Enhanced Stability and Emission Properties of Perylene Dyes by Surface Tethering: Preparation of Fluorescent Ru Nanoparticle Suspensions by Alkyne Linker Chemistry.

Spherical ruthenium nanoparticles (NPs) with a narrow size distribution were synthesised in ethanol by a facile low-temperature solvothermal process without the assistance of templates, structure-directing agents or post annealing/reduction treatments. Surface passivation with a fluorescent perylene dye (EP), and with silane ligands (ETMS), both initially bearing alkyne groups and subsequently forming vinylidene linkages, provided stable suspensions of the marginally soluble free EP. Quantitative analysis of the suspension gave an estimated EP surface coverage of 15 %, corresponding to an EP/ETMS mole ratio of ≈1:6. Photophysical evaluation of the bound and free dye revealed similar absorption bands and extinction coefficients and improved properties for the bound state, including enhanced fluorescence in the visible range for the bound dye, an extended absorption range into the near-UV providing strong emission in the visible, and significantly improved photostability. The physical basis of the enhanced photophysical properties, potential routes to further improvements and the implications for applications are discussed.

Evidence for Neural Computations of Temporal Coherence in an Auditory Scene and Their Enhancement during Active Listening.

The human brain has evolved to operate effectively in highly complex acoustic environments, segregating multiple sound sources into perceptually distinct auditory objects. A recent theory seeks to explain this ability by arguing that stream segregation occurs primarily due to the temporal coherence of the neural populations that encode the various features of an individual acoustic source. This theory has received support from both psychoacoustic and functional magnetic resonance imaging (fMRI) studies that use stimuli which model complex acoustic environments. Termed stochastic figure-ground (SFG) stimuli, they are composed of a "figure" and background that overlap in spectrotemporal space, such that the only way to segregate the figure is by computing the coherence of its frequency components over time. Here, we extend these psychoacoustic and fMRI findings by using the greater temporal resolution of electroencephalography to investigate the neural computation of temporal coherence. We present subjects with modified SFG stimuli wherein the temporal coherence of the figure is modulated stochastically over time, which allows us to use linear regression methods to extract a signature of the neural processing of this temporal coherence. We do this under both active and passive listening conditions. Our findings show an early effect of coherence during passive listening, lasting from ∼115 to 185 ms post-stimulus. When subjects are actively listening to the stimuli, these responses are larger and last longer, up to ∼265 ms. These findings provide evidence for early and preattentive neural computations of temporal coherence that are enhanced by active analysis of an auditory scene.

Unravelling the role of SNM1 in the DNA repair system of Trypanosoma brucei.

All living cells are subject to agents that promote DNA damage. A particularly lethal lesion are interstrand cross-links (ICL), a property exploited by several anti-cancer chemotherapies. In yeast and humans, an enzyme that plays a key role in repairing such damage are the PSO2/SNM1 nucleases. Here, we report that Trypanosoma brucei, the causative agent of African trypanosomiasis, possesses a bona fide member of this family (called TbSNM1) with expression of the parasite enzyme able to suppress the sensitivity yeast pso2Δ mutants display towards mechlorethamine, an ICL-inducing compound. By disrupting the Tbsnm1 gene, we demonstrate that TbSNM1 activity is non-essential to the medically relevant T. brucei life cycle stage. However, trypanosomes lacking this enzyme are more susceptible to bi- and tri-functional DNA alkylating agents with this phenotype readily complemented by ectopic expression of Tbsnm1. Genetically modified variants of the null mutant line were subsequently used to establish the anti-parasitic mechanism of action of nitrobenzylphosphoramide mustard and aziridinyl nitrobenzamide prodrugs, compounds previously shown to possess potent trypanocidal properties while exhibiting limited toxicity to mammalian cells. This established that these agents, following activation by a parasite specific type I nitroreductase, produce metabolites that promote formation of ICLs leading to inhibition of trypanosomal growth.

Attentional Selection in a Cocktail Party Environment Can Be Decoded from Single-Trial EEG.

