Period Of Sexual Maturation Research Articles

European Regulatory Authorities and Pediatric Labeling

### The Need for Medicinal Product Testing in Children #### Ethical Considerations Children should not be given medicines that have not been evaluated adequately for use in that age group. There is a responsibility, shared by applicants and the appropriate authorities, to ensure that children have timely access to safe and effective medicines that have accurate, scientifically justified prescribing information. Applicants are encouraged to investigate the safety and efficacy of a product in children, if it is likely to be of therapeutic benefit in this age-group, and to develop suitable formulation, even if use is likely to be small. However important a clinical trial may be to prove or disprove the value of a treatment, individual members of one or both of the groups—subject or control—can suffer injury as a result of inclusion in the trial, even if the whole community benefits. As with adults who participate in clinical trials and who understand the issues involved in giving their informed consent, consent should be obtained from the legal guardian of children in accordance with national legislation. Children should be fully informed about the trial in language and terms they understand and, if able, should personally sign and date the written informed consent. The child should be made aware of his/her rights to decline to participate. The child's wish to be withdrawn from a study must be respected. These measures should be applied in conjunction with 1) part 4 of Directive 75/318/EEC, as amended, which requires “… details concerning patients who may be at increased risk”; the CPMP/ICH guideline for good clinical practice; and 3) the CPMP guideline on biostatistical methodology in clinical trials in applications for marketing authorizations for medicinal products. These measures are intended to assist applicants with specific problems presented by medicinal product testing in children. The child should stand to obtain some direct benefit from the clinical trial, except … Address correspondence to Elisabeth Autret, MD, Hopital Bretonneau, Pharmacologie Clinique, Boulevard Tonnele, 37044 Tours, France.

Effects of body weight and feed allocation during sexual maturation in broiler breeder hens. 2. Ovarian morphology and plasma hormone profiles

The effects of broiler breeder BW and nutrient intake on ovary morphology and plasma reproductive hormone profiles were examined at photostimulation (PS) (21 wk) and at sexual maturity (SM) in standard (STD) and low (LOW), or high (HIGH) BW birds provided either restricted (RF) or ad libitum (AL) access to feed between PS and SM. At PS, 30 Shaver Starbro pullets at target BW were assigned to the STD treatment, and birds either 20% heavier (HIGH) or lighter (LOW) assigned accordingly. Ten birds of each size group were processed immediately for carcass analysis and 10 birds assigned to each size by feed interaction group. Blood samples were taken at 3-d intervals beginning at PS and profiles constructed for estradiol-17beta, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) to examine the relationship between body size, feeding level, and reproduction. Birds were processed for assessment of reproductive traits following SM. The AL birds reached SM with 11.0 large yellow follicles (LYF) (> 10 mm diameter) compared to 7.1 in RF birds. Small follicle atresia (< 5 mm diameter) was low in AL birds (10.3) compared to RF birds (32.3). The extent of small follicle atresia in RF birds was found to be inversely proportional to LYF number by stepwise regression. Increased small follicle atresia was associated with a longer sexual maturation period in RF birds (r = 0.619; P = 0.0003). Plasma estradiol-17beta concentration was greater in HIGH than in STD or LOW birds at PS, suggesting more advanced ovary development in HIGH birds. Estradiol-17beta profiles were similar in shape in all treatments, with the primary difference being the length of time prior to a substantial estradiol-17beta increase. Following PS, plasma LH and FSH concentrations of AL birds increased to levels nearly double that of RF birds, indicating a role for nutrient intake with rate of reproductive development. Plasma LH and FSH concentrations remained elevated for a greater time period in RF birds, however, possibly relating to the development of processes limiting LYF recruitment. This experiment demonstrated a modulation of reproductive hormone concentrations during sexual maturation by feeding level in conjunction with a sensitivity of the ovary to nutritional effects.

