bluuebunny/crossref_metadata_2025_split huggingface dataset:
LICHEN METABOLISM. 1. THE USE OF TRITIUM LABELLED WATER IN STUDIES OF ANHYDROBIOTIC METABOLISM IN RAMALINA CELASTRI AND PELTIGERA POLYDACTYLA
Authors: COWAN D. A. , GREEN T. G. A. , WILSON A. T. 
Published: May 2006

SummaryA new radiochemical technique has been applied to a study of anhydrobiotic metabolism in the lichen species, Ramalina celastri (Sprengel) Krog & Swinsc. and Peltigera polydactyla (Neck.) Hoffm. Specimens were incubated in known atmospheric humidities of THO vapour which were found to equilibrate with cellular H2O within 5 days. This method has proved effective in a study of a wide range of in vivo metabolic processes occurring at both high and low cellular water contents.Qualitative and quantitative estimations of the 3H labelling of water soluble cell constituents (ammo acids, organic acids, sugars, sugar phosphates, and sugar alcohols), neutral and polar lipids, water soluble macromolecules, and insoluble cell residues have shown that diverse metabolic systems have significantly different levels of resistance to desiccation. Tricarboxylic acid cycle reactions and related amino acid interconversions were shown to be relatively desiccation resistant, whereas Calvin cycle metabolism appeared to be highly sensitive, a conclusion supported by 14CO8 tracer experiments. Conversely, the synthesis of sugar alcohols was found to be active beyond the limit of photosynthetic metabolism. Neither lipid nor macromolecular synthesis was shown to occur to a significant degree in either lichen in the desiccated state.It is proposed that the syntheses of amino acids and sugar alcohols at low cellular saturation levels are important physiological processes. Amino acid synthesis results in the accumulation of an available store of stable intermediates, ready to feed into the T.C.A. cycle by trans‐amination or deamination on rehydration of the lichen. Sugar alcohol metabolism assists in the maintenance of a high sugar alcohol concentration to act as a physiological buffer during extreme dehydration.
STUDIES ON AEROBIOLOGY‐ATMOSPHERIC FUNGAL SPORES
Authors: BHATI H. S. , GAUR R. D. 
Published: May 2006

SummaryA survey of atmospheric fungal spores was carried out at Modinagar, situated in the western part of Uttar Pradesh (India). The site for the study represents a rural and semi‐industrial area. The incidence of the fungal spores in the air was studied by the simultaneous exposure of adhesive coated slides for 24 h and petri dishes containing culture media for 5 min daily all the year round (August 1975 to July 1976). The slides exhibited a preponderance of spores of: Alternaria; Beltrania; Cladosporium; Curvularia; Epicoccum; Fusarium; Helminthosporium; Nigrospora; Prathroda.; rust spores; smut spores; small round spores (spp. of Aspergillus, Penicillium, Mucor, Rhizopus), Thielaviopsis. Species of Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Verticillium and Thielaviopsis showed excellent growth on exposed culture media dishes. Several other types of spores were also found in comparatively low numbers. The seasonal and monthly variation of these air‐borne fungi were studied qualitatively and quantitatively.
ULTRASTRUCTURAL ASPECTS OF THE DEVELOPMENT OF FIBRES FROM THE FLOWERING STEM OF LOLIUM TEMULENTUM L.
Authors: LAWTON J. R. , HARRIS P. J. , JUNIPER B. E. 
Published: May 2006

SummaryFibres develop from initially elongated cells with a large proportion of cytoplasm containing many ribosomes, relatively few, but large, mitochondria, proplastids, Golgi bodies and either several small vacuoles or one central vacuole. During cell elongation the central vacuole enlarges and the cytoplasm forms only a thin lining except at the fibre tips. At this stage the ribosomes are present as polysomes and associated with the endoplasmic reticulum as rough ER(RER). The number of Golgi bodies apparently increases and there are both electron transparent vesicles of various sizes and small vesicles with an electron dense core. Lomasomes and inclusions between the wall and the plasmalemma are seen at this stage. Increase in cell wall thickness is associated with an increase in the number of Golgi bodies with large vesicles and also those vesicles with an electron dense core. Wall thickening is also accompanied by the appearance of many microtubules parallel to the long axis of the cell adjacent to the plasmalemma. Even in a well developed inflorescence axis bearing ripening grains there is still visible cytoplasm in the majority of the fibre cells.
CLONAL VARIATION IN POPULATIONS OF RANUNCULUS REPENS
Authors: SOANE I. D. , WATKINSON A. R. 
Published: May 2006

