bluuebunny/crossref_metadata_2025_split huggingface dataset:
The long‐chain fatty acid sensor, PsrA, modulates the expression of rpoS and the type III secretion exsCEBA operon in Pseudomonas aeruginosa
Authors: Kang Yun , Lunin Vladimir V. , Skarina Tatiana , Savchenko Alexei , Schurr Michael J. , Hoang Tung T. 
Published: June 2009

SummaryThe Pseudomonas aeruginosa PsrA autorepressor has dual roles as a repressor of the fadBA5β‐oxidation operon and an activator of the stationary‐phase sigma factor rpoS and exsCEBA operon of the type III secretion system (TTSS). Previously, we demonstrated that the repression of the fadBA5 operon by PsrA is relieved by long‐chain fatty acids (LCFAs). However, the signal affecting the activation of rpoS and exsC via PsrA is unknown. In this study, microarray and gene fusion data suggested that LCFA (e.g. oleate) affected the expression of rpoS and exsC. DNA binding studies confirmed that PsrA binds to the rpoS and exsC promoter regions. This binding was inhibited by LCFA, indicating that LCFA directly affects the activation of these two genes through PsrA. LCFA decreased rpoS and exsC expression, resulting in increased N‐(butyryl)‐l‐homoserine‐lactone quorum sensing signal and decreased ExoS/T production respectively. Based on the crystal structure of PsrA, site‐directed mutagenesis of amino acid residues, within the hydrophobic channel thought to accommodate LCFA, created two LCFA‐non‐responsive PsrA mutants. The binding and activation of rpoS and exsC by these PsrA mutants was no longer inhibited by LCFA. These data support a mechanistic model where LCFAs influence PsrA regulation to control LCFA metabolism and some virulence genes in P. aeruginosa.
Factors influencing infection of eucalypts by Cylindrocladium pteridis
Authors: Graça R. N. , Alfenas A. C. , Maffia L. A. , Titon M. , Alfenas R. F. , Lau D. , Rocabado J. M. A. 
Published: June 2009

The pattern of Cylindrocladium pteridis adhesion, germination and penetration in eucalypt leaves was assessed using scanning electron microscopy. The effects of inoculum concentration, leaf wetness period, plant age and branch position of cylindrocladium leaf blight and defoliation severity were assessed in greenhouse studies using two Eucalyptus grandis × E. urophylla hybrid clones. Penetration occurred through stomata, and there was no difference in the number of penetrations between young and old leaves. Percentage leaf area with lesions and defoliation increased with the increase in inoculum concentration (1 × 102 to 105 conidia mL−1), duration of leaf wetness period (6 to 48 h) and plant age (60 to 180 days). Branch position in plants also significantly affected the percentage leaf area with lesions and defoliation, the latter variable being significantly higher at the stem base. The highest values of lesion area were also observed on leaves at the stem base in both clones. The Pearson correlation between defoliation and leaf area with lesions was significant in all experiments (r > 0·9) indicating a high association between these two variables.
Genetic analysis of Mycosphaerella fijiensis in the Ugandan Lake Victoria region
Authors: Fahleson J. , Nakyanzi M. , Okori P. , Seal S. , Kenyon L. , Dixelius C. 
Published: June 2009

A collection of Mycosphaerella fijiensis, in total 71 isolates from 11 countries, of which 54 isolates were derived from the Ugandan Lake Victoria region, were analysed with regard to molecular markers and benomyl resistance to characterize the population structure. Forty‐seven alleles from seven restriction fragment length polymorphism (PCR‐RFLP) and five microsatellite markers were scored and utilized in the study. Using analysis of molecular variance (amova), no significant genetic differentiation could be found between isolates from different leaves compared to isolates from a single leaf (P = 0·07). Exact tests of the allelic frequencies revealed no differences between isolates from different districts or between single‐leaf‐derived isolates compared to isolates derived from different leaves (P > 0·05 in all cases except two, which, however, were shown to be of type‐I error). Resistance to benomyl, analysed both by PCR and fungicide screening, revealed that all isolates were susceptible. Compiled information from the various datasets implied that the Ugandan M. fijiensis population in the Lake Victoria Basin constitutes a homogenous population, probably as the result of a recent founder event.
Parasitoids of the African wild silkmoth, Gonometa postica (Lepidoptera: Lasiocampidae) in the Mwingi forests, Kenya
Authors: Fening K. O. , Kioko E. N. , Raina S. K. , Mueke J. M. 
Published: June 2009

