Weathering of Granite from the Damma Glacier Area: The Contribution of Cyanogenic Bacteria

The dissolution potential of five cyanogenic bacteria was studied at 25°C during 32 days using granite material from the Damma glacier (Central Alps, Switzerland) as the sole source of nutrients. The bacterial species Pseudomonas fluorescens and Pseudomonas sp. CCOS 191 were the most effective to exudate various organic acids and consequently mobilized Fe. The molecular mechanisms include both, proton-promoted and ligand-promoted dissolution, preferentially at pH below 5 and in the pH range between 5.0 and 5.8, respectively. In addition, bacterially produced cyanide plays a minor role through the formation of soluble hexacyanoferrate complexes. To our knowledge, this study is the first that reveals the direct measurement of metal-cyanide complexes formed during biotic granite weathering.     

Modellversuche zur überlebensdauer von Erwinia amylovora im Verdauungstrakt der Honigbiene,im Honig und an Teilen des Bienenstocks

An lagerndem Winterknoblauch ist unter außenluft‐(x + 6, 5 bzw. 8, 3 °C) und maschinengekühlten Bedingungen (x‐1 . . .‐2 °C) in zwei Lagerperioden die Entwicklung der einzelnen Fäuleerreger verfolgt und in Abhängigkeit von der Lagerdauer statistisch quantifiziert worden. An Hand des Masseanteiles befallener Zwiebeln und der Befallsintensität wird eine zunehmende Ausbreitung von Penicillium spp. und einer Gruppe mit Befall durch mehrere Fäuleerreger unter beiden Lagerbedingungen und von einer Botrytis‐Species (vermutlich B. porri Buchw.) im maschinengekühlten Lager belegt. Fäuleverluste durch Helminthosporium allii Campanile und Bakterien zeigen dagegen mit fortschreitender Lagerdauer einen abnehmenden Verlauf. Mit Eintreten von lagerungsbedingter Seneszenz steigen die Verluste progressiv an. Kaltlagerbedingungen verzögern dagegen ihre Ausbreitung. Die Verluste durch alle Fäulerreger (Fäule gesamt) zeigen eine gleichmäßige Zunahme während der Lagerdauer.     

Inactivation of glutamine synthetase by adenylylation in intact cells of E. coli

Summary The adenine pool of a purineless mutant of E. coli was radioactively labelled by short incubation with ¹⁴C-adenine.The glutamine synthetase was inactivated in vivo by incubation of the cell suspension with 2x10^-3 M NH₄ ⁺ for 2 min. The inactivated glutamine synthetase was extracted from the cells and purified 20-fold.Incubation of the purified glutamine synthetase with phosphodiesterase regenerated the biosynthetic activity of the enzyme paralleled by the liberation of ¹⁴C-adenine and ¹⁴C-adenosine. ¹⁴C-adenine and ¹⁴C-adenosine were also obtained when inactivated glutamine synthetase, prepared in vitro by use of ¹⁴C-ATP and purified adenylylating enzyme, was incubated with phosphodiesterase under the same conditions.The similar liberation of adenine derivatives by phosphodiesterase from glutamine synthetase inactivated in a cell-free system as well as in intact cells, demonstrates that in both cases the inactivation consists in an adenylylation of the enzyme.     

Ein einfaches Mikrokolorimeter

Ohne Zusammenfassung     

Unterschiede im revier- und sexualverhalten endemisch-anatolischer zahnkarpfen (pisces,cyprinodontidae)

The endemic Anatolian cyprinodonts Aphanius chantrei, A. (Kosswigichtys) asquamatus, and A. anatoliae show definite interspecific differences in their territorial and sexual behaviour under laboratory conditions. Intraspecific differences were found in the nine populations of A. anatoliae investigated.A. chantrei and Kosswigichthys show almost the same territorial behaviour. In A. anatoliae territoriality is found in three populations; the remaining six populations show no territoriality.The sexual behaviour consists of visual display elements and of elements which enable the fish to keep close contact without actually touching each other. The sequence of elements can be variable. Only two populations of A. anatoliae have retained display elements; the remaining seven populations have lost all of them.A correlation is discussed between biotope conditions and sexual behaviour. Display and territorial behaviour may have become superfluous in extreme, sulphate-containing habitats, where a lack of flora has led to a lack of spawning sites. Under changing breeding conditions the newly evolved element with fish staying close together (male underneath the female) may have replaced the former display elements.     

