• A Sen

      Articles written in Journal of Biosciences

    • Haemolysis of rabbit erythrocytes by a lectin from the seeds ofCroton tiglium

      Kalyan K Banerjee A Sen

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      The kinetics of haemolysis of rabbit erythrocytes byCroton tiglium lectin was studied as a function of concentration of the lectin and erythrocytes. The length of the prelytic period decreased with increasing lectin concentrations, indicating that the secondary events at the membrane which follow the binding of the lectin to cell surface carbohydrate receptors are accelerated at higher surface concentrations of the lectin. The rate or extent of haemolysis was not affected by the inclusion of ions like K+, Ca2+ and Mg2+ in the medium or by the substitution of ionic medium by a non-ionic medium. The inhibition of haemagglutination and haemolysis of rabbit red cells byCroton tiglium lectin by antilectin rabbit serum was observed. A possible mechanism of haemolysis by the lectin is discussed.

    • Olfaction in the Colorado potato beetle: Ultrastructure of antennal sensilla inLeptinotarsa sp

      A Sen B K Mitchell

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      Sensillae on the antennae of the Colorado potato beetle,Leptinotarsa decemlineata are described using scanning (SEM) and transmission (TEM) electron microscopy and compared with SEM observations of antennal sensilla inL. haldemani andL. texana. In all the three species, 13 distinct sensillar types were identified with a higher density of sensilla in the more polyphagous species,L. decemlineata than in the moderately host specificL. haldemani and the highly host specificL. texana. Cuticular specializations and the predominance of olfactory sensilla are discussed in relation to host specificity in the three species.

    • Electroantennogram responses of the potato tuber moth, Phthorimaea operculella (Lepidoptera; Gelichiidae) to plant volatiles

      P D Das R Raina A R Prasad A Sen

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      Electroantennograms (EAGs) were recorded from males and females of the potato tuber moth, Phthorimaea operculella in response to a broad range of plant volatile compounds belonging to diverse chemical classes. The responses to 27 compounds were evaluated, which indicated significant differences in EAGs between chemicals as well as between sexes. The fatty acid derivatives comprising essentially green leaf volatile components elicited significantly greater responses in females. The response profile of males was, in general, lower than that of females. EAG responses to the oxygenated and hydrocarbon monoterpenes were lower in both males and females. Dose–response studies indicate differences in response between the sexes and concentrations, suggesting the existence of sexual dimorphism. Compounds belonging to the fatty acid derivatives class appear to be important for an oligophagous pest such as the potato tuber moth and the findings are discussed in relation to host plant selection in this species.

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