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  • 1
    Electronic Resource
    Electronic Resource
    Size-dependent microhabitat use and intraspecific competition in Cottus gobio (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 67 (2005), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An electrofishing survey of daytime shelter microhabitat use of bullhead Cottus gobio in a southern English chalk stream revealed positive selection for moderate water velocity, vegetation cover and coarse substrata. Water depth, other forms of cover, shade and substratum embeddedness had no significant influence on the distribution of fish. Microhabitat use was size-dependent, with patches occupied by adult fish containing coarser substrata and less blanket weed (Cladophora algae) than those occupied by smaller juvenile conspecifics. Differences in substratum use between size-classes were less pronounced in parts of the stream shaded by the tree canopy. In laboratory tanks stocked at low fish density, both juveniles and adults favoured use of cobbles over pebbles. The response of fish to increased conspecific density was size-dependent; juveniles reduced use of the coarse substratum whereas adults maintained their predominance in this habitat. An apparently greater shift by juveniles when in the presence of adults was significant at α = 0·10 only, as was an apparent reduction in interactions between size-classes under low light intensity. The displacement of small juvenile fish from the preferred cobble substratum is consistent with the hypothesis that intraspecific competition contributes to the size-related microhabitat shift observed in the field. Although there was a tendency for the strength of competition to be reduced at low light levels, the mechanism by which tree canopy cover affects microhabitat use remains uncertain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2005.00736.x
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  • 2
    Electronic Resource
    Electronic Resource
    Isotopic change throughout the life history of a Lake Malawi cichlid fish (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of fish biology 62 (2003), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Clear changes in body size-isotope (carbon and nitrogen) trajectories of Pseudotropheus callainos, a cichlid belonging to the endemic haplochromine species radiation in Lake Malawi, were found that corresponded with an ontogenetic dietary shift from predominantly planktonic to benthic food sources. The results indicated that dietary switching was a proximate cause of isotopic change over the life history of this species and confirmed the value of stable isotope signatures for inferring diet. The data also illustrated that possible variability of signatures over the life history of a species should be considered when using stable isotope ratios to investigate fine-scale ecological differentiation among taxa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1095-8649.2003.00085.x
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  • 3
    Electronic Resource
    Electronic Resource
    Polymorphisms in the interleukin-4 and IL-4 receptor genes and multiple sclerosis: a study in Spanish-Basque, Northern Irish and Belgian populations (2005)
    Oxford, UK : Blackwell Science Ltd
    International journal of immunogenetics 32 (2005), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Cytokine gene polymorphisms are known to influence susceptibility and disease course of many autoimmune diseases. Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system white matter characterized by inflammation, demyelination and axonal damage. We analysed both the well-known intronic variable number of tandem repeat (VNTR) and +33 C/T single-nucleotide polymorphisms (SNP) in the IL-4 gene, as well as the functional Q551R SNP in the IL4-R gene in a cohort of three distinct populations comprising sporadic cases and controls from the northern Spanish Basque Country and Northern Ireland, as well as family trios from Belgium. The IL-4 +33 TT genotype was decreased in primary progressive (PP) versus relapsing-remitting (RR) patients in the Northern Irish population (OR = 0.14; 95% CI = 0.018–1.09). Two-marker haplotype distribution of the VNTR and +33 C/T SNP in PP patients differed from that seen in RR patients in Northern Ireland (P = 0.03). The R allele of the Q551R SNP was significantly under-transmitted in the Belgian trio families (P = 0.003), although this effect was not seen in the Northern Irish and Basque data sets. We did not identify IL-4–IL4-R gene–gene interaction in determining susceptibility or clinical parameters of MS. Disease or genetic heterogeneity or both may be responsible for the observed lack of reproduction in different populations. Our data reinforce recent findings for a role of IL4-R in susceptibility to MS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.2005.00542.x
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  • 4
    Electronic Resource
    Electronic Resource
    Monitoring rocky-shore communities: a critical look at spatial and temporal variation (1980)
    Springer
