Ethanol induces release of arachidonic acid but not synthesis of eicosanoids in mouse peritoneal macrophages

Exposure of mouse peritoneal macrophages to ethanol induces a rapid release of arachidonic acid to the extracellular medium. All major classes of phospholipids, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol contribute to this release. Ethanol-induced mobilization of arachidonic acid occurs by deacylation, but it is not accompanied by eicosanoid synthesis. These data suggest that at least two signals are necessary for the release and metabolism of arachidonic acid. Ethanol also activates a phospholipase C which hydrolyzes only phosphatidylinositol, and not its phosphorylated derivatives.     

Testing the “methanochondrion concept”: are nucleotides transported across internal membranes in Methanobacterium thermoautotrophicum?

In order to test the Methanochondrion concept, uptake of adenine nucleotides in various membrane preparations of Methanobacterium thermoautotrophicum was studied. The uptake showed properties which are in general interpreted as indicative of a transport mechanism: (i) kinetics in the time range of minutes, (ii) temperature dependence, (iii) substrate specificity and (iv) failure to remove the substrate by extensive washing.However, nucleotide transport as an interpretation of this uptake can definitely be excluded. Not only an exchange mechanism of the mitochondrial type, but also a general exchange or an uniport mechanism was ruled out. In contrast, the nucleotide uptake was shown to be actually a tight and specific binding of ADP and ATP to binding sites at the interior side of the cell membrane. This was conclusively demonstrated in protoplasts obtained from M. thermoautotrophicum cells. In these protoplasts which do not contain internal membranes also nucleotide binding was observed, but only after disruption of the plasma membrane by osmotic lysis, which leads to the exposure of binding sites.     

Seasonal growth lines in pleistocene scleractinians from barbados: Record potential and diagenesis

Growth line analysis of diagenetically altered scleractinians is only possible if carbonate diagenesis has followed the pathway of aragonite leaching and coeval formation of low magnesium calcite. All other possibilities of aragonite transformation into calcite exclude the preservation of this growth line banding. Examples of these diagenetic patterns are found in the Pleistocene of Barbados.     

Plasmids in the bacterial assemblage of a dystrophic Lake: Evidence for plasmid-encoded nickel resistance

Sixty-two aerobic bacterial strains isolated from the unproductive dystrophic Lake Skärshultsjön (South Sweden) were screened for plasmids. The lake is considered to be an extreme environment because of its high concentration of persistent but nontoxic humic compounds. One-third of the isolates harbored multiple plasmids usually of similar high molecular weights (>25 Mdal). The plasmid-bearing strains were members of the common aquatic taxaPseudomonas spp.,Acinetobacter sp.,Alcaligenes sp.,Aeromonas/Vibrio group, andEnterobacteriaceae (taxonomy is tentative). The majority of isolates displayed multiple resistance to antibiotics and heavy metals. Some of them were capable of degrading aromatic compounds. Three isolates were chosen for curing experiments. Only strain S-68, anAlcaligenes sp., could be cured of one of its two plasmids. It harbored the two cryptic plasmids pQQ32 and pQQ70 of 32 and ca. 70 Mdal, and the latter was segregated during ethidium bromide treatment. Parental strain S-68 was capable of degrading some of nonchlorinated phenolic compounds and displayed resistance to a broad spectrum of antibiotics and the heavy metals Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, and Hg²⁺. Derivative strain S-68-41 lost its resistance to nickel, suggesting segregated plasmid PQQ70 coded for nickel resistance. Transformation experiments to restore nickel resistance in the cured derivative strain were not successful.     

