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PubMed1999

Breeding biology of muscovy duck (Cairina moschata) under natural incubation: the use of the weibull function and a beta-binomial model to predict nest hatchability

In this paper we tested the Weibull function and beta-binomial distribution to analyse and predict nest hatchability, using empirical data on hatchability in Muscovy duck (Cairina moschata) eggs under natural incubation (932 successfully incubated nests and 11 822 eggs). The estimated parameters of the Weibull function and beta-binomial model were compared with the logistic regression analysis. The maximum likelihood estimation of the parameters was used to quantify simultaneously the influence of the nesting behaviour and the duration of the reproduction cycle on hatchability. The estimated parameters showed that the hatchability was not affected in natural dump nests, but in artificial dump nests and in nests with non-term eggs the hatchability was reduced by 10 and 25%, respectively. Similar results were obtained using logistic regression. Both models provided a satisfactory description of the observed data set, but the beta-binomial model proved to have more parameters with practical and biological meaningful interpretations, because this model is able to quantify and incorporate the unexplained variation in a single parameter theta (which is a variance measure). Copyright 1999 Academic Press.

Journal Article↗

PubMed2004

Cadmium effects on development and reproduction of Oncopeltus fasciatus (Heteroptera: Lygaeidae).

Newly hatched nymphs of the insect Oncopeltus fasciatus were exposed to various concentrations of CdCl2 administered in drinking water until the end of adult life. Significant nymphal mortalities were observed at concentrations above 30 mg Cd/l (corresponding to the LC50). The duration of the nymphal stages increased in proportion to the Cd concentration; at the lowest Cd concentration of 10 mg Cd/l, the median duration was significantly prolonged by one day, while at the highest concentration of 100 mg Cd/l it was increased by 10 days over the control group. The weight of newly emerged adults lineally decreased with Cd concentration, being reduced to half the weight of controls at 100 mg Cd/l. In addition, a proportionality between delay in development and weight reduction was found in Cd-treated adults. Survival of adult females was decreased at concentrations higher than 10 mg Cd/l, while males were only affected at 30 mg Cd/l or higher doses. Reproduction was the most affected parameter. Oviposition rate, fecundity and fertility of females exposed to 10 mg Cd/l were significantly lower than controls (73%, 58% and 55% relative to controls, respectively). Hatchability of the eggs laid by treated females was also reduced. These results show that development and reproduction of O. fasciatus are seriously impaired at sublethal Cd concentrations.

Age Factors↗

PubMed1985

Effects of concurrent pregnancy and lactation on reproduction in four strains of mice.

The influence of concurrent pregnancy until the third lactation on reproduction was studied in four strains of mice (SHN, SLN, C3H/He and GRS/A) as a possible step to evaluate the efficiency of this system on offspring production. In all strains, little difference was observed between sequential and concurrent pregnancy and lactation groups in any parameter as the index of reproductivity--delivery interval, litter size, average weight and growth rate of pups, mother weight, rearing rate, still-birth rate and rate of still-born pups. Also, no difference was seen between groups of any strain, in the number of females which had three litters. The estimated number of pups weaned per female during 50 days after first being placed with males was higher in the concurrent pregnancy groups than in the sequential pregnancy groups of all strains. Meanwhile, the incidence of spontaneous mammary tumors, the major characteristic of these strains, was consistently lower in the concurrent pregnancy group in all strains. These results have demonstrated that the concurrent pregnancy and lactation system is an efficient means of mouse production.

Animal Husbandry↗

PubMed1975

Reproductive Growth and Dry Matter Production of Glycine max (L.) Merr. in Response to Oxygen Concentration.

