bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of the arginine repressor in lysine biosynthesis of Thermus thermophilus
Authors: Fujiwara Kei , Tsubouchi Taishi , Kuzuyama Tomohisa , Nishiyama Makoto
Published: December 2006

Lysine biosynthesis of Thermus thermophilus proceeds in a similar way to arginine biosynthesis, and some lysine biosynthetic enzymes from T. thermophilus so far investigated have the potential to function in arginine biosynthesis. These observations suggest that arginine might regulate the expression of genes for lysine biosynthesis. To test this hypothesis, the argR gene encoding the regulator of arginine biosynthesis was cloned from T. thermophilus and its function in lysine biosynthesis was analysed. The addition of arginine to the culture medium inhibited the growth of an arginase gene knockout mutant of T. thermophilus, which presumably accumulates arginine inside the cells. Arginine-dependent growth inhibition was not alleviated by the addition of ornithine, which is a biosynthetic intermediate of arginine and serves as a peptidoglycan component of the cell wall in T. thermophilus. However, the growth inhibition was cancelled either by the simultaneous addition of lysine and ornithine or by a knockout of the argR gene, suggesting the involvement of argR in regulation of lysine biosynthesis in T. thermophilus. Electrophoretic mobility shift assay and DNase I footprinting revealed that the ArgR protein specifically binds to the promoter region of the major lysine biosynthetic gene cluster. Furthermore, an α-galactosidase reporter assay for this promoter indicated that arginine repressed the promoter in an argR-dependent manner. These results indicate that lysine biosynthesis is regulated by arginine in T. thermophilus.
Quorum sensing regulates dpsA and the oxidative stress response in Burkholderia pseudomallei
Authors: Lumjiaktase Putthapoom , Diggle Stephen P. , Loprasert Suvit , Tungpradabkul Sumalee , Daykin Mavis , Cámara Miguel , Williams Paul , Kunakorn Mongkol
Published: December 2006

Burkholderia pseudomallei is the causative agent of melioidosis, a fatal human tropical disease. The non-specific DNA-binding protein DpsA plays a key role in protecting B. pseudomallei from oxidative stress mediated, for example, by organic hydroperoxides. The regulation of dpsA expression is poorly understood but one possibility is that it is regulated in a cell population density-dependent manner via N-acylhomoserine lactone (AHL)-dependent quorum sensing (QS) since a lux-box motif has been located within the dpsA promoter region. Using liquid chromatography and tandem mass spectrometry, it was first established that B. pseudomallei strain PP844 synthesizes AHLs. These were identified as N-octanoylhomoserine lactone (C8-HSL), N-(3-oxooctanoyl)homoserine lactone (3-oxo-C8-HSL), N-(3-hydroxyoctanoyl)-homoserine lactone (3-hydroxy-C8-HSL), N-decanoylhomoserine lactone (C10-HSL), N-(3-hydroxydecanoyl) homoserine lactone (3-hydroxy-C10-HSL) and N-(3-hydroxydodecanoyl)homoserine lactone (3-hydroxy-C12-HSL). Mutation of the genes encoding the LuxI homologue BpsI or the LuxR homologue BpsR resulted in the loss of C8-HSL and 3-oxo-C8-HSL synthesis, demonstrating that BpsI was responsible for directing the synthesis of these AHLs only and that bpsI expression and hence C8-HSL and 3-oxo-C8-HSL production depends on BpsR. In bpsI, bpsR and bpsIR mutants, dpsA expression was substantially down-regulated. Furthermore, dpsA expression in Escherichia coli required both BpsR and C8-HSL. bpsIR-deficient mutants exhibited hypersensitivity to the organic hydroperoxide tert-butyl hydroperoxide by displaying a reduction in cell viability which was restored by provision of exogenous C8-HSL (bpsI mutant only), by complementation with the bpsIR genes or by overexpression of dpsA. These data indicate that in B. pseudomallei, QS regulates the response to oxidative stress at least in part via the BpsR/C8-HSL-dependent regulation of DpsA.
Growth-phase-dependent mobility of the lvh-encoding region in Legionella pneumophila strain Paris
Authors: Doléans-Jordheim Anne , Akermi Mongi , Ginevra Christophe , Cazalet Christel , Kay Elizabeth , Schneider Dominique , Buchrieser Carmen , Atlan Danièle , Vandenesch François , Etienne Jerome , Jarraud Sophie
Published: December 2006

The lvh region of the Legionella pneumophila genome, which encodes a type IV secretion system, is located on a plasmid-like element in strains Paris (pP36) and Philadelphia (pLP45). The pP36 element has been described either integrated in the chromosome or excised as a multi-copy plasmid, in a similar manner to pLP45. In this paper, the chromosomal integration of pP36 in the Paris strain genome was described, occurring through site-specific recombination at the 3′ end of a transfer-messenger RNA gene by recombination between attachment sites, in a similar manner to pathogenicity islands. This integration was growth-phase dependent, occurring during the exponential phase. Several pP36-borne genes were expressed during the lag phase of bacterial growth, coinciding with the peak amount of the episomal form of pP36. Expression of the same genes decreased during the exponential and stationary phases, owing to the integration phenomenon and a loss of episomal copies of pP36. A similar plasmid-like element was described in the Lens strain genome, suggesting that the mobility of the lvh region is a phenomenon widespread among Legionella sp.
Campylobacter jejuni-infected human epithelial cell lines vary in their ability to secrete interleukin-8 compared to in vitro-infected primary human intestinal tissue
Authors: MacCallum Amanda J. , Harris Dawn , Haddock Graham , Everest Paul H.
Published: December 2006

