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Substitution of the α-lactalbumin transcription unit by a CAT cDNA within a BAC clone silenced the locus in transgenic mice without affecting the physically linked Cyclin T1 gene

  • Soulier Solange1,
  • Hudrisier Marthe1,
  • Da Silva Costa José1,
  • Maeder Caroline2,
  • Viglietta Céline2,
  • Besnard Nathalie1 and
  • Vilotte Jean-Luc1Email author
Genetics Selection Evolution200335:239

Received: 12 December 2001

Accepted: 1 October 2002

Published: 15 March 2003


We recently reported that a goat bacterial artificial chromosome (BAC) clone conferred site-independent expression in transgenic mice of the two loci present within its insert, the ubiquitously expressed Cyclin T1 and the mammary specific β-lactalbumin (αlac) genes. To assess if this vector could target mammary-restricted expression of cDNA, the CAT ORF was introduced by homologous recombination in Escherichia coli in place of the αlac transcription unit. The insert of this modified BAC was injected into mice and three transgenic lines were derived. None of these lines expressed the CAT gene suggesting that the use of long genomic inserts is not sufficient to support the expression of intron-less transgenes. The physically linked goat Cyclin T1 locus was found to be active in all three lines. This observation reinforced the hypothesis that the two loci are localised in two separate chromatin domains.


bacterial artificial chromosomehomologous recombinationintrontransgenic micechromatin domain

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Authors’ Affiliations

Laboratoire de génétique biochimique et de cytogénétique, Département de génétique animale, Institut national de la recherche agronomique, Jouy-en-Josas Cedex, France
Laboratoire de biologie du développement et de biotechnologie, Département de physiologie animale, Institut national de la recherche agronomique, Jouy-en-Josas Cedex, France


© INRA, EDP Sciences 2003