cloned animals. Sex steroids are produced in the bovine placenta and their levels in maternal peripheral blood are a useful measure of placentation. The objective of this study was to investigate changes in plasma concentrations of sex steroids during gestation in cows aborting cloned fetuses. Donor cells for nuclear transfer were obtained from subculture of cumulus cells retrieved from ovarian follicles of a Japanese Black cow. Recipient oocytes were derived from ovaries obtained at an abattoir and matured in vitro. Metaphase II oocytes were enucleated and each fused with a donor cell by DC pulses. Nuclear-transferred oocytes were activated and cultured for 7 days. Embryos developed to the blastocyst stage were each transferred into the uterine horn ipsilateral to the ovary bearing the CL of 39 multiparous Japanese Black and Holstein crossbred cows at 7 to 8 days after the day of standing oestrus (day 0). Fourteen recipient cows were diagnosed pregnant on Day 40 by ultrasonography and 7 cows delivered at full term. The other seven miscarried on Day 66, 81, 85, 89, 97, 104 and 211. Blood was collected from these cows at least once a week following the pregnancy diagnosis. Progesterone, estrone, oestradiol-17β and estrone sulfate in the blood plasma were measured by RIA and were compared with those in pregnant AI cows. Statistical differences at stages of gestation were analysed with repeated-measures ANOVA. In all miscarried cows, progesterone concentrations were similar to those in AI cows until several days before abortion and then rapidly decreased to the basal level. Concentrations of all estrogens stayed low until abortion in six cows aborting by day 104, whereas estrone and oestradiol-17β started to increase around Day 80 and estrone sulfate gradually increased from around Day 50 and started to increase drastically around Day 80 in AI cows. In another cow aborting on Day 211, profiles of estrone and oestradiol-17β were similar to those in AI cows until around Day 150. Thereafter, concentrations of these estrogens gradually decreased to the basal levels by Day 160 and stayed low until abortion. In this cow, gradual increase in estrone sulfate during Day 50 to 80 was not observed, but the difference in the concentration was not statistically significant from AI cows. The following profile of estrone sulfate was similar to those in active estrogens. The fetus was still alive on day 160 and fetal death was confirmed on day 180 by ultrasonography. These results suggest the possibility that developmental or functional failure of placenta associated with steroid synthesis may be a cause of mid-term miscarriage of a cloned fetus.

Investigating the use of plasma testosterone and estradiol-17β to detect ovarian follicular atresia in farmed white sturgeon, Acipenser transmontanus

To improve quality and yield of caviar in farmed white sturgeon it is essential to correctly assess the stage of ovarian maturity and avoid harvesting females with atretic ovarian follicles. To detect atresia by changes in blood plasma sex steroids, individual females (N = 10) in the late phase of oogenesis were repeatedly bled and their ovaries biopsied before and after onset of ovarian atresia. Follicular atresia was induced by transferring females from cold (10–13 °C) to warm water (20 °C). Ovarian follicle diameter increased and oocyte polarization index decreased in sampled fish over time. Plasma testosterone concentrations in fish with normal follicles were significantly higher, compared to fish with early histological signs of follicular atresia, such as structural changes in the chorion. Plasma estradiol concentrations declined to below detection limit prior to histological signs of atresia in 55% of the fish. Ninety five percent of fish with normal ovarian follicles and 93% of fish with atretic ovarian follicles were correctly classified using a discriminant function analysis based upon plasma testosterone concentrations. Logistic regression models were developed to predict the probability of normal ovaries based on plasma concentrations of sex steroids and can be further refined to improve selection of fish with normal ovaries for caviar harvest.

