Jetto, Cuckoo et al. (2017) International Worm Meeting "Spontaneous nucleolysis occurs during organismal death in Caenorhabditis elegans."

Jetto, Cuckoo, Raj, Vishnu, Nair, Agrima, Vijayan, Bejoy, Thekkuveettil, Anoopkumar

[International Worm Meeting, 2017]

Necrotic cell death has been extensively studied for its involvement in many human diseases. In C elegance change in pH or temperature induces organismal death and is marked by a characteristic wave of necrotic cell death of worm's digestive track; a phenomenon also marked with a blue fluorescence (called death fluorescence or DF) due to anthranilate release from stored vesicles. One of the critical events in this pathway is the increase in cytoplasmic calcium levels in the digestive track, which is essential for both for the development of DF as well as for the organismal death. But whether the organismal death, being a spontaneous event, follows the necrotic cell death pathway involving calcium-triggered activation of calpain and cathepsin is not clear. Here we report a uniquely different mechanism in organismal death through calcium-regulated calpain proteases, bypassing the cathepsin/ aspartyl protease pathway. Our findings also show that nucleolysis is an immediate intracellular change occurs during organismal death and is a calcium-dependent process. These cellular responses during organismal death are unique, compare to necrotic neurodegeneration in C. elegans and could have significance in the onset of organismal death.

Raj, Vishnu et al. (2017) International Worm Meeting "Degeneration of dopamine neurons affects memory formation in Caenorhabditis elegans."

Mangalath, Aswathy, Raj, Vishnu, Santhosh, Rasitha, Nair, Agrima, Thekkuveettil, Anoopkumar, Vijayan, Bejoy

[International Worm Meeting, 2017]

Degeneration of dopamine neurons often found to develop dementia as a comorbidity. It is not deciphered, however, the involvement of the dopamine connectome in memory formation as well as in dementia. Caenorhabditis elegans is an excellent model system to study the connectome variations because of its elementary and well-mapped nervous system. The four CEP neurons in the head region of the organism use dopamine as their neurotransmitter and play a critical role in the movement. To understand the role of dopamine circuit in learning, we used adaptive learning paradigm of Caenorhabditis elegans to olfactory cues. Significantly low associative learning towards butanone was observed in mutant DAT-1::ICE, which develops dopamine neuron degeneration in their late larval stages. These results were comparable to that of mutants of str-2, a G-protein coupled receptor in AWC neurons, having a significantly low associative learning. A similar pattern of learning defects were observed in UA-44 strain with age-associated dopamine neurodegeneration. However, Cat-2 and Tph-1 mutants, which are defective in dopamine and serotonin synthesis respectively, showed no significant changes in learning pattern. These findings suggest dopamine connectome have a critical role in memory formation.