bluuebunny/crossref_metadata_2025 huggingface dataset:
Leukaemia inhibitory factor (LIF) is functionally linked to axotrophin and both LIF and axotrophin are linked to regulatory immune tolerance
Authors: Metcalfe Su M. , Muthukumarana Poorni A. De S. , Thompson H. Lorraine , Haendel Melissa A. , Lyons Gary E.
Published: December 2004

Axotrophin (axot) is a newly characterised stem cell gene and mice that lack axotrophin are viable and fertile, but show premature neural degeneration and defective development of the corpus callosum. By comparing axot
+/+, axot
+/− and axot
−/− littermates, we now show that axotrophin is also involved in immune regulation. Both T cell proliferation and T cell‐derived leukaemia inhibitory factor (LIF) were suppressed by axotrophin in a gene‐dose‐dependent manner. Moreover, a role for axotrophin in the feedback regulation of LIF is implicated. This is the first evidence that fate determination mediated by LIF maybe qualified by axotrophin.
Differentiative pathway activated by 3‐aminobenzamide, an inhibitor of PARP, in human osteosarcoma MG‐63 cells
Authors: De Blasio A. , Messina C. , Santulli A. , Mangano V. , Di Leonardo E. , D’Anneo A. , Tesoriere G. , Vento R.
Published: December 2004

This study describes the molecular mechanism by which treatment with 3‐AB, a potent inhibitor of PARP, allows human osteosarcoma MG‐63 cells to restrict growth and enter differentiation. Our findings show that in MG‐63 cells, aberrant gene expression keeps Rb protein constitutively inactivated through hyperphosphorylation and this promotes uncontrolled proliferation of the cells. After 3‐AB‐treatment, the poly(ADP‐ribosyl)ation of nuclear proteins markedly decreases and this results in an increase in both the hypophosphorylated active form of Rb and pRb/E2F complexes. These effects are accompanied by G1 arrest, downregulation of gene products required for proliferation (cyclin D1, β‐catenin, c‐Jun, c‐Myc and Id2) and upregulation of those implicated in the osteoblastic differentiation (p21/Waf1, osteopontin, osteocalcin, type I collagen, N‐cadherins and alkaline phosphatase). Our study suggests that use of PARP inhibitors may induce a remodeling of chromatin with the reprogramming of gene expression and the activation of differentiation.
Activation of the transcription factor NFAT1: concerted or modular regulation?
Authors: Salazar Carlos , Höfer Thomas
Published: December 2004

The transcription factor NFAT1 is activated through dephosphorylation of multiple serine residues, contained within the SRR1 and SP motifs. The phosphorylation status of these motifs regulates the subcellular localisation of NFAT1 via a conformational switch. Here, we discuss two molecular mechanisms for NFAT1 activation that resemble network‐oriented approaches. In the modular mechanism, import and export are regulated separately by the SRR1 and SP motifs, respectively, whereas in the concerted model all residues jointly control both processes. Using simulations of a computational model, we show that both mechanisms may be compatible with recent experimental data on the import and export kinetics of NFAT1.
Serum concentration of macrophage‐derived chemokine may be a useful inflammatory marker for assessing severity of atopic dermatitis in infants and young children
Authors: Leung Ting Fan , Ma Kwok Chiu , Hon Kam Lun , Lam Christopher W. K. , Wan Helene , Li Chung Yi , Chan Iris H. S.
Published: December 2004

Chemokines are responsible for the trafficking of leukocytes to sites of inflammation. Serum chemokine levels were previously shown to be increased in adult patients with atopic dermatitis (AD). We tested whether serum concentrations of chemokines, including macrophage‐derived chemokine (MDC), thymus and activation‐regulated chemokine (TARC), eotaxin (EOX), interferon gamma inducible protein 10 (IP‐10) and monocyte chemotactic protein 1 (MCP‐1), are useful inflammatory markers for assessing AD severity in infants and young children. To investigate this, we assessed the severity of AD clinically using the SCORing Atopic Dermatitis (SCORAD) index system. Serum chemokine concentrations were determined by sandwich enzyme immunoassay. Twenty AD patients with a median age of 2.1 years [interquartile range (IQR): 0.6–4.2] were recruited. Their SCORAD score was 23.5 (12.5–33.5). Serum concentrations of MDC, TARC, EOX, IP‐10 and MCP‐1 were 2551 (1978–3935), 1469 (1125–3070), 68 (57–85), 126 (101−226) and 518 (419–614) pg/ml, respectively. Serum MDC levels correlated with SCORAD (r = 0.608, p = 0.004) and its extent (r = 0.629, p = 0.003) and intensity (r = 0.557, p = 0.011) components. Serum TARC concentration showed weaker correlation with extent (r = 0.474, p = 0.035) and intensity (r = 0.465, p = 0.039) of skin involvement but not SCORAD. The median serum levels of MDC (3131 vs. 2394 pg/ml; p = 0.031) and EOX (80 vs. 61 pg/ml; p = 0.046) were also higher in children with moderate as compared with mild AD. The other chemokines did not correlate with AD severity. In conclusion, our results suggest that serum MDC concentration may be a useful inflammatory marker for assessing AD severity in infants and young children.
Varicella‐zoster infection in pediatric solid‐organ transplant recipients:A hospital‐based study in the prevaricella vaccine era
Authors: Pandya Anand , Wasfy Samia , Hebert Diane , Allen Upton D.
Published: December 2004

