bluuebunny/crossref_metadata_2025_split huggingface dataset:
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: POWELL CONWAY LL. 
Published: May 2006

SUMMARYOnions were preinfected with seven Endogone spore types and red clover with five spore types and then grown in P deficient, 32P labelled soils. P uptake was much greater in most mycorrhizal plants than in controls. Specific activities of absorbed P were almost identical in all mycorrhizal and control plants.
TRANSLOCATION OF PHOSPHATE IN MOULD MYCELIA
Authors: EZE J. M. O. 
Published: May 2006

SUMMARYColonies of Phycomyces blakesleeanus, Rhizopus nigricons, Mucor mucedo and M. hiemalis were grown so that the colony was in contact with two different blocks of media; one block of medium was labelled with 32P‐phosphate. When the total phosphate concentration in both blocks was the same, no lateral translocation of 32P occurred, but when the phosphate concentrations in the two blocks differed, 32P was translocated in the direction of the phosphate concentration gradient.
TRANSPORT OF INDOLEACETIC ACID IN PLANT CELLS IN RELATION TO pH AND ELECTRICAL POTENTIAL GRADIENTS, AND ITS SIGNIFICANCE FOR POLAR IAA TRANSPORT
Authors: RAVEN J. A. 
Published: May 2006

SUMMARYThe distribution of IAA between the vacuole and the bathing solution in Hydrodictyon africanum is consistent with passive entry of undissociated IAA and passive efflux of both undissociated IAA and of IAA, with PIAA (permeability coefficient)* about io−3 cm s−1 and PIAA‐ about io‐6 cms −1. The involvement of IAA− in the efflux results from the inside‐negative P.D. between the medium and the vacuole. The cytoplasm is at a higher pH than either the vacuole or the bathing solution used in most experiments; this is maintained by active H+ efflux at the plasmalemma, and active influx at the tonoplast. In this situation the efflux of IAA− is further promoted by the increased concentration of IAA− in the relatively alkaline cytoplasm. Thus the apparent active efflux of IAA from these cells can be explained in terms of passive driving forces of concentration and electrical potential acting on IAA and IAA−, with the distribution of these two species dictated ultimately by PIAA, PIAA‐ the pH of the various compartments and the electrical potential difference between them. If PIAA/PIAA‐ were larger at the apical than at the basal end of coleoptile cells, such an effect could explain polar IAA transport, with metabolic energy being used only to maintain the relative permeabilities to the two species, the pH gradient and the electrical gradient.
MORPHOGENESIS OF AERIAL SCLEROTIA OF COPRINUS LAGOPUS
Authors: WATERS H. , MOORE D. , BUTLER R. D. 
Published: May 2006

SUMMARYAerial sclerotia originated from intercalary cells of aerial hyphae. Initially only a single cell was involved. Repeated branching from the initiation point formed the sclerotium initial which was a more or less spherical mass of undifferentiated, radially arranged cells. Accumulation of glycogen in cells towards the centre of the initial marked the commencement of maturation. Cells of the central (medullary) region went through a differentiation process which involved first a heavy accumulation of glycogen; the glycogen was then mobilized, its reduction in concentration being exactly correlated with the formation of a thick, hyaline, secondary wall. As the medulla developed, differentiation of localized areas of cells just within the margin of the initial occurred to form the protective rind layer. Wall thickening in rind cells was not preceded or accompanied by glycogen accumulation. Strains which failed to produce sclerotia behaved as stable variants, sclerotium non‐production segregating as a single gene. Four such genes were recognized and some linkage information obtained.
AN ALBINO MUTANT IN PLANTAGO INSULARIS REQUIRING THIAMINE PYROPHOSPHATE—ROLE OF TPP IN PIGMENT AND PROTEIN SYNTHESIS
Authors: MICHAEL SANDRA D. , SPURR ARTHUR R. 
Published: May 2006

