bluuebunny/crossref_metadata_2025 huggingface dataset:
Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations
Authors: Westendorf Christian , Negrete Jose , Bae Albert J. , Sandmann Rabea , Bodenschatz Eberhard , Beta Carsten
Published: February 2013

The rapid reorganization of the actin cytoskeleton in response to external stimuli is an essential property of many motile eukaryotic cells. Here, we report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. When averaging the actin response of many cells to a short pulse of the chemoattractant cAMP, we observed a transient accumulation of cortical actin reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. To substantiate that an oscillatory mechanism governs the actin dynamics in these cells, we systematically exposed a large number of cells to periodic pulse trains of different frequencies. Our results indicate a resonance peak at a stimulation period of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the regulatory network of the actin system. To test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and actin-interacting protein 1, as well as knockout mutants that lack Coronin and actin-interacting protein 1. These actin-binding proteins enhance the disassembly of actin filaments and thus allow us to estimate the delay time in the regulatory feedback loop. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed in our periodic stimulation experiments.
Calcium-activated chloride channel ANO1 promotes breast cancer progression by activating EGFR and CAMK signaling
Authors: Britschgi Adrian , Bill Anke , Brinkhaus Heike , Rothwell Christopher , Clay Ieuan , Duss Stephan , Rebhan Michael , Raman Pichai , Guy Chantale T. , Wetzel Kristie , George Elizabeth , Popa M. Oana , Lilley Sarah , Choudhury Hedaythul , Gosling Martin , Wang Louis , Fitzgerald Stephanie , Borawski Jason , Baffoe Jonathan , Labow Mark , Gaither L. Alex , Bentires-Alj Mohamed
Published: February 2013

The calcium-activated chloride channel anoctamin 1 (
ANO1
) is located within the 11q13 amplicon, one of the most frequently amplified chromosomal regions in human cancer, but its functional role in tumorigenesis has remained unclear. The 11q13 region is amplified in ∼15% of breast cancers. Whether
ANO1
is amplified in breast tumors, the extent to which gene amplification contributes to ANO1 overexpression, and whether overexpression of ANO1 is important for tumor maintenance have remained unknown. We have found that ANO1 is amplified and highly expressed in breast cancer cell lines and primary tumors. Amplification of
ANO1
correlated with disease grade and poor prognosis. Knockdown of ANO1 in ANO1-amplified breast cancer cell lines and other cancers bearing 11q13 amplification inhibited proliferation, induced apoptosis, and reduced tumor growth in established cancer xenografts. Moreover, ANO1 chloride channel activity was important for cell viability. Mechanistically, ANO1 knockdown or pharmacological inhibition of its chloride-channel activity reduced EGF receptor (EGFR) and calmodulin-dependent protein kinase II (CAMKII) signaling, which subsequently attenuated AKT, v-src sarcoma viral oncogene homolog (SRC), and extracellular signal-regulated kinase (ERK) activation in vitro and in vivo. Our results highlight the involvement of the ANO1 chloride channel in tumor progression and provide insights into oncogenic signaling in human cancers with 11q13 amplification, thereby establishing ANO1 as a promising target for therapy in these highly prevalent tumor types.
UBR box N-recognin-4 (UBR4), an N-recognin of the N-end rule pathway, and its role in yolk sac vascular development and autophagy
Authors: Tasaki Takafumi , Kim Sung Tae , Zakrzewska Adriana , Lee Bo Eun , Kang Min Jueng , Yoo Young Dong , Cha-Molstad Hyun Joo , Hwang Joonsung , Soung Nak Kyun , Sung Ki Sa , Kim Su-Hyeon , Nguyen Minh Dang , Sun Ming , Yi Eugene C. , Kim Bo Yeon , Kwon Yong Tae
Published: February 2013

The N-end rule pathway is a proteolytic system in which destabilizing N-terminal residues of short-lived proteins act as degradation determinants (N-degrons). Substrates carrying N-degrons are recognized by N-recognins that mediate ubiquitylation-dependent selective proteolysis through the proteasome. Our previous studies identified the mammalian N-recognin family consisting of UBR1/E3α, UBR2, UBR4/p600, and UBR5, which recognize destabilizing N-terminal residues through the UBR box. In the current study, we addressed the physiological function of a poorly characterized N-recognin, 570-kDa UBR4, in mammalian development. UBR4-deficient mice die during embryogenesis and exhibit pleiotropic abnormalities, including impaired vascular development in the yolk sac (YS). Vascular development in UBR4-deficient YS normally advances through vasculogenesis but is arrested during angiogenic remodeling of primary capillary plexus associated with accumulation of autophagic vacuoles. In the YS, UBR4 marks endoderm-derived, autophagy-enriched cells that coordinate differentiation of mesoderm-derived vascular cells and supply autophagy-generated amino acids during early embryogenesis. UBR4 of the YS endoderm is associated with a tissue-specific autophagic pathway that mediates bulk lysosomal proteolysis of endocytosed maternal proteins into amino acids. In cultured cells, UBR4 subpopulation is degraded by autophagy through its starvation-induced association with cellular cargoes destined to autophagic double membrane structures. UBR4 loss results in multiple misregulations in autophagic induction and flux, including synthesis and lipidation/activation of the ubiquitin-like protein LC3 and formation of autophagic double membrane structures. Our results suggest that UBR4 plays an important role in mammalian development, such as angiogenesis in the YS, in part through regulation of bulk degradation by lysosomal hydrolases.
Altered temporal response of malaria parasites determines differential sensitivity to artemisinin
Authors: Klonis Nectarios , Xie Stanley C. , McCaw James M. , Crespo-Ortiz Maria P. , Zaloumis Sophie G. , Simpson Julie A. , Tilley Leann
Published: February 2013

