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At least 397 records · Page 22Linked to original sources
PubMed2006

Cloning and characterization of a cDNA encoding cholesterol side-chain cleavage cytochrome P450 (CYP11A1): tissue-distribution and changes in the transcript abundance in ovarian tissue of Japanese eel, Anguilla japonica, during artificially induced sexual development.

Cholesterol side-chain cleavage cytochrome P450 (CYP11A1: P450scc) is a crucial steroidogenic enzyme that catalyzes an initial step in the production of all classes of steroids. A cDNA encoding Japanese eel P450scc was cloned and characterized. The cDNA putatively encoded 521 amino acid residues with high homology to those of other vertebrate forms. The recombinant P450scc produced in COS-7 cells efficiently catalyzed the conversion of 25-hydroxycholesterol into pregnenolone. By northern blot, a single P450scc transcript of approximately 3.3 kb was detected in both ovary and head kidney. Transcript levels of this enzyme significantly increased throughout ovarian development artificially induced by salmon pituitary homogenate, which suggests that gonadotropic stimuli can induce ovarian expression of the P450scc gene in teleosts, as has been reported in mammals. Furthermore, RT-PCR analysis revealed that gene expression of three steroidogenic enzymes, P450scc, P450c17 and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) show distinctly different tissue-specific patterns of expression in the Japanese eel. The P450scc gene was expressed in ovary and head kidney while the sole source of the P450c17 transcript was ovary. In contrast, 3beta-HSD transcript was detected in all tissues examined, brain, liver, spleen and trunk kidney, etc. These suggest that some steroidogenic enzymes are also expressed in non-endocrine tissues and could potentially regulate the local and/or circulating steroid levels in teleosts, as they do in mammals.

3-Hydroxysteroid Dehydrogenases↗
PubMed1991

Effects of prenatal pyrethroid insecticide exposure on the sexual development of rats.

The prenatal effects of exposure to the insecticide cyhalothrin on the sexual maturation and sexual behavior of rats were investigated. Female rats were dermally treated with 1 ml/day of 0.02% (w/v) aqueous cyhalothrin solution or its vehicle throughout pregnancy. This insecticide administration delayed the age of testicle descent but did not modify the age of vaginal opening. In adulthood, both male and female rat sexual behaviors were not different from vehicle-treated animals. It was concluded that prenatal exposure to cyhalothrin can induce alterations in the development of certain physical characteristics of rats which are not correlated with functional deficiencies in the animals' later life.

Animals↗
PubMed2006

Rethinking the associations between television viewing and adolescent sexuality development: bringing gender into focus.

PURPOSE: To investigate associations between adolescents' television viewing, their sexual behavior, and their perceptions of having power and control in sexual situations (i.e., sexual agency). This study incorporates results from a recent content analysis of television and attends to the different motives for and consequences of girls' and boys' sexual and relational behavior. METHODS: Adolescents (n = 703) aged 11 to 17 years from two public school districts in the Northeastern United States completed surveys assessing their television habits and sexual experiences. Survey data were combined with two content analyses, which assessed the frequency of sexual talk and behavior and the prevalence of gendered messages about sexuality (i.e., the Heterosexual Script) on primetime network television. RESULTS: Adolescents' sexual behavior and feelings of sexual agency were not associated with viewing sexual talk and sexual behavior on television, but were related to viewing the Heterosexual Script, particularly among girls. Girls who saw sexually objectified women and portrayals of men avoiding commitment more often reported less sexual agency. Girls who saw women acting as sexual gatekeepers more often were less sexually experienced and reported more sexual agency. Boys who saw men actively asserting their sexuality more often were less sexually experienced. CONCLUSIONS: The relationship between adolescents' television viewing and sexual experiences depends on the type of sexual messages viewed, the sexual outcome considered, and the gender of the viewer. Parents and practitioners should learn to identify the Heterosexual Script on television and encourage young people to negotiate sexual encounters in safe and positive ways.

Adolescent↗
PubMed1995

Disorders of sexual development.

