CDNA CLONING OF GROWTH-HORMONE FROM THE BRUSHTAIL POSSUM (TRICHOSURUS-VULPECULA)

(1)The full-length nucleotide sequence for the cDNA of growth hormone (GH) from the marsupial brushtail possum (Trichosurus vulpecula) was d etermined using reverse transcription followed by polymerase chain rea ction (RT-PCR) and the 5'/3' rapid amplification of cDNA ends (RACE) t echnique. Sequence information showed that the possum GH cDNA was 831 base pairs (bp) in length, including the 5' untranslated region (60 bp ), the signal peptide (75 bp), the mature protein (573 bp, including s top codon), and the 3' untranslated region (123 bp). At both the nucle otide and the amino acid level (deduced from nucleotide sequence), the re was a high degree of sequence identity with pig and horse. These sp ecies were similar at 82.8 and 83.0% of bases at the nucleotide level and 91.6 and 91.1% at the amino acid level, respectively. Northern ana lysis showed that GH mRNA is present in the pituitary gland and was si milar in size to that seen in other mammals (approximate to 0.9 kb). A nalysis of molecular evolution of GH in the possum indicated that the rate of evolution is relatively slow (0.4 substitutions/amino acid sit e/year x 10(9)) and typical of that seen for nonprimate mammals, which exhibit rates ranging between 0.2 and 1.2 substitutions/amino acid si te/year x 10(9). (C) 1998 Academic Press.