Reports of emerging resistance to first-line artemisinin antimalarials make it critical to define resistance mechanisms and identify in vitro correlates of resistance. Here we combine unique in vitro experimental and analytical approaches to mimic in vivo drug exposure in an effort to provide insight into mechanisms of drug resistance. Tightly synchronized parasites exposed to short drug pulses exhibit large stage-dependent differences in their drug response that correlate with hemoglobin digestion throughout most of the asexual cycle. As a result, ring-stage parasites can exhibit >100-fold lower sensitivity to short drug pulses than trophozoites, although we identify a subpopulation of rings (2–4 h postinvasion) that exhibits hypersensitivity. We find that laboratory strains that show little differences in drug sensitivity in standard in vitro assays exhibit substantial (>95-fold) difference in sensitivity when exposed to short drug pulses. These stage- and strain-dependent differences in drug sensitivity reflect differential response lag times with rings exhibiting lag times of up to 4 h. A simple model that assumes that the parasite experiences a saturable effective drug dose describes the complex dependence of parasite viability on both drug concentration and exposure time and is used to demonstrate that small changes in the parasite’s drug response profile can dramatically alter the sensitivity to artemisinins. This work demonstrates that effective resistance can arise from the interplay between the short in vivo half-life of the drug and the stage-specific lag time and provides the framework for understanding the mechanisms of drug action and parasite resistance.
Disparities in voltage-sensor charge and electromotility imply slow chloride-driven state transitions in the solute carrier SLC26a5
Authors: Song Lei , Santos-Sacchi Joseph
Published: February 2013

Outer hair cells (OHCs) drive cochlear amplification that enhances our ability to detect and discriminate sounds. The motor protein, prestin, which evolved from the SLC26 anion transporter family, underlies the OHC’s voltage-dependent mechanical activity (eM). Here we report on simultaneous measures of prestin’s voltage-sensor charge movement (nonlinear capacitance, NLC) and eM that evidence disparities in their voltage dependence and magnitude as a function of intracellular chloride, challenging decades’ old dogma that NLC reports on eM steady-state behavior. A very simple kinetic model, possessing fast anion-binding transitions and fast voltage-dependent transitions, coupled together by a much slower transition recapitulates these disparities and other biophysical observations on the OHC. The intermediary slow transition probably relates to the transporter legacy of prestin, and this intermediary gateway, which shuttles anion-bound molecules into the voltage-enabled pool of motors, provides molecular delays that present as phase lags between membrane voltage and eM. Such phase lags may help to effectively inject energy at the appropriate moment to enhance basilar membrane motion.
Metabotropic NMDA receptor function is required for NMDA receptor-dependent long-term depression
Authors: Nabavi Sadegh , Kessels Helmut W. , Alfonso Stephanie , Aow Jonathan , Fox Rocky , Malinow Roberto
Published: February 2013

NMDA receptor (NMDAR) activation controls long-term potentiation (LTP) as well as long-term depression (LTD) of synaptic transmission, cellular models of learning and memory. A long-standing view proposes that a high level of Ca
2+
entry through NMDARs triggers LTP; lower Ca
2+
entry triggers LTD. Here we show that ligand binding to NMDARs is sufficient to induce LTD; neither ion flow through NMDARs nor Ca
2+
rise is required. However, basal levels of Ca
2+
are permissively required. Lowering, but not maintaining, basal Ca
2+
levels with Ca
2+
chelators blocks LTD and drives strong synaptic potentiation, indicating that basal Ca
2+
levels control NMDAR-dependent LTD and basal synaptic transmission. Our findings indicate that metabotropic actions of NMDARs can weaken active synapses without raising postsynaptic calcium, thereby revising and expanding the mechanisms controlling synaptic plasticity.
Zebrafish model for allogeneic hematopoietic cell transplantation not requiring preconditioning
Authors: Hess Isabell , Iwanami Norimasa , Schorpp Michael , Boehm Thomas
Published: February 2013

Recent work on vertebrate hematopoiesis has uncovered the presence of deeply rooted similarities between fish and mammals at molecular and cellular levels. Although small animal models such as zebrafish are ideally suited for genetic and chemical screens, the study of cellular aspects of hematopoietic development in lower vertebrates is severely hampered by the complex nature of their histocompatibility-determining genes. Hence, even when hosts are sublethally irradiated before hematopoietic cell transplantation, stable and long-term reconstitution by allogeneic stem cells often fails. Here, we describe the unexpected observation that transplantation and maintenance of allogeneic hematopoietic stem cells in zebrafish homozygous for the
c-myb
t25127
allele, carrying a missense mutation (Ile181Asn) in the DNA binding domain can be achieved without prior conditioning. Using this model, we examined several critical parameters of zebrafish hematopoiesis in a near-physiological setting. Limiting dilution analysis suggests that the kidney marrow of adult zebrafish harbors about 10 transplantable hematopoietic stem cells; this tissue also contains thymus-settling precursors that colonize the thymic rudiment within days after transplantation and initiate robust T-cell development. We also demonstrate that
c-myb
mutants can be stably reconstituted with hematopoietic cells carrying specific genetic defects in lymphocyte development, exemplifying one of the many potential uses of this model in experimental hematology.
Generation of a stable, aminotyrosyl radical-induced α2β2 complex of
Escherichia coli
class Ia ribonucleotide reductase
Authors: Minnihan Ellen C. , Ando Nozomi , Brignole Edward J. , Olshansky Lisa , Chittuluru Johnathan , Asturias Francisco J. , Drennan Catherine L. , Nocera Daniel G. , Stubbe JoAnne
Published: February 2013

