• Volume 74, Issue 4

      October 1971,   pages  161-215

    • Chemical mutagenesis inSorghum

      K Sreeramulu

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      The effect of NG, DEB and single and recurrent treatments after NMU on sensitivity in M1 and chlorophyll mutation frequency and spectrum in M2 was studied in the variety Co. 18 ofSorghum subglabrascens. Among the three chemical mutagens DEB was the most effective in delaying the emergence of primary leaf, and reducing the percentage of germination, survival and growth of root, coleoptile and seedlings, whereas NG was the least effective. The effect of mutagens increased with increasing dose. Recurrent treatments with NMU showed more drastic effects with respect to the above criteria than single treatments. The frequency of chimeras for chlorophyll deficiency in the M1 was found to be the maximum in the single treatments as compared to recurrent treatments after NMU. An increase in the reduction of pollen and seed fertility with an increase in dose of NMU and NG was observed. But the treatments with NMU showed more drastic effects on fertility than treatments with NG. The frequency of chlorophyll mutations was found to increase with dose in NMU, whereas such relationship was not observed in teratments with NG. The mutation rate was found to be higher in treatment with NMU than with NG. Whilealbina andxantha only were noticed in treatments with NG, a very wide spectrum of chlorophyll mutations was observed in NMU treatments. Recurrent treatments with NMU induced higher frequency and wider spectrum of chlorophyll mutations than single treatments.

    • A preliminary survey of dermatomycoses in Bangalore

      P U Indira M Sirsi N Krishnamurthi

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      Clinical and mycological investigations were made on 225 cases of suspected dermatomycoses. Of these, 102 were microscopically positive. But only 63 were culturally positive, and these are analysed here with regard to clinical patterns and aetiological species, age, sex and occupational incidence and susceptibility to griseofulvinin vitro. As in most other parts of India,Trichophyton rubrum was the dominant species. A high proportion ofEpidermophyton floccosum was an unusual feature seen. Of the clinical types, tinea cruris was the most common. The isolates were sensitive to griseofulvin at low concentrations of 1 to 5µg per ml of agar medium,E. floccosum being the most sensitive.

    • Studies on permeability changes in cotton (Gossypium hirsutum) caused byVerticillium albo-atrum

      H C Dube

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      The present work demonstrates permeability changes inVerticillium-infected cotton tissues. Permeability was determined by measuring the exosmosis rate of electrolytes. The roots and leaves showed more electrolytic leakage as compared to the stem. This leakage while continues in the leaf tissue, a fall was recorded later for the roots. The stem tissues were affected least. The ash analysis of the diseased leaves showed a marked decrease in the potassium and sodium ions as compared to the healthy tissues. Calcium showed increased accumulation in diseased tissues. There was a decrease in total nitrogen content of diseased leaves while the infected root and stem tissues did not show much difference from the healthy tissues. The total carbohydrate content of the diseased leaves was considerably low but the roots showed an increase over the healthy tissues.

    • Studies on cucurbit viruses in Madras state - IV. Some aspects of the relationships of melon mosaic virus strain to its three aphid vectors

      K Nagarajan K Ramakrishnan

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      Melon Mosaic Virus (MMV) was non-persistent in its three aphid vectors. The pre-acquisition fasting threshold, acquisition threshold and the inoculation feeding threshold were 5 minutes, 10 seconds and 60 seconds respectively forMyzus persicae, 15 minutes, 30 seconds and 3 minutes respectively forAphis gossypii, 60 minutes, 60 seconds and 5 minutes respectively forA. nerii. The optimum number of viruliferous aphids per plant for maximum transmission was 30 in all the vectors. Increasing the number of aphids above this optimum decreased the percentage transmission of the virus. In the case ofMyzus persicae, the reduction in the percentage transmission was conspicuous when 240 aphids per plant were used whereas inA. nerii the decrease was noticed even when 100 aphids per plant were used. The percentage transmission by fasted aphids was more than by the non-fasted ones. Persistance of the virus during fasting was for 90, 45 and 30 minutes respectively inM. persicae, A. gossypii andA. nerii while during feeding it was 30, 15 and 10 minutes respectively. The aphid vectors were ranked in the following descending order of transmission efficiency:Myzus persicae, Aphis gossypii andA. nerii. The length of the pre-acquisition fasting period varied inversely as the efficiency. More efficient the vector, shorter was the fasting period. The acquisition threshold and incoulation feeding threshold also varied inversely as the efficiency of the vector. The fall in the efficiency of transmission when the number of aphid vector was increased above the optimum was considered to be due to a salivary inhibitor. Apterous forms of the aphid vectors were more efficient transmitters of the viruses than the alate forms.

      It was concluded that all aphids have a salivary inactivator, the quantity secreted varied from species to species, the efficiency of transmission being inversely correlated with the quantity of inhibitor secreted.

    • The first phyllosoma stage of the Indian deep-sea spiny lobster,Puerulus sewelli Ramadan

      K H Mohamed P Vedavyasa Rao C Suseelan

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      Early development of the Indian deep-sea spiny lobster,Puerulus sewelli Ramadan was traced from the eggs hatched out in the laboratory on board the Research Vessel ‘VARUNA’. The naupliosoma and the first phyllosoma stage of the species are described. The first phyllosoma is characterised by the possession of uniramous antenna with a spine-like process at the outer border of the proximal region and conspicuous exopod on the third pereopod.

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