bluuebunny/crossref_metadata_2025 huggingface dataset:
Mast cells in the sheep, hedgehog and rat forebrain
Authors: MICHALOUDI HELEN C. , PAPADOPOULOS GEORGIOS C.
Published: March 2003

The study was designed to reveal the distribution of various mast cell types in the forebrain of the adult sheep, hedgehog and rat. Based on their histochemical and immunocytochemical characteristics, mast cells were categorised as (1) connective tissue‐type mast cells, staining metachromatically purple with the toluidine blue method, or pale red with the Alcian blue/safranin method, (2) mucosal‐type or immature mast cells staining blue with the Alcian blue/safranin method and (3) serotonin immunopositive mast cells. All 3 types of brain mast cells in all species studied were located in both white and grey matter, often associated with intraparenchymal blood vessels. Their distribution pattern exhibited interspecies differences, while their number varied considerably not only between species but also between individuals of each species. A distributional left‐right asymmetry, with more cells present on the left side, was observed in all species studied but it was most prominent in the sheep brain. In the sheep, mast cells were abundantly distributed in forebrain areas, while in the hedgehog and the rat forebrain, mast cells were less widely distributed and were relatively or substantially fewer in number respectively. A limited number of brain mast cells, in all 3 species, but primarily in the rat, were found to react both immunocytochemically to 5‐HT antibody and histochemically with Alcian blue/safranin staining.
The arterial supply to the digits of the forelimb in the Bactrian camel (Camelus bactrianus)
Authors: WANG JIAN‐LIN , GAO‐LAN  , WANG GEN‐XUAN , LI HAI‐YAN
Published: March 2003

The arterial supply of the digits of the forelimb of the Bactrian camel is described. The arteries supplying the digits were the palmar metacarpal and common palmar digital arteries III. The palmar metacarpal artery III was the continuation of the deep medial proximal metacarpal branch which was derived from the medial branch of the radial artery. It gave rise to a nutrient branch, medial branch, lateral branch and distal perforating palmar branch at the proximal end of the distal sixth of the cannon bone (fused third and fourth metacarpal bones). The common palmar digital artery III was the continuation of the median artery, which divided into medial and lateral branches. The medial branch of common palmar digital artery III which occasionally arose from the axial palmar proper digital artery III, after giving rise to the axial proximal proximal phalangeal branch, divided into the axial and abaxial palmar proper digital arteries III. The axial palmar proper digital artery III gave off the dorsoaxial distal proximal phalangeal, dorsoaxial proximal middle phalangeal, dorsoaxial distal middle phalangeal, palmoaxial middle phalangeal, palmoaxial distal phalangeal, dorsoaxial distal phalangeal branches, coronal artery and some digital tori branches. The abaxial palmar proper digital artery III gave rise to the abaxial proximal proximal phalangeal, dorsoabaxial distal proximal phalangeal, dorsoabaxial middle phalangeal, palmoabaxial middle phalangeal, palmoabaxial distal phalangeal, dorsoabaxial distal phalangeal branches, coronal artery and some digital tori branches. The lateral branch of the common palmar digital artery III in its origin, course, branching pattern and supply in the fourth digit was similar to the medial branch of common palmar digital artery III in the third digit.
Rearrangement of extracellular matrix during cluster formation by human luteinising granulosa cells in culture
Authors: RICHARDSON M. C. , SLACK C. , STEWART I. J.
Published: March 2003

Human ovarian granulosa cells were cultured on a basement membrane preparation (Matrigel) to investigate the role of extracellular matrix components in granulosa cell cluster formation. Time‐lapse videomicroscopy of these cultures revealed a rapid aggregation of cells which was initiated during the first 2–4 h of culture so that by 8 h most of the granulosa cells were incorporated into clusters. Further amalgamation then occurred with the transfer of cells along ‘bridges’ between combining clusters. The clustering process, which was complete by about 24 h, was accompanied by reorganisation of matrix which was visualised by immunolabelling of laminin. Clustering cells appeared to gather matrix which became distributed around the clusters. Confocal microscopy showed matrix to be present over the surface of each cluster as well as around the base apparently anchoring the aggregate to the culture surface. Results suggest the potential for active rearrangement of matrix by granulosa‐derived cells during corpus luteum development.
Professor J. M. F. Landsmeer (1919–1999)
Authors: KAUER JOHN M. G. , HUSON ANTHONY
Published: March 2003

Johan Matthijs Frederik (Hans) Landsmeer, Professor Emeritus of Anatomy and Embryology at the University of Leiden, died on 12 June 1999, at the age of 80. He was a gifted scientist who had devoted his professional life to research in Anatomy and Embryology. During his career he was successful in blazing new trails in the relation of morphology to function. This resulted in an impressive list of publications frequently cited in the literature. His sharp analytical approach to problems was a striking feature and illustrated his aversion to superficiality. In this way he collected a profound and inspiring knowledge of human and comparative anatomy and embryology and he knew exactly how to pass on this knowledge to others. Therefore it is not surprising that he guided a substantial number of disciples to the completion of a PhD thesis, thus forming a school. His ability to translate his concepts in a way to have them accepted in the solution of clinical problems is also generally recognised. He was a skilful dissector. The results of his work were brought together in Landsmeer's Atlas of Anatomy of the Hand, published in 1976. This volume represents his meticulous morphological analysis of structures and his ability to intermingle the gross and fine structure of the hand to its function. This has opened perspectives for the surgeon engaged in the treatment of this most difficult area.