Ontogeny of Differential Migration and Sexual Segregation in Northern Elephant Seals

Adult northern elephant seals ( Mirounga angustirostris ) are substantially sexually dimorphic in size and in migratory behavior. Both sexes migrate over vast areas of the North Pacific Ocean during biannual migrations between rookeries in California waters and northern foraging grounds, but adult males segregate from adult females during each of these double migrations. I used satellite-linked radiotelemetry to document the ontogeny of differential migration and sexual segregation as a means to better define the ultimate causal mechanisms of these patterns and to evaluate the potential influence of this sexually dimorphic trait on the magnitude of size dimorphism between sexes in the northern elephant seal. The initial direction of migration (northwesterly from rookeries) was established during the 1st year of life in both males and females. Differential migration and sexual segregation appears to develop during puberty, when growth rates of males are substantially greater than those of females, and those patterns are well established by the time males are 4.5–5 years old. This outcome suggests that the development and proximate cause of sexual segregation of northern elephant seals is more precisely related to differential metabolic needs of males during the period of sexual maturation and accelerated growth rather than to sexual differences in gross energy requirements of adults. Segregation appears to confer to pubescent males survival benefits, which more than compensate for the higher mortality that generally is associated with rapid growth during puberty in other taxa with male-biased, sexual dimorphism. The most parsimonious explanation for the evolution of sexual dimorphism in size in northern elephant seals still appears to be sexual selection (intrasexual competition) acting through differential mating success of males. Moreover, differential, rapid growth during puberty and deferred maturity of males versus females are proximate mechanisms promoting larger size of males as adults. I suggest, however, that natural selection has led to sexually dimorphic migratory patterns and segregation of foraging elephant seals and that the segregation may partially maintain and, indeed, enhance sexual dimorphism in size.

Environmental Effects on Agonistic Interactions between Males of the Cockroach Nauphoeta cinerea

AbstractThe effects of different environments on the agonistic behavior of males of the cockroach, Nauphoeta cinerea were investigated. We compared the social interactions between pairs of males that had been reared during the period of sexual maturation, when social behavior develops, under one of four environmental treatments: (1) control (28°C with ad libitum food and water) (2) heat stress (35°C, ad libitum food and water) (3) water deprivation (28°C), or (4) food and water deprivation (28°C). Different environments affected the structure of the interactions between males and the behavior of both dominant and subordinate individuals. The mean number of agonistic acts per minute was similar for all treatment groups except the water‐deprived group, which was significantly lower. Water‐deprived, food‐ and water‐deprived, and heat‐stress rearing conditions reduced the stability of agonistic interactions relative to the control group. When reared under stressful conditions, dominant‐scored males decreased the number of aggressive acts and increased the number of submissive acts, and subordinate‐scored males decreased the number of submissive acts and increased the number of aggressive acts. Thus, stressful environmental conditions can disrupt agonistic interactions and cause both dominant and subordinate male N. cinerea to adopt different behavioral strategies during male‐male competition.

Reproductive Behavior of Thyanta pallidovirens (Heteroptera: Pentatomidae)

Reproductive behavior of the stink bug Thyanta pallidovirens (Stal) was studied in the laboratory, including the determination of the sexual maturation period for both sexes, the effects of the number of copulations on fecundity, and the function of prolonged copulation. Mean premating periods for males and females were 3.6 ± 0.5 and 4.1 ± 0.6 d, respectively. Preoviposition period averaged 6.6 ± 0.9 d. Females preferred sheltered, roughtextured oviposition sites. Paired adults mated ≈13 times on average during their lifespan under laboratory conditions. The mean duration of copulations involving virgin females was >17 h, significantly longer than that of subsequent copulations, which lasted between 6.9 and 8.3 h. Multiple matings significantly increased female fecundity. Virgin males donated ≈17% of their body mass to a virgin female during mating. Duration of mating may be regulated by space available in the spermatheca for ejaculatory material. There was strong evidence of male mate choice, with males terminating copulation with small females before sperm was transferred. There was no indication of male mate-guarding behavior after copulation. Females almost always approached males from distances of >30 cm, suggesting that males attract females from a distance. Within 15 cm, males discern and approach females. Courtship behaviors of males included antennation of female antennae and abdomens, stroking the abdomens with the hind legs, and periodic male abdominal vibrations. Possible functions of these behaviors are discussed.

