Effect of hydrogen peroxide on thawed ovine sperm motility

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Control of oocyte maturation

Oocyte maturation is a complex process involving nuclear and cytoplasmic maturation. The nuclear maturation is a chromosomal segregation and the cytoplasmic maturation involves the reorganization of the cytoplasmic organelles, mRNA transcription and storage of proteins to be used during fertilization and early embryo development. The mechanism of oocyte maturation in vivo and in vitro still are not totally understood. However it is generally accepted that the second messenger cyclic adenosine monophosphate (cAMP) plays a critical role in the maintenance of meiotic blockage of mammalian oocytes. A relative increase in the level of cAMP within the oocyte is essential for maintaining meiosis block, while a decrease in cAMP oocyte concentration allows the resumption of meiosis. The oocyte cAMP concentration is regulated by a balance of two types of enzymes: adenylate cyclase (AC) and phosphodiesterases (PDEs), which are responsible for the synthesis and degradation of cAMP, respectively. After being synthesized by AC in cumulus cells, cAMP are transferred to the oocyte through gap junctions. Thus, specific subtypes PDEs are able to inhibit or attenuate the spontaneous meiotic maturation of oocytes with PDE4 primarily involved in the metabolism of cAMP in granulosa cells and PDE3 in the oocyte. Although the immature oocytes can resume meiosis in vitro, after being removed from antral follicles, cytoplasmic maturation seems to occur asynchronously with nuclear maturation. Therefore, knowledge of the oocyte maturation process is fundamental for the development of methodologies to increase the success of in vitro embryo production and to develop treatments for various forms of infertility. This review will present current knowledge about the maintenance of the oocyte in prophase arrest, and the resumption of meiosis during oocyte maturation, focusing mainly on the changes that take place in the oocyte.

The physiology and impact on fertility of the period of proestrus in lactating dairy cows

In cattle, proestrus begins with the initiation of luteolysis and ends with initiation of estrus and the GnRH/LH surge. This period is marked by a dramatic decrease in circulating progesterone (P4) that reaches a nadir by about 36-48 h in cows undergoing natural or prostaglandin F2 alpha (PGF)-induced luteolysis. Inadequate luteolysis is a cause of reduced fertility particularly in timed AI programs with small elevations in circulating P4 reducing fertility. Increasing circulating estradiol (E2) during proestrus is dependent on presence, size, and function of the dominant follicle and this varies during natural proestrus, due to whether animals have two or three follicular waves, and during PGF-induced proestrus, according to stage of the follicular wave at time of PGF treatment. Inadequate circulating E2 can limit fertility and increase pregnancy loss in some specific circumstances such as in cows with low BCS and in cows during heat stress. Thus, studies to optimize the length of proestrus and the concentrations of E2 and P4 during proestrus could produce substantial improvements in fertility and reductions in pregnancy loss.

The role of proestrus on fertility and postovulatory uterine function in the cow

Modern protocols to synchronize ovulations for timed artificial insemination and timed embryo transfer that include manipulations in the proestrus period (i.e., between luteolysis and estrus) affect fertility in cattle. Specifically, stimulating pre-ovulatory follicle growth and exposure to estrogens after CL regression increase the proportion of cows pregnant and decrease late embryo mortality. Such effects may be due to both preovulatory actions of estrogens and post-ovulatory actions of progesterone, as concentrations of the later hormone may be changed in response to manipulations conducted during proestrus. In the first portion of this paper we describe strategies used recently to manipulate the proestrus period in protocols for synchronization of ovulation, and to present evidence of their effects on fertility. Manipulations of timing and prominence of sex steroids during the proestrus and early diestrus that affect fertility may act on targets such as the endometrium. This tissue expresses receptors for both estrogens and progesterone and these hormones change endometrial function to support conceptus growth and pregnancy maintenance. However, specific cellular and molecular mechanisms through which fertility is affected via manipulations of the proestrus are poorly understood. In the second portion of this paper we describe a well-defined animal model to study changes in endometrial function induced by manipulations conducted during the proestrus. Such manipulations induced endometrial changes on sex steroid receptors expression, cell proliferation, oxidative metabolism and eicosanoid synthesis in the uterus, but not on glucose transport to uterine lumen. In summary, evidence is accumulating to support a positive role of increasing duration and estrogen availability during the proestrus on fertility to synchronization protocols. Such positive effects may be through changes in endometrial function to stimulate conceptus growth and survival.

