National Institute for Basic Biology

Imaging Science

LABORATORY FOR SPATIOTEMPORAL REGULATIONSAssociate Professor

NONAKA, Shigenori

Specially Appointed Assistant Professor:
YOKE, Hiroshi
Postdoctoral Fellow:
TANIGUCHI, Atsushi
Technical Assistant:
ISHIBASHI, Tomoko

We pursued this question by measuring Ca2+ dynamics
in the node and found that the node cells apparently cause
stochastic elevation of Ca2+. The spatiotemporal distribution is equal on the left and right sides, but becomes moreprevalent on the left after the late headfold stage, whenflow-induced commitment occurs. This asymmetry wasdisrupted in dynein mutant iv/iv and pkd2-/- mutants, inaccordance to their left-right phenotypes.
Based on these findings, we are now examining thevalidity of the two major proposed models of flow
sensing, mechanosensing and chemosensing, as well as athird novel mechanism.

II. Development of light-sheet microscopy

Our laboratory is currently pursuing two paths of scientific inquiry that are of interest to developmental biology.
One is to clarify the mechanism of left-right (L-R) determination. The other is to develop imaging technologies
for biological analyses.

Visual overview of this lab’s work.

Light-sheet microscopy has become popular during thisdecade due to benefits such as low photodamage and fast
image acquisition. We are now running two light-sheet
microscopes, one commercial and the other self-made,and are maintaining them for collaborations and our own
research interest (this being left-right asymmetry).
Over several years, we have developed a fast lightsheet microscope named ezDSLM, in which the excitation light sheet and detection objective move insteadof the specimen for z-scanning. We installed an electrically tunable lens (ETL) to achieve greater speed and theexclusion of mechanical vibrations that disturb continuous 4D imaging of floating or loosely held specimens.
Our light-sheet microscopes are available to otherresearchers via NIBB’s Collaborative Researchand MEXT’s Advanced Bioimaging Support (ABiS)
programs. Numerous collaborations are in progressincluding observation of moving cell migration in zebrafish embryos, cleared mouse brains, etc.

I. Initial step for left-right asymmetry

In mammalian development, initial left-right asymmetry
first appears as cilia-driven leftward fluid flow on theventral surface of the node, and this flow provides theinitial cue for asymmetric gene expressions that actuallydetermine asymmetric morphogenesis. The mechanismsthat convert the flow to asymmetric gene expression, i.e.
the flow sensing mechanism, remain controversial, withseveral models being proposed, and the involvement ofCa2+ being suggested.

Figure 2. Images of floating volvox taken by ezDSLM with ETL. Left:
Single optical section. Right: Maximum intensity projection.

Publication List:〔Original papers〕

Y., Matsuo, M., Kurihara, K., Suzuki, K., Nonaka, S., and• Hirata,Sugawara, T. (2021). Colocalization Analysis of Lipo-Deoxyribozyme•Figure 1. Left: Distribution of Ca2+ elevation in a 2-somite wild-type
node. Right: Time course of Ca2+ elevation frequency at the left and theright sides.

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Consisting of DNA and Protic Catalysts in a Vesicle-Based Protocellular
Membrane Investigated by Confocal Microscopy. Life (Basel) 11, 1364.
DOI: 10.3390/life11121364
Ohmura, T., Nishigami, Y., Taniguchi, A., Nonaka, S., Ishikawa, T., andIchikawa, M. (2021). Near-wall rheotaxis of the ciliate Tetrahymena
induced by the kinesthetic sensing of cilia. Sci. Adv. 7, eabi5878. DOI:
10.1126/sciadv.abi5878