bluuebunny/crossref_metadata_2025_split huggingface dataset:
A putative novel role for plant defensins: a defensin from the zinc hyper‐accumulating plant, Arabidopsis halleri, confers zinc tolerance
Authors: Mirouze Marie , Sels Jan , Richard Odile , Czernic Pierre , Loubet Stéphanie , Jacquier Amaury , François Isabelle E.J.A. , Cammue Bruno P.A. , Lebrun Michel , Berthomieu Pierre , Marquès Laurence 
Published: June 2006

SummaryThe metal tolerance of metal hyper‐accumulating plants is a poorly understood mechanism. In order to unravel the molecular basis of zinc (Zn) tolerance in the Zn hyper‐accumulating plant Arabidopsis halleri ssp. halleri, we carried out a functional screening of an A. halleri cDNA library in the yeast Saccharomyces cerevisiae to search for genes conferring Zn tolerance to yeast cells. The screening revealed four A. halleri defensin genes (AhPDFs), which induced Zn but not cadmium (Cd) tolerance in yeast. The expression of AhPDF1.1 under the control of the 35S promoter in A. thaliana made the transgenic plants more tolerant to Zn than wild‐type plants, but did not change the tolerance to Cd, copper (Cu), cobalt (Co), iron (Fe) or sodium (Na). Thus, AhPDF1.1 is able to confer Zn tolerance both to yeast and plants. In A. halleri, defensins are constitutively accumulated at a higher level in shoots than in A. thaliana. A. halleri defensin pools are Zn‐responsive, both at the mRNA and protein levels. In A. thaliana, some but not all defensin genes are induced by ZnCl2 treatment, and these genes are not induced by NaCl treatment. Defensins, found in a very large number of organisms, are known to be involved in the innate immune system but have never been found to play any role in metal physiology. Our results support the proposition that defensins could be involved in Zn tolerance in A. halleri, and that a role for plant defensins in metal physiology should be considered.
Cloning of two splice variants of the rice PTS1 receptor, OsPex5pL and OsPex5pS, and their functional characterization using pex5‐deficient yeast and Arabidopsis
Authors: Lee Jung Ro , Jang Ho Hee , Park Jin Ho , Jung Ji Hyun , Lee Seung Sik , Park Soo Kwon , Chi Yong Hun , Moon Jeong Chan , Lee Young Mee , Kim Sun Young , Kim Jae‐Yean , Yun Dae‐Jin , Cho Moo Je , Lee Kyun Oh , Lee Sang Yeol 
Published: June 2006

SummaryUsing the rice PEX14 cDNA as a bait in a yeast two‐hybrid assay, two splice variants of the type I peroxisomal targeting signal (PTS1) receptor, OsPex5pL and OsPex5pS, were cloned from a pathogen‐treated rice leaf cDNA library. The proteins were produced from a single gene by alternative splicing, which generated a full‐length variant, OsPEX5L, and a variant that lacked exon 7, OsPEX5S. OsPex5pL contained 11 copies of the pentapeptide motif WXXXF/Y in its N‐terminus, and seven tetratricopeptide repeats in its C‐terminus. Expression of OsPEX5L and OsPEX5S predominantly occurred in leaf tissues, and was induced by various stresses, such as exposure to the pathogen Magnaporthe grisea, and treatment with fungal elicitor, methyl viologen, NaCl or hydrogen peroxide. The Arabidopsis T‐DNA insertional pex5 mutant, Atpex5, which does not germinate in the absence of sucrose and was resistant to indole‐3‐butyric acid (IBA), was perfectly rescued by over‐expression of OsPex5pL, but not by OsPex5pS. Using transient expression of OsPex5pL and OsPex5pS in the Atpex5 mutant, we show that OsPex5pL translocates both PTS1‐ and PTS2‐containing proteins into the peroxisome by interacting with OsPex7p, whereas OsPex5pS is involved only in PTS1‐dependent import in Arabidopsis.
Pseudomonas syringae effector AvrPtoB suppresses basal defence in Arabidopsis
Authors: De Torres Marta , Mansfield John W. , Grabov Nina , Brown Ian R. , Ammouneh Hassan , Tsiamis George , Forsyth Alec , Robatzek Silke , Grant Murray , Boch Jens 
Published: June 2006

