bluuebunny/crossref_metadata_2025_split huggingface dataset:
Blood–brain barrier breakdown in septic encephalopathy and brain tumours*
Authors: Davies D. C. 
Published: March 2003

AbstractSeptic encephalopathy is associated with breakdown of the blood–brain barrier and cerebral oedema. These features are also common properties of brain tumours. Perimicrovessel oedema, disruption of associated astrocyte end feet and neuronal injury occur in a porcine model of acute septic encephalopathy. The adrenergic system has been implicated in the inflammatory response to sepsis and may play a role in controlling blood–brain barrier permeability, since the β2‐adrenoceptor agonist dopexamine inhibits perimicrovessel oedema formation whereas the α1‐adrenoceptor agonist methoxamine provokes it. Electron microscopy revealed tight junction opening in high‐grade astrocytoma microvessels. Expression of the tight junction protein occludin is reduced in these microvessels and this reduction is inversely correlated with the degree of cerebral oedema. Normal astrocytes secrete factors that induce barrier properties in endothelial cells, whereas high‐grade astrocytomas secrete vascular endothelial growth factor, which stimulates angiogenesis, down regulates occludin and increases endothelial cell permeability. The water channel protein aquaporin‐4 is normally expressed in astrocyte foot processes around cerebral microvessels. Its expression is massively up‐regulated in high‐grade astrocytoma and around metastatic adenocarcinoma. There is a significant correlation between aquaporin‐4 expression and the degree of cerebral oedema, but it is not clear whether increased aquaporin‐4 expression enhances oedema formation or clearance. These results suggest that the pathophysiology of brain oedema is multifactorial, but that there may be common processes operating regardless of the aetiology.
An anatomical and electrophysiological study of the genitofemoral nerve and some of its targets in the male rat
Authors: Zempoalteca René , Martínez‐Gómez Margarita , Hudson Robyn , Cruz Yolanda , Lucio Rosa Angélica 
Published: March 2003

AbstractAnatomical descriptions of the genitofemoral nerve (GFn) innervating the lower pelvic area are contradictory. Here we re‐examine its origin and innervation by its various branches of principal target organs in the male rat. Using gross dissection, electrophysiological techniques and retrograde tracing of motoneurones with horseradish peroxidase, we confirm that the GFn originates from lumbar spinal nerves 1 and 2, and that at the level of the common iliac artery it divides into a lateral femoral and a medial genital branch. In contrast to previous studies, we report that the genital and not the femoral branch innervates the abdominal–inguinal skin, and not only the genital but also the femoral branch innervates the cremaster muscle (Cm) surrounding the testes. Motoneurones innervating the Cm proper are located in the ventral nucleus of L1 and L2, and those innervating the muscular transition region of the rostral Cm are located in the ventral nucleus in L1 and the ventrolateral nucleus in L2. The GFn may contribute to male reproductive performance by transmitting cutaneous information during copulation and, via contraction of the Cm to promote ejaculation, the protective displacement of the testes into the abdominal cavity during fighting and as a sperm‐protecting thermoregulatory measure.
Characteristics of a caesium‐resistant (Cs+‐R) mutant of the N2‐fixing cyanobacterium Nostoc muscorum: dependence on Cs+ or Rb+ for normal diazotrophy and osmotolerance
Authors: SINGH S. , SINGH A. K. , CHAKRAVARTHY D. , SINGH T. P. K. , SINGH H. N. 
Published: March 2003

SUMMARYSpontaneous mutation of the cyanobacterium Nostoc muscorum to a caesium resistant (Cs+‐R) phenotype resulted in severe impairment of its nitrogenase activity, oxygenic photosynthesis, chlorophyll a content and osmotolerance. Among alkali cations only Cs+ or Rb+ restored these physiological processes to an almost normal level. Parent and mutant were similar with respect to Cs+ or Rb+ uptake and accumulation and also to regulation by NH4+. The ions Na+ or K+, at much higher concentration, significantly influenced Cs+ uptake and accumulation in both the mutant and the parent. These findings have important implications for cyanobacteria growing in Cs+‐polluted habitats.
Xylem sap abscisic acid concentration and stomatal conductance of mycorrhizal Vigna unguiculata in drying soil
Authors: EBEL ROBERT C. , DUAN XIANGRONG , STILL DAVID W. , AUGE ROBERT M. 
Published: March 2003

