bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of N on Plant Response to Heat‐wave: A Field Study with Prairie Vegetation
Authors: Wang Dan , Heckathorn Scott A. , Mainali Kumar , Hamilton E. William
Published: September 2010

More intense, more frequent, and longer heat‐waves are expected in the future due to global warming, which could have dramatic ecological impacts. Increasing nitrogen (N) availability and its dynamics will likely impact plant responses to heat stress and carbon (C) sequestration in terrestrial ecosystems. This field study examined the effects of N availability on plant response to heat‐stress (HS) treatment in naturally‐occurring vegetation. HS (5 d at ambient or 40.5 °C) and N treatments (±N) were applied to 16 1 m2 plots in restored prairie vegetation dominated by Andropogon gerardii (warm‐season C4 grass) and Solidago canadensis (warm‐season C3 forb). Before, during, and after HS, air, canopy, and soil temperature were monitored; net CO2 assimilation (Pn), quantum yield of photosystem II (ΦPSII), stomatal conductance (gs), and leaf water potential (Ψw) of the dominant species and soil respiration (Rsoil) of each plot were measured daily during HS. One week after HS, plots were harvested, and C% and N% were determined for rhizosphere and bulk soil, and above‐ground tissue (green/senescent leaf, stem, and flower). Photosynthetic N‐use efficiency (PNUE) and N resorption rate (NRR) were calculated. HS decreased Pn, gs, Ψw, and PNUE for both species, and +N treatment generally increased these variables (±HS), but often slowed their post‐HS recovery. Aboveground biomass tended to decrease with HS in both species (and for green leaf mass in S. canadensis), but decrease with +N for A. gerardii and increase with +N for S. canadensis. For A. gerardii, HS tended to decrease N% in green tissues with +N, whereas in S. canadensis, HS increased N% in green leaves. Added N decreased NRR for A. gerardii and HS increased NRR for S. canadensis. These results suggest that heat waves, though transient, could have significant effects on plants, communities, and ecosystem N cycling, and N can influence the effect of heat waves.
Physiological and Growth Responses of C3and C4Plants to Reduced Temperature When Grown at Low CO2of the Last Ice Age
Authors: Ward Joy K. , Myers David A. , Thomas Richard B.
Published: September 2010

During the last ice age, CO2concentration ([CO2]) was 180–200 μμmol/mol compared with the modern value of 380 μμmol/mol, and global temperatures were ∼8 °C cooler. Relatively little is known about the responses of C3and C4species to long‐term exposure to glacial conditions. HereAbutilon theophrastiMedik. (C3) andAmaranthus retroflexusL. (C4) were grown at 200 μμmol/mol CO2with current (30/24 °C) and glacial (22/16 °C) temperatures for 22 d. Overall, the C4species exhibited a large growth advantage over the C3species at low [CO2]. However, this advantage was reduced at low temperature, where the C4species produced 5× the total mass of the C3species versus 14× at the high temperature. This difference was due to a reduction in C4growth at low temperature, since the C3species exhibited similar growth between temperatures. Physiological differences between temperatures were not detected for either species, although photorespiration/net photosynthesis was reduced in the C3species grown at low temperature, suggesting evidence of improved carbon balance at this treatment. This system suggests that C4species had a growth advantage over C3species during low [CO2] of the last ice age, although concurrent reductions in temperatures may have reduced this advantage.
Increased Benthic Algal Primary Production in Response to the Invasive Zebra Mussel (Dreissena polymorpha) in a Productive Ecosystem, Oneida Lake, New York
Authors: Cecala Rebecca K. , Mayer Christine M. , Schulz Kimberly L. , Mills Edward L.
Published: September 2010

Increased water clarity associated with zebra mussel (Dreissena polymorpha) populations may favor benthic algal primary production in freshwater systems previously dominated by pelagic phytoplankton production. While zebra mussel‐mediated water clarity effects on benthic primary production have been implicated in published reports, few production estimates are available. This study estimates benthic primary production in Oneida Lake, NY before and after zebra mussel invasion (1992), using measured photosynthetic parameters (

, αB and β) from sampled benthic algal communities. In the summers of 2003 and 2004, primary production was measured as O2 evolution from algal communities on hard (cobble) and soft (sediment) substrate from several depths. We also backcast estimates of benthic primary production from measurements of light penetration since 1975. Estimates of whole‐lake epipelic and epilithic algal primary production showed a significant (4%) increase and exhibited significantly less interannual variability subsequent to the establishment of zebra mussels. We applied our model to two lakes of differing trophic status; the model significantly overestimated benthic primary production in a hypereutrophic lake, but there was no significant difference between the actual and predicted primary production values in the oligotrophic lake. The hypereutrophic lake had higher zebra mussel densities than Oneida (224 vs. 41 per sample respectively). Though total community respiration (measured in total darkness) was factored into our model predictions of production, our model may need modification when heterotrophic respiration is a large portion of total community metabolism.
Variation in Heat‐shock Proteins and Photosynthetic Thermotolerance among Natural Populations ofChenopodium albumL. from Contrasting Thermal Environments: Implications for Plant Responses to Global Warming
Authors: Barua Deepak , Heckathorn Scott A. , Coleman James S.
Published: September 2010

