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Kazuo Ogawa

Publications and source records attributed to Kazuo Ogawa.

At least 19 recordsLinked to original sources
PubMed2006

Involvement of host recognition by oncomiracidia and post-larval survivability in the host specificity of Heterobothrium okamotoi (Monogenea: Diclidophoridae).

Heterobothrium okamotoi, a monogenean gill parasite, shows high host specificity for tiger puffer, Takifugu rubripes. In the present study, in vivo and in vitro experimental infections were conducted using various fish species, including T. rubripes, to understand the mechanisms of specificity. In in vivo experiments, T. rubripes, grass puffer, Takifugu niphobles, olive flounder, Paralichthys olivaceus, and red sea bream, Pagrus major, were exposed to oncomiracidia of H. okamotoi labelled with a fluorescent dye, 5- (and -6) carboxyfluorescein diacetate succinimidyl ester, and the numbers of parasites on the gills and skin were recorded at intervals. Oncomiracidia were attached to gills and skin of all the experimental fish species immediately after exposure, and the infection intensity on T. rubripes was higher than that on T. niphobles and much higher than those on the other two species. After 2 days, the attached parasites remained on the gills of T. rubripes, but disappeared from the other hosts. During in vitro experiments, gill filaments excised from seven different fish species (four fish species used in the in vivo experiments and panther puffer, Takifugu pardalis, southern flounder, Paralichthys lethostigma and spotted halibut, Verasper variegates) were exposed to oncomiracidia and the attachment to each fish species and subsequent larval behaviour was observed. The percentage of post-larvae that attached to T. rubripes was slightly higher than those which attached to congeneric fish species and much higher than those of non-tetraodontid fish species. In vivo and in vitro experiments demonstrated that oncomiracidia of H. okamotoi have an affinity for their natural host, T. rubripes, and congeneric fish species. The disappearance of attached post-larvae from 'alien' hosts within 2 days during in vivo experiments suggested that host recognition by oncomiracidia and subsequent post-larval survivability are involved in the host specificity of H. okamotoi.

Animals↗
PubMed2006

Two new species of hexabothriid monogeneans from the ginzame Chimaera phantasma and shortspine spurdog Squalus mitsukurii.

Descriptions are given for two new species of hexabothriid monogeneans, one collected from the gills of shortspine spurdog Squalus mitsukurii and the other from the gills of the ginzame Chimaera phantasma in Sagami Bay on the Pacific coast of Japan. Squalonchocotyle mitsukurii n. sp. from Squalus mitsukurii can be distinguished from Squalonchocotyle squali MacCallum, 1931, the most closely related species, by the inwardly curved vagina. Callorhynchocotyle sagamiensis n. sp. from Chimaera phantasma can be distinguished from all the known species of Callorhynchocotyle Suriano & Incorvaia, 1982 by the structure of the cirrus; in the new species, the cirrus is entirely muscular with a widened opening, while in the four known species it comprises a tubular proximal part and a bulbous distal part.

Animals↗
PubMed2006

Ap58: a novel in situ outer dynein arm-binding protein.

Outer arm dynein is a molecular motor that is positioned at 24 nm intervals on outer doublet microtubules in cilia and flagella. In the present paper, we report identification of a 58 kDa novel protein with a tetratricopeptide repeat (TPR), referred to as ap58 (for 58 kDa axonemal protein) in sea urchin sperm axonemes. Ap58 is extracted along with the outer arm dynein by a high salt solution from axonemes. Sucrose density gradient centrifugation or gel filtration of the extract separates the outer arm dynein core from ap58. Most ap58 sediments to the lower density fraction or elutes in fractions of smaller molecules. However, immunogold localization reveals that ap58 is distributed at approximately 25 nm intervals on doublet microtubules, suggesting that in situ it is associated with the outer dynein arm. Thus, ap58 with the TPR motif is a new member of outer dynein arm-binding proteins distinct from the outer dynein arm-docking complex.

Amino Acid Sequence↗
PubMed2006

Molecular characterization of Ciona sperm outer arm dynein reveals multiple components related to outer arm docking complex protein 2.

