GreekLex 2: a comprehensive lexical database with part-of-speech, syllabic, phonological, and stress information

Databases containing lexical properties on any given orthography are crucial for psycholinguistic research. In the last ten years, a number of lexical databases have been developed for Greek. However, these lack important part-of-speech information. Furthermore, the need for alternative procedures for calculating syllabic measurements and stress information, as well as combination of several metrics to investigate linguistic properties of the Greek language are highlighted. To address these issues, we present a new extensive lexical database of Modern Greek (GreekLex 2) with part-of-speech information for each word and accurate syllabification and orthographic information predictive of stress, as well as several measurements of word similarity and phonetic information. The addition of detailed statistical information about Greek part-of-speech, syllabification, and stress neighbourhood allowed novel analyses of stress distribution within different grammatical categories and syllabic lengths to be carried out. Results showed that the statistical preponderance of stress position on the pre-final syllable that is reported for Greek language is dependent upon grammatical category. Additionally, analyses showed that a proportion higher than 90% of the tokens in the database would be stressed correctly solely by relying on stress neighbourhood information. The database and the scripts for orthographic and phonological syllabification as well as phonetic transcription are available at http://www.psychology.nottingham.ac.uk/greeklex/

Statistical learning leads to persistent memory: evidence for one-year consolidation

Statistical learning is a robust mechanism of the brain that enables the extraction of environmental patterns, which is crucial in perceptual and cognitive domains. However, the dynamical change of processes underlying long-term statistical memory formation has not been tested in an appropriately controlled design. Here we show that a memory trace acquired by statistical learning is resistant to inference as well as to forgetting after one year. Participants performed a statistical learning task and were retested one year later without further practice. The acquired statistical knowledge was resistant to interference, since after one year, participants showed similar memory performance on the previously practiced statistical structure after being tested with a new statistical structure. These results could be key to understand the stability of long-term statistical knowledge

Bioactive paper platform for colorimetric phenols detection.

Polyphenols, as food antioxidants, are of great interest due to their health benefits as they decrease the risks of cancer and coronary cardiopathy (1). Moreover they influence the quality and organoleptic characteristics of foods (2). Lastly, some neurotransmitters are phenolic compounds. Hence the need to work out a sensitive, portable and inexpensive detection methods to monitor these compounds (3). We developed a disposable paper-based bioassay for the detection of phenolic compounds; the assay was successfully applied for the determination of polyphenols in a real matrix such as wine. The colorimetric quantification of the analyte is based on an enzymatic assay. The tyrosinase enzyme has been immobilized on a filter paper by simple over-spotting with 3-methyl-2-benzothiazolinone hydrazone (MBTH), that allows the detection of phenols by forming stable colored adducts with their enzymatic oxidation products. The color intensity of the adduct (developed after 5 min of reaction) was found to increase proportionally with the increase of the phenolic substrate concentrations. Analyte detection can be achieved by eye and quantification can be simply obtained by using a camera phone and an image analysis software. The response, characteristics of the sensor were determined using l-3,4-dihydroxyphenyl-alanine (l-DOPA), an archetype substrate of tyrosinase, as the analyte. This disposable paper-based biosensor relies on a rapid and simple method, without need of sophisticated instrumentation and trained personnel and could be extremely useful in remote locations or developing countries which does not have ready access to laboratory facilities and where simple, sensitive and low cost bioassays are essentials. 1) D. Del Rio, L.G. Costa, M.E. Lean, A. Croizer. Nutr. Metab. Cardiovasc. Dis. 20 (2010) 1-6. 2) I. Ignat, I. Volf, V.I. Popa. Food Chem. 126 (2011) 1821-1835. 3) M. Arciuli, G. Palazzo, A. Gallone, A. Mallardi. Sensors & Actuators: B. Chemical (2013)In press

