Comparison of subcellular activation of the human neutrophil NADPH-oxidase by arachidonic acid, sodium dodecyl sulfate (SDS), and phorbol myristate acetate (PMA)

The phorbol myristate acetate (PMA) stimulation of the human neutrophil NADPH-oxidase has been demonstrated through the activation of protein kinase C (PK-C), using light membrane fractions from nitrogen-cavitated cells. Both arachidonic acid (AA) and sodium dodecyl sulfate (SDS) can also generate an active oxidase in cellfree systems. That the source of O2- with AA and SDS activation is the same NADPH-oxidase as previously studied was confirmed by the similar pH optima and Km values for NADPH as those previously described for the O2- -generating activity harvested from pre-stimulated human neutrophils. In contrast to the stimulation by PMA, however, the stimulation of the NADPH-oxidase by AA and SDS does not appear to require protein kinase C activation: the action of AA and SDS is independent of the addition of PK-C cofactors to the system, and the inhibitor of PK-C activity, H-7, had no effect on the stimulation by AA or SDS. AA and SDS activation are comparable, but the level of NADPH-oxidase expression is sixfold greater with each of these agents than that obtained with a reconstituted PK-C system. The basis of this difference in oxidase expression is unclear, but these findings suggest strongly that although activated PK-C is capable of stimulating a dormant NADPH-oxidase in a cellfree system, this is not the sole pathway for oxidase activation.     

Accumulation of mansonones E and F in seedlings of Ulmus americana in response to inoculation with Ophiostoma ulmi

Summary The accumulation of mansonones E and F was investigated in Ulmus americana L. seedlings 5 weeks after inoculation with three aggressive and three non-aggressive isolates of Ophiostoma ulmi (Buism.) Nannf. The three non-aggressive isolates stimulated significantly more mansonone E and F accumulation than the three aggressive isolates of O. ulmi. Mansonone induction also varied within both the aggressive and the non-aggressive groups. Aggressive and non-aggressive isolates were recovered in equal frequencies from the inoculation wounds, whereas the aggressive isolates were recovered more frequently than the non-aggressive isolates 15 cm and 25 cm up the seedlings' stem. Vascular browning in the outer xylem of the seedlings correlated with mansonone E and F accumulation. Mansonone accumulation in U. americana seedlings is therefore associated with vascular browning and a reduction in fungal spread.     

Irreversible inactivation of diacylglycerol kinase-II requires a mediator.

Cytosolic diacylglycerol kinase was irreversibly inactivated by 5'-AMP since the enzyme remained less active after the removal of 5'-AMP by P-10 gel chromatography. The inactivation was time-dependent, suggesting the involvement of a covalent bond modification. A reconstitution experiment detected a rat brain cytosolic mediator for the effect of 5'-AMP. A protein kinase rich fraction prepared from rat liver was also capable of restoring the sensitivity of diacylglycerol kinase-II to 5'-AMP. We propose that 5'-AMP-activated protein kinase is the mediator which inactivates diacylglycerol kinase-II, possibly by phosphorylation.     

Conversion of a primary amine to a labeled secondary amine by the addition of phenolic group and radioiodination

To preserve the nucleophilicity of amino compounds during conjugative radioiodination, a new method for converting primary amines to phenolic secondary amines was developed. Amino acids were used as model compounds for establishing optimal conditions for the reductive amination. In the first step of the reaction, the aldehyde group of 4-hydroxybenzaldehyde (formylphenol) was reacted reversibly with an amino group to form an imine. The irreversible attachment of formylphenol to the amino group was accomplished by reduction of the imine with sodium cyanoborohydride. The pH optimum for the reaction was 5.0. Higher temperature has favorable effects on the rate and extent of the conjugation. Phenolic derivatives of amino compounds suitable for radioiodination are produced by the reactions described.     

ACTIVE GROWTH OF THE OCEANIC DINOFLAGELLATE CERATIUM TERES IN THE CARIBBEAN AND SARGASSO SEAS ESTIMATED BY CELL CYCLE ANALYSIS1

The growth rate of an oceanic dinoflagellate, Ceratium teres Kofoid, was investigated in the Sargasso and Caribbean Seas from September 1989 to July 1990 using the cell cycle analysis method. Estimated growth rates ranged from 0.29 to 0.58 day^?1 and were 1.5–7.2 times higher than generally accepted rates for oceanic dinoflagellates. The higher rates in this report were mainly due to an improvement in techniques that determine the duration of a terminal cell cycle phase in situ. The day-to-day variation in growth rates was surprisingly small, but, from long-term measurements, a weak correlation was found among temperature, daily irradiance, and seasonal growth rate. The calculated species-specific primary production ranged from 0.5 to 1.8 mg C·m^?2·day^?1, about 1% of the estimated total production. Ceratium teres may be an important carbon source at the base of the grazing food chain.