How Are ‘Barack Obama’ and ‘President Elect’ Differentially Stored in the Brain? An ERP Investigation on the Processing of Proper and Common Noun Pairs

Background

One of the most debated issues in the cognitive neuroscience of language is whether distinct semantic domains are differentially represented in the brain. Clinical studies described several anomic dissociations with no clear neuroanatomical correlate. Neuroimaging studies have shown that memory retrieval is more demanding for proper than common nouns in that the former are purely arbitrary referential expressions. In this study a semantic relatedness paradigm was devised to investigate neural processing of proper and common nouns.

Methodology/Principal Findings

780 words (arranged in pairs of Italian nouns/adjectives and the first/last names of well known persons) were presented. Half pairs were semantically related (“Woody Allen” or “social security”), while the others were not (“Sigmund Parodi” or “judicial cream”). All items were balanced for length, frequency, familiarity and semantic relatedness. Participants were to decide about the semantic relatedness of the two items in a pair. RTs and N400 data suggest that the task was more demanding for common nouns. The LORETA neural generators for the related-unrelated contrast (for proper names) included the left fusiform gyrus, right medial temporal gyrus, limbic and parahippocampal regions, inferior parietal and inferior frontal areas, which are thought to be involved in the conjoined processing a familiar face with the relevant episodic information. Person name was more emotional and sensory vivid than common noun semantic access.

Conclusions/Significance

When memory retrieval is not required, proper name access (conspecifics knowledge) is not more demanding. The neural generators of N400 to unrelated items (unknown persons and things) did not differ as a function of lexical class, thus suggesting that proper and common nouns are not treated differently as belonging to different grammatical classes.     

High levels of arbuscular mycorrhizal fungus colonization on Medicago truncatula reduces plant suitability as a host for pea aphids (Acyrthosiphon pisum)

This study sheds light on a poorly understood area in insect-plant-microbe interactions,focusing on aphid probing and feeding behavior on plants with varying levels of arbuscular mycorrhizal(AM)fungus root colonization.It investigates a commonly occurring interaction of three species:pea aphid Acyrthosiphon pisum,barrel medic Medicago truncatula,and the AM fungus Rhizophagus irregularis,examining whether aphid-feeding behavior changes when insects feed on plants at different levels of AM fungus colonization(42% and 84% root length colonized).Aphid probing and feeding behavior was monitored throughout 8 h of recording using the electrical penetration graph(EPG)technique,also,foliar nutrient content and plant growth were measured.Summarizing,aphids took longer to reach their 1st sustained phloem ingestion on the 84% AM plants than on the 42% AM plants or on controls.Less aphids showed phloem ingestion on the 84% AM plants relative to the 42% AM plants.Shoots of the 84% AM plants had higher percent carbon(43.7%)relative to controls(40.5%),and the 84% AM plants had reduced percent nitrogen(5.3%)relative to the 42% AM plants(6%).In conclusion,EPG and foliar nutrient data support the hypothesis that modifications in plant anatomy(e.g.,thicker leaves),and poor food quality(reduced nitrogen)in the 84% AM plants contribute to reduced aphid success in locating phloem and ultimately to differences in phloem sap ingestion.This work suggests that M.truncatula plants benefit from AM symbiosis not only because of increased nutrient uptake but also because of reduced susceptibility to aphids.     

Segregation of a M404V mutation of the p62/sequestosome 1 (p62/SQSTM1) gene with polyostotic Paget's disease of bone in an Italian family

Mutations of the p62/Sequestosome 1 gene (p62/SQSTM1) account for both sporadic and familial forms of Paget's disease of bone (PDB). We originally described a methionine-->valine substitution at codon 404 (M404V) of exon 8, in the ubiquitin protein-binding domain of p62/SQSTM1 gene in an Italian PDB patient. The collection of data from the patient's pedigree provided evidence for a familial form of PDB. Extension of the genetic analysis to other relatives in this family demonstrated segregation of the M404V mutation with the polyostotic PDB phenotype and provided the identification of six asymptomatic gene carriers. DNA for mutational analysis of the exon 8 coding sequence was obtained from 22 subjects, 4 PDB patients and 18 clinically unaffected members. Of the five clinically ascertained affected members of the family, four possessed the M404V mutation and exhibited the polyostotic form of PDB, except one patient with a single X-ray-assessed skeletal localization and one with a polyostotic disease who had died several years before the DNA analysis. By both reconstitution and mutational analysis of the pedigree, six unaffected subjects were shown to bear the M404V mutation, representing potential asymptomatic gene carriers whose circulating levels of alkaline phosphatase were recently assessed as still within the normal range. Taken together, these results support a genotype-phenotype correlation between the M404V mutation in the p62/SQSTM1 gene and a polyostotic form of PDB in this family. The high penetrance of the PDB trait in this family together with the study of the asymptomatic gene carriers will allow us to confirm the proposed genotype-phenotype correlation and to evaluate the potential use of mutational analysis of the p62/SQSTM1 gene in the early detection of relatives at risk for PDB.     

