bluuebunny/crossref_metadata_2025 huggingface dataset:
Resisting resistance: dealing with the irrepressible problem of malaria
Authors: Edwards Geoffrey , Biagini Giancarlo A.
Published: May 2006

The burgeoning problem of malaria in the developing world and the relentless march of drug resistance demand that we continue to seek new chemotherapeutic strategies. Given the enormous expense of developing and marketing new chemical entities, we often rely on an increased understanding of the pharmacology of older drugs and judicious use of drug combinations. Development is being driven primarily by public–private partnerships from academic investigations. Two such agents are the antifolate combination Lapdap™, already licensed and soon to be combined with artesunate, and isoquine, a novel isoquinoline, about to enter clinical trials. Other drug combinations designed to minimize the spread of resistance are in the pipeline. Such developments are crucial as it becomes clear that existing drugs, even those used in combinations, may have limited lifetimes.
HapMap, pharmacogenomics, and the goal of personalized prescribing
Authors: O’Shaughnessy Kevin M.
Published: May 2006

Most of the gene variants that have been identified in the last 50 years have affected individual drug responses through effects on pharmacokinetics. Gene variants that affect a drug’s pharmacodynamics, such as polymorphisms in receptors or signalling molecules, have been more difficult to identify. This often requires a more systematic and genome‐wide approach, prompting the emergence of the new discipline of pharmacogenomics. The provision of the human genomic sequence and now data from the HapMap project look set to bring ‘personalized prescription’ a step closer.
Crypt dynamics and colorectal cancer: advances in mathematical modelling
Authors: Van Leeuwen I. M. M. , Byrne H. M. , Jensen O. E. , King J. R.
Published: May 2006

Abstract.   Mathematical modelling forms a key component of systems biology, offering insights that complement and stimulate experimental studies. In this review, we illustrate the role of theoretical models in elucidating the mechanisms involved in normal intestinal crypt dynamics and colorectal cancer. We discuss a range of modelling approaches, including models that describe cell proliferation, migration, differentiation, crypt fission, genetic instability, APC inactivation and tumour heterogeneity. We focus on the model assumptions, limitations and applications, rather than on the technical details. We also present a new stochastic model for stem‐cell dynamics, which predicts that, on average, APC inactivation occurs more quickly in the stem‐cell pool in the absence of symmetric cell division. This suggests that natural niche succession may protect stem cells against malignant transformation in the gut. Finally, we explain how we aim to gain further understanding of the crypt system and of colorectal carcinogenesis with the aid of multiscale models that cover all levels of organization from the molecular to the whole organ.
Synchronization in the cell cycle by inhibitors of DNA replication induces histone H2AX phosphorylation: an indication of DNA damage
Authors: Kurose A. , Tanaka T. , Huang X. , Traganos F. , Darzynkiewicz Z.
Published: May 2006

Abstract.   Several methods to synchronize cultured cells in the cell cycle are based on temporary inhibition of DNA replication. Previously it has been reported that cells synchronized this way exhibited significant growth imbalance and unscheduled expression of cyclins A and B1. We have now observed that HL‐60 cells exposed to inhibitors of DNA replication (thymidine, aphidicolin and hydroxyurea), at concentrations commonly used to synchronize cell populations, had histone H2AX phosphorylated on Ser‐139. This modification of H2AX, a marker of DNA damage (induction of DNA double‐strand breaks; DSBs), was most pronounced in S‐phase cells, and led to their apoptosis. Thus, to a large extent, synchronization was caused by selective kill of DNA replicating cells through induction of replication stress. In fact, similar synchronization has been achieved by exposure of cells to the DNA topoisomerase I inhibitor camptothecin, a cytotoxic drug known to target S‐phase cells. A large proportion of the surviving cells ‘synchronized’ by DNA replication inhibitors at the G1/S boundary had phosphorylated histone H2AX. Inhibitors of DNA replication, thus, not only selectively kill DNA replicating cells, induce growth imbalance and alter the machinery regulating progression through the cycle, but they also cause DNA damage involving formation of DSBs in the surviving (‘synchronized’) cells. The above effects should be taken into account when interpreting data obtained with the use of cells synchronized by inhibitors of DNA replication.
Undetectable salivary testosterone in young women with premature ovarian failure
Authors: Mason A. , Wallace A. M. , MacIntyre H. , Teoh Y. P. , Bath L. E. , Critchley H. O. , Kelnar C. J. H. , Wallace W. H. B. , Ahmed S. F.
Published: May 2006

Background  The extent of androgen deficiency in young women with premature ovarian failure (POF) is unclear.

Aim  Cross‐sectional study of androgen status in young women with POF.

Patients  Twenty women with POF: six had Turner syndrome (group A); eight had iatrogenic POF either secondary to bilateral oophorectomy or treatment of malignancy (group B); and six had idiopathic POF (group C). The median age was 30·5 years (range 19–39); in groups B and C the median duration of ovarian failure was 10·0 years (range 1–35).

Methods  After a 2‐month wash‐out period without sex steroid replacement (SSR), serum testosterone (T), androstenedione (A4), dehydroepiandrosterone (DHEAS), SHBG, salivary testosterone (SalT) and the free androgen index [FAI = (serum T/SHBG) × 100] were measured.

Results  Median serum A4 was 4·6 nmol/l (10th, 90th centiles, 3·6, 5·1) and DHEAS was 3·2 µmol/l (10th, 90th centiles, 2·3, 9·3). Although median serum T was relatively low at 1·4 nmol/l (10th, 90th centiles, 1·1, 1·7), median SHBG was also low at 34 nmol/l (10th, 90th centiles 22·2, 67·5) and the median calculated FAI was within the normal range at 3·7 (10th, 90th centiles, 2·3, 7·0). However, SalT was undetectable in almost all subjects in the three groups of POF.

