bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamics of enzyme-catalyzed reactions—a database for quantitative biochemistry
Authors: Goldberg Robert N. , Tewari Yadu B. , Bhat Talapady N. 
Published: May 2004

Abstract
Summary: The Thermodynamics of Enzyme-catalyzed Reactions Database (TECRDB) is a comprehensive collection of thermodynamic data on enzyme-catalyzed reactions. The data, which consist of apparent equilibrium constants and calorimetrically determined molar enthalpies of reaction, are the primary experimental results obtained from thermodynamic studies of biochemical reactions. The results from 1000 published papers containing data on 400 different enzyme-catalyzed reactions constitute the essential information in the database. The information is managed using Oracle and is available on the Web.
Availability: http://xpdb.nist.gov/enzyme_thermodynamics/
Changes in species richness with stocking density of marine bivalves
Authors: BEADMAN H. A. , KAISER M. J. , GALANIDI M. , SHUCKSMITH R. , WILLOWS R. I. 
Published: May 2004

Summary

Monocultures of mussels might alter the infaunal benthic community of adjacent and interstitial sediments through provision of a complex habitat, input of organically rich material and larval removal through filter feeding. At a site of commercial seabed mussel cultivation, we aimed to determine the effect of mussels on the infaunal community of an intertidal mudflat at different spatial scales and under different stocking strategies.
Mussels were laid at four different densities (2, 3, 5 and 7·5 kg m−2) on 400‐m2 plots in a 4 × 4 Latin square. Benthic samples were collected within and 10–100 m distant from the cultivation area c. 7 months prior to and 18 months after seeding the plots with blue mussels. Benthic community characteristics were related to initial seeding density and to the actual surface area of mussels associated with each set of samples collected within replicate plots.
The presence of mussels significantly changed the occurrence of some species of the infaunal community within the cultivated area. The infaunal communities supported fewer individuals and species than control treatments at all but the lowest mussel cover.
Species richness and the abundance of individuals per unit area also declined with increased area of mussel cover. The abundance of cirratulids and amphipods declined strongly with increasing mussel surface area.
Although the species composition and abundance of individual invertebrate species were altered by the presence of mussels, the distribution of individuals among species remained relatively unchanged.
Synthesis and applications. Overall, mussel beds changed the infaunal community, but the effects were localized (0–10 m) and not detectable at larger scales (10–100 m). Changes in benthic community composition could be reduced (but not eliminated) by lowering the stocking density of mussels to either 2 or 3 kg m−2. Given the small edge effects associated with cultivated mussel beds, the use of larger mussel beds would be preferable to many smaller mussel beds.
Linking contaminant profiles to the diet and breeding location of American dippers using stable isotopes
Authors: MORRISSEY CHRISTY A. , BENDELL‐YOUNG LEAH I. , ELLIOTT JOHN E. 
Published: May 2004

Summary

Individual variation in contaminant levels is a common occurrence in many toxicology studies, but the exact cause is often unclear. We investigated the influence of diet and breeding location on individual bird contaminant profiles using a colour‐marked population of American dippers Cinclus mexicanus. The population comprised two distinct groups within a single river system: resident dippers breeding on the main river and altitudinal migrants breeding on tributaries.
Residue analysis revealed that total organochlorines (OC), polychlorinated biphenyls (PCB) and mercury (Hg) were all significantly higher in eggs from river residents compared with tributary migrants. This trend was also apparent for the three most prevalent organochlorine compounds: p,p′‐dichlorodiphenyl‐dichloroethylene (DDE), hexachlorobenzene and trans‐nonachlor.
We hypothesized that the observed differences in contaminant concentrations were partially related to the proportion of salmon fry Oncorhynchus spp. in the diet relative to aquatic invertebrates. Stable isotope analyses using δ13C and δ15N were conducted on blood and feathers of dippers in addition to aquatic invertebrates and salmon fry prey. Linear mixing models using the 15N isotope in the dippers’ diet and blood revealed considerable variability in the proportion of fish consumed (0–71%). Resident dippers on the main river ate significantly higher proportions of fish (42%) than tributary migrants (22%) (P = 0·01).
The difference in diet between migratory groups explained some of the observed variation in egg contaminant profiles, as total OC (P = 0·002) in dipper eggs was positively correlated with blood δ15N values, indicating fish may be the primary source of contamination.
Synthesis and applications. We conclude that dipper eggs represent local conditions at the breeding site, making them useful tools for biomonitoring aquatic contaminants in watersheds. However, given the distinct difference in contaminant profiles between resident and migrant dippers and the link with diet, the results emphasize the importance of understanding individual species’ ecology for assessing toxicological effects at the population level.
Managing threatened species: the ecological toolbox, evolutionary theory and declining‐population paradigm
Authors: NORRIS KEN 
Published: May 2004