Using proteomic and immunochemical techniques, we have identified the light and intermediate chains (IC) of outer arm dynein from sperm axonemes of the ascidian Ciona intestinalis. Ciona outer arm dynein contains six light chains (LC) including a leucine-rich repeat protein, Tctex1- and Tctex2-related proteins, a protein similar to Drosophila roadblock and two components related to Chlamydomonas LC8. No LC with thioredoxin domains is included in Ciona outer arm dynein. Among the five ICs in Ciona, three are orthologs of those in sea urchin dynein: two are WD-repeat proteins and the third one, unique to metazoan sperm flagella, contains both thioredoxin and nucleoside diphosphate kinase modules. The remaining two Ciona ICs have extensive coiled coil structure and show sequence similarity to outer arm dynein docking complex protein 2 (DC2) that was first identified in Chlamydomonas flagella. We recently identified a third DC2-like protein with coiled coil structure, Ci-Axp66.0 that is also associated in substoichiometric amounts with Ciona outer arm dynein. In addition, Oda5p, a component of an additional complex required for assembly of outer arm dynein in Chlamydomonas flagella, also groups with this family of DC2-like proteins. Thus, the assembly of outer arm dynein onto doublet microtubules involves multiple coiled-coil proteins related to DC2.

Animals↗
PubMed2006

Association of a 66 kDa homolog of Chlamydomonas DC2, a subunit of the outer arm docking complex, with outer arm dynein of sperm flagella in the ascidian Ciona intestinalis.

We previously identified a 66 kDa axonemal protein (Ci-Axp66.0) in sperm of the ascidian Ciona intestinalis. Here we found that Ci-Axp66.0 shows sequence similarity to the DC2 subunit of the Chlamydomonas outer arm docking complex. Analysis of secondary structure of Ci-Axp66.0 suggested that the N-terminal two-thirds of the molecule is rich in coiled coil structure, as in Chlamydomonas DC2. Immunogold localization revealed that it is located in the vicinity of outer arm dynein. Ci-Axp66.0 was partly extracted from the axonemes by a high salt solution and co-purified with outer arm dynein. This co-purification was not affected by the absence of Mg(2+) in isolation buffer, indicating that Ci-Axp66.0 is associated with outer arm dynein. These results suggest that Ci-Axp66.0 is a component of the outer arm dynein docking complex in the axonemes of Ciona sperm.

Amino Acid Sequence↗
PubMed2005

Disease and health management in Asian aquaculture.

Asia contributes more than 90% to the world's aquaculture production. Like other farming systems, aquaculture is plagued with disease problems resulting from its intensification and commercialization. This paper describes the various factors, providing specific examples, which have contributed to the current disease problems faced by what is now the fastest growing food-producing sector globally. These include increased globalization of trade and markets; the intensification of fish-farming practices through the movement of broodstock, postlarvae, fry and fingerlings; the introduction of new species for aquaculture development; the expansion of the ornamental fish trade; the enhancement of marine and coastal areas through the stocking of aquatic animals raised in hatcheries; the unanticipated interactions between cultured and wild populations of aquatic animals; poor or lack of effective biosecurity measures; slow awareness on emerging diseases; the misunderstanding and misuse of specific pathogen free (SPF) stocks; climate change; other human-mediated movements of aquaculture commodities. Data on the socio-economic impacts of aquatic animal diseases are also presented, including estimates of losses in production, direct and indirect income and employment, market access or share of investment, and consumer confidence; food availability; industry failures. Examples of costs of investment in aquatic animal health-related activities, including national strategies, research, surveillance, control and other health management programmes are also provided. Finally, the strategies currently being implemented in the Asian region to deal with transboundary diseases affecting the aquaculture sector are highlighted. These include compliance with international codes, and development and implementation of regional guidelines and national aquatic animal health strategies; new diagnostic and therapeutic techniques and new information technology; new biosecurity measures including risk analysis, epidemiology, surveillance, reporting and planning for emergency response to epizootics; targeted research; institutional strengthening and manpower development (education, training and extension research and diagnostic services).

Animals↗
PubMed2005

First report of three protozoan parasites (a haplosporidian, Marteilia sp. and Marteilioides sp.) from the Manila clam, Venerupis (=Ruditapes) philippinarum in Japan.

