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PubMed1996

Effects of metal-contaminated soils on the growth, sexual development, and early cocoon production of the earthworm Eisenia fetida, with particular reference to zinc.

Juvenile Eisenia fetida (Savigny) were exposed for 20 weeks to an uncontaminated soil and to soils contaminated with cadmium, copper, lead, and zinc collected from seven sites at different distances from a smelting works at Avonmouth, southwest England. The survival, growth (= weight after 5 weeks exposure), time to sexual maturation (= percentages of adults present after 8 weeks), and reproduction (= number of cocoons produced by the worms) were compared with soil metal concentrations. Of the parameters measured, growth and sexual maturation time had the lowest EC50 values. The effects of metal-contaminated soils could be attributed both to the direct toxicity of the metals and to changes in the "scope for growth" of the exposed worms. A comparison of the results with those of an earlier toxicity test conducted with adult worms indicated that juveniles are more sensitive to metals than adults. Significant toxic effects on the growth and sexual maturation times of juveniles were detected in soils from sites for which no significant effects on the cocoon production of adults could be detected. The greater sensitivity of juvenile worms indicates the importance of considering effects on a variety of life history stages when conducting a risk assessment of the effects of pollutants in soils. Although E. fetida does not occur naturally in soils at Avonmouth, the present study provides evidence to support the suggestion that pollution from the smelter is responsible for the absence of worms within 2 km of the factory. Results presented in this paper, and from previous studies, suggest the observed absence is due to the effects of zinc on the growth and maturation of juveniles and the cocoon production rate of adult worms.

Animals↗
PubMed1981

Sexual development and fertility of Jamaican female patients with homozygous sickle cell disease.

Results of a questionnaire study of 91 Jamaican patients with homozygous sickle cell (SS) disease and 59 Jamaican control subjects of similar socioeconomic status indicated a mean delay of 2.3 years in age at menarche and of 3.9 years in age at first pregnancy in Ss disease. The mean interval between first sexual exposure and pregnancy was similar in the two groups. The delay in age at first pregnancy in SS disease resulted partly from the delay in puberty, but it also resulted from a further delay in first sexual exposure, with a mean interval between menarche and first sexual exposure of 2.6 and 4.4 years in control subjects and patients, respectively. Physical and social factors that related to this delay were reflected in the higher prevalence of casual unions in patients; this finding implied lesser sexual exposure. Although the similar interval between first sexual exposure and pregnancy did not suggest a lesser fertility in patients with SS disease, the number of infants born to patients with SS disease was less at all ages compared with Jamaican standards. This finding might reflect lesser fertility subsequent to the first pregnancy.

Adolescent↗
PubMed2006

A unique fungal two-component system regulates stress responses, drug sensitivity, sexual development, and virulence of Cryptococcus neoformans.

The stress-activated mitogen-activated protein kinase (MAPK) pathway is widely used by eukaryotic organisms as a central conduit via which cellular responses to the environment effect growth and differentiation. The basidiomycetous human fungal pathogen Cryptococcus neoformans uniquely uses the stress-activated Pbs2-Hog1 MAPK system to govern a plethora of cellular events, including stress responses, drug sensitivity, sexual reproduction, and virulence. Here, we characterized a fungal "two-component" system that controls these fundamental cellular functions via the Pbs2-Hog1 MAPK cascade. A typical response regulator, Ssk1, modulated all Hog1-dependent phenotypes by controlling Hog1 phosphorylation, indicating that Ssk1 is the major upstream signaling component of the Pbs2-Hog1 pathway. A second response regulator, Skn7, governs sensitivity to Na+ ions and the antifungal agent fludioxonil, negatively controls melanin production, and functions independently of Hog1 regulation. To control these response regulators, C. neoformans uses multiple sensor kinases, including two-component-like (Tco) 1 and Tco2. Tco1 and Tco2 play shared and distinct roles in stress responses and drug sensitivity through the Hog1 MAPK system. Furthermore, each sensor kinase mediates unique cellular functions for virulence and morphological differentiation. Our findings highlight unique adaptations of this global two-component MAPK signaling cascade in a ubiquitous human fungal pathogen.

Cryptococcus neoformans↗
PubMed1993

Innate variability in sexual development irrespective of body fatness in gilts.

