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At least 811 records · Page 45Linked to original sources
PubMed1979

Periovulatory gonadotrophin and ovarian steroid patterns in sheep of breeds with differing fecundity.

Plasma hormone concentrations before and during luteolysis (induced by injection of a prostaglandin analogue on Day 10 or 11 of the cycle), during the period of preovulatory follicle growth and ovulation were examined in sheep with known differences in ovulation rate (Romanov, Préalpes, Romanov x Préalpes cross, Ile de France). The number of CL at the time of treatment and the ovulation rate in the ensuing cycle were established by endoscopy. Plasma concentrations of FSH, LH, progesterone and total oestrogen were measured by radioimmunoassays in the 3 days before PG injection, then hourly for the 24 h after PG injection and 2-hourly for a further period up to about 100 h after PG injection. The onset and duration of oestrus were also recorded. Although breed differences were observed for many of the features studied, only the intervals between oestrus and the LH peak and between PG injection and the LH peak were significantly correlated with ovulation rate.

Animals↗
PubMed1979

The role of the seminal vesicles, coagulating glands and prostate glands on the fertility and fecundity of mice.

Female mice were allowed to mate with males which had been sham-operated (Group 1); had seminal vesicles, coagulating glands and ventral and dorsal prostate glands removed (Group 2); had the seminal vesicles removed (Group 3); had the coagulating glands removed (Group 4) or had the ventral and dorsal prostate gland removed (Group 5). The pregnancy rate was normal in Groups 1 and 4, severely reduced in Groups 2 and 3 and less so in Group 5. Litter size was reduced in Groups 2 and 3 but not in Group 5. It is suggested that the seminal vesicles and possibly the prostate glands are important in the production of young in mice.

Animals↗
PubMed1982

Improvement of sheep fecundity by treatment with antisera to gonadal steroids.

Sera from sheep immunized against oestrone (Group E1), oestradiol (Group E2), androstenedione (Group A) and testosterone (Group T) were given to ewes singly or as a mixture (Group M) of all 55 types as a single intravenous injection at the time of the start of mating. The number of lambs produced, the numbers of eggs shed and the display of oestrus were recorded. The ovulation rates were 1.8 in Group E1, 2.1 in Group E2, 1.6 in Group A, 1.8 in Group T and 2.1 in Group M compared with 1.3 for the controls (P, variation among groups, less than 0.001) in the first oestrous cycle. The effect persisted in those animals not conceiving to the first mating--1.3 in Group A, 1.8 in Group E1, 1.9 in Group E2 and 2.0 in Group M compared with 1.3 for the controls; all of the ewes in Group T conceived to mating at a single oestrus. The mean number of lambs born alive per ewe treated was 1.1 for Group A, 1.3 for Group E1, 1.3 for Group E2, 1.5 for Group T, 1.5 for Group M and 1.0 for the controls. The increase in the number of lambs born was due to a higher proportion giving birth to twins (P less than 0.01); no ewe gave birth to triplets. High conception rates were recorded for all treatments.

Androstenedione↗
PubMed1984

Plasma gonadotrophin concentrations during the oestrous cycle and after ovariectomy in two breeds of sheep with low and high fecundity.

LH and FSH concentrations were measured during the oestrous cycle in two local Moroccan breeds of sheep with low (Timahdite: 1 CL/cycle) and high (D'man: 3 CL/cycle) ovulation rates. Twenty ewes were used from each breed and blood was collected at 3- or 6-h intervals from 5-4 days before oestrus up to Day 14 of the new cycle, when 4 D'man and 4 Timahdite ewes were ovariectomized. After surgery, blood sampling was continued at 6-h intervals for 2 weeks. (1) The mean basal concentration of LH, the maximum value of the preovulatory LH surge and the area under the curve were significantly higher (P less than 0.05) in Timahdite than in D'man ewes. (2) The pattern of FSH in each breed showed no clear basal level but a periodic succession of peaks with variable amplitudes. The first and highest peak corresponded with the preovulatory LH surge. The 2nd peak followed immediately after the first peak and reached its maximum 24-30 h later. The 3rd peak was flatter and occurred around Day 6 of the cycle. The 4th peak was observed around Day 10 of the cycle and showed the lowest amplitude. The 5th and last peak occurred 66-87 h before the next preovulatory surge. (3) FSH concentrations were higher in the prolific D'man than in Timahdite ewes around the time of oestrus (pro-oestrous peak, preovulatory surge and the 2nd peak). The drop in FSH concentrations observed in D'man ewes before the preovulatory surge was more pronounced and started later.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Ovarian follicular activity in Booroola lambs with and without a fecundity gene.