Conclusions  Serum T and SHBG are relatively low in young women with POF and their FAI is therefore within the normal range. However, SalT, which measures free testosterone, is consistently low to undetectable in these young women with POF. The reliability of the FAI as a marker of androgen deficiency remains questionable.
Estimating diesel degradation rates from N2, O2 and CO2 concentration versus depth data in a loamy sand
Authors: Van De Steene J. , Verplancke H.
Published: May 2006

The degradation rate of the pollutant is often an important parameter for designing and maintaining an active treatment system or for determining the rate of natural attenuation. A quasi‐steady‐state gas transport model based on Fick’s law with a correction term for advective flux, for estimating diesel degradation rates from N2, O2 and CO2 concentration versus depth data, was evaluated in a laboratory column study. A loamy sand was spiked with diesel fuel at 0, 1000, 5000 and 10 000 mg kg−1 soil (dry weight basis) and incubated for 15 weeks. Soil gas was sampled weekly at 6 selected depths in the columns and analysed for O2, CO2 and N2 concentrations. The agreement between the measured and the modelled concentrations was good for the untreated soil (R2= 0.60) and very good for the soil spiked with 1000 mg kg−1 (R2= 0.96) and 5000 mg kg−1 (R2= 0.97). Oxygen consumption ranged from −0.15 to −2.25 mol O2 m−3 soil day−1 and CO2 production ranged from 0.20 to 2.07 mol CO2 m−3 soil day−1. A significantly greater mean O2 consumption (P < 0.001) and CO2 production (P < 0.005) over time was observed for the soils spiked with diesel compared with the untreated soil, which suggests biodegradation of the diesel substrate. Diesel degradation rates calculated from respiration data were 1.5–2.1 times less than the change in total petroleum hydrocarbon content. The inability of this study to correlate respiration data to actual changes in diesel concentration could be explained by volatilization, long‐term sorption of diesel hydrocarbons to organic matter and incorporation of diesel hydrocarbons into microbial biomass, aspects of which require further investigation.
Directions in the immune targeting of cancer: Lessons learned from the cancer‐testis Ag NY‐ESO‐1
Authors: Nicholaou Theo , Ebert Lisa , Davis Ian D , Robson Neil , Klein Oliver , Maraskovsky Eugene , Chen Weisan , Cebon Jonathan
Published: May 2006

Since the early 1990s, numerous cancer Ag have been defined and for a handful of these there is now some clinical experience, which has made it possible to assess their value as targets for cancer immunotherapy. The cancer‐testis Ag have been particularly attractive because their expression is limited to cancer and virtually no non‐malignant cells apart from germ cells and trophoblast. Among these, NY‐ESO‐1 has been the focus of our attention. The exceptional immunogenicity of this Ag coupled with its widespread distribution among many cancer types make it a very good vaccine candidate, with the potential to be used in vaccines against many types of malignancies. This article reviews emerging knowledge about the biology of NY‐ESO‐1 and experience with the early clinical development of vaccines directed against NY‐ESO‐1. These early studies have yielded a wealth of information about the immunology of NY‐ESO‐1 and set the scene for future clinical strategies for immune targeting of cancer.
Loving, Hating, Vacillating: Agreeableness, Implicit Self‐Esteem, and Neurotic Conflict
Authors: Robinson Michael D. , Wilkowski Benjamin M.
Published: May 2006

ABSTRACTAn implicit preference for the self over others may be beneficial when pursuing one's own desires but costly when adjusting the self to the desires of others. On the basis of this reasoning, the authors hypothesized that Agreeableness and implicit self‐esteem would interact in predicting measures of neurotic distress. Three studies and one meta‐analysis, involving 235 undergraduate participants, confirmed that high levels of implicit self‐esteem were beneficial (i.e., less neurotic distress) within the context of low levels of Agreeableness but costly (i.e., more neurotic distress) within the context of high levels of Agreeableness. Because findings were robust across various measures of Agreeableness, implicit self‐esteem, and neurotic distress, the interpersonal principles examined here appear to have broad relevance for understanding this particular form of intrapsychic conflict and its manifestation in neurotic distress. Results therefore supportHorney's (1945)theory concerning the consequences of intrapsychic conflicts related to interpersonal motivation and cognition.
Individual Differences in Approach and Avoidance Movements: How the Avoidance Motive Influences Response Force
Authors: Puca Rosa Maria , Rinkenauer Gerhard , Breidenstein Christian
Published: May 2006

ABSTRACTThe present research is based on the assumption that people differ in their responsiveness to incentives and threats. In two experiments we examined whether the trait corresponding to the responsiveness to threats (avoidance motive) and the trait corresponding to the responsiveness to incentives (approach motive) influence voluntary motor behavior toward or away from stimuli. In Experiment 1, stimuli consisted of positive and negative words within a lexical decision task. Participants moved their arms backward in order to withdraw from the stimuli or forward in order to approach them. In Experiment 2, participants responded with forward or backward arm movements to neutral sounds coming from behind or in front of them.

