bluuebunny/crossref_metadata_2025_split huggingface dataset:
MITOTIC SYNCHRONY INDUCED IN MERISTEMS OF VICIA FABA BY 5‐AMINOURACIL: RESPONSE OF SYNCHRONIZED CELLS TO DEOXYNUCLEOSIDES
Authors: RUDOLPH J. M. , DAVIDSON D. 
Published: May 2006

SUMMARYRoot systems of Vicia faba L. were treated with 3.93x10‐3 solutions of 5‐aminouracil (5‐AU). Cells are blocked, apparently at the S‐G2 transition point, and subsequently a wave of synchronized mitoses are seen. The time and the degree of synchronization differed in different meristems. Cells of primordia are blocked by 5‐AU to the same extent as cells of lateral or primary roots but their cells recover more rapidly than those of fully developed roots. Treatment with a solution of deoxyrinucleosides (10‐6 or 10‐7M) immediately after 5‐AU appears to reverse the block at the S‐G2 transition and results, in a number of cases, in an increase in the degree of mitotic synchrony. The evidence presented shows that 5‐AU and deoxynucleosides reach primordia and fully emerged meristems in effective concentrations; no evidence was found for differential permeability to these compounds. It is suggested that differences in the rate of recovery from the inhibition imposed by 5‐AU reflects some physiological differences between cells of different meristems.
THE GIANT LOBELIAS: PACHYCAULY, BIOGEOGRAPHY, ORNITHOPHILY AND CONTINENTAL DRIFT
Authors: MABBERLEY D. J. 
Published: May 2006

SUMMARYRecent revisions of the Asian, Jamaican and African species of pachycaul lobelias raise a number of evolutionary and biogeographical problems. Discussion of the apparent forest pachycaul ancestry of the African species is applied to problems of biogeography, pollination and Continental Drift. The available facts are accommodated in an hypothesis, wherein the African species are considered to have had an American ancestry. Herbaceous habit, dry fruit, wingless seeds, enhanced alpine pachycauly and entomophily are considered advanced characters. Further investigations, particularly with regard to the American species, are suggested to test the hypothesis.
BACTERIA AND NUCLEI IN PELOMYXA PALUSTRIS: COMMENTS ON THE THEORY OF SERIAL ENDOSYMBIOSIS
Authors: WHATLEY JEAN M. 
Published: May 2006

SUMMARYThe primitive giant amoeba, Pelomyxa palustris, contains a population of endosymbiotic bacteria. The distinctive ultrastructure of one of the species of bacteria is described in detail. A particularly close relationship exists between these bacteria and the nuclei of Pelomyxa. The significance of some aspects of this relationship is discussed with reference to the endosymbiotic theory of the origin of mitochondria from bacterial precursors.
VARIATION WITHIN COMMON GROUNDSEL, SENECIL VULGARIS L. II. LOCAL DIFFERENCES WITHIN CLIFF POPULATIONS ON PUFFIN ISLAND
Authors: ABBOTT RICHARD J. 
Published: May 2006

SUMMARYDifferences of height between plants from subjectively determined exposed and sheltered sites were examined in two cliff populations of Senecio vulgaris L. from Puffin Island, Anglesey, N. Wales. Under glass the relative dwarf habit of exposed plants from a N. cliff site was retained in their progeny throughout development, but for S. cliff material there was no difference in height between progenies of exposed and sheltered plants at maturity. It was inferred that within the N. cliff site, genetic variability seems to parallel variation in exposure. But in the S. cliff site response to different levels of exposure is mainly facilitated by a wide measure of developmental flexibility for height. It is suggested that the apparent difference of adaptive strategy between the two cliff populations some 500 m apart may be explained in terms of disparate wind speeds in the respective sites. The N. cliffs are particularly exposed to strong winds and under these conditions it is possible that genetic adaptations to the separate micro‐environments enhances survival.The reported predominant self‐pollination within S. vulgaris (Trow, 1912; Hull, 1974) is considered in discussion to be of value to an ephemeral as a means of adapting it to the local micro‐habitats in a heterogeneous environment, so perpetuating the between plant variability. There are indications that the observed pattern of localised genetic variation on Puffin Island, both between and within populations, has evolved over the last 20 years.
GLUCOSE METABOLISM IN HYDRODICTYON AFRICANUM IN RELATION TO CELL ENERGETICS
Authors: RAVEN J. A. 
Published: May 2006

