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PubMed2003

Ovarian development and blood-feeding activity in Phlebotomus bergeroti Parrot (Diptera: Psychodidae) from Egypt.

The ovarian development and blood-feeding of Phlebotomus bergeroti were investigated using a laboratory colony derived from Egyptian flies. Most (89%) of the females in this colony were autogenous. The level of ovarian development observed at the time of blood-feeding varied between Christophers' stages IIB and V, indicating that vitellogenesis did not inhibit blood-feeding and that the females that ingested blood before their initial egg-laying were facultative, not obligatory, blood-feeders. The females ingested blood 2-8 days after they had emerged, the probability of a female taking an offered bloodmeal being highest between days 4 and 7 post-emergence. Blood-feeding significantly increased fecundity, significantly reduced the number of eggs that were not laid although apparently mature, and decreased the mean duration of the gonotrophic cycle by almost 1 day. Bloodmeals increased fecundity by stimulating the previtellogenic primary follicles of the autogenous females to precipitate yolk, possibly by initiating concurrent vitellogenesis in the primary and secondary follicles of the same ovarioles. Autogeny in P. bergeroti probably has little influence on the transmission of Leishmania parasites by this species.

Animals↗
PubMed2004

Direct selection on male attractiveness and female preference fails to produce a response.

BACKGROUND: Theoretical studies suggest that direct and indirect selection have the potential to cause substantial evolutionary change in female mate choice. Similarly, sexual selection is considered a strong force in the evolution of male attractiveness and the exaggeration of secondary sexual traits. Few studies have, however, directly tested how female mate choice and male attractiveness respond to selection. Here we report the results of a selection experiment in which we selected directly on female mating preference for attractive males and, independently, on male attractiveness in the guppy, Poecilia reticulata. We measured the direct and correlated responses of female mate choice and male attractiveness to selection and the correlated responses of male ornamental traits, female fecundity and adult male and female survival. RESULTS: Surprisingly, neither female mate choice nor male attractiveness responded significantly to direct or to indirect selection. Fecundity did differ significantly among lines in a way that suggests a possible sexually-antagonistic cost to male attractiveness. CONCLUSIONS: The opportunity for evolutionary change in female mate choice and male attractiveness may be much smaller than predicted by current theory, and may thus have important consequences for how we understand the evolution of female mate choice and male attractiveness. We discuss a number of factors that may have constrained the response of female choice and male attractiveness to selection, including low heritabilities, low levels of genetic (co)variation in the multivariate direction of selection, sexually-antagonistic constraint on sexual selection and the "environmental covariance hypothesis".

Animals↗
PubMed2006

Male gonadal dose of ionizing radiation delivered during X-ray examinations and monthly probability of pregnancy: a population-based retrospective study.

BACKGROUND: Male gonadal exposure to ionizing radiation may disrupt spermatogenesis, but its influence on the fecundity of couples has been rarely studied. We aimed to characterize the influence of male gonadal dose of ionizing radiation delivered during radiodiagnostic on the monthly probability of pregnancy. METHODS: We recruited a random sample of women who retrospectively described 1110 periods of unprotected intercourse beginning between 1985 and 1999 and leading either to a live birth or to no pregnancy; their duration was censored after 13 months. The male partner answered a telephone questionnaire on radiodiagnostic examinations. We assigned a mean gonadal dose to each type of radiodiagnostic examination. We defined male dose for each period of unprotected intercourse as the sum of the gonadal doses of the X-ray examinations experienced between 18 years of age and the date of discontinuation of contraception. Time to pregnancy was analysed using a discrete Cox model with random effect allowing to estimate hazard ratios of pregnancy. RESULTS: After adjustment for female factors likely to influence fecundity, there was no evidence of an association between male dose and the probability of pregnancy (test of homogeneity, p = 0.55). When compared to couples with a male gonadal dose between 0.01 and 0.20 milligrays (n = 321 periods of unprotected intercourse), couples with a gonadal dose above 10 milligrays had a hazard ratio of pregnancy of 1.44 (95% confidence interval, 0.73-2.86, n = 31). CONCLUSION: Our study provides no evidence of a long-term detrimental effect of male gonadal dose of ionizing radiation delivered during radiodiagnostic on the monthly probability of pregnancy during the year following discontinuation of contraceptive use. Classification errors due to the retrospective assessment of male gonadal exposure may have limited the statistical power of our study.

