Eukaryotic communities associated with the decomposition of rice straw compost in a Japanese rice paddy field estimated by DGGE analysis

To estimate the succession and phylogenetic composition of the eukaryotic communities responsible for the decomposition of rice straw compost under flooded conditions during the cultivation period of paddy rice, denaturing gradient gel electrophoresis (DGGE) analysis targeting 18S rDNA followed by sequencing was conducted in a Japanese paddy field. The eukaryotic communities in rice straw compost incorporated into the flooded paddy field were influenced by the mid-season drainage and mainly composed of fungi (Ascomycota, Zygomycota, and Chytridiomycota) and protozoa (Ciliophora, Euglyphida, and Dactylopodida), most of which existed continuously during the cultivation period of paddy rice. The results indicated that these eukaryotic members were associated with the decomposition of rice straw compost in paddy field soil directly or indirectly.     

Uptake by dietary exposure and elimination of aflatoxins in muscle and liver of rainbow trout (Oncorhynchus mykiss)

Uptake and elimination of aflatoxins (AFs) by rainbow trout ( Oncorhynchus mykiss ) during a long-term (21 days) dietary exposure were studied to assess contamination by AFs in aquaculture fish fed AF-containing feed. The uptake factor (UF) of aflatoxin B(1) (AFB(1)) in muscle ranged from 0.40 × 10(-3) to 1.30 × 10(-3). AFB(1) concentrations in liver were 165-342 times higher than in muscle. AFs from feed were more highly accumulated in liver than in muscle. Aflatoxicol (AFL) and aflatoxin M(1) (AFM(1)) were detected in muscle and liver and also in the rearing water. AFL concentrations were higher than AFM(1) by 2 orders of magnitude in muscle, and AFL was a major metabolite of AFB(1). The elimination rate constants (α) of AFB(1) and AFL in muscle (1.83 and 2.02 day(-1), respectively) and liver (1.38 and 2.41 day(-1), respectively) were very large. The elimination half-life (t(1/2)) of AFB(1) was 0.38 days (9.12 h) in muscle and 0.50 days (12.00 h) in liver. The elimination half-life of AFL in muscle and liver was 0.34 day (8.16 h) and 0.29 day (6.96 h), respectively. These data show that AFs are eliminated rapidly and are not biomagnified in fish. Thus, AFB(1) concentration in muscle of fish fed AFB(1)-containing feed (ca. 500 μg/kg) decreased to below the detection limit (20 ng/kg) of the most sensitive analytical method at 1.54 days (36.96 h) after the change to uncontaminated feed.     

The relationship between the size of caudolateral curvilinear osteophyte of the canine femoral neck and the radiographic view

Caudolateral curvilinear osteophyte (CCO), an osteophyte at the site of joint capsule attachment on the caudal aspect of the femoral neck, has been advocated as a radiographic criterion for coxofemoral subluxation. The correlation between the presence of CCO on radiographs (radiographic-CCO), the size of the CCO (CCO index) on three-dimensional computed tomographic (CT) images, and hip evaluation using transverse CT images was assessed in 22 Border Collies. CCOs were detected on the radiographs and CT images of 32% and 100% femurs, respectively. The CCO index correlated significantly with radiographic-CCO, but a large CCO index did not necessarily imply that the CCO was visible on radiographs. Hence, radiographic-CCO findings should be used cautiously in hip evaluation of Border Collies.     

Relationship between the glass transition of soy protein and molecular structure

The change in molecular structure of the soy protein samples as a result of the microbial transglutaminase treatment was studied using solid-state (13)C NMR spectroscopy and circular dichroism (CD), and the relation to the glass transition temperature (T(g)) was examined. From NMR measurements, the structure of the local region of the C(alpha) methine was observed to change, and the region had relatively high mobility. From CD measurements, the structural change seemed to be caused by the change in the secondary structure (disintegration of the beta-structure). By comparison with the T(g) of another protein, the state of the secondary structure of a protein was suggested to be a key in determining its T(g).     

Virtopsy in a red kangaroo with oral osteomyelitis

This report describes the use of computed tomography (CT) in a nondomestic species. Postmortem CT was performed on a red kangaroo (Macropus rufus) and a diagnosis of oral osteomyelitis was made. CT examination revealed bony remodeling of the right mandible, an intraosseous lesion of the right temporal bone, muscle necrosis around the right mandible, and the absence of the right, first, upper molar tooth. Cardiac and intrahepatic gas and a distended intestine due to postmortem gas accumulation were also seen. All the lesions identified with CT were also identified by conventional necropsy, except the cardiac and intrahepatic gases. Virtopsy may be a useful procedure for the noninvasive identification of cause of death and as a guide for necropsy in animals.     

