The Respiratory Metabolism of Strelitzia juncea Ait. Seeds. The Effect of Dormancy Release by Oxygen on certain Glycolytic Enzyme Activities and Metabolite Concentrations

The activity of the glycolytic enzymes PFK, PFP, PK and aldolaseas well as the content of glucose, fructose, glucose-6-phosphateand fructose-6-phosphate were compared in the embryos of airand oxygen-incubated seeds of Strelitzia juncea. Determinationswere made during the first 4 d of incubation, prior to radicleemergence, which commences on day five for oxygen-treated seeds. No difference in PFK activity was found for the two treatments,and for both treatments PFK tended to increase with the incubationperiod. The fr2, 6P₂-stimulated PFP activity was slightly higherfor oxygen-incubated seeds, and showed a significant increasein activity over the 4 d incubation period for both treatments.No significant change in the general trend of PK and aldolaseactivity resulted from incubating the seeds in oxygen. The almost equimolar glucose and fructose contents of the embryoswere lower after 1 d of oxygen incubation of the seeds, andthe content decreased sharply during the incubation period.It is concluded that a moderate increase in the glycolytic capacityof embryos resulted from oxygen treatment of S. juncea seeds. Key words: Dormancy, glycolysis, Strelitzia juncea     

Xylem and Phloem Import of Na+, K+, Rb+, Cs+ and Sb(SO4)2- in Tomato Fruits: Differential Contributions from Stem and Leaf

Wolterbeek, H. Th. and De Bruin, M. 1986. Xylem and phloem importof Na⁺, K⁺ , Rb⁺, Cs⁺ and in tomato fruits: differential contributions from stem and leaf.—J.exp. Bot. 37: 928–939. The transport of Na⁺, K⁺, Rb⁺, Cs⁺ and into developing fruits of tomato (an inbred lineof Lycopersicon esculentum Mill. cv. Tiny Tim) was measured.Element solutions were introduced into the transpiration streamthrough the cut stem bases of plant parts consisting of a stempart with single green fruit, both with and without attachedfully expanded leaf. Measurements were carried out of the accumulationin the fruit of the gamma-ray emitting radiotracers ²⁴Na⁺, ⁴²K⁺,⁸⁶Rb⁺, ¹³⁴Cs⁺ and The transport into the fruit was expressed by a single parameter taking intoaccount volume flows varying with time and experiments. Xylemto phloem transfer in the stem as a source of fruit elementsupply was shown to be inversely related with the velocity offlow of the stem xylem. The results also indicated that thetransfer system in the stem was more rapidly equilibrated thanit was in the leaf. Stem loading of the phloem is suggested as a possible mechanismregulating the solute influx in fruits under varying flow velocitiesof the stem xylem, while fruit influx of phloem solutes, whichwere loaded in the leaf, may play a major role in influx regulationunder conditions of varying solute concentrations. Key words: Alkali ions, tomato fruits, stem and leaf phloem loading     

Fine Structure and Cytochemistry of Tritrichomonas foetus and Rat Neutrophil Interaction

ABSTRACT. The fine structure of normal and antibody-coated Tritrichomonas foetus cells and their interaction with rat peritoneal neutrophils was studied. Peritoneal neutrophils were obtained by glycogen stimulation. The neutrophils readily associated with and killed the parasites, which were subsequently ingested. The process involved activation of the respiratory burst, as demonstrated by the use of cytochemical methods. Images were obtained indicating that binding of parasites to the neutrophil surface triggers an exocytic response with release of oxygen-derived products. Cytochemical localization of acid phosphatase and peroxidase activities showed that leukocyte granules fused with the parasite-containing phagocytic vacuoles. We also showed the cytochemical localization of alkaline phosphatase in the parasite-neutrophil interaction.