bluuebunny/crossref_metadata_2025_split huggingface dataset:
Waterbird responses to experimental drawdown: implications for the multispecies management of wetland mosaics
Authors: Taft Oriane W. , Colwell Mark A. , Isola Craig R. , Safran Rebecca J. 
Published: March 2003

Summary

The loss and human modification of wetlands world‐wide underscores the importance of efficient management. For wetlands that provide habitats for non‐breeding waterbirds, such management often aims to support a rich and abundant waterbird community.
Among the world's many seasonal, moist‐soil managed wetlands, annual winter flooding is followed by spring drawdown to encourage germination of waterfowl food plants. Recommendations on how best to maintain flooded wetlands for multiple species are mostly theoretical, and drawdown management typically focuses on spring for migrating shorebirds. The benefits and drawbacks of shallow‐water management in winter have not been examined, especially where sizeable populations of wintering shorebirds and waterfowl occur together.
We considered The Grasslands Ecological Area in California's Central Valley, USA, as a model wetland complex in which to assess optimal winter flood‐depth for multispecies use. We also examined the relative benefits for each waterbird group (e.g. shorebirds and waterfowl) of drawdowns conducted in winter and spring. We experimentally dewatered wetlands of measured topography in the winter and spring of 1994–95, documenting changes in waterbird species richness and abundance associated with daily changes in habitat diversity and availability.
Results indicated limited regional availability of shallow‐water habitat across the landscape in winter but not spring, as use by shorebirds and teal increased on drawndown wetlands in winter only. Use by deeper‐water dabbling ducks and diving waterbirds declined during the later stages of drawdown in both seasons, but not until use by shorebirds and teal had peaked. The maximum diversity and abundance of waterbirds occurred at average depths of 10–20 cm on wetlands with topographic gradients of 30–40 cm.
This study has important implications for the winter management of seasonal wetland complexes, especially moist‐soil systems where managers provide habitat for different waterbird groups (from shorebirds to diving waterbirds) simultaneously. In general, where topography is variable (e.g. a difference of 30–40 cm between the deepest and shallowest zones), wetlands flooded to average depths of 15–20 cm should accommodate the greatest richness and abundance of waterbirds.
The effect of transgenic nematode resistance on non‐target organisms in the potato rhizosphere
Authors: Cowgill Sue E. , Bardgett Richard D. , Kiezebrink Daan T. , Atkinson Howard J. 
Published: March 2003

Summary

Plant‐parasitic nematodes are important pests of agriculture and transgenic plants with potential for nematode control are currently being developed. The expression of cysteine proteinase inhibitors (cystatins) in potato confers partial resistance to potato‐cyst nematode (PCN). Here, we used field studies to test for effects of cystatin‐expressing potato on non‐target soil organisms.
Microbial community structure, soil microarthropods and litter decomposition were studied during two growing seasons. In the second year, nematode control options of cystatin‐expressing plants and an oxime carbamate nematicide application were compared for their non‐target effects.
In the first year, the transgenic lines had no effect on the abundance, evenness or metabolic activity of the soil microbial community as determined by ester‐linked phospholipid fatty acid analysis (PLFA). However, one transgenic line (D6/7) influenced the structure of the soil microbial community. PLFA suggested it favoured fungal growth relative to bacterial growth during the latter parts of the growing season. A second transgenic line (D5/13) was more effective against PCN. It reduced the abundance of the fungal fatty acid 18 : 2ω6 in late season, suggesting a suppression of fungal growth.
In the second year PLFA analysis suggested microbial abundance was reduced by 15% and 23% in the nematicide and transgenic treatments, respectively, relative to the control. Nematicidal treatment reduced the bacterial fraction of the microbial community, whereas the transgenic plants suppressed both the bacterial and fungal community components.
The observed changes in soil microbial community structure did not result in changes in the rate of leaf litter decomposition.
The transgenic lines had no significant effect on the abundance of soil microarthropods or free‐living nematodes.
The study is the first stage of a risk assessment of the impact of transgenic nematode resistance on non‐target soil organisms. It has highlighted the importance of including currently used management options when studying the effect of transgenic plants on non‐target organisms. Both nematicide use and the transgenic plants affected components of the soil microbial community. However, the changes brought about by the two treatments were not sufficient to affect soil functioning, as measured by rates of litter decomposition.
Evaluation of an agonist index: affinity ratio for compounds active on muscarinic cholinergic M2 receptors
Authors: Tayebati S. K. , Piergentili A. , Natale D. , Amenta F. 
Published: March 2003

