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Sekino M.,Tohoku National Fisheries Research Institute | Saitoh K.,Japan National Research Institute of Fisheries Science | Shimizu D.,Fisheries Research Agency | Wada T.,Fukushima Prefectural Fisheries Experimental Station | And 4 more authors.
Conservation Genetics | Year: 2011

We examined the genetic population divergence of the spotted halibut Verasper variegatus. A previous report suggested two conservation units for this species along the Japanese Pacific coast. Extending the coverage of the genomes (29 microsatellites and three mitochondrial DNA segments) revealed hitherto-undetected genetic population boundaries. We screened population samples from the major habitats along the Japanese coast and the Yellow Sea coast (East Asian Continent). Significant genetic differentiation was found in every comparison between the habitats. In most cases, the nuclear and mitochondrial population divergences were incongruent, most likely caused by differences between the two genomes in the effects of genetic drift after recent population isolation and bottleneck events. We discuss the ecological and evolutionary mechanisms of the genetic structure as well as the units of conservation. The present study illustrates the merits of wider coverage of genomes in genetic population analysis especially for species with a shallow population history. © 2010 Springer Science+Business Media B.V.


Suga Y.,Miyagi Prefectural Government | Koshimura S.,Tohoku University | Kobayashi E.-I.,Kobe University
Journal of Disaster Research | Year: 2013

Drifting ship due to tsunami inundation flow may cause additional damage in harbor area. Many drifting ships were found in the 2011 Great East Japan earthquake tsunami and these caused various problems (damage of ships themselves, striking other structures and obstacle for restoration). In this sense, it is very important for disaster prevention to predict the drifting motion of a large ship by tsunami current. This study aims to simulate the drifting motion of ships by the 2011 Tohoku earthquake tsunami in Kesennuma harbor, Miyagi Prefecture. First, we simulated the hydrodynamic features of the 2011 tsunami by numerical simulation. Secondly, we analyzed the drifting motion of large ships using the result of tsunami numerical simulation. In the analysis, several test cases were conducted by changing parameter and initial position of the ship. Then we verified the results of the ship drifting simulation by comparing with actual grounding position of ships. Throughout the comparisons and verifications, we found the grounding position by the simulation was generally consistent with actual position of ships. Although it is necessary to verify the drifting route of ships, the results suggest that this model is beneficial for future disaster prevention.


Tomita S.,Tohoku University | Tran N.H.,Tohoku University | Miyake Y.,Tohoku University | Komatsu K.,Tohoku University | And 7 more authors.
Asia-Pacific Microwave Conference Proceedings, APMC | Year: 2010

For realizing over 2 Gbit/s transmission rate at portable terminals, we propose Advanced Kiosk Model (AKM) of 60 GHz band indoor multipath condition with hand tremor. In the AKM, coverage and bit error rate (BER) are defined as 10 m and 1 × 105 or less, respectively. Environment of multipath with Doppler effect by hand tremor causes serious inter-symbol interference (ISI). In this paper, we evaluate influence of hand tremor at 60 GHz communication systems. Measurements of relative amplitude with 2 path environment are well matched to simulation results. Simulation results show hand tremor cause serious ISI. Due to ISI, large degradation of BER performance is occurred every 1 ms periodically. Therefore, it is strongly necessary to consider influence of hand tremor with multipath environment for designing of 60 GHz-band wireless communication system. © 2010 IEICE Institute of Electronics Informati.


