Assessment of swim-up and discontinuous density gradient in sperm sex preselection for bovine embryo production / Avaliação do swim-up e do gradiente descontinuo de densidade na pré-seleção do sexo de espermatozoides na produção de embriões bovinos

The purpose of this work was to associate the modified swim-up method with centrifugation in density gradient for the separation of X-bearing spermatozoa. Sperm viability and integrity were evaluated through the Trypan Blue/Giemsa staining method. Quality control of centrifuged spermatozoa was performed in in vitro produced embryos. The results were validated by the sex ratio of in vitro produced embryos using PCR by Y- specific sequences present in bovine male genomic DNA. After determining genetic sex of in vitro produced embryos, the results showed difference (P<0.05) in deviation of sex ratio when comparing the control group (45.2% females) with the other spermatozoa selection procedures (60.6% females) (P<0.05). The sperm selection methods are capable of selecting X-bearing spermatozoa without compromising the spermatozoa fertility (cleavage and blastocyst rates, 70% and 26%, respectively) and were considered relevant methods to be introduced in bovine in vitro produced embryo programs.

O objetivo do presente trabalho foi associar o método de swim-up modificado à centrifugação em gradiente de densidade para a separação de espermatozoides portadores do cromossomo X. A viabilidade e a integridade espermática foram avaliadas pelo método de coloração Azul de Tripan e Giemsa. O controle de qualidade dos espermatozoides centrifugados foi realizado por meio da produção in vitro de embriões bovinos. Os resultados foram validados pela técnica de PCR para verificar a proporção sexual dos embriões produzidos in vitro, com o uso de sequências Y especificas presente no DNA genômico de machos bovinos. Após determinar o sexo genético dos embriões produzidos in vitro, os resultados não mostraram diferença (P<0,05) no desvio da proporção do sexo quando comparou o grupo controle (45,2% de fêmeas) com os outros processos de seleção de espermatozoides (60,6% de fêmeas) (P<0,05). Os métodos de seleção de espermatozoides são capazes de selecionar espermatozoides portadores do cromossomo X sem comprometer a fertilidade, medida pelas taxas de clivagem e blastocisto de 70% e 26%, respectivamente, e foram considerados métodos de relevância para serem introduzidos nos programas de produção in vitro de embriões bovinos.

Validação comparativa utilizando PCR quantitativo em tempo real (qPCR) e PCR convencional de sêmen bovino centrifugado em gradiente de densidade contínuo / Comparative validation using quantitative real-time PCR (qPCR) and conventional PCR of bovine semen centrifuged in continuous density gradient

The objective of the present study was to determine the sperm enrichment with X-bearing spermatozoa, after one centrifugation in a Percoll or OptiPrep continuous density gradient, using quantitative real-time polymerase chain reaction (qPCR) of sperm DNA and resultant in vitro-produced bovine embryos by PCR. Frozen/thawed sperm was layered on density gradients and the tubes were centrifuged. Supernatants were gently aspirated and the sperm recovered from the bottom of the tubes. Cleavage and blastocyst rates were determined through in vitro production of embryos and PCR was performed to identify the embryos' genetic sex. A difference in blastocyst rate was found in the Percoll treatment compared to OptiPrep (P<0.05). The percentage of female embryos in the Percoll and OptiPrep groups was 62.0 percent and 47.1 percent, respectively. These results were confirmed by qPCR of spermatozoa DNA and underestimation was seen only in the Percoll group. It was possible to sexing sperm using simple approach.

O objetivo do presente estudo foi determinar o enriquecimento de espermatozoides portadores do cromossomo X após a centrifugação em gradiente de densidade contínuo de Percoll ou OptiPrep, utilizando reação em cadeia da polimerase quantitativa em tempo real (qPCR) do DNA do espermatozoide e dos embriões bovinos produzidos in vitro resultantes pela PCR convencional. Espermatozoides descongelado foram depositados em gradientes de densidade e os tubos foram centrifugados. Os sobrenadantes foram gentilmente aspirados e os espermatozoides recuperados do fundo dos tubos. As taxas de clivagem e de blastocisto foram determinadas pela produção in vitro de embriões e a PCR foi realizada para a identificação genética do sexo dos embriões. Verificou-se diferença na taxa de blastocistos entre os grupos Percoll e OptiPrep (P<0,05). A porcentagem de embriões de fêmeas nos grupos Percoll e OptiPrep foi de 62,0 por cento e 47,1 por cento, respectivamente. Estes resultados foram confirmados pela qPCR do DNA de espermatozoides e uma subestimação foi observada no grupo do gradiente de densidade de Percoll. Foi possível a sexagem de espermatozoides utilizando uma metodologia simples.