1 A protocol for predicting full agonist, partial agonist, and antagonist profiles of compounds with M2 muscarinic cholinergic receptor activity was developed using radioligand binding assay techniques with [3H]‐N‐methyl scopolamine (NMS) and [3H]‐Oxotremorine‐M (Oxo‐M) as radioligands. 2 Full muscarinic cholinergic receptor agonists such as muscarine and oxotremorine‐M expressed a high agonist index (> 3000 for M1 muscarinic cholinergic receptors and > 900 for M2 muscarinic cholinergic receptor), whereas muscarinic receptor antagonists (selective or non‐selective) for different receptor subtypes gave a low (0.5–10) agonist index. 3 Functional studies performed on preparations of guinea‐pig ileum and heart were consistent with radioligand binding assay experiments. 4 The above results suggest that similarly as already established for the M1 muscarinic cholinergic receptor subtype, evaluation of the [3H]‐NMS/[3H]‐Oxo‐M ratio may provide useful information on the profile of compounds acting at the M2 muscarinic cholinergic receptor subtype. 5 The availability of simple and predictive techniques for the characterization of muscarinic M2 cholinergic receptor agonists, may help the identification of new compounds in therapeutic areas in which stimulation or inhibition of this receptor is desirable.
Characterisation of the atypical β‐adrenoceptor in rabbit isolated jejunum using BRL 37344, cyanopindolol and SR 59230A
Authors: MacDonald A. , Watt K. 
Published: March 2003

1 The present study was carried out to further investigate the nature of the β‐adrenoceptor in rabbit jejunum using BRL 37344, a selective β3‐adrenoceptor agonist, cyanopindolol, a β‐adrenoceptor antagonist with blocking activity at β3‐adrenoceptors and SR 59230A, a new selective β3‐adrenoceptor antagonist. 2 Isoprenaline produced a concentration‐dependent inhibition of the spontaneous contractions of rabbit jejunum with a pD2 of 7.14. Propranolol (1 μm) shifted the isoprenaline concentration‐response curve (CRC) to the right with a concentration‐ratio of 5.85, considerably less than would be expected for an action at classical β‐adrenoceptors (estimated pA2 6.66). 3 BRL 37344 also produced a concentration‐dependent inhibition of spontaneous contractions with a pD2 of 7.41. The BRL 37344 CRC was unaffected by propranolol (1 μm). 4 In the presence of propranolol (1 μm), cyanopindolol (1 μm) shifted the isoprenaline CRC to the right (concentration‐ratio of 21). Cyanopindolol also shifted the BRL 37344 CRC to the right (concentration‐ratio of 38). These shifts are consistent with the affinity of cyanopindolol for β3‐adrenoceptors (estimated pA2 values of 7.27 and 7.38 against isoprenaline and BRL 37344, respectively). 5 In the presence of propranolol (1 μm), SR 59230A produced a concentration‐dependent rightward shift of the isoprenaline CRC. The Schild plot gave a pA2 value of 7.16, although the slope of the regression line was significantly different from unity (0.65). SR 59230A also produced a concentration‐dependent shift of the BRL 37344 CRC. The Schild plot gave a pA2 of 7.58 with the slope of the regression line not significantly different from unity (0.81). 6 The presence of β3‐adrenoceptors mediating relaxation of spontaneous contractions in rabbit jejunum is supported by the relatively poor antagonism of isoprenaline by propranolol, the relaxant effect of BRL 37344 and the antagonism of isoprenaline and BRL 37344 by cyanopindolol and SR 59230A. The lack of simple competitive antagonism of isoprenaline, but not BRL 37344, by SR 59230A may suggest more than one population of atypical β‐adrenoceptor.
β1‐ and β3‐adrenoceptors mediate relaxation in ovine trachealis smooth muscle
Authors: Mustafa S. M. D. , Yousif M. , Cherian A. , Oriowo M. A. 
Published: March 2003

