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At least 415 records · Page 23Linked to original sources
PubMed1987

An endogenous inducer of sexual development in Aspergillus nidulans.

During development of the homothallic ascomycete Aspergillus nidulans, asexual sporulation is followed by sexual sporulation. We report here the detection of a solvent-extractable activity which inhibits asexual sporulation and stimulates premature sexual sporulation. This activity, called precocious sexual inducer (psi), is overproduced by certain mutants that are blocked in both modes of sporulation. Using partially purified preparations of psi, biological response could be elicited with as little as 50 ng of material. We suggest that psi is a hormone-precursor which is converted to a hormone by normal sporulating strains that respond to psi, but not by the asporogenous mutants that overproduce psi. The stability of psi activity gives promise that the compound can be purified and identified.

Aspergillus nidulans↗
PubMed2005

Pheromones and pheromone receptors are required for proper sexual development in the homothallic ascomycete Sordaria macrospora.

The homothallic, filamentous ascomycete Sordaria macrospora is self-fertile and produces sexual fruiting bodies (perithecia) without a mating partner. Even so, S. macrospora transcriptionally expresses two pheromone-precursor genes (ppg1 and ppg2) and two pheromone-receptor genes (pre1 and pre2). The proteins encoded by these genes are similar to alpha-factor-like and a-factor-like pheromones and to G-protein-coupled pheromone receptors of the yeast Saccharomyces cerevisiae. It has been suggested that in S. macrospora, PPG1/PRE2 and PPG2/PRE1 form two cognate pheromone-receptor pairs. To investigate their function, we deleted (delta) pheromone-precursor genes (delta ppg1, delta ppg2) and receptor genes (delta pre1, delta pre2) and generated single- as well as double-knockout strains. No effect on vegetative growth, fruiting-body, and ascospore development was seen in the single pheromone-mutant and receptor-mutant strains, respectively. However, double-knockout strains lacking any compatible pheromone-receptor pair (delta pre2/delta ppg2, delta pre1/delta ppg1) and the double-pheromone mutant (delta ppg1/delta ppg2) displayed a drastically reduced number of perithecia and sexual spores, whereas deletion of both receptor genes (delta pre1/delta pre2) completely eliminated fruiting-body and ascospore formation. The results suggest that pheromones and pheromone receptors are required for optimal sexual reproduction of the homothallic S. macrospora.

Crosses, Genetic↗
PubMed2004

Successful detection of (anti-)androgenic and aromatase inhibitors in pre-spawning adult fathead minnows (Pimephales promelas) using easily measured endpoints of sexual development.

Screening assays have been successfully developed for the detection of (anti-)oestrogenic substances in several fish species, including the fathead minnow (Pimephales promelas). Previous work suggested that pre-spawning adult fathead minnows might be an appropriate life-stage for developing a screen to detect endocrine active substances (EASs). Pre-spawning adult fathead minnows, in which their phenotypic sex could be determined, were exposed in flow-through systems to three reference substances for 21 days, at 25 degrees C. Male and female fish, held in separate tanks, were exposed to dihydrotestosterone (DHT, androgen), flutamide (anti-androgen) and fadrozole (aromatase inhibitor). Nominal (mean measured) concentrations for DHT were 10 (6.0), 32 (6.1) and 100 (8.6) microg l(-1), for flutamide, 100 (95.3), 320 (320.4) and 1000 (938.6) microg l(-1) and for fadrozole, 25 (24.8), 50 (51.7) and 100 (95.5) microg l(-1). After 14 and 21 days exposure, fish were evaluated for growth, secondary sexual characteristics (SSCs, number and prominence of nuptial tubercles), gonadosomatic index (GSI) and plasma vitellogenin (VTG) concentrations. Development of nuptial tubercles was sensitive to both DHT and flutamide exposure. Exposure to DHT significantly increased the number of nuptial tubercles (male characteristic) in both males (more abundant) and females, after 14 days. Flutamide (938.6 microg l(-1), day 21) significantly reduced nuptial tubercle number in male fish. Fadrozole significantly inhibited ovarian growth (lower GSI) and significantly induced testis growth (51.7 and 95.5 microg l(-1)), after 21 days. Plasma VTG concentrations were significantly elevated in male fish (6.1 and 8.6 microg l(-1)), but inhibited in female fish (6.0 microg l(-1)), exposed to DHT. Flutamide had no effect on plasma VTG in male fish, but significantly induced VTG in female fish, after 21 days. Fadrozole significantly inhibited VTG in females and induced VTG synthesis in males, at day 21. These results show that SSCs, GSI and plasma VTG concentrations can be used in pre-spawning adult fathead minnows to screen for a range of classes of EASs. This work complements other published studies in supporting the current OECD effort towards validating a 21 days non-spawning fish screening assay for assessing (anti-)oestrogens, aromatase inhibitors and (anti-)androgens.

