Mouse EWSR1 is critical for spermatid post-meiotic transcription and spermiogenesis

Spermatogenesis is precisely controlled by complex gene-expression programs. During mammalian male germ-cell development, a crucial feature is the repression of transcription before spermatid elongation. Previously, we discovered that the RNA-binding protein EWSR1 plays an important role in meiotic recombination in mouse, and showed that EWSR1 is highly expressed in late meiotic cells and post-meiotic cells. Here, we used an Ewsr1 pachytene stage-specific knockout mouse model to study the roles of Ewsr1 in late meiotic prophase I and in spermatozoa maturation. We show that loss of EWSR1 in late meiotic prophase I does not affect proper meiosis completion, but does result in defective spermatid elongation and chromocenter formation in the developing germ cells. As a result, male mice lacking EWSR1 after pachynema are sterile. We found that in Ewsr1 CKO round spermatids, transition from a meiotic gene-expression program to a post-meiotic and spermatid gene expression program related to DNA condensation is impaired, suggesting that EWSR1 plays an important role in regulation of spermiogenesis-related mRNA synthesis necessary for spermatid differentiation into mature sperm.

Factors limiting successful reproduction in wild silver carp, Hypophthalmichtys molitrix, in Kherrata Reservoir, Algeria

Silver carp, Hypophthalmichtys molitrix (Cyprinidae), is the most important freshwater fish in Algerian aquaculture. No natural spawning is observed in Algerian water bodies. This study was conducted with the aim of investigating silver carp reproduction in the wild in Algeria. This investigation can contribute tools to facilitate successful artificial reproduction. Macroscopic and histological analysis of the gonads was conducted, and the monthly distribution of maturity stages and oocyte diameters were monitored in an aggregate sample of 130 male and female silver carp, H. molitrix, (450-710 mm total length). The gonadosomatic index (GSI) ranged from 2.76 to 18.88% in females and from 0.34 to 1.85% in males. The female GSI values were the highest from June to August indicating the onset of the spawning season. The histological structures of the gonads revealed five different developmental stages in females and three stages in males. The oogenesis stages were the perinucleolar stage, the yolk vesicle stage, the primary yolk, the secondary yolk, and the tertiary yolk. Migratory nuclei and hydrated oocytes, which are considered to be the maturation stage, were not observed. Three different spermatogenesis phases (immature, maturing, and mature testis) were identified, which included final spermatozoa maturation.

Effects of sodium fluoride on the gametogenesis of the tubificid oligochaete Branchiura sowerbyi Beddard

Fluoride concentration is significantly increasing in many aquatic ecosystems because of human activities (agrochemical, pharmaceutical, refrigerant, pesticide and surfactant compounds). This study aims to examine the effects of fluorides on gametogenesis by exposing Branchiura sowerbyi (Oligochaeta) to sodium fluoride concentrations 50 to 100 times above normal ones in freshwater (0.1–0.3 mg/L) and observing the effects over time. Because non-toxic concentrations determined in short-term experiments could induce effects as exposure times increase, B. sowerbyi were exposed to sodium fluoride from the end of February 2012 to the end of July 2012. They were continuously monitored until the cocoon deposition stage to investigate any possible effects. Weekly observations were conducted on treated and untreated specimens to monitor gamete maturation in both male and female germinal lines. The results revealed temporal differences in the gametogenesis phases of treated specimens, such as incomplete spermatozoa maturation. At the end of the experiment, the exposed animals were thinner and shorter than the controls and cocoon deposition did not occur.

INFLUENCE OF ACCLIMATIZATION AND AGE OF IMPORTED BOARS ON THE QUALITY OF THEIR SPERM

In the paper the process of acclimatization and adaptation of boars on climate and microclimate conditions are described. The process of growth and sexual maturity during the breeding and accustoming of boars in taking sperms in the centers of artificial insemination or breeding stations are analyzed. It is concluded that appropriate microclimate conditions may solve sterility provoked by climate conditions and even increase fertility of pigs. For purchased and imported young boars it is very important that animals are raised in a proper way and trained for mounting and semen collecting. Ejaculate in the native sperm of imported boars is better quality comparing to the ejaculate of home breeds, but they are sensitive to unspecific infections that can reduce spermatozoa vitality, damage acrosome, disturb spermatozoa maturation and thus influence fertilizing of diluted semen. Housing and nutrition of high-born breed boars has important role in maximal exploitation of producing ability especially on longevity and lifetime production of the imported boars.

IN VITRO EMBRYOGENESIS: AN EXPERIMENTAL MODEL FOR THE UNDERSTANDING OF REPRODUCTIVE PHYSIOLOGY AND DEVELOPMENT IN MAMMALS

A complete in vitro technique has been developed in the mouse for capacitation of epididymal spermatozoa, maturation of ovarian oocytes and fertilization of such gemetes to give rise to viable embryos, which, when transplanted to proper recipients result in normal, fertile progeny. This technique, although it requires perfection, has many future possibilities and potential applications as a research tool in solving problems of mammalian reproductive physiology and developmental biology. It may be useful in the investigation of (a) gene action in the X chromosome and initiation of X-inactivation during embryogenesis; (b) nuclear transplantation and the ontogenetic commitment of oocyte cytoplasm; (c) the role of drugs, mutagens and carcinogens in the fetal environment; (d) genetic engineering; eg. enzyme induction and (e) many problems involving fertility and sterility.