bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accurately ageing trees and examining their height‐growth rates: implications for interpreting forest dynamics
Authors: Gutsell S. L. , Johnson E. A. 
Published: March 2003

Summary

We examined the validity of classifying tree species as early, mid‐, or late‐successional based on age and height‐growth rates, by comparing the age and height‐growth rates of trees in the boreal forest.
Age was first examined using the traditional method of coring 30 cm above the root collar; then dendrochronology was used to locate the root collar and missing annual growth rings. Traditional ageing differentially underestimates tree age; species classified as early successional (Populus tremuloides, Betula papyrifera, and Pinus banksiana) are less severely underestimated than those classified as mid‐ and late‐successional (Picea glauca, Picea mariana, and Abies balsamea) (0–11 vs. 0–43 years), and also have relatively fewer locally missing growth rings. Ageing at the root collar shows that all tree species recruit within 5–10 years after fire and age cannot therefore be used to determine successional status.
Mean time taken to grow to each 1‐m increment from the root collar was estimated for each species. Species classified as early successional have relatively higher growth rates between the root collar and the first metre; they are therefore less severely underestimated when aged above the root collar, explaining why they often appear older than species classified as mid‐ and late‐successional. The lack of species differences above 1 m means that height‐growth rates cannot be used to classify these tree species as early, mid‐, or late‐successional.
In the boreal forest of Saskatchewan, the rapid recruitment of all tree species after fire, and the short fire cycle mean that the forest dynamics between catastrophic wildfires are driven primarily by the mortality rates of each species.
Citicoline: neuroprotective mechanisms  in cerebral ischemia
Authors: Rao Muralikrishna Adibhatla  , Hatcher J. F. , Dempsey R. J. 
Published: March 2003

AbstractCytidine‐5′‐diphosphocholine (citicoline or CDP‐choline), an intermediate in the biosynthesis of phosphatidylcholine (PtdCho), has shown beneficial effects in a number of CNS injury models and pathological conditions of the brain. Citicoline improved the outcome in several phase‐III clinical trials of stroke, but provided inconclusive results in recent clinical trials. The therapeutic action of citicoline is thought to be caused by stimulation of PtdCho synthesis in the injured brain, although the experimental evidence for this is limited. This review attempts to shed some light on the properties of␣citicoline that are responsible for its effectiveness. Our studies in transient cerebral ischemia suggest that citicoline might enhance reconstruction (synthesis) of PtdCho and sphingomyelin, but could act by inhibiting the destructive processes (activation of phospholipases). Citicoline neuroprotection may␣include: (i) preserving cardiolipin (an exclusive inner mitochondrial membrane component) and sphingomyelin; (ii)␣preserving the arachidonic acid content of PtdCho and phosphatidylethanolamine; (iii) partially restoring PtdCho levels; (iv) stimulating glutathione synthesis and glutathione reductase activity; (v) attenuating lipid peroxidation; and (vi)␣restoring Na+/K+‐ATPase activity. These observed effects␣of citicoline could be explained by the attenuation of␣phospholipase A2 activation. Based on these findings, a singular unifying␣mechanism has been hypothesized. Citicoline also provides choline for synthesis of neurotransmitter acetylcholine, stimulation of tyrosine hydroxylase activity and dopamine release.
Up‐regulation of tissue‐type transglutaminase after traumatic  brain injury
Authors: Tolentino Paul J. , DeFord S. Michelle , Notterpek Lucia , Glenn Christopher C. , Pike Brian R. , Wang Kevin K. W. , Hayes Ronald L. 
Published: March 2003

AbstractTissue‐type transglutaminase (tTG, EC 2.3.2.13) has been implicated in various disease paradigms including neurodegenerative disease. In these studies, tTG induction after traumatic brain injury was studied using a rat cortical impact model. Using western blots, two forms of tTG protein expression were identified – a ∼79‐kDa primary form (tTG‐L) and a less abundant ∼70‐kDa form (tTG‐S). Both forms of tTG protein were elevated after injury. In ipsilateral cortex, peak induction of tTG‐L protein [561% ± 80% of control (n = 5)] was observed five days after injury, with expression remaining elevated after two weeks. Peak induction of tTG‐S protein [302% ± 81% of control (n = 5)] was observed three days after injury. Lesser tTG protein induction was observed in hippocampus. Northern blot analysis demonstrated two tTG transcripts in the ipsilateral cortex with peak induction of tTG‐L mRNA three days after injury. However, tTG‐S mRNA was not identified in control samples and only faintly detected in injured tissue. To facilitate analysis of low abundance transcripts in smaller tissue samples, a semiquantitative real‐time PCR strategy was used. Semi‐quantitative PCR analysis of tTG‐L mRNA induction in ipsilateral cortex (peak after three days; 414% ± 21% of control, n= 3) confirmed tTG‐L mRNA induction determined by northern blot (410% of control).
Dietary restriction enhances neurotrophin expression and neurogenesis in the hippocampus of adult mice
Authors: Lee Jaewon , Seroogy Kim B. , Mattson Mark P. 
Published: March 2003

