bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE CONTRIBUTION OF CURRENT PHOTOSYNTHESIS TO GROWTH AND DEVELOPMENT IN THE TULIP DURING FLOWERING
Authors: HO L. C. , REES A. R. 
Published: May 2006

SUMMARYLeaves of tulip plants were treated with 14CO2 on three occasions during flowering, one week apart–at the bud stage, at early flowering and when flowers were fully opened. The amount of 14C fixation was examined 5 min after a pulse application of 14CO2 and the organic carbon and 14C contents of various organs were examined 24 h later.Total carbon in the mother‐bulb scales fell over 14 days to only 40% of the initial value, whilst that of all new organs increased by 71%. A negligible amount of 14C was recovered from scales or from roots. The 14C recovered from the flower and stem accounted for 83% of 14C exported from leaves at the early flowering stage. The total carbon content of the daughter bulbs increased uniformly with time but the 14C recovered from the daughter bulbs was initially smail but increased to 59% of the exported 14C when the flower was fully opened.The imported 14C in flower and stem was mainly recovered from the soluble and residual (non‐starch, insoluble) fractions, whilst that in daughter bulbs was from the soluble and starch fractions. The amount of 14C lost by respiration fell from 20% to 10% of initial 14C uptake over the 3‐week period.
FURTHER OBSERVATIONS ON STOMATAL RESPONSES TO SODIUM AZIDE
Authors: PEMADASA M. A. , JEYASEELAN K. 
Published: May 2006

SUMMARYStomatal responses to different concentrations and durations of azide treatment were investigated by microscopic examination of epidermal strips of Stachytarpheta indica fixed in absolute ethanol. Both opening on illumination and closure on darkening of turgid leaves were suppressed by azide, which also arrested starch hydrolysis and accumulation of potassium in the guard cells in light, and starch synthesis and disappearance of stomatal potassium in the dark. The magnitude of the azide effect is a function of concentration and duration of the treatment. Carbon dioxide‐free air was effective in partly reversing the azide effect. It is concluded that azide suppresses stomatal movement partly by disturbing the carbon dioxide balance in the leaf and partly by hindering starch metabolism and transfer of potassium ions across the guard cell membranes.
AN INVESTIGATION OF THE FUNCTIONAL PHLOEM IN WILLOW
Authors: LAWTON JUNE R. 
Published: May 2006

SUMMARYDistribution of dyes, 14C, and the position of aphid stylets in the phloem of rooted 2 year cuttings and a standing tree of Salix fragilis correlate with callose formation on the sieve plates. It is suggested that the region concerned with translocation is that portion of the phloem near the cambium, where callose is formed on the sieve plates. During July this region is within the first lignified fibre band where there are sieve tubes in all stages of development, from recently differentiated to those in which definitive callose covers the sieve plate. The majority of sieve tubes in the area have open sieve pores with callose between the pores, and with sparse fibrillar or vesicular cytoplasm.
THE ECOLOGICAL SIGNIFICANCE OF ‘HALOPHYTES’ IN THE DEVENSIAN FLORA
Authors: ADAM PAUL 
Published: May 2006

SUMMARYThe botanical evidence for the presence of inland saline areas during the Devensian (last glacial) stage is considered. It is suggested that this evidence need not be interpreted as demonstrating the existence of saline conditions. Aspects of the present day ecology of some of the species regarded as halophytic are discussed and alternative hypotheses to explain their occurrence under full glacial conditions are advanced.
STOMATAL RESPONSES TO 2,4‐DINITROPHENOL
Authors: PEMADASA M. A. , KORALEGE S. 
Published: May 2006

