bluuebunny/crossref_metadata_2025 huggingface dataset:
Meal consumption is ineffective at maintaining or correcting water balance in a desert lizard, Heloderma suspectum
Authors: Wright Christian D. , Jackson Marin L. , DeNardo Dale F.
Published: March 2013

Many xeric organisms maintain water balance by relying on dietary and metabolic water rather than free water, even when free water may be available. For such organisms, hydric state may influence foraging decisions, since meal consumption is meeting both energy and water demands. To understand foraging decisions it is vital to understand the role of dietary water in maintaining water balance. We investigated whether meal consumption was sufficient to maintain water balance in captive Gila monsters (Heloderma suspectum) at varying levels of dehydration. Gila monsters could not maintain water balance over long time scales through meal consumption alone. Animals fed a single meal took no longer to dehydrate than controls when both groups were deprived of free water. Additionally, meal consumption imparts an acute short-term hydric cost regardless of hydration state. Meal consumption typically resulted in a significant elevation in osmolality at 6 h post-feeding, and plasma osmolality never fell below pre-feeding levels despite high water content (~70%) of meals. These results failed to support our hypothesis that dietary water is valuable to Gila monsters during seasonal drought. When considered in conjunction with previous research, these results demonstrate that Gila monsters, unlike many xeric species, are heavily reliant on seasonal rainfall and the resulting free-standing water to maintain water balance.
Gait transitions and modular organization of mammal locomotion
Authors: Maes Ludovic , Abourachid Anick
Published: March 2013

Quadrupedal locomotion is the result of complex interactions between biomechanical and neural systems. During steady gaits both systems are in stable states. When the animal changes its speed, transitions between gaits can occur where the different coordination parameters are dissociated. Consequently, transitions are the periods where it is possible to detect and identify those parameters involved in the mechanical or neural control of locomotion. We study the interlimb coordination using a sequential method (APS) to measure the footfall patterns of dogs when accelerating and decelerating from 1.5ms-1 to more than 6ms-1 and conversely. We obtained 383 transitions between all the symmetrical and asymmetrical gaits used by the dogs. The analysis of the interlimb coordination modifications and of each foot parameter showed that mechanics drive the stance phase whereas the coordination is controlled during the swing phase. Furthermore, the comparison of the transition patterns between all gaits reveals the modular organization of locomotion: a pectoral module coordinates the two fore limbs, a pelvic module coordinates the two hind limbs and an axial module coordinates the two pairs and the trunk motion. The three modules cooperate to give rise to template of stable inter-limb coordination pattern, such as the walks, the trot or the gallop.
Is there a Trade-Off between Inflation and Output Stabilization?
Authors: Justiniano Alejandro , Primiceri Giorgio E , Tambalotti Andrea
Published: March 2013

We find that the answer is no in an estimated DSGE model of the US economy in which exogenous movements in workers' market power are not a major driver of observed economic fluctuations. If they are, the tension between the conflicting stabilization objectives of monetary policy increases, but with negligible effects on the equilibrium behavior of the economy under optimal policy. (JEL E12, E23, E24, E31, E32, E52)
Blunt Instruments: Avoiding Common Pitfalls in Identifying the Causes of Economic Growth
Authors: Bazzi Samuel , Clemens Michael A
Published: March 2013

Concern has intensified in recent years that many instrumental variables used in widely-cited growth regressions may be invalid, weak, or both. Attempts to remedy this general problem remain inadequate. We show how a range of published studies can offer more evidence that their results are not spurious. Key steps include: grounding growth regressions in more generalized theoretical models, deployment of new methods for estimating sensitivity to violations of exclusion restrictions, opening the “black box” of GMM with supportive evidence of instrument strength, and utilization of weak-instrument robust tests and estimators. (JEL C52, E23, F35, O41, O47)
Monetary Commitment and Fiscal Discretion: The Optimal Policy Mix
Authors: Gnocchi Stefano
Published: March 2013

We study a noncooperative policy game between monetary and fiscal policy, where only monetary policy can commit to future actions. The equilibrium outcome of the game depends on the strategies available to the monetary policymaker. If strategies are left unrestricted, the central bank can alter the incentives of the fiscal authority in a way that replicates the full commitment solution. If the central bank cannot commit to respond to fiscal policy, the fiscal authority generates fluctuations in government expenditure that undermine the stabilization goals of the central bank. (JEL E12, E23, E31, E52, E58, E62)
Uncertainty and Economic Activity: Evidence from Business Survey Data
Authors: Bachmann Rüdiger , Elstner Steffen , Sims Eric R
Published: March 2013

This paper uses survey expectations data to construct empirical proxies for time-varying business-level uncertainty. Access to the micro data from the German IFO Business Climate Survey permits construction of uncertainty measures based on both ex ante disagreement and ex post forecast errors. Ex ante disagreement is strongly correlated with dispersion in ex post forecast errors. Surprise movements in either measure lead to significant reductions in production that abate fairly quickly. We extend our analysis to US data, measuring uncertainty with forecast disagreement from the Business Outlook Survey. Surprise increases in forecast dispersion lead to more persistent reductions in production than in the German data. (JEL C53, C83, D81, E23, E27, E32, E37)
Neuronal Correlates of View Representation Revealed by Face-View Aftereffect
Authors: Noudoost Behrad , Esteky Hossein
Published: March 2013

