bluuebunny/crossref_metadata_2025_split huggingface dataset:
ALTERNATIVES TO THE ASSESSMENT OF EARLYWOOD AND LATEWOOD IN DICOTYLEDONOUS TREES: A STUDY OF STRUCTURAL VARIATION IN GROWTH RINGS OF APPLE (MALUS PUMILA MILL.)
Authors: DOLEY D. 
Published: May 2006

SummarySeveral indices describing the variation in wood structure within growth rings of dicotyledon trees were examined in apple (Malus pumila Mill.) scions grafted on to four rootstocks of different vigour. The cross‐sectional dimensions of 9600 fibres and 7200 vessel elements were measured in each rootstock and scion combination. Indices incorporating lumen width and wall thickness of fibres varied more or less linearly across growth rings, so that assessment of latewood could be made only by selecting some arbitrary limit, which may not be suitable for all rootstocks. The patterns of variation in vessel lumen area within growth rings varied markedly between rootstocks, and gave no clear indication of the point in the ring at which latewood formation might begin. A less extensive study of the distribution of tissues in the xylem at five positions across a growth ring showed that there tended to be a prominent reduction in the proportion of vessels, and an increase in the proportion of fibres between 10 and 30% of the distance across the ring. It was concluded that the concept of earlywood and latewood is not helpful to fundamental studies of wood structure and formation, and that in industry, measurement of relevant properties, such as the density of wood or fibres, may be made as easily as the determination of proportions of earlywood and latewood, however these wood zones be defined.
CHANGING PATTERNS IN THE RESPONSE TO CYANIDE OF ARUM MITOCHONDRIA OXIDIZING MALATE AND OTHER SUBSTRATES
Authors: WEDDING RANDOLPH T. , McCREADY CHRISTOPHER C. , HARLEY JOHN L. 
Published: May 2006

SummaryOver a flowering season of 7 weeks, mitochondria from the spadices of Arum maculatum showed a progressive increase in the rate at which added malate was oxidized from less than 20 nmoles min−1 mg protein−1 to more than 700 nmoles min−1 mg protein−1. In the oxidation of succinate, α‐ketoglutarate and other substrates, much smaller differences in rate were found.Mitochondria oxidizing malate responded to the addition of high (3.8 HIM) concentrations of cyanide by stimulation when their initial rate of malate oxidation was low and by inhibition when it was high. Stimulation by KCN even with high concentrations did not increase the O2 uptake rate of young spadices to the level of mature ones.Associated with this alteration in response to cyanide was a reverse response to ADP. The early, slowly respiring mitochondria which were stimulated by KCN were often inhibited by ADP while the mitochondria from later spadices which were inhibited by KCN were usually stimulated by ADP.Similar variations in the relative rate of malate oxidation, response to cyanide and to ADP were observed in mitochondria prepared on the same day from spadices at different stages of development from the same location. In this case the change from young (β) to fully matured (ɛ) spadices approximately paralleled those from the early season to the end of the flowering period. The changes in malate metabolism of the spadix mitochondria were not solely related to stage of spadix development, however, since those from spadices at the same apparent developmental stage gathered over a 5‐week period also showed an increase in the rate of malate oxidation and a change in response to cyanide and ADP.Several types of evidence—effects of additional washing of the mitochondria, response to additions of oxalacetate and pyruvate, response to inhibitors of cytochrome oxidase other than KCN, assay of oxalacetate concentration of mitochondria, and application of an inhibitor of cyanide‐resistant electron transport (mCLAM)—support the hypothesis that one of the factors in the mitochondria from young or early spadices which limits their ability to oxidize malate is oxalacetate within the mitochondria. As the spadix develops, mitochondrial oxalacetate is diminished or disappears. The stimulation of oxygen uptake in the early stages due to cyanide is thus thought to result from the reduction of the quantity of oxalacetate by cyanohydrin formation.The inhibition by ADP is not clearly understood, but may result from the existence of other reactions which are subject to negative control by ADP and which have no relation to the role of ADP in oxidative phosphorylation or its coupling to electron transport.
NITROGEN FIXATION BY LICHENS ON GLACIAL DRIFT IN ICELAND
Authors: CRITTENDEN P. D. 
Published: May 2006