Campylobacter jejuni causes symptoms of acute inflammatory diarrhoea in man. C. jejuni interaction with epithelial cells elicits interleukin-8 (IL-8) production, and IL-8 recruits neutrophils to sites of infection. Cell culture models of bacterial interaction with epithelium are useful to define bacteria–host interaction and are used because it is thought they mimic the same bacteria–host cell interaction in the natural disease. This study looks at the ability of C. jejuni strains to elicit IL-8 production from a variety of cell lines previously used for investigating the interaction of C. jejuni with host cells. A spectrum of IL-8 responses was observed, with minimal IL-8 elicited from Caco-2 cells and more marked responses elicited from HeLa and T84 cells. These in vitro-infected cell line responses were compared to IL-8 production from in vitro
C. jejuni-infected human colonic and ileal tissue. The in vitro-infected tissue elicited the highest IL-8 responses and the cytokine was manifested earlier compared to the infected cell lines.
Comparative genomics of Neisseria meningitidis: core genome, islands of horizontal transfer and pathogen-specific genes
Authors: Hotopp Julie C. Dunning , Grifantini Renata , Kumar Nikhil , Tzeng Yih Ling , Fouts Derrick , Frigimelica Elisabetta , Draghi Monia , Giuliani Marzia Monica , Rappuoli Rino , Stephens David S. , Grandi Guido , Tettelin Hervé
Published: December 2006

To better understandNeisseria meningitidisgenomes and virulence, microarray comparative genome hybridization (mCGH) data were collected from oneNeisseria cinerea, twoNeisseria lactamica, twoNeisseria gonorrhoeaeand 48Neisseria meningitidisisolates. ForN. meningitidis, these isolates are from diverse clonal complexes, invasive and carriage strains, and all major serogroups. The microarray platform representedN. meningitidisstrains MC58, Z2491 and FAM18, andN. gonorrhoeaeFA1090. By comparing hybridization data to genome sequences, the coreN. meningitidisgenome and insertions/deletions (e.g. capsule locus, type I secretion system) related to pathogenicity were identified, including further characterization of the capsule locus, bioinformatics analysis of a type I secretion system, and identification of some metabolic pathways associated with intracellular survival in pathogens. Hybridization data clustered meningococcal isolates from similar clonal complexes that were distinguished by the differential presence of six distinct islands of horizontal transfer. Several of these islands contained prophage or other mobile elements, including a novel prophage and a transposon carrying portions of a type I secretion system. Acquisition of some genetic islands appears to have occurred in multiple lineages, including transfer betweenN. lactamicaandN. meningitidis. However, island acquisition occurs infrequently, such that the genomic-level relationship is not obscured within clonal complexes. TheN. meningitidisgenome is characterized by the horizontal acquisition of multiple genetic islands; the study of these islands reveals important sets of genes varying between isolates and likely to be related to pathogenicity.
CD3+ cells transfer the hypersensitive granulomatous response to mycobacterial glycolipid trehalose 6,6′-dimycolate in mice
Authors: Guidry Tera V. , Hunter Robert L. , Actor Jeffrey K.
Published: December 2006

The granulomatous response is the characteristic histological feature ofMycobacterium tuberculosisinfection that is essential for organism containment. Trehalose 6,6-dimycolate (TDM), a cell-wall glycolipid present on most mycobacterial species, has been implicated in the pathogenesis ofM. tuberculosisinfection. TDM has potent immunoregulatory and inflammatory properties, and can be used to model granulomatous reactions that mimic, in part, pathology caused during active infection. This study examined the hypersensitive granulomatous response, focusing on cellular responses specific to TDM. Lungs from mice immunized with TDM emulsion demonstrated exacerbated histological damage, inflammation, and lymphocytic infiltration upon subsequent challenge with TDM. Splenocytes recovered from these mice demonstrated significant interferon (IFN)-γproduction during recall response to TDM, as well as increased production of proinflammatory mediators (tumour necrosis factor-α, interleukin-6 and macrophage inflammatory protein-1α). The exacerbated response could be adoptively transferred to naïve mice. Administration of non-adherent lymphocytes or purified CD3+cells from TDM-immunized mice led to increased inflammation, lymphocytic infiltration, and vascular endothelial cell damage upon challenge with TDM. Recipient mice that received immunized CD3+lymphocytes demonstrated significant increases in Th1-type cytokines and proinflammatory mediators in lung tissue following TDM challenge. When CD1d−/−mice were immunized with TDM, they failed to generate a specific IFN-γresponse, suggesting a role for this molecule in the generation of hypersensitivity. These experiments provide further evidence for the involvement of TDM-specific CD3+T cells in pathological damage elicited duringM. tuberculosisinfection.
A gene cluster involved in the biosynthesis of vanchrobactin, a chromosome-encoded siderophore produced by Vibrio anguillarum
Authors: Balado Miguel , Osorio Carlos R. , Lemos Manuel L.
Published: December 2006

