In vivo imaging of the interior of Tradescantia zebrina leaves by optical cross-correlation interferometry.

Using optical correlation interferometry, a novel method for plant sciences, we in imaged in vivo the z-direction, perpendicular to the leaf surface, through Tradescantia zebrina leaves. Non-invasively we determined number of major cell layers, followed the time sequence of decrease in cell z-axis after exposure of tissues to high salt, and observed disruption of cells caused by freezing and thawing.

Development of the alt Mutant of Pisum sativum L.

The alt (albina-terminalis) mutant of Pisum sativum L. germinates normally, produces several nodes, and then above a sharp transition produces 2 to 3 bleached nodes, ceases growth, and eventually dies. Green nodes have normal chlorophyll content, absorption spectra, photosynthetic rates, and ultrastructure. In bleaching tissues, the chloroplasts degenerate rapidly, followed by extensive disruption and loss of the remaining cytoplasm and organelles. Application of tissue extracts of normal genotypes of pea, corn, and bean stimulates apical development of alt. The resulting tissues have essentially normal structure and function. Application of thiamine, thiamine monophosphate, and thiamine pyrophosphate also stimulate normal apical development at concentrations of 1 micromolar and above. Partial characterization of the stimulus from pea seed extracts is consistent with thiamine as the active factor.

Differences between Fragaria clones by fourth derivative room temperature spectroscopy of intact leaves.

Clones of Fragaria were characterized by the attenuance (absorption) spectra of their photosynthetic apparatus. This method uses fourth derivative analysis of spectra of intact lamina of detached leaves at room temperature (20-25 C). Twenty-one different species and hybrids of Fragaria were examined. F. chiloensis accessions frequently have characteristic fourth derivative spectra distinct from that of other Fragaria species. These spectra are characterized by a strong band that appears to be photosystem I component Ca 693; and is correlated with a higher chlorophyll b content per unit area of leaf, and a lower chlorophyll a/b ratio.

Inhibitory activity of the new adamantane derivative N,N'-bis(ethylene)-P(1-adamantyl)-phosphonic diamide against Rous sarcoma virus.

A new adamantane derivative N,N'-bis (ethylene)P(1-adamantyl)-phosphonis diamide, was found to inhibit Rous sarcoma virus replication in much the same manner as reported for the parent compound, 1-adamantanamine hydrochloride.

The cell-wall phosphatase of cotton (Gossypium) is inhibited by kelthane.

Kelthane [4,4'-dichloro-alpha-(trichloromethyl)benzhydrol] was previously shown to decrease the limited tolerance of susceptible varieties of cotton (Gossypium) to Verticillium wilt. Kelthane was shown in the present study to inhibit the cell-wall p-nitrophenyl phosphatase of cotton. In view of information already establishing the cell wall as a primary site of action of Verticillium wilt, the data are interpreted as suggesting an as yet undefined interaction between Kelthane, cell-wall phosphatase and verticillium-resistance mechanisms of the cell wall.

Light activation of ribulose bisphosphate carboxylase: purification and properties of the enzyme in tobacco.

The development of methods of preparation of long wavelength ultraviolet light capable of activating ribulose bisphosphate carboxylase is reported. This preparation was obtained from tobacco (Nicotiana tabacum) leaves which had reached about one-half maximum leaf weight. It was prepared at low ionic strength by use of mixed anion and cation exchange resins and buffers containing dimethylsulfoxide. The preparation is greatly enriched in fraction I protein to the point of apparent homogeneity. When assayed in the presence of saturating ribulose bisphosphate and sodium bicarbonate, the rate of carbon fixation is a linear function of long wavelength ultraviolet irradiation in the range of 20,000 to 30,000 ergs per square centimeter per second. Glutathione (5 mm) inhibits light activation without affecting activity in the dark. Copper sulfate inhibits both light and dark activity, but is slightly less effective in the presence of ultraviolet light. Sucrose inhibition of carboxylation is only readily apparent in the absence of ultraviolet light. Ammonium sulfate precipitation followed by solubilization in buffers containing dimethylsulfoxide plus heat treatment promotes ultraviolet light activation.

Phosphoserine and phosphohydroxypyruvic Acid: evidence for their role as early intermediates in photosynthesis.

Photosynthetic fixation of (14)CO(2) in the bean Phaseolus vulgaris, cv. Pencil Pod Black Wax, resulted in the appearance of labeled compounds that were characterized as phosphoserine and phosphohydroxypyruvate by chromatographic separation and by the synthesis of chemical derivatives. In (14)CO(2)/(12)CO(2) pulse-chase experiments these metabolites demonstrated the rapid pool saturation and depletion of (14)C characteristic of early intermediates in photosynthetic carbon fixation. They were present in sufficient amounts to account for about 35% of total carbon fixed in 1 minute.

Characterization of Phosphoenolpyruvate Carboxykinase from Pineapple Leaves Ananas comosus (L.) Merr.

Phosphoenolpyruvate carboxykinase has been partially purified from pineapple (Ananas comosus [L.]) leaves. Specific activities obtained show it to be a major activity in this tissue. Above 15 C, the respective activation energies for decarboxylation and carboxylation are 13 and 12 kcal/mol. Below 15 C, there are discontinuities in Arrhenius plots with an associated large increase in activation energy. The adenine nucleotides are preferred to other nucleotides as substrates. The apparent Km values in the carboxylation direction are: ADP 0.13 mm, HCO(3) (-) 3.4 mm, and phosphoenolpyruvate 5 mm. In the decarboxylation direction, the apparent Km values are: ATP 0.02 mm, ADP 0.05 mm, and oxaloacetate 0.4 mm. The decarboxylation activity had an almost equal velocity with either ADP or ATP. The pH optima are between 6.8 and 7. Inhibition of the carboxylation reaction by ATP, pyruvate, and carbonic anhydrase was demonstrated. Decarboxylase specific activities are over twice carboxylation activities. The data support a model in which phosphoenolpyruvate carboxykinase is of physiological significance only during the light period and then only as a decarboxylase.