Viral internet challenges scale in preadolescents: An exploratory study.

In recent years, viral challenges on the Internet have become a very frequent phenomenon. These allude to the actions that are proposed to Internet users to record themselves performing a challenge and disseminate it on different online platforms so that other users will also perform it. Despite its rapid expansion, there is no evidence of any validated assessment tool of this phenomenon. To meet this need, the Viral Internet Challenges Scale (VICH-S) was designed. The main objective of this study was to establish the psychometric properties of this scale, the prevalence of different types of challenges (social, solidary, and dangerous), as well as the single or conjoint performance of these types of challenges using the VICH-S. Furthermore, the construct validity of the scale was tested with these variables: Fear of Missing Out, Loss of Connection (nomophobia), Self-Online, and Emotional Attention Online. Participants were 417 preadolescents (41.2% boys) with age ranging from 10 to 14 years. Exploratory factor analysis of the VICH-S scale revealed the existence of two factors: Challenge Satisfaction and Social Motivation. Convergent validity indicators showed positive and significant correlations between these two dimensions and the Fear of Missing Out, Loss of Connection (nomophobia), Self-Online, and Emotional Attention Online. The most frequent challenges were social challenges (80.3%), followed by solidary (20.6%) and dangerous challenges (7.7%). This study has relevant implications, as the VICH-S presents adequate psychometric properties to evaluate this barely explored and growing phenomenon of viral challenges on the Internet in preadolescence.

Comparison of knowledge, attitudes and hand hygiene behavioral intention in medical and nursing students.

INTRODUCTION: Hand hygiene is crucial to prevent cross infection. Healthcare students are in a prime position to learn hand hygiene skills. The aim of this study was to analyze hand hygiene behavioral intentions of healthcare students before and after contact with the patient and to compare the knowledge of and attitude towards hand hygiene between medical and nursing students. METHODS: In a descriptive survey research design, convenience selection of a sample of medical students (n=657) and nursing students (n=303) was done from modules taught by the Department of Preventive Medicine and Public Health in both Medicine and Nursing undergraduate degrees in four Spanish universities. The hand hygiene Questionnaire, a validated instrument to evaluate behavior, knowledge, and attitudes, was used. RESULTS: A significantly lower percentage of students reported always or almost always carrying out hand hygiene before contact with the patient or invasive procedures in comparison to the percentage complying after contact with secretions or with the patient. Although hand hygiene knowledge appears acceptable, its importance is not sufficiently valued. CONCLUSIONS: There are deficiencies in behavioral intention, knowledge, and attitudes related to hand hygiene in medical and nursing students. Better results are observed among nursing students, especially those who have received specific training.

Mutations in the voltage-gated sodium channel gene associated with deltamethrin resistance in commercially sourced Phytoseiulus persimilis.

The implementation of Integrated Pest Management in current agricultural practice is a convenient and very effective strategy to keep pest populations under control. The use of biological control agents, such as Phytoseiulus persimilis, is key for the success of such an approach. This predatory mite is widely used as it is very effective for controlling Tetranychus urticae, one of the most devastating crop pests. Here, we identify several mutations located in the voltage-gated sodium channel (VGSC) of commercially sourced P. persimilis that correlate with a reduced susceptibility to the pyrethroid deltamethrin. We found that the mites sourced from two different biocontrol product companies have intrinsic genotypic differences that correlate with their phenotype when tested with different concentrations of deltamethrin. Mites from Syngenta Bioline, carrying the mutations M918L and A1536T, were able to survive deltamethrin concentrations of up to 10 ppm, while the mites from Koppert Biological Systems, with the combination M918L, L925V and S1539T, survived treatment with 40 ppm. All of the point mutations identified in the predatory mite samples are located in a particular region of the VGSC, previously proposed as the binding site for this family of pesticides and identified as a 'hot spot' for resistance.

Single and Combined Release of Trichopria drosophilae (Hymenoptera: Diapriidae) to Control Drosophila suzukii (Diptera: Drosophilidae).

