Are form priming effects phonological or perceptual? Electrophysiological evidence from American Sign Language

Form priming has been used to identify and demarcate the processes that underlie word and sign recognition. The facilitation that results from the prime and target being related in form is typically interpreted in terms of pre-activation of linguistic representations, with little to no consideration for the potential contributions of increased perceptual overlap between related pairs. Indeed, isolating the contribution of perceptual similarity is impossible in spoken languages; there are no listeners who can perceive speech but have not acquired a sound-based phonological system. Here, we compared the electrophysiological indices of form priming effects in American Sign Language between hearing non-signers (i.e., who had no visual-manual phonological system) and deaf signers. We reasoned that similarities in priming effects between groups would most likely be perceptual in nature, whereas priming effects that are specific to the signer group would reflect pre-activation of phonological representations. Behavior in the go/no-go repetition detection task was remarkably similar between groups. Priming in a pre-N400 window was also largely similar across groups, consistent with an early effect of perceptual similarity. However, priming effects diverged between groups during the subsequent N400 and post-N400 windows. Signers had more typical form priming effects and were especially attuned to handshape overlap, whereas non-signers did not exhibit an N400 component and were more sensitive to location overlap. We attribute this pattern to an interplay between perceptual similarity and phonological knowledge. Perceptual similarity contributes to early phonological priming effects, while phonological knowledge tunes sensitivity to linguistically relevant dimensions of perceptual similarity.

Matching pictures and signs: An ERP study of the effects of iconic structural alignment in American sign language

Event-related potentials (ERPs) were used to explore the effects of iconicity and structural visual alignment between a picture-prime and a sign-target in a picture-sign matching task in American Sign Language (ASL). Half the targets were iconic signs and were presented after a) a matching visually-aligned picture (e.g., the shape and location of the hands in the sign COW align with the depiction of a cow with visible horns), b) a matching visually-nonaligned picture (e.g., the cow's horns were not clearly shown), and c) a non-matching picture (e.g., a picture of a swing instead of a cow). The other half of the targets were filler signs. Trials in the matching condition were responded to faster than those in the non-matching condition and were associated with smaller N400 amplitudes in deaf ASL signers. These effects were also observed for hearing non-signers performing the same task with spoken-English targets. Trials where the picture-prime was aligned with the sign target were responded to faster than non-aligned trials and were associated with a reduced P3 amplitude rather than a reduced N400, suggesting that picture-sign alignment facilitated the decision process, rather than lexical access. These ERP and behavioral effects of alignment were found only for the ASL signers. The results indicate that iconicity effects on sign comprehension may reflect a task-dependent strategic use of iconicity, rather than facilitation of lexical access.

The organization of the American Sign Language lexicon: Comparing one- and two-parameter ERP phonological priming effects across tasks

We used phonological priming and ERPs to investigate the organization of the lexicon in American Sign Language. Across go/no-go repetition detection and semantic categorization tasks, targets in related pairs that shared handshape and location elicited smaller N400s than targets in unrelated pairs, indicative of facilitated processing. Handshape-related targets also elicited smaller N400s than unrelated targets, but only in the repetition task. The location priming effect reversed direction across tasks, with slightlylargeramplitude N400s for targets in related versus unrelated pairs in the semantic task, indicative of interference. These patterns imply that handshape and location play different roles during sign recognition and that there is a hierarchical organization for the sign lexicon. Similar to interactive-activation models of word recognition, we argue for differentiation between sublexical facilitation and lexical competition. Lexical competition is primarily driven by the location parameter and is more engaged when identification of single lexico-semantic entries is required.

AMF communities associated to Vitis vinifera in an Italian vineyard subjected to integrated pest management at two different phenological stages

Vitis vinifera L. is an economically important crop that can be influenced by soil microorganisms, including arbuscular mycorrhizal fungi (AMF), that establish symbiotic associations with its roots. AMF have beneficial effects on grapevine performance improving water use efficiency and replant success. Most grapevine varieties are susceptible to various diseases, and integrated pest management (IPM) is one of the emerging approaches to perform pest control. In the present study, we examined the AMF communities present in the soil associated to the roots of V. vinifera cv. Pinot Noir (comparing them to those present in a soil not affected by grapevine roots), in a vineyard subjected to IPM at two different phenological stages, using 454 Roche sequencing technology. We proposed a new approach to analyze sequencing data. Most of the taxa were included in the family Glomeraceae. In particular, Glomus sp. Rhizophagus sp. and Septoglomus viscosum were present. The family Archeosporaceae was represented only by the genus Archeospora sp. Different AMF communities were found in the two soils and the importance of the phenological stage in regulating AMF biodiversity was assessed.

Metaproteomic characterization of theVitis vinifera rhizosphere

The rhizosphere is a hotspot of microbial activity where the release of root exudates stimulates bacterial density and diversity. The majority of the bacterial cells in soil are viable, unculturable, but active. Proteomic tools could be useful in gaining information about microbial community activity and to better understand the real interactions between roots and soil. The aim of this work was to characterize the bacterial community associated with Vitis vinifera cv. Pinot Noir roots using a metaproteome approach. Our results confirmed the large potential of proteomics in describing the environmental microbial communities and their activities: in particular, we showed that bacteria belonging to Streptomyces, Bacillus, Bradyrhizobium, Burkholderia and Pseudomonas genera are the most active in protein expression. Concerning the biological activity of these genera in the rhizosphere, we observed the exclusive presence of the phosphorus metabolic process and the regulation of primary metabolic processes. To our knowledge, this is the first study reporting the rhizosphere proteome of V. vinifera, describing the bacterial community structure and activity of an important ecosystem for the Italian landscape, agriculture and economy.

