Guest Lecture on “Unravelling the reproductive biology of Indian garden lizard (Calotes versicolor)”

Held on27^thSeptember 2024, from10:30AM to 12:00PM

Introduction: The Biochemistry Department organized a guest lecture on the topic “Unravelling the reproductive biology of Indian garden lizard (Calotes versicolor)” featuring Prof. (retd) Dr. Gopal Marathe K, Department of Studies in Biochemistry and Molecular Biology, Manasagangothri, Mysore, as the distinguished speaker. The lecture aimed to shed light on the reproductive biology of Calotes versicolor, highlighting an interesting adaptation for sperm storage in the females of its species. The topic of lecture was a research project carried out in collaboration with St.Philomena’s College, Department of Zoology, with noteworthy contributions from the former principal of St.Philomena’s College, Dr. Ruth Shantha Kumari.

Key Points Covered:

1. Sperm storage in living organisms: Dr. Gopal initiated the lecture by briefly defining sperm storage as the adaptation in female species to store sperms for variable durations to account for asynchronous reproductive phases between the males and females. The speaker gave examples of organisms other than Indian garden lizard, such as ants, fruit fly, earthworm, honey bee, quail, frog, tortoise, bat, that exhibit female sperm storage.
2. Indian garden lizard (Calotes versicolor):Dr. Gopal spoke about the characteristic features in Calotes versicolor for distinguishing the sexes.The males get a bright red throat in the breeding season (are more brightly colored),and have more prominent scalation than females.
3. Phases of reproductive cycle:The speaker explained the 3 main phases (regressive, regenerative, reproductive) of the reproductive cycle in both male and female Indian garden lizard with images showing the changes in their respective reproductive organs during each phase, and graphs of the progress of the phases through specific months (April to September) of the year. Dr. Gopal drew attention to the asynchronous nature of the cycle, wherein the females have a prolonged reproductive phase that continues for a short duration after September. He highlighted the same as the reason for the adaptation to store sperms inside the female body.
4. Siteof sperm storage:Dr. Gopal explained about utero-vaginal junction (UVJ) where the sperm is stored inside the females. It is a highly folded region present between the vagina and the uterus in the female reproductive organ.Stained cross-section images of the UVJ were shared which illustrated the presence of sperms inside. The speaker also showed electron micrograph of UVJ with emphasis on the sperm and its 9+2 microtubule arrangement.

• Isolation & characterization of contents of UVJ:The speaker elaborated the procedure employed for the isolation and characterization of the contents of UVJ, particularly proteins, beginning with flushing of UVJ with 0.9% saline, followed by centrifugation, and  step-wise application of analytical techniques like SDS-PAGE. Dr. Gopal mentioned that the present step of the research was aligned with the reproductive cycle in the females and was repeated every month accordingly.
• Abundant protein: A protein with a molecular weight of 55KDa appeared prominently in the analytical results and this was further confirmed by 2D electrophoresis. Dr. Gopal went on to explain the techniques used to purify this abundant protein, i.e., affinity chromatography and ion-exchange chromatography using positively charged ion-exchange resin DEAEC (diethylaminoethyl cellulose).The speaker pointed out that the purified protein was identified as a unique protein (generating no matches in the BLAST analysis),previously unknown.
• Role of the protein:Dr. Gopal elaborated on the experiments performed to understand the role of the abundant protein. The protein was seen to inhibit sperm motility inside the UVJ inCalotes versicolor. It was also seen to inhibit sperm motility in humans, mouse, and rats.The speaker underscored the protein’s ability to deter sperm motility as the reason for the enhanced viability of the sperms inside the female’s body.
• Implications and further research:The lecture concluded with Dr. Gopal explaining about the implications of the research, with emphasis on the abundant protein and its application in veterinary science, particularly in artificial insemination of bovines and in poultry farming, to increase the viability of sperms kept in storage. He reiterated the gaps in the present research and the need for further research to understand whether there are any other important proteins, whether the abundant protein isolated from present study can be used to increase viability of human sperms in storage (which will greatly improve the success ratio of IVF procedures), and emphasised that further research is imperative to examine the effects of the abundant protein on the viability of cancer cells.Dr. Gopal ended the lecture by highlighting the importance of basic research and the need for applied research that stems from the basic research.

Conclusion: The guest lecture by Dr. Gopal Marathe K was informative and interesting. The lecture provided insights into the unique reproductive biology of Calotes versicolor. The topic was covered in sufficient detail and the research work was presented with supporting images, graphs, flowcharts, and videos, which helped in developing a thorough understanding of the materials and methods, and results.It also helped students understand the pipeline of research work carried out in the laboratory and connect theoretical knowledge of analytical techniques learnt in classroom with their practical applications in research.The event was successful in facilitating meaningful discussions and underscored the importance of interdisciplinary collaboration, basic research, and applied research to comprehend the challenges facing the scientific community and society at large and arrive at sustainable solutions for the same.