Die Beeinflussung der Histochemisch Nachweisbaren ATPase-Aktivität unter verschiedenen Versuchsbedingungen beim Vergleich der Ca- sowie Pb-Methode bei Ph 7,5 bzw. 7,2

Zusammenfassung Es wird über vergleichende Untersuchungen beim Nachweis der ATPase im niederen pH-Bereich unter Verwendung der Ca- und Pb-Methode berichtet. Hierbei zeigt es sich, daß es sich um ATPasen mit unterschiedlichen Eigenschaften handelt. Während die ATPase pH 7,2 keine Abhängigkeit von SH-Gruppen aufweist und Mg^.. benötigt, wird die Aktivität der ATPase pH 7,5 (Ca-Methode) durch SH-Gruppen-Blocker gehemmt, es tritt eine Aktivitätsminderung nach Zugabe von Mg^.. ins Inkubationsmedium ein. Auch der Einfluß der Fixierung ist bei beiden ATPasen unterschiedlich. Unabhängig hiervon ist hervorzuheben, daß sich auch Unterschiede im Verhalten der ATPase in Abhängigkeit vom untersuchten Organ ergeben. Unsere Ergebnisse unterstützen die Notwendigkeit eines spezifischen, von der Fragestellung bestimmten, Nachweises der ATPase.

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Summary The results of comparative studies on the determination of ATP-ase in the low pH range (using the Ca- and the Pb-method) are reported. The findings show that there are ATP-ases of different properties. Whereas ATP-ase pH 7.2 depends not on SH-groups but on the presence of Mg^.., the activity of ATP-ase pH 7.5 (Ca-method) is inhibited not only by SH-group blockers but also by the addition of Mg^.. to the incubation medium. There is also evidence that fixation has varying effects on ATP-ases. However, it must be emphasized that there are differences in the ATP-ase activity within the various organs investigated. Our results show that the choice of the method for a specific demonstration of ATP-ase depends to a very high degree on the problem under investigation.

     

Environmental heterogeneity determines the ecological processes that govern bacterial metacommunity assembly in a floodplain river system

How diversity is structured has been a central goal of microbial ecology. In freshwater ecosystems, selection has been found to be the main driver shaping bacterial communities. However, its relative importance compared with other processes (dispersal, drift, diversification) may depend on spatial heterogeneity and the dispersal rates within a metacommunity. Still, a decrease in the role of selection is expected with increasing dispersal homogenization. Here, we investigate the main ecological processes modulating bacterial assembly in contrasting scenarios of environmental heterogeneity. We carried out a spatiotemporal survey in the floodplain system of the Paraná River. The bacterioplankton metacommunity was studied using both statistical inferences based on phylogenetic and taxa turnover as well as co-occurrence networks. We found that selection was the main process determining community assembly even at both extremes of environmental heterogeneity and homogeneity, challenging the general view that the strength of selection is weakened due to dispersal homogenization. The ecological processes acting on the community also determined the connectedness of bacterial networks associations. Heterogeneous selection promoted more interconnected networks increasing β-diversity. Finally, spatiotemporal heterogeneity was an important factor determining the number and identity of the most highly connected taxa in the system. Integrating all these empirical evidences, we propose a new conceptual model that elucidates how the environmental heterogeneity determines the action of the ecological processes shaping the bacterial metacommunity.Subject terms: Community ecology, Microbial ecology     

Identification of Medieval Human Soft Tissue Remains in an Advanced State of Decomposition

Naturally preserved human soft tissue remains from mediaeval burials (ll-13th century A. D.) were investigated histologically after azocarmine/aniline alcohol (AZAN) or keratin-prekeratin-mucin (KPM) staining. The tissue remnants were in an advanced state of decomposition; they were completely collapsed and had lost their macroscopic characteristics. After rehydration, thin sectioning, and staining, microscopic properties permitted tissue identification, although differential staining of tissue components did not necessarily correspond with the expected results based on fresh tissue. The techniques and results presented in this paper are relevant for both anthropological and forensic purposes.     

Nephronophthisis-Associated CEP164 Regulates Cell Cycle Progression,Apoptosis and Epithelial-to-Mesenchymal Transition

We recently reported that centrosomal protein 164 (CEP164) regulates both cilia and the DNA damage response in the autosomal recessive polycystic kidney disease nephronophthisis. Here we examine the functional role of CEP164 in nephronophthisis-related ciliopathies and concomitant fibrosis. Live cell imaging of RPE-FUCCI (fluorescent, ubiquitination-based cell cycle indicator) cells after siRNA knockdown of CEP164 revealed an overall quicker cell cycle than control cells, although early S-phase was significantly longer. Follow-up FACS experiments with renal IMCD3 cells confirm that Cep164 siRNA knockdown promotes cells to accumulate in S-phase. We demonstrate that this effect can be rescued by human wild-type CEP164, but not disease-associated mutants. siRNA of CEP164 revealed a proliferation defect over time, as measured by CyQuant assays. The discrepancy between accelerated cell cycle and inhibited overall proliferation could be explained by induction of apoptosis and epithelial-to-mesenchymal transition. Reduction of CEP164 levels induces apoptosis in immunofluorescence, FACS and RT-QPCR experiments. Furthermore, knockdown of Cep164 or overexpression of dominant negative mutant allele CEP164 Q525X induces epithelial-to-mesenchymal transition, and concomitant upregulation of genes associated with fibrosis. Zebrafish injected with cep164 morpholinos likewise manifest developmental abnormalities, impaired DNA damage signaling, apoptosis and a pro-fibrotic response in vivo. This study reveals a novel role for CEP164 in the pathogenesis of nephronophthisis, in which mutations cause ciliary defects coupled with DNA damage induced replicative stress, cell death, and epithelial-to-mesenchymal transition, and suggests that these events drive the characteristic fibrosis observed in nephronophthisis kidneys.     

Structure Elucidation,Antimicrobial and Cytotoxic Activities of a Halimane Isolated from Vellozia kolbekii Alves (Velloziaceae)

A new halimane diterpene was isolated from Vellozia kolbekii Alves (Velloziaceae) and identified as (5R,8R,9S,13R)‐halim‐1,10‐ene‐15,16‐diol ( 1 ). It showed cytotoxicity against three human cancer cell lines, SF‐295 (glioblastoma), MDA‐MB‐435 (melanoma), and HCT‐8 (colon adenocarcinoma). In the mechanism of cytotoxic action, halimane 1 interferes in two major phases of the cell cycle: in S phase, in which DNA synthesis occurs and where it is very sensitive to damage, and G2M phase which is the phase of preparation for mitosis and mitosis itself, showing apoptosis‐inducing properties. Antimicrobial activity towards Gram‐positive and Gram‐negative bacteria was studied and, against Bacillus cereus, B. subtilis, Escherichia coli, and Pseudomonas aeruginosa, a MIC value of 0.025 μM was observed for halimane 1 , which is more active than the positive control chloramphenicol.