bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cholinergic and nitrergic innervation of ICC‐DMP and ICC‐IM in the human small intestine
Authors: Wang X.‐Y. , Paterson C. , Huizinga J. D. 
Published: September 2003

AbstractWith functional evidence emerging that interstitial cells of Cajal (ICC) play a role in smooth muscle innervation, detailed knowledge is needed about the structural aspects of enteric innervation of the human gut. Conventional electronmicroscopy (EM), immunohistochemistry and immuno‐EM were performed on the musculature of the distal human ileum focusing on ICC associated with the deep muscular plexus (ICC‐DMP) and intramuscular ICC (ICC‐IM). ICC‐DMP could be identified by EM but not by c‐Kit immunohistochemistry. Immuno‐EM revealed that ICC‐DMP were innervated by both cholinergic and nitrergic nerves, and were the only cells to possess specialized synapse‐like junctions with nerve varicosities and gap junction contacts with smooth muscle cells. c‐Kit positive ICC near the deep muscular plexus were not ICC‐DMP, but ICC‐IM located in septa. ICC‐IM were innervated by both cholinergic and nitrergic nerves but without specialized contacts. Varicosities of both nerve types were also found scattered throughout the musculature without specialized contact with any ICC. No ICC showed immunoreactivity for neuronal nitric oxide synthase. As ICC‐DMP form synapse‐like junctions with cholinergic and nitrergic nerves and gap junction contacts with muscle cells, it is hypothfesized that ICC‐DMP hold a specialized function related to innervation of smooth muscle of the human intestine.
Electrogastrography as a diagnostic tool for delayed gastric emptying in functional dyspepsia and irritable bowel syndrome
Authors: Van Der Voort I. R. , Osmanoglou E. , Seybold M. , Heymann‐Mönnikes I. , Tebbe J. , Wiedenmann B. , Klapp B. F. , Mönnikes H. 
Published: September 2003

AbstractSeveral pathophysiological mechanisms have been proposed in functional gastrointestinal (GI) disorders, e.g. altered GI motility and sensitivity. The aim of this study was to investigate gastric electrical activity (GEA) in patients with functional dyspepsia (FD) or irritable bowel syndrome (IBS) compared with healthy controls (HC), and to assess if abdominal symptoms and delayed gastric emptying are associated with alterations in GEA, as determined by electrogastrography (EGG). Forty patients with FD, IBS or both were compared with 22 HC. EGG was performed before and after a standard meal. Frequencies and amplitudes pre‐ and post‐prandially were analysed. Furthermore, gastric emptying and symptom scores were assessed. Eight of 40 patients (20%; three FD, three IBS, two FD and IBS) had delayed gastric emptying. Disturbed gastric emptying and lack of a postprandial increase in the EGG amplitude were significantly correlated (r = 0.8; P < 0.005). No differences between controls and patients were observed in the distribution of EGG frequencies. Treatment with the prokinetically active macrolide erythromycin improved gastric emptying, GEA and symptoms (n = 4). The data suggest that EGG could be useful as a diagnostic tool in patients with FD and IBS to identify a subgroup of patients with delayed gastric emptying.
Cocaine‐ and amphetamine‐regulated transcript: distribution and function in rat gastrointestinal tract
Authors: Ekblad E. , Kuhar M. , Wierup N. , Sundler F. 
Published: September 2003

AbstractCocaine‐ and amphetamine‐regulated transcript (CART) peptide, originally isolated from brain, is also expressed in the peripheral nervous system. The distribution, origin and projections of CART‐expressing enteric neurones by immunocytochemistry and in situ hybridization in rat gastrointestinal (GI) tract were studied. Possible motor functions of CART were studied in vitro using longitudinal muscle strips from stomach, ileum and colon. Cocaine‐ and amphetamine‐regulated transcript peptide was found in numerous myenteric neurones throughout the GI tract while CART‐expressing submucous neurones were scarce. Cocaine‐ and amphetamine‐regulated transcript was also expressed in the antral gastrin cells. Myenteric CART‐expressing neurones in both small and large intestine issued short descending projections. In atrophic ileum, CART mRNA‐expressing neurones increased in number while neurones containing CART peptide decreased. In hypertrophied ileum, no change in CART peptide or CART mRNA containing myenteric neurones was detected. Cocaine‐ and amphetamine‐regulated transcript 55–102 (10−9–10−7 mol L−1) did not induce any contractile or relaxatory responses in the muscle strips, neither did it affect responses induced by vasoactive intestinal peptide, pituitary adenylate cyclase‐activating peptide or neuronal stimulation. In colonic, but not in ileal, strips addition of CART attenuated nitric oxide (NO) donor‐induced relaxations. Although CART does not seem to play a pivotal role in classic neurotransmission to the longitudinal muscle, it may serve a modulatory role in NO transmission. It may, moreover, be involved in intestinal adaptation, and an additional hormonal role is also possible.
Copper accumulation, synthesis of ascorbate and activation of ascorbate peroxidase in Enteromorpha compressa (L.) Grev. (Chlorophyta) from heavy metal‐enriched environments in northern Chile
Authors: RATKEVICIUS N. , CORREA J. A. , MOENNE A. 
Published: September 2003

