Karel Martínek

Screening of secreted proteases of Paenibacillus larvae by using substrate-SDS-polyacrylamide gel electrophoresis

Summary This study is focused on a primary proteolytic screening of the secreted products of P. larvae cultures by means of substrate SDS-PAGE and using specific inhibitors for the determination of protease classes. Two- and five-day cultures (cultivation medium: MYPGP broth) were used for primary screening. Proteolytic activity was detected only in gels containing gelatin in the area of 87, 74 and 42 kDa in two-day culture and in the area of 87,74,42 and 40 kDa in five-day culture. By using various protease inhibitors, it was considered that the 87 and 74 kDa stable proteases (most active at pH 7) presented in two-day and five-day culture can be metalloproteases, by virtue of their sensitivity to EDTA, 1, 10-phenantroline and EGTA (metal chelators) in standard concentrations, and by the lack of sensitivity to inhibitors of the other classes of protease. The 40 kDa protease in two-day culture was inhibited also by standard concentration of metal chelators, and was most active at pH 6. The 40 and 42 kDa proteases in five-day culture (most active also at pH 6) were inhibited by 1, 10- phenantroline in 2 mM concentration; the EDTA partially inhibited them at 8 mM concentration. All proteases were partially inhibited by 5 mM DTT in incubation buffers. On the other hand, the 2-mercaptoethanol in sample buffer did not alter the proteolytic activity. The inhibited 87 and 74 kDa proteases (by means of EDTA) can be reactivated by Ca2+ and partial by Fe2+ ions. The 40 kDa proteases in twoday culture can be reactivated by Zn2+ ions. No proteolytic activity was detected on the casein substrate gels.

Observations Concerning the Thickness of Rocks Eroded Between the Cambrian and Bolsovian (= Westphalian C) in Central and Western Bohemia

Abstract Carboniferous outliers are found west of the late Carboniferous West Bohemian basins and also south of the West and Central Bohemian basins. The West Bohemian group is Asturian (= Westphalian D) or younger and is notably coal-bearing, the other group of outliers consists mostly of coal-bearing upper Carboniferous volcaniclastic rocks of Bolsovian (= Westphalian C) and/or Asturian age. They form a discontinuous belt extending through the area between and around the towns of Merklín and Beroun. These rocks are underlain chiefly by rocks of ages varying from the Neoproterozoic or Cambrian up to the Ordovician. If the nappe structure of the Barrandian Lower Paleozoic proposed by Melichar and Hladil (e.g. 1999) is not widely present, then it can be assumed that as much as 1850 m of Lower Paleozoic sediments and volcanics could have been eroded prior to the onset of sedimentation of the Bolsovian rocks. In the upper Carboniferous outliers near Mirošov, Skořice and Kamenný Újezd, where sedimentation began as late as in the Asturian, the thickness of eroded deposits might have been even greater, reaching as much as 3150 m.

Significant hiatuses in the terrestrial Late Variscan Central and Western Bohemian basins (Late Pennsylvanian–Early Cisuralian) and their possible tectonic and climatic links

Abstract Significant changes in the stratigraphy of the Central and Western Bohemian Upper Palaeozoic basins occur during or shortly after hiatuses. The different extent and changes in the depocentres of the Radnice and Nýřany members (Moscovian) in the Plzeň Basin clearly indicate changes in the structure of this basin taking place during a break in sedimentation between these two units (311.9–308.3 Ma). Thick weathered rocks that occur in boreholes in the Mšeno–Roudnice Basin indicate another sedimentation break (305.9–304.1 Ma) between the Nýřany Member and the Týnec Formation (Kasimovian). Another possible hitherto undiscovered hiatus occurred between the Týnec and Slaný formations (Kasimovian–Gzhelian, about 304–303 Ma). The most significant changes in the configuration of the basins occurred between the Slaný and Líně formations (Gzhelian–Asselian, 301.6–300.6 Ma). This is indicated by deeply cut river valleys at the top of the Slaný Formation, by high thickness of weathered deposits occurring immediately beneath the Líně Formation, and mainly by the shift of depocentres from the southern to the northern part of the Central Bohemian basins. The hiatuses between the Radnice and Nýřany members and between the Slaný and Líně formations are accompanied by significant changes in the depocentres, and they are therefore interpreted primarily as tectonic events related to the extensional collapse of the Variscan orogenic belt. By contrast, the hiatuses beneath and above the Týnec Formation are interpreted as being the products of lower sedimentation rates during drier climates, which is consistent with the characteristics of the sediments, correlation with other Central European basins, and with climate models for this period. Due to the characteristics of the Líně Formation, in which the effects of climate aridization are clearly seen, the authors presume that tectonic as well as climatic changes occurred at the hiatus between the Slaný and Líně formations.