bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE METABOLISM OF MALONATE BY MYCELIAL SUSPENSIONS OF ASPERGILLUS NIGER
Authors: YEOMAN M. M. 
Published: May 2006

SummaryThe effects of malonate on the gaseous exchange and acid metabolism of mycelial suspensions of Aspergillus niger have been studied.Malonate penetrated into the cells of the fungus but did not exert its normal effect as a competitive inhibitor in the TCA cycle, even at high external concentrations. On the contrary it stimulated oxidative catabohsm. Some of the malonate which penetrated was consumed by the fungus and it is inferred that the remainder was stored within the mycelium away from malonate sensitive centres in the cytoplasm.Experiments performed with [2‐14C] malonate have shown that part of the malonate molecule may be utilized in the synthesis of larger structural molecules of the mycelium. Possible pathways of malonate metabolism are discussed in the light of work carried out with other organisms.
ENVIRONMENTAL CONTROL OF CLEISTOGAMY IN PRAIRIE GRASS (BROMUS UNIOLOIDES H.B.K.)
Authors: LANGER R. H. M. , WILSON D. 
Published: May 2006

SummaryIn long days (16 hours) flowers of prairie grass (Bromus unioloides H.B.K.) were almost invariably cleistogamous. In shorter photoperiods chasmogamous flowers were the rule provided soil moisture was high. Chasmogamy was attended by greater anther length but later anthesis than occurred in the cleistogamic condition. Filaments and lodicules were small in cleistogamous flowers and autogamous pollination occurred soon after emergence from the leaf sheath.
THE EFFECT OF CATIONS ON THE GROWTH OF FUNGI
Authors: JONES E. B. G. , JENNINGS D. H. 
Published: May 2006

Summary Dendryphiella salina Pugh has been grown in glucose‐tryptone media differing in their ionic composition. Of the cations which have been added singly to the basal medium, potassium produces the greatest growth in terms of dry weight. Sodium stimulates dry weight production at low concentrations hut inhibits it at high concentrations. Magnesium, calcium and strontium inhibit dry weight production at all concentrations. The inhibition of dry weight production by sodium can be removed by magnesium, calcium, strontium and barium (in order of effectiveness). Under these conditions where growth is inhibited, there is a simple relationship between dry weight and mycelial potassium content. The results are interpreted in terms of the permeability of the hyphae to potassium. A number of other fungi were grown in malt extract media differing in their ionic composition. All the fungi tested have their vegetative growth inhibited by sodium; the concentration causing inhibition can differ widely from species to species. Calcium ions in all cases can reduce the extent of this inhibition. It is clear from this study that a consideration of growth media from the point of view of ionic composition may be very important in interpreting data concerning the growth of fungi.
A NOTE ON THE EFFECT OF THE SHOOT AND ROOT APEX ON SECONDARY THICKENING IN PEA RADICLES
Authors: DIGBY JOHN , WANGERMANN ELISABETH 
Published: May 2006

SummaryThe effects of excision of the root or shoot apices of young pea seedlings and of their replacement with auxin paste, suggest that, (i) cambial activity in the root is stimulated by auxin coming from the shoot; and (ii) auxin from the root apex either does not travel to the older parts of the root or has no effect on cambial activity.
STUDIES IN THE RESPIRATORY AND CARBOHYDRATE METABOLISM OF PLANT TISSUES
Authors: BARKER J. 
Published: May 2006

SummaryEarher evidence that starch is not formed from sugar in plant tissues in the absence of oxygen was confirmed for potatoes. The failure to form starch is attributed to a deficiency of glucose‐1‐phosphate in nitrogen.As in other plant tissues the dissolution of starch to sugar also appeared to be retarded in potatoes in the absence of oxygen. This observation would be explained if starch is degraded by phosphorylase to glucose‐1‐phosphate, which is then converted to sucrose before partial inversion to hexose; the rate of formation of sucrose in nitrogen would be retarded by lack of uridine triphosphate.
CYTOGENETIC STUDIES IN TUBEROUS SOLANUM SPECIES
Authors: MARKS G. E. 
Published: May 2006