SummaryThe virulence and avirulence activities of members of the Pseudomonas syringae HopAB family of effectors and AvrPto were examined in bean, tomato and Arabidopsis. Proteins were delivered by the RW60 strain of P. syringae pv. phaseolicola. RW60 causes a hypersensitive reaction (HR) in bean and tomato but is restricted without the HR in Arabidopsis. Dual avirulence and virulence functions in tomato and bean, respectively, were identified in virPphA homologues but only avrPtoB strongly enhanced virulence to Arabidopsis, overcoming basal defences operating against RW60. Virulence activity in both bean and Arabidopsis required regions of the C‐terminus of the AvrPtoB protein, whereas elicitation of the rapid HR in tomato, with the matching Pto resistance gene, did not. The effect of AvrPtoB on Arabidopsis was accession‐specific; most obvious in Wassilewskija (Ws‐3), intermediate in Columbia and not detectable in Niedersenz (Nd‐1) after inoculation with RW60 + avrPtoB. Analysis of crosses between Ws‐3 and Nd‐1 indicated co‐segregation for the AvrPtoB virulence function with the absence of the Nd‐1 FLS2 gene which mediates recognition of bacterial flagellin. In planta expression of AvrPtoB did not prevent the HR activated by P. syringae pv. tomato DC3000 + avrB, avrRpm1, avrRps4 or avrRpt2, but suppressed cell wall alterations, including callose deposition, characteristic of basal defence and was associated with reprogramming of the plant's transcriptional response. The success or failure of AvrPtoB in suppressing basal defences in Nd‐1 depended on the timing of exposure of plant cells to the effector and the flagellin flg22 peptide.
CUL4 associates with DDB1 and DET1 and its downregulation affects diverse aspects of development in Arabidopsis thaliana
Authors: Bernhardt Anne , Lechner Esther , Hano Perdita , Schade Verena , Dieterle Monika , Anders Marco , Dubin Manu Jody , Benvenuto Giovanna , Bowler Chris , Genschik Pascal , Hellmann Hanjo 
Published: June 2006

SummaryCullins are central scaffolding subunits in eukaryotic E3 ligases that facilitate the ubiquitination of target proteins. Arabidopsis contains at least 11 cullin proteins but only a few of them have been assigned biological roles. In this work Arabidopsis cullin 4 is shown to assemble with DDB1, RBX1, DET1 and DDB2 in vitro and in planta. In addition, by using T‐DNA insertion and CUL4 antisense lines we demonstrate that corresponding mutants are severely affected in different aspects of development. Reduced CUL4 expression leads to a reduced number of lateral roots, and to abnormal vascular tissue and stomatal development. Furthermore, cul4 mutants display a weak constitutive photomorphogenic phenotype. These results therefore assign an important function to CUL4 during plant development and provide strong evidence that CUL4 assembles together with RBX1 and DDB1 proteins to form a functional E3 ligase in Arabidopsis.
High genetic divergences indicate ancient separation of parthenogenetic lineages of the oribatid mite Platynothrus peltifer (Acari, Oribatida)
Authors: Heethoff M. , Domes K. , Laumann M. , Maraun M. , Norton R. A. , Scheu S. 
Published: June 2006

Abstract
Theories on the evolution and maintenance of sex are challenged by the existence of ancient parthenogenetic lineages such as bdelloid rotifers and darwinulid ostracods. It has been proposed that several parthenogenetic and speciose taxa of oribatid mites (Acari) also have an ancient origin. We used nucleotide sequences of the mitochondrial gene cytochrome oxidase I to estimate the age of the parthenogenetic oribatid mite species Platynothrus peltifer. Sixty-five specimens from 16 sites in North America, Europe and Asia were analysed. Seven major clades were identified. Within-clade genetic distances were below 2 % similar to the total intraspecific genetic diversity of most organisms. However, distances between clades averaged 56 % with a maximum of 125 %. We conclude that P. peltifer, as it is currently conceived, has existed for perhaps 100 million years, has an extant distribution that results from continental drift rather than dispersal and was subject to several cryptic speciations.
Biphonation May Function to Enhance Individual Recognition in the Dhole, Cuon alpinus
Authors: Volodina Elena V. , Volodin Ilya A. , Isaeva Irina V. , Unck Carolyn 
Published: June 2006