Kita K.,Forestry Research Institute | Uchiyama K.,Forestry Research Institute | Ichimura Y.,Miyagi Prefectural Government | Moriguchi Y.,Niigata University | And 2 more authors.
Journal of Forest Research | Year: 2014

The hybrid between Kuril larch (Larix gmelinii var. japonica) and Japanese larch (L. kaempferi) is an important afforestation tree species in Hokkaido, Japan, because of its rapid juvenile growth, straight stem, and resistance to bark gnawing by voles. To produce desirable hybrid seedlings, precise seedling discrimination is essential. However, continuous variations in morphological and phenological traits occur across L. gmelinii var. japonica × L. kaempferi and L. gmelinii var. japonica × L. gmelinii var. japonica seedlings. Therefore, we used DNA markers to verify and improve the morphological and phenological discrimination method. We collected seeds from an interspecific seed orchard and, using chloroplast DNA analysis, we showed that the hybridization rates of 1-year-old seedlings were different between years (2004, 23.2 %; 2005, 53.6 %) and between mother trees (2004, 5.8–39.4 %; 2005, 20.0–81.0 %). Discriminant analyses revealed that the root collar diameter of 2-year-old seedlings, number of sylleptic branches of 2-year-old seedlings, and day of terminal bud set in 1- and 2-year-old seedlings are traits that aid in discriminating hybrid seedlings. The proportions of correctly discriminated individuals were found to be 81.7–88.2 % when using improved phenotypic discrimination methods. These methods adopted traits with high discrimination abilities during discriminant analyses and determined the selection intensity according to the hybridization rate estimated from the DNA markers. In contrast, the proportions of correctly discriminated individuals obtained using the current method were lower, 72.7–78.5 %, because this method was based on seedling height and adopted a constant selection intensity. © 2014, The Japanese Forest Society and Springer Japan.


Kamiyama T.,Tohoku National Fisheries Research Institute | Yamauchi H.,Miyagi Prefectural Government | Nagai S.,Japan National Research Institute of Fisheries Science | Yamaguchi M.,Japan National Research Institute of Fisheries And Environment of Inland Sea
Journal of Oceanography | Year: 2014

The tsunami caused by the Great East Japan Earthquake on 11 March 2011 greatly influenced the coastal benthic environment on the northern Pacific coast of Japan. We used the direct count method to investigate changes in the abundance and distribution of Alexandrium (Alexandrium tamarense and Alexandrium catenella) cysts before and after the tsunami in Sendai Bay. Densities of Alexandrium cysts in sediments collected in summer 2011 ranged from 0 to 8,190 cysts cm-3. In the western part of the bay, the density increased greatly after the tsunami, the highest density being approximately 10 times the density recorded in 2005. Molecular identification of single cysts with multiplex polymerase chain reaction (PCR) showed that Alexandrium tamarense dominated the cyst population in the southwestern part of the bay in 2011. Furthermore, accumulation of cysts on the surface sediment after disturbance of the sediment was confirmed by a laboratory experiment. The main factor causing the drastic changes in abundance and distribution of Alexandrium cysts after the earthquake was considered to be vertical and horizontal redistribution of the cysts in sediments after the tsunami. © 2014 The Oceanographic Society of Japan and Springer Japan.


Tanaka C.,Kitasato University | Tanaka C.,Tokyo Medical University | Aoki R.,Kitasato University | Ida H.,Kitasato University | And 6 more authors.
Fisheries Science | Year: 2016

We developed a novel molecular genetic method using restriction fragment length polymorphisms (RFLPs) to identify the taxonomically debatable Japanese sand lances of the genus Ammodytes. Partial nucleotide sequences of the mitochondrial DNA cytochrome c oxidase subunit 1 (COI) gene of Ammodytes japonicus (n = 405), Ammodytes heian (n = 284), and Ammodytes hexapterus (n = 15) were determined and found to contain species-specific restriction sites for HindIII-HF and RsaI enzymes. The observed RFLP patterns from a combination of two enzymes were specific in each species except for specimens with rare haplotypes of A. japonicus (1.5 %) and A. heian (2.1 %), whereas detailed morphological analysis using 29 characters failed to discriminate the COI-identified specimens of these two species collected from the same locality. The developed molecular method will allow rapid and precise identification of the Japanese sand lances, especially for the sympatric A. japonicus and A. heian, thereby providing a reliable means for ecological research and stock management of these species. © 2016 Japanese Society of Fisheries Science

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