bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF 2‐DEOXY‐d‐GLUCOSE ON THE GROWTH AND METABOLISM OF PROTOTHECA ZOPFII KRÜGER
Authors: RANA M. S. , CASSELTON P. J. 
Published: May 2006

SummarySome effects of 2‐deoxy‐D‐glucose (2‐DG) on the growth and metabolism of Prototheca zopfii Krüger are described. 2‐DG inhibits the rate of growth of the alga in medium containing glucose as carbon source and inhibition is more marked when fructose replaces glucose. Growth in medium containing acetate is not affected by the presence of 2‐DG. The addition of 2‐DG to carbohydrate starved cells, in addition to glucose, fructose or acetate, causes a marked increase in oxygen uptake; this is attributed to assimilation of 2‐DG. 2‐DG‐6‐phosphate inhibits the in vitro activity of glucose‐6‐phosphate dehydrogenase (E.G. 1.1.1.49) and experiments with radioactive glucose suggest that 2‐DG inhibits the oxidative pentose phosphate pathway of glucose metabolism in intact cells. Other effects of 2‐DG include inhibitions of glycogen‐UDP glucosyltransferase activity in vitro and of fermentation in vivo.
ORIGINS OF THE AMINO ACIDS IN PODS AND SEEDS OF VICIA FABA L.
Authors: KIPPS A. E. , BOULTER D. 
Published: May 2006

SummaryBloom node leaves and pods of 25‐35‐day‐old fruits of Vicia faba L. var. Triple White, were allowed to photosynthesize in 14CO2 and the distribution of label in pod and seed amino acids determined by autoradiography.The pod was shown to export carbon to the seeds chiefly as aspartic acid. The leaf contributed sugars and serine directly and many other amino acids after metabolism of precursor compounds in the pod. The seed was apparently capable of amino acid interconversion and synthesis. Both leaf and pod donated carbon to seed protein, the leaf providing about ten times as much total seed carbon as did the pod.
SINK LIMITATION AND IMPORT OF ASSIMILATE INTO MATURE LEAVES
Authors: THROWER S. L. 
Published: May 2006

SummaryLabelled assimilate can be caused to move into a mature leaf which does not normally import by a technique of sink modification. This consists of darkening the chosen sink leaf, removing other foliar sinks by defoliation and decapitation, and suppressing the activity of the root by chilling.
THE RICE SHOOT IN RELATION TO OXYGEN SUPPLY AND ROOT GROWTH IN SEEDLINGS GERMINATING UNDER WATER
Authors: KORDAN H. A. 
Published: May 2006

SummaryGerminated rice seedlings completely submerged under water do not show normal root growth and vertical shoot growth unless the water is aerated. From this observation, and earlier ones, it is concluded that rice seedlings in stagnant water in darkness will not develop normally unless a supply of oxygen can be received via the shoot.
THE LOCALIZATION OF AN INSOLUBLE INTERMEDIATE IN GLUCOSE PRODUCTION IN THE LICHEN PELTIGERA POLYDACTYLA
Authors: PEVELING ELISABETH , HILL DAVID J. 
Published: May 2006

SummaryIn the lichen Peltigera polydactyla the localization of an insoluble intermediate in the production of glucose during photosynthesis by the algae was detected by high resolution autoradiography.
CRYPTOGEAL GERMINATION AND OTHER SEEDLING ADAPTIONS TO THE BURNING OF VEGETATION IN SAVANNA REGIONS: THE ORIGIN OF THE PYROPHYTIC HABIT
Authors: JACKSON GEORGE 
Published: May 2006

SummaryFollowing a study of Butyrospermum paradoxum (Jackson, 1968), observations on the germination of several savanna shrubs and trees have been made. Plumule burying (cryptogeal germination) occurs in a number of species in widely separated families. It is suggested that this feature has arisen as a result of evolution in a habitat that has long been subject to annual burning. The problem remains as to whether the fires are to be regarded as natural or as due to the widespread use of burning by man.
RESPONSE TO BORON DEFICIENCY: A COMPARISON WITH RESPONSES PRODUCED BY CHEMICAL METHODS OF RETARDING ROOT ELONGATION
Authors: ROBERTSON G. A. , LOUGHMAN B. C. 
Published: May 2006