Hans Landsmeer had a strong affiliation to the University of Leiden. Born on 14 January 1919 in Rotterdam, where he spent his youth, he started his medical studies at the Leiden University in 1935. In 1939, before graduating he entered the Department of Anatomy and Embryology, and he stayed there until his retirement. This continuity was only interrupted during World War II. In November 1940 the University of Leiden was closed by the Nazis in connection with a rectorial address on 26 November protesting against the exclusion of the Jewish professors. Without any doubt this major event made a deep impression on him. During his career he consistently refused any invitation from countries where democracy was violated.
NMDA receptors in the basal ganglia
Authors: RAVENSCROFT PAULA , BROTCHIE JONATHAN
Published: March 2003

The basal ganglia consist of several interconnected nuclei located in the telecephalon, diencephalon and mesencephalon that are involved in a variety of motor and non‐motor behavioural functions. Glutamate receptors play a major role in neurotransmission within the basal ganglia and are present in all nuclei of the basal ganglia. This review focuses on the contribution of the NMDA class of glutamatergic receptors to various movement disorders whose primary pathology lies within the basal ganglia and discusses how pharmacological manipulation of such receptors may be therapeutically useful.
The AS/AGU rat: a spontaneous model of disruption and degeneration in the nigrostriatal dopaminergic system
Authors: PAYNE A. P. , CAMPBELL J. M. , RUSSELL D. , FAVOR G. , SUTCLIFFE R. G. , BENNETT N. K. , DAVIES R. W. , STONE T. W.
Published: March 2003

The AS/AGU rat provides an alternative to experimentally produced laboratory models of basal ganglia disorders. This mutant is characterised by disturbances of movement including clumsy gait, whole body tremor, rigidity and difficulty in initiating movement. From an early age, there is a profound depletion of extracellular dopamine in the dorsal caudate‐putamen as measured via in vivo microdialysis; levels are only 10–20% of those found in the parent Albino Swiss (AS) strain. Subsequently a depletion of whole tissue dopamine levels occurs and, later still, loss of dopaminergic cells in the substantia nigra pars compacta. The dysfunction in movement and the nigrostriatal dopaminergic system are clearly linked, since movement can be ameliorated by L‐DOPA administration. Furthermore, there are depletions in glucose utilisation in several regions of the basal ganglia circuitry, including the substantia nigra pars compacta, the subthalamic nucleus and the ventrolateral thalamus. The AS/AGU rat represents a unique opportunity to investigate the intrinsic factors controlling the integrity of dopaminergic systems and the recent successful positional cloning of the agu gene will allow the molecular mechanisms underlying this interesting phenotype to be analysed.
Immunohistochemical analysis of development of desmin‐positive hepatic stellate cells in mouse liver
Authors: NITOU MIHO , ISHIKAWA KATSUTOSHI , SHIOJIRI NOBUYOSHI
Published: March 2003

Development of desmin‐positive hepatic stellate cells was studied in mice using double immunofluorescent techniques and in vitro cultures with special attention given to their cell lineages. Several studies recently reported on the presence of cells that are immunologically reactive with both antidesmin and anticytokeratin antibodies in young fetal rat livers, and suggested the possibility that these cells give rise to hepatocytes and hepatic stellate cells. At early stages of mouse liver development, stellate cells with desmin‐positive filaments were scattered in the liver parenchyma. However, the stellate cells definitely differed from hepatoblasts and hepatocytes in terms of their morphology and expression of desmin and hepatoblast and hepatocyte‐specific E‐cadherin in the liver. Fetal hepatoblasts and hepatocytes did not react with antidesmin antibodies, nor did desmin‐positive stellate cells express E‐cadherin in vivo and in vitro. Thus it is likely that desmin‐positive stellate cells and hepatoblasts belong to different cell lineages. In the fetal liver, the desmin‐positive stellate cells surrounded blood vessels, and extended their processes to haematopoietic cells and megakaryocytes. Many, but not all, hepatoblasts and hepatocytes were observed to be associated with the stellate cells. At fetal stages, cellular processes positive for desmin in the stellate cells were also thick compared with those in the adult liver, in which desmin‐positive stellate cells lay in Disse's space and were closely associated with all hepatocytes. These developmental changes in the geography of desmin‐positive cells in the liver parenchyma and their morphology may be associated with their maturation and interactions with other cell types.
Variations of the arterial pattern in the upper limb revisited: a morphological and statistical study, with a review of the literature
Authors: RODRÍGUEZ‐NIEDENFÜHR M. , VÁZQUEZ T. , NEARN L. , FERREIRA B. , PARKIN I. , SAÑUDO J. R.
Published: March 2003

A total of 192 embalmed cadavers were examined in order to present a detailed study of arterial variations in the upper limb and a meta‐analysis of them. The variable terminology previously used was unified into a homogenous and complete classification, with 12 categories covering all the previously reported variant patterns of the arm and forearm.
Soluble flt‐1 and the angiopoietins in the development and regulation of placental vasculature*
Authors: Charnock‐Jones D. Stephen
Published: March 2003

