Growth and Metabolism of Soybean as Affected by Paclobutrazol

Paclobutrazol, an experimental growth retardant, was soil-appliedat the rate of 125 or 250 µg active ingredient per 10cm pot to 19 day-old soybean plants. This compound considerablyreduced plant height, leaf area, and stem dry weight. In addition,paclobutrazol-treated plants had numerous thickened lateralroots at the soil surface and had increased chlorophyll andsoluble protein contents compared to controls. During the first14 days after treatment, paclobutrazol increased the activitiesof NAD- and NADP-glyceraldehyde-3-phosphate dehydrogenase andaminotransferases but decreased the activity of nitrate reductase.Net photosynthesis (P_n) of the first and second trifoliatesof treated plants remained fairly constant throughout the studywhile control P_n declined during the latter portion of the experimentalperiod presumably due to leaf senescence. This decline of P_nin controls was accompanied by a decrease in the activitiesof NAD- and NADP-glyceraldehyde-3-phosphate dehydrogenase, nitratereductase, aminotransferases, and NAD malate dehydrogenase.Activities of these enzymes also tended to decline in paclobutrazol-treatedplants, but were still considerably higher than in controlsat the end of the experiment. The activities of RNase, protease,and glutamic dehydrogenase were higher in controls than in treatedplants. Our results suggest that paclobutrazol not only modifiesthe activity of a number of soybean enzymes but also delaysthe onset of senescence, thereby prolonging the period of normalmetabolic activity in a given leaf. ¹ Permanent address: Department of Botany, University of Jodhpur,India.     

Direct and Repeatable Bone Marrow Chromosome Preparations from Living Mice

Using a 27 gauge hypodermic needle, bone marrow is aspirated from a lumbar vertebra into 0.1 ml of Hanks' salt solution. The aspirate is kept well mixed in 1% sodium citrate for 15 min, centrifuged, and the cell pellet fixed for 30 min in Clarke's 3:1 ethanol-acetic fixative. After removal of the fixative the cells are suspended in 0.05-0.1 ml of 60% acetic acid, centrifuged and resuspended in 0.03 ml of this fixative. Chromosome preparations are made by spreading the suspension on a slide heated to 60 C.     

Hardness of Maraglas as Affected by Solvent-Monomer Interaction

Acetone and propene oxide were mixed with equal volumes of Maraglas epoxy embedding medium. Retention of these solvents in the resin after cure at 60 C was measured. The retention of propene oxide was greater than that of acetone and appeared to be due to a chemical interaction with the monomer. The reaction was catalysed by benzyldimethylamine. Although 3-4% of added acetone was retained, no evidence that this resulted from a chemical interaction was obtained. Vacuum evacuation of added solvents prior to cure did not materially affect their retention. Retention of both solvents resulted in softer cured resins.     

Photosynthesis of Prochloron as Affected by Environmental Factors

The effects of light intensity, pH, temperature, and UV irradiation on the photosynthetic rate of Prochloron isolated from the ascidian host Lissoclinum patella, collected from Palau, were examined. Photosynthesis increased with light intensity with saturation at 500 μmol/m² per second. It was maximum at pH 8 to 9 but almost completely suppressed below pH 7. The optimum temperature was 35° to 40°C, but the photosynthesis was absent at ≤20°C and at 45°C. It was recovered when the symbiont was transferred from 1 hour of incubation at ≤20°C to 35°C but not when transferred from incubation at 45°C. Ultraviolet irradiation severely inhibited the photosynthesis of Prochloron in isolation but not in vivo. This protection was brought about by the tunic covering the ascidian colony, which contains UV-absorbing mycosporine-like amino acids. These results indicate that the characteristic condition of the tropical marine environment largely determines the ecological distribution of Prochloron, and the ascidian tunic protects the organism from UV radiation. Received February 17, 2000; accepted August 8, 2000.     

