Refinement of Hot Water Treatment for Management of Aphelenchoides fragariae in Strawberry

The effects of hot water treatments on a California population of the foliar nematode, Aphelenchoides fragariae, and on five strawberry cuttivars ('Chandler', 'Douglas', 'Fern', 'Pajaro', and 'Selva') were assessed in laboratory and greenhouse tests. Nematodes extracted from fern leaves were placed in water maintained at 44.4, 46.1,47.7, or 49.4 C for different time periods. Exposure periods of 15, 5, 4, and 2 minutes were required to produce 100% mortality at 44.4, 46.1, 47.7, and 49.4 C, respectively. In a water bath, 4 minutes were required for strawberry crowns initially at 25 C to equilibrate with temperatures ranging from 44.4-54.4 C. The maximum exposure periods that did not significantly reduce subsequent plant growth and flowering were 30, 15, and 10 minutes, at 44.4, 46.1, and 47.7 C, respectively. Survival of Selva was lower (P = 0.05) than for the other cultivars. Treatment at 49.4 C for 5 minutes significantly reduced plant growth and flowering of all cultivars. The minimum-maximum exposure periods that killed A. fragariae without damaging the cultivars tested were 20-30 minutes at 44.4 C, 10-15 at 46.1 C, or 8-10 at 47.7 C.

Evaluation of Hot Water Treatments for Management of Ditylenchus dipsaci and Fungi in Daffodil Bulbs

Treatment of daffodil (Narcissus pseudonarcissus) bulbs in a 0.37% formaldehyde water solution at 44 C for 240 minutes is a standard practice in California for management of the stem and bulb nematode, Ditylenchus dipsaci. Recent concern over the safety of formaldehyde and growers' requests for a shorter treatment time prompted a reevaluation of the procedure. The time (Y, in minutes) required to raise the temperature at the bulb center from 25 to 44 C was related to bulb circumference (X, in cm) and is described by the linear regression Y = -15 + 3.4X. The time required for 100% mortality of D. dipsaci in vitro without formaldehyde was 150, 60, and 15 minutes at 44, 46, and 48 C, respectively. Hot water treatment (HWT) with 0.37% formaldehyde at 44 C for 150 minutes controlled D. dipsaci and did not have a detrimental effect on plant growth and flower production. Shorter formaldehyde-HWT of 90, 45, and 30 minutes at 46, 48, and 50 C, respectively, controlled D. dipsaci but suppressed plant growth and flower production. Fungal genera commonly isolated from the bulbs in association with D. dipsaci were Penicillium sp., Fusarium oxysporum f. sp. narcissi, and Mucor plumbeus, representing 60, 25, and 5%, respectively, of the total fungi isolated. These fungi caused severe necrosis in daffodil bulbs. HWT at 44 C for 240 minutes reduced the number of colonies recovered from bulbs. The effects of formaldehyde, glutaraldehyde, and sodium hypochlorite in reducing the population of fungi within bulbs were variable. Satisfactory control of D. dipsaci within bulbs can be achieved with HWT of bulbs at 44 C for 150 minutes with 0.37% formaldehyde or at 44 C for 240 minutes without chemicals.

[Effects of hyperlipidemic serum on cultured vascular smooth muscle cells pre-incubated with different doses of PGE2]

Based on previous studies in our laboratory, the effects of hyperlipidemic serum on cultured SMCs, pre-incubated with different doses of PGE2, were observed by the determination of intracellular lipid peroxide and radioimmunoassay of 6-0-PGF1 alpha. The results showed that the hyperlipidemic serum accelerated the production of lipid peroxide and inhibited the synthesis of PGI2 in SMCs. PGE2 in small doses promoted the above-mentioned two effects, while large doses of PGE2 displayed an inhibitory effect on lipid peroxidation and markedly accelerated PGI2 synthesis. This indicates that PGE2 might play an important role in the protection of SMCs from peroxidative injuries and atherogenesis.

[Study and preparation of Vi-PHA reagent and its application for detection of Salmonella typhi carriers]

Purified S. typhi Vi antigen is sensitized with equal volume of tannic acid treated formalational sheep erythrocytes (SRBC) at a final concentration of 1 microgram/ml. The Vi-passive hemagglutination assay (Vi-PHA) diagnostic reagent is developed to detect Vi antibodies to S. typhi for the detection of chronic carriers after typhoid fever and the screening S. typhi healthy carriers from food-handlers, which is characterized with high sensitivity, strong specificity and good stability. This Vi-PHA reagent is able to detect 1.16 micrograms/ml of Vi antibodies and doesn't make any cross reaction with healthy sera. For the sera of other diseases, the cross rate is only 0.84%. Using this reagent, 19 positive sera (6.93%) are detected from 274 convalescent sera from typhoid fever, 14 convalescents of which are stool-culture S. typhi positive, that persists a positive rate of 73.68%; 3 positive sera are detected from 106 foodhandlers, one of which is stool-culture S. typhi positive. Therefore, the reagent is simple, convenient, rapid and easy to be applicated in basic unit.

