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At least 217 records · Page 12Linked to original sources

PubMed1987

Reproductive effects of four phthalic acid esters in the mouse.

These studies compared the reproductive toxicity of four phthalates by a continuous breeding protocol. Mice were given diets with diethyl phthalate (DEP) (0.0, 0.25, 1.25, or 2.5%), di-n-butyl phthalate (DBP) (0.0, 0.03, 0.3, or 1.0%), di-n-hexyl phthalate (DHP) (0.0, 0.3, 0.6, or 1.2%), or di(2-ethylhexyl) phthalate (DEHP) (0.0, 0.01, 0.1, or 0.3%). Both male and female CD-1 mice were dosed for 7 days prior to and during a 98-day cohabitation period. Reproductive function was evaluated during the cohabitation period by measuring the numbers of litters per pair and of live pups per litter, pup weight, and offspring survival. There was no apparent effect on reproductive function in the animals exposed to DEP, despite significant effects on body weight gain and liver weight. DBP exposure resulted in a reduction in the numbers of litters per pair and of live pups per litter and in the proportion of pups born alive at the 1.0% amount, but not at lower dose levels. A crossover mating trial demonstrated that female mice, but not males, were affected by DBP, as shown by significant decreases in the percentage of fertile pairs, the number of live pups per litter, the proportion of pups born alive, and live pup weight. DHP in the diet resulted in dose-related adverse effects on the numbers of litters per pair and of live pups per litter and proportion of pups born alive at 0.3, 0.6, and 1.2% DHP in the diet. A crossover mating study demonstrated that both sexes were affected. DEHP (at 0.1 and 0.3%) caused dose-dependent decreases in fertility and in the number and the proportion of pups born alive. A crossover mating trial showed that both sexes were affected by exposure to DEHP. These data demonstrate the ability of the continuous breeding protocol to discriminate the qualitative and quantitative reproductive effects of the more and less active congeners as well as the large differences in reproductive toxicity attributable to subtle changes in the alkyl substitution of phthalate esters.

Animals↗

PubMed1993

Seasonal changes in plasma levels of steroid hormones in an asynchronous fish the gudgeon Gobio gobio L. (Teleostei, Cyprinidae).

Annual changes in plasma of estradiol-17 beta, testosterone, and 17,20 beta-dihydroxy-4-pregnen-3-one concentrations were measured, by radioimmunoassay, in female gudgeon Gobio gobio a fish which has an asynchronous-type ovary containing oocytes at various stages of development and spawns several times during the reproductive period. The gonadosomatic index and the relation between stages of maturity and steroid concentrations were also followed during the reproductive cycle. Plasma levels of estradiol-17 beta, testosterone, and 17,20 beta-dihydroxy-4-pregnen-3-one were low from October to April and increased rapidly in May to reach 0.61 +/- 0.31; 2.3 +/- 0.42; and 3.17 +/- 0.68 ng/ml, respectively. Elevated levels were maintained during spawning when vitellogenic oocytes are present alongside oocytes in final maturation. Histological analysis of the ovary indicated that an important number of spawnings has occurred since the proportion of oocytes in final maturation stage was very low (less than 1%). Fish in the regressive phase also presented high steroid levels. The vitellogenic oocytes in preovulatory atresia and the postovulatory follicles may be responsible for these events.

Animals↗

PubMed1987

Reproductive outcome after fimbrial evacuation of tubal pregnancy.

