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Turnover of R1 (type I) and R2 (type II) retrotransposable elements in the ribosomal DNA of Drosophila melanogaster.
Genetics. 1992 May; 131(1):129-42.G

Abstract

R1 and R2 are distantly related non-long terminal repeat retrotransposable elements each of which inserts into a specific site in the 28S rRNA genes of most insects. We have analyzed aspects of R1 and R2 abundance and sequence variation in 27 geographical isolates of Drosophila melanogaster. The fraction of 28S rRNA genes containing these elements varied greatly between strains, 17-67% for R1 elements and 2-28% for R2 elements. The total percentage of the rDNA repeats inserted ranged from 32 to 77%. The fraction of the rDNA repeats that contained both of these elements suggested that R1 and R2 exhibit neither an inhibition of nor preference for insertion into a 28S gene already containing the other type of element. Based on the conservation of restriction sites in the elements of all strains, and sequence analysis of individual elements from three strains, nucleotide divergence is very low for R1 and R2 elements within or between strains (less than 0.6%). This sequence uniformity is the expected result of the forces of concerted evolution (unequal crossovers and gene conversion) which act on the rRNA genes themselves. Evidence for the role of retrotransposition in the turnover of R1 and R2 was obtained by using naturally occurring 5' length polymorphisms of the elements as markers for independent transposition events. The pattern of these different length 5' truncations of R1 and R2 was found to be diverse and unique to most strains analyzed. Because recombination can only, with time, amplify or eliminate those length variants already present, the diversity found in each strain suggests that retrotransposition has played a critical role in maintaining these elements in the rDNA repeats of D. melanogaster.

Authors+Show Affiliations

Department of Biology, University of Rochester, New York 14627.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

1317313

Citation

Jakubczak, J L., et al. "Turnover of R1 (type I) and R2 (type II) Retrotransposable Elements in the Ribosomal DNA of Drosophila Melanogaster." Genetics, vol. 131, no. 1, 1992, pp. 129-42.
Jakubczak JL, Zenni MK, Woodruff RC, et al. Turnover of R1 (type I) and R2 (type II) retrotransposable elements in the ribosomal DNA of Drosophila melanogaster. Genetics. 1992;131(1):129-42.
Jakubczak, J. L., Zenni, M. K., Woodruff, R. C., & Eickbush, T. H. (1992). Turnover of R1 (type I) and R2 (type II) retrotransposable elements in the ribosomal DNA of Drosophila melanogaster. Genetics, 131(1), 129-42.
Jakubczak JL, et al. Turnover of R1 (type I) and R2 (type II) Retrotransposable Elements in the Ribosomal DNA of Drosophila Melanogaster. Genetics. 1992;131(1):129-42. PubMed PMID: 1317313.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Turnover of R1 (type I) and R2 (type II) retrotransposable elements in the ribosomal DNA of Drosophila melanogaster. AU - Jakubczak,J L, AU - Zenni,M K, AU - Woodruff,R C, AU - Eickbush,T H, PY - 1992/5/1/pubmed PY - 1992/5/1/medline PY - 1992/5/1/entrez SP - 129 EP - 42 JF - Genetics JO - Genetics VL - 131 IS - 1 N2 - R1 and R2 are distantly related non-long terminal repeat retrotransposable elements each of which inserts into a specific site in the 28S rRNA genes of most insects. We have analyzed aspects of R1 and R2 abundance and sequence variation in 27 geographical isolates of Drosophila melanogaster. The fraction of 28S rRNA genes containing these elements varied greatly between strains, 17-67% for R1 elements and 2-28% for R2 elements. The total percentage of the rDNA repeats inserted ranged from 32 to 77%. The fraction of the rDNA repeats that contained both of these elements suggested that R1 and R2 exhibit neither an inhibition of nor preference for insertion into a 28S gene already containing the other type of element. Based on the conservation of restriction sites in the elements of all strains, and sequence analysis of individual elements from three strains, nucleotide divergence is very low for R1 and R2 elements within or between strains (less than 0.6%). This sequence uniformity is the expected result of the forces of concerted evolution (unequal crossovers and gene conversion) which act on the rRNA genes themselves. Evidence for the role of retrotransposition in the turnover of R1 and R2 was obtained by using naturally occurring 5' length polymorphisms of the elements as markers for independent transposition events. The pattern of these different length 5' truncations of R1 and R2 was found to be diverse and unique to most strains analyzed. Because recombination can only, with time, amplify or eliminate those length variants already present, the diversity found in each strain suggests that retrotransposition has played a critical role in maintaining these elements in the rDNA repeats of D. melanogaster. SN - 0016-6731 UR - https://www.unboundmedicine.com/medline/citation/1317313/Turnover_of_R1__type_I__and_R2__type_II__retrotransposable_elements_in_the_ribosomal_DNA_of_Drosophila_melanogaster_ L2 - http://www.genetics.org/cgi/pmidlookup?view=long&pmid=1317313 DB - PRIME DP - Unbound Medicine ER -