bluuebunny/crossref_metadata_2025 huggingface dataset:
TrkB Downregulation Is Required for Dendrite Retraction in Developing Neurons of Chicken Nucleus Magnocellularis
Authors: Schecterson Leslayann C. , Sanchez Jason Tait , Rubel Edwin W. , Bothwell Mark
Published: October 2012

The chick embryo (Gallus domesticus) is one of the most important model systems in vertebrate developmental biology. The development and function of its auditory brainstem circuitry is exceptionally well studied. These circuits represent an excellent system for genetic manipulation to investigate mechanisms controlling neural circuit formation, synaptogenesis, neuronal polarity, and dendritic arborization. The present study investigates the auditory nucleus, nucleus magnocellularis (NM). The neurotrophin receptor TrkB regulates dendritic structure in CNS neurons. TrkB is expressed in NM neurons at E7–E8 when these neurons have dendritic arbors. Downregulation of TrkB occurs after E8 followed by retraction of dendrites and by E18 most NM cells are adendritic. Is cessation of TrkB expression in NM necessary for dendritic retraction? To answer this question we combined focalin ovoelectroporation with transposon mediated gene transfer to obtain stable expression of Doxycycline (Dox) regulated transgenes, specifically TrkB coexpressed with EGFP in a temporally controlled manner. Electroporation was performed at E2 and Dox added onto the chorioallointoic membrane from E7.5 to E16. Expression of EGFP had no effect on development of the embryo, or cell morphology and organization of auditory brainstem nuclei. NM cells expressing EGFP and TrkB at E17–E18 had dendrites and biophysical properties uncharacteristic for normal NM cells, indicating that cessation of TrkB expression is essential for dendrite retraction and functional maturation of these neurons. These studies indicate that expression of transposon based plasmids is an effective method to genetically manipulate events in mid to late embryonic brain development in chick.
Motor-Sensory Confluence in Tactile Perception
Authors: Saig Avraham , Gordon Goren , Assa Eldad , Arieli Amos , Ahissar Ehud
Published: October 2012

Perception involves motor control of sensory organs. However, the dynamics underlying emergence of perception from motor-sensory interactions are not yet known. Two extreme possibilities are as follows: (1) motor and sensory signals interact within an open-loop scheme in which motor signals determine sensory sampling but are not affected by sensory processing and (2) motor and sensory signals are affected by each other within a closed-loop scheme. We studied the scheme of motor-sensory interactions in humans using a novel object localization task that enabled monitoring the relevant overt motor and sensory variables. We found that motor variables were dynamically controlled within each perceptual trial, such that they gradually converged to steady values. Training on this task resulted in improvement in perceptual acuity, which was achieved solely by changes in motor variables, without any change in the acuity of sensory readout. The within-trial dynamics is captured by a hierarchical closed-loop model in which lower loops actively maintain constant sensory coding, and higher loops maintain constant sensory update flow. These findings demonstrate interchangeability of motor and sensory variables in perception, motor convergence during perception, and a consistent hierarchical closed-loop perceptual model.
Influence of Highly Distinctive Structural Properties on the Excitability of Pyramidal Neurons in Monkey Visual and Prefrontal Cortices
Authors: Amatrudo Joseph M. , Weaver Christina M. , Crimins Johanna L. , Hof Patrick R. , Rosene Douglas L. , Luebke Jennifer I.
Published: October 2012

Whole-cell patch-clamp recordings and high-resolution 3D morphometric analyses of layer 3 pyramidal neurons inin vitroslices of monkey primary visual cortex (V1) and dorsolateral granular prefrontal cortex (dlPFC) revealed that neurons in these two brain areas possess highly distinctive structural and functional properties. Area V1 pyramidal neurons are much smaller than dlPFC neurons, with significantly less extensive dendritic arbors and far fewer dendritic spines. Relative to dlPFC neurons, V1 neurons have a significantly higher input resistance, depolarized resting membrane potential, and higher action potential (AP) firing rates. Most V1 neurons exhibit both phasic and regular-spiking tonic AP firing patterns, while dlPFC neurons exhibit only tonic firing. Spontaneous postsynaptic currents are lower in amplitude and have faster kinetics in V1 than in dlPFC neurons, but are no different in frequency. Three-dimensional reconstructions of V1 and dlPFC neurons were incorporated into computational models containing Hodgkin–Huxley and AMPA receptor and GABAAreceptor gated channels. Morphology alone largely accounted for observed passive physiological properties, but led to AP firing rates that differed more than observed empirically, and to synaptic responses that opposed empirical results. Accordingly, modeling predicts that active channel conductances differ between V1 and dlPFC neurons. The unique features of V1 and dlPFC neurons are likely fundamental determinants of area-specific network behavior. The compact electrotonic arbor and increased excitability of V1 neurons support the rapid signal integration required for early processing of visual information. The greater connectivity and dendritic complexity of dlPFC neurons likely support higher level cognitive functions including working memory and planning.
Optimization of a GCaMP Calcium Indicator for Neural Activity Imaging
Authors: Akerboom Jasper , Chen Tsai-Wen , Wardill Trevor J. , Tian Lin , Marvin Jonathan S. , Mutlu Sevinç , Calderón Nicole Carreras , Esposti Federico , Borghuis Bart G. , Sun Xiaonan Richard , Gordus Andrew , Orger Michael B. , Portugues Ruben , Engert Florian , Macklin John J. , Filosa Alessandro , Aggarwal Aman , Kerr Rex A. , Takagi Ryousuke , Kracun Sebastian , Shigetomi Eiji , Khakh Baljit S. , Baier Herwig , Lagnado Leon , Wang Samuel S.-H. , Bargmann Cornelia I. , Kimmel Bruce E. , Jayaraman Vivek , Svoboda Karel , Kim Douglas S. , Schreiter Eric R. , Looger Loren L.
Published: October 2012