SummarySeedlings of Vicia faba L. were subjected to treatments with IAA, 2,4‐D, tri‐iodobenzoic acid, kinetin, 2‐chloroethanephosphonic acid as well as those designed to prevent normal division in the primary meristem. Where division was inhibited with colchicine, trifluralin, dinitramine or surgical excision, a radial expansion of the root tip occurred. However, the anatomical aspects of the responses and their effects on phosphate absorption and incorporation were quite distinct from the effects produced in both boron deficiency and excess auxin treatments. Kinetin gave similar effects to mitotic inhibitors. The possibility that boron deficiency is associated with an excess level of endogenous auxin was examined. The effects of boron deficiency were compared with those associated with the presence of excess auxin.
DIFFERING EFFECTS OF WATER DEFICIT ON NET PHOTOSYNTHESIS OF INTACT AND EXCISED SORGHUM LEAVES
Authors: PASTERNAK D. , WILSON G. L. 
Published: May 2006

SummaryNet photosynthesis and leaf resistances in turgid sorghum leaves were compared with those of intact leaves which underwent relatively slow loss of water, and with excised leaves which lost water rapidly. Reduced net photosynthesis in intact leaves can largely be accounted for by stomatal closure; this is not so for excised leaves. Stomata of excised leaves both started and completed closure at much lower leaf water contents than those of attached leaves.
GROWTH PHASES IN THE LIFE OF A LICHEN THALLUS
Authors: ARMSTRONG R. A. 
Published: May 2006

SummaryThe growth rates of thalli of foliose saxicolous lichens before and after the linear phase of growth were measured in 1973. Changes in the radial growth rate (measured as mm/year) with thallus size in the prelinear phase (thalli less than approximately 1.5 cm in diameter) were consistent with the hypothesis that early growth of these lichens is logarithmic. When growth in the prelinear phase was measured as a relative growth rate (measured as cm2/cm2/year) there was a rapid rise in growth rate until about 3 mm thallus diameter and then a decline in growth rate. The radial growth rate of non‐fragmenting thalli when compared with fragmenting thalli at different stages of fragmentation suggested that the radial growth rate does not significantly decline after fragmentation of the thallus. This result is not consistent with a postlinear phase in the radial growth of a lichen thallus.
THE INFLUENCE OF ENVIRONMENT ON LEAF WAX DEVELOPMENT IN BRASSICA OLERACEA VAR. GEMMIFERA
Authors: BAKER E. A. 
Published: May 2006

SummaryThe influence of environmental conditions on the epicuticular waxes of the normal and four mutant forms of brussels sprout (Brassica oleracea var. gemmifera) has been studied. An increase in radiant energy rate, a decrease in humidity or a decrease in temperature induces the largest deposits of wax. Environmental conditions have only a limited effect on the compositions of the waxes of the normal and mutant lines but modify the size, configuration and distribution of the surface wax structures. A mechanism for the transport and subsequent organization of the wax on the plant surface is discussed.
PLANT MACROFOSSILS FROM LATE‐DEVENSIAN DEPOSITS AT NANT FFRANCON, CAERNARVONSHIRE
Authors: BURROWS C. J. 
Published: May 2006

