Action without awareness: reaching to an object you do not remember seeing

Background

Previous work by our group has shown that the scaling of reach trajectories to target size is independent of obligatory awareness of that target property and that “action without awareness” can persist for up to 2000 ms of visual delay. In the present investigation we sought to determine if the ability to scale reaching trajectories to target size following a delay is related to the pre-computing of movement parameters during initial stimulus presentation or the maintenance of a sensory (i.e., visual) representation for on-demand response parameterization.

Methodology/Principal Findings

Participants completed immediate or delayed (i.e., 2000 ms) perceptual reports and reaching responses to different sized targets under non-masked and masked target conditions. For the reaching task, the limb associated with a trial (i.e., left or right) was not specified until the time of response cuing: a manipulation that prevented participants from pre-computing the effector-related parameters of their response. In terms of the immediate and delayed perceptual tasks, target size was accurately reported during non-masked trials; however, for masked trials only a chance level of accuracy was observed. For the immediate and delayed reaching tasks, movement time as well as other temporal kinematic measures (e.g., times to peak acceleration, velocity and deceleration) increased in relation to decreasing target size across non-masked and masked trials.

Conclusions/Significance

Our results demonstrate that speed-accuracy relations were observed regardless of whether participants were aware (i.e., non-masked trials) or unaware (i.e., masked trials) of target size. Moreover, the equivalent scaling of immediate and delayed reaches during masked trials indicates that a persistent sensory-based representation supports the unconscious and metrical scaling of memory-guided reaching.     

Resveratrol induces catalytic bioscavenger paraoxonase 1 expression and protects against chemical warfare nerve agent toxicity in human cell lines

Current advances in enzyme bioscavenger prophylactic therapy against chemical warfare nerve agent (CWNA) exposure are moving towards the identification of catalytic bioscavengers that can degrade large doses of organophosphate (OP) nerve agents without self destruction. This is a preferred method compared to therapy with the purified stoichiometric bioscavenger, butyrylcholinesterase, which binds OPs 1:1 and would thus require larger doses for treatment. Paraoxonase-1 (PON-1) is one such catalytic bioscavenger that has been shown to hydrolyze OP insecticides and contribute to detoxification in animals and humans. Here we investigated the effects of a common red wine ingredient, Resveratrol (RSV), to induce the expression of PON-1 in the human hepatic cell line HC04 and evaluated the protection against CWNA simulants. Dose-response curves showed that a concentration of 20 microM RSV was optimal in inducing PON-1 expression in HC04 cells. RSV at 20 microM increased the extracellular PON-1 activity approximately 150% without significantly affecting the cells. Higher doses of RSV were cytotoxic to the cells. Resveratrol also induced PON-1 in the human lung cell line A549. RSV pre-treatment significantly (P = 0.05) protected the hepatic cells against exposure to 2x LD(50) of soman and sarin simulants. However, lung cells were protected against soman simulant exposure but not against sarin simulant exposure following RSV treatment. In conclusion, these studies indicate that dietary inducers, such as RSV, can up-regulate PON-1, a catalytic bioscavenger, which can then hydrolyze and protect against CWNA-induced toxicity, providing a prospective new method to protect against CWNA exposure.     

