Wichtigere neue Funde von Phanerogamen in Nordtirol

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Effect of environmental parameters on the efficiency of biodegradation of basalt rock by fungi

The biodegradation of an aluminum-bearing (basalt) rock by Penicillium simplicissimum has been investigated. This organism grows on a sugar substrate and releases organic acid compounds. These acids interact with the mineral matter and cause their partial decomposition. The dissolved metals are then complexed by the excess organic acids. The activity of the fungi was found to be optimum at an initial pH 7 and in the presence of 5% (w/v) substrate concentration. In 30 days of leaching almost 20% of the aluminum in the rock was solubilized and the pH was decreased from 7 to less than 3.5 in the inoculated flasks. The controls showed less than 1% of the aluminum solubilized and the final pH dropped to only 6.8. A surface characterization study performed by scanning electron microscopy indicated that the specific mineralogical phases containing aluminum and iron within this host rock were preferentially corroded. The mineral phases containing olivine and plagioclase were found to be least resistant, while phases containing titanium were most resistant to the acids released by the fungi.     

Water Balance in Cucumis Plants, Measured by Nuclear Magnetic Resonance, I

In this paper we demonstrate the study of plant water balanceby the non-invasive measurement of tissue water content andwater flow using proton nuclear magnetic resonance (NMR). Sapvelocity and flux were measured independently in the presenceof an excess of stationary tissue water. The instrumentationdescribed allows automated and unattended measurement of flow-and water content-variables in a well-defined region of theplant over periods of several days, with a time resolution betweensuccessive measurements of c. 5 s. Using this apparatus theeffect of changes in light intensity (day/night rhythm) andrelative humidity on stem tissue water content as well as onthe velocity and flux of xylem sap in the stem were investigatedin a cucumber plant. The results are in agreement with predictionsfrom a simple model for plant water balance, which is basedon water potential, flow rate and resistance to flow. As longas only transpiration is varied, flow rate and water content(or potential) are affected in opposite ways as demonstratedin this paper. In contrast, the model predicts that changesin uptake (resulting from changes in, for example, root resistance)will induce changes in water content and flow in the same direction.An experimental verification of this prediction is given ina subsequent paper, where, in addition, the NMR results arecompared to those obtained with a dendrometer. Key words: Water balance model, Cucumis sativus L., flow, water content, NMR, water balance measurement     

Melanin standard method: particle description.

Melanin isolated from the ink sac of Sepia officinalis (Sepia melanin) has been proposed as a standard for natural eumelanin. There are no standard methods for the isolation, purification, and storage of melanins. Mild methods designed to preserve the native composition and structure of melanin are needed. The specific aim of the present work, using Sepia melanin, was to develop a mild and generally applicable protocol for the isolation and purification of melanins. It is well established that melanin polymers contain a large number of free carboxylic acid residues. These anionic residues are responsible for the cation exchange properties observed for melanins. Heating melanins with hydrochloric acid at reflux has been demonstrated to lead to extensive decarboxylation. Indeed, heat alone has been shown to cause decarboxylation, and care must be exercised to avoid such conditions. By analogy with cation exchange resins, melanins should be isolated and named according to the associated counterion (e.g., Sepia melanin--K+ form). The method reported here avoided extremes in pH and temperature, and was designed to yield melanin in the K+ form. Physical disaggregation of particulate melanin using a wet milling step was also found to facilitate removal of significant quantities of adsorbed protein. The following physical parameters were used to monitor the purification and to characterize the resultant melanin: pH, conductance, particle size, and diffuse reflectance spectroscopy.     

Melanin standard method: empirical formula.

Melanin isolated from the ink sac of cuttle fish (Sepia melanin) is a proposed standard for natural eumelanin. Sepia melanin isolated by a standard protocol was submitted for both elemental analysis and quantitative amino acid analysis. The contribution of the detected amino acids to the elemental composition is subtracted from the total elemental analysis, and the resultant elemental composition reflects the composition of the Sepia melanin backbone chromophore. The assumption is made that, for eumelanins, there is only one nitrogen atom per monomeric unit, and thus, the empirical formula for the average monomeric Sepia melanin backbone chromophore was determined. Three key parameters can be determined for any melanin sample; namely, the molar C/N for the average monomeric unit, the formula weight of the average monomeric unit, and the total percent composition of amino acid residues. Three commonly used melanin preparations, namely, natural Sepia melanin, melanin prepared by the in vitro tyrosinase catalyzed polymerization of tyrosine (tyrosine-enzymatic melanin), and a polymer synthesized by the peroxide oxidative polymerization of tyrosine (tyrosine-chemical melanin), have been subjected to this standard method of characterization. Tyrosine-enzymatic and Sepia melanin are quite similar and tyrosine-chemical melanin is fundamentally different from the other two melanins.     