    Helgoland marine research 33 (1980), S. 484-494 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Increasingly programmes are being set up to monitor rocky-shore communities in order to provide baseline data which will indicate changes resulting from subsequent pollution. However, these efforts are complicated by several factors. Firstly, there are overall changes in the composition of communities both within and between years. Secondly, there is variation within certain communities due to a mosaic distribution of components, the mosaic format changing continuously with a cycle of several years. This paper reports on studies of a medium-exposed rocky shore in the Isle of Man (U. K.). It describes patterns of spatial and temporal variation, and looks at certain implications for monitoring programmes: (a) the frequency of sampling, and the duration of the sampling programme, in the light of seasonal and long-term variation; (b) the efficiency, in terms of the minimisation of variability, of sampling the same area by different strategies — belt transects, small random quadrats, single large quadrat; (c) the effect of the distribution patterns of some commoner species on the variation between samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02414773
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of long-term physical disturbance by commercial scallop fishing on subtidal epifaunal assemblages and habitats (2000)
    Springer
    Marine biology 137 (2000), S. 325-337 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  This paper examines spatial differences in the distribution of by-catch assemblages from the scallop [Pecten maximus (L.) and Aequipecten opercularis (L.)] fishing grounds in the North Irish Sea, during 1995. The sites examined have been exposed to differing known levels of fishing disturbance by scallop dredging, based on unusually high-resolution data extracted from fishermens' logbooks. Uni- and multi-variate techniques have been used on a production dataset (a value which incorporates both abundance and biomass figures), as well as abundance and biomass data individually. The original species list was reduced to higher taxonomic groupings in line with the theory that the latter is more appropriate for detecting anthropogenic change. Species diversity and richness, total number of species, and total number of individuals all decrease significantly with increasing fishing effort. Species dominance increases with effort. Total abundance, biomass and production, and the production of most of the major individual taxa investigated decrease significantly with increasing effort. Multivariate analysis reveals a significant relationship between fishing effort and by-catch assemblage structure. The taxa most responsible for the differences are the echinoids and cnidarians, but prosobranch molluscs and crustaceans also contribute to the differences. By-catch assemblage structure is more closely related to fishing effort than any other environmental parameter investigated, including depth and sediment type. We observed an approximately linear decrease in diversity with increasing fishing disturbance, and suggest this is primarily due to selective removal of sensitive species and, more importantly, habitat homogenisation. These results were interpreted in the light of ecological theories relating disturbance to community structure. The argument that invertebrate scavenger populations benefit from prolonged exposure to fishing disturbance was also examined, but no supporting evidence was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270000357
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  • 6
    Electronic Resource
    Electronic Resource
    Genetic structure of populations of two species of Chthamalus (Crustacea: Cirripedia) in the north-east Atlantic and Mediterranean (1997)
    Springer
    Marine biology 128 (1997), S. 73-82 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protein electrophoresis on starch gels was used to investigate population genetic structure of the barnacles Chthamalus montagui Southward and C. stellatus (Poli) over their north-east Atlantic and Mediterranean ranges. In each species, a single locus exhibited marked differentiation of allele frequencies between Atlantic and Mediterranean localities; in C. stellatus, genetic differentiation between the two basins had not previously been noted. In both species, mean heterozygosity per locus appeared higher in the Mediterranean samples than in the Atlantic, and Mediterranean populations had more alleles at the loci studied. Possible explanations for the differentiation between the Atlantic and the Mediterranean populations are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050070
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  • 7
    Electronic Resource
    Electronic Resource
    A study of the structure of zinc polycarboxylate dental cements (1993)
    Springer
    Journal of materials science 4 (1993), S. 32-35 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Two examples of zinc polycarboxylate dental cement were studied, one of which was prepared from an aqueous solution of poly (acrylic acid) together with the zinc oxide powder, the other being prepared by adding water to a mixture of dried polyacid and zinc oxide powder. The changes in the properties of the resultant cements with length of storage in various media were determined. In all cases the maximum strength was achieved fairly rapidly, usually at 1 week, after which there was little or no increase. Cements stored in water achieved the lowest compressive strengths, whereas cements stored in highly desiccating conditions, over concentrated sulphuric acid, achieved very high (if variable) compressive strengths. There appeared to be very little difference between the water-activated and conventional cements. These results confirm previous findings that zinc polycarboxylate cements are relatively poorly hydrated compared with other polyelectrolyte biomaterials. This in turn implies that water does not play a structural role in these cements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122974
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  • 8