Serotonin-GABA interactions modulate MDMA-induced mesolimbic dopamine release

3,4,-Methylenedioxymethamphetamine (MDMA; 'ecstasy') acts at monoamine nerve terminals to alter the release and re-uptake of dopamine and 5-HT. The present study used microdialysis in awake rats to measure MDMA-induced changes in extracellular GABA in the ventral tegmental area (VTA), simultaneous with measures of extracellular dopamine (DA) in the nucleus accumbens (NAC) shell. (+)-MDMA (0, 2.5, 5 and 10 mg/kg, i.p.) increased GABA efflux in the VTA with a bell-shaped dose-response. This increase was blocked by application of TTX through the VTA probe. MDMA (5 mg/kg) increased 5-HT efflux in VTA by 1037% (p < 0.05). The local perfusion of the 5-HT(2B/2C) antagonist SB 206553 into the VTA reduced VTA GABA efflux after MDMA from a maximum of 229% to a maximum of 126% of basal values (p < 0.05), while having no effect on basal extracellular GABA concentrations. DA concentrations measured simultaneously in the NAC shell were increased from a maximum of 486% to 1320% (p < 0.05). The selective DA releaser d-amphetamine (AMPH) (4 mg/kg) also increased VTA GABA efflux (180%), did not alter 5-HT and increased NAC DA (875%) (p < 0.05), but the perfusion of SB 206553 into the VTA failed to alter these effects. These results suggest that MDMA-mediated increases in DA within the NAC shell are dampened by increases in VTA GABA subsequent to activation of 5-HT(2B/2C) receptors in the VTA.     

p62, Ref(2)P and ubiquitinated proteins are conserved markers of neuronal aging, aggregate formation and progressive autophagic defects

Suppression of macroautophagy, due to mutations or through processes linked to aging, results in the accumulation of cytoplasmic substrates that are normally eliminated by the pathway. This is a significant problem in long-lived cells like neurons, where pathway defects can result in the accumulation of aggregates containing ubiquitinated proteins. The p62/Ref(2)P family of proteins is involved in the autophagic clearance of cytoplasmic protein bodies or sequestosomes. These unique structures are closely associated with protein inclusions containing ubiquitin as well as key components of the autophagy pathway. In this study we show that detergent fractionation followed by western blot analysis of insoluble ubiquitinated proteins (IUP), mammalian p62 and its Drosophila homologue, Ref(2)P can be used to quantitatively assess the activity level of aggregate clearance (aggrephagy) in complex tissues. Using this technique we show that genetic or age-dependent changes that modify the long-term enhancement or suppression of aggrephagy can be identified. Moreover, using the Drosophila model system this method can be used to establish autophagy-dependent protein clearance profiles that are occurring under a wide range of physiological conditions including developmental, fasting and altered metabolic pathways. This technique can also be used to examine proteopathies that are associated with human disorders such as frontotemporal dementia, Huntington and Alzheimer disease. Our findings indicate that measuring IUP profiles together with an assessment of p62/Ref(2)P proteins can be used as a screening or diagnostic tool to characterize genetic and age-dependent factors that alter the long-term function of autophagy and the clearance of protein aggregates occurring within complex tissues and cells.     

Isolation of endophytic endospore-forming bacteria from Theobroma cacao as potential biological control agents of cacao diseases

Sixty-nine endospore-forming bacterial endophytes consisting of 15 different species from five genera were isolated from leaves, pods, branches, and flower cushions of Theobroma cacao as potential biological control agents. Sixteen isolates had in vitro chitinase production. In antagonism studies against cacao pathogens, 42% inhibited Moniliophthora roreri, 33% inhibited Moniliophthora perniciosa, and 49% inhibited Phytophthora capsici. Twenty-five percent of isolates inhibited the growth of both Moniliophthora spp., while 22% of isolates inhibited the growth of all three pathogens. Isolates that were chitinolytic and tested negative on Bacillus cereus agar were tested with in planta studies. All 14 isolates colonized the phyllosphere and internal leaf tissue when introduced with Silwet L-77, regardless of the tissue of origin of the isolate. Eight isolates significantly inhibited P. capsici lesion formation (p = 0.05) in detached leaf assays when compared to untreated control leaves. ARISA with bacilli specific primers amplified 21 OTUs in field grown cacao leaves, while eubacteria specific primers amplified 58 OTUs. ARISA analysis of treated leaves demonstrated that inundative application of a single bacterial species did not cause a long-term shift of native bacterial communities. This research illustrates the presence of endospore-forming bacterial endophytes in cacao trees, their potential as antagonists of cacao pathogens, and that cacao harbors a range of bacterial endophytes.     