Abstract: We reviewed 58 cases of varicella‐zoster infection that occurred between 1988 and 1998 in 47 pediatric solid‐organ transplant recipients. The median age of patients at the time of admission with varicella‐zoster infection was 8.0 yr (range 1–17 yr). The median interval between transplantation (Tx) and varicella‐zoster virus (VZV) infection was 1.6 yr (range 0.06–9.3 yr). Varicella infection occurred at a rate of one case for every seven transplant recipients. Among the 58 cases of VZV infection, 53% were varicella while 47% were herpes‐zoster. Varicella infection occurred despite treatment with varicella‐zoster immune globulin (VZIG) in 17 of 31 cases of varicella infection. However, the disease was generally mild with severe disease occurring in only two patients. One patient (1.7%) died as a result of bacterial sepsis. There was no significant relationship between VZV infection and specific immune suppressants. Episodes of rejection were more likely to be temporally associated with the occurence of herpes zoster than with varicella infection (p = 0.02). The data generated provide useful background information in our population in the prevaricella vaccine era.
Development of liver size and perfusion after reduced‐size liver transplantation in children
Authors: Hoyer Peter F. , Rodeck Burkhard , Scherbring Markus , Melter Michael , Oldhafer Karl , Ringe Burkhardt , Pichlmayr Rudolf
Published: December 2004

Abstract: The technique of segmental liver transplantation (s‐LTx) provides a method to overcome the shortage of suitable livers for small recipients. Patient survival rates are parallel to those obtained with whole liver transplantation (w‐LTx). For long‐term rehabilitation, adaptive liver growth and adequate perfusion is crucial; however, morphometric and hemodynamic parameters in growing children with s‐LTx are not available. Seventeen children who received a s‐LTx and 25 with a w‐LTx who had follow‐up evaluation 1 and 2 yr after LTx were studied. Mean age at time of transplantation was 4.3 ± 3.5 yr for s‐LTx and 10.3 ± 6.0 yr for w‐LTx, mean height 98 ± 21 cm and 122 ± 30 cm respectively. At follow‐up evaluation mean values for liver enzymes, bilirubin and prothrombin time were in the normal ranges for both groups. Liver dimensions were measured by gray scale ultrasound, and hemodynamic parameters by Doppler sonography in the portal vein and hepatic artery using an Acuson 128 machine. Maximal (Vmax), minimal (Vmin) and time‐average velocity (TAV) were measured and the resistive index (RI) calculated. We found that 1 and 2 yr after LTx liver dimensions were at a mean in the upper normal range of healthy controls. Spleen size was above the normal range and did not show any tendency towards regression. Mean Vmax in the hepatic artery in s‐LTx and w‐LTx was 48 cm/sec vs. 28 cm/sec after 1 yr and 30 cm/sec vs. 35 cm/sec after 2 yr, the RI 0.66 vs. 0.55 and 0.59 vs. 0.73, respectively (p for all parameters > 0.05). Maximal portal vein flow was 25 cm/sec in s‐LTx vs. 29 cm/sec in w‐LTx. Blood flow calculated by vessel diameter and TAV showed no statistical difference between both groups. In conclusion, liver size after s‐LTx and w‐LTx was increased to the upper normal range, and portal vein blood flow velocities were within the normal range. Vmax in the hepatic artery was reduced in s‐LTx; however, the reduction was to the same extent as in w‐LTx. In the view of long‐term functional adaptation, s‐LTx is not inferior to w‐LTx.
Characterization of an ascorbate peroxidase in plastids of tobacco BY‐2 cells
Authors: Madhusudhan Rapolu , Ishikawa Takahiro , Sawa Yoshihiro , Shigeoka Shigeru , Shibata Hitoshi
Published: December 2004

In higher plants, ascorbate peroxidase (APX; EC 1.11.1.11), the major H2O2‐scavenging enzyme, occurs in several distinct isoenzymes that are localized in cytosol and various cell organelles. Here, we have purified and characterized an APX from the soluble fraction of plastids of non‐photosynthetic tobacco BY‐2 cells. The plastidic APX was a monomer with a molecular weight of 34 000. The enzymatic properties of the plastidic APX, including the rapid inactivation by H2O2 in ascorbate‐depleted medium, were highly comparable with those of the chloroplastic stromal APX of spinach and tea leaves. However, the other chloroplastic APX isoenzyme, the thylakoid‐membrane bound APX, was not detected in the plastids of the BY‐2 cells. The N‐terminal amino acid sequence of the plastidic APX was completely identical with the deduced amino acid sequence of a previously identified cDNA sequence of tobacco chloroplastic APX. When a green fluorescence protein gene tagged with the chloroplast‐targeting signal sequence of APX was expressed in the BY‐2 cells, the fluorescence protein exclusively localized into plastids, and not into mitochondria. We conclude that plastidic APX in non‐photosynthetic tissues is the same as the chloroplastic APX that occurs in leaves.
Molecular characterization of glutathione peroxidase‐like protein in halotolerant Chlamydomonas sp. W80
Authors: Takeda Toru , Miyao Kazuhiro , Tamoi Masahiro , Kanaboshi Haruo , Miyasaka Hitoshi , Shigeoka Shigeru
Published: December 2004

A cDNA clone encoding a glutathione peroxidase (GPX)‐like protein was isolated from the cDNA library from halotolerant Chlamydomonas W80 (C. W80) by a simple screening method based on the bacterial expression system. The cDNA clone contained an open reading frame encoding a mature protein of 163 amino acids with a calculated molecular mass of 18 267 Da. No potential signal peptide was found. The deduced amino acid sequence of the cDNA showed 40–63% and 37–46% homology to those of GPX‐like proteins from higher plants and mammalian GPXs, respectively. The C. W80 GPX‐like protein contained a normal cysteine residue instead of a selenocysteine at the catalytic site. However, it contained amino acid residues (glutamine and tryptophan) that are involved in three protein loops and are important for the catalytic activity in the mammalian GPX. Interestingly, the native and recombinant GPX‐like proteins showed activities towards unsaturated fatty acid hydroperoxides, but not towards either H2O2 or phospholipid hydroperoxide. Transformed E. coli cells expressing the C. W80 GPX‐like protein showed enhanced tolerance to 5% NaCl or 0.2 mM paraquat treatments.