SUMMARYSeedlings of Plantago insularis were grown in darkness for 5 days and then exposed to white light for 24 h. At the beginning of the light period some plants were treated with thiamine pyrophosphate (TPP). Light exposure caused a marked development of both chlorophyll a and b in the normal (al+/al+) plant, but only a slight formation of chlorophyll in the mutant (al/al) TPP plus light induced the formation of chlorophyll a and b in the mutant to near normal levels. Light alone increased the level of carotenoids in the normal type, but not in the mutant; but TPP plus light increased the carotenoids in the mutant to near normal. Albinism in Plantago is due, in part, to a deficiency in TPP and a consequent deficiency in chlorophyll and carotenoid pigments.Acid‐soluble nitrogen was distinctly lower in the albino mutant than in normal plants, but increased in the mutant after treatment with TPP and exposure to light. Exposure of dark‐grown normal seedlings to light alone caused a marked increase in acid‐insoluble nitrogen. Recovery in the mutant appeared to be at the expense of the soluble nitrogen fraction, and is attributed to the synthesis of chloroplast proteins. The light‐yellow mutant grown in the dark became bleached on exposure to light, yet a moderate increase in nitrogen occurred during exposure, indicating that some protein synthesis is independent of chlorophyll and carotenoid development in the plastids. A pathway initially involving TPP appears to be affected by light in the formation of chloroplast proteins.
ANALYSIS OF COMPOSITION OF RESPIRATORY GASES IN WOODY STEMS BY MASS SPECTROMETRY
Authors: CARRODUS B. B. , TRIFFETT A. C. K. 
Published: May 2006

SUMMARYA method of analysis of small volumes of gases from bulky plant organs, using mass spectro‐metry, is described. Results obtained from woody stems of Acacia mearnsii indicate that the most actively metabolizing tissues exist in an environment whose gaseous component is almost exclusively carbon dioxide. This observation is consistent with previous observations on the effect of carbon dioxide on the formation of compounds characteristic of heartwood in A. mearnsii.
THE CESSATION OF MITOSIS AT THE MARGINS OF A ROOT MERISTEM
Authors: CLOWES F. A. L. 
Published: May 2006

SUMMARYThe mean rates of mitosis for all cycling cells and the cell‐doubling times have been measured independently by pulse‐labelling and by blocking the cell cycle and then used to measure the fraction of cycling cells along the meristem of primary roots of Zea mays. The attenuation of mitotic activity that occurs towards the proximal and distal margins of the meristem is due solely to a reduction in growth fraction and not at all to a change in the rate of cycling. This is contrasted with the situation in the quiescent centre of the meristem where the low rate of cell formation results from both a reduction in growth fraction and prolongation of cell cycles. DNA synthesis outside a normal mitotic cycle begins to occur in regions containing cycling cells on both sides of the quiescent centre.
HYBRIDS BETWEEN LOLIUM PERENNE AND FESTUCA PRATENSIS
Authors: GYMER P. T. , WHITTINGTON W. J. 
Published: May 2006

SUMMARYMeiosis and fertility have been studied in natural and artificial hybrids between Lolium perenne and Festuca pratensis. In diploids, meiosis was normal except for a few desynaptic hybrids, but pollen fertility was very low, probably because of genie or chromosomal unbalance. In triploids the extent of homoeologous pairing varied, as did fertility.Several categories of synthetic hybrids were compared with their natural equivalents, and it is considered most likely that all the natural hybrids studied were F1 plants, although there were some discrepancies. Those that were triploid were probably produced by unreduced pollen grains.
SOME ASPECTS OF POLLINATION ECOLOGY OF ARMERIA MARITIMA (MILL.) WILLD. IN BRITAIN
Authors: EISIKOWITCH DAN , WOODELL STANLEY R. J. 
Published: May 2006

SUMMARYPollen and stigmata of Armeria maritima are very tolerant of sea water, maritime plants showing greater tolerance than those from an inland serpentine site. After pollination, sea water impairs pollen germination only briefly, whereas distilled water adversely affects pollen tube production. The tolerance of pollen to sea water is associated with the relative humidity of the air in a way not fully understood. Bumblebee behaviour in an area of saltmarsh, dune and shingle appears to be affected by the bending of inflorescence stalks and consequent deposition of bees on wet ground. The bees’ behaviour results in restriction of gene flow between adjacent populations in different habitats.
POLLEN ANALYTICAL EVIDENCE FOR PREHISTORIC FOREST CLEARANCE IN THE UPLAND AREA WEST OF RISHWORTH. W. YORKSHIRE
Authors: BARTLEY DAVID D. 
Published: May 2006

