The impact of multilingualism & language learning experiences on an immigrant woman\u27s identity: a case study

Following the interpretive qualitative approach, the present study strives to give voice to an immigrant woman by telling her story about the development of her identity as a multilingual learner of English. Using multiple methods of data collection (in-depth interviews, informal observations, documents, artifact, member checks, and peer debriefings), this research attempts to shed light on how an immigrant woman makes sense out of her social world through the languages she uses, their function in her life, the meanings she assigns to each and the role of learning languages on her multilingual identity. Some SLA investigators have argued that because mainstream SLA theorists have paid little attention to and not adequately addressed such language learning experiences as inequitable power relations between language learners and native speakers, there are major gaps in theory in reference to the relationship between the individual language learner and his/her social surroundings. For the participant in this study, these language learning experiences have been leading factors in the development of her multilingual identity and have been an affective factor for her acquisition of English, leading to subtractive bilingualism. The findings from this study call for education programs which foster and lay a foundation for additive bilingualism

An Evaluation of Kinetic Parameters of Cadmium and Copper Biosorption by Immobilized Cells

Bioremediation is the use of living organisms to reduce or eliminate environmental hazards resulting from the accumulation of toxic chemicals and other hazardous wastes. This technology is based on the utilization of microorganisms to transform organic and inorganic compounds. The filamentous yeast Trichosporon cutaneum strain R57, immobilized and free cells was cultivated as batch culture on a liquid medium in the presence of various concentrations of cadmium and copper ions. The simultaneous uptake and accumulation of Cd2+ and Cu2+ ions by Tr. cutaneum cells depending on the initial concentration of Cd2+ and Cu2+ in the medium were studied. The potential use of the free and immobilized cells of Trichosporon cutaneum to remove cadmium and copper ions, from aqueous solutions was evaluated. Two important physicochemical aspects for the evaluation of the sorption process as a unit operation are the equilibrium of sorption and the kinetics. The Cd2+ and Cu2+ ions biosorption capacities of all tested adsorbent were presented as a function of the initial concentration of metal ions within the aqueous biosorption medium. The individual, as well as bicomponent sorption kinetics of copper and cadmium ions by immobilised cells of Trichosporon cutaneum R57 is presented. A second order kinetic model obtains kinetic parameters for the copper and cadmium ions

Interactions of the Neurotoxin Vipoxin in Solution Studied by Dynamic Light Scattering

AbstractThe neurotoxin vipoxin is the lethal component of the venom of Vipera ammodytes meridionalis. It is a heterodimer of a basic toxic His-48 phospholipase A2 (PLA2) and an acidic nontoxic Gln-48 PLA2. The shape of the neurotoxin and its separated components in solution as well as their interactions with calcium, the brain phospholipid phosphatidylcholine, and two inhibitors, elaidoylamide and vitamin E, were investigated by dynamic light scattering. Calcium binding is connected with a conformational change in vipoxin observed as a change of the hydrodynamic shape from oblate ellipsoid to a shape closer to a sphere. The Ca2+-bound form of vipoxin, which is catalytically active, is more compact and symmetric than the calcium-free heterodimer. Similar changes were observed as a result of the Ca2+-binding to the two separated subunits. In the presence of aggregated phosphatidylcholine, the neurotoxic complex dissociates to subunits. It is supposed that only the toxic component binds to the substrate, and the other subunit, which plays a chaperone function, remains in solution. The inhibition of vipoxin with the synthetic inhibitor elaidoylamide and the natural compound vitamin E changes the shape of the toxin from oblate to prolate ellipsoid. The inhibited toxin is more asymmetric in comparison to the native one. Similar, but not so pronounced, effects were observed after the inhibition of the monomeric and homodimeric forms of the toxic His-48 PLA2. Circular dichroism measurements in the presence of urea, methylurea, and ethylurea indicate a strong hydrophobic stabilization of the neurotoxin. Hydrophobic interactions stabilize not only the folded regions but also the regions of intersubunit contacts

Haberlea rhodopensis alcohol extract normalizes stress-responsive transcription of the human TP53 gene

The Orpheus flower Haberlea rhodopensis (Friv.) of the family Gesneriaceae can go into anabiosis for long periods in an almost entirely desiccated state. It is an endemic relict from the Balkan Peninsula. Alcohol extracts from H. rhodopensis contain many biologically active substances with potent antioxidant, antigenotoxic, radioprotective, revitalizing and antiaging capabilities. However, regulating the gene networks responsible for these activities is vastly unknown. This study explores the cellular mechanisms underlying the protective effect of H. rhodopensis extracts (HRE). HeLa cells (human cervix epithelial carcinoma, HeLa ATCC® CCL-2™) were used as a model. We examined the changes in catalase activity and TP53 mRNA level shortly after oxidative (H2O2) and ionizing radiation (IR) induced stress with and without pre-incubation with HRE extracts. The dynamics in the activity of catalase, a main cellular antioxidant enzyme, and the expression of the stress-responsive gene TP53 were investigated by UV spectrophotometric assay and RT-qPCR, respectively. Under the applied stress conditions, H2O2 treatment and gamma radiation, catalase activity increased. This was a sign of induced ROS generation. In the first hours after treatment, the two stressors led to opposite changes in the levels of TP53 gene expression, which were alleviated by pre-incubation with HRE in a concentration-dependent manner. The broad biological activities of the studied extract, taking into account our results, show that ability of HRE to reduce the effect of stress is achieved through complex molecular mechanisms aimed at preserving cellular homeostasis. Mechanisms include the normalization of antioxidant enzyme activity such as catalase and the activity of TP53, one of the genes responsive to stress, by up or down-regulation

