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The seasonal dynamics of the maturation of trematode Bunodera luciopercae was investigated in 1992-1998. The actual fecundity of adult helminths from the ruff, perch, sander and volga pike-perch in the Rybinsk Reservoir was registered in the end of spring. The accumulation process of eggs reflected the host alteration and depended on the food ration, body length and sex of hosts.
In experiment, the mean diurnal fecundity of Leptopsylla segnis females increased during the first five days since the beginning of feeding on white mice and reached the maximum in the second five-day period (15.7-16.7 eggs per 1 female during a day). In subsequent period of stay on a host, an activity of egg laying gradually decreased. In flea females, which had lived on hosts for 40 days and more this index was 3.7 eggs. During the mean life longevity (23 days), the flea females lay about 260 eggs; the females, which have lived more than 40 days, produce above 400 eggs.
How is a species' propensity to vary in size over time related to its chances to be listed on the Red List (Red Book), that is to face the risk of extinction? Here I suggest that the linkage between the range of population fluctuations and chance of listing may be established on the basis of the ratio of species' annual fecundity to annual mortality of adults, B/M. For 23 mammalian species inhabiting the vast tracts of Western Siberia, the range of population fluctuations is found to be equal or at least proportional to B/M. Further, this ratio is estimated for a larger set of 90 mammalian species from the territory and coastal waters of the former Soviet Union, of which 25 species are listed in the Red Book of the USSR. The distribution of the Red Book species over the gradient of B/M is clearly non-uniform: most of them have low B/M, which leads to a negative relationship between chance of listing and B/M. The positive relation between population size variability and B/M and the negative relation between chance of listing and B/M suggest the resulting negative relation between chance of listing and population size variability. Both the positive and the negative relations of, respectively, population size variability and chance of listing on B/M are logically justified since B/M is a measure of the population growth rate: it is the total lifetime offspring and an upper estimate of the growth rate per generation time. Fast-growing, more resilient species tend to be more resistant to extinction and hence to have low chance of listing, but simultaneously are able to fluctuate widely. Thus, so long as population growth rate affects both chance of listing and population size variability, high variability implies low chance of listing.
Rabbit antibodies to hemolymph antigens (102.5, 101, 100, 96, 88, 80, 64, 55, 43, 29, and 23 kDa) of Anopheles stephensi reduced fecundity as well as viability in An. stephensi. However, ingestion of these antibodies was not associated with a marked effect on the engorgement of mosquitoes but egg laying was significantly delayed. Antisera raised against hemolymph proteins were also used to identify cross reactive antigens/epitopes present in other tissues by Western blotting, as well as by in vivo ELISA. In addition, a significant reduction in oocyst development was also observed in An. stephensi mosquitoes that ingested anti-hemolymph antibodies along with Plasmodium vivax. The results confirmed the feasibility of targeting mosquito antigens as a novel anti-mosquito strategy, as well as confirmed the usefulness of such antigens for the development of a transmission-blocking vaccine.
Trenbolone acetate is a synthetic steroid that is extensively used in the United States as a growth promoter in beef cattle. The acetate is administered to livestock via slow-release implants; some is converted by the animal to 17-beta-trenbolone, a relatively potent androgen receptor agonist in mammalian systems. Recent studies indicate that excreted 17-beta-trenbolone is comparatively stable in animal waste, suggesting the potential for exposure to aquatic animals via direct discharge, runoff, or both. However, little is known concerning the toxicity of trenbolone to fish. Our goal was to assess the effects of 17-beta-trenbolone on reproductive endocrinology of the fathead minnow (Pimephales promelas). An in vitro competitive binding study with the fathead minnow androgen receptor demonstrated that 17-beta-trenbolone had a higher affinity for the receptor than that of the endogenous ligand, testosterone. Male and female fish were exposed for 21 d to nominal (target) concentrations of 17-beta-trenbolone ranging from 0.005 to 50 microg/L. Fecundity of the fish was significantly reduced by exposure to measured test concentrations > or = 0.027 microg/ L. The 17-beta-trenbolone was clearly androgenic in vivo at these concentrations, as evidenced by the de novo production in females of dorsal (nuptial) tubercles, structures normally present only on the heads of mature males. Plasma steroid (testosterone and beta-estradiol) and vitellogenin concentrations in the females all were significantly reduced by exposure to 17-beta-trenbolone. The 17-beta-trenbolone also altered reproductive physiology of male fathead minnows, albeit at concentrations much higher than those producing effects in females. Males exposed to 17-beta-trenbolone at 41 microg/L (measured) exhibited decreased plasma concentrations of 11-ketotestosterone and increased concentrations of beta-estradiol and vitellogenin. Overall, our studies indicate that 17-beta-trenbolone is a potent androgen and reproductive toxicant in fish. Given the widespread use of trenbolone acetate as a growth promoter, and relative stability of its metabolites in animal wastes, further studies are warranted to assess potential ecological risk.