SUMMARYThis study was conducted to determine whether xylem abscisic acid (ABA) concentration is altered by mycorrhizal symbiosis of cowpea plants grown in drying soil, and to determine whether stomatal sensitivity to xylem ABA is altered by the symbiosis. We allowed the entire root zone to dry and found that at high soil water contents (θ), mycorrhizal plants had higher stomatal conductance (gs) and lower xylem [ABA]than did non‐mycorrhizal plants, but the difference disappeared at low tH, probably because of stomatal closure. The altered gs and xylem [ABA] were apparently not related to plant water status since shoot water potential, xylem sap osmotic potential and shoot water content were similar for mycorrhizal and non‐mycorrhizal plants across the range of soil moisture. These differences were also not related to P nutrition or plant size. The relationship of gs to xylem [ABA] was not affected by the symbiosis, indicating that either stomatal sensitivity to xylem ABA was not affected by other xylem constituents, or that more than one xylem constituent was altered by the symbiosis but was offsetting in its effect on gs. We conclude that the symbiosis altered gs non–hydraulically, and that the factor might be xylem ABA.
Effects of long‐term atmospheric CO2 enrichment on the mineral concentration of Citrus aurantium leaves
Authors: PEÑUELAS JOSEP , IDSO SHERWOOD B. , RIBAS ANGELA , KIMBALL BRUCE A. 
Published: March 2003

summaryLeaf mineral concentration of Citrus aurantium (sour orange tree) was measured at bi‐monthly intervals from 30 to 85 months of exposure in a long‐term study on the effects of a 300 μmol mol−1 enrichment of atmospheric CO2, under conditions of high nutrient and water supply. There were clear seasonal trends in the concentrations of most of the elements studied. There were initial decreases in the leaf concentrations of N and the xylem‐mobile, phloem‐immobile elements Mn, Ca and Mg, as well as a significant and sustained increase in the leaf concentration of B, and no changes in the concentrations of K, Fe, Na, P, S, Zn and Cu. Interestingly, the initial reductions in the leaf concentrations of Mn, N, Ca and Mg gradually disappeared with time.
Infection of mottled stripe disease‐susceptible and resistant sugar cane varieties by the endophytic diazotroph Herbaspirilium
Authors: OLIVARES F. L. , JAMES E. K. , BALDANI J. I. , DÖBEREINER J. 
Published: March 2003

SUMMARYLeaves of a mottled stripe disease‐susceptible cultivar (B‐4362) and of a mottled stripe disease‐resistant cultivar (SP 70–1143) of sugar cane (interspecific hybrids of Saccharum) were inoculated with the diazotrophic endophytes, Herbaspirillum rubrisubalbicans or Herbaspirillum seropedicae, via injection into the apex of the stem. At 7 and 20 d.a.i., H. seropedicae could be isolated only from a small necrotic area around the point of inoculation, where there was considerable degradation of host cells, and was not detected in any other part of the leaves. This suggested a hypersensitive response by the host to this bacterium, and no disease symptoms formed on either cultivar. By contrast, H. rubrisubalbicans could be re‐isolated from throughout the infected leaves of both cultivars at both harvests and produced widespread disease symptoms on the leaves of cv. B‐4362.Symptoms consisted of necrotic regions near the point of inoculation, and red stripes and red patches along the vertical axis of the leaves, where the bacteria had spread in the primary and secondary veins. The xylem–conducting elements in diseased regions of leaves were filled with bacteria and, at the edges of disease symptoms, the vessels were filled with a gum which stained blue‐green with toluidine blue. This material probably contained phenolic compounds, and was produced as a host defence response. Leaves of cv. SP 70–1143 only developed small red stripes near the point of inoculation. These symptoms did not spread along the leaves, and the infected xylem vessels were never seen to be completely full of bacteria. Instead, the vessels contained encapsulated bacterial colonies attached to secondary wall deposition; these colonies were surrounded by blue‐green material that might have been host‐defence gums. In cv. B‐4362, bacteria were abundant in the intercellular spaces of mesophyll adjacent to infected xylem, and also filled sub–stomatal cavities. Immunogold labelling using polyclonal antisera raised against H. rubrisubalbicans gave a weak signal with the bacteria in cv. SP 70–1143, showing that few binding sites were available to the antibodies. By contrast, bacteria in cv. B‐4362 reacted strongly with the antibody, suggesting that they had a denser coating of immunoreactive mucus. In the later stages of infection of cv. B–4362, lysed bacteria were seen within degraded plant cells surrounded by a matrix of plant gums and bacterial mucus. This matrix reacted strongly to the H. rubrisubalbicans antibodies. Immunogold labelling using antibodies against nitrogenase component II showed that nitrogenase was expressed by bacteria in the early stages of infection of cv. B–362, but not in later stages, or by bacteria infecting cv. SP 70–1143.
Influence of cucumber mosaic virus infection on the competitive ability and reproduction of chickweed (Stellaria media)
Authors: FRIESS N. , MAILLET J. 
Published: March 2003