Thirty-one ectopic pregnancies were manually expressed (i.e., "milked out") by the tubal fimbria during a 13-year period. Reproductive histories and operative findings were unremarkable when compared with the general population with ectopic gestation. The subsequent reproductive performance was evaluated in 27 patients who attempted conception. Twenty-five (92%) of the 27 patients subsequently conceived, 23 (85%) had at least one successful term pregnancy, and the remaining 2 (7%) had abortions only. There was no repeat ectopic pregnancy. Average follow-up time was 38.5 months. Previous experience with this technique has been disappointing with low postoperative rates of successful term pregnancies. Favorable outcomes after fimbrial expression have been reported only in small numbers of patients. It is suggested that the procedure is appropriate for distal tubal gestations that are loosely adherent within the tubal lumen; these are usually expressed with minimal efforts. However, if the gestational mass does not yield to gentle milking of the tube or evacuation has been incomplete, the surgeon can always use a linear salpingotomy. More experience is obviously needed to verify these preliminary results, suggesting that fimbrial evacuation is simple, safe, and advantageous in properly selected cases.

Adult↗

PubMed2005

Deficit in reproduction in polygynously mated females of the monogamous mound-building mouse Mus spicilegus.

In monogamous mound-building mice Mus spicilegus, facultative polygyny was observed in April, at the beginning of the reproductive season. In order to evaluate the cost of polygyny, we compared, under laboratory conditions, the reproductive success of trios and pairs composed of sister females mated with unrelated brother males. Females in trios were able to tolerate each other during the reproductive period and to reproduce with the same male under spatial constraints. Nevertheless, polygyny had a strong negative effect on the reproductive success of the females. The average number of young per litter was smaller in trio females than in paired females, whereas the interval between two successive litters was higher. As a result, the number of litters and the number of young per time unit were smaller in each of the trio females compared with paired females. Agonistic behaviour being absent in trios, our results strongly suggest that living in trios led to pheromonal production that affected the female physiological state and reproduction. Males of trios did not obtain a better reproductive success than males in pairs.

Animals↗

PubMed1998

Timing of menopause, reproductive years, and bone mineral density: a cross-sectional study of postmenopausal Japanese women.

Age at menopause has been found to be associated positively with bone mineral density, and age at menarche has been found to be associated negatively with bone mineral density. However, there have been few studies on the relations of timing of menopause and length of the reproductive period with bone mineral density. The purpose of this study was to examine the relations of timing of menopause and reproductive years (calculated as age at menopause minus age at menarche) with mineral density of the second metacarpal bone in postmenopausal Japanese women. The study population consisted of 1,035 naturally menopausal women aged 40-70 years who were screened in 1996-1997. Using computed x-ray densitometry, the authors measured bone mineral density by analyzing radiographic films of the right second metacarpal bone. Using the women with early menopause (age < 49 years) as the reference group and adjusting for age, subjects with late menopause were at decreased risk for low bone mineral density (odds ratio (OR) = 0.69, 95% confidence interval (CI) 0.49-0.97). After adjustment for additional covariates (grip strength, physical activity, body mass index, smoking, and calcium intake), the association was unchanged (OR = 0.70, 95% CI 0.50-0.99). Postmenopausal women with more reproductive years (> or = 40 years) were at decreased risk for low bone mineral density compared with those with fewer reproductive years, after adjustment for age (OR = 0.73, 95% CI 0.40-1.30) and potentially confounding factors (OR = 0.76, 95% CI 0.41-1.37); the p-value for trend was not statistically significant. In multiple linear regression analysis, early menopause and fewer reproductive years were independent predictors of low bone mineral density. In this study, postmenopausal Japanese women who had a late menopause and more reproductive years were at decreased risk for low bone mineral density, and may therefore be less prone to osteoporosis.

Adult↗

PubMed1999

Influence of family tradition on reproductive behavior of Gypsy population.