AbstractBiphonation (two independent fundamental frequencies in a call spectrum) represents one of the most widespread nonlinear phenomena in mammalian vocalizations. Recently, the structure of biphonations was described in detail; however, their functions are poorly understood. For the dhole (Cuon alpinus), biphonic calls represent a prominent feature of vocal activity. In this species, the biphonic call is composed of two frequency components – the high‐frequency squeak and the low‐frequency yap, which also occur alone as separate calls. In this study, we test the hypothesis that the complication of call structure, resulting from the joining of these calls into the biphonic yap–squeak may enhance the potential for individual recognition in the dhole. We randomly selected for analysis 30 high‐frequency squeaks, 30 low‐frequency yaps and 30 biphonic yap–squeaks per animal from five subadult captive dholes (450 calls in total). Discriminant analysis, based on 10 squeak parameter values, showed 80.7% correct assignment to a predicted individual. For 10 yap parameters, the correct assignment was only 44.7%. However, the analysis based on 10 parameters of the biphonic yap–squeak, selected as best contributing to discrimination, showed 96.7% correct assignment to a predicted individual. The results provide strong support for the hypothesis tested showing that the joining of two independent calls into a common vocalization may function to enhance individual recognition in the dhole.
Signal Interception and the Use of Soft Song in Aggressive Interactions
Authors: Searcy William A. , Nowicki Stephen 
Published: June 2006

AbstractSong sparrows, like many species of songbirds, produce songs of especially low amplitude during aggressive contests. Such ‘soft songs’ have been shown to be reliable signals of intention to attack in song sparrows. Low intensity is a paradoxical feature in a highly aggressive signal, in that it seems likely to make the signal less intimidating to an opponent. A hypothesis that resolves this paradox is that use of soft songs benefits a signaler by limiting the interception of his signals by third party receivers. Here, we test this hypothesis with respect to song sparrows and two classes of third party receivers, predators and conspecific males. We tested whether selection to avoid predation is responsible for use of soft song by examining whether male song sparrows increase production of soft song in an aggressive context when they also receive signals (alarm calls) that indicate a predator is present. We found that the proportion of soft song produced by male song sparrows was actually significantly lower in the predator context than in a control context, directly contradicting the prediction. We tested whether avoiding eavesdropping by conspecific males is a benefit of soft song by removing territory owners and simulating interactions on their territories using playback from two loudspeakers. We found that intrusions by third party males were more likely in trials in which the simulated owner countered an intruder's songs using soft songs than in trials in which the simulated owner countered with loud song, again directly contradicting the hypothesis. We conclude that limiting interception by predators and conspecific males does not provide an explanation for use of soft song by song sparrows.
Phenotypic Correlates of Scrounging Behavior in Zebra Finches: Role of Foraging Efficiency and Dominance
Authors: Beauchamp G. 
Published: June 2006

AbstractIn flocks, individuals can search for their own food using the producer tactic or exploit the discoveries of companions using the scrounger tactic. Models of the producer–scrounger game usually assume that tactic payoffs are independent of individual phenotypic traits. However, factors such as dominance status or foraging efficiency may constrain the use of tactics and lead to asymmetric tactic use among individuals. For instance, in flocks composed of foragers with unequal foraging efficiency, foragers that are less efficient at obtaining food are expected to rely on the scrounger tactic to a greater extent. I examined the role of foraging efficiency and dominance status as potential correlates of scrounging behavior in small aviary flocks of zebra finches (Taenopygia guttata). Individual foraging efficiency was documented in each flock in a treatment that prevented scrounging. In a subsequent treatment that allowed scrounging, higher levels of scrounging occurred as predicted in foragers with lower foraging efficiency. Dominance status was a poor predictor of tactic choice. Birds that arrived later on the foraging grid foraged less efficiently when scrounging was prevented and used scrounging to a greater extent when allowed, suggesting a link between boldness, foraging efficiency and the choice of foraging tactics in small flocks of zebra finches.
Vigilance and Collective Detection of Predators in Degus (Octodon degus)
Authors: Ebensperger Luis A. , Hurtado María José , Ramos‐Jiliberto Rodrigo 
Published: June 2006

AbstractIndividuals of social and partially social species typically reduce their vigilance activity when foraging in groups. As a result, per capita risk of predation decreases and individuals allocate more time to foraging and other fitness rewarding activities. Reduction of per capita risk is hypothesized to occur because there are more individuals to detect potential predators. If so, collective (i.e. total) vigilance is expected to increase with foraging group size. Increased surveillance during group foraging may occur if group members scan independently of one another, or sequentially to avoid the overlapping of their vigilance bouts. Intriguingly, such coordinated vigilance assumes that individuals monitor not only the presence, but the vigilance behaviour of group mates. We used seasonal records on time budget and grouping patterns of individually marked degus (Octodon degus), a social rodent, to examine if (a) individual vigilance decreases and/or foraging increases with group size, (b) collective vigilance increases with group size and (c) foraging degus coordinate their vigilance. When foraging, degus decreased their individual vigilance and increased their foraging time when in larger groups. Despite this, degus in larger groups increased their collective vigilance, supporting the hypothesis that socially foraging degus decrease predation risk through an improved ability to detect and escape potential predators. Additionally, patterns of collective vigilance suggested that degus scan independently of each other and so, they do not coordinate their vigilance to prevent its temporal overlapping. This finding does not support that foraging degus monitor the vigilance activity of group mates.
RENAL PREGLOMERULAR ARTERIAL–VENOUS O2 SHUNTING IS A STRUCTURAL ANTI‐OXIDANT DEFENCE MECHANISM OF THE RENAL CORTEX
Authors: O’Connor Paul M , Anderson Warwick P , Kett Michelle M , Evans Roger G 
Published: June 2006

