Back to Tityus serrulatus Lutz & Mello, 1922 (Scorpiones: Buthidae): new comments about an old species

A synopsis on the historical, geographical and ecological aspects related to the most conspicuous scorpion species of the genus Tityus known from Brazil is proposed. Tityus serrulatus Lutz & Mello, 1922 was described precisely one century ago, nevertheless many questions related to its ecological adaptations and geographical expansion remain without a precise response. This species, well known for its infamous reputation of noxious species, is also known for its capacity to reproduce asexually, by parthenogenesis. Although the individuals of a given population are considered clones, a new hypothesis could suggest the occurrence of mutations within isolated individuals, leading to distinct subpopulations that could present better phenotypic performances in ecological habitats distinct from those of the original area of distribution of the species.(AU)

Dynamic analysis of Ca2+ level during bovine oocytes maturation and early embryonic development

Mammalian oocyte maturation and early embryo development processes are Ca(2+)-dependent. In this study, we used confocal microscopy to investigate the distribution pattern of Ca2+ and its dynamic changes in the processes of bovine oocytes maturation, in vitro fertilization (IVF), parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT) embryo development. During the germinal vesicle (GV) and GV breakdown stage, Ca2+ was distributed in the cortical ooplasm and throughout the oocytes from the MI to MII stage. In IVF embryos, Ca2+ was distributed in the cortical ooplasm before the formation of the pronucleus. In 4-8 cell embryos and morulas, Ca2+ was present throughout the blastomere. In PA embryos, Ca2+ was distributed throughout the blastomere at 48 h, similar to in the 4-cell and 8-cell phase and the morula. At 6 h after activation, there was almost no distribution of Ca2+ in the SCNT embryos. However, Ca2+ was distributed in the donor nucleus at 10 h and it was distributed throughout the blastomere in the 2-8 cell embryos. In this study, Ca2+ showed significant fluctuations with regularity of IVF and SCNT groups, but PA did not. Systematic investigation of the Ca2+ location and distribution changes during oocyte maturation and early embryo development processes should facilitate a better understanding of the mechanisms involved in oocyte maturation, reconstructed embryo activation and development, ultimately improving the reconstructed embryo development rate.

Effects of the conditioned medium of mesenchymal stem cells on mouse oocyte activation and development

Mesenchymal stem cells (MSCs) have been reported to secrete a variety of cytokines and growth factors acting as trophic suppliers, but little is known regarding the effects of conditioned medium (CM) of MSCs isolated from femurs and tibias of mouse on the artificial activation of mouse oocytes and on the developmental competence of the parthenotes. In the current study, we investigated the effect of CM on the events of mouse oocyte activation, namely oscillations of cytosolic calcium concentration ([Ca²+]i), meiosis resumption, pronucleus formation, and parthenogenetic development. The surface markers of MSCs were identified with a fluorescence-activated cell sorter. The dynamic changes of the spindle and formation of pronuclei were examined by laser-scanning confocal microscopy. Exposure of cumulus-oocyte complexes to CM for 40 min was optimal for inducing oocyte parthenogenetic activation and evoking [Ca²+]i oscillations similar to those evoked by sperm (95 vs 100 percent; P > 0.05). Parthenogenetically activated oocytes immediately treated with 7.5 µg/mL cytochalasin B (CB), which inhibited spindle rotation and second polar body extrusion, were mostly diploid (93 vs 6 percent, P < 0.01) while CB-untreated oocytes were mostly haploid (5 vs 83 percent, P < 0.01). Consequently, the blastocyst rate was higher in the CB-treated than in the CB-untreated oocytes. There was no significant difference in developmental rate between oocytes activated with CM and 7 percent ethanol (62 vs 62 percent, P > 0.05), but the developmental competence of the fertilized oocytes was superior to that of the parthenotes (88 vs 62 percent, P < 0.05). The present results demonstrate that CM can effectively activate mouse oocytes, as judged by the generation of [Ca²+]i oscillations, completion of meiosis and parthenogenetic development.

Oocyte activation and preimplantation development of bovine embryos obtained by specific inhibition of cyclin-dependent kinases

The efficiency of bohemine and roscovitine in combination with ionomycin on parthenogenetic activation and initial embryonic development of bovine oocytes was studied. Two experiments were performed: in the first, different concentrations (0, 50, 75 or 100æM) and different exposure periods (2, 4 or 6 hours) to bohemine or roscovitine were tested for activation rates of in vitro matured (IVM) bovine oocytes, which were pre-exposed to ionomycin. The best treatments, 75µM bohemine and 50µM roscovitine, both for 6h, were used in the second experiment, in which IVM bovine oocytes were exposed to ionomycin, followed or not by bohemine or roscovitine treatment, and evaluated for nuclear status, activation rate and blastocyst development were assessed. The combined treatments (ionomycin + cyclin-dependent kinases inhibitors - CDKIs) showed better results for activation rates (77.3 percent) and initial embryonic development (35.2 percent) than the single ionomycin treatment (69.4 percent for activation and 21.9 percent for development); and also lead to a more uniform activation (nearly 90 percent single pronucleus development). The results showed that CDKIs improve the effects of ionomycin on parthenogenetic activation and blastocyst development in bovine oocytes and could help to achieve more efficient activation protocols, increasing the developmental competence of embryos obtained by reproductive biotechniques.

Realizaram-se dois experimentos para avaliar a eficiência da bohemina e roscovitina associadas à ionomicina para ativação partenogenética e desenvolvimento embrionário inicial de bovinos. No primeiro, foram testadas diferentes concentrações (0, 50, 75 ou 100æM) e diferentes tempos de exposição (2, 4 ou 6 horas) à bohemina ou à roscovitina na ativação de oócitos bovinos maturados in vitro (MIV) pré-expostos à ionomicina. Os melhores tratamentos, bohemina 75µM e roscovitina 50µM, ambos por seis horas, foram utilizados no segundo experimento, no qual oócitos bovinos MIV foram expostos à ionomicina seguido ou não pelo tratamento com inibidores específicos das quinases dependentes de ciclina (CDKI), e avaliados quanto à configuração nuclear, taxa de ativação e desenvolvimento até blastocisto. Os tratamentos combinados (ionomicina+CDKI) apresentaram melhor taxa de ativação (77,3 por cento) e desenvolvimento embrionário inicial (35,2 por cento) do que a ionomicina sozinha (69,4 por cento e 21,9 por cento, respectivamente), e também promoveram ativação mais uniforme (aproximadamente 90 por cento de formação de um pronúcleo). Estes resultados demonstram que os CDKIs potencializam o efeito da ionomicina na ativação e desenvolvimento embrionário inicial e podem auxiliar na obtenção de protocolos de ativação mais eficientes, aumentando a capacidade de desenvolvimento de embriões produzidos por meio de biotécnicas reprodutivas.

Computer simulations for biological aging and sexual reproduction

The sexual version of the Penna model of biological aging, simulated since 1996, is compared here with alternative forms of reproduction as well as with models not involving aging. In particular we want to check how sexual forms of life could have evolved and won over earlier asexual forms hundreds of million years ago. This computer model is based on the mutation-accumulation theory of aging, using bits-strings to represent the genome. Its population dynamics is studied by Monte Carlo methods

Reproductive aspects of Haemaphysalis leporis-palustris

The adult stage of Haemaphysalis leporis-palustris was studied. Two infestations consisted of male and female ticks on two rabbits (Oryctolagus cuniculus). Other two manifestations consisted of only female ticks on two O. cuniculus. Females fed without males showed differences in some biological parameters when compared to females fed with males. Parthenogenesis is reported for the first time by one H. leporis-palustris female.