SummaryThe management of threatened species is an important practical way in which conservationists can intervene in the extinction process and reduce the loss of biodiversity. Understanding the causes of population declines (past, present and future) is pivotal to designing effective practical management. This is the declining‐population paradigm identified by Caughley.There are three broad classes of ecological tool used by conservationists to guide management decisions for threatened species: statistical models of habitat use, demographic models and behaviour‐based models. Each of these is described here, illustrated with a case study and evaluated critically in terms of its practical application.These tools are fundamentally different. Statistical models of habitat use and demographic models both use descriptions of patterns in abundance and demography, in relation to a range of factors, to inform management decisions. In contrast, behaviour‐based models describe the evolutionary processes underlying these patterns, and derive such patterns from the strategies employed by individuals when competing for resources under a specific set of environmental conditions.Statistical models of habitat use and demographic models have been used successfully to make management recommendations for declining populations. To do this, assumptions are made about population growth or vital rates that will apply when environmental conditions are restored, based on either past data collected under favourable environmental conditions or estimates of these parameters when the agent of decline is removed. As a result, they can only be used to make reliable quantitative predictions about future environments when a comparable environment has been experienced by the population of interest in the past.Many future changes in the environment driven by management will not have been experienced by a population in the past. Under these circumstances, vital rates and their relationship with population density will change in the future in a way that is not predictable from past patterns. Reliable quantitative predictions about population‐level responses then need to be based on an explicit consideration of the evolutionary processes operating at the individual level.Synthesis and applications.It is argued that evolutionary theory underpins Caughley's declining‐population paradigm, and that it needs to become much more widely used within mainstream conservation biology. This will help conservationists examine critically the reliability of the tools they have traditionally used to aid management decision‐making. It will also give them access to alternative tools, particularly when predictions are required for changes in the environment that have not been experienced by a population in the past.
Using satellite telemetry and aerial counts to estimate space use by grey seals around the British Isles
Authors: MATTHIOPOULOS JASON , MCCONNELL BERNIE , DUCK CALLAN , FEDAK MIKE 
Published: May 2004

Summary

In the UK, resolving conflicts between the conservation of grey seals, the management of fish stocks and marine exploitation requires knowledge of the seals’ use of space. We present a map of grey seal usage around the British Isles based on satellite telemetry data from adult animals and haul‐out survey data.
Our approach combined modelling and interpolation. To model the seals’ association with particular coastal sites (the haul‐outs), we divided the population into subpopulations associated with 24 haul‐out groups. Haul‐out‐specific maps of accessibility were used to supervise usage estimation from satellite telemetry. The mean and variance of seal numbers at each haul‐out group were obtained from haul‐out counts. The aggregate map of usage for the entire population was produced by adding together the haul‐out‐specific usage maps, weighted by mean number of animals using that haul‐out.
Seal usage was primarily concentrated (i) off the northern coasts of the British Isles, (ii) closer to the coast than might be expected purely on the basis of accessibility from the haul‐outs and (iii) in a limited number of marine hot‐spots.
Although our results currently represent the best estimate of how grey seals use the marine environment around Britain, they are neither definitive nor equally precise for all haul‐outs. Further data collection should focus in the south‐west of the British isles and aerial counts should be repeated for all haul‐outs.
Synthesis and applications. This work provides environmental managers with current estimates of grey seal usage and describes a methodology for maximizing data efficiency. Our results could guide government departments in licensing marine exploitation by the oil industry, in estimating grey seal predation pressure on vulnerable or economically important prey and in delineating marine special areas of conservation (SAC). Our finding that grey seal usage is characterized by a limited number of hot‐spots means that the species is particularly suited to localized conservation efforts.
Reduced numbers of generalist arthropod predators after crop management
Authors: THORBEK P. , BILDE T. 
Published: May 2004