Adult↗
PubMed2005

Fertility in four regions spanning large contrasts in serum levels of widespread persistent organochlorines: a cross-sectional study.

BACKGROUND: Persistent organochlorine pollutants (POPs) may interfere with reproductive function but direct evidence in humans is very limited. METHODS: Fertility was examined in four regions with contrasting blood levels of POPs. Pregnant women and their partners in Warsaw (Poland), Kharkiv (Ukraine) and Greenland were consecutively enrolled during antenatal visits. Swedish fishermen and their spouses were recruited separately and independently of current pregnancy. Lipid adjusted serum concentrations of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (DDE) were available for both partners. Time to pregnancy interviews were obtained among 2269 women and 798 men provided a semen sample. RESULTS: Inuits had high levels of both POP markers, Swedish fishermen were high in CB-153 but low in DDE, men from Kharkiv were high in DDE and low in CB-153 while men from Warsaw were low in CB-153 and had intermediate DDE levels. Compared to Warsaw couples, fecundability was reduced among couples from Kharkiv [adjusted fecundability ratio (FR) 0.64 (95% CI 0.5-0.8)] and elevated in Swedish fishermen families [FR 1.26 (95% CI 1.0-1.6)]. Adjusted geometric means of sperm counts and morphology did not differ between regions while sperm motility was higher in men living in Warsaw. CONCLUSION: We observed regional differences in time to pregnancy and sperm motility that may be related to regional differences in POP blood levels, but other interpretations are also plausible. In particular, differences in access to safe contraception and in the prevalence of contraceptive failures are most likely to bias comparisons of time to pregnancy.

Biomarkers↗
PubMed2002

Effects of common-use pesticides on developmental and reproductive processes in Daphnia.

Daphnia magna were evaluated for use as a screen for pesticides that have been demonstrated to have estrogenic (o'p'-DDT, di-n-butyl phthalate, toxaphene), anti-androgenic (p'p-DDE, linuron), thyroid (acetochlor, alachlor, metribuzin), insulin (amitraz) or lutenizing hormone (2,4-D) activity in vertebrates, and to establish daphnid sensitivity to these compounds. Pesticides with unknown effects on vertebrate endocrine systems (chlorosulfuran, cyanazine, diflubenzuron, metolachlor, and diquat) were also evaluated. Compounds were assayed for six days at environmentally relevant concentrations ranging from 0.001 to 100 mirog/L, using female Daphnia and their offspring. Sublethal endpoints included offspring sex (sex determination), clutch size (fecundity), and adult size (growth rate). Toxaphene was the only compound that affected sexual differentiation, increasing male production. Daphnia fecundity declined with exposure to toxaphene, and daphnid growth rates were reduced by acetochlor exposure. Diflubenzuron, o'p'-DDT, and p'p-DDE significantly reduced Daphnia survival. No correlation existed between affected reproductive or developmental processes and specific endocrine systems or subsystems. Results from this study indicate that Daphnia make a good screen for assessing potential environmental impacts but are not a useful indicator of pesticide hormonal activity in vertebrates. This assay consistently detected sublethal but ecologically relevant effects of these pesticides on Daphnia at environmentally relevant concentrations typically below their listed EC50 value.

Animals↗
PubMed2003

Endometriosis and reproductive disorders.

