Cloning and expression of hyperglycemic (CHH) and molt-inhibiting (MIH) hormones mRNAs from the eyestalk of shrimps of Litopenaeus vannamei grown in different temperature and salinity conditions

This study describes the effect of temperature and salinity on the expression of chh and mih genes obtained from Litopenaeus vannamei juveniles. Results suggest that temperature had a higher effect on gene expression than salinity. Two different mih transcripts were obtained from the eyestalks of shrimps exposed to 20 °C. Direct sequence evidence suggests that these two isoforms come from a mih gene transcribed in an alternative splicing manner.The genome-cDNA alignment suggests that the mih-1 contains 4 exons and gives rise to a mature MIH-like peptide of 73 amino acids (Liv-MIH-1), while mih-2 contains exons I, II and IV and gives rise to a mature MIH-like peptide of 74 residues (Liv-MIH-2). The chh transcript is suggested to consist of 3 exons and gives rise to a mature peptide of 74 amino acids (Liv-CHH). The exon–intron boundary of the mih and chh genes follows Chambon's rule (GT-AG) for the splice donor and acceptor sites. Gene structure and phylogenetic analysis imply that these three peptides are more related to the CHH group than to the MIH/GIH group. Liv-MIH and Liv-MIH-2 may have a multi-functional role as observed in other CHH family members.