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PubMed2000

Rnf4, a RING protein expressed in the developing nervous and reproductive systems, interacts with Gscl, a gene within the DiGeorge critical region.

A yeast 2-hybrid screen was performed to identify possible transcriptional modulators interactive with goosecoid-like (gscl), a transcription factor with suppressive activity, expressed during early brain and gonad development. The screen resulted in the identification of a RING protein known as rnf4 or snrf. Gscl/rnf4 interactions were confirmed by affinity chromatography and by immunoprecipitation. Northern analysis confirmed earlier reports of ubiquitous rnf4 expression in adult tissues. Immunohistochemical analysis of mouse embryos revealed expression primarily in the developing nervous system, with strong expression in the dorsal root ganglia and developing gonads. In contrast to previous reports, both cytoplasmic and nuclear expression of rnf4 was documented. The results reported here confirm and extend earlier reports of rnf4 expression. They suggest for the first time, that in addition to acting as a modulator of transcriptional activity, rnf4 may function, as do other RING proteins, to promote the formation of intracytoplasmic complexes involved in shuttling information between the cytoplasm and the nucleus.

Animals↗
PubMed2003

Immunocytochemical applications of specific antisera raised against synthetic fragment peptides of mummichog GtH subunits: examining seasonal variations of gonadotrophs (FSH cells and LH cells) in the mummichog and applications to other acanthopterygian fishes.

Two distinct types of gonadotrophs, FSH (GtH I) cells and LH (GtH II) cells, were immunocytochemically identified from mummichog (Fundulus heteroclitus; Cyprinodontiformes, Acanthopterygii) pituitary using antisera raised against synthetic fragment peptides of FSHbeta and LHbeta. Both cell types were abundant during the spawning period (spring and early summer) and decreased in number during the post-spawning immature period. The number of FSH cells increased again during the early phases of gonadal development (cortical alveoli accumulation in the oocytes and basal spermatogenesis) in early winter, whereas the number of LH cells did not. Only FSH cells were abundant during the latter phases of gonadal development (vitellogenesis and active spermatogenesis) in early spring. These observations suggest that both GtHs have important yet different roles for reproduction in this species. Antisera against the conservative region of the FSHbeta and the LHbeta subunits immunostained FSH cells and LH cells, respectively, also in red seabream (Pagrus major; Perciformes, Acanthopterygii) and small mouth bass (Micropterus dolomieu; Perciformes, Acanthopterygii), suggesting the possibility of their use for other acanthopterygian fishes.

Animals↗
PubMed1993

Graves' autoimmune serum inhibits gonadal steroidogenesis: development of a Leydig cell bioassay to identify broad spectrum anti-endocrine autoantibodies.

In order to establish an assay for the detection of autoimmune sera with broad spectrum activity, we have investigated the effect of unselected normal and Graves' disease sera upon steroidogenesis by gonadal cells. Steroidogenesis was enhanced by the addition of normal serum in a 3-h primary Leydig cell bioassay, but was inhibited by the majority of Graves' sera. The inhibition was not related to clinical thyroid parameters, such as the severity of the TSH-binding inhibition index, and was not overcome by other agonists or second messenger supplements. Although pituitary TSH preparations bound to and stimulated Leydig cells, TSH receptor mRNA was not detectable and pure recombinant TSH failed to bind or stimulate, indicating contamination of pituitary TSH with LH. The binding of hCG to the Leydig cell luteinizing hormone receptor was not perturbed by the Graves' autoimmune sera, indicating that cross-reactive anti-TSH receptor antibodies were not responsible for the inhibition. By use of intermediates in the stimulatory pathway, the site of Graves' serum inhibition was identified to be distal to hormone receptor/adenylate cyclase coupled responses and proximal to supply of cholesterol for steroidogenesis.

Animals↗
PubMed1984

Inherited XX sex reversal in the cocker spaniel dog.

