Meeting Abstract

16.4  Thursday, Jan. 3  The nucleic acid sequence and gene structure of the hemoglobins of the brittle star Hemipholis elongata Say CHRISTENSEN, A.B.*; CHRISTENSEN, E.F.; SUKHODOLETS, M.V.; Lamar University, Beaumont, TX; Lamar University, Beaumont, TX; Lamar University, Beaumont, TX christenab@my.lamar.edu

The burrowing brittle star Hemipholis elongata expresses two hemoglobins, fraction 1 and fraction 2 that are packaged in coelomocytes present in the water vascular system. Using a poly T primer and primers designed from the partial amino acid sequences of the two globins, cDNA was amplified by PCR and sequenced. Sequences for both globins translate into a protein of 144 amino acid residues that differ by 15 amino acids. They share a 89% homology in both nucleotide and amino acid sequences. PCR amplification of genomic DNA reveals the presence of three introns, two of which occupy positions typical of vertebrate and many invertebrate globins. The third intron occupies an unusual position occurring between the start codon and the codon for the first amino acid of the globin. This position appears to be homologous to a third intron reported for the sea cucumber Caudina arenicola globin C, which occurs at the junction of an amino terminal extension of nine amino acids. Preliminary evidence suggests that there may be at least two sequences associated with fraction 1. In one version the third intron is approximately 440 nucleotides long and in the other is approximately 610 nucleotides.