W.C. Elbert

Bio: W.C. Elbert is an academic researcher from United States Public Health Service. The author has contributed to research in topics: Pyrene & Hydrazone. The author has an hindex of 16, co-authored 28 publications receiving 1091 citations.

Polynuclear Aromatic Hydrocarbon Composition of the Atmosphere in some Large American Cities.

Abstract: The air of 14 American cities was examined for the following poly cyclic hydrocarbons: pyrene, benzo [a] pyrene, benzo[e]pyrene, benzo [k] fluoranthene, perylene, benzo [g, h, i]perylene, anthanthrene and coronene. Usually, fluoranthene, chrysene, and benz[a]anthracene were also found in ambient air samples. In all urban samples the concentration of the polycyclic aromatic hydrocarbons was generally greater in winter than in summer. The ratios of benzo[a]pyrene to benzo-[g, h, i]perylene and to coronene are introduced as possible indicators of air pollution due to automobile exhaust fumes or coal combustion pollution.

Biochemical and developmental characterization of multiple forms of catalase in tobacco leaves.

Abstract: Leaf extracts of both Nicotiana tabacum and Nicotiana sylvestris contain multiple forms of catalase (H2O2:H2O2 oxidoreductase, EC 1.11.1.6) which are separable at different pH values by chromatofocusing columns. Marked changes in distribution of these catalases occur during seedling development and leaf maturation. The form of catalase eluting first (peak 1) was predominant during early seedling growth and present at all stages of development. Two more acidic forms (peaks 2 and 3) appeared later and comprised 29% of the total activity by 11 days postgermination. Mature leaves of N. tabacum contained peak 1 catalase, but peaks 2 and 3 represented 62% of the total activity. No interconversion of peaks 1, 2, and 3 was detected. The three forms of catalase differed in thermal stability with peak 1 > peak 2 ≫ peak 3. For N. sylvestris, t½ at 55°C was 31.5 and 3.0 min for peaks 1 and 3, respectively, and for N. tabacum, t½ was 41.5 and 3.2 min, respectively. All forms of catalase in tobacco show peroxidatic (measured as ethanol to acetaldehyde conversion) as well as catalatic activities. However, for both Nicotiana species the ratio peroxidatic/catalatic activity is at least 30-fold higher in peak 3 than in peaks 1 and 2. Chromatofocusing of extracts from spinach leaves separated at least four peaks of catalase activity, one of which had a 10-fold higher ratio of peroxidatic/catalatic activity than the others. Short-term growth (5 days) of tobacco seedlings under atmospheric conditions suppressing photorespiration (1% CO2/21% O2) reduced total catalase activity and caused a decline in peak 1 catalase and a substantial increase in the activity of peaks 2 and 3 relative to air-grown seedlings at the same stage.

Quenching of Fluorescence

Abstract: Fluorescence quenching refers to any process which decreases the fluorescence intensity of a given substance. A variety of processes can result in quenching. These include excited state reactions, energy transfer, complex formation, and collisional quenching. In this chapter we will be concerned primarily with quenching resulting from collisional encounters between the fluorophore and quencher, which is called collisional or dynamic quenching. We will also consider static quenching, which is due to complex formation. Static quenching is a frequent complicating factor in the analysis of dynamic quenching. In addition to the processes described above, apparent quenching can occur due to the optical properties of the sample. For example, high optical densities or turbidity can result in decreased fluorescence intensities. This is a trivial type of quenching which contains little molecular information. Throughout this chapter we will assume such trivial effects are not the cause of the observed decreases in fluorescence intensity.

A rapid method for the chemical estimation of filamentous fungi in plant tissue

Abstract: A sensitive colour reaction is described for estimating fungi which contain chitin. The method is based on the alkaline deacetylation of chitin to chitosan, the glucosamine residues of which are susceptible to deamination with nitrous acid. This yields an aldehyde which is determined colorimetrically with 3-methyl-2-benzothiazolone hydrazone. The observed level of aldehyde, expressed as glucosamine, was related to fungal dry weight by experiments using different fungi grown in vitro. The method, requiring 5 h to complete, has been tested on five phytopathogenic fungi and three hosts, and should be applicable to a wide range of host-pathogen systems.