SummaryA computer simulation model is developed to examine the relationship between the population flux of ramets, the recruitment of seedlings and genet diversity in populations of Ranunculus repens in a North Wales pasture. The study is based on a continuous monitoring of the flux of ramets and recruitment of seedlings in eight populations over a period of 4 years. A simple flow diagram, which describes the life‐cycle of R. repens and which incorporates the field census data, is used as the basis for a series of computer simulations. The computer model simulates the actual flux of ramets in each of the eight populations and, assuming no selection between families, is used to follow the fates of ramets and families of ramets. Comparisons between the numbers of families of ramets in the real and simulated populations provide little evidence for selection between families of ramets or against new seedling recruits. With no selection the number of original families present within a population declines at an approximately exponential rate and the contribution made by these families to the total genet diversity of the population rapidly becomes subordinate to the role of new seedling inputs. It is suggested that although the contribution of seedlings to maintaining the total number of individuals, Nη, in populations of plants which spread clonally may be very small, the occasional establishment of seedlings may nevertheless play a significant role in determining the number of clones or genets, N.
PROTEIN BODY MEMBRANES OF PHASEOLUS VULGARIS L. COTYLEDONS: ISOLATION AND PRELIMINARY CHARACTERIZATION OF CONSTITUENT PROTEINS
Authors: PUSZTAI A. , CROY R. R. D. , STEWART J. S. , WATT W. B. 
Published: May 2006

SummaryMembrane preparations (1·16 g ml−1 average density) produced by osmotic shock from cotyledonary protein bodies of Phaseolus vulgaris were isolated and purified by sucrose density centrifugation. The constituent polypeptides of these membranes were characteristic and different from those of storage proteins and were shown by SDS gel electrophoresis to consist of, in addition to low mol. wt glycolipid‐type material, polypeptides of 16000, 20000, 25000, 30000 and 78000. Of these, the 25000 and the 78000 components appeared to be more tightly associated with the membrane structure than other polypeptides. The 20000, 25000 and 30000 polypeptidea were separated by preparative SDS gel electrophoresis, freed from SDS and extraneous carbohydrates by phenol‐borate (pH 8) partitioning and further purified by chromatography on Bio Gel A 5 m in 5 M guanidine HC1. The 30000 polypeptide was identified by chemical, physical and immunochemical methods as a haemagglutinating globulin lectin. The 25000 polypeptide component bore a superficial resemblance to the so‐called structural protein generally distributed in a great variety of plants and animal membranes. The 20000 polypeptide has not yet been identified with any known Phaseolus vulgaris protein.
STORAGE OF DETACHED LEAVES AND TWIGS WITHOUT CHANGES IN WATER POTENTIAL
Authors: KARLIC HEIDRUN , RICHTER HANNO 
Published: May 2006

SummarySeveral different methods were investigated for storing conifer twigs and tree leaves for prolonged periods without changing their water status, as assessed by the pressure chamber. Whereas simple procedures (keeping between wet foam‐rubber mats or even immersion in water) were sufficient for gymnosperms, the leaves of angiosperma had to be protected more carefully. With deciduous leaves the best method was to store them in completely airtight bags made from aluminium foil; sclerophyllous evergreen leaves may alternatively be covered with a layer of Vaseline and stored in polythene bags between wet foam‐rubber sheets. It proved possible to keep leaves for periods of up to several days without significant changes in either their total water potential or their osmotic relations as determined by the pressure‐volume technique.
LIGHT AS A FACTOR OF GROWTH AND MORPHOGENESIS II. EFFECT OF VARYING PHOTOPERIODS ON CROTALARIA JUNCEA L. AND C. SERICEA RETZ
Authors: PANDEY B. N. , SINHA R. P. 
Published: May 2006

SummaryThe growth of Crotalaria juncea L. and C. sericea Retz. under 8, 10, 12, 14 and 16 h daylengths was studied with respect to dry wt accumulation, leaf area increase, RGR, LAR, SLA, LWR, NAR, the value of a (ratio of mean relative growth rate to mean relative rate of leaf area increase) and S/R ratio. In both species, dry wt and leaf area increased up to 14 h daylength above which these features of C. juncea declined. The higher trend maintained in C. sericea suggests this is of selective value to a ruderal. C. sericea is characterized by a narrower range of values under the varying photoperiods. Strict comparison in terms of LAR is not possible owing to ontogenetic drift. In terms of RGR and NAR, C. sericea shows greater uniformity in all photoperiodic regimes. Values of a for this species also show a narrower range. All these are suggestive of its greater capacity than C. juncea to survive ecological vicissitudes in natural habitats.
THE DEVELOPMENT OF ENDOMYCORRHIZAL ROOT SYSTEMS II. EFFECT OF AGRONOMIC FACTORS AND SOIL CONDITIONS ON THE DEVELOPMENT OF VESICULAR‐ARBUSCULAR MYCORRHIZAL INFECTION IN BARLEY AND ON THE ENDOPHYTE SPORE DENSITY
Authors: Black R. , Tinker P. B. 
Published: May 2006