SUMMARY

High blood flow to the kidney facilitates a high glomerular filtration rate, but total renal O2 delivery greatly exceeds renal metabolic requirements. However, tissue Po2 in much of the renal cortex is lower than may be expected, being similar to that of other organs in which perfusion is closely matched to metabolic demand.
The lower than expected renal cortical Po2 is now attributed largely to diffusional shunting of as much as 50% of inflowing O2 from blood within preglomerular arterial vessels to post‐glomerular venous vessels. However, the functional significance of this O2 shunting remains unclear. Indeed, this mechanism may appear maladaptive, given the kidney's susceptibility to hypoxic insults.
We hypothesize that renal preglomerular arterial–venous O2 shunting acts to protect the kidney from the potentially damaging consequences of tissue hyperoxia. The diffusion of O2 from arteries to veins within the kidney acts to reduce the O2 content of the blood before it is distributed to the renal microcirculation. Because high tissue Po2 may increase the production of reactive oxygen species, we suggest that renal arterial–venous O2 shunting may provide a physiological benefit to the organism by limiting O2 delivery to renal tissue, thereby reducing the risk of cellular oxidation.
MECHANOSENSITIVE ION CHANNELS IN SKELETAL MUSCLE: A LINK IN THE MEMBRANE PATHOLOGY OF MUSCULAR DYSTROPHY
Authors: Lansman Jeffry B , Franco‐Obregón Alfredo 
Published: June 2006

SUMMARY

Mechanosensitive (MS) channels are expressed abundantly in skeletal muscle at all stages of development. In recordings from membrane patches, MS channels are constitutively active at the resting potential. The channels are selective for cations and have a large single‐channel conductance (approximately 25 pS in physiological saline) and a high Ca2+ permeability (relative permeability of Ca2+ to K+ (PCa/PK) = 7).
Mechanosensitive channel activity recorded from the surface of myotubes from dystrophic mdx mice was substantially greater than the activity recorded from wild‐type myotubes. Increased channel activity in the mutant results from the induction in a subpopulation of channels of a novel MS gating mode characterized by markedly prolonged channel openings and inactivation in response to membrane stretch.
Membrane stretch or a strong depolarization causes an irreversible switch to the stretch‐inactivated gating mode in mdx myotubes. A stretch‐induced shift in MS channel gating mode may contribute to stretch‐induced elevations in [Ca2+]i during the early stages of disease pathogenesis.
Abnormalities of MS channel behaviour are also detected in recordings from patches on flexor digitorum brevis fibres acutely isolated from mdx mice. Mechanosensitive channel opening probability is higher in mdx fibres at all developmental stages. In addition, channel numbers are persistently elevated during postnatal development, failing to undergo a normal process of downregulation during the first 3 postnatal weeks.
Two distinct mechanisms may contribute to elevations of [Ca2+]i in dystrophin‐deficient skeletal muscle: (i) a membrane stress‐dependent switch of MS channels into to a prolonged opening mode; and (ii) a loss of developmental downregulation leading to persistent MS channel expression during postnatal muscle development.
MUSCLE DAMAGE IN MDX (DYSTROPHIC) MICE: ROLE OF CALCIUM AND REACTIVE OXYGEN SPECIES
Authors: Whitehead Nicholas P , Yeung Ella W , Allen David G 
Published: June 2006

