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Results for “Fecundability”

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At least 127 records · Page 7Linked to original sources

PubMed1994

Schistosoma mansoni: relationship between low fecundity and reduced susceptibility to parasite infection in the snail Biomphalaria glabrata.

Biomphalaria glabrata snails which were not susceptible as juveniles to infection by Schistosoma mansoni were selectively bred (by self-fertilization) from the highly susceptible NMRI laboratory snail stock. The susceptibility rate among juvenile snails derived from interbreeding NMRI parents was initially 85-95%, but after several generations of selection, less than 5% of exposed snails became infected by the parasite. Selection for low susceptibility also resulted in a large proportion of snails that displayed low fecundity and produced abnormal egg masses. Individual adult snails which were isolated from an interbreeding population of nonselected NMRI snails usually produced well-developed egg masses each containing 15-30 embryos. However, when juvenile snails from this same population were reared in isolation and not allowed to cross-fertilize, many displayed a pattern of low fecundity and abnormal egg production similar to that observed in the selected low susceptible line. Furthermore, it was found that many of the isolated snails which exhibited low egg production were also not susceptible to parasitic infection.

Animals↗

PubMed1995

Biology of Ixodes (Pholeoixodes) hexagonus under laboratory conditions. Part II. Effect of mating on feeding and fecundity of females.

The effect of mating on the feeding and fecundity of Ixodes (Pholeoixodes) hexagonus females was studied under controlled laboratory conditions of 22-23 degrees C and 98% relative humidity. The feeding period of mated females was 6-15 days and 11-13 days for unmated females. The mean weight of the engorged mated females was 114.84 +/- 45.89 mg, whereas, that of the engorged unmated females was significantly lower (80.61 +/- 28.84 mg). During the initial slow feeding period, the weight of mated females increased 6.6 times. At the end of the blood feeding, they had increased their initial weight 35.5 times. Unmated females never entered the rapid engorgement phase and up to 12 days of feeding period their mean weight did not increase more than 9.2 times. The pre-oviposition periods of mated and unmated females were 6-15 days and 4-12 days, respectively. The mean of the egg production efficiency was 40.26 +/- 12.47% for mated females and 35.68 +/- 12.2% for unmated females. The mean of the mass conversion efficiency was 73.6 +/- 13.7% for mated females and 66.48 +/- 16.55% for unmated females. Sixty per cent of the eggs deposited by mated females hatched whereas only 1% of the eggs deposited by unmated females hatched. These results indicate that I. hexagonus females possess some predisposition for parthenogenesis and only fertility and not fecundity depends on mating.

Animals↗

PubMed1989

The effect of heterologous gonadotropins on the fecundity of rhesus monkeys.

Ovarian stimulation with heterologous gonadotropins over a period of a single month did not depress the fecundity or fecundability of 50 rhesus monkeys as compared to 60 untreated monkeys in a timed breeding colony. The birth rates, seasonality of births, interbirth intervals, and waiting time to the next pregnancy were not significantly different before treatment, after treatment, or among the untreated. The stillbirth rate was not increased after treatment.

Animals↗

PubMed1996

Growth and fecundity of Oesophagostomum dentatum in high-level infections and after transplantation into naive pigs.

This experiment was designed to examine the growth, proportion of stages, and fecundity of an Oesophagostomum dentatum population by transplantation of a known small number of worms from a high-density population into helminth-naive recipient pigs. Approximately 1,500 4-week-old worms [69% fourth-stage larvae (L4), 31% adult worms] were transplanted into each of 5 recipient pigs (group B), and these pigs, along with a group of 5 high-level-infection control pigs (group C), were killed at 4 weeks after transplantation to determine and compare the worm burdens. By 2 weeks after transplantation and throughout the experiment, fecal egg counts of group B exceeded those of group C and the fecundity of the worms was higher, though not statistically significantly so, in the transplanted worms. In the recipient pigs, all worms (approx. 70% establishment) had developed to the adult stage and were significantly longer than worms recovered from the group C pigs.

Animals↗

PubMed1987

A flowthrough fecundity test with Nitocra spinipes (Harpacticoidea Crustacea) for aquatic toxicity.

A sublethal flowthrough fecundity test with the euryhaline harpacticoid copepod Nitocra spinipes has been developed as a complement to the acute toxicity test (for 48 or 96 hr LC50) with the same species (B-E. Bengtsson, 1981, Mar. Pollut. Biol. 9,238-241). Bacterial suspension as feed and test water are continuously fed by a peristaltic pump to the system. Newly fertilized females with ovigerous bands are harvested from laboratory cultures and put into the test vessels at the start of the experiment. They are then exposed to a series of concentrations of chemicals or industrial effluents for 13 days. The amount of live offspring (metanauplia and copepodids) are recorded and an EC50 for fecundity is calculated. The report gives a detailed technical description of the test system and presents the results from 11 tests with pure chemicals (Zn, Cd, As, and pentachlorophenate) and six industrial effluents (pulp industry, textile industry, and refinery) in salinities ranging from 3 to 25%.

