bluuebunny/crossref_metadata_2025_split huggingface dataset:
CARBOHYDRATE PHYSIOLOGY OF MYCORRHIZAL ROOTS OF BEECH
Authors: LEWIS D. H. , HARLEY J. L. 
Published: May 2006

SummaryMycorrhizal roots of beech absorb [14C]glucose, fructose and sucrose at rates some two and a half times faster than uninfected roots. In the latter, sucrose is synthesized from all three sugars despite the presence of an active surface invertase, clearly suggesting that uptake from sucrose involves prior hydrolysis. There is only a small incorporation into polysaccharides by uninfected roots, this being into structural polymers. In contrast, mycorrhizal roots synthesize principally trehalose and glycogen from glucose, and mannitol from fructose. Sucrose feeding results in synthesis of all three storage carbohydrates. Whatever sugar is supplied to mycorrhizas, host sugars incorporate little radioactivity and dissection shows that 70% of the activity, following long term glucose feeding, remains in the sheath and, of the 30% in the core, most is in fungal metabolites of the Hartig net. When fed separately, core tissue more closely resembles the behaviour of uninfected roots.From the totally different destinations of the two hexoses in mycorrhizas, it is concluded that the fungus, unlike host tissue, has a restricted ability to interconvert hexoses. From experiments with high specific activity [14C]glucose supplied to mycorrhizas in tracer quantities, it appears that alternative pathways of carbohydrate breakdown such as the pentose phosphate cycle and Entner‐Doudoroff scheme may possibly be operative in addition to glycolysis and so supplement the breakdown of sugars to the level of pyruvate.
LATE‐GLACIAL DEPOSITS AT BAGMERE, CHESHIRE, AND CHAT MOSS, LANCASHIRE
Authors: BIRKS H. J. B. 
Published: May 2006

SummaryInvestigations of deposits at the two sites disclose basal stratigraphic sequences characteristic of the Late‐glacial Period of north‐west Europe. The pollen analyses presented confirm that the deposits represent the Late‐glacial Period and extend into the early Post‐glacial. (The periods, which are described as Late‐glacial and Post‐glacial to conform with previous usage (Godwin, 1956) correspond to the Late‐Weichselian and Flandrian stages, respectively (West, 1963).) The low frequency of arboreal pollen during the Late‐glacial at both sites is a feature common to many sites in Western Britain. Amongst the plants recorded Cryptogramma crispa, Gentiana pneumonanthe, Saussurea alpina, Dicranum elongatum and D. spurium are the most notable.
ANATOMY AND THE TAXONOMIC SIGNIFICANCE OF GROSS VEGETATIVE MORPHOLOGY IN SENECIO
Authors: DRURY D. G. , WATSON L. 
Published: May 2006

SummaryThe well‐known arrangements of Senecio species appear to be based on inadequate data. Observations on leaf hairs, achene hairs, corolla venation, pappus structure and ovarian crystal form are presented for forty‐five species. A classification based on these features bears little resemblance to the conventional view of the genus, but its taxonomic soundness is strikingly supported by considerations of gross leaf morphology and habit.
CONTROLLED ENVIRONMENT STUDIES OF THE NATURE AND ORIGINS OF WATER DEFICITS IN PLANTS
Authors: MACKLON A. E. S. , WEATHERLEY P. E. 
Published: May 2006

SUMMARYDepression of water potential. δW (d.p.d.), in the leaves, transpiration and stomatal aperture were measured on Ricinus communis plants subjected to controlled levels of atmospheric evaporation in a climatological wind tunnel.It was found that the leaf δW of transpiring plants rooted in water took up a value of about 5 atm and remained unaffected by large changes in transpirational flux. When water was replaced by an osmoticum round the roots, leaf δW merely rose to approach the δW of the medium. These results indicate that root resistance plays little part in determining levels of leaf δW above 5 atm.However, an increase of transpiration rate led to a rise in the δW of the leaves in plants rooted in soil, and when the transpiration rate was lowered again leaf δW fell to near its original level. These results are interpreted on the hypothesis that the source of water deficits in plants lies primarily in the soil and not in the resistance to water flux offered by the roots. During a period of high transpiration, soil adjacent to the roots dries out due to the low water conductivity of the soil and this is reflected in a rise in δW in the leaves. Recovery of leaf δW occurs only when transpiration becomes low enough for the rate of water supply to the root zone to exceed the rate of absorption by the plant.This hypothesis is supported by preliminary measurements of soil δW. During a period of rapid transpiration the soil δW in the root zone rose above that in the surrounding root‐free soil. On a return to low transpiration conditions the soil δW in the root zone fell to the level of the surrounding soil again.
QUIESCENT CENTRE OF THE PRIMARY ROOT OF GLYCINE MAX
Authors: MIKSCHE J. P. , GREENWOOD M. 
Published: May 2006