Production of heat‐shock proteins (Hsps) is a key adaptation to acute heat stress and will be important in determining plant responses to climate change. Further, intraspecifc variation in Hsps, which will influence species‐level response to global warming, has rarely been examined in naturally occurring plants. To understand intraspecific variation in plant Hsps and its relevance to global warming, we examined Hsp content and thermotolerance in five naturally occurring populations ofChenopodium albumL. from contrasting thermal environments grown at low and high temperatures. As expected, Hsp accumulation varied between populations, but this was related more to habitat variability than to mean temperature. Unexpectedly, Hsp accumulation decreased with increasing variability of habitat temperatures. Hsp accumulation also decreased with increased experimental growth temperatures. Physiological thermotolerance was partitioned into basal and induced components. As with Hsps, induced thermotolerance decreased with increasing temperature variability. Thus, populations native to the more stressful habitats, or grown at higher temperatures, had lower Hsp levels and induced thermotolerance, suggesting a greater reliance on basal mechanisms for thermotolerance. These results suggest that future global climate change will differentially impact ecotypes within species, possibly by selecting for increased basal versus inducible thermotolerance.
Functional characterization of the NF‐κB transcription factor gene REL2 from Anopheles gambiae
Authors: HOA NGO T. , ZHENG LIANGBIAO
Published: September 2010

Abstract
The REL2 gene plays an important role in innate immunity against both Gram (+) and Gram (‐) bacteria and malaria parasites in Anopheles gambiae, the main vector of malaria in Africa. Through alternative splicing, REL2 produces two protein products, REL2F (with a Rel‐homology domain as well as an inhibitory ankyrin repeat region) and REL2S (without the ankyrin repeats). In the immune‐competent cell line Sua1B from An. gambiae, REL2 has been shown to be a key regulator for cecropin A (or CEC1). The high level expression of CEC1 in Sua1B was postulated to be the result of constitutive activation of REL2F. Here we showed that REL2F is indeed processed, albeit at a low level, in the Sua1B cell line. The primary cleavage requires residue 678 (an aspartic acid). Proteolytic cleavage of REL2F can be enhanced by challenge with bacteria Escherichia coli and Bacillus subtilis, but not with fungus Beauveria bassiana. The inducible cleavage can be substantially reduced by RNA interference against PGRP‐LC and CASPL1. Over‐expression of REL2S or a constitutively active form of REL2F (REL2F380C or REL2F678) in An. gambiae cell line can further increase expression of CEC1 and other antimicrobial peptide genes. Over‐expression of these constitutive active proteins in an immune naive cell line, MSQ43, from Anopheles stephensi, results in even more dramatic increased expression of antimicrobial peptides.
The origin of herbivory on land: Initial patterns of plant tissue consumption by arthropods
Authors: LABANDEIRA CONRAD
Published: September 2010

The early fossil record of terrestrial arthropod herbivory consists of two pulses. The first pulse was concentrated during the latest Silurian to Early Devonian (417 to 403 Ma), and consists of the earliest evidence for consumption of sporangia and stems (and limited fungivore borings). Herbivorization of most of these tissues was rapid, representing 0 to 20 million‐year (m.y.) lags from the earliest occurrences of these organs in the fossil record to their initial consumption (Phase 1). For approximately the next 75 m.y., there was a second, more histologically varied origination and expansion of roots, leaves, wood and seeds, whose earliest evidence for herbivorization occurred from the Middle‐Late Mississippian boundary to the Middle Pennsylvanian (327 to 309 Ma). The appearance of this second herbivory pulse during the later Paleozoic (Phase 2) is accompanied by major lags of 98 to 54 m.y. between times of appearance of each of the four organ and tissue types and their subsequent herbivory. Both pulses provide a context for three emerging questions. First is an explanation for the contrast between the near instantaneous consumption of plant tissues during Phase 1, versus the exceptionally long lags between the earliest occurrences of plant tissues and their subsequent herbivorization during Phase 2. Second is the identity of arthropod herbivores for both phases. Third is the cause behind the overwhelming targeting of seed‐fern plant hosts during Phase 2. Regardless of the answers to these questions, the trace fossil record of plant‐arthropod associations provides primary ecological data that remain unaddressed by the body‐fossil record alone.
The influence of time and temperature on molecular gut content analysis: Adalia bipunctata fed with Rhopalosiphum padi
Authors: MCMILLAN STUART , KUUSK ANNA‐KARIN , CASSEL‐LUNDHAGEN ANNA , EKBOM BARBARA
Published: September 2010

Gut content analysis is a useful tool when studying arthropod predator‐prey interactions. We used polymerase chain reaction (PCR) technique to examine how detection of prey DNA in the gut content of predators was influenced by digestion time and temperature. Such knowledge is critical before applying PCR‐based gut content analysis to field collected predators. Larvae of the two‐spotted ladybeetle (Adalia bipunctata L.) were fed with the bird cherry‐oat aphid (Rhopalosiphum padi L.) at either 21°C or 14°C. After consuming one aphid, the predators were allowed to digest the prey for a range of time periods up to 24 hours. The influence of temperature on A. bipunctata feeding behavior was also recorded. From the fed larvae, total DNA was extracted and PCR reactions with R. padi specific primers were run. The number of A. bipunctata that tested positive for R. padi DNA was negatively related to the length of digestion time. Temperature influenced larval feeding behavior but did not have a significant effect on R. padi DNA detection. After pooling the data from both temperature treatments we estimated the time point when R. padi DNA could be amplified from 50% of the fed A. bipunctata by PCR to be 4.87 hours. With such a rapid decrease in prey DNA detection success, positive PCR reactions will most likely be the result of predation events occurring shortly before capture. If a defined digestion temperature range has proven not to influence prey detection, PCR data obtained from predators collected within that particular range can be interpreted in the same way.
Morphometric and genetic variation of small dwarf honeybees Apis andreniformis Smith, 1858 in Thailand
Authors: RATTANAWANNEE ATSALEK , CHANCHAO CHANPEN , WONGSIRI SIRIWAT
Published: September 2010