Abstract Gonometa postica Walker produces silk of high quality, but it is affected by parasitoids attack. A study on the parasitism of G. postica larvae and pupae on host and non‐host plants were undertaken for the first and second generations, corresponding to the long (March–May) and short (October–December) rainy seasons in 2006 at six field sites, three each in the Imba and Mumoni forests of Mwingi, eastern Kenya. All freshly spun cocoons of G. postica were sampled at each site from a total of 100 trees of host plants and other non‐host plants where they have migrated before pupation. The cocoons were kept individually in fine net‐sealed plastic vials to determine percentage parasitism. Two dipterans and four hymenopteran larval–pupal parasitoids were identified from the two forests. The most common parasitoids were Palexorista sp. (Diptera: Tachinidae) and Goryphus sp. (Hymenoptera: Ichneumonidae) with parasitism ranging from 1.8 to 32.7% and 2.2 to 7.5%, respectively. Parasitism varied significantly according to host or non‐host plants, seasons and sites. This study indicates that, of the six parasitoid species recovered, only two had a significant impact in reducing the quality of the cocoons.
Upregulation of hyaluronan and its binding receptors in an experimental model of chronic cyclosporine nephropathy
Authors: HAN DONG HE , SONG HYUN KUK , LEE SO YOUNG , SONG JI‐HYUN , PIAO SHANG GUO , YOON HYE EUN , GHEE JUNG YEON , YOON HYUNG JU , KIM JIN , YANG CHUL WOO 
Published: June 2009

ABSTRACT:Aim:  Hyaluronan (HA) is an important extracellular matrix (ECM) proteoglycan. The localization of HA and its binding receptors, CD44 and LYVE‐1, was evaluated in an experimental model of chronic cyclosporine A (CsA)‐induced nephropathy.Methods:  Sprague–Dawley rats maintained on a low‐salt diet (0.05% sodium) received an s.c. injection of vehicle (1 mL/kg per day olive oil; VH groups) or CsA (15 mg/kg per day; CsA groups) for 1 or 4 weeks. Induction of chronic CsA nephropathy was evaluated according to renal function and pathology and expression of HA, CD44, LYVE‐1, ED‐1 and α‐smooth muscle actin (α‐SMA).Results:  CsA treatment for 4 weeks caused renal dysfunction, which was accompanied by typical striped interstitial fibrosis. In the VH group, HA immunoreactivity was observed only in the inner medulla. However, the area of HA immunoreactivity increased with the duration of CsA treatment: CsA treatment for 1 week extended HA immunoreactivity to the outer medulla, and CsA treatment for 4 weeks caused a further extension of HA immunoreactivity to the cortex, which was vulnerable to CsA‐induced renal injury. HA binding receptor, CD44 and LYVE‐1 expression were also upregulated in the CsA groups, and were localized to the area of fibrosis and the peritubular capillaries of the cortex. In the CsA groups, ED‐1 and α‐SMA were predominantly expressed in fibrotic areas in which HA had accumulated.Conclusion:  These findings suggest that upregulation of HA and its binding receptors are involved in interstitial fibrosis in chronic CsA‐induced renal injury.
Tight relations between coronary calcification and atherosclerotic lesions in the carotid artery in chronic dialysis patients
Authors: KURNATOWSKA ILONA , GRZELAK PIOTR , STEFAŃCZYK LUDOMIR , NOWICKI MICHAŁ 
Published: June 2009

ABSTRACT:Aim:  Both vascular calcification and atherosclerosis are highly prevalent in patients with end‐stage renal disease (ESRD) and have been associated with increased cardiovascular morbidity. Because those two phenomena might be only coincidentally related in chronic haemodialysis (HD) patients, in this study, coronary artery calcification (CAC), common carotid artery intima media thickness (CCA‐IMT) and thickness of atherosclerotic plaques in the carotid artery were simultaneously measured.Methods:  In a cross‐sectional study of 47 HD patients (31 male, mean age 56.8 ± 11.4 years, and 16 female, mean age 56.0 ± 7.5 years) without history of major cardiovascular complications. CCA‐IMT and presence and thickness of atherosclerotic plaques were measured with ultrasound and CAC with multidetector computed tomography.Results:  The CAC were present in 70.2% of patients. The mean CAC was 1055 ± 232, the mean CCA‐IMT was 0.96 ± 0.21. The atherosclerotic plaques in the common carotid arteries were visualized in 38 patients (80.1%), the mean thickness of the atherosclerotic plaque was 1.61 ± 0.8 mm. We found a significant positive correlation between CAC and CCA‐IMT (r = 0.70, P < 0.001). The thickness of atherosclerosis plaque positively correlated with CAC as well as with CCA‐IMT (r = 0.60, P < 0.001 and r = 0.7, P < 0.003, respectively).Conclusion:  The study revealed close relationships between CAC, intima media thickness and the thickness of atherosclerotic plaques in dialysis patients. It may indicate that both vascular calcification and atherosclerotic lesions frequently coexist in patients with ESRD and that the intima media thickness could serve as a surrogate marker of vascular calcification.
The myelin protein MAL affects peripheral nerve myelination: a new player influencing p75 neurotrophin receptor expression
Authors: Buser A. M. , Schmid D. , Kern F. , Erne B. , Lazzati T. , Schaeren‐Wiemers N. 
Published: June 2009

