Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “tuber”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed2000

A competitive PCR-based method for the detection and quantification of Erwinia carotovora subsp. atroseptica On potato tubers.

A PCR-based method was developed for the simultaneous detection and quantification of the potato pathogen Erwinia carotovora subsp. atroseptica (Eca) on potato tubers. The method incorporates a competitor PCR template cloned into Escherichia coli in vector pGEM-T (E. coli 4R l/l). Predetermined numbers of E. coli 4R were added to potato peel extract, either pre-inoculated with Eca or from naturally contaminated tubers, and Eca numbers estimated by comparing the ratio of products generated from Eca target DNA and competitor template DNA following PCR. Estimates of Eca numbers were consistent with counts obtained on crystal violet pectate medium and immunofluorescence colony staining. Unlike these methods, however, the PCR-based method is not affected by the presence of other erwinias and saprophytes and is able to detect all serogroups of Eca. Based on this method, a key was produced relating product ratios, obtained following PCR from contaminated tuber stocks, to the likelihood of blackleg disease incidence. This is the first quantitative PCR-based detection method described for Eca and is the first for any bacterial plant pathogen to incorporate a DNA extraction control.

Colony Count, Microbial↗
PubMed1996

Bioavailability to rats of 14C-lindane residues in stored potato tubers.

Potato tubers were applied with radiolabelled lindane (U-14C gamma- 1,2,3,4,5,6-hexachlorocyclohexane) at three dose levels 30, 150, and 300 ppm and stored for 30, 60 and 90 days at room temperature. The data revealed that lindane penetrated into the pulp tissues through the epidermal layer. The amounts recovered in the peel were found to increase with a greater storage period up to 60 days followed by a drop at 90 days. On the other hand, there was a slight increase in radioactivity in the pulp tissue from 30 to 60 days followed by significant increase after 90 days. The incorporation of the compound in the tubers was dose independent. Methanol extraction showed binding of about 8.1% and 5.8% of the applied dose in peel and pulp tissues, respectively. The insecticide was found to be bioavailable when rats health hazard. It is therefore, desirable to demonstrate that the quantity of the terminal residues may be safe for the consumer. In the present investigation an attempt was made to determine the fate and bioavailability of lindane when applied to stored potato tubers.

Animal Feed↗
PubMed1979

Preparation of high-fructose syrup from the tubers of the Jerusalem artichoke (Helianthus tuberosus L.

Fructose has recently received much attention due to renewed interest in natural sweeteners. In addition, fructose has some advantages to sucrose in sweetness, solubility, viscosity, and dental health characteristics. Fructose is deposited as storage fructans of the inulin (beta-1,2) type in tubers and rhizomes of the Compositae family. The utilization of the Jerusalem artichoke (Helianthus tuberosus) tuber as a source of fructose syrup is discussed. This plant has the potential to produce more sugar per acre than corn or sugar beets. In addition, the artichoke has higher frost resistance and lower heat unit requirements than corn and is somewhat more tolerant to low moisture conditions than sugar beets. A high quality fructose syrup can be produced from artichoke tubers. The extraction step was found to be particularly important since development of adverse colors and flavors must be prevented. The fructans may be acid or enzyme hydrolyzed but the latter method gave a higher quality syrup. Ion-exchange resins and activated charcoal were effective in removing coloring and flavoring materials, and also reduced other noncarbohydrate constituents. Since the enzymatic hydrolysis of the fructans is an attractive alternative to acid hydrolysis, a process was developed for producing and purifying a special beta-fructofuranosidase (inulase) from Saccharomyces fragilis. Inulase has a much higher specificity for fructans than commerically available beta-fructofuranosidase (invertase).

Carbohydrates↗
PubMed2003

Tuber storage proteins.

A wide range of plants are grown for their edible tubers, but five species together account for almost 90 % of the total world production. These are potato (Solanum tuberosum), cassava (Manihot esculenta), sweet potato (Ipomoea batatus), yams (Dioscorea spp.) and taro (Colocasia, Cyrtosperma and Xanthosoma spp.). All of these, except cassava, contain groups of storage proteins, but these differ in the biological properties and evolutionary relationships. Thus, patatin from potato exhibits activity as an acylhydrolase and esterase, sporamin from sweet potato is an inhibitor of trypsin, and dioscorin from yam is a carbonic anhydrase. Both sporamin and dioscorin also exhibit antioxidant and radical scavenging activity. Taro differs from the other three crops in that it contains two major types of storage protein: a trypsin inhibitor related to sporamin and a mannose-binding lectin. These characteristics indicate that tuber storage proteins have evolved independently in different species, which contrasts with the highly conserved families of storage proteins present in seeds. Furthermore, all exhibit biological activities which could contribute to resistance to pests, pathogens or abiotic stresses, indicating that they may have dual roles in the tubers.