The small dwarf honey bee, Apis andreniformis, is a rare and patchily distributed Apis spp. and is one of the native Thai honey bees, yet little is known about its biodiversity. Thirty (27 Thai and 3 Malaysian) and 37 (32 Thai and 5 Malaysian) colonies of A. andreniformis were sampled for morphometric and genetic analysis, respectively. For morphometric analysis, 20 informative characters were used to determine the variation. After plotting the factor scores, A. andreniformis from across Thailand were found to belong to one group, a notion further supported by a cluster analysis generated dendrogram. However, clinal patterns in groups of bee morphometric characters were revealed by linear regression analysis. The body size of bees increases from South to North but decreases from West to East, although this may reflect altitude rather than longitude. Genetic variation was determined by sequence analysis of a 520 bp fragment of the mitochondrial cytochrome oxidase subunit b (cytb). DNA polymorphism among bees from the mainland of Thailand is lower than that from Phuket Island and Chiang Mai. Although two main different groups of bees were obtained from phylogenetic trees constructed by neighbor‐joining and unweighted pair‐group method using arithmetic averages programs, no clear geographic signal was present. Thus, while the minor group (B) contained all of the samples from the only island sampled (Phuket in the south), but not the southern mainland colonies, it also contained samples from the far northern inland region of Chiang Mai, other samples of which were firmly rooted in the major group (A).
Arthropods associated with medicinal plants in coastal South Carolina
Authors: LOPEZ ROLANDO , SHEPARD B. MERLE
Published: September 2010

Arthropods were sampled from feverfew [Tanacetum parthenium (L.) Schultz‐Bip], Echinacea purpurea (L.) Moench, Echinacea pallida (Nutt.) Nutt., Valeriana officinalis L., and St. John's wort (Hypericum perforatum L.) during 1998‐2001. In addition, arthropods were sampled on tansy (Tanacetum vulgare L.) from 2001‐2004. In general, 50‐60 arthropod species where collected and identified among all of the medicinal plant species. Among the predators, Orius insidiosus (Say) (Hemiptera: Anthocoridae), Geocoris punctipes (Say) (Hemiptera: Lygaeidae) and spiders were most abundant from 1998‐2004. The three‐cornered alfalfa hopper, Spissistilus festinus (Say), was the most abundant herbivore found from 1998 to 2001. Orius insidiosus and G. punctipes were 3‐4 times more abundant on T. parthenium than on any other medicinal plant species. Based on the numbers of predatory arthropods found on T. parthenium, this crop could be suitable as a companion or “banker” plant to attract and maintain populations of predators, especially O. insidiosus and G. punctipes. Whitefly nymphs attacked by predators with piercing/sucking mouthparts are easily identified using a microscope because of the general appearance of the carcass left by the predators. Thus, populations of predators on T. parthenium suppressed Bemisia tabaci populations on E. purpurea when these crops were planted as companion crops.
Functional genomics studies on the innate immunity of disease vectors
Authors: Baton Luke A. , Garver Lindsey , Xi Zhiyong , Dimopoulos George
Published: September 2010

The increasing availability of genome sequences and the development of high‐throughput techniques for gene expression profiling and functional characterization are transforming the study of innate immunity and other areas of insect biology. Already, functional genomic approaches have enabled a quantum advance in the characterization of mosquito immune responses to malaria parasite infection, and similar high‐throughput functional genomic studies of other vector‐pathogen interactions can be expected in the near future. The application of microarray‐based and other expression analyses provide genome‐wide transcriptional profiles that can be used to identify insect immune system components that are differentially regulated upon exposure to various classes of pathogens, including many important etiologic agents of human and animal diseases. The role of infection‐responsive or other candidate immune genes identified through comparative genomic approaches can then be functionally characterized, either in vivo, for instance in adult mosquitoes, or in vitro using cell lines. In most insect vectors of human pathogens, germ‐line transgenesis is still technically difficult and maintenance of multiple transgenic lines logistically demanding. Consequently, transient RNA interference (RNAi)‐mediated gene‐silencing has rapidly become the method of choice for functional characterization of candidate innate immune genes. The powerful combination of transcriptional profiling in conjunction with assays using RNAi to determine gene function, and identify regulatory pathways, together with downstream cell biological approaches to determine protein localization and interactions, will continue to provide novel insights into the role of insect innate immunity in a variety of vector‐pathogen interactions. Here we review advances in functional genomics studies of innate immunity in the insect disease vectors, over the past decade, with a particular focus on the Anopheles mosquito and its responses to malaria infection.
Innate immunity against malaria parasites in Anopheles gambiae
Authors: Chen Yang , Weng Zhi‐Hui , Zheng Liangbiao
Published: September 2010