Lethal effect of high concentrations of Parecoxib and Flunixin meglumine on the in vitro culture of bovine embryos

Since cyclooxygenase (COX) inhibitors have been pointed out as potential treatments to increase pregnancy rates after embryo transfer, the present experiment aimed to evaluate the effects of flunixin meglumine (FM) and parecoxib (P), a COX-1 and 2 or COX-2 specific inhibitor, respectively, on the development of bovine embryos until the hatched blastocyst stage. In vitro produced bovine embryos were cultured in media with different concentrations of FM (0.14; 1.4; 14; 140 or 1400 mu g/ml) or P (0.09; 0.9; 9; 90 or 900 mu g/ml) and the production rates were evaluated. Concentrations of FM <= 14 mu g/ml and P <= 90 mu g/ml did not impair embryo development, although compiled data from non-lethal FM concentrations (<= 14 mu g/ml) indicated a toxic effect enough to decrease the hatching rate of blastocysts. Concentrations of FM at 140 and 1400 mu g/ml and P at 900 mu g/ml were lethal as no cleavage was detected on presumptive zygotes.

Developmental aspects of early pregnancy in mares

In mares, the embryo migrates to the uterus between days 5 and 6 postovulation beginning its mobility through all uterine segments, which is essential for the maternal recognition of pregnancy. During the mobility phase, the embryonic vesicle shows a linear growth rate until its fixation between days 15 and 17, when the orientation phenomenon occurs. From fixation to day 28 of pregnancy, the embryonic growth is less evident (plateau) by cross-section ultrasound examination. After this period the linear growth rate is reestablished until day 46. This plateau is attributed to the increased uterine tone that compresses the vesicle and to volume expansion, making it difficult to detect the conceptus growth only by the cross-section diameter. Around day 20, the embryo proper is visualized as an echogenic spot in the ventral aspect of the vesicle. Additionally, development of allantoic sac, embryonic heartbeat, yolk sac regression and posterior umbilical cord formation also can be visualized from days 20 to 40. An intimate interaction between uterus and conceptus is essential for the normal pregnancy development. Color-and spectral-Doppler ultrasonography can be useful for the evaluation of this interface. A gradual increase on uterine vascularity during the early pregnancy and transient changes in endometrial vascularity accompanying the vesicle location during the mobility phase have been described. Around day 38 of gestation, the formation of the endometrial cups begins and, consequently, the synthesis of the equine chorionic gonadotropin (eCG) induces the formation and development of supplementary corpora lutea, which are important to secrete progesterone and to maintain pregnancy until around day 120.

Preservation of wild feline semen by freeze-drying: experimental model

According to the Convention on International Trade in Endangered Species, 36 wild feline species are threatened by extinction or severely endangered, and to save them is the target of several conservation programs. This study aimed to assess the viability of the freeze-drying technique for domestic cat sperm cells, with the ultimate goal of transferring this technology to the wild feline species. The domestic cat is an excellent experimental model for wild felids. It is in this scenario that the freeze-drying process (low-temperature vacuum dehydration) of sperm cells shows its value in preserving male cats' germplasm. Results from membrane and DNA integrity analysis are promising and validates the use of frozen-dried sperm samples in intracytoplasmic sperm injections (ICSIs). Further studies are still necessary to evaluate the ICSI embryo production using domestic cat frozen-dried sperm and the possibility of using such technology with wild felines.

Oocyte maturation in bitches

The canine species has been used as an experimental model for preservation of endangered species. Biotechnologies of reproduction, such as in vitro maturation (IVM), have been used to meet this objective. Several protocols for in vitro embryo production (IVEP) in swine and bovine species have been adapted for canids. However, the highest rate reported for in vitro maturation in canids is only 39%, which is still lower than those in other species. Therefore, current research on assisted reproduction in canids have focused on several IVM protocols, including the addition of proteins, hormones, meiosis inhibitors, growth factors and antioxidants to the maturation media and the determination of suitable timing for culture, so that variables involved in the process can be fine-tuned. This review has the main objective of describing major developments and limitations in the process of oocyte maturation in bitches.

Paracrine and autocrine factors in the differentiation of the cumulus-oocyte complex

A better understanding of the paracrine and autocrine regulatory loops within the cumulus-oocyte complex (COC) is fundamental for the improvement of in vitro maturation (IVM) outcomes in humans and domestic species. This review presents the most important local regulators identified in the COC to date with special attention to those secreted by the oocyte and acting on cumulus cells, as well as their roles in different processes crucial for the successful maturation of the COC. An autocrine regulatory loop mediated by epidermal growth factor-like (EGF-like) peptides in cumulus cells triggers COC maturation. During COC differentiation, oocyte secreted factors (OSFs), particularly members of the transforming growth factor-beta (TGF beta) and fibroblast growth factor (FGF) families, regulate meiotic resumption, cumulus expansion, cumulus metabolism, apoptosis and steroidogenesis.

