Figure 4.

Phylogenetic tree analysis of Tumor Necrosis Factor α (TNF-α) (A) and Interleukin-1β (IL-1β) (B) originated from differences in amino acid composition of proteins identified in mammals, fish and amphibians. The circular tree demonstrates that the protein structures of mammalians is phylogenetically far respect to fish. An intermediate position is occupied by amphibians, which demonstrate sequential similarities to both mammals and fish. The protein amino acid sequences of phylogenetically close organisms are highly conserved as suggested by the link distance. The circular tree was originated by downloading the amino acid sequences from NCBI, while the distance of each entry was calculated using BLAST tool.