SummaryThe quiescent centre of Glycine max was observed to change in size at various times after sowing. It increases in size during early development, then decreases with a corresponding reduction of the cell population of the root. Delimitation of quiescent centre boundaries is difficult in view of dramatic changes in size of regions of non‐DNA synthesis within the primary root.
STUDIES IN THE LENTIBULARIACEAE
Authors: FAROOQ MOHD , SIDDIQUI SAEED A. 
Published: May 2006

SummaryThe development of endosperm in Utricularia vulgaris var. americana conforms to the Scutellaria type of Schnarf (1917). Binucleate micropylar and chalazal endosperm haustoria are present. An accessory haustorial cell may differentiate adjacent to the chalazal haustorium. Sometimes the micropylar haustorium may be trinucleate. Occasionally the development of endosperm takes place by transverse divisions. In such cases the chalazal haustorium is usually uninucleate and the entire micropylar endosperm chamber differentiates as the micropylar haustorium.
STUDIES OF THE BALLISTICS OF ASCOSPORES
Authors: WALKEY D. G. A. , HARVEY R. 
Published: May 2006

SummaryThe ballistics of horizontal spore discharge in fifteen species and two varieties of Ascomycetes have been studied. An apparatus for measuring horizontal discharge is described and formulae derived for the volumes of irregularly shaped spores. The average and maximum distances of discharge for the selected fungi are recorded and include maximum ranges of more than 50 cm for Podospora fimiseda and the 64‐spore variety of P. decipiens.An analysis of the relationship between the average distance of horizontal discharge and projectile size shows that the formula d=Kr2 does not hold true for comparisons between a large number of unrelated species. If, however, only closely related species, such as those of the genera Podospora and Sordaria, are considered then considerable agreement with the formula is observed.If, in a single species, the relationship between size and distance of discharge of various sizes of spore‐projectiles is analysed, the results are in accordance with the formula d = Kr2 only if there is relatively high separation of the full spore complement into projectiles of different sizes. It is suggested that deviation from the formula occurs because the initial velocity of discharge is not constant for all projectiles.
ANALYTICAL STUDIES OF THE GROWTH OF THE ETIOLATED SEEDLING OF AVENA SATIVA
Authors: CAUSTON D. R. , MER C. L. 
Published: May 2006

SummaryObservations have been made of cell numbers per column and the distribution of the cell length along the mesocotyl. Mathematical expressions are then derived from the calculated curves of best fit for the rate of cell production and for the mean cell length in the first millimetre of the mesocotyl below the coleoptilar node. Further expressions are deduced for mean cell length in the meristem, for the total length of the meristem, and for the number of meristematic cells present in a single column. It is now possible to describe accurately the activity of the mesocotyl meristem in the untreated plant, and so determine the effects of carbon dioxide.Considering the entire meristem, the effect of carbon dioxide is to prolong and slightly enhance cell production. This comes about through a delay in elongation of the vacuolating dividing cells. In addition carbon dioxide appears to depress slightly the potential level of mitotic activity’ of a cell of a given length or age, but this effect is more than made up for by the increase in the number of dividing cells present.
THE ABSORPTION AND TRANSLOCATION OF PHOSPHORUS BY SEEDLINGS OF HORDEUM VULGARE (L)
Authors: CROSSETT R. N. , LOUGHMAN B. C. 
Published: May 2006

SummaryMeasurements were made of the absorption of 32P and its movement into the shoots of barley seedhngs growmg in millimolar phosphate nutrient solutions. The rate of movement of 32P into the shoot increased during the first 4–6 hours of absorption but thereafter remained constant. When an identical inactive nutrient solution was substituted for one labelled with 32P movement of radioactivity into the shoot continued for only 4–6 hours, the amount moving being independent of the length of the preceding absorption period and hence the amount of 32P in the root. The kinetics of 32P movement following such a change were examined. 32P was applied to the tips of roots growing in inactive nutrient solutions and radioactivity measured along the length of the root. An analysis was made of the chemical compounds in which 32P was found and a rough estimate made of their turnover rates.It was concluded that 32P entering the root is either accumulated in it, as orthophosphate, or mixes with a small part, called the root pool, of the phosphorus in the root before moving into the shoot. It wa suggested that the pool lies outside the outside the vascular system and that the acid‐soluble organic phosphorus compounds of the root are in dynamic equihbrium with it.
CHEMO‐ORGANOTROPHIC GROWTH OF XANTHOPHYCEAN ALGAE
Authors: CASSELTON P. J. 
Published: May 2006

