Báo cáo khoa học: Temporal expression of heat shock genes during cold stress and recovery from chill

Temporal expression of heat shock genes during cold

stress and recovery from chill coma in adult

Drosophila melanogaster

Herve´ Colinet1,2, Siu Fai Lee2 and Ary Hoffmann2

1 Unite´ d’E´ cologie et de Bioge´ographie, Biodiversity Research Centre, Universite´ catholique de Louvain, Louvain-la-Neuve, Belgium

2 Department of Genetics, Centre for Environmental Stress and Adaptation Research, Bio21 Institute, University of Melbourne, Parkville,

Australia

Introduction

Temperature plays a crucial role in determining the

distribution and abundance of animals. In insects and

other ectotherms, temperature simultaneously affects

physiological processes, biophysical structures, and

metabolic activities, as well as developmental rates and

growth [1]. Many insect species are seasonally exposed

to suboptimal or supraoptimal temperatures, and this

has led to the evolution of protective biochemical and

physiological mechanisms. For example, heat shock

proteins (Hsps) are considered to play crucial roles in

environmental stress tolerance and in thermal adapta￾tion [2–5]. Hsp genes constitute a subset of a larger

group of genes coding for molecular chaperones. Their

functions include transport, folding, unfolding, assem￾bly ⁄ disassembly, and degradation of misfolded or

aggregated proteins [2,5,6].

Many Hsps are upregulated in response to a diverse

array of stresses [2]. In arthropods, they are induced

by environmental stressors such as heat, heavy metals,

ethanol, and desiccation [3,7,8]. The possibility that

cold stress could elicit heat stress responses has not

been investigated in many biological systems [9]. The

molecular basis of adaptation to nonfreezing low

temperatures has not received as much attention as the

Keywords

cold stress; Drosophila melanogaster; gene

expression; Hsp; recovery

Correspondence

H. Colinet, Bio21 Institute, University of

Melbourne, 30 Flemington Road, Parkville,

Victoria 3010, Australia

Fax: +61 3 8344 2279

Tel: +61 3 8344 2520

E-mail: [email protected]

(Received 9 September 2009, revised 28

October 2009, accepted 30 October 2009)

doi:10.1111/j.1742-4658.2009.07470.x

A common physiological response of organisms to environmental stresses

is the increase in expression of heat shock proteins (Hsps). In insects, this

process has been widely examined for heat stress, but the response to cold

stress has been far less studied. In the present study, we focused on 11 Dro￾sophila melanogaster Hsp genes during the stress exposure and recovery

phases. The temporal gene expression of adults was analyzed during 9 h of

cold stress at 0 C and during 8 h of recovery at 25 C. Increased expres￾sion of some, but not all, Hsp genes was elicited in response to cold stress.

The transcriptional activity of Hsp genes was not modulated during the

cold stress, and peaks of expression occurred during the recovery phase.

On the basis of their response, we consider that Hsp60, Hsp67Ba and

Hsc70-1 are not cold-inducible, whereas Hsp22, Hsp23, Hsp26, Hsp27,

Hsp40, Hsp68, Hsp70Aa and Hsp83 are induced by cold. This study sug￾gests the importance of the recovery phase for repairing chilling injuries,

and highlights the need to further investigate the contributions of specific

Hsp genes to thermal stress responses. Parallels are drawn between the

stress response networks resulting from heat and cold stress.

Abbreviations

Cp, crossing point; Ct, cycle threshold; HSF, heat shock factor; Hsp, heat shock protein; qRT-PCR, quantitative RT-PCR; RA, recovery with

agar; RF, recovery with food; RNAi, RNA interference; sHsp, small heat shock protein.

174 FEBS Journal 277 (2010) 174–185 ª 2009 The Authors Journal compilation ª 2009 FEBS