Survey of mutations in prolificacy genes in Santa Ines and Morada Nova sheep / Pesquisa de mutações em genes da prolificidade em ovelhas Santa Inês e Morada Nova

Polymorphisms in the BMP-15 gene related to Galway (FecXG) and Inverdale (FecXI) and in the BMPR-1B gene known as Booroola (FecB) mutations were investigated using the Polymerase Chain Reaction - Restriction Fragment Length Polymorphism (PCR-RFLP) method, on sheep from the breeds Santa Inês (n= 574) and Morada Nova (n=282). DNA was extracted and amplified through PCR with specific primers that introduced a restriction site in association with the mutation. The PCR products were submitted to endonucleases. The experiment found no FecXG and FecXI mutations. Six samples of animals with multiple offspring/birth history presented polymorphism for FecB similar to control samples, but this pattern was not confirmed by nucleotide sequencing. Although the absence of these mutations in the studied breeds, other factors related to prolificacy should be investigated to explain the inherent prolificity mechanisms.(AU)

Polimorfismos Galway (Fec XG ) e Inverdale (Fec XI), relacionados ao gene BMP-15, e Booroola (FecB), localizado no gene BMPR-1B, foram investigados usando-se a técnica de reação em cadeia da polimerase - polimorfismo de comprimento de fragmentos de restrição (PCR-RFLP), em ovelhas Santa Inês (n= 574) e Morada Nova (n=282). O DNA foi extraído e amplificado por PCR com iniciadores específicos, que introduziram um sítio de restrição associado à mutação, em seguida os amplicons foram submetidos à ação de endonucleases. Não foram observadas as mutações Fec XG e Fec XI nas amostras estudadas. Amostras de seis animais com histórico de partos gemelares apresentaram polimorfismo para FecB semelhantes às amostras controle, mas esse padrão não foi confirmado pelo sequenciamento de nucleotídeos. Apesar da ausência dessas mutações nos animais das raças estudadas, outros fatores relacionados à prolificidade devem ser pesquisados para explicar os mecanismos da alta prolificidade desses animais.(AU)

Arginine induces GH gene expression by activating NOS/NO signaling in rat isolated hemi-pituitaries

The amino acid arginine (Arg) is a recognized secretagogue of growth hormone (GH), and has been shown to induce GH gene expression. Arg is the natural precursor of nitric oxide (NO), which is known to mediate many of the effects of Arg, such as GH secretion. Arg was also shown to increase calcium influx in pituitary cells, which might contribute to its effects on GH secretion. Although the mechanisms involved in the effects of Arg on GH secretion are well established, little is known about them regarding the control of GH gene expression. We investigated whether the NO pathway and/or calcium are involved in the effects of Arg on GH gene expression in rat isolated pituitaries. To this end, pituitaries from approximately 170 male Wistar rats (~250 g) were removed, divided into two halves, pooled (three hemi-pituitaries) and incubated or not with Arg, as well as with different pharmacological agents. Arg (71 mM), the NO donor sodium nitroprusside (SNP, 1 and 0.1 mM) and a cyclic guanosine monophosphate (cGMP) analogue (8-Br-cGMP, 1 mM) increased GH mRNA expression 60 min later. The NO acceptor hemoglobin (0.3 µM) blunted the effect of SNP, and the combined treatment with Arg and L-NAME (a NO synthase (NOS) inhibitor, 55 mM) abolished the stimulatory effect of Arg on GH gene expression. The calcium channel inhibitor nifedipine (3 µM) also abolished Arg-induced GH gene expression. The present study shows that Arg directly induces GH gene expression in hemi-pituitaries isolated from rats, excluding interference from somatostatinergic neurons, which are supposed to be inhibited by Arg. Moreover, the data demonstrate that the NOS/NO signaling pathway and calcium mediate the Arg effects on GH gene expression.

Detection of mutations within exons 4 to 8 of the p53 tumor suppressor gene in canine mammary glands / Identificação de mutações nos exons 4 a 8 do gene p53 supressor de tumor em glândulas mamárias caninas

Fifteen female canines with mammary tumors and 6 normal females were used to study mutations in exons 4 to 8 of the p53 gene. DNA samples from the tumors, respective adjacent normal mammary tissue and mammary glands from healthy animals were sequenced and analyzed for the presence of mutations. Mutations were found in 71.8% of the samples and the most frequent were missense mutations. The most attacked exons in the mammary tumor were 5, 7 and 8, with 23.4, 31.6 and 23.4% mutations, respectively. Canine mammary tumors are related to mutations in gene p53 and mutations mostly occur in the region of the protein that is linked to the DNA in the cell nucleus, which can change the functionality of the cell and propitiate tumor growth. Despite being macroscopically normal, the mammary tissue adjacent to the tumors has mutations that can lead to recurrence if not removed together with the tumor.

Para estudar as mutações nos exos 4 a 8 do gene p53, foram utilizados 15 tumores mamários, mamas normais das mesmas cadelas e seis mamas de cadelas normais. O DNA extraído das amostras de tecido foi sequenciado e analisado para a presença de mutações. Em 71,8% das amostras obtidas foram observadas mutações, sendo as "missense" as mais frequentes. Os exons mais comprometidos foram 5, 7 e 8 com 23,4, 31,6 e 23,4% de mutações, respectivamente. O estudo conclui que tumores mamários caninos têm relação com mutações no gene p53 e que as mutações ocorrem com maior frequência nas regiões da proteína que estão ligadas ao DNA no núcleo celular. Isto pode alterar a funcionalidade da proteína e propiciar o crescimento do tumor. As mamas adjacentes aos tumores, apesar da aparência macroscópica normal, apresentaram mutações, que podem representar recidivas se a mama não for retirada juntamente com o tumor.