SummaryA number of algae were tested for their ability to grow in the dark when supplied various organic substrates. Glucose was utilized by Chloridella neglecta, Botrydiopsis arhiza, Chloro‐closter solani, Bumilleriopsis peterseniana and Heterococcus caespitosus but not by ViscJieria stellata and Pleurochloris commutata. Chloridella neglecta was also able to utilize galactose and Chlorocloster solani galactose, mannose and fructose. The utilization of maltose, sucrose, xylose, ribose, mannitol, acetic acid, citric acid, succinic acid and lactic acid by any of the algae was not detected.Chromatographic separation of the pigments of the algae suggested that all were members of the Xanthophyceae with the exception of C. solani. It is suggested that C. solani is a member of the Chlorophyceae since chlorophylls a and b were detected.An apparendy greater growth in the dark by C. solani utilizing fructose rather than glucose was attributed to a differential change in pH of the medium containing the sugars during autoclaving.
MORPHOLOGY OF THE FERTILE LEAVES OF THE LOMARIOPSIDACEAE, WITH SPECIAL REFERENCE TO THE VENATION
Authors: NAYAR B. K. 
Published: May 2006

SummaryFertile pinnae of thirty‐one species of the eight genera of Lomariopsidaceae studied have the lamina variously reduced, in some cases to narrow wings on either side of the midrib. The lamina is either broad, thin, and with the venation conspicuous on the surface, or narrow, fleshy, and with hidden venation. The mesophyll is undifferentiated and consists of thin‐walled parenchyma which possesses collapsible walls in some species. Intercellular air spaces are inconspicuous in most species. The epidermal cells are usually thin‐walled, chlorophyllous and dorsiventrally flattened. The midrib has two or three vascular strands which unite into one in the anterior half of the lamina. Distinct sclerenchyma tissue is absent: a few layers of thick‐walled hypodermal cells occur in the midrib region in some.Venation of the fertile pinna is almost similar to that of the sterile pinnae in Bolbitis and Lomagramma (both reticulate), and in Egenolfia, Elaphoglossum and Thysanosoria (all free‐veined). The fertile pinnae of Arthrobotrya, Lomariopsis and Teratophyllum usually possess a reticulate venation, though the sterile pinnae are free‐veined. A set of special veins supplying the sporangia is found in addition to the ‘normal’ venation in many species except Elaphoglossum and Thysanosoria. The special venation is variously developed in the different species of each genus; it consists of a set of veins close to the lower epidermis of the lamina and connected to the ‘normal’ veins at intervals: in some cases the special veins form extensive reticulations independent of the ‘normal’ venation. The two sets of veins are at different planes, one above the other. The special venation is not connected directly to the midrib and often has a longitudinal vein running parallel to the midrib on either side.In all genera, except Thysanosoria which has discrete sori restricted to the vein tips, sporangia are acrostichoid in distribution. They are of the common leptosporangiate type. The sporangial stalk is slender and long in all, except Lomagramma and Lomariopsis in which it is short and stout. The stalk is three cells thick, the third row developed secondarily as a protrusion of the basal wall cell of the capsule in continuation of the stomium. Distinct paraphyses are absent, except in Arthrobotrya, Lomagramma and Teratophyllum.The spores are bilateral, monolete and ranging in size from 22 × 33 μ(Bolbitis spp., Elaphoglossum spp.) to 90 × 125 μ(Lomariopsis intermedia). The exine is smooth except in Lomagramma, Thysanosoria (both granulose) and Lomariopsis spp. (spinulose). Lomagramma and Thysanosoria are perine‐less; all others are perinate, with the perine bearing characteristic reticulate ornamentation in all except Bolbitis and Elaphoglossum.
A SECTORIAL ENTIRE‐PINNATE LEAF CHIMERA IN THE POTATO VARIETY MAJESTIC
Authors: HOWARD H. W. 
Published: May 2006