How humans solve the cocktail party problem remains unknown. However, progress has been made recently thanks to the realization that cortical activity tracks the amplitude envelope of speech. This has led to the development of regression methods for studying the neurophysiology of continuous speech. One such method, known as stimulus-reconstruction, has been successfully utilized with cortical surface recordings and magnetoencephalography (MEG). However, the former is invasive and gives a relatively restricted view of processing along the auditory hierarchy, whereas the latter is expensive and rare. Thus it would be extremely useful for research in many populations if stimulus-reconstruction was effective using electroencephalography (EEG), a widely available and inexpensive technology. Here we show that single-trial (≈60 s) unaveraged EEG data can be decoded to determine attentional selection in a naturalistic multispeaker environment. Furthermore, we show a significant correlation between our EEG-based measure of attention and performance on a high-level attention task. In addition, by attempting to decode attention at individual latencies, we identify neural processing at ∼200 ms as being critical for solving the cocktail party problem. These findings open up new avenues for studying the ongoing dynamics of cognition using EEG and for developing effective and natural brain-computer interfaces.

COP1 and ELF3 control circadian function and photoperiodic flowering by regulating GI stability.

Seasonal changes in day length are perceived by plant photoreceptors and transmitted to the circadian clock to modulate developmental responses such as flowering time. Blue-light-sensing cryptochromes, the E3 ubiquitin-ligase COP1, and clock-associated proteins ELF3 and GI regulate this process, although the regulatory link between them is unclear. Here we present data showing that COP1 acts with ELF3 to mediate day length signaling from CRY2 to GI within the photoperiod flowering pathway. We found that COP1 and ELF3 interact in vivo and show that ELF3 allows COP1 to interact with GI in vivo, leading to GI degradation in planta. Accordingly, mutation of COP1 or ELF3 disturbs the pattern of GI cyclic accumulation. We propose a model in which ELF3 acts as a substrate adaptor, enabling COP1 to modulate light input signal to the circadian clock through targeted destabilization of GI.

The multidrug resistance pump ABCB1 is a substrate for the ubiquitin ligase NEDD4-1.

The ATP Binding Cassette transporter ABCB1 can export the neurotoxic peptide ß-amyloid from endothelial cells that line the blood-brain barrier (BBB). This has the potential to lower cerebral levels of ß-amyloid, but ABCB1 expression in the BBB appears to be progressively reduced in patients with Alzheimer's disease. The surface density of many membrane proteins is regulated by ubiquitination catalyzed by ubiquitin E3 ligases. In brain capillaries of mice challenged with ß-amyloid ex vivo, we show that the level of the ubiquitin ligase Nedd4 increases concomitant with reduction in Abcb1. In vitro we show that human ABCB1 is a substrate for human NEDD4-1 ligase. Recombinant ABCB1 was purified from Sf21 insect cells and incubated with recombinant NEDD4-1 purified from Escherichia coli. The treated ABCB1 had reduced mobility on SDS-PAGE, and mass spectrometry identified eight lysine residues, K271, K272, K575, K685, K877, K885, K887 and K1062 that were ubiquitinated by NEDD4-1. Molecular modelling showed that all of the residues are exposed on the surface of the intracellular domains of ABCB1. K877, K885 and K887 in particular, are located in the intracellular loop of transmembrane helix 10 (TMH10) in close proximity, in the tertiary fold, to a putative NEDD4-1 binding site in the intracellular helix extending from TMH12 (PxY motif, residues 996-998). Transient expression of NEDD4-1 in HEK293 Flp-In cells stably expressing ABCB1 was shown to reduce the surface density of the transporter. Together, the data identify this ubiquitin ligase as a potential target for intervention in the pathophysiology of Alzheimer's disease.

Exclusion of plastid nucleoids and ribosomes from stromules in tobacco and Arabidopsis.

Stromules are stroma-filled tubules that extend from the surface of plastids and allow the transfer of proteins as large as 550 kDa between interconnected plastids. The aim of the present study was to determine if plastid DNA or plastid ribosomes are able to enter stromules, potentially permitting the transfer of genetic information between plastids. Plastid DNA and ribosomes were marked with green fluorescent protein (GFP) fusions to LacI, the lac repressor, which binds to lacO-related sequences in plastid DNA, and to plastid ribosomal proteins Rpl1 and Rps2, respectively. Fluorescence from GFP-LacI co-localised with plastid DNA in nucleoids in all tissues of transgenic tobacco (Nicotiana tabacum L.) examined and there was no indication of its presence in stromules, not even in hypocotyl epidermal cells, which contain abundant stromules. Fluorescence from Rpl1-GFP and Rps2-GFP was also observed in a punctate pattern in chloroplasts of tobacco and Arabidopsis [Arabidopsis thaliana (L.) Heynh.], and fluorescent stromules were not detected. Rpl1-GFP was shown to assemble into ribosomes and was co-localised with plastid DNA. In contrast, in hypocotyl epidermal cells of dark-grown Arabidopsis seedlings, fluorescence from Rpl1-GFP was more evenly distributed in plastids and was observed in stromules on a total of only four plastids (<0.02% of the plastids observed). These observations indicate that plastid DNA and plastid ribosomes do not routinely move into stromules in tobacco and Arabidopsis, and suggest that transfer of genetic information by this route is likely to be a very rare event, if it occurs at all.