SummaryThe percentage of roots with vesicular‐arbuscular mycorrhizal fungi and numbers of spores were measured over 2 years in a field experiment with different crop rotations of barley, kale and fallow. Spore numbers, and subsequent infections of barley crops, were largest following barley; both kale and fallow breaks reduced spore population and infection similarly. With all crop rotations there was a long delay before appreciable percentage infection of roots developed, followed by a rapid increase, and then a constant value. Such late infections appear unlikely to improve crop nutrition, and final yield was negatively related to per cent infection.A survey of barley crops in 2 years on commercial fields following at least 3 years barley showed that infection was rather similar in most fields. There was a very slight correlation between infection percentage, clay content and pH, but no other soil factor had any influence. Early‐sown crops tended to have low infection.
MYCORRHIZAL STATUS OF ERICACEOUS PLANTS IN ALPINE AND SUBALPINE AREAS
Authors: Haselwandter K. 
Published: May 2006

SummaryMycorrhizal infection of Ericaceae is of considerable ecological significance in heathlands and may be of particular importance in alpine regions which experience short growing seasons and slow rates of mineralization of major nutrients. The extent of mycorrhizal infection has been determined by a chemical method based upon quantitative determination of fungal chitin. In five species of ericaceous plants selected from sites of different elevations in the alpine and subalpine zone, there is a relationship between extent of mycorrhizal infection and host vigour. Infection levels increase with decrease in altitude of sampling sites.
NUTRITIONAL STUDIES ON THE PARASITIC RED ALGA CHOREOCOLAX POLYSIPHONIAE
Authors: Callow J. A. , Callow M. E. , Evans L. V. 
Published: May 2006

SummaryChoreocolax polysiphoniae Reinsch is a minute, cushion‐shaped, variably‐pigmented red alga forming a‘parasitic’association with Polysiphoma lanosa. Cortical cells of Choreocolax contain starch grains and small, poorly‐differentiated plastids. Through 14C labelling experiments it has been shown that 14C fixed by Polysiphonia as sodium mannoglycerate may be transferred to Choreocolax, although clear differentiation between host and parasite tissues is difficult due to displacement of some host cells within the thallus of the parasite. However, Choreocolax can also fix CO2 photosynthetically, an ability which appears to be partially repressed in the attached state since CO2 fixation progressively increases with time if Choreocolax plants are detached from the host. The products of Choreocolax photosynthesis may include mannitol and an unidentified complex carbohydrate.
HAUSTORIAL FREQUENCY OF SOME ROOT PARASITES IN CULTURE
Authors: MUSSELMAN L. J. , MANN W. F. 
Published: May 2006

SummarySeventeen root parasites representing nine genera in three families native to the southern United States were grown with 19 tree species to determine host preference and host susceptibility. Trees were grown in pots with a single parasite. After about 12 months the plants were removed and the number of haustoria noted. The number of haustoria or haustorial frequency were interpreted as a rough index of the suitability of that tree to serve as a host. All parasites showed a broad host range indicating little host specificity. In addition, none of the hosts were immune to parasitism. A few plants behaved as complete autotrophs, even though host roots were in physical contact with those of the parasite.
CARBOHYDRATE COMPOSITION AND INVERTASE ACTIVITY IN POPLAR LEAF TISSUES INFECTED BY MILLAMPSORA AECIDIOIDES (D.C.) SCHROETER
Authors: ROBERTS S. M. , MITCHELL D. T. 
Published: May 2006

