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At least 289 records · Page 16Linked to original sources
PubMed2006

A general method for the extraction of citrus leaf proteins and separation by 2D electrophoresis: a follow up.

With the aim of studying differentially expressed proteins as a function of abiotic and biotic stress in citrus plants, we optimized a protocol for the extraction of total leaf proteins and their 2-DE separation using commercially available immobilized pH gradient strips (IPGs) in the first dimension. Critical factors for good reproducibility of citrus leaf protein separation were identified: trichloroacetic acid (TCA)/acetone precipitation after extraction in lysis buffer, sample fractionation on narrow range overlapping IPGs and sample-cup loading at the anodic or cathodic end of the strip. The use of thiourea and a strong detergent (C7BzO) in the solubilization/rehydration buffer, coupled with the increase to 10% of SDS in the equilibration buffer before the second dimension seemed to affect positively the resolution of basic proteins. Using our protocol we resolved about 30 basic proteins on 6.3-8.3 pH range strips. Further, our protocol was successfully applied reproducibly on the analysis of control and salt exposed leaf samples of Citrus reshni Hort. Ex Tan.

Citrus↗
PubMed2007

Combination of multispectral remote sensing, variable rate technology and environmental modeling for citrus pest management.

The Lower Rio Grande Valley (LRGV) of south Texas is an agriculturally rich area supporting intensive production of vegetables, fruits, grain sorghum, and cotton. Modern agricultural practices involve the combined use of irrigation with the application of large amounts of agrochemicals to maximize crop yields. Intensive agricultural activities in past decades might have caused potential contamination of soil, surface water, and groundwater due to leaching of pesticides in the vadose zone. In an effort to promote precision farming in citrus production, this paper aims at developing an airborne multispectral technique for identifying tree health problems in a citrus grove that can be combined with variable rate technology (VRT) for required pesticide application and environmental modeling for assessment of pollution prevention. An unsupervised linear unmixing method was applied to classify the image for the grove and quantify the symptom severity for appropriate infection control. The PRZM-3 model was used to estimate environmental impacts that contribute to nonpoint source pollution with and without the use of multispectral remote sensing and VRT. Research findings using site-specific environmental assessment clearly indicate that combination of remote sensing and VRT may result in benefit to the environment by reducing the nonpoint source pollution by 92.15%. Overall, this study demonstrates the potential of precision farming for citrus production in the nexus of industrial ecology and agricultural sustainability.

Agriculture↗
PubMed1998

Application of ion-exchange cartridge clean-up in food analysis. I. Simultaneous determination of thiabendazole and imazalil in citrus fruit and banana using high-performance liquid chromatography with ultraviolet detection.

A simple, rapid and reproducible analytical method for thiabendazole (TBZ) and imazalil (IMA) in citrus fruit and banana has been developed. The method involves the use of an ion-exchange cartridge for sample clean-up followed by ion-pair high-performance liquid chromatography with ultraviolet detection. The recoveries of TBZ and IMA from citrus fruits spiked at levels of 10 microgram/g and 5 microgram/g were in the range of 94-98% and 93-98% with coefficients of variation of 0.5-2.2% and 1.6-2.7%, respectively. The recoveries of TBZ and IMA from banana spiked at levels of 3 microgram/g and 2 microgram/g were 94% and 94% with coefficients of variation 1.1% and 4.9%, respectively. The detection limits for TBZ and IMA were 0.1 microgram/g in citrus fruit and 0.05 microgram in banana.

Anthelmintics↗
PubMed2003

Flavanone 3-hydroxylase expression in Citrus paradisi and Petunia hybrida seedlings.

Petunia hybrida and Citrus paradisi have significantly different flavonoid accumulation patterns. Petunia sp. tend to accumulate flavonol glycosides and anthocyanins while Citrus paradisi is known for its accumulation of flavanone diglycosides. One possible point of regulation of flavanone metabolism is flavanone 3-hydroxylase (F3H) expression. To test whether this is a key factor in the different flavanone usage by Petunia hybrida and Citrus paradisi, F3H mRNA expression in seedlings of different developmental stages was measured using semi-quantitative RT-PCR. Primers were designed to conserved regions of F3H and used to amplify an approximately 350 bp segment for quantitation by PhosphorImaging. Primary leaves of 32 day old grapefruit seedlings and a grapefruit flower bud had the highest levels of F3H mRNA expression. Petunia seedlings had much lower levels of F3H mRNA expression relative to grapefruit. The highest expression in petunia was in primary leaves and roots of 65 day old seedlings. These results indicate that preferential use of naringenin for production of high levels of flavanone glycosides in young grapefruit leaves cannot be attributed to decreased F3H mRNA expression.

