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Topic: Triploblast

Related Topics

Diploblastic

Germ layer

Ectoderm

Mesoderm

Endoderm

Embryogenesis

Gastrovascular

Cambrian Explosion

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Hallucigenia

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Aysheaia

Food chain

Amiskwia

	Triploblasty - Wikipedia, the free encyclopedia
		In higher and intermediate animals (from flat worms to man), all organisms arise from a triploblastic ovum.
		Triploblastic organisms are organisms which evolve from such an ovum.
		Generally speaking, triploblastic organisms belong to the Bilateria subregnum.
	en.wikipedia.org /wiki/Triploblasty (128 words)

	Int. J. Dev. Biol. - Mesodermal anatomies in cnidarian polyps and medusae
		In anthozoan and scyphozoan but not in hydrozoan polyps the presumptive mesodermal elements include amoeboid cells, the mesentery retractor muscles and scleroblasts, all of which are embedded or deeply rooted in the extracellular matrix (mesoglea) and derive from the ectoblastemal cells invading the extracellular matrix from the gastrulation site during or shortly after endoderm formation.
		These data lend further support to the cnidarian mesodermate hypothesis, whereby cnidarians and bilaterians share a common triploblast ancestor, the Urtriploblast, a small, motile, possibly medusa-like organism that did not feature a sessile polyp stage in its life cycle.
		As a consequence the diploblasty of the hydrozoan polyps may represent a derived morphology resulting from heterochronic modulations of the gastrulation process after endoderm formation.
	www.ijdb.ehu.es /web/paper.php?doi=062150ks (240 words)

	Gould article
		An embryo of a triploblast animal in an early stage of cleavage, right, was preserved in late Proterozoic chert from southern China.
		If the Ediacaran animals are all (or mostly) diploblasts, or something even more genealogically divergent from triploblastic animals, then this first fauna does not resolve the problem of the origin of animals (in our conventionally limited sense of modern triploblasts).
		Ediacaran strata also contain trails and feeding traces presumably made by triploblast organisms of modern design (for the flattened and mostly immobile Ediacaran animals could not crawl, burrow, or feed in a manner suggestive of activities now confined to triploblast organisms).
	www.neuroblast.net /PDFs/gouldart.htm (4073 words)

	Platyhelminthes
		Traditionally considered the most primitive of the bilateria (the 'out group' from all the other triploblastic phyla or less related to these other phyla than these other phlya are to one another, or shared the last common ancestor with these phyla longer ago than any common ancestor shared among these other phyla).
		Bottom line: the grouping of triploblastic phyla as acoelomates that gave rise to psuedocoelomates that gave rise to coelomates is rapidly loosing acceptance.
		On the origin of the Bilateria: Significance of ultrastructural research for a new understanding of metazoan phylogeny.
	science.kennesaw.edu /~jdirnber/InvertZoo/LecPlatyhel/Platyhel.html (789 words)

	The Trichoplax PaxB Gene: A Putative Proto-PaxA/B/C Gene Predating the Origin of Nerve and Sensory Cells -- Hadrys et ...
		Note that the inclusion of triploblast sequences results in a loss of bootstrap support.
		Proposed relationships to triploblast Pax258, Pax6, and Pax37 genes are indicated by dotted lines.
		ancestor of cnidarians and triploblasts for sensory organ and
	mbe.oxfordjournals.org /cgi/content/full/22/7/1569 (4181 words)

	Mesozoa
		Few dozen cells forming a two-tissue layer triploblast.
		This would be consistant with considering mesozoans as degenerate turbellarian flatworms
		18S ribosomal DNA most similar to triploblastic metazoans than to protozoans.
	science.kennesaw.edu /~jdirnber/InvertZoo/LecMesozoa/Mesozoa.html (228 words)

	Palaeos Vertebrates: Glossary E-En
		In some types, the cuneiform is found as two or three bones, in which case the more anterior ("dorsal" in dorsal/plantar terminology) is the ectocuneiform, while the more posterior or plantar bones are the mesocuneiform and entocuneiform.
		Ectoderm: One of the three primordial germ layers of all triploblast animals.
		Ectoderm may be the "original" tissue of all animals.
	www.palaeos.com /Vertebrates/Lists/Glossary/GlossaryE.html (1211 words)

	Identification of members of several homeobox genes in a planarian using a ligation-mediated polymerase chain reaction ...
		A phylogenetic tree built with these sequences is consistent with the conservation of a single gene in at least all triploblast animal genomes, although two paralogous genes seem to be present in vertebrates.
		Taken together, these results suggest the possibility that the mesoderm of bilaterally symmetrical animals, either coelomate or acoelomate, may have some common genetic basis in their patterning processes.
		This possibility is of crucial interest for our comprehension of metazoan evolution, as the cellular processes of determination and regionalization of the mesodermal germ layer in triploblasts are very diverse and lead to conflicting evolutionary hypotheses.
	nar.oxfordjournals.org /cgi/content/full/24/8/1547 (4908 words)