Proteome analysis of snake venom toxins: pharmacological insights

Snake venoms are an extremely rich source of pharmacologically active proteins with a considerable clinical and medical potential. To date, this potential has not been fully explored, mainly because of our incomplete knowledge of the venom proteome and the pharmacological properties of its components, in particular those devoid of enzymatic activity. This review summarizes the latest achievements in the determination of snake venom proteome, based primarily on the development of new strategies and techniques. Detailed knowledge of the venom toxin composition and biological properties of the protein constituents should provide the scaffold for the design of new more effective drugs for the treatment of the hemostatic system and heart disorders, inflammation, cancer and consequences of snake bites, as well as new tools for clinical diagnostic and assays of hemostatic parameters

Bioactivity of PEGylated Graphene Oxide Nanoparticles Combined with Near-Infrared Laser Irradiation Studied in Colorectal Carcinoma Cells

Central focus in modern anticancer nanosystems is given to certain types of nanomaterials such as graphene oxide (GO). Its functionalization with polyethylene glycol (PEG) demonstrates high delivery efficiency and controllable release of proteins, bioimaging agents, chemotherapeutics and anticancer drugs. GO–PEG has a good biological safety profile, exhibits high NIR absorbance and capacity in photothermal treatment. To investigate the bioactivity of PEGylated GO NPs in combination with NIR irradiation on colorectal cancer cells we conducted experiments that aim to reveal the molecular mechanisms of action of this nanocarrier, combined with near-infrared light (NIR) on the high invasive Colon26 and the low invasive HT29 colon cancer cell lines. During reaching cancer cells the phototoxicity of GO–PEG is modulated by NIR laser irradiation. We observed that PEGylation of GO nanoparticles has well-pronounced biocompatibility toward colorectal carcinoma cells, besides their different malignant potential and treatment times. This biocompatibility is potentiated when GO–PEG treatment is combined with NIR irradiation, especially for cells cultured and treated for 24 h. The tested bioactivity of GO–PEG in combination with NIR irradiation induced little to no damages in DNA and did not influence the mitochondrial activity. Our findings demonstrate the potential of GO–PEG-based photoactivity as a nanosystem for colorectal cancer treatment

Three-Dimensional Modelling of Honeybee Venom Allergenic Proteases: Relation to Allergenicity

Api SI and Api SIT are serine proteases of the honeybee venom containing allergenic determinants. Each protease consists of two structural modules: an N-terminal CUB (Api SI) or a clip domain (Api SII) and a C-terminal serine protease-like (SPL) domain. Both domains are connected with a linker peptide. The knowledge about the structure and function of Api SI and Api SII is limited mainly to their amino acid sequences. We constructed 3-D models of the two proteases using their amino acid sequences and crystallographic coordinates of related proteins. The models of the SPL domains were built using the structure of the prophenoloxidase-activating factor (PPAF)-II as a template. For modelling of the Api SI CUB domain the coordinates of porcine spermadhesin PSP-I were used. The models revealed the catalytic and substrate-binding sites and the negatively charged residue responsible for the trypsin-like activity. IgE-binding and antigenic sites in the two allergens were predicted using the models and programs based on the structure of known epitopes. Api SI and Api SII show structural and functional similarity to the members of the PPAF-II family. Most probably, they are part of the defence system of Apis mellifera.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Isolation, crystallization and preliminary X-ray diffraction analysis of l-amino-acid oxidase from Vipera ammodytes ammodytes venom

A novel l-amino-acid oxidase was isolated from V. ammodytes ammodytes venom and crystallized. The solution conditions under which the protein sample was monodisperse were optimized using dynamic light scattering prior to crystallization. Preliminary diffraction data were collected to 2.6 Å resolution

The Photobiomodulation of MAO-A Affects the Contractile Activity of Smooth Muscle Gastric Tissues

Nowadays, the utilized electromagnetic radiation (ER) in modalities such as photobiomodulation (PBM) finds broader applications in medical practice due to the promising results suggested by numerous reports. To date, the published data do not allow for the in-depth elucidation of the molecular mechanisms through which ER impacts the human organism. Furthermore, there is a total lack of evidence justifying the relation between the enzymatic activity of monoamine oxidase A (MAO-A) and the effect of 5-hydroxytryptamine (5-HT) on the spontaneous contractile activity of smooth muscle gastric tissues exposed to various light sources. We found that exposure of these tissues to lamps, emitting light with wavelengths of 254 nm and 350 nm, lasers, emitting light with 532 nm and 808 nm, and light-emitting diodes (LEDs) with ER at a wavelength of 660 nm, increased the 5-HT effect on the contractility. On the other hand, LEDs at 365 nm and 470 nm reduced it. The analysis of MAO-A enzymatic activity after exposure to the employed light emitters endorsed these findings. Furthermore, MAOA gene expression studies confirmed the possibility of its optogenetic regulation. Therefore, we concluded that the utilized emitters could alternate the functions of significant neuromediators by modulating the activity and gene transcription levels of enzymes that degrade them. Our investigations will help to disclose the selective conditions upon which PBM can effectively treat gastrointestinal and neurological disorders