Inhibition of gametogenesis by the cestodeLigula intestinalisin roach (Rutilus rutilus) is attenuated under laboratory conditions

Reproductive parameters of Ligula intestinalis-infected roach (Rutilus rutilus) which were held under long-tem laboratory conditions with unlimited food supply were investigated. Although uninfected and infected roach showed no difference in condition factor and both groups deposited perivisceral fat, the gonadosomatic-index was significantly lower in infected female and male roach. Quantitative histological analysis revealed that gonad development was retarded upon parasitization in both genders. In contrast to the phenotype described in the field, infected females were able to recruit follicles into secondary growth, but a high percentage of secondary growth follicles underwent atresia. In both genders, the histological data corresponded well with reduced expression of pituitary gonadotropins and lowered plasma concentrations of sex steroids, as revealed by real-time RT-PCR and ELISA, respectively. Furthermore, a reduction of vitellogenin mRNA and modulated expression of sex steroid receptors in the liver was demonstrated. Like in the field, there was a significant adverse impact of L. intestinalis on host reproductive physiology which could not be related to parasite burden. Our results show, for the first time, that maintenance under laboratory conditions can not abolish the deleterious effect of L. intestinalis on gametogenesis in roach, and indicate a specific inhibition of host reproduction by endocrine disruption.

Effects of the sea louse Lepeophtheirus salmonis on temporal changes in cortisol, sex steroids, growth and reproductive investment in Arctic charr Salvelinus alpinus

Groups of mature (5+ year old) Arctic charr Salvelinus alpinus held in sea water were exposed for 34 days to either a high (mean +/-s.e. 0.15 +/- 0.01 sea lice Lepeophtheirus salmonis g(-1) fish mass) (HI), medium (0.07 +/- 0.00 sea lice g(-1) fish mass) (MI) or no [control (C)] sea-lice infection during early stages of gonad development (June to July). Infection with sea lice resulted in increased plasma cortisol concentrations and this was related to intensity of infection; females tended to have higher cortisol concentrations than males at high infection intensities (HI group: female c. 130 ng ml(-1); male c. 80 ng ml(-1)). Plasma osmolality (C c. 330, MI c. 350 and HI c. 415 mOsm) and chloride concentrations (C c. 135, MI c. 155 and HI c. 190 mM) increased significantly with infection intensity, indicating osmoregulatory problems in infected fish. A strong positive relationship between plasma osmolality and cortisol concentration was recorded. Plasma sex-steroid concentrations were influenced negatively by sea-lice infection, particularly in the HI group, and were inversely related to plasma cortisol concentrations. The most heavily infected fish postponed the initiation of reproductive development until exposed to fresh water and timing of ovulation tended to be delayed in these fish. Growth rate and condition were negatively influenced by sea-lice infection and growth rate was inversely related to plasma cortisol concentrations. Sea-lice infection resulted in mortality among females in the HI group, and the proportion of maturing females was lower in the MI group (46%) than in the controls (85%). Egg production in the MI and HI groups was c. 50 and 30% of the C group. Egg size, embryonic survival and fry mass did not differ across groups. Sea lice influence reproductive development and egg production in S. alpinus, and consequently these parasites may influence populations via sublethal effects on broodfish, affecting growth and condition, and their reproductive output.

Influence of the lunar cycle on plasma melatonin, vitellogenin and sex steroids rhythms in Senegal sole, Solea senegalensis

The effect of the moon light cycle on plasma melatonin rhythms was examined in Senegal sole ( Solea senegalensis) exposed to natural outdoor or artificial indoor lighting conditions. Furthermore, in a second experiment, the effect of the lunar cycle on vitellogenin and sex steroids (Testosterone, T; Estradiol, E2; 11-ketotestosterone, 11kt) was studied using mature individuals during reproductive season. In the first experiment, during full moon, plasma melatonin peaked at night in covered tanks (deprived of night illumination) from both outdoor (133.2 ± 12.8 pg ml − 1 ) and indoor (190.6 ± 41.5 pg ml − 1 ) groups. However, for fish in the open tanks, exposed to approximately 0.3 lx of illumination, nocturnal plasma melatonin was significantly reduced ( p < 0.05), approaching to mid-light (ML) values, (79.6 ± 7.1 and 81.8 ± 14.0 pg ml − 1 , for outdoor and indoor groups, respectively). During new moon a similar pattern was observed in outdoor group: fish in the covered tank showed higher melatonin values than those in the open tank, which were exposed to the near undetectable night illumination. In the second experiment, plasma sex steroid concentrations were significantly higher during the full moon compared to the new moon. In the case of females, E2 concentration reduced from 2.4 ± 0.6 to 0.4 ± 0.1 ng ml − 1 between full and new moon samplings, while T decreased from 0.3 ± 0.0 to 0.2 ± 0.0 ng ml − 1 . Vitellogenin, however, did not show such differences between moon phases. In males, 11kt exhibited a plasma concentration of 14.3 ± 2.1 ng ml − 1 during full moon and 4.7 ± 0.7 ng ml − 1 during new moon while T values were 2.6 ± 0.4 and 1.0 ± 0.1 ng ml − 1 for full and new moon, respectively. In conclusion, these findings pointed out the high sensitivity to moon light of the Senegal sole, which could be using the melatonin signalling to synchronize their reproduction rhythms to the lunar cycle.