SUMMARYThe effect of 2,4‐dinitrophenol (DNP) on stomatal movement in excised, turgid leaves of Stachytarpheta indica was investigated by microscopic examination of the abaxial epidermis. DNP prevented wide opening on illumination and closure in the dark, and affected concurrent changes in stomatal starch and potassium concentration in the guard cells. Carbon dioxide‐free air failed to reverse the DNP effect. The effect of DNP is attributed largely to its inhibition of hydrolysis of stomatal starch and of active transport of potassium ions to and from the guard cells. The possibility that DNP affects the energy supply for stomatal movements through its inhibition of oxidative phosphorylation is briefly discussed.
ULTRASTRUCTURE OF TACTILE PAPILLAE ON TENDRILS OF ECCREMOCARPUS SCABER R. ET P.
Authors: JUNKER STEFFEN 
Published: May 2006

SUMMARYThe ultrastructure of the tactile papillae on tendrils of Eccremocarpus scaber was studied. The protoplast is highly vacuolated. Ovoid osmiophilic bodies are regularly scattered between cell wall and plasmalemma. The cytoplasm is rich in organelles, especially endoplasmic reticulum, dictyosomes, golgi vesicles and mitochondria. Chloroplasts contain poorly developed grana. Abundant plasmodesmata were observed in the walls between tactile papillae and epidermal cells and in the anticlinal epidermal cell walls. The possible functional significance of these structures is discussed.
THE ROLE OF ANABAENA IN THE AZOLLA‐ANABAENA SYMBIOSIS
Authors: HILL D. J. 
Published: May 2006

SUMMARYThe Anabaena cells in Azolla undergo a developmental pattern of differentiation parallel to that of the fern. At the apex, the algal cells are small and rapidly dividing, and do not fix atmospheric nitrogen. After the leaf cavities are colonized, the algal cells form heterocysts, fix nitrogen and the vegetative cells enlarge considerably. The synchrony between the two partners appears to break down under certain environmental conditions leading to alga‐free fern fronds.
THE SIGNIFICANCE OF ACIDIC LICHEN SUBSTANCES IN THE ESTIMATION OF CHLOROPHYLL AND PHAEOPHYTIN IN LICHENS
Authors: BROWN D. H. , HOOKER T. N. 
Published: May 2006

SUMMARYAcidic lichen substances are shown to be responsible for degrading extracted chlorophyll to phaeophytins in certain species of lichens and a method is proposed for eliminating this error during pigment extraction. The proposed extraction and measurement method is applied to lichens that have been maintained in either dry or deep frozen conditions.
POLLEN SPECTRA FROM PLIOCENE CRAG AT ORFORD, SUFFOLK
Authors: ANDREW R. , WEST R. G. 
Published: May 2006

SUMMARYA pollen diagram from the pre‐Pleistocene marine sediments near Orford, Suffolk, shows the presence of a forest flora, mainly coniferous, with a number of exotic genera of Eastern Asian/North American affinity, including Sequoia‐type, Sciadopitys and Taxodium‐type. It is suggested that this pollen assemblage may be Brunssumian (Lower Pliocene) in age.
THE EFFECT OF COTYLEDONS ON CHLOROPLAST DEVELOPMENT IN PRIMARY LEAVES OF PHASEOLUS VULGARIS
Authors: WHATLEY JEAN M. 
Published: May 2006

SummaryWhen seeds of Phaseolus vulgaris are allowed to develop normally in fruits on the mature plant, the plastids in the primary leaves of the embryo within the seed do not develop into mature chloroplasts. However, when the developing seeds are removed from the parent plants, the cotyledons detached, and the embryonic axes grown on agar, primary leaf plastids differentiate into mature chloroplasts within 7 days. In embryos with attached cotyledons, and similarly grown for a week on agar, plastids fail to differentiate.In primary leaves of dormant seeds allowed to germinate on agar, lamellar development begins earlier in seedlings from which the cotyledons have been removed than in those with attached cotyledons, although there is no significant difference between the two groups of seedlings in the time required for the chloroplasts to become fully mature. Plastid differentiation in primary leaves of developing seeds of Phaseolus therefore appears to be inhibited initially by the presence of the cotyledons. This inhibitory effect apparently declines during seed ripening and dormancy.
COMPARTMENTALIZATION IN THE COTYLEDONARY CELLS OF PHASEOLUS VULGARIS L. SEEDS: A DIFFERENTIAL SEDIMENTATION STUDY
Authors: PUSZTAI A. , CROY R. R. D. , GRANT G. , WATT W. B. 
Published: May 2006