Bul proteins, a nonredundant, antagonistic family of ubiquitin ligase regulatory proteins.

Like other Nedd4 ligases, Saccharomyces cerevisiae E3 Rsp5p utilizes adaptor proteins to interact with some substrates. Previous studies have indentified Bul1p and Bul2p as adaptor proteins that facilitate the ligase-substrate interaction. Here, we show the identification of a third member of the Bul family, Bul3p, the product of two adjacent open reading frames separated by a stop codon that undergoes readthrough translation. Combinatorial analysis of BUL gene deletions reveals that they regulate some, but not all, of the cellular pathways known to involve Rsp5p. Surprisingly, we find that Bul proteins can act antagonistically to regulate the same ubiquitin-dependent process, and the nature of this antagonistic activity varies between different substrates. We further show, using in vitro ubiquitination assays, that the Bul proteins have different specificities for WW domains and that the two forms of Bul3p interact differently with Rsp5p, potentially leading to alternate functional outcomes. These data introduce a new level of complexity into the regulatory interactions that take place between Rsp5p and its adaptors and substrates and suggest a more critical role for the Bul family of proteins in controlling adaptor-mediated ubiquitination.

Visible light induced degradation of perfluorooctanoic acid using iodine deficient bismuth oxyiodide photocatalyst.

A bismuth oxyiodide photocatalyst having coexistent iodine deficient phases viz. Bi4O5I2 and Bi5O7I was prepared by using a solvothermal method followed by calcination process. This has been used for the degradation of model perfluoroalkyl acids such as perfluorooctanoic acid at low concentrations (1 ppm) under simulated solar light irradiation. 94% PFOA degradation with a rate constant of 1.7 h-1 and 65% defluorination of PFOA have been achieved following 2 h of photocatalysis. The degradation of PFOA happened by the parallel direct redox reactions with high energy photoexcited electrons at the conduction band, electrons in iodine vacancies and superoxide radicals. The degradation intermediates were analyzed by electrospray ionization-mass spectrometry in the negative mode. The catalyst was converted to a more iodine deficient Bi5O7I phase during photocatalysis following creation of iodine vacancies, some of which were compensated by the fluoride ions released from degraded PFOA.

Enhanced removal of perfluorooctanoic acid with sequential photocatalysis and fungal treatment.

In this paper, we report the degradation of perfluorooctanoic acid (PFOA), which is a persistent contaminant in the environment that can severely impact human health, by exposing it to a photocatalyst, bismuth oxyiodide (BiOI), containing both Bi4O5I2 and Bi5O7I phases and a fungal biocatalyst (Cunninghamella elegans). Individually, the photocatalyst (after 3 h) and biocatalyst (after 48 h) degraded 35-40% of 100 ppm PFOA with 20-30% defluorination. There was a marked improvement in the degree of degradation (90%) and defluorination (60%) when PFOA was first photocatalytically treated, then exposed to the fungus. GC- and LC-MS analysis identified the products formed by the different treatments. Photocatalytic degradation of PFOA yielded short-chain perfluorocarboxylic acids, whereas fungal degradation yielded mainly 5:3 fluorotelomer carboxylic acid, which is a known inhibitor of cytochrome P450-catalysed degradation of PFAS in C. elegans. The combined treatment likely resulted in greater degradation because photocatalysis reduced the PFOA concentration without generating the inhibitory 5:3 fluorotelomer carboxylic acid, enabling the fungus to remove most of the remaining substrate. In addition, new fluorometabolites were identified that shed light on the initial catabolic steps involved in PFOA biodegradation.

Preparation, stability, and structural characterization of plutonium(VII) in alkaline aqueous solution.

