Journal of Environmental Biology

Isozymic variations in specific and nonspecific esterase and its

thermostability in silkworm, Bombyx mori L.

Author Details

Bharat Bhusan Patnaik

(Corresponding author)

Silkworm Breeding and Genetics Laboratory, Central Sericultural Research and Training Institute,

Central Silk Board, Berhampore ? 742101, India

e-mail: drbharatbhusan4@gmail.com

Tapati Datta Biswas

Silkworm Physiology Laboratory, Central Sericultural Research and Training Institute, Central Silk

Board, Berhampore ? 742101, India

Sandeepta Kumar Nayak

Silkworm Physiology Laboratory, Central Sericultural Research and Training Institute, Central Silk

Board, Berhampore ? 742101, India

A.K. Saha

Silkworm Physiology Laboratory, Central Sericultural Research and Training Institute, Central Silk

Board, Berhampore ? 742101, India

M.K. Majumdar

Central Sericultural Research and Training Institute, Central Silk Board , Berhampore ?742101, India

Publication Data

Paper received:

16 February 2011

Revised received:

31 October 2011

Accepted:

10 November 2011

Abstract

Esterase isozymic variations were documented in the haemolymph of developed multivoltine and bivoltine silkworm breeds during unfavorable seed crop seasons of May ? September using α- and β- napthylacetate separately to identify specific and nonspecific esterase having thermotolerant potentiality. Variations existed in the isozyme pattern with three bands (Est-2, 3 and 4) in pure Nistari race and other developed multivoltine and bivoltine breeds. Est-2 and Est-3 were non-specific esterases as they were observed when both α- and β-napthylacetate was used as substrates separately. Est- 4 band was observed only with α-napthylacetate as substrate and was therefore confirmed to be specific α-esterase band in the haemolymph of silkworm, Bombyx mori L. Zymograms showed that the non-specific esterase band (Est-3) with R_f of 0.43 and specific α-esterase band (Est-4) with R_f of 0.32 predominately withstood a temperature of 70 ? 2^oC for a duration of 10 min and were confirmed as thermostable esterases in haemolymph of silkworm, Bombyx mori L. This also categorized the presence of thermostable esterases in developed multivoltine and bivoltine breeds of silkworm, even though the qualitative activity was more in the former than the latter. The qualitative presence of thermostable esterases and their activity could be adopted as an indicative biochemical marker in relation to thermotolerance in silkworm.

Key words

Isozyme variations, Esterases, Thermotolerance, Breed development, Bombyx mori

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