SummaryThe results are given of crossing fifteen Central and South American wild Solanum species included in the series Conicibaccata, Demissa, Longipedicellata and Piurana. Nearly all the 210 possible combinations were examined.Pollen tube inhibition occurred in 144 cases. It was affected by the particular species used (e.g. pollen of Conicibaccata species was strongly inhibited), by polyploidy and by the breeding system. It was progressively weaker from 2x×2x to 6x×6x crosses: in crosses of parents differing in chromosome number the probability of inhibition was greater the lower the ploidy of the pollen. The effect of different breeding systems was to introduce reciprocal differences such that pollen inhibition occurred when self‐incompatible species were crossed as females with self‐compatible ones but not in reciprocal crosses. This was so at diploid and tetraploid levels except in crosses involving tetraploid and hexaploid Conicibaccata species where the results were in complete contrast: there are indications that species in this series do not have a simple one‐locus self‐incompatibility system.Post‐fertilization failure occurred in eighteen cases and breakdown was greatest in crosses between parents of different chromosome number.Hybrids were obtained in forty‐seven combinations. Generally, crossability was highest in crosses that gave even polyploid (2x, 4x, 6x) progeny and lowest where uneven polyploids (3x, 5x, 7x) were obtained. All hybrids except two were vigorous.Meiosis is described in thirty‐seven hybrids and the patterns of chromosome association are interpreted in terms of genomic differentiation. It seems that species in series Demissa and Longipedicellata have at least one common genome, which is also present in S. Uiquerrense of series Piurana. Further, it seems that this genome is similar to that of the diploid species S. verrucosum of series Demissa and consequently it is considered as an important link between the Central and South American potatoes. Both S. fendleri and S. stoloniferum of series Longipedicellata have genomic affinities with S. santolallae of series Conicibaccata; this is evidence of another genomic link across the subcontinent. Of the species in series Longipedicellata, S. fendleri and S. stoloniferum are fundamentally similar whereas S. polytrichon is different from both. S. guerreroense and S. iopetalum of series Demissa are very similar and could be considered conspecific. Evidence suggests that S. X semidemissum is probably a hybrid between S. demissum and either S. fendleri or S. stoloniferum.
THE EFFECT OF WIND ON PLANT GROWTH AND SOIL MOISTURE RELATIONS: A RE‐ASSESSMENT
Authors: HUMPHRIES A. W. , ROBERTS F. J. 
Published: May 2006

SummaryThe argument that wind and soil moisture stress induce similar anatomical changes in plant leaves, and that these changes enhance the ability of the plant to restrain water loss, is examined. It is shown that the data presented by Whitehead (1963a) can be explained satisfactorily in terms of induced changes in root distribution and leaf area, without invoking any specialized adaptations for the reduction of water loss.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P. 
Published: May 2006

SummaryCompared to Blue‐white fluorescent light at 15°C, Blue light and low temperature (10°C) resulted in a restriction in the rate of leaf growth due primarily to a sharp fall in specific leaf area with mcreasmg plant size, which was much more pronounced in low temperature. There was scarcely any effect on the leaf weight/total dry weight distribution, hut the leaves had a much higher dry matter content than plants grown in Blue‐white light. In Blue light the unit leaf rate was depressed on an energy basis, but not on a quantum basis. It was also depressed in low temperature. The depression of both unit leaf rate and leafiness resulted in a low relative growth rate in both treatments. The interrelationship of specific leaf area and unit leaf rate did not follow the same pattern as reported previously and this is discussed. The effects attributed to low temperature in field experiments were confirmed.
EXPERIMENTAL TAXONOMY OF SOME BRITISH SPECIES OF THE GENUS DICRANUM
Authors: BRIGGS D. 
Published: May 2006

SUMMARYAn experimental taxonomic study, of a group of closely related species of the moss genus Dicranum, has been carried out. Morphologically the material studied falls into four major taxa–D. bonjeanii, D. fuscescens, D. majus and D. scoparium. Cytologically three of the taxa (only a single chromosome count is available for D. bonjeanii, n = 11) show variation both in the number of ‘A’ chromosomes and in the number of minute bivalents: D. fuscescens, n = 10, 11 (10 + 1 m), 12, 24; D. majus, n = 11, 12, 13 (12 + 2 – 5 m)’D. scoparium, n = 11, 12, 13 (12 + 1 m). These chromosome numbers suggest that each taxon is an aggregate of closely related species, but until more evidence is available it is recommended that four taxa of specific rank be recognized. This procedure receives support from the fact that the different cytotypes are indistinguishable or have not yet received thorough taxonomic study. The intraspecific variation within each of the four species has been examined. Cultivation experiments have shown that certain genotypes exhibit wide phenotypic plasticity, but distinct genotypes of D. fuscescens and D. scoparium are reported. The use of varietal names for these morphologically distinct populations is not recommended, as they cannot be distinguished (except by cultivation experiments) from genotypes which are phenotypically plastic.
THE ROLES OF ADENOSINE TRIPHOSPHATE AND GLUTATHIONE IN THE INHIBITION OF CYCLOSIS BY p‐CHLOROBENZOIC ACID IN ELODEA DENSA
Authors: BRUESKE C. H. , APPLEGATE H. G. 
Published: May 2006

