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Tubers
Kinds of Tubers Terms modified by Tubers Selected AbstractsEvaluation of epileptogenic networks in children with tuberous sclerosis complex using EEG-fMRIEPILEPSIA, Issue 5 2008Julia Jacobs Summary Purpose: Ninety percent of patients with tuberous sclerosis complex (TSC) have epilepsy. Identification of epileptogenic areas can be difficult and studies are needed to characterize the epileptogenic network in more detail. Methods: Five children with TSC and focal epilepsy were studied using simultaneous EEG and functional MRI recordings. Tubers were marked by a neuroradiologist on the anatomical MRI. Spike-associated BOLD (blood oxygenation level-dependent) responses were superimposed with lesions. Results: Thirteen different types of interictal epileptiform discharges (IED) were analyzed with 12 showing a BOLD response, all involving more than one tuber. Five studies had tubers with activations exclusively within the lesion, three studies had lesional activations extending to perilesional areas, and two studies had activations involving exclusively perilesional areas of at least one tuber. Deactivations exclusively within a tuber were found in six studies, lesional deactivations extending to perilesional areas were found in four studies, and tubers with exclusively perilesional deactivations were found in five studies. A BOLD response was found in at least one tuber in the lobe of IED generation and presumed seizure onset (according to telemetry) in all patients. In four patients, the same tubers were involved following different IED localizations. The observed changes were always multifocal, sometimes involving tubers distant from the IED field. Discussion: These findings suggest extended epileptogenic networks in patients with TSC, which exceed networks described in PET and SPECT studies. It was possible to identify specific interictally active tubers. EEG-fMRI provides a noninvasive method to select tubers and areas at their borders for further presurgical investigations. [source] Novel Bibenzyl Derivatives from the Tubers of Bletilla striataHELVETICA CHIMICA ACTA, Issue 3 2008Jia-Quan Feng Abstract Three novel bibenzyl derivatives, blestritins A,C (1,3), along with 18 known constituents, were isolated from the tubers of Bletilla striata (Orchidaceae), a traditional Chinese medicine used for the treatment of tuberculosis and haemorrhage of the stomach and lungs. Their structures were identified on the basis of spectroscopic analyses. [source] Effects of Tuber Storage and Cultivar on the Quality of Vacuum Microwave-dried Potato ChipsJOURNAL OF FOOD SCIENCE, Issue 2 2003J.F. Lefort ABSTRACT: Influences of storage and cultivar on vacuum microwave-dried (VMD) potato chip quality were investigated. Tubers of several cultivars were stored at 12 °C for 0 to 4 mo, or at 4 °C for 5 to 10 mo, followed by reconditioning at 12 °C for 2 wk. Blanched potato slices (2.5 to 3.0 mm thick) were vacuum microwave-dried to produce fat-free potato chips. Chips were assessed by instrumental and sensory methods for texture and instrumentally for color. Tuber composition influenced chip texture but not color. Less breaking force was required for chips produced from cultivars with low specific gravity and starch contents. Tubers stored for up to 10 mo yielded chips of good quality. [source] Inhibited Long-Distance Movement of Potato Leafroll Virus to Tubers in Potato Genotypes Expressing Combined Resistance to Infection, Virus Multiplication and AccumulationJOURNAL OF PHYTOPATHOLOGY, Issue 9 2003J. Syller Abstract Plants of two potato clones which, in preliminary greenhouse assessments, showed resistance to multiplication and accumulation of potato leafroll virus (PLRV) were graft or aphid inoculated with the virus and grown in the greenhouse; plants of a moderately susceptible cultivar were used for comparison in all experiments. A high concentration of aphid-borne inoculum was used to ensure strong infection pressure. Clone M62759 appeared to be highly resistant to PLRV infection, whereas clone PS1706 was more susceptible. Both clones expressed a high level of resistance to virus multiplication, when primary or secondary infection was assayed by enzyme-linked immunosorbent assay. Moreover, PLRV was detected in only few or none of the progeny plants of clone M62759, which thus strongly inhibited virus transport to tubers. The study on PLRV translocation from aphid-inoculated shoots to uninoculated shoots sprouted from the same tubers showed that no specific mechanisms are likely to impair PLRV movement through the tubers of the resistant genotypes. These results indicate that three valuable components of the resistance to PLRV are probably closely linked in the genotype, a combination that seems to occur rather rarely in potato clones. Nevertheless, selecting potato genotypes for the complex resistance to PLRV may prove to be a worthwhile part of breeding programmes, provided that the genetic mechanisms governing particular types of resistance are better recognized. [source] Detection of Ralstonia solanacearum in Potato Tubers by Polymerase Chain ReactionJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2000K.