SummaryThe appearance and the yield of sedimentable organelles from the cotyledons of Phaseolus vulgaris L. were measured with respect to the influence of the method of homogenization, the choice of dry or imbibed seeds, and the composition and the concentration of the homogenization medium. Sucrose, (0.2–0.8 M), the addition of Mg2+ (2 × 10−4M) or EDTA (3 × 10−3M) or the replacement of sucrose with mannitol made little difference to the average size distribution or the amount recovered of the 21 000 gav× 10 min pelleted organelles, the main protein body‐containing fraction of the homogenate. Slicing the imbibed seeds with a razor blade or by a mechanical rotary cutter combined with a short extraction was the gentlest and the most efficient method for the production of organelles. Cell homogenates were fractionated on the basis of size by differential sedimentation into several subcellular fractions. These included a residue, starch particles (300 g× 10 min), a main protein body fraction (21 000 gav× 10 min), 38 000 gav× 60 min pellets, 78 000 gav× 240 min pellets and a final supernatant. The activity in these fractions of several catabolic enzymes was measured. Most of the activity of the acidic nucleases, amylases, the BAPA‐ase and a substantial part of the acidic phosphatase and the cathepsin A‐type enzyme(s) were found in the supernatant, while no specific DNA‐ase was found in these seeds. Protein bodies contained some of the trypsin inhibitors and most (if not all) of the lectins and Glycoprotein II. Most of the endopeptidase (azoproteinase) activity of the cotyledons appeared to be tightly bound to the cell walls or to other insoluble structural elements. Protein bodies and other intracellular organelles had very little autolytic activity and, thus, the main storage proteins of the seed were not degraded during the first 4 days of germination.
EXPERIMENTAL ALTERATION OF SOIL MICROBIAL POPULATIONS FOR STUDYING EFFECTS ON HIGHER PLANT INTERACTIONS
Authors: NEWMAN E. I. , CAMPBELL R. , ROVIRA A. D. 
Published: May 2006

SummaryIn order to investigate how soil microorganisms can affect the balance between higher plants growing together, it would be desirable to have soils similar in chemical properties but differing microbially, and to be able to maintain differences for several months without special isolation techniques. Two methods for achieving this were tried. Firstly, soil was fumigated with two different chemicals, chloropicrin and methyl bromide. The second method was to sterilize the soil by γ‐irradiation and then add contrasting inocula, either seed‐washings, soil bacterial suspension or total soil inoculum. After treatment, the soils were placed in pots in a glasshouse. Lolium perenne, Rumex acetosa and Trifolium repens were grown on them, separately and in two‐species mixtures.The fumigation method proved unsatisfactory since the two treated soils differed significantly in ammonium content but only slightly in microbial abundance. The three inoculum treatments following irradiation resulted in large differences in abundance of various microbial groups, and some of the differences were still present after four months; ammonium contents of the three soils differed only slightly, though all three had much more ammonium than the untreated soil.Fumigation increased the growth of all three species in monoculture to about an equal extent but, in the two‐species mixtures, it altered the balance in favour of Lolium against Rumex and Trifolium, and in favour of Rumex against Trifolium. Irradiation increased the growth of Lolium but reduced the growth of Trifolium. Among the three inoculum treatments, all three species in monoculture showed faster growth with total soil inoculum than with seed inoculum in the early stages but the difference disappeared later. Following irradiation, the balance between species in mixtures was much as expected from monoculture growth; the one exception was Lolium v. Rumex, where bacterial inoculum gave a balance more in favour of Lolium than would be expected.
POLLEN TRANSFER AND POLLINATION IN THE COMMON FIG (FICUS CARICA L.)
Authors: GALIL J. , NEEMAN G. 
Published: May 2006