Amino Acid Sequence↗
PubMed2003

Regulation of sucrose to starch conversion in growing potato tubers.

Growing potato tubers have been used as a model system to investigate the regulation of starch synthesis. Results indicate that sucrose degradation and starch synthesis are controlled via regulatory signals in response to sucrose and oxygen availability. (i) Sucrose leads to a co-ordinated up-regulation of sucrose synthase and ADP-glucose phosphorylase at the transcriptional and post-transcriptional level. Transcriptional regulation of ADP-glucose phosphorylase leads to rapid changes in transcript levels, but relatively slow changes in protein levels. The rapid regulation of this enzyme in response to sucrose is mediated by a novel mechanism, involving redox-activation of ADPGlc pyrophosphorylase. Sucrose synthase is regulated via transcriptional regulation, but again the resulting changes in enzyme activity occur relatively slowly. More rapid changes in the flux of this enzyme follow due to rapid changes in the levels of uridine nucleotides. (ii) Internal oxygen concentrations fall to low levels in growing tubers, triggering a restriction of respiration, a decrease in the adenylate energy status, and a widespread decrease in metabolic and biosynthetic activity. These metabolic adaptations will allow oxygen consumption to be decreased and prevent the tissue from becoming anoxic. It will be discussed how these factors interact at different levels and different time-scales of control to regulate tuber metabolism in response to physiological and environmental inputs.

Cell Respiration↗
PubMed1998

Evidence for the cell wall involvement in temporal changes in freezing tolerance of Jerusalem artichoke (Helianthus tuberosus L.) tubers during cold acclimation.

We studied the mechanism of cold acclimation of Jerusalem artichoke (Helianthus tuberosus L.) tubers with special reference to the role of the cell wall. During the cold-acclimation process from September to January, the freezing tolerance of tubers increased from -2.8 degrees C to -8.4 degrees C (LT50). By contrast, the isolated protoplasts constitutively showed a consistent high level of freezing tolerance (LT50; below -25 degrees C) throughout the period. In tuber tissues, freezing injury was effectively protected by the external addition of isotonic solutions. Cryomicroscopic observations revealed that tissue cells mounted in isotonic solutions plasmolyzed upon freezing; tissue cells mounted in water collapsed with a tight attachment of plasma membrane to the cell wall. Upon freezing of intact tissues in water to temperatures below the critical range, the cytoplasm was irreversibly acidified as revealed by a fluorescence pH-ratiometry, suggesting that occurrence of detrimental cellular events leading to permanent cell injury. The freeze-induced acidification of cytoplasm was also effectively prevented by the external addition of isotonic solutions. These results suggest that the tight attachment of the plasma membrane to the cell wall during freezing may have a harmful effect on cells, in particular on the plasma membrane, possibly due to mechanical or some sort of chemical/ physico-chemical interaction with the cell wall.

Acclimatization↗
PubMed2005

In vivo expression of a Cicer arietinum beta-galactosidase in potato tubers leads to a reduction of the galactan side-chains in cell wall pectin.

We report the generation of Solanum tuberosum transformants expressing Cicer arietinum betaIII-Gal. betaIII-Gal is a beta-galactosidase able to degrade cell wall pectins during cell wall loosening that occurs prior to cell elongation. cDNA corresponding to the gene encoding this protein was identified among several chickpea beta-galactosidase cDNAs, and named CanBGal-3. CanBGal-3 cDNA was expressed in potato under the control of the granule-bound starch synthase promoter. Three betaIII-Gal transformants with varying levels of expression were chosen for further analysis. The transgenic plants displayed no significant altered phenotype compared to the wild type. However, beta-galactanase and beta-galactosidase activities were increased in the transgenic tuber cell walls and this affected the potato tuber pectins. A reduction in the galactosyl content of up to 50% compared to the wild type was observed in the most extreme transformant, indicating a reduction of 1,4-beta-galactan side-chains, as revealed by analysis with LM5 specific antibodies. Our results confirm the notion that the pectin-degrading activity of chickpea betaIII-Gal reported in vitro also occurs in vivo and in other plants, and confirm the involvement of betaIII-Gal in the cell wall autolysis process. An increase in the homogalacturonan content of transgenic tuber cell walls was also observed by Fourier transform infrared spectroscopy (FTIR) analysis.

