Character of preovulatory follicles and oocytes after different superovulatory treatments in heifers

The relationship between the opaqueness of the surface of bovine preovulatory follicles, degree of expansion of oocyte-cumulus investment, presence of perivitelline space, and abstriction of the first polar body was examined in heifers treated with PMSG (Group I), FSH-P (Group II), and FSH-P/GnRH (Group III). Follicles greater than 8 mm in diameter were inspected by laparoscopy 65 hours after treatment with cloprostenol in all groups and were classified as clear or opaque based on their surface appearance. Subsequently, oocytes were recovered from the follicles and characterized. The proportion of clear exceeded that of opaque follicles in all groups. The oocyte recovery rate was highest for clear follicles in Group I and II, while in Group III the rates were identical for clear and opaque follicles. The proportion of oocytes with expanded cumulus investment was highest in Group III. In Group II and I decreased proportions of expansion was seen especially among oocytes from opaque follicles. The proportion of oocytes with perivitelline space was highest in Group II and III. Again, this effect was most pronounced among oocytes from "opaque" follicles. The proportion of oocytes with a polar body was highest in Group III followed by Group II while only few oocytes in Group I displayed a polar body. It is concluded that treatment with FSH-P and especially in combination with GnRH reduced the incidence of follicular atresia as measured by opaqueness and improved oocyte quality as indicated by cumulus expansion, formation of the perivitelline space, and abstriction of the first polar body.     

Accumulation of the proteolytic marker peptide ubiquitin in the trophoblast of mammalian blastocysts

Ubiquitination is a universal protein degradation pathway in which the molecules of 8.5-kDa proteolytic peptide ubiquitin are covalently attached to the epsilon-amino group of the substrate's lysine residues. Little is known about the importance of this highly conserved mechanism for protein recycling in mammalian gametogenesis and fertilization. The data obtained by the students and faculty of the international training course Window to the Zygote 2000 demonstrate the accumulation of ubiquitin-cross-reactive structures in the trophoblast, but not in the inner cell mass of the expanding bovine and mouse blastocysts. This observation suggests that a major burst of ubiquitin-dependent proteolysis occurs in the trophoblast of mammalian peri-implantation embryos. This event may be important for the success of blastocyst hatching, differentiation of embryonic stem cells into soma and germ line, and/or implantation in both naturally conceived and reconstructed mammalian embryos.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

Eukaryote-to-eukaryote gene transfer gives rise to genome mosaicism in euglenids

Background  

Euglenophytes are a group of photosynthetic flagellates possessing a plastid derived from a green algal endosymbiont, which was incorporated into an ancestral host cell via secondary endosymbiosis. However, the impact of endosymbiosis on the euglenophyte nuclear genome is not fully understood due to its complex nature as a 'hybrid' of a non-photosynthetic host cell and a secondary endosymbiont.     

Ultrastructure of in-vivo fertilization in superovulated cattle

Heifers were induced to superovulate by treatment with PMSG or FSH. Subsequently, oestrus was induced with prostaglandins and artificial insemination was performed. Ova were collected from the oviducts and their ultrastructural features were related to an estimated time of ovulation based on the time of the LH peak. With the insemination schedule used, the estimated time of ovulation defined the time at which fertilization was expected to occur. The ova were characterized as unfertilized, fertilized or possibly fertilized, and a sequence of nuclear and cytoplasmic changes associated with fertilization was revealed. Within 4 h after the estimated time of ovulation formation of the female and male pronucleus was initiated, and at 5-7 h swelling of the pronuclei occurred. At 19 h the pronuclei were closely apposed and synkaryosis was seen, and at 23 h the first two-cell stage was obtained. Within 2-3 h after the estimated time of ovulation cortical granule release, development of conspicuous Golgi complexes, and transformation of the smooth endoplasmic reticulum occurred. At approximately 7 h parallel arrays of annulate lamellae appeared. In one third of the unfertilized ova deviant oocyte maturation was noticed.