SummaryThe occurrence of plant macrofossils in Late‐Devensian sediments from the valley of Nant Ffrancon is described. The range of fossils present and their distribution relative to changes in the sedimentary sequence allow an interpretation to be made of the Late‐Devensian environments of the area. A time of barren landscape, as ice retreated from the valley and adjacent areas, was followed by a brief period of vegetation development in which some woody plants were present, then a brief return to colder conditions and devegetation. There then occurred a longer interval during which varied vegetation developed, beginning primarily with herbaceous communities and culminating in a period of predominance of birch woodland and scrub, which probably formed mosaics with herbaceous communities. Finally, there was a return to barren conditions as climate again became colder. No absolute dating is yet available for these events but, provisionally, they may be correlated with phases in the glacial history of the area and with changes recorded by pollen analysis by other workers.
THE VEGETATION HISTORY FROM 6000 b.p. TO PRESENT OF WILSONS PROMONTORY, VICTORIA, AUSTRALIA
Authors: HOPE G. S. 
Published: May 2006

SummaryPollen analysis of three sites on Wilsons Promontory provides a vegetation record from 6000 b.p. to the present day. No extensive changes in the vegetation have been found over this time period, but local and regional variations in the extent of communities may imply small climatic changes. Moister conditions than at present seem to have prevailed earlier than 4500 b.p., followed by a drier phase till less than 2000 b.p., when an increase in moisture gave conditions similar to those of today. Some evidence exists to support the theory of a relatively steady sea level close to the present level over the last 6000 years along the western Wilsons Promontory coastline.
AN ULTRASTRUCTURAL STUDY OF PIT CONNECTIONS AND PERCURRENT PROLIFERATIONS IN THE RED ALGA NEMALION HELMINTHOIDES (VELL. IN WITH.) BATT.
Authors: DUCKETT J. G. , BUCHANAN J. S. , PEEL M. C. , MARTIN M. T. 
Published: May 2006

SUMMARY Nemalion helminthoides exhibits considerable diversity in pit connection morphology. Their diameter ranges from 1.5 μm between fusion cells and the gametophyte, down to 0.3 μm on spermatial branches. Highly asymmetrical pit connections occur in the septa at the base of hairs. The plugs between the vegetative cells of the cortex possess a central groove, but this is absent from those in the medulla and on spermatial branches. The plug cap is three layered except at the base of hairs where only the innermost stratum is present. This last layer also extends as the border to the sides of the plugs separating them from the cell membrane which is continuous between adjacent cells. Granular material occurs in the cytoplasm adjacent to the plug caps, and peripheral to this is a region lacking ribosomes.Up to four successive spermatia and up to twelve hairs may be produced by percurrent proliferations in Nemalion. Absence of pit connections in the walls remaining after spermatium discharge suggests that pit connection displacement may be important in the liberation of the male gametes. Pit connections may also have a mechanical role in anchoring the cytoplasm and providing cross‐bridges between adjacent cells.
THE LATE‐GLACIAL DEPOSITS AT GLANLLYNNAU, CAERNARVONSHIRE
Authors: SIMPKINS KATHLEEN 
Published: May 2006

SUMMARYLate‐glacial deposits from two kettleholes at Glanllynnau, Caernarvonshire, are described and the lithological units and their stratigraphical relationships are discussed. The pollen analytical procedure and the method of zonation are outlined. The characteristics of each pollen assemblage zone are described, and a correlation is made between pollen zones and lithostratigraphic units: the environmental implications are stated. An attempt is made to determine the relative pollen concentration within each pollen zone/lithological type, in order to assess the relevance of statements deduced from the Blelham Bog comparison of absolute and percentage pollen data (Pennington and Bonny, 1970). The pollen record at Glanllynnau is interpreted in terms of (i) the terrestrial vegetation history, and (ii) the aquatic vegetation and palaeoecology of the sites. The significance of the Glanllynnau 14C dates is examined and a brief comparison is made with similarly dated lithostratigraphic horizons at other British sites. The inconsistency between the coleopteran and floral evidence for the beginning of the Late‐glacial interstadial at Glanllynnau is noted, but no explanation can be given. The status of the Bölling–Alleröd interval is also considered.
THE EFFECTS OF FLOWERING AND FRUIT FORMATION ON THE SUPPLY OF PHOTOSYNTHETIC ASSIMILATES TO THE NODULES OF PISUM SATIVUM L. IN RELATION TO THE FIXATION OF NITROGEN
Authors: LAWRIE ANN C. , WHEELER C. T. 
Published: May 2006