SUMMARYWhen ATP is supplied by oxidative phosphorylation alone, cyclic photophosphorylation alone or from both photosynthetic and oxidative phosphorylations, exogenous glucose is metabolized to a similar range of non‐volatile products of which a major one is starch. When only fermentative ATP supply can occur, much less starch is produced. Cyclic photophosphorylation alone supports a rather lower rate of starch synthesis from exogenous glucose than does oxidative phosphorylation alone. This is apparently due to rate‐limitation by glucose influx, since cyclic ATP production supports a faster rate of starch synthesis than does oxidative ATP production when endogenous substrate is used.Production of CO2 from specifically labelled glucose is consistent with the operation of the EMP, PPP and TCAC in both light and darkness in the presence of oxygen. Fermentation of exogenous glucose is inhibited by light absorbed by photosystem one, probably via cyclic photophosphorylation. Respiratory CO2 production is also inhibited to a small extent by photo‐system one, although most of the light inhibition needs photosystem two. This DCMU‐reversed inhibition of CO2 production in the light is due to a direct inhibition of decarboxylation reactions as well as to reassimilation of respired CO2.The relatively small randomization of C1 and C6 labelled glucose during assimilation into starch suggests that conversion to triose phosphate may not be essential for transport of hexose across the outer chloroplast membranes.
THE RATE OF CYCLIC AND NON‐CYCLIC PHOTOPHOSPHORYLATION AND OXIDATIVE PHOSPHORYLATION, AND REGULATION OF THE RATE OF ATP CONSUMPTION IN HYDRODICTYON AFRICANUM
Authors: RAVEN J. A. 
Published: May 2006

SUMMARYWork previously published by the author shows that either cyclic photophosphorylation or oxidative phosphorylation can supply ATP to a variety of ATP‐requiring processes in Hydrodictyon africanum. The rate at which the process occurs with ATP supplied from cyclic photophosphorylation is in some cases faster than that when ATP is supplied by oxidative phosphorylation; for other processes the reverse is true. The reasons for this variability in the rate at which the two ATP sources can support different ATP‐requiring processes is discussed and it is suggested that regulation of the rate of ATP‐requiring processes involves changes in the activity of the ATP‐consuming reactions as well as in the ATP concentration (or energy charge). It is concluded that the in vivo capacity for cyclic photophosphorylation is at least as great as that for oxidative phosphorylation. Based on the capacity for respiratory electron flow in vivo, it is suggested that cyclic and oxidative phosphorylation each have capacities of some 20 μMoles (mg chl)−1 h−l. Based on the capacity for non‐cyclic electron flow in vivo, it is suggested that the capacity for non‐cyclic phosphorylation in vivo is 150 μMoles (mg chl)−1 h−1. Cyclic photophosphorylation saturates at an irradiance of about 1 J m−2 s−1, while non‐cyclic photophosphorylation saturates at about 10 J m−2 s−1. These low figures for this shade‐Actapted alga contrast with about ten‐ to twenty‐fold higher values for capacity and light requirement for the various phosphorylation processes in sun‐Actapted microalgae.
CHANGES IN THE ACTIVITY OF FERREDOXIN NADP REDUCTASE DURING THE GREENING OF BEAN LEAVES
Authors: HASLETT BARRY G. , CAMMACK RICHARD 
Published: May 2006

SUMMARYDuring continuous illumination of etiolated leaves of Phaseolus vulgaris L. ferredoxin–NADP reductase activity increased exponentially after an initial lag period of 10–15 h while the chlorophyll/reductase molar ratio increased to a constant value of 750±50 after approximately 15 h illumination. The same ratio was obtained when greening occurred at low light intensity.The synthesis of ferredoxin–NADP reductase was influenced by phytochrome activity as indicated by its response to red/far‐red light treatments. The effects of D‐threo chloramphenicol and lincomycin indicated that synthesis of this enzyme did not involve translation on chloroplast ribosomes. The data are discussed in relation to the development of ferredoxin and plastocyanin in greening bean leaves.
SEED PROTEINS OF PHASEOLUS AND VIGNA
Authors: DERBYSHIRE E. , YARWOOD J. N. , NEAT E. , BOULTER D. 
Published: May 2006