SummaryAdenosine triphosphate (ATP) applied alone accelerated cyclosis in Elodea densa. When applied simultaneously with p‐chlorobenzoic acid (p ClBA), ATP nullified the inhibition of cyclosis by p C1BA, However, when ATP was applied prior to p ClBA, it only partially overcame the inhibiting action of p ClBA. Gltatathione at non‐toxic levels induced acceleration of cyclosis. Exogenous sulphydryl groups, in the form of glutathione, partially reduced p ClBA‐inhibited cyclosis. It was found that p C1BA combined with sulphydryl groups in vitro. Explanations are advanced for the action of ATP and glutathione in the inhibition of cyclosis by p ClBA.
ON THE RELATIONSHIP BETWEEN TRANSPIRATION RATE AND LEAF WATER POTENTIAL
Authors: TINKLIN R. , WEATHERLEY P. E. 
Published: May 2006

SummaryThe aim was to vary the transpiration rate of water culture plants and to measure corresponding values of ΔW, the leaf water potential depression (= DPD = suction force), as well as relative water content (relative turgidity) and stomatal aperture. On the Ohm‐law analogy ΔW and transpiration rate should be linearly related. Ricinus communis plants were placed in a wind tunnel and the transpiration rate was varied by changing the level of the relative humidity of the air stream. With increasing rate of transpiration, ΔW rose steeply to a value of about 6 atmospheres at which it remained virtually constant (Fig. 1). Thus from very low transpiration rates to the highest obtainable, far from ΔW rising linearly with transpiration, there was no response in ΔW and similarly no response in relative water content and stomatal resistance. When transpiration was reduced to zero the leaves still maintained a ΔW of about 3 atmospheres instead of zero, but reasons are put forward for considering this value to present water saturation.The main resistance to water movennent in the plant was shown to reside in the roots. If a leaf was detached from a transpiring plant and allowed to continue transpiration at a similar rate, water being freely supplied to the cut end of the petiole, its ΔW fell from 6 to 3.5 atmospheres (Fig. 3). Thus the resistance must lie‘below’the petiole. Similarly it was shown to lie below the stem.The constancy of leaf ΔW in the face of large changes in flux of water through the roots, implies that the root resistance declines in step with the rise in flux. A simple hydraulic model is presented which would behave in this way.
POLLEN ANALYSIS OF SOME LAKE DEPOSITS NEAR BAMBURGH IN NORTHUMBERLAND
Authors: BARTLEY D. D. 
Published: May 2006

SummaryLate‐glacial and early Post‐glacial deposits have been examined in two areas of Northumberland. All the sites are associated with esker or kame features and the deposits show a succession from lake to bog, two of them under calcareous conditions. The pollen diagrams show a completely unforested Late‐glacial period, probably with a total absence of trees from the higher site. The spread of forest conditions, indicated by the rise in juniper pollen followed by rising values of birch, is shown to have occurred in the middle of zone IV at the lower site but closer to the end of zone IV at the higher site. At the same time attention is drawn to the persistence of Lateglacial conditions into zone IV at the higher site. Also of note are the high percentages of Quercus and very low percentages of Pinus in zone VI. Comparisons are made with previously published diagrams from other areas, especially from Tadcaster in Yorkshire, to illustrate the later date of forest spread in the more northerly localities.The two areas described are situated in Northumberland, one on the coastal plain near Bamburgh at an altitude of 150 ft and the other some 7 miles south at an altitude of 350 ft. The country in which they lie is largely covered by a mantle of glacial drift and both sites are associated with glacial features.
OCHROMONAS OSTREAEFORMIS NOV. SP., A LARGE COMPRESSED CHRYSOMONAD
Authors: SWALE E. M. F. , BELCHER J. H. 
Published: May 2006