SUMMARYChickweed plants (Stellaria media Vill.), either inoculated with cucumber mosaic virus (CMV) or not, were grown to reproductive maturity at a range of densities, both in monoculture and in mixture. CMV infection did not influence the vegetative growth of plants grown in monoculture. Similarly, the total vegetative production of a population containing infected and healthy plants was the same as that of a monoculture of healthy plants. However, infected plants were disadvantaged when in competition with healthy plants, the disadvantage increasing with density and the proportion of healthy plants. Investment in sexual reproduction was reduced in infected plants at all densities and in healthy plants at high densities. In very hard conditions, plants did not even produce seeds.
Effects of soil trenching on occurrence of ectomycorrhizas on Pseudotsuga menziesii seedlings grown in mature forests of Betula papyrifera and Pseudotsuga menziesii
Authors: SIMARD SUZANNE W. , PERRY DAVID A. , SMITH JANE E. , MOLINA RANDY 
Published: March 2003

SUMMARYSeedlings of Pseudotsuga menziesii (Mirb.) Franco were grown for six‐16 months in untrenched and trenched treatments in three 90–120‐yr‐old mixed forests dominated by Betula papyrifera Marsh, and P. menziesii in the southern interior of British Columbia. Each forest was characterized by mesic conditions and low light intensity (PAR < 200 μmol m−2 s−1) in the understorey. The objective of the study was to evaluate the influence of overstorey tree roots on (i) ectomycorrhizal fungal composition, richness and diversity, and (ii) photosynthesis and growth of understorey P. menziesii seedlings. Seventeen ectomycorrhizal morphotypes were recognized on seedlings in the untrenched treatment, and nine in the trenched treatment over the three sites. Six types occurred in both treatments, of which on average Rhizopogon vinicolor Smith type was 20 times more abundant and Thelephora type six times less abundant in the untrenched as in the trenched treatment. Of types that formed strands or rhizomorphs, eight occurred in the untrenched treatment, where they occupied on average 23% of root tips, and only four occurred in the trenched treatment over 4% of the root tips. Mean richness, diversity, and evenness of ectomycorrhizal associates per seedling were approx. twice as great in the untrenched as in the trenched treatment.Net photosynthetic rate of P. menziesii seedlings was greater in the untrenched than in the trenched treatment in July and August, but not in September 1994. Height, diameter and biomass of seedlings did not differ between treatments, but height: diameter ratio was greater in the untrenched treatment at time of harvest. The effect of trenching on seedling performance was attributed mainly to differences in ectomycorrhizal colonization patterns because trenching had no significant effect on soil nutrient concentrations (total C, total N, NH4‐N, available N, exchangeable Ca, exchangeable Mg, exchangeable K), C:N ratio, soil pH or light availability. Nor was there a significant difference in soil water in August, when seedlings in untrenched plots had higher net photosynthetic rates than those in trenched plots. Results suggest that influence of overstorey trees and pattern of ectomycorrhizal formation are important to P. menziesii seedling performance in deeply shaded forest environments.
Responses of Lotus corniculatus to environmental change
Authors: CARTER E. B. , THEODOROU M. K. , MORRIS P. 
Published: March 2003