A freshly prepared solution of Pu(VI) in 2 M NaOH was oxidized to Pu(VII), via ozonolysis, while simultaneously collecting X-ray absorption spectra. Analyses of the XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) data, acquired throughout the in situ experiments, show a dioxo coordination environment for Pu(VI), PuO(2)(2+), typical for it and the hexavalent actinyl species of U and Np, and its evolution into a tetraoxo-coordination environment for Pu(VII), PuO(4)(-), like that known for Np(VII). The EXAFS data provide average Pu-O distances of 1.79(1) and 1.88(1) Å, respectively. The second coordination shells, also fit as O atoms, provide Pu-O distances of 2.29-2.32 Å that are independent of the Pu oxidation state. The coordination numbers for the distant O atoms in sums with those for the nearest O atoms are consistent with 6-O environments for both Pu(VI) and Pu(VII) ions in accordance with their previously proposed speciation as [Pu(VI)O(2)(OH)(4)](2-) and [Pu(VII)O(4)(OH)(2)](3-), respectively. This solution speciation accounts precisely for the Pu(VI) and Pu(VII) coordination environments reported in various solid state structures. The Pu(VII) tetraoxo-dihydroxo anion was found to have a half-life of 3.7 h. Its instability is attributed to spontaneous reduction to Pu(VI) and not to a measurable extent of disproportionation. We found no direct evidence for Pu(VIII) in the X-ray data and, furthermore, the stoichiometry of the oxidation of Cr(III) by Pu is consistent with that expected for a valence-pure Pu(VII) preparation by ozonation and, in turn, stoichiometrically equivalent to the established Np(VII)/Cr(III) redox reaction.

Predictive Gap-balancing Reduces the Extent of Soft-tissue Adjustment Required After Bony Resection in Robot-assisted Total Knee Arthroplasty-A Comparison With Simulated Measured Resection.

Background: To understand the extent and frequency of soft-tissue adjustment required to achieve mediolateral (ML) balance in measured resection (MR) vs gap-balancing (GB) total knee arthroplasty, this study compared ML balance and joint laxity throughout flexion between the 2 techniques. The precision of predictive GB in achieving ML balance and laxity was also assessed. Methods: Two surgeons performed 95 robot-assisted GB total knee arthroplasties with predictive balancing, limiting tibial varus to 3° and adjusting femoral positioning to optimize balance. A robotic ligament tensioner measured joint laxity. Planned MR (pMR) was simulated by applying neutral tibial and femoral coronal resections and 3° of external femoral rotation. ML balance, laxity, component alignment, and resection depths were compared between planned GB (pGB) and pMR. ML balance and laxity were compared between pGB and final GB (fGB). Results: The proportion of knees with >2 mm of ML imbalance in flexion or extension ranged from 3% to 18% for pGB vs 50% to 53% for pMR (P < .001). Rates of ML imbalance >3 mm ranged from 0% to 9% for pGB and 30% to 38% for MR (P < .001). The mean pMR laxity was 1.9 mm tighter medially and 1.1 mm tighter laterally than pGB throughout flexion. The mean fGB laxity was greater than the mean pGB laxity by 0.5 mm medially and 1.2 mm laterally (P < .001). Conclusion: MR led to tighter joints than GB, with ML gap imbalances >3 mm in 30% of knees. GB planning improved ML balance throughout flexion but increased femoral posterior rotation variability and bone resection compared to MR. fGB laxity was likely not clinically significantly different than pGB.

The ancestral symbiont sensor kinase CSK links photosynthesis with gene expression in chloroplasts.

We describe a novel, typically prokaryotic, sensor kinase in chloroplasts of green plants. The gene for this chloroplast sensor kinase (CSK) is found in cyanobacteria, prokaryotes from which chloroplasts evolved. The CSK gene has moved, during evolution, from the ancestral chloroplast to the nuclear genomes of eukaryotic algae and green plants. The CSK protein is now synthesised in the cytosol of photosynthetic eukaryotes and imported into their chloroplasts as a protein precursor. In the model higher plant Arabidopsis thaliana, CSK is autophosphorylated and required for control of transcription of chloroplast genes by the redox state of an electron carrier connecting photosystems I and II. CSK therefore provides a redox regulatory mechanism that couples photosynthesis to gene expression. This mechanism is inherited directly from the cyanobacterial ancestor of chloroplasts, is intrinsic to chloroplasts, and is targeted to chloroplast genes.