SUMMARYBoth nitrogenase activity and the accumulation of 14C‐labelled photosynthates in the nodules of pea plants in nitrogen‐free culture reached maxima shortly before flowering and fruit development. During the period from flowering to fruiting, nitrogenase activity and accumulation of 14C‐photosynthates in the nodules declined by 60%, whereas the photosynthesis of the plant doubled. Studies of the translocation of the photosynthates within the plant during this period suggested that this might be due to an increase from 17% to 50% of the photosynthates which accumulated at the shoot apex. Consistent increases in nitrogenase activity over the 24 hours following removal of the shoot apex were only achieved in fruiting plants, however, although vegetative, flowering and fruiting plants all showed increased accumulation of photosynthates in the nodules. Continuous removal of flowers as they were formed over a 2‐week period resulted in a large increase in accumulation of photosynthates in the nodules and in nitrogenase activity.Other factors which may regulate nitrogenase activity in these plants are discussed.
ARBUSCULAR MYCORRHIZAS IN PLANTS COLONIZING COAL WASTES IN SCOTLAND
Authors: DAFT M. J. , NICOLSON T. H. 
Published: May 2006

SUMMARYAll the grasses and nearly all the dicotyledonous plants growing on three coal tips in Scotland were infected by vesicular‐arbuscular mycorrhizal fungi. Infection levels ranged from 20 to 90%. Three main types of fungal endophytes were identified, two being Endogone spp. and one with very narrow hyphae. Mixed infections were present in some plants and there was some evidence that the endophytes occurred in different areas of the tips. The ecological importance of the mycorrhizas in these habitats is discussed.
PHOTOSYNTHETIC 14C FIXATION BY THE LICHEN UMBILICARIA MUHLENBERGH (ACH) TUCK. FOLLOWING SHORT EXPOSURES TO AQUEOUS SULPHUR DIOXIDE
Authors: PUCKETT K. J. , RICHARDSON D. H. S. , FLORA W. P. , NIEBOER E. 
Published: May 2006

SUMMARYPhotosynthetic 14C fixation by the lichen Umbilicaria muhlenbergii was reduced within 15 min of exposure to aqueous sulphur dioxide (75 ppm, pH 3.0), but no changes were observed in the spectra of extracted chlorophyll pigments. Exposed lichen samples maintained under moist, sulphur‐dioxide‐free conditions in the light for 24 h were able to fix 14C at pre‐exposure levels. Partial recovery was observed when samples were kept under moist dark conditions but little when the lichens were maintained dry in the light or dark. When samples were exposed repeatedly to sulphur dioxide, but with a recovery period between each exposure, they gradually lost the ability to regain their photosynthetic activity. After the third cycle of exposure and recovery, little 14C fixation was observed while changes in the spectra of extracted pigments was evident. Increased potassium levels were found in the medium during exposure. These levels reverted to control values after a suitable recovery period. In vitro studies showed that 10‐20 ppm sulphur dioxide was found to deactivate both staphylococcal nuclease and lysozyme. Possible explanations as to the mode of SO2 toxicity on lichen metabolism and suggestions as to recovery mechanisms are fully discussed.
SOME EFFECTS OF SULPHITE ON PHOTOSYNTHESIS IN LICHENS
Authors: HILL D. J. 
Published: May 2006