Antifungal activity of essential oils against azole-resistant and azole-susceptible vaginal Candida glabrata strains

Candida glabrata is an opportunistic pathogen, associated with endocarditis, meningitis, and disseminated disease, and also with complicated vaginitis. Essential oils derived from aromatic plants are known in traditional medicine as antimicrobial agents and have antifungal properties. The aim of this work was to evaluate whether 12 tested essential oils (tea tree, laurel, anise, basil, bergamot, lavender, mint, oregano, grapefruit, rosemary, winter savory, and ginger) could have a transverse effect on C. glabrata sensitive strains but above all on strains resistant to the three main azole antifungals used (clotrimazole, fluconazole, itraconazole). For this reason, different strains of C. glabrata, vaginal isolated, were characterized (disk diffusion assay, minimal inhibitory concentration) with respect to their response to such antifungals. Electron microscopy analyses were performed to examine cellular damages in depth. Subsequently, we wanted to evaluate the effect of the oils on human cells to estimate their potential cytotoxicity. Oregano and winter savory were the two most effective essential oils, inducing growth inhibition, cell damage of C. glabrata strains (both sensitive and resistant to azole antifungal drugs), and medium–high level of toxicity against human keratinocytes. The results of this work support the research for new alternatives or complementary therapies against vaginal candidiasis.

Sensitivity of Candida albicans to essential oils: are they an alternative to antifungal agents?

AIMS

Candida albicans is an important opportunistic pathogen, responsible for the majority of yeast infections in humans. Essential oils, extracted from aromatic plants, are well-known antimicrobial agents, characterized by a broad spectrum of activities, including antifungal properties. The aim of this work was to assess the sensitivity of 30 different vaginal isolated strains of C. albicans to 12 essential oils, compared to the three main used drugs (clotrimazole, fluconazole and itraconazole).

METHODS AND RESULTS

Thirty strains of C. albicans were isolated from vaginal swab on CHROMagar^™ Candida. The agar disc diffusion method was employed to determine the sensitivity to the essential oils. The antifungal activity of the essential oils and antifungal drugs (clotrimazole, itraconazole and fluconazole) were investigated using a microdilution method. Transmission and scanning electron microscopy analyses were performed to get a deep inside on cellular damages. Mint, basil, lavender, tea tree oil, winter savory and oregano essential oils inhibited both the growth and the activity of C. albicans more efficiently than clotrimazole. Damages induced by essential oils at the cellular level were stronger than those caused by clotrimazole.

CONCLUSIONS

Candida albicans is more sensitive to different essential oils compared to the main used drugs. Moreover, the essential oil affected mainly the cell wall and the membranes of the yeast.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of this work support the research for new alternatives or complementary therapies against vaginal candidiasis.

Ordered collagen membranes: production and characterization

A collagen membrane with microscopic order is presented. The membranes were produced with acid-soluble collagen, using two different methods to obtain orientation. The product was characterized by mean of UV and IR spectra, scanning electronic microscopy, optical microscopy and laser diffractometry. The results clearly show a high level of order in the membranes obtained by both techniques. Permeability for rifamycin, ascorbic acid and NaCl was also measured. Due to the characteristics of the membranes, they have a potential application for treatment of surface injuries.

Interactions between Pseudomonas putida UW4 and Gigaspora rosea BEG9 and their consequences for the growth of cucumber under salt-stress conditions

AIMS

After the determination of the toxic but nonlethal concentration of NaCl for cucumber, we examined the interaction between an ACC (1-aminocyclopropane-1-carboxylate) deaminase producing bacterial strain and an arbuscular mycorrhizal fungus (AMF) and their effects on cucumber growth under salinity.

METHODS AND RESULTS

In the first experiment, cucumber seedlings were exposed to 0.1, 50, 100 or 200 mmol l(-1) NaCl, and plant biomass and leaf area were measured. While seeds exposed to 200 mmol l(-1) NaCl did not germinate, plant growth and leaf size were reduced by 50 or 100 mmol l(-1) salt. The latter salt cancentration caused plant death in 1 month. In the second experiment, seeds were inoculated with the ACC deaminase-producing strain Pseudomonas putida UW4 (AcdS(+)), its mutant unable to produce the enzyme (AcdS(-)), or the AMF Gigaspora rosea BEG9, individually or in combination and exposed to 75 mmol l(-1) salt. Plant morphometric and root architectural parameters, mycorrhizal and bacterial colonization and the influence of each micro-organism on the photosynthetic efficiency were evaluated. The AcdS(+) strain or the AMF, inoculated alone, increased plant growth, affected root architecture and improved photosynthetic activity. Mycorrhizal colonization was inhibited by each bacterial strain.

CONCLUSIONS

Salinity negatively affects cucumber growth and health, but root colonization by ACC deaminase-producing bacteria or arbuscular mycorrhizal fungi can improve plant tolerance to such stressful condition.

SIGNIFICANCE AND IMPACT OF THE STUDY

Arbuscular mycorrhizal fungus and bacterial ACC deaminase may ameliorate plant growth under stressful conditions. It was previously shown that, under optimal growth conditions, Ps. putida UW4 AcdS(+) increases root colonization by Gi. rosea resulting in synergistic effects on cucumber growth. These results suggest that while in optimal conditions ACC deaminase is mainly involved in the bacteria/fungus interactions, while under stressful conditions this enzyme plays a role in plant/bacterium interactions. This finding is relevant from an ecological and an applicative point of view.