Journal: Theoretical Biology and Medical Modelling

I found two articles by John Porteous on Mendelian genetics quite informative. The first points out the errors in thinking that have crept into, and pervaded, presentation of Mendelian ideas to the current day (roughly, a confusion between phenotype and genotype). The second builds on that, using the work of Kacser & Burns, to propose a mechanism to explain Mendelian results (and results that do not fit neatly into the Mendelian picture).

I also found them interesting in that he notes that traits are distinguishable properties of phenotypes. This immediately leads (at least in my mind) to the idea of equivalence relations on phenotypes: that traits are discrete or "digital" only to the extent that the equivalence relations we impose on the phenotypes make them so. Likewise, the inputs to each generation of Mendel's pea plants appear to be discrete since genetic material comes only from specifically chosen plants. The result is that there is an intuitive preference that the mechanism in the organism that generates phenotypes in the offspring from corresponding genotypes will also be a discrete (digital) mechanism. Porteous' demonstrates that (in my wording) non-linear response curves in metabolic pathways could feasibly account for the generation of traits, rather than requiring dominant/recessive genes as being "on/off" switches.

We still fail to account for Mendel's observations
John W Porteous
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
Theoretical Biology and Medical Modelling 2004, 1:4 doi:10.1186/1742-4682-1-4
http://www.tbiomed.com/content/1/1/4

A rational treatment of Mendelian genetics
John W Porteous
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
Theoretical Biology and Medical Modelling 2004, 1:6 doi:10.1186/1742-4682-1-6
http://www.tbiomed.com/content/1/1/6

There is also a daring and intriguing article by Slobodan Tepic on the idea of eliminating an HIV infection by removing the lymphocytes in the host that HIV requires to flourish. This could be done with a currently available surgical technique. The question is whether the infection-free stability predicted by the model would indeed result. Perhaps the lack of lymphocytes might cause some other mechanism in HIV to kick in, or an unforeseen side-effect to occur? Can such possibilities be tested in vitro, rather than relying on risky in vivo experiments? More broadly, how can we predict the breadth and depth of potential functional relationships without prior experimental information?

Could a simple surgical intervention eliminate HIV infection?
Slobodan Tepic
School of Veterinary Medicine, University of Zurich, Zurich, Switzerland
Theoretical Biology and Medical Modelling 2004, 1:7 doi:10.1186/1742-4682-1-7
http://www.tbiomed.com/content/1/1/7