The classic concept of endometriosis as a cause of infertility is challenged. Traditionally, both surgical and medical therapy have focused on alleviation of symptoms, prevention of disease progression, and promotion of fertility. In spite of significant developments in medical and surgical approaches, the optimal therapy for treating endometriosis-associated infertility has yet to be established. The relationship between prevalence of fecundity and stage of the disease was studied according to the type of management. Of 151 women who were consecutively proved by laparoscopy to have endometriosis stage I and II, operative laparoscopy was performed in 49, medical treatment in 59, and expectant management in 43 cases. During a 24-month period, the cumulative pregnancy rates were 36.7%, 30.5%, and 20.9%, respectively. Survival analysis over the 20 weeks of pregnancy showed that the probability of carrying the pregnancy beyond this week was 30.6%, 25.4%, and 16.2%, respectively. Of 64 patients with advanced disease, 34 (53%) became pregnant during the 2-year follow-up period. A significantly increased pregnancy rate was found for the first year as compared to the second (76% vs. 24%). The existence of adhesions affected adversely the outcome of the treatment when early achievement of pregnancy is considered. Diagnosis and treatment of endometriosis was beneficial for the infertile women. Laparoscopic surgery seems to be the best treatment in these cases, as it increases the fecundity and involves minimal risk.

Adult↗
PubMed2006

[PCR-SSCP polymorphism of FSHbeta gene and its relationship with prolificacy of Jining grey goats].

The follicle-stimulating hormone beta-subunit (FSHbeta) gene was studied as a candidate gene for the prolificacy in Jining Grey goats. According to the sequence of ovine FSHb gene, nine pairs of primers were designed to detect single nucleotide polymorphisms of 5' regulatory region, exon 1 and exon 2 of FSHbeta gene in both high fecundity breed (Jining Grey goat) and low fecundity breeds (Liaoning Cashmere goat, Boer goat and Angora goat) by PCR-SSCP. The results indicated that the homology of nucleotide sequence of this fragment between goat and sheep was 98 percent. Only the products amplified by primer P9 displayed polymorphism. Three genotypes (AA, AB and AC) were detected in Jining Grey goats and Liaoning Cashmere goats. Three genotypes (AA, CC and AC) were detected in Boer goats. Six genotypes (AA, BB, CC, AB, AC and BC) were detected in Angora goats. Sequencing revealed a G-->A mutation at 94 bp of exon 2 of FSHbeta gene in the BB genotype in comparison to the AA genotype and a C-->T mutation at 174 bp of exon 2 of FSHbeta gene in the CC genotype in comparison to the AA genotype. The former mutation resulted in an amino acid change: alanine-->threonine, and the latter mutation did not cause any amino acid change. Genotype frequency of AA, AB and AC was 0.686, 0.137 and 0.177 in Jining Grey goats, respectively. The does with genotype AA had 0.78 (P<0.05) or 0.64 (P<0.05) kids more than those with genotype AB or AC in Jining Grey goats, respectively.

Amino Acid Sequence↗
PubMed2001

Peripubertal paternal EtOH exposure.

Fetal alcohol syndrome usually implies effects on the offspring of maternal EtOH consumption during gestation, with fewer reports addressing the impact of paternal exposure on the progeny. One previous report has dealt with the impact of EtOH exposure on peripubertal male rats as a model of teenage drinking and the deleterious effects on the offspring. We report here findings examining the effect of 2 mo of EtOH feeding on male animals as they progressed through puberty on their ability to impregnate EtOH-naive female rats and characteristics of the subsequent litters. The EtOH-imbibing fathers weighed significantly less than pairfed controls and animals ingesting a non-EtOH liquid diet ad libitum. Nevertheless, they were able to mate successfully, although fecundity was significantly reduced. The number of successful pregnancies, defined as carried to term, was diminished from 92% in controls to 75% in EtOH-fed animals (p < 0.05). There was increased paternal testicular oxidative injury demonstrated by enhanced lipid peroxidation, protein oxidation, and decreased ratio of reduced to oxidized glutathione. The litter size of the EtOH-exposed males was reduced by 46%. The average litter size was 12.4+/-1.5 pups/litter in ad libitum animals, virtually identical to the 12.5+/-0.6 pups/litter in the pair fed controls. This is in sharp contrast to the 6.7+/-0.1 pups/litter from the paternal EtOH matings (p < 0.001). There was an increase in the average individual weight of pup offspring of paternally EtOH-exposed animals (p < 0.01 vs pair-fed controls and p < 0.05 vs ad libitum). Curiously, the male-to-female pup ratio was altered with a higher preponderance of male offspring from EtOH-fed fathers. There were no gross malformations noted among the pups. Insulin-like growth factor-1 levels in the pups at 10 d of age were unaltered between the groups. However, leptin was significantly elevated in the EtOH offspring. It appears that chronic EtOH exposure in the peripubertal fathers subsequently decreases fecundity and that this may be mediated by testicular oxidative injury, perhaps leading to accelerated germ cell apoptosis.

