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Biomedical subjects

M T Davisson

Publications and source records attributed to M T Davisson.

135 records · Page 8Linked to original sources
PubMedDate not supplied

Mouse models of ocular diseases.

The Jackson Laboratory, having the world's largest collection of mouse mutant stocks and genetically diverse inbred strains, is an ideal place to discover genetically determined eye variations and disorders. In this paper, we list and describe mouse models for ocular research available from Mouse Eye Mutant Resource at The Jackson Laboratory. While screening mouse strains and stocks at The Jackson Laboratory (TJL) for genetic mouse models of human ocular disorders, we have identified numerous spontaneous or naturally occurring mutants. We characterized these mutants using serial indirect ophthalmoscopy, fundus photography, electroretinography (ERG) and histology, and performed genetic analysis including linkage studies and gene identification. Utilizing ophthalmoscopy, electroretinography, and histology, to date we have discovered 109 new disorders affecting all aspects of the eye including the lid, cornea, iris, lens, and retina, resulting in corneal disorders, glaucoma, cataracts, and retinal degenerations. The number of known serious or disabling eye diseases in humans is large and affects millions of people each year. Yet research on these diseases frequently is limited by the obvious restrictions on studying pathophysiologic processes in the human eye. Likewise, many human ocular diseases are genetic in origin, but appropriate families often are not readily available for genetic studies. Mouse models of inherited ocular disease provide powerful tools for rapid genetic analysis, characterization, and gene identification. Because of the great similarity among mammalian genomes, these findings in mice have direct relevance to the homologous human conditions.

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Juvenile bare: a new hair loss mutation on chromosome 7 of the mouse.

We describe a new juvenile hair loss mutant in the mouse in which the hair follicle follows irregular pathways to the surface and generally becomes dystrophic when the mouse is about 23 days of age. Skin from mutant mice older than 1 month of age is histologically normal, although adult mutant mice show a slightly more sparse coat than normal. Grafts of mutant littermates skin to SCID hosts indicate that the condition is probably a systemic response rather than one of the follicle per se. The hair loss is caused by a recessive mutation, which we have named juvenile bare (jb), located on proximal chromosome 7.

Alopecia↗
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A new allelic series for the underwhite gene on mouse chromosome 15.

A new allelic series at the underwhite gene is described. Three of the alleles in the series--uw, uwd, and Uwdbr--arose as spontaneous mutations on different genetic backgrounds at The Jackson Laboratory. We report here the visible phenotypes and dominance hierarchy of these alleles, all of which are defined by a reduction of pigmentation in both eye and coat color. Electron microscopic analysis of retinal epithelium suggests that the primary defect is in the melanosome. The degree of severity of melanosome anomalies in the retina correlates with the degree of hypopigmentation in the coat. The perturbed gene and its gene product are unknown. We show that the uw locus is genetically distinct from Myo10, a suggested candidate gene for this mutation.

Alleles↗
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Dense incisors (din): a new mouse mutation on chromosome 16 affecting tooth eruption and body size.

Dense incisors (din) is a new autosomal recessive mutation in the mouse that interferes with complete eruption of the incisors. The initial eruption of incisors through the gingiva does not differ in mutants and normal littermates, but subsequent further eruption of incisors is arrested in mutants. Radiographic examinations show that, because the incisors do not erupt, continued dentin formation gradually occludes the pulp chambers of these teeth creating as dense incisor. The arrested eruption of the incisor results in an anterior open bite. The pleiotropic phenotype of din/din mutant mice also includes small body size, reduced ear pinna size, and coat color dilution. The din mutation was mapped to Chr 16 near the pituitary transcription factor gene Pit1, but din is not a mutation in Pit1.

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Mesenchymal dysplasia: a recessive mutation on chromosome 13 of the mouse.

Mesenchymal dysplasia (mes) is a new autosomal recessive mouse mutation that alters normal growth of mesenchyme-derived tissues and provides a new mouse model for studying connective tissue development and defects. Mutants are characterized by preaxial polydactyly of all four feet, a shortened face, wide set eyes, domed head, and a shortened kinky tail. Multiple skeletal defects are seen in alizarin-stained specimens. Histological, areas of mineralization are found in tendons. Mutants also have increased musculature in the shoulders and hips and decreased peritoneal fat. Salivary glands, testes, and kidneys are smaller than in littermates. Mesenchymal dysplasia has been mapped to mouse chromosome (Chr) 13. These mapping crosses also confirmed that the Purkinje cell degeneration (pcd) mutation is on Chr 13.

Abnormalities, Multiple↗
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Genes on chromosome 3 of the mouse.

We have located three loci on Chromosome 3 : carbonic anhydrase-1 (Car-1), carbonic anhydrase-2 (Car-2), and blebs (my). The Robertsonian translocation Rb(1.3) 1Bnr was used as a marker for the centromere of Chromosome 3. The loci map is as follows: centromere-2.5cM-(Car-1, Car-2)-26cM-my.

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Patchy fur (Paf), a semidominant X-linked gene associated with a high level of X-Y nondisjunction in male mice.

Several X-linked mutations that have associated sex chromosomal nondisjunction have been identified in the mouse. We describe a new semidominant X-linked mutation called patchy fur (Paf) that produces an abnormal coat. It maps to the distal end of the murine X chromosome very near the XY pseudoautosomal region. The degree of severity in affected mice is hemizygous males greater than homozygous females greater than heterozygous females. An unusual feature of Paf is that either the mutation itself or an inseparable chromosomal abnormality causes delayed disjunction of the X and Y chromosomes at meiotic metaphase I, which in turn results in approximately 19% XO progeny and slightly less than 1% XXY progeny from Paf/Y males. The effect occurs only in male carriers and thus must extend into the proximal end of the XY pairing region.

Animals↗
PubMedDate not supplied

The mouse mutation ulnaless on chromosome 2.

The dominant skeletal mutation ulnaless (Ul) in the mouse causes extreme reduction of the radius and ulna and deformities of the tibia and fibula. Penetrance appears to be complete, but the homozygote is not known, as heterozygous males do not breed. We report the linkage of the Ul gene on Chromosome 2, 18 cM proximal to pallid (pa), and describe its phenotypic effects.

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