Accession number: The nucleotide sequence data reported have been submitted to the DDBJ, EMBL, and GenBank nucleotide sequence databases with the following accession number AB009083.
Resource allocation in different parts of juvenile mountain birch plants: effect of nitrogen supply on seedling phenolics and growth
Authors: Keski‐Saari Sarita , Julkunen‐Tiitto Riitta
Published: December 2004

The composition and concentrations of phenolic compounds were studied in the first true leaves, cotyledons, stems and roots of 2.5‐week‐old seedlings of mountain birch (Betula pubescens ssp. czerepanovii). The differences in secondary compounds among these plant parts were both qualitative and quantitative. In all parts, condensed tannins accounted for more than 50% of the phenolics. In the first true leaves and cotyledons, chlorogenic acid was the most abundant of the HPLC phenolics. The main components in stems were (+)‐catechins and rhododendrins whereas in roots, the main components were ellagitannins. The seedlings were grown at three levels of nitrogen supply (very low‐N, low‐N, moderate‐N), and the effect of nitrogen on concentrations of phenolic compounds was studied in all plant parts. The dry weight of all plant parts, except the roots, increased with increased nitrogen. In all parts, the concentration of condensed tannins was higher at lower levels of nitrogen than at moderate‐N. The concentrations of total HPLC phenolics and also those of the compound groups of HPLC phenolics were, however, affected only in the first true leaves and roots. The concentrations in the first true leaves were generally higher in seedlings grown at very low‐N and low‐N than in seedlings grown at moderate‐N. The concentrations in roots were highest at low‐N. Not all compounds responded to nitrogen supply in the same manner. The changes in concentrations cannot be exclusively interpreted as changes in the accumulation of phenolic compounds, due to dilution caused by the increase in biomass in better nitrogen availability. There were differences in carbon allocation between condensed tannins and HPLC phenolics in seedlings grown at different nitrogen levels.
Atrazine resistance entails a limited xanthophyll cycle activity, a lower PSII efficiency and an altered pattern of excess excitation dissipation
Authors: Váradi Gyula , Polyánka Hilda , Darkó Éva , Lehoczki Endre
Published: December 2004

Atrazine‐resistant (AR) weeds have a modified D1 protein structure, with a Ser264→Gly mutation on the D1 protein, near the plastoquinone binding niche. The photosynthetic performance, the light response of the xanthophyll cycle and chlorophyll fluorescence quenching‐related parameters were compared in attached leaves of susceptible (S) and AR biotypes of the C3 dicot Chenopodium album L., Epilobium adenocaulon Hausskn., Erigeron canadensis L., Senecio vulgaris L. and Solanum nigrum L. and the C4 dicot Amaranthus retroflexus L. grown under natural high‐light conditions. No significant difference in CO2 assimilation rate per leaf area unit was found between the S and AR biotypes of the investigated C3 plants, whereas the AR biotype of A. retroflexus exhibited a relatively poor photosynthetic performance. The D1 protein mutant plants expressed a reduced activity of light‐stimulated zeaxanthin formation. Neither the lower violaxanthin de‐epoxidase activity nor the depletion of ascorbate seems to be the cause of the lower in vivo zeaxanthin formation in the AR plants. All the D1 mutant weeds had limited light‐induced non‐photochemical (NPQ) and photochemical (qP) quenching capacities, and displayed a higher photosensitivity, as characterized by the ratio (1‐qP)/NPQ and a higher susceptibility to photoinhibition. Analysis of the chlorophyll fluorescence parameters showed that a lower proportion of excitation energy was allocated to PSII photochemistry, while a higher excess of excitation remained in the AR weeds relative to the S plants.
Habitat related variation in UV tolerance of tropical marine red macrophytes is not temperature dependent
Authors: Van De Poll Willem H. , Bischof Kai , Buma Anita G J. , Breeman Anneke M.
Published: December 2004

Because tropical marine macrophytes experience high ultraviolet‐B radiation (UVBR: 280–320 nm) it is assumed that they have high UV tolerance. This was investigated by examining the relative UV sensitivity of five Caribbean red macrophytes. Furthermore, the possibility of temperature dependence of UV effects was examined over a tropical temperature range. Algal fragments of intertidally occurring Gelidiopsis planicaulis (Taylor) Taylor, Wurdemannia miniata (Duby) Feldman and Hamel, and Hypnea spinella (Agardh) Kützing, and the subtidal species Bryothamnion triquetrum (Gmelin) Howe and Heterosiphonia gibbesii (Harvey) Falkenberg were repeatedly subjected to artificial UVBR and ultraviolet‐A radiation (UVAR: 320–400 nm) at 22, 26 and 30°C, whereas exposure to photosynthetically active radiation (PAR) served as control. Growth rates, optimal quantum yield of PSII and accumulation of DNA damage were monitored for 10 days, whereas the relative abundance of the D1 reaction centre binding protein and the presence of UV absorbing compounds were investigated in some samples. UVAR and UVBR significantly depressed growth rates of all species. UVBR exposure caused accumulation of DNA damage and resulted in stronger growth reduction than UVAR. UVBR and UVAR caused a depression of optimal quantum yield and a lower D1 abundance. However, the former recovered fast and acclimated to the UV treatments. Some species produced UV absorbing compounds in response to UVAR. UV exposure caused less pronounced effects in intertidally occurring species than in subtidal species. UV effects on growth, the accumulation of DNA damage and UV induced depression of optimal quantum yield were independent of temperature in most species. We conclude that high UVBR in tropical regions may depress in situ growth rates of these intertidal and subtidal red macrophytes.
The relationship between changes in the cell wall, lipid peroxidation, proliferation, senescence and cell death
Authors: Spiteller Gerhard
Published: December 2004