Arrestin-like proteins mediate ubiquitination and endocytosis of the yeast metal transporter Smf1.

Many plasma membrane proteins in yeast are ubiquitinated and endocytosed, but how they are recognized for modification has remained unknown. Here, we show that the manganese transporter Smf1 is endocytosed when cells are exposed to cadmium ions, that this endocytosis depends on Rsp5-dependent ubiquitination of specific lysines and that it also requires phosphorylation at nearby sites. This phosphorylation is, however, constitutive rather than stress-induced. Efficient ubiquitination requires Ecm21 or Csr2, two members of a family of arrestin-like yeast proteins that contain several PY motifs and bind to Rsp5. Ecm21 also binds to phosphorylated Smf1, providing a link between Rsp5 and its substrate. PY motif-containing arrestin-like proteins are found in many species, including humans, and might have a general role as ubiquitin ligase adaptors.

Multiple interactions drive adaptor-mediated recruitment of the ubiquitin ligase rsp5 to membrane proteins in vivo and in vitro.

Recognition of membrane proteins by the Nedd4/Rsp5 ubiquitin ligase family is a critical step in their targeting to the multivesicular body pathway. Some substrates contain "PY" motifs (PPxY), which bind to WW domains in the ligase. Others lack PY motifs and instead rely on adaptors that recruit the ligase to them. To investigate the mechanism of adaptor-mediated ubiquitination, we have characterized the interactions between the adaptor Bsd2, the ubiquitin ligase Rsp5, and the membrane proteins Cps1, Tre1, and Smf1 from Saccharomyces cerevisiae. We have reconstituted adaptor-mediated modification of Cps1 and Tre1 in vitro, and we show that two PY motifs in Bsd2 and two WW domains (WW2 and WW3) in Rsp5 are crucial for this. The binding of a weak noncanonical DMAPSY motif in Bsd2 to WW3 is an absolute requirement for Bsd2 adaptor function. We show that sorting of the manganese transporter Smf1, which requires both Bsd2 and Tre1, depends upon two PY motifs in Bsd2 and one motif in Tre1 but only two WW domains in Rsp5. We suggest that sequential assembly of first a Bsd2/Rsp5 complex, then a Tre1/Bsd2/Rsp5 complex followed by a rearrangement of PY-WW interactions is required for the ubiquitination of Smf1.

Ti-Doped SBA-15 Catalysts Used in Phenol Oxidation Reactions.

Two Ti-SBA-15 catalysts are synthesized using techniques that should either deposit Ti atoms specifically at the SBA-15 surface or allow Ti-containing species to exist at both the surface and within the bulk of SBA-15. The materials have been characterized by Fourier transform infrared (FTIR), Raman and UV visible spectroscopies, transmission electron microscopy, scanning electron microscopy/energy-dispersive X-ray spectrometry microscopies, and N2 physisorption experiments. They have been applied in the total oxidation of phenol under catalytic wet air oxidation (CWAO) conditions and using photo- and plasma promotion. The materials retain the structure of SBA-15 following the doping in both cases and Ti incorporation is confirmed. The nature of the incorporated Ti remains unclear-with evidence for anatase TiO2 (from Raman and UV vis analysis) and evidence for atomically dispersed Ti from FTIR. In terms of reactivity, the presence of Ti in the in situ-prepared catalyst improves reactivity in the photopromoted reaction (increasing conversion from 28 to 60%), while both Ti catalysts improve reactivity in the CWAO reaction (by 7% over the in situ catalyst and by 25% over the grafted material). The presence of Ti has no beneficial effect on conversion in the plasma-promoted reaction. Here, however, Ti does affect the nature of the oxidized intermediates formed during the total phenol oxidation.

CO2 Decomposition in CO2 and CO2 /H2 Spark-like Plasma Discharges at Atmospheric Pressure.

