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  • 11
    Electronic Resource
    Electronic Resource
    Differential Effects of Interleukin-12 and Interleukin-10 on Superantigen-Induced Expression of Cutaneous Lymphocyte-Associated Antigen and αEβ7 Integrin (CD103) by CD8+ T cells (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc.
    Scandinavian journal of immunology 59 (2004), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The interaction with adhesion molecules expressed by vascular endothelium is the first step in lymphocyte infiltration into tissues. At both cutaneous and mucosal sites interleukin-10 (IL-10), IL-12 and transforming growth factor (TGF)-β are important regulators of chronic inflammatory disease, where cutaneous lymphocyte-associated antigen (CLA) and αE integrin (CD103) may be expressed. Unlike CLA, CD103 is not believed to play a role in tissue-specific homing but may help to retain T cells within epithelial layers. We have previously shown that IL-12 alone can together with an unknown cofactor increase the expression of CLA. Stimulation with streptococcal pyrogenic exotoxin C (SpeC) increased the expression of CD103 by CD8+ but not CD4+ T cells. While IL-12 increased superantigen-stimulated expression of CLA, this cytokine strongly inhibited the CD103 expression, and a combination of IL-12 and TGF-β completely abrogated the induced CD103 expression. Conversely, IL-10 suppressed CLA but increased CD103 expression.These findings indicate that, in addition to suppressing the development of Th1-mediated inflammatory responses, IL-10 may also inhibit the migration of CD8+ T cells into the skin while IL-12 promotes such migration. Thus, the expression of CLA and CD103 may be antagonistically regulated by IL-10 and IL-12, and the balance between these cytokines could influence the T-cell migration of inflammatory cells into epithelial tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0300-9475.2004.01423ab.x
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  • 12
    Electronic Resource
    Electronic Resource
    Accumulation and subcellular distribution of cations in relation to the growth of potassium-deficient barley (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Growth of barley (Hordeum vulgare L., cv. Georgie) was insensitive to soil K content above about 150 mg kg−1, but at lower levels it declined. The reduction in yield was greater in soils containing approximately 10 mg Na kg−1 than in soils with about 90 mg kg−1 of Na. Growth was unaffected by changes in shoot K concentration above 75 mol m−3, but declined at lower concentrations, and the decrease was less in plants grown in soils with high Na. Growth responses were not simply related to tissue K concentrations because plants grown in soils with extra Na had higher yields but lower K concentrations.When soil Na was low, plants accumulated Ca as tissue K declined, but when Na was provided this ion was accumulated. Plant Mg concentrations were generally low but increased as K decreased. The Ca and Mg were osmotically active. There were highly significant inverse linear relationships between yield and either the Ca or Mg concentrations in the shoots.X-ray microanalysis was used to examine the compartmentation of cations in leaves from barley plants (cv. Clipper) grown in nutrient solutions with high and low K concentrations. In plants grown with 2.5 mol m−3 K, this was the major cation in both the cytoplasm and vacuole of mesophyll cells. However, in plants grown with 0.02 mol m−3 K it declined to undetectable levels in the vacuole, although it was still detectable in the cytoplasm. In all plants, Ca was mainly located in epidermal cells. The implication of the results for explaining responses to K. in terms of compartmentation of solutes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11616346
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  • 13
    Electronic Resource
    Electronic Resource
    Uptake of CO2 by aquatic vegetation (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 8 (1985), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Photosynthesis by aquatic plants based on the supply of CO2 from air-equilibrated solutions may be limited by the low diffusion coefficient of CO2 in water. For plants in which the transport of CO2 from the bulk medium is by diffusion, and the initial carboxylation uses RUBISCO, CO2 supply can be increased by growth in habitats with fast water flow over the surface (reducing unstirred layer thickness), or with heterotrophically-augmented CO2 levels, including the direct use of sediment CO2. Many aquatic plants using RUBISCO as their initial carboxylase counter the limitations on CO2 supply via the operation of biophysical CO2 concentrating mechanisms which are based on active transport of HCO−3, CO2 or H+ at the plasmalemma, and use bulk-phase HCO−3 or CO2 as the C source. A final group of aquatic plants use biochemical CO2 concentrating mechanisms based on auxiliary carboxylation by PEPc: C4-like and Crassulacean Acid Metabolism–like processes are involved. These various mechanisms for increasing CO2 supply to RUBISCO also help to offset the low specific reaction rate of aquatic plant RUBISCOs at low [CO2] and low [CO2]: [CO2]. In addition to overcoming restrictions on CO2 supply, the various methods of increasing inorganic C availability may also be important in alleviating shortages of nitrogen or photons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1985.tb01677.x
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  • 14
    Electronic Resource
    Electronic Resource
    The utilization of bicarbonate ions by the macroalga Ascophyllum nodosum (L.) Le Jolis (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A comparison of some of the methods used to determine whether aquatic plants have the ability to utilize bicarbonate ions as a source of inorganic carbon for photosynthesis has been applied to the intertidal macroalga Ascophyllum nodosum. These include: observing photosynthesis at a high pH (below the alga's CO2 compensation point), pH compensation point determinations, comparing the photosynthetic characteristics at low pH (5.20) and at high pH (7.95), estimating the maximal rates at which CO2 can diffuse through the unstirred layer and the rate at which CO2 can be produced from bicarbonate dehydration in the unstirred layer. All indicated that Ascophyllum nodosum can use bicarbonate ions for photosynthesis, though some were not always consistent. Calculating the total inorganic carbon concentration from pH measurements and acidification CO2 determinations revealed that the assumption that the alkalinity remains constant during pH drift experiments is not always valid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11611615
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  • 15
    Electronic Resource
    Electronic Resource
    Peripheral Blood T-Cell Responses to Keratin Peptides that Share Sequences with M Proteins are Largely Restricted to Skin-Homing CD8+ T Cells (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc.
