Department of Entomology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
Institute of Vegetable Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, Jiangsu, China.
BMC Genomics. 2018 Jun 18;19(1):466. doi: 10.1186/s12864-018-4868-6.
Mitochondrial (mt) genomes of animals typically contain 37 genes for 13 proteins, two ribosomal RNA (rRNA) genes and 22 transfer RNA (tRNA) genes. In sarcoptiform mites, the entire set of mt tRNA genes is present in Aleuroglyphus ovatus, Caloglyphus berlesei, Dermatophagoides farinae, D. pteronyssinus, Histiostoma blomquisti and Psoroptes cuniculi. Loss of 16 mt tRNA genes, however, was reported in Steganacarus magnus; loss of 2-3 tRNA genes was reported in Tyrophagus longior, T. putrescentiae and Sarcoptes scabiei. Nevertheless, convincing evidence for mt gene loss is lacking in these mites.
We sequenced the mitochondrial genomes of two sarcoptiform mites, Histiostoma feroniarum (13,896 bp) and Rhizoglyphus robini (14,244 bp). Using tRNAScan and ARWEN programs, we identified 16 and 17 tRNA genes in the mt genomes of H. feroniarum and R. robini, respectively. The other six mt tRNA genes in H. feroniarum and five mt tRNA genes in R. robini can only be identified manually by sequence comparison when alternative anticodons are considered. We applied this manual approach to other mites that were reported previously to have lost mt tRNA genes. We were able to identify all of the 16 mt tRNA genes that were reported as lost in St. magnus, two of the three mt tRNA genes that were reported as lost in T. longior and T. putrescentiae, and the two mt tRNA genes that were reported as lost in Sa. scabiei. All of the tRNA genes inferred from these manually identified genes have truncation in the arms and mismatches in the stems.
Our results reveal very unconventional tRNA structures in sarcoptiform mites and do not support the loss of mt tRNA genes in these mites. The functional implication of the drastic structural changes in these tRNA genes remains to be investigated.
动物的线粒体（mt）基因组通常包含 13 种蛋白质的 37 个基因、2 个核糖体 RNA（rRNA）基因和 22 个转移 RNA（tRNA）基因。在革螨目中，Aleuroglyphus ovatus、Caloglyphus berlesei、Dermatophagoides farinae、D. pteronyssinus、Histiostoma blomquisti 和 Psoroptes cuniculi 中存在整套 mt tRNA 基因。然而，Steganacarus magnus 报告了 16 个 mt tRNA 基因的缺失；Tyrophagus longior、T. putrescentiae 和 Sarcoptes scabiei 报告了 2-3 个 tRNA 基因的缺失。然而，这些螨类中缺乏 mt 基因缺失的令人信服的证据。
我们对两种革螨的线粒体基因组进行了测序，即 Histiostoma feroniarum（13896bp）和 Rhizoglyphus robini（14244bp）。使用 tRNAScan 和 ARWEN 程序，我们分别在 H. feroniarum 和 R. robini 的 mt 基因组中鉴定了 16 和 17 个 tRNA 基因。在 H. feroniarum 中，其他六个 mt tRNA 基因和在 R. robini 中，只有在考虑替代反密码子时才能通过序列比较手动识别。我们将这种手动方法应用于先前报道丢失 mt tRNA 基因的其他螨虫。我们能够识别以前报道在 St. magnus 中丢失的 16 个 mt tRNA 基因中的所有基因、以前报道在 T. longior 和 T. putrescentiae 中丢失的三个 mt tRNA 基因中的两个以及以前报道在 Sa. scabiei 中丢失的两个 mt tRNA 基因。从这些手动鉴定的基因推断出的所有 tRNA 基因在臂上都有截断，在茎上都有不匹配。
我们的结果揭示了革螨中非常非常规的 tRNA 结构，并且不支持这些螨类中 mt tRNA 基因的缺失。这些 tRNA 基因结构剧烈变化的功能意义仍有待研究。
