bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative determination of the binding of β2-glycoprotein I and prothrombin to phosphatidylserine-exposing blood platelets
Authors: BEVERS Edouard M. , JANSSEN Marie P. , COMFURIUS Paul , BALASUBRAMANIAN Krishnakumar , SCHROIT Alan J. , ZWAAL Robert F. A. , WILLEMS George M. 
Published: February 2005

The plasma protein β2GPI (β2-glycoprotein I) has been proposed to mediate phagocytosis of apoptotic cells and to play a role in the antiphospholipid syndrome. This suggestion is based mainly on the presumption that β2GPI has an appreciable interaction with PS (phosphatidylserine)-exposing cell membranes. However, quantitative data on the binding of β2GPI to PS-exposing cells under physiologically relevant conditions are scarce and conflicting. Therefore we evaluated the binding of β2GPI to PS-expressing blood platelets. Flow cytometry showed that binding of β2GPI is negligible at physiological ionic strength, in contrast with significant binding occurring at low ionic strength. Binding parameters of β2GPI and (for comparison) prothrombin were quantified by ellipsometric measurement of protein depletion from the supernatant following incubation with platelets. At low ionic strength (20 mM NaCl, no CaCl2), a dissociation constant (Kd) of 0.2 μM was found for β2GPI, with 7.4×105 binding sites per platelet. Under physiologically relevant conditions (120 mM NaCl and 3 mM CaCl2), binding of β2GPI was not detectable (extrapolated Kd&gt;80 μM). Prothrombin binding (at 3 mM CaCl2) was much less affected by ionic strength: Kd values of 0.5 and 1.4 μM were observed at 20 and 120 mM NaCl respectively. The low affinity and the presence of many lipid-binding proteins in plasma that can compete with the binding of β2GPI suggest that only a small fraction (&lt;5%) of the binding sites on PS-exposing blood cells are likely to be occupied by β2GPI. These findings are discussed in relation to the alleged (patho-)physiological functions of β2GPI.
Subtype-specific regulation of equilibrative nucleoside transporters by protein kinase CK2
Authors: STOLK Meaghan , COOPER Elizabeth , VILK Greg , LITCHFIELD David W. , HAMMOND James R. 
Published: February 2005

Two subtypes of equilibrative transporters, es (equilibrative inhibitor-sensitive) and ei (equilibrative inhibitor-insensitive), are responsible for the majority of nucleoside flux across mammalian cell membranes. Sequence analyses of the representative genes, ENT1 {equilibrative nucleoside transporter 1; also known as SLC29A1 [solute carrier family 29 (nucleoside transporters), member 1]} and ENT2 (SLC29A2), suggest that protein kinase CK2-mediated phosphorylation may be involved in the regulation of es- and ei-mediated nucleoside transport. We used human osteosarcoma cells transfected with catalytically active or inactive α′ and α subunits of CK2 to assess the effects of CK2 manipulation on nucleoside transport activity. Expression of inactive CK2α′ (decreased CK2α′ activity) increased the number of binding sites (∼1.5-fold) for the es-specific probe [3H]NBMPR ([3H]nitrobenzylthioinosine), and increased (∼1.8-fold) the Vmax for 2-chloro[3H]adenosine of the NBMPR-sensitive (es) nucleoside transporter. There was a concomitant decrease in the Vmax of the NBMPR-resistant (ei-mediated) uptake of 2-chloro[3H]adenosine. This inhibition of CK2α′ activity had no effect, however, on either the KD of [3H]NBMPR binding or the Km of 2-chloro[3H]adenosine uptake. Quantitative PCR showed a transient decrease in the expression of both hENT1 (human ENT1) and hENT2 mRNAs within 4–12 h of induction of the inactive CK2α′ subunit, but both transcripts had returned to control levels by 24 h. These data suggest that inhibition of CK2α′ reduced ei activity by attenuation of hENT2 transcription, while the increase in es/hENT1 activity was mediated by post-translational action of CK2. The observed modification in es activity was probably due to a CK2α′-mediated change in the phosphorylation state of the ENT1 protein, or an interacting protein, effecting an increase in the plasma membrane lifetime of the transport proteins.
Hepatically derived selenoprotein P is a key factor for kidney but not for brain selenium supply
Authors: SCHWEIZER Ulrich , STRECKFUß Florian , PELT Paco , CARLSON Bradley A. , HATFIELD Dolph L. , KÖHRLE Josef , SCHOMBURG Lutz 
Published: February 2005