    Scandinavian journal of immunology 59 (2004), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The association of psoriasis with throat infections by streptococcus pyogenes suggests a potential antigenic target for the T cells that are known to infiltrate dermis and epidermis of psoriatic skin. Streptococcal M protein shares an extensive sequence homology with human epidermal keratins. Keratins 16 (K16) and 17 (K17) are mostly absent from uninvolved skin but are upregulated in psoriatic lesions. There is increasing evidence that CD8+ T cells play an important effector role in psoriasis and M protein-primed T cells may recognize these shared epitopes in skin via molecular mimicry. To identify candidate epitopes, peptides with sequences from K17 were selected on the basis of predicted binding to HLA-Cw6 and sequence similarities with M6 protein. Matched peptides from the sequence of M6 protein and a set of peptides with poor predicted binding were also selected. Cw6+ individuals with psoriasis and Cw6+ healthy controls, having a family history of psoriasis, were recruited. PBMCs were incubated with the peptide antigens. T-cell activation in the CD4+, CD8+ and later the skin-homing cutaneous lymphocyte-associated antigen (CLA)-expressing subset of CD8+ T cells was evaluated by CD69 expression and intracellular IFN-γ accumulation using flow cytometry. We demonstrate that Cw6+ psoriasis patients had significant CD8+ T-cell IFN-γ responses to peptides from K17 and M6 protein selected on the basis of sequence homology and predicted HLA-Cw*0602 binding. These responses were about 10 times more frequent in the skin-homing cutaneous lymphocyte-associated antigen-expressing (CLA+) subset of CD8+ T cells. CD4+ T cells showed only borderline responses. CD8+ T cells from Cw6 + nonpsoriatic individuals responded to some M6 peptides but very rarely to K17 peptides, and this also applied to the CLA+CD8+ subset. These findings indicate that psoriatic individuals have CD8+ T cells that recognize keratin self-antigens and that epitopes shared by streptococcal M protein and human keratin may be targets for the CD8+ T cells that infiltrate psoriatic skin lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0300-9475.2004.01423f.x
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  • 16
    Electronic Resource
    Electronic Resource
    APP is required during an early phase of memory formation (2000)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The amyloid β/A4 protein precursor (APP) has been shown to be implicated in age-associated plastic changes at synapses that might contribute to memory loss in Alzheimer's disease. As APP has previously been reported to have multiple functions during normal development, we have employed a one-trial passive avoidance task in day-old chicks to study its role in the process of memory formation. Administration of anti-APP antibodies, injected 30 min pretraining, prevented memory for a one-trial passive avoidance task in day-old chicks without effects on general behaviour or initial acquisition. Amnesia was apparent by 30 min post-training and lasted for at least 24 h. The same result was obtained by down-regulation of APP expression by APP-antisense, injected 8–12 h pretraining. However, injections of anti-APP antibodies or APP antisense at later post-training time did not cause amnesia for the task. Unlike antibodies and antisense, injection of the APP328–332 pentapeptide, in either orientation, 30 min pretraining, rescued the memory and prevented antisense-induced amnesia. The post-training time within which the antibody- and antisense-induced amnesia, and within which the APP peptides prevent amnesia, correspond to that during which memory formation is vulnerable to disruption of the putative signal transduction functions of APP. These results suggest that: (i) APP is required during an early phase of memory formation, and (ii) the memory enhancing effect of secretory APP is localized within a 5-mer sequence of growth-promoting domain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2000.01344.x
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  • 17
    Electronic Resource
    Electronic Resource
    Solute-binding protein-dependent ABC transporters are responsible for solute efflux in addition to solute uptake (2001)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 40 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The ATP-binding cassette (ABC) transporter superfamily is one of the most widespread of all gene families and currently has in excess of 1100 members in organisms ranging from the Archaea to man. The movement of the diverse solutes of ABC transporters has been accepted as being strictly unidirectional, with recent models indicating that they are irreversible. However, contrary to this paradigm, we show that three solute-binding protein-dependent (SBP) ABC transporters of amino acids, i.e. the general amino acid permease (Aap) and the branched-chain amino acid permease (Bra) of Rhizobium leguminosarum and the histidine permease (His) of Salmonella typhimurium, are bidirectional, being responsible for efflux in addition to the uptake of solutes. The net solute movement measured for an ABC transporter depends on the rates of uptake and efflux, which are independent; a plateau is reached when both are saturated. SBP ABC transporters promote active uptake because, although the Vmax values for uptake and efflux are not significantly different, there is a 103−104 higher affinity for uptake of solute compared with efflux. Therefore, the SBP ABC transporters are able to support a substantial concentration gradient and provide a net uptake of solutes into bacterial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02497.x
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  • 18
    Electronic Resource
    Electronic Resource
    The vbs genes that direct synthesis of the siderophore vicibactin in Rhizobium leguminosarum: their expression in other genera requires ECF σ factor RpoI (2002)
    Oxford, UK : Blackwell Science Ltd.
