Verrucomicrobia are candidates for polysaccharide-degrading bacterioplankton in an arctic fjord of Svalbard.

In Arctic marine bacterial communities, members of the phylum Verrucomicrobia are consistently detected, although not typically abundant, in 16S rRNA gene clone libraries and pyrotag surveys of the marine water column and in sediments. In an Arctic fjord (Smeerenburgfjord) of Svalbard, members of the Verrucomicrobia, together with Flavobacteria and smaller proportions of Alpha- and Gammaproteobacteria, constituted the most frequently detected bacterioplankton community members in 16S rRNA gene-based clone library analyses of the water column. Parallel measurements in the water column of the activities of six endo-acting polysaccharide hydrolases showed that chondroitin sulfate, laminarin, and xylan hydrolysis accounted for most of the activity. Several Verrucomicrobia water column phylotypes were affiliated with previously sequenced, glycoside hydrolase-rich genomes of individual Verrucomicrobia cells that bound fluorescently labeled laminarin and xylan and therefore constituted candidates for laminarin and xylan hydrolysis. In sediments, the bacterial community was dominated by different lineages of Verrucomicrobia, Bacteroidetes, and Proteobacteria but also included members of multiple phylum-level lineages not observed in the water column. This community hydrolyzed laminarin, xylan, chondroitin sulfate, and three additional polysaccharide substrates at high rates. Comparisons with data from the same fjord in the previous summer showed that the bacterial community in Smeerenburgfjord changed in composition, most conspicuously in the changing detection frequency of Verrucomicrobia in the water column. Nonetheless, in both years the community hydrolyzed the same polysaccharide substrates.

Microbial community composition and function in permanently cold seawater and sediments from an arctic fjord of svalbard.

Heterotrophic microbial communities in seawater and sediments metabolize much of the organic carbon produced in the ocean. Although carbon cycling and preservation depend critically on the capabilities of these microbial communities, their compositions and capabilities have seldom been examined simultaneously at the same site. To compare the abilities of seawater and sedimentary microbial communities to initiate organic matter degradation, we measured the extracellular enzymatic hydrolysis rates of 10 substrates (polysaccharides and algal extracts) in surface seawater and bottom water as well as in surface and anoxic sediments of an Arctic fjord. Patterns of enzyme activities differed between seawater and sediments, not just quantitatively, in accordance with higher cell numbers in sediments, but also in their more diversified enzyme spectrum. Sedimentary microbial communities hydrolyzed all of the fluorescently labeled polysaccharide and algal extracts, in most cases at higher rates in subsurface than surface sediments. In seawater, in contrast, only 5 of the 7 polysaccharides and 2 of the 3 algal extracts were hydrolyzed, and hydrolysis rates in surface and deepwater were virtually identical. To compare bacterial communities, 16S rRNA gene clone libraries were constructed from the same seawater and sediment samples; they diverged strongly in composition. Thus, the broader enzymatic capabilities of the sedimentary microbial communities may result from the compositional differences between seawater and sedimentary microbial communities, rather than from gene expression differences among compositionally similar communities. The greater number of phylum- and subphylum-level lineages and operational taxonomic units in sediments than in seawater samples may reflect the necessity of a wider range of enzymatic capabilities and strategies to access organic matter that has already been degraded during passage through the water column. When transformations of marine organic matter are considered, differences in community composition and their different abilities to access organic matter should be taken into account.

Diagnostic immunohistochemistry of neuroblastic tumors.

Eighteen commercially available antibodies were applied to formalin-fixed, paraffin-embedded neuroblastomas (NBLs, n = 20), ganglioneuroblastomas (GNBLs, n = 7), and ganglioneuromas (GNs, n = 7) to assess their reliability as markers for neuroendocrine differentiation and degree of tumor cell maturation. Incubations with a monoclonal antibody to neuron-specific enolase resulted in positive reactions in all tumors, with consistently strong staining intensities in moderate and well-differentiated NBLs, GNBLs, and GNs. Antibodies to dopamine beta-hydroxylase and protein gene product (PGP) 9.5 reacted with all tumors except two NBLs. Among the antibodies directed to chromogranins and related proteins, HISL19 was most reliable (33/34) followed by endocrine granule constituent (EGC) (30/34), chromogranin A (LK2H10) (21/34), and chromogranin A + B (CGA + B) (19/34), in proving the existence of endocrine granules in tumor cells and Neurofilament (70 + 200 kD) immunoreactivity was demonstrated in all tumors except two undifferentiated NBLs. S-100 protein-immunoreactive cells were visualized with increasing frequency in highly differentiated GNBLs and GNs, whereas Leu 7 immunoreactivity was restricted to ganglioneuromas. We conclude that antibodies directed to neuron-specific enolase, HISL19, dopamine beta-hydroxylase, neurofilaments, EGC, LK2H10, and leucocyte common antigen represent markers that might be useful in the discrimination of GNBLs from non-neuroendocrine round and small cell tumors in routinely processed tissue. Antibodies to neuron-specific enolase, PGP 9.5, different chromogranins, neurofilaments, vasoactive intestinal peptide (VIP), and S-100 protein may help to determine the grade of tumor cell maturation.

Immunohistochemical markers in (ganglio)neuroblastomas.

17 commercially available antibodies were applied on formalin fixed and paraffin embedded tissues of neuroblastomas (NBLs, n = 20), ganglioneuroblastomas (GNBLs, n = 7) and ganglioneuromas (GNs, n = 7), to assess their reliability as markers for neuroendocrine differentiation and the degree of tumor cell maturation. Our results indicate, that antibodies directed to neuron specific enolase, HISL 19, dopamine beta-hydroxylase, neurofilament, EGC, LK2H10 and leucocyte common antigen may be useful in discrimination of neuroblastomas from non-neuroendocrine round and small cell tumors in routinely processed tissue. Antibodies to neuron specific enolase, EGC, PGP 9.5, VIP, and S 100 protein may contribute to the determination of the maturation grade of (ganglio)neuroblastomas.