Temporal Anticipation Based on Memory.

The fundamental role that our long-term memories play in guiding perception is increasingly recognized, but the functional and neural mechanisms are just beginning to be explored. Although experimental approaches are being developed to investigate the influence of long-term memories on perception, these remain mostly static and neglect their temporal and dynamic nature. Here, we show that our long-term memories can guide attention proactively and dynamically based on learned temporal associations. Across two experiments, we found that detection and discrimination of targets appearing within previously learned contexts are enhanced when the timing of target appearance matches the learned temporal contingency. Neural markers of temporal preparation revealed that the learned temporal associations trigger specific temporal predictions. Our findings emphasize the ecological role that memories play in predicting and preparing perception of anticipated events, calling for revision of the usual conceptualization of contextual associative memory as a reflective and retroactive function.

Visual Causality Judgments Correlate with the Phase of Alpha Oscillations.

The detection of causality is essential for our understanding of whether distinct events relate. A central requirement for the sensation of causality is temporal contiguity: As the interval between events increases, causality ratings decrease; for intervals longer than approximately 100 msec, the events start to appear independent. It has been suggested that this effect might be due to perception relying on discrete processing. According to this view, two events may be judged as sequential or simultaneous depending on their temporal relationship within a discrete neuronal process. To assess if alpha oscillations underlie this discrete neuronal process, we investigated how these oscillations modulate the judgment of causality. We used the classic launching effect with concurrent recording of EEG signal. In each trial, a disk moved horizontally toward a second disk at the center of the screen and stopped when they touched each other. After a delay that varied between 0 and 400 msec after contact, the right disk began to move. Participants were instructed to judge whether or not they had a feeling that the first disk caused the movement of the second disk. We found that frontocentral alpha phase significantly biased causality estimates. Moreover, we found that alpha phase was concentrated around different angles for trials in which participants judged events as causally related versus not causally related. We conclude that alpha phase plays a key role in biasing causality judgments.

Nuclear receptor superfamily structural diversity in pacific oyster: In silico identification of estradiol binding candidates.

The increasing presence of anthropogenic contaminants in aquatic environments poses challenges for species inhabiting contaminated sites. Due to their structural binding characteristics to ligands that inhibit or activate gene transcription, these xenobiotic compounds frequently target the nuclear receptor superfamily. The present work aims to understand the potential interaction between the hormone 17-ß-estradiol, an environmental contaminant, and the nuclear receptors of Crassostrea gigas, the Pacific oyster. This filter-feeding, sessile oyster species is subject to environmental changes and exposure to contaminants. In the Pacific oyster, the estrogen-binding nuclear receptor is not able to bind this hormone as it does in vertebrates. However, another receptor may exhibit responsiveness to estrogen-like molecules and derivatives. We employed high-performance in silico methodologies, including three-dimensional modeling, molecular docking and atomistic molecular dynamics to identify likely binding candidates with the target moecule. Our approach revealed that among the C. gigas nuclear receptor superfamily, candidates with the most favorable interaction with the molecule of interest belonged to the NR1D, NR1H, NR1P, NR2E, NHR42, and NR0B groups. Interestingly, NR1H and NR0B were associated with planktonic/larval life cycle stages, while NR1P, NR2E, and NR0B were associated with sessile/adult life stages. The application of this computational methodological strategy demonstrated high performance in the virtual screening of candidates for binding with the target xenobiotic molecule and can be employed in other studies in the field of ecotoxicology in non-model organisms.

Characterization of a fatty acid-binding protein from the Pacific oyster (Crassostrea gigas): pharmaceutical and toxicological implications.

