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1.
Extracrts of the shoot tips of normal and frenchedtobacco plants were chemically separated into acidic, neutral,and basic ethersoluble fractions. On chromatograms ofthese, some plant growth regulators were assayed using the Avenacoleoptile section extension test. The acidic auxins and an acids and a neutral growth inhibitorwere found. One auxin, with the samew RF value as indole-3-aceticacid, was four times more concentrated on normal as in frenchedplants. No differences could be established between the twotypes of plants in regard to other growth regulators detected. It is argued that the symptoms of the physiological diseasefrenching could be explained in terms of a auxindeficiency. 相似文献
2.
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
3.
Effect of Source of Nitrogen on the Growth of Fiskeby Soya Bean: the Carbon Economy of Whole Plants 总被引:1,自引:0,他引:1
Fiskeby V soya bean was grown from seed germination to seedmaturation with two contrasting patterns of nitrogen metabolism:either wholly dependent on dinitrogen fixation, or with an abundantsupply of nitrate nitrogen, but lacking root nodules. The carbonand nitrogen economies of the plants were assessed at frequentintervals by measurements of photosynthesis, shoot and rootrespiration, and organic and inorganic nitrogen contents. Plantsfixing atmospheric nitrogen assimilated only 2530 percent as much nitrogen as equivalent plants given nitrate nitrogen:c. 40 per cent of the nitrogen of nitrate plantswas assimilated after dinitrogen fixation had ceased in nodulatedplants. The rates of photosynthesis and respiration of the shootsof soya bean were not markedly affected by source of nitrogen;in contrast, the roots of nodulated plants respiredtwice as rapidly during intense dinitrogen fixation as thoseof nitrate plants. The magnitude of this respiratoryburden was calculated to increase the daily whole-plant respiratory loss of assimilate by 1015 per cent over thatof plants receiving abundant nitrate. It is concluded that nodulatedplants grew more slowly than nitrate plants inthese experiments for at least two reasons: firstly, the symbioticassociation fixed insufficient nitrogen for optimum growth and,secondly, the assimila tion of the nitrogen which was fixedin the root nodules was more energy-demanding in terms of assimilatethan that of plants which assimilated nitrogen by reducing nitratein their leaves. 相似文献
4.
《Journal of Molluscan Studies》1965,36(6):323
WARBURG, M. R., 1965. On the water economy of some Australianland snails. Proc. malac. Soc. Lond. 36, 297305. Page 298: second line from bottom, should read within± 1 µg for Themapupa. Page 300: Fig. 2 legend, should read Evaporative waterloss from Sinumelon remissum (a), Pleuroxia sp. (b) and Themapupaadelaidae (c). Page 300: section 4 heading, should read Continuous curvesfor water loss. Page 301: second line, for Fig. 9 read Fig.3. Page 301: Table 1, last line, for 0.120024 read0.12024. Present address: Israel Institute for Biological Research, Ness-Ziona,Israel. 相似文献
5.
SINGH N; SINGH S N; SRIVASTAVA K; YUNUS M; AHMAD K. J; SHARMA S C.; SHARGA A N 《Annals of botany》1990,65(1):41-44
Five Gladiolus cultivars, namely Aldebaran, BrightEye, Illusion, Manisha andManmohan, were exposed to 1 and 2 µg l1sulphur dioxide to test their relative-sensitivity toleranceto the pollutant Plants were fumigated experimentally for 2h daily Foliar injury symptoms were observed first in Manishafollowed by Aldebaran and Illusionat the higher dose Photosynthetic pigments and leaf extractpH were significantly decreased, particularly in Manishaand Illusion Overall disturbances in the plantmetabolism due to SO2 treatment led to retarded growth of plants,as evident from decreased shoot length and phytomass valuesThe order of sensitivity of the five Gladiolus cultivars toSO2 was as follows, with the greatest first Manisha, Illusion,Aldebaran, Bright Eye, Manmohan Cultivars, Gladiolus, sensitivity, sulphur dioxide, tolerance 相似文献
6.
A number of programs are described for the development and evaluationof probabilistic identification matrices for use with computer-assistedidentification. The program BEST reads an initial matrix ofper cent probabilities for all the binary characters examinedduring a cluster analysis and determines the most useful setof tests for distinguishing taxa in the matrix. Program RESORTcreates from the initial matrix an identification matrix inwhich the order of the tests may be different or the numberof tests reduced. A printed version of a matrix can be producedby MATPRJNT, which creates tables giving the per cent probabilityof a positive test result and the test results presented as, v and + dependingon a user-specified threshold. Program IDSC evaluates an identificationmatrix by calculating the best identification score for eachtaxon in the matrix using the expected result for each test.The programs were written in FORTRAN 77 and can be run on anymicrocomputer using the PC/MS-DOS operating system.
Received on April 27, 1990; accepted on November 5, 1990 相似文献
7.
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
8.
