Join GitHub today
GitHub is home to over 28 million developers working together to host and review code, manage projects, and build software together.Sign up
Taxon rule for 'urinary bladder' #454
Stemming from a user's request on the GO SourceForge tracker:
The uncertainty comes from these statements:
"homology_notes: In tetrapods, the urinary bladder arises as an outpocketing of the cloaca. (...) The tetrapod urinary bladder appears first among amphibians and is present in Sphenodon, turtles, most lizards, ostriches among birds, and all mammals.[well established][VHOG]"
However, the references that the GO user provided say that ostrich and rhea don't have a proper urinary bladder, but, differently from other birds, they store urine separately in an expansion of the cloaca.
The ultimate question for GO is whether we should restrict the terms 'urinary bladder development' and 'urinary bladder smooth muscle contraction' to never_in_taxon Aves (i.e. both Paleognathae and Neognathae) or just to Neognathae.
GO SF ticket for reference:
For urinary bladder, we report the following assertions:
ISBN:978-0072528305 "Kardong KV, Vertebrates: Comparative Anatomy, Function, Evolution (2006) p.577-78"
In our new process to expand and annotate an homology assertion by linking to a defined taxonomy, we also report this reference (PMID:538956 "Bentley PJ, The vertebrate urinary bladder: osmoregulatory and other uses. Yale J Biol Med (1979)"9
"Urinary bladders appear to have evolved in vertebrates at least twice, which suggests that they are useful. In tetrapods the bladder is an endodermal structure which arises as an outgrowth of the cloaca. In amniotes it gives rise to the embryonic allantoic membrane, part of which may persist as the bladder in the adult. While a bladder does not occur in birds the allantois remains an important organ during its development in the egg. The fish bladder is embryologically quite different to the tetrapod bladder and is mesodermal in origin, arising as an expansion of the mesonephoric ducts. It is thus really an extension of the kidney."
From this assertion we capture the 'urinary bladder' as an organ potentially already present into the ancestor of Tetrapoda (taxon ID 32523) , but also as an organ that potentially evolves into a more specific organ in Amniota (taxon ID 32524).
Current structures in living animals do not necessary have the same shape than the homologous one in their common ancestor. However regarding the definition of GO terms 'urinary bladder development' and 'urinary bladder smooth muscle contraction', I would say that
Hope these comments help.