SummaryQualitative analyses of ethanol‐soluble carbohydrates of rust‐infected poplar leaves were similar to those of other rust infections. Sucrose was the most abundant ethanol‐soluble carbohydrate in both healthy and infected leaf tissues. Mannitol, arabitol and trehalose were detected in low concentrations at the site of infection. Mannose formed a significant proportion of the insoluble carbohydrates in the pustule disc. Activities of both acid and alkaline invertase, assayed by two methods, were similar in both healthy and infected tissues. These results are discussed in relation to those of other biotrophic infections and it is suggested that the Populus canescens Aiton Sm./Melampsora aecidioides (D.C.) Schroeter relationship may be a benign one.
INTERGLACIAL POLLEN SPECTRA FROM SEL AYRE, SHETLAND
Authors: BIRKS H. J. B. , PEGLAR SYLVIA M. 
Published: May 2006

SummaryThe lithostratigraphy of a section exposed at Sel Ayre on the Walls Peninsula, Shetland Mainland is described. A peat bed 50 cm thick is overlain by 7·3 m of sands, gravels, and boulder clay. Pollen analyses of this peat bed and of peat laminae in the sands reveal three distinctive pollen assemblages. These assemblages are interpreted as reflecting a vegetational development from grass‐ and fern‐dominated communities an fertile brawn‐earths to dwarf‐shrub heaths dominated by ericaceous shrubs including Bruckenthatia spiculifolia. These heaths grew on acid humus‐rich podsols and were replaced by open, grass‐dominated communities. Numerical comparisons of the Sel Ayre pollen spectra with pollen data from other sites on Shetland using principal components analysis suggest that three interglacial stages are represented on Shetland Mainland –Fiandrian, Ipswichian and Hoxnian. On the basis of the composition of the presumed long‐distance tree‐pollen rain, the Sel Ayre sequence is correlated with the Ipswichian stage. A basic interglacial cycle is proposed for the Shetlands.
PINOCYTOSIS IN PLANTS
Authors: CRAM W. J. 
Published: May 2006

SummaryThe question considered is whether pinocytosis is the principal means of transporting major nutrients across the plasmalemma.It is argued that ultrastructural evidence previously advanced in favour of pinocytosis in plant cells can be interpreted in other ways and does not uniquely support the hypothesis of pinocytosis. Physiological evidence ‐ particularly, selectivity in uptake, competition between substances, differential effects on influx of changes in internal states, and the associated electrical currents ‐ is incompatible with the characteristics of pinocytosis in animal cells. The suggestion that pinocytosis in plants involves selective binding prior to uptake cannot be accepted because the required density of binding sites is at least three orders of magnitude greater than is possible.On theoretical grounds it is shown that the water flow that would be associated with pinocytosis would generate high values of turgor which are not observed and probably could not be sustained. Further, it is calculated that during pinocytosis the probable energy to overcome turgor would be needed at a rate greater than the cell could supply. Thus it appears not only that pinocytosis does not occur, but also that it could not occur in plant cells.
THE INFLUENCE OF TEMPERATURE ON THE ABSCISIC ACID STIMULATED WATER FLOW FROM EXCISED MAIZE ROOTS
Authors: COLLINS J. C. , MORGAN MAUREEN 
Published: May 2006

SummaryThe stimulatory effect of ABA on fluid exudation from excised maize roots has been confirmed. The maximum stimulation of water flow by ABA occurred at about 20 °C, and was enhanced by low concentration of the bathing medium. ABA increased the hydraulic conductivity of the root and the activation energy of water permeability was greater in the presence of ABA. It is believed that ABA acts directly at the membrane level, where it forms pores or channels in the membrane; these increase permeability to ions and water.
REPRODUCTIVE AND VEGETATIVE PERFORMANCE IN TWO WINTER ANNUAL GRASSES, CATAPODIUM RIGIDUM (L.) C.E. HUBBARD AND C. MARINUM(L.) C. E. HUBBARD
Authors: CLARK S. C. 
Published: May 2006

