and the origin of natural killer cells: Identification of a CD94/NKR-P1-related receptor in blood cells of Botryllus.
Systemic bud induction and retinoic acid signaling underlie whole body regeneration in the urochordate
Ascidians are members of the subphylum urochordates
, which is a group of the phylum chordates along with cephalochordates and vertebrates (Satoh, 2003).
Suppression of programmed cell death regulates cyclical degeneration of organs in a colonial urochordate
Brachyury (T) expression in embryos of a larvacean urochordate
, Oikopleura dioica, and the ancestral role of T.
It is present in urochordates
, cephalochordates, and larval lampreys, and its function is secretion of a mucous net to retain particles during feeding (Olsson, 1965; Deibel and Powell, 1987; Hiruta et al., 2005).
However, the expression of alternative oxidases and NADH dehydrogenases from urochordates
and fungi in mammalian cultured cells and in the fruitfly Drosophila melanogaster has proven to be benign and to counteract deleterious effects of defective OXPHOS systems, inspiring therapeutic possibilities for mitochondrial and related diseases.
(55) The most primitive group of chordates are the urochordates
, or tunicates, that have a sack-like adult body that filters seawater through pharyngeal slits.
Conversely, molecular cloning of [CB.sub.1]/[CB.sub.2] receptor orthologs has produced positive results only in urochordates
(the sea squirt, Ciona intestinalis), in cephalochordata (the amphioxus, Branchiostoma floridae), in nonmammalian vertebrates (fish, amphibians, reptiles, and birds), and in mammals, with duplication of [CB.sub.1] or [CB.sub.2] genes found in fish [49-51].
This last hypothesis is stressed by three facts: (i) the ancestors of vertebrates, the cephalochordates and urochordates
, are characterized by genomes that are neither GC-rich nor strongly methylated; (ii) mammals belonging to orders separated from each other by 100 million years display very similar methylation levels.
have short generation times, and the importance of these animals as contributor s to the high productivity in reef areas has been recognized.
Although snappers throughout the world are generally thought of as top level carnivores, several snapper species in the Pacific are known to incorporate significant amounts of zooplankton, often gelatinous urochordates
, in their diets (Parrish, 1987).
are monophyletic within the deuterostomes.
Originally identified in mammalian tissues, NO has been identified in the signaling cascades of many invertebrates such as coelenterates, platyhelminths, nematodes, annelids, molluscs, arthropods, echinoderms, and urochordates
(Martinez, 1995; Midler, 1997).
The pelagobenthic life cycle is by far the most common life cycle in the ocean, and is shared by almost all marine invertebrate phyla, from sponges to echinoderms and urochordates
. It is characterized by a planktonic larval dispersal phase that ends with settlement onto the substratum and metamorphosis into the benthic adult form.