Monitoring the Metabolic State of Fungal Hyphae and the Presence of Melanin by Nonlinear Spectral Imaging

Label-free nonlinear spectral imaging microscopy (NLSM) records two-photon-excited fluorescence emission spectra of endogenous fluorophores within the specimen. Here, NLSM is introduced as a novel, minimally invasive method to analyze the metabolic state of fungal hyphae by monitoring the autofluorescence of NAD(P)H and flavin adenine dinucleotide (FAD). Moreover, the presence of melanin was analyzed by NLSM. NAD(P)H, FAD, and melanin were used as biomarkers for freshness of mushrooms of Agaricus bisporus (white button mushroom) that had been stored at 4°C for 0 to 17 days. During this period, the mushrooms did not show changes in morphology or color detectable by eye. In contrast, FAD/NAD(P)H and melanin/NAD(P)H ratios increased over time. For instance, these ratios increased from 0.92 to 2.02 and from 0.76 to 1.53, respectively, at the surface of mushroom caps that had been harvested by cutting the stem. These ratios were lower under the skin than at the surface of fresh mushrooms (0.78 versus 0.92 and 0.41 versus 0.76, respectively), indicative of higher metabolism and lower pigment formation within the fruiting body. Signals were different not only between tissues of the mushroom but also between neighboring hyphae. These data show that NLSM can be used to determine the freshness of mushrooms and to monitor the postharvest browning process at an early stage. Moreover, these data demonstrate the potential of NLSM to address a broad range of fundamental and applied microbiological processes.     

Seasonal and Spatial Distribution of Phosphates,Nitrates, and Silicates in Lake Champlain,U.S.A.

A study of the limnological characteristics was conducted from January through November, 1970 of Lake Champlain, Vermont and New York, U.S.A. The seasonal and spatial distribution of soluble nitrate, total phosphate and reactive silicate concentrations from 20 stations are presented here. Results for soluble nitrate concentrations indicate that concentrations in the northeast area of the lake are significantly lower throughout the year than the open lake and bay stations in the western main portion of the lake. Three of the shallow bay stations generally had higher concentrations of nitrate than all other stations. Concentrations of reactive silicon dioxide do not show the same general trends as the nitrata data. Silicate concentrations in the western open portions are higher in the winter and lower in the summer than other areas. The northeast arm does not show the dramatic difference in silicates as for nitrate concentrations. The shallow bays had significantly higher silicate concentrations also, especially during peak spring runoff. No detectable soluble phosphate was measured in the surface waters of the lake. Total particulate phosphate concentrations remained relatively constant from station to station, and throughout the season. The results of the measurements of soluble nitrate and silicate generally support the hypothesis that Lake Champlain is composed of a number of distinct water masses. The general pattern of total phosphate concentrations however, does not support this hypothesis. A comparison of the three major nutrients in Lake Champlain with the St. Lawrence Great Lake indicates that the trophic status of Lake Champlain is generally higher than Lake Superior and very similar to the open waters of Lake Michigan and Lake Huron.     

Die Chromosomen vonGinkgo biloba

Zusammenfassung Das Idiogramm vonGinkgo biloba zeigt bei Pflanzen aus dem Botanischen Garten der Universität Wien sowohl im weiblichen als auch im männlichen Geschlecht dieselben chromosomalen Verhältnisse. Von den 12 Chromosomen des haploiden Satzes sind 10 anisobrachial, während 2 submedian inseriert sind; eines dieser beiden zeichnet sich durch besondere Länge aus. Es konnten 2 Satelliten im haploiden Satz aufgefunden werden: der eine hängt am langen Schenkel eines anisobrachialen Chromosoms, der andere befindet sich am fast gleichschenkeligen, längsten Chromosom und sitzt hier an dem etwas kürzeren Schenkel. Die Unterschiede, die andere Autoren für das Idiogramm männlicher und weiblicher Pflanzen beschreiben, können nicht in Zusammenhang mit der Gesehlechtsbestimmung stehen; es handelt sich wahrscheinlich bloß um Fälle von struktureller Hybridität einzelner, zufällig gerade männlicher Bäume.     

Conjugation of lectins with fluorochromes: an approach to histochemical double labeling of carbohydrate components.

Methodical investigations on the coupling of lectins (Con A, LcL, WGA, RcA) to tetramethylrhodamine isothiocyan ate (TRITC) are reported. 20-microgram of TRITC per mg of lectin were found to be the optimal amount of TRITC for the conjugation. With this fluorochrome: protein ratio conjugates were produced which resulted in a specific and brilliant fluorescence in tissue staining. The optimally conjugated lectins were separated on DEAE-Sephadex-A 50. Using two different lectins which were conjugated with TRITC or FITC, respectively, a double labeling of different lectin-binding sites in tissue sections was achieved.     

Establishing Causality between Exposure to Metals and Effects on Fish

This study evaluates causal relationships between chronic exposure of fish to metals and effects at different levels of biological organization based on a weight-of-evidence approach. Criteria for evaluation of causality were strength, consistency, and specificity of the association, as well as biological gradient and plausibility. Field sampling was conducted three times between 1998 and 2000, in Furnas Stream, impacted by an abandoned lead mine, and in three other locations, including two reference and one impacted sites. Levels of Pb, Zn, Cd, and Ag in sediments from the Furnas Stream exceeded background levels, and their concentrations were above sediment quality guidelines. Residual levels of metals in fish tissue were high enough to indicate reduced growth, reproduction and/or survival according to toxicological benchmarks. Lead-induced biochemical changes (ALA-D activity depletion) were observed in two species of siluriform catfish. The condition factor of a predatory catfish was reduced, and the percentage of prey generalists was higher in Furnas than at the noncontaminated sites. Reduction in fish community diversity and density was observed. Integration of data provided supporting evidence that observed effects on fish from the Furnas Stream resulted from long-term exposure to metals, however influences from other stressors cannot be ruled out.     

Interpolating and extrapolating with hmsIST: seeking a t<Subscript>max</Subscript> for optimal sensitivity,resolution and frequency accuracy

Non-Uniform Sampling has the potential to exploit the optimal resolution of high-field NMR instruments. This is not possible in 3D and 4D NMR experiments when using traditional uniform sampling due to the long overall measurement time. Nominally, uniformly sampled time domain data acquired to a maximum evolution time t_max can be extended to high resolution via a virtual maximum evolution time t*_max while extrapolating with linear prediction or iterative soft thresholding (IST). At the high resolution obtainable with extrapolation of US data, however, the accuracy of peak positions is compromised as observed when comparing inter- and intra-residue peaks in a 3D HNCA experiment. However, the accuracy of peak positions is largely improved by spreading the same number of acquired time domain data points non-uniformly over a larger evolution time to an optimal t_max followed by extrapolation to a total t*_max and processing the data with an appropriate reconstruction method, such as hmsIST. To explore the optimum value of experimentally measured t_max to be reached non-uniformly with a given number of sampling points we have created test situations of time-equivalent experiments and evaluate sensitivity and accuracy of peak positions. Here we use signal-to-maximum-noise ratio as the decisive measure of sensitivity. We find that both sensitivity and resolution are optimal when PoissonGap sampling to a t_max of about ½*T₂ ^*. Digital resolution is further enhanced by extrapolating the range of acquired time domain data to 2*T₂ ^* but without measuring experimental points beyond ½*T₂ ^*.