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Microphthalmia: a morphogenetic lethal mutation of the campbelli hamster (Phodopus campbelli)
1Department of Laboratory Animal Science, College of Agriculture, Osaka Prefecture University, Japan.
Abstract:
Microphthalmia is a new mutation of the campbelli hamster (Phodopus campbelli) that is controlled by an incomplete dominant autosomal gene Mi. The dorsal coat of the heterozygote had dark markings on a white background. The dark markings appear on the head, back, and rump. Their color is very similar to that of the wild type, but slightly lighter. The pupil and iris of the heterozygote are black with reddish tinge. The homozygote has pure white fur all over the body and shows a smaller body size than the wild type and heterozygote. Moreover, the homozygote is characterized by small eyes with unopened eyelids and loss of the incisors. The pupil and iris are colorless and transparent or show a faint reddish tinge when the eyelid is artificially opened. In addition to these abnormalities, individual bones of the homozygote show dwarfism. The parietal and frontal region of the skull are thin and their symphysis is incomplete. The distal regions of the vertebral ribs show swelling. The homozygote is basically lethal within 3 weeks of age. A very few survivors are sterile.
Insights
A new microphthalmia mutation in Campbell
Area of Science:
- Genetics
- Developmental Biology
- Animal Models
Background:
- Microphthalmia is a congenital eye disorder.
- Campbell's hamster (Phodopus campbelli) is a model organism for genetic studies.
Purpose of the Study:
- To characterize a novel microphthalmia mutation in Campbell's hamster.
- To investigate the genetic control and phenotypic effects of this mutation.
Main Methods:
- Genetic cross breeding and phenotypic analysis.
- Detailed morphological examination of affected hamsters.
Main Results:
- A new mutation, microphthalmia (Mi), was identified in Campbell's hamster.
- Heterozygotes exhibit dark dorsal markings and reddish-tinged pupils.
- Homozygotes display severe microphthalmia, dwarfism, skeletal abnormalities, and are largely lethal within 3 weeks.
Conclusions:
- The microphthalmia mutation (Mi) is an incompletely dominant autosomal gene.
- Homozygous microphthalmia results in severe developmental defects and reduced viability in Campbell's hamsters.