Nine XX true hermaphrodites and two XX males were discovered in a family of American cocker spaniels. The true hermaphrodites were partially-masculinized females with ovotestes; the XX males had malformed male external genitalia and cryptorchid aspermatogenic testes. Wolffian and Mullerian duct derivatives were present in both true hermaphrodites and XX males. All four sires of sex-reversed dogs were normal XY males; five of the dams were anatomically normal females and one was an XX true hermaphrodite. A second true hermaphrodite reproduced as a female, producing anatomically normal offspring. All matings that produced sex-reversed offspring were consanguineous. Matings of the parents of sex-reversed cocker spaniels to normal beagles with no family history of intersexuality produced only normal offspring. Examination of G-banded karyotypes of the affected animals, their parents, and siblings, revealed no structural anomalies of the chromosomes that were consistently associated with sex-reversal. In assays for serologically-detectable H-Y antigen, the group of XX true hermaphrodites and the group of XX males had mean levels of the antigen not significantly different from that in normal male controls. Female parents of sex-reversed dogs and some of their female siblings were typed H-Y antigen positive, but the mean level of the antigen in this group was less than that of normal male controls. It is proposed that XX sex reversal in cocker spaniels is due to a mutant gene which when homozygous in females, results in a level of H-Y antigen similar to that found in normal males and the gonads develop as ovotestes or testes. When the gene is heterozygous in females, the level of serologically-detectable H-Y antigen is lower than that found in normal males and the gonads develop as normal ovaries. The persistence of Mullerian structures in the presence of testicular tissue suggests that Mullerian inhibiting substance is deficient or ineffective in its action in this condition.

Animals↗
PubMed1987

Effect of pinealectomy on thyroid hormone (T4 and T3) levels in plasma during annual reproductive cycle in the freshwater catfish, Clarias batrachus.

Thyroxine and triiodothyronine (T3) were measured by radioimmunoassay in serum and thyroid gland of the freshwater teleost Clarias batrachus. Pinealectomy increased the glandular levels of the thyroid hormones but decreased the plasma levels of T4 concomitantly with the increase of T3 levels. Most of the effects of pinealectomy on thyroid hormones were restricted to the gonadal development periods. Pinealectomy has shown no significant impact on thyroid hormones during the other periods of the reproductive cycle. Thus, it appears that the pineal gland is inhibitory to thyroid hormones during gonadal development and maturation.

Animals↗
PubMed2006

Preliminary study of responses in mussel (Mytilus edilus) exposed to bisphenol A, diallyl phthalate and tetrabromodiphenyl ether.

Environmental pollutants with hormonal activity including bisphenol, diallyl phtalate and tetrabromodiphenyl ether, have the potential to alter gonadal development and reproduction in aquatic wildlife. Little is known about the biological impact of environmentally relevant concentrations in mussels. To investigate some aspects of their potential estrogenic action, mussels were continuously exposed during 3 weeks. Gonadal development and vitellogenin like protein levels were examined. Bisphenol (50 microg/l) induced the expression of phospho-proteins in females and spawning in both sexes. Diallyl phthalate and tetrabromodiphenyl ether decreased phospho-protein levels in both sexes and induced spawning in males. Moreover, severe damaging effects on ovarian follicles and ovocytes were observed in both bisphenol A- and tetrabromodiphenyl ether-exposed female mussels.

Animals↗
PubMed1998

Preoptic area grafts implanted in mammillary bodies of hypogonadal mice: patterns of GnRH neuronal projections.

Gonadotropin-releasing hormone (GnRH) axons project to the median eminence, where the peptide is released to stimulate pituitary gonadotrophs. Hypogonadal mice (hpg) do not synthesize GnRH due to a deletion in the gene. When neonatal preoptic area (POA) tissue from normal mice containing GnRH neurons is transplanted into the third ventricle of hpg mice, GnRH axons exit the graft and specifically project to the median eminence, where the release of GnRH in the portal circulation induces the stimulation of the pituitary-gonadal axis. To test the hypothesis that the median eminence region is critical to targeting, we placed POA grafts in the region of the mammillary bodies, which never contains GnRH cell bodies, but is nevertheless close to the median eminence. Control mice received bilateral grafts into the anterior hypothalamus. GnRH axons innervated the median eminence in animals with grafts in the mammillary bodies and posterior hypothalamus. Mice with such grafts for 4-5 months had gonadal development, while those with grafts for shorter periods did not. Anterior hypothalamic grafts merged into the third ventricle and, consistent with previous studies, this resulted in GnRH innervation of the median eminence and gonadal development. However, when grafts were located within dorsal regions such as the thalamus, no median eminence innervation was seen. In these cases, GnRH axons borrowed other bundles of fibers to travel within the host brain. The pattern of innervation from grafts within ventro-caudal regions of the hypothalamus vs. that from dorsal regions supported the hypothesis that the median eminence releases diffusible substances directing GnRH outgrowth.

Animals↗
PubMed1986

[Development of the urogenital tract in double-bodied pleurodele chimeras. Effect of position on interactions between the genital glands of different sex].