SUMMARYA pollen diagram from blanket peat at about 410 m on Rishworth Moor in the Yorkshire Pennines is discussed with particular reference to forest clearance. The evidence suggests that there was relatively little clearance in the Neolithic and Bronze Age but considerable activity accompanied by pastoral and some arable agriculture occurred in the Iron Age. This intensive agriculture seems to have ended early in the Roman period, when there was a recovery of the woodlands. The sequence is dated by four radiocarbon assays and its significance is discussed in relation to the archaeological and historical data available.
STIMULATION OF PHOTOSYNTHETIC STARCH FORMATION BY SEQUESTRATION OF CYTOPLASMIC ORTHOPHOSPHATE
Authors: SHEU‐HWA CHEN‐SHE , LEWIS D. H. , WALKER D. A. 
Published: May 2006

SUMMARYPhotosynthetic starch formation in leaf discs of spinach beet and related species can be increased more than ten fold by the presence of exogenous mannose at 10−2 M. In these species, carbon from mannose is not incorporated into starch to a significant extent and the stimulation is believed to be an indirect effect resulting from the sequestration of cytoplasmic ortho‐phosphate as mannose phosphate. In species such as tobacco, there is substantial incorporation of carbon from mannose into starch and into soluble compounds other than mannose‐6‐phos‐phate.
THE ROLE OF THE COTYLEDONS IN FOUR ACER SPECIES AND IN FAGUS SYLVATICA DURING EARLY SEEDLING DEVELOPMENT
Authors: AMPOFO S. T. , MOORE K. G. , LOVELL P. H. 
Published: May 2006

SUMMARYStudies on seedlings of Acer negundo, A. platanoides, A. pseudoplatanus, A. pseudoplatanus‐atropurpureum and Fagus sylvatica showed that the smaller seeded Acers had a shorter lag period before the onset of rapid growth than the larger seeded Fagus. Relative growth rates and net assimilation rates were high during the early stages of seedling growth when cotyledons constituted the major proportion of the photosynthetic surface area indicating the importance of cotyledon photosynthetic activity. Acer negundo which had the lowest seed weight and the smallest initial cotyledon area of the four Acer species had the most rapid dry weight increase. It also had stomata on both upper and lower surfaces of the cotyledons in contrast to A. platanoides and A. pseudoplatanus which had stomata only on the lower surface. Although this difference in stomatal distribution could be an important factor in the higher photosynthetic rate and more substantial dry weight increases in A. negundo, it is suggested that the latter is due mainly to the more rapid rate of leaf production.
COTYLEDON PHOTOSYNTHESIS DURING SEEDLING DEVELOPMENT IN ACER
Authors: AMPOFO S. T. , MOORE K. G. , LOVELL P. H. 
Published: May 2006

SUMMARYThe major storage function of cotyledons of Acer negundo, A. platanoides and A. pseudoplatanus is completed shortly after seedling emergence. Cotyledon photosynthates are essential for the maintenance of leaf production and seedling dry weight increase during the first week after emergence. However, cotyledon photosynthesis is not essential for seedling survival. Initially, much of the photosynthate exported from the cotyledons moves into the developing first leaf pair. This is most marked in A. platanoides and A. pseudoplatanus. Later, as the requirement for cotyledon photosynthate declines, less is exported from the cotyledon, mostly to the hypo‐cotyl and roots. In A. negundo successive pairs of leaves are produced before the preceding pair have fully expanded and the cotyledons supply photosynthates to the latter in contrast to A. platanoides and A. negundo in which they are presumably supplied by the first leaf pair.Substantial losses of radioactivity occur from the seedlings after 14CO2 application to cotyledons of A. pseudoplatanus, mainly during the first 48 h; this coincides with the maximum rate of radiocarbon export from the cotyledon. It is suggested that these losses are due to respiration and that they probably take place from the whole seedling, not merely from the treated organ.
TRANSLOCATION OF LABELLED ASSIMILATE IN MORPHOLOGICALLY CONTRASTING COTTON PLANTS
Authors: BHATT J. G. 
Published: May 2006

SUMMARYIn normal cotton plants and in a variety with short fruiting branches, labelled assimilate was translocated to fruiting bodies on upper and lower sympodia when the sympodial leaf on the first node of the fourth sympodium was treated with I4C sucrose. Main stem leaves similarly treated, exported the assimilate to fruiting bodies only on the lower sympodia in the long‐branch variety whereas in the short‐branch variety, the assimilate also reached the upper sympodia. This higher efficiency of the main stem leaf in short‐branch cotton may be related to a reduction in the translocation path because of the particular spatial arrangement of its leaves and fruits.
ADVENTITIOUS ROOT INITIATION AND GROWTH IN RELATION TO OXYGEN SUPPLY IN GERMINATING RICE SEEDLINGS
Authors: KORDAN H. A. 
Published: May 2006