Amino Acid Sequence↗
PubMed1998

Changes in arginine, PAL activity, and nematode behavior in salinity-stressed citrus.

De novo arginine biosynthesis has been described as a response of citrus to a range of stresses. It is often noted that stress in plants enhances susceptibility to herbivory and pathogenic attack. Using a citrus and nematode (Tylenchulus semipenetrans) system, the effects of salinity stress on nematode behavior, amino acids (particularly arginine), and phenylalanine ammonia lyase (PAL) activity was investigated. The hypothesis was tested that under salinity stress, citrus grows more slowly and produces arginine in response to high levels of in vivo ammonia, resulting in lower PAL activity and increased susceptibility to nematode attack. After 30 days of high salinity (0.1 M NaCl), plants exhibited a 38% reduction in growth, 35% reduction in PAL activity, and had 54% higher infection rates. PAL activity was inversely correlated (P < or = 0.05) with salinity level and with increase in arginine concentration.

Animals↗
PubMed1980

Does dietary elimination in infancy prevent or only postpone a food allergy? A study of fish and citrus allergy in 375 children.

In a study of fish and citrus allergy these foods were strictly avoided in 177 children up to 1 year of age, whereas 152 children had started taking fish before age 6 months and 145 children had started taking citrus fruits beofre 3 months. Both fish and citrus allergy, defined by a positive challenge, were found at age 3 years in a similar frequency (about 3%) in children with and without the first-year elimination. The results suggest that food allergy in childhood can be postponed but not prevented by dietary elimination in infancy.

Age Factors↗
PubMed2000

A new procedure to differentiate citrus tristeza virus isolates by hybridisation with digoxigenin-labelled cDNA probes.

A non-isotopic hybridisation procedure was developed to differentiate isolates of citrus tristeza virus (CTV) using digoxigenin (DIG)-labelled cDNA probes and different kinds of target RNA. Hybridisation of DIG-probes with purified double-stranded RNA (dsRNA) or concentrated total RNA extracts spotted on nylon membranes allowed detection of CTV nucleic acid equivalent to as little as 0.1-1 mg infected tissue, when the reaction was developed with a chemiluminiscent substrate. This sensitivity was similar to or slightly better than that obtained by hybridisation with a 32P-labelled probe. CTV was also detectable by hybridisation of DIG-probes with tissue prints from freshly cut young citrus shoots. Hybridisation of tissue prints with DIG-probes under stringent conditions (60 degrees C and 50% formamide) could differentiate CTV isolates in citrus, whether grown in the greenhouse or in the field. This rapid and sensitive procedure can easily be applied to many samples, even under field conditions, and opens the way to monitoring spatio-temporal movement of specific CTV strains (or groups of strains) in epidemiological studies.

Antibodies, Monoclonal↗
PubMed2001

Molecular characterization of cDNA clones for ADP-glucose pyrophosphorylase from Citrus.

Two cDNA clones encoding ADP-glucose pyrophosphorylases have been isolated from fruit and leaf cDNA libraries of Citrus (Citrus unshiu Mac. cv. Miyagawa) in which one was designated as agpS for the small subunit and the other as agpL for the large subunit. Both cDNAs have uninterrupted open reading frames deriving 57-58 kDa polypeptides. The deduced amino acid sequence of agpS has a unique feature. That is, it lacks a cysteine residue (Cys-12) which is usually conserved in all other dicot enzymes. This is the first report of agpS lacking Cys-12 among dicot small subunits. The expression pattern of both subunits showed a different profile in which leaves synthesized both agpS and agpL more vigorously than those of fruits. During leaf development, the transcripts of agpS and agpL showed a higher expression level at younger stages. During fruit development, the expression level of both subunits was observed to be highest in the mini-green stage, but it decreased in the small green stage and it increased again towards the maturing stage. These results suggest that both subunits may play an important role in the regulation of Citrus fruit and leaf development.

Amino Acid Sequence↗
PubMed2000

Molecular cloning of a homologue of dad-1 gene in citrus: distinctive expression during fruit development.

A cDNA homologue to the human defender against apoptotic death gene (dad-1), which is involved in programmed cell death, was isolated from satsuma mandarin (Citrus unshiu Marc.) fruit. It (Citdad-1-1) was 345 bp long, with a deduced protein sequence of 115 amino acids. Southern hybridization suggests that dad-1-related sequences are present as a small gene family in the citrus genome. Expression of Citdad-1-1 was progressively down-regulated in leaves as they matured, but not in juice sac/segment epidermis (edible part) towards fruit ripening. The role of dad-1 during citrus development is also discussed.