BACKGROUND: Debate has been continuing whether endocrine disrupting chemicals (EDC) in the environment affect human reproduction. We are planning to use time to pregnancy (TTP) as a measure of human fecundity to relate EDC exposure in a future research. TTP is expressed as the number of non-contracepting menstrual cycles or months required for a couple to conceive. An extended TTP might be considered to reflect an injury to reproductive processes. Since this parameter has never been measured in Japan. the present preliminary study aimed at establishing a Japanese version of the TTP questionnaire and determining if TTP could be reliably measured in Japan. METHODS: We prepared a self-administered questionnaire that consisted of questions on TTP, sexual life and dietary habits. Women who visited a gynecology clinic in Tokyo for confirmation of pregnancy during the period October 2000 to March 2001 were the subjects asked to fill in the questionnaire. The results were statistically analyzed by chi-square test, t-test and binorminal logistic model after classifying the subjects into two groups: (a) Group I (TTP < or = 6 months; n = 53) (b) Group II (TTP > 6 months; n = 16) RESULTS: Of the 92 women approached, 69 (75.0%) could report TTP. The distribution of TTP, the mode being around 1-2 months with a positive skew toward longer value, was similar to those reported so far in Western countries. There were statistically significantly more smokers in Group II (smoker 62.5%) than in I (15.6%). Logistic regression analysis indicated prior gravidity and fish and milk consumption, in addition to cigarette smoking, to be related to TTP. CONCLUSIONS: The present preliminary study indicated that TTP surveys are feasible with Japanese based on the high response rate and plausible distribution of reported value. It also indicated that TTP was related to cigarette smoking, gravidity and dietary habits, again consistent with previous studies.
Folliculogenesis was studied daily in the 18 oestrous cycles in six prolific Olkuska ewes from October to December using transrectal ultrasonography to record the number and size of all ovarian follicles > or =2 mm in diameter. Blood samples were taken once a day and were analyzed for concentrations of FSH, LH, estradiol and progesterone. Follicular and hormonal data were analyzed for associations between different stages of development of the follicular waves and concentrations of FSH and estradiol. The first wave during which at least one follicle reached maximum diameter of > or =4 mm after ovulation, was defined as a wave 1, and the following waves were numbered sequentially. Waves 1, 2, 3, 4 and the ovulatory one emerged on days: -2 to 4, 4 to 8, 6 to 11, 10 to 12 and 11 to 15, respectively. The mean number of follicles per wave that reached diameter of > or =4 mm was 4.15 +/- 1.1 and 16.62 +/- 8.6 follicles per estrous cycle of a total 299 follicles were observed. Significantly more follicles (p> or =0.05) emerged on days 2, 8 and 13 than in other days. Serum FSH concentrations fluctuated from 0.11 ngml(-1) on day 2 to preovulatory maximum 1.81 ngml(-1) on day 17 of the estrous cycle. The emergence of follicular waves was associated with elevations of FSH concentrations in blood serum. The mean increase in FSH concentration was followed by the recruitment of follicles of the next wave. The mean daily FSH concentration and the mean number of follicles emerging each day were negatively correlated. The length of the interwave interval (4.4 +/- 1.6 days) did not differ significantly from the interval between pulses of FSH (4.8 +/- 0.3 days). The mean serum estradiol concentrations showed fluctuations until day 14 and then gradually increased from 5.47 +/- 0.3 pgml(-1) to reach a peak 13.14 +/- 0.2 pgml(-1) on the day before ovulation. To summarize, the growth of ovarian follicles during the estrous cycle in high fecundity Olkuska sheep exhibited a distinct wave-like pattern. Ovarian follicles emerged from the pool of 2 mm follicles. The preovulatory follicles originated from the large follicle population were present in the ovary at the time of luteal regression. The initial stages of the growth of the largest follicles appears to be controlled primarily by increases in FSH secretion.
