Solanum tuberosum: A plant species of the genus SOLANUM, family SOLANACEAE. The starchy roots are used as food. SOLANINE is found in green parts.Solanum: A plant genus of the family SOLANACEAE. Members contain SOLANACEOUS ALKALOIDS. Some species in this genus are called deadly nightshade which is also a common name for ATROPA BELLADONNA.Plant Tubers: An enlarged underground root or stem of some plants. It is usually rich in carbohydrates. Some, such as POTATOES, are important human FOOD. They may reproduce vegetatively from buds.Solanum nigrum: A plant species of the genus SOLANUM, family SOLANACEAE that contains steroidal glycosides.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Plants, Genetically Modified: PLANTS, or their progeny, whose GENOME has been altered by GENETIC ENGINEERING.Solanum melongena: A plant species of the genus SOLANUM, family SOLANACEAE. The fruit is a large, egg-shaped berry, varying in color from dark purple to red, yellowish, or white. The leaves are large and ovate. The flowers are pendant, violet, and two inches across.Lycopersicon esculentum: A plant species of the family SOLANACEAE, native of South America, widely cultivated for their edible, fleshy, usually red fruit.Plant Stems: Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)Phytophthora infestans: A species of parasitic OOMYCETES in the family Peronosporaceae that is the causative agent of late blight of potato.Solanaceae: A plant family of the order Solanales, subclass Asteridae. Among the most important are POTATOES; TOMATOES; CAPSICUM (green and red peppers); TOBACCO; and BELLADONNA.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Glucose-1-Phosphate Adenylyltransferase: An ATP-dependent enzyme that catalyzes the addition of ADP to alpha-D-glucose 1-phosphate to form ADP-glucose and diphosphate. The reaction is the rate-limiting reaction in prokaryotic GLYCOGEN and plant STARCH biosynthesis.Gene Expression Regulation, Plant: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.Phytophthora: A genus of destructive parasitic OOMYCETES in the family Peronosporaceae, order Peronosporales, affecting numerous fruit, vegetable, and other crops. Differentiation of zoospores usually takes place in the sporangium and no vesicle is formed. It was previously considered a fungus.Plant Diseases: Diseases of plants.Starch: Any of a group of polysaccharides of the general formula (C6-H10-O5)n, composed of a long-chain polymer of glucose in the form of amylose and amylopectin. It is the chief storage form of energy reserve (carbohydrates) in plants.Starch Phosphorylase: An enzyme of the PHOSPHORYLASES family that catalyzes the degradation of starch, a mixture of unbranched AMYLOSE and branched AMYLOPECTIN compounds. This phosphorylase from plants is the counterpart of GLYCOGEN PHOSPHORYLASE in animals that catalyzes the reaction of inorganic phosphate on the terminal alpha-1,4-glycosidic bond at the non-reducing end of glucans resulting in the release of glucose-1-phosphate.Datura stramonium: A plant species of the genus DATURA, family SOLANACEAE, that contains TROPANES and other SOLANACEOUS ALKALOIDS.Plant Structures: The parts of plants, including SEEDS.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Plants: Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.Genes, Plant: The functional hereditary units of PLANTS.Plant Lectins: Protein or glycoprotein substances of plant origin that bind to sugar moieties in cell walls or membranes. Some carbohydrate-metabolizing proteins (ENZYMES) from PLANTS also bind to carbohydrates, however they are not considered lectins. Many plant lectins change the physiology of the membrane of BLOOD CELLS to cause agglutination, mitosis, or other biochemical changes. They may play a role in plant defense mechanisms.RNA, Plant: Ribonucleic acid in plants having regulatory and catalytic roles as well as involvement in protein synthesis.Chromosomes, Plant: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of PLANTS.beta-Fructofuranosidase: A glycoside hydrolase found primarily in PLANTS and YEASTS. It has specificity for beta-D-fructofuranosides such as SUCROSE.Adenosine Diphosphate Glucose: Serves as the glycosyl donor for formation of bacterial glycogen, amylose in green algae, and amylopectin in higher plants.Isomaltose: A disaccharide consisting of two glucose units in an alpha (1-6) glycosidic linkage.