Spectroscopic Investigation of the Inhibitory Effect of Fatty Acids on Photosynthetic Systems

Fatty acids have a reversible inhibitory effect on respiration and on photo-synthetic action. Investigation of the influence of octanoic acid on the photo-synthetic bacterium Rhodopseudomonas spheroides R-26 indicates that a less efficient energy transfer and decoupling of the light-gathering pigment system from the energy converting reaction centre is responsible for the inhibitory effect.     

Effects of Mineral Salts on Short-term Incorporation of Carbon Dioxide inChlorella

The effects of various mineral salts have been studied, bothsingly and in combination, on the uptake and distribution ofphotosynthetically incorporated carbon-14 in Chlorella. Whenmagnesium sulphate, potassium nitrate, and potassium phosphatewere combined in the same concentrations as are found in thenormal nutrient solution, the uptake of carbon-14 was increasedand more radioactivity was incorporated into the amino-acids,with a decrease in the percentage of radioactivity in the sugarphosphates when compared to the controls in distilled water.The most striking effect of the addition of just one salt wasobtained with salts containing nitrogen, particularly ammoniumchloride, which in one experiment increased the radioactivityfound in the amino-acids from 9.9 per cent. (expressed as percentageof the total soluble radioactivity found in this group of compounds)in the controls to 57 per cent., while the radioactivity inthe sugar phosphates fell from 64 to 7 per cent., correspondingly.The total uptake of carbon dioxide by the cells supplied withammonium chloride was three times as great as that in the controlsin distilled water. The relevance of these findings to the methodology involvedin experiments dealing with the path of carbon in photosynthesisis discussed, with particular emphasis upon the concept of a‘steady state’ and how it is thought this may bestbe achieved.     

Inhibition of rat liver and kidney arginase by cadmium ion

Cadmium ion activates arginase from many species of organisms but is an inhibitor of arginase from many other species. The purpose of this study was to investigate the inhibition of rat liver and kidney arginase by cadmium ion. Rat kidney arginase was inhibited by much lower concentrations of cadmium ion than rat liver arginase. Cadmium ion was a mixed noncompetitive inhibitor of both rat liver and kidney arginase. Cadmium ion enhanced the substrate activation of rat kidney arginase while still inhibiting the enzyme. Cadmium ion prevented the substrate inhibition of rat kidney arginase by fluoride while still inhibiting the enzyme. Cadmium ion also inhibited rat kidney arginase in the presence of manganese ion.     

Rhythmicity of Flowering in Pharbitis nil

When young seedlings of Pharbitis nil are grown under continuous light, except for a single inductive dark period, they flower to a varying degree, depending on when this dark period is given. Plants become sensitive to this induction approximately three days after the seedlings emerge from the soil. The expression of flowering varies in a rhythmic fashion for three or more cycles, when an inductive dark period is given at progressively later times. The time between maximum expression of flowering is 24 hours or somewhat longer. It appears necessary that the inductive dark period be of sufficient duration, to only partially induce the plants to flower for this rhythm to be expressed. Under the conditions employed in this study, this duration is 12 hours. If this rhythm is endogenous, it exists at least from when the plants emerged from the soil since no environmental cues are given after that time, and it raises questions of the interpretations of data from previous studies with this organism.