Malaria continues to exert a huge toll in the world today, causing approximately 400 million cases and killing between 1‐2 million people annually. Most of the malaria burden is borne by countries in Africa. For this reason, the major vector for malaria in this continent, Anopheles gambiae, is under intense study. With the completion of the draft sequence of this important vector, efforts are underway to develop novel control strategies. One promising area is to harness the power of the innate immunity of this mosquito species to block the transmission of the malaria parasites. Recent studies have demonstrated that Toll and Imd signaling pathways and other immunity‐related genes (encoding proteins possibly function in recognition or as effector molecules) play significant roles in two different arms of innate immunity: level of infection intensity and melanization of Plasmodium oocysts. The challenges in the future are to understand how the functions of these different genes are coordinated in defense against malaria parasites, and if different arms of innate immunity are cross–regulated or coordinated.
The biochemical basis of antimicrobial responses in Manduca sexta
Authors: Jiang Haobo
Published: September 2010

Innate immunity is essential for the wellbeing of vertebrates and invertebrates. Key components of this defense system include pattern recognition receptors that bind to infectious agents, extra–and intra–cellular proteins that relay signals, as well as molecules and cells that eliminate pathogens. We have been studying the defense mechanisms in a biochemical model insect, Manduca sexta. In this insect, hemolin, peptidoglycan recognition proteins, β‐1,3‐glucan recognition proteins and C‐type lectins detect microbial surface molecules and induce immune responses such as phagocytosis, nodulation, encapsulation, melanization and production of antimicrobial peptides. Some of these responses are mediated by extracellular serine proteinase pathways. The proteolytic activation of prophenoloxidase (proPO) yields active phenoloxidase (PO) which catalyzes the formation of quinones and melanin for wound healing and microbe killing. M. sexta hemolymph proteinase 14 (HP14) precursor interacts with peptidoglycan or β‐1,3‐glucan, autoactivates, and leads to the activation of other HPs including HP21 and proPO‐activating proteinases (PAPs). PAP‐1, ‐2 and ‐3 cut proPO to generate active PO in the presence of two serine proteinase homologs. Inhibition of the proteinases by serpins and association of the proteinase homologs with bacteria ensure a localized defense reaction. M. sexta HP1, HP6, HP8, HP17 and other proteinases may also participate in proPO activation or processing of spätzle and plasmatocyte spreading peptide.
Insect immune resistance to parasitoids
Authors: Carton Yves , Poirié Marylène , Nappi Anthony J.
Published: September 2010

Insect host—parasitoid interactions involve complex physiological, biochemical and genetic interactions. Against endoparasitoids, immune‐competent hosts initiate a blood cell‐mediated response that quickly destroys the intruders and envelops them in a multilayered melanotic capsule. During the past decade, considerable progress has been made in identifying some of the critical components of the host response, mainly because of the use of efficient molecular tools. This review examines some of the components of the innate immune response of Drosophila, an insect that has served as an exceptionally good experimental model for studying non‐self recognition processes and immune cell signaling mechanisms. Topics considered in this review include hematopoiesis, proliferation and adhesion of hemocytes, melanogenesis and associated cytotoxic molecules, and the genetic aspects of the host‐parasitoid interaction.
Wolbachiasymbiosis and insect immune response
Authors: Siozios Stefanos , Sapountzis Panagiotis , Ioannidis Panagiotis , Bourtzis Kostas
Published: September 2010

Bacterial intracellular symbiosis is very common in insects, having significant consequences in promoting the evolution of life and biodiversity. The bacterial group that has recently attracted particular attention isWolbachia pipientiswhich probably represents the most ubiquitous endosymbiont on the planet.W. pipientisis a Gram‐negative obligatory intracellular and maternally transmitted α‐proteobacterium, that is able to establish symbiotic associations with arthropods and nematodes. In arthropods,Wolbachia pipientisinfections have been described in Arachnida, in Isopoda and mainly in Insecta. They have been reported in almost all major insect orders including Diptera, Coleoptera, Hemiptera, Hymenoptera, Orthoptera and Lepidoptera. To enhance its transmission,W. pipientiscan manipulate host reproduction by inducing parthenogenesis, feminization, male killing and cytoplasmic incompatibility. Several polymerase chain reaction surveys have indicated that up to 70% of all insect species may be infected withW. pipientis.How doesW. pipientismanage to get established in diverse insect host species? How is this intracellular bacterial symbiont species so successful in escaping the host immune response? The present review presents recent advances and ongoing scientific efforts in the field. The current body of knowledge in the field is summarized, revelations from the available genomic information are presented and as yet unanswered questions are discussed in an attempt to present a comprehensive picture of the unique ability ofW. pipientisto establish symbiosis and to manipulate reproduction while evading the host's immune system.
Comparison of synaptic transmission and plasticity between sensory and cortical synapses on relay neurons in the ventrobasal nucleus of the rat thalamus
Authors: Hsu Ching‐Lung , Yang Hsiu‐Wen , Yen Cheng‐Tung , Min Ming‐Yuan
Published: September 2010

