• G K Manna

      Articles written in Proceedings – Animal Sciences

    • Effect of x-rays on the somatic chromosomes of the exotic fish,Tilapia mossambica

      G K Manna R C Som

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      Male and femaleT. mossambica were x-rayed with 100 r and the meta-phase chromosome aberrations in their gill epithelia were studied at 13 different intervals against suitable control. The chromosomes of males appeared more radiosensitive than those of females. Among the diploid complement of 44 chromosomes, the individual type aberrations were non-random in both sexes. The longest pair of chromosomes, taken as the marker pair, was found very highly radio-sensitive, while the remaining 21 pairs as non-markers were somewhat resistant to x-radiation when the observed and the expected numbers were subjected to statistical analysis. The break in the marker chromosome was also non-randomly distributed as the distal half had a significantly large number of breaks.

    • Effects of different doses of x-rays on meiotic chromosomes of malePhysopelta schlanbuschi (Largidae: Heteroptera)

      G K Manna S K Dey

      More Details Abstract Fulltext PDF

      Male largid bugs,Physopelta schlanbuschi, having 2n=17 chromosomes (12 autosomes +2m+X1X2Y), were irradiated with x-ray doees of 300 r, 400 r and 500 r which yielded various types of chromosome aberrations in different stages of meiosis of which the common forms were breaks, fragment of unknown origin, constriction, gap etc. Among the 3 sex chromosomes, the two conspicuously large markers, X1 and Y, sometimes formed chiasmalike configuration in prophase I and metaphase I, while a number of anaphase I plates had a chromatid bridge, very likely formed by the X1 and the Y. The qualitative and quantitative assessments of chromosome aberrations in spermatogonial metaphase, prophase I, metaphase I, anaphase I and metaphase II were made at 13 intervals for the doses of 300 r and 400 r and 14 intervals for 500 r between 5 min and 1 week or more. The data showed over-all dose-dependent aberration effects and the sex chromosomes appeared relatively more vulnerable than the autosomes to different doses of x-rays. The testes of untreated males taken as controls had practically no aberration.

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