The variant rpoS allele of S. enteritidis strain 27655R does not affect virulence in a chick model nor constitutive curliation but does generate a cold-sensitive phenotype

Adherence of pathogenic Escherichia coli and Salmonella spp. to host cells is in part mediated by curli fimbriae which, along with other virulence determinants, are positively regulated by RpoS. Interested in the role and regulation of curli (SEF17) fimbriae of Salmonella enteritidis in poultry infection, we tested the virulence of naturally occurring S. enteritidis PT4 strains 27655R and 27655S which displayed constitutive and null expression of curli (SEF17) fimbriae, respectively, in a chick invasion assay and analysed their rpoS alleles. Both strains were shown to be equally invasive and as invasive as a wild-type phage type 4 strain and an isogenic derivative defective for the elaboration of curli. We showed that the rpoS allele of 27655S was intact even though this strain was non-curliated and we confirmed that a S. enteritidis rpoS::strr null mutant was unable to express curli, as anticipated. Strain 27655R, constitutively curliated, possessed a frameshift mutation at position 697 of the rpoS coding sequence which resulted in a truncated product and remained curliated even when transduced to rpoS::strr. Additionally, rpoS mutants are known to be cold-sensitive, a phenotype confirmed for strain 27655R. Collectively, these data indicated that curliation was not a significant factor for pathogenesis of S. enteritidis in this model and that curliation of strains 27655R and 27655S was independent of RpoS. Significantly, strain 27655R possessed a defective rpoS allele and remained virulent. Here was evidence that supported the concept that different naturally occurring rpoS alleles may generate varying virulence phenotypic traits.

NMR spectroscopy in the presence of ultrasound and other perturbations

The work described in this thesis has been concerned with exploring the potential uses of ultrasound in Nuclear Magnetic Resonance (NMR) spectroscopy, The NMR spectra of liquids provide detailed structural information that may be deduced from the chemical shifts and spin-spin coupling, that are evident in the narrow resonances, arising from some of the nuclear broadening interactions being reduced to zero. In the solid state, all of the nuclear broadening interactions are present and broad lines in the NMR spectrum are observed. Current techniques employed to reduce the line widths in solids are based on coherent averaging techniques such as MAS NMR1,2 which can remove first order interactions. Recently DOR3 and DAS4 have become available to remove higher order interactions. SINNMR (Sonically Induced Narrowing of the NMR spectra of solids) has been reported by Homer et al5 and developed by Homer and Howard6 to reduce the line widths of solids. The basis of their work is the proposal that a colloidal suspension of solid particles can be made to move like large molecules by using ultrasonic agitation. The advantage of the technique is that the particles move incoherently removing all of the nuclear interactions responsible for broad lines. This thesis describes work on the extension of SINNMR by showing that the line width of 27AI and 11B for the glass Na20/B203/AI203 can be reduced by placing solid particles in a colloidal suspension. Further line width reduction is possible by applying ultrasound, at 2 MHz, of sufficient intensity. It is proposed that a cavitation field is responsible for imparting sufficient rotational motion to the solid particles to partially average the nuclear interactions responsible for broad lines. Rapid stirring of the colloidal suspension generates turbulent flow, however, the motion is insufficient to narrow the line widths for 27AI in the glass. Investigations of sonochemical reactions for in situ rate measurements by NMR have been made. 8y using the Weissler reaction7, it has been shown that ultrasonic cavitation is possible up to 10MHz. Preliminary studies have been carried out into the rate of ultrasonic polymerisation of methylmethacrylate by NMR. Long range order in liquid crystals can imposed when they are aligned in the presence a magnetic field. The degree of alignment can be monitored by NMR using, for example a deuterated solute added to the liquid crystal8. Ultrasonic streaming can then be employed to deflect the directors of the liquid crystal from their equilibrium position, resulting in a change In the NMR spectrum. The angle of deflection has been found for the thermotropic liquid crystal (I35) to be ca, 35° and for the lyotropic (ZLI-1167) to be ca, 20°, Mechanical stirring can used to re- orientate the liquid crystal but was found to give a smaller deflection, In a separate study, that did not use ultrasound, it has been found that the signal to noise ratio of 13C NMR signals can be enhanced by rapidly stirring a Iiquid. Accelerating the diffusion of nuclei out of the coil region enables M0 to be re-established more rapidly than the normal relaxation process. This allows the pulse repetition rate to be reduced without saturating the spin system. The influence of varying the relaxation delay, acquisition time and inter-pulse delay have been studied and parameters optimised. By studying cholesterol the technique was found to be most effective for nuclei with long relaxation times, such as quaternary carbon sites. Key Worde: NMR, Ulf.rasciund, 1,.lqi.fi!:l cryllltalt!h SCll1C1otlemlstryl I!r1hano~d algnflllf