AbstractThe myelin and lymphocyte protein (MAL) is a raft‐associated membrane protein predominantly expressed by oligodendrocytes and Schwann cells. Here we show that MAL regulates myelination in the peripheral nervous system. In mice overexpressing MAL, myelination was retarded and fibers were hypomyelinated, whereas myelination in MAL knockout mice was accelerated. This was not due to impaired Schwann cell proliferation, differentiation or axonal sorting. We found that the expression level of p75 neurotrophin receptor mRNA and protein was strongly reduced in developing sciatic nerves in MAL‐overexpressing mice. This reduction is well correlated with the observed alterations in myelination initiation, speed of myelination and alterations in Remak bundle development. Our results suggest a functional role for MAL in peripheral myelination by influencing the expression of membrane components that mediate axon‐glia interaction during ensheathment and myelin wrapping.
Subunit‐selective palmitoylation regulates the intracellular trafficking of AMPA receptor
Authors: Yang Guang , Xiong Wei , Kojic Luba , Cynader Max S. 
Published: June 2009

AbstractThe AMPA receptor (AMPAR) subunits GluR1 and GluR2 show different properties in central neurons and affect AMPAR trafficking via distinct mechanisms. This subunit‐specificity is partly achieved by recruiting unique protein modifications on different subunits. Here, we show that palmitoylation of GluR1 and GluR2 subunits also displays subunit‐specific properties and functions. Our findings indicate that GluR1 palmitoylation requires dynamic anterograde transport from the endoplasmic reticulum (ER) to the Golgi apparatus. In contrast, GluR2 subunits are primarily palmitoylated locally in the ER as immature receptors, and an intact microtubule network is required for their palmitoylation. Interestingly, the majority of palmitoylated GluR2 subunits are not associated with GluR1 subunits. We found that preventing palmitoylation results in loss of mature GluR2, but leaves GluR1 intact, as palmitoylation on GluR2 in the ER prevents their sorting to the lysosome after receptor maturation. Moreover, palmitoylation on GluR1 and GluR2 subunits responds differently to neuronal activity. Blocking neuronal activity by tetrodotoxin increased the pool size of palmitoylated GluR2, but not GluR1. Acute stimulation by NMDA and AMPA also differentially affect AMPAR palmitoylation in a subunit‐specific manner. The present findings thus indicate that AMPAR palmitoylation is a subunit‐specific process that contributes to its regulation and trafficking.
Deletion of TASK1 and TASK3 channels disrupts intrinsic excitability but does not abolish glucose or pH responses of orexin/hypocretin neurons
Authors: González J. A. , Jensen Lise T. , Doyle Susan E. , Miranda‐Anaya Manuel , Menaker Michael , Fugger Lars , Bayliss Douglas A. , Burdakov Denis 
Published: June 2009

AbstractThe firing of hypothalamic hypocretin/orexin neurons is vital for normal sleep–wake transitions, but its molecular determinants are not well understood. It was recently proposed that TASK (TWIK‐related acid‐sensitive potassium) channels [TASK1 (K2P3.1) and/or TASK3 (K2P9.1)] regulate neuronal firing and may contribute to the specialized responses of orexin neurons to glucose and pH. Here we tested these theories by performing patch‐clamp recordings from orexin neurons directly identified by targeted green fluorescent protein labelling in brain slices from TASK1/3 double‐knockout mice. The deletion of TASK1/3 channels significantly reduced the ability of orexin cells to generate high‐frequency firing. Consistent with reduced excitability, individual action potentials from knockout cells had lower rates of rise, higher thresholds and more depolarized after‐hyperpolarizations. However, orexin neurons from TASK1/3 knockout mice retained typical responses to glucose and pH, and the knockout animals showed normal food‐anticipatory locomotor activity. Our results support a novel role for TASK genes in enhancing neuronal excitability and promoting high‐frequency firing, but suggest that TASK1/3 subunits are not essential for orexin cell responses to glucose and pH.
Hippocampal‐dependent familiar area map supports corrective re‐orientation following navigational error during pigeon homing: a GPS‐tracking study
Authors: Gagliardo Anna , Ioalè Paolo , Savini Maria , Dell’Omo Giacomo , Bingman Verner P. 
Published: June 2009

