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At least 793 records · Page 44Linked to original sources
PubMed1996

Nuclear (DNA, RNA, histone and non-histone protein) and nucleolar changes during growth and senescence of may apple leaves.

Quantitative interference microscopy was used to determine changes in nuclear and nucleolar indices (dry mass and cross-sectional area) in upper and lower epidermal cells and adjacent leaf-margin hair cells of the May apple (Podophyllum peltatum L.) leaves over a 42-day period (after leaves emerged above the ground litter). These indices decreased in a highly correlated manner. A ploidy variation may exist between epidermal cells and leaf-margin hair cells. Using the leaf-margin hair cells model, six nuclear macromolecule indices (total nucleic acid, DNA, RNA, total nuclear protein, histone and non-histone protein), nuclear volume, nucleolar volume and perinucleolar volume (measured using quantitative epifluorescence-phase contrast microscopy) all declined with age (42-day study) in a highly correlated manner. The degeneration of the nucleus and nucleolus in the three leaf locations studied followed the patterns observed for programmed cellular senescence and death (necrosis) in epidermal cells of onion leaf bases (stored tissue; leaf bases did not contain chlorophyll) and human epithelial cells (buccal; cervical). We conclude that the epidermal cells and leaf-margin hair cells from green leaves of the May Apple are ideal for the study of programmed cell senescence and death in plants, especially for the partitioning of this process into the study of: the point-of-no-return (solubilization of the karyoskeleton and loss of non-histone proteins and RNA associated with the karyoskeleton from the nucleus); nuclear pycnosis (loss of nuclear dry mass and volume and loss of nuclear internal support structure); chromatin condensation, margination along the inner nuclear envelope; and DNA-histone degeneration; degeneration of the nucleolus and loss of the perinucleolar zone of exclusion. The characterization of chlorenchyma cells during the 42-day period should now be undertaken (leaf senescence as indicated by the beginning of yellowing about 35 days after emergence) to determine whether these cells with functional chloroplasts undergo nuclear changes like those lacking functional chloroplasts.

Allium↗
PubMed1978

Colonic response to dietary fibre from carrot, cabbage, apple, bran.

Approximately 20 g/day of concentrated dietary fibre from carrot, cabbage, apple, bran, and guar gum was added to the controlled basal diet of nineteen healthy volunteers. Faecal weight increased by 12% on bran, 69% on cabbage, 59% on carrot, 40% on apple, and 20% on guar gum. These changes in faecal weight were correlated with an increased intake of pentose-containing polysaccharides from the fibre. On the basal diet there were pronounced individual differences in faecal weight, and from these the response of subjects to the fibre preparations could be predicted. Addition of fibre shortened mean transit-time through the gut and significantly diluted an inert marker in the faeces. Diet-induced changes in colonic function may explain international differences in the prevalence of colonic disease, whilst personal variation in the response to dietary fibre may determine individual susceptibility to large-bowel disease within a community.

Adult↗
PubMed1999

Catch a falling apple: Isaac Newton and myths of genius.

Newton has become a legendary figure belonging to the distant past rather than a historical person who lived at a specific time. Historians and scientists have constantly reinterpreted many anecdotal tales describing Newton's achievements and behaviour, but the most famous concerns the falling apple in his country garden. Newton's apple conjures up multiple allegorical resonances, and examining its historical accuracy is less important than uncovering the mythical truths embedded within this symbol. Because interest groups fashion different collective versions of the past, analysing mythical tales can reveal fundamental yet conflicting attitudes towards science and its practices.

History, 18th Century↗
PubMed2001

Comparison of bioassays and laboratory assays for apple stem grooving virus.

The standard field double-budding assay with the indicator Virginia Crab and the glasshouse test with the indicator Malus micromalus, were compared with ELISA and immunocapture PCR for the detection of Apple stem grooving virus (ASGV) in 102 apple trees and three oriental pear. Twenty-two trees were positive for ASGV by both ELISA and IC-PCR but three of these trees were negative by Virginia Crab, three were negative by M. micromalus and one was negative by both these bioassays. The infected trees were re-tested by IC-PCR and ELISA in a second year; the IC-PCR results were confirmed but two of the 22 infected trees were negative by ELISA. On this evidence, IC-PCR is a more reliable assay for ASGV than the slow and expensive bioassays.