Recognition of face-views is a crucial component of our social behavior. However, little is known about the neuronal basis of face-view recognition. Recent psychophysical studies have shown that adaptation to a particular face-view changes perception of other views in humans. To understand the neuronal basis of face-view representation and the mechanisms involved in face-view adaptation, we studied the responses of inferotemporal (IT) cortex neurons before and after face-view adaptation. We first used face-view adaptation to show that monkeys, as well as humans, exhibit face-view aftereffect, suggesting the presence of a view-sensitive representation in primates. Then, we recorded from IT neurons of monkeys and found that changes in responses of these neurons can account for changes in perception of face views attributable to adaptation, indicating IT as a neural correlate of face-view perception. More importantly, we provide evidence that IT neurons with wide-view tuning not only conveyed face-view information but also exhibited neural signatures of view aftereffect before neurons with narrower tuning. Our findings show that view-dependent representation of objects does not necessarily depend on narrow-tuned neurons. The finding that wide-view tuned neurons account for view-specific perceptual changes implies the importance of accumulating sensitivity and tolerance at the level of IT neurons, as the final stage of visual object recognition.
Coordinated Population Activity Underlying Texture Discrimination in Rat Barrel Cortex
Authors: Safaai Houman , von Heimendahl Moritz , Sorando Jose M. , Diamond Mathew E. , Maravall Miguel
Published: March 2013

Rodents can robustly distinguish fine differences in texture using their whiskers, a capacity that depends on neuronal activity in primary somatosensory “barrel” cortex. Here we explore how texture was collectively encoded by populations of three to seven neuronal clusters simultaneously recorded from barrel cortex while a rat performed a discrimination task. Each cluster corresponded to the single-unit or multiunit activity recorded at an individual electrode. To learn how the firing of different clusters combines to represent texture, we computed population activity vectors across moving time windows and extracted the signal available in the optimal linear combination of clusters. We quantified this signal using receiver operating characteristic analysis and compared it to that available in single clusters. Texture encoding was heterogeneous across neuronal clusters, and only a minority of clusters carried signals strong enough to support stimulus discrimination on their own. However, jointly recorded groups of clusters were always able to support texture discrimination at a statistically significant level, even in sessions where no individual cluster represented the stimulus. The discriminative capacity of neuronal activity was degraded when error trials were included in the data, compared to only correct trials, suggesting a link between the neuronal activity and the animal's performance. These analyses indicate that small groups of barrel cortex neurons can robustly represent texture identity through synergistic interactions, and suggest that neurons downstream to barrel cortex could extract texture identity on single trials through simple linear combination of barrel cortex responses.
Learning Increases Intrinsic Excitability of Hippocampal Interneurons
Authors: McKay Bridget M. , Oh M. Matthew , Disterhoft John F.
Published: March 2013

Learning-related intrinsic excitability changes of pyramidal neurons via modulation of the postburst afterhyperpolarization (AHP) have been repeatedly demonstrated in multiple brain regions (especially the hippocampus), after a variety of learning tasks, and in multiple species. While exciting and important, the changes in pyramidal neurons are only a part of the neural circuitry involved in successful learning. For a more complete picture of the dynamic learning-related changes in the neural network, changes in inhibitory circuitry must also be systematically examined and characterized. Here we show in young adult rats and mice that learning the hippocampus-dependent trace eyeblink conditioning task induces enhanced inhibition onto CA1 pyramidal neurons mediated, in part, by an increase in intrinsic excitability of somatostatin-positive inhibitory neurons (SOMs). Furthermore, both CA1 pyramidal and SOM interneurons shared a common cellular mechanism (reduction in SK channel-mediated AHP) that led to the learning-induced increased intrinsic excitability.
A Computational Framework for Understanding Decision Making through Integration of Basic Learning Rules
Authors: Bazhenov Maxim , Huerta Ramon , Smith Brian H.
Published: March 2013

Nonassociative and associative learning rules simultaneously modify neural circuits. However, it remains unclear how these forms of plasticity interact to produce conditioned responses. Here we integrate nonassociative and associative conditioning within a uniform model of olfactory learning in the honeybee. Honeybees show a fairly abrupt increase in response after a number of conditioning trials. The occurrence of this abrupt change takes many more trials after exposure to nonassociative trials than just using associative conditioning. We found that the interaction of unsupervised and supervised learning rules is critical for explaining latent inhibition phenomenon. Associative conditioning combined with the mutual inhibition between the output neurons produces an abrupt increase in performance despite smooth changes of the synaptic weights. The results show that an integrated set of learning rules implemented using fan-out connectivities together with neural inhibition can explain the broad range of experimental data on learning behaviors.
Conditional Disruption of Calpain in the CNS Alters Dendrite Morphology, Impairs LTP, and Promotes Neuronal Survival following Injury
Authors: Amini Mandana , Ma Chun-lei , Farazifard Rasoul , Zhu Guoqi , Zhang Yi , Vanderluit Jacqueline , Zoltewicz Joanna Susie , Hage Fadi , Savitt Joseph M. , Lagace Diane C. , Slack Ruth S. , Beique Jean-Claude , Baudry Michel , Greer Peter A. , Bergeron Richard , Park David S.
Published: March 2013