SummarySpecies of Peltigera Willd. and Stereocaulon Schreb. are among the most abundant macrolichens in the developing and older Rhacomitrium heaths on glacial drift at Sólheimajökull. The crustaceous Placopsisgelida (L.) Linds. is also a common pioneer lichen on rocks. These species contain a blue‐green alga either as the primary or secondary phycobiont. Five species of these genera were studied and showed appreciable rates of acetylene reduction. The total N content was greater in species with high nitrogenase activity. The biomass of Peltigera and Stereocaulon and surface area of Placopsis were determined at four sites of different ages and estimates of N2‐fixation m−2 day−1 are computed.
THE INABILITY OF BRACHYPODIUM SYLVATICUM AND OTHER SPECIES TO UTILIZE APATITE OR ORGANICALLY BOUND PHOSPHATE IN CALCAREOUS SOILS
Authors: ABEYAKOON K. F. , PIGOTT C. D. 
Published: May 2006

SummarySeedlings of Brachypodium sylvaticum (Huds.) Beauv., Festuca gigantea (L.) Vill., Lolium perenne L. and Urtica dioica L. were grown on freshly collected soil from the upper horizons of an uncultivated rendzina and a brown forest‐soil. All species responded to addition of a soluble phosphate on both soils but, while there was no response to the addition of apatite on the rendzina, there was as large a response to apatite as to soluble phosphate on the brown forest‐soil. Brachypodium sylvaticum and Urtica dioica were also grown in sand‐culture without phosphate, with a soluble phosphate, and with humus which is rich in organic phosphate. Both species responded to soluble phosphate but showed no response to the presence of humus. The experiments imply that even Brachypodium sylvaticum, which may occur naturally on calcareous soils containing only traces of soluble phosphate, cannot obtain phosphate from either apatite or humus when the pH is above 7.0.
ASPECTS OF TRANSLOCATION OF CARBON IN THE TULIP
Authors: HO L. C. , REES A. R. 
Published: May 2006

SUMMARYMature tulip plants were treated with 14CO2 in June after flower senescence, and the fate of 14C‐labelled products followed at irregular intervals by fractionation, chromatography and autoradiography until the senescence of the above‐ground parts and, later, following replanting, when reserves were mobilized for the growth of new shoots, new daughter bulbs and roots.Following feeding with 14CO2, sucrose was identified as the main mobile sugar which was transported down the vascular bundles of the shoot to the daughter bulbs where it accounted for 74% of the total plant radioactivity after 7 days. In the daughter bulb conversion occurred progressively with time to starch and non‐starch ethanol‐insoluble material.After replanting in mid‐September, both shoots and roots showed high radioactivity (10% and 14% respectively of total activity, 60 days after replanting). Vascular tissues were strongly labelled indicating their role in the redistribution of carbohydrates which were mainly sucrose and fructose polymers in the daughter bulbs and sucrose and glucose in the growing organs.
THE EVOLUTIONARY RELATIONSHIPS OF BRITISH SPECIES OF PAPAVER IN SECTION ORTHORHOEADES AS SHOWN BY OBSERVATIONS ON INTERSPECIFIC HYBRIDS
Authors: HUMPHREYS M. O. 
Published: May 2006

SUMMARYThe morphology and cytology of the three British species of poppy in Section Orthorhoeades, Papaver rhoeas L. (2n= 14), P. lecoqii Lam. (2n= 28) and P. dubium L. (2n= 42), and their hybrids were studied. The chromosome numbers of the three species suggest that they are of diploid, tetraploid and hexaploid origin respectively. Chromosome pairing during meiosis in the hybrids suggests that P. rhoeas is only distantly related to P. dubium and P. lecoqii but that the last two species are much more closely related.The relationships between the three species and some variant, self‐fertile plants, originating from Henley‐in‐Arden, Warwickshire, were also studied. These plants have a chromosome number of 28 and the chromosome pairing behaviour in hybrids involving them is similar to that in hybrids involving P. lecoqii. However, hybrids between the Henley plants and the other three species were completely sterile. The stunted growth form of these hybrids suggests that genie differentiation has occurred in the Henley plants which upsets the physiological processes governing growth in the hybrids.It is postulated that the polyploid species possess a mechanism which prevents homoeologous pairing. The mechanism appears to operate normally in hybrids between the polyploid species but appears to break down in hybrids involving the diploid species, P. rhoeas.The significance of all the results obtained is discussed in terms of the origins and past evolution of poppies belonging to Section Orthorhoeades in Britain.
EFFECTS OF PHENYL‐MERCURIC ACETATE ON STOMATAL AND CUTICULAR RESISTANCE TO TRANSPIRATION
Authors: MORESHET S. 
Published: May 2006

SUMMARYPhenyl mercuric acetate applied to both sides of the leaves of sunflower plants growing in both wet and dry soil caused a greater closure of the stomates on the upper than on the lower side of the leaves. By contrast, application of PMA increased cuticular resistance to gas diffusion only in the case of leaves of plants growing in dry soil, suggesting that soil moisture stress as well as PMA decreases the permeability of non‐stomatal epidermal cells.
ION TRANSPORT AND ENDODERMAL SUBERIZATION IN THE ROOTS OF ZEA MAYS
Authors: FERGUSON I. B. , CLARKSON D. T. 
Published: May 2006