	Pharyngula: Jellyfish lack true Hox genes!
		They've identified homeobox-containing genes homologous to those in triploblasts, and are asking if their chromosomal organization is also homologous.
		If it is, that would suggest that the Hox clusters evolved before the cnidarian split, and that their morphological complexity is generated in a way similar to ours.
		If it isn't, that means the Hox clusters evolved after the split in the triploblast lineages, and most interestingly, that the cnidaria are using their Hox-like genes in novel ways to generate their forms.
	scienceblogs.com /pharyngula/2006/05/jellyfish_lack_true_hox_genes.php (1957 words)

	This heirarchical system was initially devised by one Carl Linne (Site not responding. Last check: 2007-11-03)
		These include the cnidarians, the first animals to reveal the continuously repeating rhythmic pulse which scientists believe led to a heartbeat once such organs began to form.
		One subset of Eumetazoa is Bilateria, triploblast animals which at some stage of development are bilaterally-symetrical.
		All bilaterally-symmetrical animals are triploblastic, which means they develop three germ layers; The three germ layers are;
	home.comcast.net /~aronra/Clades.htm (4532 words)

	On embroyos and ancestors: Fossils of tiny embryos 570 million years old may well be the greatest paleontological ... (Site not responding. Last check: 2007-11-03)
		Theories about the affinities of Ediacaran organisms span the full gamut--from viewing them (most conventionally) as simple ancestors for several modern phyla to interpreting them (most radically) as an entirely separate, and ultimately failed, experiment in multicellular animal life.
		Modern animals--except for sponges, corals, and a few other minor groups--are all triploblastic, or composed of three body layers: an ectoderm, forming nervous tissue and other organs; mesoderm, forming reproductive structures and other parts; and endoderm, building the gut and other internal organs.
		Thus, we do have evidence for the existence, and even the activities, of precursors of modern animals before the Cambrian explosion, but no data about their anatomy and appearance--a situation akin to the frustration we might feel if we could hear birdsong but had never seen birds.
	apollonius.addr.com /Bookshop/OnEmbryos.htm (3940 words)

	Special Feature: The Cambrian "explosion": Slow-fuse or megatonnage? -- Conway Morris 97 (9): 4426 -- Proceedings of ...
		The most primitive animals in the fossil record may be represented by the vendobionts (36).
		Metazoans are otherwise divided into various major groupings, of which the most significant depends on the number of germ layers: respectively, two in the diploblasts and three in the triploblasts.
		These Vendian-age assemblages comprise the problematic vendobionts, various coelenterates, and stem-group representatives of the three main groups of triploblast, referred to, respectively, as the ecdysozoans, lophotrochozoans, and deuterostomes.
	www.pnas.org /cgi/content/full/97/9/4426 (3038 words)

	.::Dictionary Entries T::.
		Transpiration: The loss of water vapor from a plant's surface.
		Triploblast: An organism that forms three distinct embryonic tissue layers, namely the mesoderm, the ectoderm, and the endoderm.
		Tuber: In plants, a structure found at the end of a rhizome which becomes swollen, and acts as food storage.
	www.freewebs.com /whatwoulddarwindo/dict_t.html (254 words)

	Interactive Fly, Drosophila
		Phylogenetic analyses indicate that arthropod ftz genes are orthologous to the Lox5 genes of lophotrochozoans (a group that includes molluscs) and, possibly, with the Mab-5 genes of nematodes and Hox6 genes of deuterostomes, and would therefore have been present in the triploblast ancestor (Telford, 2000).
		Identical with Hox3/zen in insects, the loss of AP patterning function might have released the homeodomain from stabilizing selection and led to the rapid sequence divergence seen in the insect ftz genes; indeed in its new role as a pair-rule gene, Drosophila ftz can function even with its homeodomain almost entirely deleted.
		Sequence analyses suggest that ftz orthologs are present in all protostomes and possibly all triploblasts (Telford, 2000).
	www.sdbonline.org /fly/segment/fushitr1.htm (8852 words)

	Pharyngula::Pre-Cambrian coelomate!
		nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure.
		One is the bilateral organization: the mouth is on one end, and the creature definitely has a front and back.
		It's also a triploblast, which means it primitively possesses three body layers, an ectoderm (skin and nervous system) and endoderm (gut), with mesoderm (muscle and connective tissue) sandwiched in between.
	pharyngula.org /index/weblog/comments/pre_cambrian_coelomate (1051 words)