Liver-specific inactivation of Trsp, the gene for selenocysteine tRNA, removes SePP (selenoprotein P) from plasma, causing serum selenium levels to fall from 298 μg/l to 50 μg/l and kidney selenium to decrease to 36% of wild-type levels. Likewise, glutathione peroxidase activities decreased in plasma and kidney to 43% and 18% respectively of wild-type levels. This agrees nicely with data from SePP knockout mice, supporting a selenium transport role for hepatically expressed SePP. However, brain selenium levels remain unaffected and neurological defects do not occur in the liver-specific Trsp knockout mice, while SePP knockout mice suffer from neurological defects. This indicates that a transport function in plasma is exerted by hepatically derived SePP, while in brain SePP fulfils a second, hitherto unexpected, essential role.
Crystal Structures of Alfalfa Caffeoyl Coenzyme A 3-O-Methyltransferase
Authors: Ferrer Jean-Luc , Zubieta Chloe , Dixon Richard A. , Noel Joseph P. 
Published: February 2005

Abstract
Caffeoyl coenzyme A 3-O-methyltransferases (CCoAOMTs) are S-adenosyl-l-methionine-dependent O-methyltransferases (OMTs) involved in lignin biosynthesis. Plant CCoAOMTs belong to a distinct family of OMTs, more closely related to the mammalian catechol OMTs than to other plant OMTs. The crystal structure of alfalfa (Medicago sativa) CCoAOMT in complex with the reaction products S-adenosine-l-homocysteine and feruloyl/sinapoyl CoAs presented here belong to a structurally and mechanistically distinct family of plant small molecule OMTs. These structures provide a new understanding of the substrate preferences and the catalytic mechanism accompanying CCoAOMT-mediated O-methylation of CoA-linked phenylpropanoid substrates.
The Regulation of Anion Loading to the Maize Root Xylem
Authors: Gilliham Matthew , Tester Mark 
Published: February 2005

Abstract
The regulation of anion loading to the shoot in maize (Zea mays) was investigated via an electrophysiological characterization of ion conductances in protoplasts isolated from the root stele. Two distinct anion conductances were identified. In protoplasts from well-watered plants, Z. mays xylem-parenchyma quickly-activating anion conductance (Zm-X-QUAC) was the most prevalent conductance and is likely to load the majority of NO3 − and Cl− ions to the xylem in nonstressed conditions. Z. mays xylem-parenchyma inwardly-rectifying anion conductance was found at a lower frequency in protoplasts from well-watered plants than Zm-X-QUAC, was much smaller in magnitude in all observed conditions, and is unlikely to be such a major pathway for anion loading into the xylem. Activity of Z. mays xylem-parenchyma inwardly-rectifying anion conductance increased following a water stress prior to protoplast isolation, but the activity of the putative major anion-loading pathway, Zm-X-QUAC, decreased. Addition of abscisic acid (ABA) to protoplasts from well-watered plants also inhibited Zm-X-QUAC activity within minutes, as did a high free Ca2+concentration in the pipette. ABA was also seen to activate a Ca2+-permeable conductance (Z. mays xylem-parenchyma hyperpolarization activated cation conductance) in protoplasts from well-watered plants. It is postulated that the inhibition of anion loading into the xylem (an important response to a water stress) due to down-regulation of Zm-X-QUAC activity is mediated by an ABA-mediated rise in free cytosolic Ca2+.
Carbohydrate-Active Enzymes Involved in the Secondary Cell Wall Biogenesis in Hybrid Aspen
Authors: Aspeborg Henrik , Schrader Jarmo , Coutinho Pedro M. , Stam Mark , Kallas Åsa , Djerbi Soraya , Nilsson Peter , Denman Stuart , Amini Bahram , Sterky Fredrik , Master Emma , Sandberg Göran , Mellerowicz Ewa , Sundberg Björn , Henrissat Bernard , Teeri Tuula T. 
Published: February 2005

