@article {5954, title = {The phylogenetic origin and evolution of acellular bone in teleost fishes: insights into osteocyte function in bone metabolism}, journal = {Biological Reviews}, year = {2019}, abstract = {

ABSTRACT Vertebrate bone is composed of three main cell types: osteoblasts, osteoclasts and osteocytes, the latter being by far the most numerous. Osteocytes are thought to play a fundamental role in bone physiology and homeostasis, however they are entirely absent in most extant species of teleosts, a group that comprises the vast majority of bony {\textquoteleft}fishes{\textquoteright}, and approximately half of vertebrates. Understanding how this acellular (anosteocytic) bone appeared and was maintained in such an important vertebrate group has important implications for our understanding of the function and evolution of osteocytes. Nevertheless, although it is clear that cellular bone is ancestral for teleosts, it has not been clear in which specific subgroup the osteocytes were lost. This review aims to clarify the phylogenetic distribution of cellular and acellular bone in teleosts, to identify its precise origin, reversals to cellularity, and their implications. We surveyed the bone type for more than 600 fossil and extant ray-finned fish species and optimised the results on recent large-scale molecular phylogenetic trees, estimating ancestral states. We find that acellular bone is a probable synapomorphy of Euteleostei, a group uniting approximately two-thirds of teleost species. We also confirm homoplasy in these traits: acellular bone occurs in some non-euteleosts (although rarely), and cellular bone was reacquired several times independently within euteleosts, in salmons and relatives, tunas and the opah (Lampris sp.). The occurrence of peculiar ecological (e.g. anadromous migration) and physiological (e.g. red-muscle endothermy) strategies in these lineages might explain the reacquisition of osteocytes. Our review supports that the main contribution of osteocytes in teleost bone is to mineral homeostasis (via osteocytic osteolysis) and not to strain detection or bone remodelling, helping to clarify their role in bone physiology.

}, keywords = {acellular bone, Actinopterygii, ancestral state reconstruction, anosteocytic bone, bone remodelling, endothermy, osteocyte, Salmoniformes, Scombridae, teleostei}, doi = {10.1111/brv.12505}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12505}, author = {Davesne, Donald and Fran{\c c}ois J Meunier and Schmitt, Armin D. and Friedman, Matt and Otero, Olga and Benson, Roger B. J.} } @article {5959, title = {Histology of the endothermic opah (Lampris sp.) suggests a new structure function relationship in teleost fish bone}, journal = {Biology Letters}, volume = {14}, year = {2018}, pages = {20180270}, abstract = {

Endothermy, production and retention of heat by the body, appeared convergently in mammals, birds and four spiny-rayed teleost fish lineages. Of these, red-muscle endothermy over most or all of the body has only appeared in two groups: tunas and the opah (Lampris). Hitherto, tunas have been the only spiny-rayed fishes known to have bones containing embedded osteocyte cells; others have acellular bone. We examined bone histology in Lampris for the first time, demonstrating the presence of cellular bone very similar to that of tunas. This contrasts with the acellular condition of its ectothermic close relatives. The distribution of this character suggests that it co-evolved with red-muscle endothermy, hinting at a common physiological mechanism that would link bone histology to endothermy in these distantly related teleost lineages.

}, doi = {10.1098/rsbl.2018.0270} URL = {https://royalsocietypublishing.org/doi/abs/10.1098/rsbl.2018.0270}, author = {Davesne, Donald and Meunier, Francois J. and Friedman, Matt and Benson, Roger B. J. and Otero, Olga} }