Animals↗

PubMed1995

Immunization of mice with recombinant Sjc26GST induces a pronounced anti-fecundity effect after experimental infection with Chinese Schistosoma japonicum.

We report the cloning, by polymerase chain reaction (PCR), of a cDNA encoding a Schistosoma japonicum (Chinese) 26 kDa glutathione-S-transferase (GST) (Sjc26GST), expression of the cDNA, affinity purification of the recombinant GST and its vaccine efficacy in outbred NIH mice using Freund's as adjuvant. The most striking feature of the vaccination experiments was the pronounced reduction in the number of eggs in the livers and spleens of immunized mice. A relatively low but significant level of protection in terms of reduced worm viability against challenge infection was also observed. Further, the level of anti-Sjc26GST antibody in immunized mice was significantly higher than in control mice at week 6 post-challenge infection. These results closely mirror the protection conferred by immunization of animals with the 28 kDa GST of S. mansoni (Sm28) where a reduction in worm viability, worm fecundity and egg-hatching ability have been reported following challenge with S. mansoni. In terms of developing a vaccine against schistosomiasis japonica, immunization with Sjc26GST can provide two complementary goals in human or animal populations--some reduction in worm burden following exposure to infection or reinfection, and an anti-disease effect through reduction of pathology by a decrease in worm fecundity, with this direct effect also affecting the transmission of S. japonicum.

Animals↗

PubMed1988

Does minimal endometriosis reduce fecundity?

Twenty-one patients with minimal endometriosis treated with artificial insemination with donor semen (AID) because of male sterility were compared with 40 patients with the same degree of endometriosis treated by "expectant management" (EM). The conception response of both groups was analyzed with the life-table method calculating the monthly fecundity rate (MFR), and the cumulative pregnancy rate (CPR). Both groups were similar in terms of woman's age and length of infertility before diagnosis. The results obtained after the 12th month showed that the group treated with AID had a CPR of 80.9% and an MFR of 0.201, much higher than the group treated with EM, in which the CPR was 47.5% and the MFR 0.060. The results of the fecundity rate of the AID-treated group was comparable to that of normal population.

Adult↗

PubMed1994

Infectivity, growth, distribution and fecundity of a six versus twenty-five metacercarial cyst inoculum of Echinostoma caproni in ICR mice.

Female ICR mice, 6-8 weeks old, were exposed to 6 (group A) or 25 (group B) metacercarial cysts/host of Echinostoma caproni to determine the effects of these cyst dosages on infectivity, growth, distribution and fecundity of worms in the small intestines. All 30 mice exposed (15 in group A and 15 in group B) were infected and there was no significant difference in the percentage of worm recovery between group A and B at 2, 4 and 8 weeks postinfection (PI). Growth was rapid in both groups with worm body areas increasing from about 3mm2 at 2 weeks PI to about 7 mm2 at 8 weeks PI. More worms from group B were in the anterior sections of the small intestines at 2 and 4 weeks PI than those from group A. However, at 8 weeks PI more worms from Group A were in the anterior sections of the small intestines than those from group B. There were marked differences in our findings on infectivity, growth and distribution of E. caproni in ICR mice using 6 and 25 cyst inocula compared to a previous study using the same echinostome and cyst inocula in NMRI mice, presumably related to the mouse strain. Fecundity studies were somewhat comparable in both studies showing an approximate three to four times increase in the average number of eggs/gram of faeces in mice receiving 25 versus 6 cyst inocula.

Animals↗

PubMed1984

Parasite density and the fecundity of Angiostrongylus cantonensis in rats.

The larval output of Angiostrongylus cantonensis at different initial densities in rats was examined throughout the reproductive life-span of the worms using a modified dilution technique. With an initial density of 2 worms the mean duration of larval output was 414.2 days. The output was at a level above 50000 larvae/female/day from 15 to 45 weeks after infection. The mean total output was 18.9 X 10(6) larvae/female. The larval output/female decreased with an increase in the worm burden and also with the passage of time after infection. The longevity of host rats also decreased with increasing worm density and many of the heavily infected rats died early during infection. These results suggest that worm density has an effect on the fecundity of this parasite, and that the effects may be due to fibrous changes in host lung tissue but not changes in the physiology of the worms. It is also suggested that density-dependent effects on fecundity play a role in the population dynamics of both the parasite and host as regulatory mechanisms in the field.

