On the Relationships of Net CO(2) Assimilation and Leaf Expansion to Vegetative Growth in Lycospersicum esculentum, var Jubilee.

Relationships between net plant CO(2) exchange rate (CER) and canopy development were examined in ;jubilee' tomato over the initial 4 weeks of vegetative growth. A comparison was made between two plant groups that were alternatively exposed to 200 or 800 microeinsteins per square meter per second midday irradiation to establish a differential in net CER. Plants exposed to higher irradiation demonstrated a 2- to 4-fold greater net photosynthetic rate per leaf area and 100% average higher net CO(2) assimilation rate/plant. day. However, leaf-stem growth differed by <50% suggesting a poor relationship to CER. Leaf area growth rate (LAGR) of individual leaves appeared closely related to CER during initial leaf expansion but a greater function of order of emergence in successive leaf growth. LAGR on a per plant basis increased linearly with leaf dry weight but appeared more limited by factors determining maximum leaf enlargement and rate of new leaf development. Net CO(2) assimilation/leaf area and leaf starch consistently declined with time while net CO(2) assimilation plant/day approached a constant rate following 2 to 3 weeks growth. Composite results suggested a simple relationship for sucessive growth where accumulated leaf carbohydrate in excess of 200 milligrams/plant.day could be expected to be partitioned to other plant segments.

Subcellular fractionation of wheat leaf protoplasts by centrifugal elutriation.

A new method using centrifugal elutriation for subcellular fractionation of plant cells has been developed. This method takes advantage of the fact that particles sedimenting in a gravitational field can be eluted by flow against the field. A wheat protoplast homogenate was fed into an elutriation rotor spinning at high speed and the flow rate into the rotor was gradually increased. The smaller and less dense materials such as mitochondria, microbodies, endoplasmic reticulum, and cytoplasm were elutriated earlier than the larger and denser nuclei and chloroplasts. The intact chloroplasts, free of mitochondria, microbodies, endoplasmic reticulum, and cytoplasm, could be obtained within 40 min following the rupture of protoplasts. The chlorophyll-free mitochondria could be obtained within 80 min.

Two homogeneous immunoassays for pyridoxamine.

Protein conjugates of pyridoxal have been used to elicit anti-vitamin B6 antibodies in rabbits. These antibodies have been incorporated into 2 homogeneous assays systems, a spin immunoassay, using a paramagnetic derivative of the vitamin as ligand, and a fluorescence enzyme immunoassay, using beta-galactosidase conjugated to vitamin B6 as the indicator molecule. These assay systems do not require fractionation steps, and could be the basis of analytical methodology for nutritional research or clinical diagnosis.

Effect of stereospecific hydroxylation of N(6)-(Δ (2)-Isopentenyl)adenosine on cytokinin activity.

The cytokinin activities of cis and trans ribosylzeatin isomers and that of N(6)-(Δ(2)-isopentenyl)adenosine were compared in four bioassays. The trans isomer was found to be more active than the cis isomer in stimulation of cucumber cotyledon expansion (100x), retention of chlorophyll in detached leaf pieces (7x), induction and stimulation of chlorophyll synthesis in cucumber cotyledons (20x) and of betacyanin synthesis in Amaranthus caudatus seedlings grown in the dark (60x). The N(6)-(Δ(2)-isopentenyl)adenosine adenosine was less active than the trans ribosylzeatin in all four bioassays and more active than the cis ribosylzeatin in induction and stimulation of betacyanin and chlorophyll synthesis. These results show that the hydroxylation of the trans methyl group in the N(6) side chain of N(6)-(Δ(2)-isopentenyl)adenosine increases the biological activity and that this activity is either decreased or not significantly changed when the cis methyl group is hydroxylated.

Cytokinins in tRNA Obtained from Spinacia oleracea L. Leaves and Isolated Chloroplasts.

Cytokinin-active ribonucleosides have been isolated from tRNA of whole spinach (Spinacia oleracea L.) leaves and isolated spinach chloroplasts. The tRNA from spinach leaf blades contained: 6-(4-hydroxy-3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine (cis and trans isomers), 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine, and 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-beta-d -ribofuranosylpurine (cis and trans isomers). A method for isolation of large amounts of intact chloroplasts was developed and subsequently used for the isolation of chloroplast tRNA. The chloroplast tRNA contained 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine and 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-beta-d -ribofuranosylpurine (the cis isomer only). The structures of these compounds were assigned on the basis of their chromatographic properties and mass spectra of trimethylsilyl derivatives which were identical with those of the corresponding synthetic compounds. The results of this study indicate that ribosylzeatin was present in spinach leaf tRNA, but absent from the purified chloroplast tRNA preparation.

Phage typing of coagulase-negative staphylococci and micrococci.

A total of 3217 strains of coagulase-negative staphylococci and micrococci were tested for susceptibility to a collection of phages isolated from coagulase-negative cocci; it was concluded that a useful typing scheme could be developed. Of the strains of Baird-Parker's biotype 1, 72% were lysed by one or more phages, although rather a large proportion of strains are lysed by many phages to give a complex typing pattern.Normal persons commonly yield 10 or more distinguishable strains of coagulase-negative cocci in cultures from the nose and the skin.

Antibiotic resistance of coagulase-negative staphylococci and micrococci.

Five hundred and seventy strains of Gram-positive, catalase-positive, coagulasenegative cocci from various sources were classified on the basis of their ability to grow anaerobically and to ferment mannitol. Five groups were distinguished. The frequency of strains classified in the five groups varied with the source. Only 26% of the strains were sensitive to all the nine antibiotics used in the tests. About half the strains from the lesions of hospital patients were resistant to penicillin, streptomycin, and tetracycline, and about 10% of them were resistant to cloxacillin. In general the frequency of antibiotic resistance and the ;width' of the resistance spectrum were greater in strains from hospital sources than in those from outside hospital, and they were also greater among strains regarded as falling in the genus Staphylococcus than in those classed as Micrococcus.