THE CHEMISTRY OF LIGHT EMISSION

Implications of Adenylate Metabolism in Hygiene Assessment: A Review

The assessment of a hygienic state or cleanliness of contact surfaces has significant implications for food and medical industries seeking to monitor sanitation and exert improved control over a host of operations affecting human health. Methods used to make such assessments commonly involve visual inspections, standard microbial plating practices, and the application of ATP-based assays. Visual methods for inspection of hygienic states are inherently subjective and limited in efficacy by the accuracy of human senses, the degree of task-specific work experience, and various sources of human bias. Standard microbial swabbing and plating techniques are limited in that they require hours or even days of incubation to generate results, with such steps as enrichment and colony outgrowth resulting in delays that are often incompatible with manufacturing or usage schedules. Rapid in conduct and considered more objective in operation than visual or tactile inspection techniques, swabbing surfaces using ATP-based assessments are relied on as routine, even standard, methods of hygienic assessment alone or in complement with microbial and visual inspection methods. Still, current ATP methods remain indirect methods of total hygiene assessment and have limitations that must be understood and considered if such methods are to be applied judiciously, especially under increasingly strict demands for the verification of hygiene state. Here, we present current methods of ATP-based bioluminescence assays and describe the limitations of such methods when applied to general food manufacturing or health care facilities.

Recombinant luminescent bacteria for measuring bioavailable arsenite and antimonite

Luminescent bacterial strains for the measurement of bioavailable arsenite and antimony were constructed. The expression of firefly luciferase was controlled by the regulatory unit of the ars operon of Staphylococcus aureus plasmid pI258 in recombinant plasmid pTOO21, with S. aureus RN4220, Bacillus subtilis BR151, and Escherichia coli MC1061 as host strains. Strain RN4220(pTOO21) was found to be the most sensitive for metal detection responding to arsenite, antimonite, and cadmium, the lowest detectable concentrations being 100, 33, and 330 nM, respectively. Strains BR151(pTOO21) and MC1061(pTOO21) responded to arsenite, arsenate, antimonite, and cadmium, the lowest detectable concentrations being 3.3 and 330 microM and 330 and 330 nM with BR151(pTOO21), respectively, and 3.3, 33, 3.3, and 33 microM with MC1061(pTOO21), respectively. In the absence of the mentioned ions, the expression of luciferase was repressed and only a small amount of background light was emitted. Other ions did not notably interfere with the measurement in any of the strains tested. Freeze-drying of the cells did not decrease the sensitivity of the detection of arsenite; however, the induction coefficients were somewhat lower.

Evidence for purinergic innervation of the anococcygeus muscle

1 Fluorescence histochemical localization of quinacrine (which binds to adenosine 5'-triphosphate (ATP)) revealed nerve fibres running singly and in bundles in both rat and rabbit anococcygeus muscle. Single neurone cell bodies and ganglia containing between 2 and 50 cells were also observed.2 Catecholamine fluorescence studies revealed a dense adrenergic ground plexus, but no adrenergic ganglion cells were detected. No acetylcholinesterase-positive nerve fibres or ganglion cells were seen in the rat.3 When the tone was raised with guanethidine, a relaxation in response to field stimulation was revealed, which was unaffected by atropine but blocked by tetrodotoxin.4 Release of ATP increased 3 to 6 times above background during stimulation of these non-adrenergic, non-cholinergic, inhibitory nerves.5 Neither quinacrine staining nor the release of ATP during inhibitory nerve stimulation was affected by 6-hydroxydopamine treatment, which abolished catecholamine fluorescence.6 Exogenous ATP produced relaxation in high tone preparations of the rabbit anococcygeus muscle. ATP produced either contraction or a small relaxation followed by a contraction of the rat anococcygeus muscle, but treatment with low concentrations of the prostaglandin synthesis inhibitor indomethacin, converted the contraction to a relaxation.7 These data are consistent with the view that the anococcygeus muscle is innervated by purinergic inhibitory nerves.

Metabolic dependence of the critical hemolytic volume of human erythrocytes: relationship to osmotic fragility and autohemolysis in hereditary spherocytosis and normal red cells

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