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.

研究背景：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。本研究以共生与非共生刺胞动物为研究对象，旨在探究微卫星丰度是否呈现系统发育或生态分布模式。我们采用454 GS-FLX Titanium测序技术对8个物种的个体开展鸟枪测序，并补充纳入3个已公开的刺胞动物基因组序列（星海葵*Nematostella vectensis*、水螅*Hydra magnipapillata*及指状鹿角珊瑚*Acropora digitifera*），最终分析共涵盖刺胞动物门2纲、3亚纲、8目共11个物种。
研究结果：三核苷酸与四核苷酸重复基序为丰度最高的微卫星基序，其次为六核苷酸与二核苷酸重复基序；五核苷酸重复基序在本数据集内丰度最低。层次聚类与对数似然比检验结果显示，系统发育关系与微卫星组成仅存在微弱关联。此外，对比携带胞内甲藻的刺胞动物与不携带该共生体的类群，发现非共生类群的微卫星覆盖度更高。
研究结论：本研究结果支持既往研究结论，即无脊椎动物体内丰度最高的微卫星基序为三核苷酸与四核苷酸重复序列。共生与非共生刺胞动物在微卫星覆盖度与组成上的差异表明，胞内甲藻的有无可能对宿主基因组产生一定限制作用。