Biomedical subjects

S J Delaney

Publications and source records attributed to S J Delaney.

21 records · Page 2Linked to original sources

PubMed1986

Sequence conservation around the 5' ends of the larval serum protein 1 genes of Drosophila melanogaster.

We have determined the nucleotide sequence at the 5' ends of the genes for the alpha, beta and gamma polypeptides of larval serum protein 1 (LSP1) of Drosophila melanogaster. In their upstream regions, the three genes share homology around the TATA boxes. There is also a homologous region of about 20 nucleotides at positions 200, 216 and 377 upstream from the alpha, beta and gamma genes, respectively. Another 18-nucleotide homology occurs between a sequence 111 nucleotides upstream from the alpha gene and 130 nucleotides upstream of the beta gene. This contains a seven-nucleotide match with a sequence 180 nucleotides upstream from the gamma gene. The sequences corresponding to the 5' non-translated regions of the RNA show two regions of strong homology: one being within the first 20 nucleotides at the very 5' end of the RNA, and the other being between nucleotides 27 and 52 of the three transcripts. The first AUG codon to precede a long open reading frame is found at nucleotides 89, 86 and 83 downstream from the 5' end of the alpha, beta and gamma RNAs, respectively. An extremely conserved nucleotide sequence with an exact homology of 66 nucleotides between the alpha and beta genes, and sharing 27 nucleotides with the gamma gene, is contained within this long open reading frame in the first exon. Conceptual translation of the long open reading frame shows that the hydrophobic nature of the first 20 amino acids of the three polypeptides has been conserved whereas the exact sequence has not. This suggests that the N termini contain signal sequences required for secretion of the protein into the haemolymph. The three genes have intervening sequences ranging from 65 to 68 nucleotides in length at comparable locations close to the 5' end of the genes.

Amino Acid Sequence↗

PubMed1986

Expression of the prokaryotic gene for chloramphenicol acetyl transferase in Drosophila under the control of larval serum protein 1 gene promoters.

We have linked the protein coding region of the prokaryotic gene for chloramphenicol acetyl transferase (CAT) to the promoter region of the Drosophila genes for larval serum protein 1 (LSP1). These regions consist of 1.65 X 10(3) and 2.25 X 10(3) base long DNA segments upstream from the LSP1 alpha and beta genes, respectively. The hybrid genes have been inserted into a P-element transformation vector and the constructs introduced into cultured Drosophila Kc cells by calcium phosphate-mediated transfection, or into the germ-lines of flies by P-element-mediated transformation. CAT expression occurs in approximately 1% of the cultured cells following transfection and the accumulation of protein is maximal three to four days after transfection; and it is dependent upon the presence of the LSP1 sequences. We have also obtained several lines of transformed flies that carry the LSP1-CAT genes in their germ-line. The onset of synthesis of functional chloramphenicol acetyl transferase in these organisms occurs in the late third larval instar, rising to a maximum at puparium formation. We continue to detect CAT until the first few hours of adulthood. Assays of CAT activity in the homogenates of dissected tissues indicated that the genes are only expressed in the fat body, as are the endogenous LSP1 genes. We have confirmed this tissue-specific localization of CAT in indirect immunofluorescence using an anti-CAT monoclonal antibody. Northern blots indicate that CAT transcripts are found only in the fat body but their abundance is an order of magnitude lower than endogenous LSP1 transcripts. Primer extension experiments show that transcription of the hybrid genes is initiated at the same nucleotide as the endogenous LSP1 genes. Taken together these data indicate that the 1.65 X 10(3) and 2.25 X 10(3) base segments of DNA upstream from the LSP1 alpha and LSP1 beta genes contain cis-acting regulatory elements necessary for correct tissue and temporal specificity of LSP1 gene expression.

Acetyltransferases↗

PubMed1983

Phosphorylation of spore coat proteins during development of Dictyostelium discoideum.

Immunological evidence is presented which confirms that pp95, one of the major phosphoproteins accumulated in development of the cellular slime mould Dictyostelium discoideum, is identical with spore coat protein SP13. The site of phosphorylation is identified as phosphoserine. The second major phosphorylated component, pp74, corresponds to two co-migrating spore coat proteins known collectively as SP74.

Dictyostelium↗