Base Sequence↗
PubMed2004

Attachment of Escherichia coli O157:H7 grown in tryptic soy broth and nutrient broth to apple and lettuce surfaces as related to cell hydrophobicity, surface charge, and capsule production.

This study investigated the effect of growth in tryptic soy broth (TSB) and nutrient broth (NB) on the ability Escherichia coli O157:H7 to attach to lettuce and apple surfaces. In addition, cell surface hydrophobicity, charge and capsule production were determined on cells grown in these media. Cells grown in NB attached less to lettuce and apple surfaces than did those grown in TSB. TSB, but not NB, supported capsule production by E. coli O157:H7. Cells grown in TSB were more hydrophilic than those grown in NB. No difference was found in the electrokinetic properties of cells grown in these media. Electrostatic and hydrophobic interactions and surface proteins did not appear to play an important role in the attachment of E. coli O157:H7 to these surfaces. Of the factors studied, only capsule production was associated with attachment ability.

Bacterial Adhesion↗
PubMed1998

Rapid detection of Escherichia coli O157:H7 using immuno-magnetic flow cytometry in ground beef, apple juice, and milk.

A rapid method combining flow cytometry and immunomagnetic bead separation (IMFC) was effective for detecting low populations of Escherichia coli O157:H7 inoculated into ground beef, apple juice, and raw milk samples. Modified buffered peptone was most effective for enrichment of E. coli O157:H7 in ground beef. Using IMFC in combination with a 6-h enrichment, as few as four E. coli O157:H7 cells/g of ground beef were detected in as little as a 7-h total analysis time. Our results demonstrate the possibility of using flow cytometry and immunomagnetic bead separation to detect low concentrations of E. coli O157:H7 in ground beef, apple juice and milk.

Animals↗
PubMed1997

Production of Aspergillus niger pectolytic enzymes by solid state bioprocessing of apple pomace.

The aim of this work was to develop a low cost process for apple pomace utilisation. Accordingly this production of pectynolitic enzymes based on solid state bioprocessing of this actual waste, was developed. Production of pectolytic enzymes of Aspergillus niger, pectinesterase and polygalacturonase as well as the activity of pectolytic enzymatic complex by solid state bioprocessing were studied. The results of preliminary substrate optimization, on open trays in laboratory scale experiments, were transferred to 15 1 horizontal solid state stirred tank reactor (HSS STR). In situ sterilization of solid substrate with periodical mixing was used. Secondary raw material, apple pomace the waste from food and agriculture industry combined with soya flour, wheat bran and simple mineral salts was utilised. Various substrate moistures were studied. Process parameters such as inoculation, influence of mixing, aeration, temperature and moisture content on pectolytic enzymes production were studied. Maximal amounts of 15 g kg-1 of solid medium of polygalacturonase, 200 mg kg-1 pectinesterase at activity up to 900 AJDA U ml-1 of enzyme mixture was obtained on average.

Aspergillus niger↗
PubMed1996

Enumeration of bacterial and yeast colonists of apple fruits and identification of epiphytic yeasts on pear fruits in the Pacific Northwest United States.

A procedure for the isolation of diverse culturable microflora for the estimation of the population size of yeasts and bacteria on the surface of pome fruits is described. Maximum numbers of morphologically distinct colonies of both yeasts and bacteria were recovered from apple fruit surfaces when fruits were shaken for 5 min in sterile phosphate buffer plus tween, sonicated for 5 min, and aliquots of the buffer plated onto diluted yeast malt agar and diluted nutrient broth agar, respectively. The yeast and bacterial populations on the surface of unsprayed Golden Delicious apple fruits were approximately 8.0 x 10(3) and 9.5 x 10(4) colony forming units (cfu) per cm2, respectively. The densities of yeasts on the surface of pear fruits collected from Yakima, Wa, Cascade Locks, Medford, and Hood River, OR, were approximately 7.3 x 10(3), 6.4 x 10(3), 4.1 x 10(3), and 9.9 x 10(2) cfu.cm-2, respectively. The highest number of morphologically different yeast isolates were recovered from pear fruits from Cascade Locks and Hood River, Oregon and Yakima, Washington. Aureobasidium pullulans was present on fruits in all pear orchards sampled whereas Cryptococcus albidus and Rhodotorula glutinis were isolated from 80% of the orchards. Other yeasts colonizing pear fruit surfaces in 20-60% of the orchards were Cryptococcus infirmo-miniatus, Cryptococcus laurentii, Debaryomyces hansenii, Rhodotorula aurantiaca, R. fujisanensis, R. minuta and Sporobolomyces roseus.