The main dependent variable was the strength of the approach and avoidance movements. In both experiments this variable was related to participants' avoidance‐motive disposition but not to their approach‐motive disposition. Avoidance‐motivated individuals generally showed more forceful avoidance movements than approach movements. There was no effect of stimulus valence on the strength of the movements in Experiment 1. Furthermore, the results of Experiment 2 suggest that it is not the physical direction (forward or backward) but rather the movement's effect of distance reduction (approach) or distance increase (avoidance) in regard to the stimulus that defines a movement as an approach or an avoidance movement.
Self‐Liking and Self‐Competence Separate Self‐Evaluation From Self‐Deception: Associations With Personality, Ability, and Achievement
Authors: Mar Raymond A. , DeYoung Colin G. , Higgins Daniel M. , Peterson Jordan B.
Published: May 2006

ABSTRACT
The similarities between measures of self‐evaluation and self‐deception are reviewed, and a method for discriminating between them is proposed, using personality profiles and relations to ability and achievement. Across two samples, the Rosenberg Self‐Esteem Scale (RSES) and Tafarodi's measures of self‐evaluation were used to demonstrate that the RSES and Self‐Liking are more similar to Self‐Deceptive Enhancement than is self‐competence. Further, Self‐Competence is uniquely associated with cognitive ability and both academic and creative achievement. It is concluded that, along with self‐liking, self‐competence is a useful form of self‐evaluation that should be measured and taken into account in research that has traditionally focused on self‐esteem.
The Price of UK Commercial Credit Lines: A Research Note
Authors: Hanley Aoife , Ennew Christine , Binks Martin
Published: May 2006

Abstract:  The UK Cruickshank Report (2000) highlighted the potential for market power issues where bank concentration could lead to more expensive credit. Because of the many risk factors influencing the cost of credit, it is difficult to establish whether differences in pricing is a consequence of risk or is due to differential pricing practices among lenders. In this study, we find that even when risk factors are taken into account, considerable variation in pricing among UK lenders remains. Moreover, the lenders with the largest market share in SME finance over the 8 years surveyed, charged significantly higher interest premia.
CELL WALL METABOLISM I. HEMICELLULASES OF BROMUS SEEDS
Authors: MACLEOD ANNA M. , SANDIE R.
Published: May 2006

Summary

Readily extractable hemicelluloses account for approximately 14% of the dry weight of grains of five species of Bromus. In B. mollis, although 10% of cellulose is present in the whole grain, only one‐eighth of this cellulose is located within the true seed, the remainder being restricted to the husk. Crude preparations of enzymes extracted from B. mollis can rapidly solubilize and degrade pentosan and hexosan hemicelluloses but are without apparent effect on suspensions of cellulose, and there appears to be no real evidence for the action of a true cellulase during germination.

Extracts of Bromus seeds are also extremely active in transglucosylation and can readily catalyse synthesis of β‐linked oligosaccharides from 1% solutions of cellobiose.
CYTOTAXONOMIC STUDIES IN HOLCUS
Authors: CARROLL CHRISTOPHER P. , JONES KEITH
Published: May 2006

Summary

A statistical study has been made of the morphology of Holcus lanatus (2n= 14), H. mollis (2n= 28) and of three F1 progenies (2n= 21).

The hybrids, while intermediate in some respects, tends to resemble the mollis parent strongly in morphology and growth form. This could be accounted for by their genomic composition.

The occurrence of natural F1 hybrids is reported, and considered in the light of the experimental results. Their importance in the evolution of the H. mollis complex is discussed. It is shown that interspecific hybrids could easily be confused with authentic H. mollis in the wild. A list of tentative diagnostic characters is given, but only chromosome counting can provide decisive identification.
SEASONAL VARIATIONS IN THE SECONDARY PHLOEM OF SOME FOREST TREES FROM NIGERIA
Authors: LAWTON JUNE R. , LAWTON J. R. S.
Published: May 2006

Summary

Samples of bark were taken from the main trunk of trees of Antiaris (two), Tectona, Bombax, Albizia, Ricinodendron and Holarrhena at monthly intervals for two consecutive years. Phloem zones were characterized, inter alia, by the amount and type of callose present, as indicated by the callose fluorescence. The greatest amount of the ‘active’ phloem coincided in all cases with some part of the rainy season. Bud break generally occurred at some time during the dry season, normally at the very end, and this coincided with the lowest amount of ‘active’ phloem, although it was rapidly followed by an increase in the amount of ‘active’ phloem. In only two genera, Ricinodendron and Tectona, could it be deduced that there was any cessation of cambial activity during the dry season, as indicated by the lack of ‘active’ phloem. In all other cases ‘active’ phloem was present throughout the dry season. The depth of the total fluorescent zone indicates that there is a large amount of phloem produced during the year in many of these trees.

Tylosoids were formed in three of the six genera at the time of formation of the definitive callose; in Antiaris and possibly Ricinodendron the tylosoids became lignified, but not in Bombax.
THE INTERNAL CONTROL OF NITRATE UPTAKE INTO EXCISED BARLEY ROOTS WITH DIFFERING SALT CONTENTS
Authors: SMITH F. A.
Published: May 2006

Measurements of net NO3‐ influx have been made with excised bailey roots of differing salt status. With roots grown in 0.2 mM CaSO4, net NO3‐ influx shows partial saturation with external NO3‐ concentrations greater than 0.5 mM, and is greatly reduced in the absence of external K+ or Na+. Net NO3‐ influx from NaNO3 solution is as rapid as from KNO3 solution, but when both K+ and Na+ are present the roots show high specificity for K+ over Na+. When roots are high in Cl‐, net NO3‐ influx is greatly reduced, and the reciprocal effect of reduction in Cl‐ influx into roots high in NO3‐ is also found. There is some decrease in net NO3‐ influx and in Cl‐ influx when roots are high in organic anions, and under these conditions net NO3‐ influx is completely independent of cation influx. There is no effect of external Cl‐ (up to 10 mM) on net NO3‐ influx (1 mM solution), and very little or no effect of external NO3‐ on Cl‐ influx. The results are considered in relation to the hypothesis that influx of NO3‐ and Cl‐ is subject to feedback control from the internal NO3‐ plus Cl‐ content, but it is concluded that organic anions can also play an important part in controlling influx of NO3‐ and Cl‐. The interactions between cation and anion fluxes are discussed, and a unifying model for ion transport proposed.
A NEW SPECIES OF MYCORRHIZAL ENDOGONE FROM NIGERIA WITH A DISTINCTIVE SPORE WALL
Authors: OLD K. M. , NICOLSON T. H. , REDHEAD J. F.
Published: May 2006