Amino Acid Sequence↗
PubMed1997

Characterization of the 3' proximal gene of the citrus tristeza closterovirus genome.

The 3' proximal open reading frame (ORF 11) in the citrus tristeza virus (CTV) genome potentially encodes a protein of 209 amino acids with an estimated molecular weight of 23 kDa (p23). The p23 ORF from the severe Florida strain T36 of CTV was expressed in Escherichia coli, and the expressed protein was used to raise polyclonal antibodies in a rabbit. Using these antisera on a Western blot, a protein of expected size (23 kDa) was detected in tissue extracts from CTV-infected citrus but not from uninfected citrus. Most of the p23 protein was found in the soluble, cytoplasmic fraction. Comparison of the sequence of p23 genes from several biologically and geographically diverse CTV isolates indicated a high degree of conservation for this gene and for the RNA binding motif in particular. A cluster dendrogram of the deduced amino acid sequences correlated with the biological properties of the isolates, forming distinct groups of mild, quick decline on stem pitting-inducing isolates. Therefore it is possible that, in addition to the capsid protein gene, the p23 gene also may serve as an indicator for disease severity.

Amino Acid Sequence↗
PubMed2001

Immunotoxicity of a standardized citrus polymethoxylated flavone extract.

Polymethoxylated flavones (PMFs) from citrus inhibit production of TNF-alpha and other pro-inflammatory cytokines. As TNF-alpha also modulates NK cell activity, the current studies were conducted to assess the potential for a standardized citrus PMF mixture to suppress humoral and innate immune functions. PMFs were isolated from orange peel oil using a procedure that obtained a consistent mixture of PMFs both in identity and proportion. The mixture consisted of nobiletin (30.7%), 3,3',4',5,6,7,8-heptamethoxyflavone (27.9%), trimethylscutellarein (14.5%), tangeretin (10.4%), sinensetin (5.8%), 5-demethyl-nobiletin (2.0%), hexa-O-methylquercetagetin (1.3%), 5-demethyl-tetramethylscutellarein (0.6%), and other flavonoids (2.7%). To assess the effect of the PMF mixture on humoral immune responses, female B(6)C(3)F(1) mice (n=8) were exposed to the PMF by gavage at 5, 50, 150 and 500 mg/kg/day for 28 days. On day 25, mice were sensitized to sRBC by tail vein injection and AFC response determined 4 days later. Humoral immunity was insensitive to suppression following exposure to all concentrations of the PMF mixture. Suppression of NK cell activity was observed only following 500 mg/kg/day for 28 days. Body weights were not affected by exposure to any concentration of the PMF mixture in sRBC immunized or non-immunized mice. However, in sRBC-immunized mice, higher concentrations of PMF were associated with a statistically insignificant increase in spleen weight (P>0.05). No change in spleen weight was observed in non-immunized mice. As anticipated, based on previously published in vitro observations, long-term, high-dose exposure to a standardized mixture of citrus PMFs caused a mild suppression of NK cell activity; however, humoral immunity was not sensitive to suppression at the same exposure levels.

Animals↗
PubMed2003

Simultaneous reversed-phase high-performance liquid chromatographic method for the determination of diosmin, hesperidin and naringin in different citrus fruit juices and pharmaceutical formulations.

Diosmin, hesperidin and naringin are flavonoid glycosides that occur naturally in citrus fruits. They exert a variety of pharmacological properties such as anti-inflammatory, antioxidant and free radical scavenging and antiulcer effects and also inhibit selected cytochrome P-450 enzymes resulting in drug interactions. A reversed-phase high-performance liquid chromatographic method has been developed for the simultaneous determination of diosmin, hesperidin and naringin in different citrus fruit juices and pharmaceutical preparations. Diosmin, hesperidin, naringin and the internal standard rhoifolin were separated using tetrahydrofuran/water/acetic acid (21:77:2, v/v/v) as the mobile phase at 34 degrees C, using a C8 reversed-phase column. The method was linear in the 0.25-20.0 microg/ml concentration range for all three flavonoid glycosides (r>0.999). The method has been successfully applied to the determination of all three flavonoid glycosides in several samples of different citrus fruit juices sold in Greece and for the determination of diosmin and hesperidin in pharmaceutical preparations.