1 Isoprenaline (non‐selective) and noradrenaline (β1‐selective) concentration‐dependently relaxed ovine tracheal strips precontracted with carbachol. The pD2 values were 7.07 ± 0.08 and 6.13 ± 0.10 for isoprenaline and noradrenaline, respectively. In the same preparation, salbutamol either produced weak relaxation or in some cases, contractile responses indicating the presence of very little or no β2‐adrenoceptors in this preparation.2 Isoprenaline‐and noradrenaline‐induced relaxations were antagonized by propranolol and atenolol with pA2 values in the range reported in the literature for an action on β1‐adrenoceptors. ICI 118551 also antagonized isoprenaline‐ and noradrenaline‐induced relaxation but at concentrations much higher than are required to block β2‐adrenoceptors, confirming that β2‐adrenoceptors do not contribute significantly to these responses.3 The selective β3‐adrenoceptor agonist, BRL 37344A produced concentration‐dependent relaxation of tracheal strips. BRL 37344A was a full agonist producing 100% relaxation of carbachol‐induced tone. BRL 37344A‐induced relaxation was weakly antagonized by propranolol confirming an action, mainly, on β3‐adrenoceptors. Cyanopindolol antagonized isoprenaline‐induced relaxation (in the presence of propranolol, 10−−7 m) with a pA2 value of 8.06 ± 0.24.4 It was therefore concluded that β1‐ and β3‐adrenoceptors mediated agonist‐induced relaxation in sheep tracheal strips.
Comparison of the effects of nitric oxide synthase, guanylate cyclase and potassium channel inhibition on vascular contractions in vitro in the rat
Authors: Abdullah K. , Docherty J. R. 
Published: March 2003

1 We have investigated the differences between the nitric oxide synthase inhibitor L‐NMMA, the guanylate cyclase inhibitor methylene blue and the potassium channel blockers apamin and charybdotoxin or apamin and iberiotoxin, in their abilities to increase vasoconstrictor responses in rat small mesenteric arterial rings. 2 When administered during the maintained contraction to PGF2α (10 μm), L‐NMMA (100 μm) or the combination of apamin (0.7 μm) and charybdotoxin (0.1 μm) significantly increased the contractile response. Methylene blue (10 μm) increased the contraction, but this did not reach significance. However, apamin (0.7 μm) and iberiotoxin (0.1 μm) also significantly increased the contractile response. 3 The combination of L‐NMMA or methylene blue with apamin/charybdotoxin produced significantly greater increases in the contractile response to PGF2α than achieved individually. 4 Relaxations to acetylcholine (10 μm) were significantly reduced by L‐NMMA or methylene blue but not by apamin in combination with charybdotoxin or iberiotoxin. 5 Since apamin/iberiotoxin had similar effects to apamin/charybdotoxin, it is likely that the actions of these agents involve direct actions on smooth muscle potassium channels rather than inhibition of endothelium‐derived hyperpolarising factor (EDHF). These results suggest that endothelium‐derived nitric oxide but not EDHF has a major role in modulating vascular tone under these conditions.
The effects of histamine on the isolated mouse uterus
Authors: Rubio E. , Navarro‐Badenes J. , Palop V. , Morales‐Olivas F. J. , Martínez‐Mir I. 
Published: March 2003