Seasonal cycles in total chemical composition of two Lake Baikal benthic‐pelagic sculpins (Cottocomephorus, Cottoidei)

Annual cycles in chemical composition of the body, liver, gonads, red and white muscles were determined for two medium fat sculpins, Cottocomephorus grewingki and C. inermis, endemic to Lake Baikal. Their total lipid content ranged from 3 to 9% during the year. The content of defatted dry substance was 14–17%, similar to the protein content of the other Baikalian cottoid fishes. The prespawning period was characterized by a positive lipid and protein balance in both species. In C. grewingki the liver performed largely a metabolic function, whereas in C. inermis it served also as a storage site for lipid reserves. During spawning, total body lipids of females of both species showed a two‐ to threefold decrease. Males of C. grewingki guarding nests deplete greatly their total body lipids, which decrease seven‐ to ninefold by the time of larval hatching in comparison with the prespawning period, and constitute 1–2%. After spawning, lipid reserves of C. grewingki were quickly restored to the initial level (from about 3 to 9%) and maintained during the long sexual maturation period. In C. inermis total body lipids increased only twofold in comparison to those observed during the spawning period.

Opioids regulate cell proliferation in the developing rat uterus: effects during the period of sexual maturation.

The present studies demonstrate, for the first time, that the rate of DNA synthesis in rat uterus of 21-32 days of age is inhibited by opioid peptides [D-Met2, Pro5]enkephalinamide. At around the time of vaginal opening (approximately 33 days) the opioids failed to act. High-affinity nuclear [3H]naloxone binding sites with linear Scatchard plots were detected in the uteri during the opioid-sensitive periods of DNA synthesis. Characteristics of these binding sites and the opioid sensitivity of uterine DNA synthesis are dependent on the age of the animals, the level of circulatory oestradiol and/or the maturity of the nuclear oestrogen receptor system.

Dimensionless Life Histories and Effective Population Size

The effective size (Ne) of a population can be estimated from demographic information. We evaluated a recent model, showing that Ne depends strongly on the relationship between age at reproductive maturity (M) and average adult lifespan (A). Ne converges on half the number of potentially reproducing adults (N/2) as M decreases relative to A, but it increases linearly as M increases for a given value of A. Therefore, convergence of Ne on N/2 is more likely in organisms with a short sexual maturation period scaled to adult lifespan. To assess the generality of this convergence we asked whether most organisms are characterized by this requisite relationship between M and A. The dimensionless number M/A is approximately invariant within taxa, but it is markedly different across taxa. Previous work focused on birds and mammals, taxa with unusually small M/A (0.4 and 0.75). Other animal taxa take longer than most birds and mammals to reach maturity for a given reproductive lifespan, so they are characterized by larger M/A (e.g., fish, 2.0). In theory, these taxon‐specific life histories strongly influence Ne. We conclude that Ne is expected to approach N/2, provided that M/A is (unusually) small, and that Ne/N among poikilotherms may often exceed that of mammals and especially birds.

Chromatic Polymorphism and Geophagy: Two Outstanding Characteristics of Rhammatocerus schistocercoides (Rehn 1906) Grasshoppers in Brazil (Orthoptera, Acrididae, Gomphocerinae)

A study of coloration in #Rhammatocerus schistocercoides# (Rehn 1906) grasshoppers in natural conditions revealed substantial variability, with evidence of a new case of chromatic polymorphism. Green coloration is much more common in this species than previously assumed. The percentage of green adults, or those with a partially green integument,varied seasonally within the same generation according to the phenology and especially the sexual maturity of the population. The most important coloration change occurred in September, during the sexual maturation period, when the grasshopp- ers turned progressively from brown to green or partially green. The present study also highlights evidence of a geophagy phenomenon (consumption of large amounts of soil) that has never before been reported in locusts or grasshoppers. This yet unexplainable behaviour was particularly spectacular in terms of its scale. (Resume d'auteur)

Changes in the Affinity of Estrogen and Androgen Receptors Accompany Changes in Receptor Abundance in Brown and Rainbow Trout

The present study provides new data demonstrating the occurrence of affinity changes in two distinct receptor system, the ER and AR systems, in the brown and rainbow trout during the period of sexual maturation.