Ubiquitous classical (typical) calpains, calpain-1 and calpain-2, are Ca+2-dependent cysteine proteases, which have been associated with numerous physiological and pathological cellular functions. However, a clear understanding of the role of calpains in the CNS has been hampered by the lack of appropriate deletion paradigms in the brain. In this study, we describe a unique model of conditional deletion of both calpain-1 and calpain-2 activities in mouse brain, which more definitively assesses the role of these ubiquitous proteases in brain development/function and pathology. Surprisingly, we show that these calpains are not critical for gross CNS development. However, calpain-1/calpain-2 loss leads to reduced dendritic branching complexity and spine density deficits associated with major deterioration in hippocampal long-term potentiation and spatial memory. Moreover, calpain-1/calpain-2-deficient neurons were significantly resistant to injury induced by excitotoxic stress or mitochondrial toxicity. Examination of downstream target showed that the conversion of the Cdk5 activator, p35, to pathogenic p25 form, occurred only in the presence of calpain and that it played a major role in calpain-mediated neuronal death. These findings unequivocally establish two central roles of calpain-1/calpain-2 in CNS function in plasticity and neuronal death.
ACR-12 Ionotropic Acetylcholine Receptor Complexes Regulate Inhibitory Motor Neuron Activity inCaenorhabditis elegans
Authors: Petrash Hilary A. , Philbrook Alison , Haburcak Marian , Barbagallo Belinda , Francis Michael M.
Published: March 2013

Heterogeneity in the composition of neurotransmitter receptors is thought to provide functional diversity that may be important in patterning neural activity and shaping behavior (Dani and Bertrand, 2007; Sassoè-Pognetto, 2011). However, this idea has remained difficult to evaluate directly because of the complexity of neuronal connectivity patterns and uncertainty about the molecular composition of specific receptor typesin vivo. Here we dissect how molecular diversity across receptor types contributes to the coordinated activity of excitatory and inhibitory motor neurons in the nematodeCaenorhabditis elegans. We show that excitatory and inhibitory motor neurons express distinct populations of ionotropic acetylcholine receptors (iAChRs) requiring the ACR-12 subunit. The activity level of excitatory motor neurons is influenced through activation of nonsynaptic iAChRs (Jospin et al., 2009; Barbagallo et al., 2010). In contrast, synaptic coupling of excitatory and inhibitory motor neurons is achieved through a second population of iAChRs specifically localized at postsynaptic sites on inhibitory motor neurons. Loss of ACR-12 iAChRs from inhibitory motor neurons leads to reduced synaptic drive, decreased inhibitory neuromuscular signaling, and variability in the sinusoidal motor pattern. Our results provide new insights into mechanisms that establish appropriately balanced excitation and inhibition in the generation of a rhythmic motor behavior and reveal functionally diverse roles for iAChR-mediated signaling in this process.
Oscillatory Entrainment of Primary Somatosensory Cortex Encodes Visual Control of Tactile Processing
Authors: Sieben Kay , Röder Brigitte , Hanganu-Opatz Ileana L.
Published: March 2013

Optimal behavior relies on the successful integration of complementary information from multiple senses. The neural mechanisms underlying multisensory interactions are still poorly understood. Here, we demonstrate the critical role of neural network oscillations and direct connectivity between primary sensory cortices in visual-somatosensory interactions. Extracellular recordings from all layers of the barrel field in Brown Norway ratsin vivoshowed that bimodal stimulation (simultaneous light flash and whisker deflection) augmented the somatosensory-evoked response and changed the power of induced network oscillations by resetting their phase. Anatomical tracing revealed sparse direct connectivity between primary visual (V1) and somatosensory (S1) cortices. Pharmacological silencing of V1 diminished but did not abolish cross-modal effects on S1 oscillatory activity, while leaving the early enhancement of the evoked response unaffected. Thus, visual stimuli seem to impact tactile processing by modulating network oscillations in S1 via corticocortical projections and subcortical feedforward interactions.
Dissociable Networks Control Conflict during Perception and Response Selection: A Transcranial Magnetic Stimulation Study
Authors: Soutschek Alexander , Taylor Paul C.J. , Müller Hermann J. , Schubert Torsten
Published: March 2013

Current models of conflict processing propose that cognitive control resolves conflict in the flanker task by enhancing task-relevant stimulus processing at a perceptual level. However, because conflicts occur at both a perceptual and a response selection level in that task, we tested the hypothesis of conflict-specific control networks for perceptual and response selection conflicts using transcranial magnetic stimulation (TMS). TMS of the presupplementary motor area selectively disrupted the processing of response selection conflict, whereas TMS of the posterior intraparietal sulcus/inferior parietal lobule interfered with perceptual conflict processing. In more detail, the presupplementary motor area seems to resolve response selection conflict mainly when no conflicts have occurred in the previous trial. In contrast, the posterior intraparietal sulcus/inferior parietal lobule may resolve perceptual conflicts selectively when a conflict has occurred in the previous trial. The current data show the need for revising models of cognitive control by providing evidence for the existence of conflict-specific control networks resolving conflict at different processing levels.
Efferent Feedback Minimizes Cochlear Neuropathy from Moderate Noise Exposure
Authors: Maison Stéphane F. , Usubuchi Hajime , Liberman M. Charles
Published: March 2013

