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1.
A program for predicting significant RNA secondary structures 总被引:1,自引:0,他引:1
Le Shu-yun; Chen Jih-Hsiang; Currey Kathleen M.; Maizel Jacob V. Jr 《Bioinformatics (Oxford, England)》1988,4(1):153-159
We describe a program for the analysis of RNA secondary structure.There are two new features in this program. (i) To get vectorspeeds on a vector pipeline machine (such as Cray X-MP/24) wehave vectorized the secondary structure dynamic algorithm. (ii)The statistical significance of a locally optimalsecondary structure is assessed by a Monte Carlo method. Theresults can be depicted graphically including profiles of thestability of local secondary structures and the distributionof the potentially significant secondary structures in the RNAmolecules. Interesting regions where both the potentially significantsecondary structures and open structures (single-strandedcoils) occur can be identified by the plots mentioned above.Furthermore, the speed of the vectorized code allows repeatedMonte Carlo simulations with different overlapping window sizes.Thus, the optimal size of the significant secondary structureoccurring in the interesting region can be assessed by repeatingthe Monte Carlo simulation. The power of the program is demonstratedin the analysis of local secondary structures of human T-celllymphotrophic virus type III (HIV).
Received on August 17, 1987; accepted on January 5, 1988 相似文献
2.
Healthy tomato plants were shown to contain high levels of RNA-dependentRNA polymerase activity, mainly in a soluble form,but also partly in a bound form. The boundenzyme was solublized by EDTA treatment. Both forms of enzymewere partially purified and characterized. The ion and pH optimaof the two forms were identical at all stages of purification.Both enzymes exhibited uridylyl transferase activity, whichmade up 35 per cent of total incorporation. Infection with tobacco mosaic virus (TMV) increased activityof soluble enzyme by twofold, and of solubilizedbound enzyme by less than twofold. Uridylyl transferaseactivity was also increased by infection. General propertiesof the enzymes were unaltered by infection with one exception:in the presence of TMV RNA as added template, the solubleenzyme from infected plants incorporated 3H-UTP into productswith the electrophoretic properties and RNase sensitivitiesexpected for replicative form and replicative intermediate ofTMV. Soluble enzyme from healthy plants, and solublized bound enzyme from either healthy or infectedplants did not synthesize these products. The soluble and solubilized boundenzymes behaved differently on ion-exchange chromatography.Under the conditions used, soluble enzyme didnot bind to the column, whereas solublized boundenzyme did. No differences in chromatographic behaviour werefound between enzymes from healthy or infected plants. Withboth soluble and solublized boundenzymes, the uridylyl transferase activity co-chromatographedwith the polymerase activity. Tomato, Lycopersicon esculentum, RNA-dependent RNA polymerase, tobacco mosaic virus, tobacco mosaic virus replicase 相似文献
3.
We present a new algorithm for the display of RNA secondarystructure. The principle of the algorithm is entirely differentfrom those currently in use in that our algorithm is objectoriented while currrent algorithms are procedural.The circular RNA molecule of chrysanthemum stunt viroid wasused as input data for demonstrating the operation of the program.The major interest of this method will be found in its potentialuse in simulation graphics of RNA folding processes.
Received on October 9, 1986; accepted on February 17, 1987 相似文献
4.
Base-pair probability profiles of RNA secondary structures 总被引:7,自引:0,他引:7
Dynamic programming algorithms are able to predict optimal andsuboptimal secondary structures of RNA. These suboptimal oralternative secondary structures are important for the biologicalfunction of RNA. The distribution of secondary structures presentin solution is governed by the thermodynamic equilibrium betweenthe different structures. An algorithm is presented which approximatesthe total partition function by a Boltzmannweighted summationof optimal and suboptimal secondary structures at several temperatures.A clear representation of the equilibrium distribution of secondarystructures is derived from a two-dimensional bonding matrixwith basepairing probability as the third dimension.The temperature dependence of the equilibrium distribution givesthe denaturation behavior of the nucleic acid, which may becompared to experimental optical denaturation curves after correctionfor the hypochromicities of the different base-pairs. Similarly,temperature-induced mobility changes detected in temperature-gradientgel electrophoresis of nucleic acids may be interpreted on thebasis of the temperature dependence of the equilibrium distribution.Results are illustrated for natural circular and synthetic linearpotato spindle tuber viroid RNA respectively, and are comparedto experimental data. 相似文献
5.