One of the key roles of the placenta is to mediate exchange of oxygen, nutrients and waste products between the maternal and fetal circulations. While some nutrients are actively taken up, oxygen is passively transported (i.e. it moves down a simple concentration gradient). To ensure an adequate supply as gestation progresses, the vascular structures in the human placenta remodel to facilitate this transfer. Under conditions in which oxygen is limited, at high altitude for example, these adaptations become more pronounced. In placentae obtained from high altitude the mean diameter of vessels is increased and the number of perivascular cells (pericytes) is reduced. Pericytes play an important role in modulating endothelial cell function and in their absence the endothelial cells are sensitive to growth factor withdrawal. The vascular remodelling that occurs in normal pregnancy is in part mediated by soluble factors (some produced by pericytes) and the level of these may in turn be regulated by local oxygen tension. We have shown that the mRNAs encoding both angiopoietins are present in the placenta and both are regulated by local pO2. Ang‐2 mRNA transcription is increased under reduced oxygen and the stability of Ang‐1 mRNA is reduced under similar conditions. Thus the ratio of mRNAs encoding these antagonistic factors changes (in favour of Ang‐2), in the placenta in response to a reduction in pO2. The adaptations seen in the placenta and the mechanism by which they are achieved may be generally applicable.
Recombinant human alpha‐2a interferon promotes an atypical process of mast cell secretion with ultrastructural features suggestive for piecemeal degranulation
Authors: Crivellato Enrico , Candussio Luigi , Mallardi Franco , Ribatti Domenico
Published: March 2003

Purified mast cells (MC), isolated from the rat peritoneum, were stimulated in vitro with recombinant human IFN‐α 2a (rhIFN‐α 2a) and studied ultrastructurally. Quantitative determination of histamine release was also performed. The following ultrastructural features were observed: (1) dilation of single granules, leading to the formation of cytoplasmic cavities filled with dissolved or eroded matrices; (2) induction of partially empty, non‐fused granule containers close to unaltered resting granules, a process very suggestive of piecemeal degranulation; (3) focal exocytosis, characterized by opening of single granules to the cell exterior and/or fusion of a few granules into small secretory channels. Histamine release was slightly increased in rhIFN‐α 2a‐treated MC, although not to significant levels. These results indicate that rhIFN‐α 2a induces a characteristic pattern of degranulation in rat peritoneal MC and that a small proportion of rhIFN‐α 2a‐stimulated MC shows ultrastructural features suggestive for piecemeal degranulation.
Hydrolysis of fructan in grasses: a β‐(2‐6)‐linkage specific fructan‐β‐fructosidase from stubble of Lolium perenne
Authors: MARX STEFAN P. , JOSEF NÖSBERGER , FREHNER MARCO
Published: March 2003

Several different fructan and sucrose hydrolysing enzyme activities were induced in roots and stubble (mainly leaf sheaths) of Lolium perenne L. plants after defoliation. Among those activities, a fructan‐β‐fructosidase (EC 3.2.1.80) that hydrolyses predominantly β‐(2‐6)‐fructosyl‐fructose linkages (6‐FEH) was purified from the stubble. The use of the substrate 6,6‐kestotetraose and high‐performance anion‐exchange chromatography with pulsed amperometric detection allowed linkage‐specific screening and sensitive analysis of enzyme activity. A 6‐FEH was extensively purified to yield one protein band as revealed by one‐dimensional sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS–PAGE). The 6‐FEH was separated from the contaminating β‐(2‐1)‐linkage‐specific fructan‐β‐fructosidase and invertase activities (EC 3.1.2.26) by ammonium sulphate precipitation, lectin‐affinity, anion‐exchange and size‐exclusion chromatography. The purified 6‐FEH was a glycoprotein with an apparent molecular mass of 65000, as determined by size‐exclusion chromatography, and of 69000 by SDS–PAGE. The 6‐FEH had an activity optimum in the range of pH 5.1 to 5.6. Temperatures above 30°C affected the stability of the enzyme activity; however, its temperature stability was increased in the presence of 6,6‐kestotetraose. The purified 6‐FEH activity hydrolysed the β‐(2‐6)‐linkages in 6,6‐kestotetraose and (1&6)‐kestotetraose at rates five times faster than the β‐(2‐1)‐linkages in 1,1‐kestotetraose and (1&6)‐kestotetraose. Fructose up to 50 mM did not affect 6‐FEH activity; conversely, sucrose substantially inhibited the enzyme activity. Other disaccharides did not affect 6‐FEH. It is suggested that sucrose might modulate 6‐FEH activity in vivo.
Effects of litter on substrate conditions and growth of emergent macrophytes
Authors: VAN DER PUTTEN W. H. , PETERS B. A. M. , VAN DEN BERG M. S.
Published: March 2003

summary

Three successive emergent macrophytes (Typha latifoliaL.,Phragmites australis(Cav.) Steudel andGlyceria maxima(Hartman) Holmbly) were each grown in substrates collected from three different zones of shoreline vegetation development (non‐vegetated sediment, the interface betweenT. latifoliaandP. australis, and degeneratingP. australis). The aim of the study was to assess whether accumulation of litter changes growth conditions ofP. australis, and to determine its effects on pre‐ and post successional plant species. The study was carried out by means of pot experiments in a glasshouse. Seedlings of the three species were cultured in fertilized and unfertilized substrates under both waterlogged and drained conditions.