Relay neurons in the ventrobasal nucleus of the thalamus transmit somatosensory information to the cerebral cortex and receive sensory and cortical (feedback) synaptic inputs via, respectively, medial lemniscal (ML) and corticothalamic (CT) fibres. Here, we report that calcium‐permeable AMPA receptors are expressed at CT synapses, but not ML synapses, and that the NMDA receptor (NMDAR)‐mediated/non‐NMDAR‐mediated synaptic current ratio is significantly larger at CT synapses than at ML synapses. Moreover, NMDAR‐dependent LTP and L‐type voltage‐gated calcium channel‐dependent LTD are readily induced at CT synapses, but not ML synapses. In particular, LTD of CT synaptic transmission is induced by spiking of postsynaptic relay neurons in continuous mode, but not burst mode, in current‐clamp recordings. These results show that the strength of the cortical input to thalamic relay neurons is selectively subjected to use‐dependent modification, which could be a mechanism for regulation of thalamocortical–corticothalamic interactions and the underlying sensory processing.
Lack of otolith involvement in balance responses evoked by mastoid electrical stimulation
Authors: Mian Omar S. , Dakin Christopher J. , Blouin Jean‐Sébastien , Fitzpatrick Richard C. , Day Brian L.
Published: September 2010

Passing current through mastoid electrodes (conventionally termed galvanic vestibular stimulation; GVS) evokes a balance response containing a short‐ and a medium‐latency response. The origins of these two responses are debated. Here we test the hypotheses that they originate from net signals evoked by stimulation of otolith and semi‐circular canal afferents, respectively. Based on anatomy and function, we predicted the directions of the stimulus‐evoked net head rotation vector from the canals and the linear acceleration net vector from the otoliths. We tested these predictions in healthy adults by obtaining responses with the head in strategic postures to alter the relevance of the signals to the balance system. Cross‐covariance between a stochastic waveform of stimulating current and motor output was used to assess the balance responses. Consistent with the canal hypothesis, with the head pitched down the medium‐latency EMG response was abolished while the short‐latency EMG response was maintained. The results, however, did not support the otolith hypothesis. The direction of the linear acceleration signal from the otoliths was predicted to change substantially when using monaural stimuli compared to binaural stimuli. In contrast, short‐latency response direction measured from ground‐reaction forces was not altered. It was always directed along the inter‐aural axis irrespective of whether the stimulus was applied binaurally or monaurally, whether the head was turned in yaw through 90 deg, whether the head was pitched down through 90 deg, or combinations of these manipulations. We conclude that a net canal signal evoked by GVS contributes to the medium‐latency response whilst a net otolith signal does not make a significant contribution to either the short‐ or medium‐latency responses.
A Coupled Sharp-Interface Immersed Boundary-Finite-Element Method for Flow-Structure Interaction With Application to Human Phonation
Authors: Zheng X. , Xue Q. , Mittal R. , Beilamowicz S.
Published: September 2010

A new flow-structure interaction method is presented, which couples a sharp-interface immersed boundary method flow solver with a finite-element method based solid dynamics solver. The coupled method provides robust and high-fidelity solution for complex flow-structure interaction (FSI) problems such as those involving three-dimensional flow and viscoelastic solids. The FSI solver is used to simulate flow-induced vibrations of the vocal folds during phonation. Both two- and three-dimensional models have been examined and qualitative, as well as quantitative comparisons, have been made with established results in order to validate the solver. The solver is used to study the onset of phonation in a two-dimensional laryngeal model and the dynamics of the glottal jet in a three-dimensional model and results from these studies are also presented.
The Influence of Fiber Orientation on the Equilibrium Properties of Neutral and Charged Biphasic Tissues
Authors: Nagel Thomas , Kelly Daniel J.
Published: September 2010

Constitutive models facilitate investigation into load bearing mechanisms of biological tissues and may aid attempts to engineer tissue replacements. In soft tissue models, a commonly made assumption is that collagen fibers can only bear tensile loads. Previous computational studies have demonstrated that radially aligned fibers stiffen a material in unconfined compression most by limiting lateral expansion while vertically aligned fibers buckle under the compressive loads. In this short communication, we show that in conjunction with swelling, these intuitive statements can be violated at small strains. Under such conditions, a tissue with fibers aligned parallel to the direction of load initially provides the greatest resistance to compression. The results are further put into the context of a Benninghoff architecture for articular cartilage. The predictions of this computational study demonstrate the effects of varying fiber orientations and an initial tare strain on the apparent material parameters obtained from unconfined compression tests of charged tissues.
Regulation of Ras Localization by Acylation Enables a Mode of Intracellular Signal Propagation
Authors: Lorentzen Anna , Kinkhabwala Ali , Rocks Oliver , Vartak Nachiket , Bastiaens Philippe I. H.
Published: September 2010

Active Ras is relayed between subcellular compartments by the acylation cycle.
Accelerated Aging by Compromised Wnt Signaling
Authors: Gough Nancy R.
Published: September 2010

Defective Wnt signaling may contribute to a severe premature aging disease.
Drawn In by the Activity
Authors: Wong Wei
Published: September 2010

Increased neuronal activity promotes the uptake of IGF-1 by the brain from the circulation.
Glucose Metabolism Revisited
Authors: Ray L. Bryan
Published: September 2010

Characterization of cancer cell metabolism provides evidence for a previously uncharacterized metabolic pathway.
Therapeutic Potential of a Combination of Two Gene-Specific Small Interfering RNAs against Clinical Strains of
Acanthamoeba
Authors: Lorenzo-Morales Jacob , Martín-Navarro Carmen M. , López-Arencibia Atteneri , Santana-Morales María A. , Afonso-Lehmann Raquel N. , Maciver Sutherland K. , Valladares Basilio , Martínez-Carretero Enrique
Published: September 2010