Summary Ochromonas ostreaeformis nov. sp. is described from a pool in the English Lake District. The motile cells have been recorded each spring for 4 years, although the formation of cysts was first observed in 1965. Possible factors influencing periodicity are discussed, especially variation in the phosphate phosphorus content of the water, which tended to show an inverse relationship with the number of cells.
EPIDERMAL STRUCTURE AND STOMATAL ONTOGENY IN SOME CELASTRACEAE
Authors: PANT DIVYA DARSHAN , KIDWAI PARVEEN F. 
Published: May 2006

SummaryLeaves of Celastrus paniculatus, C. stylosus, Elaeodendron glaucum, Euonymus japonicus and E. pendulus are essentially hypostomatic, although a few stomata were observed near veins in the upper epidermis of Celastrus paniculatus. Their irregularly orientated stomata show guard cells partly underarched and partly surrounded by a ring of three to eight subsidiary cells. Surface walls of epidermal cells in Euonvmus pendulus show pits whose impressions are also seen in the cuticle.Rehfous (1914) had suggested that the sunken subsidiary cells of Celastrus europaeus, Catha edulis and Euonymus japonicus and four other species of the genus are formed in an unusual manner from segments of the guard cells. Our studies on the contrary indicate that the subsidiary cells in all our plants, including E. japonicus, are typically perigene.Mesophyll of all leaves is armed but the form of midrib bundles varies in different species and to some extent in different regions of the same leaf.
THE DEVELOPMENT OF CHLOROPLASTS AND PHOTOSYNTHETIC ACTIVITIES IN YOUNG BARLEY LEAVES
Authors: RHODES M. J. C. , YEMM E. W. 
Published: May 2006

SummaryCarbon dioxide exchanges in the dark and in the light indicate that photosynthetic activity occurs m young leaves of barley seedlings after about 3 hours illumination under favourable conditions. Activity increases rapidly as chlorophyll is formed in the expanding leaf blade; a compensation point is reached after 30–40 hours and thereafter carbon dioxide assimilation exceeds respiration.Changes in the fine structure of plastids in the young leaves were examined by electron microscopy; some of the chief stages in the development of the lamella system and the differentiation of grana are described. The presence of ribosome‐ and nucleoplasm‐like structures in the chloroplast stroma was indicated.The relationship between the development of chloroplasts and their photosynthetic activity is discussed. It is suggested that the formation of distinctive double membranes between the thylakoids of the grana plays an important part in the structural organization of the pigment system. The action of light on chloroplast development indicates that a primary step in photomorphogenesis is the conversion of protochlorophyllide to chlorophyll. The further extension and development of the lamellar system probably depends upon the biosynthesis of proteins and lipids, closely linked with photosynthesis and operating under the control of nucleic acids.
THE MECHANISM OF ABSORPTION AND UTILIZATION OF PHOSPHATE BY BARLEY PLANTS IN RELATION TO SUBSEQUENT TRANSPORT TO THE SHOOT
Authors: LOUGHMAN B. C. 
Published: May 2006

SummaryAn attempt has been made to distinguish between the process of absorption of orthophosphate by the roots of whole barley plants and that of subsequent transport to the shoot. Such selection can be induced by treatment with growth regulators and inhibitors of specific biochemical stages in phosphorus metabolism. The presence of physiological concentrations of D‐mannose in the root environment has little effect on the overall uptake of radioactive phosphate. The metabolic fate of the absorbed phosphate is, however, severely affected and the ion appears to be reversibly sequestered in the form of hexose monophosphates other than those found to be labelled under normal conditions. Both glucose‐1 ‐phosphate and mannose‐6‐phosphate contain radioactive phosphorus after treatment with mannose. Although overall uptake is relatively unaffected, mannose specifically inhibits further transport of the metabolized phosphate to the shoot and it is concluded that this transport is directly dependent on the prior incorporation of the incoming phosphate into a specific sequence of organic compounds. The results are discussed in relation to the possible mechanisms involved in the separate processes of absorption and transport.
STUDIES IN SEED DORMANCY III. THE EFFECTS OF GIBBERELLIN ON DORMANT SEEDS OFCORYLUS AVELLANAL.
Authors: BRADBEER J. W. , PINFIELD N. J. 
Published: May 2006