Animals↗
PubMed1987

Antifertility effects of some sulphonamides and related compounds and their accumulation in the epididymides of male rats.

Nineteen sulphonamides and related drugs were screened for their antifertility effects in male rats. They were suspended in corn oil and fed orally to rats at 10 times the human dose for a period of 6 months. Of the 19 compounds tested, sulphamethazine, sulphapyridine, dapsone, sulphamethoxypyridazine, sulphaguanidine, sulphathizole, sulphamerazine and sulphadimethoxine reduced fecundity of male rats to 34.3, 37.6, 38.3, 53.6, 55.6, 58, 75 and 78.6% of control, respectively. The fall in fecundity was due to a reduction in the number of embryos compared with the number of corpora lutea per pregnant female, and, in some cases, was associated with a fall in epididymal sperm concentration and motility. Some of these compounds accumulated in the cauda epididymidis at concentrations equal to or higher than the free drug concentrations in the blood. It is proposed that the antifertility effects of some of these compounds may in part be mediated through a direct effect on epididymal stored spermatozoa, hence compromising some processes vital for fertilization.

Animals↗
PubMed1988

Induction of ovulation in chronically hypophysectomized Booroola ewes.

Booroola Merino ewes, with (F+; N = 17) and without (++; N = 13) a copy of the fecundity gene were hypophysectomized and 6 weeks later were given an i.m. injection of PMSG (high, medium or low dose) followed by hCG. The induced ovulation rates were observed laparoscopically. Ovulation rates were significantly higher (P less than 0.01) in Booroola F+ ewes than in ++ ewes (8.00 +/- 1.66 s.e.m. vs 3.62 +/- 1.10 respectively). This suggests that the high fecundity of the Booroola ewe may be due primarily to ovarian rather than pituitary factors.

Animals↗
PubMed1988

Stimulus requirements for pregnancy initiation in the golden hamster (Mesocricetus auratus) change with age and parity.

Hamsters were mated repeatedly at 60, 180, 300 and 420 days of age or once during their lifetime at one of these ages. Copulatory stimulation was varied both for number of ejaculations (2 versus 14) and amount of vaginocervical stimulation (5 versus 50-60 intromissions). Two ejaculations provided sufficient spermatozoa to maximize litter size for all age and parity classes tested. Differences in fecundity depended on the amount of vaginocervical stimulation received. Higher levels of vaginocervical stimulation increased littering success at 300 and 420 days for nulliparous females and at 180, 300 and 420 days for multiparous females. Females which did not deliver litters did not show a cessation of oestrous cycles which characteristically follows the induction of a luteal phase. The decreased fecundity observed with increasing age or parity therefore resulted from a change in sensitivity to the stimulus conditions necessary to activate the neuroendocrine arc for establishment of pregnancy.

Aging↗
PubMed1989

Blood flow in the ovaries and ovarian follicles of Romanov and Préalpes-du-Sud ewes.

