What We Do

We develop cutting-edge microscopy and laser spectroscopy to explore the fundamental questions of biology. By bridging the gap between microscopic physical phenomena and macroscopic biological functions, we aim to achieve a unified understanding of life—from isolated proteins to highly complex, organized living systems. 

Photosynthetic pigment-protein complexes carry out multi-step photochemical processes: light absorption, energy transfer, charge separation, and electron transfer. To monitor each step occurring on femtosecond-to-picosecond timescales, we require time-resolved measurements with extraordinary temporal resolution. In addition, to understand how the structural dynamics of proteins and membranes contribute to this series of photochemical processes, single-molecule spectroscopy demanding highly sensitive measurements is necessary. Our goal is to achieve a comprehensive understanding of the mechanisms regulating these sequential processes under dynamic and heterogeneous conditions in physiological environments by overcoming current technical limitations.

Our research focuses on two major challenges:

Tracking energy transfer using fluorescence spectroscopy: While single-molecule observations based on steady-state fluorescence spectroscopy are commonly used, time-resolved spectral measurements remain technically challenging. We are developing microspectroscopy to overcome this barrier and uncover correlations between protein and membrane dynamics and the energy-transfer rate and pathway within individual proteins and protein supercomplexes.

Tracking electron transfer using absorption microscopy: Unlike energy transfer, electron transfer is difficult to observe by fluorescence detection. Electron flow through proteins can be tracked via transient absorption changes of electron-transfer mediators. We are exploring high-sensitivity absorption microscopy to observe electron flows at the single-molecule level. 

Recent breakthroughs have sparked a revolution in biology, suggesting that quantum effects, typically observed only in highly controlled physics laboratories, may also play functional roles in living systems. We are investigating how nature utilizes these mysterious phenomena:

Quantum Energy Transfer (Photosynthesis): Photosynthetic plants and bacteria may use quantum-coherent effects to maintain remarkably high light-harvesting efficiency. We are developing time- and space-resolved microscopy to observe these phenomena at the microscopic level. By quantitatively evaluating the contribution of quantum effects, we aim to clarify how important they are for sustaining efficient photosynthesis.

Quantum Magnetic Compass (Magnetoreception): Migratory birds and other animals can detect the Earth's weak magnetic field. We are exploring how quantum entanglement and electron spin dynamics in specific proteins like cryptochromes make this navigation possible. For this purpose, we strive to quantify the actual contribution of these effects to the macroscale biological response. 

We look to the deep past, using cutting-edge microspectroscopy to read the biological history recorded in ancient rocks.

The 3.8-billion-year History: We take on the challenge of investigating how early photosynthetic organisms co-evolved with global environmental shifts through the study of both extant and extinct photosynthetic systems.

Tracing the Deep Past through Spectroscopy: We analyze geological samples using advanced microscopy and spectroscopy to detect and decode traces of ancient photosynthetic materials.

A New Frontier: By accessing these molecular "fossils," we aim to bridge geology and biology from our own unique perspective, sparking a breakthrough in our integrated understanding of the co-evolutionary history of Earth and life.