SummaryThe traditional ideas, as to how pollination is achieved in the common fig (Ficus carica L.), are untenable because the very narrow entrance slits of the ostiole render it very difficult for the pollen vector (the agaonid wasp Blastophaga psenes L.) to introduce pollen on its body surface into the female receptive fig. The process is now shown to entail: (a) loading of pollen in the polleniferous fig into intersegmental and pleural invaginations which form in the shrunken body of the wasp following water loss; (b) unloading of pollen in the receptive fig, as a result of partial swelling and contortion of the wasp's body during oviposition attempts. Conditions in the cavities of polleniferous and receptive figs are discussed in connection with the pollination process.
THE POLLINATION ECOLOGY OFEPIPACTIS CONSIMILISDON (ORCHIDACEAE) IN ISRAEL
Authors: IVRI YARIV , DAFNI AMOTS 
Published: May 2006

SummaryObservations on the pollination ecology ofEpipactis consimilisDon (Orchidaceae) in Israel are described. The pollinators were found to be eight species of five genera of hover files (Syrphidae), especiallySphaerophoria scriptaandS. rueppellii.Different behaviour patterns of the insect species and the sexes thereof are given and discussed. It is suggested that the flower mimics the shape and colour of aphids and this attracts aphidophagous hover flies.
INCORPORATING CHECKS AGAINST OBSERVER ERROR INTO IDENTIFICATION KEYS
Authors: PAYNE R. W. , PREECE D. A. 
Published: May 2006

SummaryA method is suggested for checking for errors that may be made when an identification (or diagnostic) key is used. Such errors may arise either from tests being incorrectly used or observed, or because the specimen examined is aberrant or incomplete. The method involves constructing a check key for each endpoint of the main key. Use of the appropriate check key confirms or corrects the initial identification.
CHANGES IN THE LEVELS OF ENDOGENOUS CYTOKININS AND INDOLE‐3‐ACETIC ACID DURING EPIPHYLLOUS BUD FORMATION IN BRYOPHYLLUM DAIGREMONTIANUM
Authors: HENSON I. E. , WAREING P. F. 
Published: May 2006

SUMMARYLevels of endogenous cytokinins and indole‐3‐acetic acid (IAA) in mature leaves and shoot tips of Bryophyllum daigremontianum (R. Hamet and Perr.) Berg, were determined at various times following transfer of the plants from short to long photoperiods, a treatment which results in release of the epiphyllous buds from correlative inhibition. There were transient increases in levels of both cytokinins and IAA following transfer to long days. The increase in IAA levels occurred prior to the increase in cytokinins. Maximum IAA levels were present in shoot tips 5 to 10 days after transfer, while maximum cytokinin activity was not detected until after 20 long days in the case of shoot tips, and 10 to 20 long days with mature leaves. Growth of epiphyllous buds, which was restricted to the shoot tips, became apparent only after 20 long days. Levels of both cytokinins and IAA were higher in shoot tips of plants grown throughout in short days than in plants raised entirely in long days. The types of cytokinins present in the two sets of plants did not, however, appear to differ.
RATES OF TRANSLOCATION AND PHOTOSYNTHESIS IN MIMOSA PUDICA L.
Authors: HODDINOTT JOHN 
Published: May 2006

SUMMARYFollowing mechanical stimulation, the leaves of Mimosa close and their photosynthetic rate declines by 40%. The translocation rate remains constant during leaf closure suggesting that blockage of transport by rapid sieve plate callose formation is not occurring. The rates of photosynthesis and translocation do not appear to be closely coupled.
A HISTOCHEMICAL INVESTIGATION OF LEAD UPTAKE IN RAPHANUS SATIVUS
Authors: LANE S. D. , MARTIN E. S. 
Published: May 2006