Growth of Haemophilus influenzae in human milk: synthesis, distribution, and activity of IgA protease as determined by study of iga+ and mutant iga- cells

The nonencapsulated, IgA protease-positive Haemophilus influenzae strain Rd and serogroup b clinical isolates were found to proliferate in human milk. Growth did not require supplemental X and V factors. In milk, strain Rd synthesized IgA protease, but it was completely inhibited by antibody, so secretory IgA in milk cultures remained intact. Inhibition was largely attributable to IgA1 antibodies. Rd cells also aggregated during growth in milk and showed colony size variation, whereas a protease-negative mutant of Rd (Rd225DK) aggregated less and had uniform colony size. Like differences in protease inhibition, these differences in growth pattern were mediated by secretory IgA1. Thus, milk antibody not only inhibited the extracellular protease but also interacted directly with the enzyme precursor or related antigens on growing bacterial cells. This self-protective property of milk secretory IgA may be an important immunologic attribute for the upper respiratory mucosa of the infant.

Adverse effects of cyclophosphamide on progeny outcome can be mediated through post-testicular mechanisms in the rat

Previous studies from our laboratory have suggested that, in addition to an effect on spermatozoa in the testis, cyclophosphamide may have an adverse effect on spermatozoa after they leave the testis, during epididymal transit. To elaborate on this post-testicular effect on germ cells and to determine at which site(s) in the epididymis germ cells are most sensitive to cyclophosphamide treatment, three experiments were undertaken. First, the time course of the effect of treatment of male rats with cyclophosphamide on the outcome of their progeny was determined. Male rats were treated daily by gavage with saline or one of two doses of cyclophosphamide (6.8 mg/kg or 10.0 mg/kg) for 1, 4, or 7 days. At the end of each treatment period, males were mated to assess the effect on pregnancy outcome. No effect was observed on pre-implantation loss at any time among any of the groups, but there was a time-dependent and dose-related increase in post-implantation loss. Post-implantation loss was significantly increased after 4 days of treatment and reached nearly 40% after 7 days of drug exposure (10.0 mg/kg). Second, the effect of treatment with single high doses of cyclophosphamide was studied. Male rats were treated with a single dose of cyclophosphamide (10, 30, or 70 mg/kg) and bred 1 day and 4 days post-treatment. No significant change in pre-implantation loss was observed at either time point; no change in post-implantation loss was found after 1 day post-treatment. However, a significant increase in post-implantation loss was observed in the two high-dose groups 4 days post-treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Diurnal starch accumulation and utilization in phosphorus-deficient soybean plants

The effects of phosphorus deficiency on carbohydrate accumulation and utilization in 34-day-old soybean (Glycine max L. Merr.) plants were characterized over a diurnal cycle to evaluate the mechanisms by which phosphorus deficiency restricts plant growth. Phosphorus deficiency decreased the net CO(2) exchange rate throughout the light period. The decrease in the CO(2) exhange rate was associated with a decrease in stomatal conductance and an increase in the internal CO(2) concentration. These observations indicate that phosphorus deficiency increased mesophyll resistance. Assimilate export rate from the youngest fully expanded leaves was decreased by phosphorus deficiency, whereas starch concentrations in these leaves were increased. Higher starch concentrations in phosphorus-deficient youngest fully expanded leaves resulted from a longer period of net starch accumulation and a shorter period of net starch degradation relative to those for phosphorus-sufficient controls. Phosphorus deficiency decreased sucrose-P synthase activity by 27% (averaged over the diurnal cycle), and essentially eliminated diurnal variation in sucrose-P-synthase activity. Diurnal variations in nonstructural carbohydrate concentrations in leaves and stems were also less pronounced in phosphorus-deficient plants than in controls. In phosphorus-deficient plants, only 30% of the whole plant starch present at the end of a light phase was utilized during the subsequent 12-hour dark phase as compared with 68% for phosphorus-sufficient controls. Although phosphorus deficiency decreased the CO(2) exchange rate and whole plant leaf area, accumulation of high starch concentrations in leaves and stems and restricted starch utilization in the dark indicate that growth processes (i.e. sink activities) were restricted to a greater extent than photosynthetic capacity. Further experimentation is required to determine whether decreased starch utilization in phosphorus-deficient plants is the cause or the result of restricted growth.

Antioxidant action of certain simple phenolic compounds derived from Chinese herbs

H2O2 and hydroxyl free radical active oxygen generation systems were utilized to define the antioxidant activities of simple phenolic compounds derived from Chinese herbs. Although the antioxidant activities of compounds differed when assessed in the two systems, all compounds tested were found to be effective at preventing red blood cell membrane lipid peroxidation, with the propyl and butyl esters of gallic acid being especially potent. No compound was able to prevent hemoglobin oxidation. All compounds but salicylic acid were found to interact dose-dependently with H2O2 and hydroxyl free radical as determined by a chemiluminescence method.