To separate the effects of fatness from those of lean tissue growth on reproductive development, 52 gilts (33.2 kg, 75 d) had ad libitum access to a high-energy diet (HE; n = 31) or were fed restrictively a low-energy diet (approximately 80% of ad libitum; LE; n = 31) until 160 d of age. All HE and 15 LE gilts were then slaughtered; the 16 LE gilts that remained were then allowed ad libitum access to the low-energy diet until slaughter at 175 d (LER). Twelve littermate trios allocated across treatments were cannulated and bled during both unfed and fed states before slaughter. Gilts in the HE group were 8 kg heavier, 3.5 mm fatter (backfat), and consumed 14.9 MJ of DE more per day than gilts in the LE group at 160 d (hereafter P < .05); LER gilts were 7 kg heavier, 2.2 mm fatter, and consumed 21 MJ of DE more per day at 175 d than LE gilts at 160 d. Carcass fat was lower in LE gilts than in HE or LER gilts, but carcass lean was similar among groups. Treatment did not affect basal or episodic LH or growth hormone secretion, reproductive tract weight, follicular volume, or plasma or follicular fluid estradiol-17 beta. Postprandial plasma insulin was greater in LER than in HE or LE gilts, but plasma insulin-like growth factor I and urea nitrogen were similar among groups. Plasma nonesterified fatty acids and creatinine were greater in HE than in LE or LER gilts. These results suggest that when protein accretion rate is maximal, differences in fatness do not influence reproductive development in the prepubertal gilt. Irrespective of treatment, the only measured factor showing an association with ovarian development was the innate variability in episodic and basal LH secretion.

Adipose Tissue↗
PubMed2001

Renal function, cytogenetic measurements, and sexual development in adolescents in relation to environmental pollutants: a feasibility study of biomarkers.

BACKGROUND: Human exposure to chemicals is normally monitored by measurement of environmental pollutants in external media. We investigated whether biomarkers in adolescents can show exposure to, and health effects of, common environmental pollutants. METHODS: We recruited 200 17-year-old adolescents (120 girls) from a rural control area and from two suburbs polluted by a lead smelter and two waste incinerators. We measured biomarkers of exposure and of effect in blood and urine samples, and obtained questionnaire data. School doctors measured testicular volume and staged sexual maturation. FINDINGS: Internal exposure was mostly within current standards. Concentrations of lead and cadmium in blood, PCBs (polychlorinated biphenyls) and dioxin-like compounds in serum samples, and metabolites of VOCs (volatile organic compounds) in urine were higher in one or both suburbs than in the control area. Children who lived near the waste incinerators matured sexually at an older age than others, and testicular volume was smaller in boys from the suburbs than in controls. Biomarkers of glomerular or tubular renal dysfunction in individuals were positively correlated with blood lead. Biomarkers of DNA damage were positively correlated with urinary metabolites of PAHs (polycyclic aromatic hydrocarbons) and VOCs. Interpretation Biomarkers can be used to detect environmental exposure to pollutants and measure their biological effects before overt disease develops. Our findings suggest that current environmental standards are insufficient to avoid measurable biological effects.

Adolescent↗
PubMed1987

Variations in soluble and particulate ABP of rat testis during sexual development.

Androgen binding activity (ABP) was determined in two different fractions of developing rat testicular homogenates: in cytosol (cABP) and in a particulate fraction isolated by differential centrifugation (pABP). Homogenates were prepared under stabilization conditions by adding 350 nM testosterone to the homogenization buffer. cABP and pABP concentrations were maximal in 22- to 32-day-old animals, to decrease thereafter during sexual maturation. However, both cABP and pABP increased with age when results were expressed on a per organ basis. pABP could be solubilized under conditions in which it could retain its binding activity. It was then photoaffinity labeled and chromatographed on a Sephadex G 200 column using cytosolic epididymal ABP as a control. Similarities between cABP and pABP include not only the same androgen binding characteristics but also the same exclusion volume after Sephadex G 200 chromatography. Since pABP is only present in Sertoli cells, it might represent ABP before being secreted. Because of its intracellular localization, it could play a role in the compartmentalization of androgens within the testis.

Androgen-Binding Protein↗
PubMed1986

Postpubertal sexual development in merino rams after differential feeding through puberty.

Spring-born Merino ram lambs were reared on 130%, 165% or 200% of recommended maintenance energy requirements from 7 to 12 mo of age and were then placed on a common plane of nutrition from 12 to 25 mo of age. During the latter 13 mo, the 24 rams were studied for changes in live-weight and testicle characteristics. Semen characteristics and sexual activity were observed from 12 to 19 mo of age. At the beginning of the study, groups coming from low (L), medium (M), and high (H) nutrition had liveweights of 38.9, 46.8, and 53.6 kg (P < 0.05) and scrotal circumferences of 24.6, 28.9, and 32.1 cm (P < 0.05), respectively. When the rams were given common feed conditions, the differences between groups in both liveweight and scrotal circumference quickly decreased and were not significant by the sixth month. No significant differences existed between groups in ejaculate characteristics during semen collection, except in sperm density which, at the end of semen collection, was significantly (P < 0.05) higher in Group M (3.98 x 10(9)/ml) than in Group L (2.55 x 10(9)/ml). However, in analyses of pooled data, there were significant differences between months of collection in sperm density, total number of sperm per ejaculate, and percentages of live and abnormal sperm. The data indicate that differential nutrition during the first year of life will affect some reproductive characters contemporaneously, but with restored feeding, reproductive differences are resolved more quickly than those in liveweight and the changes proceed despite countervailing photoperiodic influences.

