Hsp70 expression in Chironomus ramosus exposed to gamma radiation

Abstract

Purpose: A tropical species of midge, Chironomus ramosus has been recently reported to be one of the radio-tolerant groups of organisms. The present study was undertaken to examine the protein profile and expression of Heat shock protein-70 (Hsp70) in gamma radiation stress, which has also been reported as a common biomarker for different type of stressors.

Materials and methods: Metabolic labelling of salivary gland (SG) proteins with [³⁵S]-methionine showed over-expression of a 70 kDa protein band up to 4 hours (h) of observation in the post exposure recovery period. For confirmation of the expression of Hsp70 in SG cells after gamma radiation exposure, semi-quantitative real-time-polymerase chain reaction (RT-PCR), Western blotting and immuno-fluorescence detection of Hsp70 were carried out.

Results: Results showed elevated levels of Hsp70 mRNA and protein in SG cells of larvae immediately after gamma radiation exposure. The levels dropped to basal values by 48 h in the recovery period.

Conclusions: The present study confirmed that radio-tolerant midge, C. ramosus expressed Hsp70 upon gamma radiation exposure and Hsp70 might be one of the gamma radiation-induced stress proteins required during the early stages of radiation stress management in aquatic midge larvae. This is the first report of its kind from the juvenile stage of any aquatic insect group.

Keywords:

• chironomus ramosus
• midge
• gamma radiation
• radiation stress
• Hsp70

Acknowledgements

The authors acknowledge the use of all the facilities and support provided in Molecular Biology Division (MBD) and Nuclear Agriculture and Biotechnology Division (NABTD) of the Bhabha Atomic Research Centre, Mumbai, and Department of Zoology (UGC-CAS and BCUD-UoP grants, BCUD Grant number-BCUD/397/dt.26.10.2006), University of Pune, for supporting the experimental work. Support from Department of Atomic Energy (DAE), India, for fellowship to Kailas Datkhile is duly acknowledged. Authors also acknowledge Mr. Manjur Ali for assistance in confocal microscopy.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.