(1) At 5 hr, gastrulation has occurred in the absence of any structure comparable to the echinoid hyaline layer; therefore, at least one important mechanism proposed for echinoid gastrulation cannot occur in this crinoid.
(2) This is done from a comparative perspective, with reference to members of the five extant echinoderm classes; crinoids, holothurians, asteroids, ophiuroids, and echinoids.
(3) Several species of fish are deterred from eating food by the inclusion in it of these sulphates at the concentration found in crinoids.
(4) We report the results of cutting experiments on embryos of the crinoid Florometra serratissima, which produce, in the doliolaria stage, a striped pattern of ciliary bands.
(5) We have examined echinoderms from the five existing classes (echinoids, asteroids, ophiuroids, holothurians and crinoids) for the expression of these specific phosphagen kinases in different tissues.
(6) The range of (presumed) polyketide constituents in comatalid crinoids has been extended to include bianthronyls, meso-naphthodianthrones and sulphate esters of various of the polyketides.
(7) In contrast, the obliquely striated fibres of crinoids show markedly continuous and homogeneous oblique Z-lines; such a structure is not compatible with 'super-performances' like sliding and shearing of the sarcomere elements, but instead could allow functions comparable to those characteristic of a cross-striated muscle (quick, short movements, mechanically amplifiable by bone levers).
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.