Journal Article↗
PubMed1996

Stress signal, mediated by a Hog1-like MAP kinase, controls sexual development in fission yeast.

We identified the phh1+ gene that encodes a MAP kinase as the effector of Wis1 MAP kinase kinase in fission yeast, which is highly homologous with HOG1 of S. cerevisiae. Heterothalic phh1 dsiruptant is phenotypically indistinguishable from wis1 deletion mutant, both displaying the same extent of partial sterility and enhanced sensitivity to a variety of stress. In phh1 disruptant, nitrogen starvation-induced expression of ste11+, a key controller of sexual differentiation, is markedly diminished. Ectopic expression of ste11+ effectively restores fertility, but not stress resistance, to the phh1 disruptant. These data show that stress signal, mediated by a MAP kinase, is required for efficient start of sexual differentiation.

Amino Acid Sequence↗
PubMed1985

Plasma prolactin, LH, FSH and estrogen excretion patterns in gilts during sexual development.

Plasma prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay in groups of eight gilts sampled every 20 min for 6 h at about 2-wk intervals between 15 and 192 d of age. The PRL levels were high at 15 and 28 d, declined at 40 d just after weaning and then rose slowly until 192 d of age. The number of LH pulses during 6 h was higher between 83 and 125 d than at the other periods. Magnitude of LH pulses was highest at 15 d, constant from 54 to 125 d, fell at 137 d and remained low until 192 d. Plasma FSH was high from 15 to 125 d, with a maximum at 54 d. It declined slowly until 168 d and did not change thereafter. Estrogen excretion was estimated from urine excretion of estrone (E1; conjugated plus nonconjugated E1) per 24 h from 40 d until puberty in three gilts and at 156 and 174 d in two other animals. The E1 excretion increased with age and four levels were described before peak values with the onset of first estrus. The first increase in E1 excretion occurred between 68 and 110 d, when antral follicles appeared in the ovaries. It was subsequent to the highest levels of FSH and concomitant with the increased frequency of LH pulses. The drop in levels of both gonadotropins after 125 d probably corresponded to the development of the negative feedback as a result of greater ovarian activity in these gilts.

Aging↗
PubMed1999

Effects of "products of chicken embryo" on growth and sexual development in rats.

Products of Chicken Embryo (PCE) such as Ji-Pei-Jing is a kind of food for Chinese children prepared from chicken embryo. Female rats on 21 days were administered with aqueous solutions of Ji-Pei-Jing (1.2%, 3%, 12%, and 48%, respectively) by gavage up to their onsets of puberty. The rats in the control group were treated with distilled water. However, Ji-Pei-Jing treatment exerted some effects on sexual maturation in the immature female rats. Essentially, the effects showed a dose-response tendency with an inverted "U" shape. The age of vaginal opening for group treated with Ji-Pei-Jing was significantly earlier than that to the control. Its uterus weight/b.w. ratio also significantly increased on day 30 and at the first estrus. There were significantly increases in the adrenal weight/b.w. ratio of 30-day-old rats that were treated with 3%, 12%, and 48% Ji-Pei-Jing. The rats treated with 48% Ji-Pei-Jing had significantly lesser ovary weight/b.w. ratio on day 30, too. The rats treated with Ji-Pei-Jing could normally ovulate at the first estrus, and no significant differences were observed during estrous cycles. The effects of PCE on serum levels of E2, P, LH in 30-day-old rats and FSH in 28-day-old rats were elevated significantly by 3% Ji-Pei-Jing treatment. It appears that the effects of PCE result from interaction of contained complex physiologically active substances. Steroids, especially estradio-17 beta, possibly play a key role, and polypeptide hormones may also exert important effects.

Animals↗
PubMed1986

A quantitative study of Sertoli cell and germ cell populations as related to sexual development and aging in the stallion.

Testes from 47 stallions, 1-20 yr of age, were used to examine the influence of age on Sertoli and germ cell populations as well as on functional activity of Sertoli cells. For these stallions, the number of Sertoli cells per paired testes declined linearly with age, and was only 41.7% as great at age 20 as at age 2. However, development of reproductive organs proceeded until age 12-13, as evident from increases in paired testes weight and quantitative rates of spermatozoal production. Although the absolute number of Sertoli cells declined during this period of development, individual Sertoli cells displayed a remarkable capacity to accommodate greater numbers of developing germ cells. Between age 2 and age 12, the mean numbers of developing spermatogonia, young primary spermatocytes, old primary spermatocytes, and round spermatids supported by each Sertoli cell at Stage I of spermatogenesis increased by 49, 176, 153, and 161%, respectively.

Aging↗