Studies on the mechanism of action on antitumour imidazotetrazinones

The imidazotetrazinones are clinically active antitumour agents, temozolomide currently proving successful in the treatment of melanomas and gliomas. The exact nature of the biological processes underlying response are as yet unclear.This thesis attempts to identify the cellular targets important to the cytotoxicity of imidazotetrazinones, to elucidate the pathways by which this damage leads to cell death, and to identify mechanisms by which tumour cells may circumvent this action. The levels of the DNA repair enzymes O6-alkylguanine-DNA-alkyltransferase (O6-AGAT) and 3-methyladenine-DNA-glycosylase (3MAG) have been examined in a range of murine and human cell lines with differential sensitivity to temozolomide. All the cell lines were proficient in 3MAG despite there being 40-fold difference in sensitivity to temozolomide. This suggests that while 3-methyladenine is a major product of temozolomide alkylation of DNA it is unlikely to be a cytotoxic lesion. In contrast, there was a 20-fold variation in O6-AGAT levels and the concentration of this repair enzyme correlated with variations in cytotoxicity. Furthermore, depletion of this enzyme in a resistant, O6-AGAT proficient cell line (Raji), by pre-treatment with the free base O6-methylguanine resulted in 54% sensitisation to the effects of temozolomide. These observations have been extended to 3 glioma cell lines; results that support the view that the cytotoxicity of temozolomide is related to alkylation at the O6-position of guanine and that resistance to this drug is determined by efficient repair of this lesion. It is clear, however, the other factors may influence tumour response since temozolomide showed little differential activity towards 3 established solid murine tumours in vivo, despite different tumour O6-AGAT levels. Unlike mitozolomide, temozolomide is incapable of cross-linking DNA and a mechanism by which O6-methylguanine may exert lethality is unclear. The cytotoxicity of the methyl group may be due to its disruption of DNA-protein interactions, or alternatively cell death may not be a direct result of the alkyl group itself, but manifested by DNA single-strand breaks. Enhanced alkaline elution rates were found for the DNA of Raji cells treated with temozolomide following alkyltransferase depletion, suggesting a relationship between O6-methylguanine and the induction single-strand breaks. Such breaks can activate poly(ADP-ribose) synthetase (ADPRT) an enzyme capable of rapid and lethal depletion of cellular NAD levels. However, at concentrations of temozolomlde relevant in vivo little change in adenine nucleotides was detected in cell lines, although this enzyme would appear important in modulating DNA repair since inhibition of ADPRT potentiated temozolomide cytotoxicity in Raji cells but not O6-AGAT deficient GM892A cells. Cell lines have been reported that are O6-AGAT deficient yet resistant to methylating agents. Thus, resistance to temozolomide may arise not only by removal of the methyl group from the O6-position of guanine, but also from another mechanism involving caffeine-sensitive post-replication repair or mismatch repair activity. A modification of the standard Maxam Gilbert sequencing technique was used to determine the sequence specificity of guanine-N7 alkylation. Temozolomide preferentially alkylated runs of guanines with the intensity of reaction increasing with the number of adjacent guanines in the DNA sequence. Comparable results were obtained with a polymerase-stop assay, although neither technique elucidates the sequence specificity of O6-guanine alkylation. The importance of such specificity to cytotoxicity is uncertain, although guanine-rich sequences are common to the promoter regions of oncogenes. Expression of a plasmid reporter gene under the control of the Ha-ras proto~oncogene promoter was inhibited by alkylation with temozolomide when transfected into cancer cell lines, However, this inhibition did not appear to be related to O6~guanine alkylation and therefore would seem unimportant to the chemotherapeutic activity of temozolomide.