Genetically encoded calcium indicators (GECIs) are powerful tools for systems neuroscience. Recent efforts in protein engineering have significantly increased the performance of GECIs. The state-of-the art single-wavelength GECI, GCaMP3, has been deployed in a number of model organisms and can reliably detect three or more action potentials in short bursts in several systemsin vivo. Through protein structure determination, targeted mutagenesis, high-throughput screening, and a battery ofin vitroassays, we have increased the dynamic range of GCaMP3 by severalfold, creating a family of “GCaMP5” sensors. We tested GCaMP5s in several systems: cultured neurons and astrocytes, mouse retina, andin vivoinCaenorhabditischemosensory neurons,Drosophilalarval neuromuscular junction and adult antennal lobe, zebrafish retina and tectum, and mouse visual cortex. Signal-to-noise ratio was improved by at least 2- to 3-fold. In the visual cortex, two GCaMP5 variants detected twice as many visual stimulus-responsive cells as GCaMP3. By combiningin vivoimaging with electrophysiology we show that GCaMP5 fluorescence provides a more reliable measure of neuronal activity than its predecessor GCaMP3. GCaMP5 allows more sensitive detection of neural activityin vivoand may find widespread applications for cellular imaging in general.
Mitotic Motors Coregulate Microtubule Patterns in Axons and Dendrites
Authors: Lin Shen , Liu Mei , Mozgova Olga I. , Yu Wenqian , Baas Peter W.
Published: October 2012

Microtubules are nearly uniformly oriented in the axons of vertebrate neurons but are non-uniformly oriented in their dendrites. Studies to date suggest a scenario for establishing these microtubule patterns whereby microtubules are transported into the axon and nascent dendrites with plus-ends-leading, and then additional microtubules of the opposite orientation are transported into the developing dendrites. Here, we used contemporary tools to confirm that depletion of kinesin-6 (also called CHO1/MKLP1 or kif23) from rat sympathetic neurons causes a reduction in the appearance of minus-end-distal microtubules in developing dendrites, which in turn causes them to assume an axon-like morphology. Interestingly, we observed a similar phenomenon when we depleted kinesin-12 (also called kif15 or HKLP2). Both motors are best known for their participation in mitosis in other cell types, and both are enriched in the cell body and dendrites of neurons. Unlike kinesin-12, which is present throughout the neuron, kinesin-6 is barely detectable in the axon. Accordingly, depletion of kinesin-6, unlike depletion of kinesin-12, has no effect on axonal branching or navigation. Interestingly, depletion of either motor results in faster growing axons with greater numbers of mobile microtubules. Based on these observations, we posit a model whereby these two motors generate forces that attenuate the transport of microtubules with plus-ends-leading from the cell body into the axon. Some of these microtubules are not only prevented from moving into the axon but are driven with minus-ends-leading into developing dendrites. In this manner, these so-called “mitotic” motors coregulate the microtubule patterns of axons and dendrites.
Proliferation of External Globus Pallidus-Subthalamic Nucleus Synapses following Degeneration of Midbrain Dopamine Neurons
Authors: Fan Kai Y. , Baufreton Jérôme , Surmeier D. James , Chan C. Savio , Bevan Mark D.
Published: October 2012

The symptoms of Parkinson's disease (PD) are related to changes in the frequency and pattern of activity in the reciprocally connected GABAergic external globus pallidus (GPe) and glutamatergic subthalamic nucleus (STN). In idiopathic and experimental PD, the GPe and STN exhibit hypoactivity and hyperactivity, respectively, and abnormal synchronous rhythmic burst firing. Following lesion of midbrain dopamine neurons, abnormal STN activity emerges slowly and intensifies gradually until it stabilizes after 2–3 weeks. Alterations in cellular/network properties may therefore underlie the expression of abnormal firing. Because the GPe powerfully regulates the frequency, pattern, and synchronization of STN activity, electrophysiological, molecular, and anatomical measures of GPe–STN transmission were compared in the STN of control and 6-hydroxydopamine-lesioned rats and mice. Following dopamine depletion: (1) the frequency (but not the amplitude) of mIPSCs increased by ∼70%; (2) the amplitude of evoked IPSCs and isoguvacine-evoked current increased by ∼60% and ∼70%, respectively; (3) mRNA encoding α1, β2, and γ2 GABAAreceptor subunits increased by 15–30%; (4) the density of postsynaptic gephyrin and γ2 subunit coimmunoreactive structures increased by ∼40%, whereas the density of vesicular GABA transporter and bassoon coimmunoreactive axon terminals was unchanged; and (5) the number of ultrastructurally defined synapses per GPe–STN axon terminal doubled with no alteration in terminal/synapse size or target preference. Thus, loss of dopamine leads, through an increase in the number of synaptic connections per GPe–STN axon terminal, to substantial strengthening of the GPe–STN pathway. This adaptation may oppose hyperactivity but could also contribute to abnormal firing patterns in the parkinsonian STN.
Effectiveness of eplerenone or spironolactone treatment in preserving renal function in primary aldosteronism
Authors: Fourkiotis Verena , Vonend Oliver , Diederich Sven , Fischer Evelyn , Lang Katharina , Endres Stephan , Beuschlein Felix , Willenberg Holger S , Rump Lars C , Allolio Bruno , Reincke Martin , Quinkler Marcus , _ _
Published: October 2012

Objective

Primary aldosteronism (PA) has deleterious effects on kidney function independent of blood pressure levels. Up to now, data on effectiveness of different PA therapies regarding renal function are scarce.