Plants and mammals contain polyunsaturated fatty acids (PUFAs) in their membranes. PUFAs belong to the most oxygen sensitive molecules encountered in nature. It would seem that nature has selected this property of PUFAs for signalling purposes: PUFAs are stored in the surface of cells and organelles not in free form but conjugated to phospho‐ and galactolipids. Any change in membrane structure apparently activates membrane‐bound phospholipases, which cleave the conjugates. The obtained free PUFAs are substrates for lipoxygenases (LOX). These transform PUFAs to lipidhydroperoxides (LOOHs). LOOHs are converted to a great variety of secondary products. These lipid‐peroxidation (LPO) products and the resulting generated products thereof represent biological signals, which do not require a preceding activation of genes. They are produced as a non‐specific response to a large variety of external or internal impacts, which therefore do not need interaction with specific receptors. When, due to an external impact, e.g. attack of a microorganism, or to a change in temperature, the amount of liberated free PUFAs exceeds a certain threshold, LOX commit suicide. Thus iron ions, located in the active centre of LOX, are liberated. Iron ions react with LOOHs in the close surroundings by generating alkoxy radicals (LO.). These induce a non‐enzymatic LPO. A fraction of the LO. radicals generated from linoleic acid (LPO products derived from linoleic acid play a dominant role in signalling which was previously overlooked) is converted to 2,4‐dienals which induce the programmed cell death (PCD) and the hypersensitive reaction (HR). While peroxyl radicals (LOO.) generated as intermediates in the course of an enzymatic LPO are transformed within the enzyme complex to corresponding anions (LOO–), and thus lose their reactivity, peroxyl radicals generated in non‐enzymatic reactions are not deactivated. They not only react by abstraction of hydrogen atoms from activated X‐H bonds of molecules in their close vicinity, but also by epoxidation of double bonds and oxidation of a variety of biological molecules, causing a dramatic change in molecular structure which finally leads to cell death. As long as reducing agents, like glutathione, or compounds with free phenolic groups are available, the amount of LOOHs is kept low. Cell death is induced in a defined way by apoptosis. But when the reducing agents have been consumed, PCD seems to switch to necrotic processes. Thus proliferation is induced by minor changes at the cell membrane, while slow changes at cell membranes are linked with apoptosis (e.g. response to attack of microorganisms or drought) and necrosis (severe wounding), depending only on the amount, but not on the type, of applied stimulus.
Development of a strategy for transgenic studies and monitoring of transgene expression in two closely related Moricandia species possessing a C3 or C3–C4 intermediate photosynthetic phenotype
Authors: Thole Vera , Rawsthorne Stephen
Published: December 2004

In order to establish a model system for comparative studies of C3 and C3–C4 intermediate photosynthesis, the development of efficient transformation systems and the monitoring of transgene behaviour and stability were carried out in two closely related Moricandia species (Brassicaceae): the C3–C4 photosynthetic intermediate species M. arvensis and the C3 species M. moricandioides. In this study the green fluorescent protein (gfp) reporter gene was used as a vital marker gene while the use of the β‐glucuronidase (gusA) gene was based on the highly sensitive detection of its activity. For Agrobacterium‐mediated transformation of leaf explants, a cauliflower mosaic virus 35S promoter‐driven, modified version of gfp, the mgfp5‐ER gene and the gusA gene, respectively, were introduced into the new dual binary transformation vector system pGreen/pSoup (Hellens et al. 2000, Plant Mol Bio 42: 819–832). GFP5 produced bright‐green fluorescence in transformed tissues that was distinctly detected 5–12 days following transformation in developing calli of the two species. Visual screening, combined with antibiotic selection, enabled early and easy identification of transformation events and contributed to improvements in the transformation strategies. Transgene integration studies demonstrated that mgfp5‐ER was inserted with low copy number in the M. arvensis plant lines and the transgene was transmitted in a Mendelian fashion to T1 and T2 progenies. GFP5 expression levels in a population of 100 independent primary transformed M. arvensis plant lines (T0) showed great variation between transformation events (coefficient of variation of 108%). The mgfp5‐ER or gusA reporter genes were expressed in 90–95% of the kanamycin‐resistant M. arvensis plant lines and in up to 98% of the independent M. moricandioides plant lines.
Factors that affect leaf extracellular ascorbic acid content and redox status
Authors: Burkey Kent O. , Eason Gwendolyn , Fiscus Edwin L.
Published: December 2004