Nutrient leaching from the plow layer by water percolation and accumulation in the subsoil in an irrigated paddy field

To estimate the impact of water percolation on the nutrient status in paddy fields, the seasonal variations of the concentrations of cations, anions, inorganic carbon (IC), and of dissolved organic carbon (DOC) in percolating water that was collected from just below the plow layer (PW-13) and from drainage pipes at the 40 em depth (PW-40), as well as in irrigation water were measured in an irrigated paddy field. Total amounts of Ca, Mg, K, Fe, and Mn leached from PW-13 during the period of rice cultivation were estimated to range from about 390 to 770, 65 to 130, 33 to 66, 340 to 680, and 44 to 87 kg ha^-1, respectively. Amounts of losses that were estimated from the differences between the input by irrigation water and the output by percolation water from the plow layer corresponded to 11 to 26, 22 to 47,5.9 to 12, and 13 to 26% of exchangeable Ca and Mg, amorphous Fe, and easily reducible Mn in the plow layer, respectively. The concentrations of Ca, Mg, K, Fe, and Mn in PW13 were higher than those in PW-40. The amounts of these nutrients that were retained in the subsoil between the 13 em and 40 em soil depth corresponded to 83, 86, 61, 99, and 89% of the amounts that percolated from the plow layer, respectively. Total amounts of IC and DOC that percolated from the plow layer ranged from 750 to 1,500 and 85 to 170 kg-C ha^-1, which corresponded to 5.0 to 10.0% and 0.6 to 1.1% of the total carbon content in the plow layer, respectively. Eighty eight % of IC in the percolating water from the plow layer was also retained in the subsoil.     

Effects of complete submergence on seedling growth and survival of five riparian tree species in the warm-temperate regions of Japan

To reveal the relationship between tolerance to submergence and the distribution ranges of riparian tree species in the floodplains of the warm-temperate regions in Japan, we assessed the response and tolerance of current-year seedlings of two Salix and three Ulmaceae species to submergence treatments for 1, 2, 4, and 8 weeks. We investigated shoot elongation, number of leaves, and survival rate of seedlings during the experiment, and biomass allocation was determined at the end of the experiment. Shoot elongation and leaf production of seedlings were suppressed in all the species during the submergence treatments. However, the seedlings of Salix chaenomeloides and S. pierotii elongated shoots rapidly and produced leaves after the treatments. All the underground biomass in these two species was larger than aboveground biomass. These results are considered as typical responses of flood-tolerant species. In contrast, the underground biomass of Ulmaceae seedlings (Celtis sinensis var. japonica, Aphananthe aspera, and Ulmus parvifolia) decreased more rapidly than aboveground biomass during prolonged submergence. Furthermore, A. aspera seedlings also showed suppression of shoot elongation and leaf production after the treatments. Our results indicate that the three Ulmaceae species are less tolerant to submergence than the two Salix species. In conclusion, we suggest that submergence stress is one of the important factors determining the distribution of tree species in the floodplains of lowlands in the warm-temperate regions of Japan.     

Humeral Chondrosarcoma in a Hokkaido Brown Bear (Ursus arctos yesoensis)

Humeral chondrosarcoma was found in an 18-year-old male Hokkaido brown bear (Ursus arctos yesoensis). Necropsy revealed a large firm mass under the left superficial pectoral muscle at the axillary region. The mass involved the left shoulder joint and peripheral muscles, and connected to the head of the humerus with osteolysis. Histopathologically, the mass was composed of irregularly shaped myxomatous to cartilaginous tumor lobules. The tumor cell showed moderate nuclear atypia with a relatively high mitotic index, especially in the edges of the myxomatous lobules. The tumor cells were positively immunostained with vimentin and S-100 protein. Based on these findings, the tumors were diagnosed as chondrosarcoma. Metastases were found in the left axillary lymph node, lungs, liver and kidney.     

Anatomical and histological characterization of ileal and jejunal Peyer's patch in lesser mouse deer (Tragulus javanicus)

Tragulidae is a primitive ungulate family within the order Cetartiodactyla, suborder Ruminantia. Domestic ruminants such as cattle, sheep, and goat have two types of Peyer's patches (PP): jejunal and ileal PP, in which there are morphological and functional differences. In this study, lesser mouse deer (Tragulus javanicus) PP was studied by gross anatomical and histological procedures. At the fetal stage, both types of PP were formed in the small intestine. Ileal PP was observed as a single continuous aggregation of lymphatic follicles extending cranially from the ileo-caecal junction. However, jejunal PP was observed as multiple and discrete accumulations of lymphatic follicles. This study showed that the lesser mouse deer has two types of PP in the small intestine. In addition, the anatomical and histological characteristics of jejunal and ileal PP are quite similar to those of other ruminants' jejunal and ileal PP. Further studies are needed to analyze immune function of both PP in lesser mouse deer in order to determine the evolutionary process of Cetartiodactyla.     

Geographical variation of skull morphology and its functional significances in the red-cheeked squirrel

Skulls of the red-cheeked squirrel (Dremomys rufigenis) from various geographical locations: Malaysia (peninsular area), Vietnam (south district)-Laos, and Thailand (north district) were osteometrically examined. The skull size of the squirrels in the southern (Malaysia) population was fundamentally larger than that in the northern (Vietnam, Laos and Thailand) populations. The proportion indices indicated that the splanchnocranium was relatively longer in the Malaysia population, and that the interorbital space was narrower in Vietnam-Laos, and Thailand populations. We suggest that the long nose and laterally-oriented orbits in the skull may be better adapted for terrestrial-insectivorous life in the Malaysia population and the binocular sense facilitated by rostrally-oriented eyes contributes to the arboreal-fruit eating behavior in the two northern populations. The Malaysia population was clearly distinguished from the other populations by the principal component analysis. We suggest that the geographical barrier of the Isthmus of Kra influences the morphological variation of the skull among the squirrel populations.