Pharmaceuticals and their metabolites constitute a class of xenobiotics commonly found in aquatic environments which may cause toxic effects in aquatic organisms. Several different lipophilic molecules, including some pharmaceuticals, can bind to fatty acid-binding proteins (FABPs), a group of evolutionarily related cytoplasmic proteins that belong to the intracellular lipid-binding protein (iLBP) family. An oyster FABP genome-wide investigation was not available until a recent study on gene organization, protein structure, and phylogeny of Crassostrea gigas iLBPs. Higher transcript levels of the C. gigas FABP2 gene were found after exposure to sewage and pharmaceuticals. Because of its relevance as a potential biomarker of aquatic contamination, in this study, recombinant FABP2 from C. gigas (CgFABP2) was successfully cloned, expressed, and purified, and in vitro and in silico assays were performed using lipids and pharmaceuticals. This is the first characterization of a protein from the iLBP family in C. gigas. Homology modeling and molecular docking were used to evaluate the binding affinities of natural ligands (palmitic, oleic, and arachidonic acids) and pharmaceuticals (ibuprofen, sodium diclofenac, and acetaminophen). Among the tested fatty acids, CgFABP2 showed preference for palmitic acid. The selected pharmaceuticals presented a biphasic-binding mode, suggesting a different binding affinity with a preference for diclofenac. Therefore, the approach using circular dichroism and in silico data might be useful for ligand-binding screening in an invertebrate model organism.

Probucol Protects Neuronal Cells Against Peroxide-Induced Damage and Directly Activates Glutathione Peroxidase-1.

Experimental evidence has shown that probucol, a hypocholesterolemic agent, is also able to increase glutathione peroxidase (GPx) activity. However, there is a lack of knowledge about the mechanism(s) involved in this event. In this study, in vitro experiments with purified GPx1 from bovine erythrocytes and cultured SH-SY5Y neuroblastoma cells, as well as in silico studies with GPx1, were performed in order to elucidate mechanisms mediating the stimulatory effect of probucol on GPx activity and to investigate the relevance of this event in terms of susceptibility against peroxide-induced cytotoxicity. In vitro experiments with purified GPx1 showed a direct stimulatory effect of probucol on the activity of GPx1, which was related to an increase in Vmax with no changes in KM. Probucol also increased GPx activity in cultured SH-SY5Y neuroblastoma cells, while the levels of GPx1 expression were not changed, corroborating the results found with the purified enzyme. In addition, probucol rendered SH-SY5Y cells more resistant to hydroperoxide-induced cytotoxicity, and this event was abolished in GPx1 knocked-down cells. In silico studies with GPx1 pointed to a potential binding site for probucol at the close vicinity of the GSH pocket. Collectively, the results presented herein indicate that GPx1 plays a central role in the probucol-induced protective effects against peroxide toxicity. This highlights a novel target (GPx1) and a new mechanism of action (direct activation) for an "old drug." The relevance of such results for in vivo conditions deserves further investigation.

Reverse T3 interacts with αvß3 integrin receptor and restores enzyme activities in the hippocampus of hypothyroid developing rats: Insight on signaling mechanisms.

In the present study we provide evidence that 3,3',5'-triiodothyronine (reverse T3, rT3) restores neurochemical parameters induced by congenital hypothyroidism in rat hippocampus. Congenital hypothyroidism was induced by adding 0.05% propylthiouracil in the drinking water from gestation day 8 and continually up to lactation day 15. In the in vivo rT3 exposure, hypothyroid 12-day old pups were daily injected with rT3 (50 ng/kg body weight) or saline until day 14. In the ex vivo rT3 treatment, hippocampal slices from 15-day-old hypothyroid pups were incubated for 30 min with or without rT3 (1 nM). We found that ex vivo and/or in vivo exposure to rT3 failed in restoring the decreased 14C-glutamate uptake; however, restored the phosphorylation of glial fibrillary acidic protein (GFAP), 45Ca2+ influx, aspartate transaminase (AST), glutamine synthetase (GS) and gamma-glutamate transferase (GGT) activities, as well as glutathione (GSH) levels in hypothyroid hippocampus. In addition, rT3 improved 14C-2-deoxy-D-glucose uptake and lactate dehydrogenase (LDH) activity. Receptor agonists/antagonists (RGD peptide and AP-5), kinase inhibitors of p38MAPK, ERK1/2, CaMKII, PKA (SB239063, PD98059, KN93 and H89, respectively), L-type voltage-dependent calcium channel blocker (nifedipine) and intracellular calcium chelator (BAPTA-AM) were used to determine the mechanisms of the nongenomic rT3 action on GGT activity. Using molecular docking analysis, we found rT3 interaction with αvß3 integrin receptors, nongenomically activating signaling pathways (PKA, CaMKII, p38MAPK) that restored GGT activity. We provide evidence that rT3 is an active TH metabolite and our results represent an important contribution to elucidate the nonclassical mechanism of action of this metabolite in hypothyroidism.

