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Bilaterally Asymmetric Helical Myofibrils in Ascidian Tadpole Larvae
Koichi Matsuo1, Ryota Tamura2, Kohji Hotta3
1Laboratory of Cell and Tissue Biology, Keio University School of Medicine, Tokyo, Japan.
Frontiers in Cell and Developmental Biology
|December 24, 2021
Summary
Ascidian larvae possess left-handed helical muscle cells, demonstrating symmetry breaking within their bilateral locomotor system. This finding suggests bilateral animals can overcome cellular homochirality for supracellular organization.
Area of Science:
- Developmental Biology
- Cellular Morphology
- Biophysics
Background:
- The macroscopic locomotor system in bilateral animals exhibits high symmetry.
- Cellular homochirality (single-handedness of biological molecules) is compatible with bilateral body plans.
- The role of single-handed cells in the development of bilateral locomotion remains unclear.
Purpose of the Study:
- To investigate the cellular and subcellular morphology of the ascidian tadpole larva tail.
- To determine how cellular chirality contributes to the bilateral locomotor system.
- To explore the relationship between cellular-level asymmetry and macroscopic bilateral symmetry in locomotion.
Main Methods:
- Utilized quantitative phase-contrast X-ray tomographic microscopy to analyze tail morphology at cellular and subcellular scales.
- Employed fluorescence microscopy to detect asymmetry in myofibril inclination.
- Investigated Zernike phase-contrast X-ray tomographic microscopy for detailed helical structure analysis.
Main Results:
- Identified a high-density midline structure ventral to the notochord in the ascidian tail.
- Observed bilateral alignment of muscle cell nuclei.
- Detected left-right asymmetry in myofibril inclination and confirmed the presence of left-handed myofibril helices in muscle cells on both sides.
Conclusions:
- Ascidian larvae's locomotor system exhibits symmetry-breaking left-handed helical cells.
- Cellular alignment is bilaterally symmetrical despite underlying helical cellular structures.
- Bilateral animals can override cellular homochirality to establish supracellular bilateral symmetry in locomotion.
Keywords:
Ciona robustabilateral symmetrycellular homochiralityleft-handed helixleft-right asymmetrymuscle cellmyofibrilssynchrotron radiationMore Related Videos
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