INTRODUCTION: Stability of traditional opinion in different ethnic communities determines to a great degree the demographic behavior of their members. AIM: To analyze the influence of family traditions and system of values on the reproduction of gypsy population. MATERIALS AND METHODS: The opinions of 495 Gypsy women in reproductive age was studied by direct individual questionnaire. The answers characterizing the reproductive behavior of two successive generations were analyzed. The following statistical analyzes were applied: descriptive statistics, chi-square and t-tests. All p-values are two-tailed. The statistical analyses were made on a PC using SPSS 5.0.2. RESULTS: Mean age at marriage in different generations under study was similar (it is 15.50 +/- 0.10 years in the present generation vs. 15.58 +/- 0.09 years in the previous generation, p > 0.05). The same is valid for the mean age at the first birth (16.98 +/- 0.11 years vs. 17.04 +/- 0.10 years, respectively, p > 0.05). However, there was a statistically significant difference in the mean number of live-births between the generations (2.37 +/- 0.05 vs. 4.10 +/- 0.09, respectively, p < 0.001). The latter finding might be explained by fact that the women from the present generation are still in their reproductive period. CONCLUSION: It is obvious that family traditions may have, to a certain extent, an influence on the patterns of reproductive behavior in gypsy population. These traditions represent an indispensable part of their lifestyle and their intentions to have many children.

Adult↗

PubMed2006

[Survey of the cycle of reproduction of red algae Gelidium sesquipedale (Turner) Thuret (case of the maritime zone of El Jadida-Jarf lasfer of Morocco)].

The industrial exploitation of the agarophyte, Gelidium sesquipedale, is an important part of the economy of Morocco, however the species is in danger of being overexploited. The development of research on the biological cycle of the species enbles a better understanding of environmental influencies on its reproduction periods and of the effect of pulling up on the growth of the thalli. This should assist in helping to avoid excessive collection of the species and to reinforce a period of rest where no collection takes place. The major are of collection supplying industries is the maritime sector of El Jadida - Jarf Lasfar. In order to study the methods of reproduction of G sesquipedale, a first series of experimentation was carried out by the INRH. Studies relating to biology and the effect of pulling up on the biometrics of the thalli of this species were carried out at two stations of the maritime zone El Jadida - Jarf lasfar: Moulay Abdellah and Sidi Bouzid during the period 2000-2002. The results obtained show that the fertile thalli are present all the year with a maximum reproductive activity in winter. The recruitment of the young slings takes place before the winter and occurs more in Sidi Bouzid. The regeneration and the growth of the thalli are carried out in spring and summer. To preserve this resource, it is necessary to put in place a system whereby one zone or area is allowed to rest whilst another area is cultivated for a year; whilst in the following year the rercise occurs.

Morocco↗

PubMed2003

Modeling biological invasions into periodically fragmented environments.

Range expansion of a single species in a regularly striped environment is studied by using an extended Fisher model, in which the rates of diffusion and reproduction periodically fluctuate between favorable and unfavorable habitats. The model is analyzed for two initial conditions: the initial population density is concentrated on a straight line or at the origin. For each case, we derive a mathematical formula which characterizes the spatio-temporal pattern of range expansion. When initial distribution starts from a straight line, it evolves to a traveling periodic wave (TPW), whose frontal speed is analytically determinable. When the range starts from the origin, it tends to expand radially at a constant average speed in each direction (ray speed) keeping its frontal envelope in a similar shape. By examining the relation between the ray speed and the TPW speed, we derive the ray speed in a parametric form, from which the envelope of the expanding range can be predicted. Thus we analyze how the pattern and speed of the range expansion are affected by the pattern and scale of fragmentation, and the qualities of favorable and unfavorable habitats. The major results include: (1). The envelope of the expanding range show a variety of patterns, nearly circular, oval-like, spindle-like, depending on parameter values; (2). All these patterns are elongated in the direction of stripes; (3). When the scale of fragmentation is enlarged without changing the relative spatial pattern, the ray speed in any direction increases, i.e., the rate of range expansion increases.

Algorithms↗

PubMed2006

Partial development of the steroidogenic ultrastructural features in degenerative corpora lutea after a single injection of pituitary extract in the Western painted turtle (Chrysemys picta).