Ribonucleotide reductase (RNR) catalyzes the conversion of nucleoside diphosphates to deoxynucleoside diphosphates (dNDPs). The
Escherichia coli
class Ia RNR uses a mechanism of radical propagation by which a cysteine in the active site of the RNR large (α2) subunit is transiently oxidized by a stable tyrosyl radical (Y•) in the RNR small (β2) subunit over a 35-Å pathway of redox-active amino acids: Y
122
• ↔ [W
48
?] ↔ Y
356
in β2 to Y
731
↔ Y
730
↔ C
439
in α2. When 3-aminotyrosine (NH
2
Y) is incorporated in place of Y
730
, a long-lived NH
2
Y
730
• is generated in α2 in the presence of wild-type (wt)-β2, substrate, and effector. This radical intermediate is chemically and kinetically competent to generate dNDPs. Herein, evidence is presented that NH
2
Y
730
• induces formation of a kinetically stable α2β2 complex. Under conditions that generate NH
2
Y
730
•, binding between Y
730
NH
2
Y-α2 and wt-β2 is 25-fold tighter (
K
d
= 7 nM) than for wt-α2|wt-β2 and is cooperative. Stopped-flow fluorescence experiments establish that the dissociation rate constant for the Y
730
NH
2
Y-α2|wt-β2 interaction is ∼10
4
-fold slower than for the wt subunits (∼60 s
−1
). EM and small-angle X-ray scattering studies indicate that the stabilized species is a compact globular α2β2, consistent with the structure predicted by Uhlin and Eklund’s docking model [Uhlin U, Eklund H (1994)
Nature
370(6490):533–539]. These results present a structural and biochemical characterization of the active RNR complex “trapped” during turnover, and suggest that stabilization of the α2β2 state may be a regulatory mechanism for protecting the catalytic radical and ensuring the fidelity of its reactivity.
Molecular chaperoning function of Ric-8 is to fold nascent heterotrimeric G protein α subunits
Authors: Chan PuiYee , Thomas Celestine J. , Sprang Stephen R. , Tall Gregory G.
Published: February 2013

We have shown that resistance to inhibitors of cholinesterase 8 (Ric-8) proteins regulate an early step of heterotrimeric G protein α (Gα) subunit biosynthesis. Here, mammalian and plant cell-free translation systems were used to study Ric-8A action during Gα subunit translation and protein folding. Gα translation rates and overall produced protein amounts were equivalent in mock and Ric-8A–immunodepleted rabbit reticulocyte lysate (RRL). GDP-AlF
4
−
–bound Gαi, Gαq, Gα13, and Gαs produced in mock-depleted RRL had characteristic resistance to limited trypsinolysis, showing that these G proteins were folded properly. Gαi, Gαq, and Gα13, but not Gαs produced from Ric-8A–depleted RRL were not protected from trypsinization and therefore not folded correctly. Addition of recombinant Ric-8A to the Ric-8A–depleted RRL enhanced GDP-AlF
4
−
–bound Gα subunit trypsin protection. Dramatic results were obtained in wheat germ extract (WGE) that has no endogenous Ric-8 component. WGE-translated Gαq was gel filtered and found to be an aggregate. Ric-8A supplementation of WGE allowed production of Gαq that gel filtered as a ∼100 kDa Ric-8A:Gαq heterodimer. Addition of GTPγS to Ric-8A–supplemented WGE Gαq translation resulted in dissociation of the Ric-8A:Gαq heterodimer and production of functional Gαq-GTPγS monomer. Excess Gβγ supplementation of WGE did not support functional Gαq production. The molecular chaperoning function of Ric-8 is to participate in the folding of nascent G protein α subunits.
Hydration of metal surfaces can be dynamically heterogeneous and hydrophobic
Authors: Limmer David T. , Willard Adam P. , Madden Paul , Chandler David
Published: February 2013

We have applied molecular dynamics and methods of importance sampling to study structure and dynamics of liquid water in contact with metal surfaces. The specific surfaces considered resemble the 100 and 111 faces of platinum. Several results emerge that should apply generally, not just to platinum. These results are generic consequences of water molecules binding strongly to surfaces that are incommensurate with favorable hydrogen-bonding patterns. We show that adlayers of water under these conditions have frustrated structures that interact unfavorably with adjacent liquid water. We elucidate dynamical processes of water in these cases that extend over a broad range of timescales, from less than picoseconds to more than nanoseconds. Associated spatial correlations extend over nanometers. We show that adlayer reorganization occurs intermittently, and each reorganization event correlates motions of several molecules. We show that soft liquid interfaces form adjacent to the adlayer, as is generally characteristic of liquid water adjacent to a hydrophobic surface. The infrequent adlayer reorganization produces a hydrophobic heterogeneity that we characterize by studying the degrees by which different regions of the adlayers attract small hydrophobic particles. Consequences for electrochemistry are discussed in the context of hydronium ions being attracted from the liquid to the metal–adlayer surface.
Resilience of Pink Salmon and Chum Salmon to Simulated Fisheries Capture Stress Incurred upon Arrival at Spawning Grounds
Authors: Raby Graham D. , Cooke Steven J. , Cook Katrina V. , McConnachie Sarah H. , Donaldson Michael R. , Hinch Scott G. , Whitney Charlotte K. , Drenner S. Matthew , Patterson David A. , Clark Timothy D. , Farrell Anthony P.
Published: February 2013

