Microarray analysis of Med23 mutation in E9.5 mouse embryos relative to control littermates

Development of the vertebrate head is a complex and dynamic process, which requires integration of all three germ layers and their derivatives. Of special importance are ectoderm-derived cells that form the cranial placodes, which then differentiate into the cranial ganglia and sensory organs. Critical to a fully functioning head, defects in cranial placode and sensory organ development can result in congenital craniofacial anomalies. In a forward genetic screen aimed at identifying novel regulators of craniofacial development, we discovered an embryonically lethal mouse mutant, snouty, which exhibits malformation of the facial prominences, cranial nerves and vasculature. The snouty mutation was mapped to a single nucleotide change in a ubiquitously expressed gene, Med23, which encodes a subunit of the global transcription co-factor complex, Mediator. This experiment examines transcriptional differences between Med23 mutant mice and their wt littermates at embryonic day 9.5. Two wt and three Med23 mutant embryos are compared across 6 microarrays using a dye swap strategy. The third mutant is compared to a mixture of the 1st and 2nd wt replicates.脊椎动物头部的发育是一个复杂且动态的过程，需要整合三个胚层及其衍生物。其中尤为关键的是外胚层来源的细胞，这些细胞可形成颅基板（cranial placodes），随后分化为颅神经节与感觉器官。颅基板与感觉器官的正常发育是头部行使正常功能的关键，其发育缺陷可引发先天性颅面畸形。 在一项旨在筛选颅面发育新型调控因子的正向遗传筛选（forward genetic screen）中，我们发现了一种胚胎致死的小鼠突变体snouty，该突变体表现出面突、颅神经及脉管系统的畸形。snouty突变被定位至一个遍在表达基因Med23的单核苷酸变异位点，该基因编码全局转录辅因子复合物中介体（Mediator）的一个亚基。 本实验旨在检测胚胎发育第9.5天的Med23突变型小鼠与其野生型（wild type，wt）同窝仔鼠之间的转录表达差异。研究采用染料交换（dye swap）策略，借助6张微阵列（microarrays）芯片对2只野生型胚胎与3只Med23突变型胚胎进行比较分析；其中第3只突变型胚胎与第1、2只野生型重复样本的混合样品进行比对。