ABSTRACT Enteromorpha compressa is the dominant species in coastal areas of northern Chile receiving copper mine wastes. Copper remains as the main heavy metal in these coastal waters and it is accumulated in E. compressa growing at the impacted sites. Algae from these sites showed higher levels of lipoperoxides than from non‐impacted sites, which suggests the occurrence of cellular damage resulting from oxidative stress. The strong activation of ascorbate peroxidase detected in this study probably occurs in order to buffer this oxidative stress. Unexpectedly, the activity of glutathione reductase, normally coupled to ascorbate peroxidase activity, was not affected by the chronic exposure to the mine wastes. Moreover, catalase, dehydroascorbate reductase and glutathione peroxidase, commonly reported to buffer oxidative stress in plants and algae, were not detected in E. compressa from any of the studied sites. Levels of total glutathione and phenolic compounds decreased in algae from mine‐impacted sites. In contrast, high levels of dehydroascorbate were found in algae from impacted sites, whereas ascorbate remained unchanged. Therefore, it is suggested that E. compressa tolerates a copper‐enriched environment, and the accompanying oxidative stress, through the accumulation of copper, activation of ascorbate peroxidase, synthesis of ascorbate (accumulated as dehydroascorbate) and consumption of glutathione and water‐soluble phenolic compounds.
The effect of temperature on stigmatic receptivity in sweet cherry (Prunus avium L.)
Authors: HEDHLY A. , HORMAZA J. I. , HERRERO M. 
Published: September 2003

ABSTRACTPlant reproduction is highly vulnerable to environmental conditions such as temperature and, consequently, planet warming may have significant consequences on the reproductive phase with serious implication in agricultural crops. Although pollen tube growth is clearly affected by temperature, little information is available on its effect on the female side and on flower receptivity. In this work, the effect of temperature has been evaluated on stigmatic receptivity of sweet cherry in vivo, in the laboratory, and in planta, in the field. Results herein show that temperature has a clear effect on the duration of stigmatic receptivity. Thus, whereas high temperature reduced stigmatic receptivity, low temperature enlarged it. The stigma lost the capacity to offer support first for pollen penetration, second for pollen germination and, finally, for pollen adhesion. The effect of temperature was more pronounced on pollen germination and penetration than on pollen adhesion. High temperature reduced the germination capacity of the pollen as early as the first day after anthesis, a time when no apparent signs of stigma degeneration are apparent. This clear effect of temperature on stigmatic receptivity and pollen performance may have clear implication in crop performance and in establishing screening criteria of best‐adapted genotypes.
High‐temperature inhibition of photosynthesis is greater under sunflecks than uniform irradiance in a tropical rain forest tree seedling
Authors: LEAKEY A. D. B. , PRESS M. C. , SCHOLES J. D. 
Published: September 2003

ABSTRACTThe survival of dipterocarp seedlings in the understorey of south‐east Asian rain forests is limited by their ability to maintain a positive carbon balance. Photosynthesis during sunflecks is an important component of carbon gain. Field measurements demonstrated that Shorea leprosula seedlings in a rain forest understorey received a high proportion of daily photon flux density at temperatures supra‐optimal for photosynthesis (72% at ≥30 °C, 14% at ≥35 °C). To investigate the effect of high temperatures on photosynthesis during sunflecks, gas exchange and chlorophyll fluorescence measurements were made on seedlings grown in controlled environment conditions either, under uniform, saturating irradiance (approximately 539 µmol m−2 s−1) or, shade/fleck sequences (approximately 30 µmol m−2 s−1/approximately 525 µmol m−2 s−1) at two temperatures, 28 or 38 °C. The rate of light‐saturated photosynthesis, under uniform irradiance, was inhibited by 40% at 38 °C compared with 28 °C. However, during the shade/fleck sequence, photosynthesis was inhibited by 59% at 38 °C compared with 28 °C. The greater inhibition of photosynthesis during the shade/fleck sequence, when compared with uniform irradiance, was driven by the lower efficiency of dynamic photosynthesis combined with lower steady‐state rates of photosynthesis. These results suggest that, contrary to current dogma, sunfleck activity may not always result in significant carbon gain. This has important consequences for seedling regeneration processes in tropical forests as well as for leaves in other canopy positions where sunflecks make an important contribution to total photon flux density.
Higher amounts of anthocyanins and UV‐absorbing compounds effectively lowered CPD photorepair in purple rice (Oryza sativa L.)
Authors: HADA H. , HIDEMA J. , MAEKAWA M. , KUMAGAI T. 
Published: September 2003