SummaryGeneralist arthropod predators act as natural enemies of insect pests in agro‐ecosystems. Crop management activities may cause a reduction in arthropod densities, either directly through mortality and emigration, or indirectly through habitat disruption. Our aim was to quantify direct mortality caused by mechanical crop treatments. For some treatments, we also quantified emigration and other indirect effects, such as population declines caused by the impact of habitat deterioration on reproduction and survival.Direct mortality was determined by measuring predator densities simultaneously in control and treatment plots using closed emergence traps immediately following a mechanical treatment. Treatments consisted of the following crop management activities: ploughing, non‐inversion tillage, superficial soil loosening, mechanical weed control and grass cutting. Predator densities were measured a second time 5–26 days after treatment to quantify emigration and indirect effects.All treatments had a negative influence on one or more arthropod taxa. Direct mortality caused a 25–60% reduction in arthropod densities. Overall, spiders were more vulnerable to mechanical crop treatment than carabid and staphylinid beetles. Intensive soil cultivation, such as ploughing and soil loosening, did not kill more arthropods than weed harrowing and grass cutting.We estimated the cumulative effects of mortality, emigration and indirect effects 3 weeks following treatment. The cumulative effect was greater than direct arthropod mortality, suggesting delayed effects of habitat disruption.Grass cutting caused spiders and staphylinid beetles to move out of the crop, except in one case when the grass was left to dry, suggesting an important role of organic material or structural elements for arthropod persistence. Our results also suggest that arthropod predators aggregate in undisturbed or less disrupted habitats.Synthesis and applications. Mechanical operations in arable crops and grass cutting cause mortality and emigration of generalist arthropod predators, especially spiders. Effects can be species‐specific and are likely to be affected by the timing of management. In grassland, cutting and removal have greater adverse impacts than leaving cuttings that contribute to habitat structure. Adjacent, less‐disturbed refuge areas are colonized by predators following husbandry events, demonstrating significant spatial dynamics among farmland arthropods. The negative effects of crop husbandry operations might be mitigated by the provision of refuge areas within and adjacent to fields and by maintaining crop and landscape diversity.
Has Danish agriculture maintained farmland bird populations?
Authors: FOX A. D. 
Published: May 2004