Glucose as a substrate in recombinant strain fermentation technology

Summary Glucose supplements to complex growth media of Escherichia coli affect the production of a recombinant model protein under the control of a temperature-sensitive expression system. The bacterial Crabtree effect, which occurs in the presence of glucose under aerobic conditions, not only represses the formation of citric acid cycle enzymes, but also represses the formation of the plasmid-encoded product even though the synthesis of this protein is under the control of the temperature-inducible lambda P _R-promoter/cl857-repressor expression system. When the recombinant E. coli is grown at a moderate temperature (35° C) with protein hydrolysate and glucose as substrates, a biphasic growth and production pattern is observed. In the first phase, the cells grow with a high specific growth rate, utilizing glucose and forming glutamate as a byproduct. The intracellular level of recombinant protein is very low in this phase. Later, glutamate is consumed, indicating an active citric acid cycle. The degradation of glutamate is accompanied by the intracellular accumulation of high amounts of recombinant protein.     

Glucocorticoid receptor binds cooperatively to adjacent recognition sites.

In order to define the mechanism of synergistic induction mediated by multiple glucocorticoid response elements (GRE), the affinity of the glucocorticoid receptor to a single or duplicated GRE was analyzed by gel retardation, nitrocellulose filter binding and by footprinting experiments. Direct measurement of the relative affinity and indirect determination by competition showed greater than 10-fold higher affinity of the glucocorticoid receptor to a duplicated GRE when compared to a single element. Maximal stability of the GRE-receptor complex was obtained using two closely spaced GREs positioned on the same side of the DNA helix. Increasing the distance or changing the helical position of the GREs considerably increased the off rate of the receptor. DNase I footprinting shows in addition to the protection of the GRE region, an altered pattern in the nonprotected intervening DNA indicating structural alteration of the DNA helix by the receptor bound to adjacent GREs.     

Reactive extraction of penicillin G from mycel-containing broth in a countercurrent extraction decanter

Penicillin was recovered from mycel-containing fermentation broth by direct reactive extraction into a counter-current extraction decanter, Type CA 226-290 of the Westfalia Separator Co., at room temperature via steady state operation. Penicillin concentrations in the feed varied from 3 to 41 g L(-1), Amberlite LA-2 carrier concentrations from 7 to 20 g L(-1)and/or DITDA carrier concentrations from 7.2 to 84 g L(-1), the LA-2-to-penicillin mole concentration ratio from 4 to 6.4, and/or the DITDA-to-penicillin mole concentration ratio was maintained at 2. The throughputs of the fermentation broth (520 to 880 L h(-1)) of the solvent phase (200 to 860 L h(-1)) and the over all throughput (800 to 1750 L h(-1)) were high. Extraction degrees of 72 to 96% were achieved between pH 4.6 and 5.1. Without carriers in the same pH range, extraction degrees of only 17 to 19% were attained. By reducing the pH to 2.3 and in the absence of carriers, the degree of extraction was increased to 61%. However, during the extraction, 6.5% of the penicillin decomposed. At these high throughputs, the steady state was attained within 1 to 4 min. Through the mechanical stress, the length of the hyphae was reduced and the protein content of the broth was increased by 50 to 100%. However, this protein content had no appreciable influence on the phase separation.     

A dynamic theory of coordination of discrete movement

The concepts of pattern dynamics and their adaptation through behavioral information, developed in the context of rhythmic movement coordination, are generalized to describe discrete movements of single components and the coordination of multiple components in discrete movement. In a first step we consider only one spatial component and study the temporal order inherent in discrete movement in terms of stable, reproducible space-time relationships. The coordination of discrete movement is captured in terms of relative timing. Using an exactly solvable nonlinear oscillator as a mathematical model, we show how the timing properties of discrete movement can be described by these pattern dynamics and discuss the relation of the pattern variables to observable end-effector movement. By coupling several such component dynamics in a fashion analogous to models of rhythmic movement coordination we capture the coordination of discrete movements of two components. We find the tendency to synchronize the component movements as the discrete analogon of in-phase locking and study its breakdown when the components become too different in their dynamic properties. The concept of temporal stability leads to the prediction that remote compensatory responses occur such as the restore synchronization when one component is perturbed. This prediction can be used to test the theory. We find that the discrete analogon to antiphase locking in rhythmic movement is a tendency to move sequentially, a finding that can also be subjected to empirical test.