ABSTRACTGrowth of a near‐isogenic line (NIL) for the purple leaf gene Pl of rice with a genetic background of Taichung 65 (T‐65) rice was significantly retarded by supplementary ultraviolet‐B radiation (UV‐B), despite the fact that the amounts of UV‐absorbing compounds and anthocyanins in NIL were significantly higher than those in T‐65. In order to understand the role of flavonoids in UV‐B induced damage protection in T‐65 and the NIL, both the (1) relationships between changes in the steady state of cyclobutane pyrimidine dimer (CPD) levels and changes in accumulation of anthocyanins and UV‐absorbing compounds in leaves with leaf age, and (2) the susceptibility to CPD induction by UV‐B radiation and the ability to photorepair CPD were examined. Although supplementary UV‐B elevated the steady state of CPD levels in leaves in both strains, the level in the leaf of the NIL was higher than that in T‐65 at any time. The susceptibility to CPD induction by short‐term (challenge) UV‐B exposure was lower in the NIL than in T‐65. On the other hand, the CPD photorepair was also lower in the leaves of the NIL than in those of T‐65. The decrease in CPD‐photorepair in the NIL was due to a lowering of the leaf‐penetrating blue/UV‐A radiation, which is effective for photoreactivation by photolyase, by anthocyanins. Thus, accumulation of anthocyanins and UV‐absorbing compounds did not effectively function as screening against damage caused by elevated UV‐B radiation in the NIL, and the retardation of growth in the NIL resulted from its lower ability to photorepair CPD by higher amounts of anthocyanins.
Functional characterization and expression analysis of a glutathione transporter, BjGT1, from Brassica juncea: evidence for regulation by heavy metal exposure
Authors: BOGS J. , BOURBOULOUX A. , CAGNAC O. , WACHTER A. , RAUSCH T. , DELROT S. 
Published: September 2003

ABSTRACTGlutathione and its derivatives play an important role in the tolerance of plants against heavy metals. A glutathione transporter, BjGT1 (AJ561120), was cloned and functionally characterized from Brassica juncea, a plant which may be used for phytoremediation. The full‐length BjGT1 cDNA showed homology with the high affinity glutathione transporter HGT1 from Saccharomyces cerevisiae and shares 92% identity with a putative glutathione transporter from A. thaliana (At4g16370). When expressed in the S. cerevisiae hgt1Δ strain, BjGT1 complemented the mutant on medium with glutathione as the only sulphur source and mediated the uptake of [3H]GSH. Immunoblot analysis with a peptide‐specific antiserum directed against a C‐terminal sequence revealed high BjGT1 expression in leaf tissue and relatively low expression in stem tissue, whereas BjGT1 protein was not detectable in root tissue. The amounts of BjGT1 mRNA and protein were analysed during a 6 d exposure of B. juncea to 25 µm Cd(NO3)2. BjGT1 mRNA was strongly induced by cadmium in stems and leaves. Unexpectedly, the amount of BjGT1 protein in leaves showed a pronounced decrease with a minimum after 96 h of Cd exposure, followed by partial recovery. The strong regulation of BjGT1 by cadmium suggests a role of this glutathione transporter during heavy metal exposure.
Aerenchyma formation and radial O2 loss along adventitious roots of wheat with only the apical root portion exposed to O2 deficiency
Authors: MALIK A. I. , COLMER T. D. , LAMBERS H. , SCHORTEMEYER M. 
Published: September 2003