An unnamed species of mycorrhizal Etidogone from Nigeria is described. It belongs to the zygosporic or azygosporic group and the spore wall resembles that of a ‘honey‐coloured’ species recently described by Mosse. The most conspicuous feature is seen in the outer layers. These show a porous and meshwork construction and ultrastructural aspects are described. The species is not formally named at this stage as reorganization of the genus is currently taking place.
XYLEM FLECKS: A NOTE ON SOME UNEXPLAINED ABNORMALITIES IN THE WOOD OF EUROPEAN LARCH AND OTHER TREES
Authors: BUCZACKI S. T.
Published: May 2006

Small patches of abnormal tissue in the wood of European larch, termed xylem flecks, are described. They are particularly prevalent in the wood formed in the penultimate internode. Similar tissues were also seen in four other tree species. Fleck formation varied from year to year. Although xylem flecks resemble the tissue abnormalities associated with frost damage, it seems unlikely that their causation is climatic. All larch trees suffering from epidemic dieback contained xylem flecks and the possibility of an association with adelgid infestations is discussed. It is concluded that the flecks may have been a response to stress conditions, although a positive correlation in one tree between numbers of flecks and annual radial increment indicated a less simple explanation.
THE EVOLUTION OF SEED INCOMPATIBILITY IN PRIMULA
Authors: EATON R. D.
Published: May 2006

The validity of using the strength of the ‘seed incompatibility’ reaction (Valentine, 1956) in establishing evolutionary relationships on a species of Primula is questioned, and a hypothesis advanced to account for the observed symptoms of the phenomenon.
HYBRIDS BETWEEN LOLIUM PERENNE AND FESTUCA PRATENSIS II. COMPARATIVE MORPHOLOGY
Authors: GYMER P. T. , WHITTINGTON W. J.
Published: May 2006

Morphological evidence was found to support the belief that both natural and artificial hybrids between Lolium perenne and Festuca pratensis would fall into three classes, namely diploid, festucoid or loloid triploids. Natural diploids resembled diploids produced by artificial hybridization. Whereas natural festucoids resembled F1 festucoids, natural loloids on the other hand, perhaps due to selective or random survival in the pasture, showed some differences from both the F1 and back cross loloids.
THE RELATIONSHIP OF SOME POPULATIONS INVOLVING EUCALYPTUS CYPELLOCARPA AND E. GLOBULUS TO THE PROBLEM OF PHANTOM HYBRIDS
Authors: KIRKPATRICK J. B. , SIMMONS DIANNE , PARSONS R. F.
Published: May 2006

A taxonomically anomalous population of eucalypts at Mallacoota, Victoria, is mapped and studied in detail. Measurements of adult and seedling morphology show the population to be intermediate between Eucalyptus globulus and E. cypellocarpa. However, on leaf terpenoid data the population is indistinguishable from E. cypellocarpa. The very restricted distribution of the population, and the high variability of its adult morphology suggest that it arose by hybridization between the two species named above. As the nearest stand of E. globulus is 6.4 km away, the population may represent a phantom hybrid stand. It is inferred from distribution data that E. globulus stands may have been present in the area before submergence by rising sea levels. If any pure E. globulus trees remained, a preponderance of E. cypellocarpa pollen may have prevented the continued production of more preponderant E. globulus progeny.
RADIOCARBON DATES AND VEGETATIONAL HISTORY OF THE BRITISH ISLES
Authors: SMITH A. G. , PILCHER J. R.
Published: May 2006

Radiocarbon dates for a number of pollen analytic features marking important vegetational changes in the Post‐glacial of the British Isles are plotted in two figures (Figs. 2 and 3, summarized in Fig. 4). Despite the limitations of the radiocarbon method it becomes clear, where sufficient dates are available, that most of the vegetational developments of the earlier part of the Post‐glacial are diachronous. Some of these changes have been used as pollen zone boundaries. The elm decline appears synchronous, however, within the limits of the methods, and the final pine decline in Ireland, which is shown to be older than supposed by Jessen (1949), appears to be one of the least diachronous of the horizons examined. Marked differences in the dates of similar vegetational changes within a small area, and between upland and lowland, are pointed out.
A LATE‐ AND POST‐GLACIAL POLLEN DIAGRAM FROM CRANBERRY BOG, NEAR BEAMISH, COUNTY DURHAM
Authors: TURNER JUDITH , KERSHAW A. PETER
Published: May 2006

Cranberry Bog is a lowland moss which developed originally in a small shallow glacial hollow which contained open water during the late‐ and early post‐glacial. After a brief transition stage ombrogenous peat began to form and continued to do so throughout zone VI. An unusual feature of the bog is a well‐developed ‘Grenzhorizont’ which was not formed as a result of changes in climate. The late‐ and early post‐glacial vegetation of the area was transitional in character between that described from the Northumberland lowlands to the north and that described from the Yorkshire lowlands to the south, although it more closely resembles the former. Several unusual features of the pollen diagram, high birch frequencies throughout and low alder frequencies in zone VIII, are best understood in terms of a locally dominated pollen spectrum.
CHANGES IN THE CARBOHYDRATE COMPOSITION OF LEAVES OF TUSSILAGO FARFARA DURING INFECTION BY PUCCINIA POARUM
Authors: HOLLIGAN P. M. , CHEN C. , LEWIS D. H.
Published: May 2006