In its own litter, growth ofP. australiswas strongly reduced, compared with the productivity of plants in substrates from preceeding successional stages, and could not be compensated for by fertilization or soil drainage. The redox potential of the substrate was not strongly reduced and the sediment density was well above the critical level. Soil sterilization by gamma‐irradiation did not improve growth substantially, although there was some positive effect in unfertilized substrate. Phytotoxic compounds might have caused poor growth ofP. australisin its own litter.T. latifoliaandG. maximawere relatively less affected by theP. australislitter. The possible importance of litter accumulation on species replacement in shoreline vegetation is discussed. It is concluded that the accumulation of organic matter should be considered as a factor affecting spatio‐temporal processes in littoral vegetation owing to its specific impact on the functioning of individual dominant plant species.
Purification and substrate specificity of an extracellular fructanhydrolase from Lactobacillus paracasei ssp. paracasei P 4134
Authors: MÜLLER M. , SEYFARTH W.
Published: March 2003

A novel extracellular fructanhydrolase was isolated from the culture filtrate of Lactobacillus paracasei ssp. paracasei P 4134 grown on a mineral medium supplemented with fructan extracted from Timothy (Phleum pratense L.) as the only carbon source. The enzyme was purified by a combination of ammonium sulphate precipitation, affinity chromatography, preparative isoelectric focusing and anion‐exchange chromatography. As a result of these procedures, the specific enzyme activity increased 93‐fold, with a final yield of 28·4%. The substrate‐specific activities against different fructan types were determined by incubating the enzyme fractions with fructan extracted from Timothy (predominantly β‐2,6 fructosyl‐fructose linkages), inulin from Dahlia tubers (mostly β‐2,1 fructosyl‐fructose linkages) and sucrose. The purified enzyme catalysed the hydrolysis of β‐2,6‐linked fructan more rapidly than the β‐2,1 linkages of inulin. Additionally, the enzyme showed low ability to hydrolyse sucrose. Fructose was the main product of the degradation of Timothy fructan and inulin, indicating a high exohydrolytic activity of the enzyme. It is proposed that the fructan‐degrading enzyme from L. paracasei ssp. paracasei P 4134 is a β‐D‐fructan‐fructohydrolase (EC 3.2.1.80). The enzyme preparation showed a single protein band in sodium dodecyl sulphate‐polyacrylamide gel electrophoresis with a mobility corresponding to molecular weight of c. 42 kDa. It was concluded that only one molecular weight of fructan‐degrading enzyme exists in L. paracasei ssp. paracasei P 4134.
Correlation between potassium efflux and copper sensitivity in 10 Arahidopsis ecotypes*
Authors: MURPHY ANGUS , TAIZ LINCOLN
Published: March 2003

To study the relationship between copper sensitivity and membrane permeability in Arabidopsis, the seedling growth rates (measured as root extension and f. wt increase) of 10 ecotypes with differing copper sensitivities were compared with their patterns of potassium efflux and copper uptake. At 36 h, inhibition of root extension in 40 μi Cu correlated well with K+ efflux (r= 0.96) and a decrease in osmolality (r= 0.96). By contrast, neither tissue osmolality nor K+ efflux correlated significantly with growth inhibition after 4 h Cu treatment. In detailed time‐course studies of two of the less sensitive ecotypes (Shadhara and Ws) and two of the more sensitive ecotypes (Berkeley and Limeport) in 20 μM Cu, growth, K+ retention and osmolality decreased rapidly during the first 4 h. Only the two less sensitive ecotypes recovered during the following 32 h. A similar pattern was observed with 40 μM Cu, except that growth inhibition was more marked. Interestingly, after 4 h the less sensitive ecotypes exhibited greater inhibition than the more sensitive. In time‐course measurements, the Cu contents of the four ecotypes were not significantly different when normalised on a f. wt basis. We conclude that variations in the metal sensitivities of Arabidopsis ecotypes are not due to constitutive differences in membrane permeability but, rather, to differences in the ability to reverse K+ efflux. The possibility that short‐term Cu‐induced K+‐leakage is regulated by channels rather than lipid oxidation is discussed.
Effect of the arbuscular mycorrhizal fungus Glomus fasciculatum on the uptake of amino nitrogen by Lolium perenne
Authors: CLIQUET JEAN BERNARD , MURRAY PHILIP J. , BOUCAUD JEAN
Published: March 2003

summary

The ability of ryegrass (Lolium perenne L.) to take up and utilize aspartic acid (Asp) and serine (Ser,), and the effect of colonization of the roots by the arbuscular mycorrhizal (AM) fungus Glomus fasciculatum (Thax. sensu Gerd.) were studied. The seedlings were grown under controlled conditions in a series of micro‐lysimeters. All plants were fed with a nutrient solution containing either nitrate, Asp or Ser as the sole N source. After 49 d, they were supplied with 15N labeled nitrate. Asp or Ser for 1 h and harvested.

AM colonization increased the growth and total N content of the plants in all cases. Similarly, the amount of Asp or Ser taken up was higher in AM than in control plants. There were no differences in biomass production between the nitrate and Ser‐fed plants. However uptake rates were lower for Ser than for nitrate. Growth of the Asp‐fed plants was significantly less than the other two treatments, and uptake of 15N‐Asp was lower than uptake of 15N‐Ser. Analysis of 15N incorporation into the amino acids extracted from the roots suggests the hydrolysis of Ser followed by re‐assimilation of the resulting ammonia via the GS‐GOGAT cycle. There were no differences in the patterns of accumulation of amino acids in the root‐zone of control and AM‐ryegrass. The implication of these results for the pathway of nitrogen transfer between plants is discussed.
Allozyme diversity and genetic structure in South‐Western populations of heather, Calluna vulgaris
Authors: MAHY G. , VEKEMANS X. , JACQUEMART AL. , DE SLOOVER JR.
Published: March 2003