Translation as an ideological interface : English translations of Hitler's Mein Kampf

The present thesis is located within the framework of descriptive translation studies and critical discourse analysis. Modern translation studies have increasingly taken into account the complexities of power relations and ideological management involved in the production of translations. Paradoxically, persuasive political discourse has not been much touched upon, except for studies following functional (e.g. Schäffner 2002) or systemic-linguistic approaches (e.g. Calzada Pérez 2001). By taking 11 English translations of Hitler’s Mein Kampf as prime examples, the thesis aims to contribute to a better understanding of the translation of politically sensitive texts. Actors involved in political discourse are usually more concerned with the emotional appeal of their message than they are with its factual content. When such political discourse becomes the locus of translation, it may equally be crafted rhetorically, being used as a tool to persuade. It is thus the purpose of the thesis to describe subtle ‘persuasion strategies’ in institutionally translated political discourse. The subject of the analysis is an illustrative corpus of four full-text translations, two abridgements, and five extract translations of Mein Kampf. Methodologically, the thesis pursues a top-down approach. It begins by delineating sociocultural and situative-agentive conditions as causal factors impinging on the individual translations. Such interactive and interpersonal factors determined textual choices. The overall textual analysis consists of an interrelated corpus-driven and corpus-based approach. It demonstrates how corpus software can be fruitfully harnessed to discern ‘ideological significations’ in the translated texts. Altogether, the thesis investigates how translational decision-makers attempted to position the source text author and his narrative in line with overall rhetorical purposes.

A compact, portable and low cost generic interrogation strain sensor system using an embedded VCSEL, detector and fibre Bragg grating

We present a compact, portable and low cost generic interrogation strain sensor system using a fibre Bragg grating configured in transmission mode with a vertical-cavity surface-emitting laser (VCSEL) light source and a GaAs photodetector embedded in a polymer skin. The photocurrent value is read and stored by a microcontroller. In addition, the photocurrent data is sent via Bluetooth to a computer or tablet device that can present the live data in a real time graph. With a matched grating and VCSEL, the system is able to automatically scan and lock the VCSEL to the most sensitive edge of the grating. Commercially available VCSEL and photodetector chips are thinned down to 20 µm and integrated in an ultra-thin flexible optical foil using several thin film deposition steps. A dedicated micro mirror plug is fabricated to couple the driving optoelectronics to the fibre sensors. The resulting optoelectronic package can be embedded in a thin, planar sensing sheet and the host material for this sheet is a flexible and stretchable polymer. The result is a fully embedded fibre sensing system - a photonic skin. Further investigations are currently being carried out to determine the stability and robustness of the embedded optoelectronic components. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission

Changes at the BCLA

As we welcome 2014 we say goodbye to 2013 and I must start with an apology to authors who have submitted papers to CLAE and seen a delay in either the review process or the hard copy publication of their proofed article. The delays were caused by a major hike in the number of submissions to the journal in 2012 that increased further in 2013. In the 12 months leading to the end of October 2011 we had 94 new paper submissions, and for the same period to the end of 2012 the journal had 116 new papers. In 2012 we were awarded an impact factor for the first time and following that the next 12 month period to the end of October 2013 saw a massive increase in submissions with 171 new manuscripts being submitted. This is nearly twice as many papers as 2 years ago and 3 times as many as when I took over as Editor-in-Chief. In addition to this the UK academics will know that 2014 is a REF year (Research Excellence Framework) where universities are judged on their research and one of the major components of this measure remains to be published papers so there is a push to publishing before the REF deadline for counting. The rejection rate at CLAE has gone up too and currently is around 50% (more than double the rejection rate when I took over as Editor-in-Chief). At CLAE the number of pages that we publish each year has remained the same since 2007. When compiling issue 1 for 2014 I chose the papers to be included from the papers that were proofed and ready to go and there were around 200 proofed pages ready, which is enough to fill 3½ issues! At present Elsevier and the BCLA are preparing to increase the number the pages published per issue so that we can clear some of this backlog and remain up to date with the papers published in CLAE. I should add that on line publishing of papers is still available and there may have been review delays but there are no publishing online so authors can still get an epub on line final version of their paper with a DOI (digital object identifier) number enabling the paper to be cited. There are two awards that were made in 2013 that I would like to make special mention of. One was for my good friend Jan Bergmanson, who was awarded an honorary life fellowship of the College of Optometrists. Jan has served on the editorial board of CLAE for many years and in 2013 also celebrated 30 years of his annual ‘Texan Corneal and contact lens meeting’. The other award I wish to mention is Judith Morris, who was the BCLA Gold Medal Award winner in 2013. Judith has had many roles in her career and worked at Moorfields Eye Hospital, the Institute of Optometry and currently at City University. She has been the Europe Middle East and Africa President of IACLE (International Association of Contact Lens Educators) for many years and I think I am correct in saying that Judith is the only person who was President of both the BCLA (1983) and a few years later she was the President College of Optometrists (1989). Judith was also instrumental in introducing Vivien Freeman to the BCLA as they had been friends and Judith suggested that Vivien apply for an administrative job at the BCLA. Fast forward 29 years and in December 2013 Vivien stepped down as Secretary General of the BCLA. I would like to offer my own personal thanks to Vivien for her support of CLAE and of me over the years. The BCLA will not be the same and I wish you well in your future plans. But 2014 brings in a new position to the BCLA – Cheryl Donnelly has been given the new role of Chief Executive Officer. Cheryl was President of the BCLA in 2000 and has previously served on council. I look forward to working with Cheryl and envisage a bright future for the BCLA and CLAE. In this issue we have some great papers including some from authors who have not published with CLAE before. There is a nice paper on contact lens compliance in Nepal which brings home some familiar messages from an emerging market. A paper on how corneal curvature is affected by the use of hydrogel lenses is useful when advising patients how long they should leave their contact lenses out for to avoid seeing changes in refraction or curvature. This is useful information when refracting these patients or pre-laser surgery. There is a useful paper offering tips on fitting bitoric gas permeable lenses post corneal graft and a paper detailing surgery to implant piggyback multifocal intraocular lenses. One fact that I noted from the selection of papers in the current issue is where they were from. In this issue none of the corresponding authors are from the United Kingdom. There are two papers each from the United States, Spain and Iran, and one each from the Netherlands, Ireland, Republic of Korea, Australia and Hong Kong. This is an obvious reflection of the widening interest in CLAE and the BCLA and indicates the new research groups emerging in the field.

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission. © 2013 Optical Society of America.

A compact, portable and low cost generic interrogation strain sensor system using an embedded VCSEL, detector and fibre Bragg grating

We present a compact, portable and low cost generic interrogation strain sensor system using a fibre Bragg grating configured in transmission mode with a vertical-cavity surface-emitting laser (VCSEL) light source and a GaAs photodetector embedded in a polymer skin. The photocurrent value is read and stored by a microcontroller. In addition, the photocurrent data is sent via Bluetooth to a computer or tablet device that can present the live data in a real time graph. With a matched grating and VCSEL, the system is able to automatically scan and lock the VCSEL to the most sensitive edge of the grating. Commercially available VCSEL and photodetector chips are thinned down to 20 µm and integrated in an ultra-thin flexible optical foil using several thin film deposition steps. A dedicated micro mirror plug is fabricated to couple the driving optoelectronics to the fibre sensors. The resulting optoelectronic package can be embedded in a thin, planar sensing sheet and the host material for this sheet is a flexible and stretchable polymer. The result is a fully embedded fibre sensing system - a photonic skin. Further investigations are currently being carried out to determine the stability and robustness of the embedded optoelectronic components. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

