Data from: Duplication and sub/neofunctionalization of Malvolio, an insect homolog of Nramp, in the subsocial beetle Nicrophorus vespilloides

With growing numbers of sequenced genomes, increasing numbers of duplicate genes are uncovered. Here we examine Malvolio, a gene in the natural resistance-associated macrophage protein (Nramp) family, that has been duplicated in the subsocial beetle, Nicrophorus vespilloides, which exhibits advanced parental behavior. There is only one copy of Mvl in honey bees and Drosophila, whereas in vertebrates there are two copies that are subfunctionalized. We first compared amino acid sequences for Drosophila, beetles, mouse and humans. We found a high level of conservation between the different species, though there was greater variation in the C-terminal regions. A phylogenetic analysis across multiple insect orders suggests that Mvl has undergone several independent duplications. To examine the potential for different functions where it has been duplicated, we quantified expression levels of Mvl1 and Mvl2 in eight tissues in N. vespilloides. We found that while Mvl1 was expressed ubiquitously, albeit at varying levels, expression of Mvl2 was limited to brain and midgut. Because Mvl has been implicated in behavior, we examined expression during different behavioral states that reflected differences in opportunity for social interactions and expression of parental care behaviors. We found differing expression patterns for the two copies, with Mvl1 increasing in expression during resource preparation and feeding offspring, and Mvl2 decreasing in these same states. Given these patterns of expression, along with the protein analysis, we suggest that Mvl in N. vespilloides has experienced sub/neofunctionalization following its duplication, and may be evolving differing and tissue-specific roles in behavior and physiology.随着测序完成的基因组数量持续增加，新发现的重复基因数目也日益增多。本研究聚焦于自然抗性相关巨噬细胞蛋白（natural resistance-associated macrophage protein, Nramp）家族中的Malvolio基因——该基因在具有高级双亲行为的亚社会性埋葬虫（Nicrophorus vespilloides）中发生了复制事件。果蝇（Drosophila）与蜜蜂体内仅存在单个Mvl拷贝，而脊椎动物中则存在两个发生了亚功能化的Mvl拷贝。我们首先比对了果蝇、埋葬虫、小鼠与人类的氨基酸序列，结果发现不同物种间的序列保守性较高，但C端区域的变异程度更为显著。对多个昆虫纲类群开展的系统发育分析表明，Mvl基因经历了多次独立的复制事件。为探究该基因复制后潜在的功能分化情况，我们对N. vespilloides的8种组织中Mvl1与Mvl2的表达水平进行了定量检测。结果显示，尽管Mvl1呈广谱表达且表达水平存在差异，但Mvl2的表达仅局限于脑组织与中肠。鉴于Mvl已被证实与行为调控相关，我们进一步检测了反映不同社会交互机会与双亲抚育行为状态下的基因表达情况。结果发现两个拷贝的表达模式存在显著差异：Mvl1在资源准备与抚育后代阶段的表达量上升，而Mvl2在相同状态下的表达量则出现下降。结合上述表达模式与蛋白质序列分析结果，我们推测N. vespilloides中的Mvl基因在复制后经历了亚功能化/新功能化，其在行为与生理过程中可能演化出了不同的组织特异性功能。