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.DNA, Plant: Deoxyribonucleic acid that makes up the genetic material of plants.Lectins: Proteins that share the common characteristic of binding to carbohydrates. Some ANTIBODIES and carbohydrate-metabolizing proteins (ENZYMES) also bind to carbohydrates, however they are not considered lectins. PLANT LECTINS are carbohydrate-binding proteins that have been primarily identified by their hemagglutinating activity (HEMAGGLUTININS). However, a variety of lectins occur in animal species where they serve diverse array of functions through specific carbohydrate recognition.Caulimovirus: A genus of PLANT VIRUSES, in the family CAULIMOVIRIDAE, that are transmitted by APHIDS in a semipersistent manner. Aphid-borne transmission of some caulimoviruses requires certain virus-coded proteins termed transmission factors.Potexvirus: A genus of plant viruses in the family FLEXIVIRIDAE, that cause mosaic and ringspot symptoms. Transmission occurs mechanically. Potato virus X is the type species.Tobacco: A plant genus of the family SOLANACEAE. Members contain NICOTINE and other biologically active chemicals; its dried leaves are used for SMOKING.Rhizosphere: The immediate physical zone surrounding plant roots that include the plant roots. It is an area of intense and complex biological activity involving plants, microorganisms, other soil organisms, and the soil.Genome, Plant: The genetic complement of a plant (PLANTS) as represented in its DNA.Glyceric AcidsSequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Oxylipins: Eighteen-carbon cyclopentyl polyunsaturated fatty acids derived from ALPHA-LINOLENIC ACID via an oxidative pathway analogous to the EICOSANOIDS in animals. Biosynthesis is inhibited by SALICYLATES. A key member, jasmonic acid of PLANTS, plays a similar role to ARACHIDONIC ACID in animals.Lipoxygenase: An enzyme of the oxidoreductase class primarily found in PLANTS. It catalyzes reactions between linoleate and other fatty acids and oxygen to form hydroperoxy-fatty acid derivatives.Plastids: Self-replicating cytoplasmic organelles of plant and algal cells that contain pigments and may synthesize and accumulate various substances. PLASTID GENOMES are used in phylogenetic studies.Cyclopentanes: A group of alicyclic hydrocarbons with the general formula R-C5H9.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Apyrase: A calcium-activated enzyme that catalyzes the hydrolysis of ATP to yield AMP and orthophosphate. It can also act on ADP and other nucleoside triphosphates and diphosphates. EC 188.8.131.52.Sucrose: A nonreducing disaccharide composed of GLUCOSE and FRUCTOSE linked via their anomeric carbons. It is obtained commercially from SUGARCANE, sugar beet (BETA VULGARIS), and other plants and used extensively as a food and a sweetener.DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Nucleotidyltransferases: A class of enzymes that transfers nucleotidyl residues. EC 2.7.7.Carbohydrate Metabolism: Cellular processes in biosynthesis (anabolism) and degradation (catabolism) of CARBOHYDRATES.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Carbohydrates: The largest class of organic compounds, including STARCH; GLYCOGEN; CELLULOSE; POLYSACCHARIDES; and simple MONOSACCHARIDES. Carbohydrates are composed of carbon, hydrogen, and oxygen in a ratio of Cn(H2O)n.Photoperiod: The time period of daily exposure that an organism receives from daylight or artificial light. It is believed that photoperiodic responses may affect the control of energy balance and thermoregulation.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Disease Resistance: The capacity of an organism to defend itself against pathological processes or the agents of those processes. This most often involves innate immunity whereby the organism responds to pathogens in a generic way. The term disease resistance is used most frequently when referring to plants.Mitochondria: Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)Allium: A genus of the plant family Liliaceae (sometimes classified as Alliaceae) in the order Liliales. Many produce pungent, often bacteriostatic and physiologically active compounds and are used as VEGETABLES; CONDIMENTS; and medicament, the latter in traditional medicine.