Investigations revealed that the anatomy of the primary radicularroot of yam bean (Pachyrhizus erosus L.) was typically dicotyledonousexcept that the xylem was not completely developed centripetally.Most of the roots had tetrarch xylem, although a few triarchand pentarch roots were also observed. In both tuberous andnon-tuberous roots, secondary thickening occurred by the formationof the meristematic vascular cambium which formed secondarytissues in a normal fashion. Subsequently, tuberization wasinitiated in the secondary xylem by the development of anomaloussecondary cambia from parenchyma cells surroundingvessel elements. Anomalous secondary cambia alsodeveloped from parenchyma cells not associated with vessels.Subsequently, anomalous tertiary cambia differentiatedfrom tissues produced by the anomalous secondarycambia. Activities of these anomalous cambia resulted in theproduction of parenchyma storage cells and were chiefly responsiblefor the growth of the mature tuber. Pachyrhizus erosus L., yam bean, tuberous root, anatomy, anomalous secondary cambia, anomalous tertiary cambia, centripetal xylem development 相似文献
6.
Primary and Secondary Induction Requirements for Flowering of Contrasting European Varieties of Lolium perenne 总被引:1,自引:0,他引:1
The flowering requirements of six European varieties of Loliumperenne L. were studied in controlled environments. In experimentson primary induction, flowering was recorded after transferto long days (LD) in a greenhouse at 1224°C. In experimentson secondary induction, primary induction was first accomplishedat 6°C/10 h daylength for 12 weeks. When evaluated by the50% heading criterion, the requirement for duration of primaryinduction at 6°C/8 h daylength was <3 weeks in Mediterranean,56 weeks in Central European and 78 weeks in Scandinavianvarieties. While Veyo (Italy) flowered profuselyregardless of temperature or daylength during primary induction,critical temperatures for primary induction in SD and LD were15 and 11°C in Baca (Czech Republic) and 11and 7°C in Falster (Denmark). The criticalphotoperiod for secondary induction at 15°C ranged from12 h in Veyo and 14 h in Baca to16.5 h in Falster and 17.5 in Kleppe(Norway). The critical number of LD cycles varied correspondingly.While the Central and North European varieties required fewerLD cycles for 50% heading at 18 than at 12°C, Veyoshowed the opposite response. It is concluded that the requirementsfor both primary and secondary induction of Lolium perenne increasewith increasing latitude of origin of the germplasm. In oneexperiment, 3987% of the inflorescences came from tillersthat were not visible on transfer from primary to secondaryinduction, thus it is also concluded that there is no juvenilestage in tillers of Lolium perenne. Copyright 2000 Annals ofBotany Company Daylength, flowering, juvenility, perennial ryegrass (Lolium perenne L.), primary induction, secondary induction, temperature, varieties, vernalization 相似文献
7.
A Macintosh Hypertalk program (Hypercard stack)for use in phylogenetic comparative analysis of RNA structureis described. The program identifies covariations and compensatorychanges in RNA sequence alignments, for use in the constructionof secondary structure models or the identification of tertiaryinteractions. The results of an analysis are presented eitheras a list of positions in the alignment which covary, or asa 2-dimensional matrix in which potential helices in the secondarystructure appear as diagonal patterns.
Received on January 7, 1991; accepted on March 19, 1991 相似文献
8.
The advantages of nucleotide-resolution models over atomic-resolutionand cylinder models of large RNA structure are discussed, anda toolkit of RNA substructures for use in building pencilmodels is described. Prefabricated elements from the toolkitcan be used to quickly assemble complex RNA structure modelsfor the visualization of known RNA structures, or for exploringpotential tertiary structure configurations based on secondarystructure and other information. 相似文献
9.