Vibrio anguillarumserotype O2 strains produce a catechol siderophore named vanchrobactin, which has been identified asN-[N′-(2,3-dihydroxybenzoyl)-arginyl]-serine. This work describes a chromosomal region that harbours the genetic determinants necessary for the biosynthesis of vanchrobactin. The authors have identified the genes involved in 2,3-dihydroxybenzoic acid (DHBA) biosynthesis (vabA,vabBandvabC) and activation (vabE), and a gene (vabF) encoding a non-ribosomal peptide synthetase, which is putatively involved in the assembly of the siderophore components. Also described are the identification and characterization of genes encoding a putative vanchrobactin exporter (vabS) and a siderophore esterase (vabH). In-frame deletion mutants invabA,vabB,vabC,vabE,vabFandvabHwere impaired for growth under conditions of iron limitation, and the analysis of culture supernatants by chrome azurol-S and cross-feeding assays showed almost no production of siderophores in any of thevabABCEFmutants. In addition, deletion mutations ofvabA,vabBandvabCabolished production of DHBA, as assessed by chemical and biological analyses. Complementation of each mutant with the corresponding gene providedin transconfirmed the involvement of this gene cluster in the biosynthesis of DHBA and vanchrobactin inV. anguillarumstrain RV22. Based on chemical and genetic data, and on published models for other catechol siderophores, a model for vanchrobactin biosynthesis is proposed.
Evaluation of platelet function and lack of response to epinephrine in pregnant women
Authors: SAGDILEK E. , BUYUKCOSKUN N. I. , OZLUK K.
Published: December 2006

Previous studies in healthy subjects have demonstrated a lack of response of platelets to epinephrine at a rate of 16–40% on an aggregometer. An association between the increased procoagulant factors during pregnancy and venous thromboembolism is known, and it has also been shown that prolactin levels increase platelet aggregation. We evaluated whether platelet functions in pregnant women and also assessed the lack of response to epinephrine during this period. We compared 27 healthy and volunteering pregnant women with 26 similar control subjects. Platelet functions were assessed with an aggregometer and a Platelet Function Analyzer (PFA‐100). Less than 40% response to epinephrine on the aggregometer was defined as an impaired epinephrine response. The aggregation response of epinephrine was normal in 25 of the 27 pregnant women, while two of them showed a late‐rising response. Eight of the 26 subject control group (30.8%) showed an impaired response to epinephrine. When we compared the 25 pregnant and 18 control subjects with normal aggregation responses, the maximum aggregation responses to ADP and epinephrine, and the Col/Epi and Col/ADP cartridge closure time values were significantly lower in pregnant women. There were no difference beetween second and third trimesters as regards platelet function parameters. The fact that no impaired response to epinephrine was detected in pregnant women while a 30% rate was observed in non‐pregnant women indicates that the platelet malfunction caused by a disorder in the Gi protein and intracellular mechanisms is bypassed during pregnancy thanks to some physiological changes.
RBC alloimmunization in blood transfusion‐dependent β‐thalassemia patients in southern Iran
Authors: KARIMI M. , NIKROOZ P. , KASHEF S. , JAMALIAN N. , DAVATOLHAGH Z.
Published: December 2006

β‐thalassemia is considered a severe, progressive anemia, which needs regular transfusions for life expectancy. One of the most important complications of regular blood transfusions may be alloimmunization, which increases the need for transfusion. This study was performed to investigate the production of red cell alloantibodies in β‐thalassemia patients in Shiraz, southern Iran. Blood sampling was performed among 711 β‐thalassemia patients in Dastgheib hospital in 2002–2004. Direct and indirect coombs tests were performed to check the auto and alloantibodies and a panel test was conducted to detect the type of alloantibodies. Auto and alloantibodies were observed among 1.7% and 5.3% of patients, respectively. The most common alloantibodies were Anti‐kell (50%) > Anti‐Rh (D) (15.8%) > Anti‐Rh (E) (10.5%). All the patients who had developed alloantibody were in the age group of 6 years or more. So for decreasing the rate of alloantibody synthesis, we should crossmatched the packed cells for minor blood groups especially for kell and Rh(E) in addition to major blood groups from the start of transfusion.
Expression of CD55 and CD59 on peripheral blood cells in patients with lymphoproliferative disease of granular lymphocytes
Authors: ISODA A. , TSUKAMOTO N. , MITSUI T. , YAMANE A. , HATSUMI N. , MATSUSHIMA T. , MURAKAMI H. , NOJIMA Y. , KARASAWA M.
Published: December 2006

Lymphoproliferative disease of granular lymphocytes (LDGL) is a disorder characterized by the clonal expansion of granular lymphocytes. It has recently been shown that the clonal expansion of granular lymphocytes occurs in patients with paroxysmal nocturnal hemoglobinuria (PNH) in a subclinical fashion. To test the possibility that LDGL patients share a PNH phenotype, we obtained peripheral blood cells from 20 patients with LDGL and examined the expression of the glycosylphosphatidyl inositol (GPI)‐anchored proteins, CD55 and CD59. Compared with normal controls, however, a defective expression of CD55/59 was not observed on either granulocytes or erythrocytes from LDGL patients. An unexpected finding was the significantly lower CD55/59 expression on granular lymphocytes from patients with CD16+CD56− phenotype LDGL than from patients with CD16+CD56+ phenotype LDGL, or natural killer (NK) and NK/T lymphocytes from healthy individuals. The positive correlation between the expression of CD56 and CD55/59 might have some relevance to the functional properties of the CD56+ subset of large granular lymphocytes.
Density dependence and noise determine the long‐term dynamics of two species of lady beetle (Coleoptera: Coccinellidae: Epilachninae) in the Indonesian tropics
Authors: BONSALL MICHAEL B. , HASAN NUSYIRWAN , NAKAMURA KOJI
Published: December 2006

Abstract1. The long‐term dynamics of two beetles (Epilachna vigintioctopunctataandEpilachna enneasticta) from Indonesia are analysed using descriptive time‐series statistics and mechanistic time‐series models.