Superior (potato): 'Superior' is a white-skinned and white-fleshed, midseason potato variety. It was released by the University of Wisconsin potato breeding program in 1962 and is not under plant variety protection.Solanum chacoense: Solanum chacoense is a species of wild potato. It is native to South America, where it can be found in Brazil, Bolivia, Argentina, Peru, Uruguay, and Paraguay.Taradi: Taradi, or Himalayan yam, is a little-studied plant which appears above the ground as a low vine, but underground bears long, convoluted tuber growth stretching sometimes as deep as 2 metres. It is native to Palampur in northern India.Plant perception (physiology): Plant perception is the ability of plants to sense and respond to the environment to adjust their morphology, physiology and phenotype accordingly. Other disciplines such as plant physiology, ecology and molecular biology are used to assess this ability.Cercospora melongenae: Cercospora melongenae is a fungal plant pathogen that causes leaf spot on eggplant (Solanum melongenum). It is a deuteromycete fungus that is primarily confined to eggplant species.Sun-dried tomato: Sun-dried tomatoes are ripe tomatoes that lose most of their water content after spending a majority of their drying time in the sun. These tomatoes are usually pre-treated with sulfur dioxide or salt before being placed in the sun in order to improve quality.Pith: 250px|right|thumb|[[Elderberry shoot cut longitudinally to show the broad, solid pith (rough-textured, white) inside the wood (smooth, yellow-tinged). Scale in mm.Phytophthora infestans: Phytophthora infestans is an oomycete that causes the serious potato disease known as late blight or potato blight. (Early blight, caused by Alternaria solani, is also often called "potato blight".Brunfelsia: Brunfelsia is a genus of flowering plants in the family Solanaceae, the nightshades. There are about 50 species described.Canna Leaf Roller: Cannas are largely free of pests, but in the USA plants sometimes fall victim the Canna Leaf Roller, which can actually be two different insects. Larva of the Brazilian skipper butterfly (Calpodes ethlius), also known as the Larger Canna Leaf Roller, cut the leaves and roll them over to live inside while pupating and eating the leaf.Wolfgang PreissSquamosa promoter binding protein: The SQUAMOSA promoter binding protein-like (SBP or SPL) family of transcription factors are defined by a plant-specific DNA-binding domain. The founding member of the family was identified based on its specific in vitro binding to the promoter of the snapdragon SQUAMOSA gene.Phytophthora ramorum: Phytophthora ramorum is the oomycete plant pathogen known to cause the disease sudden oak death (SOD). The disease kills oak and other species of trees and has had devastating effects on the oak populations in California and Oregon, as well as being present in Europe.Fungicide use in the United States: A more accurate title for this page would be "Common plant pathogens to food crops in the United States".Starch gelatinization: Starch gelatinization is a process of breaking down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. This irreversibly dissolves the starch granule in water.Jimson Weed (painting): Jimson Weed is an oil on linen painting by American artist Georgia O'Keeffe from 1936, located in the Indianapolis Museum of Art, which is in Indianapolis, Indiana, USA. It depicts four large blossoms of jimson weed, or datura.Aureusidin synthase: Aureusidin synthase (, AmAS1) is an enzyme with system name 2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside:oxygen oxidoreductase.Endodermis: The endodermis is the central, innermost layer of cortex in some land plants. It is made of compact living cells surrounded by an outer ring of endodermal cells that are impregnated with hydrophobic substances (Casparian Strip) to restrict apoplastic flow of water to the inside.Coles PhillipsJacalin: Jacalin is a plant based lectin, but not a legume lectin, found in jackfruit. It has been studied for capturing O-glycoproteins such as mucins and IgA1, for potential applications in human immunology.Invertase: Invertase is an enzyme that catalyzes the hydrolysis (breakdown) of sucrose (table sugar). Alternate names for invertase include , saccharase, glucosucrase, beta-h-fructosidase, beta-fructosidase, invertin, sucrase, maxinvert L 1000, fructosylinvertase, alkaline invertase, acid invertase, and the systematic name: beta-fructofuranosidase.Isomaltooligosaccharide: Isomaltooligosaccharide (IMO) is a mixture of short-chain carbohydrates which has a digestion-resistant property. IMO is found naturally in some foods, as well as being manufactured commercially.Protein primary structure: The primary structure of a peptide or protein is the linear sequence of its amino acid structural units, and partly comprises its overall biomolecular structure. