Relation between pathogenicity and genetic variation within <Emphasis Type="Italic">Plasmodiophora brassicae</Emphasis>

The relation between diversity of pathogenicity on clubroot-resistant (CR) cultivars of Chinese cabbage (Brassica rapa subsp. pekinensis) bred in Japan and DNA polymorphisms in 17 populations of Plasmodiophora brassicae from cruciferous plants was examined by inoculation tests and random amplified polymorphic DNA (RAPD) analysis using 18 arbitrary primers. Four pathotypes (A–D) were identified after inoculation of six CR cultivars of Chinese cabbage in the 17 populations from cruciferous crops. A relatively high level of genetic diversity was also detected among these populations in the RAPD analysis. Although the four pathotypes could not be clearly differentiated using the RAPD data, most populations of three pathotypes had a consistent location on the dendrogram. All pathotype B (virulent on five cultivars except Utage 70) and D (avirulent on all cultivars) populations, which were common in incompatible interactions with cv. Utage 70, were located in a single subcluster. All five pathotype C populations (virulent only on cv. Utage 70) except for one population grouped in another single subcluster. Because four pathotype A populations (virulent on all six cultivars, races 4 and 9) fell in different subclusters, the populations may be genetically polyphyletic. Populations from cruciferous weed Cardamine flexuosa differed remarkably from those from cruciferous crops in pathogenicity on common cultivars of Chinese cabbage and turnip and C. flexuosa, but they grouped in a single cluster with all race 9 populations from crops. Race 9 populations from crops may thus be closely related to populations from the weed rather than to races 1 and 4 from crops.     

Culture method and growth characteristics of marine benthic dinoflagellate Ostreopsis spp. isolated from Japanese coastal waters

Blooms of toxic dinoflagellates of the genus Ostreopsis, which is known as a producer of palytoxin (PTX) analogs, may pose a threat to human health in tropical, subtropical, and temperate regions around the world. In the present study, we established a suitable culture method for Ostreopsis spp. isolated from Japanese coastal waters and characterized their growth potential using the method to discuss their bloom dynamics. Each clonal strain of Ostreopsis cf. ovata, Ostreopsis sp.?1, Ostreopsis sp.?5, and Ostreopsis sp.?6 was incubated in 25?×?150?mm test tubes with a flat bottom containing various kinds of medium. Since Ostreopsis spp. strains grew well in IMK and/or f/2 media, we selected these media for cultivation of all the Ostreopsis spp. isolates. Growth rates of O. cf. ovata (0.834?divisions/day), Ostreopsis sp.?1 (0.619?divisions/day), and Ostreopsis sp.?6 (1.04?divisions/day) that produce PTX analogs significantly differed (p?<?0.05) respectively and are clearly higher than those of other reported epiphytic dinoflagellate Gambierdiscus toxicus, Prorocentrum lima, and Coolia monotis cultures, which suggest that these species have ecological advantages to predominate through the algal succession in Japanese coastal waters, resulting in a potential risk to human health in this region.     

Fecal progestagens to detect and monitor pregnancy in captive female cheetahs (Acinonyx jubatus)

The purposes of the present study were to establish a noninvasive monitoring assay of fecal progestagen measurement to detect pregnancy and to identify the components of fecal progestagens in early, middle and late pregnancy in cheetahs. Feces were collected from 7 female cheetahs and analyzed from 30 days before the last copulation to parturition in 9 pregnancies. Blood was collected from one cheetah. Fecal progestagen and serum progesterone concentrations were determined by enzyme immunoassay (EIA). The profiles of the fecal progestagen concentrations were similar to the serum progesterone profile. Fecal progestagen and serum progesterone concentrations remained at the baseline until copulation. In the mean fecal progestagen profile during pregnancy (92.8 ± 0.4 days; from the last copulation to parturition), the concentrations increased 3-4 days after the last copulation and remained high until parturition. To investigate changes in the components of progestagen metabolites in the tripartite periods of gestation, fecal progestagens were analyzed by HPLC-EIA. Marked immunoreactive peaks consistent with 5α-pregnan-3α/β-ol-20-one and 5α-pregnan-3,20-dione and small peaks consistent with 5β-pregnan-3α/β-ol-20-one were detected. There were no distinct difference in the components of progestagens among the first, second and third trimesters of pregnancy. The hormone assay, as an indicator of fecal 5α-reduced pregnanes, is useful for detecting pregnancy and monitoring pregnant luteal activity in cheetahs.     

Effect of application of rice straw and cellulose on methane emission and biological nitrogen fixation in a subtropical paddy field

Methane-oxidizing bacteria (MOB, methanotrophs) limit the flux of methane to the atmosphere from sediments and soils, and consume atmospheric methane (King 1992; Oremland and Culbertson 1992). IPCC (1995) reported that an aerobic soil is equivalent to a sink of 10–20% of methane emissions. Hence MOB play an important role in regulating the atmospheric methane content (Mancinelli 1995). Over the last 20y, although a large amount of information has been supplied on the biochemistry of MOB, few ecological investigations have been devoted to them so far (Holzapfel-Pschorn et al. 1985; Oremland and Culbertson 1992).     