SUMMARYAdventitious root initiation and root growth occur in rice seedlings germinating under favourable environmental oxygen concentrations whereas rice seedlings germinating at low oxygen concentrations or under anaerobiosis form adventitious root primordia but show no visible adventitious root growth. Transferring the seedlings from unfavourable to favourable oxygen environments results in root growth. Thus the phenomena of adventitious root primordia initiation and of root growth differ profoundly with respect to their oxygen requirements.
THE ULTRASTRUCTURE OF COLLEMA TENAX, WITH PARTICULAR REFERENCE TO MICRO‐TUBULE‐LAKE INCLUSIONS AND VESICLE PRODUCTION
Authors: BOUSFIELD JOAN , PEAT ALANT 
Published: May 2006

SUMMARYAn ultrastructural study of the vegetative thallus of Collema tenax (SW). Ach, showed that although haustorial connections were absent, the mycobiont did occasionally penetrate the algal sheath material. Concentric bodies and mesosome‐like structures were characteristically found in the mycobiont.Normal and senescent blue‐green algal cells were found alongside unusual vesiculating cells. Vesicles from these latter cells are apparently produced by reverse pinocytosis of plastoglobuli. These vesicles were occasionally found in close juxtaposition to the fungal hyphae, after dissolution of the algal sheath, and the hypothesis is advanced that they may be implicated in lipid transfer.‘Microtubule‐like’structures were observed in the algal cells and their relationship to similar structures in free living Nostoc, other blue‐green algae, bacteria, algal and higher plant chloroplasts and to typical microtubules is discussed.The ultrastructure of fresh and rehydrated material was compared. There was no apparent difference in the ultrastructure of material which had been dried for 3 months and rehydrated and that of material which had been freshly fixed.
GROWTH OF LATERAL ROOT PRIMORDIA IN VICIA FABA L.
Authors: MacLEOD R. D. 
Published: May 2006

SUMMARYOver the 136 h period between the initiation of a lateral root primordium and its subsequent emergence as a secondary root, cell number, length and volume of the primordium tended to increase in a linear manner, each increase being closely correlated with the others. The corresponding rates of increase, however, when calculated for different stages of primordium development, fluctuated greatly. Thus, the rate of cell proliferation was high 10 h following anlage initiation, but was subsequently very low. The rates of increase in meristem volume and length were also high at an early stage of primordium development (28–45 h), but decreased to reach minimal values between 62 and 78 h before increasing again.These changes in rate are discussed with respect to the development of a cavity in the adjacent cortical tissues of the primary root. Such cavities, which are initiated as a result of mechanical pressure, begin to form when the primordium has attained a cell number of about 1490 and reach a maximum size when the primordium contains about 10,800 cells.
VARIATION WITHIN COMMON GROUNDSEL, SENECIO VULGARIS L.
Authors: ABBOTT RICHARD J. 
Published: May 2006

SUMMARYVariation within and between four populations of the highly plastic and ephemeral plant Senecio vulgaris L. has been evaluated for several quantitative characters in three environments and at four stages of development. The populations were from soils of high and low nutrient levels and in habitats of different degrees of exposure. There are significant differences between the means and phenotypic variances of populations for most characters but the degree of difference tends to change both in level and direction between environments and throughout development. However, there are some consistent differences and these seem closely related to the differences between habitats. Of special interest was the variation within populations where it emerged that samples of the populations from sites that were highly heterogeneous for exposure showed much more heritable variation for height and several other characters which might influence the expression of stature than samples from apparently homogeneous sites. It is suggested that though S. vulgaris is capable of showing a wide measure of phenotypic plasticity which could be of adaptive significance in the field, many differences between and within populations may in part be attributed to gene differences that are likely to have resulted from the action of natural selection.
ACTIVE INFLUX OF HEXOSE IN HYDRODICTYON AFRICANUM
Authors: RAVEN J. A. 
Published: May 2006

SUMMARYThe glucose analogue, 3‐O‐methyl glucose, is actively transported inwards at the plasmalemma of Hydrodictyon africanum. It is likely that a similar mechanism is operative for glucose influx, although demonstration of its active transport is complicated by an apparent coupling of the rates of glucose entry and metabolism. Active OMG Transport, and the influx and metabolism of glucose, need ATP. This ATP can be supplied, in order of increasing rates of the two processes, by fermentation, cyclic photophosphorylation, oxidative phosphorylation and by photo‐phosphorylation plus oxidative phosphorylation.
NUCLEOTIDE EFFECTS ON THE OXIDATION OF MALATE AND OXALOACETATE BY ARUM MITOCHONDRIA
Authors: WEDDING RANDOLPH T. , McCREADY CHRISTOPHER C. , HARLEY JOHN L. 
Published: May 2006