Although protective effects of the cochlea's efferent feedback pathways have been well documented, prior work has focused on hair cell damage and cochlear threshold elevation and, correspondingly, on the high sound pressure levels (>100 dB SPL) necessary to produce them. Here we explore the noise-induced loss of cochlear neurons that occurs with lower-intensity exposures and in the absence of permanent threshold shifts. Using confocal microscopy to count synapses between hair cells and cochlear nerve fibers, and using measurement of auditory brainstem responses and otoacoustic emissions to assess cochlear presynaptic and postsynaptic function, we compare the damage from a weeklong exposure to moderate-level noise (84 dB SPL) in mice with varying degrees of cochlear de-efferentation induced by surgical lesion to the olivocochlear pathway. Such exposure causes minimal acute threshold shifts and no chronic shifts in mice with normal efferent feedback. In de-efferented animals, there was up to 40% loss of cochlear nerve synapses and a corresponding decline in the amplitude of the auditory brainstem response. Quantitative analysis of the de-efferentation in inner versus outer hair cell areas suggested that outer hair cell efferents are the most important in minimizing this neuropathy, presumably by virtue of their sound-evoked feedback reduction of cochlear amplification. The moderate nature of this acoustic overexposure suggests that cochlear neurons are at risk even in everyday acoustic environments, so the need for cochlear protection is plausible as a driving force in the design of this feedback pathway.
Engineered Deafness Reveals That Mouse Courtship Vocalizations Do Not Require Auditory Experience
Authors: Mahrt Elena J. , Perkel David J. , Tong Ling , Rubel Edwin W , Portfors Christine V.
Published: March 2013

Auditory experience during development is necessary for normal language acquisition in humans. Although songbirds, some cetaceans, and maybe bats may also be vocal learners, vocal learning has yet to be well established for a laboratory mammal. Mice are potentially an excellent model organism for studying mechanisms underlying vocal communication. Mice vocalize in different social contexts, yet whether they learn their vocalizations remains unresolved. To address this question, we compared ultrasonic courtship vocalizations emitted by chronically deaf and normal hearing adult male mice. We deafened CBA/CaJ male mice, engineered to express diphtheria toxin (DT) receptors in hair cells, by systemic injection of DT at postnatal day 2 (P2). By P9, almost all inner hair cells were absent and by P16 all inner and outer hair cells were absent inDTRmice. These mice did not show any auditory brainstem responses as adults. Wild-type littermates, also treated with DT at P2, had normal hair cells and normal auditory brainstem responses. We compared the temporal structure of vocalization bouts, the types of vocalizations, the patterns of syllables, and the acoustic features of each syllable type emitted by hearing and deaf males in the presence of a female. We found that almost all of the vocalization features we examined were similar in hearing and deaf animals. These findings indicate that mice do not need auditory experience during development to produce normal ultrasonic vocalizations in adulthood. We conclude that mouse courtship vocalizations are not acquired through auditory feedback-dependent learning.
Adaptive Temporal Encoding Leads to a Background-Insensitive Cortical Representation of Speech
Authors: Ding Nai , Simon Jonathan Z.
Published: March 2013

Speech recognition is remarkably robust to the listening background, even when the energy of background sounds strongly overlaps with that of speech. How the brain transforms the corrupted acoustic signal into a reliable neural representation suitable for speech recognition, however, remains elusive. Here, we hypothesize that this transformation is performed at the level of auditory cortex through adaptive neural encoding, and we test the hypothesis by recording, using MEG, the neural responses of human subjects listening to a narrated story. Spectrally matched stationary noise, which has maximal acoustic overlap with the speech, is mixed in at various intensity levels. Despite the severe acoustic interference caused by this noise, it is here demonstrated that low-frequency auditory cortical activity is reliably synchronized to the slow temporal modulations of speech, even when the noise is twice as strong as the speech. Such a reliable neural representation is maintained by intensity contrast gain control and by adaptive processing of temporal modulations at different time scales, corresponding to the neural δ and θ bands. Critically, the precision of this neural synchronization predicts how well a listener can recognize speech in noise, indicating that the precision of the auditory cortical representation limits the performance of speech recognition in noise. Together, these results suggest that, in a complex listening environment, auditory cortex can selectively encode a speech stream in a background insensitive manner, and this stable neural representation of speech provides a plausible basis for background-invariant recognition of speech.
Central Dopamine D2 Receptors Regulate Growth-Hormone-Dependent Body Growth and Pheromone Signaling to Conspecific Males
Authors: Noaín Daniela , Pérez-Millán M. Inés , Bello Estefanía P. , Luque Guillermina M. , Casas Cordero Rodrigo , Gelman Diego M. , Peper Marcela , Tornadu Isabel García , Low Malcolm J. , Becú-Villalobos Damasia , Rubinstein Marcelo
Published: March 2013

Competition between adult males for limited resources such as food and receptive females is shaped by the male pattern of pituitary growth hormone (GH) secretion that determines body size and the production of urinary pheromones involved in male-to-male aggression. In the brain, dopamine (DA) provides incentive salience to stimuli that predict the availability of food and sexual partners. Although the importance of the GH axis and central DA neurotransmission in social dominance and fitness is clearly appreciated, the two systems have always been studied unconnectedly. Here we conducted a cell-specific genetic dissection study in conditional mutant mice that selectively lack DA D2 receptors (D2R) from pituitary lactotropes (lacDrd2KO) or neurons (neuroDrd2KO). Whereas lacDrd2KO mice developed a normal GH axis, neuroDrd2KO mice displayed fewer somatotropes; reduced hypothalamicGhrhexpression, pituitary GH content, and serum IGF-I levels; and exhibited reduced body size and weight. As a consequence of a GH axis deficit, neuroDrd2KO adult males excreted low levels of major urinary proteins and their urine failed to promote aggression and territorial behavior in control male challengers, in contrast to the urine taken from control adult males. These findings reveal that central D2Rs mediate a neuroendocrine-exocrine cascade that controls the maturation of the GH axis and downstream signals that are critical for fitness, social dominance, and competition between adult males.
Novel GABAergic Circuits Mediating Excitation/Inhibition of Cajal-Retzius Cells in the Developing Hippocampus
Authors: Quattrocolo Giulia , Maccaferri Gianmaria
Published: March 2013

