(1) Because ctenophore and all other known metazoan mtDNA is circular, the shared occurrence of linear mtDNA in three of the four cnidarian classes suggests a basal position for the Anthozoa within the phylum.
(2) Cloning of three Antennapedia-related sequences from cnidarians provides evidence of ancient roles for homeobox genes early in metazoan evolution.
(3) Cnidocytes, the stinging cells of cnidarians, discharge nematocysts in response to physical contact accompanied by the stimulation of specific chemoreceptors.
(4) It is suggested that they may also be present as predominant components in nematocysts of other cnidarian species and thus might represent a class of compounds which is characteristic for a whole phylum of the animal kingdom.
(5) The principal sources of these agents are bacteria, higher fungi, cnidarians (coelenterates) and the venoms of snakes, insects and other arthropods.
(6) The presence of cholecystokinin (CCK), originally isolated from porcine small intestine, has been reported in a diversity of invertebrates ranging, from cnidarians to protochordates, but so far, not in echinoderms.
(7) Cnidarians arose from a protist ancestry different from the second group, the Bilateria.
(8) In these trees, cnidarians (Radiata) seemed to have evolved independently from the Bilateria, which is in contradiction with the general evolutionary view.
(9) It is present in all cnidarians and can be isolated without enzyme treatment.
(10) The ganglion has been compared to the nervous systems in cnidarians, some spiralians, and especially other hemichordates, echinoderms, and chordates; it is found to be of primitive rather than degenerate nature.
(11) We report the nucleotide sequence of eveC, a cnidarian eve-class homeobox; this is the first homeobox to be identified in any diploblastic organism, and is only the second eve-class in an invertebrate.
(12) We previously characterized annexin XII from the freshwater cnidarian Hydra vulgaris (Schlaepfer, D. D., D. A. Fisher, M. E. Brandt, H. R. Bode, J. Jones, and H. T. Haigler.
(13) This report describes the cloning and sequencing of both cDNA and genomic clones of GFP from the cnidarian, Aequorea victoria.
(14) Eggs from all of the animals considered are covered by complex vitelline envelopes except those of cnidarians.
(15) The application of molecular techniques to cnidarians can provide important insights into developmental processes and phylogenetic relationships both within the phylum Cnidaria and among the eumetazoa.
(16) A new system is described for the study of ECM-tissue interactions, using the ECM (called mesogloea) of various cnidarians and isolated striated muscle and endodermal tissue of jellyfish.
(17) gamma-Glutamyltransferase activity was studied in extracts of the cnidarian Hydra attenuata.
(18) The results show that: polyps under normal conditions have similar regeneration patterns, regardless of individual variability; and ATxII, a neurotoxin of cnidarian origin, produces a statistically significant increase in the Tentacle Regeneration Index.
(19) In the context of earlier observations in cnidarians, these cytological features suggest a sensory as well as a modulatory function for 5-HT in Renilla koellikeri.
(20) Specifically, sperm eggs from cnidarians, echinoderms, decapod crustaceans, ascidians, lampreys, bony fishes, and amphibians are discussed.
Holdfast
Definition:
(n.) Something used to secure and hold in place something else, as a long fiat-headed nail, a catch a hook, a clinch, a clamp, etc.; hence, a support.
(n.) A conical or branching body, by which a seaweed is attached to its support, and differing from a root in that it is not specially absorbent of moisture.
Example Sentences:
(1) In addition, distribution of lead and cadmium varied within the individual producer (Fucus vesiculosus) in such a way that the holdfast exhibited the highest concentration followed by the apcial tip and the branches of the first dichotomy was the lowest.
(2) Thus, we propose that the attachment of the holdfast to the cell is a true adhesion process and that the stalk tip and base of the flagellum must have compositions distinctly different from that of the remainder of the caulobacter cell surface.
(3) Upon closer examination, they were distinguishable on the basis of protein band profiles on polyacrylamide gel electrophoresis, gross colony characteristics, or holdfast composition or by DNA restriction fragment length polymorphism analysis with flagellin and S-layer gene probes.
(4) The mutant could also attach to the discarded holdfast produced by a shedding mutant.
(5) Also, attachment to the cell is accomplished by bond formations that occur not only at the time of holdfast production.
(6) One class of mutants made a normal holdfast by all available criteria, yet the attachment to the cell was very weak, such that the holdfast was readily shed.
(7) Once attached the bacterium appears to undergo a complex life cycle which involves the development of a long filament divided into a number of segments within which holdfasts or spores are formed.
(8) Deletion and complementation analysis of the hfaAB locus revealed two genes in a single operon; both were required for holdfast attachment to the cell.
(9) The structure and distribution of papillae suggest that the ventral sucker likely functions as a holdfast organ and the oral sucker as a probing organ involved in feeding.
(10) The formation of the holdfast, cell walls and septa is followed.
(11) Within each mother cell two new holdfast segments developed.
(12) The paunch epithelium was densely colonized by bacteria, many of which possessed holdfast elements that secured them tightly to this tissue and to other bacterial cells.
(13) Caulobacters attach to surfaces in the environment via their holdfasts, attachment organelles located at the base of the flagellum in swarmer cells and later at the end of the cellular stalk in the stalked cells which develop from the swarmer cells.
(14) Taken together, the data support the interpretation that there is a specialized attachment site for the holdfast at the base of the flagellum which later becomes the end of the stalk, but not a specialized region of the holdfast for attachment to this site.
(15) The bacterium is attached to the epithelial cell by a special segment (holdfast) and causes specific changes in the epithelial cell at the site of attachment.
(16) This was unexpected, since holdfast deficiency is often a characteristic of pleiotropic mutants obtained when selecting for loss of other polar structures.
(17) This information suggests that the protein encoded by the hfaA locus may have a direct role in the attachment of the holdfast to the cell, whereas hfaB may be involved in the positive regulation of hfaC.
(18) A single prostheca extends from one pole of mature cells, and cells attach to various substrata by means of a holdfast located at the distal tip of the appendage.
(19) However, there was no subsequent division, or flagellum or holdfast synthesis.
(20) Alternately, in some filaments, newly formed but not yet released holdfasts were converted into endospores, which were released in the same manner as holdfasts, presumably to spread the bacterial colony to other members of the rodent population.