SUMMARYProgressive suberization and thickening of the endodermis along secondary seminal axes of Zea mays had little effect on the radial movement of phosphate into the vascular tissue. In all parts of the root, inhibitors of respiration, and low temperature, reduced uptake and xylem translocation of phosphate by more than 90%. With calcium, however, there appeared to be two components of the translocated fraction; one was sensitive to metabolic inhibition and was most prominent in young tissue near to the root tip, while the other was insensitive to metabolic inhibition. In older zones near the base of the root, where there was little calcium movement into the stele, only the second insensitive component of calcium transport was found.A marked maximum in calcium translocation, but not in the translocation of phosphate, was found 12 cm from the root tip. This was not associated with a marked increase in total absorption but was due to a high proportion of the absorbed calcium which moved into the stele. This region is one where lateral roots are initiated in the pericycle and where the structure of the endodermis may change transiently.At the extreme base of the roots the development of a suberized hypodermis appeared to restrict very severely the translocation of both phosphate and calcium.Iron and manganese were also absorbed and translocated by all regions of the root examined; the proportion translocated was much greater for manganese than for iron.
HORMONAL CHANGES DURING AFTER‐RIPENING IN SEEDS OF STACHYS ALPINA L.
Authors: PINFIELD N. J. , MARTIN M. H. , STOBART A. K. 
Published: May 2006

SUMMARYUnchilled seeds of Stachys alpina L. were dormant when harvested but germinated well if incubated in gibberellin. Chilling resulted only in limited increases in germination even after periods as long as 140 days. Endogenous gibberellins were not detectable in unchilled seeds, but extracts showed appreciable inhibitory activity. Chilling of the seeds resulted in increases in endogenous gibberellin‐like substances and decreases in endogenous inhibitors. Significant levels of gibberellins were first detected after 50 days and continued to increase thereafter, while inhibitory activity was considerably reduced after periods exceeding 26 days.The comparatively slow changes in endogenous gibberellin levels are discussed in terms of the limited germination response of the seeds to prolonged chilling.
AN ULTRASTRUCTURAL STUDY OF THE AZOLLA, ANABAENA AZOLLAE RELATIONSHIP
Authors: DUCKETT J. G. , TOTH R. , SONI S. L. 
Published: May 2006

SUMMARYElectron microscopy reveals that the multicellular hairs, in the Anabaena‐containing leaf cavities of Azolla, produce labyrinthine wall ingrowths, and have dense cytoplasm with numerous mitochondria and abundant endoplasmic reticulum. Development of transfer cell morphology, in this location, might be an adaptation facilitating interchange of metabolites between Azolla and its algal partner. Equally prominent wall ingrowths are also found in the absence of Anabaena. It is suggested that they may be either a constitutive feature of Azolla or may be induced as a response to the presence of combined nitrogen sources in the axenic culture medium. The occurrence of plasmalemmasomes, in the developing hair‐cells of Azolla, is compared with their presence in lichens, mycorrhiza and at host‐parasite interfaces.
GROWTH OF CROSS‐ AND SELF‐POLLEN TUBES IN THE STYLES OF BRASSICA OLERACEA
Authors: OCKENDON D. J. , GATES P. J. 
Published: May 2006

SUMMARYIncompatible pollen tubes grew at approximately the same rate as compatible pollen tubes in the styles of Brassica oleracea. This is further evidence that in this species the chief barrier to the growth of incompatible pollen tubes is the stigmatic surface and that there is no positive inhibition of incompatible pollen tubes in the style. There were usually very many more pollen tubes at the top of the style than at its base, which indicated considerable variation in growth rate between the pollen tubes in a single style. The fastest pollen tubes in a style typically had a growth rate of 0.40–0.70 mm/h but the mean rate of growth was 0.14–0.34 mm/h.
STRATIGRAPHY AND POLLEN ANALYSIS OF BROMFIELD SWAMP, NORTH EASTERN QUEENSLAND, AUSTRALIA
Authors: KERSHAW A. P. 
Published: May 2006

