Identification and expression of a small heat shock protein in two lines of the endoparasitic wasp Venturia canescens

Increased expression of small heat shock proteins (sHSPs) is known to be a key regulatory mechanism in extending tolerance to a variety of environmental stresses. In the present study, a full-length cDNA clone encoding a member of the α-crystallin/sHSP family was isolated and characterized from the endoparasitic wasp Venturia canescens (Hymenoptera: Ichneumonidae). Western blot analysis indicated that the mature protein has a mass of about 35 kDa (Vc_sHSP35). Sequence analysis of RT-PCR products revealed that two transcript forms of the gene are expressed in different developmental stages and tissues of the wasp, with the longer form likely to contain an unspliced intron sequence. Furthermore, gene expression was analysed in ovaries of V. canescens wasps from two genetically different lines after exposure to different temperatures (heat or cold shock and heat or cold acclimation, respectively). Wasps from both lines principally showed the same cold induced change in expression of the shorter transcript form (Vc_sHSP35-2). However, expression levels were higher in wasps from one line compared to the other. These results are discussed in relation to the environmental stress resistance and molecular ecology of both V. canescens lines.