Induction of the acrosome reaction test to in vitro estimate embryo production in Nelore cattle / Teste de indução da reação acrossomal na estimativa de produção in vitro de embriões Nelore

The effectiveness of induction of the acrosome reaction (AR) test as a parameter to in vitro estimate embryo production (IVP) in Nelore breed and the AR pattern by the Trypan Blue/Giemsa (TB) stain were evaluated. Frozen semen samples from ten Nelore bulls were submitted to AR induction and were also evaluated for cleavage and blastocyst rates. The treatments utilized for AR induction were: control (TALP medium), TH (TALP medium + 10μg heparin), TL (TALP medium + 100μg lysophosphatidylcholine) and THL (TALP medium + 10μg heparin + 100μg lysophosphatidylcholine). Sperm acrosomal status and viability were evaluated by TB staining at 0 and after 4h incubation at 38ºC. The results obtained for AR presented a significant difference (P<0.05) in the percentage of acrosome reacted live sperm after 4h of incubation in the treatments that received heparin. The cleavage and blastocyst rates were 60 percent and 38 percent respectively and a significant difference was observed among bulls (P<0.05). It was founded a satisfactory model to estimate the cleavage and blastocyst rates by AR induction test. Therefore, it can be concluded that the induction of the AR test is a valuable tool to predict the IVP in Nelore breed.

Avaliou-se a eficiência da técnica de indução da reação acrossomal (RA) como parâmetro para estimar a produção in vitro (PIV) de embriões Nelore e analisou-se o padrão de RA pela técnica de coloração Azul de Tripan/Giemsa (TB). Amostras de sêmen congelado de dez touros foram submetidas à indução da RA e avaliadas quanto a taxa de clivagem e blastocisto. Os tratamentos utilizados para indução da RA foram: controle (meio TALP), TH (meio TALP + 10μg heparina), TL (meio TALP + 100μg lisofosfatidilcolina) e THL (meio TALP + 10μg heparina + 100μg lisofosfatidilcolina). Avaliou-se viabilidade espermática e acrossomal pela coloração TB a zero e após 4h de incubação a 38ºC. Os resultados obtidos para RA mostram uma diferença significativa (P<0,05) na porcentagem de espermatozoides vivos com acrossoma reagindo após 4h de incubação nos tratamentos que receberam heparina. As taxas de clivagem e blastocisto obtidas foram 60 por cento e 38 por cento respectivamente e observou-se uma diferença significativa entre touros (P<0,05). Delineou-se um modelo satisfatório para estimar as taxas de clivagem e blastocisto. Desta forma, conclui-se que o teste de indução da RA é uma ferramenta valiosa para predizer a PIV na raça Nelore.

Effect of salbutamol on pulmonary responsiveness in chronic pulmonary allergic inflammation in guinea pigs

Beta-2-agonists have been widely used by asthmatic subjects to relieve their obstructive symptoms. However, there are reports that continuous use could lead to loss of bronchial protection and exacerbation of asthma symptoms. We evaluated the effect of two regimens of salbutamol administration (twice and five times a week) in a model of chronic airway inflammation in male Hartley guinea pigs (protocol starting weight: 286 ± 30 g) induced by repeated exposures to aerosols of ovalbumin (OVA). After sensitization, guinea pigs were exposed to aerosols of 0.1 mg/ml salbutamol solution twice a week (OVA + S2x, N = 7) or five times a week (OVA + S5x, N = 8). We studied allergen-specific (OVA inhalation time) and -nonspecific (response to methacholine) respiratory system responsiveness. Seventy-two hours after the last OVA challenge, guinea pigs were anesthetized and tracheostomized, respiratory system resistance and elastance were measured and a dose-response curve to inhaled methacholine chloride was obtained. Specific IgG1 was also quantified by the passive cutaneous anaphylactic technique. OVA-sensitized guinea pigs (N = 8) showed reduction of the time of OVA exposure before the onset of respiratory distress, at the 5th, 6th and 7th exposures (P < 0.001). The OVA + S2x group (but not the OVA + S5x group) showed a significant increase in OVA inhalation time. There were no significant differences in pulmonary responsiveness to methacholine among the experimental groups. OVA + S2x (but not OVA + S5x) animals showed a decrease in the levels of IgG1-specific anaphylactic antibodies compared to the OVA group (P < 0.05). Our results suggest that, in this experimental model, frequent administration of ß2-agonists results in a loss of some of their protective effects against the allergen.

Further characterization of ascaris suum component(s) with supressive activity on the IgE antibody response

In order to characterize the component(s) of Ascaris suum reponsible for damping of the IgE antibody production we demonstrated that the extract incubated in sodium acetate buffer, pH 4.5, maintained its suppressive effect and the same protein banding pattern by SDS-PAGE. Elimination of the lipoprotein components of the extract also left its damping properties unchanged. SDS-PAGE of the lipoprotein-free extract revealed practically the same pattern as shown by the whole extract, except for the high molecular weight polupeptides. These results indicate that the suppressive component(s) of A. suum did not precipitate and retained their activity at low pH. In addition, they appear not to be lipoproteins