Identification of the minus-dominance gene ortholog in the mating-type locus of Gonium pectorale
Identification of the minus-dominance gene ortholog in the mating-type locus of Gonium pectorale
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DOI：
10.1534/genetics.107.078618
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发表时间：
2008-01-01
期刊：
影响因子：
3.3
通讯作者：
Nozaki, Hisayoshi
中科院分区：
文献类型：
--
作者：
Hamaji, Takashi;Ferris, Patrick J.;Nozaki, Hisayoshi
群体团簇中异配/异配的进化可能发生在所有祖先同配群体生物中，如胸藻，单细胞近亲有一个交配型（MT）基因座，其中包含几个交配型特异性基因，其中一个参与交配型决定，另一个参与仅在两个同配体之一中的管状交配结构的功能。在本研究中，作为鉴定胸肌 MT 基因座的第一步，我们从胸肌中分离出莱茵衣藻交配型决定负优势 (CrMID) 基因的直系同源物，该基因仅定位于 MT 基因座。使用简并引物的 3'-和 5'-RACE RT-PCR 鉴定出 CrMID 直系同源 164 个氨基酸编码基因 (GpMID)，在 C 末端附近含有长链拉链 RWP-RK 结构域，与 CrMID 的情况一样。基因组 Southern 印迹分析表明，GpMID 仅在胸肌负株中编码。 RT-PCR 显示 GpMID 表达在氮饥饿期间增加。对 F-1 后代的分析表明，GpMID 和异丙基苹果酸脱水酶 LEUIS 紧密相连，表明它们隐藏在与莱茵衣藻 MT 基因座相当的重组抑制下的染色体区域中。然而，莱茵衣藻 MT 基因座中存在的另外两个基因与胸肌 LEUIS/MID 没有关联，这表明 volvocalean MT 基因座的基因内容随着时间的推移并不是静态的。胸肌中叶绿体和线粒体基因组的遗传分别是来自正亲本和负亲本的单亲遗传，莱茵衣藻也是如此。
The evolution of anisogamy/oogamy in the colonial Volvocales might have Occurred in all ancestral isogamous colonial organism like Gonium pectorale, The unicellular, close relative has a mating-type (MT) locus harboring several mating-type-specific genes, including one involved in mating-type determination and another involved in the function of the tubular Mating structure in only one of the two isogamates. In this Study, as the first, step in identifying the G. pectorale MT locus, we isolated from G. pectorale the ortholog of the C. reinhardtii mating-type-determining minus-dominace (CrMID) gene, which is localized only in the MT- locus. 3'- and 5'-RACE RT-PCR using degenerate primers identified a CrMID-orthologous 164-amino-acid coding gene (GpMID) containing a lencine-zipper RWP-RK domain near the C-terminal, as is the case with CrMID. Genomic Southern blot analysis showed that GpMID was coded only in the minus strain of G. pectorale. RT-PCR revealed that GpMID expression increased during nitrogen starvation. Analysis of F-1 progeny suggested that GpMID and isopropylmalate dehydratase LEUIS are tightly linked, suggesting that they are harbored in a chromosomal region under recombinational suppression that is comparable to the C. reinhardtii MT locus. However, two other genes present in the C. reinhardtii MT locus are not linked to the G. pectorale LEUIS/MID, suggesting that the gene content of the volvocalean MT loci is not static over time. Inheritance of chloroplast and mitochondria genomes in G. pectorale is uniparental from the plus and minus parents, respectively, as is also the case in C. reinhardtii.