To further the use of local parasitoids to control the spotted wing drosophila suzukii (Matsumura) in Mexico, three treatments were implemented by sextuplicate in commercial berry fields of Colima and Jalisco from June 2017 to May 2018: single release of Trichopria drosophilae Perkins (pupal parasitoid), combined release of T. drosophilae + Leptopilina boulardi Barbotin, Carton & Kelner-Pillault (larval parasitoid), and a no release control. Compared with the no release sites, parasitism by T. drosophilae increased 4 and 4.1-fold at the single and combined release sites, respectively, and parasitism of L. boulardi increased 2.8-fold at the sites where it was evaluated. Additionally, it was registered a 50 and 55% reduction of D. suzukii at the sites with single and combined releases, respectively; in other words, supplementing T. drosophilae with L. boulardi provided little benefit compared with the release of T. drosophilae alone. These results indicate that single release of local T. drosophilae is a more cost-effective option to reduce D. suzukii populations, and that such activity can contribute significantly to the phytosanitary management of this invasive pest.

Relationship between cyberbullying and health-related quality of life in a sample of children and adolescents.

PURPOSE: Health-related quality of life (HRQoL) is a well-known construct that refers to a state of complete physical, mental, and social well-being. Its relationship with multiple forms of violence, including bullying, has been widely explored, but this is not the case for cyberbullying. The main objective is to analyze how HRQoL varies depending on the role played in cyberbullying, its temporal stability, and gender and age differences. METHOD: An analytical and longitudinal study was conducted at two temporal moments. At Time 1 (December 2015), 920 Spanish students aged between 11 and 18 years participated (Mage = 13.36, SD = 1.83: 48.9% boys and 51.1% girls). At Time 2 (April 2016), there were 313 participants (Mage 12.81 years, SD = 1.59: 53.4% boys and 46.6% girls). We used the Cyberbullying Test (technological scale) and the Spanish version of the KIDSCREEN-52. RESULTS: Cybervictims and cyberbully-victims present worse scores in all dimensions of the KIDSCREEN-52 (p < .001), compared to cyberbystanders or uninvolved individuals. There are gender differences only in cyberaggression and cyberbystanding. There are significant inverse correlations between all the dimensions of the KIDSCREEN-52 and cybervictimization, with Bullying (r = - .603, p < .001), Mood (r = - .329, p < .001), and School environment (r = - .327, p < .001) being particularly relevant. There were statistically significant differences between T1 and T2 for cyberbystanding (lower scores at T2). CONCLUSION: Cybervictims and cyberbully-victims have worse quality of life in all the dimensions than uninvolved individuals, especially in Psychological well-being, School environment, and Bullying.

Diseño y validación del cuestionario breve de seguridad del paciente para los servicios de urgencias: la visión del paciente / Design and validation of a brief questionnaire on the patient’s view of safety in the emergency department

Objetivos: Diseñar un cuestionario breve basado en las buenas prácticas para evaluar la percepción de seguridad desde el punto de vista del paciente en los servicios de urgencias(SU); obtener indicadores de validez y fiabilidad de la herramienta; y explorar los resultados preliminares. Método: Estudio de validación instrumental entre agosto de 2011 y febrero de 2012.Se ha creado para la ocasión el cuestionario breve de seguridad del paciente. En el estudio participaron 301 pacientes que fueron asistidos en el SU del Hospital Universitario San Cecilio de Granada (España).Resultados: Tras la realización del análisis factorial exploratorio se han obtenido datos que avalan la unidimensionalidad de la herramienta, con un factor que explica más del44,9% de la varianza total. El coeficiente del alfa de Cronbach para elementos tipificados fue superior a 0,822. Se han encontrado diferencias significativas (p < 0,004) en la puntación media del cuestionario breve de seguridad del paciente entre quienes refirieron padecer un evento adverso o haber interpuesto una reclamación, y quienes no lo reportaron. Los resultados preliminares señalan que existe una percepción positiva de la seguridad por parte de los pacientes. Conclusiones: El cuestionario muestra una alta consistencia interna y fiabilidad, además de una alta validez externa con los criterios usados. De tal forma, entendemos que es una herramienta válida para evaluar de forma rápida la percepción de seguridad del paciente en los SU (AU)