-H. Pastrik Abstract A new polymerase chain reaction (PCR) assay was developed for the detection of Ralstonia solanacearum in potato tubers. The designed primers PS-1/PS-2 based on the sequence data of the 16S rRNA gene. Using the optimized PCR protocol, it was possible to detect R. solanacearum cells artificially added to concentrated potato extracts in the range of 1,10 colony-forming units (CFU) per PCR reaction mixture (10,100 CFU/ml potato homogenate). No amplification products were obtained, when bacteria belonging to other species or genera were submitted to PCR under the same conditions. A total of 10 different DNA extraction methods were adapted for the isolation of R. solanacearum DNA from potato homogenates and were compared for their suitability as pre-PCR procedures. Zusammenfassung Es wurde ein neuer PCR-Test entwickelt für die Detektion von Ralstonia solanacearum in Kartoffel-Knollen. Die entwickelten Primer PS-1/PS-2 basierten auf Sequenzdaten des 16S rRNA Gens. Mit dem optimierten PCR Protokoll war es möglich künstlich zugegebene R. solanacearum Zellen in konzentrierten Kartoffel-Homogenaten zu detektieren, bei einer Nachweis-Empfindlichkeit von 1,10 CFU pro PCR-Mix (10,100 CFU pro ml Kartoffel-Homogenat). Mit dem optimierten PCR Protokoll wurden keine Amplifikationsprodukte bei Bakterien anderer Arten oder Gattungen erhalten. Außerdem wurden 10 unterschiedliche DNA-Extraktionsmethoden getestet zur Isolierung von Ralstonia solanacearum DNA aus Kartoffel-Homogenat und ihre Eignung für die PCR verglichen. [source] Impact of hot water treatment on sprouting, membrane permeability, sugar content and chip colour of reconditioned potato tubers following long-term cold storageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2008Marios C Kyriacou Abstract BACKGROUND: The efficacy of hot water treatment in facilitating successful reconditioning of processing potato (Solanum tuberosum L.) cultivar Hermes following 6 months cold storage at 4.5 °C was examined. Tubers were subjected to hot water treatments (HWTs) at 52.5, 55.0, 57.5 and 60.0 °C for 0,60, 0,50, 0,40 and 0,20 min, respectively, and then reconditioned for 20 days at 16 °C before evaluated for sprouting, fresh weight loss, membrane permeability, sugar content and processing quality. RESULTS: The study demonstrates that in order to achieve complete inhibition of sprouting during potato reconditioning HWTs must exceed the thermal tolerance threshold of the tubers. Short-duration HWT was effective in retarding sprout growth and tuber dehydration without significantly affecting storage parenchyma membrane permeability, tuber sugar content or processing quality. On the contrary, prolonged HWT caused extensive heat damage, loss of membrane integrity and induced an increase in tuber sucrose and reducing sugar content resulting in deterioration of chip colour in proportion to treatment duration. CONCLUSION: Although HWT at 52.5,60 °C following long-term cold storage did not improve the processing quality of potato tubers after 20 days of reconditioning, future work is needed to evaluate the effect of short-duration HWT on the permissible extent of reconditioning and subsequent processing quality. Copyright © 2008 Society of Chemical Industry [source] Tubers as fallback foods and their impact on Hadza hunter-gatherersAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Frank W. Marlowe Abstract The Hadza are hunter-gatherers in Tanzania. Their diet can be conveniently categorized into five main categories: tubers, berries, meat, baobab, and honey. We showed the Hadza photos of these foods and asked them to rank them in order of preference. Honey was ranked the highest. Tubers, as expected from their low caloric value, were ranked lowest. Given that tubers are least preferred, we used kilograms of tubers arriving in camp across the year as a minimum estimate of their availability. Tubers fit the definition of fallback foods because they are the most continuously available but least preferred foods. Tubers are more often taken when berries are least available. We examined the impact of all foods by assessing variation in adult body mass index (BMI) and percent body fat (%BF) in relation to amount of foods arriving in camp. We found, controlling for region and season, women of reproductive age had a higher %BF in camps where more meat was acquired and a lower %BF where more tubers were taken. We discuss the implications of these results for the Hadza. We also discuss the importance of tubers in human evolution. Am J Phys Anthropol, 140:751,758, 2009. © 2009 Wiley-Liss, Inc. [source] Tuberous Sclerosis: from Tubers to mTORANNALS OF HUMAN GENETICS, Issue 1 2003D. J. Kwiatkowski Summary Tuberous sclerosis (TSC) is an autosomal dominant hamartoma syndrome whose causative genes (TSC1 and TSC2) were identified 5 and 9 years ago respectively. Their encoded proteins are large, and apart from a strong binding interaction with each other, relatively little was known about their biochemical function. Recent studies in Drosophila have pinpointed a critical function for the DrosophilaTSC1/TSC2 homologues in the regulation of cell size. Epistasis experiments and a variety of biochemical studies that followed have indicated a critical function for these proteins in the highly conserved PI-3-kinase-Akt-mTOR signalling pathway. [source] Evaluation of epileptogenic networks in children with tuberous sclerosis complex using EEG-fMRIEPILEPSIA, Issue 5 2008Julia Jacobs Summary Purpose: Ninety percent of patients with tuberous sclerosis complex (TSC) have epilepsy. Identification of epileptogenic areas can be difficult and studies are needed to characterize the epileptogenic network in more detail. Methods: Five children with TSC and focal epilepsy were studied using simultaneous EEG and functional MRI recordings. Tubers were marked by a neuroradiologist on the anatomical MRI. Spike-associated BOLD (blood oxygenation level-dependent) responses were superimposed with lesions. Results: Thirteen different types of interictal epileptiform discharges (IED) were analyzed with 12 showing a BOLD response, all involving more than one tuber. Five studies had tubers with activations exclusively within the lesion, three studies had lesional activations extending to perilesional areas, and two studies had activations involving exclusively perilesional areas of at least one tuber. Deactivations exclusively within a tuber were found in six studies, lesional deactivations