Radioactive microspheres (15 microns diameter) were used to measure capillary blood flow rates in the ovaries and ovarian follicles (Qf) in high fecund Romanov and low fecund Préalpes-du-Sud ewes at the preovulatory stage of the oestrous cycle. Additionally, assessments of the percentage of arterial blood passing through ovarian arterio-venous anastomoses were obtained. The mean +/- s.e.m. Qf per unit volume of theca [ml/min) x 10(4)/mm3) for non-atretic follicles in Romanov ewes was significantly greater (P less than 0.05) than that in Préalpes ewes (365.8 +/- 42.4, n = 19, compared with 241.3 +/- 30.1, n = 14). For each breed, the mean Qf value for non-atretic follicles was 8-10 times greater than that for atretic follicles. In Romanov ewes, total Qf [ml/min) x 10(4) and Qf per unit volume of theca was greatest in small-sized follicles (3.1-5.0 mm) while in Préalpes ewes, maximum flow was attained in larger-sized follicles (5.1-7.0 mm). The elevated Qf in small-sized follicles in Romanov ewes may be conducive to more follicles achieving maturation at a smaller diameter in this breed than occurs in the Préalpes ewes. The absence of flow through ovarian arterio-venous anastomoses in the Romanov, but not in the Préalpes, ewes suggests different mechanisms for controlling the distribution of the total ovarian blood supply in the 2 breeds.

Animals↗
PubMed1993

Effects of tamoxifen on the fertility of male rats.

The effects of oral administration of tamoxifen (a synthetic non-steroidal anti-oestrogen) at doses of 40, 200 or 400 micrograms kg-1 day-1 on the circulating concentrations of LH, FSH, prolactin, testosterone and oestradiol, weights of pituitary, testes, secondary sex organs and the fertility of adult male rats were determined. The drug was administered per os daily, for up to 90 days. The fertility of rats treated with tamoxifen for 60, 70, 80 or 90 days was assessed by allowing them to mate with normal female rats of proven fertility. Tamoxifen at 40 micrograms kg-1 day-1 reduced concentrations of testosterone in plasma but had no affect on LH, FSH, prolactin and oestradiol concentrations, and the weights of pituitary, testes, epididymides, ventral prostate and seminal vesicles. Tamoxifen at 40 micrograms kg-1 day-1 reduced potency, fecundity, the number of implantation sites, the fertility index and litter size. Tamoxifen at 200 and 400 micrograms kg-1 day-1 reduced the concentrations of LH and testosterone in plasma and the weights of testes and secondary sex organs compared with controls. Tamoxifen at 400 micrograms kg-1 day-1 was most effective in reducing the number of viable pups, the litter size (< or = 1) and the fecundity (20%). The potency of treated rats (a measure of the presence of an ejaculate) was significantly decreased when compared with controls, but copulation was apparently not affected as mated female rats showed a constant dioestrous phase. Histology of the testes revealed disorganization of the cytoarchitecture of the tubules with obliterated lumen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

A new method of estimating the pollen dispersal curve independently of effective density.

We introduce a novel indirect method of estimating the pollen dispersal curve from mother-offspring genotypic data. Unlike an earlier indirect approach (TwoGener), this method is based on a normalized measure of correlated paternity between female pairs whose expectation does not explicitly depend on the unknown effective male population density (d(e)). We investigate the statistical properties of the new method, by comparison with those of TwoGener, considering the sensitivity to reductions of d(e), relative to census density, resulting from unequal male fecundity and asynchronous flowering. Our main results are: (i) it is possible to obtain reliable estimates of the average distance of pollen dispersal, delta, from indirect methods, even under nonuniform male fecundity and variable flowering phenology; (ii) the new method yields more accurate and more precise delta-estimates than TwoGener under a wide range of sampling and flowering scenarios; and (iii) TwoGener can be used to obtain approximate d(e) estimates, if needed for other purposes. Our results also show that accurately estimating the shape of the tail of the pollen dispersal function by means of indirect methods remains a very difficult challenge.

Flowers↗
PubMed2001

Females receive a life-span benefit from male ejaculates in a field cricket.