SUMMARYA histochemical method was used to investigate the distribution of applied lead in the seed and seedling stage of Raphanus sativus. Lead contamination of the embryo was inhibited by the testa until it ruptured during imbibition. In seedlings, lead moved into the root cortex predominantly along the cell walls as far as the endodermis. Beyond the endodermis lead was localized extensively in the vascular tissues. There was little movement of lead from the vascular tissue into the surrounding tissue of the stem and cotyledons.
THE UPTAKE OF THIOUREA BY CHLORELLA
Authors: SYRETT P. J. , BEKHEET I. A. 
Published: May 2006

SUMMARYCells of Chlorella fusca grown with urea as nitrogen source take up and accumulate thiourea; ammonium‐grown cells take up thiourea more slowly. Uptake results from a metabolic process superimposed on passive diffusion. The uptake system has a high affinity for thiourea and urea. Fifty μM thiourea allows half the maximum rate of uptake. Urea inhibits competitively uptake of thiourea and, from the kinetics of inhibition, it can be concluded that the half‐saturation constant for urea is about 5 μM. Uptake of thiourea by urea‐grown organisms is not inhibited by low concentrations of nitrate or of ammonium. There is evidence that the cells metabolize thiourea to a limited extent.
THE FINE STRUCTURE OF PROCHLORON
Authors: WHATLEY JEAN M. 
Published: May 2006

SUMMARYThe fine structure is described of Prochloron, a unicellular prokaryotic alga which contains both chlorophyll a and chlorophyll b. The cell wall resembles that of a blue‐green alga. The thylakoids and cytoplasm together occupy a wide peripheral band. However, the thylakoids are present not as single lamellae, as in blue‐green algae, but in pairs or, sometimes, in thicker stacks. Both thylakoids and cytoplasm are absent from a large central zone which is generally electron‐transparent, but may contain electron‐dense granules and fibrils. The function of the central zone is not known.
AMINO ACID MOVEMENT FROM LEAVES OF TUSSILAGO FARFARA L. TO THE RUST, PUCCINIA POARUM NEILS.
Authors: BURRELL M. M. , LEWIS D. H. 
Published: May 2006

SUMMARYThe amino acids, alanine, aspartic acid, glutamic acid, glutamine and serine, were labelled when 14CO2 was supplied to leaves of Tussilago farfara. Exogenously supplied [14C] glycine, serine, cysteine and methionine are rapidly metabolized by host tissue. An isotope dilution technique was used to investigate the movement of amino acids into the rust pustule. The results indicate that serine and alanine are absorbed more readily from the host than aspartic acid, glutamic acid or glutamine.
EFFECTS OF LIGHT INTENSITY ON THE FORMATION OF VESICULAR‐ARBUSCULAR ENDOMYCORRHIZAS ON ALLIUM CEPA BY GIGASPORA CALOSPORA
Authors: FURLAN V. , FORTIN J.‐A. 
Published: May 2006

SUMMARYFour different light intensities exerted distinctly different effects on the formation, reproduction and influence of vesicular‐arbuscular mycorrhiza on onion plants. Over a growth period of 100 days, the rate of infection under low light intensities (5 and 10 klux) was more rapid and the percentage of infection higher than on mycorrhizal plants cultivated under a light of 15 and 20 klux. The production of spores increased with light intensity. A plant growth enhancement occurred at all light levels but was most pronounced under a 10 klux light regime.
PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS
Authors: KERSHAW K. A. 
Published: May 2006