extending to perilesional areas were found in four studies, and tubers with exclusively perilesional deactivations were found in five studies. A BOLD response was found in at least one tuber in the lobe of IED generation and presumed seizure onset (according to telemetry) in all patients. In four patients, the same tubers were involved following different IED localizations. The observed changes were always multifocal, sometimes involving tubers distant from the IED field. Discussion: These findings suggest extended epileptogenic networks in patients with TSC, which exceed networks described in PET and SPECT studies. It was possible to identify specific interictally active tubers. EEG-fMRI provides a noninvasive method to select tubers and areas at their borders for further presurgical investigations. [source] Bet,v,1, the major birch pollen allergen, initiates sensitization to Api,g,1, the major allergen in celery: evidence at the T,cell levelEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2003Barbara Bohle Abstract Due to IgE cross-reactivity, birch pollen-allergic individuals frequently develop type,I hypersensitivity reactions to celery tuber. We evaluated the T,cell response to the major allergen in celeriac, Api,g,1, and the cellular cross-reactivity with its homologous major allergen in birch pollen, Bet,v,1. Api,g,1-specific T,cell lines (TCL) and clones (TCC) were established from peripheralblood mononuclear cells of allergic patients. Epitope mapping of Api,g,1 with overlapping Api,g,1-derived peptides revealed one dominant T,cell-activating region, Api,g,1109,126. TCL and TCC generated with Api,g,1 cross-reacted with the birch pollen allergen and, although initially stimulated with the food allergen, cellular responses to Bet,v,1 were stronger than to Api,g,1. Epitopemapping with Bet,v,1-derived peptides revealed that T,cells specific for several distinct epitopes distributed over the complete Bet,v,1 molecule could be activated by Api,g,1. Bet,v,1109,126 was identified as the most important T,cell epitope for cross-reactivity with Api,g,1. This epitope shares 72% amino acid sequence similarity with the major T,cell-activating region of the food allergen, Api,g,1109,126. Our data provide evidence that humoral as well as cellular reactivity to the major celery allergen is predominantly based on cross-reactivity with the major birch pollen allergen. The activation of Bet,v,1-specific Th2 cells by Api,g,1, in particular outside the pollen season, may have consequences for birch pollen-allergic individuals. [source] Antioxidative activity of water extracts from the yam (Dioscorea opposita Thunb.) tuber mucilage tororoEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 6 2006Takeshi Nagai Abstract A water extract as a viscous solution was obtained from the yam Dioscorea opposita tuber mucilage tororo, and its functional properties were demonstrated. The protein content was about 280,,g/mL extract, and the main protein bands with an MW of ,33,kDa without 2-mercaptoethanol (2-ME) and ,31,kDa with 2-ME were detected by SDS-PAGE. The water extract possessed high antioxidative activity and scavenging activities against superoxide anion and hydroxyl radicals. However, it showed no inhibitory activity against angiotensin,I-converting enzyme. The yam tuber contains relatively high contents of vitamins, different micro- and macroelements, enzymes, and dietary fibers. The yam D.,opposita tuber will be increasingly regarded as a health-promoting food. [source] Phage-selected lipopolysaccharide mutants of Pectobacterium atrosepticum exhibit different impacts on virulenceJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2010T.J. Evans Abstract Aims:, To positively select Pectobacterium atrosepticum (Pa) mutants with cell surface defects and to assess the impact of these mutations on phytopathogenesis. Methods and Results:, Several phages were isolated from treated sewage effluent and were found to require bacterial lipopolysaccharide (LPS) for infection. Two strains with distinct mutations in LPS were obtained by transposon mutagenesis. Along with a third LPS mutant, these strains were characterized with respect to various virulence-associated phenotypes, including growth rate, motility and exoenzyme production, demonstrating that LPS mutations are pleiotropic. Two of the strains were deficient in the synthesis of the O-antigen portion of LPS, and both were less virulent than the wild type. A waaJ mutant, which has severe defects in LPS biosynthesis, was dramatically impaired in potato tuber rot assays. The infectivity of these novel phages on 32 additional strains of Pa was tested, showing that most Pa isolates were sensitive to the LPS-dependent phages. Conclusions:, Native LPS is crucial for optimal growth, survival and virulence of Pa in vivo, but simultaneously renders such strains susceptible to phage infection. Significance and Impact of the Study:, This work demonstrates the power of phages to select and identify the virulence determinants on the bacterial surface, and as potential biocontrol agents for Pa infections. [source] VISCOUS PROPERTIES OF TARO FLOUR EXTRUDED WITH WHEY PROTEINS TO SIMULATE WEANING FOODS,JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2002C. I. ONWULATA Taro flour, derived from the corm of Colocasia Esculenta cv. Lehua, a root tuber grown in the tropical regions of the world, was extruded with whey protein concentrate (WPC), whey protein isolate (WPI) or lactalbumin (LAC), to derive blends containing 20% protein, simulating the protein content of some weaning foods. Taro flour is unique because of its extremely small particle size (1,5 micron) and high mucilage or gum content, making it a possible replacement for corn or wheat starch in weaning foods. Extrusion processing temperatures were from 100 to 130C and moisture of the feed