(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.
Substrate
Definition:
(n.) A substratum.
(a.) Having very slight furrows.
(v. t.) To strew or lay under anything.
Example Sentences:
(1) 5-HT thus appears to be the preferred substrate for uptake into platelets and for movement from cytoplasm to vesicles.
(2) Some common eye movement deficits, and concepts such as 'the neural integrator' and the 'velocity storage mechanism', for which anatomical substrates are still sought, are introduced.
(3) These results demonstrate that increased availability of galactose, a high-affinity substrate for the enzyme, leads to increased aldose reductase messenger RNA, which suggests a role for aldose reductase in sugar metabolism in the lens.
(4) The common polyamines, spermidine and spermine, and histones were not substrates.
(5) Manometric studies with resting cells obtained by growth on each of these sulfur sources yielded net oxygen uptake for all substrates except sulfite and dithionate.
(6) The PSB dioxygenase system displayed a narrow substrate range: none of 18 sulphonated or non-sulphonated analogues of PSB showed significant substrate-dependent O2 uptake.
(7) The observed relationship between prorenin and renin substrate concentrations might be a consequence of their regulation by common factors.
(8) This theory was confirmed by product analysis and by measuring the affinity of the substrate for the enzyme by its inhibition of p-nitrophenyl glucoside hydrolysis.
(9) Yields of Thiobacillus dentrificans on different substrates were compared.
(10) It includes preincubation of diluted plasma with ellagic acid and phospholipids and a starting reagent that contains calcium and a chromogenic peptide substrate for thrombin, Tos-Gly-Pro-Arg-pNA.
(11) The present results provide no evidence for a clear morphological substrate for electrotonic transmission in the somatic efferent portion of the primate oculomotor nucleus.
(12) Fluorination with [18F]acetylhypofluorite yields 6-[18F]fluoro-L-dopa with 95% radiochemical purity; fluorination of the same substrate with [18F]F2 yields a mixture of all three structural isomers in a ratio of 70:16:14 for 6-, 5-, and 2-fluoro compounds.
(13) The enzyme, when assayed as either a phospholipase A2 or lysophospholipase, exhibited nonlinear kinetics beyond 1-2 min despite low substrate conversion.
(14) The stopped-flow technique was used to measure the rate constants for the reactions between the oxidized forms of peroxidase with luminol and the following substrates: p-iodophenol, p-bromophenol, p-clorophenol, o-iodophenol, m-iodophenol, luciferin, and 2-iodo-6-hydroxybenzothiazole.
(15) The time-course and dose-response for this modification of pp60c-src paralleled PDGF-induced increases in phosphorylation of pp36, a major cellular substrate for several tyrosine-specific protein kinases.
(16) Control incubations revealed an inherent difference between the two substrates; gram-positive supernatants consistently contained 5% radioactivity, whereas even at 0 h, those from the gram-negative mutant released 22%.
(17) Uptake could be supported either by substrate oxidation or by adenosine 5'-triphosphate (ATP), and was inhibited in the former case by antimycin or cyanide, in the latter case by oligomycin, and in both cases by 2,4-dinitrophenol.
(18) These results indicate that both the renal brush-border and basolateral membranes possess the Na(+)-dependent dicarboxylate transport system with very similar properties but with different substrate affinity and transport capacity.
(19) Congenitally deficient plasmas were used as the substrate for the measurement of procoagulant activities in a one-stage clotting assay.
(20) This capacity is expressed during incubation of the bacteria with the substrate and needs a source of carbon and other energy metabolites.