Bacteria↗
PubMed2000

An outbreak of Escherichia coli O157:H7 infections and haemolytic uraemic syndrome associated with consumption of unpasteurized apple cider.

During October 1996, an outbreak of Escherichia coli O157:H7 infections among Connecticut residents occurred. An epidemiologic investigation included enhanced surveillance and a case-control study. Clinical isolates of Escherichia coli O157:H7 were typed by pulsed-field gel electrophoresis (PFGE). Implicated cider samples were analysed by culture and polymerase chain reaction (PCR). Consumption of implicated cider was associated with illness; (matched odds ratio = undefined, 95 % confidence interval = 3.5-infinity). Ultimately, a total of 14 outbreak-associated patients were identified. All isolates analysed by PFGE yielded the outbreak-associated subtype. Escherichia coli O157:H7 was not cultured from three cider samples; PCR analysis detected DNA fragments consistent with Escherichia coli O157:H7 in one. This outbreak was associated with drinking one brand of unpasteurized apple cider. PFGE subtyping supported the epidemiologic association. PCR analysis detected microbial contaminants in the absence of live organisms. Washing and brushing apples did not prevent cider contamination.

Adolescent↗
PubMed2000

Application of directly coupled HPLC-NMR-MS to the identification and confirmation of quercetin glycosides and phloretin glycosides in apple peel.

Directly coupled HPLC-NMR-MS was used to identify and confirm the presence of quercetin O-glycosides and phloretin O-glycosides in an extract of apple peel. From the MS and MS/MS data, the molecular weights of the intact molecules as well as those of quercetin and phloretin and their sugar moieties were deduced. The NMR data provided information on the identity of the compounds as well as the alpha and beta conformations and the position of the glycosides on quercetin and phloretin. The following O-glycosides of quercetin could be identified: quercetin-3-alpha-L-rhamnosyl-(1-->6)-beta-D-glucoside (rutin), quercetin-3-beta-D-galactoside (hyperin), quercetin-3-beta-D-glucoside (isoquercitrin), quercetin-3-beta-D-xyloside (reynoutrin), quercetin-3-alpha-L-arabinofuranoside (avicularin), and quercetin-3-alpha-L-rhamnoside (quercitrin). Phloretin was present as phloretin-2'-beta-D-glucoside (phloridzin) and the 2'-beta-D-xylosyl-(1-->6)-beta-D-glucoside. Concentrations were between 0.2 and 5 mg/g of apple peel.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

High-pressure processing of apple juice: kinetics of pectin methyl esterase inactivation.

High-pressure (HP) inactivation kinetics of pectin methyl esterase (PME) in apple juice were evaluated. Commercial PME was dispensed in clarified apple juice, sealed in dual peel sterilizable plastic bags, and subjected to different high-pressure processing conditions (200-400 MPa, 0-180 min). Residual enzyme activity was determined by a titration method estimating the rate of free carboxyl group released by the enzyme acting on pectin substrate at pH 7.5 (30 degrees C). The effects of pressure level and pressure holding time on enzyme inactivation were significant (p < 0.05). PME from the microbial source was found to be more resistant (p < 0.05) to pressure inactivation than PME from the orange peel. Almost a full decimal reduction in the activity of commercial PME was achieved by HP treatment at 400 MPa for 25 min. Inactivation kinetics were evaluated on the basis of a dual effect model involving a pressure pulse effect and a first-order rate model, and the pressure sensitivity of rate constants was modeled by using the z-value concept.

Algorithms↗
PubMed2006

Trichloroethylene uptake by apple and peach trees and transfer to fruit.