2. Statistical analysis of the time series reveals that the dynamics ofE. vigintioctopunctataare underpinned by a second order density‐dependent [AR(2)] process, which is consistent between sites. Similarly, the dynamics ofE. enneastictaare also described by a second order density‐dependent [AR(2)] process. The predicted dynamics from these statistical models are stable dynamics.

3. Mechanistic models of the density dependence predict that in the absence of noise the dynamics of the populations should also be stable. Inclusion of the stochasticity in the models of density dependence allows a more accurate description of the population dynamics of each species to be determined.

4. Correlation analyses reveal that the fluctuations between species are a function of both the density dependence and the environmental conditions experienced by each species. Under low environmental variance it is predicted that the dynamics could be synchronised but under high variance in environmental noise, the dynamics may not be synchronised and species respond idiosyncratically to the environment.

5. The study highlights the value of long‐term population dynamic time series for exploring the structure of population regulation and fluctuations in insect populations.
The potential of grass field margin management for enhancing beetle diversity in intensive livestock farms
Authors: WOODCOCK B. A. , POTTS S. G. , PILGRIM E. , RAMSAY A. J. , TSCHEULIN T. , PARKINSON A. , SMITH R. E. N. , GUNDREY A. L. , BROWN V. K. , TALLOWIN J. R.
Published: December 2006

Declining populations of UK grassland flora and fauna have been attributed to intensification of agricultural management practices, including changes in cutting, fertilizer, grazing and drainage regimes. We aimed to develop field margin management practices that could reverse declines in intensively managed grassland biodiversity that would have application in the UK and Europe. Here we focus on one aspect of grassland biodiversity, the beetles.

In four intensively managed livestock farms in south‐west England, 10‐m wide field margins in existing grasslands were managed to create seven treatments of increasing sward architectural complexity. This was achieved through combinations of inorganic (NPK) fertilizer, cattle grazing, and timing and height of cutting. To examine the potential influence of complexity on faunal diversity, beetles were identified to species level from suction samples taken between 2003 and 2005, and their assemblage structure was related to margin management, floral assemblages and sward architecture.

Beetle abundance, and species richness and evenness were influenced by margin management treatment and its interaction with year. Correlations with sward architecture and the percentage cover of dominant forbs and grasses were also found. Functional groups of the beetles showed different responses to the management treatments. In particular, higher proportional abundances of seed/flower‐feeding guilds were found in treatments not receiving NPK fertilizer.

The assemblage structure was shown to respond to margin management treatments, sward architecture and the percentage cover of dominant forbs and grasses. The most extensively managed treatments were characterized by distinct successional trajectories from the control treatment.

Synthesis and applications. This study provides management options suitable for use within agri‐environment schemes intended to improve faunal diversity associated with intensively managed lowland grasslands. Field margins receiving either no management or a single July silage cut were shown to support greater abundances and species richness of beetles, although subtler modifications of conventional management may also be beneficial, for example the absence of NPK fertilizer while maintaining grazing and silage cutting systems.
Enhancing diversity of species‐poor grasslands: an experimental assessment of multiple constraints
Authors: PYWELL RICHARD F. , BULLOCK JAMES M. , TALLOWIN JERRY B. , WALKER KEVIN J. , WARMAN ELIZABETH A. , MASTERS GREG
Published: December 2006

Many grasslands in north‐west Europe are productive but species‐poor communities resulting from intensive agriculture. Reducing the intensity of management under agri‐environment schemes has often failed to increase botanical diversity. We investigated biotic and abiotic constraints on diversification by manipulating seed and microsite availability, soil fertility, resource competition, herbivory and deficiencies in the soil microbial community.

The effectiveness of 13 restoration treatments was investigated over 4 years in a randomized block experiment established in two productive grasslands in central‐east and south‐west England.

Severe disturbance involving turf removal followed by seed addition was the most effective and reliable means of increasing grassland diversity. Disturbance by multiple harrowing was moderately effective but was enhanced by molluscicide application to reduce seedling herbivory and by sowing the hemiparasite Rhinanthus to reduce competition from grasses.

Low‐level disturbance by grazing or slot‐seeding was ineffective in increasing diversity. Inoculation with soil microbial communities from species‐rich grasslands had no effect on botanical diversity. Nitrogen and potassium fertilizer addition accelerated off‐take of phosphorus in cut herbage but did not cause a reduction in soil phosphorus or increase botanical diversity.

Different grazing management regimes had little impact on diversity. This may reflect the constraining effect of the July hay cut on species dispersal and colonization.

