本研究將一種巨蚓科蚯蚓Amynthas gracilis (Kinberg, 1867)的粒線體NADH dehydorgenase subunit 1 (ND1)基因的完整DNA序列解出。此基因的DNA序列長度為923bp，轉譯成307個胺基酸序列。A. gracilis的DNA序列及胺基酸序列與正蚓科蚯蚓Lumbricus terrestris相比較，發它們的相似性分吸達71.8%及77.7%。除此之外，此研究亦從基因銀行調出其它來自環節動物的ND1基因完整DNA序列，除了比這些序列的GC含量外，亦利用譜系分析建構出這些序列的關係。比前人在不同類群無脊椎動物的研究後，我們認為一段包含ND1、CO1與其它已發表基因在內，總長度超過3000bp的DNA序列，將有助於瞭解目前不甚清楚的巨蚓科親緣關係。

The complete sequence of the mitochondrial gene ecoding NADH dehydrogenase subunit 1 (ND1) from a megascolecid earthworm, Amynthas gracilis (Kinberg, 1867), is published in this study. The gene is 923 bp in size, encoding a polypeptide of 307 amino acid rresidues. Its nucleotide sequence and amino acid sequence are 71.8% and 7737% identical to those of the European earthworm Lumbricus terrestris ND1 gene, respectively. In addition, the GC contents among some published annelid ND1 full sequences were compared, and the relationships among these sequences were reconstructed using a phylogenetic analysis. Accordingly, we believe that a 300-bp sequence comprising the ND1 and the CO1 genes and the genes used by Jamieson et al. (2002) can be a good candidate to be used in the phylogenetic analysis to unravel the phylogeny of the Megascolecidae.