Root Permeability as Affected by Picloram and Other Chemicals

The effects of picloram (4-amino 3,5,6-trichloropicolinic acid) and several other chemicals on root permeability were studied. Initially, effects on cell permeability were investigated by measuring the betacyanin efflux from red beet (Beta vulgaris L.) root sections. Picloram solutions ranging from 10^-3M to 10^-6M had no significant effect on betacyanin efflux when compared to controls. Similar results were found for 10^-4M and 10^-5M 2-methoxy-3,6-dichlorobenzoic acid (dicamba), 10^-4M 2,4-dichlorophenoxyacetic acid (2,4-D) and 10 μl/l of ethylene. Compounds that caused significant pigment leakage were 10^-4M and 10^-5M phenylmercuric acetate (PMA), 10^-3M and 10^-4M 2,4-dinitrophenol (DNP), 10^-3M and 10^-4M 2,4,5–trichlorophenoxyacetic acid (2,4,5-T) and 10^-3M 2,4-D. The effects of picloram on root permeability were also studied with bean plants (Phaseolus vulgaris L. cv. Black Valentine) grown in nutrient solution under controlled environmental conditions. Roots treated for 3 hours with 10^-5M picloram showed no significant electrolyte leakage as determined by conductivity measurements of the root-bathing solution over a period of 52 hours. When bean plants were root-trated for 3 hours with 10^-5M, and 10^-7M picloram and then decapitated, increased stem exudation by the treated plants as compared to controls was observed. Xylem exudate of the teated plants also showed increased electrolytic conductivity. The increased exudation rate accompanied by increased conductivity indicates that picloram has little effect on root cell membrane integrity, appears not to act as a metabolic inhibitor in the root system, and in some way stimulates salt secretion into the xylem.     

Growth and Metabolism of Senna as Affected by Salt Stress

Pot culture experiments were conducted using different NaCl concentrations to assess their impact on the growth and metabolic changes in senna (Cassia angustifolia Vahl.). Five treatments (0, 40, 80, 120, and 160 mM NaCl) were given to the plants at three phenological stages, i.e. at pre-flowering, (45 days after sowing, DAS); flowering (75 DAS) and post-flowering (90 DAS) stages. A significant reduction in the biomass and length of the roots and shoots, photosynthetic rate, stomatal conductance, the total chlorophyll content, protein content, nitrate reductase activity, and reduced nitrogen content of the leaves was observed at each phenological stage with each salt concentration applied. Contrary to this, proline and nitrate contents of the leaves increased markedly. The post-flowering stage was most sensitive to NaCl treatment.     

人体半导体激光外照射的疗效及其作用机理研究：血浆肽类神经递质 …

本工作应用半导体激光（６５０ｎｍ,１５－２０ｍＷ,ＣＷ）穴位照射人体双侧“扶突”穴后,同步观察其在血浆肽类神经递质上的变化以及其在血液黏度,免疫功能,抗氧化体系等方面的影响及其相关性。结果发现β－Ｅｐ有非常显著性的下降（Ｐ＜０．０２）,患者的ＮＫ细胞活性,在照射后即有所显著性地提高（Ｐ＜０．０５）。患者的超氧化物歧化酶（ＳＯＤ）亦有同步增加（Ｐ＜０．０５）。此外在血液流变学方面,发现血粘度指标中有     

Development of Heterodera glycines as Affected by Alachlor and Fenamiphos

A series of greenhouse experiments was conducted to elucidate the postinfection development of Heterodera glycines in response to applications of alachlor and fenamiphos. The rate of H. glycines maturation on a susceptible soybean cultivar was not altered by 1.0 μg alachlor/g soil but was completely inhibited by 1.0 or 1.5 μg fenamiphos/g soil. An alachlor-fenamiphos combination allowed development after an initial 300-degree-day delay. Nematode maturation on the resistant soybean cultivar Centennial with 1.0 μg alachlor/g soil was similar to that observed on an untreated resistant control. Twice as many females matured on Centennial plants growing in alachlor-treated soil as on untreated Centennial plants. Fenamiphos in combination with alachlor (1.0 μg a.i./g soil) allowed development on Centennial at half the rate of the resistant control. This antagonism between alachlor and fenamiphos on development may help to explain late season population resurgence of H. glycines observed with field application of these pesticides.     