Cajal-Retzius cells are a class of neurons believed to play critical roles during cortical development. However, their network computational functions remain poorly understood. Although work in the neocortex and hippocampus has shown that Cajal-Retzius cells receive predominantly, if not exclusively, spontaneous GABAAreceptor-mediated input, the cellular sources originating these events remain unclear. However, a precise definition of the presynaptic GABAergic interneurons contacting Cajal-Retzius cells is important to understand the microcircuits and network patterns controlling their activation. Here, we have taken advantage of electrophysiological and anatomical techniques applied to mouse hippocampal slicesin vitroto directly address this question. Our paired recording experiments indicate that Cajal-Retzius cells receive small-amplitude, kinetically slow synaptic input from stratum lacunosum-moleculare interneurons, anatomically identified as neurogliaform cells. In addition, a convergence of optogenetic, electrophysiological, and pharmacological experiments shows that Cajal-Retzius cells receive GABAergic input from oriens lacunosum-moleculare cells and that this input has different physiological properties (i.e., larger amplitude and faster kinetics) from the one provided by neurogliaform cells. Last, we show that GABAergic evoked synaptic input onto Cajal-Retzius cells may either increase their excitability and trigger action potentials or inhibit spontaneous firing by depolarization block. We propose that the specific type of response depends on both the membrane potential of Cajal-Retzius cells and the kinetics of the received GABAergic input. In conclusion, we have unraveled a novel hippocampal microcircuit with complex GABAergic synaptic signaling, which we suggest may play a role in the refinement of the hippocampal network and connections during development.
A bi-faceted role of estrogen receptor β in breast cancer
Authors: Leygue Etienne , Murphy Leigh C
Published: March 2013

Despite over 15 years of research, the exact role, if any, played by estrogen receptor β (ERβ) in human breast cancer remains elusive. A large body of data bothin vitroandin vivosupports its role as an antiproliferative, pro-apoptotic factor especially when co-expressed with ERα. However, there is a smaller body of data associating ERβ with growth and survival in breast cancer. In clinical studies and most often in cell culture studies, the pro-growth and pro-survival activity of ERβ occurs in ERα-negative breast cancer tissue and cells. This bi-faceted role of ERβ is discussed in this review.
TOP2A is overexpressed and is a therapeutic target for adrenocortical carcinoma
Authors: Jain Meenu , Zhang Lisa , He Mei , Zhang Ya-Qin , Shen Min , Kebebew Electron
Published: March 2013

Adrenocortical carcinoma (ACC) is a rare but aggressive malignancy with no effective therapy for patients with unresectable disease. The aim of the current study was i) to evaluate TOP2A expression and function in human adrenocortical neoplasm and ACC cells and ii) to determine the anticancer activity of agents that target TOP2A. TOP2A mRNA and protein expression levels were evaluated in 112 adrenocortical tissue samples (21 normal adrenal cortex, 80 benign adrenocortical tumors, and 11 ACCs). In vitro siRNA knockdown of TOP2A in ACC cell lines (NCI-H295R and SW13) was used to determine its effect on cellular proliferation, cell cycle, anchorage-independent growth, and cellular invasion. We screened 14 TOP2A inhibitors for their anticancer activity in ACC cells. TOP2A mRNA and protein expression was significantly higher in ACC than in benign and normal adrenocortical tissue samples (P<0.05). Knockdown of TOP2A gene expression in ACC cell lines significantly decreased cell proliferation, anchorage-independent growth, and invasion (P<0.05). A screening assay in NCI-H295R cells showed that 11 of 14 TOP2A inhibitors had antiproliferative activity, 5 of the 14 TOP2A inhibitors had a higher antiproliferative activity than mitotane, and aclarubicin was the agent with the highest activity. Aclarubicin was validated to significantly decrease proliferation and tumor spheroid size in both NCI-H295R and SW13 ACC cell lines (P<0.05). Our results suggest that TOP2A is overexpressed in ACC, regulates cellular proliferation and invasion in ACC cells, and is an attractive target for ACC therapy. Of the TOP2A inhibitors screened, aclarubicin is a good candidate agent to test in future clinical trials for patients with locally advanced and metastatic ACC.
Changes in gonadal gene network by exogenous ligands in temperature-dependent sex determination
Authors: Matsumoto Yuiko , Yatsu Ryohei , Taylor Caitlin , Crews David
Published: March 2013

We examined the expression of candidate sex-determining genes in the red-eared slider turtle (Trachemys scripta) during the temperature-sensitive period (TSP). Aromatase and Rspo1 were used as markers of ovarian differentiation and Sox9 was used as a marker of testicular differentiation. Eggs were incubated at a male-producing temperature (26 °C or MPT) and a female-producing temperature (31 °C or FPT). First, eggs at the beginning of the TSP (stage 16) were topically treated with the steroid hormones 17β-estradiol (E2), testosterone in combination with aromatase inhibitor (AI+T), the E2 antagonist (ICI 182 780), and the androgen antagonist (flutamide). Secondly, gonads were removed at stage 16 and treated in vitro with E2, AI+T, or hormone antagonists. At the FPT, AI+T in ovo suppressed aromatase and Rspo1, while activating Sox9. At the MPT, E2 treatment rapidly increased aromatase and Rspo1, while suppressing Sox9. Treatment with the E2 antagonist in ovo decreased aromatase at the FPT. Treatment with the androgen antagonist in ovo increased aromatase and Rspo1 at early time points at MPT and decreased Sox9 at MPT at later developmental stages. Treatment of isolated gonads cultured in vitro with AI+T at FPT decreased aromatase and Rspo1 and E2 increased the expression of these genes at MPT. In vitro treatment with E2 antagonist suppressed aromatase and Rspo1 expression at FPT. Overall, our results suggest that exogenous ligands dictate gonadal development by redirecting the expression of candidate sex-determining genes within the genetic cascades induced by temperature.
Manejo de capim pé-de-galinha em lavouras de soja transgênica resistente ao glifosato
Authors: Ulguim André da Rosa , Vargas Leandro , Agostinetto Dirceu , Magro Taísa Dal , Westendorff Nixon da Rosa , Holz Marcelo Timm
Published: March 2013