Leaf ascorbic acid content and redox status were compared in ozone‐tolerant (Provider) and ozone‐sensitive (S156) genotypes of snap bean (Phaseolus vulgaris L.). Plants were grown in pots for 24 days under charcoal‐filtered air (CF) conditions in open‐top field chambers and then maintained as CF controls (29 nmol mol−1 ozone) or exposed to elevated ozone (71 nmol mol−1 ozone). Following a 10‐day treatment, mature leaves of the same age were harvested early in the morning (06:00–08:00 h) or in the afternoon (13:00–15:00 h) for analysis of ascorbic acid (AA) and dehydroascorbic acid (DHA). Vacuum infiltration methods were used to separate leaf AA into apoplast and symplast fractions. The total ascorbate content [AA + DHA] of leaf tissue averaged 28% higher in Provider relative to S156, and Provider exhibited a greater capacity to maintain [AA + DHA] content under ozone stress. Apoplast [AA + DHA] content was 2‐fold higher in tolerant Provider (360 nmol g−1 FW maximum) relative to sensitive S156 (160 nmol g−1 FW maximum) regardless of sampling period or treatment, supporting the hypothesis that extracellular AA is a factor in ozone tolerance. Apoplast [AA + DHA] levels were significantly higher in the afternoon than early morning for both genotypes, evidence for short‐term regulation of extracellular ascorbate content. Total leaf ascorbate was primarily reduced with AA/[AA + DHA] ratios of 0.81–0.90. In contrast, apoplast AA/[AA + DHA] ratios were 0.01–0.60 and depended on genotype and ozone treatment. Provider exhibited a greater capacity to maintain extracellular AA/[AA + DHA] ratios under ozone stress, suggesting that ozone tolerance is associated with apoplast ascorbate redox status.
Unbeatable strategy, constraint and coevolution, or how to resolve evolutionary conflicts: the case of the fig/wasp mutualism
Authors: Anstett Marie Charlotte
Published: December 2004

Constraints and evolution are central for the resolution of conflicts between mutualistic species and for the stability of mutualisms. However, proximal causes of the benevolence of mutualistic species are often unknown. Monoecious fig species and their specific pollinators are in conflict on the use of fig ovaries, which can either produce one seed or host one pollinator larva. Here, I provide new data showing that, probably because of space constraints during the development of both seeds and wasps, ovaries vary in their quality as a substrate for pollinator development depending on their location within the fig inflorescence. This constraint may be responsible for the stability of the fig/wasp mutualism. Moreover, population density of pollinators and density dependent selection on the pollinators could be sufficient to explain the observed highly variable seed/wasp ratios produced by figs.
Effects of intraspecific and interspecific density on the demography of a perennial herb, Sanicula europaea
Authors: Gustafsson Christel , Ehrlén Johan
Published: December 2004

We examined the effects of intraspecific and interspecific competition on demographic processes in the perennial herb Sanicula europaea by manipulating the density of neighbouring plants. We followed the response in terms of survival, growth and reproduction and in terms of seedling recruitment. The demographic data from all phases of the life cycle enabled us to assess also the overall effects of treatments on population growth rate (λ) by transition matrix models. We also decomposed the differences in λ between control and treatments, using life table response experiments (LTRE). To study the effects of competition on recruitment in more detail and to evaluate the role of seed availability, we sowed seeds at different densities with or without vegetation removal.

Vegetative growth and flowering frequency of established individuals was not significantly affected by removal treatments, which suggest no, or a delayed response to released competition. Neighbour removal had no effect on seedling emergence but enhanced recruitment through a higher seedling survival. Conspecific and simultaneous conspecific and heterospecific removal of plants led to an increase in population growth rate (λ), whereas heterospecific removal alone led to a decrease. Emergence of seedlings and fate of vegetative established individuals contributed most to differences in λ between the control and the different treatments. Seed addition enhanced seedling emergence but, as seedling and juvenile survival were density dependent, densities of established individuals appear not to be seed limited.

In S. europaea removal treatments had different effects on established individuals and recruitment. This suggests that studies quantifying the effects of competition over the entire life cycle and performed in a natural environment are necessary to assess the importance of competition in perennial plant populations.
Relatedness and competitive asymmetry – implications for growth and population dynamics
Authors: Aikio Sami , Pakkasmaa Susanna
Published: December 2004

The members of natural populations often differ in size and relatedness to each other, which may affect the division of limited resources and have consequences on reproductive success and population dynamics. We modeled seasonal growth and dynamics in populations composed of different types of relatives (full‐sibs, half‐sibs and non‐related individuals) under the continuum of competitive scenarios between complete symmetry and asymmetry. Growth was assumed logistic in proportion to individual biomass and the size‐differences were weighted by the relatedness of individuals. The symmetric component of competition was experienced by all individuals in proportion to their biomass, whereas the asymmetric component was individual‐specific, and influenced only by the individuals larger than the focal individual. Relatedness decreased and competitive asymmetry increased the variability of individual biomasses. Mortality of the smallest individuals and the size threshold of reproduction decreased population density. Population dynamics were stable when there was no size threshold for reproduction but the presence of the threshold led to cyclic dynamics under low competitive asymmetry. The effects of the threshold were greater among related than unrelated individuals. The results suggest that individual differences and the asymmetry of competition can greatly affect population dynamics. Full symmetry of competition may be evolutionarily unstable in populations of related individuals as it may increase the probability of extinction due to demographic stochasticity.
Comparing species richness among assemblages using sample units: why not use extrapolation methods to standardize different sample sizes?
Authors: Melo Adriano S. , Pereira Rodrigo A. S. , Santos Adalberto J. , Shepherd George J. , Machado Glauco , Medeiros Hermes F. , Sawaya Ricardo J.
Published: December 2004

