Comparison of methods for estimating Erwinia carotovora numbers on potato tubers

Two methods for estimation of the numbers of Erwinia carotovora on potato tubers were compared using 17 naturally infected stocks. The 'wash' method estimates the surface count, whereas the 'peel' method is based on a subcuticular count. A correlation of 0.79 was obtained. Comparisons between methods were also made using a bactericide, Myacide As, and on stocks during chitting. Erwinia carotovora counts were reduced in treated tubers with the 'wash' method, but not with the 'peel' method.     

Aeromedical transport: its hidden problems.

Air transport can move patients safely and rapidly over long distances. However, changes in altitude can have disastrous effects because diminished ambient air pressure may allow gases in closed spaces and tissues to expand rapidly. Even pressurized commercial aircraft do not maintain sea-level pressure: cabin pressures equal to those at yp to 8000 ft may be experienced, diminishing oxygen tension in proportion. Air transport is absolutely contraindicated for patients with untreated pneumothorax, gas gangrene, or air trapped in the cranium and those who have recently undergone abdominal surgery. Special considerations including a planned low-altitude flight are warrented for patients who are anemic, in respiratory or cardiac distress, or immobilized in casts, or who have been engaged in underwater diving immediately before the flight.     

Effects of pressure on uptake and release of calcium by brain synaptosomes

Uptake of radioactive calcium from guinea pig brain fractions enriched in synaptosomes could be significantly and reproducibly decreased by exposure to high pressure. Calcium efflux from preloaded synaptosomes was unaffected by pressure exposure. It was hypothesized that the development of pressure-induced encephalopathy may be related to an effect of pressure on the central nervous system calcium transport system.     

A strategy to study gene polymorphism by direct sequence analysis of cosmid clones and amplified genomic DNA

A two-step strategy is described here to rapidly analyze gene-sequence variation or polymorphism. First, DNA sequences flanking the coding region of the gene to be analyzed are determined directly from a cosmid clone, including the gene, using the modified T7 DNA polymerase and sequencing primers based on the cDNA sequence of the gene. Second, the identified gene-flanking sequences are used to design amplification primers for the polymerase chain reaction (PCR) to permit amplification of DNA segments of up to 1 kilobase in genomic DNA from multiple individuals. These amplified DNA segments are directly sequenced using the thermostable Taq DNA polymerase.     

Effects of phorbol dibutyrate on M currents and M current inhibition in bullfrog sympathetic neurons

1. Effects of bath-applied phorbol dibutyrate (PDBu) on M currents (IM) and on the inhibition of IM by muscarine and luteinizing hormone-releasing hormone (LHRH) were recorded in voltage-clamped bullfrog lumbar sympathetic ganglion cells. 2. PDBu (0.1-30 microM) produced a slowly developing, irreversible and partial (less than or equal to 60%) inhibition of IM. This effect was not replicated by 4-alpha-phorbol or by vehicle. 3. After treatment with PDBu, residual IM showed a reduced sensitivity to inhibition by muscarine or LHRH but not by Ba2+. The reduced response to muscarine appeared to result from a 10-fold shift in the concentration dependence for inhibition. 4. PDBu did not clearly reproduce the ability of muscarine to inhibit the slow, Ca-activated K current IAHP or to increase the leak conductance at hyperpolarized potentials. The latter effect of muscarine was enhanced, rather than inhibited, by PDBu. 5. IM and IAHP were not inhibited by 1 mM dibutyryl cyclic AMP or by 20 microM forskolin. 6. It is concluded that activation of protein kinase C, but not protein kinase A, partly replicates the effect of muscarine on frog sympathetic neurons.     

Phosphorylation of AMP by inorganic phosphorylating agents

AMP was phosphorylated by inorganic phosphorylating agents: cyclo-triphosphate and diphosphonate, in aqueous solution (70-80 degrees C, pH 6-12). The molecular structures of phosphorylated products were established by use of phosphorus-31 NMR and high-performance liquid chromatography (HPLC). The OH groups on AMP were phosphorylated by both phosphorylating agents to form 2'- or 3'-phosphate but an OH group on dAMP was not phosphorylated. Phosphorylation of OH group proceeds in two steps: formation of hydrogen bond between OH group and phosphorylating agent; subsequent nucleophilic attack of OH group on a phosphorus atom. Phosphate group on AMP was phosphorylated by diphosphonate but not by cyclo-triphosphate. The difference in the reactivities is explained in terms of charge repulsion between AMP and agents.