bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endothelium‐dependent vasodilatation mechanisms by histamine in simian but not in canine femoral arterial branches
Authors: Arai M. , Chiba S. 
Published: March 2003

1 The vascular response of isolated, perfused canine and simian femoral arteries, which distribute blood to deep skeletal muscles, were investigated. 2 The vascular responses to histamine, 2‐pyridylethylamine (2‐PEA), dimaprit and α‐methylhistamine were pharmacologically analyzed in canine and simian vessels, using diphenhydramine (DPH, a histamine H1 receptor antagonist), cimetidine (a histamine H2 antagonist) and saponin which readily removed the endothelium. 3 In canine arteries, α‐methylhistamine showed no vascular response, but in simian preparations, it caused a slight vasoconstriction. 4 In canine arteries, histamine and 2‐PEA consistently induced a vasoconstriction in preconstricted and non‐preconstricted preparations. However, in simian arteries histamine usually produced a vasodilatation at small doses (less than 10−−7mol) and a vasoconstriction at large doses in preconstricted preparations. 5 Vasoconstrictor responses to histamine and 2‐PEA were significantly inhibited by DPH in both species. In simian vessels, histamine‐and dimaprit‐induced vasodilatations were significantly inhibited by cimetidine. 6 After removal of the endothelium by intraluminal treatment with saponin in canine femoral arteries, the vascular responses to histamine, 2‐PEA and dimaprit were not significantly affected. On the other hand, in simian femoral arteries, the vasodilatation responses to histamine and 2‐PEA were significantly depressed by the removal of endothelium. 7 It is concluded that (1) in both simian and canine femoral arterial branches, there are abundant histamine H1 and H2 receptors (2) in simian but not in canine arteries, there exist histamine H3 receptors, although their role is not clear (3) histamine induces a vasoconstriction mediated via histamine H1 receptors and a vasodilatation via H2 receptors which exist in vascular smooth muscle, and (4) in simian but not in canine arteries, there are endothelium‐dependent vasodilatation mechanisms.
Retracted: Dopamine receptor immunohistochemistry in the rat choroid plexus
Authors: Mignini F. , Bronzetti E. , Felici L. , Ricci A. , Sabbatini M. , Tayebati S. K. , Amenta F. 
Published: March 2003

1 Earlier studies have demonstrated a high density of dopamine D1‐like receptor binding in the choroid plexus by light microscope autoradiography, but the dopaminergic specificity of this binding was questioned. 2 In this study the localization of dopamine receptor subtypes was investigated in the rat choroid plexus by Western blot analysis and immunohistochemistry using antibodies raised against dopamine D1–D5 receptor protein. 3 Western blot analysis revealed reactivity with immune bands of approximately 50 and 51 KDa corresponding to dopamine D1 and D5 receptors, respectively. Dopamine D1‐like (D1 and D5) receptor protein immunoreactivity insensitive to superior cervical ganglionectomy was located in smooth muscle of choroid arteries and to a larger extent within choroid plexus epithelium. 4 Western blot analysis revealed reactivity with immune bands of approximately 53 KDa and 40–42 KDa corresponding to dopamine D2 and D4 receptors, respectively, and no dopamine D3 receptor reactivity. Dopamine D2‐like receptor protein immunoreactivity displayed a distribution similar to that of tyrosine‐hydroxylase (TH)‐immunoreactive sympathetic fibres and disappeared after superior cervical ganglionectomy. It consisted in the expression of dopamine D2 and to a lesser extent of D4 receptor protein immunoreactivity perivascularly and associated with choroid epithelium. No D3 receptor protein immunoreactivity was found in rat choroid plexus. 5 The above results indicate that rat choroid plexus expresses dopamine receptor protein, being dopamine D1‐like receptors predominant in epithelium and arterial smooth muscle and D2‐like receptors in sympathetic nerve fibres supplying choroid plexus epithelium and vasculature. 6 These findings suggests that dopamine receptors with a different anatomical localization may modulate production of cerebrospinal fluid.
The minor population of M3‐receptors mediate contraction of human detrusor muscle in vitro
Authors: Chess‐Williams R. , Chapple C. R. , Yamanishi T. , Yasuda K. , Sellers D. J. 
Published: March 2003