Design and methods

This prospective multi-center study included 29 patients with newly diagnosed PA evaluated before and 1 year after treatment initiation, and a second cohort including 119 patients who were evaluated 5.3 and 6.8 years after treatment initiation. Glomerular filtration rate (GFR), spot urine albumin excretion/urinary creatinine (UAE/Ucrea) ratio, biochemical parameters, and 24-h blood pressure were measured. In a larger cross-sectional cohort, renal function was evaluated depending on the type of treatment (adrenalectomy (ADX; n=86); spironolactone (n=65); and eplerenone (n=18)).

Results

GFR and UAE/Ucrea ratio significantly decreased in newly diagnosed PA patients after treatment initiation. In the second cohort, GFR and UAE/Ucrea ratio did not change during study period, and blood pressure was well controlled. In the larger cross-sectional cohort, no differences were seen in GFR and UAE/Ucrea ratio between PA patients on different treatment regimens. However, eplerenone treatment showed lower potassium levels and higher number of required antihypertensive medications.

Conclusions

Renal dysfunction with elevated albuminuria was seen in PA patients and was reversible after treatment initiation. Medical therapies with spironolactone or eplerenone seem to be as effective as ADX regarding renal function and blood pressure; however, sufficient daily doses need to be given.
Development of an Analytical Method for the Determination of Arsenic in Urine by Gas Chromatography‐mass Spectrometry for Biological Monitoring of Exposure to Inorganic Arsenic
Authors: Takeuchi Akito , Namera Akira , Kawasumi Yaeko , Imanaka Tsutoshi , Sakui Norihiro , Ota Hirokazu , Endo Yoko , Sumino Kimiaki , Endo Ginji
Published: October 2012

Development of an Analytical Method for the Determination of Arsenic in Urine by Gas Chromatography‐mass Spectrometry for Biological Monitoring of Exposure to Inorganic Arsenic: Akito TAKEUCHI, et al. Osaka Occupational Health Service Center, Japan Industrial Safety and Health Association—

Objectives

The purpose of this study was to develop an analytical method for the simultaneous determination of inorganic arsenic [As(III) and As(V)] and monomethylarsonic acid (MMA) in urine by gas chromatography‐mass spectrometry (GC‐MS) for the biological monitoring of exposure to inorganic arsenic.

Methods

Arsenic compounds (after reduction of arsenic to the trivalent state) were derivatized with 2,3dimercapto‐1‐propanol and then analyzed using a GC‐MS. The proposed method was validated according to the US Food and Drug Administration guidelines. The accuracy of the proposed method was confirmed by analyzing Standard Reference Material (SRM) 2669 (National Institute of Standards and Technology).

Results

Calibration curves showed linearity in the range 1−100 µg/l for each of the arsenic species, with correlation coefficients of >0.999. For each of the arsenic species, the limits of detection and quantification were 0.2 µg/l and 1 µg/l, respectively. The recoveries were 96−100%, 99−102% and 99−112% for As(III), As(V) and MMA, respectively. Intraday accuracy and precision were 82.7−99.8% and 0.9−7.4%, respectively. Interday accuracy and precision were 81.3−100.0% and 0.8−9.9%, respectively. The analytical values of SRM 2669 obtained by the proposed method were sufficiently accurate.

Conclusions

The proposed method overcame the disadvantages of high‐performance liquid chromatography with inductively coupled plasma mass spectrometry. It was a robust, selective and cost‐effective method suitable for routine analyses and could be useful for the biological monitoring of occupational exposure to inorganic arsenic.
Thin-film Micro-Batteries Based on Metal Nanoparticles
Authors: Peng Shuang , Du Wenjun , Rakesh Leela , Mellinger Axel , Kaya Tolga
Published: October 2012

We proposed the use of Copper (Cu) and Zinc (Zn) nanoparticles as the electrodes for thin-film microbatteries in the applications of micro-scale sensors. Compared to the widely used lithium-based batteries, Cu and Zn nanoparticles are less expensive, less prone to oxidation (thus involving simpler fabrication steps) and flammability, safe to use, and only requires very simple fabrication processes.Even though the voltage output is inherently smaller (∼1V) than conventional lithium-based batteries, it is sufficient for low-voltage Integrated Circuits (IC) technologies such as 130 nm and 90 nm channel length transistor processes.

Commercial paper will be used as the separator to demonstrate the battery capacity. Paper that acts as the separator is slurry-casted with nanoparticles (30-40 nm in size) on both sides. The thickness of the metal nanoparticles-coated thin films and the paper separator are 1 μm and 100 μm, respectively.

The electrodes were developed to achieve high conductivity (lower than 1 (Ω·cm)-1) with smooth surface, good adhesion, and flexibility. The metal nanoparticles will be formulated to slurry solutions for screen printing or ink-jet printing for the battery fabrication. For fabrication purposes, the slurries viscosity is approximately in the range of 10-12 cPs at the operating temperature, a surface tension between 28-33 dynes/cm. During the fabrication process including printing/coating and sintering, reductive environment is required to minimize the oxidation. AFM (Atomic Force Microscopy) and EDS (Energy Dispersive Spectroscopy) results will be employed to demonstrate the surface morphology as well as the percentages of metal oxides. Batteries will be tested with and without an ionic liquid for comparison. Humidity effects on the battery performance will also be discussed.