Synthesis and applications. Three alternative approaches to grassland diversification, with different outcomes, are recommended. (i) High intervention deturfing, which would create patches with low competitive conditions for rapid and reliable establishment of the target community. For reasons of cost and practicality this can only be done over small areas but will form source populations for subsequent spread. (ii) Moderate intervention (harrowing or slot‐seeding) over large areas, which would establish a limited number of desirable, generalist species that perform well in restoration. This method is low cost and rapid but the increases in biodiversity are less predictable. (iii) Phased restoration, which would complement the above approaches. Productivity and competition are reduced over 3–5 years using Rhinanthus or fertilizers to accelerate phosphorus off‐take. After this time harrowing and seeding should allow a wide range of more specialist species to establish. However, further research is required to determine the long‐term effectiveness of these approaches.
Social Instability in Adolescence Alters the Central and Peripheral Hypothalamic‐Pituitary‐Adrenal Responses to a Repeated Homotypic Stressor in Male and Female Rats
Authors: McCormick C. M. , Merrick A. , Secen J. , Helmreich D. L.
Published: December 2006

There has been little research on effects of chronic stressors on neuroendocrine function in adolescence despite increasing evidence of enduring effects of stressors during this period on behaviour in adulthood. We previously reported that social stress (SS: daily 1 h isolation and new cage partner for 16 days) in adolescence altered locomotor responses to psychostimulants in adulthood. Here, we investigated neuroendocrine responses over the duration of the procedure that may underlie the enduring effects of SS. SS rats were compared to rats undergoing daily isolation only (ISO) and controls (CTL) to determine responses to acute and repeated isolation with and without social instability. At 30 days of age (first isolation), higher plasma corticosterone and corticotrophin‐releasing hormone (CRH) mRNA expression in the paraventricular nucleus (PVN) of the hypothalamus and in the central nucleus of the amygdala (CeA) were found in males caged with a new partner (SS) after isolation than those returned to their original partner (ISO). On day 45, SS males and females showed less habituation (higher bioactive levels of corticosterone based on plasma corticosterone and corticosteroid binding globulin levels) to the 16th episode of isolation than did ISO. SS and ISO had higher baseline expression of CRH mRNA in the PVN on day 45 than did CTL, and only CTL had increased levels after isolation. CRH mRNA expression in the CeA increased to a first isolation in CTL and to a 16th isolation in SS but not in ISO males. Modest differences in social interactions were observed between SS and ISO when returned to their cages after isolation. The results suggest that mild social stressors in adolescence impede neuroendocrine adaptation to homotypic stressors. The resultant increase in exposure to glucocorticoids over adolescence may alter ongoing brain development and increase vulnerability to psychopathology.
Identifying Canadian mosquito species through DNA barcodes
Authors: CYWINSKA A. , HUNTER F. F. , HEBERT P. D. N.
Published: December 2006

Abstract A short fragment of mt DNA from the cytochrome c oxidase 1 (CO1) region was used to provide the first CO1 barcodes for 37 species of Canadian mosquitoes (Diptera: Culicidae) from the provinces Ontario and New Brunswick. Sequence variation was analysed in a 617‐bp fragment from the 5′ end of the CO1 region. Sequences of each mosquito species formed barcode clusters with tight cohesion that were usually clearly distinct from those of allied species. CO1 sequence divergences were, on average, nearly 20 times higher for congeneric species than for members of a species; divergences between congeneric species averaged 10.4% (range 0.2–17.2%), whereas those for conspecific individuals averaged 0.5% (range 0.0–3.9%).
Geometric and mechanosensory properties of the sigmoid colon evaluated with magnetic resonance imaging
Authors: Frøkjær J. B. , Liao D. , Steffensen E. , Dimcevski G. , Bergmann A. , Drewes A. M. , Gregersen H.
Published: December 2006

Abstract  The aim of this study was to use magnetic resonance imaging (MRI) to evaluate the three‐dimensional geometry and mechanosensory properties of the sigmoid colon. The sigmoid colon was stepwise distended by a water‐filled bag in eight subjects. Simultaneous MRI, bag pressure recording and sensory assessment were performed before and after smooth muscle relaxation with butylscopolamine. The surface distributions of principal curvature radii, wall thickness, tension, stress and circumferential strain were calculated. The geometry of the distended sigmoid colon was complex and the spatial distributions of the biomechanical parameters were non‐homogeneous. The circumferential length, strain, pressure and wall stress increased as a function of bag volume (all P < 0.001). In response to butylscopolamine, the pressure and wall stress were reduced (P < 0.05) and the stress–strain curves were shifted to the right. The sensory response was a linear function of the biomechanical parameters (all P < 0.001) and decreased in response to butylscopolamine as a function of volume (P = 0.02). The stimulus–response data indicate that the mechanosensitive afferents are affected by smooth muscle tone. The present study provides a method for characterizing the complex geometry and mechanical properties of the sigmoid colon, including the role of smooth muscle tone. This may be valuable in understanding of the biomechanical and mechanosensory functions in colonic diseases.
Good genes, genetic compatibility and the evolution of polyandry: use of the diallel cross to address competing hypotheses
Authors: IVY T. M.
Published: December 2006

Genetic benefits can enhance the fitness of polyandrous females through the high intrinsic genetic quality of females’ mates or through the interaction between female and male genes. I used a full diallel cross, a quantitative genetics design that involves all possible crosses among a set of genetically homogeneous lines, to determine the mechanism through which polyandrous female decorated crickets (Gryllodes sigillatus) obtain genetic benefits. I measured several traits related to fitness and partitioned the phenotypic variance into components representing the contribution of additive genetic variance (‘good genes’), nonadditive genetic variance (genetic compatibility), as well as maternal and paternal effects. The results reveal a significant variance attributable to both nonadditive and additive sources in the measured traits, and their influence depended on which trait was considered. The lack of congruence in sources of phenotypic variance among these fitness‐related traits suggests that the evolution and maintenance of polyandry are unlikely to have resulted from one selective influence, but rather are the result of the collective effects of a number of factors.
The ethics of blood management
Authors: Sazama K.
Published: December 2006

