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.     

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.     

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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Rapid localization of Gag/GagPol complexes to detergent-resistant membrane during the assembly of human immunodeficiency virus type 1

During human immunodeficiency virus type 1 (HIV-1) assembly in HIV-1-transfected COS7 cells, almost all steady-state Gag/Gag and Gag/GagPol complexes are membrane bound. However, exposure to 1% Triton X-100 gives results indicating that while all Gag/GagPol complexes remain associated with the detergent-resistant membrane (DRM), only 30% of Gag/Gag complexes are associated with the DRM. Analysis of the localization of newly synthesized Gag/Gag and Gag/GagPol to the membrane indicates that after a 10-min pulse with radioactive [(35)S]Cys-[(35)S]Met, all newly synthesized Gag/GagPol is found at the DRM. Only 30% of newly synthesized Gag/Gag moves to the membrane, and at 0 min of chase, only 38% of this membrane-bound Gag/Gag is associated with the DRM. During the first 30 min of chase, most membrane-bound Gag/Gag moves to the DRM, while between 30 and 60 min of chase, there is a significant decrease in membrane-bound Gag/Gag and Gag/GagPol. Since the localization of newly synthesized Gag/Gag to the DRM and the interaction of GagPol with Gag both depend upon Gag multimerization, the rapid localization of GagPol to the DRM probably reflects the interaction of all newly synthesized GagPol with the first newly synthesized polymeric Gag to associate with the DRM.     

The interaction between HIV-1 Gag and human lysyl-tRNA synthetase during viral assembly

Human lysyl-tRNA synthetase (LysRS) is a tRNA-binding protein that is selectively packaged into HIV-1 along with its cognate tRNALys isoacceptors. Evidence exists that Gag alone is sufficient for the incorporation of LysRS into virions. Herein, using both in vitro and in vivo methods, we begin to map regions in Gag and LysRS that are required for this interaction. In vitro reactions between wild-type and truncated HIV-1 Gag and human LysRS were monitored using GST-tagged molecules and glutathione-agarose chromatography. Gag/LysRS interaction in vivo was detected in 293FT cells cotransfected with plasmids coding for wild-type or mutant HIV-1 Gag and LysRS, either by monitoring Gag.LysRS complexes immunoprecipitated from cell lysate with anti-LysRS or by measuring the ability of LysRS to be packaged into budded Gag viral-like particles. Based on these studies, we conclude that the Gag/LysRS interaction depends upon Gag sequences within the C-terminal domain of capsid (the last 54 amino acids) and amino acids 208-259 of LysRS. The latter domain includes the class II aminoacyl-tRNA synthetase consensus sequence known as motif 1. Both regions have been implicated in homodimerization of capsid and LysRS, respectively. Sequences falling outside these amino acid stretches can be deleted from either molecule without affecting the Gag/LysRS interaction, further supporting the observation that LysRS is incorporated into Gag viral-like particles independent of its ability to bind tRNALys.