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Calcification Processes

Calcification Processes. In vivo light-microscopic documentation for primary calcification processes in the hermatypic coral Stylophora pistillata 2006 M. Raz-Bahat, J. Erez, B. Rinkevich. Biomineralization Brown Bag February 28, 2007 Remy Okazaki. Paper Goals.

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Calcification Processes

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  1. Calcification Processes In vivo light-microscopic documentation for primary calcification processes in the hermatypic coral Stylophora pistillata2006M. Raz-Bahat, J. Erez, B. Rinkevich Biomineralization Brown Bag February 28, 2007 Remy Okazaki

  2. Paper Goals • Describe calcification processes • Examine diurnal calcification Findings • 4 Stage Process • No diurnal pattern

  3. Growth: taller then fatter CC • Centers of calcification = nucleation sites • Crystals bundled in packets • Accreted at night • Fasciculi = bundles of fibers • Note: morphology differs among taxa fibers Cohen and McConnaughey 2003

  4. Day vs Night • Night: faster extension • Day: higher calcification • Photosynthesis-enhanced • Note: results for Acropora cervicornis, not all species have diurnal cycle Cohen and McConnaughey 2003

  5. How they did it Stylophora pistillata = fast-growing & branching • Nubbin + glue + slide • Tissue growth on slide • Tetracycline bath • Binds CaCO3 and fluoresces • Inverted microscope • Limitation: tissue extension, not branch tips Raz-Bahat et al. 2006

  6. 4 Stage Process Stage 1: Tissue expansion - No CaCO3 or zooxanthellae tt = tissue expansion Stage 2: Fusiform crystals - Discontinuous skeletal front New primary crystals Modified from Raz-Bahat et al. 2006

  7. Solidifying the skeleton Stage 3: Needle-like crystals Black = needlelike crystals Red = primary crystals Stage 4: Gap-filling Red = Stage 4 White = Stages 1-3 progression Raz-Bahat et al. 2006

  8. The stages continue on different timeframes: Stage 1 0 hr Stage 2 1 hr Stage 1 & 2 2 hr Days - weeks Few hours Raz-Bahat et al. 2006

  9. New observation: terraces • Stage 2: fusiform crystals randomly deposited (arrows) • Stages 4: needles form a terrace (t) parallel to former skeleton (fs) • Terraces have not been documented up to now Raz-Bahat et al. 2006

  10. Primary seed is a single crystal • Not a bundle as previously believed • Polarized light • Single crystal: Uniformly transmits light • Multiple crystals: Dark with glowing areas Raz-Bahat et al. 2006

  11. Stage 4: Skeletal morphology was different and random • Laminar • Needles radiate in same direction • Scattered • Shorter needles randomly radiate l = laminar, s = scattered Raz-Bahat et al. 2006

  12. Distal tissue lacks zooxanthellae • No zooxanthellae • No skeletal elements • No organic matter • No contribution to primary calcification? • Translocation of ATP? • Role of organic matrix? Dotted line = proximal edge of expanding tissue tt = leading tissue v = vacuole n = nematocyst c = cytoplasmic projections g = glass Modified from Raz-Bahat et al. 2006

  13. Distal tissue only has 2 layers • Epidermis & Calicoblastic epithelium (outside layers) • Missing coelenteron and gastrodermis oral epidermis coelenteron gastrodermis mesoglea Epithelial junction calicoblastic cells Raz-Bahat et al. 2006

  14. No diurnal phases Calcification: Stages 1 & 2 = Primary; Stages 3 & 4 = Secondary  Both stages occur during day and night Raz-Bahat et al. 2006

  15. Implications • No closed space or extracellular pocket • Ca2+ and CO32- exchange • All stages at all times of the day  No diurnal changes in calcification • Stages of calcification • “Intrinsic fundamental process controls skeletogenesis” - “insufficient to contradict… light-enhanced calcification”

  16. Questions • Vacuoles in expanding tissue? • Laminar vs scattered crystals? • Formation of primary crystals? • Organic matrix? Forms precursors?

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