蟾蜍棒线虫线粒体全基因组特征分析

doi:10.16431/j.cnki.1671-7236.2025.07.020

摘要/Abstract

摘要： 【目的】获得蟾蜍棒线虫(Rhabdias bufonis)线粒体全基因组并分析其特征。【方法】通过PCR扩增蟾蜍棒线虫线粒体基因组序列，利用测序、注释、组装、拼接，获得线虫线粒体全基因组，对其进行序列分析；以湖沼驼形线虫(Camallanus lacustris)为外群，基于线粒体12个蛋白质编码基因(PCGs)氨基酸串联序列，采用邻接法(Neighbor-Joining,NJ)和贝叶斯法(Bayesian inference,BI)构建系统发育树进行进化分析。【结果】蟾蜍棒线虫线粒体基因组为环形结构，全长为14 208 bp，由12个PCGs、22个转运RNA(tRNAs)、2个核糖体RNA(rRNAs)和2个非编码控制区组成；其线粒体基因组碱基组成中AT含量为75%、GC含量为25%，AT偏倚(AT-skew)为0.26，GC偏倚(GC-skew)为-0.36，呈现明显的AT偏向性。PCGs以ATG、GTG作为起始密码子，以TGA、TAA及不完整的TA-作为终止密码子。tRNAs二级结构分析显示，除trnS2和trnH基因缺少二氢尿嘧啶(DHU)臂外，其余均为典型的三叶草结构。系统进化树分析显示，垫刃亚目(Tylenchina)分为两个大的分支，首叶超科(Cephaloboidea)和垫刃超科(Tylenchoidea)形成分支Ⅰ，类圆超科(Strongyloidoidea)、斯氏超科(Steinernematoidea)、滑刃超科(Aphelenchoidea)及Panagrolaimoidea形成分支Ⅱ；在分支Ⅱ中，斯氏科(Steinernematidae)和棒线科(Rhabdiasidae)聚集在一起再与滑刃科(Aphelenchoidiae)和Panagrolaimidae形成的另一姐妹支形成一个大的分支，而类圆科(Strongyloididae)则独立形成另一个大的分支；林蛙源蟾蜍棒线虫与蟾蜍源蟾蜍棒线虫(OR725306)聚集在一起，两者关系较其他两株Rhabdias kafunata亲缘关系近；寄生于两栖类棒线虫与昆虫斯氏线虫聚为一支，且与寄生于植物的滑刃科线虫亲缘关系较寄生于哺乳动物的类圆线虫近。【结论】本研究成功获得林蛙源蟾蜍棒线虫线粒体全基因组序列，且斯氏科与棒线科的亲缘关系明显近于类圆科，支持斯氏超科作为独立分类阶元的有效性，斯氏科应归于斯氏超科。试验结果为棒线科线虫的分类学、群体遗传学和系统发育学的研究提供了基础资料。

关键词: 蟾蜍棒线虫; 线粒体基因组; 序列分析; 遗传进化分析

Abstract: 【Objective】 The aim of this experiment was to obtain the complete mitochondrial genome of Rhabdias bufonis and analyze its characteristics. 【Method】 The mitochondrial genes of Rhabdias bufonis were amplified by PCR,and the whole mitochondrial genome of Rhabdias bufonis was obtained by sequencing,annotation,assembly and spliceover,and the sequence analysis was performed.Using Camallanus lacustris as an outgroup,based on the amino acid series of 12 protein-coding genes (PCGs) in mitochondria.The phylogenetic tree was constructed by Neighbor-Joining (NJ) and Bayesian inference (BI) method for evolutionary analysis. 【Result】 The mitochondrial genome of Rhabdias bufonis was a circular structure with a total length of 14 208 bp,consisting of 12 PCGs,22 tRNAs,2 rRNAs and 2 non-coding control regions.The base composition of the mitochondrial genome，AT content was 75%,GC content was 25%,AT-skew was 0.26,GC-skew was -0.36,showing obvious AT bias.PCGs used ATG and GTG as start codons and TGA,TAA and incomplete TA- as stop codon.Secondary structure analysis of tRNAs showed that the trnS2 and trnH genes lacked dihydroouracil (DHU) arm,and the rest were typical clover structures.Phylogenetic tree analysis showed that Tylenchina was divided into two large clades,Cephaloboidea and Tylenchoidea formed clade Ⅰ,Strongyloidoidea,Steinernematoidea,Aphelenchoidea and Panagrolaimoidea formed clade Ⅱ.In clade Ⅱ,Steinernematidae and Rhabdiasidae gathered together to form a branch and grouped to another sisters branch formed by Aphelenchoidiae and Panagrolaimidae.Howerver,Strongyloididae independently formed another large branch.In Rhabdiasidae,Rhabdias bufonis from forest frog in this study and the Rhabdias bufonis (OR725306) from toad gathered together,and it was more closely to two strains of Rhabdias kafunata.The amphibian-parasitic Rhabdias sp.and the insect-associated Steinernema sp.clustered together,which exhibited more closer to the plant-parasitic Aphelenchoididae than to the mammalian-parasitic Strongyloididae. 【Conclusion】 In this study,the complete mitochondrial genome sequence of Rhabdias bufonis from forest frog was obtained. The phylogenetic relationship between Steinernematidae and Rhabdiasidae was obviously close to that of Strongyloididae,supporting the validity of Steinernematoidea as an independent taxonomic order,and Steinernematidae should be included in Steinernematoidea.The results provided basic information for the taxonomy,population genetics and phylogeny of Rhabdiasidae.

Key words: Rhabdias bufonis; mitochondrial genome; sequence analysis; genetic evolutionary analysis

中图分类号:

S852.73^＋1

杨彦, 胡雁鸣, 丁健, 李犇, 何雨桐, 刘雪薇, 王佳文, 兰卓, 邱鸿宇, 高俊峰, 王春仁. 蟾蜍棒线虫线粒体全基因组特征分析[J]. 中国畜牧兽医, 2025, 52(7): 3190-3201.

YANG Yan, HU Yanming, DING Jian, LI Ben, HE Yutong, LIU Xuewei, WANG Jiawen, LAN Zhuo, QIU Hongyu, GAO Junfeng, WANG Chunren. Characterization Analysis of Complete Mitochondrial Genome of Rhabdias bufonis[J]. China Animal Husbandry & Veterinary Medicine, 2025, 52(7): 3190-3201.

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