SummaryDemographic analysis of the leaf population of three populations of Catapodium rigidum and one of C. marinum grown throughout their life‐cycles in a growth‐room showed that the factors affecting the age‐structure and life‐expectancies of the leaf‐populations were in the order, temperature and/or photoperiod > soil‐type > populations. Winter conditions produced an uneven‐aged, long‐lived leaf population, in which maximum leaf‐age was c. 150 d. Summer conditions produced even‐ aged, short‐lived populations in which maximum leaf‐ age was c. 60 d. Leaves which developed in winter conditions had shorter expectancies in summer conditions than those which developed during summer. There were some significant differences between soils for parts but not the whole of the life‐ cycle. The result of late sowing was to reduce the differences in age‐structure and expectancies between stage of the life‐cycle and to reduce maximum leaf‐age by c. 35%. Differences between the leaf‐populations of the early‐and late‐ sown plants were apparently due to external and not ontogenetic factors. The relationship between leaf life‐expectancy and leaf and tiller numbers on the one hand and numbers and weights of caryopses on the other was investigated using a step‐wise multiple regression technique. Leaf life expectancy, especially late in the life‐cycle, was significantly (negatively) associated with caryopsis weights but not with numbers and it accounted for c. 80% of the variation. Leaf numbers, especially late in the life‐cycle, were significantly positively associated with caryopsis‐numbers and accounted for 100% of the variation. Leaf‐numbers early in the life‐cycle were also associated (negatively) with caryopsis‐weights, when they accounted for c. 40% of the variation. Tiller‐numbers were not as closely associated with caryopsis production and accounted for < 40 % only of the variation. Possible effects on seed production of alterations in the demographic parameters of leaf‐populations are discussed.
THE INHIBITION OF GERMINATION OF BIDENS PILOSA SEEDS BY LEAF CANOPY SHADE IN SOME NATURAL VEGETATION TYPES
Authors: FENNER M. 
Published: May 2006

SummaryThe inhibition of germination by leaf canopies was investigated in Bidens pilosa, a widespread tropical colonizing weed species. Seeds of this species were sown in the shade of four natural vegetation types: early colonizing stage of an old field succession, a later stage of the same sere, short grass, and long grass. There were four control treatments: full sunlight on open soil, banana‐leaf shade, ‘neutral’ shade under white paper, and darkness. Since the temperature regimes under the canopies differed, the effect of temperature on the germination of the seeds was investigated. The results show that the leaf canopies of the vegetation types investigated are markedly effective in inhibiting germination of this species in the field. Inhibition by unfavourable temperatures could have been only a contributory factor. It is suggested that seed sensitivity to leaf canopy shade may be of importance in effecting changes in species composition in early successional stages, and in excluding open‐habitat species from closed vegetation generally.
THE BIOLOGY OF AMBROSIA TRIFIDA L. V.RESPONSE TO FERTILIZER, WITH GROWTH ANALYSIS AT THE ORGANISMAL AND SUB‐ORGANISMAL LEVELS
Authors: HUNT RODERICK , BAZZAZ F. A. 
Published: May 2006

SummaryGiant ragweed, Ambrosia trifida L., was grown over a period of 36 days in a glasshouse at two levels of soil fertility. Growth was investigated both by the conventional (whole‐plant) techniques of growth analysis and by these same techniques applied to data obtained on the growth of roots, stems and each of the successive leaves.Results showed that the superior performance of the fertilized plants was due to their higher leaf‐area ratio rather than to an enhanced unit leaf rate. Here, the rates of dry‐matter commitment to leaves at nodes 2, 3 and 4, expressed per unit of whole plant dry wt, were initially around 0‐04 g g−1 day−1 ‐about twice the values obtained for the same leaves in the unfertilized plants.There was a heavy early commitment to root growth especially in the unfertilized plants. Stem production was moderately high throughout in both treatments. The large response to fertilizer application would be expected of the species since it colonizes arable land and flood‐plains both of which experience nutrient pulses. This behaviour, together with the flexibility of material allocation contribute to the high success of the species.The study provided the opportunity to assess the techniques of growth analysis when applied at the sub‐organismal level. The value of this approach was discussed in relation to the parallel activity of leaf demography.
MORPHOLOGICAL VARIATION BETWEEN SOME ISOLATED POPULATIONS OF SILENE MARITIMA WITH. IN THE BRITISH ISLES WITH PARTICULAR REFERENCE TO INLAND POPULATIONS ON METALLIFEROUS SOILS
Authors: BAKER A.J. M. , DALBY D. H. 
Published: May 2006

SummaryThe present distribution of Silene maritima in the British Isles is discussed in relation to the phylogenetic history of the bladder campions and the status of the inland populations. An experimental study of morphological variation between geographically isolated populations of S. maritima is described. Large‐scale divergence in a number of quantitative and qualitative vegetative and floral characters was apparent. The populations studied included coastal, arctic‐alpine and inland, heavy‐metal mine types, together with one mine population of S. vulgaris. Populations from mine sites proved distinct from coastal and arctic‐alpine populations in their growth habit and leaf morphology. Similar, but smaller, differences in floral morphology were apparent. For every quantitative character scored, significant inter‐population variation was detected. The qualitative characters scored also showed great inter‐population differences. The possible evolutionary significance of morphological divergence between these S. maritima populations is discussed.