Blood transfusion practices have evolved empirically, with few or no research data supporting them. In the past several decades, fuelled by fears of infection and reports of mistakes, patients have increasingly demanded their rights to choice, both in the components given to them as well as to refuse to receive these therapies based on religious convictions. In parallel, episodic blood unavailability and growing awareness of the need to apply evidence‐based methods have caused physicians to begin re‐evaluating traditional practices and to focus on minimizing or eliminating unnecessary transfusions while learning and applying methods that permit reuse of the patient's autologous blood or rely on pharmacologic agents. Ethical principles of autonomy, beneficence, non‐maleficence and justice provide a rational basis for decision‐making when a new blood management programme is instituted. By proactively considering the ethical dilemmas posed by the juxtaposition of patient needs with clinical judgement at the outset, institutions may devise workable programmes that improve patient safety and quality outcomes.
Single nucleotide polymorphism profiling assay to exclude serum sample mix‐up
Authors: Huijsmans C. J. J. , Heilmann F. G. C. , Van Der Zanden A. G. M. , Schneeberger P. M. , Hermans M. H. A.
Published: December 2006

Background and Objectives  Sample mix‐ups are a threat to the validity of clinical laboratory test results. To detect serum sample mix‐ups we developed a single nucleotide polymorphism (SNP) profiling test. SNPs are frequent sequence variations in the human genome. Each individual has a unique combination of these nucleotide variations.

Materials and Methods  Predeveloped SNP amplification assays are commercially available. We recently discovered that these SNP assays could be applied to serological samples, which is not self‐evident because a key step in serum preparation is removal of white blood cells, the major source of DNA, from blood. DNA was extracted from serum samples. Real‐time polymerase chain reaction (PCR) analysis of the purified DNA using a selection of 10 SNP assays provided SNP profiles.

Results  The applicability of the SNP profiling test was demonstrated by means of a case where hepatitis E virus serological determinations of four serum samples of one patient seemed inconsistent. SNP profiling of the samples demonstrated that this was due to the enzyme‐linked immunosorbent assay test instead of sample mix‐up.

Conclusion  We have developed an SNP profiling assay that provides a way to link human serum samples to a source, without post‐PCR processing. The chance for two randomly chosen individuals to have an identical profile is 1 in 18 000. Solving potential serum sample mix‐ups will secure downstream evaluations and critical decisions concerning the patients involved.
The interaction between prion protein and laminin modulates memory consolidation
Authors: Coitinho Adriana S. , Freitas Adriana R. O. , Lopes Marilene H. , Hajj Glaucia N. M. , Roesler Rafael , Walz Roger , Rossato Janine I. , Cammarota Martin , Izquierdo Ivan , Martins Vilma R. , Brentani Ricardo R.
Published: December 2006

Cellular prion protein (PrPc) has a pivotal role in prion diseases. PrPc is a specific receptor for laminin (LN) γ1 peptide and several lines of evidence indicate that it is also involved in neural plasticity. Here we investigated whether the interaction between PrPc and LN plays a role in rat memory formation. We found that post‐training intrahippocampal infusion of PrPc‐derived peptides that contain the LN binding site ( and ) or of anti‐PrPc or anti‐LN antibodies that inhibit PrPc–LN interaction impaired inhibitory avoidance memory retention. The amnesic effect of anti‐PrPc antibodies and peptide was reversed by co‐infusion of a LN γ1 chain‐derived peptide containing the PrPc‐binding site, suggesting that PrPc–LN interaction is indeed crucial for memory consolidation. In addition, peptide and anti‐PrPc or anti‐LN antibodies also inhibited the activation of hippocampal cAMP‐dependent protein kinase A (PKA) and extracellular regulated kinase (ERK1/2), two kinases that mediate the up‐regulation of signaling pathways needed for consolidation of inhibitory avoidance memory. Our findings show that, through its interaction with LN, hippocampal PrPc plays a critical role in memory processing and suggest that this role is mediated by activation of both PKA and ERK1/2 signaling pathways.
Morphological and cellular changes within embryonic striatal grafts associated with enriched environment and involuntary exercise
Authors: Döbrössy Máté D. , Dunnett Stephen B.
Published: December 2006

Environmental enrichment (EE) and exercise have been implicated in influencing behaviour and altering neuronal processes associated with cellular morphology in both ‘normal’ and injured states of the CNS. Using a rodent model of Huntington's disease, we investigated whether prolonged EE or involuntary exercise can induce morphological and cellular changes within embryonic striatal transplants. Adult rats were trained on the Staircase test – requiring fine motor control to reach and collect reward pellets – prior to being lesioned unilaterally in the dorsal neostriatum with quinolinic acid. The lesioned animals received E15 whole ganglionic eminence cell suspension grafts followed by housing in EE or standard cages. Half of the animals in standard cages received daily forced exercise on a treadmill. The grafted animals showed significant functional recovery on both the Staircase test and in drug‐induced rotation. Neither the housing conditions nor the training had an impact on the behaviour, with the exception of the treadmill reducing the ipsilateral drug‐induced rotation observed amongst the lesioned animals. However, the animals housed in the EE had significantly increased striatal brain‐derived neurotrophic factor (BDNF) levels, and graft neurons in these animals exhibited both greater spine densities and larger cell volumes. Animals on forced exercise regime had reduced BDNF levels and grafted cells with sparser spines. The study suggests that the context of the animal can affect the plasticity of transplanted cells. Appropriately exploiting the underlying, and yet unknown, mechanisms could lead the way to improved anatomical and potentially functional integration of the graft.
Differential expression of active zone proteins in neuromuscular junctions suggests functional diversification
Authors: Juranek Judyta , Mukherjee Konark , Rickmann Michael , Martens Henrik , Calka Jaroslaw , Südhof Thomas C. , Jahn Reinhard
Published: December 2006

