Dipolar relaxation in a lipid bilayer detected by a fluorescent probe, 4''-dimethylaminochalcone.

The dynamic behavior of polar molecules in egg phosphatidylcholine (PC) bilayers has been studied using a membrane fluorescent probe, 4''-dimethylaminochalcone (DMAC). Time and spectrally resolved fluorescence spectroscopy of DMAC incorporated in PC liposomes, as compared to studies of the probe in organic solvents, shows the existence of two independent populations, associated with different extent and speed of dipolar solvent relaxation. The first DMAC population represents approximately 69% of the fluorescence-emitting molecules, has a short fluorescence decay time (0.

Desulfurococcus fermentans sp. nov., a novel hyperthermophilic archaeon from a Kamchatka hot spring, and emended description of the genus Desulfurococcus.

An obligately anaerobic, hyperthermophilic, organoheterotrophic archaeon, strain Z-1312(T), was isolated from a freshwater hot spring of the Uzon caldera (Kamchatka Peninsula, Russia). The cells were regular cocci, 1-4 microm in diameter, with one long flagellum. The cell envelope was composed of a globular layer attached to the cytoplasmic membrane.

Investigation of structure and antigenic capacities of Thermococcales cell envelopes and reclassification of "Caldococcus litoralis" Z-1301 as Thermococcus litoralis Z-1301.

Fourteen strains of hyperthermophilic organotrophic anaerobic marine Archaea were isolated from shallow water and deep-sea hot vents, and four of them were characterized. These isolates, eight previously published strains, and six type strains of species of the order Thermococcales were selected for the study of cell wall components by means of thin sectioning or freeze-etching electron microscopy. The cell envelopes of most isolates were shown to consist of regularly arrayed surface protein layers, either single or double, with hexagonal lattice (p6) symmetry, as the exclusive constituents outside the cytoplasmic membrane.

The spatial structure of lipids in human leukocytes: studies by nonradiative energy transfer.

The spatial structure of lipids in living human lymphocytes and granulocytes has been studied using the energy transfer between lipophilic fluorescent probes. One of the probes, an energy donor (DMC), was localized in the lipid interior, whereas another donor (K-68) and an energy acceptor (DSP-12) were near the lipid/water interface. The energy transfer in lymphocytes was the same as in artificial lipid membranes (liposomes).

Anaerobic extremely thermophilic carboxydotrophic bacteria in hydrotherms of Kuril Islands.

A new group of extremely thermophilic, obligately anaerobic, carboxydotrophic eubacteria is described. The organisms are characterized by a novel type of chemotrophic metabolism in thermophilic environments. They grow at temperatures up to 80-85°C chemolithotrophically with 100% CO in the gas phase as the sole energy source.