O objetivo deste trabalho foi avaliar a resistência de capim pé-de-galinha (Eleusine indica) ao glifosato, em lavouras de soja transgênica; avaliar o efeito de aplicações de glifosato em diferentes estádios de desenvolvimento; identificar práticas agronômicas associadas à seleção de biótipos resistentes; e avaliar a eficiência dos herbicidas cletodim, fluazifope-P-butílico, clomazona, glufosinato de amônio e glifosato nas plantas resistentes. Plantas escapes ao tratamento com glifosato foram coletadas em 24 propriedades, no Rio Grande do Sul. As plantas foram cultivadas em casa de vegetação, tendo-se avaliado a sua resistência ao glifosato. Os acessos resistentes foram selecionados e avaliados quanto ao efeito da aplicação do glifosato em diferentes estádios de crescimento e quanto à sensibilidade aos herbicidas. Foi aplicado um questionário aos produtores para identificação das práticas agronômicas associadas às falhas no controle. O controle de E. indica pelo glifosato é mais efetivo com a aplicação em estádios iniciais de desenvolvimento. Práticas agronômicas, como uso contínuo de baixas doses do herbicida, aplicação em estádios de desenvolvimento avançados das plantas daninhas (mais de um afilho) e a ausência de rotação de culturas foram relacionadas às falhas de controle observadas. Os herbicidas cletodim, fluazifope-P-butílico e glufosinato de amônio são alternativas eficientes para o controle de E. indica.
Estaquia de mirtilo nas estações do ano com ácido indolbutírico e aquecimento do substrato
Authors: Marangon Marcos Aurélio , Biasi Luiz Antonio
Published: March 2013

O objetivo deste trabalho foi avaliar os efeitos da aplicação de concentrações do ácido indolbutírico (AIB) e do aquecimento do substrato sobre o enraizamento de estacas caulinares das cultivares de mirtilo Bluebelle, Bluegem e Powderblue, nas quatro estações do ano. Utilizou-se o delineamento experimental inteiramente casualizado, com arranjo fatorial 4x5x2 (estações x concentrações de AIB x com e sem aquecimento do substrato), com 4 repetições e 20 estacas como unidade experimental. Foram avaliadas as percentagens de estacas enraizadas, mortas, vivas e com calo, e o número e o comprimento médio de raízes. As maiores percentagens de enraizamento foram 57,1% na 'Bluegem', no verão, 30% na 'Bluebelle', na primavera, com aquecimento, e 63% na 'Powderblue', no verão, com aquecimento. O AIB na concentração de 2.000 mg L-1 aumentou o enraizamento de estacas das cultivares Bluegem e Powderblue. O aquecimento do substrato melhora o enraizamento das estacas coletadas no outono e no inverno, em todas as cultivares e, também, das estacas coletadas no verão e na primavera, na cultivar Bluebelle.
Condições meteorológicas e tipo de solo na composição da uva 'Cabernet Sauvignon'
Authors: Luciano Rodrigo Vieira , Albuquerque Jackson Adriano , Rufato Leo , Miquelluti David José , Warmling Maria Tereza
Published: March 2013

O objetivo deste trabalho foi avaliar os efeitos das condições meteorológicas e do tipo de solo sobre características físico-químicas e compostos fenólicos da uva 'Cabernet Sauvignon' (Vitis vinifera). O experimento foi realizado em vinhedo implantado em 2003, enxertado sobre o porta-enxerto 'Paulsen 1103' e conduzido no sistema espaldeira. No vinhedo, foram selecionados dois solos: Cambissolo Háplico e Cambissolo Húmico. O efeito das condições meteorológicas (precipitação e temperatura mínima e máxima do ar) foi avaliado nas safras 2008/2009, 2009/2010 e 2010/2011. Foram determinados os atributos físicos e químicos dos solos, os teores de sólidos solúveis, a acidez titulável e o pH do mosto, bem como o índice de polifenóis totais e dos teores de antocianinas e de taninos da uva. Os fatores solo e as condições meteorológicas (safras) foram arranjados em esquema fatorial 2x3. Com exceção do teor de polifenóis totais, as condições meteorológicas e o tipo de solo afetam as características físico-químicas da uva 'Cabernet Sauvignon', com efeito mais pronunciado das condições meteorológicas do que do tipo de solo. Menores precipitações e maiores amplitudes térmicas favorecem o acúmulo de sólidos solúveis na uva 'Cabernet Sauvignon'. Maiores precipitações favorecem o aumento da acidez do mosto.
Desempenho animal e características de pastos de capim-piatã submetidos a diferentes intensidades de pastejo
Authors: Nantes Nayana Nazareth , Euclides Valéria Pacheco Batista , Montagner Denise Baptaglin , Lempp Beatriz , Barbosa Rodrigo Amorim , Gois Phillippe Oliveira de
Published: March 2013

