Maternal Inheritance and my Mitotyping Project
By Loren Bolinger, Tuesday, October 04, 2005

My interest in maternal inheritance has been longstanding. My mitochondrial DNA study project has been contemplated for over fifteen years before I got brave enough to think I might be able to make some kind of positive contribution in knowledge toward the Thoroughbred that I dearly love. It was Charles Bruce Lowe whose writings and difficulties gave me inspiration and confidence to at least make the attempt. An abortive attempt was made in 1997 with Dr. Ann Bowling, but she suddenly passed away at the age of 41 from a cerebral hemorrhage.

I have prepared myself by operating a Thoroughbred breeding farm for 36 years, immersing myself in pedigree theories, conducting breeding experiments on my farm, breeding research, biological research, and a background of extensive historical research. My planned matings using pedigree patterns, inbreeding, balanced-sex inbreeding, techniques learned from successful breeders, and voracious reading of Hewitt, Lowe, etc. has produced very satisfying and successful runners in a regional setting.

Our mtDNA study was started by, financed by, and matured with a horse breeder interested in selective mating, maternal inheritance, and the expression of performance traits. I have tried to NOT bring to the table the baggage of stubborn opinion or "know-it-all" closed mindedness. I hope I have the open mindedness that objective science requires. Academic pursuit of knowledge while important is parallel to the potential benefit of pragmatic application of modern, biological science for the horse breeder's benefit. In this genomic age we are still applying eighteenth century, archaic breeding practices.

Mitochondrial investigation must be more than a tool of identity in order to be incorporated by the interested horse breeder in his breeding program. I am happy and willing to acknowledge the great, groundbreaking contribution made by Hill, Cunningham, Bowling, et al. I have no intent to duplicate their efforts - why would I want to do what has already been done?

Our interest in identifying matrilines is just an initial step because how can legitimate research be done if you cannot identify that which you are studying? How can you trust any conclusions if you don't know from where you started? Obviously, therefore, the research must start with identity. In approximately 20 -25 percent of the samples we have sequenced so far, the mtDNA haplotype is in disagreement with the recorded lineage of the individual. The Jockey Club had no parentage verification prior to 1987 other than an honor system dependent on the integrity of Thoroughbred breeders. Registration relied on written and diagrammatic descriptions of external markings similar to those used by state and federal live stock inspectors with other domesticated animals. From 1987 until 2001, parentage verification was determined through nuclear DNA from a sample of blood in addition to the written and diagrammatic descriptions (except for an unsatisfactory attempt to use nasal swabs for DNA verification in 1994-95). The integrity of lineages is crucial to any rational selective breeding scheme. Mis- identification of Thoroughbred lineages has lent an unwelcome and unpredictable variability to selective mating schemes causing inexplicable and unexpected failures from some matings selected by experienced and expert breeders. Mis-identification of lineages invalidates any thoughtful, objective attempt at breeding selection.

Our ultimate objectives are not the same as previous researchers. We have better equipment [Transgenomics WAVE technology], a state-of-the- art, forensic genetics laboratory, at least 8x better accuracy with our methods compared to previous methods, far cheaper and quicker processing, etc. At this time, we are building our own DNA database. Access to the hair and blood samples retained by The Jockey Club would be a researcher's dream.

In Mendelian inheritance, the nuclear DNA is the scaffolding or structure. There are little differences at the level of DNA between a horse, a human, or a hamster. What goes on is going on beneath. Researching the nuclear genome is so large and complex that it would take millions of dollars and far more elaborate facilities, years, and resources to make any kind of meaningful contribution - Inquiry into nuclear inheritance is far beyond my limited means.

The much smaller mitochondrial genome of "Equus caballus" [ACCESSION X79547] is 16660 bp [base pairs] in size. It is monoclonal [that is it replicates or clones from dam to progeny. The mitochondrial genome does not split, divide, and recombine as in nuclear processes]. It is somewhat simpler to understand and research. PLUS, it has to do with maternal inheritance, which is where my interests have laid for thirty years. Long live the ladies!

Yours truly, Loren