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MONOPHYLETIC ORIGINS. "At one time or another, all of these traits have been implicated as bilaterian synapomorphies, though arguments have also been made for multiple independent origins of mesoderm, coeloms, and through-guts within Bilateria. Comparative molecular developmental data have provided support for the monophyletic origin of these traits." https://lnkd.in/dph5vzr View in LinkedIn

PATTERNED GENE EXPRESSION. "The anterior-posterior axis of bilaterians is known to be patterned by staggered Hox expression domains. In cnidarians, Hox expression domains are similarly staggered along the oral-aboral axis. The dorsal-ventral axis of bilaterians is patterned partially by the asymmetrical expression of dpp/BMP4. Likewise, dpp is expressed asymmetrically relative to directive axis of sea anemones." https://lnkd.in/dph5vzr View in LinkedIn

CONSISTENCY IN DIVERSITY. "Despite their morphological diversity, most bilaterians are united by a handful of fundamental body plan features including bilateral symmetry, triploblasty, a coelom, a through-gut, and a central nervous system." https://lnkd.in/dph5vzr View in LinkedIn

STAGGERED GENE DOMAINS. "Typically, each individual Hox gene is expressed in a band of cells representing a subset of the animal’s anterior-posterior axis. Different Hox genes have distinct domains of spatial expression along the primary body axis. Collectively, the staggered Hox expression domains specify regional identity over the majority of the body axis, as each region of the body comes to express a different Hox gene or combination of Hox genes. The “Hox code” effectively subdivides the bilaterian body plan into distinct regions." https://lnkd.in/dph5vzr View in LinkedIn

VAST FOOTPRINT. "The ancestral bilaterian left quite a legacy. Modern-day bilaterians number some 32 phyla encompassing well over a million described species. Bilaterians are far more abundant, far more diverse morphologically, and far more diverse ecologically than non-bilaterian metazoans (Porifera, Ctenophora, Cnidaria, and Placozoa). In addition, much greater morphological complexity is achieved within the Bilateria than within the non-bilaterian phyla." https://lnkd.in/dph5vzr View in LinkedIn

HOMEOBOX TOOLKIT. "In all bilaterians that have been examined, the Hox genes play a conserved role in patterning the anterior-posterior axis. Hox genes represent a subset of the larger family of homeobox containing transcription factors. A cluster of seven or eight Hox genes was present in the bilaterian ancestor." https://lnkd.in/dph5vzr View in LinkedIn

MOST ANIMALS ARE BILATERIANS. "Over 99% of modern animals are members of the evolutionary lineage Bilateria. The evolutionary success of Bilateria is credited partly to the origin of bilateral symmetry." https://lnkd.in/dqjRU3K View in LinkedIn

AXIS HOMOLOGS. "Different gene networks are responsible for patterning each axis. For example, Hox genes play an evolutionary conserved role in pattering the A-P axis of all bilaterians studied to date. Patterning of the D-V axis in both vertebrates and insects depends on the activities of decapentaplegic (dpp) and short gastrulation (sog) homologs." https://lnkd.in/dph5vzr View in LinkedIn

BILATERAL SYMMETRY. "It is achieved by the intersection of two orthogonal axes of polarity: the anterior-posterior (A-P) axis and the dorsal-ventral (D-V) axis." https://lnkd.in/dph5vzr View in LinkedIn

AXIS GENES. "Hox genes play a conserved role in patterning the A-P axis of bilaterians. Hox genes are expressed in staggered axial domains along the oral-aboral axis of cnidarians, suggesting that Hox patterning of the primary body axis was already present in the cnidarian-bilaterian ancestor. Dpp plays a conserved role patterning the D-V axis of bilaterians." https://lnkd.in/dph5vzr View in LinkedIn