1 A study is made of the contractile and relaxant effects, and mechanism of action, of histamine on isolated uterus from mice treated with diethylstilboestrol, employing acetylcholine and adrenaline as contractile and relaxant standard agents. 2 Concentration‐response curves for histamine agonists were obtained in the absence and presence of selective histaminergic blocking drugs (clemizole, ranitidine and thioperamide) and indomethacin. A number of experiments were carried out in uterus from reserpinised mice. Concentration‐response curves for acetylcholine and adrenaline were also obtained in the absence and presence of their selective antagonist (atropine and propranolol). 3 In isolated oestrogenised mouse uterus, histamine and acetylcholine produced a concentration‐related contractile response. When the uterus was precontracted with KCl, histamine at lower doses produced a slight contraction, though in the presence of clemizole it induced concentration‐related relaxation, reminiscent of that produced by adrenaline. Atropine and propranolol antagonised the contractile and relaxant effects of acetylcholine and adrenaline, respectively. 4 In isolated uterus from reserpinised mice, histamine and 2‐pyridylethylamine, but not 4‐methylhistamine, produced a concentration‐related contractile response. Ranitidine potentiated the contractile effect of histamine, though clemizole – in the presence of ranitidine – competitively antagonised the contractile effect of histamine (pA2 = 10.50 ± 0.81). The concentration‐relaxant curve of histamine in the presence of clemizole was not modified by ranitidine or indomethacin, but shifted to the right with thioperamide. The same displacement was also observed in the presence of clemizole plus ranitidine. 5 In mouse isolated uterus, histamine mainly produced contraction mediated by histamine H1‐receptors, though the existence of histamine H2‐or H3‐receptors mediating relaxation could not be excluded.
Role of endothelium in ischaemia‐induced myocardial dysfunction of isolated working hearts: cardioprotection by activation of adenosine A2A receptors
Authors: Maddock H. L. , Broadley K. J. , Bril A. , Khandoudi N. 
Published: March 2003

Summary 1 This study aimed to determine the role of the vascular endothelium on recovery of contractile function following global low‐flow ischaemia of guinea‐pig isolated working hearts and the effects of adenosine analogues on this recovery. 2 Guinea‐pig isolated spontaneously beating or paced working hearts were set up and coronary flow (CF), aortic output (AO) (as an index of cardiac function), heart rate (HR), left ventricular pressure (LVP) and dP/dt max recorded. The endothelium was either intact or removed by a blast of oxygen. 3 In spontaneously beating hearts, low‐flow ischaemia for 30 min reduced CF and cardiac contractility (LVP, dP/dt max) but not AO. On reperfusion, CF, LVP and dP/dt max recovered, while AO fell precipitously followed by a gradual recovery, indicative of myocardial stunning. The effects of ischaemia did not differ between endothelium‐intact and ‐denuded hearts, indicating no role of the endothelium in the changes observed. 4 The adenosine analogues, N6‐cyclopentyladenosine (CPA, A1 selective), 5'‐N‐ethylcarboxamidoadenosine (NECA, two‐fold A2 selective over A1) and 2‐p‐((carboxyethyl)‐phenethylamino)‐5'carboxamidoadenosine (CGS21680, A2A selective) were infused (3 × 10−7 M) from 10 min into the 30‐min low‐flow ischaemia of denuded hearts and during reperfusion. 5 CGS21680 increased CF and improved the postischaemic functional recovery, as measured by the AO. NECA and CPA were not cardioprotective. The A2A selective antagonist, ZM241385, attenuated the coronary vasodilatation by CGS21680 and abolished the improved recovery of AO on reperfusion. 6 Reperfusion of paced working hearts caused a dramatic fall in AO which failed to recover. Infusion of CGS21680 from 15 min into the ischaemic period produced vasodilatation but failed to restore AO, presumably because the ischaemic damage was irreversible. 7 Thus, the endothelium plays no role in myocardial dysfunction following low‐flow global ischaemia and reperfusion of guinea‐pig working hearts. The A2A adenosine receptor‐selective agonist but not the non‐selective A2 receptor agonist, NECA, attenuated ischaemia‐ and reperfusion‐induced stunning. This was attributed to increased CF and was independent of the endothelium.
Possible latitudinal clines in Antarctic intertidal and subtidal zone communities encrusting ephemeral hard substrata
Authors: Barnes D. K. A. , Arnold R. J. 
Published: March 2003

