RT Journal Article
SR Electronic
T1 Stem cells in a colonial animal with localized growth zones
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 001685
DO 10.1101/001685
A1 Stefan Siebert
A1 Freya E. Goetz
A1 Samuel H. Church
A1 Pathikrit Bhattacharyya
A1 Felipe Zapata
A1 Steven H.D. Haddock
A1 Casey W. Dunn
YR 2014
UL http://biorxiv.org/content/early/2014/01/06/001685.abstract
AB Summary Siphonophores (Hydrozoa) have unparalleled colony-level complexity, precision of organization, and functional specialization between zooids (i.e., the units that make up colonies). Previous work has shown that, unlike other colonial animals, most growth in siphonophores is restricted to one or two well-defined growth zones that are the sites of both elongation and zooid budding. To understand this unique growth at the cellular level, we characterize the distribution of interstitial stem cells (i-cells) in the siphonophore Nanomia bijuga. Within the colony we find that i-cells are present at the tips of the growth zones, at well-defined sites where new zooid buds will arise, and in the youngest zooid buds. As each zooid matures, i-cells become progressively restricted to specific regions until they are mostly absent from the oldest zooids. We find no evidence of the migratory i-cells that have been observed in colonial cnidarian relatives. The restriction of i-cells to particular developing structures and sites of growth suggest a plant-like model of growth for siphonophores, where the growth zones function much like meristems. This spatial restriction of stem cells could also explain the precision of colony-level organization in siphonophores as a consequence of restricted growth potential.