Comparisons of species richness among assemblages using different sample sizes may produce erroneous conclusions due to the strong positive relationship between richness and sample size. A current way of handling the problem is to standardize sample sizes to the size of the smallest sample in the study. A major criticism about this approach is the loss of information contained in the larger samples. A potential way of solving the problem is to apply extrapolation techniques to smaller samples, and produce an estimated species richness expected to occur if sample size were increased to the same size of the largest sample. We evaluated the reliability of 11 potential extrapolation methods over a range of different data sets and magnitudes of extrapolation. The basic approach adopted in the evaluation process was a comparison between the observed richness in a sample and the estimated richness produced by estimators using a sub‐sample of the same sample. The Log‐Series estimator was the most robust for the range of data sets and sub‐sample sizes used, followed closely by Negative Binomial, SO‐J1, Logarithmic, Stout and Vandermeer, and Weibull estimators. When applied to a set of independently replicated samples from a species‐rich assemblage, 95% confidence intervals of estimates produced by the six best evaluated methods were comparable to those of observed richness in the samples. Performance of estimators tended to be better for species‐rich data sets rather than for those which contained few species. Good estimates were found when extrapolating up to 1.8‐2.0 times the size of the sample. We suggest that the use of the best evaluated methods within the range of indicated conditions provides a safe solution to the problem of losing information when standardizing different sample sizes to the size of the smallest sample.
Conflicts between plants and pollinators that reproduce within inflorescences: evolutionary variations on a theme
Authors: Dufaÿ Mathilde , Anstett Marie‐Charlotte
Published: December 2004

The high diversity of mutualisms has probably limited the development of a general theory about their evolution and their stability. Here we review conflicts of interests occurring in the 13 known nursery pollination systems, where pollinators reproduce within the inflorescence they pollinate. We found three main conflicts of interest between mutualists that correspond to the following evolutionary questions: 1) Why do plants not kill their pollinators’ larvae? 2) Why do pollinators visit deceptive flowers? and 3) Why do pollinators pollinate? We show that the reproductive system of the plant is strongly correlated not only with the set of conflicts of interests that actually occur but also with the proximal resolution of these conflicts. In many cases the evolutionary stability of nursery pollination mutualisms relies on the avoidance of intra‐specific competition among pollinator larvae. This stabilizing factor could perhaps also explain the absence of overexploitation in other mutualisms.
Predicting root biomass from branching patterns of Douglas‐fir root systems
Authors: Richardson Andrew D. , Zu Dohna Heinrich
Published: December 2004

There are many examples of branching networks in nature, such as tree crowns, river systems, arteries and lungs. These networks have often been described as being self‐similar, or following scale‐invariant branching rules, and this property has been used to derive several scaling laws. In this paper we model root systems of Douglas‐fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) as branching networks following several simple branching rules. Our objective is to establish a relationship between trunk diameter and root biomass. We explore the effect of the self‐similar branching assumption on this relationship. Using data collected from a mature stand in British Columbia, we find that branching asymmetry and the rate of root taper change with root size, thereby violating the assumption of self‐similarity. However, the data are in general agreement with Leonardo da Vinci's area‐preserving branching hypothesis. We use the field data to parameterize two models, one assuming self‐similar branching and a second incorporating the measured size dependencies of branching parameters. The two models differ by only a small amount (≈8%) in their predictions. For both models, the predicted relationship between trunk diameter and root biomass is in good concordance with previously published empirical data. We conclude that the assumption of self‐similar branching, although violated by the data, nevertheless provides a useful tool for predicting the allometric relationship between trunk diameter and root biomass. Finally, we use our models to show that the geometric properties of individual bifurcations fundamentally change the root biomass cost of different root topologies.
Spatial synchrony of the two‐year cycle budworm outbreaks in central British Columbia, Canada
Authors: Zhang Qi‐Bin , Alfaro René I.
Published: December 2004

Outbreaks of forest defoliating insects are usually synchronized over a large spatial scale. Observed records of past outbreaks are usually short and incomplete, therefore long proxy data are useful for better understanding of the spatial synchrony. In this study, we developed tree‐ring proxy records of two‐year cycle spruce budworm (Choristoneura biennis Freeman) outbreaks in central British Columbia, Canada, and examined the spatial patterns of past outbreaks. This budworm is a major defoliating insect of the interior spruce (Picea engelmannii Parry×P. glauca Moench) and subalpine fir (Abies lasiocarpa [Hook.] Nutt.) forests in the Prince George Region of British Columbia. Four outbreaks occurred in relatively close synchrony over the entire region in the period 1880–1999, however, the initiation year, the intensity and extent of outbreaks varied spatially and from one outbreak to another. In some instances, the occurrence of outbreaks was restricted to only one area. The general synchrony of outbreaks suggested that a large‐scale extrinsic factor, such as weather, was at play. However, the imperfect synchrony of outbreaks suggested that local stand characteristics, such as canopy structure, composition of tree species and host plant quality, probably played a major role in preconditioning outbreaks. Dispersal might play a role in synchronizing outbreaks, but the extent to which it contributed to the synchrony was limited in this mountainous region.
Site selection under differential predation risks by drifting prey in streams
Authors: Ruetz III Carl R. , Stephens David W.
Published: December 2004