Mitochondria from 1-day-old bean cotyledons were isolated bya slow isolation procedure involving a wash andby a rapid procedure. The mitochondria isolatedby the rapid procedure were more tightly coupledthan those isolated by the slow procedure. Anexogenous supply of cytochrome c or NAD was shown to improvethe activity of mitochondria isolated by the slowprocedure, but not those isolated by the rapidprocedure. The phosphorylative abilities of the latter weremuch greater than the former and were retained for longer periods.It was found that there was a leakage of NAD out of the mitochondria. 相似文献
9.
A system for pattern matching applications on biosequences 总被引:5,自引:0,他引:5
ANREP is a system for finding matches to patterns composed of(i) spacing constraints called spacers, and (ii)approximate matches to motifs that are, recursively,patterns composed of atomic symbols. A user specifiessuch patterns via a declarative, free-format and strongly typedlanguage called A that is presented here in a tutorial stylethrough a series of progressively more complex examples. Thesample patterns are for protein and DNA sequences, the applicationdomain for which ANREP wos specifically created. ANREP providesa unified framework for almost all previously proposed biosequencepatterns and extends them by providing approximate matching,a feature heretofore unavailable except for the limited caseof individual sequences. The pemformance of ANREP is discussedand an appendix gives concise specification of syntax and semantics.A portable C softwore package implementing ANREP is availablevia anonymous remote file transfer. 相似文献
10.
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
11.
12.
Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of B extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of Bin lupin pods was 5001,500 times more potent than thatof inhibitor ß in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of A of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of B. Mature podsof virus-infected plants again yielded moreA,but also 2? times more B than pods of healthyplants. Healthy pods yielded more A than virus-infectedpods, and there was no difference in X. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. A accelerated abscission when applied proximally,and delayed or prevented it when applied distally. Bstrongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances A and B. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism. 相似文献
13.
The Nitrogen Content of Plants and the Self-thinning Rule of Plant Ecology: A Test of the Core-skin Hypothesis 总被引:3,自引:0,他引:3
The core-skin hypothesis postulates that secondarilythickened plants behave energetically as an inert corecovered by an active skin, the skinbeing two-imensional, the core three-dimensional.This would explain the self-thinning or3/2 rule of plant ecology, that is, the tendencyfor log (dry weight per plant) and log (number of plants perunit area) to progress along a straight line relationship, withslope = 3/2. The hypothesis was tested as follows. Plant nitrogen contentwas used as an estimate of the mass of skin perplant, and dry weight as an estimate of the mass of the core.As plants mature the slope of the relationship between y = log(mass of nitrogen per plant) and x = log (mass of dry matterper plant) is expected to decline from an initial value of 1.0towards a final value of 0.66. The intercept of the relationshipis expected to reflect the intrinsic content of skinper unit of core. Genotypic variation in thisparameter should cause genotypic differences in the maximumattainable yield of biomass per unit area. The expectations were investigated by fitting the function y= p+qx+r exp x to 30 sets of data on plant nitrogencontent, plant weight and time in 18 different vegetables. Simplelinear regressions of y on x were fitted to more limited setsof data on weights and nitrogen contents of mature trees. Theexpectations were, with some minor exceptions, confirmed. Nitrogen, yield, plant competition, self-thinning 相似文献
14.
15.
Water Relations of Beetroot Seed Germination: I. Microbial Factors, with Special Reference to Laboratory Germination 总被引:1,自引:0,他引:1
Laboratory test results obtained with two seed lots of the cultivarDetroit Globe have shown: (1) 8 ml of water in a 9-cm diameterpetri-dish are excessive for good germination of 25 two-seededclusters, either natural or rubbed, which germinatewell in 3 ml of water. (2) Some of this depression in germinationis due to a direct effect of the excessive water-supply.(3) But the benefit from either surface sterilization or theuse of aureomycin, a bacteriostatic antibiotic, indicates thatsome of the depression of germination in the presence of excesswater is the result of bacterial colonization of the seed clusters.The excess water effect can also be mitigated by preliminaryrubbing of the seed clusters, presumably by removalof some of the bacterial inoculum, provided that the rubbingprocess itself does not injure the seeds. (4) There is goodevidence that the bacteria depress the germination of the seedsby competing with them for oxygen. (5) The effect of the bacterialpopulation on germination in excess water can be aggravatedby preliminary washing of the seed clusters. This is probablydue to a delicate equilibrium between the bacteria and at leastpart of the fungal population of the seeds which when retainedmay produce an antibacterial substance; but the water-solublephenolic acids contained in the seed clusters may also be involved:at high concentrations these inhibit germination, but they mayalso depress bacterial activity, even at lower than germination-inhibitingconcentrations. (6) Fungicides aggravate the depression of germinationon over-wet paper in the laboratory, but are of value in thefield. (7) There is evidence that different limiting factorsmay operate on different seed lots and care must be taken notto generalize from results obtained from a limited number ofseed samples. 相似文献
16.
