Data from: Microsatellite abundance across the Anthozoa and Hydrozoa in the phylum Cnidaria

Background: Microsatellite loci have high mutation rates and thus are indicative of mutational processes within the genome. By concentrating on the symbiotic and aposymbiotic cnidarians, we investigated if microsatellite abundances follow a phylogenetic or ecological pattern. Individuals from eight species were shotgun sequenced using 454 GS-FLX Titanium technology. Sequences from the three available cnidarian genomes (Nematostella vectensis, Hydra magnipapillata and Acropora digitifera) were added to the analysis for a total of eleven species representing two classes, three subclasses and eight orders within the phylum Cnidaria. Results: Trinucleotide and tetranucleotide repeats were the most abundant motifs, followed by hexa- and dinucleotides. Pentanucleotides were the least abundant motif in the data set. Hierarchical clustering and log likelihood ratio tests revealed a weak relationship between phylogeny and microsatellite content. Further, comparisons between cnidaria harboring intracellular dinoflagellates and those that do not, show microsatellite coverage is higher in the latter group. Conclusions: Our results support previous studies that found tri- and tetranucleotides to be the most abundant motifs in invertebrates. Differences in microsatellite coverage and composition between symbiotic and non-symbiotic cnidaria suggest the presence/absence of dinoflagellates might place restrictions on the host genome.

背景：微卫星位点（microsatellite loci）具有较高的突变率，可反映基因组内的突变过程。本研究以共生与无共生体的刺胞动物（cnidarians）为研究对象，旨在探究微卫星丰度是否遵循系统发育或生态学模式。研究对8个物种的个体采用454 GS-FLX Titanium平台开展鸟枪法测序（shotgun sequencing），并纳入已公开的3个刺胞动物基因组序列（星状海葵Nematostella vectensis、水螅Hydra magnipapillata以及指状鹿角珊瑚Acropora digitifera）进行分析，最终共纳入刺胞动物门（Cnidaria）下2纲、3亚纲、8目的11个物种。结果：三核苷酸与四核苷酸重复序列是本数据集中丰度最高的重复基序，其次为六核苷酸与二核苷酸重复序列，五核苷酸重复序列的丰度最低。层级聚类分析（hierarchical clustering）与对数似然比检验（log likelihood ratio tests）结果显示，系统发育关系与微卫星组成之间仅存在微弱关联。进一步对比携带胞内甲藻共生体的刺胞动物与无共生体的刺胞动物，发现后者的微卫星覆盖度更高。结论：本研究结果与此前在无脊椎动物中发现三、四核苷酸重复为丰度最高基序的研究结论一致。共生与非共生刺胞动物之间的微卫星覆盖度与组成差异表明，甲藻共生体的存在与否可能会对宿主基因组施加一定限制。