Epitope-specific human influenza antibody repertoires diversify by B cell intraclonal sequence divergence and interclonal convergence

We generated from a single blood sample five independent human mAbs that recognized the Sa antigenic site on the head of influenza hemagglutinin and exhibited inhibitory activity against a broad panel of H1N1 strains. All five Abs used the V(H)3-7 and J(H)6 gene segments, but at least four independent clones were identified by junctional analysis. High-throughput sequence analysis of circulating B cells revealed that each of the independent clones were members of complex phylogenetic lineages that had diversified widely using a pattern of progressive diversification through somatic mutation. Unexpectedly, B cells encoding multiple diverging lineages of these clones, including many containing very few mutations in the Ab genes, persisted in the circulation. Conversely, we noted frequent instances of amino acid sequence convergence in the Ag combining sites exhibited by members of independent clones, suggesting a strong selection for optimal binding sites. We suggest that maintenance in circulation of a wide diversity of somatic variants of dominant clones may facilitate recognition of drift variant virus epitopes that occur in rapidly mutating virus Ags, such as influenza hemagglutinin. In fact, these Ab clones recognize an epitope that acquired three glycosylation sites mediating escape from previously isolated human Abs.     

An invasive plant and climate change threat index for weed risk management: Integrating habitat distribution pattern and dispersal process

Invasive plants pose a significant threat to the integrity and biodiversity of native systems. Weed risk assessment and management provides a framework for assessing this threat. However, relatively little attention has been paid to the threat posed to biodiversity by invasive plants in a rapidly changing climate. This paper aims to estimate the impacts of climate change on exotic plant habitats, and incorporates elements of dispersal to develop a management index for identifying invasive plant threat under climate change. The spatial distribution of habitat suitability is modelled at the landscape scale for multiple exotic plant species under current climate and a climate change scenario for the year 2030. Expert opinion of the dominant dispersal mechanisms and weed status is used to model relative dispersal threat of each exotic plant species. These pattern and process outputs are integrated to create a multi-species management priority layer in an effort to synthesise the inherently complex outputs from multiple models of multiple species. The overall multi-species management index thus combines pattern and process to identify geographic locations at greatest threat from invasion under climate change.     

Coordinated functions of WSS1, PSY2 and TOF1 in the DNA damage response

The stabilization and processing of stalled replication forks is required to maintain genome integrity in all organisms. In an effort to identify novel proteins that might be involved in stabilizing stalled replication forks, Saccharomyces cerevisiae mutant wss1Δ was isolated from a high-throughput screening of ~5000 deletion strains for genes involved in the response to continuous, low-intensity UV irradiation. Disruption of WSS1 resulted in synergistic increases in UV sensitivity with null mutants of genes involved in recombination (RAD52) and cell cycle control (RAD9 and RAD24). WSS1 was also found to interact genetically with SGS1, TOP3, SRS2 and CTF4, which are involved in recombination, repair of replication forks and the establishment of sister chromatid cohesion. A yeast two-hybrid screen identified a potential physical interaction between Wss1 and both Psy2 and Tof1. Genetic interactions were also detected between PSY2 and TOF1, as well as between each gene and RAD52 and SRS2, and between WSS1 and TOF1. Tof1 is known to be involved in stabilizing stalled replication forks and our data suggest that Wss1 and Psy2 similarly function to stabilize or process stalled or collapsed replication forks.     

Inability of Pseudomonas stutzeri denitrification mutants with the phenotype of Pseudomonas aeruginosa to grow in nitrous oxide.

Pseudomonas aeruginosa PAO1 reduced nitrous oxide to dinitrogen but did not grow anaerobically in nitrous oxide. Two transposon insertion Nos- mutants of Pseudomonas stutzeri exhibited the P. aeruginosa phenotype. Growth yield studies demonstrated that nitrous oxide produced in vivo was productively respired, but nitrous oxide supplied exogenously was not. The defect may be in electron transport or in nitrous oxide uptake.