SUMMARYProtein band patterns of globulins extracted from the seeds of a number of different species of Phaseolus and Vigna, have been obtained by disc electrophoresis and the sub‐units of the major seed proteins have been separated on gels by use of continuous SDS electrophoresis. The agglutinin potential of seed extracts with respect to human Group O red blood cells has also been determined. The globulin extracted from Phaseolus lunatus was different from that from P. acutifolius, P. coccineus, P. dumosus and P. vulgar is, and these globulins were different from the major globulins extracted from other species which differed among themselves. The globulin patterns for P. atropurpureus and P. lathyroides were not the same as those of the other species examined and saline extracts from the two species Iysed red blood cells. Agglutinin activity was detected only in extracts from P. acutifolius, P. coccineus, P. dumosus and P. vulgaris. Glyco‐protein II, the major seed protein of P. vulgaris, was tentatively identified as the major globulin in extracts from P. acutifolius, P. coccineus and P. dumosus, and was not detected in the other species, with the exception possibly of P. atropurpureus and P. lathyroides. We discuss our data in relation to recent re‐classifications of species of Phaseolus and Vigna.
DISTRIBUTION OF THE C4 DICARBOXYLIC ACID PATHWAY OF PHOTOSYNTHESIS IN LOCAL MONOCOTYLEDONOUS PLANTS AND ITS TAXONOMIC SIGNIFICANCE
Authors: RAGHAVENDRA A. S. , DAS V. S. R. 
Published: May 2006

SUMMARYThe photosynthetic characteristics of fifty‐six monocotyledonous plants belonging to seventeen families were examined. As many as twenty‐three plants, hitherto unreported, showed C4 pathway characteristics. C4 species were recorded in ten new genera. The C4 plants were confined to the families, Cyperaceae and Gramineae. The findings confirm the highly evolved nature of the tribes Andropogoneae and Paniceae in contrast to the primitive features of Agrosteae and Festuceae. On the basis of photosynthetic characteristics, it is suggested that Aristida should be included in a separate tribe, Aristideae, whereas Eragrostis resembles more panicoid grasses rather than the members of Festuceae. The importance of the C4 syndrome in relation to the evolution of grasses is stressed.
ULTRASTRUCTURE OF WHEAT RHIZOSPHERE
Authors: FOSTER R. C. , ROVIRA A. D. 
Published: May 2006

SUMMARYUltrathin sections of rhizospheres of wheat roots showed sparse colonization of the root surface by microorganisms in young roots. Older roots at the flowering stage showed considerable development of microorganisms both in the rhizosphere and in the outer cortical cells and cell walls. The invasion of cortical cells was preceded by lysis of the host cell wall, the stages of lysis are illustrated. The spatial relationships between clay aggregates, microorganisms, mucilaginous materials and the root surface are described.
A MICROSCOPICAL STUDY OF THE DEVELOPMENT OF A SPORE‐LIKE STAGE IN THE LIFE CYCLE OF THE ROOT‐NODULE ENDOPHYTE OF ALNUS GLUTINOSA (L.) GAERTN.
Authors: van DIJK C. , MERKUS E. 
Published: May 2006

SUMMARYA light‐ and electron‐microscopical study of the root‐nodule endophyte of Alnus gluttinosa (L.) Gaertn. was carried out to investigate the development of a spore‐like stage, here called the granule, in the life cycle of the endophyte. Comparison of granule‐rich and granule‐free root nodules showed that granule formation takes place via local transverse growth of thick endo‐phytic hyphae, giving rise to multicellular‘granulated bodies’differing in shape and size. Subsequently, the cells of these granulated bodies are transformed into granules by cell separation and ultrastructural changes, the most striking of which are cell‐wall thickening, reduction of the number of mesosomes, and increased density of the cytoplasm. Granule development takes place both intracellularly and intercellularly. Intracellularly produced granules are eventually liberated by the death of the host cell. Mature granules show a strong resemblance to spores of free‐living actinomycetes in their ultrastructure and behaviour.It is concluded that, in view of the terminology currently used in the description of members of the Actinomycetales, the term granule should be replaced by spore and thus the term granulated body by sporogenous body.
ECOLOGICAL PHYSIOLOGY OF THE LICHEN HYPOGYMNIA PHYSODES
Authors: FARRAR J. F. 
Published: May 2006

SUMMARYThe effect of constant saturation with water upon Hypogymnia physodes for periods of up to 7 days was investigated in either light or dark, at either 20°C (representative of most laboratory experiments on lichen physiology) or 5°C (more representative of field conditions). In all cases the capacity for photosynthesis, phosphate uptake, and total polyol content declined over 7 days; the decline was greater at 20°C than 5°C, and usually greater in the dark than in the light. In general, both alga and fungus reacted similarly to the treatments.Previously fixed 14C mostly remained in the polyol pool during the treatments, with relatively little entering the insoluble fraction. The substantial loss of previously fixed 14C during 7 days saturation was almost entirely from the methanol soluble fraction. Within the insoluble fraction, there was also no loss of 14C during the 7‐day period if protein had been previously labelled with 14C‐leucine.Two other lichens, Xanthoria aureola and Peltigera horizontalis, also showed broadly similar declines to Hypogymnia physodes in various physiological characteristics.
ORIGIN OF INTERNODAL AIR SPACES IN HIPPURIS VULGARIS L.
Authors: KORN ROBERT W. 
Published: May 2006

