Search

Research has been conducted on the metal binding to nucleic acids. The use of the solid-state (super)59 Co MAS NMR spectra in investigating this binding is described.

Author(s): Oscar E. Gaggiotti [1, 2]; Felicity Jones [3]; William M. Lee [1]; William Amos [1]; John Harwood [4]; Richard A. Nichols (corresponding author) [5] The colonization of a new [...]

Research has been conducted on the stannylated oxazolines. The addition of these oxazolines to the bromonaphthoquinones at the carbonyl group vicinal to the bromine atom has been investigated and the results are presented.

Membranes provide the structural framework that divides cells from their environment and that, in eukaryotic cells, permits compartmentation. They are not simply passive barriers that are liable to be damaged during environmental challenge or pathological states, but are involved in cellular responses and in modulating intracellular signalling. Recent data show that the expression of several genes, particularly those that respond to changes in temperature, ageing or disease, is influenced and/or controlled by the membrane's physical state.

13C and 31P cross-polarization magic angle nuclear magnetic resonance was used to study the crytalline forms of the racemic and enantiomerically pure zwitterionic phospholipids. Observed spectra revealed two types of packaging behavior which are dependent on the optical purity of the phospholipids and the structure of the head group. The effect of dipole orientation was found insignificant in liquid crystalline and metastable gel phases.

An examination of the role of oxygen in regulating changes in delta12-desaturase activity during the acclimation of Acanthamoeba castellanii to temperature revealed that oxygen regulates the formation of new delta12-desaturase and the activity of presynthesized enzyme. It is the first report on the role of oxygen in the regulation of desaturase synthesis. These responses can occur separately from temperature changes. Results showed a decline in cellular fatty acid unsaturation and a pronounced decrease in delta12-desaturase activity along with decreased oxygen concentration during growth.

A novel method for using the PhSeH radical clock has been developed. In the method, the clock functions under pseudo-first-order conditions without reagent excess and in which reactions are run to completion. The approach avoids problems posed by the analysis of limited quantities of product in the presence of excess reagent or substrate. PhSeH is also introduced in a catalytic quantity in the form of PhSeSePh.

A study was conducted on the use of multiple-quantum magic-angle spinning (MQMAS) data and its application to spin-3/2 nuclear magnetic resonance (NMR) experiments. The analytical capabilities of MQMAS NMR were demonstrated on a series of sodium salts with identified inequivalent sites. The technique proved to be efficient in determining the values of the isotropic quadrupolar and isotropic chemical shifts of inequivalent locations in powdered samples.

Examination of the phagocytosis in the soil amoeba Acanthamoeba castellanii by flow cytometry reveals that the largest cells of A. castellanii have higher phagocytotic activity than the smallest cells. Rate of rotary agitation of cell suspension and culture age exert significant influence on binding and phagocytosis of beads. Control sodium azide incubations help differentiate between internalization of beads and cell surface binding.

Titrimetry with electronanalytical endpoint detection was used to determine sequestration capacities of polyphosphates for Fe2+ and Fe3+. These methods have the advantage of directly monitoring sequestration of the metal ions. Potentiometry with a divalent ion ion-selective electrode was used to monitor sequestration of Fe2+; polarography was used to monitor sequestration of Fe3+. Four commercial liquid polyphosphate formulations, a Zn-orthophosphate, a silicate formulation, two solid polyphosphates, and pyrophosphate were studied. No significant difference was found in sequestration capacities for either metal ion among the polyphosphates. Polyphosphates were found to sequester only about 14% as much Fe2+ as Fe3+. The polarographic titration affords an efficient, precise method of studying factors affecting sequestration of iron by polyphosphates.

Phagocytosis assay, radioactive counting and lipid analyses of the physiological activities and low-temperature adaptations of Acanthamoeba castellanii lipids to determine the effect of lipid saturation levels on growth indicate that fatty acid unsaturation level, and not cell division or oxygen intake, determines the phagocytotic functions. Stationary-and late-exponential-phase culture chilling causes a significant elevation in the polyunsaturated fatty acid synthesis. Chilling promotes the effect of fatty acid unsaturation level in reducing cell division and oxygen intake.