Different geometries that are designed to make the batteries with higher voltage or charge will be proposed. Characterization results will include the open-circuit voltage, dielectric property, charging and discharging curve, capacitance and capacity, AFM of the surface test, EDS of the electrodes and the SEM (Scanning Electron microscopy) of the particles.Ourresearch suggest that conductive paper can be scalable and could make high-performance energy storage and conversion devices at low cost and would bring new opportunities for advanced applications.
Enzymatic Synthesis of Polyaniline/Graphite Oxide Nanocomposites
Authors: Guerrero-Bermea C. , Sepulveda-Guzman S. , Cruz-Silva R.
Published: October 2012

In this work, we prepared graphite oxide (GO)/polyaniline nanocomposites by enzymatic polymerization of aniline in an aqueous dispersion of graphite oxide. Two GO dispersions with sheets having an average lateral size of 12.50 μm and 247 nm were used. The enzymatic polymerization was carried out in aqueous acidic medium using toluenesulfonic acid (TSA) as doping agent, horseradish peroxide (HRP) as catalyst, and hydrogen peroxide as oxidizer. The polymerization reaction was studied using 1.0, 2.5 and 5 wt % of GO and nGO dispersions. No changes were observed in the catalytic activity of the peroxidase during the enzymatic synthesis due to the additionof GO sheets. Scanning electron microscopy images show that PANI colloids were attached on GO sheets. The PANI-GO colloids were characterized by ultraviolet–visible spectroscopy and Fourier transformed infrared spectroscopy, whereas their colloidal stability was evaluated at different pHs. The UV-vis spectroscopy study revealed that GO affects the electronic conjugation of PANI modifying its absorption spectrum.
SERS Biotags (SBTs) for the Quantitative Ratiometric Discrimination between Noncancerous and Cancerous Prostate Cells
Authors: Pallaoro Alessia , Braun Gary , Moskovits Martin
Published: October 2012

We report on a multiplexed, ratiometric method that can confidently distinguish between cancerous and non-cancerous epithelial prostate cells in vitro, as demonstrated by a double blind experiment. The technique is based on bright SERRS biotags (SBTs) infused with unique Raman reporter molecules, and carrying cell-specific peptides. Two sets of SERRS biotags were used. One targets the neuropilin-1 (NRP) receptors of cancer cells through the RPARPAR peptide. The other functions as a positive control (PC) and binds to both non-cancerous and cancer cells through the HIV derived TAT peptide. Averaging the SERRS signal over a given cell yielded an NRP/PC ratio from which a robust quantitative measure of the overexpression of the NRP-1 by the cancer cell line was extracted. The use of a local, on-cell reference produces quantitative, statistically robust measures of overexpression independent of such sources of uncertainty such as variations in the location of the focal plane, the local cell concentration and turbidity.
Study of the Cu, Mn, Pb and Zn dynamics in soil, plants and bee pollen from the region of Teresina (PI), Brazil
Authors: Silva Aline S. , Araújo Sebastião B. , Souza Darcet C. , Silva Fábio A. Santos e
Published: October 2012

The purpose of this study is to characterize native bee plants regarding their capacity to extract and accumulate trace elements from the soil and its consequences to the sanity of the produced pollen. The trace elements Cu, Mn, Pb and Zn were analyzed in soil, plants and bee pollen from Teresina region (PI), Brazil, by flame atomic absorption spectrophotometer. Considering the studied plant species, Cu and Pb metals presented in the highest levels in the roots of B. platypetala with 47.35 and 32.71 μg.mL-1 and H. suaveolens with 39.69 and 17.06 μg.mL-1, respectively, while in the aerial parts Mn and Zn metals presented the highest levels in S. verticillata with 199.18 and 85.73 μg.mL-1. In the pollen, the levels of Cu, Mn, Pb and Zn vary from 5.44 to 11.75 μg.mL-1; 34.31 to 85.75 μg.mL-1; 13.98 to 18.19 μg.mL-1 and 50.19 to 90.35 μg.mL-1, respectively. These results indicate that in the apicultural pasture the translocation (from soil to pollen) of Mn and Zn was more effective than in case of Cu and Pb, therefore, the bee pollen can be used as food supplement without causing risks to human health.
Primeiro registro de Guyalna cuta em pinhão-manso no estado de Mato Grosso do Sul
Authors: Oliveira Harley Nonato de , Martinelli Nilza Maria , Bellon Patrícia Paula , Maccagnan Douglas Henrique Bottura
Published: October 2012

Trata-se do primeiro registro de ocorrência de Guyalna cuta (Walker) (Hemiptera: Cicadidae) em pinhão-manso, Jatropha curcas L. (Euphorbiaceae) no Estado de Mato Grosso do Sul. Adultos desse inseto foram observados na parte aérea da planta, durante novembro e dezembro de 2008 e de 2009. Em Mato Grosso do Sul, existem plantios comerciais e experimentais do pinhão-manso, tornando-se necessários estudos relacionados a este inseto, a fim de prevenir eventuais danos à cultura.
Book-tax differences e gerenciamento de resultados no mercado de ações do Brasil
Authors: Ferreira Felipe Ramos , Martinez Antonio Lopo , Costa Fábio Moraes da , Passamani Renato Rovetta
Published: October 2012

Este estudo verifica a relação entre book-tax differences (BTD) e gerenciamento de resultado em companhias listadas na BM&FBovespa no período de 2005 a 2009. Metodologicamente, foram empregadas duas abordagens: (i) distribuição de frequências e (ii) accruals discricionários - Modelo Jones Modificado. Os achados indicam uma relação diretamente proporcional entre a BTD e os accruals discricionários. Foram identificadas evidências de que as entidades preponderantemente gerenciam seus resultados na mesma direção do sinal observado da BTD, além de buscarem apresentar o montante de BTD em nível e em variação em torno do ponto zero e desta forma evitar sinalizar baixa qualidade do lucro. Adicionalmente, foram encontradas evidências de que o tamanho da firma e a adoção do regime tributário de transição estão relacionados de forma inversamente proporcional ao nível dos accruals discricionários.
Theory of reasoned action for continuous improvement capabilities: a behavioral approach
Authors: Yen-Tsang Chen , Csillag João Mário , Siegler Janaina
Published: October 2012