Angiostrongylus↗

PubMed1985

The effect of host density on the establishment and fecundity of Heligmosomoides polygyrus.

The effect of mouse population density on the establishment, survival and fecundity of single cohorts of Heligmosomoides polygyrus was investigated. No significant relationship was found between host population density and the worm burden at post mortem. But, lower host population densities were associated with higher parasite fecundities and with higher overall mean daily faecal output. The results might be explained by a decrease in male hormone secretion or digestive disturbances associated with lower ingesta in the higher host population densities. Effects resulting from changes in immunological responses might also exist.

Animals↗

PubMed1987

The regulation of Ostertagia ostertagi populations in calves: density-dependent control of fecundity.

The decline in faecal egg counts, characteristic of calves which have been experimentally infected with Ostertagia ostertagi, is analysed using a mathematical model in which parasite fecundity is assumed to be an inverse function of both the duration and intensity of infection. The model incorporates a description of the frequency distribution of mature parasites between hosts (which is less over-dispersed than is usual for many other helminth infections). The model provides a good overall description of the decline in faecal egg production observed during trickle and single infection experiments. The main discrepancy between a comparison of the model predictions and the results of the most detailed available series of trickle infection experiments occurs at the initial peak of egg production. The magnitude of this difference appears to be related to the worm burden at the peak of egg production. The possible mechanisms underlying density-dependent regulation of the fecundity of O. ostertagia are discussed.

Animals↗

PubMed1992

Estimation of relative fecundity in Eimeria tenella strains by a mixed infection method.

The relative fecundity of populations of Eimeria tenella was estimated by means of mixed infection using electrophoretic variation of glucose-phosphate isomerases (GPIs) as a genetic marker. A decoquinate-resistant strain with GPI-9 isozyme (DR-NIAH), a decoquinate-sensitive one with GPI-1 (DS-Iwate), and three decoquinate-resistant lines (No. 3, 4, and 5) derived from cross-fertilization between DR-NIAH and DS-Iwate, were used. The GPI phenotypes of the No. 3 and No. 4 lines are GPI-9, and that of No. 5 is GPI-1. Mixed infection experiments were performed between DR-NIAH and DS-Iwate, No. 3 and No. 5, and No. 4 and No. 5. DR-NIAH was predominant over DS-Iwate in the mixed infection, whereas, in single infections, the total oocyst output of DR-NIAH was similar to or less than that of DS-Iwate. Among three lines, No. 4 was predominant over No. 5, and No. 5 was predominant over No. 3 in the mixed infection. Relative fecundity between No. 3 and No. 5 and their patterns of oocyst output in single infections were similar to those in the mixed infection. In contrast, No. 5 produced more oocysts than No. 4 in single infections, suggesting that the oocyst production in the mixed infection may be influenced by the mutual interference or competition between the populations of E. tenella in the chicken caeca.

Animals↗

PubMed1997

The effects of natural Plasmodium falciparum infection on the fecundity and mortality of Anopheles gambiae s. l. in north east Tanzania.

Rodent and avian malaria parasites have been reported to have an adverse affect upon the reproductive fitness of mosquitoes. In order to determine whether fecundity reduction occurs in Anopheles gambiae s. l. infected with human malaria a study of wild-caught mosquitoes was undertaken in the Muheza district of north east Tanzania. Fully engorged, indoor resting females were collected daily for 4 months and maintained for 5 days. A sporozoite rate of 11.5% was detected for the whole collection and of those females alive on day 6 an additional 17.5% were infected with oocysts alone. Oocyst, but not sporozoite, infection resulted in a 17.5% reduction in egg production. Fecundity reduction was not caused by a reduction in bloodmeal size in infected females and no size difference was detected between oocyst-infected and uninfected females although sporozoite-positive females were significantly larger. Comparisons in parity between uninfected and infected groups indicate that infection does not affect survival beyond the first gonotrophic cycle as no changes in survivorship occurred as a result of sporozoite infection.

Animals↗

PubMed1981

The estimation of epistasis in components of fitness in experimental populations of drosophila melanogaster II. Assessment of meiotic drive, viability, fecundity and sexual selection.

An analysis of fitness components was performed on laboratory populations of Drosophila melanogaster bearing Curly and Plum marked second chromosome inversions with two genetic backgrounds. Selective differences between Curly, Plum, Curly-Plum, and wild phenotypes were partitioned into meiotic drive, viability, fecundity and mating success. Although no significant meiotic drive was detected, there were significant differences between genotypes in the other three components. Interlocus interactions in fertility and sexual selection components were measured, and statistics to quantify epistasis at these levels of fitness were devised. Significant fitness interactions between genes on the Curly and Plum inversions in viability, fecundity, and sexual selection were found. These results were qualitatively consistent with the maximum likelihood fitness estimates found previously. The expected allele frequency trajectories computed from the estimated components adequately fitted the observed selection trajectories.

