No abstract

Laboratory-based studies have suggested that marine organisms can be harmed by ingesting microplastics. However, unless the current and future microplastic abundance in the ocean environment is quantified, these experimental studies could be criticized for using an unrealistic density or sparsity of microplastics. Here we show the secular variations of pelagic microplastic abundance in the Pacific Ocean from 1957 to 2066, based on a combination of numerical modeling and transoceanic surveys conducted meridionally from Antarctica to Japan. Marine plastic pollution is an ongoing concern especially in the North Pacific, and pelagic microplastics are regarded as non-conservative matter due to the removal processes that operate in the upper ocean. The results of our numerical model incorporating removal processes on a 3-year timescale suggested that the weight concentrations of pelagic microplastics around the subtropical convergence zone would increase approximately twofold (fourfold) by 2030 (2060) from the present condition.

To investigate concentrations of pelagic micro- (<5mm in size) and mesoplastics (>5mm) in the East Asian seas around Japan, field surveys using two vessels were conducted concurrently in summer 2014. The total particle count (pieces km(-2)) was computed based on observed concentrations (pieces m(-3)) of small plastic fragments (both micro- and mesoplastics) collected using neuston nets. The total particle count of microplastics within the study area was 1,720,000 pieces km(-2), 16 times greater than in the North Pacific and 27 times greater than in the world oceans. The proportion of mesoplastics increased upstream of the northeastward ocean currents, such that the small plastic fragments collected in the present surveys were considered to have originated in the Yellow Sea and East China Sea southwest of the study area.

Deviations from the universal genetic code have been reported for several microorganisms. Termination codons are used for coding some amino acids in Paramecium, Mycoplasma or Tetrahymena, and in Escherichia coli, the UGA termination codon is used to code for selenocysteine. In mitochondria, the changes of sense codons to termination codons or to codons encoding other amino acids have also been reported. Here we report another example of divergence from the universal code, this time in a non-spore-forming yeast Candida cylindracea, in which the universal codon for leucine, CUG, is used to code for serine. This conclusion is based on the observations that: (1) the amino-acid composition and the partial amino-acid sequences of an extracellular lipase from this yeast agreed with those deduced from the complementary DNA if CUG was assumed to specify serine; and (2) serine, but not leucine, was incorporated into a polypeptide in a cell-free translation system from this yeast in the presence of a synthetic CUG oligomer.

Tsunami accompanied with the Sumatra earthquake of 26 December 2004 affected many countries around the Indian Ocean. Thailand located approximately 500 km east of its source, was also severely suffered from the tsunami. From 24 February through 4 March 2005, we surveyed the damaged areas in Thailand from south of Phuket Island up to the border of Myanmar including four islands. The whole coastal area facing the Andaman Sea could be covered. We measured 37 points in total, the tsunami heights are less than 10 m, except at a few locations. We found that the largest tsunami height reached up to 19.6 m at Ban Thung Dap of Phra Thong Island. During our survey, we also collected five paper copies of analog tide gauge records. In addition that we could detect two other tide gauge records from the web-site. Therefore, totally seven tide gauge records were obtained in Thailand. All of the recorded tsunami waveforms indicate that sea level initially withdrew with duration in 30 to 60 min, followed by the rising-up. This phenomenon corresponds to the eyewitnesses' accounts of the survivors who experienced the tsunami.