Summary

Rapid agricultural change in western Europe has occurred in the last three decades, at cost to farmland biodiversity, particularly birds. This study reviewed agricultural change in Denmark from 1983 to 2001, to compare patterns of intensification and farmland bird abundance with the UK.
Changes in 26 agricultural variables summarized using principal components analysis (PCA) showed consistent changes throughout the period that were similar to the UK. Pig and sheep production, and the extent of winter cereals, rape and fodder maize, all increased. The area used to grow fodder beet and spring barley, the applications of agrochemicals and the numbers of cattle reared all declined. The greatest change in land area in Denmark was the switch from spring‐ to autumn‐sown cereals in the 1980s, almost a decade later than in the UK.
PCA described changes in annual indices of bird abundance based on Danish point count surveys from 1983 to 2001, which were most marked during 1983–90, after which ordination values varied little despite continued agricultural change. Of 27 bird species associated with farmland habitat in Denmark, five declined, 10 showed stable trends and 12 increased, compared with 15, eight and four, respectively, among the same species in the UK.
Agricultural yields have been sustained or enhanced during the survey period, while most farmland bird species declining in the UK have remained stable or increased in Denmark. Of the five declining Danish species, only lapwing Vanellus vanellus and yellowhammer Emberiza citrinella are associated with predominantly farmland habitat. The timing of the declines suggests that the switch to autumn sowing in Denmark has had little effect on any species.
In contrast to the UK, pesticide and inorganic fertilizer use has declined and organic farming has expanded in Denmark since 1983, coinciding with the period of stability/increase in farmland bird abundance. It is not possible to establish any causality from this analysis.
The ability of species showing marked declines in Europe to maintain their number and distribution in the Danish landscape in the face of agricultural intensification gives some optimism for safeguarding farmland birds and biodiversity in the future. However, we need to understand the reasons behind contrasting population trends in Denmark and the UK.
Synthesis and applications. Marked differences between national patterns of agriculture and the contrasting nature of historical intensification offer the opportunity to contrast the effects of major changes in land‐use practice on European farmland biodiversity. Appropriate comparative and individual studies of the effects of changes in specific agricultural management at greater spatial (i.e. supranational) scales are necessary in order to underpin the successful development of future European agricultural policies that will sustain and enhance agricultural yields whilst maintaining farmland biodiversity.
GABABreceptors in Schwann cells influence proliferation and myelin protein expression
Authors: Magnaghi Valerio , Ballabio Marinella , Cavarretta Ilaria T. R. , Froestl Wolfgang , Lambert Jeremy J. , Zucchi Ileana , Melcangi Roberto C. 
Published: May 2004

AbstractThe location and the role of γ‐aminobutyric acid type B (GABAB) receptors in the central nervous system have recently received considerable attention, whilst relatively little is known regarding the peripheral nervous system. In this regard, here we demonstrate for the first time that GABABreceptor isoforms [i.e. GABAB(1)and GABAB(2)] are specifically localized in the rat Schwann cell population of the sciatic nerve. Using the selective GABABagonist [i.e. (–)‐baclofen] and the antagonists (i.e. CGP 62349, CGP 56999 A, CGP 55845 A), such receptors are shown to be functionally active and negatively coupled to the adenylate cyclase system. Furthermore, exposure of cultured Schwann cells to (–)‐baclofen inhibits their proliferation and reduces the synthesis of specific myelin proteins (i.e. glycoprotein Po, peripheral myelin protein 22, myelin‐associated glycoprotein, connexin 32), providing evidence for a physiological role of GABABreceptors in the glial cells of the peripheral nervous system.
Long‐lasting nicotinic modulation of GABAergic synaptic transmission in the rat nucleus accumbens associated with behavioural sensitization to amphetamine
Authors: De Rover Mischa , Mansvelder Huibert D. , Lodder Johannes C. , Wardeh George , Schoffelmeer Anton N. M. , Brussaard Arjen B. 
Published: May 2004

AbstractA robust increase in dopaminergic transmission in the nucleus accumbens (NAc) shell has been reported to be consistently associated with the long‐term expression of behavioural sensitization to drugs of abuse. However, little is known about how this affects the neuronal network of the NAc. We made cellular recordings in NAc slices of saline‐ and amphetamine‐pretreated adult rats and found that expression of behavioural sensitization was associated with long‐lasting changes in the basal firing pattern of cholinergic interneurons up to 3 weeks after the last drug injection. Consequently, upon amphetamine sensitization, an inhibiting effect of the nicotinic receptor blocker mecamylamine on the amplitudes of spontaneous GABAergic synaptic currents as well as on the failure rate of electrically evoked GABAergic currents was found that was not present under control conditions. Thus, behavioural sensitization to amphetamine is associated with an up‐regulation of the endogenous activation of nicotinic receptors that, in turn, stimulate the GABAergic synaptic transmission within the NAc shell. This is a new mechanism by which drugs of abuse may induce alterations in the processing and integration of NAc inputs involved in psychomotor sensitization.
Dendritic spine pathology and deficits in experience‐dependent dendritic plasticity in R6/1 Huntington's disease transgenic mice
Authors: Spires Tara L. , Grote Helen E. , Garry Sylvia , Cordery Patricia M. , Van Dellen Anton , Blakemore Colin , Hannan Anthony J. 
Published: May 2004