SUMMARYThe sequence of vegetation changes evidenced in the Bromfield Swamp pollen diagram is similar to those derived from previous studies at Lake Euramoo and Quincan Crater. It is established that the initial presence of sclerophyll vegetation around the sites was a regional feature of the Atherton Tableland, determined by low precipitation. Throughout the succeeding rain forest phase, precipitation was higher at Bromfield Swamp than at the other sites suggesting that the rainfall gradient across the Tableland has remained constant. The contrast between the relatively simple stratigraphic sequence of deposits in the swamp and the present complex mosaic of vegetation types and depositional environments implies that there has been a great deal of recent interference with the swamp and the surrounding crater slopes.
HYBRIDS BETWEEN LOLIUM PERENNE AND FESTUCA PRATENSIS
Authors: GYMER P. T. , WHITTINGTON W. J. 
Published: May 2006

SUMMARYMany cytogenetic abnormalities are described from Festuca‐Lolium hybrids. Some have not been reported before, notably extra spindles in meiotic interphase and second telophase, and the formation of secondary cells from syncytes. Many of the abnormalities prevent the formation of normal gametes and thus contribute to the sterility of the species. Previous work, however, has shown that this is largely due to genie imbalance in the hybrids.
POLYMORPHISM IN ARRHENATHERUM ELATIUS (L.) BEAUV. EX J. & C. PRESL
Authors: MAHMOUD A. , GRIME J. P. , FURNESS S. B. 
Published: May 2006

SUMMARYIn the vicinity of Sheffield, natural populations of Arrhenatherum elatius exhibit continuous variation in tiller and leaf number, leaf length and tiller angle. In the associated range of morphologies, the extremes are represented by erect and prostrate plants. Field and laboratory investigations suggest that this polymorphism is genetically controlled and may be attributed to the conflicting selection pressures imposed by competition for light in tall herbaceous vegetation and by continuous defoliation in pastures.
INTERFEROMETRIC CHANGES IN ONION NUCLEI AND NUCLEOLI DURING DEVELOPMENT
Authors: MONOSON H. L. , KULFINSKI F. B. 
Published: May 2006

SUMMARYThe inner epidermis of the outermost (1) through to the innermost (7) bulb scales of mature white onions were studied by means of quantitative interferometry. Scale 7 represented the oldest unemerged leaf, whereas scales 1 to 6 represented mature leaf bases whose blades had grown, emerged, and withered. A developmental sequence was observed from scale 7 through to scale 1. Nuclei increased in area from 2.9 × 10−6 cm2 in scale 7 to 9.9 × 10−6 cm2 in scale 1, with the greatest increases among the younger scales. Nucleoli increased in area from 3.7 × 10−8 cm2 in scale 7 to 13.9 × 10−8 cm2 in scale 2. Dry mass per unit area of the nuclei increased from 7.8 × 10−5 g/cm2 in scale 7 to 12.4 × 10−5 g/cm2 in scale 1, with a maximum of 13.7 × 10−5 g/cm2 in scale 3. Nucleoli increased in dry mass per unit area from 6.2 × 10−5 g/cm2 in scale 7 to 9.2 × 10−5 g/cm2 in scale 1, with a maximum of 11.6 × 10−5 g/cm2 in scale 3. Nuclear dry mass increased from 2.1 × 10−10 g in scale 7 to 12.1 × 10−10 g in scale 1. Nucleolar dry mass increased from 2.3 × 10−12 g in scale 7 to 12.9 × 10−12 g in scale 1. The data suggest that nuclei and nucleoli increase in size and mass with cell size, thereby providing a greater biosynthetic (control) capacity to enlarging cells.
THE INFLUENCE OF NIGHT LENGTH ON STOMATAL BEHAVIOUR IN TRADESCANTIA VIRGINIANA
Authors: MARTIN E. S. , MEIDNER H. 
Published: May 2006

SUMMARYIn continuous light the time course of stomatal opening in Tradescantia virginiana was substantially modified by the length of the preceding night, e.g. the time to maximum opening was decreased as the preceding night length increased. This response can be correlated with an underlying stomatal rhythm in darkness. The possibility that this rhythm is due to changes in osmotic relations between guard and epidermal cells is discussed.
A REGIONAL SUB‐DIVISION OF DINOFLAGELLATE CYSTS AROUND THE BRITISH ISLES
Authors: REID PHILIP C. 
Published: May 2006

SUMMARYA cluster analysis of the dinoflagellate cyst assemblage of sixty‐eight intertidal sediment samples from the British Isles has been used to divide the coastline into eleven regions. The resulting pattern of regions is discussed in relation to hydrography and the distribution of dinoflagellates in the plankton. The subdivision of dinoflagellate regions shows a close relationship to the occurrence of chaetognath indicators of water masses around the British Isles. This suggests that cyst propagation is localized and that each water mass has its own characteristic dinoflagellate population.
THE ACTIVITY OF INVERTASE AND ITS RELEVANCE TO THE ACCUMULATION OF STORAGE POLYSACCHARIDES IN LEAVES INFECTED BY BIOTROPHIC FUNGI
Authors: LONG D. E. , FUNG A. K. , McGEE E. E. M. , COOKE R. C. , LEWIS D. H. 
Published: May 2006