SUMMARYAir spaces in the internodal regions of Hippuris vulgaris L. are separated from each other by a single file of cells, a feature which permits a geometric description of their arrangement according to the number of adjacent air spaces. This number ranges from four to eight with an average of 6.04 ± 0.29. Vertices between three adjacent air spaces are composed of either an hexagonal central cell from which three cells radiate outward, is called a cell vertex (CV) and has a frequency of 0.453, or by three pentagonal cells with a common wall point, is called a wall vertex (WV) and has a frequency of 0.547. Air spaces arise from certain three‐rayed vertices by wall separation and a subsequent series of unequal cell divisions in which the ends of cell plates only attach to walls bordering air spaces.A paper‐pencil model was devised in order to identify the critical steps of this ontogenetic sequence. One important ordering process in generating this pattern of air space arrangement is an alternating selection of vertices around cell and cell groupings which will become air spaces. A second ordering feature is the positioning of cell plates in order that they attach only to facets bordering air spaces. This model produces the features of spaces separated by a single row of cells and the ratio of the two types of vertices cited above but only approximates the number of cells around a space. It has been demonstrated here that walls of a cell can influence each other through some type of inhibition, and as a morphogenetic mechanism in general, it may play an important role in other cases of tissue development.
BREEDING SYSTEM AND POPULATION STRUCTURE OF ARMERIA MARITIMA (MILL.) WILLD. ON A ZINC‐LEAD MINE
Authors: LEFÈBVRE C. 
Published: May 2006

SUMMARYUsing marker genes the breeding system (mating type gene) and the structure (hairy stalk gene) of a zinc–lead mine population of Armeria maritima, an insect‐pollinated plant, was studied in situ. Strict allogamy occurs in the population in nature although this population shows self‐fertility in experimental garden plots. The population is divided into sub‐populations differing in the frequency of hairy stalked individuals. Gene flow between these sub‐populations is very low (if any) so that the differences, which are likely to have originated by chance, remain constant through generations.
WOUND REPAIR IN YAM TUBERS: PHYSIOLOGICAL PROCESSES DURING REPAIR
Authors: PASSAM H. C. , READ S. J. , RICKARD J. E. 
Published: May 2006

SUMMARYWhen bisected or deeply cut by knife, yam tubers (Dioscorea rotundata Poir.) undergo a process of wound repair which comprises: (a) an immediate migration of starch to the cut surface (within 5–10 h of injury); (b) after 2–3 days, the formation of a suberized layer beneath the cut surface; (c) after approx. 5 days, the production of periderm (cork). Concurrent with these structural changes are a rapid increase in the rate of respiration, a hydrolysis of starch to sugar and an increase in invertase activity. Metabolic activity remains high until healing is complete. When tubers are wounded by surface abrasion or severe bruising these wound‐healing processes do not occur. Weight loss and respiratory activity of bruised tubers remain high until decay. Abrasions or superficial cuts are not sealed off by a layer of periderm, and in consequence a prolonged loss of moisture content and an increased susceptibility to pathogen attack result.
THE ESTIMATION OF PLANT ORGANIC ACIDS BY GAS‐LIQUID CHROMATOGRAPHY
Authors: PHILLIPS R. D. , JENNINGS D. H. 
Published: May 2006

SUMMARYA gas‐liquid chromatographic technique for the rapid separation of organic acids as silyl derivatives is described. The procedure involves two successive analyses using different stationary phases, one of which separates citric and isocitric acids directly as silyl derivatives. This avoids the tedious conversion of isocitric acid to the lactone. The chromatographic analysis of the major acids in a plant with Crassulacean acid metabolism can be completed in under 20 min.
THE ONTOGENY OF THE VASCULAR CAMBIUM IN HOHERIA ANGUSTIFOLIA RAOUL.
Authors: BUTTERFIELD B. G. 
Published: May 2006