AbstractThe adult brain contains small populations of neural precursor cells (NPC) that can give rise to new neurons and glia, and may play important roles in learning and memory, and recovery from injury. Growth factors can influence the proliferation, differentiation and survival of NPC, and may mediate responses of NPC to injury and environmental stimuli such as enriched environments and physical activity. We now report that neurotrophin expression and neurogenesis can be modified by a change in diet. When adult mice are maintained on a dietary restriction (DR) feeding regimen, numbers of newly generated cells in the dentate gyrus of the hippocampus are increased, apparently as the result of increased cell survival. The new cells exhibit phenotypes of neurons and astrocytes. Levels of expression of brain‐derived neurotrophic factor (BDNF) and neurotrophin‐3 (NT‐3) are increased by DR, while levels of expression of high‐affinity receptors for these neurotrophins (trkB and trkC) are unchanged. In addition, DR increases the ratio of full‐length trkB to truncated trkB in the hippocampus. The ability of a change in diet to stimulate neurotrophin expression and enhance neurogenesis has important implications for dietary modification of neuroplasticity and responses of the brain to injury and disease.
Glucose deprivation and hypoxia increase the expression of the GLUT1 glucose transporter via a specific mRNA cis‐acting regulatory element
Authors: Boado Ruben J. , Pardridge William M. 
Published: March 2003

AbstractThe expression of the glucose transporter type‐1 (GLUT1) gene is up‐regulated in hypoxia and glucose deprivation. A 10 nucleotide (nt) cis‐acting regulatory element (CAE), which is located within nt 2181–2190 of the GLUT1 3′‐untranslated region (CAE2181−2190), increases the expression of a GLUT1‐luciferase reporter gene and decreases its mRNA decay. The present study investigated the role of the GLUT1 CAE2181−2190 in glucose deprivation and hypoxia using stable transfectants. Glucose and O2 deprivation produced a marked increase in the expression of the GLUT1 reporter gene carrying the CAE2181−2190, and this effect was additive. Glucose deprivation and/or hypoxia induced no significant changes in the expression of the reporter gene wherein the GLUT1 CAE2181−2190 was site‐directed deleted. Data presented here suggest that the GLUT1 CAE2181−2190 participates in the increase of GLUT1 gene expression in glucose deprivation and hypoxia.
Interaction between metabotropic glutamate receptor 7 and alpha tubulin
Authors: Saugstad Julie A. , Yang Sufang , Pohl Jan , Hall Randy A. , Conn P. Jeffrey 
Published: March 2003

AbstractMetabotropic glutamate receptors (mGluRs) mediate a variety of responses to glutamate in the central nervous system. A primary role for group‐III mGluRs is to inhibit neurotransmitter release from presynaptic terminals, but the molecular mechanisms that regulate presynaptic trafficking and activity of group‐III mGluRs are not well understood. Here, we describe the interaction of mGluR7, a group‐III mGluR and presynaptic autoreceptor, with the cytoskeletal protein, alpha tubulin. The mGluR7 carboxy terminal (CT) region was expressed as a GST fusion protein and incubated with rat brain extract to purify potential mGluR7‐interacting proteins. These studies yielded a single prominent mGluR7 CT‐associated protein of 55 kDa, which subsequent microsequencing analysis revealed to be alpha tubulin. Coimmunoprecipitation assays confirmed that full‐length mGluR7 and alpha tubulin interact in rat brain as well as in BHK cells stably expressing mGluR7a, a splice variant of mGluR7. In addition, protein overlay experiments showed that the CT domain of mGluR7a binds specifically to purified tubulin and calmodulin, but not to bovine serum albumin. Further pull‐down studies revealed that another splice variant mGluR7b also interacts with alpha tubulin, indicating that the binding region is not localized to the splice‐variant regions of either mGluR7a (900–915) or mGluR7b (900–923). Indeed, deletion mutagenesis experiments revealed that the alpha tubulin‐binding site is located within amino acids 873–892 of the mGluR7 CT domain, a region known to be important for regulation of mGluR7 trafficking. Interestingly, activation of mGluR7a in cells results in an immediate and significant decrease in alpha tubulin binding. These data suggest that the mGluR7/alpha tubulin interaction may provide a mechanism to control access of the CT domain to regulatory molecules, or alternatively, that this interaction may lead to morphological changes in the presynaptic membrane in response to receptor activation.
Symbiotic nitrogen fixation research in the postgenomics era
Authors: Colebatch G. , Trevaskis B. , Udvardi M. 
Published: March 2003

