Extra heterochromatin in natural populations of Gomphocerus sibiricus (Orthoptera: Acrididae) |
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Authors: | J. Gosálvez C. López-Fernández |
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Affiliation: | (1) Departamento de Genética C-XV, Facultad de Ciencias, Universidad Autónama, Madrid-34, Spain |
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Abstract: | Two types of extra heterochromatin, in the form of either supernumerary segments or B-chromosomes, have been observed in natural populations of Gomphocerus sibiricus. The presence of a heterochromatic supernumerary segment affecting the M7 pair in a population from the Valle de Arán disturbs the normal separation of this bivalent at anaphase I of meiosis and non-disjunction products, respectively deficient or duplicate for the M7, are present at metaphase II.A stable Bm chromosome has been detected in a second population from Formigal. In a single individual where a Bm is present together with a small unstable Bs supernumerary chromosome both the Bm and the M5 are unstable in the germ line and in the case of the M5 this unstability leads to a state of germ line polysomy. |
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