SUMMARY

Duchenne muscular dystrophy (DMD) is a lethal, degenerative muscle disease caused by a genetic mutation that leads to the complete absence of the cytoskeletal protein dystrophin in muscle fibres.
The present review provides an overview of some of the physiological pathways that may contribute to muscle damage and degeneration in DMD, based primarily on experimental findings in the mdx mouse, an animal model of this disease.
A rise in intracellular calcium is widely thought to be an important initiating event in the dystrophic pathogenesis. The pathway(s) leading to increased intracellular calcium in dystrophin deficient muscle is uncertain, but recent work from our laboratory provides evidence that stretch‐activated channels are an important source of the calcium influx. Other possible routes of calcium entry are also discussed.
The consequences of elevated cytosolic calcium may include activation of proteases, such as calpain, and increased production of reactive oxygen species (ROS), which can cause protein and membrane damage.
Another possible cause of damage in dystrophic muscle involves inflammatory pathways, such as those mediated by neutrophils, macrophages and associated cytokines. There is recent evidence that increased ROS may be important in both the activation of and the damage caused by this inflammatory pathway in mdx muscle.
5‐HYDROXYTRYPTAMINE IN THE CARDIOVASCULAR SYSTEM: FOCUS ON THE SEROTONIN TRANSPORTER (SERT)
Authors: Ni Wei , Watts Stephanie W 
Published: June 2006

SUMMARY

The function of the serotonin transporter (SERT) is to take up and release serotonin (5‐hydroxytyptamine (5‐HT)) from cells and this function of SERT in the central nervous system (CNS) is well‐documented; SERT is the target of selective serotonin reuptake inhibitors used in the treatment of CNS disorders, such as depression.
The aim of the present review is to discuss our current knowledge of 5‐HT and SERT in the cardiovascular (CV) system, as well as their function in physiological and pathophysiological states.
The SERT protein has been located in multiple CV tissues, including the heart, blood vessels, brain, platelets, adrenal gland and kidney. Modification of SERT function occurs at both transcriptional and translational levels. The functions of SERT in these tissues is largely unexplored, but includes modulation of cardiac and smooth muscle contractility, platelet aggregation, cellular mitogenesis, modulating neuronal activity and urinary excretion.
Recent studies have uncovered potential relationships between the expression of SERT gene promoter variants (long (l) or short (s)) with CV diseases. Specifically, the risk of myocardial infarction and pulmonary hypertension is increased with expression of the ll promoter, a variant associated with increased expression and function of SERT. The relationship between promoter variants and other CV diseases has not been investigated.
Newly available experimental tools, such as pharmacological compounds and genetically altered mice, should prove useful in the investigation of the function of SERT in the CV system.
In summary, the function of SERT in the CV system is just beginning to be revealed.
THERMAL PRECONDITIONING PROTECTS THE HUMAN INTERNAL MAMMARY ARTERY FROM HYPOXIA/RE‐OXYGENATION‐INDUCED DAMAGE
Authors: Hammerer‐Lercher Angelika , Haeusler Christa , Prelog Martina , Bonatti Johannes , Hoefer Daniel , Ruttmann Elfriede , Laufer Guenther , Werner Ernst R , Dirnhofer Stephan , Puschendorf Bernd , Mair Johannes 
Published: June 2006

SUMMARY

Preconditioning has been demonstrated to ameliorate ischaemia/reperfusion injury in several cells and tissues. Therefore, in the present study we investigated whether preconditioning of human bypass grafts, internal mammary artery (IMA) and saphenous vein (SV) induces heat shock protein (Hsp) expression and reduces apoptosis in response to subsequent hypoxia/re‐oxygenation damage in both vessels.
Internal mammary artery and SV rings, obtained from 30 patients (median age 66.5 years) undergoing coronary artery bypass grafting, were either incubated for 30 min at 42°C (preconditioned) or kept in a standard incubator at 37°C (not preconditioned). Six hours later, graft segments were exposed to 90 min hypoxia followed by a 30 min re‐oxygenation period. Western blot, real‐time quantative polymerase chain reaction analysis and apoptosis detection by the Terminal deoxyribonucleotidyl transferase‐mediated dUTP–digoxigenin nick end‐labelling method were performed.
Heat‐preconditioned IMA showed significantly increased protein expression of Hsp72 after hypoxia/re‐oxygenation treatment compared with controls (median 9.1 vs 5.0 µg/mg total protein; P = 0.048). Expression of Hsp73 was weak and Hsp60 was not detectable in the IMA.
In the SV, neither protein nor mRNA expression of Hsp were significantly different between preconditioned and not preconditioned veins.
There were significantly fewer apoptotic cells in the intima of the preconditioned compared with not preconditioned IMA (P = 0.041) after hypoxia/re‐oxygenation injury, whereas in the SV apoptosis was not significantly prevented by preconditioning.
Mild heat preconditioning before hypoxia/re‐oxygenation injury is a stimulus for Hsp72 protein expression and a reduction in apoptosis in the human IMA.