SummaryNitrogen‐fixing symbioses between legumes and rhizobia are important for sustainable agriculture and contribute significantly to the global nitrogen cycle. The genomes of two rhizobial species, Mesorhizobium loti and Sinorhizobium meliloti have now been completely sequenced. Hundreds of thousands of expressed sequence tags representing tens of thousands of different genes from three major legume species; soybean, Medicago truncatula and Lotus japonicus have also been deposited in the public domain. Lotus japonicus recently became the focus of a genome project that aims to sequence one third of the entire genome over the next 5 yr. With this as a backdrop, the stage is set for a renaissance in symbiosis research, which will provide new insight into the complex molecular interplay that underpins symbiotic nitrogen fixation. This review considers how functional genomics might contribute to this renaissance.
Dry matter content as a measure of dry matter concentration in plants and their parts
Authors: Shipley Bill , Vu Thi‐Tam 
Published: March 2003

Summary

This study compared the predictive ability of dry matter content (DMC, dry mass per fresh mass) of leaves, stems, roots and entire plants in relation to dry matter concentration (D, dry mass per volume of plant organ). Data came from 28 species of field‐collected plants (woody and herbaceous) and 17 species of herbaceous plants grown in hydroponic sand culture. Specific leaf areas were also measured.
Dry matter content of the herbaceous plants grown in sand culture varied more between tissue types than did dry matter concentration but the correlation among plant parts was stronger when using DMC. Means and standard errors for DMC (g g−1) were 0.212 ± 0.009 (leaves), 0.176 ± 0.012 (support tissues) and 0.170 ± 0.021 (roots); for D (g cm−3) the values were 0.158 ± 0.010 (leaves), 0.168 ± 0.017 (support tissues) and 0.153 ± 0.013 (roots).
Leaf DMC provided approximate estimates of leaf D (r = 0.76) for the field‐collected plants but sclerophyllous leaves from shrubs restricted to acidic bogs proved to be outliers. The relationship between these two variables was stronger in the herbaceous species grown in sand culture, especially so for whole plant estimates (r = 0.91).
Dry matter content and dry matter concentration were equally good predictors of specific leaf area.
Load Testing of Floor Slabs in a Full‐scale Reinforced Concrete Building
Authors: Scott R. H. , Gilbert S. G. , Moss R. M. 
Published: March 2003

AbstractA series of short and long term service load tests were undertaken on the sixth floor of the full‐scale, seven storey, reinforced concrete building at the Large Building Test Facility of the Building Research Establishment at Cardington. By using internally strain gauged reinforcing bars cast into an internal and external floor bay during the construction process it was possible to gain a detailed record of slab strains resulting from the application of several arrangements of test loads. Short term tests were conducted in December 1998 and long term monitoring then ensued until April 2001. This paper describes the test programmes and presents results to indicate slab behaviour for the various loading regimes.
Failure Investigation of a Gas Turbine Inlet Weatherhood
Authors: Sykes J. , Allison I. M. 
Published: March 2003

AbstractAnalytical and experimental methods have been used to investigate fatigue failures in the weatherhood protecting the air inlet to an offshore gas turbine power generation unit. A simple method for modelling transverse vibration of the leading edge is described, and the results are compared with experimental measurements made on a prototype installation. Calculation of the stresses induced at the critical locations, where cracking has been observed, suggests the failure should be attributed to aerodynamic excitation of the leading edge.
P–T conditions of decompression of the Limpopo high‐grade terrane: record from shear zones
Authors: Smit C. A. , Van Reenen D. D. , Gerya T. V. , Perchuk L. L. 
Published: March 2003