Measuring children’s auditory statistical learning via serial recall

Statistical learning (SL) has been a prominent focus of research in developmental and adult populations, guided by the assumption that it is a fundamental component of learning underlying higher-order cognition. In developmental populations, however, there have been recent concerns regarding the degree to which many current tasks reliably measure SL, particularly in younger children. In the current article, we present the results of two studies that measured auditory statistical learning (ASL) of linguistic stimuli in children aged 5–8 years. Children listened to 6 min of continuous syllables comprising four trisyllabic pseudowords. Following the familiarization phase, children completed (a) a two-alternative forced-choice task and (b) a serial recall task in which they repeated either target sequences embedded during familiarization or foils, manipulated for sequence length. Results showed that, although both measures consistently revealed learning at the group level, the recall task better captured learning across the full range of abilities and was more reliable at the individual level. We conclude that, as has also been demonstrated in adults, the method holds promise for future studies of individual differences in ASL of linguistic stimuli

Seasonal variations of Rana esculenta L. skin tyrosinase

Various enzymes are known to be involved in melanin biosynthesis, but the key role appertains to tyrosinase. In amphibians this enzyme displays peculiar characteristics: i) it requires an activation process; ii) its level of enzymatic activity in the animal skin changes depending on the season. In this work, by using chymotrypsin, subtilisin and SDS as putative activators, we studied the activation process of the skin pro-tyrosinase of Rana esculenta L. in different seasons over a period of two years. We found that chymotrypsin and subtilisin were able to yield an active enzyme, but not SDS. The maximum levels of tyrosinase activity were recorded in winter and the minimum in summer. We detected tyrosinase activity in the melanosomal fraction, where the enzyme form was least sensitive to proteolytic activation, probably corresponding to a "mature" tyrosinase. The enzyme forms found in the microsomal and soluble fractions were more sensitive to proteolytic activation, probably corresponding to "immature" tyrosinase. On SDS-PAGE, the tyrosinase activity assays showed a dopa-positive band at 200 kDa and a second aggregated band with a still higher molecular mass. The significance of these results in frog melanogenesis regulation is discussed

Essential oils as tyrosinase inhibitors: a different effect on tyrosinase of different sources. A preliminary study

Plant extracts are a rich source of bioactive compounds and have been traditionally used for both cosmetic and therapeutic purposes. In plants and fungi, the presence of a variety of phenolic compounds leads to the undesirable browning of fruits and vegetables (1). In humans, disorders in the amount and distribution of melanin pigments can be associated to disease states. Plant-derived chemicals have been shown to exert various biological activities and pharmacological effects (2). Because tyrosinase catalyzes the key steps of melanogenesis, most of the strategies for developing skin-lightening and/or anti-food-browning agents are based on the inhibition of tyrosinase activity (i.e. oxidation of L-DOPA) (3). In this study, the essential oils obtained by hydrodistillation from nine different plants were investigated for their potential inhibitory activity on mushroom tyrosinase (MT) and on B16 melanoma cell line tyrosinase (MCLT). The essential oils composition was assessed by GC-mass-spectrometry techniques, anyway we decided to investigate their possible anti-tyrosinase activity considering the oil in its entirety because the biological activity of plant extracts often derives from the combined effect of their different components (4,5). Our results indicate a different inhibitory efficacy on MT and MCLT activities. While extracts from Cinnamonum zeylanicum, Syzigium aromaticum and Citrus aurantium amara appear to be the best inhibitors of both MT and MCLT, with an oil dose-dependent effect, oils from Origanum vulgaris and Rosmarinus officinalis have major inhibitory effect on MT. Our findings indicate that cinnamon, clove and bitter orange essential oils have high potentials in applications as skin-whitening agents of natural source. (1) Martinez M.V. et al. Trends Food Sci Technol 1995, 6: 195-200. (2) Craig W.J. Am J Clin Nutr 1999, 70: 491S-9S. (3) Briganti S. et al. Pigment Cell Res 2003,16: 101-110. (4) Burt S. Int J Food Microbiol 2004, 94: 223-253