• Volume 47, Issue 5

      May 1958,   pages  263-314

    • An evaluation of the standards used in the study of the yeast nucleus

      N V Aswathanarayana M K Subramaniam

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      1. In the brewery yeast BY 1, the nucleus is visible in 1–2% of the cells from 6–8-day cultures in barley malt wort and 0·5–1% of the cells from 10–12-day cultures in Galactose Peptone Yeast extract medium.

      2. The nucleus is extra-vacuolar and is delimited from the cytoplasm as well as the vacuole by a definite nuclear membrane.

      3. Under phase contrast, the nuclear matrix shows gradations in optical density.

      4. Using the living nucleus as the standard, the variations in its structure are illustrated from iron haematoxylin and Feulgen stained preparations of hydrolysed cells.

      5. The vacuole shows no stainable inclusions and leuco-basic fuchsin stains only limited regions of the resting nucleus.

    • Studies on the menispermaceæ

      P M Mathew

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      1. Cytological study has been made of the staminate plants of six species belonging to six genera and three tribes of the Menispermaceæ.

      2. The chromosome counts made in them aren=13 and 2n=26 inTinospora cordifolia, 2n=26 inAnamirta cocculus, n=13 inTiliacora racemosa, n=13 and 2n=26 inStephania rotunda, n=12 and 2n=24 inCissampelos pereira andn=24 and 2n=48 inCyclea peltata.

      3. From a discussion of all the available cytological data on the Menispermaceæ it is suggested that the existing basic chromosome numbers in the family are 12 and 13, of which 13 is the most common.

      4. Taxonomic relationships of the family are briefly discussed in the light of cytological findings, and it is suggested that the ancestors of the present-day Menispermaceous genera with basic numbers 12 and 13 might have originated from more than one genus in the Berberidaceæ with 6 and 7 as their basic numbers.

      5. Chromosome size variation in the family is briefly considered and together with data on floral morphology it is suggested thatStephania should be transferred from the tribeCissampelideæ to the tribeCocculeæ.

      6. Unequal pairs of chromosomes were seen in the male plants ofStephania rotunda andCissampelos pereira. Heteropyknosis was found in one of the chromosomes in the male plants ofTinospora cordifolia. These male plants are provisionally suggested to be heterogametic with XY type of sex chromosomes.

    • Contributions to our knowledge of Indian algae - II. Volvocales, unicellular forms

      M T Philipose

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    • Polyploidy and vitamin C inEmblica officinalis gaertn

      E K Janaki Ammal R Sundara Raghavan

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      Emblica officinalis collected from various parts of India was found to have chromosome number 2n=98=14x and is therefore a much higher polyploid than the one reported on by Perry which is a tetraploid 2n=28. Cultivated forms ofEmblica officinalis have variable numbers ranging from 2n=98 to 2n=104 and these have larger fruits. A comparative analysis of Vitamin C content of wild and cultivated varieties is given. Ascorbic acid content is found to be directly proportional to the size of the fruit and fruit size is correlated with the presence of a few extra chromosomes in the already high polyploid.

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