AbstractWood formation is a fundamental biological process with significant economic interest. While lignin biosynthesis is currently relatively well understood, the pathways leading to the synthesis of the key structural carbohydrates in wood fibers remain obscure. We have used a functional genomics approach to identify enzymes involved in carbohydrate biosynthesis and remodeling during xylem development in the hybrid aspen Populus tremula × tremuloides. Microarrays containing cDNA clones from different tissue-specific libraries were hybridized with probes obtained from narrow tissue sections prepared by cryosectioning of the developing xylem. Bioinformatic analyses using the sensitive tools developed for carbohydrate-active enzymes allowed the identification of 25 xylem-specific glycosyltransferases belonging to the Carbohydrate-Active EnZYme families GT2, GT8, GT14, GT31, GT43, GT47, and GT61 and nine glycosidases (or transglycosidases) belonging to the Carbohydrate-Active EnZYme families GH9, GH10, GH16, GH17, GH19, GH28, GH35, and GH51. While no genes encoding either polysaccharide lyases or carbohydrate esterases were found among the secondary wall-specific genes, one putative O-acetyltransferase was identified. These wood-specific enzyme genes constitute a valuable resource for future development of engineered fibers with improved performance in different applications.
Plant persistence traits in fire‐prone ecosystems of the Mediterranean basin: a phylogenetic approach
Authors: Pausas J. G. , Verdú M. 
Published: February 2005

The two main fire response traits found in the Mediterranean basin are the resprouting capacity (R) and the propagule‐persistence capacity (P). Previous studies suggested that these two traits might be correlated. In this paper we first test whether R and P have evolved independently. Then, we ask if the correlation occurs because (a) one trait is not the target of selection but it is genetically linked to the other trait which is the one under selection pressure (indirect selection), or (b) because different evolutionary responses to the same selective pressure are acting in parallel on populations at different genetic starting points (parallel selection). Finally, we test to what extent resprouting is associated with some vegetative and reproductive traits.To answer these questions we used a traits database for the eastern Iberian Peninsula and we assembled the phylogenetic tree on the basis of published information. The results indicate that the two traits are negatively associated and support the parallel selection scenario in which changes in R precedes changes in P. The phylogenetic–informed associations of resprouting with other traits (plant height, age at maturity) support the existence of allocation tradeoffs.The results are consistent with the biogeographical history of the Mediterranean basin flora where most of lineages already resprouted to persist after a disturbance during the Tertiary, thus making it improbable that an additional costly persistence strategy would evolve under the Quaternary climatic conditions.
Frequency distributions of sward height under sheep grazing
Authors: Barthram G. T. , Duff E. I. , Elston D. A. , Griffiths J. H. , Common T. G. , Marriott C. A. 
Published: February 2005

AbstractCattle and sheep can create and maintain a mixture of relatively tall and short patches in grass swards through selective grazing. In swards that are grazed by cattle this heterogeneous structure can result in the frequencies of height measurements having a skewed distribution that has variously been better described by the double‐normal distribution the gamma distribution and the Weibull distribution than by the more common normal distribution. The fit of these statistical distributions, and the adequacy of the potentially useful log‐normal distribution, to sward height frequencies were tested in sown temperate swards grazed by sheep and compared within a single sward. It was concluded that the single‐normal and Weibull distributions were inadequate and that overall the log‐normal and gamma distributions had the best fit to the measurements.
Plant functional traits, herbivore selectivity and response to sheep grazing in Patagonian steppe grasslands
Authors: CINGOLANI ANA M. , POSSE GABRIELA , COLLANTES MARTA B. 
Published: February 2005