summary

Genetic diversity, population genetic structure and gene flow in Calluna vulgaris (L.) Hull were assessed by means of seven allozyme loci scored in 18 populations from the South‐Western area of the species' range. Genetic diversity was lower (HT= 0.20) than reported for long‐lived widespread species but was characterized by a high number of alleles per locus (5.60 at the species level) of which more than 70% were rare. More than 95% of genetic variation was found at the intrapopulation level (GST= 0.047). High levels of past gene flow were inferred, based on the allozyme data (Nm= 5.2 from GST. Nm= 10.2 from the ‘private allele’ method). Calluna vulgaris exhibited several geographic patterns of genetic variation. Both cluster analysis, constructed with various genetic distances and principal components analysis showed that Spanish and Pyrenean populations were clearly different from those collected in the Massif Central and Belgium. Also, a trend for decreasing genetic diversity towards Northern populations was detected. These patterns might be related to the post‐glacial history of Calluna. In addition, it is shown that isolation by distance has played a role in the geographic shaping of genetic variation in this species.
The potential for the biological control of cavity‐spot disease of carrots, caused byPythium coloratum, by streptomycete and non‐streptomycete actinomycetes
Authors: EL‐TARABILY KHALED A. , HARDY GILES E. ST. J. , SIVASITHAMPARAM KRISHNAPILLAI , HUSSEIN ASSEM M. , KURTBÖKE D. IPEK
Published: March 2003

summary

Actinomycetes isolated from carrot rhizosphere were screened for theirin vitroandin vivoantagonism toPythium colorationVaartaja, a causal agent of cavity‐spot disease of carrots (Daucus carataL.). Forty‐five streptomycete and non‐streptomycete actinomycete isolates were screened forin vitroantagonism in a carrot bioassay. Of these, seven which reduced or prevented lesion formation were identified using cultural, morphological, physiological, biochemical and cell wall characteristics asStreptomyces janthimts, S. cinerochromogenes, Streptoverticilium netropsis, Actinomadura rubra, Actinoplanes philippinensis, Muromonospora carbonaceae, andStreptosporangium albidum.All seven isolates tested produced non‐volatile antifungal metabolites, but failed to produce inhibitory volatile compounds.Actinoplanef philippincnsisand M.carbonaceagrew epiphytically on the hyphae and oospores ofP. eoloratum.The external surface of the oospores of the pathogen was heavily colonized by both hyperparasites, their hyphae were found to coil tightly around the oospore wall, and frequently caused cytoplasmic collapse of oospores. Sporangia ofA. philippinensiswere often seen to emerge from the colonized hyphae and oospores ofP. eoloratum.None of the other actinomycete isolates showed hyperparasitism.

All seven isolates significantly reduced the incidence of cavity spot in soil artificially infested with the pathogen in the glasshouse.Streptomyces janlhinusandStfepto. albidumwere the most effective in reducing the disease in inoculated plants. In addition, all the actinomycetes species exceptAc. rubraandM. carbonacea, in the presence or absence of the pathogen, significantly (P< 0.05) increased mean fresh root weight compared to the treatment which includedP. thoriumonly. This study shows that these actinomycetes have considerable potential for future use as biocontrol agents of cavity spot under natural field conditions. This is the first report of cavity‐spot disease of carrots being controlled by microbial antagonists, and is the first report of non‐streptomycete actinomycetes to control aPythiumdisease.
Elevated CO2 and tree root growth: contrasting responses in Fraxinus excelsior, Quercus petraea and Pinus sylvestris
Authors: CROOKSHANKS MEG , TAYLOR GAIL , BROADMEADOW MARK
Published: March 2003

Root growth and respiration in elevated CO2 (700 μmol mol−1) was studied in three tree species, Fraxinus excelsior L., Quercus petraea. L. and Pinus sylvestris L. grown in open‐top chambers (OTCs) during a long‐term exposure (20 months), during which root systems were allowed to develop without restriction imposed by pots. Root growth, measured as root length using root in‐growth bags was increased significantly in trees exposed to elevated CO2, although the magnitude of the response differed considerably between species and with time of sampling, the greatest effect observed after 6 months in ash (ratio of elevated: ambient, e∶a; 3·40) and the smallest effect observed in oak (e∶a; 1·95). This was accompanied by changes in specific root length, with a significant decrease in all species after 6 months, suggesting that root diameter or root density were increased in elevated CO2. Increases in root length might have resulted from an acceleration in root cell expansion, since epidermal cell size was significantly increased in the zone of elongation in ash root tips (P<0·05).

Contrasting effects of elevated CO2 were observed for root carbohydrates, with significant increases in soluble sugars for all species (P<0·05), but both increases and decreases in starch content were observed, depending on species, and producing a significant interaction between species and CO2 (P<0·001). Exposure to elevated CO2 increased the total root d. wt for whole trees of all three species after 8 months of exposure, although the magnitude of this effect, in contrast to the root in‐growth study, was greatest in Scots pine and smallest in ash. No significant effect of elevated CO2 was observed on the root∶shoot ratio. Further detailed analysis of whole root systems after 20 months confirmed that species differences in root responses to elevated CO2 were apparent, with increased coarse and fine root production in elevated CO2 for Scots pine and ash respectively. Lateral root number was increased in elevated CO2 for all species, as was mean root diameter. Root respiration rates were significantly reduced in elevated CO2 for all three species. These results provide firm evidence that exposure of trees to future CO2 concentrations will have large effects on root system development, growth, carbohydrate status and respiration. The magnitude and direction of such effects will differ, depending on species. The consequences of such responses for the three species studied are discussed.
Ethylene produced by the lichen Cladina stellaris exposed to sulphur and heavy‐metal‐containing solutions under acidic conditions
Authors: KAUPPI M. , KAUPPI A. , GARTY J.
Published: March 2003