AbstractIt is hypothesized that a central role of the vertebrate hippocampal formation (HF) in behavior is the learning and operation of a map‐like representation of familiar landmarks and landscape features. One critical property of a map is that it should enable an individual to re‐orient towards a goal location following a navigational error. To test this prediction on a spatial scale consistent with their naturally occurring behavior, control and HF‐lesioned homing pigeons were trained from two locations and then subsequently released, while carrying portable GPS‐tracking devices, following a phase‐shift treatment. Analyses revealed that the HF‐lesioned pigeons were less successful than control pigeons in re‐orienting homewards following the phase‐shift‐induced error in their initial orientation. Furthermore, the observation that HF‐lesioned pigeons were found to routinely ignore a land–sea landscape boundary when returning home from one of the release sites suggests that coarse landscape features may be an underappreciated source of navigational information for homing pigeons. The data demonstrate that, on a scale of tens of kilometers, homing pigeons are able to learn a hippocampal‐dependent, map‐like representation of familiar landmarks/landscape features that can support corrective re‐orientation following a navigational error.
Intertwined interspecies relationships: approaches to untangle the microbial network
Authors: Haruta Shin , Kato Souichiro , Yamamoto Kyosuke , Igarashi Yasuo 
Published: June 2009

SummaryIn nature, microorganisms live by interacting with each other. Microbiological studies that only consider pure cultures are not sufficient to adequately describe the natural behaviour of microbes. Several microbial interactions have been recognized to affect the growth or metabolism of others; e.g. syntrophic cometabolism, competition, production of inhibitors or activators, and predation. It is believed that third‐party organisms easily affect the two‐species relationships and these relationships form the basis of interspecies networks within microbial communities. A microbial network contributes to ‘functional redundancy’ or ‘structural diversity’ and the microbial communities effectively act as a multicellular organism. It is necessary to understand not only the physiological activity of members within microbial communities but also their roles to regulate the activity or population of others. To access the microbial network, we require (i) comprehensive determination of all possible interspecies relationships among microbes, (ii) knock‐out experiments by which certain members can be removed or suppressed, and (iii) supplemental addition of microbes or activation of certain members. Microbial network studies have started using defined microbial communities, i.e. a mixed culture that is composed of three or four species. In order to expand these studies to microflora in nature, microbial ecology requires the help of mathematical biology.
Paradoxically, prior acquisition of antioxidant activity enhances oxidative stress‐induced cell death
Authors: Murik Omer , Kaplan Aaron 
Published: June 2009

SummaryOxidative stress has been implicated in the induction of programmed cell death in a wide variety of organisms. Acquiring antioxidant capacity is thought to enhance the viability of cells challenged by a subsequent oxidative stress. Counter‐intuitively, we show that in two phytoplankton species, Chlamydomonas reinhardtii and Peridinium gatunense, representing the green and red plastid lineages, oxidative stress induced cell death in cultures that already possessed high antioxidant activity but not in cells that exhibited low activity. Cell death of low antioxidant possessing cultures was markedly enhanced by the addition of dehydroascorbate, a product of ascorbate peroxidase (APX), but not of ascorbate or reduced glutathione, and was preceded by increased metacaspase expression and activity. These data suggested that the level of APX and its products, strongly upregulated by oxidative stress, serves as a possible surveillance signal, reporting that the cells already experienced an earlier oxidative stress. Our data presents a novel role of APX in antioxidant activity and response to oxidative stress in photosynthetic microorganisms. Elimination of cysts production by phytoplankton cells that were already damaged by oxidative stress (indicated by the rise in oxidized proteins) as the inoculum for the following year's population may be the evolutionary trigger for this phenomenon.
Disturbing epithelial homeostasis in the metazoan Hydra leads to drastic changes in associated microbiota
Authors: Fraune Sebastian , Abe Yuichi , Bosch Thomas C. G. 
Published: June 2009

