Downregulation of dTps1 in Drosophila melanogaster larvae confirms involvement of trehalose in redox regulation following desiccation
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As a survival strategy to environmental water deficits, desiccation-tolerant organisms are commonly known for their ability to recruit stress-protective biomolecules such as trehalose. We have previously reported the pivotal role of trehalose in larval desiccation tolerance in Drosophila melanogaster. Trehalose has emerged as a versatile molecule, serving mainly as energy source in insects and also being a stress protectant. While several recent reports have revealed the unconventional role of trehalose in scavenging reactive oxygen species in yeast and plants, this aspect has not received much attention in animals. We examined the status of desiccation-induced generation of reactive oxygen species in D. melanogaster larvae and the possible involvement of trehalose in ameliorating the harmful consequences thereof. Insect trehalose synthesis is governed by the enzyme trehalose 6-phosphate synthase 1 (TPS1). Using the ubiquitous da-GAL4-driven expression of the dTps1-RNAi transgene, we generated dTps1-downregulated Drosophila larvae possessing depleted levels of dTps1 transcripts. This resulted in the inability of the larvae for trehalose synthesis, thereby allowing us to elucidate the significance of trehalose in the regulation of desiccation-responsive redox homeostasis. Furthermore, the results from molecular genetics studies, biochemical assays, electron spin resonance analyses and a simple, non-invasive method of whole larval live imaging suggested that trehalose in collaboration with superoxide dismutase (SOD) is involved in the maintenance of redox state in D. melanogaster.
KeywordsDrosophila Desiccation stress Trehalose ROS SOD dTps1-RNAi transgene
We thank Dr. Takashi Okuda (NIAS, Japan) for his critical advice and suggestions on insect desiccation tolerance. We are extremely grateful to Prof. Alexander Brehm for the kind gift of dTps1-RNAi and GAL4 fly lines. Thanks are also due to the ESR analysis facility provided by SAIF, IIT Bombay, and to Vrindha Vishwanathan for her technical advice. This work was partially supported by UGC-CAS and DST-PURSE grants to the Department of Zoology, SPPU, and UoP-BCUD grants to BBN. LJT acknowledges the financial support received from the Council of Scientific and Industrial Research-Senior Research Fellowship (CSIR-SRF), New Delhi, India. The authors thank the two anonymous reviewers for their valuable comments on our manuscript.
B. Nath, L. Thorat and S. Chatterjee designed the experiments. L. Thorat, K. Mani and P. Thangaraj performed the experiments. L. Thorat, B. Nath and S. Chatterjee analysed the data. L. Thorat and B. Nath wrote the paper with contributions from S. Chatterjee.
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