Original Article

Heredity (1997) 78, 1–11; doi:10.1038/hdy.1997.1

P-element inserts in transgenic flies: a cautionary tale

Marcel Kaiser1, Matthias Gasser1, Ruedi Ackermann2 and Stephen C Stearns1

  1. 1Zoology Institute, University of Basle, Rheinsprung 9, CH-4051 Basle
  2. 2Biocentre, University of Basle, Klingelbergstrasse 70, CH-4056 Basle, Switzerland

Correspondence: Stephen C Stearns, Zoology Institute, University of Basle, Rheinsprung 9, CH-4051 Basle. E-mail: stearns@wz.unibas.ch

Received 2 January 1996.

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Abstract

The fruitfly, Drosophila melanogaster, can be transfected with P-elements and induced to overexpress a transfected gene whose impact on lifespan can be measured. Here, it is reported that in previous experiments a transfected gene was not expressed. This suggested a new statistical analysis indicating that (1) the size of the insert, the position and the interactions of the insert with the genetic backgrounds into which the P-element are inserted have effects on lifespan similar to those attributed to overexpression; (2) these effects occur without expression of the transfected gene; and (3) effects of interactions with backgrounds and effects of positions are as large as responses to six generations of strong directional artificial selection. Reports of effects of overexpression of transfected genes on lifespan in Drosophila melanogaster may be experimental artefacts. Credible experiments on the phenotypic effects of trans-genesis need proper controls for the effects of insert size and position and should estimate the magnitudes of interactions of treatment with genetic backgrounds.

Keywords:

Drosophila melanogaster, elongation factor, genetic manipulation, lifespan, position effects, size effects

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