Feeding habits of stone flounder <Emphasis Type="Italic">Platichthys bicoloratus</Emphasis> larvae in Mutsu Bay,Japan

To clarify the feeding strategy of pelagic larvae of stone flounder in Mutsu Bay, the dietary composition and pray size was investigated from February to April during 1989–1999. Diets were compared with the numerical and volumetric compositions and frequency of occurrence of each prey species. Mensuration formulae were applied to estimate individual prey volume in the diet, while the length of planktonic species was measured from net and water samples. Prey shapes were assumed as sphere, cylinder, ellipsoid, pyramid, two elliptical cones, or a combination of ellipsoid and cylinder. Prey-size range increased as the larvae grew. Preflexion larvae fed mainly on copepod nauplii. Flexion and postflexion larvae ingested primarily appendicularians, with a suggestion that these larvae might depend on some parts of the microbial food web. Low frequencies of flexion and postflexion larvae with empty guts (1.7 and 1.4%, respectively) might be derived from feeding on slow-swimming appendicularians. From a size comparison between ‘house’-like organ length and trunk length of the appendicularian Oikopleura sp., almost all house-like organs with trunks in the larval diet were nonexpanded ‘house rudiments’, not expanded ‘houses’. Thus, stone flounder larvae may not chew the houses, but swallow the house rudiments with trunks.     

Effect of grain direction on transmittance of 100-GHz millimeter wave for hinoki (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>)

The attenuation coefficients of 100-GHz millimeter waves polarized linearly were measured for cross-cut, quarter-sawn, and flat-sawn boards of hinoki (Chamaecyparis obtusa) that were 0.2–2.0 cm thick. This was done to examine the applicability of free-wave propagation theory for applying electromagnetic waves to wood. It was found that the transmittance of a millimeter wave through the specimen boards was lower when the fiber direction of a board was parallel to the direction of the electric field of the incident wave than when the fiber direction was perpendicular to the electric field, and there was little difference in the transmittance between the tangential and radial directions for the former case. These findings can be quantitatively explained by using propagation theory and the dielectric properties of wood.     

Host immune-related gene responses against highly pathogenic avian influenza virus infection in vitro differ among chicken cell lines established from different organs

Highly pathogenic avian influenza virus (HPAIV) induces acute disease in chickens causing high mortality and morbidity and is a major threat to poultry industries in Southeast Asian countries. The mechanisms of disease manifestation and host innate immune responses against HAPIV in chickens are not well understood. In this study, we examined virus replication and host gene expressions in four chicken cell lines in vitro to elucidate the impact of host innate immune responses against viral replication. It was demonstrated that viral replication efficiencies were different depending on the cell line. The viral replication appeared to be affected by the basal expression of IFN related genes. The expression of immune-related genes against the viral infection also varied in a cell line dependent manner. In non-immune derived cell lines, but not in immune derived cell lines, the expression of the CCL5 and CCL20 genes were induced by HPAIV infection. Reverse genetics HPAIV, with internal genes from avirulent avian influenza, reduced virus replication and affected immune-related gene expression in a cell line dependent manner. These results suggest the possibility that differential immune responses in different cell types in local tissues could modulate the consequences of HPAIV infection in chickens.     

An H5N1 highly pathogenic avian influenza virus that invaded Japan through waterfowl migration

In 2010, an H5N1 highly pathogenic avian influenza virus (HPAIV) was isolated from feces of apparently healthy ducks migrating southward in Hokkaido, the northernmost prefecture of Japan. The H5N1 HPAIVs were subsequently detected in domestic and wild birds at multiple sites corresponding to the flyway of the waterfowl having stopovers in the Japanese archipelago. The Hokkaido isolate was genetically nearly identical to H5N1 HPAIVs isolated from swans in the spring of 2009 and 2010 in Mongolia, but less pathogenic in experimentally infected ducks than the 2009 Mongolian isolate. These findings suggest that H5N1 HPAIVs with relatively mild pathogenicity might be selected and harbored in the waterfowl population during the 2009-2010 migration seasons. Our data provide "early warning" signals for preparedness against the unprecedented situation in which the waterfowl reservoirs serve as perpetual sources and disseminators of HPAIVs.     