SummaryApplication of exogenous gibberellin over a concentration range of 3 × 10−7M‐3 × 10−3M has been found to break hazel seed dormancy, growth of tbe embryonic axis being detectable within a few days of gibberellin application. Metabolic studies of seeds pre‐treated with 3 × 10−4M gibberellin or water have been made during the period prior to the detection of embryonic axis growth. Imbibition of seeds in the presence or absence of gibberellin resulted in an increase of the percentage of incorporated radioactivity found in RNA and protein in both cotyledons and embryonic axes. Data on the incorporation of radioactivity into DNA were not conclusive. Gibberellin pre‐treatment has so far been found to have three clear effects on cotyledonary metabolism, namely, to increase the proportion of [8−14C]adenine incorporated into nucleotide, to reduce the proportion of [2−14C]acetate incorporated into lipid and to increase the activity of isocitrate lyase (Pinfield, 1967).It is suggested that imbibition of dormant hazel seeds initiates the synthesis of RNA and protein, both in cotyledons and embryonic axes. The primary effect of gibberellin action may occur in the cotyledons, where its role in the breaking of seed dormancy may be in the induction of increased levels of activity of certain enzymes, particularly those concerned with the mobilization of the cotyledonary oil reserves. It is not clear as to what part, if any, the gibberellin stimulated adenine nucleotide synthesis plays in the breaking of hazel seed dormancy.
EFFECT OF GIBBERELLIC ACID ON THE GROWTH AND ANATOMY OF COLEUS BLUMEI, ANTIRRHINUM MAJUS AND SALVIA SPLENDENS
Authors: BOSTRACK JACK M. , STRUCKMEYER B. ESTHER 
Published: May 2006

SummaryPlants of Coleus blumei (Coleus), Antirrhinum majus (snapdragon) and Salvia splendens (Salvia) exhibited three common responses to foliar applications of 50 mg/1 aqueous solution of gibherellic acid (GA); elongation of the internodes, hyponasty and chlorosis. Elongation of subapical internodes was a result primarily of cell division in both Antirrhinum majus and Salvia splendens. Gibberellic acid at 500 mg/1 caused less elongation of the sub‐apical region than at 50 mg/1 and 100 mg/1 in S. splendens. Treated plants had a smaller stem diameter and more xylem parenchyma. Coleus blumei cuttings showed reduced rooting when treated with 50 mg/1 GA.
THE ROLE OF CARBON DIOXIDE, LIGHT AND NITRATE IN THE SYNTHESIS AND DEGRADATION OF NITRATE REDUCTASE IN LEAVES OF PERILLA FRUTESCENS
Authors: KANNANGARA C. G. , WOOLHOUSE H. W. 
Published: May 2006

SummaryNitrate reductase in leaves of Perilla is an adaptive enzyme, the induction of which is shown to require carbon dioxide, light and nitrate. Following illumination of a leaf containing nitrate, the activity of the enzyme rises to a maximum after 6 hours and then begins to decline again. However, the enzyme activity is not entirely lost in such a leaf, provided that a supply of nitrate is maintained. When leaves containing nitrate reductase are placed in darkness, the enzyme breaks down at an approximately linear rate, which is influenced by temperature and by the age of the leaf. Synthesis of the enzyme appears to depend on active photosynthesis, since, when a leaf containing nitrate is illuminated in a CO2‐free atmosphere, no detectable enzyme is formed. When a leaf possessing nitrate reductase activity is illuminated in a CO2‐free atmosphere, the enzyme activity falls at a similar rate to that which occurs when the leaf is darkened. Thus it is reasonable to conclude that synthesis of the enzyme is dependent upon both light and CO2 and that a continuous breakdown of the enzyme is taking place even during a period of net synthesis. Using this information it becomes possible to estimate and compare the capacity of leaves of different ages to s)nthesize nitrate reductase.
RATES OF INCORPORATION OF LABEL FROM d‐[14C]GLUCOSE INTO DIFFERENT REGIONS OF THE ROOT‐TIP OF MAIZE (ZEA MAYS L.)
Authors: ROBERTS R. M. , BUTT V. S. 
Published: May 2006

SummaryWhen D‐[U‐14C]glucose was supplied externally to root‐tips of maize, uptake was linear with time, but saturation rates of incorporation into the ethanol‐xylene‐water insoluble fractions were not achieved simultaneously by the different tissues. The more deeply lying cortex and pith required longer periods to reach steady state rates than the outer regions of the root. Thus, after 30 minutes, autoradiographs showed label to be present only in the epidermis, outer cortex and marginal cells of the cap but, after 4 hours, each of the regions appeared to have reached saturation. It could not be determined how far these differences in incorporation rates were due to higher synthetic activity in the outer tissues and hence a more rapid equilibration of labelled compound with the precursor pools, or to the penetration of the tracer compound to successive tissues of the root.