Blotting, Northern↗
PubMed2005

Physiological and metabolic adaptations of Potamogeton pectinatus L. tubers support rapid elongation of stem tissue in the absence of oxygen.

Tubers of Potamogeton pectinatus L., an aquatic pondweed, over-winter in the anoxic sediments of rivers, lakes and marshes. Growth of the pre-formed shoot that emerges from the tuber is remarkably tolerant to anoxia, with elongation of the stem occurring faster when oxygen is absent. This response, which allows the shoot to reach oxygenated waters, occurs despite a 69-81% reduction in the rate of ATP production, and it is underpinned by several physiological and metabolic adaptations that contribute to efficient energy usage. First, extension of the pre-formed shoot is the result of cell expansion, without the accumulation of new cellular material. Secondly, after over-wintering, the tuber and pre-formed shoot have the enzymes necessary for a rapid fermentative response at the onset of growth under anoxia. Thirdly, the incorporation of [(35)S]methionine into protein is greatly reduced under anoxia. The majority of the anoxically synthesized proteins differ from those in aerobically grown tissue, implying an extensive redirection of protein synthesis under anoxia. Finally, anoxia-induced cytoplasmic acidosis is prevented to an unprecedented degree. The adaptations of this anoxia-tolerant plant tissue emphasize the importance of the mechanisms that balance ATP production and consumption in the absence of oxygen.

Adaptation, Physiological↗
PubMed1988

A musculocutaneous transposition flap mammaplasty for correction of the tuberous breast.

Presented here is a technique employing a laterally based serratus musculocutaneous transposition flap for the correction of the infraareolar skin insufficiency characteristic of the tuberous breast deformity in its severe form. This surgical maneuver, augmenting those previously described for this problem, allows for the sculpting of a fuller and more pleasing breast contour with a better defined inframammary fold. Two patients are presented, one with a bilateral severe tuberous deformity and the other with a severe asymmetry and a unilateral severe tuberous deformity.

Adolescent↗
PubMed2000

Tuberous breast deformity: principles and practice.

The tuberous breast deformity is one of the most challenging congenital breast anomalies. The nomenclature, classification, and treatment of this pathological condition have varied considerably. In this study, 16 patients with 23 tuberous breast deformities are evaluated. The breast deformities are classified according to the three-tier classification system used at the authors' institution. The treatment pattern is evaluated and a flexible algorithm is discussed for the treatment of the tuberous breast deformity.

Breast↗
PubMed1980

The neuroendocrine control of gonadotrophin release in the Japanese quail. III. The role of the tuberal and anterior hypothalamus in the control of ovarian development and ovulation.

Reproduction in the Japanese quail (Coturnix coturnix japonica), as in many other species, is controlled by the length of the daily photoperiod. The present experiments have investigated the neuroendocrine regulation of both the photoperiodically induced 'tonic' gonadotrophin secretion, which causes the development and maintenance of the ovary, and the 'cyclic' surge release of luteinizing hormone (LH), which stimulates ovulation. Areas within the anterior and tuberal hypothalamus were destroyed by means of electrolytic lesions while a small knife was used to isolate, to various degrees, the tuberal hypothalamus. Information was obtained on the regulation of 'tonic' and 'cyclic' secretion of gonadotrophin by using immature and mature laying females, respectively. The results indicate that the neuroendocrine regulation of photoperiodically induced gonadotrophin secretion in immature quail appears to be controlled by two discrete hypothalamic centres, the infundibular nuclear complex (i.n.c.) and the preoptic region (po.r.). The supraoptic region (so.r.) appears to have no influence on photoperiodically induced ovarian development. Deafferentation reveals that afferents from the anterior hypothalamus enter the tuberal region in a diffuse manner from both anterior and lateral directions. As in the developing animals, destruction of either the i.n.c. or the po.r. in mature birds results in a complete block to 'tonic' gonadotrophin release and to regression of the ovaries. When the supraoptic region is destroyed, the 'cyclic' ovulatory surge of LH is blocked and a polyfollicular syndrome ensues in which the ovaries, still under the influence of 'tonic' gonadotrophin release, grow to a very large size, but no ovulation takes place. An intramuscular injection of progesterone stimulates a release of LH in both untreated mature females and in sham-operated females, but not in so.r.-lesioned birds. Priming these lesioned females with oestrogen and progesterone restores, in some birds, the ability to respond positively to progesterone stimulation.

Animals↗
PubMed2002

Expression analysis of a family of nsLTP genes tissue specifically expressed throughout the plant and during potato tuber life cycle.