Growth and Respiration in Plants from Various Adaptation Groups as Affected by Mineral Nutrient Deficiency

The effect of the deficiency in mineral nutrients was investigated in plant species representing various adaptation groups (stress-tolerant, competitive, and ruderal plants). Dry and fresh weight, as well as the length of shoots and underground organs, were determined in 20- to 50-day-old seedlings. The ratio between the dry weights of shoot and root (SRR), relative growth rate (RGR), the rate of total dark respiration (R), gross photosynthesis (P _g), and the proportion of the respiratory expenditures to gross photosynthesis (R/P _g) were calculated. When affected by a deficiency in mineral nutrients, the weight of the whole plant decreased. In resistant species of clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.), this reduction was insignificant, whereas, in the ruderal species amaranth (Amaranthus retroflexus L.), it was at its highest. In all the species investigated, the ratio R/P _g was 38–46%. Under stress conditions, this index increased. Given a deficiency in mineral nutrients, the changes in SRR, RGR, and R/P _g were greater in amaranth, suggesting that this plant species is less tolerant to stress. The correlation between RGR and R observed in amaranth under normal conditions indicates that the major energy expenditures are associated with growth. Under stress conditions, such a correlation was not observed. In more resistant species of clover and alfalfa, a weak positive correlation between RGR and R was observed both under normal and stress conditions. In these species, the deficiency in mineral nutrients probably brought about a reduction in the growth component of total dark respiration and a rise in the adaptation component. The complex of indices (R/P _g, RGR, and SRR) and the extent of their variation in the seedlings describe the potential productivity and resistance of particular species to a deficiency in mineral nutrients and may characterize the adaptation type of the plants.     

Water Content of Branches as Affected by Cutting Methods

The results of McDermott and Gibbs on the water content of branchsegments, and their conclusions regarding the effect of cuttingmethods, are reanalysed using a t-test on paired differences.It is concluded that the results do not give unequivocal evidencefor the presence of water columns under tensile stress.     

Xiphinema americanum as Affected by Soil Organic Matter and Porosity

The effects of four soil types, soil porosity, particle size, and organic matter were tested on survival and migration of Xiphinema americanum. Survival and migration were significantly greater in silt loam than in clay loam and silty clay soils. Nematode numbers were significantly greater in softs planted with soybeans than in fallow softs. Nematode survival was greatest at the higher of two pore space levels in four softs. Migration of X. americanum through soft particle size fractions of 75-150, 150-250, 250-500, 500-700, and 700-1,000 μ was significantly greater in the middle three fractions, with the least occurring in the smallest fraction. Additions of muck to silt loam and loamy sand soils resulted in reductions in survival and migration of the nematode. The fulvic acid fraction of muck, extracted with sodium hydroxide, had a deleterious effect on nematode activity. I conclude that soils with small amounts of air-filled pore space, extremes in pore size, or high organic matter content are deleterious to the migration and survival of X. americanum, and that a naturally occurring toxin affecting this species may be present in native soft organic matter.     

Rhizobacterial Glutathione Levels as Affected by Starvation and Cadmium Exposure

The rhizosphere is a continuously fluctuating environment in which severe stresses are put on its inhabitants, and glutathione, a reducing tripeptide, and related compounds probably have important roles in cellular protection. In the present study the metabolism of glutathione was examined in rhizobacteria subjected to stress. The plant-growth-promoting rhizobacterium Pseudomonas fluorescens 5.014 and its mutant 5-2/4 were exposed to starvation, either by resuspension or exhaustion, and to cadmium. Glutathione levels, cell protein, and viable count were determined and compared in different conditions. Both starvation and cadmium exposure decreased the amount of glutathione in the cell. No changes of the glutathione concentration in the medium were observed with or without the presence of rhizobacteria, indicating that there was no transport over the cell membrane. The glutathione levels within the rhizobacteria may give valuable information on how different stresses affect the bacteria. In this study, the involvement of glutathione in the increased stress resistance earlier observed in nutrient-starved P. fluorescens was not supported. The concentration of bacterial glutathione is suggested as a possible marker for rhizosphere competence, which, however, needs to be further evaluated with several strains of rhizobacteria. Received: 17 April 1998 / Accepted: 21 May 1998     

肯氏相思~(60)Co-r辐照诱变研究

采用不同剂量（3000、5000、7000Rad）(60)Co－r辐照肯氏相思种子，选育出诱变化株（M1），以M1的种子（M2）扩种试验。观测M1和M2代的形态、物候，并测定过氧化物酶同功酶带谱、酶活性、蛋白质含量，结果表明，各处理的优株与对照都存在差异。在相同生态条件下，M1代林木生长量和民代地上部生物量分别高于对照见11.48％～21．64％和14．62％～73．98％，以5000Rad辐照剂量最优，其次为7000Rad。访变个体后代表现树干直、花果期提早和种子小。     

Radial Oxygen Losses from Intact Rice Roots as Affected by Distance from the Apex, Respiration and Waterlogging

