Development and senescence of Grevillea 'Sylvia' inflorescences, flowers and flower parts

To characterise the physiology of development and senescence for Grevillea 'Sylvia'. oral organs, respiration, ethylene production and ACC concentrations in harvested flowers and flower parts were measured. The respiration rate of harvested inflorescences decreased over time during senescence. In contrast, both ethylene production and ACC concentration increased. Individual flowers, either detached from cut inflorescences held in vases at 20degreesC or detached from in planta inflorescences at various stages of development, had similar patterns of change in ACC concentration and rates of respiration and ethylene production as whole inflorescences. The correlation between ACC concentration and ethylene production by individual flowers detached from cut inflorescences held in vases was poor (r(2)=0.03). The isolated complete gynoecium (inclusive of the pedicel) produced increasing amounts of ethylene during development. Further sub-division of flower parts and measurement of their ethylene production at various stages of development revealed that the distal part of the gynoecium (inclusive of the stigma) had the highest rate of ethylene production. In turn, anthers had higher rates of ethylene production and also higher ACC concentrations than the proximal part of the gynoecium (inclusive of the ovary). Rates of ethylene production and ACC concentrations for tepal abscission zone tissue and adjacent central tepal zone tissue were similar. ACC concentration in pollen was similar to that in senescing perianth tissue. Overall, respiration, ethylene and ACC content measurements suggest that senescence of G. 'Sylvia' is non-climacteric in character. Nonetheless, the phytohormone ethylene is produced and evidently mediates normal flower development and non-climacteric senescence processes.

Upper Devonian biostratigraphy of the Iberian Pyrite Belt, southwest Spain Part One: Miospores

The Iberian Pyrite Belt (IPB), which forms part of the Variscan orogenic massif, is renowned for the magnitude and extent of its massive sulfide mineralization. The stratigraphic record of the IPB consists of Upper Palaeozoic sedimentary and igneous rocks. In ascending order, these comprise the thick Phyllite-Quartzite Group attributed to the Middle and Upper Devonian and characterized by shales and quartzites with conglomeratic and carbonate intercalations towards the top; the appreciably thinner Volcano-Sedimentary Complex, a heterogeneous uppermost Devonian-Mississippian unit embodying diverse volcanic, subvolcanic, and sedimentary rocks that host the massive sulfide deposits; and the shaly and sandy, turbiditic Culm Group (Carboniferous). This entire succession was folded and faulted during the Asturian phase of the Variscan Orogeny that gave rise to a thin-skinned type structure. The present study constitutes a detailed blostratigraphic investigation of palynologically productive samples representative of the Phyllite-Quartzite Group and the basal (anoxic) portion of the Volcano-Sedimentary Complex. These were collected from surface and mine exposures variously located in the Spanish part of the IPB; out of 282 samples processed, 117 proved to be productive palynologically. The aim of this project is to provide comprehensive palynostratigraphic data applicable to precise dating and correlation of the IPB's stratigraphic succession (i.e., of the two sampled lithostratigraphic units), which has hitherto been investigated biostratigraphically on a relatively localized basis. The results are incorporated in two successive parts. The first of these, i. e., the present paper, focuses on the systematic analysis of the terrestrial (miospore) component of the palynological assemblages. The second part, devoted to the marine, organic-walled microphytoplankton (acritarchs and prasinophytes), will evaluate the stratigraphic significance of the IPB palynofloras and their application to elucidating the geological history of the region. In the systematic-descriptive section, which occupies the bulk of this paper, 55 species of trilete miospores are described and are allocated among 34 genera, two of which (Cristicavatispora and Epigruspora) are newly instituted herein. The majority of the species are either positively identifiable or closely affiliable with previously named species. The nine newly established species are as follows: Camptozonotriletes confertus, Indotriradites diversispinosus, Cristicavatispora dispersa (type species), Epigruspora regularis (type species), Ancyrospora? implicata, Endosporites tuberosus, Rugospora explicata, Spelaeotriletes plicatus, and Teichertospora iberica.

Suppressor of cytokine signaling 3 limits protection of leukemia inhibitory factor receptor signaling against central demyelination

Enhancement of oligodendrocyte survival through activation of leukemia inhibitory factor receptor (LIFR) signaling is a candidate therapeutic strategy for demyelinating disease. However, in other cell types, LIFR signaling is under tight negative regulation by the intracellular protein suppressor of cytokine signaling 3 (SOCS3). We, therefore, postulated that deletion of the SOCS3 gene in oligodendrocytes would promote the beneficial effects of LIFR signaling in limiting demyelination. By studying wild-type and LIF-knockout mice, we established that SOCS3 expression by oligodendrocytes was induced by the demyelinative insult, that this induction depended on LIF, and that enclogenously produced LIF was likely to be a key determinant of the CNS response to oligodendrocyte loss. Compared with wild-type controls, oligo-dendrocyte-specific SOCS3 conditional-knockout mice displayed enhanced c-fos activation and exogenous LIF-induced phosphorylation of signal transducer and activator of transcription 3. Moreover, these SOCS3-deficient mice were protected against cupri-zone-induced oligodendrocyte loss relative to wild-type animals. These results indicate that modulation of SOCS3 expression could facilitate the endogenous response to CNS injury.