SUMMARYDetails of the effect of sulphite on H14CO3‐ fixation in the light were studied. The reduction of fixation by sulphite was rapid, taking place within 30 min of contact with the lichen. Parmelia physodes recovered in 24 h from almost total reduction of fixation caused by 1 h treatment with 0.4 mM sulphite but Usnea sp. did not. Studies with [35S] sulphite indicated that sulphite was taken up nonlinearly with time and that it was bound to protein. Algae isolated from Usnea sp., Parmelia physodes and Lecanora conizaeoides were similar in their response to sulphite, although the intact lichen L. conizaeoides is known to be more resistant. L. conizaeoides did not seem to be resistant to sulphite by causing rapid oxidation of sulphite to sulphate. There was no marked effect of temperature on the concentration of sulphite required to reduce fixation in Usnea sp.
PSEUDOGAMY IN THE GENUS POTENTILLA L.
Authors: GOSWAMI D. ACHARYA , MATFIELD B. 
Published: May 2006

SUMMARYThree closely related pseudogamic species, Potentilla argentea L., P. recta L. and P. cf. hirta L. were pollinated by other species of Potentilla and observations were made on pollen germination, pollen tube growth, ovule development and seed set. The three pseudogamic species stimulated seed set in each other, but no seeds were formed after pollination by ten other species although well‐developed pollen tubes were observed in a number of cases. The offspring from the successful pollinations were mainly maternal but a few deviant individuals were also produced.
FACTORS INFLUENCING NITRATE REDUCTION IN SOYBEAN FOLIAGE
Authors: TINGEY DAVID T. , FITES ROGER C. , BAHARSJAH JUSTIKA 
Published: May 2006

SummaryOptimum conditions for the in vivo nitrate reductase assay in soybean (Glycine max (L.) Merr.) foliage were determined. The in vivo and in vitro nitrate reductase assays correlated highly but exhibited differential decay rates with increasing leaf age. Nitrate reduction could be coupled to the oxidation of either frustose‐I,6‐diphosphate or 6‐phosphogluconate. Compounds, such as glucose, 2,4‐dinitrophenol or phosphate, which stimulate glycolysis also stimulated nitrate reduction. Citrate stimulated nitrate reduction in young expanding leaves but was inhibitory in mature, expanded leaves. Caffeic acid was inhibitory in young but not in mature leaves.
EFFECT OF WATER STRESS UPON ENDOGENOUS ETHYLENE LEVELS IN VICIA FABA
Authors: EL‐BELTAGY A. S. , HALL M. A. 
Published: May 2006

SummaryConditions of drought or waterlogging lead to greatly increased internal ethylene concentrations in Vida faba L. These increases appear to be due partly to decreased diffusion and partly to increased synthesis and are superimposed on normal diurnal fluctuations in internal ethylene concentration. The higher concentrations observed are correlated with a reduction in growth rate and increased leaf and flower abscission and senescence. The role of ethylene in the mediation of developmental responses to water stress is discussed.
VERTICAL AND RADIAL MOVEMENT OF AUXIN IN YOUNG SYCAMORE PLANTS
Authors: ZAMSKI E. , WAREING P. F. 
Published: May 2006

SummaryThree‐year‐old active and dormant sycamore plants were treated with labelled auxin solution applied to the outer bark or the inner xylem in order to establish the rate of transport of radioactive materials in longitudinal and radial directions.The velocity of auxin transport in the vertical direction within the bark was 0.4–0.6 cm/h in active plants and 0.1–0.2 cm/h in dormant plants. It was found that auxin can move from bark to xylem or vice versa. Autoradiography shows that radial transport takes place within the rays. Auxin is translocated from xylem to bark at a higher rate and in greater amounts than in the reverse direction both in active and dormant plants, but the radial transport from bark to xylem in dormant plants is greater than in active plants. The slower the vertical transport within the bark the faster the radial one in the centripetal direction. On the other hand, the rate of the transport in the centrifugal direction was found to be slower for dormant plants. A higher level of auxin may be maintained in the cambium of active plants because of the centrifugal movement of auxin within the xylem.
THE EFFECT OF MICRO‐ORGANISMS ON THE ABSORPTION OF MANGANESE BY PLANTS
Authors: BARBER D. A. , LEE R. B. 
Published: May 2006

