Bioscientifica Proceedings

Summary. Synthesis of biologically active LH is complex, due in part to its hetero-dimeric subunit structure and to the numerous post-translation modifications of each subunit. Through the use of mammalian expression vectors we have been able to introduce the bovine α subunit and LH-β genes into a Chinese hamster ovary cell line deficient in dihydrofolate reductase. The bovine genes are actively expressed and the Chinese hamster ovary cells secrete b...

Keywords: pig; models; metabolism© 1990 Journals of Reproduction & Fertility Ltd...

Summary. Behavioural responses can have direct effects on reproduction when the performance of the behaviour contributes to productivity (e.g. achievement of copulation). Alternatively, there are indirect effects where a behavioural change is insufficient to allow adaptation to an environmental change and so the animal has to resort to physiological mechanisms with potential adverse effects on productivity.Boar contact has substantial ...

The number of female germ cells in pig fetuses decreases by 70% between day 50 after mating and day 300 after birth. Approximately 55% of antral follicles undergo degeneration (atresia) except during the 3 days before oestrus, when only 15% of the follicles survive to ovulate. Apoptosis, a form of programmed cell death, is recognized as the mechanism of germ cell death and follicle atresia at all stages of folliculogenesis. The internucleosomal cleavage of genomic DNA ca...

Despite the importance of fertilization for animal production, species preservation and controlling reproduction, the molecular basis underlying fertilization is not well understood. More progress has been made in mice than in other mammals, but targeted deletion of specific genes in the mouse has often yielded unexpected results. The pig is also a useful animal to study, as large numbers of pig gametes can be acquired easily. However, it appears that the pig zona pelluc...

Lactating sows are not able to ingest sufficient energy to produce the large amount of milk they are presently capable of. Therefore, sows use a considerable amount of body reserves to maintain their milk production. Body weight loss is negatively associated with subsequent reproductive performance. Addition of fat to the diet is often used to increase energy intake during lactation. This review examines the effects of adding fat to the diet on subsequent reproductive pe...

Summary. In four studies secretion patterns of LH, FSH, prolactin, testosterone and progesterone were measured in male and female cattle to determine endocrine changes associated with sexual maturation. Two periods of increasing gonadotrophin secretion were observed, the second one coinciding with puberty. A short luteal phase of 8–12 days precedes the first oestrus at 10–11 or 14 months of age. The testosterone values of the bulls increased with age...

Abstract unavailableKeywords: inhibin; oestradiol; cow; pig; FSH© 1991 Journals of Reproduction & Fertility Ltd...

Determining the stage- and tissue-specific patterns of gene expression shown by the embryo and fetus will provide information about the control of normal development. Identification of alterations in these patterns associated with specific abnormal phenotypes will also be informative regarding the underlying molecular mechanisms. In addition, qualitative and quantitative changes in gene expression that deviate from the norm may provide a potential marker system for predicting ...

Stress influences the activity of the reproductive system at several sites. One of the most significant effects is at level of the GnRH secretory system to reduce GnRH pulsatility and thus LH pulsatility. This in turn reduces the oestradiol signal that stimulates the GnRH–LH surge in the follicular phase. Three sequential phases have been identified in the induction of the GnRH–LH surge by oestradiol: (i) activation, (ii) transmission and (iii) surge secretion. There...