Chimeric grafts of the embryos of the urodele amphibian (Pleurodeles waltlii Michah.) produced viable, double-bodied animals having two pairs of genital glands of the same sex [homosexual chimeras: anterior testes--posterior testes (male----male) and anterior ovaries--posterior ovaries (female----female)] or of different sex [(heterosexual chimeras: anterior ovaries--posterior testes (female----male) and anterior testes--posterior ovaries (male----female)]. 115 chimeras aged 5 months to 15 years were analysed. Gonadal development in a same animal was observed at different times by exploratory laparotomy. The testes of heterosexual chimeras were removed in order to prevent their inhibitory effect on the ovaries (freemartin effect). The 115 experimental animals were classified according to gonadal development as follows: 47 male----male chimeras (41%), 26 female----female chimeras (23%), 13 female----male chimeras (11%), 29 male----female chimeras (25%). As a rule, male----male chimeras only developed three normal testes. The fourth testis, always situated in the anterior part of the chimera, remained vestigial; nevertheless, it could attain a normal size if the other three testes were removed. female----female chimeras usually had four ovaries; the times of vitellogenesis and of sexual maturity were synchronous in all four ovaries. The anterior ovaries of female----male chimeras were always inhibited and the posterior testes were always normal. male----female chimeras always had normal anterior testes but their posterior ovaries were often weakly inhibited. The high number of male----male chimeras and the low number of female----female ones could be due to a phenotypic reversal of the anterior ovaries in some of the female----male chimeras. The number of male----female chimeras (corresponding to the theoretical number) suggests that the phenotypic sex of the posterior ovaries was not reversed. The freemartin effect in double-bodied heterosexual chimeras depended on the location of the ovaries in relation to the testes. The effect was more significant on the anterior ovaries when posterior testes were present. No or weak freemartin effect was observed when the posterior ovaries developed facing the anterior testes; in about 60% of cases, a reciprocal inhibition or an equilibrium between gonads of different sex occurred.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1997

Social stimulation and regulation of body mass in female starlings

The influence of consexual social stimulation on the regulation of body mass in female European starlings, Sturnus vulgarisduring reproductive development was examined. Twenty-four pairs of birds were housed in three social stimulation treatments: (1) control, where birds were housed in visual isolation from their partner; (2) visual contact, pairs of birds were separated by a clear Perspex screen, preventing direct physical contact, but allowing birds to view each other; (3) complete contact, pairs of birds were housed with no intervening divider, allowing full interactions between birds. The influence of these treatments on gonadal development, body mass and energetic reserves was examined. The manipulation did not significantly influence degree or rate of gonadal development, but did influence total body mass; birds from the complete contact group increased body mass to a greater extent than the other groups. This between-group difference was attributable to changes in lean mass, rather than energetic reserves. However, within the complete contact group, subdominants increased their energetic reserves more than dominants. These results are, in part, consistent with differences in competition for food between the treatment groups influencing mass regulation, although changes in activity levels may also be important. Unlike previous studies, these results suggest that the social environment may influence the regulation of lean mass in addition to energetic reserves.

Journal Article↗
PubMed2000

Seasonal variations and maturity stages in relation to differences in serum levels of gonadal steroids, vitellogenin, and thyroid hormones in the common dentex (Dentex dentex).

Seasonal variations in serum concentrations of 17beta-estradiol (E(2)), vitellogenin (Vg), testosterone (T), 11 ketotestosterone (11-KT), and thyroid hormones (T(4), l-thyroxine; and T(3), 3,5, 3'-triiodo-l-thyronine) were investigated during the first, second, and third reproductive cycles in intensively reared populations of common dentex, Dentex dentex, and correlated with gonadal development and spawning. In females, there were baseline E(2) values (<0.10 ng/ml) and negligible Vg concentrations during the postspawning and pregametogenesis period (June to December), and these increased thereafter to peak during the spawning period. Maximum T(3) and T(4) serum concentrations were found around spawning. There was a positive correlation during vitellogenesis and final maturation between Vg and T(3) (r(2) = 0.366). In addition, Vg and T(3) concentrations were statistically higher in the stages of vitellogenesis and final maturation than at the other stages (P<0.001). Minimum T(3) and T(4) concentrations (October) coincided with the decrease in water temperature and the associated decrease in the daily feeding rate and the specific growth rate. In males, as in females, seasonal changes in serum levels of T and 11-KT were well correlated with gonadal development. The presence of males in the stage of completed spermiogenesis in December coincided with the surge in both androgens and this increase lasted until the end of the spawning period. There were no significant differences in serum T(3) and T(4) levels among the maturity stages. The observed seasonal changes in serum gonadal steroids and Vg reflected the pattern of oocyte development and the spawning behavior of common dentex and were typical of the patterns described in most multiple spawners studied to date. Thyroid hormones may enhance early ovarian development and stimulate vitellogenesis in female dentex.

