Sex in Symbiodiniaceae dinoflagellates: genomic evidence for independent loss of the canonical synaptonemal complex
Sex in Symbiodiniaceae dinoflagellates: genomic evidence for independent loss of the canonical synaptonemal complex
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DOI：
10.1038/s41598-020-66429-4
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发表时间：
2020-06-17
影响因子：
4.6
通讯作者：
Chan, Cheong Xin
中科院分区：
文献类型：
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作者：
Shah, Sarah;Chen, Yibi;Chan, Cheong Xin
共生甲藻科的甲藻包括多种共生体，它们对珊瑚和生活在珊瑚礁中的其他物种至关重要。众所周知，有性生殖在不断变化的环境中增强了适应性进化。虽然与减数分裂功能相关的基因在共生藻科中有报道，但减数分裂和受精的细胞学证据在这些分类群中尚未观察到。使用转录组和基因组数据从21共生菌科菌株，我们研究了基因编码的蛋白质与不同阶段的减数分裂和融合。我们报告的基因编码的联会复合体（SC），介导同源染色体配对和I类交叉的蛋白质结构的主要成分的情况下。这一结果表明，一个独立的损失典型的SC在肺泡，这也包括SC缺乏纤毛虫。我们假设，这种损失部分是由于永久浓缩的染色体和重复丰富的序列在共生藻科（和其他甲藻），有利于SC独立的II类交叉途径。我们的研究结果揭示了新的见解，在生态重要的共生藻科和其他真核生物的减数分裂分子机制的进化。
Dinoflagellates of the Symbiodiniaceae family encompass diverse symbionts that are critical to corals and other species living in coral reefs. It is well known that sexual reproduction enhances adaptive evolution in changing environments. Although genes related to meiotic functions were reported in Symbiodiniaceae, cytological evidence of meiosis and fertilisation are however yet to be observed in these taxa. Using transcriptome and genome data from 21 Symbiodiniaceae isolates, we studied genes that encode proteins associated with distinct stages of meiosis and syngamy. We report the absence of genes that encode main components of the synaptonemal complex (SC), a protein structure that mediates homologous chromosomal pairing and class I crossovers. This result suggests an independent loss of canonical SCs in the alveolates, that also includes the SC-lacking ciliates. We hypothesise that this loss was due in part to permanently condensed chromosomes and repeat-rich sequences in Symbiodiniaceae (and other dinoflagellates) which favoured the SC-independent class II crossover pathway. Our results reveal novel insights into evolution of the meiotic molecular machinery in the ecologically important Symbiodiniaceae and in other eukaryotes.