In this work, a spark-like plasma discharge is ignited in pure CO2 and in CO2 /H2 mixtures to investigate CO formation. Power pulsing is used to limit arc formation to sustain a high current transient "spark-like" plasma consisting of a mixed mode discharge comprising an initial current pulse ("spark") followed by a longer-lived glow mode thorough each half cycle of the applied voltage. In pure CO2 , the efficiency ranged between 20-50 % for CO2 conversions between 9-18 % for gas residence times of 100-600 ms. Adding H2 as a co-reactant was investigated for a wide range of mixture ratios. The outlet gas was found to produce O2 -free mixtures of CO/H2 /CO2 . Conversion rates in CO2 /H2 mixtures are found to be similar to pure CO2 at equivalent residence times. The primary role of H2 as a co-reactant is therefore found to be the removal of O2 formed during dissociation of CO2 . The energy cost of this dilution resulted in reduced efficiency for CO2 conversion (from 41 to 18 %), which is correlated to the efficiency drop found for pure CO2 conversion at lower flows. Opportunities for optimising this small volume "unit-cell" spark reactor are encouraged by the results presented. This approach could enable deployment of serial or parallel combinations of such reactors capable of dealing cost-effectively with the conversion of the larger CO2 and CO2 /H2 volumes required in future industry applications.

An Arabidopsis mutant able to green after extended dark periods shows decreased transcripts of seed protein genes and altered sensitivity to abscisic acid.

An Arabidopsis mutant showing an altered ability to green on illumination after extended periods of darkness has been isolated in a screen for genomes uncoupled (gun) mutants. Following illumination for 24 h, 10-day-old dark-grown mutant seedlings accumulated five times more chlorophyll than wild-type seedlings and this was correlated with differences in plastid morphology observed by transmission electron microscopy. The mutant has been named greening after extended darkness 1 (ged1). Microarray analysis showed much lower amounts of transcripts of genes encoding seed storage proteins, oleosins, and late embryogenesis abundant (LEA) proteins in 7-day-old seedlings of ged1 compared with the wild type. RNA gel-blot analyses confirmed very low levels of transcripts of seed protein genes in ged1 seedlings grown for 2-10 d in the dark, and showed higher amounts of transcripts of photosynthesis-related genes in illuminated 10-day-old dark-grown ged1 seedlings compared with the wild type. Consensus elements similar to abscisic acid (ABA) response elements (ABREs) were detected in the upstream regions of all genes highly affected in ged1. Germination of ged1 seeds was hypersensitive to ABA, although no differences in ABA content were detected in 7-day-old seedlings. This suggests the mutant may have an altered responsiveness to ABA, affecting expression of ABA-responsive genes and plastid development during extended darkness.

Modulation of F1 hybrid stature without altering parent plants through trans-activated expression of a mutated rice GAI homologue.

Hybrid breeding, by taking advantage of heterosis, brings about many superior properties to the F1 progeny. However, some properties, such as increased plant height, are not desirable for agronomic purposes. To specifically counter the height increase associated with hybrid progeny, we employed an Arabidopsis model and tested a trans-activation system for specifically expressing a mutated GAI gene only in the F1 hybrid plants to reduce plant stature. A transcriptional activator, the Gal4 DNA-binding domain fused to the acidic activation domain of herpes simplex virus VP16 protein, driven by a maize ubiquitin promoter, was introduced in one parental line. A rice GAI homologue with an N-terminal deletion of the DELLA domain, driven by a promoter that is responsive to the transcriptional activator, was transferred into another parental line. After genetic crossing, trans-activation of the GAI mutant gene resulted in a dwarf phenotype. Over 50 pair-wise crosses between the parental lines were performed, and analyses suggested that the percentage of F1 progeny exhibiting dwarfism ranged from about 25% to 100%. Furthermore, the dwarfism trait introduced in F1 progeny did not seem to affect total seed yield. Our result suggests the feasibility of manipulating F1 hybrid progeny traits without affecting parent plants or the agronomic property of the progeny.

Low-Frequency Cortical Entrainment to Speech Reflects Phoneme-Level Processing.

The human ability to understand speech is underpinned by a hierarchical auditory system whose successive stages process increasingly complex attributes of the acoustic input. It has been suggested that to produce categorical speech perception, this system must elicit consistent neural responses to speech tokens (e.g., phonemes) despite variations in their acoustics. Here, using electroencephalography (EEG), we provide evidence for this categorical phoneme-level speech processing by showing that the relationship between continuous speech and neural activity is best described when that speech is represented using both low-level spectrotemporal information and categorical labeling of phonetic features. Furthermore, the mapping between phonemes and EEG becomes more discriminative for phonetic features at longer latencies, in line with what one might expect from a hierarchical system. Importantly, these effects are not seen for time-reversed speech. These findings may form the basis for future research on natural language processing in specific cohorts of interest and for broader insights into how brains transform acoustic input into meaning.