Effects of Latent Infection of Stock Plants and Abundance of Thrips on the Occurrence of <Emphasis Type="Italic">Tomato spotted wilt virus </Emphasis>in Chrysanthemum Fields

DAS-ELISA proved to be reliable enough to detect a latent infection by Tomato spotted wilt virus (TSWV) in asymptomatic stock plants of chrysanthemum. A high density of Frankliniella occidentalis, the predominant vector, in the presence of latently infected stock plants resulted in a high incidence of disease in the chrysanthemum production field. The incidence of disease was low when the vector thrips were not abundant in spite of the presence of latently infected stock plants. These results suggest that an infestation of the vector thrips causes severe secondary spread of TSWV originating from latently infected stock plants in chrysanthemum production fields. Received 27 July 2001/ Accepted in revised form 27 November 2001     

Strong antiviral activity of heated and hydrated dolomite--preliminary investigation

Heated and hydrated naturally occurring dolomite showed very strong antiviral activity. Infectivity of avian and human influenza, avian infectious bronchitis (coronavirus), Newcastle disease (paramyxovirus) and avian laryngotracheitis (herpesvirus) viruses dropped at least 1,000 fold following contact with the dolomite for five minutes at 4 degrees C. Dolomite is expected to be useful to inhibit the incidence of emerging and re-emerging infectious diseases.     

Estimation of daily urinary potassium excretion using urinary creatinine as an index substance in prepartum dairy cows

In the present study, the daily excretion of potassium (K) in urine (urinary K(UK)) was estimated from a 6 h urine sample using urinary creatinine (UC) as the index substance. All urine was collected from six pregnant Holstein cows at 6 h intervals for 24 h on 3 days of the 4th, 2nd and final week before the expected date of parturition. In total, 72 6 h urine samples were obtained. Daily UC excretion (mg/day per kg bodyweight (BW)) was almost the same for the three sampling days. Daily UC excretion varied among cows from 22.1 to 24.3 mg/day per kg BW with a mean of 22.8 mg/day per kg BW with no significant difference. Thus, daily UC excretion was confirmed to be constant throughout the prepartum period with no differences among individuals. The concentration ratios of K to creatinine ((UK mg/dL)/(UC mg/dL) (UK/UC)) correlated strongly to the hourly K excretions (mg/h per kg BW) (r = 0.952, P < 0.01) in the 6 h urine samples. The differences in the UK/UC ratio between sampling periods were not significant within each cow. Therefore, daily UK excretion (mg/day) can be estimated using the equation: daily UK excretion (mg/day) = daily UC excretion (mg/day per kg BW) × BW (kg) × 6 h urine sample UK/UC, where daily UC excretion can be a given value.     

Passive protection of dogs against clinical disease due to Canine parvovirus-2 by specific antibody from chicken egg yolk

The protective effect of immunoglobulins derived from chicken egg yolk (IgY) against infection by Canine parvovirus 2 (CPV-2) was evaluated in 10 beagle dogs orally challenged with a strain of the virus. The 2-mo-old dogs were divided into 3 groups and treated with powders containing CPV-2 IgY or normal egg yolk for 7 d after the challenge. The 4 dogs receiving normal egg yolk (control group) demonstrated mild symptoms typical of CPV-2 infection, such as vomiting, diarrhea, and weight loss. No symptoms were observed by 16 d after challenge in the 3 dogs receiving 2 g of IgY powder. Of the 3 dogs receiving 0.5 g of IgY powder, 2 had clinical CPV-2 disease; however, the manifestations were less severe than in the control group. Furthermore, the IgY-treated groups had significantly greater weight gain and shorter duration of virus shedding than the control group. These results indicate that IgY is useful in protecting dogs from CPV-2-induced clinical disease.     