Promotive and inhibitory effects of rice straw and cellulose application on rice plant growth in pot and field experiments

Abstract

Quantitative characterization of crusts is necessary to evaluate the crusting susceptibility of soils, to reveal the soil properties affecting soil crust development and, thus, to predict the occurrence of crusting. For the quantification of the morphological characteristics of soil surface crusts, the authors applied an image analyzing method to quantify the state of pores, in terms of apparent porosity, using vertical thin sections of the surface crust formed under simulated rainfall.     

Effect of presowing seed treatments on germination and early seedling growth of wheat varieties under saline conditions

The effect of presowing wheat seed treatments was investigated for the salt-sensitive variety Blue Silver and relatively salt-tolerant variety PARI-73 at the germination and early seedling stages. Seeds were treated with distilled water (DW) or 10/50 mm KCl, KNO₃ , CaCl₂, Ca(NO₃)₂ and then germinated in DW or 200 mm NaCl. Treatment with calcium (Ca) or potassium (K) did not lead to a significantly higher rate for final germination than the DW treatment. Ca salt treatments significantly improved shoot growth during the early seedling establishment stage in both varieties, especially in the salt-sensitive variety Blue Silver. There were significant differences in the Ca content of seeds after various presowing treatments. There were also significant differences between both varieties in the ion contents after seed treatment. However, these differences appeared to be related to the improvement of shoot growth during the early seedling establishment stage and not to the effectiveness of pres owing seed treatments in increasing germination.     

Effect of boiled barley-rice-feeding in hypercholesterolemic and normolipemic subjects

Barley contains approximately 10% dietary fiber and is easily cooked with rice, the dominant cereal in Japan, to increase the intake of dietary fiber. This research involved three experiments to examine the influence of barley on blood lipids in human subjects. All subjects received a boiled barley-rice (50/50 w/w mix) supplement two times per day in place of rice for 2 or 4 weeks. In the normolipemic subjects, serum lipids were unaffected by the ingestion of barley for 4 weeks. In twenty hypercholesterolemic men aged 41 ± 5 years, the ingestion of barley was associated with a significant fall in serum total cholesterol, LDL-cholesterol, phospholipids and LDL and VLDL-lipoproteins. In seven mildly hypercholesterolemic women aged 56±7 years, a significant improvement of serum lipid profiles was observed. The present study suggests the possibility that the ingestion of barley-rice could lower serum lipids in hypercholesterolemic subjects.     

Anatomical characterization of decayed wood in standing light red meranti and identification of the fungi isolated from the decayed area

To further our understanding of wood decay in living light red meranti (Shorea smithiana) trees, microscopic characteristics of the cell and cell wall degradations of S. smithiana wood in the presence of the decay fungi, the identity of the causal fungi, and the decay potential and pattern by an isolated fungus were investigated. Cell wall degradations, including cell wall thinning, bore holes formation, rounded pit erosion, and eroded channel opening were clearly observed under light and scanning electron microscopy. In transverse view, many large voids resulting from a coalition of degraded wood tissue appeared in the decayed canker zone. All these observations suggest the well-known simultaneous decay pattern caused by white-rot fungi. By phylogenetic analysis based on the sequences of internal transcribed spacer region of ribosomal DNA, a basidiomycete fungus isolated from the decayed wood was identified as Schizophyllum commune. The degradation caused by this fungus on sound S. smithiana wood in an in situ laboratory decay test was classified as the early stage of simultaneous decay, and showed a similar pattern to that observed in the wood samples naturally decayed.     

Detection of Thiophanate-methyl-resistant Strains in Diplocarpon mail, Causal Fungus of Apple Blotch

Isolates of Diplocarpon mali, causal fungus of apple blotch, collected from four prefectures in Japan in 1997–1998 were tested for sensitivity to thiophanate-methyl. Results from mycelial growth tests showed that MIC values of the fungicide were 0.19 μg/ml against all isolates from Akita, Nagano and Saga prefectures but 100 or 200 μg/ml against all isolates from the Tokusa area in Yamaguchi prefecture. Detached apple leaves sprayed with the fungicide developed severe symptoms when inoculated with the isolate from Tokusa, but developed no symptoms with the isolate from Nagano. These results are the first confirmation of thiophanate-methyl-resistant strains in D. mali. Received 1 September 1999/ Accepted in revised form 15 October 1999     

Changes in anti-erythrocyte membrane antibody level of dogs experimentally infected with Babesia gibsoni.

To account for the conflict between the excessive destruction of erythrocytes and the number of parasitized erythrocytes in dogs infected with Babesia gibsoni, we examined the correlation between anti-erythrocyte membrane antibody level (AEMAL) and the number of erythrocytes (RBC count) in dogs with experimentally induced babesiosis using hematological examination and an enzyme linked immunosorbent assay (ELISA). In the infected dogs without splenectomy, more prominent reduction in RBC count accompanied with the elevated AEMAL was presented than anticipated from parasitemia until the 21st day. Furthermore, autoagglutinated erythrocytes and spherocytes were demonstrated in blood films. These results suggest that a humoral immunologic mechanism may be involved in a decrease in RBC count in dogs infected with B. gibsoni.