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vertebrate gene numbers and immune evolution

Donald Forsdyke forsdyke at post.queensu.ca
Wed Aug 22 19:16:22 EST 2001

> Could Immune Evolution Put A Cap On Vertebrate Gene Numbers?
> Recent analysis of the human genome caused surprise with the number of
> genes put at one third of the number expected with some comparison made
> against some invertebrate genomes, with the yeast genome or with plant
> genomes in the lay press.

You may have been surprised. Some of us were not.

it is likely that the gene
> number in various vertebrate species will show an upper limit determined
> by the need to optimize the constraints on immune repertoire
> construction. The greater the number of "self" epitopes expressed in the
> thymic education of T-cells, the greater the number of holes created in
> the repertoire.

Only if you believe that all potentially autoreactive T cells must be
eliminated. Again, some of us do not.

Levels of non-self recognition in individuals must be
> optimal while populations need extensive polymorphism for MHC class I
> and II yet the limit on MHC loci is such that only a dozen of the
> hundreds of available MHC alleles are expressed in any individual (two
> alleles each of six class I and II genes).

Why "and yet?" Some of us have no problem with this.

     So, perhaps you should consider your premises before you get too

Donald Forsdyke,


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