Substitution of the alpha-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.
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 alpha-lactalbumin (alphalac) 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 alphalac 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.
Soulier
Solange
S
Laboratoire de génétique biochimique et de cytogénétique, Département de génétique animale, Institut national de la recherche agronomique, 78352 Jouy-en-Josas Cedex, France.
Hudrisier
Marthe
M
Da Silva
José Costa
JC
Maeder
Caroline
C
Viglietta
Céline
C
Besnard
Nathalie
N
Vilotte
Jean-Luc
JL
D000818:Animals; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics*; D056906:Cyclin T; D016213:Cyclins / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D020868:Gene Silencing; D007768:Lactalbumin / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic
C503685:Ccnt1 protein, mouse; D056906:Cyclin T; D016213:Cyclins; D017931:DNA Primers; D007768:Lactalbumin