Mating has been found to be costly for females of some species because of toxic products that males transfer to females in their seminal fluid. Such mating costs seem paradoxical, particularly for species in which females mate more frequently than is necessary to fertilize their eggs. Indeed, some studies suggest that females may benefit from mating more frequently. The effect of male ejaculates on female life span and lifetime fecundity was experimentally tested in the variable field cricket, Gryllus lineaticeps. In field crickets, females will mate repeatedly with a given male and mate with multiple males. Females that were experimentally mated either repeatedly or multiply lived more than 32% longer than singly mated females. In addition, multiply mated females produced 98% more eggs than singly mated females. Because females received only sperm and seminal fluid from males in the experimental matings, these life-span and fecundity benefits may result from beneficial seminal fluid products that males transfer to females during mating. Mating benefits rather than mating costs may be common in many animals, particularly in species where female mate choice has a larger effect on male reproductive success than does the outcome of sperm competition.

Animals↗
PubMed2001

[Effects of food deprivation levels on the oogenesis of Panstrongylus megistus].

The effects of various levels of food deprivation on the oogenesis of P. megistus was studied. Immediately after the imaginal ecdysis, six groups (GI to GVI) of 15 couples each were formed. Each group was fed as follows: GI -- on days 5 and 25; G-II -- on days 5 and 35; GIII -- on days 5 and 45; GIV -- on day 20; GV -- on day 30; GVI -- on day 40 after the imaginal ecdysis. After the established fasting period, all groups were fed fortnightly. Fifteen couples were in the control group (CG), which was fed on the day 5 after the imaginal ecdysis and subsequently fortnightly. GI produced more eggs, matings and fertile eggs. GII had longer life spans, higher fecundity and hatchings. GIII had a shorter life span, low fecundity, fertility and hatchings. GVI presented the least favorable results for all parameters, except for the pre-oviposition period. The CG had the best results in all parameters when compared with all experimental groups.

Animals↗
PubMed1992

The susceptibility of adult schistosomes to immune attrition.

Mouse infection models are described that demonstrate reduction of egg production in Schistosoma haematobium infections and both worm loss and reduced fecundity in S. bovis infections. Neither phenomenon could be shown in S. mansoni infected mice. The immunological basis for these anti-adult responses was inferred by comparison with infections in T-cell deprived mice and by serum transfer of the ability to reduce a S. bovis worm burden into immunocompromised hosts. Vaccination with irradiation attenuated parasites was also shown to have consequences for the adults of a challenge infection of S. haematobium and S. bovis specifically. Prior vaccination resulted in an abrogation of the anti-fecundity and adult worm elimination that occurred in non-vaccinated similarly infected mice. These models are being used to define the targets and mechanisms involved in anti-adult attrition. A serological assay, quantitation of a circulating antigen (CAA) has been assessed for its ability to measure worm burdens of different species of schistosome in mice. This assay will be used to question whether anti-adult immunity contributes to the pattern of infection with S. mansoni and S. haematobium in man.

Animals↗
PubMedDate not supplied

Effect of temperature on different stages of Romanomermis iyengari, a mermithid nematode parasite of mosquitoes.

The effect of temperature (20 degrees-35 degrees C) on different stages of Romanomermis iyengari was studied. In embryonic development, the single-cell stage eggs developed into mature eggs in 4.5-6.5 days at 25-35 degrees C but, required 9.5 days at 20 degrees C. Complete hatching occurred in 7 and 9 days after egg-laying at 35 and 30 degrees C, respectively. At 25 and 20 degrees C, 85-96% of the eggs did not hatch even by 30th day. Loss of infectivity and death of the preparasites occurred faster at higher temperatures. The 50% survival durations of preparasites at 20 and 35 degrees C were 105.8 and 10.6 hr respectively. They retained 50% infectivity up to 69.7 and 30.3 hr. The duration of the parasitic phase increased as temperature decreased. Low temperature favoured production of a higher proportion of females which were also larger in size. The maximum time taken for the juveniles to become adults was 14 days at 20 degrees C and the minimum was 9 days at 35 degrees C. Oviposition began earlier at higher temperature than at lower temperature. However, its fecundic period was shorter at 20 degrees C than at 35 degrees C indicating enhanced rate of oviposition at 20 degrees C. Fecundity was adversely affected at 20 degrees C and 35 degrees C. It is shown that the temperature range of 25 degrees-30 degrees C favours optimum development of R. iyengari.

Animals↗

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