Aging↗
PubMed2002

The molecular genetic jigsaw puzzle of vertebrate sex determination and its missing pieces.

Since the identification of SRY as the mammalian Y-chromosomal testis-determining gene a decade ago, more than a dozen additional genes essential for early gonadal development in mammals and other vertebrate classes have been identified. The location of these known pieces of the puzzle in the sex determination pathway, and how they interact, is briefly outlined. Two insights emerge: except for SRY, the same basic set of genes appears to operate during early gonadal development in all vertebrate classes, despite the difference in mechanisms; and vertebrate sex determination results from a complex network of regulatory interactions and not from a simple hierarchical cascade of gene actions. However, important pieces of the puzzle are still missing, such as the molecular nature of the sex switch in marsupials, monotremes and non-mammalian vertebrates; the target of SRY; the upstream regulators of SOX9; and the genes in the ovarian pathway. The enigma of SRY-positive XY gonadal dysgenesis females and SRY-negative XX males also indicates that the picture is still far from complete. Filling in these missing pieces is the challenge for the future.

Animals↗
PubMed2001

Carbofuran induced impairment in the hypothalamo-neurohypophyseal-gonadal complex in the teleost, Channa punctalus (Bloch).

The effect of chronic exposure to carbofuran (4.5 ppm in static water) for six months on the gonadal histophysiology and hypothalamo-neurohypophyseal complex was studied in Channa punctatus. Experimental observations revealed significant inhibition of gonadal development with associated degenerative abnormalities as evidenced by ovarian and testicular histology and reduced gonadosomatic index. Degenerative changes in ovary were exihibited by stage I (oogonium) and stage II (immature/non-vitellogenic) oocytes as marked by perinuclear ooplasmic lysis, clumping and dissolution resulting in disintigration of nuclear material altogether attributed to complete degeneration of such oocytes. Testicular deleterious changes included degeneration of spermatogenic elements and necrosis of interstitial cells of Leydig. Correlative histophysiological changes were also observed in the pituitary gonadotrophs and hypothalamic, nucleus pre-opticus, neurons that were smaller, inactive and less in number with associated necrosis. Corresponding to the changes in nucleus pre-opticus neurons, significant inhibition of brain monoamine oxidase enzyme activity was also recorded in treated group. These observations suggest that carbofuran even at low concentration level under long-term exposure is capable of inducing retardation of gonadal development which might have been mediated through the impairment of the hypothalamo-neurohypophyseal-gonadal axis in this species.

Animals↗
PubMedDate not supplied

The role of pineal and eyes in the photoperiodic effect on the gonad of the medaka, Oryzias latipes.

Studies on gonadal development in the female medaka, Oryzias latipes, intact, blinded or blinded-pinealectomized, maintained on different lighting schedules, i.e. LD14:10 and LD 10:14 and under natural daylight conditions, revealed that: 1)blinded fish were capable of responding to annual photoperiodic shifts with alterations of gonadal development, if the pineal was left intact; 2)the mean gonosomatic index(GSI) was higher in blinded fish than in intact fish, during a period from October through April, under LD 14:10, LD 10:14 and the natural daylight conditions; 3)when reared under the natural daylight conditions, the mean GSI in blinded fish was approximately half of that in intact ones in May and June, although the values were significantly larger than those in fish examined during all the other seasons; and 4)in December, the mean GSI was larger in blinded-pinealectomized fish than in intact and blinded ones. These findings seem to indicate that, during the breeding season, the gonadal growth in the medaka is stimulated by the pineal blocking the inhibitory mechanism against the hypothalamo-hypophyseal gonadotropic system, whereas during non-breeding seasons, the gonadal involution is induced by an anti-gonadal factor released by the pineal. It is likely that the effects of photoperiods are exerted on the pineal through the eyes.

Animals↗
PubMed2001

Are male reproductive disorders a common entity? The testicular dysgenesis syndrome.

