新興小鼠毛蟎的外觀形態與分子特徵

Abstract

Myobia murismusculi (又名Myobia musculi, MOB)、 Radfordia affinis (RDA)、Myocoptes musculinus (COP)是當代最常見的三種實驗小鼠外寄生蟲。臺灣大學獸醫專業學院實驗動物醫學診斷研究室例行性健康監測中，發現一個疑似新興毛蟎感染病例。在這個研究，我們根據外觀資料(結構與特徵)與分子生物數據(核醣體核醣核酸ribosomal RNA [rRNA]與二級結構)以分析此新興毛蟎特徵與鑑定其物種分類，並將此小鼠毛蟎暫命名為Species A (SPA)。我們將三種小鼠毛蟎SPA、RDA和COP的18S與28S rRNA的基因序列與其他過去已經發佈的蟎蟲基因做數據比較分析，18S及28S rRNA基因的親緣分析顯示SPA與MOB及RDA應屬於同一個科(Myobiidae family)，而COP與SPA的親緣關係較遠。此外，28S rRNA的二級結構比較顯示結構雖然相似，但部分區域的結構多樣性建議未來可應用於類似SPA新興毛蟎物種的分辨。在SPA與其他小鼠蟎蟲的外觀特徵比較顯示SPA與MOB在外觀上難以辨別，與RDA的體型大小相似，但微細結構特徵仍不同，而與COP外表形狀有明顯差異，因此根據外觀分析建議SPA是Myobia屬的新成員。這篇研究的結論支持SPA與MOB相近，且SPA是Myobiidae科Myobia屬的新發現小鼠毛蟎。

Myobia murismusculi (aka Myobia musculi, MOB), Radfordia affinis (RDA) and Myocoptes musculinus (COP) are the three most prevalent ectoparasite species in contemporary laboratory mice. In this study, based on the morphological and molecular evidences and the predicted secondary structures of ribosomal RNA (rRNA), we have identified and characterized a novel fur mite from naturally infested laboratory mice and designated as Species A (SPA). The nucleotide sequences of the 18S and/or 28S rRNA genes of SPA, RDA, and COP were determined and compared with other previously characterized mites. Phylogenetic analysis results of the 18S and/or 28S rRNA gene sequences revealed that SPA belongs to the same family as MOBs and RDAs, and COP is least related to SPA. Genetic distance results indicated that SPA is most closely related to MOBs and RDAs, but distinctly different from COP. The comparison of the predicted secondary structures of 28S rRNA revealed that structural variations could be possibly applied in differentiating SPA-like organisms from other fur mites in the future. Comparison of morphological characters of SPA and other mouse fur mites showed that SPA is externally indistinguishable from MOB, with similar shape/size but different external structures to RDA, and highly distinct to COP in shape and externals. SPA was a novel member of Myobia genus. In conclusion, SPA was a novel member of Myobia genus in the family Myobiidae with MOB.