Biosynthesis and Release of Methylarsenic Compounds During the Growth of Freshwater Algae

金沢大学工学部Arsenic transformations by freshwater algae have been studied under laboratory conditions. By the use of a new analytical method, we identified methylarsenic(III) species in the growth medium of green-alga Closterium aciculare incubated under axenic conditions. The arsenate concentration in the experimental medium began to decrease just after inoculation, and the levels of arsenite and methylarsenicals increased with the growth of C. aciculare. Initially, most of the arsenate was converted into arsenite, which peaked in concentration during the exponential phase. Methylarsenicals accumulated rapidly in the stationary phase. DMAA(V) production was enhanced when the ratio of phosphate to arsenate decreased in the culture medium. The levels of DMAA(V) increased continuously toward the end of the experiment. On the other hand, methylarsenic(III) species remained relatively steady during the stationary phase. Methylarsenic(III) species accounted for 0-35% of methylarsenicals. These results suggest that arsenite and methylarsenicals (containing methylarsenic(III) species) are supplied by phytoplankton, and serve as evidence of the origin of methylarsenic(III) species in natural waters. © 2001 Elsevier Science Ltd

A Case of Perforated Sigmoid Diverticulitis in Which Gram Staining of Ascitic Fluid Was Useful for Diagnosis

An 85-year-old woman was admitted to our hospital for steroid therapy for relapsing nephrotic syndrome. During hospitalization, she complained of sudden epigastric pain at night. Although there were signs of peritoneal irritation, CT showed a large amount of ascitic fluid, but no free intraperitoneal gas. Gram staining of ascitic fluid obtained by abdominal paracentesis showed Gram-negative rods, which raised a strong suspicion of gastrointestinal perforation and peritonitis. Therefore, emergency surgery was performed. Exploration of the colon showed multiple sigmoid diverticula, one of which was perforated. The patient underwent an emergency Hartmann's procedure. Imaging studies failed to reveal any evidence of gastrointestinal perforation, presenting a diagnostic challenge. However, a physician performed rapid Gram staining of ascitic fluid at night when laboratory technicians were absent, had a strong suspicion of gastrointestinal perforation, and performed emergency surgery. Gram staining is superior in rapidity, and ascitic fluid Gram staining can aid in diagnosis, suggesting that it should be actively performed. We report this case, with a review of the literature on the significance of rapid diagnosis by Gram staining

Oxidative Stress-induced Interaction between Autophagy and Cellular Senescence in Human Keratinocytes

福岡歯科大学2017年

Evaluation of major nutrients regulating the growth of diatoms in Harima-Nada, the Seto Inland Sea, Japan

　In the eastern Seto Inland Sea, dissolved inorganic nitrogen has decreased due to the reduction of nutrient inputs, and there have been changes in the total cell density and the composition of the phytoplankton assemblages. The major phytoplankton component was diatoms, and the contribution was always over 90 percent of total phytoplankton since the 1990s. In order to elucidate growth characteristics and nutrient consumption of diatom species, we conducted major nutrients-enrichment bottle incubation experiments on shipboard using the surface waters in Harima-Nada, eastern part of the Seto Inland Sea. Seawater incubation experiments demonstrated that nutrient environments for phytoplankton are in a state of nitrogen-limitation in Harima-Nada. The addition of nitrate to surface waters of this coastal region promotes blooms of large chain-forming diatom species. These results suggest that diatom blooms cause depletion of the nutrients (mainly nitrogen) in Harima-Nada

The possibility of regulating the species composition of marine phytoplankton using organically complexed iron

金沢大学理工研究域物質化学