blends was held constant at 18%. The extrudates were pulverized, made into powders, and rehydrated to make a paste. Viscosities of the feed blends before extrusion and the pastes made from the extrudates were determined using a Rapid Visco Analyzer (RVA) to determine peak, final, and breakdown viscosities. Water solubility and absorption indices were also determined. Extrudates made from taro containing whey products expanded more than taro alone; were easier to grind into powders; and rehydrated readily in water to form pastes. Before extrusion, the peak viscosities of the blends were 5000, 2600, 1600, 1600 cP for taro flour, taro with WPI, taro with WPC, or taro with LAC, respectively. After extrusion cooking, the viscosities for taro flour, taro with WPI, taro with WPC, or taro with LAC were 110, 65, 70 or 90 cP, respectively. Taro extrudates without protein absorbed the most water, and were more soluble than products containing whey proteins or LAC. The addition of whey proteins reduced peak viscosities, but WPI and taro pastes were characteristic of weaning foods. Both extrusion cooking and the [source] Acid Phosphatase Activity May Affect the Tuber Swelling by Partially Regulating Sucrose-mediated Sugar Resorption in PotatoJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 6 2008Da-Yong Wang Abstract APase activity is involved in regulating many physiological and developmental events by affecting the resorption process. In this study, we investigate the role of APase activity in tuber development in potato. APase activities were mainly localized in cytoplasm, gaps among cells and stroma of amyloplasts of parenchyma cells at the stage of tuber swelling. AP1, encoding a putative APase, was also highly expressed in swelling tubers and a low level of expression was observed in elongated stolons and matured tubers. Inhibition of APase activity by applying Brefeldin A, an inhibitor of APase production and secretion, significantly suppressed the tuber swelling and moderately affected the stolon elongation and the tuberization frequency. During tuber development, sucrose serves as the main soluble sugar for long-distance transportation and resorption. Moreover, inhibition of APase activity by Brefeldin A markedly reduced the sucrose content in tubers and further decreased the starch accumulation, suggesting that the function of APase in regulating the tuber swelling might be at least partially mediated by the sugar resorption. Exogenous sucrose treatments further indicate the important role of sucrose-mediated sugar resorption in tuber swelling. These results suggest that the APase activity might affect the tuber swelling by partially regulating the sucrose-mediated sugar resorption. [source] Clinical quality of removable dentures provided by dentists, denturists and laboratory techniciansJOURNAL OF ORAL REHABILITATION, Issue 4 2003R. Tuominen summary, The aim of this study was to evaluate the clinical quality of removable dentures of elderly Finnish men, which had been prepared either by dentists, denturists or dental laboratory technicians. The participants comprised 242 denture-wearing subjects, with 231 maxillary and 177 mandibular removable dentures which had been prepared either by dentists, denturists or dental laboratory technicians. Clinical examinations were carried out without the examining dentist knowing who had provided the dentures. Complete dentures which had been illegally provided by laboratory technicians had significantly poorer retention and fitted less well in tuber and alveolar areas than those provided by either dentists or denturists. Complete maxillary dentures which had been provided illegally by laboratory technicians had significantly (P < 0·01) higher occurrence (90%) of some unacceptable characteristics than those (43%) provided by dentists or denturists. The difference between complete mandibular dentures was also obvious, 86% versus 59%, although statistically non-significant. Of those partial maxillary dentures provided by dentists 53% had some unacceptable characteristics, compared with 80% of those illegally provided by denturists or laboratory technicians (NS). In the case of partial mandibular dentures, 36% of those provided by dentists and 32% of those by denturists or laboratory technicians had some unacceptable characteristic (NS). Illegal provision of removable dentures seemed to be related to decreased clinical quality. [source] Acetylcholinesterase inhibitors from Stephania venosa tuberJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2006Kornkanok Ingkaninan Acetylcholinesterase (AChE) inhibitors have lately gained interest as potential drugs in the treatment of Alzheimer's disease. Three AChE inhibitors were isolated from tubers of a Thai medicinal plant, Stephania venosa (Bl) Spreng. They were identified as quaternary protoberberine alkaloids, stepharanine, cyclanoline and N -methyl stepholidine. They expressed inhibitory activity on AChE with IC50 values (concentration that caused 50% inhibition of activity) of 14.1K ± 0.81, 9.23 ± 3.47 and 31.30 ± 3.67 ,M, respectively. The AChE inhibitory activity of these compounds was compared with those of the related compounds, palmatine, jatrorrhizine and berberine, as well as tertiary protoberberine alkaloids isolated from the same plant, stepholidine and corydalmine. The results suggest that the positive charge at the nitrogen of the tetrahydroisoquinoline portion, steric substitution at the nitrogen, planarity of the molecule or substitutions at C-2, ,3, ,9, and ,10 affect the AChE inhibitory activity of protoberberine alkaloids. [source] The in-vivo effects of sho-saiko-to, a traditional Chinese herbal medicine, on two cytochrome P450 enzymes (1A2 and 3A) and xanthine oxidase in manJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2003Junji Saruwatari ABSTRACT The Chinese