Unique dominant rat spotting gene known as australian downunder – may represent a new major spotting gene of rattus norvegicus.
For most of the history of the domesticated form of Rattus norvegicus, the hooded mutation has been the most commonly known spotting gene. Several alleles of the hooded series have been documented over the span of the past century. The common traits for most of the variant forms tend to display pigment along the face, head, shoulders, and then some variations of pigmentation along the dorsal side. In the fall of 1999, a very unique rat mutation was discovered in Australia amongst hairless breeding stock. The mutation is known as ’downunder’, although it is not yet scientifically described in the literature. Breeding stock was imported into the USA in December, 2002. Unlike the typical hooded alleles, the downunder mutation displays very obvious and prominent ventral spotting. Sometimes, the entire ventral surface is fully pigmented, and the individual rat can still display the typical hooded patterns on the dorsal surface. Inheritance is definitely dominant. But, it is not yet known whether the downunder gene is a lethal dominant, or whether the downunder gene can be expressed in the homozygous state in viable, fertile individuals. Some early eye anomalies did surface in the original hairless downunder stock. The main defects include missing or reduced eyes. In the USA, one hairless anophthalmic female has been produced. Early speculation in Australia leaned towards classifying the downunder gene as a hooded allele. Recent speculation has leaned towards viewing the downunder gene as separate and distinct from the hooded series. The preliminary work to date still leaves many important questions unanswered.
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Document Type: Research Article
Publication date: August 1, 2004