We compared exhaustion‐related physiological stress and physical injury as contributors to fish condition, longevity, and egg retention in two Pacific salmon species after their arrival at spawning areas. Adult female Pink Salmon Oncorhynchus gorbuscha and Chum Salmon O. keta were exposed to six experimental capture treatments that represented different levels of exhaustive exercise, air exposure, and injury. After we evaluated its reflex impairment and obtained a blood sample, each fish was released into its natal spawning channel with an external tag and later retrieved postmortem to evaluate spawning success via examining egg retention. Reflex impairment, plasma lactate, chloride, potassium, and osmolality varied among treatments, with differences generally driven by the length of exposure to capture stress, which included exhaustive exercise and air exposure. However, overall prespawn mortality was negligible (about 5%) and consistent across treatments for both species. We hypothesize that Pink and Chum Salmon are resilient to capture‐related exhaustion upon reaching spawning areas because of a combination of low water temperature (about 12°C in this study) and a physiological shift towards increased use of anaerobic pathways during their final weeks of life. The capture and release of fish arriving at the spawning ground does not appear to influence survival, in contradiction to the results of other studies, which focused on earlier components of Pacific salmon spawning migrations. Fisheries adjacent to spawning sites represent the end of the continuum of salmon fisheries that begin with the high seas fishery and extend through the coastal and riverine environments. The mortality rates in this study should be interpreted cautiously by management until research efforts are broadened to provide a better understanding of how postrelease outcomes at different life stages compare in natural systems and under conditions more representative of real fisheries.
Unbiased Methods for Calculating Mortality in Mark-Selective Fisheries Models for Ocean Salmon
Authors: Conrad Robert , Hagen-Breaux Angelika , Yuen Henry
Published: February 2013

Mark-selective fisheries (MSF) are increasingly being used as a strategy for managing fisheries for Coho Salmon Oncorhynchus kisutch and Chinook Salmon O. tshawytscha on the west coast of North America. Mark-selective fisheries allow anglers to keep legal-size Coho Salmon or Chinook Salmon with a missing adipose fin (typically hatchery fish) and require the release of those with an adipose fin (unmarked fish, which are usually wild fish). The objective of MSF is to provide meaningful fisheries on abundant stocks of hatchery salmon while reducing the impact on wild (unmarked) salmon stocks. As has been previously shown, the model currently used in the Pacific Fishery Management Council's preseason planning process to project mortalities for proposed Coho Salmon and Chinook Salmon fisheries underestimates the number of unmarked salmon mortalities occurring in MSF and concurrent nonselective fisheries. We propose equations that provide unbiased estimates of salmon mortalities that occur in these fisheries due to the release of fish. The performance of the proposed methods is evaluated and compared to the current methods using a simulation model. The methods are shown to provide unbiased calculations of total mortalities for unmarked salmon in both mark-selective and concurrent nonselective fisheries. The unbiased methods are able to incorporate different release-mortality and mark-recognition rates for the fisheries modeled.

Received July 24, 2012; accepted November 26, 2012
Contrasting life history characteristics of the eightbar grouper Hyporthodus octofasciatus (Pisces: Epinephelidae) over a large latitudinal range reveals spawning omission at higher latitudes
Authors: Wakefield Corey B. , Newman Stephen J. , Marriott Ross J. , Boddington Dion K. , Fairclough David V.
Published: February 2013

Wakefield, C. B., Newman, S. J., Marriott, R. J., Boddington, D. K., and Fairclough, D. V. 2013. Contrasting life history characteristics of the eightbar grouper, Hyporthodus octofasciatus (Pisces: Epinephelidae), over a large latitudinal range reveals spawning omission at higher latitudes. – ICES Journal of Marine Science, 70: 485–497. Demographic data on deep-water groupers are limited despite them being highly exploited throughout the Indo-Pacific. In Western Australia, the continuous distribution of the eightbar grouper, Hyporthodus octofasciatus, spans tropical to temperate waters over ∼3500 km from 12°S–35°S. The maximum age was markedly higher in the northern tropical waters than in southern temperate waters, i.e. 47 vs 20 years. Females attained a significantly larger length-at-age in southern temperate waters. Macroscopic and microscopic examination of gonads and annual trends in mean monthly gonadosomatic indices (GSIs) were used to determine that this monandric protogynous hermaphrodite spawns from late spring to summer (October–February) in northwestern Australia. In the temperate waters of WA, there was no evidence of reproduction and no males were observed south of ∼30°S latitude. The lengths at which 50% of female H. octofasciatus matured and changed sex were estimated from northern tropical populations at 560 mm (6.1 years) and 1022 mm (≥11 years). Although the population connectivity of H. octofasciatus is unknown, the spawning omission in temperate waters suggests recruitment from the northern tropical areas and highlights the importance of preserving spawning stocks in those northern waters.
Tobacco MAP Kinase Phosphatase (NtMKP1) Negatively Regulates Wound Response and Induced Resistance Against Necrotrophic Pathogens and Lepidopteran Herbivores
Authors: Oka Kumiko , Amano Yuta , Katou Shinpei , Seo Shigemi , Kawazu Kei , Mochizuki Atsushi , Kuchitsu Kazuyuki , Mitsuhara Ichiro
Published: February 2013