A greenhouse study was conducted to quantify 14C-trichloroethylene (TCE) uptake and transfer into the edible fruit of apple and peach trees. Trees were subsurface irrigated with solutions of 14C [TCE] that bracketed groundwater concentrations (5 and 500 microg/L) found in residential areas surrounding Hill Air Force Base, UT, where trace amounts of TCE had been found in several fruits during a preliminary field survey. Nondosed control trees were grown within the canopy of the dosed trees and in a separate greenhouse. Tissue samples were analyzed for 14C and TCE using combustion/liquid scintillation counting (LSC) and headspace/gas chromatography/mass spectrometry (HS/GC/MS). Tissue was also extracted and analyzed by GC/MS for dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), and trichloroethanol (TCEt), three specific TCE metabolites that have been previously identified in laboratory and field studies. No 14C was detected in the nonexposed control trees. Exposed trees contained levels of 14C that were proportional to the exposure concentration. 14C concentrations were greatest in leaves followed by branches and fruits. At the end of the study, TCE was detected only in roots implying that the 14C in the leaves, branches, and fruit was associated with unidentified nonvolatile TCE transformation products and/or is nonextractable. However, TCAA and DCAA were positively identified only in leaves collected during the first year from an apple tree exposed to the high dose treatment. Additional data for other chemicals and fruittrees are needed to better understand the potential transfer of organic compounds to edible fruit.

Carbon Isotopes↗
PubMed2001

Comparative degradation of [14C]-2,4-dichlorophenoxyacetic acid in wheat and potato after Foliar application and in wheat, radish, lettuce, and apple after soil application.

The fate of 2,4-dichlorophenoxyacetic acid (2,4-D) applied foliarly as the 2-ethylhexyl ester (EHE) to wheat and potatoes, to the soil as the dimethylamine (DMA) salt under apple tree canopies, and preplant as the free acid for wheat, lettuce, and radish was studied to evaluate metabolic pathways. Crop fractions analyzed for (14)C residues included wheat forage, straw, and grain; potato vine and tubers; and apple fruit. The primary metabolic pathway for foliar application in wheat is ester hydrolysis followed by the formation of base-labile 2,4-D conjugates. A less significant pathway for 2,4-D in wheat was ring hydroxylation to give NIH-shift products 2,5-dichloro-4-hydroxyphenoxyacetic acid (4-OH-2,5-D), 4-OH-2,3-D, and 5-OH-2,4-D both free and as acid-labile conjugates. The primary metabolic pathway in potato was again ester hydrolysis. 2,4-D acid was further transformed to 4-chlorophenoxyacetic acid and 4-OH-2,5-D. For the soil applications, (14)C residues in the crops were low, and characterization of the (14)C residues indicated association with or incorporation into the biochemical matrix of the tissue. The degradative pathways observed in wheat are similar to those characterized in other intact plant studies but differ from those in studies in wheat cell suspension culture in that no amino acid conjugates were observed.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2000

Effect of enzymatic and chemical oxidation on the antioxidant capacity of catechin model systems and apple derivatives.

Changes in the chain-breaking activity of catechin model systems and apple derivatives were studied as a consequence of enzymatic and chemical oxidation. Although in different time scales, both enzymatic and chemical oxidations of catechin promoted an initial increase and a following decrease in the chain-breaking activity. The latter was associated with the formation of brown pigments. Similar changes were detected during storage at -18 degrees C of nonoxidized and enzymatically oxidized apple purees. The initial increase in antioxidant activity upon oxidation was attributed to the formation of procyanidins with larger aromatic structure and to synergy effects among them. The formation of tannins, the reactivity of which is sterically hindered, was proposed as a possible explanation for the decrease in antioxidant capacity in the advanced phases of oxidation.

Antioxidants↗
PubMed2000

Inhibitory effects of apple polyphenols and related compounds on cariogenic factors of mutans streptococci.

