Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus-the 'D-shuttle' project

Twelve high schools in Japan (of which six are in Fukushima Prefecture), four in France, eight in Poland and two in Belarus cooperated in the measurement and comparison of individual external doses in 2014. In total 216 high-school students and teachers participated in the study. Each participant wore an electronic personal dosimeter 'D-shuttle' for two weeks, and kept a journal of his/her whereabouts and activities. The distributions of annual external doses estimated for each region overlap with each other, demonstrating that the personal external individual doses in locations where residence is currently allowed in Fukushima Prefecture and in Belarus are well within the range of estimated annual doses due to the terrestrial background radiation level of other regions/countries.

Construction of Pta-Ack pathway deletion mutants of Escherichia coli and characteristic growth profiles of the mutants in a rich medium

Escherichia coli grown in a rich medium excreted acetate and reused the acetate. Using cloned genes and a plasmid with a temperature-sensitive replication origin, three kinds of Pta-Ack pathway deletion mutants were constructed. Acetate production and reuse by wild-type cells grown in the rich medium was confirmed to largely occur through the Pta-Ack pathway. The deletion mutants of the gene encoding phosphotransacetylase secreted pyruvate before the secretion of acetate into the medium. A deletion mutant of the gene encoding acetate kinase grew at a slow rate, but its secretion and use of acetate were rapid. These results indicated that a pathway(s), other than the Pta-Ack pathway, functions in the control of excess carbon flow in the mutants.

Identification and characterization of the ackA (acetate kinase A)-pta (phosphotransacetylase) operon and complementation analysis of acetate utilization by an ackA-pta deletion mutant of Escherichia coli

The pta gene encoding phosphotransacetylase was cloned on a high copy plasmid with or without the ackA gene encoding acetate kinase in Escherichia coli. The acetate kinase and phosphotransacetylase were overproduced in cells harboring the plasmid possessing both genes. Nucleotide sequencing of the pta gene revealed that it is able to produce a polypeptide comprising 714 amino acid residues, which starts at 70 base pairs downstream from the stop codon of the ackA gene. The 77-kDa protein band of overproduced phosphotransacetylase was observed on SDS-polyacrylamide gel electrophoresis, of which the amino terminal sequence corresponds to that of the deduced polypeptide without the amino terminal methionine. Two transcripts of pta of different sizes were found in the cells. A 3,700 nucleotide transcript, which covers the ackA and pta genes, seemed to be produced by the first promoter in the operon and a 2,300 nucleotide transcript, which covers just pta, seemed to be produced by the second promoter. In a synthetic medium containing acetate as the sole carbon source, the growth of an ackA-pta double mutant was greatly impaired. Complementation analyses revealed that both the acetate kinase and phosphotransacetylase were required for the rapid growth in the acetate medium.

Urinary beta-2-microglobulin does not serve as diagnostic tool for Minamata disease

"Minamata disease" (methylmercury poisoning), originally found in Minamata, Japan 3 decades ago, still poses a medico-socio-legal problem mostly resulting from difficulty in drawing diagnostic demarcation. To examine the efficacy of urinary beta-2-microglobulin (BMG) in identifying patients with Minamata disease, the authors studied 115 patients (63 males and 52 females) who were officially registered for compensation (registered patients); 114 patients (54 males, 60 females) currently undergoing medical evaluations for compensation (unregistered patients); and 82 control subjects (40 males, 42 females) matched for sex and age. There was no significant difference with regard to urinary BMG (corrected by creatinine) among the above three groups, although there was a parallel increase in urinary BMG and neurological scores of male patients which suggested the presence of a dose-effect relationship. Although renal tubular dysfunction manifesting hyper-beta-2-microglobulinuria has been reported in patients with Minamata disease, our findings indicate that excessive excretion of BMG is not a satisfactory diagnostic parameter for Minamata disease.