Two types of heat tolerance in FHM-cells. Induction by heat-shock versus elevated culturing temperature

1. 1.Increased heat tolerance in FHM-cells from Pimephales promelas (Pisces) can be induced by culturing the cells at elevated temperatures (heat resistant acclimation) as well as by heat shock (heat hardening).

2. 2.After shift of culturing temperature (CT) from 16 to 32°C both effects are detectable with different temporal patterns.

3. 3.Cellular concentrations of heat-shock proteins correlate with the hardening effect but not with heat resistance acclimation.

4. 4.Several culturing temperature specific proteins were detected. The patterns of some enzymes are also altered by culturing temperature.

5. 5.Heat resistance acclimation is not caused by selection of a thermoresistant subpopulation of cells.

6. 6.Heat hardening and heat resistance acclimation must be distinguished as different phenomena in FHM-cells.

Energy-dependent receptor activities of Escherichia coli K-12: mutated TonB proteins alter FhuA receptor activities to phages T5, T1, ⊘80 and to colicin M

Abstract The activity of the FhuA receptor in the outer membrane of Escherichia coli is dependent on the TonB, ExbB and ExbD proteins which are anchored to the cytoplasmic membrane. Only infection by phage T5 occurs independently of TonB, ExbB and ExbD. In this paper we describe mutated FhuA proteins which displayed either an increased or decreased FhuA activity to phage T5 when combined with mutated TonB proteins. These results suggest conformational changes in FhuA by TonB which are recognized by phage T5. Similar results were obtained with colicin M and the phages T1 and ⊘80. It is proposed that the FhuA mutant proteins assume conformations which are either improved or impaired by the TonB derivatives. For the direct interaction of FhuA with TonB regions which are located outside the TonB box of FhuA and the region around residue 160 of TonB are important.     

Structure and mechanism of action of riboflavin-binding protein: Small-angle X-ray scattering,sedimentation, and circular dichroism studies on the holo- and apoproteins

Riboflavin-binding protein, a transport protein occurring in egg whites, binds riboflavin tightly at pH values above 4.5 but releases it readily at pH values below 4.0. Structural aspects of this biologically important binding were studied by several methods. Analysis of sedimentation equilibrium data gave an average molecular weight of 32,500 ± 1000 for all forms of the protein and showed the absence of changes in quaternary structure when riboflavin was bound at neutral pH or released at pH 3.7. Sedimentation velocity showed no change in tertiary structure on binding at pH 7.0 but revealed a significant change in sedimentation constant at pH 3.7. While circular dichroism showed no appreciable change in secondary structure, it gave evidence of a marked change in the aromatic region at the lower pH. Small-angle X-ray scattering, going from the holoprotein at neutral pH to the apoprotein at low pH, showed a small but significant increase in radius of gyration (19.8 ± 0.2 vs 20.6 ± 0.1 Å) with slightly decreased anisotropy and with substantial increases in molecular volume (55,600 ± 530 vs 66,500 ± 240 ų), surface (11,840 ± 120 vs 13,470 ± 140 Å), and hydration (0.27 ± 0.01 vs 0.38 ± 0.01 g H₂O/g dry protein). Hydration values were obtained from small-angle X-ray scattering in two different ways for comparison with those calculated from sedimentation coefficients by way of frictional coefficients (derived from two different dimensionless ratios based independently on the structural small-angle X-ray scattering data). For either form of the protein, the surface calculated from an ellipsoidal model could account for only about 62% of the surface found experimentally. The excess surface was ascribed to topographic features of the molecule. Relative changes in this new parameter, together with the circular dichroism data and the known association of riboflavin binding with aromatic residues, suggested the opening of an aromatic-rich cleft concomitant with the release of riboflavin as a consequence of lowered pH.