Over the past 6 years, the structures of four key genes involved in sexual differentiation have been identified (see Figure 2). Mutations within these genes have been demonstrated to cause a significant percentage of the disorders of sexual differentiation described in this chapter. It should be noted, however, that there are significant numbers of patients with these disorders in whom no mutation in any of these genes has yet been characterized. It is probable that further genes involved in sexual differentiation will be identified and shown to be the cause of a number of these diseases.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Changes in the control of gonadotrophin secretion by neurotransmitters during sexual development in rats.

Gonadotrophin hormone releasing hormone (GnRH) is the primary messenger involved in sexual maturation and the onset of puberty. The activity of these neurons are controlled by several neurotransmitters systems. The onset of puberty implies changes from a prepubertal type of gonadotrophin secretion, characterized by a low activity of GnRH neurons, to an adult pattern of secretion with phasic and synchronous activation of GnRH neurons resulting in an increase in the amplitute and frequency of GnRH pulses. Neurotransmitter systems are involved in these changes of GnRH secretion during the onset of puberty by quantitative and qualitative modifications in the effect on GnRH secretion. Serotonin (5-HT), GABA and catecholamines (CA) have qualitative differences in the effects on GnRH and LH secretion in early prepubertal than in late prepubertal and adult female rats. The administration of 5-hydroxytryptophan a precursor of serotonin (5-HT) which increases 5-HT hypothalamic levels induces GnRH and LH release in early prepubertal female rats, these effects dissapear in late prepubertal stage having an inhibitory action in adult female rats. GABAergic system also stimulates GnRH and LH secretion in early prepubertal female rats and has an inhibitory action on this axis in late prepubertal period and in adult female rats. On the contrary the inhibition of catecholamines synthesis by alpha-methyl-p-tyrosine induced an increase of LH secretion in early prepubertal female rats and inhibitory effect in late prepubertal and adult stage. These effects indicate tha CA has an inhibitory effects on GnRH-LH secretion in early prepubertal female rats changing to an stimulatory action in the late puberty and adult rats. These qualitative modifications were observed only in female rats and are probably connected with the hypothalamic differentiation into a female type of gonadotrophin control. Opiadergic and excitatory amino acid systems have quantitative differences on GnRH-LH secretion during prepubertal and peripubertal and adult stages. Opiates has an high inhibitory tone in early prepubertal rats that is decreasing during sexual maturation to reach puberty. On the contrary EAA increases its stimulatory activity on GnRH-LH secretion during sexual maturation by increasing the hypothalamic release of aspartate and glutamate, the excitatory amino acids involved in GnRH release, and the sensibility of NMDA receptors to these amino acids. In conclusion sexual maturation and the onset of puberty in the female rats involve qualitative and quantitative modifications in the effects of neurotrasmitters system on GnRH secretion.

Animals↗
PubMed1979

Men with a distinct testicular hypoplasia: sexual development and activity.

In 101 married men examined for sterility a distinct testicular hypoplasia was found. The long axis of both sexual glands was shorter than 30 mm. Their heterosexual development and activity in sex life were studied by means of HTDM and SAM Questionnaires. A comparison with a group of 325 normozoospermic men of the same age has shown that the heterosexual development was in the pathological group only slightly retarded but that the activity in sex life was distinctly lower in a number of items.

Adult↗
PubMed2000

Genetics of sexual development.

In humans, the choice between male or female development is genetically determined. Sex determination occurs as the undifferentiated and bipotential embryonic gonad becomes either testes or ovary. This process is influenced by the action of genes that have been discovered by genetics studies of sex-reversed patients, XY females, XX males, and XX true hermaphrodites. The development of the gonad is better known in males than in females. SRY, a gene located on the Y chromosome, triggers a complex genetic cascade leading to testicular development. Other genes such as DAX1, located on the X chromosome, antagonize the action of SRY and may influence ovarian development. Only a minority of sex-reversed patients can be explained genetically, suggesting that many genes influencing sex determination are yet to be discovered.

Disorders of Sex Development↗
PubMed1977

Adult cryptorchids: Sexual development and activity.