SummaryThe docken‐ (entire‐) leaf sport in the potato variety Majestic is a periclinal chimera in which L2 and L3 have a mutation for entire leaf but in which L1 has the unchanged genotype for normal pinnate leaves. A shoot was found after X‐ray treatment which had pinnate, entire and sectorial leaves. The arrangement of leaves on this shoot would fit a hypothesis postulating only two initial cells for L2. The L2 of leaf primordia may trace back to only two cells at a time when the L2 has about sixteen or thirty‐two cells as seen in transverse section.
THE OCCURRENCE OF LIVING AND SUB‐FOSSIL REMAINS OF BETULA NANA L. IN UPPER TEESDALE
Authors: HUTCHINSON T. C. 
Published: May 2006

SummaryA small colony of the arctic‐alpine dwarf birch, Betula nana, has been discovered in Upper Teesdale, this being the only English station for the species. It is elsewhere in Britain confined to the Scottish Highlands. The plant associations with which the species occurs throughout its range are of two types, tundra vegetation in the north, and sub‐alpine dwarf shrub vegetation in the south of its range. In Teesdale the species is confined to the sub‐alpine dwarf shrub type although an open tundra type is also present. Sub‐fossil leaf remains of B. nana have been found in Teesdale close to the living colony, in a fen peat. The leaf remains are associated with deposits later than the commencement of Zone Vila, thus indicating that the species has probably been continuously present in Teesdale since Atlantic times. The Late‐glacial finding of the species in Lower Teesdale suggests that the present colony may have a continuity in Upper Teesdale from Late‐glacial times to the present day (approximately 12,000 years).
SOME EFFECTS OF ADENINE ON GROWTH, RESPIRATION, ADENOSINE DIPHOSPHATE AND TRIPHOSPHATE CONCENTRATIONS IN PLANT TISSUES
Authors: MERRETT M. J. , HANDOLL C. 
Published: May 2006

SummaryConditioned callus tissues of Nicotiana tabacum type White Burley variety Judy's Pride were grown on basal media supplemented with purine or pyrimidine bases. A substantial increase in ATP concentration in the tissues occurred only with adenine. The accumulation of ATP was not the result of growth inhibition and the ATP concentration of the tissues was increased by adenine concentrations which did not inhibit growth. When exogenous adenine was added to tissues grown on basal media, the respiration rate was not increased. The respiration rate of tissues grown on adenine‐containing media was the same as that of tissues grown on basal media. Although adenine increased the total amount of ATP in the tissue, the ADP concentration was unatfected. Dinitrophenol stimulated the respiration rate and this, taken together with the unaltered ADP concentration, suggests that the availability of phosphate acceptors still controls the respiration rate of tissues grown with adenine in the medium. The response of tobacco callus tissue to adenine infected with tobacco mosaic virus was similar to that of non‐infected tissue.
STUDIES IN THE RESPIRATORY AND CARBOHYDRATE METABOLISM OF PLANT TISSUES
Authors: BARKER J. , KHAN M. A. A. , SOLOMOS T. 
Published: May 2006

SummaryThe changes of glucose‐6‐phosphate, fructose‐6‐phosphate, fructose diphosphate, dihydroxy‐acetonephosphate, 3‐phosphoglycerate, 2‐phosphoglycerate, phosphoenolpyruvate, adenosine triphosphate, adenosine diphosphate, adenosine 5′‐monophosphate and oxidized co‐enzyme I were determined in shelled green peas held in air and in nitrogen. In anoxia 3‐phosphoglycerate, 2‐phosphoglycerate, phosphoenolpyruvate, adenosine triphosphate and oxidized co‐enzyme I, each decreased markedly to new steady levels after ahout 15 minutes; except in one experiment, adenosine diphosphate increased markedly for about 15 minutes. Similarly, the development of the Pasteur effect in shelled green peas is rapid, i.e. less than 30 minutes (Wager, 1961). In contrast, glucose‐6‐phosphate decreased for some 24 hours of anoxia, while fructose diphosphate and dihydroxyacetonephosphate first increased, then decreased and finally might rise again.From our results, the metabolic fate of adenosine diphosphate appears to be of primary importance in controlling the rate of glycolysis. Thus, with transfer to anoxia, the most consistent ehange in the glycolytic intermediates is the rapid decrease in the contents of 3‐phosphoglycerate and of phosphoenolpyruvate. One explanation of these changes is that the pyruvate kinase reaction is accelerated, due possibly to a local increase of adenosine diphosphate. With a faster pyruvate kinase reaction, the additional adenosine triphosphate formed might hasten glycolysis and this faster rate might then be maintained.The fact that, in anoxia, smaller amounts of adenosine triphosphate support a higher rate of glycolysis than in air has suggested that in air this nucleotide is not readily available to the sugar‐phosphorylating enzymes. Similarly, the present results could be explained if the glycolytic enzymes were mainly confined to an organized structure showing a difference in accessibility for adenosine di‐ and triphosphates.On the other hand, our results may be related to a feed‐back mechanism not yet specified. How important such mechanisms might be is shown by the complex effeets of adenosine nucleotides, of inorganic phosphate and of other compounds on the activity of phospho‐fruetokinase in vitro.The changes m anoxia, stated above, of glueose‐6‐phospliate, of fructose diphosphate and of dihydroxyacetone phosphate are considered.A difference in the metabolic fate of adenosine triphosphate in aerobie and anaerobie conditions is described. The difference is readily explained in terms of a glyeolytic structure but could also be due to an acceleration of the hexokinase and phosphofructokinase reaetions in anaerohiosis either by activation or by a decrease in the inhibition of these enzymic stages.While the existence of a glycolytic structure has not been proved beyond doubt, evidence that such a strueture may exist is accumulating.
NATURAL SELECTION IN AN ARTIFICIAL POPULATION OF SORDARIA FIMICOLA
Authors: COX B. S. , PARRY ELIZABETH M. 
Published: May 2006

