Skeletal morphogenesis and growth mode of modern and fossil deep-water isidid gorgonians (Octocorallia) in the West Pacific (New Zealand and Sea of Okhotsk)

Fabric and growth mode of deep-water isidid gorgonian skeletons showing bright Mg-calcitic internodes and dark proteinageous nodes were investigated on modern, subrecent and fossil skeletons. The internodial microstructure is characterised by three-dimensionally interfingering calcitic fascicles accreting around a central axis. Macroscopic colour banding results from varying orientations of organic-rich fascicle bundles and intercalated bands of organic-poor granular crystals. This skeletal structure of isidid gorgonians strikingly differs from the density banding of scleractinians. Radiocarbon dating of a fossil skeleton gave an age of 3,985±35 to 3,680±35 years before present (BP) with a record of 305±35 years (±range). Linear extension rates of 0.4 mm year−1 average allow for an annual to sub-annual resolution on micrometer scale of colour bands or fascicles, respectively. The growth mode of branched skeletons is characterised by simultaneous secretion of vertically alternating nodes/internodes and lateral accretion of concentric increments enveloping the entire skeleton. Bifurcations at various growth stages imply that adjacent branches have different ages and show varying numbers of growth bands at any skeletal cross section. The scleroprotein gorgonin plays a crucial role in the formation of organic nodes and the secretion of calcitic internodes by providing a structural framework in the biomineralisation process

The redox state of cytochrome C modulates resistance to methotrexate in human MCF7 breast cancer cells

Background: Methotrexate is a chemotherapeutic agent used to treat a variety of cancers. However, the occurrence of resistance limits its effectiveness. Cytochrome c in its reduced state is less capable of triggering the apoptotic cascade. Thus, we set up to study the relationship among redox state of cytochrome c, apoptosis and the development of resistance to methotrexate in MCF7 human breast cancer cells. Results: Cell incubation with cytochrome c-reducing agents, such as tetramethylphenylenediamine, ascorbate or reduced glutathione, decreased the mortality and apoptosis triggered by methotrexate. Conversely, depletion of glutathione increased the apoptotic action of methotrexate, showing an involvement of cytochrome c redox state in methotrexateinduced apoptosis. Methotrexate-resistant MCF7 cells showed increased levels of endogenous reduced glutathione and a higher capability to reduce exogenous cytochrome c. Using functional genomics we detected the overexpression of GSTM1 and GSTM4 in methotrexate-resistant MCF7 breast cancer cells, and determined that methotrexate was susceptible of glutathionylation by GSTs. The inhibition of these GSTM isoforms caused an increase in methotrexate cytotoxicity in sensitive and resistant cells. Conclusions: We conclude that overexpression of specific GSTMs, GSTM1 and GSTM4, together with increased endogenous reduced glutathione levels help to maintain a more reduced state of cytochrome c which, in turn, would decrease apoptosis, thus contributing to methotrexate resistance in human MCF7 breast cancer cells