Radial oxygen losses (ROL) from the roots of intact rice plants were assayed by the cylindrical Pt electrode technique. At 23°C losses from roots grown in waterlogged soil proved to be about double those from non-waterlogged plants. Cooling which lowers respiratory activity led to increased ROL and it was estimated that at 23°C respiratory activity had been reducing oxygen loss by 8 to 10 10^–8g O₂ cm^–2 root surface min^–1 (c. 50 %) in the non waterlogged, and by 4.5 to 5.5 10^–8g O₂ cm^–2 min^–1 (2C–30 %) in the waterlogged roots. Lacunae formation occurred nearer to the apex and was eventually more extensive in the waterlogged roots while the presence of more intact and presumably functional tissue in the non-waterlogged roots coincides with the greater respiratory effect noted. Estimated flux rates at 23°C (respiration inactive) were respectively 15–17 × 10^–8g O₂ cm^–2 min^–1 (non-waterlogged) and 20–23 × 10^–8g O₂ cm^–2 min^–1 (waterlogged). A major part of this difference can probably be accounted for directly by the differences in root porosity, and Meakiness' superimposed upon lower porosity in the non-waterlogged plants may account for the remainder. ROL was also examined in relation to distance from the apex. With respiratory activity lowered by cooling, two patterns of oxygen loss were detected. Pattern I was a property of younger roots of length between 5–9 cm, while pattern 2 was found in longer roots 11–16 cm bearing numerous emergent laterals. In both, ROL fell rapidly towards the base and at 4–5 cm approached zero in pattern 1 and near zero to about 16% of the maximum in pattern 2. The rapid drop in oxygen loss in both patterns which indicates a concomitant decrease in root wall permeability was associated with the appearance of cortical lacunae at 2–3 cm from the apex. In pattern 2 a rise in ROL began at 5–6 cm from the apex. The presence of lateral root initials in both the pericycle and unbroken segments of cortex was associated with maintained permeability in this pattern as well as with the basal increase in ROL. With a 3-electrode system placed around the apical 3 cm regions of waterlogged roots, it was found that ROL was substantially affected by respiratory activity at 0.5 cm, a little less so at 1.7 cm, but much less or not at all at 3 cm from the apex. The drop in respiratory effect parallelled the formation of cortical lacunae.     

Comparison of planned and measured rectal dose in-vivo during high dose rate Cobalt-60 brachytherapy of cervical cancer

Cobalt-60 (Co-60) is a relatively new source for the application of high-dose rate (HDR) brachytherapy. Radiation dose to the rectum is often a limiting factor in achieving the full prescribed dose to the target during brachytherapy of cervical cancer. The aim of this study was to measure radiation doses to the rectum in-vivo during HDR Co-60 brachytherapy. A total of eleven HDR brachytherapy treatments of cervical cancer were recruited in this study. A series of diodes incorporated in a rectal probe was inserted into the patient's rectum during each brachytherapy procedure. Real-time measured rectal doses were compared to calculated doses by the treatment planning system (TPS). The differences between calculated and measured dose ranged from 8.5% to 41.2%. This corresponds to absolute dose differences ranging from 0.3 Gy to 1.5 Gy. A linear relationship was observed between calculated and measured doses with linear regression R² value of 0.88, indicating close association between the measured and calculated doses. In general, absorbed doses for the rectum as calculated by TPS were observed to be higher than the doses measured using the diode probe. In-vivo dosimetry is an important quality assurance method for HDR brachytherapy of cervical cancer. It provides information that can contribute to the reduction of errors and discrepancies in dose delivery. Our study has shown that in-vivo dosimetry is feasible and can be performed to estimate the dose to the rectum during HDR brachytherapy using Co-60.     

Generation of Reactive Oxygen Species from Hinokitiol under Near-UV Irradiation

Near-UV irradiation caused the decomposition of hinokitiol in an aqueous solution. During the photochemical reaction, the distinct electron spin resonance signal characteristic of the adduct of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) with the hydroxyl radical was accompanied by small signals corresponding to the adduct of DMPO with the superoxide anion radical. More than 95% of Escherichia coli cells were killed by the incubation with hinokitiol under near-UV irradiation by BLB fluorescent lamps. These results indicated the generation of reactive oxygen species during photochemical reaction of hinokitiol under near-UV irradiation.