ABSTRACTThis study investigated aerenchyma formation and function in adventitious roots of wheat (Triticum aestivum L.) when only a part of the root system was exposed to O2 deficiency. Two experimental systems were used: (1) plants in soil waterlogged at 200 mm below the surface; or (2) a nutrient solution system with only the apical region of a single root exposed to deoxygenated stagnant agar solution with the remainder of the root system in aerated nutrient solution. Porosity increased two‐ to three‐fold along the entire length of the adventitious roots that grew into the water‐saturated zone 200 mm below the soil surface, and also increased in roots that grew in the aerobic soil above the water‐saturated zone. Likewise, adventitious roots with only the tips growing into deoxygenated stagnant agar solution developed aerenchyma along the entire main axis. Measurements of radial O2 loss (ROL), taken using root‐sleeving O2 electrodes, showed this aerenchyma was functional in conducting O2. The ROL measured near tips of intact roots in deoxygenated stagnant agar solution, while the basal part of the root remained in aerated solution, was sustained when the atmosphere around the shoot was replaced by N2. This illustrates the importance of O2 diffusion into the basal regions of roots within an aerobic zone, and the subsequent longitudinal movement of O2 within the aerenchyma, to supply O2 to the tip growing in an O2 deficient zone.
Intracellular phosphorylation of benzyladenosine is related to apoptosis induction in tobacco BY‐2 cells
Authors: MLEJNEK P. , DOLEŽEL P. , PROCHÁZKA S. 
Published: September 2003

ABSTRACTTreatment of tobacco BY‐2 cells with micromolar concentration of benzyladenosine ([9R]BA) resulted in the loss of cell viability in a time‐ and concentration‐dependent manner. Cell death induced by [9R]BA exhibited typical apoptotic hallmarks including cell shrinkage, chromatin condensation and degradation of nuclear DNA to characteristic high molecular weight (HMW) as well as nucleosomal size fragments. Externally added [9R]BA was very rapidly and almost quantitatively phosphorylated within BY‐2 cells. Accumulation of [9R]BA‐monophosphate was accompanied by massive production of endogenous reactive oxygen species (ROS), intracellular ATP depletion, and these events were followed by the loss of cell viability. Inhibition of intracellular phosphorylation of [9R]BA by adenosin kinase inhibitor, 5′‐amino‐5′‐deoxyadenosine (AdAs), diminished ROS production, ATP depletion, and consequently prevented cells from death. Selective inhibition of ROS production without restoring ATP production, however, did not provide any protection to cells. In contrast, even enhanced phosphorylation of [9R]BA caused by adenosine that simultaneously revived ATP synthesis reduced the number of dying cells. This is the first evidence of a direct relationship between intracellular phosphorylation of [9R]BA and apoptosis induction in BY‐2 cells. ATP depletion but not ROS production is the key secondary event that determines the cellular decision between life and death.
Cellular responses of developing Fucus serratus embryos exposed to elevated concentrations of Cu2+
Authors: NIELSEN H. D. , BROWN M. T. , BROWNLEE C. 
Published: September 2003

ABSTRACTElevated concentrations of Cu2+ can have inhibitory effects on early development in plants and algae by targeting specific cellular processes. In the present study the effects of elevated Cu2+ on developmental processes in embryos of the brown algae Fucus serratus (Phaeophyceae) were investigated. Elevated Cu2+ was shown to inhibit fixation of the zygotic polar axis but not its formation. Actin localization was unaffected by elevated Cu2+ but polarized secretion, which occurs downstream, was inhibited. Significant differences in tolerance to Cu2+ were observed for polarization and rhizoid elongation of embryos derived from adults from Cu2+‐contaminated and uncontaminated locations. Moderate Cu2+ exposure inhibited the generation of cytosolic Ca2+ signals in response to hypo‐osmotic shocks. In contrast, cytosolic Ca2+ was elevated by treatments with high [Cu2+] and this coincided with production of reactive oxygen species. The results indicate that direct effects on signalling processes involved in polarization and growth may in part explain complex, concentration‐dependent effects of Cu2+ on early development.
Axial‐to‐radial water permeability of leaf major veins: a possible determinant of the impact of vein embolism on leaf hydraulics?
Authors: SALLEO S. , RAIMONDO F. , TRIFILÒ P. , NARDINI A. 
Published: September 2003

