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Transient changes in intracellular calcium ([Ca2+]i) have been shown to punctuate the cell cycle in various types of cells in culture and in early embryos. The [Ca2+]i transients are correlated with cell-cycle events: pronuclear migration, nuclear envelope breakdown, the metaphase-anaphase transition of mitosis, and cytokinesis. Mitotic events can be(More)
Using calcium-sensitive dyes together with their dextran conjugates and confocal microscopy, we have looked for evidence of localized calcium signaling in the region of the nucleus before entry into mitosis, using the sea urchin egg first mitotic cell cycle as a model. Global calcium transients that appear to originate from the nuclear area are often(More)
We report an ion channel in the plasma membrane of unfertilized oocytes of the ascidian Ciona intestinalis that is directly gated by the second messenger ADP-ribose. The ion channel is permeable to Ca2+ and Na+ and is characterized by a reversal potential between 0 and +20 mV and a unitary conductance of 140 pS. Preinjection of the Ca2+ chelator(More)
There are two current hypotheses as to how the spermatozoon triggers the oocyte into activity; a transmembrane receptor mechanism involving G-proteins and a soluble sperm-factor mechanism. In this short review we show that the present data favours the idea of a soluble factor diffusing from the spermatozoon into the oocyte following plasma membrane fusion(More)
BACKGROUND Calcium is an important and ubiquitous signalling ion. In most cell types, changes in intracellular calcium concentrations are sensed by calmodulin, a signal transduction protein that regulates cell function through its interactions with kinases and phosphatases. Calcium signals show complex spatiotemporal patterning, but little, if anything, is(More)
We combine small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) with aerodynamic levitation techniques to study in situ phase transitions in the liquid state under contactless conditions. At very high temperatures, yttria-alumina melts show a first-order transition, previously inferred from phase separation in quenched glasses. We show(More)
We have used confocal microscopy and a fluorescent calmodulin probe to examine the mechanism of localisation of calmodulin during the first cell cycle of the sea urchin zygote. Using fluorescein-calmodulin, calmodulin can be observed within the nucleus and interphase astral microtubule arrays as cells approach mitosis. During mitosis, calmodulin(More)
Crystalline and amorphous forms of silicon are the principal materials used for solid-state electronics and photovoltaics technologies. Silicon is therefore a well-studied material, although new structures and properties are still being discovered. Compression of bulk silicon, which is tetrahedrally coordinated at atmospheric pressure, results in a(More)
We have used ratiometric confocal microscopy and three fluorescence techniques to study the distribution and activity of mitochondria in frog oocytes during the early stages of oogenesis. Mitochondria in frog oocytes during oogenesis were characterised by a high ratio in the 'mitochondrial cloud' and perinuclear region and a low ratio in mitochondria freely(More)
  • M Grande, B J Maddison, C J Howe, B J Kellett, P Sreekumar, J Huovelin +24 others
  • 2009
The Chandrayaan-1 X-ray Spectrometer (C1XS) is a compact X-ray spectrometer for the Indian Space Research Organisation (ISRO) Chandrayaan-1 lunar mission. It exploits heritage from the D-CIXS instrument on ESA's SMART-1 mission. As a result of detailed developments to all aspects of the design, its performance as measured in the laboratory greatly surpasses(More)