    Molecular microbiology 44 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A cluster of eight genes, vbsGSO, vbsADL, vbsC and vbsP, are involved in the synthesis of vicibactin, a cyclic, trihydroxamate siderophore made by the symbiotic bacterium Rhizobium leguminosarum. None of these vbs genes was required for symbiotic N2 fixation on peas or Vicia. Transcription of vbsC, vbsGSO and vbsADL (but not vbsP) was enhanced by growth in low levels of Fe. Transcription of vbsGSO and vbsADL, but not vbsP or vbsC, required the closely linked gene rpoI, which encodes an ECF σ factor of RNA polymerase. Transfer of the cloned vbs genes, plus rpoI, to Rhodobacter, Paracoccus and Sinorhizobium conferred the ability to make vicibactin on these other genera. We present a biochemical genetic model of vicibactin synthesis, which accommodates the phenotypes of different vbs mutants and the homologies of the vbs gene products. In this model, VbsS, which is similar to many non-ribosomal peptide synthetase multienzymes, has a central role. It is proposed that VbsS activates L-N5-hydroxyornithine via covalent attachment as an acyl thioester to a peptidyl carrier protein domain. Subsequent VbsA-catalysed acylation of the hydroxyornithine, followed by VbsL-mediated epimerization and acetylation catalysed by VbsC, yields the vicibactin subunit, which is then trimerized and cyclized by the thioesterase domain of VbsS to give the completed siderophore.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.02951.x
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  • 19
    Electronic Resource
    Electronic Resource
    Transcription of a Rhizobium ieguminosarum biovar phaseoli gene needed for melanin synthesis is activated by nifA of Rhizobium and Klebsiella pneumoniae (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 2 (1988), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Rhizobium leguminosarum biovar phaseoli symbiotic plasmid pRP2JI carries a gene, melA, specifying the enzyme tyrosinase, which is responsible for the production of the pigment melanin in these bacteria. Transcription of melA is activated by the nifA gene of Rhizobium and, when the cloned melA gene is transferred to Escherichia coli, melA is expressed if the recipients contain nifA gene of Klebsiella pneumoniae. This nifA-dependent activation was temperature sensitive and required the ntrA gene. The cloned nifA gene of K. pneumoniae, when transferred to a nifA mutant of Rhizobium phaseoli biovar phaseoli, corrected the Mer− but not the Fix− phenotype. nifA of R. leguminosarum biovar phaseoli activated melA at higher levels in cells grown in low concentrations of oxygen. Also, nifA of fl. leguminosarum biovar phaseoli activated nifH of K. pneumoniae in Escherichia coli cells grown In low-oxygen concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1988.tb00036.x
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  • 20
    Electronic Resource
    Electronic Resource
    Single and multiple mutations affecting properties of the regulatory gene nodD of Rhizobium (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 3 (1989), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: nodD of Rhizobium leguminosarum has two regulatory properties: it autoregulates and, in cells grown with specific flavonoids, activates other nod genes. We isolated mutations in nodD affecting one or both properties. Those abolishing autoregulation and nod gene induction were at the 5′ end of nodD, as were those which only affected autoregulation. Mutations affecting nod gene activation are at the 3’end of nodD. Eleven mutations in this region of nodD were isolated: some had little effect on the regulatory properties; others reduced activation of other nod genes. 265 bps were removed from the 3’end of nodD: this abolished nodD function. Doubly mutant derivatives of nodD were constructed by making nodD genes with a mutation that conferred the ability to activate transcription of nod genes in the absence of inducers (class IV) plus another that abolished autoregulation and/or flavonoid-dependent nod gene activation. The behaviour of such double mutants was complex; e.g. in one case, a doubly mutant nodD gene containing the class IV mutation, coupled to one of those that (alone) abolished autoregulation and nod gene induction, was similar in behaviour to the wild type. In other cases, double mutants were similar to one of the parentals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1989.tb00142.x
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