RESUMO Porcos tibetanos são caracterizados por diferenças fenotípicas significativas em relação aos porcos de planície. Nosso estudo anterior demonstrou que os genes CRYAB e CTGF eram expressos diferentemente nos tecidos do coração entre os porcos tibetanos (raça das terras altas) e Yorkshire (raça das terras baixas), indicando que eles poderiam participar da adaptação à hipoxia. CRYAB (ɑB-crystallin) e CTGF (fator de crescimento do tecido conjuntivo) também foram relatados como estando associados ao desenvolvimento pulmonar. Entretanto, os padrões de expressão do CRYAB e CTGF nos tecidos pulmonares em diferentes altitudes e sua caracterização genética não são bem compreendidos. Neste estudo, o qRT-PCR e a mancha ocidental de tecido pulmonar revelou níveis de expressão de CRYAB mais elevados em porcos tibetanos e Yorkshire de altitude e média altitude do que em seus pares de planície. Com um aumento na altitude, o nível de expressão do CTGF aumentou nos porcos tibetanos, enquanto diminuiu nos porcos Yorkshire. Além disso, foram identificados dois novos polimorfismos de um único nucleotídeo na região flanqueadora de CRYAB (g.39644482C>T e g.39644132T>C) e CTGF (g.31671748A>G e g.31671773T>G). O polimorfismo pode contribuir parcialmente com as diferenças nos níveis de expressão entre grupos a uma mesma altitude. Estas descobertas proporcionam novos conhecimentos sobre as adaptações de hipoxia a alta altitude dos porcos tibetanos.

ABSTRACT Tibetan pigs are characterized by significant phenotypic differences relative to lowland pigs. Our previous study demonstrated that the genes CRYAB and CTGF were differentially expressed in heart tissues between Tibetan (highland breed) and Yorkshire (lowland breed) pigs, indicating that they might participate in hypoxia adaptation. CRYAB (ɑB-crystallin) and CTGF (connective tissue growth factor) have also been reported to be associated with lung development. However, the expression patterns of CRYAB and CTGF in lung tissues at different altitudes and their genetic characterization are not well understood. In this study, qRT-PCR and western blot of lung tissue revealed higher CRYAB expression levels in highland and middle-highland Tibetan and Yorkshire pigs than in their lowland counterparts. With an increase in altitude, the expression level of CTGF increased in Tibetan pigs, whereas it decreased in Yorkshire pigs. Furthermore, two novel single-nucleotide polymorphism were identified in the 5′ flanking region of CRYAB (g.39644482C>T and g.39644132T>C) and CTGF (g.31671748A>G and g.31671773T>G). The polymorphism may partially contribute to the differences in expression levels between groups at the same altitude. These findings provide novel insights into the high-altitude hypoxia adaptations of Tibetan pigs.

ABSTRACT Aquaporin 2 (AQP2) is a small protein located in the collecting tubules of kidneys; it plays an important role in the concentration and production of urine. The aim of this study was to determine the expression level of the AQP2 gene in the kidney of broiler chickens after the administration of renaldose dopamine. Broiler chickens (25 days-old) were randomly divided into two groups (n=20 per group): intravenous administration of saline solution (control group) or renal-dose dopamine (dopamine group). The expression and localization of the AQP2 gene were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry (IHC), respectively. The protein level of AQP2 was analyzed by western blot analysis. The dopamine group presented no significant difference (p>0.05) in the biochemical criterion or mRNA expression of AQP2 compared with the control group. However, AQP2 protein level was significantly reduced (p<0.05) in the membrane of renal tubular epithelial cells. In contrast, protein level was significantly increased (p<0.05) in the cytoplasm of the dopamine group compared with the control group. Moreover, AQP2 protein was apparently more distributed and localized in the cytoplasmic vacuoles than in the membranes of the kidney in the renaldose dopamine administered chickens group. In conclusion, present findings suggest that renaldose dopamine mediates the level of AQP2 protein via shuttle from the cell membrane to the cytoplasm rather than changing the expression of AQP2 gene to adjust the secretion and absorption of water in kidney.