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end.Leguminous lectin family: In molecular biology, the leguminous lectin family is a family of lectin proteins.Nicotiana glauca: Nicotiana glauca is a species of wild tobacco known by the common name tree tobacco. Its leaves are attached to the stalk by petioles (many other Nicotiana species have sessile leaves), and its leaves and stems are neither [nor sticky like Nicotiana tabacum].Rhizosphere: The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms. Soil which is not part of the rhizosphere is known as bulk soil.Glyceric acidSymmetry element: A symmetry element is a point of reference about which symmetry operations can take place. In particular, symmetry elements can be centers of inversion, axes of rotation and mirror planes.Octadecanoid pathway: The octadecanoid pathway is a reasonably well-characterized biosynthetic pathway for the production of the phytohormone jasmonic acid (JA), an important hormone for induction of defense genes. JA is synthesized from alpha-linolenic acid, which can be released from the plasma membrane by certain lipase enzymes.Arachidonate 5-lipoxygenase: Arachidonate 5-lipoxygenase, also known as 5-lipoxygenase, 5-LOX or 5-LO, is an enzyme that in humans is encoded by the ALOX5 gene. Arachidonate 5-lipoxygenase is a member of the lipoxygenase family of enzymes.Stromule: A stromule is a microscopic structure found in plant cells. Stromules (stroma-filled tubules) are highly dynamic structures extending from the surface of all plastid types, including proplastids, chloroplasts, etioplasts, leucoplasts, amyloplasts, and chromoplasts.CyclopentaneBranching order of bacterial phyla (Gupta, 2001): There are several models of the Branching order of bacterial phyla, one of these was proposed in 2001 by Gupta based on conserved indels or protein, termed "protein signatures", an alternative approach to molecular phylogeny. Some problematic exceptions and conflicts are present to these conserved indels, however, they are in agreement with several groupings of classes and phyla.Apyrase: Apyrase (, ATP-diphosphatase, adenosine diphosphatase, ADPase, ATP diphosphohydrolase) is a calcium-activated plasma membrane-bound enzyme (magnesium can also activate it) () that catalyses the hydrolysis of ATP to yield AMP and inorganic phosphate. Two isoenzymes are found in commercial preparations from S.Sucrose gap: The sucrose gap technique is used to create a conduction block in nerve or muscle fibers. A high concentration of sucrose is applied to the extracellular space to increase resistance between two groups of cells, which prevents the correct opening and closing of sodium and potassium channels.Ligation-independent cloning: Ligation-independent cloning (LIC) is a form of molecular cloning that is able to be performed without the use of restriction endonucleases or DNA ligase. This allows genes that have restriction sites to be cloned without worry of chopping up the insert.Nucleoside-triphosphate-hexose-1-phosphate nucleotidyltransferase: Nucleoside-triphosphate-aldose-1-phosphate nucleotidyltransferase (, NDP hexose pyrophosphorylase, hexose 1-phosphate nucleotidyltransferase, hexose nucleotidylating enzyme, nucleoside diphosphohexose pyrophosphorylase, hexose-1-phosphate guanylyltransferase, GTP:alpha-D-hexose-1-phosphate guanylyltransferase, GDP hexose pyrophosphorylase, guanosine diphosphohexose pyrophosphorylase, NTP:hexose-1-phosphate nucleotidyltransferase) is an enzyme with system name NTP:alpha-D-aldose-1-phosphate nucleotidyltransferase. This enzyme catalyses the following chemical reactionCS-BLASTCarbohydrate chemistry: Carbohydrate chemistry is a subdiscipline of chemistry primarily concerned with the synthesis, structure, and function of carbohydrates. Due to the general structure of carbohydrates, their synthesis is often preoccupied with the selective formation of glycosidic linkages and the selective reaction of hydroxyl groups; as a result, it relies heavily on the use of protecting groups.DNA sequencer: A DNA sequencer is a scientific instrument used to automate the DNA sequencing process. Given a sample of DNA, a DNA sequencer is used to determine the order of the four bases: G (guanine), C (cytosine), A (adenine) and T (thymine).Mitochondrion: The mitochondrion (plural mitochondria) is a double membrane-bound organelle found in most eukaryotic cells. The word mitochondrion comes from the Greek , , i.Allium drummondii: Drummond's onion (Allium drummondii), also known as Wild garlic and the Prairie onion, is a North American species of onion native to the southern Great Plains of North America. It is found in South Dakota, Kansas, Nebraska, Colorado, Oklahoma, Arkansas, Texas, New Mexico, and northeastern Mexico.