The importance of interaction between Operations Management (OM) and Human Behavior has been recently re-addressed. This paper introduced the Reasoned Action Theory suggested by Froehle and Roth (2004) to analyze Operational Capabilities exploring the suitability of this model in the context of OM. It also seeks to discuss the behavioral aspects of operational capabilities from the perspective of organizational routines. This theory was operationalized using Fishbein and Ajzen (F/A) behavioral model and a multi-case strategy was employed to analyze the Continuous Improvement (CI) capability. The results posit that the model explains partially the CI behavior in an operational context and some contingency variables might influence the general relations among the variables involved in the F/A model. Thus intention might not be the determinant variable of behavior in this context.
Frequência de comportamentos alimentares inadequados e sua relação com a insatisfação corporal em adolescentes
Authors: Silva Tatiana Araújo Bertulino da , Ximenes Rosana Christine Cavalcanti , Holanda Manuelle de Araújo , Melo Michel Gomes de , Sougey Everton Botelho , Couto Geraldo Bosco Lindoso
Published: October 2012

OBJETIVO: Descrever a relação entre a frequência de insatisfação com a imagem corporal e a presença de sintomas de transtornos alimentares em adolescentes. MÉTODOS: O estudo foi realizado com uma amostra de 300 adolescentes, de ambos os sexos, na faixa etária de 10 a 17 anos, estudantes de uma escola pública estadual da cidade do Recife, Brasil. Foram utilizadas as versões brasileiras para adolescentes de três escalas autoaplicativas (EAT-26, BITE e BSQ), além de um questionário contendo dados biodemográficos. RESULTADOS: A frequência de sintomas de transtornos alimentares detectada pelo EAT-26 foi de 32,3%; 2,3% para comportamentos sugestivos de bulimia nervosa, por meio da escala BITE, tendo 36,67% dos alunos apresentado padrão alimentar não usual; 5,6% apresentaram insatisfação com a imagem corporal; 8,6% demonstraram tendência à preocupação com a insatisfação com a imagem corporal e 17,6% apresentaram leve insatisfação, além de 66,3%, que mostraram normalidade em relação à sua forma corporal. CONCLUSÃO: Os adolescentes apresentaram níveis de alteração na autoimagem corporal, com alta frequência de insatisfação da imagem corporal, podendo apresentar associação com comportamentos alimentares inadequados.
Alterações anatômicas induzidas por Meloidogyne enterolobii (=M. mayaguensis) e Meloidogyne javanica em tomateiros resistentes a meloidoginose
Authors: Westerich Juliana Nogueira , Rodella Roberto Antonio , Rosa Juliana Magrinelli Osório , Wilcken Silvia Renata Siciliano
Published: October 2012

A resistência de tomateiros (Solanum lycopersicum L.) a M. incognita, M. javanica e M. arenaria, conferida pela presença do gene Mi, não contempla a espécie M. enterolobii (=M. mayaguensis). O objetivo da pesquisa foi verificar as alterações anatômicas causadas por M. enterolobii no sistema radicular de porta-enxertos de tomateiro com o gene de resistência Mi ('Magnet' e Helper M') e compará-las com as causadas por M. javanica. As observações anatômicas das raízes foram feitas com auxílio de microscópio de luz e os aspectos mais relevantes foram fotografados. Com base em contagens e mensurações do tamanho dos sítios de alimentação e das células gigantes, foram efetuadas analises utilizando o método estatístico de Análise de Agrupamento. O aparecimento de células nutridoras incitadas por M. enterolobii foi verificado em ambos os porta-enxertos de tomateiro, entre 10 e 17 dias após a inoculação (DAI). O número e a área de sítios de alimentação e de células gigantes foram menores aos 17 DAI do que aos 24 DAI. Nesta época (24 DAI), foram observados sítios de alimentação constituídos pela presença de várias células nutridoras multinucleadas, com parede celular espessa, citoplasma denso e granuloso. Os tecidos vasculares apresentaram-se comprimidos e desorganizados, foi observada, também, hipertrofia de células do parênquima cortical. As raízes inoculadas com M. javanica não apresentaram alterações anatômicas.
Produção e sensibilidade de isolados brasileiros de Xanthomonas axonopodis pv. citri à bacteriocinas
Authors: Bonini Marcel , Rodrigues Neto Júlio , Maringoni Antonio Carlos
Published: October 2012

Este trabalho teve por objetivo avaliar a produção e a sensibilidade de 48 isolados brasileiros de X. axonopodis pv. citri (Xac) à bacteriocinas. Pelos resultados obtidos, nenhum isolado de Xac foi sensível às bacteriocinas produzidas pelos isolados bacterianos avaliados.
Levantamento revela a predominância do Lettuce mottle virus em três regiões produtoras de alface no Estado de São Paulo
Authors: De Marchi Bruno Rossitto , Spadotti David Marques de Almeida , Oliveira Milena Leite de , Sanches Márcio Martinello , Krause-Sakate Renate , Pavan Marcelo Agenor
Published: October 2012

Entre os problemas fitossanitários da cultura da alface estão as doenças causadas por vírus. Três vírus causam sintomas de mosaico praticamente indistinguíveis: o Lettuce mosaic virus (LMV, Potyvirus), o Lettuce mottle virus (LeMoV, Sequivirus) e o Bidens mosaic virus (BiMV, Potyvirus). Através de RT-PCR utilizando-se oligonucleotídeos específicos para cada um destes vírus, amostras de alface e plantas invasoras, preferencialmente com sintoma de mosaico, foram coletadas em campos de produção de alface das regiões de Mogi das Cruzes, Campinas e Bauru no Estado de São Paulo e analisadas para a presença dos vírus. Verificou-se que o LeMoV foi o vírus encontrado com maior freqüência, seguido do LMV. A ocorrência de BiMV em alface foi extremamente baixa e restrita às regiões de Campinas e Bauru, onde também foi verificado em plantas invasoras como Bidens pilosa e Galinsoga parviflora. Esta ultima é hospedeira dos três vírus.
Germinação do banco de sementes de espécies nativas sob dossel de espécies exóticas
Authors: Carmo Flávia Maria da Silva , Poeiras Lucas Marinho , Gonçalves Andrea Brandão , Mello Sabrina Marinho de , Meira Neto João Augusto Alves , Borges Eduardo Euclydes de Lima e , Silva Alexandre Francisco da
Published: October 2012