Reproductive as well as vegetative parameters of mature soybean (Glycine max [L.] Merr. cv. Wye) plants grown in chambers in which the aerial portion was exposed to altered pO(2) during all or part of the growth cycle were measured. Oxygen concentration was found to be a key factor controlling all phases of reproductive development. Exposure to 5% O(2) from early seedling stage to senescence increased leaf, stem, and root dry weights and reduced seed yields when compared to 21% O(2); exposure to low O(2) during the vegetative growth stage from early seedling to mid-flowering arrested pod but not seed development; exposure from mid-flowering to mid-pod filling almost completely arrested seed but not pod development; exposure from mid-pod filling to senescence arrested seed development at the mid-filling stage.Exposures to 5% O(2) initiated at mid-flowering for 1, 2, 3, 5, 10, and 15 days had no effect on seed development when the exposure was up to 3 days and produced almost total arrest when the exposure was 10 or more days, suggesting reversibility. The requirement for O(2) in seed development is independent of CO(2) concentration with similar results produced by subambient O(2) combined with ambient CO(2), elevated CO(2) up to 2000 mul/l or depressed levels of CO(2) with the CO(2)/O(2) ratio as in air. An elevated O(2) atmosphere containing 40% O(2) and ambient or elevated CO(2) inhibited total growth but did not affect the balance of vegetative to reproductive growth.We conclude that an unknown reaction or process requiring at least atmospheric concentrations of O(2) but independent of CO(2) in contrast to photorespiration is necessary for optimization of all phases of reproductive growth and the effect is reversible for exposures of up to 3 days but not for exposures of 10 days or more. We propose that this O(2) phenomenon may be the result of a unique physical process or chemical reaction associated with translocation and accumulation of assimilates in reproductive structures.

Journal Article↗

PubMed2002

Cycle-to-cycle variation in utero-ovarian hemodynamic indices in ovarian stimulation and natural cycles of the same women and its effect on the outcome of assisted reproduction treatment.

OBJECTIVE: To investigate the blood flow parameters between cycles of the same women to assess whether parameters predicting a successful pregnancy in a stimulation cycle could be used to determine the outcome of subsequent natural cycles. DESIGN: A prospective study. SETTING: Assisted reproduction unit, the University of Hong Kong. PATIENT(S): Fifty-eight IVF cycles and 40 natural cycles were evaluated. INTERVENTION(S): Assessments of the utero-ovarian pulsatility indices (PIs), resistance indices (RIs), and endometrial color signals. RESULT(S): In IVF cycles, the pregnancy rate (27%) was similar to that in frozen-thawed embryo transfer (FET) (28%) cycles. The utero-ovarian PIs and RIs in IVF cycles were significantly lower than those in the natural cycles. There was a significant correlation between the uterine PI in stimulation cycles and that in natural cycles. In IVF cycles, the pregnancy rate declined significantly when the uterine PI was >2.70 and the RI was >0.9. In FET cycles, no decline in pregnancy rate was seen. Conceptional FET cycles showed significantly higher uterine PI, uterine RI, and endometrial color signals compared with conceptional IVF cycles. CONCLUSION(S): Hemodynamic parameters in stimulation cycles are different from those in natural cycles, and the values of various parameters in predicting pregnancy are also different.

Cryopreservation↗

PubMed2006

The impact of increased environmental stochasticity due to climate change on the dynamics of asiatic wild ass.

Theory proposes that increased environmental stochasticity negatively impacts population viability. Thus, in addition to the directional changes predicted for weather parameters under global climate change (GCC), the increase in variance of these parameters may also have a negative effect on biodiversity. As a case study, we assessed the impact of interannual variance in precipitation on the viability of an Asiatic wild ass (Equus hemionus) population reintroduced in Makhtesh Ramon Nature Reserve, Israel. We monitored the population from 1985 to 1999 to determine what environmental factors affect reproductive success. Annual precipitation during the year before conception, drought conditions during gestation, and population size determined reproductive success. We used the parameters derived from this model to assess population performance under various scenarios in a Leslie matrix type model with demographic and environmental stochasticity. Specifically, we used a change in the precipitation regime in our study area to formulate a GCC scenario and compared the simulated dynamics of the population with a no-change scenario. The coefficient of variation in population size under the global change scenario was 30% higher than under the no-change scenario. Minor die-offs (> or = 15%) following droughts increased extinction probability nearly 10-fold. Our results support the idea that an increase in environmental stochasticity due to GCC may, in itself, pose a significant threat to biodiversity.