Recently, natural stocks of the Manila clam, Venerupis (=Ruditapes) philippinarum, have been drastically reduced in Japan. To clarify the reason for this decline in number, clams were sampled monthly from Yamaguchi and processed for histological observations, during which three protozoan parasites were discovered. Transmission electron microscopy revealed that these parasites were unidentified haplosporidian in the connective tissues, Marteilia sp. in the digestive gland and Marteilioides sp. in the oocytes. Histopathological observations suggest that Marteilia sp. and Marteilioides sp. were not pathogenic to the host. However, infection with a haplosporidian may have a negative impact on the clams. The prevalence of these parasites was low and further investigations should be undertaken to clarify their taxonomic status and establish any pathogenicity to clams.

Animals↗
PubMed2005

Synthesis and structure-activity relationship of 4-substituted benzoic acids and their inhibitory effect on the biosynthesis of fatty acids and sterols.

The synthesis of 4-[3-(substituted phenyl)-2-oxo-5-oxazolidinyl]methoxybenzoic acids and their inhibitory effects on the biosynthesis of fatty acids and sterols is described. IC50 values in vitro were 10(-6) and 10(-5) M, respectively. Though the in vitro inhibitory activity of all these compounds toward sterol biosynthesis was inferior to that of pravastatin, several compounds had a stronger reducing effect in Sprague-Dawley (SD) rat on both, cholesterol (TC) and triglyceride (TG), than pravastatin and bezafibrate. The potent compounds were present at high concentrations in rat liver. The enantiomers of the potent racemic compounds (4-[3-(4-bromo-2-fluorophenyl)-2-oxo-5-oxazolidinyl]methoxybenzoic acid) were prepared and their activity was examined in vivo and in vitro. In vivo, each enantiomer possessed more activity than the racemic compound. Further, in Watanabe hereditable hyperlipidemic (WHHL) rabbit, optically active (R)-4-[3-(4-bromo-2-fluorophenyl)-2-oxo-5-oxazolidinyl]methoxybenzoic acid also potently reduced the effect of both TC and TG on serum levels, compared with pravastatin and bezafibrate.

Animals↗
PubMed2005

Removal of tightly bound ADP induces distinct structural changes of the two tryptophan-containing regions of the ncd motor domain.

ncd is a molecular motor belonging to the kinesin superfamily. In solution, it is a homo-dimer of a 700 amino acid polypeptide. The C-terminus of each polypeptide forms a globular domain of about 40 kDa, the motor domain with ATPase activity. The ATPase site of the motor domain of kinesin family members, including ncd, binds ADP tightly, the release of which is facilitated by microtubules during the mechanochemical ATPase cycle. Previously, we studied the spectroscopic characteristics of the ncd motor domain, focusing on interactions of the transition-moment-dipoles between ADP and aromatic amino acid side chains using circular dichroism (CD) spectroscopy. In the present study, we generated several ncd motor domain mutants. In each, a tryptophanyl or specific tyrosyl residue was mutated. We found that Trp370 and Tyr442, the latter of which stacks directly with the adenine moiety of bound ADP, caused the bound ADP to exhibit peculiar CD signals. In addition, fluorescence measurements revealed that Trp370, but not Trp473, was responsible for the emission intensity change depending on the presence or absence of bound ADP. This fluorescence result implies that the structural change induced at the ADP-binding site (on the release of the ADP) is transmitted to the region that includes Trp370, which is relatively close to the ADP-binding site but not in direct contact with the ADP-binding region. In contrast, Trp473 in the region that is in contact with the alpha-helical coiled coil stalk did not experience the structural changes caused on removal of ADP. The distinct behavior of these two tryptophanyl residues suggests that the ncd motor domain has a bifacial architecture made up of a relatively deformable side including the nucleotide binding site and a more rigid one.

Adenosine Diphosphate↗
PubMed2005

Expression patterns of plasma proteins in spontaneously diabetic rats after oral administration of a Kampo medicine, Hachimi-jio-gan, using SELDI ProteinChip platform.