Summary 1 The objective was to determine the role of muscarinic receptor subtypes in mediating contraction of the human detrusor smooth muscle in vitro. 2 Contractile responses of human detrusor muscle strips to carbachol were obtained in the absence and presence of a range of muscarinic antagonists (pirenzepine, methoctramine, 4‐diphenylacetoxy‐N‐methyl piperidine methiodide (4‐DAMP), tropicamide, oxybutynin and tolterodine). Affinity estimates (pKB values) were calculated for the antagonists and correlated with values at the cloned muscarinic receptor subtypes quoted in the literature. 3 Pirenzepine, methoctramine and tropicamide drugs that have high affinities at M1, M2 and M4‐receptors, respectively, all had low affinities on the human detrusor (pKB values of 6.8, 6.9 and 6.5, respectively), whilst the M3‐selective antagonist 4‐DAMP had a high affinity (9.5). Schild plots for all four antagonists had slopes of unity indicating an action at a single receptor. Oxybutynin and tolterodine also acted as competitive antagonists with affinity estimates of 7.6 and 8.1, respectively. 4 When the antagonist affinities obtained on the bladder were plotted against the values published for these antagonists at the cloned muscarinic receptor subtypes, the best correlations were obtained for the m3‐ and m5‐muscarinic receptor subtypes. 5 These data suggest that direct contractile responses of the human detrusor muscle to muscarinic receptor stimulation in vitro are mediated solely via the M3‐muscarinic receptor subtype with no contribution from the major M2‐receptor population.
The origin of present forest composition and pattern in southern Sweden
Authors: Lindbladh Matts , Bradshaw Richard 
Published: March 2003

Abstract. Deciduous forests in much of southern Sweden are often located on former ‘in‐field’ sites close to farms and villages. The more distant ‘out‐field’ sites are almost always dominated by conifers. Using palaeecological methods, we investigate the origin of this forest pattern at a small estate in Småland, southern Sweden that was the birthplace of Carl Linnaeus.Prior to extensive permanent settlement (c.ad 1100) both in‐fields and out‐fields supported a rich, mixed deciduous forest that was irregularly ravaged by forest fire. After ad 1100 the in‐field site was transformed into a species‐rich forest‐meadow system with tree composition similar to the pre‐cultural state with the addition of Fagus sylvatica L. The out‐field sites were used for grazing and slash‐and‐burn agriculture, but nevertheless maintained a high degree of forest continuity. Forest composition however changed from deciduous to coniferous dominance. Floristic diversity is closely linked to human activity. Herbaceous diversity is greatest during the earliest phase of the forest‐meadow system. It declines during the late‐mediaeval agrarian crisis and again during the over‐exploitation of the late nineteenth century. Diversity returns to pre‐cultural levels after the abandonment of the forest‐meadow system during the present century. Present forest composition and pattern in the study area are closely related to former human activities and are not primarily a function of soil type or present‐day management.
Integrated palaeoecological evidence for biodiversity at the floodplain‐forest margin
Authors: Brayshay Barbara A. , Dinnin Mark 
Published: March 2003

SummaryThis paper presents the results of a combined palynological and palaeoentomological investigation into the changing diversity of Holocene floodplain forest biota at Bole Ings in the lower reaches of the River Trent. The aim in combining the two techniques represents an attempt to overcome some of the inherent differences of scale and resolution which characterize different types of fossil species data. The two lines of ecofactual evidence, pollen and beetle remains indicate changes in the biodiversity of the floodplain, both in terms of the diversity and abundance of individual species, habitats and ecosystem structure. The results of the study demonstrate the potential of this approach in tracing the decline in plant and entomofaunal diversity at the floodplain forest margin. Although there are recognized limitations imposed by taphonomic uncertainties, taxonomic resolution and restricted ecological data, the combined results provide added details of variations in both species composition and structural diversity within the landscape. The results emphasize the need for multidisciplinary research design in palaeoecological investigations of biodiversity.
Surface pollen‐vegetation relationships on the Atlantic seaboard: South Uist, Scotland
Authors: Brayshay Barbara A. , Gilbertson David D. , Kent* Martin , Edwards Kevin J. , Wathern Peter , Weaver Ruth E. 
Published: March 2003

