Overview of the super-resolution and advanced microscopy imaging session at the 21st IUPAB and the 62nd Biophysics Society of Japan joint congress.

Recent advancements in microscopic techniques have significantly progressed, with improvements in fundamental parameters such as resolution, as well as the emergence of novel imaging techniques for measuring cellular information. In this session, six invited speakers introduced recent advancements in super-resolution and advanced microscopy imaging, covering both the development of novel microscopy techniques and their biological applications.

BMP4 regulates asymmetric Pkd2 distribution in mouse nodal immotile cilia and ciliary mechanosensing required for left-right determination.

Background: Mouse nodal immotile cilia mechanically sense the bending direction for left-right (L-R) determination and activate the left-side-specific signaling cascade, leading to increased Nodal activity. Asymmetric distribution of Pkd2, a crucial channel for L-R determination, on immotile cilia has been reported recently. However, the causal relationship between the asymmetric Pkd2 distribution and direction-dependent flow sensing is not well understood.

Optical microscopic imaging, manipulation, and analysis methods for morphogenesis research.

Morphogenesis is a developmental process of organisms being shaped through complex and cooperative cellular movements. To understand the interplay between genetic programs and the resulting multicellular morphogenesis, it is essential to characterize the morphologies and dynamics at the single-cell level and to understand how physical forces serve as both signaling components and driving forces of tissue deformations. In recent years, advances in microscopy techniques have led to improvements in imaging speed, resolution and depth.

Biophysical Analysis of Mechanical Signals in Immotile Cilia of Mouse Embryonic Nodes Using Advanced Microscopic Techniques.

Immotile cilia of crown cells at the node of mouse embryos are required for sensing leftward fluid flow that gives rise to the breaking of left-right (L-R) symmetry. The flow-sensing mechanism has long remained elusive, mainly because of difficulties inherent in manipulating and precisely analyzing the cilium. Recent progress in optical microscopy and biophysical analysis has allowed us to study the mechanical signals involving primary cilia.

Immotile cilia mechanically sense the direction of fluid flow for left-right determination.

Immotile cilia at the ventral node of mouse embryos are required for sensing leftward fluid flow that breaks left-right symmetry of the body. However, the flow-sensing mechanism has long remained elusive. In this work, we show that immotile cilia at the node undergo asymmetric deformation along the dorsoventral axis in response to the flow.

Planar cell polarity-dependent asymmetric organization of microtubules for polarized positioning of the basal body in node cells.

For left-right symmetry breaking in the mouse embryo, the basal body must become positioned at the posterior side of node cells, but the precise mechanism for this has remained unknown. Here, we examined the role of microtubules (MTs) and actomyosin in this basal body positioning. Exposure of mouse embryos to agents that stabilize or destabilize MTs or F-actin impaired such positioning.

Angle change of the A-domain in a single SERCA1a molecule detected by defocused orientation imaging.

The sarcoendoplasmic reticulum Ca-ATPase (SERCA) transports Ca ions across the membrane coupled with ATP hydrolysis. Crystal structures of ligand-stabilized molecules indicate that the movement of actuator (A) domain plays a crucial role in Ca translocation. However, the actual structural movements during the transitions between intermediates remain uncertain, in particular, the structure of E2PCa has not been solved.

Ciliogenesis-coupled accumulation of IFT-B proteins in a novel cytoplasmic compartment.

Cluap1/IFT38 is a ciliary protein that belongs to the IFT-B complex and is required for ciliogenesis. In this study, we have examined the behaviors of Cluap1 protein in nonciliated and ciliated cells. In proliferating cells, Cluap1 is located at the distal appendage of the mother centriole.

Three-dimensional tracking of microbeads attached to the tip of single isolated tracheal cilia beating under external load.

To study the properties of tracheal cilia beating under various conditions, we developed a method to monitor the movement of the ciliary tip. One end of a demembranated cilium was immobilized on the glass surface, while the other end was capped with a polystyrene bead and tracked in three dimensions. The cilium, when activated by ATP, stably repeated asymmetric beating as in vivo.