3.1 Mitogenome Organization and Base Composition
The total lengths of the mitogenomes of Amipittia virgata ,Halpe nephele and Onryza maga are 15,333 bp, 15,291 bp and 15,381 bp, respectively (Figure 1). The gene order and organization are similar to those of other butterflies previously determined, containing 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs) and a non-coding AT-rich region. Among them, 14 genes (trnQ ,trnC , trnY , trnF , nad5 , trnH ,nad4 , nad4L , trnP , nad1 , trnL1 ,rrnL , trnV , rrnS ) are encoded from the N-strand, and the remaining 23 genes (trnM , trnI , nad2 ,trnW , cox1 , trnL2 , cox2 , trnK ,trnD , atp8 , atp6 , cox3 , trnG ,nad3 , trnA , trnR , trnN , trnS1 ,trnE , trnT , nad6 , cytb , trnS2 ) are from the J-strand (Table 2).
Nucleotide composition of is A. virgata is A=39.7%, C=11.8%, G=7.5% and it is T=41.0%. The base composition of H. nephele is A=40.3%, C=12.3%, G=7.6% and T=39.7%. And A=39.8%, C=12.2%, G=7.7% and T=40.2% in O. maga. The A+T content are 80.7%, 80.0% and 80.0% respectively, showing a relatively strong AT bias (Table 3). Compared with the whole genome, the non-coding AT-rich region (NCR) has the highest AT content, up to 89.7%, 89.3%, and 91.9%, respectively. On the contrary, PCGs are the regions with the lowest AT content, which is 79.1%, 78.4%, 78.2% respectively. In addition, the T content of these mitogenomes is higher than that of A, with the exception of H. nephele (Table 3).