• Volume 79, Issue 5

      May 1974,   pages  173-226

    • A karyotype study of some teleosts from portonovo waters

      R Natarajan K Subrahmanyam

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      1. The present report embodies the results of a study on the karyotypes of 16 teleost species belonging to 15 families and 7 orders,viz., Anguilliformes (1 sp.), Cypriniformes (1 sp.), Siluriformes (1 sp.), Synbranchiformes (1 sp.), Scorpaeniformes (2 spp.), Perciformes (9 spp.) and Tetradontiformes (1 sp.).

      2. The diploid chromosome numbers in the 16 species presently studied ranges from 40 to 62.

      3. The size of the chromosomes ranges from 0·83 to 5·30µ.

      4. No heteromorphic pair or pairs of chromosomes are discernible in any of them: further, a study of the karyotypes in both the sexes ofMystus gulio, Etroplus suratensis, E. maculatus, Mugil cephalus andAnabas testudineus failed to reveal the occurrence of heteromorphism, if any, in them.

      5. Based on the available morphological and cytological information, the systematic position and species interrelationships have also been discussed.

    • Holocene sea-levels on the Western Continental Shelf of India

      R R Nair

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      Submerged terraces on the Western Continental Shelf between Bombay and Karwar atd ep thso f −92, −85, −75 and −55 meters are inferred, on the basis of radiocarbon dates, to be of Holocene age (about 10,000 years before present) and thus suggest apparent similarities to Global Holocene sea-level fluctuations. An unequivocal chronology of the sea-level fluctuations is however not possible at present due to the limited data points, the possible tectonic instability of the shelf and the unknown extent of the influence of the downwarping by the Indus cone on the shelves bordering the Arabian Sea.

    • Studies on some jumping spiders of the genusMarpissa from India (family—Salticidae)

      B K Tikader

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    • Cytological effects of Argemone oil on the mitotic cells ofAllium cepa

      S Subramanyam P Venkat Reddy G Prem Veer Reedy Dwarkanath K Murthy

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      The cytological effects of Argemone oil, which is one of the adulterants of edible oils, on the mitotic cells ofAllium cepa, have been investigated in detail following a treatment for one hour at different concentrations and also after recovery for 24, 48 and 72 hours. Large number of cells have been scored and aberrations such as chromosome erosions, breakages, fragmentations, gaps, ana- and telo-phase bridges, stickiness and groupings have been analysed. Among the two types of Argemone oil employed, the screw-pressed oil was more effective in inducing these changes than the solvent-extracted one. The recovery from the effects of treatment caused by the former was extremely slow compared to that of the latter. The implications of these results and the possible mutagenic action of the oil have been discussed. Representative photomicrographs are presented.


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