Unveiling the binding and orientation of the antimicrobial peptide Plantaricin 149 in zwitterionic and negatively charged membranes

Antimicrobial peptides are a large group of natural compounds which present promising properties for the pharmaceutical and food industries, such as broad-spectrum activity, potential for use as natural preservatives, and reduced propensity for development of bacterial resistance. Plantaricin 149 (Pln149), isolated from Lactobacillus plantarum NRIC 149, is a peptide with the ability to inhibit bacteria from the Listeria and Staphylococcus genera, which is capable of promoting inhibition and disruption of yeast cells. In this study, the interactions of Pln149 with model membranes composed of zwitterionic and/or anionic phospholipids were investigated using a range of biophysical techniques, including isothermal titration calorimetry, surface tension measurements, synchrotron radiation circular dichroism spectroscopy, oriented circular dichroism spectroscopy, and optical microscopy, in order to elucidate their mode of interactions and provide insight into their functional roles. In anionic model membranes, the binding of Pln149 to lipid bilayers is an endothermic process and induces a helical secondary structure in the peptide. The helices bind parallel to the surfaces of lipid bilayers and can promote vesicle disruption, depending on peptide concentration. Although Pln149 has relatively low affinity for zwitterionic liposomes, it is able to adsorb at their lipid interfaces, disturbing the lipid packing, assuming a similar parallel helix structure with a surface-bound orientation, and promoting an increase in the membrane surface area. Such findings can explain the intriguing inhibitory action of Pln149 in yeast cells whose cell membranes have a significant zwitterionic lipid composition

E-retailing ethics in Egypt and its effect on customer repurchase intention

The theoretical understanding of online shopping behaviour has received much attention. Less focus has been given to the formation of the ethical issues that result from online shopper interactions with e-retailers. The vast majority of earlier research on this area is conceptual in nature and limited in scope by focusing on consumers’ privacy issues. Therefore, the purpose of this paper is to propose a theoretical model explaining what factors contribute to online retailing ethics and its effect on customer repurchase intention. The data were analysed using variance-based structural equation modelling, employing partial least squares regression. Findings indicate that the five factors of the online retailing ethics (security, privacy, non- deception, fulfilment/reliability, and corporate social responsibility) are strongly predictive of online consumers’ repurchase intention. The results offer important implications for e-retailers and are likely to stimulate further research in the area of e-ethics from the consumers’ perspective

Development and Evaluation of Representative Models to Build Amino Acids and Protein Structures

A set of plastic pieces to represent structures to build amino acids and proteins was developed and named as “Building Amino Acids and Proteins Molecules”. The kit was evaluated, in a first step, by graduate students using specific assessment questionnaire. This step guided the final adjustments of the plastic parts and the evaluation methodology. The last assessment of the kit was performed in a workshop for 256 teachers in the fields of natural sciences from Regional Boards of São Paulo State Department of Education. The data presented refer to the evaluations carried out by Biology and Chemistry high school teachers regarding a ludic activity consisting of the construction of tridimensional models with the kit. The evaluation results show that the material had great acceptance by the community of teachers and can become a valuable tool for teaching about amino acids and proteins structures. Regarding the answers given to the question “Would you use this material to teach this topic in high school? Comment”, 80% of the teachers chose YES and the 58 who justified their answers raised some questions concerning the use of the instructional material proposed, which will be discussed in the present work. This material has been certified and integrated the Guide for MEC Educational Technology 2008

THE USE OF EDUCATIONAL MODELS OF DNA IN CLASSROOM BY TEACHERS OF ELEMENTARY SCHOOL

The importance of the teaching of Biotechnology and Molecular Biology is evidenced by the progress of those areas and it generates a demand in the updating of science and biology teachers. In that sense, a project was proposed inside of the Public Education Program of FAPESP, in partnership with CBME.The goal was evaluate, among other educational tools, the contribution of the plastic models "Building the molecules of the life: DNA and RNA" in the teaching and learning of these concepts. Nine science teachers of public elementary schools had an updating course after which they elaborated a diagnosis questionnaire in order to subsidize the application of the activities in the classroom. The activities were planned seeking contextualize the subject in classroom, taking into account the difficulties detected in the diagnosis questionnaire. A sheet of notes was elaborated, where the teachers could record their observations and thoughts after the application of the activities, as well as their possibilities and the students' difficulties. These registers indicated that the teachers were satisfied with the use of the material, which made possible a deepened study on the content and a greater interest and participation of the students. It also allowed a reflection on their practice, glimpsing new ways to teach

