ABSTRACT
O reconhecimento materno da gestação é o período em que o concepto sinaliza sua presença para a mãe. Em ruminantes, este período coincide com o alongamento do embrião e a máxima produção de interferon-tau (IFNT). O IFNT produzido pelo concepto age via parácrina no útero inibindo a expressão dos receptores de estrógenos (ESR1) e de ocitocina (OXTR) no epitélio luminal do endométrio, evitando, assim, a liberação de pulsos luteolíticos de prostaglandina F2 alfa (PGF2 ), hormonio responsável pelo início da luteólise. Além da sua ação durante o reconhecimento materno da gestação em ruminantes, o IFNT aumenta a expressão de vários genes estimulados por interferons (ISGs) no útero, no corpo lúteo (CL) e em células sanguíneas. Estudos recentes demonstraram que o IFNT possui ação endócrina no CL ovino e também estende o ciclo estral (pseudo gestação) além do dia 32 após a infusão de IFNT recombinante ovino (roIFNT) na veia uterina. A comprovação da saída de IFNT do útero pela veia uterina sugere que a ação endócrina do IFNT possa ser um mecanismo complementar ao mecanismo intrauterino de reconhecimento materno da gestação. A ação direta do IFNT em tecidos extrauterinos estimula a expressão de ISGs que, no CL, podem estar envolvidos com a resistência luteal à ação luteolítica da PGF2a.
Maternal recognition of pregnancy is the period when the conceptus signals its presence to the dam. In ruminants, it requires conceptus elongation, which coincides with maximum production of interferon-tau (IFNT). Conceptus IFNT acts in a paracrine manner silencing estrogen receptor alpha (ESR1) and oxytocin receptor (OXTR) in the luminal epithelium, thus preventing luteolytic prostaglandin F2 alpha (PGF2 ) pulses. Besides its role during maternal recognition of pregnancy, IFNT induces the expression of several interferon stimulated genes (ISGs) in the endometrium, corpus luteum (CL) and blood cells. Recently, it was suggested an endocrine role for IFNT during the period of maternal recognition of pregnancy in sheep. It was demonstrated that infusion of IFNT into the uterine vein can extend the estrous cycle beyond 32 days. This direct action of IFNT in extrauterine tissues induces ISGs expression, which might be involved in the rescue of the CL from the luteolytic effects of PGF2 pulses.
ABSTRACT
Interferon-tau (IFN-tau) is a newly discovered IFN of type I. It was originally found for its role as a pregnancy recognition hormone in ruminant animals such as sheep and cows. Like the other type I IFNs, IFN-tau have the same biological activities including antiviral, antiproliferative and immunomodulatory effects. In order to clearly identify the function of IFN-tau, the coding sequence of IFN-tau was amplified by PCR from IFN-tau cDNA, this fragment digested by EcoR I and BamH I and was inserted into pBV220 to form the recombinant plasmid pBV220/IFN-tau which was then transformed into E.coli BL21. It was found that pBV220/IFN-tau was highly expressed as inclusion body in BL21. Next, the expressed protein was purified on S-100 High Resolution and the purified product was confirmed by amino acid sequence analysis. Moreover, the standard antiviral activity test indicated that the activity of IFN-tau was about 2.09?106IU/ml.
ABSTRACT
Avaliou-se a interferência da criopreservação sobre a secreção de interferon-tau (IFN-t) por embriões bovinos produzidos in vitro. Usaram-se dois grupos de tratamentos: I) constituído por embriões não criopreservados (fresco) e II) embriões criopreservados. Os embriões, após atingirem a fase de blastocisto (fresco ou imediatamente após o descongelamento dos criopreservados), continuaram a ser cultivados individualmente por mais sete dias. Do meio de cultivo em que se mantiveram os blastocistos retiraram-se alíquotas com três e sete dias do início do cultivo, para a avaliação da secreção de IFN-t pelos embriões cultivados. Os embriões congelados secretaram menos IFN-t do que aqueles não criopreservados (P<0,05), e com sete dias houve maior secreção do interferon do que com três dias (P<0,05). A criopreservação prejudicou a produção de IFN-t pelo trofoblasto e pode comprometer o reconhecimento materno da gestação e o desenvolvimento do embrião pós-descongelamento.
The effect of cryopreservation in IFN-tau, from bovine embryos produced in vitro was evaluated. Two treated groups (G1= fresh bovine embryos, n=59 and G2= freezed embryos, n=84) were used to study the effect of cryopreservation on IFN-tau secretion. After reaching the blastocyst phase, the embryos were kept on individual culture for additional period of 7 days. On days 3 and 7 after the beginning of embryos cultivation, samples of the media culture were taken for IFN-tau secretion titration. Oocysts taken from follicles ranging from 3 to 5mm in diameter were obtained from ovaries of females at slaughterhouse. The embryos were frozen, after being dehydrated with ethylene glycol (1.8m), conditioned on 0.5ml palletes and frozen. Frozen embryos secreted lower IFN-tau than fresh embryos (P<0.05). At day 7 it was registered higher IFN-tau secretion from trophoblast than at day 3 (P<0.05). The increasing of IFN-tau secretion was observed when the blastocyst began to longed and it was directly related to the embryos development. The synthesis of IFN-tau is related to the capability of development of the blastocyst. Cryopreservation is a method that affects the maternal recognition of pregnancy and the post-freezing embryo development.
Subject(s)
Blastocyst , Cattle , Cryopreservation/methods , Embryonic Structures/anatomy & histology , Embryonic Structures/physiology , Fertilization in Vitro/methodsABSTRACT
Objective The microcapsules were prepared by using chitosan and sodium alginate as wall materials,and the controlled-release microcapsulas of interferon tau were hoped to be develop an oral interferon preparation.Methods The microcapsules were prepared by using syringe hand-made drop.In the process of dropping,speed and distance were the major factors which influence the form of microcapsules.Results Chitosanalginate microcapsules which was prepared simple and fast had high encapsulation rate and extended-release effect in intestine.Conclusion Chitosan-alginate microcapsules have the potential to be used to prepare interferon tau and other protein medicines.