O Conselho tutelar e o direito à educação

O presente trabalho intitulado O Conselho Tutelar e o direito à educação pretende verificar de que forma através da atuação do Conselho Tutelar se pode ter garantido o direito à educação. A decisão de trabalhar com este tema se deu em primeiro lugar pelo fato de a pesquisadora ter atuado como conselheira tutelar em duas gestões consecutivas do Conselho Tutelar de Rio Claro/SP, no período de 2006 a 2011 (quarta e quinta gestões). Em segundo lugar, embora a atuação do Conselho Tutelar não se restrinja ao atendimento do direito à educação, abrangendo as mais diversas áreas, optou-se por tratar o tema vinculado ao direito à educação por ser um trabalho de conclusão do curso de pedagogia da UNESP/IB e pelo fato de o Conselho Tutelar ser até então pouco explorado no meio acadêmico, principalmente em relação aos encaminhamentos dados à garantia do direito à educação. Em terceiro lugar esta decisão também se baseou no entendimento de que a educação tornou-se um dos requisitos indispensáveis para que os indivíduos tenham acesso ao conjunto de bens e serviços disponíveis na sociedade, constituindo-se em condição necessária para se usufruir de outros direitos constitutivos do estatuto da cidadania (OLIVEIRA, 2002). De modo que no Brasil, a educação é um direito garantido por lei para todos os cidadãos prescrito na Constituição Federal de 1988 (CF/88), sendo que a Lei Federal 8069/90 Estatuto da Criança e do Adolescente (ECA) e a Lei n.º 9.394/96, a Lei de Diretrizes e Bases da Educação (LDB/96) ratificam o princípio constitucional. Entretanto devemos levar em conta que nosso país apresenta uma série de desigualdades sociais, econômicas e culturais que dificultam o acesso de parcela considerável da população ao ensino formal. Para podermos tratar deste tema procuramos traçar inicialmente um breve percurso da história social da infância... (Resumo completo, clicar acesso eletrônico abaixo)

A emergência do escravo agente na historiografia brasileira da escravidão entre os anos 1970 e 1980

Pós-graduação em História - FCLAS

Rememorando vidas: lembranças de velhos trabalhadores

Pós-graduação em Serviço Social - FCHS

Migração e trabalho: impactos do processo migratório na vivência da mulher nordestina

Pós-graduação em Serviço Social - FCHS

A conversão de registros na implantação de repositórios institucionais: o caso do Repositório Institucional UNESP

O Repositório Institucional UNESP foi criado em 2013 e, para sua implantação, foi povoado com dados obtidos de forma automática. Considerando a experiência realizada na UNESP, este trabalho tem por objetivo apresentar os processos utilizados para a conversão dos registros coletados de três diferentes fontes de dados (Web of Science, SciELO e Scopus) para inclusão no repositório. A partir da coleta dos registros, os padrões de metadados da Web of Science, da SciELO e da Scopus foram mapeados para o perfil de aplicação de metadados utilizado no repositório. Os registros foram coletados como arquivos XML e, para sua conversão, foram elaboradas folhas de estilo utilizando a linguagem XSLT. Após essa conversão, os arquivos XML foram convertidos em arquivos CSV e, então, importados no Repositório. Conclui-se que os processos de conversão utilizados permitiram alcançar as metas iniciais do Repositório e evitaram a necessidade de inclusão dos registros de forma manual.

Introdução à pesquisa com sequências didáticas na formação continuada online de professores de ciências

The integration of research in teaching practices assumes increasing importance and complexity in education. One aspect involved in this issue and poorly investigated is the training of teachers for the development of research linked with their practices. In this context, we present a training for research developed on a distance-learning course in the Science Teaching, which involves the design, implementation and analysis of didactic sequences: the Study Guide to the Initiation of the Term Paper (SGITP). Our research goal is to present a training proposal produced from the results collected from a survey of the literature of the area, and to investigate its application and its results in the teachers' continuing education program. Using data extracted from the production of students and tutors, we concluded that SGITP had a good acceptance among them and it was positively evaluated by teachers, in addition to promoting a greater understanding of research.