The ovaries of 3-month-old Booroola lambs which were heterozygous carriers of a major gene (F) influencing the ovulation rate in mature ewes (i.e. F + lambs) were compared to those ofsimilarly-aged Booroola lambs which were non-carriers of the F-gene (i.e. ++ lambs). The ovaries of the F + Booroola lambs were significantly lighter (P less than 0.01) than those of ++ lambs even though the mean +/- s.e.m. number of follicles (greater than or equal to 1 mm diam.) in the F + lambs was greater than that in the ++ lambs (i.e. F + lambs, 30.2 +/- 2.5 follicles; ++ lambs, 18.4 +/- 1.2 follicles; P less than 0.01). In granulosa cells from non-atretic follicles (greater than or equal to 1 mm diam.) from F + and ++ Booroola lambs, FSH (NIAMDD-FSH-S16) doses of 100 and 1000 ng/ml caused significant stepwise increases (P less than 0.05) in cyclic adenosine 3',5'-monophosphate (cAMP) production compared to that achieved at FSH doses of 0 and 1 ng/ml or at any FSH dose in cells from atretic follicles. However, no significant differences in FSH-induced cAMP production were noted with regard to Booroola genotype or follicular diameter. None of the granulosa cell preparations from non-atretic follicles of 1-2.5 mm diameter from F + lambs (N = 13) or from non-atretic follicles of 1-4.5 mm diameter from ++ lambs (N = 16) responded to LH (NIAMDD-LH-S24; 10 or 1000 ng/ml) to produce significantly more cAMP than did the controls. In contrast, the granulosa cell preparations from non-atretic follicles of 3-4.5 mm diameter from F + lambs (N = 4) and from non-atretic follicles of greater than or equal to 5 mm diameter of ++ lambs (N = 4) produced significantly more cAMP (P less than 0.05) in response to LH (1000 and/or 10 ng/ml) relative to that in the controls. The theca interna from follicles of lambs of both genotypes had functional LH receptors as judged by the androstenedione responses to exogenous LH although no genotypic differences were noted. In F + lambs, the follicular fluid concentrations of testosterone but not oestradiol (i.e. in 1-4.5 mm diam. follicles) and granulosa cell aromatase activity (i.e. in 3-3.5 mm diam. follicles) were significantly higher (both P less than 0.05) than in corresponding follicles or cells from ++ lambs. Collectively the results suggest that the Booroola F-gene influences the composition and function of sheep ovaries before puberty.

Animals↗
PubMed1989

Effects of oestradiol-17 beta, progesterone or bovine follicular fluid on the plasma concentrations of FSH and LH in ovariectomized Booroola ewes which were homozygous carriers or non-carriers of a fecundity gene.

The plasma concentrations of FSH and LH were measured in ovariectomized Booroola FF and ++ ewes before and after treatment with subcutaneous implants of oestradiol-17 beta (0, 2 or 8 cm Silastic capsules; 5 ewes/genotype per dose) or progesterone (0, 1 or 3 Silastic envelopes; 5 ewes/genotype per dose) or subcutaneous injections of steroid-free bovine follicular fluid (bFF; 0, 0.5, 1.0, 2.5 or 5 ml; 4 ewes/genotype per dose). During the first 50 h after implantation of oestradiol or progesterone, or the first 24 h after bFF treatment, the FSH and LH concentrations in plasma were not different between the genotypes although there were significant effects of the steriods and bFF with respect to dose (P less than 0.05). At 6 days after steroid implantation, no gene-specific effects were noted for the plasma concentrations of FSH although significant effects of dose of oestradiol (P less than 0.01) but not progesterone were noted. Also at 6 days after steroid implantation, no gene-specific differences in the pulsatile patterns (i.e. peak frequency or amplitude) of plasma LH concentrations were noted although there were significant effects of steriod dose (P less than 0.05) on frequency and/or amplitude. It is concluded that the higher ovulation-rate in FF than ++ Booroola ewes is unlikely to be due to gene-specific differences in the sensitivity of the hypothalamic-pituitary axis to ovarian hormones.

Animals↗
PubMed1991

Plasma LH, FSH and testosterone concentrations in adult rams which were homozygous carriers or non-carriers of the Booroola fecundity gene.

No gene-specific differences were found with respect to LH or testosterone pulsatile secretion (over 12 h), or in 12 hourly mean FSH concentrations in adult Booroola FF and ++ rams. Also, no differences between genotypes in the LH response to an injection of testosterone propionate, the FSH response to an infusion of bovine follicular fluid, or the testosterone response to injections of PMSG were noted. However, during the phase of seasonal testicular development, mean testosterone pulse amplitude (over 12 h) and the FSH response to 25 micrograms GnRH were higher in FF than in ++ rams (P less than 0.05); there were also significant effects of sire (P less than 0.05 in FF genotype only) and litter size (P less than 0.05) on testosterone pulse amplitude and GnRH-stimulated FSH release, respectively. During the breeding season, mean LH, but not FSH, concentrations were higher in FF than in ++ rams, after an injection of 0.5 micrograms GnRH; LH release was not affected by sire or litter size (P greater than 0.05). Long-term studies revealed that the FF rams were born in significantly larger litters, they weighed significantly less than ++ rams (P less than 0.05), and that bodyweight was significantly correlated (P less than 0.05) with litter size. There were no differences in testis size, and testis size was not significantly correlated with bodyweight. There was a strong tendency (P = 0.056) for overall mean FSH concentrations, measured weekly for 9 months, to be highest more often in FF than in ++ rams.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of castration on plasma concentrations of luteinizing hormone and follicle-stimulating hormone in adult Merino rams which were homozygous carriers or non-carriers of the Booroola fecundity gene.

