Bioscientifica Proceedings

Ovulation rate is the principal source of variation in the reproductive rate of small ruminants. There is extensive variability in this trait both in terms of major genes and polygenes. Identification of the DNA changes responsible for the Booroola and Inverdale effects enabled testing for these mutations in any population. Surprisingly, in only one of six populations, with segregation of major genes for ovulation rate, could the effect be attributed to one of these mutations....

This paper reviews the major approaches used to map quantitative trait loci (QTL) and current knowledge about QTL affecting reproductive trait loci in pigs. Three different approaches, i.e. functional candidate gene analyses, genome-wide linkage studies (GWLS) and genome-wide association studies (GWAS) have been used to map QTL in pigs. The interest and limits of each of the three approaches are discussed. Candidate genes and QTL have been reviewed based on PigQTLdb at <...

In ruminants, more than 30% of the embryonic losses observed after artificial insemination (AI) have an early origin, coincident with a marked elongation of the trophoblast which occurs before implantation. Several observations provide clear evidence that early elongation of the conceptus relies on cell multiplication, cell growth and cell shape remodeling. Recent results indicating an intense multiplication of a non-fully differentiated trophoblast, which still expresses ...

Abstract unavailableKeywords: progesterone; protein kinase C; intracellular calcium; prostaglandins; arachidonic acid; luteal cells; cattle© 1991 Journals of Reproduction & Fertility Ltd...

A review of the remarkable production of steroids by the testes of the boar is presented, with the principal aims of highlighting the achievements of the Leydig cells and, at the same time, pointing to the considerable deficiencies in our understanding of its biological relevance. The onset of gonadal steroidogenesis at an early stage of sex differentiation and the pattern of pre- and postnatal secretion of steroids are outlined. This is followed by a list of steroids id...

The human protamine gene cluster consists of three tightly regulated genes, protamine 1 (PRM1), protamine 2 (PRM2) and transition protein 2 (TNP2). Their products are required to repackage the paternal genome during spermiogenesis into a functional gamete. They reside within a single DNase I-sensitive domain associated with the sperm nuclear matrix, bounded by two haploid-specific Matrix Attachment Regions. The nuclear matrix is a dynamic proteinaceous network that is associat...

Summary. It is proposed that the first follicular phase in the lamb is initiated when responsiveness to oestradiol inhibition of LH secretion decreases sufficiently to permit the expression of an inherent hourly LH pulse rhythm. The hourly LH pulse rhythm is believed to drive oestradiol production to levels that induce the first LH surge. This hypothesis is based upon several considerations. First, pulsatile LH secretion invariably occurs at low frequencies in...

The roles of testicular hormones in the negative feedback regulation of the secretion and actions of GnRH in male domestic ruminants are reviewed, concentrating mainly on research conducted with rams. Testicular steroids have major feedback actions directly at the hypothalamus to inhibit the secretion of GnRH, although it is apparent that, under certain circumstances, the steroids also have actions directly at the pituitary gland. Further research is necessary to delineate the...

Light microscopic semen evaluation provides useful information about a given sperm sample, but due to its subjective nature has limited prognostic value for the reproductive performance of males or the outcome of assisted fertilization. Cryptic sperm abnormalities (occurring at the molecular level) are not easily detectable by light microscopy, but can be revealed by an array of biomarkers. The latter include fluorescent markers of acrosomal status, fluorochromes detecting alt...

The autocrine and paracrine role of the insulin-like growth factors (IGFs) and epiderrnal growth factor (EGF)-related peptides in pig ovary are reviewed. For convenience, each of these regulatory systems is divided into several interactive components: regulated expression of the growth factors, growth factor reception at the cell surface and intracellular action of the growth factors. In addition, the concept of regulated bioavailability and targeting of growth factors in...