Biochemical composition in relation to the energetics of growth and sexual maturation in the ommastrephid squid Illex argentinus

The proximate (protein, lipid, carbohydrate and ash) and elemental (C, H, N and P) composition of the major tissues were measured for 18 male and 51 female Illex argentinus sampled from the feeding grounds over the Patagonian Shelf. In most tissues the chemical composition did not vary with sexual maturity, although the mass of the tissue increased significantly because sexual maturation and growth were proceeding simultaneously. The composition of the ovary and associated tissues (nidamental gland, oviducal gland) did change significantly during sexual maturation. Several tissues contained significant amounts of one or more unknown components. The nitrogen content of an unknown component in the testis was similar to that of DNA. In the spermatophoric complex the nitrogen content suggested the unknown fraction may be an amino acid or short peptide, whereas in the nidamental gland the nitrogen content suggested an amino-sugar or polysaccharide derivative. The digestive gland was rich in lipid and continued to accumulate substantial reserves of energy throughout the period of sexual maturation on the feeding grounds. During this period there was no evidence for the utilization of either digestive gland or mantle tissues to supply energy for gonads. Accumulation of carbon and energy (estimated stoichiometrically from carbon) during the final 50 days on the feeding grounds indicated that energy demands for tissue synthesis in females were almost twice those of the smaller males, and that a relatively small fraction of the demands were for reproductive tissues (5% in males, 15% in females). Most energy intake in this period was directed to the digestive gland (40% in males, 47% in females) and other somatic growth (54% in males, 38% in females). A preliminary power budget suggested that during the final days of feeding before migrating to the spawning grounds, energy intake of Illex argentinus is 4-5% body energy content per day, growth efficiencies are low (17-22%) and that energy reserves in the digestive gland would fuel migration in the absence of feeding for 14 days in males and 21 days in females

Comportement sexuel et stratégie reproductrice chez le Chryseida bennetti Burks (Hymenoptera: Eurytomidae), parasitoïde de la bruche du haricot. I. Effet de l'âge des partenaires

This paper relates a female age effect to the mating behavior of Chryseida bennetti Burks, an ectoparasitoid of the bean weevil (Acanthoscelides obtectus (Say)). The sexual behavior includes rapid courtship and copulation followed by a postmating courtship behavior ("guarding"). Male guarding behavior varies according to the females' age, with males guarding females of 2–3 days old longer than younger and older females. A period of sexual maturation is necessary for most of the males. Females' attractiveness begins at the pupal stage, and their receptivity on emergence. Mated females are still attractive to males. Multiple matings (up to four copulations) with the same male have been observed. The females' age seems to control copulation frequency and the duration of the postmating courtship behavior. Two- and three-day-old females had more successive multiple matings with the same male than the other females did, and males spent much more time guarding them. The age of the males (except from newly emerged males) did not seem to influence copulation frequency. On the other hand, the complexity of the sequential courtship behavior increased with the age of the partners. The function of males' postmating courtship is discussed.

Age-related changes in the secretion of growth hormone in vivo and in vitro in infantile and prepubertal Holstein bull calves

The average concentration of GH in blood is high at birth and declines during the period of sexual maturation in bulls. The objectives of these studies were (1) to define age-related changes in vivo in the pulsatile secretion of GH from birth to puberty, (2) to determine whether pituitary cell content of GH and characteristics of the secretion of GH in vitro reflect age-related changes in vivo, and (3) to examine whether responsiveness to GH-releasing hormone (GHRH) and somatostatin (SRIF) in vitro changed with age in Holstein bull calves. In experiment 1, calves were bled every 15 min for 12 h at < 1, 12 and 42 weeks of age (n = 5/group), these being representative of infantile, juvenile and pubertal stages of development. Calves were killed 3 to 5 days later and the pars distalis of the anterior pituitary gland was enzymatically dispersed into a suspension of single cells. Aliquots of cells were extracted with 0.01 mol NaHCO3/l to determine the content of GH and cultured for 18 and 72 h. As expected, the average concentration of GH in plasma decreased with age (P < 0.001). The initial decrease in GH was caused by a reduction in the baseline concentration between birth and 12 weeks of age. There was a marked decrease in GH pulse amplitude between 12 and 42 weeks of age and a further reduction in the baseline concentration. In contrast, the pulse frequency of GH increased (P < 0.05) from < 1 week to 12-weeks of age and remained constant thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein metabolism during sexual maturation in female Atlantic salmon (Salmo salar L)

