Weaver James C.

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Weaver
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James C.
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  • Preprint
    Microstructural and biochemical characterization of the nanoporous sucker rings from Dosidicus gigas
    ( 2008-11-24) Miserez, Ali ; Weaver, James C. ; Pedersen, Peter B. ; Schneeberk, Todd ; Hanlon, Roger T. ; Kisailus, David ; Birkedal, Henrik
    Recent interest in the development of environmentally benign routes to the synthesis of novel multifunctional materials has resulted in numerous investigations into structure-function relationships of a wide range of biological systems at the ultrastructural, micromechanical, and biochemical levels. While much of this research has concentrated on mineralized structures such as bone, mollusk shells sponge spicules and echinoderm ossicles, there is an equally broad range of animals whose skeletal structures are devoid of mineral components.One such group, the squids (Mollusca: Cephalopoda: Teuthoidea), are remarkable in several aspects. In addition to having an exceptionally well developed brain, sensory systems and skin (for adaptive coloration), these swift agile predators have eight flexible strong arms, two fast extensible tentacles, and strong malleable suckers, all of which are muscular hydrostats.
  • Preprint
    Changes in reflectin protein phosphorylation are associated with dynamic iridescence in squid
    ( 2009-07-18) Izumi, Michi ; Sweeney, Alison M. ; DeMartini, Daniel ; Weaver, James C. ; Powers, Meghan L. ; Tao, Andrea ; Silvas, Tania V. ; Kramer, Ryan M. ; Crookes-Goodson, Wendy J. ; Mathger, Lydia M. ; Naik, Rajesh R. ; Hanlon, Roger T. ; Morse, Daniel E.
    Many cephalopods exhibit remarkable dermal iridescence, a component of their complex, dynamic camouflage and communication. In the species Euprymna scolopes, the light-organ iridescence is static and is due to reflectin protein-based platelets assembled into lamellar thin-film reflectors called iridosomes, contained within iridescent cells called iridocytes. Squid in the family Loliginidae appear to be unique in that the dermis possesses a dynamic iridescent component, with reflective, colored structures that are assembled and disassembled under the control of the muscarinic cholinergic system and the associated neurotransmitter acetylcholine (Mathger et al. 2004). Here we present the sequences and characterization of three new members of the reflectin family associated with the dynamically changeable iridescence in Loligo and not found in static Euprymna iridophores. In addition, we show that application of genistein, a protein tyrosine kinase inhibitor, suppresses acetylcholine- and calcium-induced iridescence in Loligo. We further demonstrate that two of these novel reflectins are extensively phosphorylated in concert with the activation of iridescence by exogenous acetylcholine. This phosphorylation and the correlated iridescence can be blocked with genistein. Our results suggest that tyrosine phosphorylation of reflectin proteins is involved in the regulation of dynamic iridescence in Loligo.