Pharynx mitochondrial [Ca²⁺] dynamics in live C. elegans worms during aging

Area of Science:

• Cellular Biology
• Mitochondrial Physiology
• Aging Research

Background:

• Mitochondrial dysfunction is a hallmark of aging.
• Mitochondrial calcium ([Ca2+]M) plays a crucial role in cellular energy metabolism and function.
• Understanding [Ca2+]M dynamics during aging is vital for insights into age-related decline.

Purpose of the Study:

• To measure mitochondrial calcium ([Ca2+]M) dynamics in the pharynx of live C. elegans during aging.
• To investigate the impact of aging on [Ca2+]M oscillations and their relationship with cellular energy status.
• To compare [Ca2+]M dynamics in wild-type and nuo-6 mutant C. elegans.

Main Methods:

• Expression of a Ca2+ sensor in the mitochondrial matrix of C. elegans pharynx cells.
• Real-time measurement of mitochondrial [Ca2+] ([Ca2+]M) dynamics in live C. elegans during aging.
• Analysis of [Ca2+]M oscillatory kinetics, frequency, height, and width in response to serotonin stimulation.

Main Results:

• Serotonin stimulation induced high-frequency [Ca2+]M oscillations and prolonged increases, indicative of energy depletion.
• The frequency of [Ca2+]M oscillations remained stable throughout the worm's lifespan (2-12 days).
• The height and width of [Ca2+]M peaks progressively decreased with age, indicating reduced Ca2+ uptake/release capacity.
• [Ca2+]M oscillations were present in nuo-6 mutants but showed reduced height and frequency, and increased width compared to controls.
• Mitochondrial Ca2+ fluxes were diminished in nuo-6 mutants and decreased similarly with age in both genotypes.

Conclusions:

• Mitochondrial Ca2+ fluxes are relatively well-preserved in terms of frequency during C. elegans aging.
• A progressive decrease in the magnitude of mitochondrial Ca2+ fluxes occurs during aging.
• Mitochondrial Ca2+ dynamics are impaired in respiratory chain complex I mutants and decline with age.