2014 Bone & Cartilage: from Development to Human Diseases
Suzhou, China, November 3-7, 2014
  
57
THE ZEBRAFISH SCALE: A MODEL FOR STUDYING THE
MOLECULAR REGULATION OF MAMMALIAN BONE/PLASMA
CA2+ EXCHANGE; THE IMMEDIATE BONE WOUNDING
RESPONSE; AND BONE REGENERATION AND REPAIR.
Andrew L Miller¹, Jacky T Hung¹, Alessandro Rubinacci², Joseph G Kunkel³,
Alan M Shipley
4
, Paola D Pajevic
5
, Chevonne H Angus
6
, Sarah E Webb¹ 
1
HKUST, Division of Life Sciences, Hong Kong, China, ²San Raffaele
Hospital, Bone Metabolism Unit, Milan, Italy, ³University of New England,
Marine Science Center, Biddeford, ME,
4
Applicable Electronics, Design and
Manufacture, New Haven, CT,
5
MGH, Endocrine Unit THR 1101, Boston, MA,
6
North Atlantic Fisheries College, Marine Science Centre, Scalloway, United
Kingdom
The elasmoid scales of teleost fish form part of the dermal skeleton and
represent a significant internal reservoir of Ca2+. Our understanding, however,
of their contribution to plasma Ca2+ balance and how Ca2+ deposition and
mobilization are regulated from a molecular perspective in these calcified
structures in vivo, is far from complete. This is especially so when diadromous
fish transition from euhaline to fresh water environments, and vice versa. This
gap in our understanding is partly due to the technical challenges involved in
measuring Ca2+ fluxes around the scales of live fish in real-time, and under
various Ca2+ challenges. From preliminary experiments using scales removed
from zebrafish (Danio rerio), we have begun to develop a combination of
techniques for the removal, live-culturing, mounting then surface scanning of
intact scales, using a non-invasive, scanning ion-selective electrode technique
(SIET), which can resolve Ca2+ flux values in the sub pmol/cm2/sec range, and
with a spatial resolution of ~5µm. Thus, under different extracellular calcemic
environments, Ca2+ fluxes both into and out of scales can be quantified and
correlated to particular anatomical features of individual scales. It has been
recently proposed that fish scales may be used as a new vertebrate model to
study human bone development, disease and regeneration in order to
complement the current (more expensive) mammalian models such as the
mouse. It is becoming clear that fish scales are composed of many of the
essential cell types and structures found in mammalian bone (e.g., osteoclasts,
osteoblasts, matrix proteins, hydroxyapatite crystals, and collagen fibers), and
we will present preliminary data to support the proposal that similar to
mammalian bone, fish scales also act as an alternative Ca2+ store that plays a
key role in the homeostatic regulation of Ca2+ in interstitial fluids and blood.
We are also exploring the involvement of the estrogen, 17ß-estradiol, and
parathyroid hormone in mediating Ca2+ mobilization under different calcemic
conditions. The goal of the study is to extend our limited understanding of the
relationship between Ca2+ stored in the scales of fishes, and that in the internal
blood plasma and external environment, as well as the possible roles of Ca2+
signalling in wound repair and scale/bone regeneration.