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Dosage compensation and sex-chromatin in non-mammals
Published online by Cambridge University Press: 14 April 2009
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1. Inactivation of one X chromosome in somatic cells of female mammals is a form of dosage compensation of sex-linked genes, but the mechanism is entirely different from that operating in Drosophila. The latter is designated as dosage compensation sensu strictu.
2. There is no dosage compensation of barred, sex-linked dilution or slow-feathering in domestic fowls, of almond or faded in pigeons, or of cinnamon in canaries. Among Lepidoptera the same is true of sex-linked melanism in Lymantria monacha and of a locus controlling haemolymph colour in Choritoneura spp. There is no positive evidence that dosage compensation occurs outside Drosophila and mammals.
3. Sex-chromatin in female birds (heterogametic) has been reported by several authors; the genetical evidence is against the possibility that this represents (as in mammals) an inactivated X chromosome. Sex-chromatin in the heterogametic sex also occurs in some (not all) Lepidoptera and Heteroptera; in Heteroptera it usually represents a heteropyknotic Y chromosome.
4. Some complications in Muller's theory of dosage compensation sensu strictu are discussed. Not all ‘compensatory modifiers’ are necessarily sex-linked.
5. The problem of dosage compensation in species with impaternate males is discussed; fused in Habrobracon is not compensated.
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- Copyright © Cambridge University Press 1964
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