• Volume 93, Issue 3

      April 1984,   pages  159-264

    • Development of organophosphorus and carbamate-resistance in Indian strains ofAnopheles Stephensi Liston

      S Chitra M K K Pillai

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      Larvae of two Indian strains ofAnopheles stephensi were highly susceptible to chlorpyrifos, temephos, dichlorvos, fenitrothion, fenthion and malathion but not to carbamates, DDT and Γ-HCH. Both strains upon continuous and intense larval selection under laboratory conditions, developed high level of resistance to malathion and moderate levels to fenitrothion, fenthion, and temephos. However, selection with propoxur did not produce resistance in both strains. Larval selection could not induce any tolerance in adults. In general, selection with op-compounds induced cross-tolerance to other op-compounds, organochlorines and carbamates. Malathion-selection caused high cross resistance to fenitrothion while, fenitrothion selection produced high cross-resistance to malathion.

    • Alterations in gene expression during senescence

      M S Kanungo

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      Data on the kinetics, peptide maps, induction and isoenzyme pattern of enzymes of rats show that functional changes in genes lead to aging in eukaryotes. Covalent modifications, such as acetylation and phosphorylation, of chromosomal proteins which are complexed with eukaryotic DNA to form the chromatin, decrease with age. Digestion of the chromatin DNA by the endonucleases, DNase I that cuts DNA at 10 base pair intervals and micrococcal nuclease (MCN) that cuts the linker DNA, were carried out to probe the conformational changes in chromatin. Whereas digestion by DNase I significantly decreases with age, the digestion by MCN does not. Thus the chromatin undergoes increasing compaction in non-dividing cells resulting in alterations in its fine structure. This leads to decreasing gene expression and progressive senescence.

    • Use of electrophoresis and immunoelectrophoresis in taxonomic and pollution studies

      Maria R Menezes S Z Qasim

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      Studies were conducted on the electrophoresis of blood serum and eye lens proteins of 5 fishes and immunoelectrophoresis of the soluble lens proteins of 10 fishes. The effects of a toxic pollutant (mercury) on the electrophoretic patterns of the serum, haemoglobin and eye lens proteins of a euryhaline fishTilapia mossambica (Peters) has also been studied. The use of fish blood morphology as a biological index of water quality has been indicated.

    • Cardiovascular effects of serotonin on the pigeonColumba livia

      D Banerjee Asok Ghosh

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      The effect of serotonin on the blood pressure and the heart rate of the pigeonColumba livia was investigated in anaesthetised condition. The effect of histamine was also investigated to understand the mechanism of action of serotonin. Serotonin and histamine were both depressors. Serotonin produced bradycardia while histamine produced tachycardia. Atropine treatment reversed the serotonin-induced depressor response but only partially blocked the histamine-induced fall in blood pressure. Atropine treatment completely abolished the serotonin-induced bradycardia but partially inhibited the histamine-induced tachycardia. A reflex vagal activity and a direct vasoconstrictor activity were proposed on the action of serotonin.

    • The problem of marine timber destroying organisms along the Indian coasts

      N Balakrishnan Nair

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      The serious problem of destruction of wood in sea and brackish waters of India has been discussed with special reference to the organisms that are involved, their distribution, nature of infestation and vertical distribution, seasons of settlement, duration of larval period, growth rates and dispersal. The different ecological factors that determine the distribution of borers have been described such as temperature, salinity, primary film, rate of water flow, turbidity, pollution, effects of fouling, parasites, predators and associates. Control measures to check their ravages are also indicated.

    • Observations on the social behaviour of free ranging groups of tame Asiatic elephant (Elephas maximus Linn)

      Madhav Gadgil P Vijayakumaran Nair

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      This study is based on 645 hr of observations on the social behaviour of tame elephants maintained at three wildlife sanctuaries of Bandipur, Mudumalai and Anaimalai in South India. These elephants are wild captured adults, and their calves born in captivity. The observations were carried out when the elephants are left free for grazing in their natural habitat, where they often intermingle with wild herds. The adult females always stay together when there are calves present: while the adult males graze by themselves. The calves position themselves between adult females and juveniles closer to their mother. All females rush together when a calf sounds alarm. The adult females stand guard over calves lying down for rest thereby accepting considerable reduction in the amount of time devoted to feeding. The ‘allomothers’ suckle other calves when they have no calf of their own, sometimes as much as the mother herself. The acts of social communication are largely initiated by the calf touching the breast or body of an adult female with its nostril. There is much variation in the extent of communication and suckling from one allomother to another with a mother definitely preferring her own calf.

    • Mother mouse sets the circadian clock of pups

      N Viswanathan M K Chandrashekaran

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      We report here the ontogeny of a circadian clock of the field mouseMus booduga expressing itself 16 days after parturition in the locomotory activity of neonate pups removed from the mother and held in continuous darkness ever since birth. Locomotion is a ‘complex’ activity serving such functions as foraging, exploration, and territoriality. Since these functions are not conventionally associated with neonate and altricial animals, it is of interest that this ability has such an early circadian origin. A backward extrapolation of the pups rhythm and the rhythm of the mother strongly implicate maternal synchronization. The period of the circadian rhythm of the pups shortens with age, from birth up to six months.

    • Thrips-fimgus association with special reference to the sporophagousBactrothrips idolomorphus (Karny). (Tubulifera: Thysanoptera)

      T N Ananthakrishnan K Dhileepan

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      Aspects of feeding and fungal spore preference in terms of the percentage of gut-spore composition, and the relative preference of sporophagous Tubulifera to Coelomycetes, Ascomycetes, Hyphomycetes are highlighted. A positive correlation between the width of the maxillary stylets and the fungal spore size indicates the relationship between the two in the choice of the spore type for feeding. The incidence of reproductive polymorphism among the majority of large spore feeding thrips and their absence in hyaline spore feeders, the role of abiotic factors such as temperature and relative humidity in determining the type of reproduction and their influence on the post-embryonic development inBactrothrips idolomorphus are discussed. Numerical variation in the pre-vitellogenic, vitellogenic and developing oocytes during oviparity, ovoviviparity and viviparity is also discussed.

    • Descriptions of new species of oriental Mymaridae and Aphelinidae (Hymenoptera: Chalcidoidea)

      B R Subba Rao

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      A new genus and species, Kubja longipes from Sabah, Hispaniella tenia sp. nov. from Pakistan; Parallelaptera teleonemiae sp. nov.; Eretmocerus breviclavus sp. nov.; Encarsia longifasciata sp. nov.; Azotus bharathius sp. nov.; Azotusfumipermis sp. nov., all from India and of economic importance, are described.

    • Foreword

      T N Ananthakrishnan

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