Pituitary gonadotrophins in Booroola and control Merino sheep

Robertson, David; Ellis, Susan; Foulds, Lynda M.; Findlay, Jock K.; Bindon, B. M.

doi:10.1530/jrf.0.0710189

Cited by 42 publications

(26 citation statements)

References 14 publications

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“…The high fecundity of the Booroola Merino flock (NewtonTurner, 1978) is due to a major gene that is responsible for an increased ovulation rate (Bindon, 1984 (Davis et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

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The effect of the Booroola (FecB) gene on peripheral FSH concentrations and ovulation rates during oestrus, seasonal anoestrus and on FSH concentrations following ovariectomy in Scottish Blackface ewes

Boulton

Haley²,

Springbett³

et al. 1995

Reproduction

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“…The high fecundity of the Booroola Merino flock (NewtonTurner, 1978) is due to a major gene that is responsible for an increased ovulation rate (Bindon, 1984 (Davis et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

“…Despite the finding of genetic markers of the Fee gene (Montgomery et al, 1993;Lanneluc et al, 1994) (Bindon, 1984;McNatty et al, 1987), it has not been proved that these are responsible for the differences in ovulation rate between genotypes (Driancourt and Fry, 1990). At (McNatty et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

The effect of the Booroola (FecB) gene on peripheral FSH concentrations and ovulation rates during oestrus, seasonal anoestrus and on FSH concentrations following ovariectomy in Scottish Blackface ewes

Boulton

Haley²,

Springbett³

et al. 1995

Reproduction

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“…The physiological mechanism involved in the expression of the fecundity of the Booroola ewe is still unclear. The increased number of follicles that mature and ovulate in each oestrous cycle in the Booroola ewe may result from differences in gonadotrophin secretion or from differences within the follicle itself (Bindon, 1984).…”

Section: Introductionmentioning

confidence: 99%

Induction of ovulation in chronically hypophysectomized Booroola ewes

Fry¹,

Clarke

Cummins

et al. 1988

Reproduction

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Summary. 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 < 0\m=.\01) in Booroola F+ ewes than in ++ ewes (8\m=.\00 \m=+-\1\m=.\66s.e.m. vs 3\m=.\62\m=+-\ 1 \ m= . \ 1 0 respectively). This suggests that the high fecundity of the Booroola ewe may be due primarily to ovarian rather than pituitary factors.

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“…The gene-specific differences in LH secretion arise from an increased LH pulse amplitude, with no change in pulse frequency. Pituitary LH concentrations are similar in all genotypes, whereas F gene carriers have higher pituitary FSH contents (2,4). Moreover, McNatty et a/.…”

mentioning

confidence: 91%

Pituitary Binding Sites for Gonadotrophin‐Releasing Hormone in Booroola Merino Ewes which were Non‐Carriers or Homozygotes of the Fecundity Gene F

Fleming

Lun

Smith

et al. 1990

J Neuroendocrinology

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Pituitary binding sites for gonadotrophin-releasing hormone (GnRH) were examined in Booroola ewes on Days 4 and 12 of the oestrous cycle and more than 12 months after ovariectomy. No significant differences were observed in the affinity of the binding sites for [lZ51]D Ala6, des Gly" GnRH ethylamide, in non-carriers ( + + ) or homozygotes of the fecundity gene (FF), in intact or ovariectomized animals (overall Ka=(1.8f0.1) x lo9 M-'; mean+SEM, n=67). In + + ewes, the number of GnRH binding sites on Day 4 of the oestrous cycle (0.199f0.025 fmol/mg pituitary, n=8) was significantly greater (P<0.05) than on Day 12 (0.107k0.012 fmol/mg pituitary, n=12). In contrast in FF ewes the number of binding sites on Days 4 and 12 were similar (Day 4: 0.119k0.030, n=8; Day 12: 0.092k0.014, n=10). On Day 4, but not Day 12, the binding site numbers were significantly higher in + + compared with FF pituitaries (P<0.05). Likewise on Day 4, but not Day 12, the plasma concentrations of follicle-stimulating hormone were significantly higher (P<0.005) in FF (1.60f0.15 nglml) than + + ewes (0.96f0.10 ng/ml). After ovariectomy, no gene-specific differences in binding site numbers were noted despite significantly higher plasma follicle-stimulating hormone concentrations in FF animals. No gene-specific differences in plasma luteinizing hormone concentrations were observed in these animals on Days 4 or 12, or after ovariectomy. Moreover, luteal phase plasma progesterone concentrations were also similar between + + and FF ewes.We conclude that the gene-specific differences in pituitary responsiveness to GnRH and in pituitary gonadotrophin output are unlikely to be due to differences in GnRH receptor binding affinities.

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Pituitary gonadotrophins in Booroola and control Merino sheep

Cited by 42 publications

References 14 publications

The effect of the Booroola (FecB) gene on peripheral FSH concentrations and ovulation rates during oestrus, seasonal anoestrus and on FSH concentrations following ovariectomy in Scottish Blackface ewes

The effect of the Booroola (FecB) gene on peripheral FSH concentrations and ovulation rates during oestrus, seasonal anoestrus and on FSH concentrations following ovariectomy in Scottish Blackface ewes

Induction of ovulation in chronically hypophysectomized Booroola ewes

Pituitary Binding Sites for Gonadotrophin‐Releasing Hormone in Booroola Merino Ewes which were Non‐Carriers or Homozygotes of the Fecundity Gene F

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