Nerve terminals of the central nervous system (CNS) contain specialized release sites for synaptic vesicles, referred to as active zones. They are characterized by electron‐dense structures that are tightly associated with the presynaptic plasma membrane and organize vesicle docking and priming sites. Recently, major protein constituents of active zones have been identified, including the proteins Piccolo, Bassoon, RIM, Munc13, ERCs/ELKs/CASTs and liprins. While it is becoming apparent that each of these proteins is essential for synaptic function in the CNS, it is not known to what extent these proteins are involved in synaptic function of the peripheral nervous system. Somatic neuromuscular junctions contain morphologically and functionally defined active zones with similarities to CNS synapses. In contrast, sympathetic neuromuscular varicosities lack active zone‐like morphological specializations. Using immunocytochemistry at the light and electron microscopic level we have now performed a systematic investigation of all five major classes of active zone proteins in peripheral neuromuscular junctions. Our results show that somatic neuromuscular endplates contain a full complement of all active zone proteins. In contrast, varicosities of the vas deferens contain a subset of active zone proteins including Bassoon and ELKS2, with the other four components being absent. We conclude that Bassoon and ELKS2 perform independent and specialized functions in synaptic transmission of autonomic synapses.
Docosahexaenoic acid (22:6n‐3) enrichment of membrane phospholipids increases gap junction coupling capacity in cultured astrocytes
Authors: Champeil‐Potokar Gaelle , Chaumontet Catherine , Guesnet Philippe , Lavialle Monique , Denis Isabelle
Published: December 2006

Although it is agreed that n‐3 polyunsaturated fatty acids (PUFAs) are important for brain function, it has yet to be demonstrated how they are involved in precise cellular mechanisms. We investigated the role of enhanced n‐3 PUFA in astrocyte membranes on the gap junction capacity of these cells. Astrocytes isolated from newborn rat cortices were grown in medium supplemented with docosahexaenoic acid (DHA), the main n‐3 PUFA in cell membranes, or arachidonic acid (AA), the main n‐6 PUFA, plus an antioxidant (α‐tocopherol or N‐acetyl‐cystein) to prevent peroxidation. The resulting three populations of astrocytes differed markedly in their n‐3 : n‐6 PUFA ratios in phosphatidylethanolamine and phosphatidylcholine, the main phospholipids in membranes. DHA‐supplemented cells had a physiological high n‐3 : n‐6 ratio (1.58), unsupplemented cells had a low n‐3 : n‐6 ratio (0.66) and AA‐supplemented cells had a very low n‐3 : n‐6 ratio (0.36), with excess n‐6 PUFA. DHA‐supplemented astrocytes had a greater gap junction capacity than unsupplemented cells or AA‐supplemented cells. The enhanced gap junction coupling of DHA‐enriched cells was associated with a more functional distribution of connexin 43 at cell interfaces (shown by immunocytochemistry) and more of the main phosphorylated isoform of connexin 43. These findings suggest that the high n‐3 : n‐6 PUFA ratio that occurs naturally in astrocyte membranes is needed for optimal gap junction coupling in these cells.
Episodic ataxia type 1 mutations in the KCNA1 gene impair the fast inactivation properties of the human potassium channels Kv1.4‐1.1/Kvβ1.1 and Kv1.4‐1.1/Kvβ1.2
Authors: Imbrici Paola , D'Adamo Maria Cristina , Kullmann Dimitri M. , Pessia Mauro
Published: December 2006

Episodic ataxia type 1 (EA1) is an autosomal dominant neurological disorder characterized by constant muscle rippling movements (myokymia) and episodic attacks of ataxia. Several heterozygous point mutations have been found in the coding sequence of the voltage‐gated potassium channel gene KCNA1 (hKv1.1), which alter the delayed‐rectifier function of the channel. Shaker‐like channels of different cell types may be formed by unique hetero‐oligomeric complexes comprising Kv1.1, Kv1.4 and Kvβ1.x subunits. Here we show that the human Kvβ1.1 and Kvβ1.2 subunits modulated the functional properties of tandemly linked Kv1.4‐1.1 wild‐type channels expressed in Xenopus laevis oocytes by (i) increasing the rate and amount of N‐type inactivation, (ii) slowing the recovery rate from inactivation, (iii) accelerating the cumulative inactivation of the channel and (iv) negatively shifting the voltage dependence of inactivation. To date, the role of the human Kv1.4‐1.1, Kv1.4‐1.1/Kvβ1.1 and Kv1.4‐1.1/Kvβ1.2 channels in the aetiopathogenesis of EA1 has not been investigated. Here we also show that the EA1 mutations E325D, V404I and V408A, which line the ion‐conducting pore, and I177N, which resides within the S1 segment, alter the fast inactivation and repriming properties of the channels by decreasing both the rate and degree of N‐type inactivation and by accelerating the recovery from fast inactivation. Furthermore, the E325D, V404I and I177N mutations shifted the voltage dependence of the steady‐state inactivation to more positive potentials. The results demonstrate that the human Kvβ1.1 and Kvβ1.2 subunits regulate the proportion of wild‐type Kv1.4‐1.1 channels that are available to open. Furthermore, EA1 mutations alter heteromeric channel availability which probably modifies the integration properties and firing patterns of neurones controlling cognitive processes and body movements.
Glutamate‐mediated excitotoxicity in neonatal hippocampal neurons is mediated by mGluR‐induced release of Ca++ from intracellular stores and is prevented by estradiol
Authors: Hilton Genell D. , Nunez Joseph L. , Bambrick Linda , Thompson Scott M. , McCarthy Margaret M.
Published: December 2006