Experimentally-induced maternal hypothyroidism alters enzyme activities and the sensorimotor cortex of the offspring rats.

In this study, we used an experimental model of congenital hypothyroidism to show that deficient thyroid hormones (TH) disrupt different neurochemical, morphological and functional aspects in the cerebral cortex of 15-day-old offspring. Our results showing decreased glutamine synthetase (GS) activity and Ca2+ overload in the cerebral cortex of hypothyroid pups suggest misregulated glutamate metabolism associated with developmentally induced TH deficiency. The 14C-MeAIB accumulation indicates upregulated System A activity and glutamine uptake by neurons. Energy metabolism in hypothyroid cortical slices was preserved, as demonstrated by unaltered glucose metabolism. We also found upregulated acetylcholinesterase activity, depleting acetylcholine from the synaptic cleft, pointing to disrupted cholinergic system. Increased reactive oxygen species (ROS) generation, lipid peroxidation, glutathione (GSH) depletion, which were associated with glutathione peroxidase, superoxide dismutase and gamma-glutamyltransferase downregulation suggest redox imbalance. Disrupted astrocyte cytoskeleton was evidenced by downregulated and hyperphosphorylated glial fibrillary acidic protein (GFAP). Morphological and structural characterization of the sensorimotor cerebral cortex (SCC) showed unaltered thickness of the SCC. However, decreased size of neurons on the layers II & III and IV in the right SCC and increased NeuN positive neurons in specific SCC layers, suggest that they are differently affected by the low TH levels during neurodevelopment. Hypothyroid pups presented increased number of foot-faults in the gridwalk test indicating affected motor functions. Taken together, our results show that congenital hypothyroidism disrupts glutamatergic and cholinergic neurotransmission, Ca2+ equilibrium, redox balance, cytoskeleton integrity, morphological and functional aspects in the cerebral cortex of young rats.

The use of smoke acid as an alternative coagulating agent for natural rubber sheets' production.

A comparative study of rubber sheets obtained using formic, acetic, and smoke acid as coagulants is shown for latex obtained from native Amazonian trees and also from commercial cultivated trees. The evaluation of both processes of coagulation was carried out by spectroscopic and physical-chemical analysis, showing no differences in the rubber sheets obtained. This new method of rubber sheet preparation was introduced into Amazonian rainforest rubber tapper communities, which are actually producing in large scale. The physical-mechanical properties were similar among a large sheets made by different rubber tapper communities using this new method.

Polymerase Chain Reaction and blood culture for diagnosis of canine sepsis / Reação em Cadeia da Polimerase e hemocultura para diagnóstico de sepse canina

ABSTRACT: Sepsis is characterized by the presence of organ dysfunction secondary to the dysregulated systemic inflammatory response associated with an infection, and has high mortality rates. Traditional diagnostic techniques based on non-microbiological isolation are time-consuming and may delay treatment. Thus, this study aimed to compare bacterial and fungal broad-range polymerase chain reaction (PCR) and blood culture for diagnosis of sepsis in dogs. Blood samples from 88 dogs with suspected sepsis were analyzed by blood culture, and PCR to detect bacterial and fungal DNA. On blood culture, 20 (22.7%) samples tested positive for bacterial isolates; however, none tested positive for fungi. Through PCR analysis, bacterial DNA was detected in 46 (52.3%) animals, whereas fungal DNA was present in one (1.1%) sample. Our results showed that PCR-based testing has important diagnostic value for canine blood infections because it has a shorter turnaround time and higher sensitivity than traditional blood culture.