Animals↗

PubMed1998

Exogenous influences on human fertility: fluctuations in sperm parameters and results of in-vitro fertilization coincide with conceptions in the normal population.

Intra- and interindividual short-term fluctuations of sperm parameters were observed in assisted reproduction patients, paralleled by respective fluctuations of the in-vitro fertilization (IVF) results. To test whether the fertility fluctuations observed in the clinic were representative for the overall population, birth statistics of two normal subpopulations (urban and rural) were studied. There were highly significant parallels in the fluctuations of the monthly deliveries in both normal subpopulations. Also, there was a significant correlation when the fluctuation of sperm parameters in IVF patients was compared with those of a control group. Furthermore, delivery fluctuations in the overall population were significantly paralleled by fluctuations in sperm parameters and IVF results around the conception time of these deliveries. In all groups, the pattern and amplitude of the short-term fluctuations varied from year to year. Frequently observed peaks in late autumn gave rise to the appearance of a semi-seasonal variation in fertility. The existence of an external influence on overall male gamete quality must be postulated, which has considerable influence on the IVF results. This short-term influence might be causally linked to the factors responsible for the previously found annual variation in human fertility and possibly for the long-term changes in human reproductive function.

Birth Rate↗

PubMed1995

Tolerance induction and life cycle changes in cadmium-exposed Chironomus riparius (Diptera) during consecutive generations.

Cultures of Chironomus riparius were exposed to cadmium during nine consecutive generations to determine whether cadmium tolerance could be induced. Selection for cadmium tolerance was assumed to influence the population dynamics of this species. Therefore, the responses and interactions of different population parameters (such as mortality, growth, and reproduction) were studied during the selection process. Exposure to cadmium during consecutive generations caused increasing effects on some life cycle parameters compared to a one-generation experiment. Tolerance to cadmium increased during exposure to 54.2 nM Cd and the tolerant population seemed to be stimulated by low cadmium concentrations (based on an acute growth experiment). Despite this tolerance development, mortality among cadmium-exposed tolerant chironomids remained high. These experiments illustrated that changes of the life cycle and tolerance can be expected as soon as single-generation NOEC values are exceeded, and in addition that "safe concentrations" based on a one-generation toxicity experiment could well underestimate the potential effects of a toxicant on midge populations.

Animals↗

PubMed1984

The reproductive potential of normal mouse embryo fibroblasts during culture in vitro.

A direct estimate of the reproductive potential of mouse embryo fibroblasts through their entire lifespan has been made using the mini-clone technique, which permits the direct observation of the growth fraction in a bulk population by inspection of the growth behaviour of individual cells. We have measured the colony size on each island that contained one or two cells at the beginning and the fraction of islands which, starting from one or two cells failed to divide even once. We observed that even in a young culture there are individual cells that can only reproduce two or three times. With each succeeding passage the distribution of colony sizes shifts to a greater proportion of small colonies. The median colony size decreases with each passage. Furthermore, the fraction of non-dividers directly observed increases smoothly with time; the fraction of non-dividers is quite small at the first passage but increases steadily to reach 0.6 at the last passage, after about 30 generations. These smooth changes in the growth behaviour of this cell strain are accurately described by the mortalization theory of Shall and Stein, in which the single parameter gamma, describes the change in reproductive potential over the entire lifespan. The parameter gamma describes the rate at which the doubling time of the culture increases; it is the number of generations at which half of the newborn cells are themselves reproductively sterile. Our present data provide an estimate of gamma for this cell strain equal to 21.2 generations, which compares well with a previous estimate of 20.3 generations.

Animals↗

PubMed1993

Impact of experimental genital mycoplasmosis on pregnancy outcome in Sprague-Dawley rats.