    Electronic Resource
    Electronic Resource
    Population differentiation and taxonomic status of the exploited limpet Patella candei in the Macaronesian islands (Azores, Madeira, Canaries) (1996)
    Springer
    Marine biology 125 (1996), S. 141-152 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There has been considerable confusion in the taxonomy of limpets of the North East Atlantic Ocean and Mediterranean Sea, particularly those from the Macaronesian islands. The present study compared populations of the intertidal limpet Patella candei d'Orbigny from the Azores, Madeira and the Canaries with those of P. caerulea Linnaeus and P. depressa Pennant from the European and African continental coasts. No major differences in radular morphology were detected between the three species. However, electrophoretic analysis of 15 enzyme loci gave overall genetic identity (I) values of ∼0.5 between the three species, indicating that they cannot be regarded as conspecific as previously thought, and suggesting that P. candei is endemic to the Macaronesian islands. Comparisons of P. candei within these islands showed that, although populations did not differ with respect to radular morphology and soft-body parts, populations from the Azores were distinct from those in Madeira and the Canaries in shell shape and gene frequencies. Individuals from the Azores had, no average, taller shells and longer radulae, while those in Madeira and the Canaries had a shallow, depressed and stellate shell form. This was interpreted as being due to the wider habitat distribution of the species in the Azores compared to Madeira and the Canaries. Electrophoretic results showed that P. candei from the Azores differed from P. candei in Madeira and the Canaries by almost 40% of the loci investigated (I=0.660), suggesting that the former is a separate endemic species. An I value of 0.969 between populations in Madeira and the Canaries was typical of conspecific populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350768
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  • 9
    Electronic Resource
    Electronic Resource
    Wound-induced lignin and suberin deposition in a woody angiosperm (Eucalyptus gunnii Hook.): Histochemistry of early changes in young plants (1996)
    Springer
    Protoplasma 191 (1996), S. 96-104 
    Details
    ISSN: 1615-6102
    Keywords: Eucalyptus ; Histochemistry ; Lignin ; Phenolics ; Suberin ; Wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A simple system was developed to investigate the deposition of lignin and synthesis occurring in response to mechanical wounding in the woody angiospermEucalyptus gunnii Hook. The spatiotemporal deposition of these phenolic polymers was histochemically characterized in stem tissue through a combination of fluorescent microscopy and specific stains. Lignin and suberin deposition was detectable 24 h post wounding in the “xylem wound zone” and by 3 days post wounding in the “bark wound zone” where a welldeveloped necrophylactic (wound) periderm could be observed by 7 days post wounding. Close examination suggests that the spatial reinforcement of cell walls with lignin and/or suberin is carefully orchestrated so as to rapidly produce an effective protective barrier. Specific lignin colour reactions indicate that the lignin formed in response to wounding in both the bark and xylem wound zones is relatively poor in syringyl monomers as compared to that of “developmental” xylem lignin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280829
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  • 10
    Electronic Resource
    Electronic Resource
    Feeding behaviour in Littorina littorea: a study of the effects of ingestive conditioning and previous dietary history on food preference and rates of consumption (1990)
    Springer
    Hydrobiologia 193 (1990), S. 191-198 
    Details
    ISSN: 1573-5117
    Keywords: feeding ; preference ; learning ; phagostimulant ; intertidal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding responses of the generalist herbivore, Littorina littorea (L.), to the perceived ‘taste’ of macroalgae were assessed with respect to the effects of recent dietary intake and to overlapping versus nonoverlapping distributions of winkles and algae. The extent of grazing on artificial substrates impregnated with crude algal extracts was used as a measure of rate of response to the odour of preferred algae, and of feeding preference among less preferred algae, in a variety of designs. Adult L. littorea collected from a site where a range of algae were present showed preference among extracts of fucoids, whereas adults from a nearby site showed no such preference. Juvenile L. littorea of two weight cohorts collected from the former site responded faster to Porphyra umbilicalis extract-containing substrate than similar-sized animals from the latter site. Juveniles, fed either Porphyra, Ulva lactuca, or starved for two weeks in the laboratory, responded similarly to Ulva versus Porphyra extracts in a dose-dependent manner across a range of concentrations, although the Porphyra-maintained group consumed more of each, and the starved group less over seven days. Juveniles maintained on a mixed diet of Ulva and Porphyra consumed more Porphyra extract and less Ulva extract over the same period. These results are discussed in relation to the possible role of ingestive conditioning and previous dietary history in determining the occurrence and extent of chemically-mediated feeding preference in L. littorea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028076
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