Showing papers by "Allan Bradley published in 1987"

A potential animal model for Lesch–Nyhan syndrome through introduction of HPRT mutations into mice

Abstract: The human Lesch–Nyhan syndrome is a rare neurological and behavioural disorder, affecting only males, which is caused by an inherited deficiency in the level of activity of the purine salvage enzyme hypoxanthine-guanosine phosphoribosyl transferase (HPRT)1–3. How the resulting alterations in purine metabolism lead to the severe symptoms characteristic of Lesch–Nyhan patients is still not understood3,4. No mutations at the Hprt locus leading to loss of activity have been described in laboratory animals. To derive an animal model for the Lesch–Nyhan syndrome, we have used cultured mouse embryonic stem cells5, mutagenized by retroviral insertion and selected for loss of HPRT activity, to construct chimaeric mice6,7. Two clonal lines carrying different mutant Hprt alleles have given rise to germ cells in chimaeras, allowing the derivation of strains of mutant mice having the same biochemical defect as Lesch–Nyhan patients. Male mice carrying the mutant alleles are viable and analysis of their cells shows a total lack of HPRT activity.

Tissue-specific expression of the human type II collagen gene in mice

Abstract: Type II collagen is crucial to the development of form in vertebrates as it is the major protein of cartilage. To study the factors regulating its expression we introduced a cosmid containing the human type II collagen gene, including 4.5 kilobases of 5' and 2.2 kilobases of 3' flanking DNA, into embryonic stem cells in vitro. The transformed cells contribute to all tissues in chimeric mice allowing the expression of the exogenous gene to be studied in vivo. Human type II collagen mRNA is restricted to tissues showing transcription from the endogenous gene and human type II collagen is found in extracellular matrix surrounding chondrocytes in cartilage. The results indicate that the cis-acting requirements for correct temporal and spatial regulation of the gene are contained within the introduced DNA.