Specific-pathogen-free (SPF) female Sprague-Dawley rats were infected by intravaginal inoculation with 3 x 10(7) CFU of Mycoplasma pulmonis X1048 in 0.1 ml of Frey's broth or with an equal volume of sterile Frey's broth. A minimum of 10 days postinfection, rats were bred to noninfected males. Rats were necropsied at days 11, 14, and 18 of gestation and within 24 h of parturition. Throughout pregnancy, at least 50% of rats remained infected in the lower genital tract. At parturition, the major site of colonization was the respiratory tract (P = 0.02). M. pulmonis was not isolated from any site of any control rat. Pregnancy outcome was adversely affected by infection with M. pulmonis. Infected rats had significantly smaller litter sizes at day 18 of gestation (P < or = 0.01) and at term (P < or = 0.004). No statistically significant differences among the gestational stages in infected rats were noted for litter size. Total litter weight is a reflection of individual pup weight and of the number of pups born. Therefore, it was obvious that infected rats would have a significantly lower (P < or = 0.008) total litter weight than noninfected controls. However, when individual pup weights were considered, infected pups (n = 49) also had significantly lower (P < or = 0.0001) birth weights than did noninfected controls (n = 68). The incidence of an adverse pregnancy outcome at term (stillbirths, macerated fetuses, or resorptions) was higher (P < or = 0.01) in infected rats than in noninfected control rats. No stillborn pups or macerated fetuses were observed in any control term rats (n = 5). All control rats had live-born pups. Three infected rats had no live-born offspring. Resorptions were more common in infected rats than in control rats (P < or = 0.01). The mean number of resorptions per rat was greater in rats which went to term than in rats necropsied during gestation, indicating that the severity of disease was progressive. The rat is frequently the laboratory animal of choice for a wide variety of reproductive studies, and the experimental parameters that are most often measured (litter size, pup weight, and neonatal survival) were all adversely affected by genital mycoplasmosis. Genital mycoplasmosis is important as an animal model for the interaction of infectious agents and the host during pregnancy as well as in its own right as a confounding variable affecting research projects which use the rat as a model to study reproductive function and physiology.

Animals↗

PubMed2005

Lack of evidence for endocrine disrupting effects in rats exposed to fenitrothion in utero and from weaning to maturation.

Fenitrothion is a broad-spectrum organophosphate insecticide. Recently, it has been reported to exert androgenic or anti-androgenic activity in in vitro and in vivo screening assays, although the effects appear equivocal in vivo. To provide a conclusive and comprehensive evaluation of fenitrothion, especially regarding its anti-androgenic activity in the reproductive and endocrine systems, we conducted a one-generation reproductive toxicity study at appropriately toxic dose levels with a number of sensitive endpoints for endocrine disruption. Fenitrothion was administered to Crj:CD(SD)IGS parental animals (P) at concentrations of 10, 20, and 60 ppm in the diet for 10 weeks prior to mating, and throughout mating, gestation and lactation. Their offspring (F1) were exposed from weaning until maturation at the age of 10 weeks. In the P generation, brain cholinesterase activity was remarkably reduced in the 60 ppm males and in the 20 and 60 ppm females. Reproductive performance, organ weights, histopathology, and sperm analytical parameters were not affected. In the F1 generation, no general toxicity or effects on anogenital distance, retention of areolae/nipples, onset of puberty, organ weights, histopathological findings, and sperm parameters were observed. In conclusion, fenitrothion had no effects on the reproductive or endocrine systems of the P and F1 generations, even at toxic doses that markedly suppressed brain cholinesterase activity in P animals. The results suggest that fenitrothion at in-use levels in the environment is unlikely to cause disruption of human endocrine systems.

Acetylcholinesterase↗

PubMed1999

Assessment of the toxicity of a pesticide with a two-generation reproduction test using Daphnia magna.

