Transport of 14C-L-glycine by the haustorial mycoparasite Tieghemiomyces parasiticus in axenic culture.

Transport of L-glycine by the haustorial mycoparasite Tieghemiomyces parasiticus grown in axenic culture was investigated using endogenously metabolizing cells. Transport occurred against a concentration gradient and required the expenditure of energy supplied by metabolic reactions that were inhibited by catalytic amounts of sodium azide and 2,4-dinitrophenol. The process exhibited both pH and temperature dependence with optima at pH 4 and 35 degrees C, respectively. The energy of activation and Q10 for transport were calculated to be 18,227 cal/mole and 2.82 respectively, between 20 and 30 degrees C. The kinetics of the system were consistent with a mechanism of transport that depended upon a finite number of sites on the cell surface and had a Kt of 1.46 x 10(-5) M. The system for L-glycine transport lacked sterospecificity and was most inhibited in the presence of other neutral amino acids while less inhibition was observed in the presence of the acidic and basic amino acids. These results suggest that L-glycine transport in this mycoparasite occurs by an energy dependent, protein-mediated process characteristic of active transport.     

Pharmaceutical provisions of the FDA Modernization Act of 1997: one year and counting.

The FDA Modernization Act of 1997 represents a notable public policy achievement that was conceived not out of crisis, but rather out of a shared commitment that the FDA can both protect patient health (by assuring drugs are safe and effective) and promote public health (by being given additional resources and new procedural efficiencies to accelerate the review of applications for new medicines). The FDA is conscientiously implementing this important new law, but there are areas where more work is required. On balance, the prospects are that this law will help usher in a much improved era for patients.     

Respiration in energy-transducing membranes of the thermophilic cyanobacterium Mastigocladus laminosus: II. Oxidative phosphorylation

Oxidative phosphorylation was measured in isolated energy-transducing membranes of the thermophilic cyanobacterium Mastigocladus laminosus with NADH-mediated electron transport. This dark phosphorylation was similar to photophosphorylation in its sensitivity to uncouplers and energy-transfer inhibitors. However, photophosphorylation was 20- to 50-times more active than oxidative phosphorylation. The $\text{P}\text{O}$ ratio of oxidative phosphorylation was about 0.2. Besides oxidative phosphorylation, adenylate kinase- and ADP-P_i exchange activity were measured in the dark. The ADP-P_i exchange reaction was identified as polynucleotide phosphorylase.     

Nothobranchius cooperi (Teleostei: Cyprinodontiformes): a new species of annual killifish from the Luapula River drainage,northern Zambia

Nothobranchius cooperi, Nagy, Watters and Bellstedt, new species, is described from seasonal streams and ephemeral pools associated with the upper Mansa River system in the middle Luapula drainage and systems draining into the low-lying area marginal to the southwestern part of Lake Bangweulu, in the Luapula province of northern Zambia. It belongs to the N. brieni species group. Males of Nothobranchius cooperi are distinguished from congeners by the following unique combination of characters: body scales with broad orange posterior margin, forming a highly irregular cross-barred pattern; anal fin fairly uniform orange-red with irregular to regular, light blue-green zone close to the base; caudal peduncle length 1.2–1.3 times its depth; prepelvic length 48.8–51.9% SL; and head depth 75–77% of head length. Genetic divergence of the mitochondrial COI and ND2 genes and nuclear S7 gene support the distinction of the new species from its closest known relative, N. rosenstocki and confirms its position in the N. brieni species group.     

Outer membrane vesiculation of acinetobacter calcoaceticus

For intact cells of A. calcoaceticus 69V susceptibility to hydrophobic agents (antibiotics, dyes) was established. The composition of its outer membrane and comparison with that of a reference strain, A. calcoaceticus CCM 5593 with a blocked hydrophobic pathway, gave no indication of phospholipid bilayer domains as the structural basis of these permeability characteristics. The outer membrane composition together with the data of time-resolved fluorescence anisotropy measurements is indicative of a high state of order of the hydrocarbon region. A. calcoaceticus 69V releases lipopolysaccharide (LPS)-rich membrane vesicles into the growth medium when grown on a hydrophobic carbon source. While the cells contain both R-form and S-form LPS, the LPS released with the vesicles is exclusively of the R-type. The same selectivity with respect to LPS composition was observed when LPS was removed from intact cells by EDTA-NaCl treatment which leads to a break-down of the barrier to hydrophobic agents in A. calcoaceticus CCM 5593. We propose that due to its physical properties, R-form LPS forms tightly packed structures within the membrane which, under certain conditions, become destabilized and liberated into the surrounding medium. As a consequence, a disturbance of the highly ordered lateral molecular arrangement might lead to altered permeability properties of the outer membrane as suggested in one of the two alternative models existing to explain permeability changes observed in deep rough mutant strains of Enterobacteriaceae.