Combination of Iron Overload Plus Ethanol and Ischemia Alone Give Rise to the Same Endogenous Free Iron Pool

Iron overload aggravates tissue damage caused by ischemia and ethanol intoxication. The underlying mechanisms of this phenomenon are not yet clear. To clarify these mechanisms we followed free iron (“loosely” bound redox-active iron) concentration in livers from rats subjected to experimental iron overload, acute ethanol intoxication, and ex vivo warm ischemia. The levels of free iron in non-homogenized liver tissues, liver homogenates, and hepatocyte cultures were analyzed by means of EPR spectroscopy. Ischemia gradually increased the levels of endogenous free iron in liver tissues and in liver homogenates. The increase was accompanied by the accumulation of lipid peroxidation products. Iron overload alone, known to increase significantly the total tissue iron, did not affect either free iron levels or lipid peroxidation. Homogenization of iron-loaded livers, however, resulted in the release of a significant portion of free iron from endogenous depositories. Acute ethanol intoxication increased free iron levels in liver tissue and diminished the portion of free iron releasing during homogenization. Similarly to liver tissue, the primary hepatocyte culture loaded with iron in vitro released significantly more free iron during homogenization compared to non iron-loaded hepatocyte culture. Analyzing three possible sources of free iron release under these experimental conditions in liver cells, namely ferritin, intracellular transferrin-receptor complex and heme oxygenase, we suggest that redox active free iron is released from ferritin under ischemic conditions whereas ethanol and homogenization facilitate the release of iron from endosomes containing transferrin-receptor complexes.     

Role of the autonomic nervous system in generating non-linear dynamics in short-term heart period variability.

We evaluated the role played by the autonomic nervous system in producing non-linear dynamics in short heart period variability (HPV) series recorded in healthy young humans. Non-linear dynamics are detected using an index of predictability based on a local non-linear predictor and a surrogate data approach. Different types of surrogates are utilized: (i) phase-randomized Fourier-transform based (FT) data; (ii) amplitude-adjusted FT (AAFT) data; and (iii) iteratively refined AAFT (IAAFT) data of two types (IAAFT-1 and IAAFT-2). The approach was applied to experimental protocols activating or blocking the sympathetic or parasympathetic branches of the autonomic nervous system or periodically perturbing cardiovascular control via paced respiration at different breathing rates. We found that short-term HPV was mostly linear at rest. Experimental protocols activating the sympathetic or parasympathetic nervous system did not produce non-linear dynamics. In contrast, paced respiration, especially at slow breathing rates, elicited significantly non-linear dynamics. Therefore, in short-term HPV ( approximately 300 beats) the use of non-linear models is not supported by the data, except under conditions whereby the subject is constrained to a slow respiratory rate.     

Cell wall proteomics of sugarcane cell suspension cultures

The use of cell walls to produce cellulosic ethanol from sugarcane bagasse is a new challenge. A better knowledge of proteins involved in cell wall remodelling is essential to improve the saccharification processes. Cell suspension cultures were used for this first cell wall proteomics study of sugarcane. Proteins extracted from cell walls were identified using an adapted protocol. They were extracted using 0.2 M CaCl₂ and 2 M LiCl after purification of cell walls. The proteins were then identified by the innovative nanoACQUITY UPLC MS/MS technology and bioinformatics using the translated SUCEST EST cluster database of sugarcane. The experiments were reproduced three times. Since Sorghum bicolor is the closest plant with a fully sequenced genome, homologous proteins were searched for to complete the annotation of proteins, that is, prediction of subcellular localization and functional domains. Altogether, 69 different proteins predicted to be secreted were identified among 377 proteins. The reproducibility of the experiments is discussed. These proteins were distributed into eight functional classes. Oxidoreductases such as peroxidases were well represented, whereas glycoside hydrolases were scarce. This work provides information about the proteins that could be manipulated through genetic transformation, to increase second‐generation ethanol production.     

Efficacy of <Emphasis Type="Italic">Neoseiulus californicus</Emphasis> and <Emphasis Type="Italic">Phytoseiulus persimilis</Emphasis> in suppression of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> in young clementine plants

Tetranychus urticae is one of the most damaging tetranychid mites affecting clementine orchards in Spain, where natural control is insufficient. Furthermore, in clementine nurseries, tender foliage is highly susceptible to attack and natural enemies are almost always absent. Therefore, acaricides are often used indiscriminately. Alternative control measures are necessary, both in commercial orchards and clementine nurseries. In order to assess the efficacy of inoculative releases of N. californicus and P. persimilis to reduce T. urticae populations in young Spanish clementine plants, a semi-field experiment was conducted and repeated in three seasons (spring, summer and autumn). Phytoseiulus persimilis was highly effective in reducing both T. urticae infestations and the damage level inflicted on plants at both release rates evaluated (40 and 80 phytoseiids/plant) and all three periods considered. By contrast, N. californicus demonstrated low performance under certain conditions. The results of this study could be adapted and transferred to nurseries and young citrus plantations.     

Anisotropic elastic network modeling of entire microtubules

Microtubules are supramolecular structures that make up the cytoskeleton and strongly affect the mechanical properties of the cell. Within the cytoskeleton filaments, the microtubule (MT) exhibits by far the highest bending stiffness. Bending stiffness depends on the mechanical properties and intermolecular interactions of the tubulin dimers (the MT building blocks). Computational molecular modeling has the potential for obtaining quantitative insights into this area. However, to our knowledge, standard molecular modeling techniques, such as molecular dynamics (MD) and normal mode analysis (NMA), are not yet able to simulate large molecular structures like the MTs; in fact, their possibilities are normally limited to much smaller protein complexes. In this work, we developed a multiscale approach by merging the modeling contribution from MD and NMA. In particular, MD simulations were used to refine the molecular conformation and arrangement of the tubulin dimers inside the MT lattice. Subsequently, NMA was used to investigate the vibrational properties of MTs modeled as an elastic network. The coarse-grain model here developed can describe systems of hundreds of interacting tubulin monomers (corresponding to up to 1,000,000 atoms). In particular, we were able to simulate coarse-grain models of entire MTs, with lengths up to 350 nm. A quantitative mechanical investigation was performed; from the bending and stretching modes, we estimated MT macroscopic properties such as bending stiffness, Young modulus, and persistence length, thus allowing a direct comparison with experimental data.