The inhibitory effects of apple polyphenols (APP) on the synthesis of water-insoluble glucans by glucosyltransferases (GTF) of streptococci of the mutans group and on the sucrose-dependent adherence of the bacterial cells were examined in vitro. APP markedly inhibited the activity of GTF purified from the cariogenic bacterial cells. However, APP showed no significant effect on the growth of the cariogenic bacteria. The strongest GTF inhibitors in APP were apple condensed tannins (ACT), a mixture of procyanidins. The 50% inhibitory doses of ACT against the GTF of S. sobrinus and that of S. mutans were 1.5 microgram/mL and 5 microgram/mL, respectively. The ACT efficacy largely depended upon the degree of polymerization. Interestingly, while the other polyphenols known to inhibit GTF such as tannic acid markedly inhibited salivary alpha-amylase activity, APP and ACT only scarcely inhibited that enzyme activity. This means that APP and ACT might selectively inhibit the bacterial GTF activity under oral conditions.

Bacterial Adhesion↗
PubMed2000

Transgenic apple (Malus x domestica) shoot showing low browning potential.

Transgenic apple shoots were prepared from leaf disks by using Agrobacterium tumefaciens carrying the kanamycin (KM) resistance gene and antisense polyphenol oxidase (PPO) DNA. Four transgenic apple lines that grew on the medium containing 50 microgram/mL KM were obtained. They contained the KM resistance gene and grew stably on the medium for >3 years. Two transgenic shoot lines containing antisense PPO DNA in which PPO activity was repressed showed a lower browning potential than a control shoot.

Agrobacterium tumefaciens↗
PubMed2001

Impacts of ionizing radiation on volatile production by ripening gala apple fruit.

Apple (Malus x domestica Borkh., cv. Gala) fruit treated with 0.5 microL x L(-1) 1-methylcyclopropene (MCP) or air (non-MCP) for 12 h at 20 degrees C were exposed to gamma radiation at doses of 0, 0.44, 0.88, or 1.32 kGy at 23 degrees C and then stored at 20 degrees C. Production of volatile compounds was measured on the day of irradiation and 1, 3, 7, 14, and 21 days after irradiation. Both MCP treatment and irradiation inhibited ethylene production. MCP treatment reduced production of all volatile esters and alcohols detected, whereas irradiation inhibited production of most, but not all, esters and some alcohols by non-MCP-treated fruit. The inhibition of volatile production following irradiation increased with dose. Production of methyl and propyl esters was inhibited more than that of other esters following irradiation or MCP treatment. The impact of irradiation on production of esters and alcohols by MCP-treated fruit was minimal. Non-MCP-treated fruit irradiated at 0.44 kGy produced the most esters during the 21-day period at 20 degrees C following irradiation, and the ester production rate in these fruit was comparable to that of the nonirradiated fruit 21 days after irradiation. Fruit treated with doses higher than 0.44 kGy did not recover their ability to produce volatile compounds. These results indicate both MCP and ionizing radiation inhibit production of many aroma compounds produced by ripening apple fruit.

Alcohols↗
PubMed2002

Investigations of aroma volatile biosynthesis under anoxic conditions and in different tissues of "Redchief Delicious" apple fruit (Malus domestica Borkh.).

Disks from different tissues were obtained from "Redchief Delicious" apple fruit (Malus domestica Borkh.) and analyzed for the ability to metabolize 1-pentanol as well as synthesize constitutive esters and alcohols under anoxic and aerobic conditions. The skin tissue displayed a greater capacity to synthesize pentanal, pentyl acetate, pentyl propionate, pentyl butyrate, and pentyl hexanoate than the hypanthial and carpellary tissues during incubation with 1-pentanol. With the exception of pentyl acetate and pentyl propionate biosynthesis, the hypanthial tissue synthesized these compounds at a higher rate than the carpellary tissue. Anoxia inhibited both constituent and 1-pentanol-derived ester biosynthesis. While anoxia inhibited ester biosynthesis, ethanol biosynthesis increased at a greater rate in tissue disks held under these conditions. Biosynthesis of 1-butanol, 2-methyl-1-butanol, and 1-hexanol was greater in tissue disks held in air during the first part of the measurement period and dropped off more rapidly than those transpiring in tissue disks held under anoxic conditions. The biosynthetic rates of all esters, both constituent and 1-pentanol-derived, increased as a result of air exposure. While hypoxic or anoxic conditions may promote ethanol synthesis, these conditions also appear to inhibit the formation of the ethanol-derived esters partially responsible for the off-flavor in apples attributed to ultralow O(2) controlled atmosphere storage.

Alcohols↗