Analysis of Variance↗
PubMed1988

Synthesis of specific proteins for sexual development in Dictyostelium discoideum.

The development of Dictyostelium discoideum may proceed by two pathways, macrocyst or fruiting-body formation, the former being the sexual and the latter the asexual cycle. The pathway of development depends on the presence or absence of zygote giant cells which are produced through fusion of opposite mating-type cells in a population, in heterothallic strains. During the early stages of macrocyst development the patterns of developmentally regulated proteins were noted to differ considerably from those during fruiting-body development. Furthermore, the haploid cells around zygote giant cells synthesized a large number of specific proteins for macrocyst development through the influence of giant cells.

Dictyostelium↗
PubMedDate not supplied

[Effect of piracetam on rat reproductive function and the sexual development of their progeny].

Administration of piracetam to infantile rats in a daily dose of 100 mg/kg for 10 days caused acceleration of sexual maturation of females and a slight delay of maturation of males. Antenatal administration of the same dose of piracetam exerted a depressive action on the development of the organs of the reproductive system in males from the offspring with a simultaneous increase in the pituitary gonadotropic activity.

Animals↗
PubMedDate not supplied

[Dynamics of the changes in the content of testosterone and estradiol receptors in the hypothalamus of male rats in the course of sexual development].

The content of receptors to testosterone and estradiol in hypothalamus of the male rats was studied during their sexual maturation (7, 14, 21, 28, 35 and 42 days). In all the age groups of animals the concentration of receptors to testosterone in the cytoplasmic and nuclear fractions of hypothalamus was at a relatively constant level, except in 7 day old males in which the minimal concentration of cytoplasmic and the maximal concentration of nuclear receptors were noted. The highest values of estradiol-binding sites in cytosol of hypothalamus were observed on the 7th and 14th days and in the nuclear fraction on the 28th, 35th and 42nd days of life. The binding of both the hormones with their receptors is a specific process characterized by a high affinity. A suggestion is put forward that receptors both to androgens and estrogens take part in the brain sexual differentiation.

Aging↗
PubMed1993

[Nephropathy-related disorders of physical and sexual development in girls: experience with successful stimulation by zinc, parlodel and norcolut].

The paper reports 3 cases of physical and sexual retardation in girls aged 14-22 with nephropathy: 1 girl had uremia in a conservative stage, 1 patient was put on a chronic hemodialysis for terminal uremia, 1 girl received a renal transplant. In response to combined treatment (zinc sulfate+parlodel) in the former two patients and norcolute therapy in the latter one body mass and growth increased in all the 3. The discussion is concerned with mechanisms of developmental defects in nephropathies, comparative efficacy of the drugs used and social rehabilitation of nephropathy girls with small height and sexual infantilism.

Adolescent↗
PubMed1981

Sexual development, age, and dating: a comparison of biological and social influences upon one set of behaviors.

Data from the U.S. National Health Examination Survey of 12-17-year-old youths were used to determine whether the development of the social behavior of dating is more closely linked to the level of sexual maturation or to the progression through age grades without reference to sexual maturation. Regression analyses and partial correlations show that individuals levels of sexual maturation add very little to the explained variance in dating after age had been taken into account. It appears that social pressures, based on behavior considered typical and appropriate at various ages, determines the onset of dating in adolescents. Individual rates of sexual maturation that deviate from the norm for that age have little impact on dating. These findings show how social standards can reduce dramatically the impact of individual biological processes on institutionalized forms of behavior.

Adolescent↗
PubMed1983

Sexual development, maturation, and behavior.

The Y chromosome directs the primitive gonad to develop into a testis. Without a Y chromosome an ovary will develop, but that ovary will not be normal unless two X chromosomes are present. Active intervention is needed for male differentiation; internal male structures will not be found unless sufficient and effective testosterone is secreted by the immature testis to develop the wolffian duct system into the internal male reproductive tract. The testis must also secrete mullerian regression factor to cause the demise of the internal female duct structures. Finally, enough 5-alpha-reductase activity must be present to convert testosterone into dihydrotestosterone for the normal virilization of the male external genitalia. Without testosterone or its receptor sites, without dihydrotestosterone, and without mullerian regression factor, the reproductive system is female. Early in life, a child assumes both a gender identity (an awareness of what sex he or she belongs to) and a gender role (behavior deemed to be more or less characteristic of one sex or the other). As puberty is passed, sexual orientation becomes more obvious, although the development of that orientation has probably been in the making since early childhood. Early developmental hormone milieu and social environment undoubtedly all play a role in subsequent sexual behavioral patterns, but the extent to which each of these impacts upon that behavior still remains unknown.

Adolescent↗