What's the difference between bract and leaf?

Bract


Definition:

  • (n.) A leaf, usually smaller than the true leaves of a plant, from the axil of which a flower stalk arises.
  • (n.) Any modified leaf, or scale, on a flower stalk or at the base of a flower.

Example Sentences:

  • (1) Enterobacter agglomerans was the most predominant bacterium on leaf and bract.
  • (2) Field-dried cotton bract, a contaminant of cotton dust, has been implicated in byssinosis pathogenesis.
  • (3) Cotton bract tannin is a potent stimulus for platelet aggregation and secretion.
  • (4) Byssinosis, COPD, cotton fever and cotton pneumoconiosis may be different types of responses due to the different duration of exposure, the different parts of bronchial tree (upper respiratory tract, small airway, and respiratory part) where deposition occurs, and the different components of cotton dust (broken cotton fibers, bracts, pericarps, bacteria, and fungi).
  • (5) Comparison of the cytotoxicity dose curves for aqueous bracts extracts with those for tannin demonstrated that tannin was the major cytotoxin present in bracts.
  • (6) Bract is the most abundant component in respirable raw cotton dust.
  • (7) After clearing and removal of the cuticle, the bracts are bleached, washed, dehydrated, and if studied by light microscopy, stained in 2% chlorazol black E and mounted in Diaphane; or, if studied by scanning electron microscopy, dried by the critical-point method and either left uncoated or coated with a film of various conductive metals.
  • (8) The human T lymphocyte proliferative response to cotton bract tannin was shown to be dependent upon the presence of monocytes.
  • (9) Pulmonary function measured by flow changes on partial expiratory flow volume curves was used to assess airway responses to the bract extracts after their inhalation by a panel of volunteers.
  • (10) The content of bract was unaffected by this harvest-aid practice.
  • (11) Raw cotton from 4 machine picked varieties and 2 machine stripped varieties is examined by stereomicroscope and bright-field microscopy for presence of plant trash(bract, leaf, stem, seed, boll, and weed fragments-size range 841-2000mum) that gives rise to cotton dust during yarn manufacturing operations.
  • (12) The effects of a water extract of cotton bracts (CBE) on guinea pig isolated trachealis smooth muscle was studied.
  • (13) The authors established an in vitro cytotoxicity assay using 51Cr release to assess time- and dose-dependent toxicity of condensed tannin, a component of bracts, on porcine aortic and pulmonary arterial endothelial cells.
  • (14) Senescence affected the population levels of the various genera on leaf and bract.
  • (15) The provenance of bristles and bracts suggests that the bristle cells move into their final positions.
  • (16) Mill workers are exposed to bract which has weathered in the field, but it is not known whether biologic effects of bract are due to intrinsic plant compound(s) or to contamination occurring during field weathering.
  • (17) To determine if constituents of cotton plants might play a role in byssinosis by injuring pulmonary epithelium, we added extracts of cotton dust, green bract, and field-dried bract to human A549 and rat type II pneumocytes.
  • (18) Macrophages obtained by bronchoalveolar lavage from volunteers pre-challenged with bract extract release increased amounts of chemotactic factor and superoxide anion.
  • (19) The role of nonspecific reactivity of the airways in this reaction to cotton bract extract is undefined.
  • (20) Extracts of cotton dust and field-dried bract produced significant dose- and time-dependent lysis and detachment of both target cells, while green bract extract was less damaging.

Leaf


Definition:

  • (n.) A colored, usually green, expansion growing from the side of a stem or rootstock, in which the sap for the use of the plant is elaborated under the influence of light; one of the parts of a plant which collectively constitute its foliage.
  • (n.) A special organ of vegetation in the form of a lateral outgrowth from the stem, whether appearing as a part of the foliage, or as a cotyledon, a scale, a bract, a spine, or a tendril.
  • (n.) Something which is like a leaf in being wide and thin and having a flat surface, or in being attached to a larger body by one edge or end; as : (a) A part of a book or folded sheet containing two pages upon its opposite sides. (b) A side, division, or part, that slides or is hinged, as of window shutters, folding doors, etc. (c) The movable side of a table. (d) A very thin plate; as, gold leaf. (e) A portion of fat lying in a separate fold or layer. (f) One of the teeth of a pinion, especially when small.
  • (v. i.) To shoot out leaves; to produce leaves; to leave; as, the trees leaf in May.

Example Sentences:

  • (1) The dumplings could also be served pan-fried in browned butter and tossed with a bitter leaf salad and fresh sheep's cheese for a lighter, but equally delicious option.
  • (2) Subsequently the plant protein was partially purified from leaf extract.
  • (3) In autumn, leaf-heaps composted themselves on sunken patios, and were shovelled up by irritated owners of basement flats.
  • (4) Isolated nuclei from green leaf tissue of tomato plants infected with potato spindle tuber viroid (PSTVd) were bound to microscope slides, fixed with formaldehyde and hybridized with biotinylated transcripts of cloned PSTVd cDNA.
  • (5) The nuclear membrane was highly deformed with a leaf-like profile in cross-section, possibly due to an interaction with the rod-like, condensed chromosomes.
  • (6) The mass of glycolic acid recovered from sunflower leaf tissue was proportional to the amount of tissue extracted.
  • (7) cDNA clones of potato virus X (PVXcp strain), potato virus Y (PVYo strain), potato leaf roll virus (PLRV) and potato spindle tuber viroid (PSTV) were used separately or combined for the detection of the corresponding RNAs in extracts of infected plants.
  • (8) Positive cDNA clones isolated from both a pea leaf and embryo lambda gt11 expression library using an antibody raised against the purified lipoamide dehydrogenase proved to be the product of a single gene.
  • (9) Betel leaf extract at the dose levels used in the present study did not affect the body weight gain among rats.
  • (10) Poison oak, ivy, and sumac dermatitis is a T-cell-mediated reaction against urushiol, the oil found in the leaf of the plants.
  • (11) Leaf TBC was usually third while fiber had the least TBC.
  • (12) Using this estimate, the pure Photosystem I emission spectrum was subtracted from the measured emission spectrum of a flashed leaf to give an emission spectrum representative of pure Photosystem II fluorescence at -196 degrees C. Emission spectra were also measured on flashed leaves which had been illuminated for several hours in continuous light.
  • (13) The effect of 50% methanolic extract (U-ext) from Bearberry leaf on immuno-inflammation was studied by contact dermatitis caused by picryl chloride (PC-CD) in mice.
  • (14) Several antisera from rabbits immunized with tobacco smoke components reacted by immunoprecipitation with tobacco smoke or leaf antigens.
  • (15) DNP treatment reduced ion absorption by leaf tissue.
  • (16) Instead, cell divisions are gradually restricted to the base of the leaf with localized sites of increased division at the preligule region.
  • (17) In the leaf-nosed bat, Macrotus californicus, a 4.5-month period of delayed early embryogenesis (October-March) precedes a 3.5-month period of normal embryogenesis (March-June).
  • (18) Plastic responses in leaf form resulting from ontogenetic or external influences are initiated very early in primordial development and are brought about by effects on the rate and direction of cell division and expansion in different regions of the primordium.
  • (19) Northern blot analysis of infected leaf tissue extracts revealed the presence of an oligomeric series of plus RNAs (of monomer size and greater) but minus RNAs were present only as high molecular weight species of heterogeneous size.
  • (20) And, hey, until Friday morning, most surveillance reform advocates were worried about the Senate ramming through the currently neutered version of the USA Freedom Act as its fig leaf of reform, before going back to business as usual and proposing bills that will give the NSA more power – not less.