Podetia of the terricolous lichen Cladina stellaris (Opiz) Brodo, collected in an unpolluted rural area in N. Finland, were wetted with either H2O, diluted acidic solutions of H2SO4, HNO3 and NaHSO3, simulating acidic rain, or the following salts: K2SO4, KCl, CuSO4, CuCl2, Cu(NO3)3, ZnSO4, ZnCl2, Zn(NO3)2, FeSO4, FeCl2, Fe2(SO4)3, FeCl3 and Fe(NO3)3. The samples were further exposed to combined treatments in both acidic solutions, simulating acidic rain, and heavy metal salts in solution. Lichen samples wetted with H2O at pH 6·8, diluted solutions of H2SO4, HNO3 or a mixture of these two acids produced low concentrations of endogenous ethylene. The application of NaHSO3 greatly increased the production of ethylene. The application of KCl induced a higher rate of ethylene production than the application of K2SO4 solutions. The application of Cu‐containing solutions enhanced the production of ethylene. The influence of Zn was smaller than that of Cu. Iron was the most effective heavy metal to promote the production of ethylene: very high ethylene concentrations were detected upon the application of FeCl2. Combined treatments in H2SO4 or H2SO4+HNO3 followed by either FeCl2 or FeSO4, yielded higher concentrations of ethylene than the same treatments in a reversed order. The role of Fe ions in the production of ethylene is discussed in reference to previous works dealing with ethylene production in higher plants, fungi and algae.
Soluble and membrane symbiosis‐related polypeptides associated with the development of arbuscular mycorrhizas in tomato (Lycopersicon esculentum)
Authors: BENABDELLAH K. , AZCÓN‐AGUILAR C. , FERROL N.
Published: March 2003

To analyse the effect of arbuscular mycorrhizal (AM) colonization on tomato gene expression, two‐dimensional polyacrylamide gel electrophoresis (2D‐PAGE) patterns of crude extracts, soluble and membrane proteins of tomato roots, either mycorrhizal and the AM fungus Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe or non‐mycorrhizal, have been compared. In the three fractions analysed, AM colonization induced up‐regulation with down‐regulation of the synthesis of polypeptides already present in tomato roots and induction of some new polypeptides. Separation of root extracts into soluble and membrane fractions allowed us to identify two soluble, and five membrane‐bound, newly induced polypeptides in AM roots. Comparison of the protein patterns of AM roots with those of the external mycelium of G. mosseae showed that one of the newly induced polypeptides might correspond to a fungal polypeptide. By using this experimental approach, we have been able to detect 44 polypeptides that are differentially displayed in tomato roots as a consequence of the establishment of the AM symbiosis.
Arbuscular mycorrhizal colonization delays nucleus senescence in leek root cortical cells
Authors: LINGUA G. , SGORBATI S. , CITTERIO A. , FUSCONI A. , TROTTA A. , GNAVI E. , BERTA G.
Published: March 2003

Arbuscular mycorrhizas are a widespread symbiosis between soil fungi and plant roots. Flow cytometry, after DNase I partial digestion and DAPI staining, and light and electron microscopy were used to analyse chromatin condensation and nuclear conditions in mycorrhizal and control roots of Allium porrum. The 2C peak, detected by flow cytometry, split into two peaks representing two populations of nuclei, one more resistant and one more susceptible to the enzyme action. The microscopic analyses showed the presence of pyknotic and chromatolytic nuclei, two typical features of senescence. In order to quantify the senescing process, a terminal deoxynucleotidyl transferase assay was performed on extracted nuclei, later analysed by flow cytometry. The numbers of senescing nuclei and their DNA cleavage were higher in control plants. Our results show the existence of senescing nuclei in cortical cells of the bulbous monocotyledon A. porrum and the delaying effect of arbuscular mycorrhizas on senescence.
Mechanisms and regulation of reduction‐based iron uptake in plants
Authors: SCHMIDT WOLFGANG
Published: March 2003

Despite the usually high abundance of iron (Fe) in soils, the low solubility of Fe‐bearing minerals restricts the available Fe pools in most aerobic soils to levels that are far below those required for microbial or plant growth. To acquire the necessary amounts of Fe from the environment, organisms have evolved mechanisms that enhance the solubility and dissolution rate of Fe(iii) oxyhydroxides prevailing in aerobic soils. Chemically, these mechanisms are based on weakening of the Fe–O bond by reduction, chelation and protonation. Physiologically, two distinct and in all known cases mutually exclusive strategies can be distinguished: the excretion of siderophores capable of solubilizing external ferric Fe and subsequent uptake of the ferric siderophore complex; and reduction of Fe(iii) prior to uptake of the more soluble Fe2+ ion. With the exception of graminaceous species, in which Fe uptake is based on the former mechanism, the latter strategy is found in all cormophytes and certain algae, yeast and bacteria. In higher plants, the increase in their capacity to convert extracellular ferric to ferrous Fe is part of a series of physiological and morphological events that act in concert to achieve appropriate internal levels of Fe. It is this amalgam of features that determines the Fe efficiency of a species or cultivar that in turn affects the yield of economically important plants and the natural distribution of species. Adaptive changes to limited Fe availability have been studied at the molecular, physiological and whole‐plant level. This review summarises current knowledge of the components of reduction‐based Fe uptake in plants and presents an integrated view of the present understanding of mechanisms that control the rate and extent of Fe absorption by roots.
Time course of nodule development in the Discaria trinervis (Rhamnaceae) –Frankia symbiosis
Authors: VALVERDE CLAUDIO , WALL LUIS GABRIEL
Published: March 2003