As sementes no solo desempenham o importante papel de promover a regeneração da vegetação e a conservação da biodiversidade local, mas, a despeito dessa importância, estão sujeitas a fatores bióticos e abióticos que podem inibir sua germinação, entre eles efeitos alelopáticos desencadeados pelas plantas que estão presentes no ambiente do solo. Neste trabalho foi testada a hipótese de que a germinação das sementes presentes no banco do solo sob vegetação de Floresta Estacional Semidecidual (FES) é inibida sob o dossel de espécies arbóreas exóticas. Foram coletadas 50 amostras simples de 0,25 x 0,25 x 0,05 m do solo em um fragmento de FES, que foram homogeneizadas, constituindo amostra composta. Desta, foram retiradas amostras que foram submetidas a quatro tratamentos: depositadas em casa de vegetação (SMN-CV); devolvidas ao fragmento de mata (SMN-MN); depositadas sob dossel homogêneo de Pinus elliottii (SMN-P); e alocadas sob plantio homogêneo de Eucalyptus sp. (SMN-E). Foram coletadas, também, amostras de solo sob dossel de P. elliotti (SP-CV) e de Eucalyptus sp. (SE-CV), que foram transferidas para casa de vegetação. A cada 15 dias, o número de plantas foi contado em cada amostra e as plantas obtidas, identificadas quando possível. Foram obtidas, ao todo, 515 plantas de 15 famílias botânicas, 21 gêneros e 13 morfoespécies. A análise de variância dos dados e a comparação das médias pelo teste de Tukey-Kramer a 0,01% evidenciaram que não existem diferenças estatisticamente significativas entre o número de plantas obtidas em cada local. Esses resultados indicam que a baixa densidade e diversidade de plantas frequentemente verificadas no subosque de P. elliotti e Eucalyptus sp. não estão diretamente relacionadas com efeitos supressores promovidos pela presença dessas espécies, suportando dados recentes da literatura que apontam os plantios florestais de espécies exóticas como possíveis áreas de conservação da biodiversidade, em oposição à alcunha de "desertos verdes" que lhe são atribuídos.
Murcha-bacteriana: disseminação do patógeno e efeitos da doença sobre a clonagem do eucalipto
Authors: Mafia Reginaldo Gonçalves , Alfenas Acelino Couto , Penchel Filho Ricardo Miguel , Ferreira Maria Alves , Alfenas Rafael Ferreira
Published: October 2012

Este trabalho objetivou estudar a disseminação de Ralstonia solanacearum por meio de mudas e avaliar os efeitos da murcha-bacteriana sobre a produtividade na clonagem do eucalipto. Amostras de minicepas, miniestacas e mudas de sete clones foram avaliadas quanto à presença de infecções bacterianas. Em experimento específico, avaliou-se o substrato de enraizamento como fonte de inóculo do patógeno. Em intervalos mensais, determinaram-se o enraizamento médio e o índice de produtividade (IP), visando avaliar os efeitos da doença sobre a produtividade de minicepas. Constatou-se a presença do patógeno em minicepas de cinco clones, enquanto todas as mudas de todos os setes clones avaliados apresentaram a doença. Essa diferença comprovou que a disseminação do patógeno e a transmissão da doença ocorreram durante o processo de clonagem do eucalipto. O substrato de enraizamento foi eficiente para a sobrevivência do patógeno e como fonte de inóculo para a doença. As mudas sem sintomas e com infecções sistêmicas provaram o potencial de transmissão do patógeno para o campo no sistema de propagação clonal do eucalipto. Os estresses fisiológicos causados pelas infecções bacterianas reduziram quatro vezes o IP dos minijardins clonais. As medidas adotadas foram eficientes para a erradicação da doença no viveiro e para evitar a disseminação do patógeno para o campo.
Efeito do volume de tubetes na produção de mudas de Calophyllum brasiliense e Toona ciliata
Authors: Lisboa Alysson Canabrava , Santos Paulo Sérgio dos , Oliveira Neto Sílvio Nolasco de , Castro Daniele Nunes de , Abreu Alan Henrique Marques de
Published: October 2012

A demanda por informações silviculturais de espécies florestais alternativas para reflorestamentos com fins econômicos, entre as quais incluem os métodos de produção de mudas, tem aumentado nos últimos anos. Neste trabalho, avaliou-se a influência de volumes de tubetes, com dimensões de 115, 180 e de 280 cm³, no crescimento de mudas de guanandi (Calophyllum brasiliense Cambess.) e cedro-australiano (Toona ciliata M. Roem. var. australis (F. Muell.) Bahadur). O substrato utilizado foi composto por uma mistura de 80% de substrato comercial e 20% de argila. Foram avaliados o diâmetro de colo e a altura das mudas aos 60, 90, 120 e 150 dias após a repicagem. Nessa última ocasião, determinou-se também o peso de massa seca da parte aérea, do sistema radicular e total, bem como o Índice de Qualidade de Dickson. Houve efeito do volume do tubete sobre as características das mudas, sendo o cedro-australiano a espécie mais responsiva. Conclui-se que para o guanandi o tubete mais indicado é o de 180 cm³ e para o cedro-australiano, o de 280 cm³.
Caracterização florística e ecológica da arborização de praças públicas do município de Guarapuava, PR
Authors: Kramer João Alberto , Krupek Rogério Antonio
Published: October 2012