Summary

In some ecosystems there is a positive feedback between forage quality and grazing intensity. This involves three components of plant tolerance to grazing: functional traits, herbivore selectivity and response to grazing. We analysed the relationships between these components at species and community levels in Patagonian steppe grasslands.
We measured plant functional traits [height, specific leaf area (SLA) and foliar toughness] and estimated sheep selectivity and grazing response indices for 35 plant species. Sheep selectivity indices were obtained from microhistological and species’ availability data, and grazing response indices from species’ abundances in sites with contrasting grazing intensities. We performed correlations and multiple regressions among the three types of variables across the pool of 35 species.
To analyse data at the community level, we computed weighted averages of traits and sheep selectivity indices for 34 floristic samples taken from each side of 17 fence lines with contrasting grazing intensities. Correlations between mean trait values and sheep selectivity across the 34 samples, and paired comparisons of those variables between sides of the fences, were performed.
Taller plants had leaves with lower SLA and/or higher toughness. Short species of intermediate toughness were selected more often by sheep, while SLA was not related to sheep selectivity. Short species with high SLA increased with grazing, while toughness and sheep selectivity were unrelated to grazing response.
At the community level, short swards with high average SLA had high selectivity indices and were more abundant on the most intensively grazed sides of fence lines. Leaf toughness was unrelated to other traits or to sheep selectivity, and showed no significant response to grazing.
Synthesis and applications. Intensive grazing can increase the forage value of grasslands by the creation of lawns dominated by tolerant species. However, results from this study showed that some plant species that were avoided by grazers also increased, indicating a potential risk of a shift in composition of grazing lawns towards states of low forage value. This suggests that periodic resting of lawns could be a good management strategy to favour palatable species, thereby minimizing the risk of undesirable shifts in the overall species composition.
Demographic meta‐analysis: synthesizing vital rates for spotted owls
Authors: BOYCE MARK S. , IRWIN LARRY L. , BARKER RICHARD 
Published: February 2005

SummaryEffective resource management ultimately influences vital rates of fecundity and survival for target species. Meta‐analysis can be used to combine results from multiple demographic studies replicated in time and space to obtain estimates of vital rates as well as metrics of population growth.Workshop formats were used to conduct meta‐analyses of mark–recapture experiments on spotted owlsStrix occidentalisin the western USA. The implied motivation for demographic studies of spotted owls has been that changes in vital rates and population growth, λ, reflect the success of conservation strategies, but how to interpret results may not be obvious. Demographic analysis is of little practical utility until vital rates can be linked to management. In the case of spotted owls, future meta‐analyses must focus on co‐variation between vital rates and habitat variables, and experiments will be necessary.Sensitivity of population growth to variation in vital rates is central to demographic analysis, but results must be interpreted cautiously because these sensitivities are not likely to identify the vital rates most responsible for variation in population size, and cannot reveal which vital rates will be most responsive to conservation investments.Difficulties in documenting dispersal seriously compromised estimates of juvenile survival and thereby biased estimates of λpmfrom a projection matrix, a problem that was resolved in later workshops by estimating λRJSdirectly using a reparameterized Jolly–Seber mark–recapture method.Several sources of bias for estimates of vital rates and λ were reviewed. Bias exists in meta‐analysis estimates of λ combined over spatial replicates because λ is a non‐linear function of vital rates. Bias also exists in estimates of average population growth where λtvaries over time. This problem can be reduced by calculating the geometric mean of λ. Research to measure biases associated with the estimation of vital rates and the selection of study areas will be necessary to validate meta‐analyses of demography for spotted owls.Synthesis and applications.Meta‐analysis is ideally suited to studies of the demography of long‐lived species because of the large areas involved, high costs for each individual study, and multiple jurisdictions within which the organisms occur. Mixed models selected using information–theoretic approaches provide a powerful way to combine research results from several studies in a meta‐analysis.
Development of inland lakes as hubs in an invasion network
Authors: MUIRHEAD JIM R. , MACISAAC HUGH J. 
Published: February 2005