Summary Aim Encrusting faunal communities on rocks were examined from Southern Ocean intertidal and subtidal (6 m) zones to investigate potential change with latitude. Location The site locations were South Georgia (54°S [sub‐Antarctic]), Signy Island (60.5°S [maritime Antarctic]) and Adelaide Island (68°S [high Antarctic]). Methods The number of taxa, degree of colonization and bryozoan growth and mortality were measured. Results The communities present were relatively simple in terms of composition and interactions. Spirorbid polychaetes (Annelida) and cheilostomatid bryozoans were the principal components. The community simplicity and dominance of unitary (compared to colonial) fauna increased with latitude. Mean annual mortality of subtidal cheilostomatids also significantly increased with latitude. The number of bryozoan species and potential aspects of community complexity increased with latitude. The growth of the bryozoan Inversiula nutrix increased with latitude reversing the general trend of decreased growth rate. Conclusions These findings suggest that disturbance may significantly increase with latitude within the Southern Ocean. The apparent reversal of typical latitudinal growth trends is probably a result of classical island biogeography, with species decreasing away from a centre of high diversity.
Greta's Garbo: stranded seeds and fruits from Greta Beach, Christmas Island, Indian Ocean
Authors: Green P. T. 
Published: March 2003

Summary AimTo describe the species composition of stranded seeds and fruits drifted by ocean currents to Christmas Island, Indian Ocean. LocationChristmas Island, Indian Ocean. MethodsFrequent visual searches along the strand line of the island's few accessible beaches over a 4‐year period 1988–92, with most effort concentrated on Greta Beach, on the east coast. ResultsThe collection contained not fewer than sixty‐three species in forty‐nine genera and twenty‐nine families. Leguminous seeds were by far the most common (especially Caesalpinia bonduc (L.) Roxb., Dioclea spp., Entada spp., Erythrina spp. and Mucunagigantea (Willd.) DC.), but Calophyllum inophyllum L., Guettarda speciosa L., Hernandia ovigera L., Heritiera littoralis Aiton and Terminalia catappa L. were also common. Main conclusionsOnly about one‐third of species recorded in the drift flora are native to the island, and most disseminules stranded on the island are probably not locally derived. The most likely distant sources of drift disseminules are probably the southern Indonesian islands and Sumatra, with most disseminules probably arriving via the Timor and Arafura Seas between Indonesia and Australia. However, some disseminules may originate from as far east as the Moluccas and the east coast of Kalimantan. The majority of species recorded in the drift flora are not native to the island, and yet some of these were encountered frequently and displayed a high degree of viability on arrival (e.g. Dioclea hexandra (Ralph) Mabb., Erythrina fusca Loureiro and Mucuna gigantea (Willd.) DC.). Several possible reasons for the failure of many drift species to establish on the island are discussed.
Evidence for reticulate palaeogeography: beetle diversity linked to connection‐disjunction cycles of the Gibraltar strait
Authors: Palmer Miquel , Cambefort Yves 
Published: March 2003

AbstractAim Dispersal barriers between areas within some regions have appeared and disappeared throughout evolutionary time. Here we describe the distributional patterns displayed by three taxa living in such kind of regions. These patterns can be better explained considering a reticulated rather than a hierarchically branched palaeogeography.Location Western Mediterranean.Methods The taxa studied are Misolampus (Coleoptera, Tenebrionidae), Tentyria (Coleoptera, Tenebrionidae) and Thorectes (Coleoptera, Geotrupidae). All them are flightless and show a high degree of endemicity. The individual pattern of area relationships was determined separately for each genus by Brooks Parsimony Analysis (BPA). A theoretical general area cladogram was constructed based on the palaeogeographical history of the region. Finally, the general area cladogram is reconciled with the individual ones.Results The ancestor of Misolampus probably was North African. Land dispersal toward the Iberian Peninsula is proposed. Speciation within Iberia is related to specific vicariance events, and the presence of insular (Balearic Islands) populations is explained by sea‐surface or, more probably, human‐mediated dispersal. The ancestor of Tentyria was Iberic. The proposed hypothesis to explain the current species distribution mainly relies on the occurrence of specific vicariance events. However, the occurrence of some sea‐surface dispersal event is not discarded. Almost all possible vicariance events can be recognized in the first clade of the Thorectes genus. There is evidence for dispersal between Africa and Europe at different dates and in both directions. In spite of some uncertainties, the appearance of the second Thorectes clade can also be explained by the occurrence of specific historical events. An ancient dispersal toward the eastern Mediterranean and several dispersal events during the Messinian seem likely.Main conclusions The same historical events have specific outcomes in every tree (even in every branch within a tree) depending on the ability for dispersal and speciation of each taxon. Connection‐disjunction cycles of dispersal barriers have acted as diversity producers.