Cloning and mRNA expression levels of αtubulin cDNAs from three noctuid spelies
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Key Words：Noctuidae， insect， αtubulin， cloning， mRNA expression
Abstract：Total RNA was isolated from the prepupae of Spodoptera exigua, Agrotis ypsilon and Agrotis c-nigrum, respectively. Three αtubulin cDNA sequences were cloned by RT-PCR and rapid amplification of cDNA ends (RACE). The three cDNA sequences all contain an open reading frame of 1 353 base pairs. Each cDNA sequence encodes a polypeptide of 450 amino acid residues with a predicted molecular weight of about 50 kDa. There is a tubulin signature sequence GGGTGSG at positions 142 to 148 of the deduced amino acid sequence. The C-terminal tyrosine residue is conserved. The MRECI domain, probably implicated in the posttranscriptionalautoregulatory mechanisms, was found at the N-terminus. Three αtubulin cDNA sequences and their deduced amino acid sequences share high homology with those from other insects. The identities between the three isolated nucleotides and between the deduced amino acids are 94.4%～97.1% and 100%, respectively. RT-PCR showed that α-tubulin mRNA could be detected in the 4th, 5th and 6th instars and pupae, and also in the gut, integument and fat bodies of the 6th instar larvae.