Low molecular weight sugars and sugar alcohols, fructans of varying molecular weight and neutral sugars derived by acid hydrolysis from healthy leaves of Tussilago farfara and leaves infected by pyenial and aecial stages of Puccinia po arum have been identified and quantitatively analysed. At sites of infection, there are progressive increases in amounts of the fungal components, mannitol, arabitol and a mannose containing polymer, and of host fructans. Results are compared and contrasted with other host‐parasite combinations.
THE EFFECT OF RHIZOPHAGUS TENUIS MYCORRHIZAS ON RYEGRASS, COCKSFOOT AND SWEET VERNAL
Authors: CRUSH J. R.
Published: May 2006

Growth of ryegrass (Lolium perenne) in a soil extremely deficient in available phosphorus, depended on conversion of most of the root system into endomycorrhizas by Rhizophagus tenuis. A further growth increment could be obtained in infected plants by adding other nutrients, whereas uninfected plants responded only to phosphorus. Cocksfoot (Dactylis glomerata) and sweet vernal (Anthoxanthum odoratum) also relieved extreme phosphorus deficiency by symbiosis with Rhizophagus tenuis; but in slightly more fertile soil all three grasses grew better without the fungus. Then R. tenuis grew mainly in the rhizosphere of inoculated plants with much less penetration.
EFFECT OF ENDOGONE MYCORRHIZA ON PLANT GROWTH V. INFLUENCE OF INFECTION ON THE MULTIPLICATION OF VIRUSES IN TOMATO, PETUNIA AND STRAWBERRY
Authors: DAFT M. J. , OKUSANYA B. O.
Published: May 2006

The effects of mycorrhizal infection on the production of three viruses in three hosts were examined. In tomato, the multiplication of tomato aucuba mosaic virus was increased and the amount of potato virus × produced depended on the stage of the mycorrhizal development. The amount of extractable arabis mosaic virus from petunia and strawberry plants was greater from mycorrhizal than from non‐mycorrhizal plants. These results are attributed to the higher levels of phosphate contained in mycorrhizal plants, because enhanced virus production could also be achieved in non‐mycorrhizal plants given various levels of soluble phosphate. These results are discussed in relation to other three‐membered systems.
GROWTH AND NITROGEN FIXATION IN LUPINUS ARBOREUS AS AFFECTED BY SHADING AND WATER SUPPLY
Authors: SPRENT JANET I.
Published: May 2006

Three experiments were carried out to investigate the effects of shading and water supply on growth and nitrogen fixation by young plants of Lupinus arboreus (up to 4 months old). Firstly, two light treatments, 20,000 and 6500 lux, were given under controlled environment conditions, and plants sampled weekly for 7 weeks. Secondly, four shading treatments (100%, 37%, 19% and 10% full daylight) were given to plants grown outside and samples taken after 4, 8 and 10 weeks. Thirdly, response to and recovery from moisture stress were investigated under controlled‐environment conditions.

Results from the two shading experiments showed that L. arboreus responds to shade as a typical mesophyte. Growth (measured as dry weight) was proportional to the logarithm of relative irradiance. Roots were affected more than shoots and hence the shoot: root ratio rose with increased shading. Water content varied with age and shading, the responses differing amongst different parts of the plant. Photosynthetic efficiency increased with moderate shading but decreased, as did relative growth rate, at 10% full daylight. The compensation point was estimated to be 7–8% full daylight (approximately 70 J cm‐2 day‐1).

Nodule number and weight were reduced by shading. There was a highly significant linear relationship between root and nodule dry weights, I g root tissue supporting 50 mg nodule tissue. Acetylene‐reducing activity per plant was also proportional to log relative irradiance and this was largely accounted for by the smaller amounts of nodule tissue formed under shade. Activity per milligram fresh weight was only slightly reduced by moderate shading and this probably resulted from increased vacuolation of the infected cells. Only severe shading (10% full daylight) had a marked effect on activity per milligram fresh weight. Nodule senescence was not observed under shade, since the amount of nodule tissue formed was in equilibrium with growth of other parts of the plant. N content was higher in shaded plants after 1 week, but the difference diminished with time until at 5 weeks the N content was the same in shaded and control plants.

Response to and recovery from moisture stress were similar to those reported for other species. Seedlings were grown on the fine sand taken from forests where L. arboreus is planted in New Zealand. In this sand the change from sufficient water to severe deficit occurs over a very small range of water contents (1.0–0.5% DW). Shaded plants responded to similar levels of stress as unshaded plants. Water potentials of leaves measured with a pressure bomb were correlated with acetylene‐reducing activity of nodules.
SEASONAL GROWTH AND GROWTH RATE‐COLONY SIZE RELATIONSHIPS IN SIX SPECIES OF SAXICOLOUS LICHENS
Authors: ARMSTRONG R. A.
Published: May 2006

The pattern of seasonal growth and the relation of growth rate to colony size were studied in four foliose and two crustose species of saxicolous lichens. A new method of measuring growth was used whereby the advance of a sample of lobes along millimetres marked on the substrate was measured under a magnification of × 10. Three peaks of growth were found (in March, June and November) for the foliose species and a single peak (in May–August) for the crustose species. The peaks of growth corresponded approximately to peaks of rainfall. Growth rate in relation to increasing colony size fell in a smooth exponential curve when expressed on a cm2/cm2/unit time basis. This result is consistent with a linear radial rate for most of the thallus sizes for the six species. There is also evidence for an exponential increase in growth rate initially until about 1.5 cm thallus diameter in two of the species when the linear radial rate is achieved.
ONSET OF SEED DORMANCY IN AEGILOPS KOTSCHYI BOISS. AND ITS EXPERIMENTAL MODIFICATION
Authors: WURZBURGER JUDITH , KOLLER D.
Published: May 2006

