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Kai Y.,Kyoto University | Orr J.W.,National Oceanic and Atmospheric Administration | Sakai K.,Noto Marine Center | Nakabo T.,Kyoto University
Ichthyological Research | Year: 2011

The molecular phylogeny of the Careproctus rastrinus species complex is presented on the basis of sequence variations in the 16S rRNA and cytochrome b genes (1,447 base pairs) of mitochondrial DNA using specimens collected from across the North Pacific and its marginal seas, including the Sea of Japan, the Pacific coast of Japan, the Sea of Okhotsk, the Bering Sea, the Gulf of Alaska, and the Arctic Ocean. Gene flow and migration between geographic regions is apparently strictly restricted in the C. rastrinus species complex, as this phylogeny revealed nine genetically diverged groups in the C. rastrinus species complex, most of which corresponded well with major geographic regions. Most of the groups were different in terms of morphological characters. Five nominal species have been considered to be members of the complex and have been variously recognized as being valid or as synonyms of C. rastrinus, but the present genetic and morphological differences suggested that the C. rastrinus species complex represents far more divergence. Such cryptic diversity of the C. rastrinus species complex defined by geographic regions may be related to their low dispersal ability, because they bear large demersal eggs. The genetic divergence suggested that colder climates from the late Pliocene and the isolation of marginal seas during the Pleistocene may have driven the divergence of the C. rastrinus species complex. © 2011 The Ichthyological Society of Japan.

Kai Y.,Kyoto University | Sakai K.,Noto Marine Center | Orr J.W.,National Oceanic and Atmospheric Administration | Nakabo T.,Kyoto University
Ichthyological Research | Year: 2011

The Careproctus rastrinus species complex, widely known from the North Pacific, has been revealed recently to include nine genetically divergent groups on the basis of mitochondrial DNA (mtDNA) sequence variations. Herein we describe an AFLP analysis that focuses on three closely related groups in order to clarify the evolutionary history of the species complex in the Sea of Japan and off the Pacific coast of Japan. A principal coordinate analysis indicated the absence of nuclear divergence in two groups defined by mtDNA variations in the Sea of Japan, whereas another group from the Pacific coast of northern Japan was clearly distinct. This suggests extensive gene flow between two groups in the Sea of Japan as a result of secondary contact. © 2011 The Ichthyological Society of Japan.

Suzuki N.,Kyushu University | Suzuki N.,Kanazawa University | Yachiguchi K.,Kyushu University | Yachiguchi K.,Noto Marine Center | And 20 more authors.
Journal of the Faculty of Agriculture, Kyushu University | Year: 2011

The fish scales are the major source of internal calcium requirement due to having a higher internal calcium reservoir than the body skeleton during the periods of drastic calcium demand, such as sexual maturation. Therefore, we developed original in vitro assay system using goldfish scales that contain osteoclasts and osteoblasts, and examined the direct effect of inorganic mercury (HgCl2) on osteoclasts and osteoblasts. In this assay system, we measured the activities of tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) as respective indicators of each activity in osteoclasts and osteoblasts. TRAP activity in the scales significantly decreased by the treatment of HgCl2 (10-5 to 10-3M) during 6 hrs of incubation. In addition, mRNA expressions of osteoclastic markers: TRAP and cathepsin K significantly decreased compared with control. In our knowledge, this is the first report of a direct effect of inorganic mercury on osteoclasts. On the other hand, ALP activity decreased after exposures of HgCl2 at a concentration of 10-6, 10-5 or 10-4M for 36 and 64 hrs, although its activity did not change after 6 and 18 hrs. The mRNA expression of metallothionein (MT) which is a metal-binding-protein that protects the organism from heavy metal, significantly increased by HgCl2 (10-4M) although insulin-like growth factor-I (osteoblastic marker) was less than those of control scales by treatment with HgCl2 (10-4M). These results suggests that osteoblasts may synthesize MT and protect from mercury until 18 hrs incubation. Thus, the scale in vitro assay system would be a useful means for analysis of heavy metal on bone metabolism.

Sakai K.,Noto Marine Center | Nakabo T.,Kyoto University
Ichthyological Research | Year: 2014

The taxonomy of the Atlantic and Eastern Pacific species of Kyphosus is reviewed with K. bosquii (Lacepède 1802), K. incisor (Cuvier 1831), K. analogus (Gill 1862) and K. elegans (Peters 1869) considered valid, and K.atlanticus sp. nov. newly described. Kyphosus bosquii and K.atlanticus are both characterized by 12 dorsal- and 11 anal-fin soft rays, but differ in the number of longitudinal scale rows along the midbody (61-66, mode 63 vs. 50-56, mode 54). Kyphosus incisor and K. analogus, characterized by 14 dorsal- and 13 anal-fin soft rays, similarly differ from each other in midbody longitudinal scale row counts (57-64, mode 60 vs. 68-74, mode 70 or 72). Kyphosus elegans is characterized by 13 dorsal- and 12 anal-fin soft rays, and 51-57 midbody longitudinal scale rows. Kyphosus bosquii, K.atlanticus and K. incisor are distributed in the Atlantic Ocean, K. analogus and K. elegans occurring in the Eastern Pacific. The holotype of Pimelepterus flavolineatus Poey 1866, here regarded as a junior synonym of K. incisor, was located within a collection of Cuban fishes donated to the Smithsonian Institution by Poey in 1873. A neotype is designated here for K. analogus.Pimelepterus gallveii Cunningham 1910, Kyphosus palpebrosus Miranda-Ribeiro 1919 and K.metzelaari Jordan and Evermann 1927 are recognized as junior synonyms of K. bosquii. Pimelepterus sandwicensis Sauvage 1880 is a junior synonym of K. elegans. Perca saltatrix Linnaeus 1758, together with the replacement name Perca sectatrix Linnaeus 1766, is regarded as nomina dubia. © 2014 The Ichthyological Society of Japan.

Tsukagoshi H.,Hokkaido University | Tsukagoshi H.,Iwate University | Sakai K.,Noto Marine Center | Yamamoto K.,Nomi Inc | And 2 more authors.
Ichthyological Research | Year: 2013

The amphidromous sculpin Cottus pollux small-egg type (SE) is an endemic species in rivers that flow into the Pacific Ocean on the east side of Honshu Island, Japan. However, our molecular genetic and morphological analyses using recently collected specimens showed that C. pollux SE inhabits some rivers flowing into the Sea of Japan, where this species is originally non-indigenous. Thus, these results suggest that C. pollux SE was anthropogenically introduced into these rivers. In addition, our data on the size distribution of juvenile fishes suggest that non-indigenous C. pollux SE reproduce at least in rivers of Ishikawa Prefecture. © 2012 The Ichthyological Society of Japan.

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