(1/1525) Synthesis and kinetic evaluation of 4-deoxymaltopentaose and 4-deoxymaltohexaose as inhibitors of muscle and potato alpha-glucan phosphorylases.
alpha-Glucan phosphorylases degrade linear or branched oligosaccharides via a glycosyl transfer reaction, occurring with retention of configuration, to generate alpha-glucose-1-phosphate (G1P). We report here the chemoenzymic synthesis of two incompetent oligosaccharide substrate analogues, 4-deoxymaltohexaose (4DG6) and 4-deoxymaltopentaose (4DG5), for use in probing this mechanism. A kinetic analysis of the interactions of 4DG5 and 4DG6 with both muscle and potato phosphorylases was completed to provide insight into the nature of the binding mode of oligosaccharide to phosphorylase. The 4-deoxy-oligosaccharides bind competitively with maltopentaose and non-competitively with respect to orthophosphate or G1P in each case, indicating binding in the oligosaccharide binding site. Further, 4DG5 and 4DG6 were found to bind to potato and muscle phosphorylases some 10-40-fold tighter than does maltopentaose. Similar increases in affinity as a consequence of 4-deoxygenation were observed previously for the binding of polymeric glycogen analogues to rabbit muscle phosphorylase [Withers (1990) Carbohydr. Res. 196, 61-73]. (+info)
(2/1525) Simultaneous antisense inhibition of two starch-synthase isoforms in potato tubers leads to accumulation of grossly modified amylopectin.
A chimaeric antisense construct was used to reduce the activities of the two major starch-synthase isoforms in potato tubers simultaneously. A range of reductions in total starch-synthase activities were found in the resulting transgenic plants, up to a maximum of 90% inhibition. The reduction in starch-synthase activity had a profound effect on the starch granules, which became extremely distorted in appearance compared with the control lines. Analysis of the starch indicated that the amounts produced in the tubers, and the amylose content of the starch, were not affected by the reduction in activity. In order to understand why the starch granules were distorted, amylopectin was isolated and the constituent chain lengths analysed. This indicated that the amylopectin was very different to that of the control. It contained more chains of fewer than 15 glucose units in length, and fewer of between 15 and 80 glucose units. In addition, the amylopectin contained more very long chains. Amylopectin from plants repressed in just one of the activities of the two starch-synthase isoforms, which we have reported upon previously, were also analysed. Using a technique different to that used previously we show that both isoforms also affect the amylopectin, but in a way that is different to when both isoforms are repressed together. (+info)
(3/1525) Polynucleotide probes that target a hypervariable region of 16S rRNA genes to identify bacterial isolates corresponding to bands of community fingerprints.
Temperature gradient gel electrophoresis (TGGE) is well suited for fingerprinting bacterial communities by separating PCR-amplified fragments of 16S rRNA genes (16S ribosomal DNA [rDNA]). A strategy was developed and was generally applicable for linking 16S rDNA from community fingerprints to pure culture isolates from the same habitat. For this, digoxigenin-labeled polynucleotide probes were generated by PCR, using bands excised from TGGE community fingerprints as a template, and applied in hybridizations with dot blotted 16S rDNA amplified from bacterial isolates. Within 16S rDNA, the hypervariable V6 region, corresponding to positions 984 to 1047 (Escherichia coli 16S rDNA sequence), which is a subset of the region used for TGGE (positions 968 to 1401), best met the criteria of high phylogenetic variability, required for sufficient probe specificity, and closely flanking conserved priming sites for amplification. Removal of flanking conserved bases was necessary to enable the differentiation of closely related species. This was achieved by 5' exonuclease digestion, terminated by phosphorothioate bonds which were synthesized into the primers. The remaining complementary strand was removed by single-strand-specific digestion. Standard hybridization with truncated probes allowed differentiation of bacteria which differed by only two bases within the probe target site and 1.2% within the complete 16S rDNA. However, a truncated probe, derived from an excised TGGE band of a rhizosphere community, hybridized with three phylogenetically related isolates with identical V6 sequences. Only one of the isolates comigrated with the excised band in TGGE, which was shown to be due to identical sequences, demonstrating the utility of a combined TGGE and V6 probe approach. (+info)
(4/1525) Divinyl ether fatty acid synthesis in late blight-diseased potato leaves.
We conducted a study of the patterns and dynamics of oxidized fatty acid derivatives (oxylipins) in potato leaves infected with the late-blight pathogen Phytophthora infestans. Two 18-carbon divinyl ether fatty acids, colneleic acid and colnelenic acid, accumulated during disease development. To date, there are no reports that such compounds have been detected in higher plants. The divinyl ether fatty acids accumulate more rapidly in potato cultivar Matilda (a cultivar with increased resistance to late blight) than in cultivar Bintje, a susceptible cultivar. Colnelenic acid reached levels of up to approximately 24 nmol (7 microgram) per g fresh weight of tissue in infected leaves. By contrast, levels of members of the jasmonic acid family did not change significantly during pathogenesis. The divinyl ethers also accumulated during the incompatible interaction of tobacco with tobacco mosaic virus. Colneleic and colnelenic acids were found to be inhibitory to P. infestans, suggesting a function in plant defense for divinyl ethers, which are unstable compounds rarely encountered in biological systems. (+info)
(5/1525) The covalent attachment of polyamines to proteins in plant mitochondria.