RESUMO: Sepse se caracteriza pela presença de disfunção orgânica secundária à resposta inflamatória sistêmica desregulada, associada a uma infecção com elevadas taxas de mortalidade. As técnicas tradicionais baseadas no isolamento microbiológico são demoradas e podem atrasar o tratamento. O objetivo deste estudo foi comparar a Reação em Cadeia da Polimerase (PCR) bacteriana e fúngica e hemocultura em cães com sepse. Foram analisadas 88 amostras de sangue de cães com suspeita de sepse por meio de hemocultura e PCR para detectar DNA bacteriano e fúngico. Nas culturas sanguíneas, 20 (22,7%) amostras foram positivas para isolados bacterianos. No entanto, nenhuma amostra foi positiva para fungos. Através da análise por PCR, o DNA bacteriano foi detectado em 46 animais (52,3%), enquanto que o DNA fúngico estava presente em uma amostra (1,1%). Neste caso, a PCR apresenta importante valor diagnóstico em cães com infeções sanguíneas devido a sua rapidez e maior sensibilidade do que a isolamento por hemocultura.

Composição florística de trepadeiras em florestas sazonais semidecíduais do sudeste do Brasil / Species composition of climbers in seasonal semideciduous forest fragments of Southeastern Brazil

In this study we evaluated floristic composition patterns of communities of climbers within ten inventories carried out in semideciduous forest fragments of southeastern Brazil. One of the inventories is original, being carried out for the present study in Ribeirão Cachoeira forest, Campinas, São Paulo State, Southeastern Brazil. This inventory was then pooled together to other nine climbers' inventories made in other forests of Southeastern Brazil to form a data base, which was examined regarding species richness, similarity, species distribution and climbing methods. The total number of species obtained was 355, belonging to 145 genera and 43 families. The ten most diverse families Bignoniaceae (45 species), Fabaceae (42), Malpighiaceae (36), Asteraceae (31), Apocynaceae (29), Sapindaceae (28), Convolvulaceae (21), Cucurbitaceae (14), Passifloraceae (10), and Euphorbiaceae (8) contributed to 74.4 percent of the total number of species recorded. The commonest climbing method in the studied sites was main stem or branch twining, accounting for 178 species or 50.1 percent of the total, the second commonest was tendril climbing (121 species, 34.1 percent), and the least, scrambling (56 species, 15.8 percent). We found a high percentage of exclusive species i.e., those occurring in only one forest site, which accounted for 49.3 percent of the total recorded. The mean similarity among forest sites (30 percent) may be considered low. The climbing species contribution to the total wood plant richness recorded on the forests sites was very high in some of the sites (up to 52.5 percent). These results indicated the importance of climber communities to plant diversity for semideciduous forests in Southeastern Brazil, enhancing the regional diversity and the conservation value of these forest remnants.

No presente estudo avaliamos as variações na composição de espécies das comunidades de trepadeiras abordando dez inventários florísticos realizados em fragmentos de floresta estacional semidecidual do sudeste do Brasil. Um destes inventários é inédito e foi realizado especialmente para o presente estudo. Comparamos este levantamento a outros nove inventários florísticos de trepadeiras realizados em outras florestas do sudeste para investigar aspectos como riqueza, similaridade, distribuição de espécies e mecanismos de escalada. Ao todo foram encontradas 355 espécies, pertencentes a 145 gêneros e 43 famílias. As dez famílias mais ricas Bignoniaceae (45 espécies), Fabaceae (42), Malpighiaceae (36), Asteraceae (31), Apocynaceae (29), Sapindaceae (28), Convolvulaceae (21), Cucurbitaceae (14), Passifloraceae (10), e Euphorbiaceae (8) representaram 74,4 por cento do total de espécies encontrado. Considerando os mecanismos de escalada, observamos o predomínio de espécies volúveis (178 espécies ou 50,1 por cento), sobre espécies com gavinhas (121 espécies, 34,1 por cento), e apoiadoras (56 espécies, 15,8 por cento). A porcentagem de espécies exclusivas, i.e. aquelas que ocorreram em apenas uma das localidades estudadas, foi de 49,3 por cento do total amostrado e pode ser considerada alta. Além disso, a similaridade entre as florestas analisadas foi bastante baixa e a contribuição das espécies de trepadeiras para a diversidade de plantas lenhosas nestas áreas foi bastante elevada em algumas áreas, chegando a 52,5 por cento. Estes resultados indicaram a importância das comunidades de trepadeiras para a diversidade vegetal nas florestas semideciduais do sudeste do Brasil, aumentando a valor de conservação desses remanescentes florestais.