Augmented expression of polysaccharide intercellular adhesin in a defined Staphylococcus epidermidis mutant with the small-colony-variant phenotype

While coagulase-negative staphylococci (CoNS), with their ability to form a thick, multilayered biofilm on foreign bodies, have been identified as the major cause of implant-associated infections, no data are available about biofilm formation by staphylococcal small-colony variants (SCVs). In the past years, a number of device-associated infections due to staphylococcal SCVs were described, among them, several pacemaker infections due to SCVs of CoNS auxotrophic to hemin. To test the characteristics of SCVs of CoNS, in particular, to study the ability of SCVs to form a biofilm on foreign bodies, we generated a stable mutant in electron transport by interrupting one of the hemin biosynthetic genes, hemB, in Staphylococcus epidermidis. In fact, this mutant displayed a stable SCV phenotype with tiny colonies showing strong adhesion to the agar surface. When the incubation time was extended to 48 h or a higher inoculum concentration was used, the mutant produced biofilm amounts on polystyrene similar to those produced by the parent strain. When grown under planktonic conditions, the mutant formed markedly larger cell clusters than the parental strain which were completely disintegrated by the specific beta-1,6-hexosaminidase dispersin B but were resistant to trypsin treatment. In a dot blot assay, the mutant expressed larger amounts of polysaccharide intercellular adhesin (PIA) than the parent strain. In conclusion, interrupting a hemin biosynthetic gene in S. epidermidis resulted in an SCV phenotype. Markedly larger cell clusters and the ability of the hemB mutant to form a biofilm are related to the augmented expression of PIA.     

Subcellular localization, oligomerization, and ATP-binding of Caenorhabditis elegans CED-4.

Caspase family cell death proteases are activated during apoptosis through the oligomerization of caspase-binding "adapter" proteins. In the nematode Caenorhabditis elegans one adapter protein, CED-4, exists. Here we report an analysis of CED-4 protein expressed in insect Sf9 cells by infection with recombinant baculovirus. During expression, CED-4 assumed a perinuclear spherical or reticular localization where it was partly resistant to extraction with nonionic detergents. Both purified FLAG-CED-4 and GST-FLAG-CED-4 proteins were present in solution as large complexes. FLAG-CED-4 complexes were estimated by gel filtration to have a molecular weight of approximately 500 kDa to >1.2 MDa, while GST-FLAG-CED-4 complexes appeared somewhat smaller. Unlike its mammalian homologue Apaf-1, CED-4 exhibited a marked preference for ATP over dATP in filter binding studies and in competition experiments. ATP hydrolysis was required neither for complex stability nor for binding of CED-3. These features are likely to be relevant for CED-4's function as a caspase adapter.     

Tafelfonds

Ohne Zusammenfassung     

Die Identifizierung vonTephea Delile und andere die Oliniaceae betreffende Feststellungen

Ohne Zusammenfassung     

Keimung verschieden alter Konidien von Aspergillus niger und Wachstum aus ihnen gezogener Mycelien.

Zusammenfassung 12–13 Jahre alte Konidien von 5 Aspergillus niger-Rassen keimten später als 12 Monate alte und junge, etwa 4 Tage alte, wobei die Versuchstemperatur grundsätzlich ohne Bedeutung war, falls sie Keimung gestattete.Verzögert war nach mikroskopischen Beobachtungen sowohl die der eigentlichen Keimung vorausgehende Quellung der Sporen, als auch die Keimung selbst.Die spätere Keimung der älteren Konidien beruhte zu einem geringen Teil auf stärkerer Austrocknung, die eine mechanische Wasseraufnahme erschwerte, in der Hauptsache jedoch war sie eine Folge des Alters, eine Alterserscheinung.Hatte Keimung stattgefundeu, so war kein Unterschied festzustellen in der Waschstumsstärke und der Konidienfruktifikation zwischen den Mycelien, die auf ungleichalterige Konidien zurückgingen; sie breiteten sich auf Nähragarplatten gleich schnell aus, bildeten auf Nährlösungen Decken von gleichem Gewicht und entwickelten Konidien von nor maler Form und Farbe.Die Untersuchungen wurden 1943/44 in der pharmakognostischen Abteilung der Botanischen Anstalten Breslau durchgeführt.