Animals↗

PubMed1999

Phylogenetic status of a fecundity-enhancing Wolbachia that does not induce thelytoky in Trichogramma.

Wolbachia are widespread bacteria which infect a number of species of insects and other arthropods. They manipulate the reproduction of their hosts at their own advantage. In Trichogramma species all Wolbachia known so far induce thelytoky and form a monophyletic group in the B subdivision of Wolbachia. Here we show that some strains of the arrhenotokous species Trichogramma bourarachae harbour Wolbachia symbionts that locate in the A subdivision, and which do not induce thelytoky. Although the symbiont of T. bourarachae is closely related to Wolbachia that induce cytoplasmic incompatibility in other insects, no cytoplasmic incompatibilities were found in crosses involving infected and uninfected strains. In T. bourarachae the presence of this Wolbachia is associated with a higher fecundity of strains. Our results strongly suggest that Wolbachia are involved in this increased fecundity. Theoretical models on the evolution of host-Wolbachia interaction predict that a reduced effect on reproduction can be selected for if cost of infection is reduced. The effect in T. bourarachae should illustrate this prediction.

Animals↗

PubMed1996

The effects of chemical sympathectomy on contralateral testicular histology, fertility and fecundity in unilateral abdominal testes.

OBJECTIVE: To evaluate the effects of abdominal testis on ipsilateral and contralateral testicular histology, fertility and fecundity in rats which were chemically sympathectomized neonatally. MATERIALS AND METHODS: The study comprised 60 male albino rats, 30 receiving a placebo and 30 a chemical sympathectomic agent neonatally. When 21 days old, the two groups of 30 rats were each divided into three groups and underwent a control operation or abdominal fixation of one or both testes. After they were 8 weeks old, each male rat was housed with two fertile female rats for 25 days, after which their testes were harvested. Females were observed for an additional 25 days and any pregnancies and the number of offspring were recorded. Mean seminiferous tubular diameters and mean testicular biopsy scores were determined for each testis. RESULTS: Although fertility and fecundity rates and mean testicular biopsy scores were not significantly different, chemical sympathectomy prevented the decrease in mean seminiferous tubular diameters which occurred in the contralateral testis. CONCLUSION: Chemical sympathectomy protected contralateral testicular histology to some degree. Therefore, the sympathetic system may play a role in contralateral testicular deterioration.

Animals↗

PubMed1990

Fecundity of partially engorged female Dermacentor albipictus (Acari: Ixodidae) removed by cattle grooming.

Eight Hereford heifer calves were infested 28 times over a 64-d period with approximately 49,560 Dermacentor albipictus (Packard) larvae per calf. The fecundity of partially engorged and small, fully engorged female ticks, prematurely removed by grooming behavior of the calves, were compared. A total of 3,532 females of various engorged weights was collected from all calves, resulting in a mean female tick yield of 1.78% based on the number of larvae used for all infestations. The ratio of partially to fully engorged females was 1:16. Female oviposition success was 96%. The mean (+/- SE) values for female weight, number of larvae, and percentage larval eclosion of 50 partially engorged females that ranged in weight from 54 to 397 mg was 174 +/- 99, 1,272 +/- 931 and 85 +/- 14, respectively. The correlation between preoviposition weight and number of larvae from partially engorged females was highly significant (r = 0.95, P less than 0.0001). A prediction model (Y = -354.6 + 9.07X) showed that the preoviposition weight of partially engorged females and larval fecundity from a separate study was highly correlated (r = 0.92, P less than 0.0001). There was no significant difference between mean values of larval numbers and percentage eclosion for partially engorged and small, fully engorged females of similar weight.

Animals↗

PubMed1990

Longevity and fecundity of Musca domestica (Diptera: Muscidae) as a function of temperature.

Longevity and fecundity of adult house flies were determined at constant temperatures of 20, 25, 30, and 35 degrees C. At the four temperatures, respectively, the median mortality rates (1/days to 50% mortality) for females were 0.023, 0.041, 0.060, and 0.099 and for males were 0.029, 0.047, 0.066, and 0.085. The numbers of days for 50% of the eggs to be deposited for each temperature were 34.5, 21.3, 10.2 and 7.1, respectively. The total numbers of eggs deposited per female for each temperature were 184, 729, 709, and 506, respectively. Models were developed for longevity and fecundity and their distributions as functions of temperature.

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