ABSTRACT
Chloramphenicol acetyl transferase gene under control of hsp promoter (hsp-CAT gene) was introduced and expressed upon heat shock in Drosophila cells at 48 and 72 hr following transfection. Expression of CAT gene was remarkably reduced when DNA methylated at CpG sites was used although presence of methylated plasmid DNA could be demonstrated in cells at 48 and 72 hr. Thus, in Drosophila cells exogenously introduced methylated DNA is expressed differently from unmethylated DNA.
Subject(s)
Animals , Chloramphenicol O-Acetyltransferase/genetics , Cytosine/metabolism , DNA Methylation , Drosophila melanogaster/genetics , Gene Expression Regulation, Enzymologic/physiology , Genes, Insect , Promoter Regions, GeneticABSTRACT
MboI repeat fragment of mosquito Anopheles stephensi has been isolated by molecular cloning. The restriction map and entire nucleotide sequence of the 433bp insert has been determined. Hybridization of this repeat DNA with restriction enzyme digest of mosquito DNA does not show an interspersed pattern but suggests that this repeat may be tandemly repeated at one major site and a few minor sites in the genome of Anopheles stephensi. The hybridization pattern also indicates that this repeat family comprises of many similar but non-identical sequences. An open reading frame encoding 66 amino acids with an initiation and two tandem termination codons has been identified. This putative 66 amino acid polypeptide sequence has significant homology to a small region of RNA tumour viral envelope protein.