The induction of allophanate lyase during the vegetative cell cycle in light-synchronized cultures of Chlamydomonas reinhardi.

Allophanate lyase can be induced by urea or acetamide 20-40-fold within 4 h in NH4 + -deprived cultures of Chlamydomonas reinhardi. In light-synchronized cultures, allophanate lyase induction appeared to be limited to the light phase of the cell cycle, provided that culture samples were induced under ongoing illumination conditions (i.e. light induction of light phase cells and dark induction of dark phase cells). However, when culture samples were induced under constant light conditions this cell cycle pattern was abolished. Light was found to be required for allophanate lyase induction and this was shown to be due, in part, to the light requirement for inducer uptake. The relationship between allophanate lyase induction and gametogenesis is discussed.     

Phosphatidylcholine synthesis in castor bean endosperm: the localization and control of CTP: choline-phosphate cytidylyltransferase activity

The reaction catalyzed by CTP:choline-phosphate cytidylyltransferase (EC 2.7.7.15) has been postulated to be a control reaction in the synthesis of phosphatidylcholine (PtdCho) in many animal tissues and some plants. In 3-day-old castor bean (Ricinus communis L. var. Hale) endosperm the majority of cytidylyltransferase activity resided in a 12,000gav 10-min pellet. Following density-gradient fractionation, 60 to 70% of the enzyme activity was associated with the endoplasmic reticulum (ER) fraction, with the remainder in the particulate fraction being in an unidentified membrane band (band A), less than occurred in the soluble fractions. The properties and kinetics of the forward and reverse reactions are described. About 40% of the total ER activity could be solubilized by treatment of the fraction with 0.32 M KCl, which resulted in a threefold increase in the specific activity of the enzyme. The Michaelis constants of the solubilized enzyme were similar to those of the ER activity. The activity of the solubilized enzyme was stimulated 35% by addition of phosphatidylglycerol or phosphatidylinositol to the assay. Addition of a number of other phospholipids to the incubation medium caused only a small change in activity (+/- 10%) but the enzyme could be stimulated up to 60% by the addition of 0.01-1 mM sodium oleate. A combination of 0.25 mM PtdCho with oleate in the assay resulted in additional stimulation at all concentrations of oleate. Oleate had no effect on the ER activity. These results are discussed in relation to the regulation of cytidylyltransferase activity in plants.     

Alteration of the omega-3 fatty acid desaturase gene is associated with reduced linolenic acid in the A5 soybean genotype

Reducing the linolenic acid (18?:?3^{ω? 3,6,9}) concentration of soybean [Glycine max (L.) Merr.] oil may lessen the need for chemical hydrogenation and enhance flavor stability. Soybean genotypes A5 and A23 have reduced linolenic acid concentration compared with current cultivars. Seed linolenic acid is synthesized primarily by the ω-3 fatty acid desaturase located in the microsomes. The objective of this research was to study whether this enzyme has a role in reducing the fatty acid levels in the soybean genotypes A5 and A23. DNA from A5 and A23 was analyzed by gel-blot hybridization with a cDNA encoding the ω-3 fatty acid desaturase. A5 and lines selected from it have a DNA fragment missing compared to A23 and lines with normal linolenic acid concentration. Seventy F_4:5 lines from a population segregating for linolenic acid concentration were scored for presence or absence of the fragment. The absence of the fragment was significantly (P?0.0001) associated with a reduced linolenic acid level and accounted for 67% of the variation for linolenic acid in the population. These results suggest that the reduced linolenic acid concentration in A5 was at least partially the result of a full or partial deletion of a microsomal ω-3 desaturase gene. No DNA polymorphisms were found for the desaturase gene in A23, so no mutations could be studied in this line.     

Correlation of blood rheology with vascular resistance in critically ill patients.

Blood rheologic measurements together with peripheral resistance determinations in vivo were made in 27 critically ill patients. Eighteen of these patients (group I) suffered from violent trauma or operative injury and the other 9 (group II) were patients with generalized sepsis. As a result of fluid therapy all patients underwent hemodilution, resulting in a decrease in blood viscosity. This drop in blood viscosity was counteracted to some extent by an increased plasma viscosity due to elevated fibrinogen levels and a decreased red cell deformability associated with massive transfusions of stored blood. The correlation of vivo hemodynamics with blood rheological data made it possible to separate the relative roles of vascular dimensions and blood viscosity in affecting the total peripheral resistance. This approach permitted us to distinguish varying degrees of vasoconstriction in nonseptic patients in low flow states (group I) and varying degrees of vasodilation in septic patients (group II). This type of analysis serves to elucidate the pathophysiology of hemodynamic alterations in disease and provides a rational basis for devising an effective therapeutic program.     

Discovery of N-{[1-(propylsulfonyl)-4-pyridin-2-ylpiperidin-4-yl]methyl}benzamides as novel,selective and potent GlyT1 inhibitors

Employing an iterative analogue library approach, novel potent and selective glycine transporter 1 (GlyT1) inhibitors containing a 4-pyridin-2-ylpiperidine sulfonamide have been discovered. These inhibitors are devoid of time-dependent CYP inhibition activity and exhibit improved aqueous solubility versus the corresponding 4-phenylpiperidine analogues.