Ikuko Ohtani

Bio: Ikuko Ohtani is an academic researcher from Nagoya University. The author has contributed to research in topics: Absolute configuration & Moiety. The author has an hindex of 11, co-authored 18 publications receiving 3984 citations. Previous affiliations of Ikuko Ohtani include University of Tsukuba.

A novel dodecadepsipeptide, cereulide, isolated from Bacillus cereus causes vacuole formation in HEp-2 cells

Abstract: A HEp-2 cell-vacuolation factor was extracted and purified from the culture supernatant of a Bacillus cereus strain which caused emetic-syndrome food poisoning. The final preparation was chemically pure, and the toxin was named as cereulide. Mass spectrometry, NMR studies and chemical degradation revealed that the cereulide is a cyclic dodecadepsipeptide, (D-O-Leu-D-Ala- L-O-Val-L-Val)3, which is closely related to the potassium ionophore, valinomycin.

A new aspect of the high-field NMR application of Mosher's method. The absolute configuration of marine triterpene sipholenol A

Abstract: These results indicate that the high-field NMR application of Mosher's method may not work for a compound that possesses a sterically hindered secondary hydroxy group and that the problem can be overcome by inverting the hydroxy group

Ptilomycalin A: a novel polycyclic guanidine alkaloid of marine origin

Abstract: Identification par spectrometrie de masse d'un nouvel alcaloide guanidique d'origine marine (Eponge): la Ptilomycaline A

Toxic cyanobacteria in water: a guide to their public health consequences, monitoring and management.

Abstract: This book describes the present state of knowledge regarding the impact of cyanobacteria on health through the use of water. It considers aspects of risk management and details the information needed for protecting drinking water sources and recreational water bodies from the health hazards caused by cyanobacteria and their toxins. It also outlines the state of knowledge regarding the principal considerations in the design of programmes and studies for monitoring water resources and supplies and describes the approaches and procedures used. The development of this publication was guided by the recommendations of several expert meetings concerning drinking water (Geneva, December 1995; Bad Elster, June 1996) and recreational water (Bad Elster, June 1996; St Helier, May 1997). An expert meeting in Bad Elster, April 1997, critically reviewed the literature concerning the toxicity of cyanotoxins and developed the scope and content of this book. A draft manuscript was reviewed at an editorial meeting in November 1997, and a further draft was reviewed by the working group responsible for updating the Guidelines for Drinkingwater Quality in March 1998.

From soil to gut: Bacillus cereus and its food poisoning toxins

Abstract: Bacillus cereus is widespread in nature and frequently isolated from soil and growing plants, but it is also well adapted for growth in the intestinal tract of insects and mammals. From these habitats it is easily spread to foods, where it may cause an emetic or a diarrhoeal type of food-associated illness that is becoming increasingly important in the industrialized world. The emetic disease is a food intoxication caused by cereulide, a small ring-formed dodecadepsipeptide. Similar to the virulence determinants that distinguish Bacillus thuringiensis and Bacillus anthracis from B. cereus, the genetic determinants of cereulide are plasmid-borne. The diarrhoeal syndrome of B. cereus is an infection caused by vegetative cells, ingested as viable cells or spores, thought to produce protein enterotoxins in the small intestine. Three pore-forming cytotoxins have been associated with diarrhoeal disease: haemolysin BL (Hbl), nonhaemolytic enterotoxin (Nhe) and cytotoxin K. Hbl and Nhe are homologous three-component toxins, which appear to be related to the monooligomeric toxin cytolysin A found in Escherichia coli. This review will focus on the toxins associated with foodborne diseases frequently caused by B. cereus. The disease characteristics are described, and recent findings regarding the associated toxins are discussed, as well as the present knowledge on virulence regulation.

Manganese Cluster in Photosynthesis: Where Plants Oxidize Water to Dioxygen

Abstract: The essential involvement of manganese in photosynthetic water oxidation was implicit in the observation by Pirson in 1937 that plants and algae deprived of Mn in their growth medium lost the ability to evolve O{sub 2}. Addition of this essential element to the growth medium resulted in the restoration of water oxidation within 30 min. There is increased interest in the study of Mn in biological chemistry and dioxygen metabolism in the last two decades with the discovery of several Mn redox enzymes. The list of enzymes where Mn is required for redox activity includes a Mn superoxide dismutase, a binuclear Mn-containing catalase, a binuclear Mn-containing ribonucleotide reductase, a proposed binuclear Mn site in thiosulfate oxidase, a Mn peroxidase that is capable of oxidative degradation of lignin, and perhaps the most complex and important, the tetranuclear Mn-containing oxygen-evolving complex in photosystem II (Mn-OEC). Mn is well suited for the redox role with accessible oxidation states of II, III, and IV, and possibly V: oxidation states that have all been proposed to explain the mechanisms of the Mn redox enzymes.