Aspects of the infectivity of the plerocercoid stage and the fecundity of the adult stage of Schistocephalus solidus were examined using the chicken, Gallus gallus, as an experimental host. To investigate size-related infectivity of the plerocercoid stage to a definitive host, a range of plerocercoids (166) were weighed, and each was fed to an individual male chicken. Only a very small percentage of plerocercoids weighing less than 50 mg established compared with in excess of 50% in all other weight classes. To examine the factors affecting the quantity of eggs produced by the adult stage, 15 similar-sized plerocercoids (160-218 mg) were fed to chickens. The majority of plerocercoids administered established as adults and survived until the experiment was terminated on day 7 postinfection (PI). Fecal egg counts indicated that all established worms commenced egg production on day 2 PI with peak output on day 2 or 3 PI. By day 7 PI, egg production in the surviving worms had declined, but it was still evident. The final weight of the adult and the average egg output per worm were unrelated to the initial weight of the infecting plerocercoid. However, the average egg output was predicted by the final adult dry weight and to a lesser extent by the proportion of weight lost in the transition from plerocercoid to adult, but not by the absolute weight loss.
Laboratory observations on the effect of Hepatozoon gracilis on the egg production of the mosquito Cx. (Cx.) pipiens Linneaus under laboratory conditions revealed that H. gracilis infected mosquitoes produced significantly fewer eggs than uninfected ones. The egg production decreased as parasite burdens increased. Reduction in blood meal size in infected females did not reduce fecundity. No size differences was detected between oocyst-infected and uninfected females although sporozoite positive females were significantly large. Preoviposition period was affected significantly, while incubation period and percentage of egg hatching showed no significant changes. The longevity of female infected mosquitoes decreased insignificantly than in uninfected ones.
Myrrh has molluscicidal effect on infected Bulinus truncatus and Biomphalaria alexandrina snails at low concentrations (10 & 20 ppm respectively) after 24 hours exposure. The number of dead-snails increased with prolongation of exposure time. All Schistosoma free cercariae were killed by 2.5 ppm within 15 minutes. One day-old egg masses were more susceptible to the ovicidal effect of Myrrh than the five-day old ones. Both types of eggs were more resistant to the effect of Myrrh than the adult snails, embryogenesis began to stop at 20 ppm and eggs were all killed at 60 & 80 ppm. Shedding of cercariae of Schistosoma mansoni from infected B. alexandrina stopped at 1 ppm and was suppressed at 0.8 ppm. Snail fecundity decreased at 1 ppm.
The Bateman principle, which holds that oocytes are the limiting gamete in reproduction, is violated in a variety of species. Self-fertilizing hermaphrodites of the nematode Caenorhabditis elegans provide an example of a system in which sperm number limits lifetime reproductive output, in this species due to the protandrous nature of sperm production that in turn delays the onset of fertilization. This reproductive delay forms the basis of a trade-off between generation time and total fecundity, in which sperm number plays a pivotal role. I use an age-structured population model to describe the number of sperm that maximize fitness, given larval development time and rates of gamete production. The model predicts the evolution of sperm numbers that are consistent with empirical data for C. elegans provided that precocious larval sperm production is taken into account. Several testable hypotheses follow from the model regarding how natural selection and environmental variation may influence patterns of sperm production among populations or species with a similar mode of reproduction.
With the method of space substituting time, the structure of Camellia rosthorniana populations in three forest communities, i.e., Jiant bamboo forest, coniferous and broad-leaved mixed forest, and evergreen broad-leaved forest in Mt. Jinyun was investigated, and based on static life-tables, the fecundity tables and reproductive value tables of C. rosthorniana populations were constructed. Each reproductive parameter and its relation to bionomic strategies of C. rosthorniana populations were also analyzed. The results indicated that in evergreen broad-leaved forest, C. rosthorniana population had the longest life span and the greatest fitness. The stage of maximum reproductive value increased with increasing stability of the community. The sum of each population's reproductive value, residual reproductive value and total reproductive value for the whole life-history of C. rosthorniana also increased with increasing maturity of the community, showing their inherent relationships with reproductive fitness. As regards to bionomic strategy, C. rosthorniana showed mainly the characteristics of a k-strategies, but in less stable community, the reproductive parameters were greatly changed, showing some characteristics of a r-strategies.