AbstractStudies of modern pollen rain from remote islands have raised a number of interesting issues concerning the spatial precision of present‐day pollen spectra in relation to their parent plant community types. This paper examines the relationships and degree of correlation between a sequence of contemporary vegetation types, environments and their associated surface pollen spectra from a transect across the island of South Uist in the Outer Hebrides of Scotland. Paired data on both contemporary vegetation and associated surface pollen assemblages have been collected and analysed using methods of numerical classification and ordination. In general terms, the modern pollen rain on South Uist reflects the major changes in vegetation pattern and the major community types fairly closely. The major boundary between the alkaline machair sand dune communities and the various acidic upland vegetation types is particularly clear. However, both variability in the vegetation and the effects of the strong prevailing westerly and south‐westerly winds tend to blur the boundaries of the various communities within each of these larger categories. On average 86.6% of the palynomorphs come from in‐community quadrat sources, while only 1.3% are from off‐island sources. The limited present‐day tree distribution on the transect is discussed in the context of the more widespread distribution of arboreal pollen. Overall, there is a strong numerical correspondence between vegetation, pollen and environmental variables. The various problems inherent in examining surface pollen spectra are reviewed.
Isozyme variation and recent biogeographical history of the long‐lived conifer Fitzroya cupressoides
Authors: Premoli A. C. , Kitzberger T. , Veblen T. T. 
Published: March 2003

AbstractAim Palaeoenvironmental records of Pleistocene glaciation and associated vegetation changes in Patagonia have led to the hypothesis that during the last glacial maximum (LGM) tree species survived locally in favourable habitats. If present populations originated from spread from only one refugium, such as an ice‐free area of coastal Chile (Single Refugium hypothesis), we would expect that eastern populations would be genetically depauperate and highly similar to western populations. In contrast, if the ice cap was not complete and tree species persisted in forest patches on both slopes of the Andes (Multiple Refugia hypothesis), we would expect a greater degree of genetic divergence between populations either on opposite sides of the Cordillera (Cordillera Effect scenario) or towards its present‐day southern distributional limit where the ice sheet reached its maximum coverage (Extent‐of‐the‐Ice scenario).Location We tested this refugia hypothesis using patterns of isozyme variation in populations sampled over the entire modern range of the endemic conifer Fitzroya cupressoides (Mol.) Johnst. (Cupressaceae) in temperate South America.Methods Fresh foliage was collected from twenty‐four populations and analysed by horizontal electrophoresis on starch gels.Results Twenty‐one putative loci were reliably scored and 52% were polymorphic in at least one population. Populations from the eastern slope of the Andes were genetically more variable than those from the western slope; the former had a greater mean number of alleles per locus, a larger total number of alleles and rare alleles, and higher polymorphism. Genetic identities within western populations were greater than within eastern populations. Discriminant analyses using allelic frequencies of different grouping schedules of populations were non significant when testing for the Single Refugium hypothesis whereas significant results were obtained for the Multiple Refugia hypothesis.Main conclusions Our results indicate that present Fitzroya populations are the result of spreading from at least two, but possibly more, glacial refugia located in Coastal Chile and on the southern flanks of the Andes in Argentina.
Using habitat models to map diversity: pan‐African species richness of ticks (Acari: Ixodida)
Authors: Cumming Graeme S. 
Published: March 2003