SHEWRY P. R.; FIELD J. M.; KIRKMAN M. A.; FAULKS AUDREY J.; MIFLIN B. J. 《Journal of experimental botany》1980,31(2):393-407
This paper reports further studies on the characteristics ofthe storage protein fraction (hordein) of barley. Hordein consistsof two groups of polypeptides (termed B and C)coded by two separate but linked loci. Whereas the Cpolypeptides are readily soluble and extracted in 60% (v/v)ethanol at room temperature, the B group is moresoluble in, and therefore more efficiently extracted by, 50%(v/v) propan-1-ol or 45% (v/v) propan-2-ol at elevated temperaturesand in the presence of 2-mercaptoethanol. However, the mostefficient conditions for hordein extraction (50% propan-1-ol+ 2% (v/v) 2-mercaptoethanol at 60 °C) also extract somecontaminating non-hordein polypeptides resulting in an apparentlyincreased lysine content of the hordein fraction. Amino acid analysis of the purified B and Chordein groups shows that, whereas C hordein containsmore glutamate + glutamine, proline, and phenylalanine thanB hordein, it contains only traces of lysine andsulphur amino acids in contrast to B hordein whichcontains 0·5% lysine 0·6% methionine, and 2·5%cysteine. Equilibrium sedimentation analyses carried out on the purifiedB and C groups indicates that thepreparations were reasonably monodisperse with molecular weightsof approximately 32 000 and 52 000 respectively. These valuesare considerably lower than those previously determined by SDS-PAGE. 相似文献
17.
Naturally occurring gibberellin-like substances possessing acidic,basic, and neutral properties were detected, by paper partitionchromatography, in ethanolic extracts of tomato seed and ofetiolated seedlings after 72 and 116 hours' growth. Dwarf maizemutants of the d-1 and d-5 types, Meteor pea seedlingsand young Potentate tomato plants were used asbioassay material. Hydrolysis of seed and seedling proteinsby ficin in phosphate buffer, pH 6.2, after removal of ethanol-solublesubstances, liberated more and different boundgibberellin-like substances. It is suggested that protein hydrolysisduring germination is an important means of liberating thesesubstances at different stages of seedling development. Acidic substances were present in all the extracts prepared,but in general two with Rfs 0.25 and 0.55 in iso-propanol: ammonia:water : : 10:1:1 v/v were differentiated on d-2 and d-5 maizerespectively. Neutral substances in dry seed extracts chromatographedin the same solvent, had Rfs of 0.05, 0.35, and 0.95 and thesewere found only in the ethanolic (free) extracts.They were active on d-1 and d-2 maize and Meteorpea. Basic gibberellin-like substances with Rfs of 0.05 and0.35 were found in free extracts of both dry seedand etiolated seedlings after 116 hours' growth which were activeon d-2 maize only. Two others with Rfs 0.45 and 0.95 were extractedfrom seedlings after 72 hours' growth and these were activeon young Potentate tomato plants. It is suggested that certain gibberellin-like substances, capableof reversing dwarfism in test plants, may be responsible formorphogenetic or other responses not involving stem extensionin the parent species. Changes were found in the levels of gibberellin-likesubstances but there was no evidence of changes in levels ofseed inhibitors relative to seed growth substances. 相似文献
18.
The back cover of this book states that contrary to theclaims of the nativists, research shows that man-dispersed speciesincrease biological diversity, benefit ecosystems, and act asan important force for healing the planet. This is anuncompromising statement, and David Theodoropoulos divides hisdevelopment of the arguments supporting this statement intothree parts. Part I (Chapters 16) is Nature, Dispersaland Reaction. Part II (Chapters 7 and 8) is Why?Psychology, Politics and Pseudoscience. Part III (Chapters911) is Humanity and Diversity. There isalso an Introduction including a summary of findingsand An outline for a new theory of anthropogenic dispersal, 相似文献
19.
Diurnal laminar reorientation was followed in solar-trackingleaves of Lavatera cretica L. under simulated conditions. Asimulated sun was moved over the lamina in a 180?arc in the vertical plane of the mid-vein, at an angular velocityof 15? h1 in a regime of 12-h photoperiods. In one groupof plants the petioles of the experimental leaves were arrangedto face sunrise, while in the other they werearranged to face sunset. At sunrise,the laminae in both groups, which were inclined towards theanticipated direction of sunrise, changed theirelevation towards the rising sun, resulting inprogressive reduction in the angle of incidence (AI) of lighton the laminar surface (AI= differential between laminar andsolar elevation). As a result, laminar and solarelevation converged, and laminar reorientation gradually ceased,until the solar elevation had passed the normalto the laminar surface (AI=0?). laminar reorientation was thenresumed, but its direction was reversed to follow the directionof solar reorientation. During most of the remainingday, laminar elevation (LE) trailed that of thesun by an average of 11?-14?. Laminar reorientationthen anticipated sunset by starting to slow down60 to 90min in advance. During the 12-h dark period, the laminareoriented towards the anticipated direction of the subsequentsunrise. The time-course of nocturnal reorientationwas qualitatively different in the two groups of experimentalplants. The time-course of diurnal phototropism under naturaland simulated conditions is analysed and compared and differencesand similarities between them are discussed. Key words: Diurnal phototropism, solar-tracking, vectorial excitation 相似文献
20.
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