SummaryMicrobes have profound influence on the biology of host tissue. Imbalances in host–microbe interaction underlie many human diseases. Little, however, is known about how epithelial homeostasis affects associated microbial community structure. In Hydra, the epithelium actively shapes its microbial community indicating distinct selective pressures imposed on the epithelium. Here, using a mutant strain of Hydra magnipapillata we eliminated all derivatives of the interstitial stem cell lineage while leaving both epithelial cell lineages intact. By bacterial 16S rRNA gene analysis we observed that removing gland cells and neurones from the epithelium causes significant changes in hydra's microbial community. Absence of interstitial stem cells and nematocytes had no affect on the microbiota. When compared with controls, animals lacking neurones and gland cells showed reduced abundance of β‐Proteobacteria accompanied by a significantly increased abundance of a Bacteroidetes bacterium. This previously unrecognized link between cellular tissue composition and microbiota may be applicable to understanding mechanisms controlling host–microbe interaction in other epithelial systems.
Increased expression of OsSPX1 enhances cold/subfreezing tolerance in tobacco and Arabidopsis thaliana
Authors: Zhao Linna , Liu Fengxia , Xu Wenying , Di Chao , Zhou Shaoxia , Xue Yongbiao , Yu Jingjuan , Su Zhen 
Published: June 2009

SummaryLow temperature is a major environmental stress for plants. Many important cultivated crops have limited capacity to survive below freezing/subfreezing temperatures. Low inorganic phosphate (Pi) is reportedly important in triggering cold acclimatization. SPX (SYG1/Pho81/XPR1: SYG1, suppressor of yeast gpal; Pho81, CDK inhibitor in yeast PHO pathway; XPR1, xenotropic and polytropic retrovirus receptor) domain proteins have been shown to be involved in the phosphate‐related signal transduction and regulation pathways. Recently, Arabidopsis AtSPX family genes have been found to possess diverse functions in plant tolerance to phosphorus starvation, and OsSPX1 is involved in phosphate homeostasis in rice and optimizes growth under phosphate‐limited conditions through a negative feedback loop. In this study, our phylogenetic and gene expression profiling approaches identified six rice OsSPX genes up‐regulated during cold stress. Transgenic tobacco plants with constitutive expression of OsSPX1 were more tolerant to cold stress than were wild‐type plants, and showed better seedling survival and reduced cellular electrolyte leakage. In addition, there was decreased total leaf Pi content and accumulation of free proline and sucrose in transgenic tobacco plants during cold stress. To further establish a cause‐and‐effect relationship between intracellular Pi level and cold acclimatization in transgenic plants, we generated transgenic Arabidopsis plants with constitutive expression of OsSPX1. Cold stress resulted in reduced leaf Pi levels in Arabidopsis transgenic relative to wild‐type plants. From real‐time reverse transcriptase‐polymerase chain reaction analysis, several Pi starvation‐related genes, such as AtSPX1 (orthologue of OsSPX1), PHO2, PLDZ2 and ATSIZ1, showed differential expression between wild‐type and transgenic plants during cold stress. Our results indicate that OsSPX1 may play an important role in linking cold stress and Pi starvation signal transduction pathways.
Asymmetrical cortical processing of radial expansion / contraction in infants and adults
Authors: Shirai Nobu , Birtles Deirdre , Wattam‐Bell John , Yamaguchi Masami K. , Kanazawa So , Atkinson Janette , Braddick Oliver 
Published: June 2009

AbstractWe report asymmetrical cortical responses (steady‐state visual evoked potentials) to radial expansion and contraction in human infants and adults. Forty‐four infants (22 3‐month‐olds and 22 4‐month‐olds) and nine adults viewed dynamic dot patterns which cyclically (2.1 Hz) alternate between radial expansion (or contraction) and random directional motion. The first harmonic (F1) response in the steady‐state VEP response must arise from mechanisms sensitive to the global radial motion structure. We compared F1 amplitudes between expansion‐random and contraction‐random motion alternations. F1 amplitudes for contraction were significantly larger than those for expansion for the older infants and adults but not for the younger infants. These results suggest that the human cortical motion mechanisms have asymmetrical sensitivity for radial expansion vs. contraction, which develops at around 4 months of age. The relation between development of sensitivity to radial motion and cortical motion mechanisms is discussed.