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  • Blackwell Science Ltd  (9)
  • Copernicus  (4)
  • 2000-2004  (13)
  • 2003  (13)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of adult pheromones on the avoidance of suspended sediment by migratory banded kokopu juveniles (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: Migratory banded kokopu Galaxias fasciatus juveniles exhibited an attraction to adult odours and an avoidance towards suspended sediment with a turbidity of 25 nephelometric turbidity units (NTU) in a two-choice chamber apparatus. When the adult odours were mixed with suspended sediment at a turbidity of 25 or 35 NTU, an attraction towards the odour and suspended sediment chamber resulted. When adult odours were paired with turbid water at 50 NTU, juveniles would avoid the odour and suspended sediment chamber. These results demonstrate adult pheromones can increase the threshold for an avoidance response to suspended sediment in banded kokopu juveniles. This provides supporting evidence that odours released by adult conspecifics may provide an important migratory cue for juveniles in stream and habitat selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1095-8649.2003.00029.x
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  • 2
    Electronic Resource
    Electronic Resource
    Human milk lactoferrin is a serine protease that cleaves Haemophilus surface proteins at arginine-rich sites (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 47 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Lactoferrin is a member of the lactotransferrin family of non-haem, iron-binding glycoproteins and is found at high concentrations in all human secretions, where it plays a major role in mucosal defence. In recent work, we observed that lactoferrin has proteolytic activity and attenuates the pathogenic potential of Haemophilus influenzae by cleaving and removing two putative colonization factors, namely the IgA1 protease protein and the Hap adhesin. Experiments with protease inhibitors further suggested that lactoferrin may belong to a serine protease family. In the present study we explored the mechanism of lactoferrin protease activity and discovered that mutation of either Ser259 or Lys73 results in a dramatic decrease in proteolysis. Examination of the crystal structure revealed that these two residues are located in the N-terminal lobe of the protein, adjacent to a 12–15 Å cleft that separates the N-lobe and the C-lobe and that can readily accommodate large polypeptide substrates. In additional work, we found that lactoferrin cleaves IgA1 protease at an arginine-rich region defined by amino acids 1379–1386 (RRSRRSVR) and digests Hap at an arginine-rich sequence between amino acids 1016 and 1023 (VRSRRAAR). Based on our results, we conclude that lactoferrin is a serine protease capable of cleaving arginine-rich sequences. We speculate that Ser259 and Lys73 form a catalytic dyad, reminiscent of a number of bacterial serine proteases. In addition, we speculate that lactoferrin may cleave arginine-rich sequences in a variety of microbial virulence proteins, contributing to its long-recognized antimicrobial properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03327.x
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  • 3
    Electronic Resource
    Electronic Resource
    Ectopic RNase E sites promote bypass of 5′-end-dependent mRNA decay in Escherichia coli (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 47 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In Escherichia coli, 5′-terminal stem–loops form major impediments to mRNA decay, yet conditions that determine their effectiveness or the use of alternative decay pathway(s) are unclear. A synthetic 5′-terminal hairpin stabilizes the rpsT mRNA sixfold. This stabilization is dependent on efficient translational initiation and ribosome transit through at least two-thirds of the coding sequence past a major RNase E cleavage site in the rpsT mRNA. Insertion of a 12–15 residue ‘ectopic’ RNase E cleavage site from either the rne leader or 9S pre-rRNA into the 5′-non-coding region of the rpsT mRNA significantly reduces the stabilizing effect of the terminal stem–loop, dependent on RNase E. A similar insertion into the rpsT coding sequence is partially destabilizing. These findings demonstrate that RNase E can bypass an interaction with the 5′-terminus, and exploit an alternative ‘internal entry’ pathway. We propose a model for degradation of the rpsT mRNA, which explains the hierarchy of protection afforded by different 5′-termini, the use of internal entry for bypass of barriers to decay, ‘ectopic sites’ and the role of translating ribosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03292.x
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  • 4
    Electronic Resource
    Electronic Resource
