Dear Gillian and Guy,
Brain size is probably a direct result of the trajectory of the ectoderm
contraction wave. Thus a more direct approach to your problem would be to
analyze this wave in embryos of different sexes and genotypes, to look
for factors affecting the trajectory. See:
Brodland, G. W., R. Gordon, M. J. Scott, N. K. Bjorklund, K. B. Luchka,
C. C. Martin, C. Matuga, M. Globus, S. Vethamany-Globus & D. Shu (1993).
Furrowing surface contraction wave coincident with primary neural
induction in amphibian embryos. J. Morph. 219, 131-142.
Gordon, R., N. K. Bjorklund & P. D. Nieuwkoop (1994). Dialogue on
embryonic induction and differentiation waves. Int. Rev. Cytol. 150, 373-420.
Best regards, -Dick Gordon, U.Manitoba[May18,95]
On Wed, 17 May 1995, Guy F. Barbato wrote:
> We are currently analyzing a series of experiments intended to elucidate the
> genetic architecture of brain size in chickens. The data sets are comprised
> of 4 diallel crosses made up of related and unrelated
> populations of chickens (3, 4 and 5 parental stocks with brain and body
> weights measured at hatch through 84 days of age in both sexes).
>> During analysis of the data, using both the Griffing and Eberhart and Gardner
> models (similar to Gene Eisen's work in mice), we also performed the
> 'traditional' Hayman's analysis (similar to Norm Henderson's work, also in
> mice). We have found evidence for significant dominance for brain size using
> both types of analysis.
>> Curiously, we have observed that the expression of dominance differs between
> males and females. females tend to exhibit sig. dominance variation at early
> ages which diminishes over time, while males exhibit increasing dominance at
> later ages.
>> Does anyone have any thoughts regarding possible genetic or evolutionary
> explanations of differential expression of dominance between the sexes??
> please respond to me or to Gillian Leach (grl104 at email.psu.edu)
> //// G. F. Barbato Phone: (814)-865-4481
> < * ) Dept. Poultry Science FAX: (814)-865-5691
> \ \__/// Penn State University Lab: (814)-865-3189
> ( --- ) University Park, PA 16802 Email: gfb1 at psu.edu> \/ \/ **** URL: http://ps235.cas.psu.edu/ ****
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> " Education is what survives when
> what was learnt has been forgotten."
> -------- B.F. Skinner