Plant Morphology: The Historic Concepts of Wilhelm Troll, Walter Zimmermann and Agnes Arber 总被引:1,自引:1,他引:0
Recent molecular systematic and developmental genetic findingshave drawn attention to plant morphology as a discipline dealingwith the phenotypic appearance of plant forms. However, sincedifferent terms and conceptual frameworks have evolved overa period of more than 200 years, it is reasonable to surveythe history of plant morphology; this is the first of two paperswith this aim. The present paper deals with the historic conceptsof Troll, Zimmermann and Arber, which are based on Goethe'smorphology. Included are contrasting views of unity anddiversity, position and process, and morphologyand phylogeny, which, in part, are basic views of currentplant morphology, phylogenetic systematics and developmentalgenetics. Wilhelm Troll established the type conceptand the principle of variable proportions. Hehas provided the most comprehensive overview of the positionalrelations of plant forms. Agnes Arber started from the universaldynamics of life and attempted to describe all structures asprocesses. She paid attention to repetitive branching,differential growth, and parallelism.As a result she has recently been rediscovered by developmentalbotanists. Walter Zimmermann rejected any metaphysical influenceon plant form and instead called for objective procedures. Hewas mainly interested in phylogenetic character transformationand the reconstruction of genealogical lines.Guided by the example of flower-like inflorescences, a futurepaper will deal with functional and developmental constraintsinfluencing plant forms. Recent morphological concepts (trialectical,continuum/fuzzy, processmorphology) will be discussed and related to currentmorphological and developmental genetic research. Copyright2001 Annals of Botany Company Plant form, plant morphology, natural philosophy, homology, phylogeny, Goethe, Troll, Arber, Zimmermann, typology, character transformation, differential growth, complementarity 相似文献
10.
11.
KANAMORI-FUKUDA IKUKO; ASHIHARA HIROSHI; KOMAMINE ATSUSHI 《Journal of experimental botany》1981,32(1):69-78
Marked changes in the activity of the de novoand salvage pathways of pyrimidine biosynthesisduring growth of Vinca rosea cells in a batch suspension culturewere observed. The activity of these pathways was investigated by determiningthe contribution of 14C of [2-14Cluracil, 12-14Cluridine. and[6-14Clorotate to the cell constituents and by measuring theactivity of the several enzymes of these pathways. During the lag phase of the culture, uracil- anduridine-salvage pathways made the predominantcontribution to nucleotide biosynthesis, but, following theinitiation of cell division, the de novo pathwayfor nucleotide biosynthesis operated appreciably. These results suggest that nucleotide synthesis during cellgrowth in a suspension culture can be divided into two stages:a turnover stage, during the lag phase of cellgrowth, and a true biosynthetic stage, which isinitiated in the cell division phase. 相似文献
12.
p. 186, right column line 11 27.2 KBq change to37.2 MBq p. 187, left column line 8 27.2 KBq change to37.2 MBq line 10 13.6 KBq change to 18.6 MBq line 11 13.6 KBq change to 18.6 MBq line 21 89% change to 80% right column line 24 CLC-NH4 change to CLC-NH2 P. 189, Table 1 appeared incorrectly: it should appear as indicated. 相似文献
13.
Subjects from Britain and America were tested on their skillat applying the taste adjectives sweet, sour,salty, and bitter to clearly distinguishablesolutions of sucrose, citric acid, NaCl and quinine sulphate,respectively. The main error that occurred was calling citricacid bitter while the tendency to call quininesulphate sour was not so common; this is the wellknown sour-bitter confusion. A sour-salty confusion was alsonoted as well as a tendency to call citric acid sweet.All these confusions were rectified by mere definition usingstandards. Skill at applying taste adjectives was not alwaysfound to be consistent over time. More errors occurred at lowersolution concentrations, even though stimuli were clearly distinguishable;indistinguishability of stimuli may account for some confusionsin other studies.
*Present address: Department of Psychology, University of Bristol,Bristol BS8 1HH, England. 相似文献
14.
In the early days of the Human Interactome Project, ameeting was organized.... Perhaps, a few years from now,newspapers will describe in those terms how straightforwardit was to plan the large-scale mapping of protein interactionsin human and other model organisms. Scientists attending thesecond Cold Spring Harbor Laboratory/Wellcome Trust symposiumon Interactome Networks1 know well that thingsare not that easy. Important scientific, technical and sociologicalissues remain before the Human Interactome Projectcan be considered on its way. But things 相似文献
15.