The time course of initiation and development of root nodules was investigated in the South American actinorhizal shrub Discaria trinervis (Rhamnaceae). A local strain of Frankia (BCU110501) which was isolated from D. trinervis nodules, was used as inoculum. Inoculated seedlings were periodically studied under the light microscope after clearing with aqueous NaClO. In parallel, semithin and ultrathin sections were analysed by light and electron microscopy. Infection by Frankia BCU110501 involved intercellular penetration among epidermal and cortical root cells. Nodule primordia were detected from 6 d after inoculation, while bacteria were progressing through intercellular spaces of the outer layers of cortical cells. Invasion of host cells by the symbiont occurred 7–9 d after inoculation, and hypertrophy of the primordium cells was associated with Frankia penetration. Root hairs were not deformed during the early events of nodule formation. From 13 to 16 d after inoculation, the proximal cellular zone of the primordia behaved differently from the other tissues after NaClO treatment and remained darkly pigmented. At the same time, differentiation of Frankia vesicles started to occur inside already infected cells. By 16 d after inoculation, spherical vesicles of BCU110501 were homogeneously distributed in the host cells. These vesicles were septate and surrounded by void space. Frankia spores or sporangia were not observed in the nodule tissue. This study has clarified the mode of Frankia penetration in D. trinervis, one of the Rhamnaceae which also includes Ceanothus. The events involved in infection, nodule induction, host‐cell infection and vesicle differentiation have been characterized and identified as time‐segregated developmental processes in the ontogeny of D. trinervis root nodules.
Tetraphenylphosphonium cation (TPP+) is not a reliable membrane potential probe in the cyanobacterium Synechococcus R‐2 PCC 7942
Authors: RITCHIE RAYMOND J.
Published: March 2003

Uptake of the lipophilic cation, tetraphenylphosphonium (TPP+), which is often used as a membrane potential probe, was studied in the cyanobacterium Synechococcus R‐2 (PCC 7942) to determine if the technique was valid for these cells. Lipophilic cation probes are notorious for giving inconsistent estimates of membrane potential (ΔΨ) using the Nernst equation (ETPP+=ΔΨ). It is necessary to correct for the large amounts of TPP+ bound to the surface of the cells. The rate of equilibration of intracellular TPP+ is very fast (t½≈1–3 min), hence the permeability of the plasmalemma to TPP+ (PTPP+≈10–50 nm s−1) is very high. There appears to be an active uptake of TPP+ with a pH optimum at about pHo 7.5. TPP+ does not readily uncouple Synechococcus cells. Carbonyl cyanide p‐trifluoromethoxyphenylhydrazone (FCCP) and dinitrophenol depolarized ETPP+, but monensin made ETPP+ more negative. Accumulation of TPP+ is not affected by [K+] in the medium in a way consistent with it acting as a reporter of the membrane potential. Addition of K+, NH4+ and HCO3− altered the uptake rate of TPP+ in a way consistent with electrogenic uptake of these ions but the effects were smaller than those found using the 86Rb+/valinomycin and 201TI+ probes. A comparison has been made with ΔΨ determinations using other membrane potential probes. ETPP+ was often close to the value of the membrane potential obtained using other methods under control conditions but effects of experimental treatments are sometimes inconsistent with those found using other ΔΨ probes. The TPP+ method is therefore unreliable and could be seriously misleading.
Environmental effects on the fitness of triazine‐resistant and triazine‐susceptible Brassica rapa and Chenopodium album in the absence of herbicide
Authors: PLOWMAN AMY B. , RICHARDS A. J. , TREMAYNE MICHELLE A.
Published: March 2003

For a number of generations, we followed the frequency, performance and fecundity of an initial mixture (50∶50) of triazine resistant (R) and susceptible (S) but otherwise near‐isogenic lines of Brassica rapa (for 3 yr) and of Chenopodium album (for 2 yr) in neighbouring experimental garden plots, which differed in aspect (north‐facing versus south‐facing), shading, and transparent cover from precipitation. Each of eight treatments was replicated four times per species. Seed from each plot was kept separate and sown back in its plot of origin to provide the next generation. For both Brassica and Chenopodium, R frequency changed between generations. In Brassica R frequency declined consistently from an initial 0.5 and, after 2 yr, R plants had disappeared in all replicates in two treatments and averaged <0.126 in the remaining treatments. However, R frequencies in the smaller second generation samples in each year were less consistent. In Chenopodium, R frequency increased consistently from an initial 0.5 in all treatments and replicates during 1995 to average 0.772 on south‐facing sites and 0.675 on north‐facing sites. However, in 1996 Chenopodium R frequency did not change significantly from that in 1995 for any treatment. Brassica S plants were more fecund that R plants, except in shaded conditions, and south‐facing plots produced significantly more S seeds than north‐facing plots. Both Brassica plants and plots were more productive in 1996 than in 1995. By contrast, Chenopodium was much less productive in 1996, a season with more climatic extremes between plots than 1995. In 1995, R plants were more fecund than S plants in south‐facing plots and in covered conditions, but this difference was not detected in 1996. South‐facing Chenopodium plots were more productive than north‐facing plots in 1995, but the reverse was the case in 1996. Cover resulted in an increase in seed production in Chenopodium on south‐facing plots in 1995, but a decline in 1996. We conclude that selection might act against triazine‐resistant plants in B. rapa under the climatic conditions in the UK, but in C. album, which is more susceptible to extreme conditions of light and water stress, triazine‐resistant phenotypes might predominate in low stress cool moist conditions. We suggest that a relationship might exist between the overall climatic tolerance of a species, and climate thresholds beyond which herbicide‐resistant phenotypes might spread. Thus, in the absence of herbicide, it is not inevitable that the frequency of R phenotypes will decline in field conditions.
Importance of light and CO2 on the effects of endomycorrhizal colonization on growth and photosynthesis of potato plantlets (Solanum tuberosum) in an in vitro tripartite system
Authors: LOUCHE‐TESSANDIER D. , SAMSON G. , HERNÁNDEZ‐SEBASTIÀ C. , CHAGVARDIEFF P. , DESJARDINS Y.
Published: March 2003

