Delineating a New Heterothallic Species of Volvox (Volvocaceae, Chlorophyceae) Using New Strains of "Volvox africanus".
Delineating a New Heterothallic Species of Volvox (Volvocaceae, Chlorophyceae) Using New Strains of "Volvox africanus".
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DOI：
10.1371/journal.pone.0142632
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Takahashi F
中科院分区：
文献类型：
--
作者：
Nozaki H;Matsuzaki R;Yamamoto K;Kawachi M;Takahashi F
沃尔沃辛藻类代表了一个优秀的模型谱系，可以根据相关物种的比较分析来研究雌性和雄性的进化。在这些物种中，Volvox carteri 作为一种受精且复杂的生物体模型已被广泛研究。然而，它可能具有其他沃尔沃物种所不存在的独特衍生特征。因此，有关团簇其他物种有性繁殖特征的信息也很重要。 1971 年，斯塔尔研究了几种被鉴定为非洲团藻 (Volvox africanus) 的全球菌株的四种性行为；然而，缺乏对这些菌株的进一步分类学研究，并且四种性类型中的三种的菌株尚不可用。在这里，我们研究了最近从日本琵琶湖分离出的两种非洲弧菌的形态、有性生殖和分类学。这两个物种与 Starr 在 1971 年描述的两种有性类型非常相似：一种在异宗体品系中产生雌雄异株的有性球体，另一种在单一品系中形成雄性球体和雌雄同株的球体。前一个物种产生具有网状细胞壁的受精卵，而后一个物种中观察到光滑的受精卵壁，如之前在世界各地报道的非洲弧菌。我们的多基因系统发育分析表明，这些物种彼此是姐妹物种。然而，核核糖体 DNA 内转录间隔区 2 二级结构最保守区域存在补偿性碱基变化，交叉实验证明杂种不存活，球体中相邻细胞（单个鞘）的凝胶材料之间邻接密度的形态差异支持对两个物种的识别，即具有光滑合子壁的非洲弧菌和野崎弧菌。 sp。十一月具有网状合子壁。
The volvocine algae represent an excellent model lineage in which to study evolution of female and male genders based on comparative analyses of related species. Among these species, Volvox carteri has been extensively studied as a model of an oogamous and complex organism. However, it may have unique derived features that are not present in other species of Volvox. Therefore, information regarding the characteristics of sexual reproduction of other species of Volvox is also important. In 1971, Starr studied four types of sexuality in several global strains identified as Volvox africanus; however, further taxonomic studies of these strains have been lacking, and strains of three of the four sexual types are not available. Here, we studied the morphology, sexual reproduction, and taxonomy of two V. africanus-like species isolated recently from Lake Biwa, Japan. These two species were very similar to two sexual types described by Starr in 1971: one producing dioecious sexual spheroids in heterothallic strains and the other forming both male spheroids and monoecious spheroids in a single strain. The former species produced zygotes with a reticulate cell wall, whereas a smooth zygote wall was observed in the latter species as in V. africanus previously reported from various localities around the world. Our multigene phylogenetic analysis demonstrated that these are sister species to each other. However, the presence of a compensatory base change in the most conserved region of the secondary structure of nuclear ribosomal DNA internal transcribed spacer-2, hybrid inviability demonstrated by intercrossing experiments, and morphological differences in the density of abutment between the gelatinous material of adjacent cells (individual sheaths) in the spheroid supported the recognition of the two species, V. africanus having a smooth zygote wall and V. reticuliferus Nozaki sp. nov. having a reticulate zygote wall.