Cloning and expression analysis of an o-methyltransferase (OMT) gene from Chinese shrimp, Fenneropenaeus chinensis

O-methyltransferase (OMT) is ubiquitously present in diverse organisms and plays an important regulatory role in plant and animal growth, development, reproduction and defence and has also been implicated in human emotion and disease. A putative o-methyltransferase (OMT) gene has been cloned from the haemocytes of bacteria-infected Chinese shrimp (Fenneropenaeus chinensis) by suppression subtractive hybridisation (SSH) coupled with the SMART cDNA method. The isolated 944 bp full-length cDNA contains a single 666 bp open reading frame (ORF) encoding a putative OMT protein of 221 amino acids. The predicted protein has a molecular weight of 24 572.06 Da and a pI of 5.27 as well as ten phosphorylation sites. Northern blot and in situ hybridisation analyses demonstrated that the OMT transcripts were constitutively expressed in tissue of shrimp challenged by bacterial infection and in unchallenged shrimp tissue. Constitutive OMT transcript was found in areas such as haemocytes, heart, hepatopancreas, stomach, gill, intestine and ovary. However, the OMT transcripts were upregulated in hepatopancreas and stomach in challenged shrimp.