ABSTRACTThe leaf hydraulic conductance (KL) was measured in Prunus laurocerasus L. and Juglans regia L. in which previous measurements had revealed different impacts of dehydration on KL. Leaves of P. laurocerasus lost 8% of their KL at water potentials (ΨL) of −2.0 MPa. Leaflets of J. regia showed KL losses of 40% at ΨL = −1.0 MPa. When major veins were blocked using cyanoacrylate to simulate their embolism, the KL of P. laurocerasus was reduced by 57% but that of J. regia leaflets was reduced by 80%. Such differences were hypothesized to be due to different axial‐to‐radial permeabilites of major veins. Infiltration of leaves with Phoxine B revealed that P. laurocerasus major veins were largely leaky in the radial direction whereas those of J. regia leaflets showed prevailing axial water transport. Differences between species in terms of axial‐to‐radial water permeability were confirmed by measurements of changes of hydraulic resistance along the midrib. The two hydraulic models are discussed in terms of leaf vulnerability to embolism and plant adaptation to dry habitats.
Do the capacity and kinetics for modification of xanthophyll cycle pool size depend on growth irradiance in temperate trees?
Authors: NIINEMETS Ü. , KOLLIST H. , GARCÍA‐PLAZAOLA J. I. , HERNÁNDEZ A. , BECERRIL J. M. 
Published: September 2003

ABSTRACTThe present study investigated the interaction of growth irradiance (Qint) with leaf capacity for and kinetics of adjustment of the pool size of xanthophyll cycle carotenoids (sum of violaxanthin, antheraxanthin and zeaxanthin; VAZ) and photosynthetic electron transport rate (Jmax) after changes in leaf light environment. Individual leaves of lower‐canopy/lower photosynthetic capacity species Tilia cordata Mill. and upper canopy/higher photosynthetic capacity species Populus tremula L. were either illuminated by additional light of 500–800 µmol m−2 s−1 for 12 h photoperiod or enclosed in shade bags. The extra irradiance increased the total amount of light intercepted by two‐fold for the upper and 10–15‐fold for the lower canopy leaves, whereas the shade bags transmitted 45% of incident irradiance. In control leaves, VAZ/area, VAZ/Chl and Jmax were positively associated with leaf growth irradiance (Qint). After 11 d extra illumination, VAZ/Chl increased in all cases due to a strong reduction in foliar chlorophyll, but VAZ/area increased in the upper canopy leaves of both species, and remained constant or decreased in the lower canopy leaves of T. cordata. The slope for VAZ/area changes with cumulative extra irradiance was positively associated with Qint only in T. cordata, but not in P. tremula. Nevertheless, all leaves of P. tremula increased VAZ/area more than the most responsive leaves of T. cordata. Shading reduced VAZ content only in P. tremula, but not in T. cordata, again demonstrating that P. tremula is a more responsive species. Compatible with the hypothesis of the role of VAZ in photoprotection, the rates of photosynthetic electron transport declined less in P. tremula than in T. cordata after the extra irradiance treatment. However, foliar chlorophyll contents of the exposed leaves declined significantly more in the upper canopy of P. tremula, which is not consistent with the suggestion that the leaves with the highest VAZ content are more resistant to photoinhibition. This study demonstrates that previous leaf light environment may significantly affect the adaptation capacity of foliage to altered light environment, and also that species differences in photosynthetic capacity and acclimation potentials importantly alter this interaction.
Anomalous unradiogenic 87Sr//86Sr ratios in ultrahigh‐pressure crustal carbonates – evidence for fluid infiltration during deep subduction?
Authors: Romer R. L. , Wawrzenitz N. , Oberhänsli R. 
Published: September 2003

AbstractMarbles from Changpu (Dabie Shan, eastern China), subducted to 4.4 GPa, have 87Sr/86Sr values < 0.7040. These low 87Sr/86Sr values, which would imply a sedimentation age > 2 Ga if considered as primary signature, reflect fluid–rock interaction with a fluid from a low‐87Sr/86Sr source. The introduction of low‐87Sr/86Sr was paralleled by introduction of Mg and loss of Si, K and Na in such a way that carbonates from the purest marbles have the least evolved Sr isotopic composition. Introduction of Mg is also indicated by the distribution of calcite and dolomite. Calcite forms inclusions in garnet, whereas dolomite is restricted to the matrix. These chemical changes, inferred from the mineralogy, in combination with textural evidence require a mobile metamorphic fluid. P–T–X constraints for fluid generation and for permeability increase related to mineral reactions and phase transitions suggest that the marbles acquired their anomalous Sr‐isotopic composition during subduction below 60 km. The marbles with the least radiogenic Sr isotopic composition demonstrate that crustal rocks may lose their isotopic fingerprint during deep subduction.