Competence of <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis> and <Emphasis Type="Italic">Frankliniella intonsa</Emphasis> strains as vectors for <Emphasis Type="Italic">Chrysanthemum stem necrosis virus</Emphasis>

The vector competence of Frankliniella occidentalis for Chrysanthemum stem necrosis virus (CSNV) was evaluated. Three vector strains with distinct competences for Tomato spotted wilt virus (TSWV) transmission were investigated, including an artificially selected strain (TsH) that has a particularly high competence (>90 %). Newly hatched larvae of F. occidentalis were given an acquisition access period of 5 days on CSNV-infected D. stramonium leaves, and reared to maturity. Their transmission efficiencies were examined using a leaf disk assay using Petunia x hybrida leaves. Following the leaf disk assay, the virus accumulation in the vectors was examined via a double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) of their bodies. The results showed that the CSNV acquisition and transmission efficiency of the TsH strain did not differ from those of the others, indicating that the competence of F. occidentalis as a vector for CSNV is not related to that for TSWV. The CSNV transmission and acquisition efficiencies of two F. intonsa strains (Hiroshima and Fukuoka) were also evaluated. In Hiroshima strain, 35 % of adults were viruliferous, but only two transmitters (3 %) were observed. In Fukuoka strain, 6 % were viruliferous, and no transmitters were observed. These results indicate that F. intonsa cannot be a major vector for CSNV. The accumulation of CSNV in the adults of F. occidentalis and F. intonsa evaluated using DAS-ELISA showed a significant difference in ELISA values among transmitter, viruliferous non-transmitter, and non-viruliferous individuals. These results clearly demonstrated that only transmitters that accumulated a threshold quantity of virus can transmit CSNV to plants.     

Comparison of changes in sugars and ethylene production of cherimoya fruit grown at different seasons

Summary

Changes in fruit weight, total soluble solids (TSS), sugar content and postharvest ethylene production during fruit development were compared on fruit of cherimoya (Annona cherimola Mill., cv. Big Sister) pollinated at different times (early, at the beginning of April, 1995 and late, at the end of May, 1994). Fruit weight increased by growth, independently of pollination times. Changes in TSS and sugar content were strongly affected by pollination time. In late pollinated fruits, both TSS and sugar content increased during the growth period, 110–160 d after pollination, while neither increased with fruit growth in early pollinated fruit. Moreover, changes in TSS and sugar content after ripening depended not only on pollination time but also on the growth period. With late pollination, fruit harvested after 140 d became edible after ripening. The TSS and total sugar contents, (the sum of fructose, glucose and sucrose contents) increased to about 20° Brix and above 16%, respectively. But early pollinated fruits were not edible after ripening, since total sugar content increased only to about 7%, even though they kept growing for 160 d on the tree. The maximum rate of ethylene production declined and the number of days to the ethylene peak from harvest is also reduced with growth in both cases. These changes were closely correlated with days after pollination (r>0.9) regardless of pollination time. Comparisons of accumulated temperature suggest that temperature at pollination time and during the resting period of growth affected fruit development. These results indicate that neither fruit weight nor number of days after pollination is a suitable index for harvesting time.     

Contribution of charcoal to short-term nutrient dynamics after surface fire in the humus layer of a dwarf bamboo-dominated forest

Ecological function of charcoal has been mainly investigated by adding charcoal to soil, which is not fully adequate to understand in situ the role in fire-prone forest ecosystem. To determine in situ effects of charcoal on ecosystem functions, such as nutrient availability, we conducted an experimental burning in a Japanese white birch forest with dense coverage of dwarf bamboo in the understory with or without removal of charcoal. Ammonium-N in the remaining humus layer increased immediately after the burning, but decreased to the level of unburnt plots within 1?month of the burning. Removal of charcoal had no significant effect on the NH₄ ⁺-N dynamics. Although burning did not affect NO₃ ^?-N dynamics during the sampling period, charcoal removal led to a slight increase in NO₃ ^?-N. The available P increased immediately after the burning, but then fell at 1?month after burning. Charcoal inhibited the available P depletion and prolonged the high availability of P. Greater availability of P might be due to the adsorption of phosphate in charcoal pores. Exchangeable Ca and Mg increased gradually; charcoal appeared to extend the period of higher concentration of exchangeable Ca and Mg. Charcoal deriving from fire is a key factor in influencing available nutrient in the humus layer of post-fire forests.     