    Coupled biogeochemical and hydrological responses of streams and rivers to drought (2003)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 48 (2003), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 〈list xml:id="l1" style="custom"〉1Severe or extreme droughts occurred about 10% of the time over a 105-year record from central New Mexico, U.S.A., based on the Palmer Drought Severity Index.2Drought lowers water tables, creating extensive areas of groundwater recharge and fragmenting reaches of streams and rivers. Deeper groundwater inputs predominate as sources of surface flows during drought. Nutrient inputs to streams and rivers reflect the biogeochemistry of regional ground waters with longer subsurface residence times.3Inputs of bioavailable dissolved organic carbon to surface waters decrease during drought, with labile carbon limitation of microbial metabolism a byproduct of drought conditions.4Decreased inputs of organic forms of carbon, nitrogen and phosphorus and a decrease in the organic : inorganic ratio of nutrient inputs favours autotrophs over heterotrophs during drought.5The fate of autotrophic production during drought will be strongly influenced by the structure of the aquatic food web within impacted sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2003.01082.x
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  • 5
    Electronic Resource
    Electronic Resource
    Simulated and observed fluxes of sensible and latent heat and CO2 at the WLEF-TV tower using SiB2.5 (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Three years of meteorological data collected at the WLEF-TV tower were used to drive a revised version of the Simple Biosphere (SiB 2.5) Model. Physiological properties and vegetation phenology were specified from satellite imagery. Simulated fluxes of heat, moisture, and carbon were compared to eddy covariance measurements taken onsite as a means of evaluating model performance on diurnal, synoptic, seasonal, and interannual time scales. The model was very successful in simulating variations of latent heat flux when compared to observations, slightly less so in the simulation of sensible heat flux. The model overestimated peak values of sensible heat flux on both monthly and diurnal scales. There was evidence that the differences between observed and simulated fluxes might be linked to wetlands near the WLEF tower, which were not present in the SiB simulation. The model overestimated the magnitude of the net ecosystem exchange of CO2 in both summer and winter. Mid-day maximum assimilation was well represented by the model, but late afternoon simulations showed excessive carbon uptake due to misrepresentation of within-canopy shading in the model. Interannual variability was not well simulated because only a single year of satellite imagery was used to parameterize the model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00671.x
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  • 6
    Electronic Resource
    Electronic Resource
    Simulated variations in atmospheric CO2 over a Wisconsin forest using a coupled ecosystem–atmosphere model (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Ecosystem fluxes of energy, water, and CO2 result in spatial and temporal variations in atmospheric properties. In principle, these variations can be used to quantify the fluxes through inverse modelling of atmospheric transport, and can improve the understanding of processes and falsifiability of models. We investigated the influence of ecosystem fluxes on atmospheric CO2 in the vicinity of the WLEF-TV tower in Wisconsin using an ecophysiological model (Simple Biosphere, SiB2) coupled to an atmospheric model (Regional Atmospheric Modelling System). Model parameters were specified from satellite imagery and soil texture data. In a companion paper, simulated fluxes in the immediate tower vicinity have been compared to eddy covariance fluxes measured at the tower, with meteorology specified from tower sensors. Results were encouraging with respect to the ability of the model to capture observed diurnal cycles of fluxes. Here, the effects of fluxes in the tower footprint were also investigated by coupling SiB2 to a high-resolution atmospheric simulation, so that the model physiology could affect the meteorological environment. These experiments were successful in reproducing observed fluxes and concentration gradients during the day and at night, but revealed problems during transitions at sunrise and sunset that appear to be related to the canopy radiation parameterization in SiB2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00613.x
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  • 7
    Electronic Resource
    Electronic Resource
    Reproductive ecology of the nine-spined stickleback from south-central Alaska (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of fish biology 63 (2003), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The life cycle of the nine-spined stickleback Pungitius pungitius from Airolo Lake, Alaska, was studied using samples taken during 1993–1994 and 1997–1998. Pungitius pungitius was actively reproducing in late May and ceased reproductive activities by late June. Spawning adults were 2+ years old. Contrary to an earlier report, the data indicate that an individual female oviposits all of her ovulated eggs (i.e. an entire clutch) into a male's nest during one spawning episode. There was a trade-off between clutch size and egg size without concomitant variation in clutch mass between two years. The results are compared to those from other studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1095-8649.2003.00232.x