Pathogenic strains of the genus
Acanthamoeba
are causative agents of severe infections, such as fatal encephalitis and a sight-threatening amoebic keratitis. Antimicrobial therapy for these infections is generally empirical, and patient recovery is often problematic, due to the existence of a highly resistant cyst stage in these amoebae. In previous studies, small interfering RNAs (siRNAs) against the catalytic domains of extracellular serine proteases and glycogen phosphorylase from
Acanthamoeba
were designed and evaluated for future therapeutic use. The silencing of proteases resulted in
Acanthamoeba
failing to degrade human corneal cells, and silencing of glycogen phosphorylase caused amoebae to be unable to form mature cysts. After the siRNA design and concentration were optimized in order to avoid toxicity problems, cultures of
Acanthamoeba
were treated with a combination of both siRNAs, and cells were evaluated under an inverted microscope. This siRNA-based treatment dramatically affected the growth rate and cellular survival of the amoebae. These results were observed less than 48 h after the initiation of the treatment. In order to check possible toxic effects of the siRNA combination, three eukaryotic cell lines (HeLa, murine macrophages, and osteosarcoma cells) were treated with the same molecules, and cytotoxicity was examined by measuring lactate dehydrogenase release. The future use of the combination of these siRNAs is proposed as a potential therapeutic approach against pathogenic strains of
Acanthamoeba
.
In VitroActivities of Several Antimicrobial Agents against Recently Isolated and GenotypedChlamydia trachomatisUrogenital Serovars D through K
Authors: Donati Manuela , Di Francesco Antonietta , D'Antuono Antonietta , Delucca Federica , Shurdhi Alisa , Moroni Alessandra , Baldelli Raffaella , Cevenini Roberto
Published: September 2010

A systematic evaluation of the susceptibility of allChlamydia trachomatisurogenital serovars (D through K) to levofloxacin, erythromycin, doxycycline, clarithromycin, and azithromycin was performed. AllC. trachomatisserovars had comparable susceptibilities with respect to the various antimicrobials tested, thus confirming the homogeneous data so far obtained regarding the susceptibility ofC. trachomatisto antimicrobial agents.
DifferentialAspergillus lentulusEchinocandin Susceptibilities Are Fksp Independent
Authors: Staab Janet F. , Kahn Jennifer Nielsen , Marr Kieren A.
Published: September 2010

The recently described speciesAspergillus lentulusexhibits differential and reduced susceptibilities to echinocandins and other antifungal drugsin vitro. A. lentulusisolates overall are less susceptible to caspofungin, although they maintain susceptibility to anidulafungin and micafungin. Mutations or polymorphisms infks, the gene encoding the catalytic subunit of β-1,3-glucan synthase, are known to confer decreased susceptibility to echinocandins inCandidaspp. andAspergillus fumigatus. The analysis of theA. lentulus fkssequence did not reveal a polymorphism at any of the known hot-spot regions of the gene. Caspofungin and micafungin kinetic inhibition profiles of theA. lentulusglucan synthase were comparable to those from susceptibleA. fumigatusenzymes. Although the basal cell wall chitin levels inA. lentulusaveraged 60% of those inA. fumigatus, echinocandin treatment promoted the increase of cell wall chitin in both organisms, indicating thatA. lentulusdisplays a compensatory chitin response similar to that ofA. fumigatus. The data suggest that differential echinocandin susceptibilities inA. lentulusare independent of the echinocandin target, Fksp, and they emphasize the potential that the drugs' capacity to inhibit the target enzyme is unequal at the cellular level.
Molecular Characterization of Off-Target Activities of Telithromycin: a Potential Role for Nicotinic Acetylcholine Receptors
Authors: Bertrand Daniel , Bertrand Sonia , Neveu Estelle , Fernandes Prabhavathi
Published: September 2010

Adverse effects have limited the clinical use of telithromycin. Preferential inhibition of the nicotinic acetylcholine receptors (nAChR) at the neuromuscular junction (α3β2 and NMJ), the ciliary ganglion of the eye (α3β4 and α7), and the vagus nerve innervating the liver (α7) could account for the exacerbation of myasthenia gravis, the visual disturbance, and the liver failure seen with telithromycin use. The studies presented here enable the prediction of expected side effects of macrolides in development, such as solithromycin (CEM-101).
Mitochondrial Electron Transport Inhibition and Viability of Intraerythrocytic
Plasmodium falciparum
Authors: Painter Heather J. , Morrisey Joanne M. , Vaidya Akhil B.
Published: September 2010

Although mitochondrial electron transport is a validated target of the antimalarial drug atovaquone, the molecular details underlying parasite demise are unclear. We have shown that a critical function of mitochondrial electron transport in blood-stage
Plasmodium falciparum
is to support pyrimidine biosynthesis. Here, we explore the effects of atovaquone, alone and in combination with proguanil, on
P. falciparum
viability. Our results suggest that the effects of inhibition depend upon the erythrocytic stage of the parasites and the duration of exposure. Ring- and schizont-stage parasites are most resilient to drug treatment and can survive for 48 h, with a fraction remaining viable even after 96 h. Survival of parasites does not appear to require nutrient uptake. Thus, intraerythrocytic parasites with inhibited mitochondrial electron transport and collapsed mitochondrial membrane potential do not undergo apoptosis but enter an apparent static state. These results have significant implications for desirable properties of antimalarials under development that target mitochondrial functions.
In Vitro
Sensitivity and Resistance of 46
Leptospira
Strains Isolated from Rats in the Philippines to 14 Antimicrobial Agents
Authors: Chakraborty Antara , Miyahara Satoshi , Villanueva Sharon Y. A. M. , Gloriani Nina G. , Yoshida Shin-ichi
Published: September 2010