Multiplex PCR and Genescan analysis to detect immunoglobulin heavy chain gene rearrangement in feline B-cell neoplasms

Lymphoid neoplasms are usually diagnosed on the basis of cytological and histopathological findings. However, in some cases, discrimination of lymphoid neoplasms from reactive lymphoid proliferation is difficult. PCR amplification of complementarity-determining region 3 (CDR3) of the immunoglobulin heavy-chain variable region (IGHV) gene can be used to assess clonality of B-cell populations as a supportive diagnostic tool for B-cell neoplasms. Because of the sequence variation and possible somatic hypermutation of the IGHV gene, sensitivity of the PCR-based assay to detect clonal IGHV gene rearrangement largely depends on the sequences and numbers of primer sets. Prior to the development of an efficient assay, we cloned and sequenced 97 IGHV complementary DNAs (48 IGHV-1 and 49 IGHV-3 clones) from normal cat spleens. On the basis of these sequences, we designed 6 forward primers at the variable region and 5 reverse primers at the joining region. Using each of 6 forward primers and a mixture of 5 reverse primers, we amplified CDR3 of IGHV genes and analyzed the PCR products by conventional PAGE and Genescan analyses using fluorescence-labeled primers. Twenty-six feline B-cell neoplasms diagnosed by histopathological and immunohistochemical examinations were subjected to the newly developed analysis of IGHV gene rearrangement. Clonal IGHV gene rearrangement was detected in 22 of 26 (84%) samples by both PAGE and Genescan analyses. To reduce the number of PCR reactions, we constructed a multiplex PCR analysis system using a mixture of IGHV-1- and IGHV-3-specific primers as forward primers and a mixture of 5 joining region reverse primers. Results of the multiplex PCR were 100% concordant with those obtained by each of the singleplex PCRs. The multiplex PCR-based assay and Genescan analysis developed in the present study would be useful and practical tools to detect clonal IGHV gene rearrangement in feline B-cell neoplasms.     

Prevalence of Dirofilaria immitis infection in living raccoon dogs assessed by hematological examination

The prevalence of Dirofilaria immitis in free-ranging raccoon dogs (Nyctereutes procyonoides viverrinus) was examined in the southeast region of Kanagawa Prefecture, Japan, using a rapid immunomigration (RIM) test kit. Between April 2007 and March 2010, we examined 108 raccoon dogs rescued and housed by the Kanazawa Zoological Garden. D. immitis infection was found in 8 (7.4%) raccoon dogs. This is the first report to reveal the prevalence of D. immitis infection in living raccoon dogs. The prevalence of the infection was lower than previously reported values obtained on postmortem examination. One reason might be that the present study included young raccoon dogs infected with immature worms. Significant high-risk areas of D. immitis infection in the raccoon dogs were not observed.     

A rapid and simple method to obtain canine peripheral blood-derived macrophages

Macrophages play an important role in a variety of situations, including pathogen elimination, inflammation, and tissue repair. However, these cells are not fully studied in dogs, in part, due to the difficulty of efficiently isolating and culturing them in vitro. In this study, we cultured canine peripheral blood mononuclear cells (PBMCs) with 10 ng/ml of phorbol 12-myristate-13-acetate (PMA) for 5 days to obtain macrophages. A high number of round-adherent cells were obtained without the addition of any cytokine. These cells showed active phagocytic activity and a cell surface antigen profile different from dendritic cells. Our method facilitates a high yield of macrophages in a short cultivation period compared with previous studies. This method might be a powerful tool to study macrophage functions in dogs.     

Cutaneous lymphoplasmacytic lymphoma with systemic metastasis in a cat

A lymphoplasmacytic lymphoma was diagnosed in a 12- year-old domestic cat that had a primary cutaneous mass involving the stomach, liver, kidneys, heart, abdominal wall, diaphragm, bone marrow and several lymph nodes. Histopathologically, the most characteristic feature of this tumor was the heterogeneity of cell components, such as small lymphocytes, well-differentiated plasma cells and plasmacytoid transformed lymphocytes. Amyloid was deposited in the skin, stomach, and several lymph nodes. Immunohistochemically, neoplastic small lymphocytes were positive for CD20, and well-differentiated plasma cells and plasmacytoid transformed lymphocytes were positive for λ-Ig light chains and MUM1/IRF-4. These results emphasize the importance of lymphoplasmacytic lymphoma as a differential diagnosis of extramedullary cutaneous plasmacytoma in cats.