O objetivo deste trabalho foi avaliar o valor nutritivo, a estrutura do dossel e a produção animal de novilhos em pastos de capim-piatã (Urochloa brizantha, cultivar Piatã), manejados a 15, 30 e 45 cm de altura, sob lotação contínua. Utilizou-se o delineamento experimental de blocos ao acaso, com duas repetições e três alturas. As alturas dos pastos foram monitoradas duas vezes por semana, e as taxas de lotação ajustadas. Mensalmente, os pastos foram amostrados e os animais foram pesados. Não houve diferença no valor nutritivo dos pastos manejados com diferentes alturas. Os ganhos médios diários de 650 g por novilho foram semelhantes entre as diferentes alturas de manejo. A taxa de lotação foi menor para o pasto com 45 cm (2,4 UA ha-1), intermediária para o de 30 cm (3,1 UA ha-1) e maior para o manejado com 15 cm (3,8 UA ha-1), o que resultou em maior ganho por área dos pastos manejados com 15 cm (1.050 kg ha-1) e 30 cm (910 kg ha-1) de altura, quando comparados ao manejado a 45 cm (635 kg ha-1). O capim-piatã apresenta grande flexibilidade de manejo sob lotação contínua e pode ser manejado entre 15 e 45 cm de altura.
Complicações locais após a injeção de silicone líquido industrial: série de casos
Authors: Mello Daniel Francisco , Gonçalves Karen Chicol , Fraga Murilo F. , Perin Luis Fernando , Helene Jr Américo
Published: March 2013

OBJETIVO: analisar uma série de casos de pacientes submetidos à injeção de silicone líquido industrial de maneira clandestina e por pessoas não habilitadas. MÉTODOS: análise retrospectiva de prontuários de pacientes atendidos no período de setembro de 2003 a dezembro de 2010. Foram avaliados: sexo, idade, local e volume de silicone injetado, tempo decorrido entre a aplicação e as manifestações clínicas, complicações, tratamento e evolução. Definiu-se como precoce as manifestações ocorridas até 30 dias da injeção e manifestações tardias após este período. RESULTADOS: Foram atendidos 12 pacientes, oito eram do sexo masculino, sendo sete transexuais. O volume injetado variou de 5ml a 2000ml, sendo desconhecido em três casos. Os locais mais frequentemente utilizados para injeção foram a região de coxas e glúteos. Oito casos apresentaram manifestações precoces, com quadros de inflamação e/ou infecção. Foi necessária a realização de desbridamento cirúrgico em cinco casos. Três pacientes com histórico de injeção na região mamária foram submetidas à adenomastectomia. Houve um óbito por quadro de choque séptico refratário. CONCLUSÃO: O uso do silicone líquido industrial deve ser totalmente contraindicado como material de preenchimento e modificação do contorno corporal, podendo apresentar graves complicações e até mesmo óbito.
Risco climático da cana-de-açúcar cultivada na região nordeste do Brasil
Authors: Silva Vicente de P. R. da , Oliveira Sonaly D. de , Santos Carlos A. C. dos , Silva Madson T.
Published: March 2013

Este estudo avalia os impactos das alterações climáticas sobre o zoneamento agrícola de risco climático da cultura da cana-de-açúcar cultivada na região Nordeste do Brasil, baseado nos relatórios do IPCC. Combinado com técnicas de geoprocessamento (SIG) o modelo de balanço hídrico foi utilizado para identificar as áreas da região de estudo nas quais a cultura poderá sofrer restrições de rendimento devido às mudanças climáticas. Os dados utilizados no estudo foram as séries históricas de precipitação com no mínimo 30 anos de dados diários, coeficientes de cultura, evapotranspiração potencial e duração do ciclo da cultura. Adotou-se, como critério de corte para o Índice de Satisfação das Necessidades de Água para a cultura (ISNA) definido como a relação entre a evapotranspiração real e a evapotranspiração máxima (ETr/ETm) o valor 0,65. Os cenários utilizados nas simulações sem aumento na temperatura do ar e com aumento de 1,5; 3 e 5 ºC foram associados às alterações na precipitação de ±10, ±25 e ±40%. Os resultados indicam que existe uma diferença relevante entre os cenários de aquecimento e as condições climáticas atuais, em termos dos efeitos projetados da variação de temperatura sobre as áreas cultivadas com a cana-de-açúcar na região de estudo.
Períodos de interferência das plantas daninhas na cultura do girassol em Rondônia
Authors: Alves Gibran da S. , Tartaglia Francilene de L. , Rosa Jhonatas C. , Lima Pamela C. de , Cardoso Gleibson D. , Beltrão Napoleão E. de M.
Published: March 2013