We investigated the changes (increase or decrease in peak intensity) in the expression of plasma proteins in spontaneously diabetic WBN/Kob rats that were with complicated diabetic nephropathy, to determine multiple biomarkers in the plasma of diabetic rats. The present study using surface enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) demonstrated that six peaks at mass/charge ratios (m/z) of 4678, 4732, 4808, 9058, 9323, and 9465, among approximately 80 peaks per spectrum in the 2000-10000 Da mass range, had increased peak intensities with the development or progression of diabetic nephropathy in plasma of spontaneously diabetic WBN/Kob rats as compared with those of normal Wistar rats. Administration of the Kampo medicine Hachimi-jio-gan was effective at reducing the expression of diabetic nephropathy but not at reducing blood glucose levels. It also improved the increased levels of these plasma proteins. Other biomarker peaks at m/z 5067, 5279, 7598, and 7917 were not affected by Hachimi-jio-gan administration. Further study will be needed to identify these positive biomarkers and to evaluate the relationship between the efficacy and expression patterns of the plasma proteins in greater detail. The expression patterns of proteins and molecular-related ions revealed that several proteins in plasma may be involved in the development and/or progression of diabetic nephropathy in WBN/Kob rats and the efficacy of Hachimi-jio-gan. This study using ProteinChip technology may provide a useful basis in the search for multiple biomarkers in plasma for the diagnosis of disease and therapeutic evaluation of Kampo medicines.

Administration, Oral↗
PubMed2004

Near-infrared spectroscopy analysis of frontal lobe dysfunction in schizophrenia.

BACKGROUND: Previous studies have shown that near-infrared spectroscopy (NIRS) has high temporal resolution, requires little restraint, and is suitable for examining the effect of psychological tasks on brain circulation. In the present study, frontal function in schizophrenic patients was analyzed by NIRS during random number generation (RNG), ruler-catching (RC), and sequential finger-to-thumb (SFT) tasks. METHODS: Two sets of NIRS probes were attached to the foreheads of 13 schizophrenic patients and 10 control subjects approximately at Fp1-F7 and Fp2-F8. Near-infrared spectroscopy was conducted at a sampling rate of 1 Hz, with the pathlength being determined by time-resolved spectroscopy with differential pathlength factor measurements. The absolute changes in oxygenated (oxy-Hb) and deoxygenated (deoxy-Hb) hemoglobin concentrations in response to each task were measured, and total hemoglobin (total-Hb) concentration was calculated as the sum of the two. RESULTS: During RNG task, total- and oxy-Hb concentrations increased, and deoxy-Hb decreased, but the responses were significantly smaller in schizophrenic patients. During RC task, oxy-Hb in schizophrenic patients tended to decrease, in contrast to the mostly increasing response in control subjects. No group difference was observed during SFT task. CONCLUSIONS: Task-dependent profile of functional abnormalities was observed in schizophrenic frontal brain metabolism. These results support the usefulness of NIRS data in investigating frontal lobe dysfunction and evaluating psychopathologic condition in schizophrenic patients.

Acoustic Stimulation↗
PubMed2004

Early developmental stages of a protozoan parasite, Marteilioides chungmuensis (Paramyxea), the causative agent of the ovary enlargement disease in the Pacific oyster, Crassostrea gigas.

A paramyxea, Marteilioides chungmuensis, causes the irregular enlargement of the ovary in the Pacific oyster, Crassostrea gigas in Korea and Japan. The knowledge about the life cycle of the parasite has been limited to the sporulation stages within the oocyte of oysters. In this study, we used the parasite-specific DNA probes and electron microscopy to experimentally infected oysters in a field and successfully clarified early developmental stages of the parasite. The parasite invaded the oysters through the epithelial tissues of the gills, mantle and labial palps. Extrasporogony repeatedly occurred in the connective tissues by binary fusion. The inner cell of the extrasporogonic stage migrated into the gonadal epithelium, invaded the oocyte to start sporulation.

Animals↗
PubMed2004

Two species of parasitic copepods (Caligidae) new to Japan.

Two species of parasitic copepods (Siphonostomatoida: Caligidae), Caligus sclerotinosus Roubal, Armitage & Rohde, 1983, parasitic on red seabream Pagrus major (Temminck & Schlegel), and Lepeophtheirus longiventralis Yü & Wu, 1932, parasitic on spotted halibut Verasper variegatus (Temminck & Schlegel), are redescribed based on material found on their respective hosts cultured in Japan. Both species are new to Japan. Preliminary observation on the occurrence of L. longiventralis indicates that the larval development takes place on the body surface of the host and only the post-mated female migrates into the host's gill-cavities. Whilst the occurrence of L. longiventralis in Japan can be considered as due to natural causes, the occurrence of C. sclerotinosus is likely due to anthropogenic activities.

Animals↗
PubMed2004

A microsporidian parasite of the genus Spraguea in the nervous tissues of the Japanese anglerfish Lophius litulon.