Growing evidence from clinical and epidemiological studies points to a synchronized increase in the incidence of male reproductive problems, such as genital abnormalities, testicular cancer, reduced semen quality, and subfertility. Together these male reproductive problems may reflect the existence of one common entity, a testicular dysgenesis syndrome (TDS). Experimental and epidemiological studies suggest that TDS is a result of disruption of embryonal programming and gonadal development during fetal life. The recent rise in the prevalence of TDS may be causally linked to endocrine disrupters affecting genetically susceptible individuals. We recommend that future epidemiological studies on trends in male reproduction do not focus on one symptom only, but take all aspects of TDS into account. The potential impact of adverse environmental factors and the role of genetic polymorphisms involved in gonadal development requires further research.

Adult↗
PubMed1986

Maternal transfer of photoperiodic information influences the photoperiodic response of prepubertal Djungarian hamsters (Phodopus sungorus sungorus).

Daylengths during the spring are repeated in reverse order in the autumn. For some photoperiodic species, a given photoperiod may be stimulatory for reproduction in the spring and inhibitory in the autumn. The mechanisms regulating this type of seasonal response have, until recently, remained a mystery. Horton (1984a) showed in Microtus montanus that the photoperiod experienced by the mother influences the gonadal development of her young after weaning. To determine if this phenomenon is characteristic of other photoperiodic rodents, adult Djungarian hamsters were paired on 16L:8D, 14L:10D, or 12L:12D. Young males born from these pairings were killed at 15, 28, and 34 days of age to assess gonadal development (testes weight). At 15 days testicular development was identical in all groups; by 28 days, however, males raised in 16L:8D or 14L:10D exhibited a greater degree of testicular development than those raised in 12L:12D. Next, females maintained on each of the three photoperiods throughout gestation were transferred, with their offspring, to the other two photoperiods at birth. Postnatal exposure to 14L:10D or 12L:12D inhibited testicular development in young that had been gestated on 16L:8D. Both 16L:8D and 14L:10D stimulated testicular growth in animals that had been gestated on 12L:12D or 14L:10D. Therefore, a) 16L:8D stimulates testicular growth in all animals, b) 12L:12D inhibits testicular growth in all animals, and c) the testicular response to 14L:10D depends on the photoperiod experienced by the mother during pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Iopanoic acid prevents spring premigratory increase in body weight of redheaded bunting Emberiza bruniceps.

Effects of long term administration of iopanoic acid (IOP), a potent inhibitor of peripheral conversion of thyroxine (T4) into triiodothyronine (T3), on body weight and gonad development in intact and in thyroidectomized (Thx) redheaded bunting that received replacement therapy with T4 were studied. IOP prevented the premigratory increase in body weight observed in intact bunting (during March/April). In contrast to the Thx birds receiving T4 only, IOP administration in combination with T4 caused a significant decrease in body weight of Thx birds. The gonad development in intact and Thx birds that received IOP was significantly inhibited. Results suggest that IOP through an effective inhibition of peripheral T4-monodeiodination may prevent the spring premigratory fattening. Emphasis is given for an important role of T3 in the physiological preparations associated with migration.

Animals↗
PubMed2003

Prevalence and infection intensity of the ovarian parasite Marteilioides chungmuensis during an annual reproductive cycle of the oyster Crassostrea gigas.

The occurrence of Marteilioides chungmuensis, a protozoan paramyxean parasite in the reproductive system of the Pacific oyster Crassostrea gigas, was observed at Gosung Bay, Korea. Seasonal variation in gonad development was investigated in a suspended cultured oyster population. Gametogenesis began in February and first-spawning was observed between mid and late June when surface water temperature reached 22 to 25 degrees C. Spawning activity extended from mid June to late September, with 2 marked spawning peaks in June and August. Histological examination indicated that gonad development paralleled seasonal fluctuations in water temperature. Spawning in late June was partly associated with a sudden drop in salinity due to large freshwater inputs to the Bay with the summer monsoon. M. chungmuensis occurred in developing and fully mature eggs of spawning oysters in late June to January, but were not observed from February to May. Monthly mean infection intensity was high in late June when most oysters had their first spawning period. The infection level was also relatively high in late August and November, when oysters were spawning or had completed spawning. Several oysters collected in November (11.4%) and December (16.3%) carried a large quantity of ripe but M. chungmuensis-infected eggs, suggesting that infection also causes spawning failure by delaying spawning and destroying ripe oocytes.

Animals↗