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.     

Effect of nitrogen application at the flowering stage on the quality of soybean seeds

Application of nitrogen (N) fertilizer at the flowering stage changed the contents of storage compounds in seeds of Soybean (Glycine max L. cvs Enrei and Tamahomare). The effects of the N application on the maturation of soybean seeds were examined by comparing changes in the contents of amino acids, sugars, water, protein, and oil in seeds from N‐dressed plants (NDS) with those from undressed plants (UDS) during maturation. The application resulted in a decrease of contents of total and some amino acids (glutamine and asparagine) in developing seeds except for at the early maturation stage and in a decreased protein content of mature seeds. On the other hand, the N application led to faster accumulation of oil in developing seeds and to an increased oil content of mature seeds. Based on these results, it was concluded that the N application at the flowering stage changed the composition of solutes imported by developing seeds and resulted in variations in the contents of storage compounds. The results indicate that it is possible to improve seed quality by fine control of N application.     

Cloning and characterization of a NADP+-malic enzyme gene from Bradyrhizobium japonicum USDA110

Malic enzymes have been considered to play a key role in energy metabolism for nitrogenase reaction in bacteroids. To elucidate the physiological role of the malic enzymes in Bradyrhizobium japonicum bacteroids, a putative malic enzyme gene Bjtme1 was cloned by polymerase chain reaction (PCR) using degenerated primers from conserved regions of the protein sequences of bacterial malic enzymes and draft sequence data of the Bradyrhizobium japonicum USDA110 genome sequence project. To confirm the characteristics of the Bjtme1 gene, the protein encoded by this gene was over-expressed using a pET32a(+) system and it exhibited a NADP⁺-malic enzyme (EC 1.1.1.40) activity, indicating that Bjtme1 was the gene of the NADP⁺-malic enzyme. This is the first report on the cloning and characterization of the NADP⁺-malic enzyme gene from B. japonicum, and the gene structure was compared with that of NADP⁺-malic enzyme genes of other rhizobia.     

A possible connection between psychosomatic symptoms and daily rhythmicity in growth hormone secretion in healthy Japanese students

Background  

Students suffering from psychosomatic symptoms, including drowsiness and feelings of melancholy, often have basic lifestyle problems. The aim of this study was to investigate whether psychosomatic complaints may be related to circadian dysfunction.     

Histological observations of canine cystic endometrial hyperplasia induced by intrauterine scratching

Of eight mongrel bitches, the antimesometrial side of the nonpregnant left horn of the uterus at the pregnant or nonpregnant luteal phase was scratched with a Kirschner's wire. Cystic endometrial hyperplasia (CEH) was induced in seven of the eight bitches (87.5%). No difference in the incidence of CEH in the left horn was seen between the pregnant and the nonpregnant groups. Histological examinations showed CEH with a dilatation of the basal glands, resembling "Swiss cheese endometrium".     

Pharmacokinetics of procaterol in thoroughbred horses

Procaterol (PCR) is a beta‐2‐adrenergic bronchodilator widely used in Japanese racehorses for treating lower respiratory disease. The pharmacokinetics of PCR following single intravenous (0.5 μg/kg) and oral (2.0 μg/kg) administrations were investigated in six thoroughbred horses. Plasma and urine concentrations of PCR were measured using liquid chromatography–mass spectrometry. Plasma PCR concentration following intravenous administration showed a biphasic elimination pattern. The systemic clearance was 0.47 ± 0.16 L/h/kg, the steady‐state volume of the distribution was 1.21 ± 0.23 L/kg, and the elimination half‐life was 2.85 ± 1.35 h. Heart rate rapidly increased after intravenous administration and gradually decreased thereafter. A strong correlation between heart rate and plasma concentration of PCR was observed. Plasma concentrations of PCR after oral administration were not quantifiable in all horses. Urine concentrations of PCR following intravenous and oral administrations were quantified in all horses until 32 h after administration. Urine PCR concentrations were not significantly different on and after 24 h between intravenous and oral administrations. These results suggest that the bioavailability of orally administrated PCR in horses is very poor, and the drug was eliminated from the body slowly based on urinary concentrations. This report is the first study to demonstrate the pharmacokinetic character of PCR in thoroughbred horses.