Pituitary glands were removed from sexually mature female turtles (Chrysemys picta) and they were injected intraperitoneally (i.p.) into other mature females of the same species (experimental). In addition mature females of the same species received saline injection only (controls). Initially all the turtles used in this study were steroidogenically inactive with corpora lutea already undergoing luteolysis (degeneration) as these turtles had ovioposited their eggs approximately 2 weeks earlier. Forty-eight hour post injection the corpora lutea were removed from the control and experimental turtles. In the experimental turtles, the lutein granulosa cells developed ultrastructural features such as tubular and cisternal smooth endoplasmic reticulum (SER) and mitochondria with tubular cristae associated with lipid droplets. However, the controls maintained degenerative corpora lutea without steroidogenic ultrastructural features. The circulating progesterone (Pro) levels in the experimental turtles were significantly higher than the controls (P<0.049). Although the 48h development of steroidogenic ultrastructural features in the lutein granulosa cells was only partial in development, the effect of the pituitary taken from the inactive donor triggered an activating process within a short period, clear evidence of gonadotropic effect on the inactive corpora lutea. The present data offer interesting information on the short-term effect of gonadotropins during the non-reproductive period. This information may have useful implication under natural conditions particularly during the onset of a new reproductive cycle where the ovary is still inactive.

Animals↗

PubMed1978

Sexual maturity in broiler breeder males.

Sexual maturity and fertility of two lines of broiler breeder males, one commercial and one experimental, were evaluated individually in order to determine the earliest age at which they could be expected to produce viable spermatozoa capable of producing acceptable fertility. Comparative data for the two lines were also collected on duration of fertility, percent fertility, percent hatchability and chicks per hen during an 8-week period using pooled semen from each of the two lines. The results of this study indicate that 9.1 and 6.8% of the male of the experimental and commercial lines, respectively, produce viable spermatozoa at 11 weeks of age, and consequently, could be selected at that age and used to reproduce stock under selection. The duration of fertility was 10.5 days for the experimental line and 8.8 days for the commercial lines; with fertility levels of 86.1 and 82.8%, respectively, for the eggs produced by the two lines during this period. There were no differences in fertility, hatchability, or chicks produce per hen between the two lines for the 8-week reproductive period.

Age Factors↗

PubMed1995

Histochemical analysis of lizard testicular glycoconjugates during the annual spermatogenetic cycle.

The distribution of glycoconjugates in the testis of lizard Podarcis s. campestris De Betta was investigated by HRP-conjugated lectins during the annual spermatogenetic cycle. In addition, pretreatments of sections with neuraminidase and removal of alkali-labile O-linked sequences by beta-elimination allowed the structure of glycoconjugates to be further explored. Leydig cells displayed changes of lectin-binding sites during annual cycle, and during the abortive spermatogenesis period lacked N-linked sialylgalactosyl glycans. Sertoli cells stained by Con A, WGA, RCA120, BS I-B4, showed, except in July, O-linked sialylgalactosyl glycans. Spermatogonia bound Con A and WGA. Spermatocytes bound also BS I-B4, SBA, UEA I, and during spring spermatogenesis, revealed O-linked sialylgalactosyl glycans. The acrosomes of spermatids were also stained by RCA120 and PNA, whereas the heads of spermatozoa did not bind SBA and PNA. During the abortive spermatogenic period, the acrosomes showed O-linked sialylgalactosyl glycans and N-linked glycans terminating in beta-galactosyl residues. During the reproductive period, the acrosomes of spermatozoa expressed O- and N-linked sialylgalactosyl glycans and beta-galactosyl terminal residues on O- and N-linked glycans. This, in the testis of lizard, the two spermatogenesis periods show the emergence of different types of glycosylation.

Acrosome↗

PubMed1982

The effect of temperature and of dietary restriction on lifespan and reproduction in the rotifer Asplanchna brightwelli.