The
in vitro
susceptibilities of 46
Leptospira
isolates from rats to 14 antimicrobial agents were tested. All of the strains were found to be sensitive to ampicillin, cefotaxime, ciprofloxacin, norfloxacin, doxycycline, erythromycin, and streptomycin. In contrast, the tested isolates showed resistance to amphotericin B, 5-fluorouracil, fosfomycin, trimethoprim, sulfamethoxazole, neomycin, and vancomycin. These findings will help in selecting effective and ineffective antimicrobials for treatment of leptospirosis and for the development of new selective media, respectively.
Effect of N-1/C-8 Ring Fusion and C-7 Ring Structure on Fluoroquinolone Lethality
Authors: Malik Muhammad , Marks Kevin R. , Schwanz Heidi A. , German Nadezhda , Drlica Karl , Kerns Robert J.
Published: September 2010

Quinolones rapidly kill bacteria by two mechanisms, one that requires protein synthesis and one that does not. The latter, which is measured as lethal action in the presence of the protein synthesis inhibitor chloramphenicol, is enhanced by N-1 cyclopropyl and C-8 methoxy substituents, as seen with the highly lethal compound PD161144. In some compounds, such as levofloxacin, the N-1 and C-8 substituents are fused. To assess the effect of ring fusion on killing, structural derivatives of levofloxacin and PD161144 differing at C-7 were synthesized and examined with
Escherichia coli
. A fused-ring derivative of PD161144 exhibited a striking absence of lethal activity in the presence of chloramphenicol. In general, ring fusion had little effect on lethal activity when protein synthesis was allowed, but fusion reduced lethal activity in the absence of protein synthesis to extents that depended on the C-7 ring structure. Additional fused-ring fluoroquinolones, pazufloxacin, marbofloxacin, and rufloxacin, also exhibited reduced activity in the presence of chloramphenicol. Energy minimization modeling revealed that steric interactions of the
trans
-oriented N-1 cyclopropyl and C-8 methoxy moieties skew the quinolone core, rigidly orient these groups perpendicular to core rings, and restrict the rotational freedom of C-7 rings. These features were not observed with fused-ring derivatives. Remarkably, structural effects on quinolone lethality were not explained by the recently described X-ray crystal structures of fluoroquinolone-topoisomerase IV-DNA complexes, suggesting the existence of an additional drug-binding state.
Inhibition of T Cells Provides Protection against Early Invasive Pneumococcal Disease
Authors: LeMessurier Kim , Häcker Hans , Tuomanen Elaine , Redecke Vanessa
Published: September 2010

Infections caused byStreptococcus pneumoniaeare major causes of morbidity and mortality, which are in part mediated by immune cell-dependent mechanisms. Yet, the specific contributions of individual cell types to immunopathology are only partially understood. T cells are well characterized with respect to their function in protective humoral immune responses; however, their roles during early stages of infection and invasive pneumococcal disease (IPD) are less well defined. Using a mouse model of pneumococcal sepsis, we found that CD4+T cells were recruited to the lung as early as 12 h after intranasal infection. Recruitment was accompanied by upregulation of CD69 and B7-H1, reflecting T-cell activation. Unexpectedly, major histocompatibility complex (MHC) class II-deficient mice, which lack CD4+T cells, displayed an increased survival despite comparable bacterial titers in the blood, spleen, and lung. The higher survival correlated with a lower cytokine and chemokine response uponS. pneumoniaechallenge in MHC class II-deficient mice, suggesting that inflammation may contribute to the mortality of IPD. Comparable to the case for MHC class II-deficient mice, antibody-mediated depletion of CD4+T cells and drug-induced inhibition of T-cell function with cyclosporine, or interference with T-cell activation using CTLA4-immunoglobulin (Abatacept), led to significant increases in survival during IPD. Our results reveal an important and adverse role of CD4+T cells in the pathogenesis of IPD and suggest that modulation of T-cell activation during early phases ofS. pneumoniaeinvasive infection may provide a therapeutic option.
Which antibody and which cancer in which paraneoplastic syndromes?
Authors: Gozzard Paul , Maddison Paul
Published: September 2010

Paraneoplastic neurological syndromes can be associated with the presence of onconeural antibodies. These antibodies are the result of an immune response against a tumour that is ectopically expressing a neuronal antigen. The ‘classical’ onconeural antibodies (anti-Hu, Yo, Ma2, CRMP-5, amphiphysin and Ri) are directed against intracellular antigens and are strongly associated with underlying malignancy. By contrast, onconeural antibodies directed against cell surface antigens (eg, anti-NMDA, VGKC, AChR) have a weaker tumour association. This article gives a practical overview of the tumour associations, and the neurological associations, of the onconeural antibodies. There is also guidance on how to investigate occult malignancy in antibody positive cases.
When confronted by a patient with the radiologically isolated syndrome
Authors: Chataway Jeremy
Published: September 2010