Onset of seed dormancy in caryopses of Aegilops kotschyi was investigated. Neither of the two caryopses in the spikelet was germinable until the fourth week after anthesis. After this, germinability of the upper caryopsis increased progressively while that of the lower one remained low. Drying by lyophilization improved germinability of the upper caryopsis, but only during the phase of increasing germinability. Excision of the upper floret at, or soon after anthesis, enhanced germinability of the remaining lower caryopsis. This response became progressively weaker as excision was delayed. The possibility is discussed that dormancy of the lower caryopsis depends on competition between the upper and lower caryopsis for an essential metabolite.
ACTIVE ACCUMULATION OF SODIUM BY ROOTS OF FIVE AQUATIC SPECIES
Authors: SHEPHERD U. H. , BOWLING D. J. F.
Published: May 2006

The accumulation of several major nutrient ions by the roots of some aquatic plants was investigated. Five species growing in freshwater lochs on the north coast of Scotland were studied. Electrical potential differences between root epidermal cells and the surrounding loch water were measured using micro‐electrodes. From these measurements, electrochemical potential gradients between the roots and the loch water were calculated, and also the driving forces on each ion. For each species investigated, the results indicate that sodium is actively accumulated by the roots. This contrasts with results of studies which provide evidence for a sodium efflux pump in plant cells. It is suggested that active accumulation of sodium is evident in plant roots when the external sodium concentration is low. The results showed that K+, Cl‐, and NO3‐ are actively accumulated; Ca++ and Mg++ appear to be in electrochemical equilibrium with the external medium.
CARBON DIOXIDE AND ETHYLENE EFFECTS IN THE CO‐ORDINATION BETWEEN THE POLLINATOR BLASTOPHAGA QUADRATICEPS AND THE SYCONIUM IN FICUS RELIGIOSA
Authors: GALIL J. , ZERONI M. , (BOGOSLAVSKY) D. BAR SHALOM
Published: May 2006

The multilateral inter‐relationships between figs and their pollinators contain ecophysiological elements in addition to morphological and behavioural co‐adaptations. The changes in the internal atmosphere of the ripening fig have a decisive effect on the activity of males and females of the pollinating wasp. During the early stages of the male phase of Ficus religiosa, the internal atmosphere of the fig consists of about 10% CO2, 10% O2 and some ethylene. The males of the pollinator, Blastopliaga quadraticeps, carry out their usual activities in perforating the walls of the galls and in fertilizing the females under these conditions while at the same time the females are inactivated. After perforation of the syconia wall by the males, the atmosphere within the fig becomes equilibrated with the external atmosphere. As a result, male wasps are inhibited, whereas the females become active, leave their galls, load pollen pockets with pollen and emerge from the fig. The differential response of male and female wasps to the changes in the composition of the internal atmosphere within the fig ensures the completion of the developmental cycle of both the pollinator and the fig. Differences in the behaviour of wasp pollinators of different Ficus spp. under normal conditions are regarded as adaptations to diversely composed internal atmospheres within male‐phase figs of the respective species.
GRAVITY AND THE DISTRIBUTION OF LEAF SHAPE IN THE TREES OF SASSAFRAS ALBIDUM
Authors: GHENT ARTHUR W.
Published: May 2006

Studies of leaf distribution in the North American Sassafras albidum (Nutt.) Nées revealed marked excesses of lobed leaves, above random expectation, attached to the gravitationally lowermost three‐eighths of branches, although some leaves of the ovate, two‐lobed, and three‐lobed shapes were found in all attachment positions. Ovate leaves predominate along the upper surface, and at the base and apex of branches. Air‐dry weights of leaves of all three shapes proved significantly heavier at lower and mid‐branch attachment positions. Ovate leaves on secondary branchlets were shown to be significantly more lanceolate than those on primary branches. No consistent pattern of lobed‐leaf frequency relative to the concept of ‘juvenile’ and ‘mature’ foliage could be detected. The ‘thumb‐lobes’ of two‐lobed leaves were found to occur with significantly greater frequency on the apically directed, gravitationally lower edges of laterally‐attached leaves. Speculation on the possible role of starch grains or similar heavy‐bodied entities, as determinants of leaf‐lobing, is presented.
PLATE TECTONICS AND SOME ASPECTS OF PACIFIC PLANT GEOGRAPHY
Authors: WHITMORE T. C.
Published: May 2006

The new interpretation of the geological history of the west and south‐west Pacific, in the light of plate tectonic theory, is that the islands formerly lay much closer or in contact with each other and with the land masses which form the western rim of the Ocean. There have been massive increases in separation during the Tertiary because of ocean floor spreading. Plant distribution patterns in the region are re‐interpreted against this history. Old World Winteraceae (centred around the Coral Sea) and Ficus section Pharmacosycea (ranging east to New Caledonia) are considered in detail. Attention of geologists is drawn to enigmas of phytogeography whose interpretation await refinement of the geological reconstruction, namely the high endemism of New Caledonia and amphi‐Pacific plant genera of the lowland humid tropics.
TIMING ABSCISSION IN PHASEOLUS VULGARIS L. BY CONTROLLING ETHYLENE PRODUCTION AND SENSITIVITY TO ETHYLENE
Authors: JACKSON MICHAEL B. , HARTLEY CHRISTOPHER B. , OSBORNE DAPHNE J.
Published: May 2006

Abscission in explants excised from the primary‐leaf petioles of dwarf bean (Phaseolus vulgaris L. cv. Canadian Wonder) is accelerated by removing the leaf‐blade 24 or 48 hours before the explants are cut. Deblading increases ethylene production before weakening of the abscission zone begins and the amount of ethylene produced is sufficient to promote abscission. Deblading also enhances the responsiveness of explants to ethylene and it is proposed that these two effects of deblading together account for the subsequent acceleration of abscission. If the auxin indol‐3‐yl acetic acid is applied to freshly debladed petiole stumps the responses to deblading do not occur.

