Laboratory of Insect Diapause

Diapause is a central element of insect life-cycle. Diapause allows insects to overcome harsh seasons and exploit fluctuating resources. Our aim is to contribute to basic understanding of the molecular, biochemical and physiological mechanisms of diapause and associated expression of high tolerance to abiotic environmental stressors. We focus on two major topics: (1) the role of biological circadian clocks in the perception and transduction of photoperiodic information into the overt manifestation of diapause (cessation of development, cell cycle arrest, accumulation of energy reserves, low metabolic rate, altered gene expression, metabolic switch); (2) the principles of seasonally acquired high cold tolerance (changes in metabolomic profiles, accumulation of cryoprotective compounds, restructuring of membrane composition, adjustments of membrane function, expression of heat shock proteins). Our results may serve practical purposes: development of new techniques for cryopreservation of biological material; forecasting the seasonal activities and estimation of overwintering survival in populations of pest species.

Current research projects

Clock genes and diapause

We study putative functional participation of known clock genes period, timeless, cryptochrome, and others in the perception of changing day length and seasonal induction of diapause. We clone clock genes in the species with clear manifestation of diapause and assess their expression patterns using RT-qPCR and other techniques. We disrupt gene expression using RNAi and localize clock neurons using immunocytochemistry. We exploit mutant and transgenic insect lines with disturbed diapause response and observe their photoperiodic and circadian phenotypes.

Mechanisms of insect cold tolerance and long term cryopreservation

We analyze physiological nature of high cold tolerance in diapausing insects. Knowledge on mechanisms of cold tolerance can serve as a basis for development of cryopreservation techniques for insects or other biological material. We exploit laboratory-acclimation protocols to trigger/stimulate high cold tolerance. We focus on changes in membrane phospholipid composition, which affect the membrane fluidity and phase behaviour and, consequently, allow to maintain membrane functions or protect its integrity at low temperatures. In addition, we study changes of gene expression, which result in metabolic switching and synthesis of protective substances such as polyols or heat shock proteins.

Physiology of insect pests' overwintering

We follow the course and the success of overwintering in selected insect pest species in the field. We assess the seasonal timings of diapause induction, initiation, termination and the onset of spring activity. We assess a whole set of physiological parameters, which correlate and/or are causally involved in cold tolerance. We use various techniques (supercooling point, vapour pressure, and Clifton nanoliter osmometers, differential scanning calorimetry, respirometry, analysis of metabolites using GC-MS, LC-ESI-MS). Model species: Ips typographus, Cydia pomonella, Ostrinia nubilalis.

CONTACT

Biology Centre CAS
Institute of Entomology
Branišovská 1160/31
370 05 České Budějovice

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