SUMMARYFive clonal plants of three genotypes of Lotus corniculatus were grown in each of eight controlled environments under combinations of two temperature regimes (18/10 °C and 25/15 °C), two CO2 concentrations (ambient and 700 ppmv) and two water applications (ad libitum or 60% draughted). Plants were harvested at full flower and measurements made of plant growth and development. Of the three environmental variables studied, higher growth temperatures resulted in the largest number of significant changes to the measured variables. Reproductive capacity, growth rate, shoot biomass, water use efficiency and chlorophyll content were all enhanced by raising the growth temperature from 18 to 25 °C. Doubling the CO2 concentration enhanced the growth rate, shoot biomass and water use efficiency and ameliorated some of the effects of drought, including reproductive capacity, and biomass production, but reduced flowering time, specific leaf area, and chlorophyll content of both droughted and undroughted plants. Drought alone reduced reproductive capacity, growth rate and above ground biomass but significantly increased root biomass in all environments. The agronomic effects resulting from a combined increase in growth temperature, doubled CO2 concentration and mild drought in this experiment were a shorter vegetative period and an increase in biomass, but a fall in reproductive capacity.
Effects of elevated CO2 and soil–nitrogen supply on chlorophyll fluorescence and gas exchange in Scots pine, based on a branch–in–bag experiment
Authors: WANG KAI‐YUN , KELLOMÄKI SEPPO 
Published: March 2003

SUMMARYApplying the branch‐in‐bag method, naturally seeded Scots pine (Finns sylvestris L.) trees, 25–30 yr old, were subjected to two CO, concentrations (350 and 700/tmol mol') and two soil‐nitrogen‐supply regimes for three growing seasons (1994–96). Gas exchange and chlorophyll a fluorescence in detached shoots were measured simultaneously in a diffuse radiation field. Elevated CO, did not lead to a significant ‘downward regulation’ in the light‐saturated rate of net photosynthesis (Pn,max), the maximum apparent quantum yield (aA,max) or the maximum photochemical efficiency (Fv/Fm) of photosyscem II (PS II). However, the elevated CO2 significantly decreased the light‐saturated stoniatal conductance and increased the sensitivity of stoniatal conductance to change in low photon‐flux densities. The high soil‐nitrogen supply significantly increased photosvnthetic capacity, as manifested by increases in Pn,mBS, £tAjMBlFJFm, and the effective photochemical efficiency (dLF/F'm) at low photon‐flux densities, did not, on the other hand, enhance the magnitude of photosynthetic response to elevated CO2concentration. In addition, the treatment‐induced modifications in fluorescence parameters are discussed in detail.
The biology of mycorrhiza in the Ericaceae
Authors: KERLEY SIMON J. , READ DAVID J. 
Published: March 2003

SUMMARYMeasurements of the chitin content of the rooting horizons of a typical mor‐humus heathland soil, indicate that chitin can contain in excess of 20% of the total nitrogen in the litter (L) horizon and 30% in the fermentation (F) horizon. Much of this chitin‐nitrogen is thought to be contained in the mycelial walls of soil fungi.Experiments were therefore designed to test the hypothesis that such sources of N could be rendered accessible to the ericaceous plants by their fungal endophytes. Mycelium of the ericoid endophyte Hymenoscyphus ericae (Read) Korf & Kernan and of the ectomycorrhizal fungus Suillus bovinus (Fr.) O. Krantze were grown in liquid culture before being killed and added either in the intact condition, or after fractionation, as sole sources of N to sterile media upon which were grown H. ericae in pure culture, or mycorrhizal and non‐mycorrhizal plants of Vaccinium macrocarpon Ait. and Calluna vulgaris L. The abilities of the test organisms to utilize the nitrogen contained in the intact mycelial necromass, or in its fractions, were assessed by determining their yields and nitrogen concentrations of their tissues.It was revealed that H. ericae was able to produce significantly higher yield when grown on intact fungal necromass than when provided with equivalent concentrations of N in the form of ammonium. Its yields on mycelial fractions were lower, but still significantly greater than those obtained in the controls lacking N. Significantly greater yields and N contents were also found in the ericaceous plants grown with these nitrogenous substrates in the mycorrhizal condition. Without H. ericae they had no access to the substrates. The possible ecological implications of these results are discussed.
Plant growth and reproduction on a toxic alpine ultramafic soil: adaptation to nutrient limitation
Authors: NAGY LASZLO , PROCTOR JOHN 
Published: March 2003