Plant mitochondria from both potato and mung bean incorporated radioactivity into acid insoluble material when incubated with labelled polyamines (spermine, spermidine and putrescine). Extensive washing of mitochondrial precipitates with trichloroacetic acid and the excess of cold polyamine failed to remove bound radioactivity. Addition of nonradioactive polyamine stopped further incorporation of radioactivity but did not release radioactivity already bound. The radioactivity is incorporated into the membrane fraction. The labelling process has all the features of an enzymatic reaction: it is long lasting with distinctive kinetics peculiar to each polyamine, it is temperature dependent and is affected by N-ethylmaleimide. The latter inhibits the incorporation of putrescine but stimulates the incorporation of spermine and spermidine. Treatment of prelabelled mitochondria with pepsin releases bound radioactivity thus indicating protein to be the ligand for the attachment of polyamines. HPLC of mitochondrial hydrolysates revealed that the radioactivity bound to mitochondria is polyamines; traces of acetyl polyamines were also found in some samples. On autoradiograms of SDS/PAGE gels several radioactive bands of proteins were detected. Protein sequencing of labelled spots from a 2D gel gave a sequence which was 60% identical to catalase. We suggest that the attachment of polyamines to mitochondrial proteins occurs cotranslationally possibly via transglutaminases. (+info)
(6/1525) Conversion of cucumber linoleate 13-lipoxygenase to a 9-lipoxygenating species by site-directed mutagenesis.
Multiple lipoxygenase sequence alignments and structural modeling of the enzyme/substrate interaction of the cucumber lipid body lipoxygenase suggested histidine 608 as the primary determinant of positional specificity. Replacement of this amino acid by a less-space-filling valine altered the positional specificity of this linoleate 13-lipoxygenase in favor of 9-lipoxygenation. These alterations may be explained by the fact that H608V mutation may demask the positively charged guanidino group of R758, which, in turn, may force an inverse head-to-tail orientation of the fatty acid substrate. The R758L+H608V double mutant exhibited a strongly reduced reaction rate and a random positional specificity. Trilinolein, which lacks free carboxylic groups, was oxygenated to the corresponding (13S)-hydro(pero)xy derivatives by both the wild-type enzyme and the linoleate 9-lipoxygenating H608V mutant. These data indicate the complete conversion of a linoleate 13-lipoxygenase to a 9-lipoxygenating species by a single point mutation. It is hypothesized that H608V exchange may alter the orientation of the substrate at the active site and/or its steric configuration in such a way that a stereospecific dioxygen insertion at C-9 may exclusively take place. (+info)
(7/1525) Immunization with potato plants expressing VP60 protein protects against rabbit hemorrhagic disease virus.
The major structural protein VP60 of rabbit hemorrhagic disease virus (RHDV) has been produced in transgenic potato plants under the control of a cauliflower mosaic virus 35S promoter or a modified 35S promoter that included two copies of a strong transcriptional enhancer. Both types of promoters allowed the production of specific mRNAs and detectable levels of recombinant VP60, which were higher for the constructs carrying the modified 35S promoter. Rabbits immunized with leaf extracts from plants carrying this modified 35S promoter showed high anti-VP60 antibody titers and were fully protected against the hemorrhagic disease. (+info)
(8/1525) Differential import of nuclear-encoded tRNAGly isoacceptors into solanum Tuberosum mitochondria.
In potato ( Solanum tuberosum ) mitochondria, about two-thirds of the tRNAs are encoded by the mitochondrial genome and one-third is imported from the cytosol. In the case of tRNAGly isoacceptors, a mitochondrial-encoded tRNAGly(GCC) was found in potato mitochondria, but this is likely to be insufficient to decode the four GGN glycine codons. In this work, we identified a cytosolic tRNAGly(UCC), which was found to be present in S.tuberosum mitochondria. The cytosolic tRNAGly(CCC) was also present in mitochondria, but to a lesser extent. By contrast, the cytosolic tRNAGly(GCC) could not be detected in mitochondria. This selective import of tRNAGly isoacceptors into S. tuberosum mitochondria raises further questions about the mechanism under-lying the specificity of the import process. (+info)