What is the molecular mechanism of neuronal aging? How does the environment affect neuronal aging?
We unconsciously accept that we all age. Our brains and neurons age. That is so true that we believe that neuronal aging is an inevitable, natural, and passive process. Is it true? What if neuronal aging is genetically programmed? What if our diet can modulate neuronal aging? We are addressing the molecular mechanism of how neuronal functions change over time.
Youtube: Ken's public talk in Japanese about lifespan and neuronal aging
Studying neuronal aging is challenging because both aging and behavior have inherent variations and because aging spans a long time. To overcome these challenges, we use a nematode, C. elegans, as a model. We favor unbiased approaches and carry out genetic screens of C. elegans and bacteria, which serve as food for C. elegans.
C. elegans is a free-living soil nematode which is 1 mm long. C. elegans is ideal for studying neuronal aging for several reasons:
1. Short lifespan
In the laboratory condition, C. elegans lives for 2 to 3 weeks. Also, it manifests behavioral changes within a week after egg laying.
2. Population analysis
Since C. elegans is tiny, we can readily cultivate many worms on a small plate. In addition, their large brood size (~300 progeny) helps to prepare many individuals.
3. Genetic tractability and homogeneity
C. elegans is usually a hermaphrodite, which can self-fertilize and reproduce itself. Thus, we can readily generate a genetically homogenous population.
To know more about C. elegans, watch the talk Ken gave to the general audience at Nagoya University (Video).
C. elegans eats bacteria as food. We use different bacteria to address the dietary effect on neuronal aging.
1. E. coli
E. coli, OP50 strain, is the standard diet in the laboratory condition
2. Lactic acid bacteria
Lactic acid bacteria are long known as probiotics. We use lactic acid bacteria as an alternative food source for C. elegans.
We quantify several behaviors of C. elegans as a proxy of neuronal functions. Their behaviors change during only five days of adulthood (eight days after birth).
Worms are innately attracted to the smells of bacteria which serve as their foods.
Worms associate cultivation temperature and food availability and show attraction to the temperature they were cultivated with foods.