SummaryA strain of Sordaria fimicola carries a reciprocal translocation which results in the formation of aborted ascospores in perithecia hybrid between this and the normal strain. Petri‐dish populations of the two strains were propagated by ascospore samples and the frequency of hybrid perithecia formed in each generation was followed. It was found that there was a rapid decrease in their frequency over eight generations. This was accounted for by the progressive elimination of normal nuclei by natural selection. Reasons for this selection are discussed.
A CHROMOSOMAL TRANSLOCATION IN SORDARIA FIMICOLA AND IRREGULAR SEGREGATION OF CHROMOSOMES
Authors: COX B. S. , GILL J. J. B. 
Published: May 2006

SummaryA strain of Sordaria fimicola has been isolated which has normal black spores with 98% viability, but which, when crossed with wild‐type Sordaria, gives rise to aborted spores in the majority of asci in hybrid perithecia. The pattern of spore abortion is consistent with the hypothesis that the abnormal strain contains a reciprocal translocation and this is supported by the cytological data and also by tetrad analysis data. Consideration of a few exceptions in the tetrad analysis and in the chromosome preparations suggests that irregular segregation following a failure of pairing may sometimes occur at meiosis.
CO2 FIXATION, ORGANIC ACIDS AND SOME ENZYMES IN GREEN AND COLOURLESS TISSUE CULTURES OE KALANCHOË CRENATA
Authors: MCLAREN L , THOMAS D. R. 
Published: May 2006

SummaryMeasurements of gaseous exchange between green callus tissue cultures of Kalanchoe crenata and air showed that photosynthesis occurred in the green callus. Feeding experiments with 14CO2 showed that 14C was incorporated by green callus into sugars and sugar phosphates in the light, and some 14C was incorporated into organic acids. Organic acids were the main products of dark fixation of 14CO2 by green callus but no activity was detected in sugars or sugar phosphates. The products of 14CO2 fixation in colourless callus were primarily organic acids both in the light and dark and no activity was detected in sugars or sugar phosphates.Green callus did not show a diurnal fluctuation of acid content. This, coupled with the observations that green callus did not show a net fixation of CO2 in the dark, suggested that the green callus did not exhibit crassulacean acid metabolism. Green callus, however, contained greater quantities of malate, citrate and isocitrate than did colourless callus. Enzyme assays suggested that the presence of PEP carboxylase in green callus and its absence in colourless callus might in part contribute to the higher acid levels of green callus.
EVOLUTION OF THE ENDOSPERM IN PROTEACEAE
Authors: RAO C. VENKATA 
Published: May 2006

SummaryThe endosperm development in several genera of both sub‐families of Protcaceae is studied. The scanty nuclear endosperm and large persistent nucellus (perisperm) seem to represent the most primitive conditions. The general absence of endosperm haustoria in Proteoideae and their universal occurrence in Grevilleoideae are attributed to the different methods of the post‐fertilization growth of their ovules. The probable factors which led to the origin of the endosperm haustorium in Grevilleoideae are suggested and the trends in its evolution are outlined.