In this study, the effects of different environmental temperatures and of dietary restriction on the lifespan, reproductive cycle, and fecundity of the rotifer Asplanchna brightwelli were examined. When temperature effects were analyzed, it was observed that the mean lifespan and the times at which the reproductive cycle started and ended all increased as environmental temperatures decreased. When dietary restriction was imposed by increasing the interval between feeding times from 12 to 36 hours, there was an increase both in the mean lifespan and in the length of the reproductive period in this rotifer.

Animals↗

PubMed2002

Component community of larval trematodes in the mudsnail Hydrobia ventrosa: temporal variations in prevalence in relation to host life history.

Temporal variations in the prevalence of larval trematodes in the short-lived prosobranch mudsnail Hydrobia ventrosa (Montagu) were investigated in relation to host life history and season for 4 successive years in temperate windflats of the southern Baltic Sea. The component community of trematode larvae in H. ventrosa comprises at least 10 species; families (and species) represented include Notocotylidae (1), Echinostomatidae (1 or 2), Heterophyidae (2), Monorchidae (1), Microphallidae (3 or 4), Psilostomatidae (1), and Hemiuridae (1). The notocotylid Paramonostomum alveatum was the most prevalent species, followed by the microphallids Maritrema subdolum and Microphallus sp. Trematode prevalence in H. ventrosa fluctuated seasonally. Prevalence usually peaked in summer between July and September-October and decreased in late winter-early spring. This seasonal change is chiefly explained by the life history patterns of the semelparous snail host. Hydrobia ventrosa has a maximum life span of about 2 yr and reproduces between June and November of its second calendar year. The first trematode infections appeared annually in May when the most abundant cohort of H. ventrosa, the second-calendar-year snails, mature. The prevalence continued to increase until August-September, throughout the reproductive period of the second-calendar-year snails, Prevalence decreased during winter, when most of the second-calendar-year snails died after reproduction. On the basis of longterm laboratory experiments, it has been shown that the late autumn-winter mortality was not the result of trematode infections. Seasonal patterns of prevalence were similar among the trematode species except for the monorchid Asymphylodora demeli, the only one using fish definitive hosts. Species-specific differences in the seasonal occurrence of prepatent infections and the predominance of certain larval stages in winter are interpreted as different strategies of the trematode species to survive the harsh winter conditions, or to survive the death of the first intermediate host in autumn-winter, or both.

Animals↗

PubMed2002

Quantitative analysis of carbon balance for reproduction in woody species.

The carbon balance in reproductive organs over the whole reproductive period was estimated for 20 woody species on the basis of the published data on the final dry weight and CO(2) exchange of reproductive organs. The relationship between net respiration and dry weight growth was formulated by a linear function with a negative y-intercept. From this linear relationship, linear relations of dry weight growth and net respiration to net translocation were derived. The size dependence of net respiration showed that the net respiration changed from negative to positive as the final dry weight of the reproductive organ exceeded 0.481 g. The cost for translocation per unit dry weight was much lower in the species with small reproductive organs (<0.481 g) because of their photosynthetic contribution to the weight growth. The relation of dry weight growth/net translocation ratio to net translocation was expressed as a hyperbolic function. The dry weight growth/net translocation ratio remained at 0.650, in the higher range of net translocation, irrespective of woody species.

Journal Article↗

PubMed2003

Major life-history transitions by deterministic directional natural selection.

For large-scale evolution on Earth there has been a directional change where simple self-replicators evolved into large organisms with high metabolic rates and long pre-reproductive periods. Associated with this increase there have been major life-history transitions from asomatic, non-senescing, haploid, and asexually reproducing organisms to somatic, senescing, diploid, and sexually reproducing organisms with male and female individuals. Using a game theoretical model, it is shown that this trajectory can be explained by deterministic natural selection as it arises from first principles of the self-replication process in mobile organisms. It is shown (i) that selection for an increase in the energetic state of the organism puts a direction to evolution, (ii) that selection by density-dependent competitive interactions can explain the major life-history transitions as a function of the energetic state of the organism, and (iii) that the two selection processes combined can explain an exponentially increasing body mass. It is also shown (iv) why, for the case with an increasing body mass, we may expect many life histories to evolve in accordance with the exponents of the body mass allometries, (v) that an upper constraint on the body mass and metabolic rate can induce an additional transition into eusocial communities, and (vi) that the evolutionary trajectory is likely reversible with backward evolution during periods of environmental crises.