Explants from older plants abscind more slowly than those from younger plants and the difference can be related to the higher sensitivity to ethylene of younger explants, rather than to differences in their patterns of ethylene production. The nature of this sensitivity is briefly discussed.
PINOCYTOSIS, ATP‐ASE AND ION UPTAKE BY PLANT CELLS
Authors: BAKER D. A. , HALL J. L.
Published: May 2006

The possible role of membrane‐bound vesicles in the uptake of ions by plant cells is discussed. Evidence of compartmentation obtained from kinetic analyses of the influx and efflux of ions is considered in conjunction with the findings of biochemical and cytochemical studies of ATP‐ase activity and localization with reference to the possible role of this enzyme in ion uptake. A model is proposed for ion uptake, an important feature of which is the formation of pinocytotic vesicles at the plasmalemma. This model also incorporates the differential pattern of uptake observed at low (system 1) and high (system 2) external concentrations. The relationship of such mechanisms to long‐distance transport of ions is considered.
ENHANCEMENT OF NITRATE REDUCTASE ACTIVITY IN SENESCING KALE LEAF DISCS BY N,N‐DIMETHYLAMINO‐SUCCINAMIC ACID
Authors: KNYPL J. S.
Published: May 2006

Freshly cut discs (385 mm2 total area) from mature leaves of kale (Brassica oleracea L. var. acephala) produced about 70 nmol NO‐2 when incubated with 0.02 M KNO3 for 3 hours. The amount of NO‐2 formed in the 3‐hour test was smaller when the discs were incubated on water for 24 hours before the test but it was much increased when the discs were incubated for 24 hours with KNO3, KNO3 plus N,N‐dimethylamino‐succinamic acid (B‐Nine) or B‐Nine alone. The effort of B‐Nine on increasing nitrate reductase activity was abolished by cycloheximide and unaffected by chloramphenicol. It is concluded that B‐Nine can induce the synthesis of nitrate reductase in the absence of light or of nitrate.
EFFECT OF ENDOGONE MYCORRHIZA ON PLANT GROWTH VI. INFLUENCE OF INFECTION ON THE ANATOMY AND REPRODUCTIVE DEVELOPMENT IN FOUR HOSTS
Authors: DAFT M. J. , OKUSANYA B. O.
Published: May 2006

The effect of Endogone infection on the stem anatomy and on the reproduction in tomato, maize, strawberry and petunia was examined. In tomato, petunia and maize plants, the infection increased the amount of vascular tissue. The lignification of the xylem was greater in mycorrhizal tomato and petunia plants and more vascular bundles were produced in the maize plants. Mycorrhizal infection stimulated flower production in petunia, the formation of fruit in strawberry and the development of pollen in maize.
THE SUPPLY OF PHOTOSYNTHETIC ASSIMILATES TO NODULES OF PISUM SATIVUM L. IN RELATION TO THE FIXATION OF NITROGEN
Authors: LAWRIE A. C. , WHEELER C. T.
Published: May 2006

A marked correlation was found between the accumulation of labelled photosynthates in nodules and the rate of acetylene reduction during the growth cycle of pea plants in nitrogen‐free culture. Both the rate of acetylene reduction and this accumulation of labelled photosynthates were reduced when plants were darkened for different lengths of time and then fed 14CO2 immediately on return to the light, but, when plants were fed 14CO2 prior to darkening, photosynthates continued to accumulate in the nodules as nitrogenase activity declined.

Micro‐autoradiography of active nodules indicated that the main site of accumulation of labelled photosynthates was the infected tissue. The main ‘sink’ appeared to be cells partially filled with bacteroids and little accumulation was observed in cells which were completely filled. By contrast, histochemical tests with tetrazolium salts suggested that the major sites of reduction were the cells which were totally occupied by bacteroids. The less densely filled cells showed much less reducing activity.

The main sites of accumulation of labelled photosynthates do not apparently correspond with the sites of most active reduction and a substantial part of the photosynthates received by the nodules therefore appears not to be deployed in nitrogen fixation. It is suggested that nitrogen fixation is supported mainly by a rapid, undetected flux of photosynthates through metabolically active cells densely filled with bacteroids, which have largely ceased to multiply.
MODERN POLLEN RAIN STUDIES IN ICELAND
Authors: RYMER L.
Published: May 2006

The relationship between modern pollen rain and the floristic composition of vegetation was studied for six vegetation types in Iceland, viz. fell‐field, Rhacomitrium heath, grassland with dwarf‐shrub, dwarf‐shrub heath, mires within dwarf‐shrub heath, and a Salix herbacea‐ dominated slope. The results suggest that the vegetation types examined can be characterized, to some degree, by their modern pollen rain.
THE POLARITY OF AUXIN TRANSPORT IN INVERTED CUTTINGS
Authors: SHELDRAKE A. R.
Published: May 2006

Summary

The original, basipetal polarity of auxin transport persisted in the stems of inverted cuttings of Tagetes, tomato and tobacco in spite of the reversal of the relative positions of the roots and shoots. No significant acropetal auxin transport could be detected even after four months growth. These results indicate that the polarity of newly formed cells in secondarily thickening internodes is determined by the existing polarity of auxin transport within the tissues.
ON THE INHIBITION OF MESOCOTYL GROWTH BY ETHYLENE
Authors: MER C. L.
Published: May 2006

Summary

Oat seedlings have been treated with ethylene‐generating substances, (2‐chloroethyl)phos‐phonic acid (ethrel) and β‐hydroxyethylhydrazine (B‐OH), as well as with gaseous ethylene in an attempt to confirm the claim that mesocotyl growth can be stimulated by ethylene. The factorially arranged experiments included a standard exposure to light to permit evaluation of the light × ethylene interaction.

