Biodiversity risk assessment of genetically modified Chaetoceros gracilis for outdoor cultivation.

A genetically modified (GM) strain of the diatom Chaetoceros gracilis expressing the phosphite dehydrogenase gene (ptxD), which is a useful gene both for the biological containment and the avoidance of microbial contamination, was characterized to estimate the risk against the biodiversity by laboratory experiments. GM strain could grow in the medium containing phosphite as a sole source of phosphorus, while its general characteristics such as growth, salt tolerance, heat and dehydration resistance in the normal phosphate-containing medium were equivalent to those of wild type (WT) strain. The increase in potential toxicity of GM strain against plant, crustacean, fish and mammal was also disproved. The dispersal ability of WT strain cultured in an outdoor raceway pond was investigated for 28 days by detecting the psb31 gene in vessels, settled at variable distances (between 5 and 60 m) from the pond. The diatom was detected only in one vessel placed 5 m apart. To estimate the influence on the environment, WT and GM strains were inoculated into freshwater, seawater and soil. The influence on the microbiome in those samples was assessed by 16S rRNA gene amplicon sequencing, in addition to the analysis of the survivability of those strains in the freshwater and the seawater. The results indicated that the effect to the microbiome and the survivability were comparable between WT and GM strains. All results showed that the introduction of the ptxD gene into the diatom had a low risk on biodiversity.

[A study of seroprevalence of leptospirosis in Gunma Prefecture, 2010].

OBJECTIVES: Leptospirosis is a zoonotic infection; water and soil are contaminated with Leptospira through the urine of rodents carrying the agent in the kidneys, and then the infection is established percutaneously or orally. In November 2009, the first notification of leptospirosis was submitted in Gunma Prefecture. It is important to clarify the current status of the leptospirosis epidemic in the prefecture and to enlighten residents and healthcare professionals. Hence, we examined the infection status of leptospirosis in residents living near the residence of the patient in this study. SUBJECTS: SUBJECTS were residents of Isesaki City, Gunma Prefecture, aged 40-64 years and who had undergone a specific health examination (mass health examination) for insured persons under Japan's National Health Insurance on April 23 and 26, 2010. SAMPLE SIZE: We randomly selected 100 subjects from residents who underwent the examination, and antibody titer against leptospirosis was measured. Testing method: Measurement of the antibody titer was commissioned to the National Institute of Infectious Diseases. Microscopic agglutination tests using 6 serotypes of living Leptospira that are widely distributed to the main islands of Japan were performed. RESULTS: One hundred eighty subjects underwent the examination on the 2 days, and 174 of them consented to participate in the study. Serum antibody titer was measured in 100 patients, and the results were all negative. CONCLUSION: Leptospirosis is a treatable disease when it is diagnosed; therefore, early diagnosis and treatment is important. Mild cases may be missed. Awareness of leptospirosis is low among healthcare professionals in the prefecture. Although it is a rarely infectious disease, it is important to make leptospirosis known to medical associations in the prefecture and to conduct training workshops and similar activities.