A factorial analysis was conducted to investigate the effects of different levels of photosynthetic photon flux (PPF) and CO2 concentration on the interactions between the vesicular–arbuscular endomycorrhizal fungus Glomus intraradices and potato plantlets (Solanum tuberosum) cultured in an in vitro tripartite system. We observed that CO2 enrichment from 350 to 10000 ppm stimulated root colonization by the fungus, and that this stimulation was more pronounced under high PPF (300 μmol m−2 s−1) than low PPF (60 μmol m−2 s−1). Consistent with these observations, the effects of G. intraradices on dry matter production in potato plantlets were strongly dependent on the CO2 and PPF levels during cultivation. There was no significant effect of the mycorrhizal fungus on dry matter production at 350 ppm of CO2. However, under the high CO2 concentration, mycorrhiza had opposite effects on dry matter production depending on the PPF: a decrease (−21%) and a stimulation (+25%) of dry matter production after 2 wk of growth under low and high PPF, respectively, were observed in presence of G. intraradices relative to plantlets grown in its absence. Furthermore, in mycorrhizal plantlets grown under high levels of both PPF and CO2, the chlorophyll and carotenoid contents as well as the quantum yields of photosynthetic electron transport and the photochemical quenching qP of the chlorophyll‐a fluorescence measured near the PPF during growth were all higher than in non‐infected plantlets. Our results therefore indicate that mycorrhizal G. intraradices can alleviate the down regulation of photosynthesis related to sink limitation, and its effect on dry matter production is strongly dependent on the levels of CO2 and PPF during growth which determine the balance between the photosynthetic carbon uptake by the plantlets and the carbon cost by the fungus.
Pool sizes of fructans in roots and leaves of mycorrhizal and non‐mycorrhizal barley
Authors: MÜLLER JOACHIM , MOHR UWE , SPRENGER NORBERT , BORTLIK KARLHEINZ , BOLLER THOMAS , WIEMKEN ANDRES
Published: March 2003

The effect of arbuscular mycorrhizas on fructan accumulation was studied in barley (Hordeum vulgare) infected with Glomus mosseae. Treatments with and without fertilizer were included in order to distinguish between mere fertilizer effects and the effects of the symbiosis, and plants were harvested at two different time points, 35 and 50 d after planting. Fructan was the major storage carboyhdrate in both leaves and roots. The amounts of fructan were markedly altered in the mycorrhizal plants. In roots of non‐fertilized mycorrhizal plants, fructan pools were significantly greater than in the corresponding non‐mycorrhizal plants. By contrast, fertilization caused a general decrease in amounts of fructan in roots. The increase of fructan in mycorrhizal roots was correlated with a decrease of invertase activity. In leaves, fructan pools decreased or remained unchanged upon mycorrhizal infection; fertilization had a similar effect. However, when individual leaves of a plant were compared, intriguing effects of the mycorrhizal symbiosis could be observed. Whereas in non‐mycorrhizal plants, the youngest leaves had the highest fructan contents and the oldest leaves the lowest (as previously reported), this gradient was markedly altered in mycorrhizal plants, indicating systemic effects of mycorrhiza on assimilate partitioning in shoots.
Impact of leaf damage on growth of mountain birch shoots
Authors: HENRIKSSON JANNE , HAUKIOJA ERKKI , RUOHOMÄKI KAI
Published: March 2003

Canopies of heterophyllous trees expand by production of long shoots. We have previously shown in mountain birch (Betula pubescens ssp. czerepanovii) that damage to internode leaves within long shoots does not impede shoot growth, indicating that long‐shoot elongation occurs by means of external resources. To study to what extent leaves other than true long‐shoot leaves are necessary for the normal growth of mountain birch long shoots, we simulated herbivore damage to the two basal leaves of shoots (which flush simultaneously with short‐shoot leaves) and the short‐shoot leaves nearest to the long shoot within the branch. Damage to the two basal long‐shoot leaves significantly reduced long‐shoot growth. Additional damage to short‐shoot leaves, situated proximally to the long shoot, did not retard long‐shoot growth any more than damage to basal leaves alone. To determine the extent to which short‐shoot leaves within a large branch are responsible for the pooled long‐shoot production of the branch, we clipped differing proportions of short‐shoot leaves from such branches. We found small but significant reduction in the pooled length of the long shoots of the branch, presumably indicating a limited role in long‐shoot elongation of current photosynthates within the branch. Our experiments indicate that long shoots are not independent modular units in their carbon economy.