Evaluation of The Virtual Cells Software: a Teaching Tool

Studies show that the use of games and interactive materials  at schools is a good educational strategy, motivating students to create mental  outlines and developing the reasoning and facilitating  the learn- ing. In this context, the Scientific Dissemination Coordination of the Center  for Structural Molecular Biotechnology  (CBME),  developed  a series of educational materials  destined  to the  elementary and high  schools,  universities  and  general  public.   Among  these,  we highlighted  the  Virtual  Cells soft- ware that was developed  with  the  aim of helping  in the  understanding of the  basic concepts  of cell types,  their  structures, organelles  and  specific functions.   Characterized by its  interactive  interface, this  software shows eukaryotes  and prokaryotes cells images, where organelles are shown as dynamic structures. In addition, it presents exercises in another  step that reinforce the comprehension  of Cy- tology.  A speaker  narrates the  resources  offered by the  program  and  the  necessary  steps  for its use. During  the  stage  of development of the  software,  students and  teachers of public and  private  high schools from Sao Carlos  city, Sao Paulo  State,  were invited  to register their  opinions  regarding  the language and content of the software in order to help us in the improvement of it.  After this stage, the Scientific Dissemination Coordination of CBME organized a series of workshops, where 120 individuals evaluated the software (students and teachers  of high school and others undergraduate students). For this evaluation, a questionnaire was elaborated based on the international current literature in the area of sciences teaching  and it was applied  after the interactive section with the software.  The analysis of the results demonstrated that most of the individuals  considered the software of easy handling,  having an accessible language,  supporting the  software  as an education  tool that is capable  to facilitate  the learning  of the fundamental concepts  about the theme.  Other  workshops are programmed to happen with participants from different educational institutions of Sao Carlos  city,  with the goal to broaden our sample

THE HISTORY OF SCIENCE IN THE INTERACTIVE SPACE OF CBME

Considering that since the 1980’s it has a paradigm change, strengtheningthe perception of Science as a human construction and not as "natural truth", newapproaches of teaching emphasizes the importance of the History of Science inthe educational process, also recommended by the Brazilian PCNs. In thiscontext, it is presented the conclusion of the elaboration and evaluation of anillustrated historical panel that is in permanent exposition in the Interactive Spaceof Biotechnology of the CBME. It presents 25 pictures, inserted in a timeline thatselects important events related to cell biology, microbiology and immunology. Thetimeline is initiated in century XVI, with the microbial theory of the illnesses;spontaneous generation and the experiments of Needham and Spallanzani alsoare commented, as well as the production of the first vaccine. Koch, in centuryXIX, is remembered with its postulates and the discovery of some illnessescausative agents. Brazilians’ researchers - Adolfo Lutz, Oswaldo Cruz, Vital Braziland Carlos Chagas – and institutes are presented too. The panel revealed itself asan important source of information, awakening the interest of the visitors for thesubject. The idea was based on presenting Science as a human knowledgeadventure, emphasizing the scientific process in the construction of theknowledge, based on procedures, needs and different interests and values

Antibody recognition of synthetic peptides mimicking immunodominant regions of HIV-1 p24 and p17 proteins Reconocimiento por anticuerpos de péptidos sintéticos que imitan regiones inmunodominantes de las proteínas p24 y p17 de VIH-1

The gag gene of HIV-1 encodes a single open reading frame of 55 kDa that contains three subdomains: the matrix domain (p17), the capsid domain (p24) and the nucleocapsid domain (p15). The p24 and p17 proteins have a predominant a-helical structure and perform important functions throughout thevirallife-cycle. The determination of gag-specific antibodies is important because declining titers of these antibodies herald clinical deterioration.In this work we present the results obtained on immunoreactiviy of synthetic peptides that mimic immunogenic a-helical regions of p24 and p17. The influence on the immunoreactivity of structural modifications in native sequences, including the addition of non immunogenic side chains: AAAC- and -CAAA on both side of minimal epitopes was evaluated in indirect and competitive enzymeimmunoassays. The conformational characteristcs to the peptides were analysed by circular dichroism and these results were correlated with that obtained in the immunoassays. It was shown that the reactivity of peptides mimicking short a-helical regions of p24 and p17 is improved by adding short non immunogenic chains on both N- and C- terminus. These modifications enhanced the immobilization of the peptides onto the solid support and allowed more accesibility to the minimal epitopes byspecific antibodies, in solution.El gen gag del VIH-1 codifica una región de 55kDA que contiene tres subdominios: matriz (p17), cápside (p24) y nucleocápside (p15). Las proteínas p24 y p17 tienen una estructura predominante helicoidal y cumplen un rol importante en el ciclo de vida del virus. En este trabajo presentamos los resultados de inmunorreactividad de péptidos sintéticos que imitan regiones helicoidales de p24 y p17. Utilizando enzimoinmunoensayos se evaluó la influencia de modificaciones en las secuencias nativas sobre la capacidad de reconocimiento de anticuerpos específicos en solución y en fase sólida, incluyendo el agregado de cadenas no inmunogénicas en ambos extremos de los epitopes mínimos. La conformación de los péptidos se determinó por dicroísmo circular y los resultados se correlacionaron con los de inmunorreactividad. Se observó que la capacidad de reconocimiento de anticuerpos por péptidos pequeños que imitan estructuras helicoidales de p24 y p17 mejoró con el agregado de cadenas no inmunogénicas en ambos extremos de los epitopes. Estas modificaciones mejoran la inmovilización sobre las superficies sólidas y permiten una mayor accesibilidad de los anticuerpos a los epitopes mínimos en solución