Anopheles dirus were reared at two different larval densities (100/pan and 400/pan) to produce two different size classes of adults. Both the wing length and fecundity of females from the two densities were significantly different (p less than 0.001). Adult size was related to larval density and protein accumulation during immature life. Egg production was also related to adult size. Consequently, larger field adults have the potential to live longer and produce more eggs. The smaller adult size associated with crowded larval development was apparently caused by space associated effect on feeding rather than by a shortage of food per se.
Changes in polypeptides pattern of haemolymph, midgut, ovary and salivary glands of female mosquito A. stephensi were studied when fed upon anti-mosquito haemolymph antibodies. The expression of almost all polypeptides was reduced in haemolymph and ovary of the immune fed mosquitoes as compared to control. However, there was no significant difference in case of midgut and salivary glands. Seven polypeptides 100, 90, 84, 80, 62, 19 and 12.5 kDa were absent in haemolymph and five 92, 90, 80, 60 and 55 kDa were absent in ovaries. Changes in the polypeptide pattern have been correlated with the fecundity reduction due to immunized blood feeding.
The study on the development, survivorship and fecundity of Cicadulina bipunctella reared on corn, wheat, sorghum, rice, millet, barley and Leptochloa panacea showed that the insect could develop and reproduce on all test host plants except for Leptochloa panacea. The development duration of C. bipunctella at its immature stages reared on sorghum was the shortest (24.1 d), then on corn (24.2 d), and the longest on wheat (25.5 d). The survival rate (40.8%), longevity (12.2 d) and oviposition per female (12.3 eggs) of female adults reared on rice were lower than those reared on the other five host plants. Based on the life-table parameters, the most suitable host plants for the development and reproduction of C. bipunctella were millet and corn, followed by sorghum, barley, wheat and rice.
The luteal phase of cycles stimulated with human menopausal gonadotropins (hMG) may be characterized by aberrant hormone levels, altered endometrial development, and shortened length. Luteal phase support with supplemental progesterone or hCG has been recommended to help correct these problems and thus improve pregnancy rates, but the efficacy of such regimens is controversial. Therefore, a randomized cross-over study was performed to evaluate the effects of luteal phase hCG administration on pregnancy rates during ovulation induction with hMG. Sixty-seven infertile women were randomly assigned to either group A (N = 33) or group B (N = 34). Non-treatment cycles (no luteal phase support) were alternated with treatment cycles, in which patients received 2500 IU hCG on the third, sixth, and ninth days after the ovulatory dose of 10,000 IU hCG. Patients in group A received supplemental hCG in odd-numbered cycles, whereas group B was given luteal support in even-numbered cycles. The mean number of cycles per patient was 2.2 and 2.3 for groups A and B, respectively. Analysis of 151 cycles revealed a cycle fecundity of 0.15 for 72 hCG-supported cycles, versus 0.13 for 79 nonsupported cycles (P = not significant). Midluteal progesterone levels were significantly higher in supported (45.6 ng/mL) versus unsupported cycles (31.9 ng/mL) (P less than .001). There were no significant differences in the mean peak estradiol levels in hCG-supported versus -unsupported cycles. We conclude that hCG support of the luteal phase is not routinely warranted in hMG-stimulated cycles.
Laboratory work has shown that mosquitoes obtaining blood meals from animals treated with ivermectin exhibit lowered adult survival, fecundity, egg hatch and larval survival. Computer simulation evaluated the consequences of this phenomenon in field populations of Psorophora columbiae feeding on cattle in the rice agroecosystem. Results suggest that rather minor reductions, on the order of 10% below normal, in these life history parameters would significantly affect the population dynamics of this species in this particular system. Significant reductions in the amount of insecticide used for mosquito abatement are also projected.
The insecticidal activity of Trigonella foenum-graecunm (fenugreek) against the larval maturation and adult emergency of An. pharoensis 3rd stage was evaluated under controlled laboratory conditions. Concentrations of 100%, 70%, 50%, 25%, 5%, 2%, 1%, 0.9%, 0.7%, 0.5% & 0.3% showed 100% larval mortality rate. 0.2% & 0.1% caused mortality of 88.9% & 66.7% respectively. On the other hand, the fecundity of emerged adults was zero % and 33.3%. However, one control larvae died and the nine emerged adults were fertile. So, it was recommended to be use in controlling larvae of An. pharoensis.