Plasma testosterone in 72 unilateral and 83 bilateral cryptorchids, 11-45 years of age, revealed that, from 13 years on , values of male hormone were lower than in the control group of 69 normal boys and 85 fertile and potent men. Analysis of heterosexual development by means of the HTDM questionnaire in 49 unilateral and 57 bilateral cryptorchids, aged 21-40 years, who were examined for sterility, revealed only slight social developmental retardation compared to 184 normospermic men from sterile marriages. On the other hand, examination of sexual activity by means of the SAM questionnaire in the same three groups revealed that in cryptorchids the first ejaculation is slightly later and that the frequency of nocturnal emissions in pubescence is lower. In adulthood the patients with cryptorchidism exhibit fewer signs of high sexual activity suca as repeated coitus on the same day or a high frequency of sexual intercourse. Also, there is an earlier appearance of prolonged periods of sexual abstinence.

Adolescent↗
PubMed2006

Regulation of sexual development of Plasmodium by translational repression.

Translational repression of messenger RNAs (mRNAs) plays an important role in sexual differentiation and gametogenesis in multicellular eukaryotes. Translational repression and mRNA turnover were shown to influence stage-specific gene expression in the protozoan Plasmodium. The DDX6-class RNA helicase, DOZI (development of zygote inhibited), is found in a complex with mRNA species in cytoplasmic bodies of female, blood-stage gametocytes. These translationally repressed complexes are normally stored for translation after fertilization. Genetic disruption of pbdozi inhibits the formation of the ribonucleoprotein complexes, and instead, at least 370 transcripts are diverted to a degradation pathway.

Animals↗
PubMed2003

The expression of sterigmatocystin and penicillin genes in Aspergillus nidulans is controlled by veA, a gene required for sexual development.

Secondary metabolism is commonly associated with morphological development in microorganisms, including fungi. We found that veA, a gene previously shown to control the Aspergillus nidulans sexual/asexual developmental ratio in response to light, also controls secondary metabolism. Specifically, veA regulates the expression of genes implicated in the synthesis of the mycotoxin sterigmatocystin and the antibiotic penicillin. veA is necessary for the expression of the transcription factor aflR, which activates the gene cluster that leads to the production of sterigmatocystin. veA is also necessary for penicillin production. Our results indicated that although veA represses the transcription of the isopenicillin synthetase gene ipnA, it is necessary for the expression of acvA, the key gene in the first step of penicillin biosynthesis, encoding the delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase. With respect to the mechanism of veA in directing morphological development, veA has little effect on the expression of the known sexual transcription factors nsdD and steA. However, we found that veA regulates the expression of the asexual transcription factor brlA by modulating the alpha/beta transcript ratio that controls conidiation.

Aspergillus nidulans↗
PubMed2000

Hormones in male sexual development.

Classical embryology has provided a clear view of the timing and hormonal cues that govern sexual differentiation. Molecular biology has added important details to this picture. The cloning of SRY, MIS, and INSL3 provide insight into the molecular signals that provide important cues at the cellular level. Continued understanding of these pathways may provide the necessary information to one day reverse defects of sexual differentiation.

Animals↗
PubMed1980

Postnatal development, sexual difference and sexual cyclic variation of prolactin cells in rats: special reference to the topographic affinity to gonadotroph.

During the postnatal development of rat pituitary it has been shown that PRL cells appear oval, polygonal or cup shaped in both sexes. The oval cells first appear on Day 10 after birth. Development of the latter two shapes is delayed to Days 20 and 30, respectively. The polygonal shaped cells become predominant with sexual maturation. Some of them surround the gonadotrophs with their elongate, cytoplasmic processes, taking on the appearance of cup cells. Although the PRL cells are more numerous in the female than in the male, the cup shaped cells are inverse. Further it is noted that the immunostainability of the oval and polygonal cells varies during the estrous cycle; the weakest reaction was revealed at estrus and the strongest at dioestrus. Those immunohistochemical findings may suggest that the oval cells are premature, the polygonal ones mature and the cup ones particularly differentiated. The topographic affinity between the cup cells and the gonadotrophs may be a morphological indication of their intimate functional relationship.

Animals↗