Anaerobic degradation of papermill sludge in a two-phase digester containing rumen microorganisms and colonized polyurethane foam

Summary The use of reticulated polyurethane foam as a support material for the immobilization of methanogenic associations and its application to the anaerobic treatment of fine particulate solid wastes was investigated. The colonization of polyurethane support particles in a continuous upflow reactor fed on a mixture of acetate, propionate and butyrate, was both rapid and dense. The combination of rumen microorganisms and colonized support particles in a two-phase digester resulted in an efficient anaerobic decomposition of papermill sludge.     

Diadenosine tetraphosphate (Ap4A) is compartmentalized in nuclei of mammalian cells

The intracellular compartmentation of Ap4A in various growth and cell-cycle stages in mammalian cells was studied by applying a non-aqueous extraction procedure for cell nuclei. In both slowly and in exponentially growing Ehrlich ascites tumour cells from random cultures, more than 75% of the whole cellular Ap4A content is localized in the nuclei. In G1 and early S-phase cells of synchronized baby hamster kidney (BHK) fibroblast cultures, approx. 90% of the intracellular Ap4A pool is confined to the nuclear compartment. In contrast, Ap4A is distributed to nearly equal amounts between cytoplasm and nuclei during mid-S phase. After transition through the S-phase, increasing proportions of Ap4A (78% 18 h and 96% 22 h after serum replenishing, respectively) are again localized in the nuclear compartment.     

Distinct mouse DNA sequences enable establishment and persistence of plasmid DNA polymers in mouse cells.

Distinct elements isolated from mouse genomic DNA confer on plasmid DNA the ability to persist at high copy numbers in mouse L fibroblasts (1). Field inversion gel electrophoresis demonstrated that - in contrast to our previous assumption - the persisting plasmid DNA does not exist extrachromosomally but as clusters of tandem repeats integrated into genomic DNA. Digestion with restriction endonucleases that do not cut within the plasmid DNA results in fragments of 50-300 kb in length indicating reiteration of 10-50 plasmid DNA molecules. Restriction with several enzymes that cut once or twice within the plasmid sequences lead to fragment(s) indicative for head-to-tail tandem repeats. In situ hybridization revealed signals for a long homogeneously staining region (HSR) in one or two chromosomes per cell nucleus. Possibilities how these elements could act in the establishment and/or maintenance of the head-to-tail polymers of plasmid DNA in mouse cells are discussed.