TASTE GROUP THRESHOLDS AND SENSORY EVALUATION OF SPANISH WINE VINEGARS

Wine vinegar is a product obtained from wine acidification which contains at least 5% by wt. of acetic acid, in general without any additives or colorings.
Aspects studied in this work include: the determination of the taste group thresholds (geometric mean of the individual best-estimate thresholds "BET") of two different acids (citric and acetic acids) in aqueous solution and spanish vinegars produced from table and sherry wines. The results obtained suggest that wine vinegar can be considered something more than just an acidulant agent.
In order to evaluate differences among wine vinegars, discriminant tests for twenty-five spanish vinegars (sherry, table and flavored vinegars) were applied. Six of the twelve attributes freely chosen by assessors allowed grouping of the spanish wine vinegars according to their sensory aspects.     

Arginine deprivation in KB cells: I. Effect on cell cycle progress

When exponentially growing KB cells were deprived of arginine, cell multiplication ceased after 12 h but viability was maintained throughout the experimental period (42-48 h). Although tritiated thymidine ([(3)H]TdR) incorporation into acid-insoluble material declined to 5 percent of the initial rate, the fraction of cells engaged in DNA synthesis, determined by autoradiography, remained constant throughout the starvation period and approximately equal to the synthesizing fraction in exponentially growing controls (40 percent). Continous [(3)H]TdR-labeling indicated that 80 percent of the arginine-starved cells incorporated (3)H at some time during a 48-h deprivation period. Thus, some cells ceased DNA synthesis, whereas some initially nonsynthesizing cells initiated DNA synthesis during starvation. Flow microfluorometric profiles of distribution of cellular DNA contents at the end of the starvation period indicated that essentially no cells had a 4c or G2 complement. If arginine was restored after 30 h of starvation, cultures resumed active, largely asynchronous division after a 16-h lag. Autoradiographs of metaphase figures from cultures continuously labeled with [(3)H]TdR after restoration indicated that all cells in the culture underwent DNA synthesis before dividing. It was concluded that the majority of cells in arginine-starved cultures are arrested in neither a normal G1 nor G2. It is proposed that for an exponential culture, i.e. from most positions in the cell cycle, inhibition of cell growth after arginine with withdrawal centers on the ability of cells to complete replication of their DNA.     

Inhibition of in Vivo Conversion of Methionine to Ethylene by l-Canaline and 2,4-Dinitrophenol

l-Canaline, a potent inhibitor of pyridoxal phosphate-mediated reactions, markedly inhibited the conversion of methionine to ethylene and carbon dioxide by apple tissue. A 50% inhibition of methionine conversion into ethylene was obtained with 50 mum canaline and almost complete inhibition with 300 mum canaline. When 2,4-dinitrophenol, an oxidative phosphorylation uncoupler, was fed to apple tissue, it inhibited the conversion of radioactive methionine to ethylene by 50% at a concentration of 60 mum and by 90% at a concentration of 100 mum. Production of labeled carbon dioxide from acetate-1-(14)C was increased by 2,4-dinitrophenol, indicating that the inhibition of ethylene production was due to uncoupling of phosphorylation. Auxin-induced ethylene production by mungbean (Phaseolus mungo L.) hypocotyl sections was similarly inhibited by these inhibitors.These results support the proposal that pyridoxal phosphate is involved in the formation of ethylene from methionine, substantiate the requirement for ATP in ethylene production, and suggest that this ATP requirement occurs in the step (s) between methionine and ethylene. The biosynthetic mechanism probably involves activation of methionine by ATP followed by a pyridoxal phosphate-mediated gamma-elimination.     

Zur systematischen Stellung derGaleopsis Murriana Borb. et Wettst

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