summaryThe ultramafic sites at Meikle Kilrannoch, Scotland, have small sparsely colonized patches with soils which have highly toxic (to many non‐indigenous plants) concentrations of Mg and Ni. These toxic metals are unlikely to be the main cause of the open vegetation as the indigenous plants are at least partially tolerant of them. The hypothesis that low. soil nutrients were a likely cause of the open vegetation was tested by a fertilization experiment in which major nutrients and Ca were added in August 1991 and July 1992 to replicated quadrats which initially had 5.3‐6.6% plant cover. There was a large increase in plant cover on major nutrient addition. The increase in rosette size, flowering, seed production, and recruitment of the dominant semelparous Cochlearia pyrenaica DC. ssp. alpina (Bab.) Dalby was studied in detail. The increased growth of Cochlearia (and some other native species at the site) on nutrient addition strengthens the argument that a major nutrient deficiency rather than a metal toxicity limits plant growth at Meikle Kilrannoch and shows that at least some stress tolerators respond with rapid growth and reproduction when nutrient limitation is removed. A small‐scale experiment set up in June 1993, in which the major nutrients were added separately, suggested that P and not N, or K was the limiting element. The effects of P seem to be unrelated to any possible reduction in the availability of the toxic ions Mg2+and Ni2+.
Enhanced ozone‐tolerance in wheat grown at an elevated CO2 concentration: ozone exclusion and detoxification
Authors: MCKEE I. F. , EIBLMEIER M. , POLLE A. 
Published: March 2003

summaryElevated [CO2] has been shown to protect photosynthesis and growth of wheat against moderately elevated [O3]. To investigate the role of ozone exclusion and detoxification in this protection, spring wheat (Triticum aestivum L. ev. Wembley) was grown from seed, in controlled‐environment chambers, under reciprocal combinations of [CO2] at 350 or 700 μmol mol−1and [O3] peaking at < 5 or 60 nmol mol−1, respectively. Cumulative ozone dose to the mesophyll and antioxidant status were determined throughout flag leaf development. Catalase activity correlated with rates of photorespiration and declined in response to elevated [CO2] and/or [O3]. Superoxide dismutase activity was not significantly affected by either condition. Neither ascorbate nor glutathione content was enhanced by elevated [CO2]. In wheat, at moderately elevated [O3], our results show that stomatal exclusion plays a major role in the protective effect of elevated [CO2] against O3 damage.
Biology of the ectomycorrhizal genus, Rhizopogon
Authors: MOLINA RANDY , SMITH JANE E. , MCKAY DONARAYE , MELVILLE L.H. 
Published: March 2003

summarySeedlings of Pseudotsuga menziesii (Mirb.) Franco, Pinus ponderosa Dougl. ex Laws, Arbutus menziesii Pursh., and cuttings of Arclast apliylos uva‐ursi (L.) Spreng were grown in monoculture and in conifer‐hardwood dual‐culture combinations in the glasshouse and inoculated with spore slurries of six Rhizopogon species. The primary objectives were to assess and compare the pattern of host specificity between symbionts and to study the influence of co‐cultured plants on ecromycorrhiza development. The Rhizopogon spp. ranged from genus‐specific to multiple‐host compatible. In monoculture, four Rhisopogon sp, (R. ellenae Smith, R. occidentalis Zeller & Dodge, R. smithii Hosfnrd and R. subcaerulescens Smith) formed ectomycorrhizas with Pinus ponderosa, and two Rhizopogon sp. (R. parksii Smith and R. vinicolor Smith) formed ectomycorrhizas with Pseudotsuga menziesii. None of the fungi tested developed ectomycorrhizas on Arbutus menziesii or Arctostaphylos uvaursi in monoculture. In dual culture, three of the four Rhizopogon species (R. ellenae, R. occidentalis and R. subcaerulescens) that formed ectomycorrhizas on Pinus ponderosa, formed some ectomycorrhizas on Arbutus menziesii and Arrtastaphvlos uva‐ursi. Rhizopogon parksii and R. tinicoior only formed ectomycorrhizas on Pseudotsuga mensiesti.
Laser ablation of the cell wall and localized patch clamping of the plasma membrane in the filamentous fungus Aspergillus: characterization of an anion‐selective efflux channel
Authors: ROBERTS STEPHEN K. , DIXON GRAHAM K. , DUNBAR STUART J. , SANDERS DALE 
Published: March 2003

summaryWe have used a pulsed u.v. laser to ablate the cell wall of the filamentous fungus Aspergillus niger van Tiegh., and expose the plasma membrane at defined points along the hypha. Using the patch clamp technique, giga ohm seals (up to 20 GΩ) and recordings of plasma membrane ion channels were obtained. We describe, for the first time in fungi, a 43 pS plasma membrane anion efflux channel. Its potential role in cell signalling and pH homeostasis is discussed.