UV laser radiation alters the embryonic protein profile of adrenal-kidney-gonadal complex and gonadal differentiation in the lizard, Calotes Versicolor

Abstract

Purpose: To examine the impact of ultraviolet (UV) laser radiation on the embryos of Calotes versicolor in terms of its effects on the protein profile of the adrenal-kidney-gonadal complex (AKG), sex determination and differentiation, embryonic development and hatching synchrony.

Materials and methods: The eggs of C. versicolor, during thermo-sensitive period (TSP), were exposed to third harmonic laser pulses at 355 nm from a Q-switched Nd:YAG laser for 180 sec. Subsequent to the exposure they were incubated at the male-producing temperature (MPT) of 25.5 ± 0.5°C. The AKG of hatchlings was subjected to protein analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and to histology.

Results: The UV laser radiation altered the expression of the protein banding pattern in the AKG complex of hatchlings and it also affected the gonadal sex differentiation. SDS-PAGE of AKG of one-day-old hatchlings revealed a total of nine protein bands in the control group whereas UV laser irradiated hatchlings expressed a total of seven protein bands only one of which had the same R_f as a control band. The UV laser treated hatchlings have an ovotestes kind of gonad exhibiting a tendency towards femaleness instead of the typical testes.

Conclusions: It is inferred that 355 nm UV laser radiation during TSP induces changes in the expression of proteins as well as their secretions. UV laser radiation had an impact on the gonadal differentiation pathway but no morphological anomalies were noticed.

Keywords::

• UV laser irradiation
• lizard embryos
• SDS-PAGE protein profile
• gonadal sex differentiation

Acknowledgements

The corresponding author (LSI) dedicates this work on the 83rd birthday of Prof. M. I. Savadatti who has been a constant source of inspiration. She also thanks the Indian National Science Academy, New Delhi, for the award of a Visiting Scientist Fellowship to work at the Indian Institute of Science, Bangalore. All experiments were conducted in accordance with the regulations of CPCSEA guidelines and the Institutional Animal Ethical Committee with Registration no. 639/02/a/CPCSEA of Karnatak University, Dharwad, Karnataka, India.

Declaration of interest

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

The work was supported by a research grant [2009/37/8/BRNS/1962] received from the Department of Atomic Energy, Bombay, India, under BRNS Major Research Project. One of the authors (BSK) is grateful to BRNS for the award of JRF/ SRF and RSN thanks the UGC for the award of a project fellowship under MRP [F. No. 41-90/2012 (SR)].