Mitogen-activated protein kinase (MAPK) cascades are universal signal transduction pathways in eukaryotic cells. In tobacco, two MAPK, wound-induced protein kinase (WIPK) and salicylic acid (SA)-induced protein kinase (SIPK), are activated by biotic and abiotic stresses. Both WIPK and SIPK positively regulate the biosynthesis of jasmonic acid (JA) or ethylene (ET) while negatively regulating SA accumulation. We showed previously that recombinant tobacco MAPK phosphatase (NtMKP1) protein dephosphorylates and inactivates SIPK in vitro, and overexpression of NtMKP1 repressed wound-induced activation of both SIPK and WIPK. To elucidate the role of NtMKP1 in response to biotic and abiotic stresses, we generated transgenic tobacco plants in which NtMKP1 expression was suppressed. Suppression of NtMKP1 expression resulted in enhanced activation of WIPK and SIPK and production of both JA and ET upon wounding. Wound-induced expression of JA- or ET-inducible genes, basic PR-1 and PI-II, was also significantly enhanced in these plants. Furthermore, NtMKP1-suppressed plants exhibited enhanced resistance against a necrotrophic pathogen, Botrytis cinerea, and lepidopteran herbivores, Mamestra brassicae and Spodoptera litura. These results suggest that NtMKP1 negatively regulates wound response and resistance against both necrotrophic pathogens and herbivorous insects through suppression of JA or ET pathways via inactivation of MAPK.
Application of Geographic Information Systems to Identify the Oversummering Regions of Blumeria graminis f. sp. tritici in China
Authors: Li Boning , Cao Xueren , Chen Lin , Zhou Yilin , Duan Xiayu , Luo Yong , Fitt Bruce D. L. , Xu Xiangming , Song Yuli , Wang Baotong , Cao Shiqin
Published: February 2013

Blumeria graminis f. sp. tritici, the pathogen that causes wheat powdery mildew, can oversummer as mycelia or conidia on leaves of volunteer wheat plants in cool mountainous areas in China. In this study, the regions in China where B. graminis f. sp. tritici can oversummer were identified on the basis of the probability that temperature remains below a critical temperature that is lethal to B. graminis f. sp. tritici. Two methods, one describing the relationship between the average temperature (20 to 26°C) in a given continuous 10-day period and wheat powdery mildew severity, the other describing the relationship between the average temperature (26 to 33°C) and the number of lethal days on powdery mildew development, were used to calculate the oversummering probability using weather data for 743 sites across China. Spatial interpolation based on the ordinary kriging method was conducted for the regions without observation. Oversummering probability values were similar for most locations estimated between the two methods. The B. graminis f. sp. tritici oversummering regions in China were identified to be in mountainous or high-elevation areas, including most regions of Yunnan, west and central areas of Guizhou, south and northwest Sichuan, south and east Gansu, south Ningxia, north and west Shaanxi, central-north Shanxi, west Henan and Hubei, and some regions in Qinghai, Tibet, and Xinjiang. When the oversummering sites from this study were compared with observed survey data for some of these sites, about 90% of sites where B. graminis f. sp. tritici oversummering was observed had been found suitable by both methods. The coincidence frequency and the area under the receiver operating characteristic curve for model 2 were higher, albeit only slightly, than those for model 1. Thus, both methods may be used to assist in disease management and further investigation on pathogen oversummering.
Field Strains of Monilinia fructicola Resistant to Both MBC and DMI Fungicides Isolated from Stone Fruit Orchards in the Eastern United States
Authors: Chen F. , Liu X. , Schnabel G.
Published: February 2013

In 2012, significant brown rot disease was observed on stone fruit in Pennsylvania, Maryland, and South Carolina despite preharvest application of methyl benzimidazole carbamate (MBC) and demethylase inhibitor (DMI) fungicides. In total, 140 Monilinia fructicola isolates were collected from diseased orchards and examined for fungicide sensitivity. In addition to isolates resistant to either the DMI propiconazole or the MBC thiophanate-methyl, 22 isolates were discovered that were resistant to both fungicides, including 4 isolates from peach in South Carolina, 12 isolates from peach and sweet cherry in Maryland, and 6 isolates from sweet cherry in Pennsylvania. Analysis of MBC resistance revealed that dual-resistant isolates from South Carolina carried the β-tubulin E198A mutation, whereas isolates from Maryland and Pennsylvania carried E198 mutations not previously described in the Monilinia genus, E198Q or F200Y. The genetic element Mona, associated with DMI fungicide resistance in M. fructicola, was detected in the dual-resistant isolates from South Carolina but not in the isolates from the two more northern states. An investigation into the molecular mechanism of DMI resistance in the latter isolates revealed that resistance was not based on increased expression or mutation of MfCYP51, which encodes the target of DMI fungicides. Label rates of formulated propiconazole or thiophanate-methyl were unable to control dual-resistant isolates on detached peach fruit, confirming field relevance of dual resistance. The same isolates were not affected by fitness penalties based on mycelial growth rate, ability to sporulate, and virulence on detached peach fruit. The emergence of M. fructicola strains resistant to both DMI and MBC fungicides in multiple states and multiple stone fruit crops is a significant development and needs to be considered when designing resistance management strategies in stone fruit orchards.
Spots and stripes: ecology and colour pattern evolution in butterflyfishes
Authors: Kelley Jennifer L. , Fitzpatrick John L. , Merilaita Sami
Published: February 2013