SUMMARYThe procambium in Hoheria angustifolia (Malvaceae) develops behind the apical meristem as an almost complete cylinder of meristematic cells. Differentiating protophloem strands are separated by narrow interfascicular sectors. These sectors also interrupt the procambial cylinder. The first protoxylem elements differentiate as discrete bundles to the inside of a number of protophloem strands and remain separated from them by an actively dividing procambial cylinder six to eight cells wide. Periclinal divisions also occur in the interfascicular sectors so that by the centre of the first internode below the shoot tip the procambium forms a complete cylinder. In this way the short cells of the interfascicular sectors become transformed into primordial ray intitials. Repeated periclinal division in the procambium leads to the radial seriation of its cells. Subsequent differentiation of the derivatives produces complete cylinders of metaxylem and metaphloem by the third internode.Internodal elongation ends by the fifth or sixth internode below the shoot tip after which the transverse ended primordial fusiform cells of the procambium become transformed into fusiform cambial cells with pointed tips. Except during ray formation, transverse division ceases and the non‐storeyed cambium gradually acquires a storeyed appearance in tangential view by repeated radial longitudinal divisions accompanying radial growth. The first new rays appear about the seventh internode.The transition from procambium to cambium in Hoheria angustifolia is a gradual one with the meristem acquiring some cambial characteristics before and some after internodal elongation has ceased.
TRANSLOCATION OF LABELLED ASSIMILATE IN POTASSIUM‐DEFICIENT PLANTS
Authors: THROWER STELLA L. , THROWER L. B. 
Published: May 2006

SummaryThe pattern of distribution of labelled assimilate, and the amounts exported from a source leaf, have been investigated in eleven species of plants growing in a potassium‐deficient medium. Comparison with the same parameters for plants growing with full nutrient complement showed no detectable differences in either the pattern or quantity of photosynthate that was translocated.
EFFECT OF POTASSIUM ON PROLINE ACCUMULATION IN CUCUMBER COTYLEDONS
Authors: UDAYAKUMAR M. , RAO S. RAMA , PRASAD T. G. , SASTRY K. S. KRISHNA 
Published: May 2006

SummaryFree proline accumulation in excised cucumber cotyledons and in leaves of cowpea seedlings increased after treatment of the plants with potassium chloride. In excised cucumber cotyledons there was less K‐induced proline accumulation in the presence of benzyladenine (BA) and free proline disappeared when cotyledons were transferred to BA. Cycloheximide increased the proline content in the tissue when present alone or in combination with BA and/or K. Under simulated water stress, the proline content increased but the increase was greater in cotyledons also treated with KCl. In cowpea seedlings, reduction in relative water content (RWC) under stress was much less in seedlings treated with additional amounts of KCl, and their praline content was also high. There appears to be thus a relationship between K content, praline accumulation and water content of the leaves.
HIGH TEMPERATURE REQUIREMENT FOR AFTERRIPENING IN SEEDS OF WINTER ANNUALS
Authors: BASKIN JERRY M. , BASKIN CAROL C. 
Published: May 2006

SummaryTemperature requirements for afterripening were investigated in seeds of the winter annuals, Stellaria media, Valerianella umbilicata and Phacelia purshii. Seeds were incubated during the summer dormancy period at nine temperature regimes on wet and alternately wetted and dried sand. Low temperatures (5, 10, 15, 15/6 and 20/10°C) inhibited and high temperatures (20, 25, 30/15 and 35/20°C) promoted afterripening of the seeds. Temperatures (5 and 10°C) which promote afterripening in species with a chilling requirement (e.g., summer annuals) almost completely prevented afterripening of the three winter annuals. Thus, although dormancy is an adaptation of winter annuals to their hot, dry summer habitat, the summer temperatures are required for afterripening of the seeds.
THE PHYSIOLOGY OF NEOSPONGIOCOCCUM OVATUM DEASON
Authors: KHADKE VIMAL , MERRETT MICHAEL J. 
Published: May 2006

SummaryBy enrichment culture and conventional microbiological techniques the dominant alga of sewage trickle filters was obtained in axenic culture and identified as Neospongiococcutn ovatum Deason. A wide range of carbon compounds failed to support heterotrophic growth or alter the mean generation time or final cell yield in the light. The rate of photosynthetic carbon dioxide fixation was also unaffected by the growth conditions. The enzymes of the tricarboxylic acid cycle were present at comparable specific activity in cell extracts, but significant uptake of [14C]‐acetate or [14C]‐glycollate was not detected. It is suggested that impermeability to exogenous compounds may be an advantage in a toxic environment.
THE HORMONAL CONTROL OF CELL WALL TURNOVER IN PISUM SATIVUM L.
Authors: GILKES N. R. , HALL M. A. 
Published: May 2006

SUMMARYA tentative structure for the polysaccharides of pea epicotyl cell walls is presented. The turnover of these polysaccharides has been followed by gravimetric and pulse chase studies. It is suggested that an important effect of IAA is the promotion of turnover in certain wall hemi‐celluloses, notably xyloglucan; moreover, such turnover appears to be inhibited by kinetin. The relevance of these findings is discussed in terms of longitudinal and lateral cell expansion.