herbal medicine sho-saiko-to is a mixture of seven herbal components (Bupleurum root, Pinellia tuber, Scutellaria root, Jujube fruit, Ginseng root, Glycyrrhiza root and Ginger rhizome) that is widely administered to patients with chronic hepatitis in Japan. We assessed the effects of sho-saiko-to on the activity of cytochrome P450 (CYP) 1A2, CYP3A and xanthine oxidase (XO) in man. Twenty-six healthy subjects were studied to evaluate their baseline activity of CYP1A2 and XO by the respective urinary metabolic ratios of an 8-h urine sample after an oral 150-mg dose of caffeine and of CYP3A by a urinary excretion ratio of 6,-hydroxycortisol (6,-HC) to free cortisol (FC). Thereafter, the subjects received a twice-daily 2.5-g dose of sho-saiko-to for five days, and underwent the caffeine test on day 1 and day 5. The mean activity of CYP1A2 decreased by 16% on both day 1 and day 5 compared with the baseline (P = 0.001). The mean activity of XO also significantly decreased by 25% on day 1 and 20% on day 5 (P < 0.0001) compared with the baseline value. The activity of CYP3A tended to be lower on day 5 than the baseline (P = 0.146). It is concluded that sho-saiko-to reduces CYP1A2 and XO activity in man. [source] INFLUENCE OF CELL SIZE AND CELL WALL VOLUME FRACTION ON FAILURE PROPERTIES OF POTATO AND CARROT TISSUEJOURNAL OF TEXTURE STUDIES, Issue 1 2005ARTUR ZDUNEK ABSTRACT This article presents the influence of cell size and cell wall volume fraction on the failure parameters of potato tuber and carrot tissue. Confocal scanning laser microscope was used for obtaining images of the cell structure of the tissues. The mean cell face area and the cell wall volume fraction obtained from the images was compared with work to failure, failure stress, failure strain and secant modulus obtained in a compression test of potato and carrot tissue at two strain rates. Bigger cells and less amount of cell wall material weakened the tissue, which was visible as a linear decrease in the parameters: work to failure, failure stress and failure strain. There were differences between potato and carrot in the secant modulus. For carrot, the secant modulus changed with microstructural parameters, whereas for potato, the secant modulus did not depend on these values. The strain rate decreases all the failure properties for potato. For carrot, only the work to failure was affected by the strain rate. [source] Glucosinolates in isaño (Tropaeolum tuberosum) tubers: qualitative and quantitative content and changes after maturityJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2004Rodrigo Ramallo Abstract Six varieties of isaño (Tropaeolum tuberosum), an Andean edible tuber, were analysed. The aim was to characterise qualitatively and quantitatively their content of glucosinolates and to determine concentration changes of these compounds upon delayed harvest. Additionally, exploratory assays were carried out on the effect of postharvest cold storage of the tubers as well as of a drying process imposed on blanched tuber slices. Only one glucosinolate (p -methoxybenzyl glucosinolate) was found in the six domestic varieties analysed. Its concentration varied between 36.5 and 90.0 µmol g,1 dry matter. This range is relatively high when compared with other edible glucosinolate-containing vegetables. ,Dark' coloured tuber varieties showed higher levels than ,light' coloured tuber varieties at normal harvest time. Of the two varieties on which the effect of delayed harvest was studied, one showed increasing and then decreasing changes until 44 days after maturity, while the other did not show any significant change with time. Postharvest cold stored samples showed similar changes to tubers kept in soil, and glucosinolate levels in dried blanched tubers did not differ significantly from those in fresh samples. Taken together, the data indicate that the glucosinolate content of isaño is highly dependent on both the variety and the time of harvest. These parameters should be taken into account when considering isaño as a promising food source with medicinal properties for humans and animals, but also with possible adverse biological effects, all related to the presence of glucosinolates. Copyright © 2004 Society of Chemical Industry [source] Effect of section of yam (Dioscorea cayenensis) tuber used in minisett on the biochemical properties of the resultant tuberJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2002Andrew O Wheatley Abstract The effect of the section of yam (Dioscorea cayenensis) tuber used as planting material in minisett on the biochemical properties of the resultant tuber was studied. The biochemical parameters invertase (EC 3.2.1.26), acid phosphatase (EC 3.1.3.2), peroxidase (EC1.11.1.7), polyphenol oxidase (EC 1.10.3.1), total sugars and starch were evaluated in tubers resulting from field-grown and tissue culture-derived setts of the cultivars Roundleaf and Blackwiss yellow yams. No significant differences were observed between tubers resulting from field-grown and tissue culture-derived setts relative to the parameters studied. Invertase activity was found to be highest in tubers from middle-derived setts, while tail-derived setts had the lowest activity for both cultivars. Middle-derived tubers were also found to have significantly higher levels of acid phosphatase activity and starch content. However, middle-derived tubers had the lowest level of total sugars. Polyphenol oxidase and peroxidase were also found to be significantly higher in tubers from middle-derived setts. These results suggest a higher rate of active starch formation in tubers from middle-derived setts. © 2002 Society of Chemical Industry [source] Flowering Frequency and Plant Performance and their Relation to Age in the Perennial Orchid Spiranthes spiralis (L.) Chevall.PLANT BIOLOGY, Issue 3 2000J. H. Willems Abstract: Long-term demographic data have been analyzed to establish possible costs of flowering in the terrestrial orchid Spiranthes spiralis (L.) Chevall. in The Netherlands. Costs of flowering can be expressed as individual plant performance and flowering frequency in relation to the generative or vegetative status in the following year. Flowering in individuals of S. spiralis in a given year (t) is followed by a non-flowering phase in the next growing season (t + 1) in more than 80 % of the plants. The decline in flowering frequency is not a result of the age structure of the population involved because individual plants do not show signs of senescence after 10 - 15 years of aerial presence as an autotrophic plant. Rosettes have a smaller leaf area in the year of flowering (t), compared to the previous (t - 1) and following year (t + 1), due to the allocation of the limited underground resources to both flowering stalk and rosette at the beginning of its growing season. Generative reproduction in S. spiralis has a significant negative impact on both flowering frequency in subsequent years and on rosette size in the year of flowering. The flowering frequency and rosette size in relation to the life history, characterized by the yearly replacement of the underground tuber, is discussed. Better understanding of the life-history strategy, including costs of reproduction, may contribute to the creation of sustainable environmental conditions for growth of S. spiralis, e.g., optimal conditions for photosynthesis during the aboveground stage of the tiny wintergreen rosettes. [source] Strategy differences of two potato species in response to nitrogen starvation.PLANT CELL & ENVIRONMENT, Issue 7 2000Do plants have a genetic switch for nitrogen signalling? ABSTRACT Survival responses to nitrogen starvation are well known in micro-organisms but little studied in plants. To construct a framework for study of the plant responses, we investigated the strategy differences of tubers from two closely related potato species. Solanum tuberosum conserves tuber nitrogen by inhibiting shoot growth, but S. phureja mobilizes tuber nitrogen to grow shoots, flowers and seeds. Genetic analysis of progeny from S. phureja,haploid S. tuberosum crosses uncovered segregation of a single dominant gene for the S. tuberosum inhibition strategy. Within S. tuberosum, haploid progeny closely resembled their tetraploid parents, suggesting strong genetic control of the inhibition. Growth of the inhibited shoots was proportional to sub-optimal levels of added nitrate, and was triggered by exogenous gibberellic acid (GA3). These observations support the notion that potato plants can closely tie shoot growth to ambient nitrogen levels , probably by a root,shoot nitrogen signal transduction pathway, and that this can be overridden by emergency mobilization of nitrogen reserves, perhaps by GA signalling from the tuber. Furthermore, genes for such developmental switches can be identified by classical genetic analysis of closely related species, such as S. tuberosum and S. phureja, that exhibit opposite survival strategies. [source] Potato diseases caused by soft rot erwinias: an overview of pathogenesisPLANT PATHOLOGY, Issue 1 2002M. C. M. Pérombelon Three soft rot erwinias, Erwinia carotovora ssp. carotovora, E. carotovora ssp. atroseptica and E. chrysanthemi are associated with potatoes causing tuber soft rot and blackleg (stem rot). Latent infection of tubers and stems is widespread. As opportunistic pathogens, the bacteria tend to cause disease when potato resistance is impaired. Pathogenesis or disease development in potato tubers and stems is discussed in terms of the interaction between pathogen, host and environment, microbial competition and recent findings on the molecular basis of pathogenicity. Emphasis is placed on the role of free water and anaerobiosis in weakening tuber resistance and in providing nutrient for erwinias to multiply. Blackleg symptoms are expressed when erwinias predominate in rotting mother tubers, invade the stems and multiply in xylem vessels under favourable weather conditions. Soft rot erwinias tend to out-compete other bacteria in tuber rots because of their ability to produce larger quantities of a wider range of cell wall-degrading enzymes. However, despite extensive studies on their induction, regulation and secretion, little is known about the precise role of the different enzymes in pathogenesis. The putative role of quorum-sensing regulation of these enzymes in disease development is evaluated. The role certain pathogenicity-related characters, including motility, adhesion, siderophores, detoxifying systems and the hrp gene complex, common to most bacteria including symbionts and saprophytes, could play in latent and active infections is also discussed. [source] Differential interaction of Phytophthora infestans on tubers of potato cultivars with different levels of blight resistancePLANT PATHOLOGY, Issue 3 2001W. G. Flier Differential interactions in tuber blight attack between potato cultivars and Phytophthora infestans isolates were studied using whole tuber and tuber slice assays. Tuber blight incidence and severity were studied in a whole tuber assay, whilst necrosis and mycelium coverage were evaluated in a tuber slice assay. The overall defence reaction of the potato cultivars tested varied considerably. Cultivars like Kartel and Producent showed resistant reactions, whilst Bintje and, to a lesser extent, Astarte reacted more susceptibly after inoculation with aggressive strains of P. infestans. A highly significant cultivar by year interaction was observed when tuber blight incidence was evaluated in two successive years. Differential responses were revealed by changing ranked order of cultivars after exposure to aggressive isolates of P. infestans. The results show that