The redoxomics of PTEN: walking a fine line between damage and signaling:mass spectrometry-based approaches to study the effect of oxidation on PTEN function, structure, and protein-protein interactions

The research described in this PhD thesis focuses on proteomics approaches to study the effect of oxidation on the modification status and protein-protein interactions of PTEN, a redox-sensitive phosphatase involved in a number of cellular processes including metabolism, apoptosis, cell proliferation, and survival. While direct evidence of a redox regulation of PTEN and its downstream signaling has been reported, the effect of cellular oxidative stress or direct PTEN oxidation on PTEN structure and interactome is still poorly defined. In a first study, GST-tagged PTEN was directly oxidized over a range of hypochlorous acid (HOCl) concentration, assayed for phosphatase activity, and oxidative post-translational modifications (oxPTMs) were quantified using LC-MS/MS-based label-free methods. In a second study, GSTtagged PTEN was prepared in a reduced and reversibly H2O2-oxidized form, immobilized on a resin support and incubated with HCT116 cell lysate to capture PTEN interacting proteins, which were analyzed by LC-MS/MS and comparatively quantified using label-free methods. In parallel experiments, HCT116 cells transfected with a GFP-tagged PTEN were treated with H2O2 and PTENinteracting proteins immunoprecipitated using standard methods. Several high abundance HOCl-induced oxPTMs were mapped, including those taking place at amino acids known to be important for PTEN phosphatase activity and protein-protein interactions, such as Met35, Tyr155, Tyr240 and Tyr315. A PTEN redox interactome was also characterized, which identified a number of PTEN-interacting proteins that vary with the reversible inactivation of PTEN caused by H2O2 oxidation. These included new PTEN interactors as well as the redox proteins peroxiredoxin-1 (Prdx1) and thioredoxin (Trx), which are known to be involved in the recycling of PTEN active site following H2O2-induced reversible inactivation. The results suggest that the oxidative modification of PTEN causes functional alterations in PTEN structure and interactome, with fundamental implications for the PTEN signaling role in many cellular processes, such as those involved in the pathophysiology of disease and ageing.

Space division multiple access for wireless sensor networks

This dissertation proposed a self-organizing medium access control protocol (MAC) for wireless sensor networks (WSNs). The proposed MAC protocol, space division multiple access (SDMA), relies on sensor node position information and provides sensor nodes access to the wireless channel based on their spatial locations. SDMA divides a geographical area into space divisions, where there is one-to-one map between the space divisions and the time slots. Therefore, the MAC protocol requirement is the sensor node information of its position and a prior knowledge of the one-to-one mapping function. The scheme is scalable, self-maintaining, and self-starting. It provides collision-free access to the wireless channel for the sensor nodes thereby, guarantees delay-bounded communication in real time for delay sensitive applications. This work was divided into two parts: the first part involved the design of the mapping function to map the space divisions to the time slots. The mapping function is based on a uniform Latin square. A Uniform Latin square of order k = m 2 is an k x k square matrix that consists of k symbols from 0 to k-1 such that no symbol appears more than once in any row, in any column, or in any m x in area of main subsquares. The uniqueness of each symbol in the main subsquares presents very attractive characteristic in applying a uniform Latin square to time slot allocation problem in WSNs. The second part of this research involved designing a GPS free positioning system for position information. The system is called time and power based localization scheme (TPLS). TPLS is based on time difference of arrival (TDoA) and received signal strength (RSS) using radio frequency and ultrasonic signals to measure and detect the range differences from a sensor node to three anchor nodes. TPLS requires low computation overhead and no time synchronization, as the location estimation algorithm involved only a simple algebraic operation.