As MRI becomes ever easier to access, it is clear that there is a group of patients, scanned for a wide range of symptoms, where the imaging looks inflammatory, despite the discordance with the clinical presentation. This is the so-called radiologically isolated syndrome, which can be a source of anxiety and difficulty for both patient and clinician. The evidence for its relationship to the clinically isolated syndrome and therefore to multiple sclerosis is presented, and I will describe a pragmatic approach to managing the situation.
KEY DISTRIBUTION VERSUS KEY ENHANCEMENT IN QUANTUM CRYPTOGRAPHY
Authors: NAGY NAYA , NAGY MARIUS , AKL SELIM G.
Published: September 2010

It has been said that quantum cryptography in general offers a secure solution to the problem of key enhancement. This means that two parties who already share a small secret key, can use quantum protocols to establish a new large secret key. This large secret key can be arbitrarily long and is unbreakable. Thus, to date, the main contribution of quantum cryptography has been believed to be quantum key enhancement. This paper shows that quantum cryptography can do significantly more. The quantum protocol described here distributes an unbreakable secret key to the two parties by relying on public information only. This is the first time that quantum cryptography is shown to be able to produce secret information using only public information. This contribution is also unique for cryptography in general, classical and quantum.
ON THE IMPORTANCE OF BEING QUANTUM
Authors: AKL SELIM G.
Published: September 2010

Game playing is commonly cited in debates concerning human versus machine intelligence, and Chess is often at the center of such debates. However, the role of Chess in delineating the difference between natural and artificial intelligence has been significantly diminished since a World Chess Champion lost in a tournament against a computer. Computer brute force is regularly blamed for the human defeat. This paper proposes a Quantum Chess Board in an attempt to bring back some equilibrium, putting humans and computers on an ostensibly equal footing when faced with the uncertainties of quantum physics.
RENORMALIZATION GROUP EVOLUTION OF NEUTRINO MASSES AND MIXING IN SEESAW MODELS
Authors: RAY SHAMAYITA
Published: September 2010

We consider different extensions of the Standard Model which can give rise to the small active neutrino masses through seesaw mechanisms, and their mixing. These tiny neutrino masses are generated at some high energy scale by the heavy seesaw fields which then get sequentially decoupled to give an effective dimension-5 operator at the low energy. The renormalization group evolution of the masses and the mixing parameters of the three active neutrinos in the high energy as well as the low energy effective theory is reviewed in this paper.
A RENORMALIZATION PROCEDURE FOR TENSOR MODELS AND SCALAR-TENSOR THEORIES OF GRAVITY
Authors: SASAKURA NAOKI
Published: September 2010

Tensor models are more-index generalizations of the so-called matrix models, and provide models of quantum gravity with the idea that spaces and general relativity are emergent phenomena. In this paper, a renormalization procedure for the tensor models whose dynamical variable is a totally symmetric real three-tensor is discussed. It is proven that configurations with certain Gaussian forms are the attractors of the three-tensor under the renormalization procedure. Since these Gaussian configurations are parametrized by a scalar and a symmetric two-tensor, it is argued that, in general situations, the infrared dynamics of the tensor models should be described by scalar-tensor theories of gravity.
NEUTRINO MIXING, LEPTONIC CP VIOLATION, THE SEESAW MECHANISM AND BEYOND
Authors: PETCOV S. T.
Published: September 2010

The phenomenology of 3-neutrino mixing and of the related Dirac and Majorana leptonic CP violation is reviewed. The leptogenesis scenario of generation of the baryon asymmetry of the Universe, which is based on the see-saw mechanism of neutrino mass generation, is considered. The results showing that the CP violation necessary for the generation of the baryon asymmetry of the Universe in leptogenesis can be due exclusively to the Dirac and/or Majorana CP-violating phase(s) in the neutrino mixing matrix U are briefly reviewed.
LOCAL LEARNING ESTIMATES BY INTEGRAL OPERATORS
Authors: LI HONG , CHEN NA , TANG YUAN Y.
Published: September 2010

In this paper, we consider the problem of local risk minimization on the basis of empirical data, which is a generalization of the problem of global risk minimization. A new local risk regularization scheme is proposed. The error estimate for the proposed algorithm is obtained by using probabilistic estimates for integral operators. Experiments are presented to illustrate the general theory. Simulation results on several artificial real datasets show that the local risk regularization algorithm has better performance.
TIME-FREQUENCY ANALYSIS BY EVOLUTIONARY PERIODOGRAM WITH APPLICATION IN GEAR FAULT DIAGNOSIS
Authors: AL-MANIE M. A. , WANG W. J.
Published: September 2010

The evolutionary periodogram has been introduced to mechanical fault diagnosis and relationship between the evolutionary periodogram and time-frequency spectrogram has been investigated. The evolutionary periodogram is unveiled as an especially windowed spectrogram, and is applied to gearbox fault diagnosis. It has been shown that the window used in the evolutionary periodogram is not a single function but a combination of a set of functions. Two cases of gearbox diagnosis are presented as examples of application. Vibration signals and a synchronous signal are collected for the analysis. The time synchronous averaging is used to reduce background noise or random transients to enhance the periodicity of a specific gear rotation. The performance of the evolutionary periodogram has been compared with the spectrogram for gear diagnosis, showing that the evolutionary periodogram is an alternative technique in time-frequency analysis for fault detection and better resolution can be obtained as more choices are offered by the way of constructing the window.