Non-specific lipid-transfer proteins (nsLTPs) are capable of binding lipid compounds in plant tissues and are coded by the nsLTP genes. Here, we present the analysis of expression of a family of potato (Solanum tuberosum) nsLTP genes that express throughout the developing plant in a highly tissue-specific manner. Three transcript-derived fragments were isolated using an amplified restriction fragment polymorphism-derived technique for RNA fingerprinting that show homology to plant nsLTP genes. These transcript-derived fragments displayed modulated expression profiles related to the development of new tissues, with a peak of transcription around the time of tuberization and just prior to sprout development, at dormancy breakage. In addition, a homologous family of expressed sequence tags was identified whose individual members could be classified according to their tissue specificity. Two subgroups of expressed sequence tags were found to express during tuber life cycle. To study the regulation of potato nsLTP genes, two putative potato nsLTP promoters were isolated and their expression was studied using promoter-marker-gene fusions. The results showed that one of the two promoters directed a highly specific pattern of expression detected in the phloem surrounding the nodes of young plants and in the same tissue of tuber related organs, whereas the second putative promoter showed little tissue or organ specificity. This difference in expression is likely due to a 331-bp insertion present in the tissue-specific promoter.

Amino Acid Sequence↗
PubMed2003

Biphasic superoxide generation in potato tubers. A self-amplifying response to stress.

Potato (Solanum tuberosum) cultivars differ quantitatively in their responses to mechanical stress including the ability to synthesize melanin pigments in tuber tissues. Investigations into the cellular events induced by mechanical stress on tuber tissues have shown that an early cellular response is a significant and rapid synthesis of superoxide radicals. This burst of radical production distinctively displays a reproducible biphasic pattern over time with peaks of generation at 2 and 5 h. A concomitant consequence of the generation of these free radicals is elevated levels of oxidatively modified tuber proteins. Both radical generation and protein modification vary between cultivars but both are directly proportional to the amount of melanin pigments produced. Cell-free extracts of mechanically stressed tissues, pectic fragments, and scission products generated from cell walls are able to induce superoxide generation in non-stressed tissues, indicating the participation of a biologically active factor that induces a further a phase of radical synthesis.

Adaptation, Physiological↗
PubMed1992

Apoplastic expression of yeast-derived invertase in potato : effects on photosynthesis, leaf solute composition, water relations, and tuber composition.

In potato plants (Solanum tuberosum), a chimeric yeast-derived invertase gene fused to a 35S cauliflower mosaic virus promoter has been expressed. The protein was targeted to the cell wall by using the signal peptide of proteinase inhibitor II fused to the amino terminus of the yeast invertase. The transformed plants had crinkled leaves, showed a reduced growth rate, and produced fewer tubers. Although in the apoplast of the leaves of the transformed plants the content of glucose and fructose rose by a factor of 20, and that of sucrose declined 20-fold, 98% of the carbohydrate in the phloem sap consisted of sucrose, demonstrating the strong specificity of phloem loading. In the leaf cells of the transformed plants, glucose, fructose, and amino acids, especially proline, were accumulated. Consequently, the osmolality of the cell sap rose from 250 to 350 mosmol/kg. Our results show that the observed 75% decrease of photosynthesis is not caused by a feedback regulation of sucrose synthesis and is accompanied by an increase in the osmotic pressure in the leaf cells. In the transformed plants, not only the amino acid to sucrose ratio in the phloem sap, but also the amino acid and protein contents in the tubers were found to be elevated. In the tubers of the transformed plants, the protein to starch ratio increased.

Journal Article↗
PubMed1993

Further Evidence for Stachyose and Sucrose/H+ Antiporters on the Tonoplast of Japanese Artichoke (Stachys sieboldii) Tubers.

Vacuoles of Japanese artichoke (Stachys sieboldii) tubers accumulate up to 180 mM stachyose ([alpha]-galactose-[1->6]-[alpha]-galactose-[1->6]-[alpha]-glucose-[1 <->2]-[beta]-fructose) against a concentration gradient, probably by means of an active stachyose/H+ antiporter situated on the tonoplast. The goal of this study was to use isolated tonoplast vesicles to provide further evidence for the existence of such a transport mechanism. Therefore, vesicles were prepared from purified vacuoles of dormant tubers. ATP- and pyrophosphate (PPi)-dependent fluorescence quenching of the [delta]pH probe 9-amino-6-chloro-2-methoxyacridine (ACMA) indicated that these vesicles were capable of building up a pH gradient ([delta]pH, inside acid). The potent V-type H+-ATPase inhibitor bafilomycin prevented the formation of a [delta]pH in the vesicles. Bafilomycin (as well as nitrate, but not vanadate) also inhibited ATP hydrolysis, confirming the tonoplast origin of the isolated vesicles. Addition of stachyose (or sucrose, but not of mannitol) to energized vesicles caused a recovery of ACMA fluorescence, indicating a sugar-dependent dissipation of [delta]pH. The rate of fluorescence recovery was dependent on the external sugar concentration used. It displayed a single saturable response to increasing sugar concentrations. Apparent Km values of 52 and 25 mM were computed for stachyose and sucrose antiporter activities, respectively. It was also demonstrated that energized vesicles showed a much higher rate of [14C]stachyose (3 mM) and [14C]sucrose (1 mM) uptake than deenergized vesicles. The results obtained with isolated tonoplast vesicles were very similar to those obtained earlier with intact vacuoles and, therefore, confirm the existence of active stachyose and sucrose/H+ antiporters on the tonoplast of Stachys tuber vacuoles.