Hypoxic/ischemic (HI) brain injury in newborn full‐term and premature infants is a common and pervasive source of life time disabilities in cognitive and locomotor function. In the adult, HI induces glutamate release and excitotoxic cell death dependent on NMDA receptor activation. In animal models of the premature human infant, glutamate is also released following HI, but neurons are largely insensitive to NMDA or AMPA/kainic acid (KA) receptor‐mediated damage. Using primary cultured hippocampal neurons we have determined that glutamate increases intracellular calcium much more than kainic acid. Moreover, glutamate induces cell death by activating Type I metabotropic glutamate receptors (mGluRs). Pretreatment of neurons with the gonadal steroid estradiol reduces the level of the Type I metabotropic glutamate receptors and completely prevents cell death, suggesting a novel therapeutic approach to excitotoxic brain damage in the neonate.
Properties of cholinergic responses in neurons in the intermediate grey layer of rat superior colliculus
Authors: Sooksawate Thongchai , Isa Tadashi
Published: December 2006

The intermediate grey layer (SGI) of superior colliculus (SC) receives cholinergic innervation from brainstem parabrachial region. To clarify the action of cholinergic inputs to local circuits in the SGI, we investigated the effect of cholinergic agonists and antagonists on a large number of randomly sampled neurons in Wistar rat SGI (n = 246) using whole‐cell patch clamp technique in slices of the rat SC. Responses of the recorded cells (n = 98) to bath application of carbachol were classified into five patterns: (i) nicotinic inward only (n = 14); (ii) nicotinic inward + muscarinic inward (n = 26); (iii) nicotinic inward + muscarinic inward + muscarinic outward (n = 39); (iv) nicotinic inward + muscarinic outward (n = 13) and (v) muscarinic outward only (n = 4). Among these, a majority of morphologically identified projection neurons exhibited either response pattern (ii) (9/28) or (iii) (15/28), which suggested that the primary action of cholinergic inputs on the SGI output is excitatory. Nicotinic receptor subtypes involved in the nicotinic current were examined by testing the effects of antagonists on the currents induced by bath application of 1,1‐dimethyl‐4‐phenyl‐piperazinium or transient pressure application of acetylcholine (ACh). Muscarinic receptor subtypes involved in the muscarinic inward and outward currents were investigated by examining the effects of antagonists on muscarine‐induced currents. The results showed that nicotinic inward currents are mediated mainly by α4β2 and partly by α7 nicotinic receptors and that muscarinic inward and outward currents are mediated by M3 (plus M1) and M2 muscarinic receptors, respectively.
A CaV2.1 calcium channel mutation rocker reduces the number of postsynaptic AMPA receptors in parallel fiber–Purkinje cell synapses
Authors: Kodama Takashi , Itsukaichi‐Nishida Yuko , Fukazawa Yugo , Wakamori Minoru , Miyata Mariko , Molnar Elek , Mori Yasuo , Shigemoto Ryuichi , Imoto Keiji
Published: December 2006

The rocker mice are hereditary ataxic mutants that carry a point mutation in the gene encoding the CaV2.1 (P/Q‐type) Ca2+ channel α1 subunit, and show the mildest symptoms among the reported CaV2.1 mutant mice. We studied the basic characteristics of the rocker mutant Ca2+ channel and their impacts on excitatory synaptic transmission in cerebellar Purkinje cells (PCs). In acutely dissociated PC somas, the rocker mutant channel showed a moderate reduction in Ca2+ channel current density, whereas its kinetics and voltage dependency of gating remained nearly normal. Despite the small changes in channel function, synaptic transmission in the parallel fiber (PF)–PC synapses was severely impaired. The climbing fiber inputs onto PCs showed a moderate impairment but could elicit normal complex spikes. Presynaptic function of the PF–PC synapses, however, was unexpectedly almost normal in terms of paired‐pulse facilitation, sensitivity to extracellular Ca2+ concentration and glutamate concentration in synaptic clefts. Electron microscopic analyses including freeze‐fracture replica labeling revealed that both the number and density of postsynaptic α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptors substantially decreased without gross structural changes of the PF–PC synapses. We also observed an abnormal arborization of PC dendrites in young adult rocker mice (∼ 1 month old). These lines of evidence suggest that even a moderate dysfunction of CaV2.1 Ca2+ channel can cause substantial changes in postsynaptic molecular composition of the PF–PC synapses and dendritic structure of PCs.