Analysis of alpha 1,3-galactosyltransferase knockout mice.
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Animals↗
Biomedical subjects
R Tearle
Publications and source records attributed to R Tearle.
The dominant Drop eye mutations of Drosophila melanogaster define two loci implicated in normal eye development.
The three existing dominant gain-of-function Drop alleles, Dr1, DrMio and DrWe, previously assumed to define a single locus, severely disrupt eye development. Genetic analysis of ethylmethanesulphonate (EMS) and irradiation-induced revertants revealed that the Drop mutations define two loci: the Drop locus, which is defined by the Dr1 and DrMio mutants, and a separate locus defined by the DrWe mutation, which has been renamed Wedge. The majority of the Dr1 and DrMio revertants are embryonic lethal in trans, mutant embryos exhibiting trachea that fail to join the Filzkörper, thus revealing a role for the Drop gene in embryogenesis. Clonal analysis of lethal revertant alleles suggests a role for both genes in eye development. In the Drop homozygous mutant clones, the outer photoreceptor cells R1-R6 develop aberrantly. Wedge, however, is not required by the developing photoreceptor cells but its absence does disrupt normal ommatidial alignment. Although the Drop and nearby string loci were shown to be genetically distinct, both Dr1 and DrMio were found to interact in trans with lesions at the string locus, causing loss and derangement of bristles and loss of neuromuscular coordination.
Alleles↗
Site-specific transgene insertion: an approach.
Methods to improve the production of transgenic animals are being developed. Conventional transgenesis, involving microinjection of DNA into fertilized eggs, has a number of limitations. These result from the inability to control both the site of transgene insertion and the number of gene copies inserted. The approach described seeks to overcome these problems and to allow single copy insertion of transgenes into a defined site in animal genomes. The method involves the use of embryonic stem cells, gene targeting and the FLP recombinase system.
Animals↗
Tissue specific effects of ommochrome pathway mutations in Drosophila melanogaster.
The tissue-specific effects of 17 mutations affecting the synthesis of brown eye pigment (xanthommatin) have been investigated by combining them with chocolate and red cells, two mutations causing ectopic pigmentation of the Malpighian tubules and larval fat body (which normally only synthesize pigment precursors). The majority of mutations block the pigmentation of four organs; the normally pigmented eyes and ocelli, and ectopically pigmented tubules and fat body. They represent genes that would appear to be required for the normal operation of the pathway per se and are likely to encode structural proteins. Mutations at 5 loci affect pigmentation of a subset of organs: cd and po affect only the eyes and ocelli; kar affects the eyes, ocelli and fat body; car causes excretion of pigment from tubules; and z affects pigmentation of the eyes alone. Of these loci, only z has been shown to encode a regulatory protein and the role of the remaining four gene products is not clear. Two mutations affecting the red eye pigments (drosopterins), bw and mal, do not substantially perturb brown pigment synthesis in any of the four organs.
Amino Acids↗