The incredible diversity of colour patterns in coral reef fishes has intrigued biologists for centuries. Yet, despite the many proposed explanations for this diversity in coloration, definitive tests of the role of ecological factors in shaping the evolution of particular colour pattern traits are absent. Patterns such as spots and eyespots (spots surrounded by concentric rings of contrasting colour) have often been assumed to function for predator defence by mimicking predators' enemies' eyes, deflecting attacks or intimidating predators, but the evolutionary processes underlying these functions have never been addressed. Striped body patterns have been suggested to serve for both social communication and predator defence, but the impact of ecological constraints remains unclear. We conducted the first comparative analysis of colour pattern diversity in butterflyfishes (Family: Chaetodontidae), fishes with conspicuous spots, eyespots and wide variation in coloration. Using a dated molecular phylogeny of 95 species (approx. 75% of the family), we tested whether spots and eyespots have evolved characteristics that are consistent with their proposed defensive function and whether the presence of spots and body stripes is linked with species' body length, dietary complexity, habitat diversity or social behaviour. Contrary to our expectations, spots and eyespots appeared relatively recently in butterflyfish evolution and are highly evolutionarily labile, suggesting that they are unlikely to have played an important part in the evolutionary history of the group. Striped body patterns showed correlated evolution with a number of ecological factors including habitat type, sociality and dietary complexity. Our findings question the prevailing view that eyespots are an evolutionary response to predation pressure, providing a valuable counter example to the role of these markings as revealed in other taxa.
Palaeo-precipitation is a major determinant of palm species richness patterns across Madagascar: a tropical biodiversity hotspot
Authors: Rakotoarinivo Mijoro , Blach-Overgaard Anne , Baker William J. , Dransfield John , Moat Justin , Svenning Jens-Christian
Published: February 2013

The distribution of rainforest in many regions across the Earth was strongly affected by Pleistocene ice ages. However, the extent to which these dynamics are still important for modern-day biodiversity patterns within tropical biodiversity hotspots has not been assessed. We employ a comprehensive dataset of Madagascan palms (Arecaceae) and climate reconstructions from the last glacial maximum (LGM; 21 000 years ago) to assess the relative role of modern environment and LGM climate in explaining geographical species richness patterns in this major tropical biodiversity hotspot. We found that palaeoclimate exerted a strong influence on palm species richness patterns, with richness peaking in areas with higher LGM precipitation relative to present-day even after controlling for modern environment, in particular in northeastern Madagascar, consistent with the persistence of tropical rainforest during the LGM primarily in this region. Our results provide evidence that diversity patterns in the World's most biodiverse regions may be shaped by long-term climate history as well as contemporary environment.
Estradiol-induced object recognition memory consolidation is dependent on activation of mTOR signaling in the dorsal hippocampus
Authors: Fortress Ashley M. , Fan Lu , Orr Patrick T. , Zhao Zaorui , Frick Karyn M.
Published: February 2013

The mammalian target of rapamycin (mTOR) signaling pathway is an important regulator of protein synthesis and is essential for various forms of hippocampal memory. Here, we asked whether the enhancement of object recognition memory consolidation produced by dorsal hippocampal infusion of 17β-estradiol (E2) is dependent on mTOR signaling in the dorsal hippocampus, and whether E2-induced mTOR signaling is dependent on dorsal hippocampal phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK) activation. We first demonstrated that the enhancement of object recognition induced by E2was blocked by dorsal hippocampal inhibition of ERK, PI3K, or mTOR activation. We then showed that an increase in dorsal hippocampal ERK phosphorylation 5 min after intracerebroventricular (ICV) E2infusion was also blocked by dorsal hippocampal infusion of the three cell signaling inhibitors. Next, we found that ICV infusion of E2increased phosphorylation of the downstream mTOR targets S6K (Thr-421) and 4E-BP1 in the dorsal hippocampus 5 min after infusion, and that this phosphorylation was blocked by dorsal hippocampal infusion of inhibitors of ERK, PI3K, and mTOR. Collectively, these data demonstrate for the first time that activation of the dorsal hippocampal mTOR signaling pathway is necessary for E2to enhance object recognition memory consolidation and that E2-induced mTOR activation is dependent on upstream activation of ERK and PI3K signaling.
Heterotrimeric G Proteins Serve as a Converging Point in Plant Defense Signaling Activated by Multiple Receptor-Like Kinases
Authors: Liu Jinman , Ding Pingtao , Sun Tongjun , Nitta Yukino , Dong Oliver , Huang Xingchuan , Yang Wei , Li Xin , Botella José Ramón , Zhang Yuelin
Published: February 2013

