为认识养殖半滑舌鳎无眼侧黑化的细胞学特性,利用显微观察方法研究了其皮肤黑色素细胞、黄色素细胞和虹彩细胞的形态特征,比较了3种色素细胞在有眼侧皮肤、无眼侧正常和黑化皮肤中的数量分布特征。为进一步揭示无眼侧黑化的分子机制,克隆了半滑舌鳎pomc基因的c DNA序列。结果显示,黑色素细胞较大,含黑色和棕色的色素颗粒,有树突状分枝不明显和延伸成放射状两种形态;黄色素细胞较小,含黄色素颗粒;虹彩细胞最小,含鸟粪素颗粒。半滑舌鳎pomc基因的c DNA序列长910 bp,包括一个114 bp的5'非翻译区和一个154 bp的3'非翻译区,开放阅读框长度为642 bp,共编码213个氨基酸,包含ACTH、α-MSH、β-MSH、γ-LPH、β-内啡肽5个多肽序列,但缺失γ-MSH和大部分连接区。半滑舌鳎pomc基因的氨基酸序列与其他鱼类的同源性为30%-64%。定量PCR分析显示,pomc m RNA主要在垂体中表达,其次是脑、性腺和无眼侧黑化皮肤。正常与黑化皮肤中的差异表达结果显示,无眼侧黑化皮肤中pomc m RNA表达量最高,并与有眼侧皮肤和无眼侧正常皮肤中的pomc m RNA表达量差异显著,揭示了pomc的表达与无眼侧黑化性状密切相关。
<正>The present study examined the levels of dopamine D2 and D4 receptor mRNA expression in the brain of chronic high-fat diet-induced obese (cDIO) and obese-resistant (cDR) mice. Twenty-eight mice were fed with...
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<正>The present study examined the levels of dopamine D2 and D4 receptor mRNA expression in the brain of chronic high-fat diet-induced obese (cDIO) and obese-resistant (cDR) mice. Twenty-eight mice were fed with a high-fat diet (HF: 40% of calories from fat) for 4 weeks and then classified as the cDIO (n=8) or cDR (n=8) mice according to the highest and lowest body weight gainers. Seven mice were placed on a low-fat diet (LF: 10% of calories from fat) and were used as controls. After 20 weeks of feeding, the visceral fat deposit per gram of initial body weight was significantly higher in the cDIO group than the cDR and LF groups (0.25:0.09:0.04). Using quantitative in situ hybridization techniques, the levels of D2 and D4 receptor mRNAs were measured in multiple brain sections of mice from the 3 groups. Most regions did not differ between groups but, importantly, the cDIO mice had a significantly higher level of D2 receptor mRNA expression in the core of nucleus accumbens (AcbC) and caudate
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