Alamethicin appears to allow voltage-dependent lipid exchange ("flip-flop") between leaflets of a planar bilayer. In membranes with one leaflet of phosphatidyl serine and one of phosphatidyl ethanolamine, the shape of the nonactin current-voltage curve accurately reports the difference in surface potential between the two sides of the membrane. The surface potential is itself a good measure of ...

BACKGROUND Hepatic microvesicular steatosis is a clinical manifestation seen in a number of liver diseases. Although the role of mitochondrial beta-oxidation in the development of the disease has been well studied, information on lipid peroxidative damage in liver subcellular organelles is scarce. The present study looked at oxidative stress in hepatic peroxisomes and microsomes in microvesicul...

The lateral diffusion of a fluorescent-labeled phospholipid, phosphatidyl-N-(4-nitrobenzo-2-oxa-1,3,-diazole)ethanolamine, has been measured in binary mixtures of cholesterol and dimyristoyl phosphatidylcholine at temperatures both above and below 23.8 degrees C, the chain-melting transition temperature of this phosphatidylcholine. There is a temperature-composition region, approximately temper...

Sonicated unilamellar liposomes containing phosphatidylethanolamine and palmitoylhomocysteine fuse rapidly when the medium pH is lowered from 7 to 5. Liposome fusion was demonstrated by (i) mixing of the liposomal lipids as shown by resonance energy transfer, (ii) gel filtration, and (iii) electron microscopy. The pH-sensitive fusion of liposomes was observed only when palmitoylhomocysteine (gr...

Here we explore how incorporation of the omega-3 fatty acid docosahexaenoic acid (DHA) into murine leukemia cells (T27A) may alter membrane structure and function. When cells were cultured in DHA-supplemented medium, DHA incorporated rapidly and preferentially into phosphatidyl-ethanolamine (PE), with lesser and slower incorporation into phosphatidylcholine (PC). DHA at low concentrations prefe...

Monolayers of fragments of our rod segments were formed at an air-water interface. The area of these particles was measured as a function of the pH of the aqueous phase. A maximum area was measured at pH 6.5. The film was characterised by measuring the decrease in surface pressure, after compression, and the half time required to reach constant pressure. At a pH between 6 and 7 the decrease in ...

Using cytochrome oxidase and esterase assays as a guide, mitochondria and microsomes were prepared from ox heart homogenate with about 25% cross-contamination of phospholipid. By the same criteria, the lipid complement of well washed myofibrils was essentially microsomal in origin. Approximately 60% of the phospholipid of the whole homogenate was found to be associated with microsomes, about ha...

A promising class of compounds for DNA transfection have been designed by conjugating various polyamines to bile-acid-based amphiphiles. Formulations containing these compounds were tested for their ability to facilitate the uptake of a beta-galactosidase reporter plasmid into COS-7 cells. Dioleoyl phosphatidyl ethanolamine (DOPE) formulations of some of the compounds were several times better ...

The 2001 anthrax mail attacks in the United States demonstrated the potential threat of bioterrorism, hence driving the need to develop sophisticated treatment and diagnostic protocols to counter biological warfare. Here, by performing flux balance analyses on the fully-annotated metabolic networks of multiple, whole genome-sequenced bacterial strains, we have identified a large number of metab...

Previously we demonstrated high concentrations of desmosterol and docosahexaenoic acid (DHA, 22:6 n-3) in monkey testes and sperm. Desmosterol, a cholesterol precursor, is not present elsewhere in the body. High concentrations of DHA are found elsewhere only in the retina and brain. To examine the distribution of these compounds in the heads and tails of sperm, we separated them and determined ...