Animals↗

PubMed2006

[What is the future of our genome?].

Where do we go and what will happen with our genomes? Viewed as a reflection of what we know about our origin as Homo sapiens, history and forecast. Archeogenetics tries to find our sourcing place and to explain how humans occupied the globe. One of the first theories based on mtDNA polymorphisms@ studies stressed on our African origin followed by stepwise dispersal all over the world which took approximately 80,000 years. But not all findings agreed with this assumption if based on nuclear loci and supported multifocal origin of humans. The process of establishing a new species--Homo sapiens, is still not fully understood and many questions remained unanswered. From the point of view of population genetics we can assume that: 1. Mutability (natural or from internal causes) does not change though we cannot neglect suspicion that environment could influence its increase. The content of harming mutations in our genome, due to the protective effect of health care, which blocks natural selection, is increasing and moreover changes of our life style opened the door for manifestation of week deleterious alleles accumulated during foregoing period of evolution. Also prolongation of our life span is accompanied with effects of genotypes positively selected because of their positive effect on our reproductive period but which could be harmful during postreproductive stage--antagonistic pleiotropy. 2. According traditional assumption on the quality of new mutations is that they are either neutral or harming. Changes which are drift-dependent are becoming reduced. 3. Effective population size (steady state could be supposed or some increase due to more intensive local migration). 4. Migration (In spite of absence of corresponding demographic data) seems to be nowadays more intensive than it was in the past.

Forecasting↗

PubMed2006

Reproductive health, criminal activity, and abuse among 10- to 15-year-old females enrolled in medicaid.

OBJECTIVE: To quantify the degree of abuse or criminal behavior among young females presenting for reproductive health care services. METHODS: An evaluation was conducted among Alaskan females age 10 through 15 years enrolled in Medicaid. Subjects were identified who had experienced reproductive health outcomes. The Medicaid file was linked to a Child Protective Services database and a Juvenile Justice database to identify episodes of abuse by a caretaker and criminal behavior. RESULTS: Of 21,350 Alaskan females aged 10-15 years enrolled in Medicaid during 1999-2003, 841 (3.9%) presented for reproductive health care, 2,930 (14%) were referred to Child Protective Services and 1,858 (8.7%) were referred to Juvenile Justice for criminal activity. Among the subjects with a reproductive health-related claim, 39% were referred to Child Protective Services while 31% were referred to Juvenile Justice at some point during the study period. Reproductive health care was strongly associated with referral to Child Protective Services (adjusted odds ratio [aOR] 2.9, 95% confidence interval [CI] 2.5-3.4), substantiated sexual abuse (aOR 2.3, 95% CI 1.7-3.2), and referral to Juvenile Justice (aOR 2.9, 95% CI 2.5-3.4). These associations remained regardless of the type of reproductive health care, including contraceptive management. CONCLUSION: Females aged 10-15 years enrolled in Medicaid who present for any type of reproductive health care are at increased risk of abuse by a caretaker and criminal behavior. Clinicians caring for low-income females should consider routine screening for sexual activity and the experience of violence. LEVEL OF EVIDENCE: II-2.

Adolescent↗

PubMed1970

Senescence and genetic load: evidence from Tribolium.

After 40 generations in which young adults were killed shortly after the onset of reproduction, strains of Tribolium castaneum with significantly decreased median longevity evolved. These findings support the hypothesis that the longevity of a species is controlled by genetic factors, and represents a compromise between selection for longer reproductive period and the limit set by environmental hazards.

Aging↗