Before castration, the mean plasma concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) did not differ between FF and ++ Booroola rams. After castration, mean LH and FSH concentrations increased after 8 h, and for the next 14 days the rate of increase in FSH, but not LH, secretion was significantly faster in FF than in ++ rams (P less than 0.05). Mean FSH concentrations over this period were significantly higher in FF than in ++ rams (P less than 0.05). In both genotypes, the ranked FSH values did not significantly change their order over time, i.e. a significant within-ram effect was noted (P less than 0.05). Repeated-measures analysis of variance indicated a significant effect of genotype on mean FSH secretion (P less than 0.05) and a significant effect of sire in the FF (P less than 0.05), but not the ++ (P = 0.76), genotype. From Day 28 to Day 58 after castration, FSH and LH concentrations were variable and no overall increases in concentrations were observed. The mean concentrations of both hormones over this period were not related to genotype. There were no gene-specific differences in pulsatile LH secretion 14 weeks after castration. However, the mean LH, but not FSH, response to a bolus injection of 25 micrograms of gonadotrophin-releasing hormone (GnRH) was significantly higher in FF than in ++ rams (P less than 0.05) and this was not significantly affected by sire. These studies support the hypothesis that the F gene is expressed in adult rams, in terms of pituitary responsiveness to an injection of GnRH and to the removal of the testes, but it is not clear from this study whether the influence of sire is related to or independent of the apparent gene-specific differences.

Animals↗
PubMed2004

Fixation probability favors increased fecundity over reduced generation time.

The cornerstone of population genetics is a probabilistic understanding of the ultimate fate--survival or extinction--of rare mutations. If a mutation is beneficial, it enables its carrier to reproduce faster than native wild-type individuals. In classic derivations and in the considerable body of research that has followed, "faster" has been defined mathematically to mean "able to produce more surviving offspring per generation." Many organisms, however, may increase their reproductive rate by producing the same number of offspring in a shorter generation time: a mutant bacterium, for example, may complete the cell cycle and produce two offspring more quickly than the wild type. We find that the ultimate fixation probability of a mutation conferring a shorter generation time differs from that of a mutation conferring more offspring by a factor of 2 ln(2)-nearly 40%. This predicts a reduction in the overall substitution rate for any mutation that decreases the generation time: fixation probability is biased toward increased offspring number.

Amino Acid Substitution↗
PubMed1992

[The artificial fecundation in Japanese monkeys (Macaca fuscata) by induced ovulation and artificial insemination in nonmating season].

Induced ovulation trials by PMSG-hCG administration were conducted in eleven female Japanese monkeys showing neither bleeding nor ovulation in nonmating season. The ovulation was confirmed by the laparoscopic observation in nine of the 11 females. Artificial inseminations were performed in these 9 females by the injection of semen collected by the penile electrode approach. The semen was injected into the uterine cervix in 6 females or the uterine cavity in 3 females. A gestational sac was confirmed on the ultrasonic diagnostic apparatus 19 days after ovulation in one of the 3 females inseminated into the uterine cavity. The pregnancy, however, could not be maintained.

Animals↗
PubMedDate not supplied

Fecundity changes induced by low-doses of gamma radiation on Biomphalaria straminea (Dunker, 1848).

A population of 420 snails Biomphalaria straminea, an intermediate host of Schistosoma mansoni, received gamma-rays obtained from a 60Co source in low-doses (0/2,5/5/7,5/10/15/20 and 25 Gy); half population was kept in colonies (allowing cross fertilization) and the other half was maintained in sexual isolation (allowing self fertilization). Results showed that 15 Gy stimulates the fertility of both groups but the colonies were more sensitive and at this dose its fertility overpasses the control group dose. The possible hormonal role played in the observed phenomena is under investigation.

Animals↗
PubMedDate not supplied

Life cycle and fecundity analysis of Lutzomyia shannoni (Dyar) (Diptera: Psychodidae).

The life cycle of Lutzomyia shannoni (Dyar), was described for laboratory conditions with maximum daily temperature of 27-30 degree C, minimum daily temperatures of 22-27 degree C and relative humidity between 87-99%. Life cycle in each stage was as follows: egg 6-12 days (ave, 8.5 days); first stage larva 5-13 days (ave. 9.6 days); second stage larva 4-13 days (ave. 9.2 days); third stage larva 5-19 days (ave. 11.8 days); fourth stage larva 7-37 days (ave. 19.9 days); pupa 7-32 days (ave. 15.2 days). The life expectancy of adults ranged from 4 to 15 days (ave. 8.6 days). The entire egg to adult period ranged from 36 to 74 days (ave. 54.6 days). On average, each female oviposited 22.7 eggs; the average egg retention per female was 24.3 eggs.

Animals↗