Objetivou-se, neste trabalho, determinar os períodos de interferência das plantas daninhas na cultura do girassol e seus efeitos sobre o diâmetro do capítulo, teor de óleo, rendimento de óleo e produtividade. Adotou-se o delineamento experimental de blocos ao acaso com três repetições. Os tratamentos foram distribuídos em esquema fatorial 2 x 2 x 5, sendo os fatores: cultivares (Embrapa 122 e Hélio 358), modalidade de competição (na presença e na ausência de plantas daninhas) e períodos de convivência ou controle das plantas daninhas da emergência aos 15, 30, 45, 60 e 110 dias. As variáveis mensuradas foram diâmetro de capítulo, teor de óleo, rendimento de óleo e produtividade. As plantas daninhas interferem negativamente no diâmetro do capítulo, produtividade e rendimento de óleo, mas o convívio com as mesmas aumentou o teor de óleo das sementes, além de reduzir em 76,83 e 92,68% a produtividade dos cultivares Embrapa 122 e Hélio 358, respectivamente. Admitindo-se uma perda de 10% na produtividade, o período anterior à interferência (PAI), o período total de prevenção a interferência (PTPI) e o período crítico de prevenção e interferência (PCPI) para a cultivar Embrapa 122 foram de 16; 37 e 21 dias, respectivamente. Para o híbrido Hélio 358 o PAI, o PTPI e o PCPI foram de 24; 43 e 19 dias, respectivamente.
Pressupostos epistemológicos que balizam a Situação de Estudo: algumas implicações ao processo de ensino e à formação docente
Authors: Sangiogo Fábio André , Halmenschlager Karine Raquiel , Hunsche Sandra , Maldaner Otavio Aloisio
Published: March 2013

Frente às propostas de ensino baseadas em temas que sinalizam reconfiguração curricular, objetiva-se identificar e apresentar pressupostos epistemológicos presentes na Situação de Estudo (SE), bem como destacar implicações destes no ensino e na formação docente. A pesquisa é de natureza qualitativa, desenvolvida mediante a análise de textos publicados que referenciam a SE, e de uma entrevista semiestruturada realizada com um professor idealizador da proposta. A análise dos materiais permite inferir que o principal referencial epistemológico da SE é o bachelardiano, e, no âmbito educacional, o vigotskiano. Contudo, assumir esses referenciais implica construir programas escolares que considerem aspectos do cotidiano do estudante para que, nas interações assimetricamente estabelecidas sobre o objeto em estudo, possa apropriar-se do conhecimento historicamente produzido. Para isso, sinaliza-se a necessidade de discussões de cunho epistemológico na formação docente, para além dos educacionais, para que se desenvolva um ensino mais coerente com as Ciências e significativo aos estudantes.
A ficção científica e o estranhamento cognitivo no ensino de ciências: estudos críticos e propostas de sala de aula
Authors: Piassi Luís Paulo
Published: March 2013

Este trabalho, partindo da apresentação de propostas de ensino de ciências com o uso da ficção científica e fundamentando-se em referenciais dos estudos literários críticos sobre o gênero, objetiva argumentar que sua maior contribuição para a educação científica não se situa nem na precisão científica, nem na qualidade didática e nem mesmo no potencial lúdico que esse tipo de narrativa desperta. Sem desconsiderar a importância desses aspectos, mostramos que o sentido de levar a ficção científica para as aulas de ciências está nos mecanismos de produção ficcional que, por características que lhe são próprias, envolve um modo especial de raciocinar sobre o mundo natural. Tais mecanismos baseiam-se em conjecturas que promovem o chamado estranhamento cognitivo capaz de promover, nos estudantes, a problematização que pode ser o ponto de partida para uma abordagem crítica, não apenas de conceitos e leis, mas, também, de suas implicações e motivações epistemológicas e socioculturais.
Como os livros didáticos de biologia abordam as diferentes formas de estimar a biodiversidade?
Authors: Cardoso-Silva Cláudio Benício , Oliveira Antonio Carlos de
Published: March 2013

O rápido avanço das pesquisas científicas tem possibilitado que novos conhecimentos sejam assimilados, e que antigas teorias e hipóteses reformuladas. É inquestionável a importância dos livros didáticos enquanto objeto pedagógico na formação do cidadão. Por conta disso, torna-se imprescindível que estes sejam constantemente reavaliados, no que tange a seu conteúdo. No presente estudo, foram avaliadas as diferentes formas pelas quais os livros didáticos de Biologia abordam o tema biodiversidade. Para realizar esta pesquisa, foram utilizados livros didáticos, os quais fazem parte do catálogo do Programa Nacional do Livro do Ensino Médio (PNLEM). Observamos que alguns tópicos relacionados ao estudo da biodiversidade são apresentados de maneira superficial e, por vezes, equivocada. Também ficou evidente que os livros didáticos analisados neste estudo tratam de um mesmo assunto com abordagem e profundidade diferentes. Isto sugere que adoção de um único livro didático nas escolas pode comprometer o processo de aprendizado do aluno.
Representações sociais de meio ambiente: subsídios para a formação continuada de professores
Authors: Magalhães Júnior Carlos Alberto de Oliveira , Tomanik Eduardo Augusto
Published: March 2013

A formação de educadores ambientais deve envolver, sempre que possível, processos contínuos de estudo, atualização e a valorização dos conhecimentos dos próprios educadores. Partindo desses pressupostos, o objetivo deste trabalho foi investigar as Representações Sociais sobre o meio ambiente compartilhadas pelos professores das séries iniciais da Educação Básica da cidade de Porto Rico, Estado do Paraná, Brasil, para indicar caminhos para a formação continuada desses profissionais como Educadores Ambientais. Utilizamos a técnica de evocação de palavras para identificar os possíveis elementos que compõem as representações sociais, além de entrevistas. Identificamos que tais representações são caracterizadas por uma visão naturalista de meio ambiente e que os professores possuem conhecimentos limitados sobre o ambiente local. Esses elementos indicam a conveniência da oferta de cursos voltados para a transmissão e discussão de informações sobre o ambiente regional e para a compreensão de que os professores são, também, parte deste ambiente.