In fungi and metazoans, extracellular signals are often perceived by G-protein-coupled receptors (GPCRs) and transduced through heterotrimeric G-protein complexes to downstream targets. Plant heterotrimeric G proteins are also involved in diverse biological processes, but little is known about their upstream receptors. Moreover, the presence of bona fide GPCRs in plants is yet to be established. In Arabidopsis (Arabidopsis thaliana), heterotrimeric G protein consists of one Gα subunit (G PROTEIN α-SUBUNIT1), one Gβ subunit (ARABIDOPSIS G PROTEIN β-SUBUNIT1 [AGB1]), and three Gγs subunits (ARABIDOPSIS G PROTEIN γ-SUBUNIT1 [AGG1], AGG2, and AGG3). We identified AGB1 from a suppressor screen of BAK1-interacting receptor-like kinase1-1 (bir1-1), a mutant that activates cell death and defense responses mediated by the receptor-like kinase (RLK) SUPPRESSOR OF BIR1-1. Mutations in AGB1 suppress the cell death and defense responses in bir1-1 and transgenic plants overexpressing SUPPRESSOR OF BIR1-1. In addition, agb1 mutant plants were severely compromised in immunity mediated by three other RLKs, FLAGELLIN-SENSITIVE2 (FLS2), Elongation Factor-TU RECEPTOR (EFR), and CHITIN ELICITOR RECEPTOR KINASE1 (CERK1), respectively. By contrast, G PROTEIN α-SUBUNIT1 is not required for either cell death in bir1-1 or pathogen-associated molecular pattern-triggered immunity mediated by FLS2, EFR, and CERK1. Further analysis of agg1 and agg2 mutant plants indicates that AGG1 and AGG2 are also required for pathogen-associated molecular pattern-triggered immune responses mediated by FLS2, EFR, and CERK1, as well as cell death and defense responses in bir1-1. We hypothesize that the Arabidopsis heterotrimeric G proteins function as a converging point of plant defense signaling by mediating responses initiated by multiple RLKs, which may fulfill equivalent roles to GPCRs in fungi and animals.
NOT2 Proteins Promote Polymerase II–Dependent Transcription and Interact with Multiple MicroRNA Biogenesis Factors in Arabidopsis
Authors: Wang Lulu , Song Xianwei , Gu Lianfeng , Li Xin , Cao Shouyun , Chu Chengcai , Cui Xia , Chen Xuemei , Cao Xiaofeng
Published: February 2013

MicroRNAs (miRNAs) play key regulatory roles in numerous developmental and physiological processes in animals and plants. The elaborate mechanism of miRNA biogenesis involves transcription and multiple processing steps. Here, we report the identification of a pair of evolutionarily conserved NOT2_3_5 domain–containing-proteins, NOT2a and NOT2b (previously known as At-Negative on TATA less2 [NOT2] and VIRE2-INTERACTING PROTEIN2, respectively), as components involved in Arabidopsis thaliana  miRNA biogenesis. NOT2 was identified by its interaction with the Piwi/Ago/Zwille domain of DICER-LIKE1 (DCL1), an interaction that is conserved between rice (Oryza sativa) and Arabidopsis thaliana. Inactivation of both NOT2 genes in Arabidopsis caused severe defects in male gametophytes, and weak lines show pleiotropic defects reminiscent of miRNA pathway mutants. Impairment of NOT2s decreases the accumulation of primary miRNAs and mature miRNAs and affects DCL1 but not HYPONASTIC LEAVES1 (HYL1) localization in vivo. In addition, NOT2b protein interacts with polymerase II and other miRNA processing factors, including two cap binding proteins, CBP80/ABH1, CBP20, and SERRATE (SE). Finally, we found that the mRNA levels of some protein coding genes were also affected. Therefore, these results suggest that NOT2 proteins act as general factors to promote the transcription of protein coding as well as miRNA genes and facilitate efficient DCL1 recruitment in miRNA biogenesis.
The WD40-Repeat Proteins NFC101 and NFC102 Regulate Different Aspects of Maize Development through Chromatin Modification
Authors: Mascheretti Iride , Battaglia Raffaella , Mainieri Davide , Altana Andrea , Lauria Massimiliano , Rossi Vincenzo
Published: February 2013

The maize (Zea mays) nucleosome remodeling factor complex component101 (nfc101) and nfc102 are putative paralogs encoding WD-repeat proteins with homology to plant and mammalian components of various chromatin modifying complexes. In this study, we generated transgenic lines with simultaneous nfc101 and nfc102 downregulation and analyzed phenotypic alterations, along with effects on RNA levels, the binding of NFC101/NFC102, and Rpd3-type histone deacetylases (HDACs), and histone modifications at selected targets. Direct NFC101/NFC102 binding and negative correlation with mRNA levels were observed for indeterminate1 (id1) and the florigen Zea mays CENTRORADIALIS8 (ZCN8), key activators of the floral transition. In addition, the abolition of NFC101/NFC102 association with repetitive sequences of different transposable elements (TEs) resulted in tissue-specific upregulation of nonpolyadenylated RNAs produced by these regions. All direct nfc101/nfc102 targets showed histone modification patterns linked to active chromatin in nfc101/nfc102 downregulation lines. However, different mechanisms may be involved because NFC101/NFC102 proteins mediate HDAC recruitment at id1 and TE repeats but not at ZCN8. These results, along with the pleiotropic effects observed in nfc101/nfc102 downregulation lines, suggest that NFC101 and NFC102 are components of distinct chromatin modifying complexes, which operate in different pathways and influence diverse aspects of maize development.
A Dual Strategy to Cope with High Light in Chlamydomonas reinhardtii
Authors: Allorent Guillaume , Tokutsu Ryutaro , Roach Thomas , Peers Graham , Cardol Pierre , Girard-Bascou Jacqueline , Seigneurin-Berny Daphné , Petroutsos Dimitris , Kuntz Marcel , Breyton Cécile , Franck Fabrice , Wollman Francis-André , Niyogi Krishna K. , Krieger-Liszkay Anja , Minagawa Jun , Finazzi Giovanni
Published: February 2013