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  • 8
    Electronic Resource
    Electronic Resource
    A translocated protein tyrosine phosphatase of Pseudomonas syringae pv. tomato DC3000 modulates plant defence response to infection (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 49 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Pseudomonas syringae strains translocate effector proteins into host cells via the hrp-encoded type III protein secretion system (TTSS) to facilitate pathogenesis in susceptible plants. However, the mechanisms by which pathogenesis is favoured by these effectors are not well understood. Individual strains express multiple effectors with apparently distinct activities that are co-ordinately regulated by the alternative sigma factor HrpL. Genes for several effectors were identified in the P. syringae pv. tomato DC3000 genome using a promoter trap assay to identify HrpL-dependent promoters. In addition to orthologues of avrPphE and hrpW, an unusual allele of avrPphD was detected that carried an IS52 insertion. Using this avrPphD::IS52 allele as a probe, a wild-type allele of avrPphD, hopPtoD1, and a chimeric homologue were identified in the DC3000 genome. This chimeric homologue, identified as HopPtoD2 in the annotated DC3000 genome, consisted of an amino terminal secretion domain similar to that of AvrPphD fused to a potential protein tyrosine phosphatase domain. Culture filtrates of strains expressing HopPtoD2 were able to dephosphorylate pNPP and two phosphotyrosine peptides. HopPtoD2 was shown to be translocated into Arabidopsis thaliana cells via the hrp-encoded TTSS. A ΔhopPtoD2 mutant of DC3000 exhibited strongly reduced virulence in Arabidopsis thaliana. Ectopic expression of hopPtoD2 in P. syringae Psy61 that lacks a native hopPtoD2 orthologue delayed the development of several defence-associated responses including programmed cell death, active oxygen production and transcription of the pathogenesis-related gene PR1. The results indicate that HopPtoD2 is a translocated effector with protein tyrosine phosphatase activity that modulates plant defence responses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03616.x
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  • 9
    Electronic Resource
    Electronic Resource
    C-terminal domain mutations in ClpX uncouple substrate binding from an engagement step required for unfolding (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 48 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: ClpX mediates ATP-dependent denaturation of specific target proteins and disassembly of protein complexes. Like other AAA + family members, ClpX contains an αβ ATPase domain and an α-helical C-terminal domain. ClpX proteins with mutations in the C-terminal domain were constructed and screened for disassembly activity in vivo. Seven mutant enzymes with defective phenotypes were purified and characterized. Three of these proteins (L381K, D382K and Y385A) had low activity in disassembly or unfolding assays in vitro. In contrast to wild-type ClpX, substrate binding to these mutants inhibited ATP hydrolysis instead of increasing it. These mutants appear to be defective in a reaction step that engages bound substrate proteins and is required both for enhancement of ATP hydrolysis and for unfolding/disassembly. Some of these side chains form part of the interface between the C-terminal domain of one ClpX subunit and the ATPase domain of an adjacent subunit in the hexamer and appear to be required for communication between adjacent nucleotide binding sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03424.x
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  • 10
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    Comment on evidence for surface-initiated homogeneous nucleation (2003)
    Copernicus
    Details
    Publication Date: 2003-09-22
    Description: We investigate theoretical, laboratory, and atmospheric evidence for a recently proposed hypothesis: homogeneous ice nucleation initiates at the surface, not in the volume, of supercooled water drops. Using existing thermodynamic arguments, laboratory experiments, and atmospheric data, we conclude that ice embryo formation at the surface cannot be confirmed or disregarded. Ice nucleation rates measured as a function of drop size in an air ambient could help distinguish between volume and surface nucleation rates.
    Print ISSN: 1680-7316
    Electronic ISSN: 1680-7324
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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