The Kuroda Chiromorphology project investigated the chirality of shape at different levels, from molecules to crystals in the non-biological domain, and from gene products to individual living organisms in the biological domains, with a view to linking these microscopic and macroscopic domains. The term gchiromorphologyh was coined by Kuroda from the words gchiralh and gmorphologyh to describe the concept of chirality of shape across these many domains.
Research Director: Dr. Reiko Kuroda
(Professor, Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo)
Research Term 1999-2004
A) Molecular chiromorphology
UCS1: The first spectrophotometer capable of simultaneously measuring linear dichroism, linear birefringence, circular dichroism (CD) and circular birefringence (CB) was developed. Only with this machine can one measure artefact-free CD spectra of samples with macroscopic anisotropies, such as crystals and films.
UCS2: A second model was developed for measuring diffuse reflectance CD spectra of powder samples and for measuring artefact-free CD spectra of soft materials affected by gravity, e.g., gels. Using UCS2 it was possible to carry out real-time measurements of peptides during aggregation, which is relevant to neurodegenerative disorders.
Solid-state crystallization of charge-transfer adducts: Simple co-grinding of organic crystals was found to produce strongly coloured charge-transfer type co-crystals in the solid state without melting, which are sometimes different from crystals obtained from solution. During the process, hydrogen-bonded partners are exchanged and molecules are diffused and rearranged, with molecular chirality being recognized.
Novel systems with chirality: Novel solid-state chemistry systems incorporating chirality were developed. For example, the conformational chirality of molecules was transferred to configurational chirality by crystallization and a subsequent solid-state reaction, yielding enantio-selective (unlike racemates for corresponding solution reactions) and uniquely stereo specific products. In some cases, a chiral cavity created in crystals was used for optical resolution of alcohols.
B) Organismal chiromorphology
Robust breeding program: A robust breeding program was developed to establish homozygous snail lines and for the large-scale production of eggs and snails required for all biochemical and molecular biology studies.
General strategies: Due to a lack of genetic maps and DNA sequence data for the snail, new techniques were either developed or adapted to study L. stagnalis. Several approaches to reveal molecular mechanisms that determine snail handedness were studied in parallel, which include the establishment of a bioassay system, visualization of cytoskeletal dynamics, differential analysis, homologue cloning, genetic backcrossing approaches and the state-of-the art mass spectrometric de novo sequencing following the two-dimensional polyacrylamide gel electrophoresis of proteins from l one-cell eggs.
Cytoskeletal dynamics and chirality of snails: The dynamics of the major cytoskeletal proteins, actin and tubulin, in both right- and left-handed L. stagnalis embryos were visualized by using confocal immunofluorescence. Significantly, contrary to previous assumptions, it was found that the cleavage patterns at the third cleavage stage for dextral and sinistral snails are not mirror images of each other. The crucial importance of the chirality-dependent cytoskeletal organization revealed by cell biological techniques was corroborated by genetic approaches, and it was found that a strong genetic linkage exists between the genes that induce the dextral-specific Spiral Deformation (SD) and/or Spindle Inclination (SI) and the long-sought still-unknown organismal chirality-determining gene(s).