AbstractAims To show how logistic regression models for individual species can be used to produce improved estimates of species richness at a continental scale; to present these data for African ticks (Acari: Ixodida); and to address the question of whether there is a latitudinal gradient in tick species richness.Location Africa.Methods A database of 34,060 collection records for African ticks is used to produce a pan‐African map of known tick species richness at 0.25 × 0.25‐degree resolution. The likely distributions of seventy‐three species are then estimated from environmental factors using logistic regression, and localities where there is a suitably high probability of occurrence for a given species are added to the original data for that species. These augmented data are combined to produce a map of the predicted pan‐African distribution of tick species richness. The relationship of species richness to latitude is considered along a transect placed across some of the more extensively collected areas.Results Maps of known and predicted pan‐African tick species richness are presented, and deficiencies in the available data are highlighted. Correlations using both known and predicted estimates of tick species richness suggest that ticks follow similar species richness patterns to those described for African mammals and birds, with a latitudinal gradient and highest species richness in east equatorial Africa. Tick species ranges are log‐normally distributed.Main conclusions Carefully constructed probability surfaces offer a more powerful approach to mapping species ranges than simple presence‐absence maps. Such models are a useful extension to current biogeographical methods and have a wide range of potential applications in ecology, epidemiology and conservation. Tick species richness at a continental scale follows similar trends to those reported for mammals and birds.
A bioclimatic model for the distribution of Sphagnum‐dominated peatlands in North America under present climatic conditions
Authors: Gignac L. D. , Halsey L. A. , Vitt D. H. 
Published: March 2003

AbstractAimA model was developed that estimates the climatic and geographical distribution of Sphagnum‐dominated peatlands in western Canada and North America.LocationThe model is based on the abundance of Sphagnum species on 640 peatland sites located in proximity to permanent weather stations throughout western Canada.MethodsThe per cent cover of Sphagnum species was quantified for all possible combinations of mean annual temperature (MAT) and mean annual total precipitation (MATP) found in western Canada. Abundance values were expanded to include all climatic values in North America, by interpolating within the matrix of values for western Canada using distance‐weighted means. Because Sphagnum‐dominated peatlands do not occur in areas having summer moisture index (P–PET) values ≤ 6 cm, that value was also included in the model. The result produced a matrix of 3360 grid nodes in which each node was characterized by MAT, MATP and P–PET values and the presence of Sphagnum‐dominated peatlands. The climatic data in the model was then match merged with the MAT, MATP and P–PET values obtained from Leemans & Cramer (The IIASA Database for Mean Monthly Values of Temperature, Precipitation, and Cloudiness on a Global Terrestrial Grid. International Institute for Systems Analysis, Laxenberg, 1991), which is a global data set that also contains geographical data on a 0.5° latitude by longitude grid. The geographical distribution of Sphagnum‐dominated peatlands was then mapped for western Canada and North America. Those maps were compared with the observed distribution of bogs and poor fens for the same area.ResultsResults of the comparisons indicated that the model's estimations matched the southern distribution of Sphagnum‐dominated peatlands relatively closely. Results for the northern distribution, however, were not as accurate. The overall accuracy was c. 80%.Main conclusionsSome of the errors were caused by inaccurate climatic data which resulted from the lack of permanent weather stations in northern areas and the lack of definition of the northern limits of the actual distribution of bogs and poor fens. In areas where both the climatic data and the actual distribution of Sphagnum‐dominated peatlands are accurate, the model accuracy was c. 90%.
Ecological and biogeographical implications of Yellow‐Legged Gulls (Larus cachinnans Pallas) as seed dispersers of Rubia fruticosa Ait. (Rubiaceae) in the Canary Islands
Authors: Nogales Manuel , Medina Félix M. , Quilis Vicente , González‐Rodríguez Mercedes 
Published: March 2003