Daphnia magna (F0 generation) were exposed during 21 days to different diazinon concentrations. Offspring (animals from the first and third brood: F1 (1st) and F1 (3rd), respectively) were transferred to a free pesticide medium during a 21-day recovery period. The algae Nannochloris oculata (5x10(5) cells/ml) were used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters, and the intrinsic rate of natural increase (r) as population parameter for F1 (1st and 3rd broods) daphnids. Reproduction as well as survival was still reduced in F1 (1st) generation daphnids from parentals (F0) exposed to the highest diazinon concentration. However, F1 (1st) and F1 (3rd) individuals from parentals exposed to pesticide concentrations below 0.5 ng/l were able to restore reproduction and survival when a recovery period of 21 days was allowed.

Animals↗

PubMed2000

Population dynamics in Daphnia magna as modified by chronic tetradifon stress.

Two Daphnia magna offsprings (animals from the first and third brood) whose parentals (F0-generation) were exposed during 21 days to different tetradifon (4-chlorophenyl 2,4,5-trichlophenyl sulfone) concentrations, were transferred to a pesticide free medium during 21 days (recovery period). The algae Nannochloris oculata (5 x 10(5) cells/mL) was used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters and the intrinsic rate of natural increase (r) as population parameter, for F1 generation (1st and 3rd broods). Reproduction was still reduced in F1 (1st and 3rd broods) generation daphnids from parentals (F0) exposed to 0.18 mg/L tetradifon and higher concentrations even after 21 days in clean water. However, survival was not significantly different (p > 0.05) in those F1 offsprings from parentals pre-exposed to the acaricide. Growth was still reduced in F1 daphnids from parentals pre-exposed to 0.10-0.44 mg/L tetradifon. The intrinsic rate of natural increase (r) was still affected in F1 generation daphnids, specially in those from the third brood. Therefore, F1 generation D. magna offsprings from a parental generation (F0) previously exposed to the acaricide tetradifon were not able to recuperate completely when a recovery period of 21 days was allowed.

Animals↗

PubMed1996

Malthusian parameter on the Finnish population in the 20th century.

We were interested in studying a demographic indicator, the Malthusian parameter which had not been investigated earlier in the case of the Finnish population. We computed the Malthusian parameter with a known renewal equation, which is, as usual, approximated on discrete data by using normal distribution, on the Finnish population in the 20th century. The data was collected from the abundant official statistical sources which are known to be accurate and reliable in Finland. In addition to this parameter we computed the gross and net reproduction rates, the total fertility index, and the mean and variance age of females at child-bearing. The Malthusian parameter seems to be a rather good means of characterizing the development of the population. If the parameter is positive for long enough, the population tends to grow. If it is negative, as has been the case in Finland since 1969, the population starts to diminish sooner or later. On the other hand, it cannot take all factors into account. For instance, because of still increasing lifetime and also because of a relatively large quantity of females at the reproductive age the population is not yet decreasing in Finland. In any case, the Malthusian parameter forecasts the future trend of the decreasing population.

Adolescent↗

PubMed1996

The effect of stress on semen reduction in the marmoset monkey (Callithrix jacchus).

This study compared a number of semen parameters of two separate groups of the common marmoset monkey (Callithrix jacchus) in order to determine the effect of a continuous potentially stressful situation on these parameters, and thus on the monkey's reproductive ability. The semen from 16 adult male marmoset monkeys was collected and analysed to compare semen parameters between a 'normal' (control) group (n = 9) and a 'blood withdrawn' ('stress') group (n = 7). The semen parameter values observed in the control were: pH 7.51 +/- 0.22, volume 40.2 +/- 27.2 microliters, concentration 27.3 +/- 14.8 x 10(4)/microliters, motility 47.4 +/- 15.9%, grade of velocity 3.5 +/- 1.2, and normal morphological forms 51.8 +/- 13.7%. The 'blood withdrawn' group of marmoset monkeys showed significantly lower semen volume and sperm concentration than the 'normal' group. In addition, total count of spermatozoa, normal spermatozoa, motile spermatozoa and normal motile spermatozoa per ejaculate per monkey was significantly reduced in the 'blood withdrawn' group. The semen of these monkeys also revealed a significantly higher percentage of abnormally-shaped sperm heads than the normal group, and cases of impotence and sham ejaculation were recorded. Our study revealed that the continuous withdrawal of a small volume of blood from a group of marmoset monkeys appeared to be stressful to these monkeys and as a result, influenced their semen parameters, possibly making them less fertile. In addition, electroejaculation was found to be possibly harmful to the monkey's reproductive ability.