Body composition and fractional rates of protein synthesis (percentage of the protein mass synthesized per day) were determined in female Atlantic salmon returning to the River Tay, Scotland in July and in October after a 95 day period without food, during which time the animals became sexually mature. During the 95 day period of starvation/sexual maturation the ventricle and red muscle remained as a constant proportion of fresh weight whereas the liver, gill and ovary increased and the stomach and white muscle decreased. Fractional rates of protein synthesis increased markedly in the liver, stomach and ovary during the period of starvation/sexual maturation. In the gill, ventricle and white muscle fractional protein synthesis rates increased slightly or remained constant. From the estimated rates of protein loss or gain in the various tissues it is concluded that there is considerable protein turnover and repartitioning of amino acids during the period of starvation and sexual maturation. The absolute rate of protein synthesis rates in the ovary indicates that this tissue made the largest contribution to the energy and amino acid demands of the fish, whilst most of the amino acids required for maturation of the ovary were derived from white muscle, principally as the result of increased muscle protein degradation.

The period of sexual maturation and the age at mating in Iridomyrmex humilis, an ant with intranidal mating

The process of sexual maturation was studied in the ant Iridomyrmex humilis. Spermatogenesis starts during the pupal stage and sperm is transferred to the seminal vesicles during the first four days after emergence. The testes start to degenerate early in the pupal stage and totally shrivel up during the first days after emergence. Males therefore have a fixed amount of sperm. Both males and females reach sexual maturity only 2–3 days after emergence; some of them mate as early as the first day after emergence. Overall, it appears that the length of time needed to reach sexual maturity in ants is highly correlated with the mode of colony founding. The maturation period is much longer in those species in which young queens initiate colonies without the help of workers (independent founding) than in those where young queens need the help of workers (dependent founding). This is probably associated with the fact that independent founding queens require large amounts of energy reserves in order to found colonies; these energy reserves are accumulated after emergence. In contrast, dependent founding queens do not accumulate as many energy reserves and are therefore sexually receptive at a younger age.

Induced Abortion Among Unmarried Women in Shanghai, China

In 1988-1989 researchers analyzed data on 15178 induced abortions among 15-29 year old single women from 5 districts of Shanghai China to determine trends in abortion among single women. They also looked at medical records at Hua-chuan General Hospital in Shanghai to learn the percentage of single women who experienced late abortions. The highest abortion rate was among 20-24 year old women (]59) followed by 25-29 year old women (94) and 15-19 year old women (56). In fact 21 year olds experienced the most abortions (182.7) and 15 year olds the least (0). Among teenagers the rate stood 57% higher in the rural districts than the urban districts (72.2 vs. 45.9). Further abortion rates rose rapidly in the rural districts with age peaking at 20 years (264.1) then fell sharply to 23 among 28 year olds. On the hand the increase was more gradual among urban women and peaked at 21 (224.9) and the ensuing fall was more steady and was higher than rural areas. In 1982 in the 3 urban districts 14% of abortions occurred in single women. By 1986 it increased to 28%. It fell slightly to 25% in 1988. These corresponding figures for the rural districts were 14% 20% and 24%. Between 1982-1988 the abortion rate of 15-19 year olds rose from 5-56. Further abortion rates among 20-24 year olds and 30-34 year olds rose 4 times and among 25-29 year olds more than twice. 43% of all 2nd and 3rd trimester abortions occurred in unmarried women in 1982 by 1988 this figure soared to 63%. This indicated that single women were more likely to obtain an abortion late in their pregnancies than married women. The Chinese family planning program encourages women to delay marriage until age 23 and improved health and nutrition have reduced the age of menarche thus leaving women a longer period of sexual maturity. This coupled with the fact that cultural mores stress sexual abstinence outside of marriage and premarital pregnancy brings shame the considerable abortion rate among single women in Shanghai was not surprising.

