Skeletal Ultrastructures in some Cerioporine Cyclostome Bryozoans

Abstract The ultrastructure of the calcareous skeleton is described in nine species of Recent cyclostome bryozoans belonging to the suborder Cerioporina. Two species of Heteropora have interior zooecial walls comprising a granular precursory layer followed by a thick layer of transverse fibres and a subordinate foliated fabric with, in mature proximal walls, a semi-nacreous layer. The remaining seven species have interior walls with no transverse fibres and instead predominantly comprise a distally-imbricated, regularly foliated fabric overlying a granular precursory layer. Older, proximal surfaces often have abundant screw dislocations, but true semi-nacre is absent. Basal walls comprise an outer finely granular precursory fabric and planar spherulitic layer, succeeded by the same ultrastructural succession seen in the interior zooecial walls of the respective groups. Exterior walled diaphragms, peristomes and gonozooids similarly comprise an external fabric of planar spherulitic calcite, lined internally by the predominant fabric seen in the interior walls. Ultrastructurally, therefore, cerioporines may be split into two groups with different fabric suites, the first resembling cinctiporids and many tubuliporines in having interior walls with fabrics of transverse fibres, foliated crystallites and semi-nacre; and the second resembling the rectangulates Lichenopora and Disporella in having interior walls comprising only the foliated fabric. These findings support the close phylogenetic relationship between cerioporines and other cyclostomes but suggest that the cerioporines may constitute either a diphyletic or a paraphyletic group.     

Genbank accession #: AF139098

Plant Molecular Biology -     

Simultaneous quantification of emtricitabine and tenofovir nucleotides in peripheral blood mononuclear cells using weak anion-exchange liquid chromatography coupled with tandem mass spectrometry

Emtricitabine (FTC) and tenofovir (TFV) are widely used antiviral agents that require intracellular phosphorylation to become active. This article describes the development and validation of an assay for the simultaneous quantification of FTC mono-, di- and triphosphate (FTC-MP, -DP and -TP), TFV and TFV mono- and diphosphate (TFV-MP and -DP) in peripheral blood mononuclear cells. Reference compounds and internal standards were obtained by thermal degradation of FTC-TP, TFV-DP, stable isotope-labeled TFV-DP and stable isotope-labeled cytosine triphosphate. Cells were lysed in methanol:water (70:30, v/v) and the extracted nucleotides were analyzed using weak anion-exchange chromatography coupled with tandem mass spectrometry. Calibration ranges in PBMC lysate from 0.727 to 36.4, 1.33 to 66.4 and 1.29 to 64.6 nM for FTC-MP, FTC-DP and FTC-TP and from 1.51 to 75.6, 1.54 to 77.2 and 2.54 to 127 nM for TFV, TFV-MP and TFV-DP, respectively, were validated. Accuracies were within ?10.3 and 16.7% deviation at the lower limit of quantification at which the coefficients of variation were less than 18.2%. At the other tested levels accuracies were within ?14.3 and 9.81% deviation and the coefficients of variation lower than 14.7%. The stability of the compounds was assessed under various analytically relevant conditions. The method was successfully applied to clinical samples.