Angioy Anna M.; Barbarossa Iole Tomassini; Liscia Anna; Usai Maria L.; Orru Sergio; Muroni Patrizia; Crnjar Roberto 《Chemical senses》1990,15(2):145-150
Stimulation of single largest or marginallabellar chemosensilla can evoke ipsi- and contralateral labellarlobe spreading responses in Protophormia. Measurements of reflexlatencies indicate that the response is triggered by messagescoming from the largest ipsilateral chemosensilla.Input from the marginal chemosensilla would playa role in maintaining the already triggered response. 相似文献
16.
A program to facilitate the design of oligonucleotide primnershas been devised. Olga is written in draft ANSI standard Cand makes use of the implementation of Digital Research GEM(Graphics Environment Manager) on the Atari ST Olga is specificallysuited to the polymnerase chain reaction (PCR) allowing si analysisof two primer sequences. The advantage of Olga is that it providesin one program analyses for direct repeats, secondary structuresand primer dimerization as well as several useful finishingtools for workers engaged in PCR optimization and oligonucleotidesyntheses. 相似文献
17.
The effects of the foliar application of phytocidal concentrationsof 2-methyl-4-chlorophenoxyacetic acid (MCPA) on change in totaldry weight, and in available carbohydrate (starch,total and reducing sugars), totalnitrogen, phosphorus, potassium, calcium, and magnesium of topsand roots of tomato plants have been followed over a periodof 14 days following spraying. There were two main treatmentsnutrient(nutrient supply to roots continued after spraying) and water(distilled water only supplied to roots after spraying) andwater (distilled water only supplied to rootsafter spraying)the sub-treatments consisting of MCPAversus no-MCPA for each of the main treatments.Twelve different times of sampling were used. In analysing the present data, the quantity residualdry weight (total dry weight less available carbohydrate),which was originally introduced by Mason and Maskell as a basisof reference for analyses of plant organs in short-period experimentsnot involving appreciable growth, has been used as an estimateof the permanent structure of plant growth. This new use ofthe residual dry weight basis has brought outimportant features which were obscured when the data were leftin their primary form (as percentages of total dry weight oramounts per plant). Growth, as measured by increase in residual dry weight,was greatly inhibited by 2-methyl-4-chlorophenoxyacetic acidshortly after spraying, in both the presence and the absenceof nutrient. In the presence of 2-methyl-4-chlorophenoxyacetic acid, netassimilation rate (estimated as rate of increase in total dryweight per gram residual dry weight of the tops)was greatly diminished while uptake of total nitrogen and ofP2O5 (estimated as increase in total nitrogen or of P2O5 ofthe whole plant per day per 1 g. residual dry weightof the roots) appeared to undergo a similar but much smallerdiminution. It seemed probable, however, that in the presenceof MCPA a larger proportion of the carbohydrate actually formedwas utilized for synthesis of aminoacids and protein. In the plant as a whole there was no evidence of actual depletionof available carbohydrate as a result of MCPAtreatment, this fraction showing a steady increase in all treatmentsthroughout the experiment. The rate of increase was, however,much reduced by MCPA treatment. The tops presentedmuch the same picture as the whole plant, but for the rootsthe situation was quite different. While the roots of the no-MCPAplants and also of the MCPA-water plants showeda steady increase in available carbohydrate, those of the MCPA-nutrientplants rose only very slightly (from the initial value of 8mg. per plant to about 10 mg.) during the first 2 days, andthen in the next 2 days declined to a value (about 6 mg.) belowthe initial and remained at this low level for the rest of theexperiment. It is suggested that the phytocidal effect of 2-methyl-4-chlorophenoxyaceticacid in the presence of nutrient may be due to depletion ofthe available carbohydrate supplies in the roots,which is shown to be brought about, in part, by reduced transportfrom the tops, and partly by the relatively greater utilizationof the carbohydrate present. These results offer an explanationfor the facts that plants showing vigorous growth are more easilykilled by MCPA and that perennial plants, particularly thosewith storage tissues in their roots, are more resistant. Further,they suggest the useful practical application that MCPA treatmentshould be given when the carbohydrate reserves of the rootsare at a minimum. For perennial plants, conditions might beexpected to be optimal for the application of MCPA in late spring,at a time when the first flush of growth is slowingdown and before any appreciable new reserves of carbohydratehave been accumulated. It was also shown that 2-methyl-4-chlorophenoxyacetic acid preventedthe net synthesis of starch, but still permitted an appreciablenet formation of sucrose. 2-methyl-4-chlorophenoxyacetic acid appeared to have no effecton the uptake of potassium, calcium, or of magnesium. The lackof effect on potassium is contrasted with the previous observationby Rhodes, Templeman, and Thruston (1950) that sub-lethal concentrationsof MCPA, applied over a relatively long period to the rootsof tomato plants, specifically depressed the uptake of potassium. 相似文献
18.