SUMMARYInfection of Senecio squalidus by Albugo tragopogonis and of Tussilago farfara and Poa pratensis by Puccinia poarum results in an increase in the activity of an acid invertase localized at the sites of infection. It is concluded that sucrose from the host is first hydrolysed and then absorbed by the parasite. Invertase also plays a key role in the provision of substrate for the typical accumulation of starch around pustules of biotrophic fungi on host species which store this polysaccharide. Compartmentation of invertase and the enzymes concerned with synthesis of sucrose and fructans permits these carbohydrates to be accumulated within pustules on host species which normally store fructans.
STIMULATION OF SEX ORGAN FORMATION IN PHYTOPHTHORA BY ANTAGONISTIC SPECIES OF TRICHODERMA
Authors: BRASIER C. M. 
Published: May 2006

SUMMARYEvidence for the occurrence of the ‘Trichoderma effect’ in nature is reviewed. It is considered that the effect may be a specifically evolved defence mechanism, and that root inhabiting species of Phytophthora may be more ecologically specialized for response to Trichoderma than others. It is suggested that the ‘Trichoderma effect’ and similar phenomena could influence speciation in heterothallic Phytophthora species.
AN ALBINO MUTANT IN PLANTAGO INSULARIS REQUIRING THIAMINE PYROPHOSPHATE—EFFECTS OF TPP ON CHLOROPLAST ULTRASTRUCTURE
Authors: MICHAEL SANDRA D. , SPURR ARTHUR R. 
Published: May 2006

SUMMARYThe responses of normal (al+/al+) and albino mutant (aljal) seedlings of Plantago insularis to light and thiamine pyrophosphate (TPP) were studied by transmission electron microscopy.Plastids in seedlings of normal and albino genotypes grown in darkness had the structure of etioplasts with a thylakoid plexus (prolamellar body) from which extend thylakoids. Some of the thylakoids were often associated into parallel or concentric sheets. In the mutant, the thylakoid sheets were generally shorter, and some were vesiculated. Exposure of normal plants to light resulted in the transformation of the etioplasts to chloroplasts, with the loss of the thylakoid plexus and the formation of typical grana and an intergranal thylakoid system, plus a few globules in the stroma. Exposure of the albino mutant to light caused the loss of the thylakoid plexus and the formation of highly ordered, concentrically associated thylakoid sheet systems, but no grana. After 24 h of illumination, the plastids of the albino mutant showed evidence of thylakoid degeneration and accumulation of globules and starch. These changes are interpreted as a consequence of very low TPP in the mutant and as evidence for the role of TPP in the degradation of glucose through the Krebs cycle in the normal genotype.The application of TPP to the albino mutant resulted in the formation of essentially normal chloroplasts. The ultrastructural observations support the view that TPP deficiency does not handicap the mutant in protein synthesis until after exposure to light. TPP and light are essential for the formation of normal grana and TPP is in some way involved in the pathways for pigment and protein synthesis in chloroplasts.
CYLINDROCAPSA: CELL DIVISION AND PHYLOGENETIC AFFINITIES
Authors: PICKETT‐HEAPS IEREMY D. , McDONALD KENT L. 
Published: May 2006

SUMMARYEach vegetative cell of Cylindrocapsa is enclosed by its own wall, and the filamentous form is maintained by a separate sheath of wall material derived from parental cells. Cell division differs from most other Ulotrichalean genera so far described. Cleavage is initiated even before prophase, usually first from that side of the cell where the interphase nucleus and centrioles lie near the wall. Centrioles replicate and the pairs then separate around the nucleus. The spindle is closed; the poles are broad and flattened with the centrioles coming to lie to one side of them. The nuclear envelope is highly perforated at each pole and spindle microtubules run into these small holes. As anaphase progresses, the ingrowing cleavage furrow impinges upon the interzonal spindle, often deforming it. No phycoplast is formed for cytokinesis. Instead, the spindle seems to collapse as the furrow pushes through it so that the daughter nuclei eventually lie on either side of it.Recent work has shown this type of cell division to occur in several other Ulotrichalean algae. A recent redefinition of the order Ulvales based on this type of cell division includes several algae formerly in the Ulotrichales. We support this redefinition and the inclusion of Cylindrocapsa in the Ulvales as the only genus in the family Cylindrocapsaceae.