DIFFUSION BOUNDARY LAYER TRANSPORT IN GRACILARIA CONFERTA (RHODOPHYTA)1

A theoretical framework on the combined effect of water velocity and solute concentration on the photosynthetic performance of the red alga Gracilaria conferta (Rhodophyta) is developed. This is based on the balance between the rate of transport through boundary layers and Michaelis-Menten-type equations for carbon consumption and for production of oxygen and hydroxyl ions. By comparing the theoretical models with experimental data, we found that the mechanism of enhancing photosynthetic rates by increasing water velocity cannot be attributed to enhanced bicarbonate and CO₂ transport, nor to CO₂ as a sole source of carbon. Velocity-facilitated photosynthesis may be due to the enhanced removal of OH^? ions, which inhibit photosynthesis when accumulated on the algal surface. Oxygen had no inhibitory effect on Gracilaria conferta.     

Copper content and amino acid composition of catechol oxidase from clairette grapes

Catechol oxidase was purified 330 × from chloroplasts of Clairette grapes. The MW of the enzyme is 80 000 and its Cu content is half an atom per molecule. The amino acid composition of the enzyme is also described.     

Congenital hypoaldosteronism. Thirteen year follow-up in identical twins.

Identical male twins suffering from congenital hypoaldosteronism due to a rare adrenal enzyme deficiency between corticosterone and aldosterone were followed-upfrom birth till their present age of 13 years. The symptoms of salt loss disappeared and normal growth rate resumed following treatment with DOCA and salt supplementation. Discontinuation of mineralocorticoid administration at the age of 7 years resulted during a 5-year period in a marked decline in their growth rate. Labororatory data revealed a persistent, albeit less pronounced, metabolic impairment. Mineralocorticoid administration was resumed and the twins entered normal puberty and increased their growth rate, emphasizing their need for continued mineralocorticoid administration to maintain adequate growth rate and development.     

Synthesis of 5-aminolevulinic acid-[14C] by cell-free preparations from greening maize leaves

The conversion of 2-ketoglutarate-[¹⁴C] to 5-aminolevulinic acid-[¹⁴C] (ALA) by a cell-free system from maize leaves is described. Optimal conversion was achieved at pH 6.2 using a 20 000 g supernatant after gel filtration through Sephadex G-25. The formation of ALA required Mg²⁺, an amino donor (alanine or glutamate), pyridoxal phosphate and NADH. NADPH was somewhat less effective.