Summary

The ability to predict spatially explicit dispersal by non‐indigenous species is a difficult but increasingly important undertaking as it allows management efforts to be focused around areas identified as susceptible to invasion. Lakes may serve as useful models for these studies because the habitats are well defined, and vectors of spread may be readily identified and quantified. In this study, we examined patterns of spread of the non‐indigenous spiny waterflea Bythotrephes longimanus to inland lakes in Ontario, Canada, to identify lakes for which management efforts to reduce traffic would be most effective.
We surveyed people using lakes for recreational purposes to quantify movements of trailered boats and other risky activities, to model relative vector traffic from invaded lakes to non‐invaded and other invaded lakes. Non‐linear functions were developed to describe the cumulative number of invaded and non‐invaded destination lakes visited by people leaving five important lakes already invaded by the spiny waterflea (Huron, Simcoe, Muskoka, Panache and Kashagawigamog). The relative difference in these functions was used to identify which lakes will develop into future invasion hubs and will therefore be most important to future dispersal of the species.
In the recent past, Lake Muskoka has been an important hub from which the spiny waterflea has invaded other lakes. It is unlikely to continue to be a source for waterflea invasion as most outbound traffic is to previously invaded lakes. Conversely, most outbound traffic from Lakes Kashagawigamog and Simcoe is to non‐invaded lakes and, therefore, these lakes are likely to develop into hubs in the future.
Synthesis and applications. These data on zooplankton in lake systems and associated mechanisms of transport indicate patterns not only of intrinsic value to lake management, but also of potential importance in understanding invasions more generally. Frequency distributions of the number of outbound connections to both invaded and non‐invaded destinations from invaded sources follow a power function, consistent with scale‐free networks. These networks indicate that small proportions of sources function as hubs. Management efforts targeted to remove developing hubs from the invasion network, rather than equal effort applied to outbound vector traffic from all sources, may reduce the predicted rate of new invasions.
Fungicide levels and arbuscular mycorrhizal fungi in golf putting greens
Authors: BARY FREDERIC , GANGE ALAN C. , CRANE MARK , HAGLEY KAREN J. 
Published: February 2005

Summary

Annual meadow grass Poa annua is the most problematic weed within sports turf in temperate climates. It is so abundant that herbicides cannot be used against it because almost total loss of the sward would occur. Arbuscular mycorrhizal (AM) fungi can be used as biological control agents of P. annua, acting to reduce its growth while increasing that of desirable perennial grasses. However, natural levels of AM fungi in amenity turf are very low. Sports turf is characterized by high fungicide usage, so this study tested the hypothesis that levels of toxic elements (derived from historical fungicide applications) and/or organic fungicides are related to the low mycorrhizal abundance observed.
Records of fungicide applications to putting greens at four golf courses in south‐east England were collected for the period 1993–2000. Soils from all 18 putting greens on each course were sampled during spring 2000. Levels of arsenic, cadmium, copper and lead were recorded, as these elements formed part of the fungicidal compounds applied in the past. Of the organic fungicides in current use, chlorothalonil, fenarimol and iprodione were found to comprise more than 70% of all compounds used and soil levels of these three chemicals were also measured. Levels of AM colonization of P. annua were recorded at every putting green. The rates of AM colonization of desirable grasses could not be obtained because these were too rare in all the swards examined.
There was little evidence that the abundance of AM fungi, as measured by arbuscular colonization of roots, was affected by the presence of any of the chemicals. Levels of all elements were below the ambient levels for UK soils.
Chlorothalonil, fenarimol and iprodione were applied to a single putting green over a 6‐month period but no effects on AM colonization were found.
Synthesis and applications. We have demonstrated that the low levels of AM fungi in putting greens are unlikely to be a consequence of excessive fungicide application. Levels of compounds applied in the last 20 years are very low and modern fungicides do not reduce existing AM colonization when applied to turf. Therefore, if AM fungi are added to sports turf to control P. annua, their effectiveness will not be compromised by current or past fungicide use.