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Cytogenetic studies following high dosage paternal irradiation in the mealy bug, Planococcus citri

II. Cytology of X1 females and the problem of lecanoid sex determination

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Summary

When females of the mealy bug. Planococcus citri, are mated to males previously irradiated with heavy doses of gamma rays (30,000 to 120,000 rep), the progeny is mostly female. These X1 females are gynogenetic, with unbroken chromosomes. Detailed cytology of 17 such gynogenetic females showed triploids, diploids. 3N/2N and 2N/N mosaics. Most of the embryos produced by triploid mothers were aneuploid and these degenerated before gastrulation. Regardless of aneuploidy, male embryos showed the typical lecanoid heterochromatization of the paternal set of chromosomes. Just prior to degeneration, the euchromatic chromosomes in the aneuploid male embryos showed endomitotic splitting while the heterochromatic did not. Among the progeny of 3N ♀ X 2N ♂ matings, only males with 5 euchromatic + 5 heterochromatic chromosomes and females with 10 or 15 euchromatic chromosomes were found. A search for adults with 5 heterochromatic +10 euchromatic chromosomes among the progeny of triploid mothers was unsuccessful. Chromosomal variables such as aneuploidy of the euchromatic set, haploidy and fragmentation are discussed in relation to the problems of heterochromatization of the paternal set and sex determination in this species.

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Authors and Affiliations

  1. Department of Genetics, University of California, Berkeley, California, USA

    H. Sharat Chandra

  2. Department of Botany, Manasa Gangotri University of Mysore, 2, Mysore, India

    H. Sharat Chandra

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  1. H. Sharat Chandra
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Additional information

From of a dissertation submitted to the University of California, in partial satisfaction of the requirements for the degree of Doctor of Philosophy.

This investigation was supported in part by a National Science Foundation Grant (No. G-9772) to Professor Spencer W. Brown.

N. I. H. Predoctoral trainee in Genetics, 1961–1962.

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Chandra, H.S. Cytogenetic studies following high dosage paternal irradiation in the mealy bug, Planococcus citri. Chromosoma 14, 330–346 (1963). https://doi.org/10.1007/BF00326819

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  • DOI: https://doi.org/10.1007/BF00326819

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