We derived a model to predict site selection by drifting prey in streams. This model considers the conflicting demands between feeding and avoiding both benthic and drift predators. Our analysis suggests a ranking of site qualities based on the ratio of food acquisition rate to benthic predation risk (termed site value). Drifting organisms should accept a given site type when its site value exceeds the expected value of drifting, which is the average site value prey are likely to encounter adjusted for the costs of drifting. These costs are represented as drift predation risk and time that is lost from foraging as prey search for a better site. We contend that prey should rank site types in descending order based on site value and sequentially add site types to the acceptable category in order of highest rank until the addition of the next lowest ranked site decreases rather than increases the expected value of drifting. The best sites should be those with high food availability and low benthic predation risk. Prey should reject a site when drift predation risk is low, the proportion of acceptable site types is high, and the rate that prey settle from the drift is high. Interestingly, prey with the greatest locomotory ability should have the greatest propensity to drift because these individuals spend less time drifting, making them less susceptible to drift predators. Our model provides a framework to simultaneously integrate the effects of food availability, benthic predation risk, and drift predation risk on site selection of actively drifting prey.
What determines disturbance‐productivity‐diversity relationships? The effect of scale, species and environment on richness patterns in an Australian woodland
Authors: Allcock Kimberly G. , Hik David S.
Published: December 2004

Much of the observed variation in relationships between diversity and disturbance or productivity may be attributed to scale, species characteristics, or environment. We used exclusion fences to create gradients of grazing (by native and introduced herbivores), cover, and standing crop in temperate Eucalypt woodlands. We investigated patterns of native, exotic, and total plant species richness at two scales (1 m2 and 625 m2). Richness patterns were similar at both scales, though species richness at 1m2 was more strongly affected by our grazing treatments. Season and rainfall explained more variation in richness than did surrogate measures of productivity or disturbance by herbivores. The richness‐herbivory relationship depended strongly on rainfall, season, and species origin, and altering these factors produced the entire range of observed diversity‐disturbance relationships. Richness‐biomass and richness‐cover relationships were consistently hump‐shaped, and related to species origin with native richness negatively related and exotic richness positively related. The ability of weedy annuals to pre‐empt space after death may have contributed to the observed unimodal responses.
Antipredator defence of the hermit crab Pagurus filholi induced by predatory crabs
Authors: Mima Azusa , Wada Satoshi , Goshima Seiji
Published: December 2004

Hermit crabs have two antipredator tactics: taking refuge in its shell and fleeing. We examined the following two hypotheses using the hermit crab Pagurus filholi: (1) hermit crabs change their preference for shell types that they take refuge in and/or change the timing of fleeing (i.e. the duration of refuge in the shell) when they perceive a predator threat; (2) the type of shell that a hermit crab occupies affects the fleeing tactic of the individual. Under the stimulus of a crushed conspecific, hermit crabs changed neither their preference for shell species nor their refuge duration. On the other hand, under the stimulus of the predatory crab Gaetice depressus, hermit crabs increased their preference for Batillaria cumingi shells, which provide superior protection against predators, and shortened their refuge duration in the shells even when they occupied those effective against predation. Refuge duration was longer in B. cumingi shells than in the more vulnerable shells of Homalopoma sangarense. These results suggest that both antipredator defences (changing shell and timing of fleeing) are induced by the stimulus of a predator, and the timing of fleeing is affected by the shell type occupied.
Depressant Effects of Ambroxol and Erdosteine on Cytokine Synthesis, Granule Enzyme Release, and Free Radical Production in Rat Alveolar Macrophages Activated by Lipopolysaccharide
Authors: Jang Yoon Young , Song Jin Ho , Shin Yong Kyoo , Han Eun Sook , Lee Chung Soo
Published: December 2004

Abstract: The present study examined the effects of ambroxol and erdosteine, bronchial expectorants, on the cytokine synthesis, granule enzyme release, and free radical production in rat alveolar macrophages activated by lipopolysaccharide. Ambroxol and erdosteine significantly decreased the production of tumour necrosis factors‐α, interleukin‐1β, and interleukin‐6 in alveolar macrophages activated by lipopolysaccharide. These drugs significantly reduced the production of superoxide anion, hydrogen peroxide, and nitric oxide and the release of acid phosphatase and lysozyme in lipopolysaccharide‐activated macrophages. Ambroxol and erdosteine showed no scavenging effect on superoxide anion and hydrogen peroxide, whereas both drugs effectively decomposed nitric oxide. The results show that ambroxol and erdosteine may inhibit the responses, including cytokine synthesis and free radical production, in rat alveolar macrophages activated by lipopolysaccharide. Unlike the production of reactive oxygen species, the inhibitory effect of ambroxol and erdosteine on the production of nitric oxide in lipopolysaccharide‐activated alveolar macrophages may be accomplished by a scavenging action on the species and inhibition of the respiratory burst.
Effects of the Environmental Oestrogens Bisphenol A, Tetrachlorobisphenol A, Tetrabromobisphenol A, 4‐Hydroxybiphenyl and 4,4′‐Dihydroxybiphenyl on Oestrogen Receptor Binding, Cell Proliferation and Regulation of Oestrogen Sensitive Proteins in the Human Breast Cancer Cell Line MCF‐7
Authors: Olsen Christel M. , Meussen‐Elholm Elise T. M. , Samuelsen Mari , Holme Jørn A. , Hongslo Jan K.
Published: December 2004