Antioxidants↗
PubMed2003

Total tooth loss and prevalent cardiovascular disease in men and women: possible roles of citrus fruit consumption, vitamin C, and inflammatory and thrombotic variables.

BACKGROUND AND OBJECTIVE: Tooth loss has been associated with cardiovascular disease (CVD), but the mechanisms are unclear. We evaluated the association of total tooth loss with prevalent CVD in men and women; as well as with citrus fruit consumption, plasma vitamin C, and inflammatory and thrombotic variables. METHODS: We used an age-and sex-stratified population survey, of men and women aged 25-74 years, in North Glasgow. RESULTS: Thirty-eight percent of women and 29% of men were edentulous. Total tooth loss was associated with prevalent CVD in both sexes. After adjustment for major potential confounders (age, sex, smoking, and social class), the odds ratio (95% CI) for prevalent CVD was 1.55 (1.13, 2.13) in the edentulous. Total tooth loss was also associated with low citrus fruit consumption and low plasma vitamin C levels, increased plasma C-reactive protein in men, and with increased plasma interleukin-6, fibrinogen, and factor VIII levels in women. CONCLUSION: Prevalent CVD is associated with total tooth loss. Possible mechanisms include low intake of citrus fruit, and hence, low plasma vitamin C levels, and a predisposition to low-grade inflammation and thrombosis. It may be prudent to ensure adequate vitamin C intake in people with no teeth.

Adult↗
PubMed2000

Sensitivity to citrus red mite and the development of asthma.

BACKGROUND AND OBJECTIVE: The citrus red mite (Panonychus citri, CRM) is an important allergen in the development of asthma and/or rhinitis in citrus farmers and a common sensitizing allergen among exposed children. The aim of this study was to evaluate CRM-induced skin responses and serum-specific IgE, IgG4, and IgG1 responses, and their role in the development of asthmatic symptoms among exposed adolescents. METHODS: A total of 100 adolescents between the ages of 15 and 16 years (59 males and 41 females) were randomly recruited. All of the subjects responded to the ISAAC questionnaire themselves. Skin prick tests to CRM were carried out and serum-specific IgE, IgG4, and IgG1 levels were measured using ELISA. RESULTS: Fourteen subjects (14%) had experienced wheezing during last 12 months. The wheal size formed by CRM was larger than 3 mm in 23 subjects (23%). Serum-specific IgE levels were elevated in 21 subjects (21%), IgG4 levels were elevated in 32 subjects (32%), and IgG1 levels were elevated in five subjects (5%). The prevalence of wheezing during last 12 months was significantly higher in subjects with positive skin responses and serum-specific IgE responses induced by CRM than in those with negative skin responses and low serum IgE responses (30.4% versus 9.0%, P < .05; 33.3% versus 8.7%, P < .05). The prevalence of wheezing, however, did not differ according to serum-specific IgG4 levels (9.4% versus 16.2%, P > .05). Skin responses to CRM showed a significant correlation with serum-specific IgE levels, but not with IgG1 and IgG4 levels. Serum CRM-specific IgE levels correlated with specific IgG1 and IgG4 levels, but no significant correlation was found between serum IgG1 and IgG4 levels. CONCLUSION: The specific IgE responses induced by CRM were prevalent among adolescents living near citrus farms, and may be important in the development of asthma. The specific IgG4 and IgG responses induced by CRM play a minimal role in the development of asthma symptoms.

Adolescent↗
PubMed2000

Composition of the essential oil of Citrus tamurana Hort. ex Tanaka (Hyuganatsu).

The composition of the essential oil of Citrus tamurana Hort. ex Tanaka (Hyuganatsu), isolated by the cold-pressing method, was investigated by capillary GC and GC-MS. The effects of harvesting time, degree of freshness, and size of fruits on the composition of Hyuganatsu peel oils were also determined. A total of 126 volatile constituents were confirmed in the Hyuganatsu oils. The Hyuganatsu oils contained hydrocarbons (95.95-96.95%), aldehydes (0.33-0.62%), alcohols (1.91%-2.64%), ketones (0.40-0.62%), esters (0.28-0.39%), oxides (0.04-0.06%), acids (0.01%), and trace amounts of fugenol methyl ether. Monoterpene hydrocarbons were predominant. Limonene (80.35-82.39%), gamma-terpinene (7.71-9.03%), myrcene (2.11-2.28%), linalol (1.37-2.01%), and alpha-pinene (1.17-1.43%) were the most abundant components in Hyuganatsu oils. The principal sesquiterpene hydrocarbon was trans-beta-farnesene (0.60-1.04%), and its content in Hyuganatsu oils was higher than in oils of other citrus fruits. The number of ketones and the content of l-carvone in Hyuganatsu oils were higher than in other citrus oils.