SUMMARYThe control of the net photosynthetic rate in Peltigera canina var. praetextata and P. polydactyla by temperature, light and moisture has been examined on a seasonal basis. Mean optimum values of 6 mg CO2 g−1·h−1 are achieved by young lobes of either species during late spring, summer and early winter. However, under full winter conditions optimum net photo‐synthetic rates fall to 3 mg CO2 g−1·h−1. Light saturation is approximately 500 μE m−2 s−1 at all times of the year, but the temperature at which maximum rates of net photosynthesis are achieved changes markedly throughout the year in both species. In winter, maximum rates occur at an experimental thallus temperature of 5°C but by mid‐summer, the optimum temperature for net photosynthesis is c. 30°C, which corresponds to equivalent ambient temperature levels in the field. This temperature acclimation of net photosynthetic optima is achieved without any significant change in respiration rate and shows a remarkable degree of homeostasis during spring, summer and early winter. The results strongly emphasize the unsatisfactory nature of the univariate experimental design which has often been used in lichen physiological ecology. The extreme importance of a controlled storage temperature for experimental lichen material is also clearly evident. The low net photosynthetic rates in winter show the same pattern in both Peltigera species during these low temperature and short day conditions.
H+ AND Ca2+ IN PHLOEM AND SYMPLAST: RELATION OF RELATIVE IMMOBILITY OF THE IONS TO THE CYTOPLASMIC NATURE OF THE TRANSPORT PATHS
Authors: RAVEN J. A. 
Published: May 2006

SUMMARYThe capacity of the symplast and the phloem to transport Ca2+ and H* (OH−) is discussed in relation to the concentrations of free and bound Ca2+ and H* in these transport systems, and the general restrictions on the concentrations of free Ca2+ and H* in cytoplasm. It is concluded that the low Ca2+ and H+ transport capacity of symplast and phloem are consequences of the cytoplasmic nature of these transport systems. The significance of the low transport capacity for these two ions relative to the rate at which the plant produces or consumes H+ or can take up Ca2+ and transport it in the xylem is discussed. Other transport characteristics of the phloem can also be related to the cytoplasmic nature of the transport conduit: the nature of the transported organic C and N compounds is partly dependent on the requirement that high concentrations of these solutes can be tolerated by cytoplasmic enzymes, i.e. sucrose, mannitol and amino‐acids are ‘compatible solutes'. The properties of the intracellular transport systems (symplast and phloem) are contrasted with those of extracellular transport systems such as plant xylem and animal blood.
ASPARTATE‐DEPENDENT ALANINE PRODUCTION BY LEAF DISCS OF AMARANTHUS PANICULATUS, AN ASPARTATE UTILIZING NAD‐MALIC ENZYME TYPE C4 PLANT
Authors: RAGHAVENDRA A. S. , DAS V. S. R. 
Published: May 2006

SUMMARYIlluminated leaf discs of Amaranthus paniculatus formed alanine rapidly after infiltration with aspartate. a‐oxoglutarate and glutamate accelerated aspartate‐dependent alanine production. Alanine was also formed by A. paniculatus leaf discs infiltrated with oxalacetate; this production was stimulated only by glutamate. Our results confirm that alanine can be formed rapidly from aspartate in C4 plants. Aspartate‐dependent alanine production was stimulated greatly by light. The stimulatory effect of light could almost be replaced by ATP in presence of sodium ions. These findings are discussed in relation to a possible light‐dependent active transport of amino acids into the bundle sheath, mediated by Na+‐dependent ATPase activity.
TOLERANCE OF ANOXIA AND ETHANOL METABOLISM IN GERMINATING SEEDS
Authors: CRAWFORD R. M. M. 
Published: May 2006

SUMMARYSeeds resistant to soaking injury and the associated condition of anoxia regulate glycolysis so that there is minimal production of ethanol. This regulation is achieved by low anaerobic respiration rates, the minimization of the Pasteur effect, and by the production of lactate as an alternative to ethanol during the early stages of anaerobiosis. Resistant seeds differ from those intolerant of soaking where anoxia causes an acceleration of glycolysis, an induction of alcohol dehydrogenase activity and the production of large quantities of ethanol as the exclusive end‐product of glycolysis. Seeds tolerant of soaking are therefore similar to the roots of flood‐tolerant plants where ethanol production is also limited during periods cf anoxia.