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Nogawa C.,Azabu University | Baba H.,Azabu University | Masaoka T.,Japan National Research Institute of Fisheries And Environment of Inland Sea | Aoki H.,Mie Prefecture Fisheries Research Institute | Samata T.,Azabu University
Gene | Year: 2012

The molluscan shell is a composite of inorganic crystals comprising calcium carbonate and a minute amount of organic matrix. The organic matrix (OM) is intimately involved in every step of shell formation and has consequently received much attention in recent years. However, most of the deposited information has resulted from cDNA analysis, with little analysis of the genome, including the presence and effects of polymorphic genes encoding OM proteins.The current study aimed to clarify the genome structure of the . N16 gene from the Japanese pearl oyster, . Pinctada fucata, with particular reference to polymorphisms. The . N16 gene was analyzed using PCR and DNA sequencing. 23 polymorphic variants were identified from 28 individuals. The variants were analyzed for their relationship to shell formation. All the variations detected by genomic PCR appeared in the cDNAs, implying that all the polymorphisms were transcribed and translated into N16 proteins. Additional genome analysis revealed at least two . N16 genes, which were sequentially positioned, each of them comprising four exons and three introns.Further analyses of the transcriptional regulation and function of the . N16 genes may provide new insights into their role in molluscan biomineralization. © 2012. Source

Butler IV M.J.,Old Dominion University | Paris C.B.,University of Miami | Goldstein J.S.,University of New Hampshire | Matsuda H.,Mie Prefecture Fisheries Research Institute | Cowen R.K.,University of Miami
Marine Ecology Progress Series | Year: 2011

Behavior such as ontogenetic vertical migration (OVM) limits the transport of marine larvae with short pelagic larval durations (PLDs), but its effect on the supposed long-distance dispersal of larvae with long PLDs is unknown. We conducted laboratory tests of ontogenetic change in larval phototaxis and examined size-specific patterns of larval distribution in the plankton to characterize OVM in the Caribbean spiny lobster Panulirus argus during its long (6 mo) PLD. We then used a coupled biophysical model to explore the consequences of OVM and hydrodynamics on larval P. argus dispersal in the Caribbean Sea. Larvae reared in the laboratory were positively phototatic for the first 2 mo and then avoided light thereafter, similar that seen in the planktonic distribution of same-sized larvae. Simulations of larval dispersal from 13 spawning sites in the Caribbean Sea predicted that twice as many larvae would recruit to nurseries if they displayed OVM compared with passive dispersers. Larvae with OVM typically settled <400 km from where they were spawned, while passive dispersers often settled >1000 km away. OVM also produced an asymmetrical bimodal pattern of dispersal dominated by larvae that settled near their origin (~60%), but showed a second peak of larvae that dispersed over long distances (~20%). Hydrodynamics created subregional differences in the potential for self-recruitment. Our findings suggest that (1) larval behavior constrains the dispersal of even long-lived larvae, particularly in tandem with retentive oceanographic environments, and (2) larval sources of P. argus in the Caribbean Sea cannot be estimated from passive transport and surface circulation. © Inter-Research 2011. Source

Tanaka S.,Mie Prefecture Fisheries Research Institute | Yamamoto S.,Minami ise Town Fisheries Nursery Institute
Fish Pathology | Year: 2013

The occurrences of Caligus sclerotinosus, a parasitic copepod on cultured red sea bream Pagrus major, were surveyed in fish farms and the phototaxis of adult caligid was experimentally examined. The parasite infection occurred from April to December, in which up to approximately 500 caligids infected the external surface of each diseased fish, covering the whole body surface, eyes and fins. The main disease signs were scale exfoliation, abrasion and ulcerative lesions on the body surface, and chipped fins. Listless swimming near the water surface was also observed. Daily mortalities were usually below 0.1%. When illuminated at different light intensities, most adult caligids showed positive phototaxis and those illuminated at 50 ^imol/m2/s swam significantly faster than those illuminated at 200 and 800 ^imol/m2/s. When infected fish were illuminated from one direction in a tank, 2.5% of caligids moved from fish to the illuminated wall of tank. When an infected fish and an uninfected fish were separated with a screen partition in each tank and illuminated from one side, 25% of caligids moved from fish in the shaded side to fish in the illuminated side, but never vice versa, showing that fish-to-fish transfer of C. sclerotinosus adults was affected by light conditions. Source

Sugimoto R.,Kyoto University | Kasai A.,Kyoto University | Miyajima T.,University of Tokyo | Fujita K.,Mie Prefecture Fisheries Research Institute
Estuarine, Coastal and Shelf Science | Year: 2010

An important aspect of the nitrogen cycle in coastal environments concerns the source of the nitrogen used in primary production. Phytoplankton production in Ise Bay, one of the most eutrophic embayments in Japan, is supported by external nitrogen derived from rivers and the ocean, and regenerated nitrogen formed in hypoxic water within the bay. We evaluated the contribution of each source of dissolved inorganic nitrogen (DIN) to phytoplankton production in Ise Bay. A unique three-dimensional ecosystem model including nitrogen isotopes (δ15N) was developed based on precise observations. Model results revealed that DIN (=ammonium + nitrate) consumption by phytoplankton exceeds the DIN supply from the rivers and ocean, indicating that a large amount of phytoplankton production in Ise Bay depends on regenerated DIN within the bay rather than on newly supplied DIN. However, the ratio of consumption to external supply differs seasonally. Distributions of simulated δ15N clearly showed the source of nitrogen incorporated by phytoplankton in each source. The intrusion depth of oceanic water changes from the bottom to the middle layer in spring. Oceanic nitrate is transported into the euphotic layer by the middle layer intrusion and stimulates phytoplankton production at the bay mouth. The subsurface chlorophyll maximum layer then develops. In autumn, however, the intrusion depth of oceanic water changes from the middle layer to the bottom layer. Regenerated NO3-, which is accumulated in the hypoxic water mass, is uplifted and continuously supplied to the euphotic layer. These results imply that phytoplankton production in Ise Bay is mainly dominated by the internal cycle rather than the external supply. © 2009 Elsevier Ltd. All rights reserved. Source

Ogawa K.,University of Tokyo | Tanaka S.,Mie Prefecture Fisheries Research Institute | Sugihara Y.,Nagasaki Prefectural Institute of Fisheries | Takami I.,Nagasaki Prefectural Institute of Fisheries
Parasitology International | Year: 2010

A new sanguinicolid blood fluke, Cardicola orientalis n. sp., is described from the afferent branchial artery and heart of Pacific bluefin tuna Thunnus orientalis (Temminck & Schlegel) cultured in Mie and Nagasaki Prefectures, Japan. The new species is most similar to C. ambrosioi Braicovich, Etchegoin, Timi et Sardella, 2006 from the Brazilian flathead, Percophis brasiliensis Quoy & Gaimard, but can be differentiated by the position of the female genital pore (in midline or slightly sinistral in C. orientalis vs. sinistral in C. ambrosioi) and much longer distance between male and female genital pore (101 μm vs. 27 μm). In wet mount preparations of infected fish, eggs were accumulated in great numbers in the gill lamellae and afferent filament arteries. Importance of this blood fluke infection of cultured Pacific bluefin tuna in Japan is discussed. © 2009 Elsevier Ireland Ltd. All rights reserved. Source

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