Physicochemical properties of the thermal gel of water-washed meat in the presence of the more soluble fraction of porcine sarcoplasmic protein

We investigated the physicochemical properties of the thermal gel of water‐washed pork meat (WWM) in the presence of the soluble fraction of porcine sarcoplasmic protein (SP) obtained with ammonium sulfate at 75 percent saturation. Two precipitated fractions of SP were obtained at 0–50 percent and 50–75 percent saturation, named SP‐f1 and SP‐f2, respectively, and the soluble fraction obtained at 75 percent saturation, SP‐f3, was used. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis showed that SP‐f3 contained mainly glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), while SP‐f1 and SP‐f2 had other SPs such as phosphorylase b, enolase, actin and phosphoglycerate mutase. The gel strength of WWM was greater when SP‐f3 rather than one of various animal proteins such as bovine plasma (BP), egg white, or whey protein isolates (WPI), was added and SP‐f3 had a gel‐enhancing effect as good as that of polyphosphate (PP). The gel strength of WWM with added SP‐f3 increased significantly with NaCl at 0.15 mol/L or more, but not in the absence of NaCl (0 mol/L). The effect of SP‐f3 was evident at neutral pH and maximum gel strength was obtained at a pH above 6.0. Differential scanning calorimetric (DSC) analysis showed that an endothermic peak corresponding to myosin heads in WWM shifted to a lower temperature with the addition of SP‐f3, as in the case of PP, though there was no such shift in the presence of other animal proteins (BP, egg white and WPI), suggesting that SP‐f3 increases the gel strength of WWM through the dissociation of actomyosin similar to PP. Scanning electron microscopy (SEM) revealed wall‐like structures among the protein strands in the WWM gel matrix in the presence of SP‐f3. The results of DSC and SEM indicated that the formation of a gel network in meat products is reinforced with GAPDH in SP after the interaction between GAPDH and myofibrillar protein.     

Effects of field pea (Pisum sativum L.) hay feeding on dry matter intake and milk production of Murrah buffaloes (Bubalus bubalis) fed rice straw ad libitum

To identify the effects of field pea hay (FPH) as a supplement of rice straw (RS) on feed intake and milk production of mid‐late lactation buffaloes in Tarai, Nepal, nine multiparous Murrah were fed a concentrate at 0.6% of their bodyweight (BW) on a concentrate dry matter (DM) basis daily while having ad libitum access to RS. The buffaloes were divided into three groups, and the experiment with three levels of FPH feeding was conducted at the following rate of BW: 0% (T1), 0.5% (T2) and 1.0% (T3) on an FPH DM basis. The DM intake (DMI) was higher in T2 and T3 than in T1. As the amount of FPH was raised, the BW change, crude protein intake (CPI) and total digestible nutrient intake (TDNI) was increased. Although the yield of milk and milk composition did not differ among the treatments, the 7% fat corrected milk yield (FCMY) tended to increase as FPH feeding amount was raised. Although there were no significant differences in FCMY/DMI and FCMY/TDNI among the treatments, FCMY/CPI decreased with FPH feeding. Supplementary FPH increased DMI, CPI and TDNI that might have raised BW, and tended to improve FCMY in mid‐late lactating buffaloes as a result of an increase in TDNI.     

Appearance of race Pfs:5 of spinach downy mildew fungus, Peronospora farinosa f. sp. spinaciae, in Japan

The races for the causal agent of spinach downy mildew Peronospora farinosa f. sp. spinaciae were identified by inoculation of race-differential cultivars. One isolate was identified as Pfs:5s and the others belonged to a new race. This is the first report of race Pfs:5 and another new race in Japan.     

Effects of carbon and nitrogen amendment on soil carbon and nitrogen mineralization in volcanic immature soil in southern Kyushu,Japan

Soil N mineralization is affected by microbial biomass and respiration, which are limited by available C and N. To examine the relationship between C and N for soil microbial dynamics and N dynamics, we conducted long-term laboratory incubation (150 days) after C and N amendment and measured changes in C and N mineralization, microbial biomass C, and dissolved C and N throughout the incubation period. The study soil was volcanic immature soil from the southern part of Japan, which contains lower C and N compared with other Japanese forest soils. Despite this, the area is covered by well-developed natural and plantation forests. Carbon amendment resulted in an increase in both microbial biomass and respiration, and net N mineralization decreased, probably due to increasing microbial immobilization. In contrast, N amendment resulted in a decrease in microbial respiration and an increase in net N mineralization, possibly due to decreased immobilization by microbes. Amendment of both C and N simultaneously did not affect microbial biomass and respiration, although net N mineralization was slightly increased. The results suggested that inhibitory effect on microbial respiration by N amendment should be reduced if carbon availability is higher. Thus, soil available C may limit microbial biomass and respiration in this volcanic immature soil. Even in immature soil where C and N substrate is low, soil C, such as plant root exudates and materials from above- and belowground dead organisms, might help to maintain microbial activity and N mineralization in this study site.