Este estudo teve por objetivo realizar o levantamento florístico e avaliar algumas características ecológicas das principais praças públicas do Município de Guarapuava, região centro-sul do Estado do Paraná. Os trabalhos de campo foram realizados no período de janeiro de 2007 a março de 2009. Foram identificadas 98 espécies, distribuídas em 43 famílias. A abundância mensurada foi de 1.143 indivíduos. A espécie mais bem distribuída foi Tipuana tipu, enquanto as mais abundantes, Grevillea robusta e Platanus acerifolia. Com relação à origem, a maioria das espécies, tanto em riqueza quanto em abundância, é exótica. Os valores de riqueza, abundância, H' e equidade foram relativamente altos, enquanto que os de dominância e similaridade, foram baixos. Apesar do alto valor de riqueza e diversidade, a alta frequência de poucas espécies e o baixo número de indivíduos por área amostrada têm colocado as praças públicas da área avaliada em condições ecológicas ainda longe das ideais. O alto número de espécies exóticas reflete, ainda, a falta de interesse na conservação da flora regional.
Natural regeneration in abandoned fields following intensive agricultural land use in an Atlantic Forest Island, Brazil
Authors: Silvestrini Milene , Cysneiro Airton de Deus , Lima Aline Lopes , Veiga Larissa Giorgeti , Isernhagen Ingo , Tamashiro Jorge Yoshio , Gandolfi Sergius , Rodrigues Ricardo Ribeiro
Published: October 2012

The time required to regrowth a forest in degraded areas depends on how the forest is removed and on the type of land use following removal. Natural regeneration was studied in abandoned old fields after intensive agricultural land use in areas originally covered by Brazilian Atlantic Forests of the Anchieta Island, Brazil in order to understand how plant communities reassemble following human disturbances as well as to determine suitable strategies of forest restoration. The fields were classified into three vegetation types according to the dominant plant species in: 1) Miconia albicans (Sw.) Triana (Melastomataceae) fields, 2) Dicranopteris flexuosa (Schrader) Underw. (Gleicheniaceae) thickets, and 3) Gleichenella pectinata (Willd.) Ching. (Gleicheniaceae) thickets. Both composition and structure of natural regeneration were compared among the three dominant vegetation types by establishing randomly three plots of 1 x 3 m in five sites of the island. A gradient in composition and abundance of species in natural regeneration could be observed along vegetation types from Dicranopteris fern thickets to Miconia fields. The gradient did not accurately follow the pattern of spatial distribution of the three dominant vegetation types in the island regarding their proximity of the remnant forests. A complex association of biotic and abiotic factors seems to be affecting the seedling recruitment and establishment in the study plots. The lowest plant regeneration found in Dicranopteris and Gleichenella thickets suggests that the ferns inhibit the recruitment of woody and herbaceous species. Otherwise, we could not distinguish different patterns of tree regeneration among the three vegetation types. Our results showed that forest recovery following severe anthropogenic disturbances is not direct, predictable or even achievable on its own. Appropriated actions and methods such as fern removal, planting ground covers, and enrichment planting with tree species were suggested in order to restore the natural forest regeneration process in the abandoned old fields.
Composição e estrutura de comunidades arbóreas de cerrado stricto sensu no norte do Tocantins e sul do Maranhão
Authors: Medeiros Marcelo Brilhante de , Walter Bruno Machado Teles
Published: October 2012

Este trabalho teve por objetivo avaliar a composição e a estrutura da comunidade arbórea de cerrado stricto sensu (s.s.) no município de Filadélfia (norte do Tocantins) e compará-la com a mesma fitofisionomia em uma área adjacente na bacia do rio Tocantins, no município de Carolina (MA), na província norte-nordeste do Cerrado. Em Filadélfia foram alocadas aleatoriamente 10 parcelas de 20 × 50m, totalizando um ha. Todos os indivíduos lenhosos com diâmetro de caule > 5 cm, medidos a 30 cm do solo, foram incluídos. Os dados de composição e estrutura da vegetação em Carolina foram obtidos em literatura. Dois métodos de análise foram empregados: UPGMA, adotando-se o índice de Sørensen, e TWINSPAN, agrupando parcelas e espécies. Em Filadélfia foram encontrados 789 indivíduos, 53 espécies e 44 gêneros; H' foi igual a 3,32 nats. ind-1 e J'=0,83. Nove espécies (Qualea parviflora, Pouteria ramiflora, Curatella americana, Hirtella ciliata, Qualea grandiflora, Parkia platycephala, Diospyros sericea, Stryphnodendron sp. e Stryphnodendron rotundifolium) representaram 49,9% do VI total. Das 69 espécies encontradas nas duas áreas, 36 foram comuns. O índice de Sørensen mostrou baixa similaridade florística entre Carolina e Filadélfia. A análise por TWINSPAN também mostrou similaridade qualitativa e quantitativa reduzidas entre as áreas. Os resultados revelaram que as comunidades de cerrado s.s. são diferenciadas entre e dentre as áreas, com provável influência das diferenças de solo. Não obstante, a fitossociologia foi similar a de outros estudos na região e a composição é característica da província fitogeográfica norte/nordeste do bioma Cerrado, contendo elementos típicos como Hirtella ciliata, Platonia insignis e Caryocar coriaceum.
Distribution of tree species in a geomorphological and pedological gradient of submontane semidecidual seasonal forest in the vicinity of Rio Doce state park, Minas Gerais
Authors: Souza Priscila Bezerra de , Lelis João José , Schaefer Carlos Ernesto Gonçalves Reynaud , Souza Agostinho Lopes de , Meira Neto João Augusto Alves
Published: October 2012

