TITLE:
Chondrichthyes Chitinase: Molecular Cloning, Distribution, and Phylogenetic Analysis
AUTHORS:
Miku Watanabe, Hiromi Kakizaki, Momo Kanai, Satoshi Kawashima, Kaneyuki Hamaguchi, Hiroki Mizuno, Tsubasa Ueno, Chiaki Yasukawa, Ryuji Agata, Mana Ikeda, Hideto Fukushima, Mitsuhiro Ueda, Masahiro Matsumiya
KEYWORDS:
Chitinase, Distribution, Chondrichthyes, cDNA Cloning, Phylogenetic Analysis
JOURNAL NAME:
Open Journal of Marine Science,
Vol.8 No.1,
January
31,
2018
ABSTRACT: We have previously reported the presence of three types of chitinase (acidic
fish chitinase-1: AFCase-1, acidic fish chitinase-2: AFCase-2, fish chitinase-3:
FCase-3) in Actinopterygii. In the present research, we report the identification
of the novel chitinase genes HjChi (ORF: 1380 bp) and DkChi (ORF:
1440 bp) from the stomach of Chondrichthyes, Japanese bullhead shark (Heterodontus
japonicas) and Kwangtung skate (Dipturus kwangtungensis), respectively.
Organ-specific expression analysis identified the stomach-specific
expression of HjChi, whereas DkChi was expressed widely in all organs. Chitinase
activity was measured using pNP-(GlcNAc)n (n = 2, 3) as a substrate
and β-N-acetylhexosaminidase (Hex) activity was measured using pNPGlcNAc.
Relatively high values of chitinase activity were observed in the stomach,
spleen, and gonads of the Japanese bullhead shark, H. japonicas , compared
with that observed in the stomach of the Kwangtung skate D. kwangtungensis
. However, Hex activity was detected throughout the body of both
species. The optimal pH of chitinase in both the Japanese bullhead shark, H.
japonicas, and the Kwangtung skate, D. kwangtungensis, were 3.5 - 5.5 and
3.5 - 4.0, respectively, and 4.0 for Hex in both species. Phylogenetic analysis
revealed that Chondrichthyes chitinase forms a unique group (Chondrichthyes
chitinase). These results suggested that the possibility of the formation
of chitinase groups for each class in the phylogenetic analysis based on the
observation of class-specific chitinase.