AbstractHuntington's disease (HD) is a fatal neurodegenerative disease caused by a CAG repeat expansion coding for an expanded polyglutamine tract in the huntingtin protein. Dendritic abnormalities occur in human HD patients and in several transgenic mouse models of the disease. In this study, we examine, for the first time, dendrite and spine pathology in the R6/1 mouse model of HD, which mimics neurodegeneration seen in human HD. Enriching the environment of HD transgenic mice delays the onset of symptoms, so we also examine the effects of enrichment on dendrite pathology. Golgi‐impregnated tissue from symptomatic R6/1 HD mice reveals a decrease in dendritic spine density and dendritic spine length in striatal medium spiny neurons and cortical pyramidal neurons. HD also causes a specific reduction in the proportion of bifurcated dendritic spines on basal dendrites of cortical pyramidal neurons. No differences in soma size, recurving distal dendrites, or dendritic branching were observed. Although home‐cage environmental enrichment from 1 to 8 months of age increases spine density in wild‐type mice, it has no effect on the spine pathology in HD mice. These results show that dendritic spine pathology in R6/1 HD mice resembles degenerative changes seen in human HD and in other transgenic mouse models of the disease. We thus provide further evidence that the HD mutation disrupts the connectivity in both neostriatum and cerebral cortex, which will contribute to motor and cognitive disease symptoms. Furthermore, we demonstrate that Huntington's disease pathology interferes with the normal plastic response of dendritic spines to environmental enrichment.
Two distinct classes of muscarinic action on hippocampal inhibitory synapses: M2‐mediated direct suppression and M1/M3‐mediated indirect suppression through endocannabinoid signalling
Authors: Fukudome Yuko , Ohno‐Shosaku Takako , Matsui Minoru , Omori Yuko , Fukaya Masahiro , Tsubokawa Hiroshi , Taketo Makoto M. , Watanabe Masahiko , Manabe Toshiya , Kano Masanobu 
Published: May 2004

AbstractThe cholinergic system in the CNS plays important roles in higher brain functions, primarily through muscarinic acetylcholine receptors. At cellular levels, muscarinic activation produces various effects including modulation of synaptic transmission. Here we report that muscarinic activation suppresses hippocampal inhibitory transmission through two distinct mechanisms, namely a cannabinoid‐dependent and cannabinoid‐independent mechanism. We made paired whole‐cell recordings from cultured hippocampal neurons of rats and mice, and monitored inhibitory postsynaptic currents (IPSCs). When cannabinoid receptor type 1 (CB1) was blocked, oxotremorine M (oxo‐M), a muscarinic agonist, suppressed IPSCs in a subset of neuron pairs. This suppression was associated with an increase in paired‐pulse ratio, blocked by the M2‐prefering antagonist gallamine, and was totally absent in neuron pairs from M2‐knockout mice. When CB1 receptors were not blocked, oxo‐M suppressed IPSCs in a gallamine‐resistant manner in cannabinoid‐sensitive pairs. This suppression was associated with an increase in paired‐pulse ratio, blocked by the CB1 antagonist AM281, and was completely eliminated in neuron pairs from M1/M3‐compound‐knockout mice. Our immunohistochemical examination showed that M2 and CB1 receptors were present at inhibitory presynaptic terminals of mostly different origins. These results indicate that two distinct mechanisms mediate the muscarinic suppression. In a subset of synapses, activation of M2 receptors at presynaptic terminals suppresses GABA release directly. In contrast, in a different subset of synapses, activation of M1/M3 receptors causes endocannabinoid production and subsequent suppression of GABA release by activating presynaptic CB1 receptors. Thus, the muscarinic system can influence hippocampal functions by controlling different subsets of inhibitory synapses through the two distinct mechanisms.