Abstract: Bisphenol A is extensively used in the manufacturing of epoxy resins and polycarbonate plastics, whereas several brominated and chlorinated analogues are used as flame retardants and intermediates in the plastic industry. Due to the structural relationship between these chemicals and the high production volumes, we wanted to characterize and compare their potential oestrogen‐like potency using several end‐points in MCF‐7 cells: induction of pS2 protein and progesterone receptor, reduction of oestrogen receptor level, and stimulation of cell growth. Bisphenol A, tetrachloro‐ and tetrabromo‐bisphenol A, 4‐hydroxybiphenyl and 4,4′‐dihydroxybiphenyl all showed oestrogen‐like properties in MCF‐7 cells. The chemicals tested had affinity to the oestrogen receptor isolated from MCF‐7 cells, although their EC50s were 1,000 to 80,000 times higher than the EC50 of 17β‐oestradiol. Bisphenol A and 4‐hydroxybiphenyl induced cell growth in MCF‐7 cells, and the highest test concentrations induced responses, apparently exceeding the cell growth induced by 17β‐oestradiol. The other chemicals tested induced less than 50% of the maximum 17β‐oestradiol‐stimulated cell growth. Bisphenol A, 4‐hydroxybiphenyl, tetrabromobisphenol A and tetrachlorobisphenol A all increased the level of the oestrogen‐regulated proteins, progesterone receptor and pS2, whereas 4,4′‐dihydroxybiphenyl showed no such effect. Bisphenol A was the only chemical tested that clearly mimicked 17β‐oestradiol in its ability to reduce the level of cytosolic oestrogen receptors in MCF‐7 cells. By measuring several oestrogen‐dependent endpoints it seems that some xeno‐oestrogens cause an imbalanced oestrogen‐response. Their ability and potency in mimicking 17β‐oestrogen in one parameter is not necessarily accompanied by a similar effect in another oestrogen‐linked parameter.
In vitro Metabolism of Genistein and Tangeretin by Human and Murine Cytochrome P450s
Authors: Breinholt Vibeke M. , Rasmussen Salka E. , Brøsen Kim , Friedberg Thomas H.
Published: December 2004

Abstract: Recombinant cytochrome P450 (CYP) 1A2, 3A4, 2C9 or 2D6 enzymes obtained from Escherichia coli and human liver microsomes samples were used to investigate the ability of human CYP enzymes to metabolize the two dietary flavonoids, genistein and tangeretin. Analysis of the metabolic profile from incubations with genistein and human liver microsomes revealed the production of five different metabolites, of which three were obtained in sufficient amounts to allow a more detailed elucidation of the structure. One of these metabolites was identified as orobol, the 3′‐hydroxylated metabolite of genistein. The remaining two metabolites were also hydroxylated metabolites as evidenced by LC/MS. Orobol was the only metabolite formed after incubation with CYP1A2. The two major product peaks after incubation of tangeretin with human microsomes were identical with 4′‐hydroxy‐5,6,7,8‐tetramethoxyflavone and 5,6‐dihydroxy‐4′,7,8‐trimethoxyflavone, previously identified in rat urine in our laboratory. By comparison with UV spectra and LC/MS fragmentation patterns of previously obtained standards, the remaining metabolites eluting after 14, 17 and 20 min. were found to be demethylated at the 4′,7‐, 4′,6‐positions or hydroxylated at the 3′‐ and demethylated at the 4′‐positions, respectively. Metabolism of tangeretin by recombinant CYP1A2, 3A4, 2D6 and 2C9 resulted in metabolic profiles that qualitatively were identical to those observed in the human microsomes. Inclusion of the CYP1A2 inhibitor fluvoxamine in the incubation mixture with human liver microsomes resulted in potent inhibition of tangeretin and genistein metabolism. Other isozymes‐selective CYP inhibitors had only minor effects on tangeretin or genistein metabolism. Overall the presented observations suggest major involvement of CYP1A2 in the hepatic metabolism of these two flavonoids.
Morphine and d‐Amphetamine Nullify Each Others' Hypothermic Effects in Mice
Authors: Baker Alexis , Meert Theo
Published: December 2004

Abstract: We have examined the effects of the psychostimulant d‐amphetamine and the neuroleptic haloperidol on hypothermia induced by intraperitoneal injection of the centrally penetrating opioids morphine, fentanyl and sufentanil and the peripherally acting opioid loperamide. Measuring rectal body temperatures, dose‐response relationships were established for all compounds. Morphine and sufentanil produced hyperthermia at low doses and dose‐related hypothermia at higher doses. Fentanyl and loperamide produced dose‐related hypothermia. Fixed doses of each opioid producing significant hypothermia were selected for interaction studies. The psychostimulant d‐amphetamine was found to produce biphasic effects with low doses inducing hypothermia and higher doses inducing hyperthemia. Haloperidol produced dose‐related hypothermia. The selected doses of the opioids were then injected followed after 15 min. by injection of hypothermia producing doses of d‐amphetamine or haloperidol. Hypothermia induced by morphine, fentanyl and sufentanil was reversed by d‐amphetamine whereas loperamide‐induced hypothermia was unaffected. Rebound hyperthermia was also measured with fentanyl and sufentanil. Haloperidol increased the hypothermic effects of morphine, fentanyl and sufentanil but not of loperamide. In conclusion, the central stimulating effects of opioids and amphetamine may combine resulting in thermogenesis and reversal of hypothermia. Central mechanisms of opioid‐induced hypothermia in mice are influenced by drugs which alter the dopamine system, whereas peripheral mechanisms are unaffected. A possible clinical implication for this dopaminergic interaction may be toxicity associated with hyperpyrexia caused by psychostimulant misuse, which is increasingly occurring concomitantly with abuse of opioids.