In the present study, a high percentage of Japanese anglerfish, Lophius litulon (Jordan, 1902), contained a microsporidian infection of the nervous tissues. Xenomas were removed and prepared for standard wax histology and transmission electron microscopy (TEM). DNA extractions were performed on parasite spores and used in PCR and sequencing reactions. Fresh spores measured 3.4 x 1.8 microm and were uniform in size with no dimorphism observed. TEM confirmed that only a single developmental cycle and a single spore form were present. Small subunit (SSU) rDNA sequences were >99.5% similar to those of Spraguea lophii (Doflein, 1898) and Glugea americanus (Takvorian et Cali, 1986) from the European and American Lophius spp. respectively. The microsporidian from the nervous tissue of L. litulon undoubtedly belongs in the genus Spraguea Sprague et Vivra, 1976 and the authors suggest a revision to the generic description of Spraguea to include monomorphic forms and the transfer of Glugea americanus to Spraguea americana comb. n. Since no major differences in ultrastructure or SSU rDNA sequence data exist between Spraguea americana and the microsporidian from the Japanese anglerfish, they evidently belong to the same species. This report of Spraguea americana is the first report of a Spraguea species from L. litulon and indeed from the Pacific water mass.

Animals↗
PubMed2003

Sperm motility-activating complex formed by t-complex distorters.

Transmission ratio distortion is a dramatic example of non-Mendelian transmission. In mice, t-haplotype males produce dysfunctional +-sperm and normal t-sperm, leading to transmission in favor of t-sperm. Genetic studies have indicated that the t-complex responder locus, Tcr, rescues t-sperm but not +-sperm from defective products of t-complex distorter loci, Tcds. Light chain 1 (LC1) and LC3 from sea urchin sperm outer arm dynein have sequence similarities to Tctex2 and Tctex1, respectively, both of which are wild-type products of Tcds. We show here that LC1 and LC3 are able to make a 1:1 complex. Since Tcr is a member of the Smok (sperm motility kinase) family and LC1 is phosphorylated at the activation of sperm motility in a cAMP-dependent manner, this complex in a dynein motor molecule might be a direct target of Smok/Tcr kinase in a signal cascade that regulates sperm motility. Thus, we designate it as Smoac (sperm motility activating complex).

Amino Acid Sequence↗
PubMed2003

Isolation and 18S ribosomal DNA gene sequences of Marteilioides chungmuensis (Paramyxea), an ovarian parasite of the Pacific oyster Crassostrea gigas.

To develop sensitive detection techniques with the aim of elucidating the life cycle of Marteilioides chungmuensis, an intracellular paramyxean infecting the ovary of the Pacific oyster Crassostrea gigas, we isolated the parasite at the sporont stage from infected oysters using a freeze-thaw procedure at -20 degrees C and differential centrifugations in discontinuous sucrose and Percoll gradients. DNA was extracted from the isolated sporonts, and a PCR amplicon of 18S small subunit ribosomal RNA gene DNA was partially sequenced. In situ hybridization using 3 parasite-specific probes designed from the obtained sequence successfully detected parasite cells in infected oysters, and confirmed that the sequenced DNA was derived from M. chungmuensis.

Animals↗
PubMed2003

Description of two new actinosporean types from a brook of Fuji Mountain, Honshu, and from Chitose River, Hokkaido, Japan.

Actinospore infection of oligochaetes living in the mud of 3 freshwater biotopes in Japan was studied. Using the cell-well plate method, a new aurantiactinomyxon type was found in 0.77% of the examined Tubifex tubifex oligochaete specimens from a brook near Yamanashi Prefectural Fisheries Experimental Station on Fuji Mountain. In 0.14% of Lumbriculus variagetus collected from Chitose River, near Chitose Salmon Hatchery, a new siedleckiella type was found, while at the same time 8.1% of the Lumbriculus spp. oligochaetes released triactinomyxons of Myxobolus arcticus. Of the examined Rhyacodrilus komarovi oligochaetes collected from the Mena River system, Hokkaido, 0.2, 0.6, 0.5 and 0.8% were infected with echinactinomyxon, neoactinomyxum and 2 types of triactinomyxon spores, respectively, and described in our previous paper. The oligochaetes released actinospores for several weeks. Actinospore infection showed high intensity in positive oligochaetes in the case of all the actinosporean types. Two of the actinospore types (aurantiactinomyxon and siedleckiella) presented here have not been previously described.

Animals↗