Water-stress influenced on CAM activity of Kalanchoe integrifolia

Experiments were performed to test the changes which may occur in the activity of the Crassulacean-acid metabolism [CAM] as exhibited by the succulent Kalanchoe integrifolia in response to their water status. When the plant water status was lowered by witholding water or by irrigation with 2% NaCl, a change from a typical CAM to a CAM-idling occurs. Water is conserved and low levels of metabolic activity are maintained during water stress by stomatal closure yet little fluctuation of organic acids occurs. Under the mode of dampened CAM the survival of plants that were held waterless for relatively long periods was possible. The result are discussed in relation to physiological significance and evolution- of the CAM-idling mode of metabolism

effects of uncoupling agents on nitrite uptake by Scendesmus obliquus

Light increased the capacity for nitrite absorption by Scenedesmus obliquus posaibly through the increased energy supply and/or the increased nitrite reductase activity. Assimilation was observed when normal algal cells were illuminated in the absence of CO[2]under aerobic condition. The rate of assimilation by-carbohydrate-deficient cultures depends on light and the presence of CO[2]. The failure of illuminated carbohydrate-deficient cells to reduce nitrite in absence of CO[2] seems to be due to the exhaustion of the respiratory substrates in the cells. The effect of uncoupling agents was studied in an attempt to clarify the relation between the photochemical reductant and the reduction of nitrite. Addition of DNP or KCN inhibited the utilization of nitrite by about 80% compared to about 28 percent with DCMU. Under heterotrophic conditions inhibition was almost the same. These results indicate that high energy phosphate is involved in the assimilation of nitrite by this alga

occurrence of Phytoplankton and some relation to physico-chemical characteristics in the Ismailia canal

Qualitative and quantitative estimations of phytoplankton and their relation to physicochemical characteristics along the Ismailia Canal were conducted between 1976 and 1983. Three major groups were found namely, Chlorophyceae, Cyanophpceae and the Bacillariophyceae. Diatoms were the most abundant group throughout the investigation. Phytoplankton densities usually fell between 105 to 106 organism per litre. Concentrations of Chlorophyll a contents fluctuated between 3.5 to 17.6 micro g/1. There was no apparent indication of pollution as evidenced by the phytoplanktonic diversity, autotrophic index, ammonia, nitrite, contents and COD and BOD estimations