SUMMARYMalate oxidation by mitochondria prepared from stage γArum spadices is inhibited by ADP. When oxaloacetate is also present, the effect of ADP is to increase the rate of oxygen uptake to one well in excess of the rate with malate alone. Arum mitochondria cannot oxidize oxaloacetate alone, but when increments of ADP or other nucleotides are added with oxaloacetate, oxygen uptake begins and continues for an extended period at a constant rate. The rate is proportional to the amount of nucleotide added. The stimulation of oxaloacetate oxidation by nucleotides increases in the order AMP < ADP < ATP, and Mg2+, but not PO2−3, is required for the stimulatory effect of the nucleotide. These responses to nucleotides are thought to be occasioned by the role of these substances as effectors of an enzyme or enzymes concerned with the metabolism of malate and oxaloacetate rather than involving the phosphorylative capacity of the mitochondria because the results are independent of the presence or absence of uncoupling substances.
EFFECTS OF SULPHUR DIOXIDE ON BIOCHEMICAL ACTIVITY AND ULTRASTRURAL ORGANIZATION OF PINE NEEDLED CHOROPLASTS
Authors: MALHOTRA S. S. 
Published: May 2006

SUMMARYThe effects of aqueous SO2 on the ultrastructural organization of pine (Pinus contorta Dougl. var. latifolia Engelm.) chloroplasts and on their photosynthetic activity were determined under laboratory conditions. At aqueous concentrations of 100 and 500 ppm, SO2 caused swelling of thylakoid discs and disintegrated other intrachloroplast membranes, resulting in the formation of small vesicles (in older, matured tissues). Chloroplast structural injury was more pronounced in old tissues than in younger and more metabolically active tissues. The biochemical observations (Hill reaction activity) made on chloroplasts isolated from SO2‐treated pine needle segments are in good agreement with the cytological observations.
THE INFLUENCE OF LEAVES ON COTYLEDON PHOTOSYNTHESIS AND EXPORT DURING SEEDING DEVELOPMENT IN ACER
Authors: AMPOFO S. T. , MOORE K. G. , LOVELL P. H. 
Published: May 2006

SUMMARYThe photosynthetic contributions of the cotyledons and of leaf pair one to seedling growth of Acer and the interactions between them were studied using 14CO2. During early development the cotyledons of A. negundo, A. platanoides and A. pseudoplatanus exported photosynthates to the hypocotyl, roots and young expanding leaves. When the first pair of leaves began to export photosynthate, export from the cotyledons declined in A. negundo and A. pseudoplatanus and was directed increasingly to the roots and hypocotyl. As further leaf pairs were produced, the movement of photosynthates from the first leaf pair became increasingly basipctal (as occurred at an earlier stage for the cotyledons).The decline in total fixation in, and percentage export from, cotyledons of A. negundo and A. pseudoplatanus was shown to be due to the increase in other sources of photosynthesis (leaves) and a consequent reduction in the demand for cotyledon photosynthetic products. Removal of the expanded leaves resulted in an increase in cotyledon fixation and export and also a rapid, marked change in the direction of export. Thus, the cotyledons maintained a high potential for photosynthesis although this was realized later in seedling development only if other sources of photosynthetic products were removed. A. platanoides differed from the other two species in that there was an increase in export from both cotyledons and leaf pair one about 30 days after seedling emergence, coinciding with the production of leaf pairs two and three. Presumably these constituted a major sink which created a greater demand for photosynthetic products, thereby increasing fixation and export rates of the photosynthetic organs present.
ESTIMATION OF CAFFEINE, THEOPHYLLINE AND THEOBROMINE IN PLANT MATERIAL
Authors: JALAL M. A. F. , COLLIN H. A. 
Published: May 2006

SUMMARYA method for the combined estimation of caffeine, theophylline and theobromine in plant material is presented. The method involved a chloroform‐ammonia extraction, separation of the bases in the chloroform extract by thin layer or paper chromatography and finally estimation of the eluted bases by spectrophotometry. Good recoveries of all three compounds were recorded. The method was used to estimate the level of these compounds in tea, coffee beans and cocoa cotyledons.