Research
C.elegans Ecology
With the onset of the genomic era, a new opportunity to study ecology at the genetic level is just dawning. In the Lee lab we use C. elegans genetics to study how the worm interacts with its environment and other organisms at the gene level. Our ultimate goal is to understand how nematodes use their genes to gain fitness advantages in nature. We are studying C. elegans ecology at several levels:
C. elegans natural environments:
In nature C. elegans can be found in places where their favorite food, bacteria, is found in abundance. You’ll especially find them on the ground in rotting fruit and vegetation. We found Caenorhabditis nematodes here in Korea in rotting peaches, pear and yuzu fruit (Choi et al, 2016). However, we would like to learn more about C elegans natural ecology and life history. What are the conditions that allow Caenorhabditis nematodes to grow and reproduce? Can we replicate those conditions in the laboratory? We have developed a protocol to cultivate C. elegans in soil and rotting fruit in the laboratory (Indong et al, 2024).
C. elegans natural soil and fruit habitat in the labratory
Studying C.elegans in 3-D:
In the lab C. elegans is cultivated on an agar plate with E. coli bacteria, but in nature they live in soil and rotten fruits with diverse bacteria. Thus, the worms’ natural habitat is 3D rather than a flat 2D world as in the lab. We developed a system in our lab to cultivate worms in 3D called NGT-3D to study C. elegans development and behavior in three dimensions (Lee et al, 2016). By using behavioral analysis and video technology we are assessing worm behavior in 3D, and trying to relate these behaviors to reproductive fitness and evolution of the nematodes.
Nematode Growth Tube
Nematode Growth Bottle NGB-3D
Hundreds of C.elegans surrounding a bacterial colony in 3D
C. elegans maternal and oviposition behavior
Maternal behaviors are important innate behaviors performed by mothers that increase the survival of its young. C. elegans mothers don’t actively care for their young, but they can control their egg laying. In adverse environments such as in the toxic bacterial metabolite violacein, mothers make the ultimate sacrifice by holding their eggs in their bodies resulting in internal hatching that leads to their own death but survival of the young, termed matriphagy (Yoon et al, 2020).
In the normal laboratory 2D plate culture of C. elegans, hermaphrodite mother worms lay eggs with no pattern. But in a 3D culture of C. elegans, we find that mothers will spread out the bacteria to form a “nest” of bacteria, and the mother worms actively moves away from the bacteria to lay its eggs, which we term 3D oviposition behavior. We identified low oxygen as a cue that induces oviposition behavior, and a neuropeptide and a receptor that regulate the behavior, and find that this behavior gives a fitness advantage for the survival of the young (Lee et al, 2022).
C.Elegans in space
Our future may be beyond this planet. However, before we travel throughout the galaxy and colonize other planets, we must understand how environments outside our Earth’s atmosphere are affecting our biology. How do changes in gravity affect our bodies and development? We are currently performing experiments to understand how high or low gravity can affect C. elegans muscle, neuronal development, and innate immunity using molecular biology and microscopy, and we have shown that space microgravity causes muscle atrophy in C. elegans, just as it does in humans (Kim et al, 2023).
We are also beginning to assess how low gravity can affect neuron development using an instrument called a clinostat. Our lab has both a 2D clinostat and a 3D clinostat to simulate microgravity conditions. Finally, with an international team of scientists from Europe, USA and East Asia, we have sent C. elegans into space aboard the International Space Station in 2018, 2021 and 2022 to study the effect of space on neuron development, innate immunity and muscle atrophy. For more info on our spaceflight experiments in collaboration with the European Space Agency (ESA), check out the following link: www.mme-spaceworms.com
Here’s a Korean news article of our experiment: https://www.yna.co.kr/view/AKR20190411131200017
DD/VD motor neurons exposed to 100 G hypergravity
Clinstat used to simulate low gravity
PVD neuron dendrites
Our worm samples ready for launch!
Jin and Je-hyun at Kennedy Space Center
Bacteria bearing red fluorescence infects C. elegans intestine in space but not on Earth
C.elegans odor
behaviors
Worms may seem like simple organisms, but they can sense and remember many things such as cultivation temperature, toxic foods, and smells. In conjunction with Dr. Kyoung-hye Yoon’s lab at Yonsei University Wonju Medical College, we study what odors worms can smell, what factors like age can alter their sense of smell, and are identifying the odor receptors that are responsible for sensing the odors.
C. elegans moves towards attractive odor
After pre-exposure to odor, C. elegans remembers odor and is no longer interested in the odor
DD/VD motor neurons exposed to 100 G hypergravity