Animals↗

PubMed2007

Small is useful in endocrine disrupter assessment--four key recommendations for aquatic invertebrate research.

As we enter the 21st "biocentury", with issues such as biodiversity and biotechnology growing in public profile, it is important to reflect on the immense ecological, medical and economic importance of invertebrates. Efforts to understand the diverse biology of invertebrates come from many directions, including Nobel Prize winning developmental biology, research to control insects that threaten human health and food supplies, aquaculture opportunities and also within ecotoxicology. In the latter context, this special journal volume highlights the importance of addressing endocrine disruption in aquatic invertebrates, from molecular and cellular biomarkers to population-relevant adverse effects. The contributors to this special volume have provided an excellent assessment of both the fundamental endocrinology and applied ecotoxicology of many aquatic invertebrate groups. On the premise that reproductive success is ultimately the vital population parameter, this chapter gives a personal view of key gaps in knowledge in invertebrate reproductive and developmental endocrinology and ecotoxicology. Based on current knowledge, there are four key issues that need to be prioritised within aquatic ecotoxicology: (1) a wider assessment of the reproductive status of invertebrates in both freshwater and coastal ecosystems; (2) prioritisation of laboratory studies in OECD and other regulatory test organisms, including basic endocrinology and ADME (absorption, distribution, metabolism and excretion) research; (3) development and validation of mechanistic biomarkers that can be used as "signposts" to help prioritise species and chronic test endpoint selection, and help link data from laboratory and field studies; and (4) develop a comparative invertebrate toxicology database utilising the prioritised reference chemicals from the EDIETA workshop, encompassing the diverse modes-of-action pertinent to endocrine disrupter testing in both aquatic arthropod and non-arthropod invertebrates.

Animals↗

PubMed1984

[Antineoplastic agents and pregnancy].

The current impossibility of establishing a definite causal relationship between the administration of antineoplastic drugs before and/or during pregnancy and possible modifications of the gestational attitude in the treated women is discussed after a review of the Literature. The data till now reported are often deficient as far as concerns the evaluation of either the fetal, perinatal and post-natal parameters and the past and current reproductive performance of the patients on study. The need for strict methodology in the study and report of feto-maternal parameters to provide a comprehensive answer to the questions raised by the use of antineoplastic drugs before and/or during pregnancy is discussed in detail.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

Circannual rhythms in reproductive functions of human males, correlations among hormones and hormone-dependent parameters.

In a longitudinal study one healthy man aged 26 yrs underwent semen collections and blood samplings at monthly interval from January to December 1985. The ejaculated samples were analyzed for sperm density, motility, relative proportion of early (ab) and late (cd) spermatids, concentrations of Fructose, L-Carnitine and Transferrin. In a transverse study, 248 serially independent samplings were performed of normal men, 28.9 +/- 7.5 yrs old, consulting for infertility from January 1981 to December 1983. The Cosinor method was employed for searching on circannual rhythms of the studied parameters. The longitudinal study did not detect circannual rhythms of the considered seminal parameters nor of the studied hormones. However, peaks, significantly above the mean values throughout the year (p less than 0.005), were observed of Cortisol, PRL, FSH, LH, Testosterone, Fructose and L-Carnitine levels. Young spermatids and sperm motility showed significant (p less than 0.001) acrophases between June and July; an acrophase was also evident for late spermatids but shifted by six months, between December and January. Mesors and amplitudes were respectively: 28 +/- 1.5 and 9.6 +/- 4.3 (mean +/- SE) for motility; 33.4 +/- 1.6 and 9.9 +/- 5 for early spermatids; 46.6 +/- 1.9 and 13 +/- 6.2 for late spermatids.

Adult↗