Mycorrhizal Response of Two Tomato Genotypes Relates to their Ability to Acquire and Utilize Phosphorus 总被引:3,自引:0,他引:3
The purpose of this study was to determine how a plant's responseto colonization by mycorrhizal fungi relates to its abilityto acquire and utilize phosphorus for growth and reproduction.Two tomato genotypes previously found to be either responsive(LA1709) or unresponsive (large cherry)to mycorrhizal colonization during early vegetative growth wereexamined in detail. Plants were grown at four levels of addedphosphate or with mycorrhizal inoculum. Vegetative and reproductivegrowth, phosphorus uptake and root length density were measuredduring the course of plant development. Mycorrhizal symbiosissignificantly increased above-ground dry mass, root length,phosphorus content and yield under low phosphorus conditionsin LA1709, while it had less effect on these characteristicsin large cherry. When uninfected, however, LA1709grew and reproduced poorly unless high amounts of phosphoruswere added to the soil, while large cherry grewwell under very low phosphorus conditions. This was becauselarge cherry had significantly higher root lengthdensities than LA1709, enabling plants from thisgenotype to explore more soil volume and acquire greater amountsof phosphorus when grown without mycorrhizal fungi in low phosphorussoil. Large cherry also had higher phosphorususe efficiency and allocated a greater proportion of phosphorusto reproduction when uninfected than LA1709. Itappears traits that affect a plant's ability to acquire andutilize phosphorus efficiently for growth and reproduction canalso affect its response to mycorrhizal colonization in tomato.Copyright1998 Annals of Botany Company. Tomato,Lycopersicon esculentum,mycorrhiza,Glomus etunicatum,phosphorus, reproduction, lifespan. 相似文献
19.
1. Horseradish roots reach a stage of ripeness to regenerateat the age of 12 months, when secondary thickening hasbegun, a phellogen has formed, and the primary cortex has beenshed; provided that they are then detached from the parent plant. 2. New primordia arise (as is already known) only in associationwith the scars of lateral roots; but they are produced, notas previously believed from a callus, but individually as organizedmeristems whose cells are derived only from the phellogen ofthe main root. 3. The primordia appear to be undetermined (indifferent)in nature; their subsequent differentiation into buds or rootsis described. 相似文献
20.
Effect of large- and of small-bodied zooplankton on phytoplankton in a eutrophic oxbow 总被引:1,自引:0,他引:1
Grigorszky Istvaan; Nagy Saandor; Tooth Albert; Maathee Csaba; Muuller Zoltaan; Borbeely Gyoorgy 《Journal of plankton research》1998,20(10):1989-1995
Macrozooplankton and microzooplankton effects on the phytoplanktonwere measured in situ in a eutrophic lake. Indigenous phytoplanktonwere incubated for 5 days in 301 mesocosms with either the macro-and microzooplankton (complete), microzooplankton only (micro)or no zooplankton (none). Changes in phytoplankton biovolumewere investigated. Rotifer densities became significantly higherin the micro treatment than in the completeand none treatments. Total algal biovolume changedlittle in the complete and nonetreatments, but increased significantly in the microtreatment. The results suggest that macrozooplankton (Daphniamagna) suppressed it and microzooplankton (Keratella cochlearis)enhanced it. They had opposite net effects on the phytoplankton.Suppression of microzooplankton by Daphnia probably had an indirectnegative effect on the phytoplankton. 相似文献