	[No title]
		Briefly describe the life cycle of (and disease caused by, if applicable): Ascaris; Trichinella; filarial worms.
		Which of the organisms in this chapter are: multicellular; diploblasts; triploblasts; pseudocoelomate?
		Chapter 30: The Protostomes For protostomes and deuterostomes, describe: cleavage type; structure associated with blastopore; type of coelom.
	www.midlandstech.edu /science/kelleherk/102/StudyGuides/102SQ3.doc (726 words)

	LED Projects
		This project is funded by a grant from the Marsden Fund.
		Recent phylogenetic studies have split the triploblast metazoans into three large clades, the deuterostomes, the ecdysozoa and the lophotrocozoa.
		One consequence of this phylogenetic reorganisation is that all of the current model genetic organisms fall into either the ecdysozoa or the deuterostomes.
	biochem.otago.ac.nz /deardenlab/web-content/Projects.html (451 words)

	Review Questions - Chapter 8 of Avise 2004 (Site not responding. Last check: 2007-11-03)
		The Cambrian Explosion involves the geologically sudden appearance of nearly every modern phylum of large-bodied "triploblast" (ecto-, meso-, and endoderm) animals with or without skeletons.
		Also label these internal nodes: ME = all metazoans or multicellular animals; BI = bilaterian animals (includes cnidarians!); TR = triploblasts; DE = deuterostomes (also includes us); PR = protostomes; SP = spiralians; EC = ecdysozoans.
		According to Peterson et al., how many triploblastic "worms" "crawled" across the Ediacaran/Cambrian boundary?
	biology.fullerton.edu /courses/biol_402/web/rqs/ch08.htm (926 words)

	Diverse DNA transposons in rotifers of the class Bdelloidea -- Arkhipova and Meselson 102 (33): 11781 -- Proceedings of ...
		a group of basal triploblast animals that appears to have evolved
		triploblast phylum Rotifera, are the taxonomic group for which
		in the poorly explored assemblage of basal triploblasts to which
	www.pnas.org /cgi/content/full/102/33/11781 (4639 words)

	General (via CobWeb/3.1 planetlab2.cs.unc.edu) (Site not responding. Last check: 2007-11-03)
		Other multicellular eukaryotes also have homeobox-like genes, but they do not have the peculiar expression patterns.
		An elaborate family of Hox/HOM genes existed already in the ancestor of all triploblast animals; This confounds the ``gradist'' prediction that animals emerging earlier in evolution than the coelomates (lower Metazoa) have a simpler homeotic cluster, if any, than the higher Metazoa [G. Balavoline and M. Telford, Proc.
		There is a stage of development at which the precursor to the body plan is actually visible.
	nausicaa.phys.chuo-u.ac.jp.cob-web.org:8888 /MDS/anima97/node3.html (287 words)

	The Mitochondrial Genome of Phoronis architecta--Comparisons Demonstrate that Phoronids Are Lophotrochozoan Protostomes ...
		same gene content as the triploblast animals studied here.
		The branch lengths are proportional to the number of substitutions calculated in the maximum-likelihood analysis.
		The triploblast taxa are the same as in figure 2.
	mbe.oxfordjournals.org /cgi/content/full/21/1/153 (2885 words)

	A Brief Review of Metazoan Phylogeny and Future Prospects in Hox-Research -- Halanych and Passamaneck 41 (3): 629 -- ...
		of mesoderm is used to distinguish between diploblasts and triploblasts.
		Current understanding of metazoan phylogeny suggests the triploblast categories are environmental, not phylogenetic, in nature
		traditionally considered to be basal triploblasts because they
	icb.oxfordjournals.org /cgi/content/full/41/3/629 (3781 words)

	Investigating the origins of triploblasty: `mesodermal' gene expression in a diploblastic animal, the sea anemone ...
		is the likely sister group of the triploblastic Bilateria.
		reinforces the hypothesis that the mesoderm and endoderm of triploblastic
		endoderm and mesoderm of triploblasts evolved from the endoderm
	dev.biologists.org /cgi/content/full/131/10/2463 (6739 words)

	The Panda's Thumb: Diploblasts and triploblasts
		Posted by gav on July 3, 2005 10:25 AM
		Any other reason to think, apart from this, that the common ancestor of protostomes and deuterostomes was itself a triploblast?
		I’m (evidently) completely out of my depth here and would appreciate a life-line.
	www.pandasthumb.org /archives/2005/06/diploblasts_and.html (291 words)

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