Anisogamy evolved with a reduced sex-determining region in volvocine green algae.
Anisogamy evolved with a reduced sex-determining region in volvocine green algae.
复制标题
DOI：
10.1038/s42003-018-0019-5
复制
发表时间：
2018
影响因子：
5.9
通讯作者：
Nozaki H
中科院分区：
文献类型：
--
作者：
Hamaji T;Kawai-Toyooka H;Uchimura H;Suzuki M;Noguchi H;Minakuchi Y;Toyoda A;Fujiyama A;Miyagishima SY;Umen JG;Nozaki H
大小不同的雄性和雌性配子（异性配子）独立于各种真核谱系中的同配祖先而出现，尽管这种出现的遗传基础仍然未知。沃尔沃辛绿藻是研究从同配性到异配性转变的模型谱系。在这里，我们重点关注两个密切相关的 volocine 属，它们支持这种转变——同配的 Yamagishiella 和异配的 Eudorina。我们生成了 Yamagishiella 和 Eudorina 两种性别的从头核基因组组装，以鉴定每种性别决定染色体区域或交配型基因座 (MT) 的二态性。与纯配子Volvox的大(>1 Mb)和复杂的MT相比，Yamagishiella和Eudorina MT更小(7-268 kb)并且更简单，只有两个性别限制基因——负/雄性限制的MID和正/雌性限制的FUS1。在这两个物种中都没有发现明显的二态性配子体。因此，volvocine 藻类异配的第一步可能是在不增加 MT 大小和复杂性的情况下发生的。滨路隆 等人报告了两种 volocine 绿藻物种的基因组组装，跨越了从同配性到异配性的转变。出乎意料的是，他们发现这两个物种的交配型位点（MT）都很简单，这表明它们向异配性的转变是在没有增加 MT 大小和复杂性的情况下发生的。
Male and female gametes differing in size—anisogamy—emerged independently from isogamous ancestors in various eukaryotic lineages, although genetic bases of this emergence are still unknown. Volvocine green algae are a model lineage for investigating the transition from isogamy to anisogamy. Here we focus on two closely related volvocine genera that bracket this transition—isogamous Yamagishiella and anisogamous Eudorina. We generated de novo nuclear genome assemblies of both sexes of Yamagishiella and Eudorina to identify the dimorphic sex-determining chromosomal region or mating-type locus (MT) from each. In contrast to the large (>1 Mb) and complex MT of oogamous Volvox, Yamagishiella and Eudorina MT are smaller (7–268 kb) and simpler with only two sex-limited genes—the minus/male-limited MID and the plus/female-limited FUS1. No prominently dimorphic gametologs were identified in either species. Thus, the first step to anisogamy in volvocine algae presumably occurred without an increase in MT size and complexity. Takashi Hamaji et al. report genome assemblies for two volvocine green algae species spanning the transition from isogamy to anisogamy. Unexpectedly, they found that both species’ mating type loci (MT) are simple, suggesting their transition to anisogamy occurred without increased MT size and complexity.