Journal Article↗
PubMed2003

De novo amino acid biosynthesis in potato tubers is regulated by sucrose levels.

Plant growth and development are strongly dependent on sink-source interactions. In the majority of plants, sucrose (Suc) is the dominant form in which photo-assimilate is transported from source to sinks. Although the effects of Suc on photosynthetic metabolism have been intensively studied, the effect of Suc supply on metabolism in sink organs has received relatively little attention. For this reason, we performed a detailed characterization of the metabolism of potato (Solanum tuberosum) plants in which the Suc supply to the tuber was restricted by genetic or environmental perturbation. These characterizations revealed a clear inverse relationship between the levels of Suc and free amino acids. When data obtained from this study were considered alongside our previous work, a negative correlation between tuber Suc and amino acid content became apparent. Analysis of the transcript levels of key enzymes involved in amino acid biosynthesis revealed that several of these were increased under these conditions. Taken together, these data strongly suggest that Suc regulates amino acid biosynthesis in storage tissues such as potato tubers, most probably at the level of transcription.

Amino Acids↗
PubMed1994

Expression of Escherichia coli glycogen synthase in the tubers of transgenic potatoes (Solanum tuberosum) results in a highly branched starch.

A chimeric gene containing the patatin promoter and the transit-peptide region of the small-subunit carboxylase gene was utilized to direct expression of Escherichia coli glycogen synthase (glgA) to potato (Solanum tuberosum) tuber amyloplasts. Expression of the glgA gene product in tuber amyloplasts was between 0.007 and 0.028% of total protein in independent potato lines as determined by immunoblot analysis. Tubers from four transgenic potato lines were found to have a lowered specific gravity, a 30 to 50% reduction in the percentage of starch, and a decreased amylose/amylopectin ratio. Total soluble sugar content in these selected lines was increased by approximately 80%. Analysis of the starch from these potato lines also indicated a reduced phosphorous content. A very high degree of branching of the amylopectin fraction was detected by comparison of high and low molecular weight carbohydrate chains after debranching with isoamylase and corresponding high-performance liquid chromatography analysis of the products. Brabender viscoamylograph analysis and differential scanning calorimetry of the starches obtained from these transgenic potato lines also indicate a composition and structure much different from typical potato starch. Brabender analysis yielded very low stable paste viscosity values (about 30% of control values), whereas differential scanning calorimetry values indicated reduced enthalpy and gelatinization properties. The above parameters indicate a novel potato starch based on expression of the glgA E. coli gene product in transgenic potato.

Base Sequence↗
PubMed1995

The major tuber storage protein of araceae species is a lectin. Characterization and molecular cloning of the lectin from Arum maculatum L.

A new lectin was purified from tubers of Arum maculatum L. by affinity chromatography on immobilized asialofetuin. Although this lectin is also retained on mannose-Sepharose 4B, under the appropriate conditions free mannose is a poor inhibitor of its agglutination activity. Pure preparations of the Arum lectin apparently yielded a single polypeptide band of approximately 12 kD upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, N-terminal sequencing of the purified protein combined with molecular cloning of the lectin have shown that the lectin is composed of two different 12-kD lectin subunits that are synthesized on a single large precursor translated from an mRNA of approximately 1400 nucleotides. Lectins with similar properties were also isolated from the Araceae species Colocasia esculenta (L.) Schott, Xanthosoma sagittifolium (L.) Schott, and Dieffenbachia sequina Schott. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration of the different Araceae lectins have shown that they are tetrameric proteins composed of lectin subunits of 12 to 14 kD. Interestingly, these lectins are the most prominent proteins in the tuber tissue. Evidence is presented that a previously described major storage protein of Colocasia tubers corresponds to the lectin.

Amino Acid Sequence↗