Pérez-Enciso Miguel, Ferraz André L J, Ojeda Ana, López-Béjar Manel
Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
BMC Genomics. 2009 Feb 24;10:89. doi: 10.1186/1471-2164-10-89.
Transcriptome variability is due to genetic and environmental causes, much like any other complex phenotype. Ascertaining the transcriptome differences between individuals is an important step to understand how selection and genetic drift may affect gene expression. To that end, extant divergent livestock breeds offer an ideal genetic material.
We have analyzed with microarrays five tissues from the endocrine axis (hypothalamus, adenohypophysis, thyroid gland, gonads and fat tissue) of 16 pigs from both sexes pertaining to four extreme breeds (Duroc, Large White, Iberian and a cross with SinoEuropean hybrid line). Using a Bayesian linear model approach, we observed that the largest breed variability corresponded to the male gonads, and was larger than at the remaining tissues, including ovaries. Measurement of sex hormones in peripheral blood at slaughter did not detect any breed-related differences. Not unexpectedly, the gonads were the tissue with the largest number of sex biased genes. There was a strong correlation between sex and breed bias expression, although the most breed biased genes were not the most sex biased genes. A combined analysis of connectivity and differential expression suggested three biological processes as being primarily different between breeds: spermatogenesis, muscle differentiation and several metabolic processes.
These results suggest that differences across breeds in gene expression of the male gonads are larger than in other endocrine tissues in the pig. Nevertheless, the strong presence of breed biased genes in the male gonads cannot be explained solely by changes in spermatogenesis nor by differences in the reproductive tract development.
转录组变异性如同其他任何复杂表型一样，是由遗传和环境因素导致的。确定个体间的转录组差异是理解选择和遗传漂变如何影响基因表达的重要一步。为此，现存的不同家畜品种提供了理想的遗传材料。
我们使用微阵列分析了来自四个极端品种（杜洛克猪、大白猪、伊比利亚猪以及与中欧杂交系的杂交猪）的16头猪（雌雄各半）内分泌轴的五个组织（下丘脑、腺垂体、甲状腺、性腺和脂肪组织）。使用贝叶斯线性模型方法，我们观察到最大的品种变异性对应于雄性性腺，且大于包括卵巢在内的其他组织。屠宰时对外周血性激素的测量未检测到任何与品种相关的差异。不出所料，性腺是具有最多性别偏向基因的组织。性别和品种偏向表达之间存在很强的相关性，尽管大多数品种偏向基因并非最具性别偏向的基因。连通性和差异表达的综合分析表明，品种之间主要在三个生物学过程上存在差异：精子发生、肌肉分化和几个代谢过程。
这些结果表明，猪的雄性性腺基因表达的品种差异大于其他内分泌组织。然而，雄性性腺中强烈存在的品种偏向基因不能仅通过精子发生的变化或生殖道发育的差异来解释。