Ethrel always inhibited growth and caused the malformations associated with ethylene treatment. In contrast, B‐OH brought about the ‘CO2 effect’; that is, mesocotyl growth was retarded at first but subsequently enhanced due to an increased number of cells having an unchanged final length, while the growth of the coleoptile was reduced. These plants showed no ethylene‐type distortions, however. As ethylene gas itself was invariably inhibitory it cannot be assigned any stimulatory properties at the concentrations used.

One treatment combination (B‐OH with CO2) caused the death, selectively, of the tip cells of the coleoptile. Even without these cells, allegedly an essential part of the growth‐regulatory system of the seedling, a promotion of mesocotyl growth was observed.

In the discussion support is deduced for the view that mesocotyl growth is not controlled by the tip of the coleoptile.
EFFECTS OF 2‐DEOXY‐d‐GLUCOSE ON THE GROWTH AND METABOLISM OF PROTOTHECA ZOPFII KRÜGER
Authors: RANA M. S. , CASSELTON P. J.
Published: May 2006

Summary

Some effects of 2‐deoxy‐D‐glucose (2‐DG) on the growth and metabolism of Prototheca zopfii Krüger are described. 2‐DG inhibits the rate of growth of the alga in medium containing glucose as carbon source and inhibition is more marked when fructose replaces glucose. Growth in medium containing acetate is not affected by the presence of 2‐DG. The addition of 2‐DG to carbohydrate starved cells, in addition to glucose, fructose or acetate, causes a marked increase in oxygen uptake; this is attributed to assimilation of 2‐DG. 2‐DG‐6‐phosphate inhibits the in vitro activity of glucose‐6‐phosphate dehydrogenase (E.G. 1.1.1.49) and experiments with radioactive glucose suggest that 2‐DG inhibits the oxidative pentose phosphate pathway of glucose metabolism in intact cells. Other effects of 2‐DG include inhibitions of glycogen‐UDP glucosyltransferase activity in vitro and of fermentation in vivo.
ORIGINS OF THE AMINO ACIDS IN PODS AND SEEDS OF VICIA FABA L.
Authors: KIPPS A. E. , BOULTER D.
Published: May 2006

Summary

Bloom node leaves and pods of 25‐35‐day‐old fruits of Vicia faba L. var. Triple White, were allowed to photosynthesize in 14CO2 and the distribution of label in pod and seed amino acids determined by autoradiography.

The pod was shown to export carbon to the seeds chiefly as aspartic acid. The leaf contributed sugars and serine directly and many other amino acids after metabolism of precursor compounds in the pod. The seed was apparently capable of amino acid interconversion and synthesis. Both leaf and pod donated carbon to seed protein, the leaf providing about ten times as much total seed carbon as did the pod.
SINK LIMITATION AND IMPORT OF ASSIMILATE INTO MATURE LEAVES
Authors: THROWER S. L.
Published: May 2006

Summary

Labelled assimilate can be caused to move into a mature leaf which does not normally import by a technique of sink modification. This consists of darkening the chosen sink leaf, removing other foliar sinks by defoliation and decapitation, and suppressing the activity of the root by chilling.
THE RICE SHOOT IN RELATION TO OXYGEN SUPPLY AND ROOT GROWTH IN SEEDLINGS GERMINATING UNDER WATER
Authors: KORDAN H. A.
Published: May 2006

Summary

Germinated rice seedlings completely submerged under water do not show normal root growth and vertical shoot growth unless the water is aerated. From this observation, and earlier ones, it is concluded that rice seedlings in stagnant water in darkness will not develop normally unless a supply of oxygen can be received via the shoot.
THE LOCALIZATION OF AN INSOLUBLE INTERMEDIATE IN GLUCOSE PRODUCTION IN THE LICHEN PELTIGERA POLYDACTYLA
Authors: PEVELING ELISABETH , HILL DAVID J.
Published: May 2006

Summary

In the lichen Peltigera polydactyla the localization of an insoluble intermediate in the production of glucose during photosynthesis by the algae was detected by high resolution autoradiography.
CRYPTOGEAL GERMINATION AND OTHER SEEDLING ADAPTIONS TO THE BURNING OF VEGETATION IN SAVANNA REGIONS: THE ORIGIN OF THE PYROPHYTIC HABIT
Authors: JACKSON GEORGE
Published: May 2006

Summary

Following a study of Butyrospermum paradoxum (Jackson, 1968), observations on the germination of several savanna shrubs and trees have been made. Plumule burying (cryptogeal germination) occurs in a number of species in widely separated families. It is suggested that this feature has arisen as a result of evolution in a habitat that has long been subject to annual burning. The problem remains as to whether the fires are to be regarded as natural or as due to the widespread use of burning by man.
NUMERICAL METHODS IN QUATERNARY PALAEOECOLOGY
Authors: GORDON A. D.
Published: May 2006

Summary

In some pollen analytical studies, the required information can be obtained without a complete analysis of the core. The paper describes, with a practical example, strategies for economically extracting the required information, and indicates some properties of these strategies.
A SIMPLE FIELD VERSION OF THE WINKLER DETERMINATION OF DISSOLVED OXYGEN
Authors: DREW EDWARD A. , ROBERTSON WILLIAM A. A.
Published: May 2006

Summary

A simple version of the Winkler method of determining dissolved oxygen is described. It is convenient for a wade range of field and laboratory studies.