cultivar by isolate interactions existed for all components of tuber blight resistance studied. The quantitative nature of the observed resistance responses suggests the presence of quantitative trait loci governing resistance to tuber blight. The consequences of differential interactions in relation to the stability of tuber resistance are discussed. [source] Detection, distribution and control of Potato mop-top virus, a soil-borne virus, in northern EuropeANNALS OF APPLIED BIOLOGY, Issue 2 2010J. Santala Potato mop-top virus (PMTV; genus Pomovirus; family Virgaviridae) is transmitted by the soil-borne Spongospora subterranea f.sp. subterranea, a protoctist that causes powdery scab on potato. PMTV is distributed widely in the potato growing areas in South and North America, Japan and northwestern Europe. This article reviews the current knowledge on detection, distribution and control of PMTV with focus on the Baltic Sea region. Since the 1980s, PMTV has caused great economic losses to potato production in the Nordic countries (Norway, Sweden, Denmark and Finland), but its occurrence in other countries of the Baltic Sea region remained unknown. To fill this knowledge gap, harmonised sampling and virus detection procedures including bioassays and serological and molecular methods were employed by 21 research institutions to detect PMTV in potato tubers and soil samples in 2005,2008. Potato growing areas were widely contaminated with PMTV in the Nordic countries. Only the main seed potato production area in northern Sweden and the High Grade seed potato production zone in Finland were negative for PMTV. Intensive and systematic surveys in Poland in 2004,2008 found no evidence of PMTV, except a single PMTV-infected tuber detected in 2008. Surveys in the Baltic countries (Lithuania, Latvia and Estonia) and northwestern Russia (Leningrad province) were negative for PMTV, except infection of minitubers in a screenhouse in Latvia in 2005. Varying percentages of tubers expressing spraing symptoms in Sweden, Norway, Denmark and Poland were infected with Tobacco rattle virus, and bioassays indicated similar results for Russia. Incidence of symptomless infections with PMTV was high in tubers of many potato cultivars. Here, we discuss the contrasting patterns of distribution of PMTV in the Baltic Sea region, factors playing a role in dispersal and establishment of PMTV in new fields and means for controlling PMTV and its spread to new areas. We emphasise the use of the current virus-specific methods for the detection of PMTV in symptomless potato tubers and the high risks of disseminating PMTV to new fields and areas in viruliferous resting spores of S. subterranea in the soil adhering to seed tubers. PMTV-resistant potato cultivars will provide the only sustainable means for preventing yield losses in the infested fields and the prospects of resistance breeding are summarised. [source] Placement of Brånemark implants in the maxillary tuber region: anatomical considerations, surgical technique and long-term resultsCLINICAL ORAL IMPLANTS RESEARCH, Issue 1 2009Arne Ridell Abstract Background: Fixture placement in the tuber area is one way to overcome the problem of insufficient bone volume for routine implant surgery in the posterior maxilla due to severe resorption of jawbone and an extensive enlargement of the maxillary sinus. However, little is known about the long-term results. Purpose: The aim of this study was to retrospectively evaluate the survival rate and marginal bone conditions at fixtures placed in the tuber region of the maxilla. Material and methods: Twenty-one patients previously treated with at least one implant in the tuber region of the maxilla were included in this retrospective analysis. A total of 23 standard Brånemark System fixtures with a turned surface had been surgically placed in the tuber regions and 71 additional implants in adjacent areas to support fixed dental bridges. All implants were allowed to heal for 6,8 months before abutment connection and following prosthetic treatment. The patients were radiographed after 1,12 years for evaluation of marginal bone levels. In addition, the relation between the apex of the fixture in the tuberosity area and the posterior border of the maxilla was measured. Results: Twenty of the 21 patients representing 22 tuber and 64 additional implants were radiographically evaluated. No implants in the tuber areas were lost during the follow-up whereas two fixtures in the anterior region had to be removed, one before loading and the other after 4 years of loading not interfering with the prosthesis stability. The mean marginal bone level at tuber implants was situated on average 1.6 mm (SD 1.1, n=22) from the abutment-fixture junction, whilst the other implants showed an average bone level of 1.9 mm (SD 0.8, n=64). The results were similar when comparing partially and totally edentulous patients. Conclusion: The present retrospective study shows good clinical outcome with standard Brånemark fixtures placed in the tuber region of the posterior maxilla using a two-stage procedure. In appropriate cases where bone of adequate volume and density is available, our data indicate that the technique can be used as an alternative to more extensive surgery and especially to the sinus lift procedure. However, prospective comparative studies are needed in order to evaluate the efficacy of the described technique for this purpose. [source] Abnormal giant cells in the cerebral lesions of tuberous sclerosis complexCONGENITAL ANOMALIES, Issue 1 2007Masashi Mizuguchi ABSTRACT Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations of either of the two tumor suppressor genes, TSC1 and TSC2, encoding hamartin and tuberin, respectively. TSC is pathologically characterized by the occurrence of multiple hamartias (focal dysplasias) and hamartomas (benign tumors) in the brain and many other organs. Cortical tubers are hamartias in the cerebral cortex responsible for many neuropsychiatric symptoms of TSC. Unlike TSC-associated hamartomas, cortical tubers do not result from second somatic mutations of the TSC gene, and the mechanism by which they occur remains obscure. Histologically, the most conspicuous feature of cortical tubers is the presence of abnormal giant cells, which show abnormal size and differentiation. Recent studies on human TSC and its animal models have elucidated the critical roles of hamartin and tuberin regulating the growth and differentiation of neural cells. [source] The Composition of Jerusalem Artichoke (Helianthus tuberosus L.) Spirits Obtained from Fermentation with Bacteria and YeastsENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2005K. Szambelan Abstract The composition of spirits distilled from fermentation of Jerusalem artichoke (Helianthus tuberosus L.) tubers was compared by means of gas chromatography. The microorganisms used in the fermentation processes were the bacterium Zymomonas mobilis, strains,3881 and 3883, the distillery yeast Saccharomyces cerevisiae, strains,Bc16a and D2 and the Kluyveromyces fragilis yeast with an active inulinase. The fermentation of mashed tubers was conducted using a single culture of the distillery yeast Saccharomyces cerevisiae and the bacterium Zymomonas mobilis (after acid or enzymatic hydrolysis) as well as Kluyveromyces fragilis (sterilized mashed tubers). The tubers were simultaneously fermented by mixed cultures of the bacterium or the distillery yeast with K.,fragilis. The highest ethanol yield was achieved when Z.,mobilis,3881 with a yeast demonstrating inulinase activity was applied. The yield reached 94,% of the theoretical value. It was found that the distillates resulting from the fermentation of mixed cultures were characterized by a relatively lower amount of by-products compared to the distillates resulting from the single species process. Ester production of 0.30,2.93,g/L, responsible for the aromatic quality of the spirits, was noticed when K.,fragilis was applied for ethanol fermentation both in a single culture process and also in the mixed fermentation with the bacterium. Yeast applied in this study caused the formation of higher alcohols to concentrations of 7.04,g/L much greater than those obtained with the bacterium. The concentrations of compounds other than ethanol obtained from Jerusalem artichoke mashed tubers, which were fermented by Z.,mobilis, were lower than those achieved for yeasts. [source] Evaluation of epileptogenic networks in children with tuberous sclerosis complex using EEG-fMRIEPILEPSIA, Issue 5 2008Julia Jacobs Summary Purpose: Ninety percent of patients with tuberous sclerosis complex (TSC) have epilepsy. Identification of epileptogenic areas can be difficult and studies are needed to characterize the epileptogenic network in more detail. Methods: Five children with TSC and focal epilepsy were studied using simultaneous EEG and functional MRI recordings. Tubers were marked by a neuroradiologist on the anatomical MRI. Spike-associated BOLD (blood oxygenation level-dependent) responses were superimposed with lesions. Results: Thirteen different types of interictal epileptiform discharges (IED) were analyzed with 12 showing a BOLD response, all involving more than one tuber. Five studies had tubers with activations exclusively within the lesion, three studies had lesional activations extending to perilesional areas, and two studies had activations involving exclusively perilesional areas of at least one tuber. Deactivations exclusively within a tuber were found in six studies, lesional deactivations extending to perilesional areas were found in four studies, and tubers with exclusively perilesional deactivations were found in five studies. A BOLD response was found in at least one tuber in the lobe of IED generation and presumed seizure onset (according to telemetry) in all patients. In four patients, the same tubers were involved following different IED localizations. The observed changes were always multifocal, sometimes involving tubers distant from the IED field. Discussion: These findings suggest extended epileptogenic networks in patients with TSC, which exceed networks described in PET and SPECT studies. It was possible to identify specific interictally active tubers. EEG-fMRI provides a noninvasive method to select tubers and areas at their borders for further presurgical investigations. [source] Assessment of the resistance of potato cultivars to Synchytrium endobioticum (Schilb.) Per. in PolandEPPO BULLETIN, Issue 2 2008J. Przetakiewicz In Poland the Plant Breeding and Acclimatization Institute is responsible for officially assessing the resistance to Synchytrium endobioticum of domestic potato breeding lines and cultivars from other countries. Cultivation of potato cultivars in Poland requires confirmation of resistance to potato wart disease. The official assessment uses the modified Glynne-Lemmerzahl method (laboratory tests) and pot tests. The full cycle of assessment of resistance to wart disease requires 52 seed potatoes per variety/breeding line. Forty two tubers are used in laboratory tests. To complete the laboratory tests the next 10 tubers are grown in pot tests (in soil with winter sporangia) during the vegetation season. The final results for domestic breeding lines of potato are available after 3 years of investigation. For cultivars from other countries the authorization of resistance to S. endobioticum takes approximately one year. The Polish breeders (breeding lines) or the breeder's representative (cultivars from other countries) receive the certificate only for lines/cultivars with laboratory and field resistance to S. endobioticum. [source] | ||||||||||||||||||||||||||||||||||