Analysis of Codon Usage Patterns in Based on Transcriptome Data from DB.

, a flagellated parasitic protozoan, the most common cause of parasite-induced diarrheal diseases worldwide. Codon usage bias (CUB) is an important evolutionary character in most species. However, CUB remains unclear. Thus, this study analyzes codon usage patterns to assess the restriction factors and obtain useful information in shaping CUB. The neutrality analysis result indicates that has a wide GC3 distribution, which significantly correlates with GC12. ENC-plot result-suggesting that most genes were close to the expected curve with only a few strayed away points. This indicates that mutational pressure and natural selection played an important role in the development of CUB. The Parity Rule 2 plot (PR2) result demonstrates that the usage of GC and AT was out of proportion. Interestingly, we identified 26 optimal codons in the genome, ending with G or C. In addition, GC content, gene expression, and protein size also influence CUB formation. This study systematically analyzes codon usage pattern and clarifies the mechanisms of CUB. These results will be very useful to identify new genes, molecular genetic manipulation, and study of evolution.