AbstractThe Southern Marginal Zone of the late Archean Limpopo Belt of southern Africa is an example of a high‐grade gneiss terrane in which both upper and lower crustal deformational processes can be studied. This marginal zone consists of large thrust sheets of complexly folded low‐strain gneisses, bound by an imbricate system of kilometre‐wide deep crustal shear zones characterized by the presence of high‐strain gneisses (‘primary straight gneisses’). These shear zones developed during the decompression stage of this high‐grade terrane. Low‐ and high‐strain gneisses both contain similar reaction textures that formed under different kinematic conditions during decompression. Evidence for the early M1/D1 metamorphic phase (> 2690 Ma) is rarely preserved in low‐strain gneisses as a uniform orientation of relict Al‐rich orthopyroxene in the matrix and quartz and plagioclase inclusions in the cores of early (M1) Mg‐rich garnet porphyroblasts. This rare fabric formed at > 820 °C and > 7.5 kbar. The retrograde M2/D2 metamorphic fabric (2630–2670 Ma) is well developed in high‐strain gneisses from deep crustal shear zones and is microscopically recognized by the presence of reaction textures that formed synkinematically during shear deformation: M2 sigmoid‐shaped reaction textures with oriented cordierite–orthopyroxene symplectites formed after the early M1 Mg‐rich garnet porphyroblasts, and syn‐decompression M2 pencil‐shaped garnet with oriented inclusions of sillimanite and quartz formed after cordierite under conditions of near‐isobaric cooling at 750–630 °C and 6–5 kbar. The symplectites and pencil‐shaped garnet are oriented parallel to the shear fabric and in the stretching direction. Low‐strain gneisses from thrust sheets show similar M2 decompression cooling and near‐isobaric cooling reaction textures that formed within the same P–T range, but under low‐strain conditions, as shown by their pseudo‐idioblastic shapes that reflect the contours of completely replaced M1 garnet and randomly oriented cordierite–orthopyroxene symplectites. The presence of similar reaction textures reflecting low‐strain conditions in gneisses from thrust sheets and high‐strain conditions in primary straight gneisses suggests that most of the strain during decompression was partitioned into the bounding shear zones. A younger M3/D3 mylonitic fabric (< 2637 Ma) in unhydrated mylonites is characterized by brittle deformation of garnet porphyroclasts and ductile deformation of the quartz–plagioclase–biotite matrix developed at < 600 °C, as the result of post‐decompression shearing under epidote–amphibolite facies conditions.
Fluid inclusions in coesite‐bearing eclogites and jadeite quartzite at Shuanghe, Dabie Shan (China)
Authors: Fu B. , Touret J.L.R. , Zheng Y.‐F. 
Published: March 2003

AbstractFluid inclusions in coesite‐bearing eclogites and jadeite quartzite at Shuanghe in Dabie Shan, East‐central China, have preserved remnants of early, prograde and/or peak metamorphic fluids, reset during post‐UHP (ultrahigh‐pressure) metamorphic uplift. Inclusions occur in several minerals (e.g. omphacite & epidote), notably as isolated, primary inclusions in quartz included in various host minerals. Two major fluid types have been identified: non‐polar fluid species (N2 or CO2) and aqueous, the latter is by far the most predominant. Aqueous fluids cover a wide range of salinity, from halite‐bearing brines to low salinity fluids. For non‐polar fluids, few N2 inclusions occur in undeformed eclogite, whereas a number of CO2‐rich inclusions have been found in microshear zones of eclogite or jadeite quartzite in close proximity to marble occurrences.The primary character of N2 and high‐salinity aqueous inclusions indicates that they are remnants from UHP metamorphic fluids and for some there is the distinct possibility that they are ultimately derived from pre‐metamorphic fluids. This conclusion is supported by the preservation, in some samples, of microdomains containing synchronous inclusions of variable salinities, which tend to relate to the chemical composition of the host crystal. Carbonic fluids may be derived from neighbouring rocks, notably marble and carbonate‐bearing metasediments, during post‐metamorphic uplift. During post‐UHP exhumation, a limited decrease of the fluid density has occurred, with formation of new sets of fluid inclusions. Fluid movements, however, remained exceedingly limited, at the scale of the enclosing crystal.
Metamorphic processes: a celebration of the career contribution of Ron Vernon
Authors: Brown Michael , Clarke Geoffrey L. 
Published: March 2003