SummaryThe uptake of manganese by barley plants grown in solution culture is stimulated in the presence of micro‐organisms, irrespective of whether they originated as casual laboratory contaminants or as rhizosphere micro‐organisms in the soil. The microbial effect is mediated by a watersoluble substance but neither its identity nor its mode of action has yet been established.When manganese is supplied as EDTA chelates these appear to be broken down at or near the surface of the roots and this process is accelerated in the presence of micro‐organisms. Under the conditions of these experiments EDTA was absorbed by the plants much less readily than manganese.
KARYOTYPE VARIATION AND EVOLUTION IN THE VICIA SATIV A AGGREGATE
Authors: HOLLINGS E. , STACE C. A. 
Published: May 2006

SummaryPrevious accounts of the chromosome complement of members of the Vicia sativa aggregate and of V. lathyroides are reviewed, and the results of a new survey of 122 strains belonging to four taxa presented. Significant variation in chromosome morphology within each of the three segregates of V. sativa agg. was found; in V. segetalis both 2n= 10 and 2n= 12 was encountered among the cultivated material. In wild V. lathyroides also both 2n = 10 and 2n= 12 populations were found. Reasons are given for considering that this group of vetches shows a reductional evolutionary series 2n= 14 2n= 12 2n= 10, and the inter‐relationships of these three karyotypes are discussed. In addition two counts of 2w = 14 are reported for wild Turkish strains of V. amphicarpa.
POPULATION VARIATION AND TAXONOMY IN ARMERIA MARITIMA WITH SPECIAL REFERENCE TO HEAVY‐METAL‐TOLERANT POPULATIONS
Authors: LEFÈBVRE C. 
Published: May 2006

SummaryPopulations of Armeria maritima growing in various ecological situations were studied in northwestern and central Europe. In their typical ecogeographical areas populations of ssp. maritima, ssp. elongata and ssp. alpina are well differentiated. These three subspecies are nevertheless interconnected by transitional populations related to ssp. intermedia and ssp. halleri s.1. Populations from mines of heavy metals (ssp. halleri s.1.) show endemic frequencies of morphological traits from one site to another. This variation which can occur in neighbouring areas is random and may be due to genetic drift associated with the founder principle. Mixed populations of ssp. intermedia originated from hybridization between ssp. maritima and ssp. elongata in their overlapping area (west part of the Baltic). Morphological differences between populations are not correlated with sterility barriers so that there is discordance between morphological units and biosystematical units. Taxonomic treatments of the group of metal‐tolerant populations is misleading.
PLASTID DEVELOPMENT IN PRIMARY LEAVES OF PHASEOLUS VULGARIS
Authors: BRADBEER J. W. , IRELAND H. M. M. , SMITH J. W. , REST J. , EDGE H. J. W. 
Published: May 2006

SummaryBy the use of light and electron microscopy a quantitative investigation has been made of plastid membrane formation in the primary leaves of bean plants, during germination and growth in the dark. From 4 to 14 days of dark growth there was an eleven‐fold increase in cell number and a twenty‐six‐fold increase in plastid number per leaf. Formation of plastid envelope membrane between 6 and 14 days of dark growth amounted to 98 cm2 of membrane per leaf while the corresponding formation of internal plastid membrane was 272 cm2 per leaf. This internal plastid membrane appears to be formed, at least during the early stages of leaf growth, by the invagination of the inner envelope membrane. When a substantial amount of the thylakoid membrane has accumulated in the plastid a condensation process takes place to give the pro‐lamellar body, which is a structure composed of branching membrane tubules. Calculations based on the dimensions of these tubules have established that 1 μ3 of prolamellar body contains about 44 μ2 of membrane.Dark‐grown leaves have been found to contain all of the enzymes of the photosynthetic carbon cycle. The course of development, during dark growth, has been determined for the activities of eight enzymes of the photosynthetic carbon cycle and for two enzymes of the cytoplasm.