The objective of this study was to test the hypothesis that the distribution of tree species in a fragment of submontane seasonal semideciduous forest, a buffer zone in the Parque Estadual do Rio Doce, Minas Gerais, is influenced by geomorphological and weather and soil variables, therefore it can represent a source of information for the restoration of degraded areas where environmental conditions are similar to those of the study area. A detailed soil survey was conducted in the area by sampling three soil profiles per slope segment, totaling 12 profiles. To sample the topsoil, four composite samples were collected from the 10-20 cm layers in each topographic range totaling 16 composite samples. In the low ramp and the lower and upper concave slopes, the texture ranged from clay to sandy-clay. The soil and topographic gradient was characterized by changes in the soil physical-chemical properties. The soil in the 10-20 cm sampled layer was sandier, slightly more fertile and less acid in the low ramp than the clayer soil, nutrient-poor and highly acid soil at the top. The soil conditions in the lower and upper slope of the sampled layers, in turn, were intermediate. The P levels were limiting in all soils. The species distribution along the topographic gradient was associated with variations in chemical fertility, acidity and soil texture. The distribution of Pera leandri, Astronium fraxinifolium, Pouteria torta, Machaerium brasiliense and Myrcia rufipes was correlated with high aluminum levels and to low soil fertility and these species may be indicated for restoration of degraded areas on hillsides and hilltops in regions where environmental conditions are similar. The distribution of Pouteria venosa, Apuleia leiocarpa and Acacia polyphylla was correlated with the less acid and more fertile soil in the environment of the low ramps, indicating the potential for the restoration of similar areas.
Prognose do crescimento e da produção em classes de diâmetro para povoamentos desbastados de Eucalyptus grandis no sul do Brasil
Authors: Retslaff Fabiane Aparecida de Souza , Figueiredo Filho Afonso , Dias Andrea Nogueira , Bernett Luiz Gastão , Figura Marco Aurélio
Published: October 2012

Este trabalho teve como objetivo desenvolver modelos de crescimento e produção em classes de diâmetro para plantios de Eucalyptus grandis submetidos a desbastes. Os dados utilizados na modelagem foram provenientes de plantios de Eucalyptus grandis localizados no Município de Telêmaco Borba, Estado do Paraná, e oriundos de parcelas permanentes, temporárias e de inventário pré-corte, com idades variando de 2,5 a 26,5 anos. A função de densidade de probabilidade Weibull foi utilizada para gerar a distribuição diamétrica. O processo de modelagem de atributos do povoamento foi dividido em etapas, considerando-se os estágios de desenvolvimento do povoamento. Dessa maneira, dois sistemas de prognose foram gerados para predizer os atributos na idade do primeiro desbaste, segundo desbaste ou para o corte final. Os atributos modelados foram aqueles necessários para recuperação dos parâmetros da função Weibull nas idades de intervenção pelo método dos momentos. Para avaliação das prognoses, utilizaram-se o teste de aderência de Kolmogorov-Smirnov e o teste de identidade L&O proposto por Leite e Oliveira (2002). Os dois sistemas de prognose apresentaram boas estimativas de ajuste e precisão. A metodologia empregada possibilitou simular o crescimento e produção em plantios de Eucalyptus grandis ao longo da rotação, gerando resultados adequados, principalmente, para o corte final, quando são colhidas as melhores árvores com maiores valores agregados.
Critical levels of organic acids on seed germination and seedling growth of wheat
Authors: Tunes Lilian Madruga de , Avelar Suemar Alexandre Gonçalves , Barros Antonio Carlos Souza Albuquerque , Pedroso Daniele Cardoso , Muniz Marlove Fátima Brião , Menezes Nilson Lemos de
Published: October 2012

The objective of this study was to determine the responses of the wheat cultivars CD 108 and CD 111 for tolerance to organic acids. The effects of five concentrations of the three main acids formed in the soil were studied: acetic acid (0, 4, 8, 12 and 16 mM), propionic acid (0, 4, 8, 12 and 16 mM) and butyric acid (0, 2, 4, 8 and 12 mM). Tests included germination, shoot length, root length and dry weight of shoot and root. The variable root length is the most responsive variable for all the acids tested and the critical level of toxicity of acetic, propionic and butyric acids, which reduced root length by at least 50% was 9.0, 8.5 and 4.0 mM respectively. It was concluded that the presence of acetic, propionic and butyric acids in the germination substratum of wheat seeds of the cultivars CD 111 and CD 108 reduced seedling development, mainly by reducing the length of the radicles.
Physiological quality of coffee seeds produced under different levels of solar radiation and maturation stages
Authors: Baliza Danielle Pereira , Caixeta Franciele , Pinho Édila Vilela de Resende Von , Cunha Rodrigo Luz da , Martins Denize Carvalho , Rosa Sttela Dellyzete Veiga Franco da
Published: October 2012

In Brazil, although the coffee plantations are predominantly grown under full sunlight, the use of agroforestry systems can lead to socioeconomic advantages, thus providing a favorable environment to the crop by promoting its sustainability as well as environmental preservation. However, there is a lack of information on physiological quality of the coffee seeds produced under different levels of solar radiation. Within this context, the objective of this study was to evaluate the influence of different levels of solar radiation and maturation stages on the physiological quality of coffee (Coffea arabica L.) seeds, cv. Acaiá Cerrado MG-1474. Three levels of solar radiation (plants grown under full sunlight; under plastic screens of 35% shading; and under plastic screens of 50% shading) and three maturation stages (cherry, greenish-yellow and green) were assessed. Physiological quality of seeds was assessed by using germination test, first count of germination, abnormal seedlings, dead seeds, and seedlings with open cotyledonary leaves. Electrophoretic analysis of isoenzymes catalase, esterase, superoxide dismutase and peroxidase was also performed. With the evolution of development the coffee seeds presents increases on physiological quality, and at its beginning the seeds show improvements on quality with the reduction of solar radiation.