AbstractThis Special Issue is in celebration of the career contribution of Ron Vernon. It arises from the ‘Ron Vernon Symposium’, which was held as part of the 15th Australian Geological Convention in Sydney in 2000. To date Ron has published more than one hundred scientific papers, several books and contributed widely to international conferences. He is the doyen in the multidisciplinary field of microstructures, which spans petrology and structural geology. However, Ron's range is phenomenal, and he has contributed to many aspects of metamorphism, magmatism and rock deformation. He has drawn on data from his work in these areas to contribute widely to understanding thermal regimes, crustal evolution and tectonics, as exemplified by his ideas about HTLP metamorphism and emplacement of granites. Ron has followed the scientific method in his work; it has led him to many innovative interpretations, some of which undermined established dogma. By example, Ron has been a positive role model for the younger generation. However, for the older generation, he has been something of a bête noire! The papers in this Special Issue cover the range from low‐ to high‐grade metamorphism, from metasomatism to melting, from microstructures to tectonics, and from fieldwork to experiments. It is our hope that in reading them you will take time to think about what has been achieved in the past 40 years, and use this as motivation for what remains to be done.
Laboratory and field evaluation of insect repellents as larvicides against the mosquitoes Aedes albopictus and Anopheles albimanus
Authors: Xue R.‐D. , Barnard D. R. , Ali A. 
Published: March 2003

Abstract. Acute toxicity and persistence of three insect repellents, deet and two piperidines (AI3‐35765 and AI3‐37220), were evaluated against mosquito larvae of Aedes albopictus (Skuse) and Anopheles albimanus Wiedemann (Diptera: Culicidae) in the laboratory, and against natural populations of Ae. albopictus in the field. In laboratory studies, the LC50 values of the repellents for first instars ranged between 0.005 and 0.021% (Ae. albopictus) and between 0.01 and 0.014% (An. albimanus) and, for fourth instars, between 0.019 and 0.034% (Ae. albopictus) and between 0.015 and 0.024% (An. albimanus). A 0.1% concentration of deet caused 90–100% mortality in first‐instar Ae. albopictus for 4 weeks, whereas AI3‐35765 and AI3‐37220 at the same concentration killed 95–100% of larvae for 12 weeks and 98–100% of larvae for 33 weeks post‐treatment, respectively. Deet and AI3‐35765 at 0.1% concentration resulted in complete mortality of first‐instar An. albimanus for 3 weeks post‐treatment, whereas AI3‐37220 resulted in 91–99% larval mortalities for 35 weeks post‐treatment. A 0.1% concentration of AI3‐37220 provided 77–98% larval mortality for 20 weeks and 63–97% larval mortality for 12 weeks post‐treatment, respectively, against fourth‐instar Ae. albopictus and An. albimanus.In the field, in artificial containers, the reduction of Ae. albopictus larvae caused by deet, AI3‐35765 and AI3‐37220 was 88–95% for 3–4 weeks, 98–100% for 7 weeks, and 82–100% for 13 weeks post‐treatment, respectively. In used tyres, the same concentration of the repellents resulted in 100% reduction of Ae. albopictus larvae for 2 weeks (deet), 4 weeks (AI3‐35765) and 5 weeks (AI3‐37220) post‐treatment. In cemetery flower vases, Aedes spp. larvae were eliminated for 4 weeks (deet) and 6 weeks post‐treatment by both AI3‐35765 and AI3‐37220. These topical repellents (particularly AI3‐37220) have good potential for development and use in the management of container‐inhabiting mosquitoes because they deter oviposition and kill larvae.
Technical Advance: Tobacco rattle virus as a vector for analysis of gene function by silencing
Authors: Ratcliff Frank , Martin‐Hernandez Ana Montserrat , Baulcombe David C. 
Published: March 2003

SummaryVirus vectors carrying host‐derived sequence inserts induce silencing of the corresponding genes in infected plants. This virus‐induced gene silencing (VIGS) is a manifestation of an RNA‐mediated defence mechanism that is related to post‐transcriptional gene silencing (PTGS) in transgenic plants. Here we describe an infectious cDNA clone of tobacco rattle virus (TRV) that has been modified to facilitate insertion of non‐viral sequence and subsequent infection to plants. We show that this vector mediates VIGS of endogenous genes in the absence of virus‐induced symptoms. Unlike other RNA virus vectors that have been used previously for VIGS, the TRV construct is able to target host RNAs in the growing points of plants. These features indicate that the TRV vector will have wide application for gene discovery in plants.