Absorption of light in excess of the capacity for photosynthetic electron transport is damaging to photosynthetic organisms. Several mechanisms exist to avoid photodamage, which are collectively referred to as nonphotochemical quenching. This term comprises at least two major processes. State transitions (qT) represent changes in the relative antenna sizes of photosystems II and I. High energy quenching (qE) is the increased thermal dissipation of light energy triggered by lumen acidification. To investigate the respective roles of qE and qT in photoprotection, a mutant (npq4 stt7-9) was generated in Chlamydomonas reinhardtii by crossing the state transition–deficient mutant (stt7-9) with a strain having a largely reduced qE capacity (npq4). The comparative phenotypic analysis of the wild type, single mutants, and double mutants reveals that both state transitions and qE are induced by high light. Moreover, the double mutant exhibits an increased photosensitivity with respect to the single mutants and the wild type. Therefore, we suggest that besides qE, state transitions also play a photoprotective role during high light acclimation of the cells, most likely by decreasing hydrogen peroxide production. These results are discussed in terms of the relative photoprotective benefit related to thermal dissipation of excess light and/or to the physical displacement of antennas from photosystem II.
Classification of Argentinean Sauvignon Blanc Wines by UV Spectroscopy and Chemometric Methods
Authors: Azcarate Silvana Mariela , Cantarelli Miguel Ángel , Pellerano Roberto Gerardo , Marchevsky Eduardo Jorge , Camiña José Manuel
Published: February 2013

Argentina is an important worldwide wine producer. In this country, there are several recognizable provinces that produce Sauvignon blanc wines: Neuquén, Río Negro, Mendoza, and San Juan. The analysis of the provenance of these white wines is complex and requires the use of expensive and time‐consuming techniques. For this reason, this work discusses the determination of the provenance of Argentinean Sauvignon blanc wines by the use of UV spectroscopy and chemometric methods, such as principal component analysis (PCA), cluster analysis (CA), linear discriminant analysis (LDA), and partial least square discriminant analysis (PLS‐DA). The proposed method requires low‐cost equipment and short‐time analysis in comparison with other techniques. The results are in very good agreement with results based on the geographical origin of Sauvignon blanc wines.

Practical Application:  This manuscript describes a method to determine the geographical origin of Sauvignon wines from Argentina. The main advantage of this method is the use of nonexpensive techniques, such as UV‐Vis spectroscopy.
Advantages of an antagonist: bicuculline and other GABA antagonists
Authors: Johnston Graham AR
Published: February 2013

The convulsant alkaloid bicuculline continues to be investigated more than 40 years after the first publication of its action as an antagonist of receptors for the inhibitory neurotransmitter GABA. This historical perspective highlights key aspects of the discovery of bicuculline as a GABA antagonist and the sustained interest in this and other GABA antagonists. The exciting advances in the molecular biology, pharmacology and physiology of GABA receptors provide a continuing stimulus for the discovery of new antagonists with increasing selectivity for the myriad of GABA receptor subclasses. Interesting GABA antagonists not structurally related to bicuculline include gabazine, salicylidene salicylhydrazide, RU5135 and 4‐(3‐biphenyl‐5‐(4‐piperidyl)‐3‐isoxazole. Bicuculline became the benchmark antagonist for what became known as GABAA receptors, but not all ionotropic GABA receptors are susceptible to bicuculline. In addition, not all GABAA receptor antagonists are convulsants. Thus there are still surprises in store as the study of GABA receptors evolves.
8‐BuS‐ATP derivatives as specific NTPDase1 inhibitors
Authors: Lecka Joanna , Gillerman Irina , Fausther Michel , Salem Mabrouka , Munkonda Mercedes N , Brosseau Jean‐Philippe , Cadot Christine , Martín‐Satué Mireia , d'Orléans‐Juste Pedro , Rousseau Éric , Poirier Donald , Künzli Beat , Fischer Bilha , Sévigny Jean
Published: February 2013

Background and Purpose

Ectonucleotidases control extracellular nucleotide levels and consequently, their (patho)physiological responses. Among these enzymes, nucleoside triphosphate diphosphohydrolase‐1 (NTPDase1), −2, −3 and −8 are the major ectonucleotidases responsible for nucleotide hydrolysis at the cell surface under physiological conditions, and NTPDase1 is predominantly located at the surface of vascular endothelial cells and leukocytes. Efficacious inhibitors of NTPDase1 are required to modulate responses induced by nucleotides in a number of pathological situations such as thrombosis, inflammation and cancer.

Experimental Approach

Here, we present the synthesis and enzymatic characterization of five 8‐BuS‐adenine nucleotide derivatives as potent and selective inhibitors of NTPDase1.

Key Results

The compounds 8‐BuS‐AMP, 8‐BuS‐ADP and 8‐BuS‐ATP inhibit recombinant human and mouse NTPDase1 by mixed type inhibition, predominantly competitive with Ki values <1 μM. In contrast to 8‐BuS‐ATP which could be hydrolyzed by other NTPDases, the other BuS derivatives were resistant to hydrolysis by either NTPDase1, −2, −3 or −8. 8‐BuS‐AMP and 8‐BuS‐ADP were the most potent and selective inhibitors of NTPDase1 expressed in human umbilical vein endothelial cells as well as in situ in human and mouse tissues. As expected, as a result of their inhibition of recombinant human NTPDase1, 8‐BuS‐AMP and 8‐BuS‐ADP impaired the ability of this enzyme to block platelet aggregation. Importantly, neither of these two inhibitors triggered platelet aggregation nor prevented ADP‐induced platelet aggregation, in support of their inactivity towards P2Y1 and P2Y12 receptors.

Conclusions and Implications

The 8‐BuS‐AMP and 8‐BuS‐ADP have therefore potential to serve as drugs for the treatment of pathologies regulated by NTPDase1.