Reproductive biology of middle Mississippi River shovelnose sturgeon: insights from seasonal and age variation in plasma sex steroid and calcium concentrations

Shovelnose sturgeon Scaphirhynchus platorynchus are endemic to the Mississippi River drainage and are commercially harvested for roe in several states. The status of shovelnose sturgeon populations throughout much of its range is unknown or declining; Mississippi River stocks are experiencing recruitment overfishing and may be at risk of collapse. Restoration of shovelnose sturgeon populations will require additional information on their reproductive biology, including age at maturity and reproductive status and cycles. The objectives of this study were to determine the effects of reproductive stage, fish age, and season on plasma 17-β estradiol (E2) and calcium (Ca2+) concentrations in female shovelnose sturgeon and plasma testosterone (T) concentrations in male shovelnose sturgeon from the middle Mississippi River (MMR). The relationship was also assessed between plasma vitellogenin (VTG) and Ca2+concentrations for female shovelnose sturgeon. Plasma E2 and Ca2+concentrations in females and T concentrations in males differed among reproductive stages, consistent with results of prior research on shovelnose sturgeon and other sturgeon species. VTG and Ca2+concentrations were strongly correlated in female shovelnose sturgeon, indicating that Ca2+can be used as a surrogate for VTG assays for identification of vitellogenic females, as has been shown for other sturgeon species. Age at maturity was estimated at 10 years for males and 9 years for females based on T and E2 profiles, consistent with other recent age at maturity estimates in the MMR and Wabash River determined by gonadal examination. Peaks in plasma sex steroid and Ca2+concentrations during April and October possibly reflected the spring spawning season and provide additional evidence in support of recent documentation of autumn spawning by shovelnose sturgeon in the MMR. Additional research is needed to elucidate autumn spawning by shovelnose sturgeon in the MMR.

Human sex hormone-binding globulin gene expression- multiple promoters and complex alternative splicing.

BackgroundHuman sex hormone-binding globulin (SHBG) regulates free sex steroid concentrations in plasma and modulates rapid, membrane based steroid signaling. SHBG is encoded by an eight exon-long transcript whose expression is regulated by a downstream promoter (PL). The SHBG gene was previously shown to express a second major transcript of unknown function, derived from an upstream promoter (PT), and two minor transcripts.ResultsWe report that transcriptional expression of the human SHBG gene is far more complex than previously described. PL and PT direct the expression of at least six independent transcripts each, resulting from alternative splicing of exons 4, 5, 6, and/or 7. We mapped two transcriptional start sites downstream of PL and PT, and present evidence for a third SHBG gene promoter (PN) within the neighboring FXR2 gene; PN regulates the expression of at least seven independent SHBG gene transcripts, each possessing a novel, 164-nt first exon (1N). Transcriptional expression patterns were generated for human prostate, breast, testis, liver, and brain, and the LNCaP, MCF-7, and HepG2 cell lines. Each expresses the SHBG transcript, albeit in varying abundance. Alternative splicing was more pronounced in the cancer cell lines. PL- PT- and PN-derived transcripts were most abundant in liver, testis, and prostate, respectively. Initial findings reveal the existence of a smaller immunoreactive SHBG species in LNCaP, MCF-7, and HepG2 cells.ConclusionThese results extend our understanding of human SHBG gene transcription, and raise new and important questions regarding the role of novel alternatively spliced transcripts, their function in hormonally responsive tissues including the breast and prostate, and the role that aberrant SHBG gene expression may play in cancer.