Virus-directed formation of electrocatalytically active nanoparticle-based Co3O4 tubes.

Spinel-type Co3O4 finds applications in a wide range of fields, including clean energy conversion, where nanostructured Co3O4 may provide a cost-efficient alternative to platinum- and iridium-based catalysts for electrocatalytic water-splitting. We here describe a novel strategy in which basic cobalt carbonate - a precursor to Co3O4 - is precipitated as sheet-like structures and microspheres covered with fine surface protrusions, via ammonium carbonate decomposition at room temperature. Importantly, these mild reaction conditions enable us to employ bio-inspired templating approaches to further control the mineral structure. Rod-like tobacco mosaic viruses (TMV) were used as biotemplates for mineral deposition, where we profit from the ability of Co(ii) ions to mediate the ordered assembly of the virus nanorods to create complex tubular superstructures of TMV/ basic cobalt carbonate. Calcination of these tubules is then achieved with retention of the gross morphology, and generates a hierarchically-structured solid comprising interconnected Co3O4 nanoparticles. Evaluation of these Co3O4 materials as electrocatalysts for the oxygen evolution reaction (OER) demonstrates that the activity of Co3O4 prepared by calcination of ammonia diffusion-grown precursors in both, the absence or presence of TMV exceeds that of a commercial nanopowder.

Epigenetic regulation of hematopoietic stem cell development.

Hematopoietic stem cells (HSCs) are multipotent self-renewing precursors with the capacity to differentiate into all adult blood cell lineages. HSC development is a highly orchestrated process regulated by multiple transcription factors and signaling pathways. Emerging evidence suggests that epigenetic regulation is an additional essential component of HSC development. Powerful genetic and imaging approaches, combined with conservation of mammalian programs, have made zebrafish a prominent model for the study of HSC production. This chapter summarizes approaches that have been used to identify epigenetic regulators of HSC development in zebrafish and highlights additional strategies that are likely to facilitate progress in this promising field.

An ikaros-containing chromatin-remodeling complex in adult-type erythroid cells.

We have previously described a SWI/SNF-related protein complex (PYR complex) that is restricted to definitive (adult-type) hematopoietic cells and that specifically binds DNA sequences containing long stretches of pyrimidines. Deletion of an intergenic DNA-binding site for this complex from a human beta-globin locus construct results in delayed human gamma- to beta-globin switching in transgenic mice, suggesting that the PYR complex acts to facilitate the switch. We now show that PYR complex DNA-binding activity also copurifies with subunits of a second type of chromatin-remodeling complex, nucleosome-remodeling deacetylase (NuRD), that has been shown to have both nucleosome-remodeling and histone deacetylase activities. Gel supershift assays using antibodies to the ATPase-helicase subunit of the NuRD complex, Mi-2 (CHD4), confirm that Mi-2 is a component of the PYR complex. In addition, we show that the hematopoietic cell-restricted zinc finger protein Ikaros copurifies with PYR complex DNA-binding activity and that antibodies to Ikaros also supershift the complex. We also show that NuRD and SWI/SNF components coimmunopurify with each other as well as with Ikaros. Competition gel shift experiments using partially purified PYR complex and recombinant Ikaros protein indicate that Ikaros functions as a DNA-binding subunit of the PYR complex. Our results suggest that Ikaros targets two types of chromatin-remodeling factors-activators (SWI/SNF) and repressors (NuRD)-in a single complex (PYR complex) to the beta-globin locus in adult erythroid cells. At the time of the switch from fetal to adult globin production, the PYR complex is assembled and may function to repress gamma-globin gene expression and facilitate gamma- to beta-globin switching.

Determination of ochratoxin A in regional samples of cow's milk from Germany.

Samples (121) of cow's milk from a northern region of Germany were analysed for the occurrence of ochratoxin A by means of a sensitive high-performance liquid chromatographic (HPLC) method. The samples were extracted with a mixture of chloroform and methanol at pH < 2. The extracts were cleaned up by solid-phase extraction on silica gel cartridges. The detection limit was 0.01 ng/ml, the quantitation limit was estimated at 0.03 ng/ml. The mean recovery from spiked samples was 84 +/- 7% in the concentration range of 0.03-0.5 ng/ml. An enzyme-linked immunosorbent-assay (ELISA) was shown to be suitable for the confirmation of ochratoxin A levels down to the detection limit of the HPLC method. No ochratoxin A was detected in the samples analysed, either by HPLC or by ELISA.

Effect of ethanol on the induction of lung tumours by ethyl carbamate in mice.

Groups of 25 female NMRI-mice received daily doses of 0, 18, 36, 90, or 180 mg ethyl carbamate/kg body wt either in water or in 20% ethanol by gavage for 8 weeks. Another 8 weeks later, the animals were sacrificed and lung adenomas were counted. Ethyl carbamate was found to increase the number of lung adenomas per mouse dose-dependently in all dose groups. No significant differences, however, were observed between groups receiving ethyl carbamate in water or in 20% ethanol. Thus, ethanol had no effect on ethyl carbamate induced tumourigenesis.