My overall comment:
08-04-16
I've completed the first review of the references in
Sea Urchin
. They are heavily biased toward thyroid hormones. I don't know if
this reflects an early evolution of thyroid hormones or just an early
interest in them.
Searching Google for "sea urchin" discovered 3,860,000 references:
https://www.google.com/search?q=sea+urchin&ie=utf-8&oe=utf-8
Sea urchin - Wikipedia
https://en.wikipedia.org/wiki/Sea_urchin
"Sea urchins or urchins (/ˈɜːrtʃɪnz/), archaically called sea hedgehogs,[1][2] are small, spiny, globular animals that, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. About 950 species of echinoids inhabit all oceans from the intertidal to 5,000 metres (16,000 ft; 2,700 fathoms) deep.[3]
The shell, or "test", of sea urchins is round and spiny, typically from
3 to 10 cm (1.2 to 3.9 in) across. Common colors include black and dull
shades of green, olive, brown, purple, blue, and red. Sea urchins move
slowly, feeding primarily on algae. Sea otters, starfish, wolf eels, triggerfish, and other predators hunt and feed on sea urchins. Their roe is a delicacy in many cuisines. The name "urchin" is an old word for hedgehog, which sea urchins resemble."
Tripneustes ventricosus and Echinometra viridis,
two species of tropical sea urchins.
Contents
Abstract:
http://www.ncbi.nlm.nih.gov/pubmed/16965768
"The neurobiology of sea urchins is of particular
interest because they have a close phylogenetic relationship with
chordates, yet a distinctive pentaradiate body plan and unusual neural
organization."
" A family of genes encoding voltage-gated ion channels is present but,
surprisingly, genes encoding gap junction proteins (connexins and
pannexins) appear to be absent.
Genes required for synapse formation and
function have been identified and genes for synthesis and transport of
neurotransmitters are present.
There is a large family of
G-protein-coupled receptors, including 874 rhodopsin-type receptors, 28
metabotropic glutamate-like receptors and a remarkably expanded group of
161 secretin receptor-like proteins."
"There are at least 37 putative
G-protein-coupled peptide receptors and precursors for several
neuropeptides and peptide hormones have been identified,
including ... a vasotocin-like peptide,
glycoprotein hormones, and insulin/insulin-like growth factors.
Identification of a neurotrophin-like gene and Trk receptor in sea
urchin indicates that this neural signaling system is not unique to
chordates.
Several hundred chemoreceptor genes have been predicted
using several approaches, a number similar to that for other animals." Full length article:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1950334/?tool=pubmed
My comment:
There's quite a lot here about hormones as well as neurotransmitters, but no mention of steroids.
2007 36<198
Gametogenesis correlated with steroid levels during the gonadal cycle of the sea urchin Paracentrotus lividus (Echinodermata: Echinoidea).
2008 30<198
The amphioxus genome enlightens the evolution of the thyroid hormone signaling pathway.
2009 27<198
Effects of 17beta-estradiol, and its metabolite, 4-hydroxyestradiol on fertilization, embryo development and oxidative DNA damage in sand dollar (Dendraster excentricus) sperm.
2009 20<198
Endocrine interactions between plants and animals: Implications of exogenous hormone sources for the evolution of hormone signaling.
2010 19<198 Free Article
Evolution of 11beta-hydroxysteroid dehydrogenase-type 1 and 11beta-hydroxysteroid dehydrogenase-type 3.
2014 9<198
Neuropeptides and polypeptide hormones in echinoderms: new insights from analysis of the transcriptome of the sea cucumber Apostichopus japonicus.
2014 6<198
Characterization of insulin-like peptides (ILPs) in the sea urchin Strongylocentrotus purpuratus: insights on the evolution of the insulin family.
2014 4<198
Evolution of gonadotropin-inhibitory hormone receptor and its ligand.
2015 1<198
Unraveling estradiol metabolism and involvement in the reproductive cycle of non-vertebrate animals: The sea urchin model.
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