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le jeudi 03 juin à 11:00

Sylvain Charlat

Salle de formation du PRABI

par Vincent Daubin - 3 juin 2010

On the genetic architecture of Cytoplasmic Incompatibility : inference from phenotypic data

In the absence of a clear understanding of its genetic basis, Cytoplasmic
Incompatibility (CI) has so far been conceptualized using a simple
toxin-antitoxin model. Under this model, a symbiont’s ³compatibility type²
is determined by the specific interaction between two components : a
modification factor (mod, expressed in sperm) and a rescue factor (resc,
expressed in the eggs). Here we confront this model to a well studied,
complex and puzzling CI study system : the mosquito Culex pipiens. We show
that a more elaborate model is required to account for the observed pattern,
including multiple mod and resc genes, and possibly quantitative variation
in gene products. We develop such a model and fit its parameters to the data
using a parsimony approach. We thereby produce explicit predictions with
regards to the genetic architecture of CI ; namely, we infer that at least
five mod / resc pairs are required to explain the data. These predictions
provide a starting point for future genetic and genomic analyses of CI and
will hopefully contribute to the decryption of its molecular basis.