Cloning of
Metallotionein cDNAs and Its Gene in Shore Crab(Carcinus
maenas)
LI Bing*
( Experimental Medical Research Center, Guangzhou Medical College,
Guangzhou 510182, China )
SAVVA Demitris
( School of Animal and Microial Sciences, The Reading University, Reading,
RG6 AJ1, UK )
Abstract
Metallothioneins are cysteine-rich proteins which chelate metal ion(Zn, Cu, Hg
and Cd)and regulate ion concentrations in animal body. Based on the published amino
acid sequence of C.maenas metallothionein, completely degenerated PCR
primers were designed and two different types of cDNA were amplified from gill
tissue RNA of C.maenas using RT-PCR method. These cDNAs were cloned to
pGEM T Easy Vector and the nucleotic acid sequences were determined. The
results showed that one group of the cDNA sequence is exactly same as first 123
bases, as predicted from MTIb cDNA. Another group of cDNA was also
amplified, which is truncated and different at the 3′end of cDNA. Based on the
former cDNA sequence, specific primers were designed to amplify the full length
MTIb cDNA coding region. The MTIb gene was also amplified and
cloned into the pGEM Vectors. The gene sequence showed that MTIb gene
contains two introns(575 bp and 602 bp), dividing the gene to three exons(22
bp, 77 bp and 78 bp).
Key word shore crab metallothionein；cDNAs；gene structure
*Corresponding author：Tel,86-20-81340202；e-mail,[email protected]