Hybrid approaches to estimating freeway travel times using point traffic detector data

The accurate and reliable estimation of travel time based on point detector data is needed to support Intelligent Transportation System (ITS) applications. It has been found that the quality of travel time estimation is a function of the method used in the estimation and varies for different traffic conditions. In this study, two hybrid on-line travel time estimation models, and their corresponding off-line methods, were developed to achieve better estimation performance under various traffic conditions, including recurrent congestion and incidents. The first model combines the Mid-Point method, which is a speed-based method, with a traffic flow-based method. The second model integrates two speed-based methods: the Mid-Point method and the Minimum Speed method. In both models, the switch between travel time estimation methods is based on the congestion level and queue status automatically identified by clustering analysis. During incident conditions with rapidly changing queue lengths, shock wave analysis-based refinements are applied for on-line estimation to capture the fast queue propagation and recovery. Travel time estimates obtained from existing speed-based methods, traffic flow-based methods, and the models developed were tested using both simulation and real-world data. The results indicate that all tested methods performed at an acceptable level during periods of low congestion. However, their performances vary with an increase in congestion. Comparisons with other estimation methods also show that the developed hybrid models perform well in all cases. Further comparisons between the on-line and off-line travel time estimation methods reveal that off-line methods perform significantly better only during fast-changing congested conditions, such as during incidents. The impacts of major influential factors on the performance of travel time estimation, including data preprocessing procedures, detector errors, detector spacing, frequency of travel time updates to traveler information devices, travel time link length, and posted travel time range, were investigated in this study. The results show that these factors have more significant impacts on the estimation accuracy and reliability under congested conditions than during uncongested conditions. For the incident conditions, the estimation quality improves with the use of a short rolling period for data smoothing, more accurate detector data, and frequent travel time updates.

Toward understanding the study experience of culturally sensitive graduate students in *American distance education programs

The purpose of this research was to gain an understanding of the study experience of non-American graduate students living outside of the United States and formally engaged in graduate studies in an American Distance Education (DE) Program. These students have been labeled “culturally sensitive.” The nature of this study dictated a qualitative case study methodology using in-depth interviews to collect the data and the hermeneutic approach to understanding and description. This study aims at generating questions and hypotheses that will lead to further investigations that explore the need for cultural and contextual sensitivity in order to provide more equitable and accessible higher education for all. ^ The study attempted to answer the question: What is the study experience of “culturally sensitive” graduate students in American DE Programs? The underlying issue in this study is whether education designed and provided by educators of different socio-cultural backgrounds from that of the students could be content relevant and instructionally appropriate, resulting in educational enhancement and/or prepare students to function adequately in their own communities. ^ Participants in this study (n = 12) were engaged in Master's level (n = 2) and Doctoral level (n = 10) DE programs at American Universities, and were interviewed by E-mail, face-to-face, or using a combination of the two. Data analysis compared interviews and highlighted repetitive patterns. Interview data was triangulated with recent related literature and data from document reviews of archived E-mail conversations between students and their professors. The patterns that emerged were coded and categorized according to generative themes. The following themes were identified in order to analyze the data and confirmed through participant check-back: program benefits, communication, technology, culture and methodology, and reflectivity. ^ Major findings in this study indicate that culture plays an important role in cross-cultural encounters for students in American DE programs vis-à-vis student perceptions as to whether their study needs were being met. Most notably, it was found that the coupling of cultural perceptual differences with transactional distance created a potential barrier to communication that could affect short-term success in American DE programs. To overcome this barrier, students cited good communication as essential in meeting student's needs, especially those communications that were supportive and full of detail and context and from a primary source (ex. directly from the professor). Evaluation was a particularly sensitive issue, especially when students were unaware of their professor's cultural and contextual intricacies and therefore were uncertain about expectations and intended meaning. CSGS were aware of their position and the American rather than global context in which they were participating. Students appear to have developed “extended identities”, meaning that they acculturated in varying degrees in order to be successful in their program but that their local cultural identity was not compromised in any way. For participants from Venezuela access to higher DE has been a limiting factor to participation, due to the high cost of technology and telephone lines for communication. ^

Desenvolvimento e validação de testes de fluxo lateral para a detecção de cultivares geneticamente modificados e de aflatoxinas em produtos agrícolas

