Genomic Instability of I Elements of Drosophila melanogaster in Absence of Dysgenic Crosses

PLoS One

Patrizio Dimitri¹  Roberta Moschetti²  Ruggiero Caizzi²  Nikolaj Junakovic³ 

[1] Dipartimento di Genetica e Biologia Molecolare, Charles Darwin, Roma, Italy;Dipartimento di Genetica e Microbiologia, Università di Bari “Aldo Moro”, Bari, Italy;Istituto di Biologia e Patologia Molecolari, CNR, Roma, Italy

关键词: Transposable elements;    Invertebrate genomics;    Drosophila melanogaster;    Genetic networks;    Gonads;    Reverse transcriptase-polymerase chain reaction;    Southern blot;    Fluorescent in situ hybridization;   

DOI  :  10.1371/journal.pone.0013142

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

Retrotranspostion of I factors in the female germline of Drosophila melanogaster is responsible for the so called I-R hybrid dysgenesis, a phenomenon that produces a broad spectrum of genetic abnormalities including reduced fertility, increased frequency of mutations and chromosome loss. Transposition of I factor depends on cellular conditions that are established in the oocytes of the reactive females and transmitted to their daughters. The so-called reactivity is a cellular state that may exhibit variable levels of expression and represents a permissive condition for I transposition at high levels. Defective I elements have been proposed to be the genetic determinants of reactivity and, through their differential expression, to modulate transposition of active copies in somatic and/or germ line cells. Recently, control of transposable element activity in the germ line has been found to depend on pi-RNAs, small repressive RNAs interacting with Piwi-family proteins and derived from larger transposable elements (TE)-derived primary transcripts. In particular, maternally transmitted I-element piRNAs originating from the 42AB region of polytene chromosomes were found to be involved in control of I element mobility. In the present work, we use a combination of cytological and molecular approaches to study the activity of I elements in three sublines of the inducer y; cn bw; sp isogenic strain and in dysgenic and non-dysgenic genetic backgrounds. Overall, the results of FISH and Southern blotting experiments clearly show that I elements are highly unstable in the Montpellier subline in the absence of classical dysgenic conditions. Such instability appears to be correlated to the amount of 5′ and 3′ I element transcripts detected by quantitative and real-time RT-PCR. The results of this study indicate that I elements can be highly active in the absence of a dysgenic crosses. Moreover, in the light of our results caution should be taken to assimilate the genomic annotation data on transposable elements to all y; cn bw sp sublines.

【 授权许可】

CC BY