Chromatography, Gas↗
PubMed2001

Citrus pectin: characterization and inhibitory effect on fibroblast growth factor-receptor interaction.

This study was undertaken to characterize the pectin from four citrus species and to determine their in vitro inhibitory activities on the binding of fibroblast growth factor (FGF) to the FGF receptor (FGFR). Pectin from various parts of lemon, grapefruit, tangerine, and orange were isolated and characterized. Tangerine had the highest pectin content among the four citrus species. Segment membrane contained as much as or more pectin than flavedo/albedo. Anhydrogalacturonic content was highest in pectin from segment membrane of tangerine and flavedo/albedo of grapefruit. Lemon pectin contained the highest methoxyl content (MC), and grapefruit contained the largest proportion of lower molecular weight (<10000 Da) pectin. Tangerine contained the highest neutral sugar in both flavedo/albedo and segment membrane. The interdependency of heparin on factor-receptor interaction provides a means for identifying new antagonists of growth factor activity and thus for treatment of various diseases. These results showed that pectin significantly inhibited the binding of FGF-1 to FGFR1 in the presence of 0.1 microg/mL heparin. The pectin from the segment membrane of lemon was the most potent inhibitor. The inhibition activity was significantly correlated with sugar content, MC, and size of pectin. Kinetic studies revealed a competitive nature of pectin inhibition with the heparin, a crucial component of the FGF signal transduction process. The observation that the heparin-dependent biological activity of FGF signal transduction is antagonized by citrus pectin should be further investigated for the use of these pectins as anti-growth factor agents for potential health benefits.

Citrus↗
PubMed2001

Extraction parameters and capillary electrophoresis analysis of limonin glucoside and phlorin in citrus byproducts.

Limonin glucoside (LG) and phlorin were extracted from citrus fruit tissues and assayed by capillary electrophoresis (CE). LG was determined in dried [1.20 +/- 0.10 mg of dry weight (dw)] and wet peel residues (1.16 +/- 0.04 mg of dw), orange juice finisher pulp (0.58 +/- 0.03 mg of dw), dried grapefruit seeds (2.70 +/- 0.15 mg of dw), and 50 degrees Brix molasses (2225 +/- 68 mg/L). Phlorin was purified from orange peel residue and grapefruit albedo, and concentrations were determined in some citrus products. Phlorin and LG were extracted from residues with water/pectinase or with water solutions of methanol and ethanol. Efficient LG extraction from grapefruit seeds (2.40 +/- 0.15 mg/g) was achieved with 50-65% methanol, solvent polarity P' approximately equal to 7-8. Extracts were purified and concentrated by adsorptive resins and HPLC to obtain 95% pure compounds of LG and phlorin. CE analysis did not require extract purification beyond filtration. LG and phlorin migrated as anions in electropherograms containing peaks representing other citrus flavonoids and limonoid glucosides.

Citrus↗
PubMed2002

A pectinmethylesterase gene associated with a heat-stable extract from citrus.

A putative thermostable pectinmethylesterase (TSPME) protein of 36 kDa was isolated from heat-treated citrus finisher pulp. After purification and partial sequencing of the protein, a reverse genetic approach was used to obtain the complete genomic sequence of a new pectinmethylesterase (PME) gene, CsPME4, from Citrus sinensis (L.) Osb. cv. Valencia. The CsPME4 gene contained two exons of 1203 and 690 bp interrupted by a single positionally conserved intron of 1230 bp. A full-length CsPME4 cDNA clone amplified from Valencia orange juice vesicles shared 98% identity with the genomic clone. The encoded protein of the full-length CsPME4 cDNA shared 66 and 39% amino acid identity with the full-length encoded proteins of the citrus PME, CsPME1, and CsPME3, respectively, whereas the predicted mature protein of CsPME4 shared 80 and 61% identity with the predicted mature proteins of CsPME1 and CsPME3, respectively. Southern analysis demonstrated that CsPME4 was present in at least two copies in the Valencia orange genome. Northern analysis revealed that CsPME4 mRNA was accumulated mainly in young and developing tissues of Valencia orange. Several approaches to express recombinant CsPME4 in different systems failed to obtain active protein. Further research will be necessary to successfully express the putative TSPME gene CsPME4 for biochemical characterization.

Amino Acid Sequence↗