Curvas de maturação gonadal e crescimento de fêmeas de Saguiru prata, (Steindachnerina insculpra Fernandez - Yepez, 1948), capturadas na Represa de Ibitinga, Estado de São Paulo, Brasil

O objetivo deste trabalho foi determinar em que comprimento e idade ocorre a primeira maturação sexual de fêmeas de Saguiru prata Steindachnerinainsculpia, na Represa de Ibitinga (21046'S 48059'W). Os valores encontrados através da curva de maturação, ajustados pela equação de von Bertalanffy, foram: Loo= 143,5 mm e K = 0,381. A primeira maturação sexualdá-se com um comprimento total médio de 97,73 mm, aos 3 anos de idade.

Longitudinal Study of Serum Cholesterol, Apolipoproteins and Sex Hormones During Puberty

In order to determine the age and sex dependency of some of the major risk factors for coronary heart disease during the period of sexual maturation a five-year longitudinal study was carried out on 105 boys and 133 girls living in Plzen, Czechoslovakia. Serum cholesterol was significantly elevated in 13-year-old girls (p less than 0.01), while no statistically significant sex-related differences in total and lipoprotein cholesterol and apolipoprotein A-I and apolipoprotein B levels were found in other age groups during the period of follow-up. In boys the total cholesterol showed a constant and statistically significant decrease (p less than 0.01) between the ages 11 to 13 years, but tended to rise during the last two years of study. In girls, serum cholesterol decreased significantly between the ages 11 to 15 years (p less than 0.05). A statistically significant decrease in pre-beta cholesterol was found in girls during puberty (p less than 0.05). The changes in beta lipoprotein cholesterol were similar to those for total cholesterol. The apolipoprotein A-I concentration decreased significantly between 11 and 15 years in boys (p less than 0.05), while it underwent no substantial change in girls. The apolipoprotein B level decreased permanently and significantly (p less than 0.05) during the 5-year period in girls. In boys, the concentration of this protein decreased between 11 and 14 years and increased during the 15th year when a value significantly higher than that for girls was attained (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Seasonal and sex-linked variations in hepatic and extrahepatic biotransformation activities in striped mullet ( Mullus barbatus)

Microsomal cytochrome P450 content, NADPH-cytochrome c reductase, and phase I (ethoxycoumarin and ethoxyresorufin O-dealkylases) and phase II (glutathione S-transferase and UDP-glucuronyltransferase) activities were studied in the liver and intestine of the striped mullet ( Mullus barbatus) for 8 months (before and during sexual maturation). Biotransformation activities were much lower in extrahepatic tissues than the corresponding activities in the liver. Intestinal and hepatic biotransformation activities presented similar seasonal fluctuations: Phase I activity increased from October to February (during water cooling) and generally decreased before spawning; Phase II activity was not greatly different. Moreover, NADPH-cytochrome c reductase, ethoxyresorufin O-dealkylase, and glutathione S-transferase activities were measured in the kidney during the sexual maturation period. Renal phase I and phase II activities showed very little fluctuation during the 5 months studied. Cytochrome P450 and ethoxycoumarin and ethoxyresorufin O-dealkylases exhibited sex-linked differences during sexual maturation, whatever the tissue: in the liver the values are higher in male fish, whereas in the intestine and kidney they are lower.

Mechanisms involved in parasitic castration: In vitro effects of the trematode Prosorhynchus squamatus on the gametogenesis and the nutrient storage metabolism of the marine bivalve mollusc Mytilus edulis

The mechanisms involved in the parasitic castration of the marine mussel Mytilus edulis by the trematode parasite Prosorhynchus squamatus Odhner, 1905, have been investigated in vitro with two bioassays employing dissociated host tissues. There is no conclusive evidence that P. squamatus affects the secretion of two host neuroendocrine factors, viz., gonial mitosis-stimulating factor and glycogen mobilization hormone, involved in the gametogenesis/nutrient storage cycles of the mussel. In contrast, extracts of P. squamatus sporocysts and cercariae significantly stimulated glycogen mobilization in host glycogen cells and strongly inhibited host gonial mitosis. A gonial mitosis-inhibiting factor (GMIF) was found in the hemolymph of parasitized mussels. The existence of an endogenous GMIF in mantle tissue of uninfected mussels has been demonstrated. This factor appeared to be secreted into the hemolymph during the period of sexual maturity. Whether the parasite acts directly on the host gonia, or by provoking the liberation of this endogenous GMIF, has yet to be ascertained. It would appear, however, that the parasite acts directly on host glycogen cells.