The expansion of cultivated areas with genetically modified crops (GM) is a worldwide phenomenon, stimulating regulatory authorities to implement strict procedures to monitor and verify the presence of GM varieties in agricultural crops. With the constant growing of plant cultivating areas all over the world, consumption of aflatoxin-contaminated food also increased. Aflatoxins correspond to a class of highly toxic contaminants found in agricultural products that can have harmful effects on human and animal health. Therefore, the safety and quality evaluation of agricultural products are important issues for consumers. Lateral flow tests (strip tests) is a promising method for the detection both proteins expressed in GM crops and aflatoxins-contaminated food samples. The advantages of this technique include its simplicity, rapidity and cost-effective when compared to the conventional methods. In this study, two novel and sensitive strip tests assay were developed for the identification of: (i) Cry1Ac and Cry8Ka5 proteins expressed in GM cotton crops and; (ii) aflatoxins from agricultural products. The first strip test was developed using a sandwhich format, while the second one was developed using a competitive format. Gold colloidal nanoparticles were used as detector reagent when coated with monoclonal antibodies. An anti-species specific antibody was sprayed at the nitrocellulose membrane to be used as a control line. To validate the first strip test, GM (Bollgard I® e Planta 50- EMBRAPA) and non-GM cotton leaf (Cooker 312) were used. The results showed that the strip containing antibodies for the identification of Cry1Ac and Cry8Ka5 proteins was capable of correctly distinguishing between GM samples (positive result) and non-GM samples (negative result), in a high sensitivity manner. To validate the second strip test, artificially contaminated soybean with Aspergillus flavus (aflatoxin-producing fungus) was employed. Food samples, such as milk and soybean, were also evaluated for the presence of aflatoxins. The strip test was capable to distinguish between samples with and without aflatoxins samples, at a sensitivity concentration of 0,5 μg/Kg. Therefore, these results suggest that the strip tests developed in this study can be a potential tool as a rapid and cost-effective method for detection of insect resistant GM crops expressing Cry1Ac and Cry8Ka5 and aflatoxins from food samples.

Desenvolvimento e validação de testes de fluxo lateral para a detecção de cultivares geneticamente modificados e de aflatoxinas em produtos agrícolas

The expansion of cultivated areas with genetically modified crops (GM) is a worldwide phenomenon, stimulating regulatory authorities to implement strict procedures to monitor and verify the presence of GM varieties in agricultural crops. With the constant growing of plant cultivating areas all over the world, consumption of aflatoxin-contaminated food also increased. Aflatoxins correspond to a class of highly toxic contaminants found in agricultural products that can have harmful effects on human and animal health. Therefore, the safety and quality evaluation of agricultural products are important issues for consumers. Lateral flow tests (strip tests) is a promising method for the detection both proteins expressed in GM crops and aflatoxins-contaminated food samples. The advantages of this technique include its simplicity, rapidity and cost-effective when compared to the conventional methods. In this study, two novel and sensitive strip tests assay were developed for the identification of: (i) Cry1Ac and Cry8Ka5 proteins expressed in GM cotton crops and; (ii) aflatoxins from agricultural products. The first strip test was developed using a sandwhich format, while the second one was developed using a competitive format. Gold colloidal nanoparticles were used as detector reagent when coated with monoclonal antibodies. An anti-species specific antibody was sprayed at the nitrocellulose membrane to be used as a control line. To validate the first strip test, GM (Bollgard I® e Planta 50- EMBRAPA) and non-GM cotton leaf (Cooker 312) were used. The results showed that the strip containing antibodies for the identification of Cry1Ac and Cry8Ka5 proteins was capable of correctly distinguishing between GM samples (positive result) and non-GM samples (negative result), in a high sensitivity manner. To validate the second strip test, artificially contaminated soybean with Aspergillus flavus (aflatoxin-producing fungus) was employed. Food samples, such as milk and soybean, were also evaluated for the presence of aflatoxins. The strip test was capable to distinguish between samples with and without aflatoxins samples, at a sensitivity concentration of 0,5 μg/Kg. Therefore, these results suggest that the strip tests developed in this study can be a potential tool as a rapid and cost-effective method for detection of insect resistant GM crops expressing Cry1Ac and Cry8Ka5 and aflatoxins from food samples.