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Titolo:
MOLECULAR EVOLUTION OF THE METALLOTHIONEIN GENE MTN IN THE MELANOGASTER SPECIES GROUP - RESULTS FROM DROSOPHILA-ANANASSAE
Autore:
STEPHAN W; RODRIGUEZ VS; ZHOU BJ; PARSCH J;
Indirizzi:
UNIV MARYLAND,DEPT ZOOL COLLEGE PK MD 20742 UNIV MARYLAND,GRAD PROGRAM MOLEC & CELL BIOL COLLEGE PK MD 20742
Titolo Testata:
Genetics
fascicolo: 1, volume: 138, anno: 1994,
pagine: 135 - 143
SICI:
0016-6731(1994)138:1<135:MEOTMG>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
CENTROMERIC REGION; X-CHROMOSOME; POPULATIONS; SEQUENCES; AMPLIFICATION; LOCUS; POLYMORPHISM; SELECTION; PROTEINS; SIGNALS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
W. Stephan et al., "MOLECULAR EVOLUTION OF THE METALLOTHIONEIN GENE MTN IN THE MELANOGASTER SPECIES GROUP - RESULTS FROM DROSOPHILA-ANANASSAE", Genetics, 138(1), 1994, pp. 135-143

Abstract

Three distinctly different alleles of the metallothionein gene Mtn have been identified in natural Drosophila melanogaster populations: Mtn(.3), Mtn(1), and Dp(Mtn(1)), where the latter designates a tandem duplication of Mtn(1). In Drosophila simulans, only Mtn(.3)-type alleles have been found. It has been suggested that Mtn(.3) is the ancestral allele and demonstrated that a presumed two-step transition from Mtn(.3) to Mtn(1) to Dp(Mtn(1)) is accompanied by an approximate 5-fold increase in RNA levels. We analyzed the evolutionary genetics of the Mtn locus of Drosophila ananassae, a distant relative of D. melanogaster and D. simulans within the melanogaster species group. The Mtn gene of D. ananassae is most similar to Mtn(.3): (i) it is identical with Mtn(.3) at the amino acid level, but differs from Mtn(1) in its terminal codon; (ii) its 3' UTR contains a characteristic extra DNA segment of about 50 bp which is present in Mtn(.3), but lacking in Mtn(1); (iii) duplications of Mtn were not found in a worldwide sample of 110 wild D. ananassae chromosomes. However, the intron of the Mtn gene in D. ananassae is only 69 bp long, whereas the length of the Mtn(.3) and Mtn(1) introns is 265 bp; and it lacks a polypyrimidine stretch upstream of the 3' splice site in contrast to the much greater pyrimidine-richness found in the Mtn(.3) and Mtn(1) introns. A short intron (67 bp) was also identified in a D. pseudoobscura Mtn allele, suggesting that the short intron is the ancestral form and that the transition from the short to the long intron occurred within the melanogaster species group. We discuss the significance of this observation with regard to the recently proposed classification of D. melanogaster introns into two groups: short introns (<90 bp) which tend to lack polypyrimidine stretches,and longer ones which have strong 3' splice signals similar to mammalian introns. A database search revealed that this length dimorphism isan evolutionarily conserved feature of Drosophila introns; transitions from one size class to the other appear to be rare between closely related species (e.g., within the melanogaster subgroup).

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Documento generato il 02/12/20 alle ore 17:55:04