AimFew data sets exist on the role of gulls as seed dispersal agents. Our purpose is to quantify the number of seeds dispersed, to assess damage to the seeds regurgitated and those expelled via cloaca, to check for possible differences in seed viability and germination rates, to study the seed retention time, and to evaluate gulls as adequate dispersal agents throughout the Canary Islands and for the colonization of this archipelago by this plant species (or its ancestor), from Africa.LocationThis study was developed in ‘Los Islotes’, a small archipelago located off the northern part of Lanzarote Island (Canaries).MethodsWe counted the number of seeds in each pellet and dropping collected and we measured and weighed them. Seed viability and germination from the three treatments (plants, pellets and droppings) were studied. Gut pass time (GPT) was assessed in two gulls by using glass beads (similar in size with Rubia fruticosa Ait. seeds). We employed a combination of univariate and bivariate statistical tests to analyse the data.ResultsFrom 81 pellets and 84 droppings, we extracted a total of 60,679 seeds (48,460 and 12,219, respectively). Data obtained in the GPT experiments show that a similar number of seeds are defecated and regurgitated. No externally damaged seed was observed and the majority were viable, giving more than 95% in all treatments (seeds from plants, droppings and pellets). Most seeds on these treatments showed germination rates of over 80%, verifying the importance of the gulls as legitimate dispersers of this Macaronesian endemic plant species. Taking into account that the gulls’ flight cruise speed is about 31–40 km h–1 and mean GPT of these birds is between 9.51 and 16.92 h, they could cover a distance between 295 and 677 km before expelling the seeds. This distance is well within the range of colonization of the different islands of the Canaries and the neighbouring archipelagos of Salvages and Madeira from the north‐west of Africa, where the ancestor of this plant may have originated.Main conclusionsThe results support the idea that gulls could have been one of the main agents responsible for the movement of R. fruticosa seeds among the islands of the Canaries and for the colonization of the Macaronesian archipelagos from Africa. Furthermore, this study suggests that gulls are generalist feeding seabirds with high capacity for seed transport and high long‐distance power displacements, could have played a more important role than that currently recognized by most authors, in the colonization of oceanic islands by some plants whose genetic origins were located at long‐distances.
Factors affecting the distribution of vascular plants, springtails, butterflies and birds on small tropical islands
Authors: Koh Lian Pin , Sodhi Navjot S. , Tan Hugh Tiang Wah , Peh Kelvin S.‐H. 
Published: March 2003

AimThe primary objective of our study was to examine the factors affecting the distribution of vascular plants, springtails, butterflies and birds on small tropical islands to understand how different groups of organisms with distinct biological traits respond to biogeographical variables, such as island area.LocationThe Republic of Singapore (103°50′E, 1°20′N) located at the southern tip of Peninsular Malaysia.MethodsSeventeen islands were surveyed for vascular plants, springtails, butterflies and birds. Correlation analysis, simple linear and multiple regression analyses and the nestedness index were used to test the hypotheses that (1) area is the best predictor of species/genus richness at both the community and specific/generic levels; (2) there is no correlation between population density and island area; and (3) species/genera are distributed as nested subsets.ResultsArea was the most significant factor in determining the island distribution of springtails, butterflies and birds at both the community and specific/generic levels, although there were disparate responses to the biogeographical variables between the three taxonomic groups, as well as between common species within each group. Individual species displayed disparate responses to biogeographical variables, suggesting that patterns of distribution at the community level may not be a good indicator of the population dynamics of individual species/genera. Plant species richness did not show any correlation with any of the tested variables. Population densities of springtails, butterflies and birds were positively correlated with area, contradicting the assumption of the equilibrium theory of island biogeography that population density of island species is independent of area. Population densities of plants showed no correlation with any of the tested biogeographical variables. Vascular plant, springtail, butterfly and bird communities on the islands showed significant patterns of nestedness, indicating there may be species/genus‐specific responses to biogeographical variables.Main conclusionsWe conclude that although area was the most important factor affecting the island distribution of springtails, butterflies and birds, conservation planning must take into consideration how target taxonomic groups respond to biogeographical variables, instead of relying on general principles (e.g. those derived from the equilibrium theory). On a local scale, in order to preserve the island biodiversity of Singapore, the highest priority should be given to preserving the larger islands (e.g. Pulau Ubin) which not only have higher numbers of species, but also species that are absent on smaller islands.