Bruce Macintosh Cattanach

Research

Mutagenesis Cattanach centered a portion of his work on mutagenesis, the process of mutations causing changes in the genetic material of an organism, where he found numerous mutants of interest useful in research. One example is Bruce’s identification of the hpg genetic variant mouse model. His research group noticed a strain of mice with underdeveloped reproductive organs, which they realized was caused by them lacking a hormone called hypothalamic GnRH (gonadotropin-releasing hormone) because the GnRH gene had a part of it missing. As a result, there were also reduced levels of other key reproductive hormones. Although the evidence of autosomal imprinting has been observed in previous research, Cattanach was the first to recognize its significance and to investigate its mechanism in mice. Cattanach identified the particular regions of chromosomes that are essential for autosomal imprinting.

Dog Breeding and Genetics Bruce also had a passion for dog breeding and genetics. Wondering if there was a way to breed Boxers to have naturally short tails without having to dock them, he attempted to cross breed a Corgi and a Boxer. Cattanach’s experiment showed that transferring a gene between breeds could be easy and can cause physical changes; in this case, it was a dog’s version of the T gene which, when disrupted, results in developing short tails. He also investigated canine genetic diseases. Bruce found that the STRN gene variant is not what actually causes heart disease in Boxers, but is instead a marker that can be used to identify or track it.

X inactivation and X-chromosome controlling element Cattanach's discovery of the “Cattanach's translocation” in a mouse model, involves the relocation of a piece of chromosome 7 into the X chromosome, which led to the observation of mosaic female mice, mice that displays both dark and white fur due to different genetic make up, which were later called "flecked" mice. Upon further investigation with Susumo Ohno, they were able find that the "flecked" mice phenotype was due to X chromosome inactivation, which is a natural phenomenon where all except one X chromosome and its genes are silenced when an organism has more than one X chromosome. The "flecked" mice helped verify Mary Lyon's hypotheses on the natural mosaicism, meaning cells from the same organism have a different genetic make up, in female mammals due to X inactivation. Overall, his research on X chromosomes contributed to the understanding of X chromosome inactivation and mosaicism.