Objectives: 1) To design a brief questionnaire based on good practices to assess the patient’s perspective on safety in the emergency department; 2) to assess the tool's validity and reliability; and 3) to explore preliminary results. Methods: Questionnaire validation study performed between August 2011 and February 2012. The brief patient safety questionnaire was designed and tested in 301 patients attended in the emergency department of Hospital Universitario San Cecilio de Granada, Spain. Results: Exploratory factorial analysis to assess the dimensionality of the tool found that 1 factor explained more than 44.909%of the total variance. The Cronbach α calculated based on standardized scores exceeded 0.822. Significant differences (P<.004)were found in the mean scores of patients who reported an adverse event or made a complaint and those who did not. The preliminary results suggest that the patients had a positive view of safety in the emergency department. Conclusions: The questionnaire has high internal consistency and reliability as well as high external validity based on the external criteria used in the design. We therefore conclude that this instrument is valid for quickly assessing the patient’s view of safety in an emergency department (AU)

Acute and chronic stress increase salivary cortisol: a study in the real-life setting of a national examination undertaken by medical graduates.

Spanish medical graduates who apply for a medical specialty training position (MIR) must take an examination that will shape their future personal and professional lives. Preparation for the test represents an important stressor that persists for several months. The aim of this study was to elucidate the stress pattern of this group and evaluate possible changes in the circadian rhythm of cortisol release in medical graduates preparing for this test. A repeated-measures longitudinal study was performed, measuring the salivary cortisol concentrations in 36 medical graduates (13 males and 23 females; mean age of 24.2 years) on five sampling days. Five cortisol samples were collected from 07:00 to 21:00 h in order to monitor changes in the circadian rhythm. On all sampling days (except on the day of the official examination), anxiety and psychological stress were evaluated with the Spanish versions of the State-Trait Anxiety Inventory (STAI) and the Perceived Stress Scale (PSS). During the study period, participants showed higher levels of anxiety than the Spanish reference population as well as a progressive increase in self-perceived stress. A significant increase in salivary cortisol concentration was observed in both chronic (study and examination preparation) and acute (examinations) situations. Our results suggest that the cortisol awakening response (CAR) may be a good indicator of anticipatory stress but is unaffected by long-term examination preparation. Comparison of results between the official examination day and the mock examination days yielded evidence that learning may modulate the behavior of the hypothalamic-pituitary-adrenal axis.

Riesgo psicosocial en el trabajo, estrés autopercibido y cortisol en saliva en una muestra de urgenciólogos de Granada / Psychosocial risk at work, self-perceived stress, and salivary cortisol level in a sample of emergency physicians in Granada

Objetivos: Describir los riesgos psicosociales y la disposición estable al estrés, determinar los niveles de cortisol en la saliva en una muestra de urgenciólogos de los servicios de urgencias hospitalarios de Granada, determinar si existe o no asociación entre los parámetros antes mencionados y realizar comparaciones entre la variable sexo a través de todas las dimensiones de estudio. Método: Estudio analítico de corte transversal. Han participado un total de 32 urgenciólogos de dos hospitales en Granada (España). Para evaluar los riesgos psicosociales asociados al puesto de trabajo y el nivel de estrés se ha utilizado los cuestionarios validados y baremados CopSoQ-ISTAS-21 y el STAI-R, respectivamente. Además se ha medido el cortisol en saliva (Salivette®) como marcador bioquímico del estrés en tres determinaciones distintas durante la jornada laboral. Resultados: Los urgenciólogos manifiestan tener riesgos psicosociales desfavorables, especialmente por sus altas exigencias psicológicas y su bajo control del trabajo. Además, los varones presentan puntuaciones de estrés significativamente más elevadas que la población general (p < 0,017). Los valores de cortisol se encuentran dentro del rango de normalidad. No se encuentra relación entre el ISTAS-21, el STAI-R y el cortisol en saliva. Conclusiones: Los urgenciólogos presentan, en general, una situación potencialmente perniciosa para su actividad laboral, aunque no se afectan los niveles de cortisol como reflejo bioquímico de estrés (AU)

Objectives: 1) To describe psychosocial risks, stable disposition to feel stress, and salivary cortisol levels in a sample of emergency physicians in Granada, Spain; 2) to explore bivariate associations between the aforementioned factors; and3) to analyze the results by gender. Methods: Cross-sectional study of 32 physicians working at the emergency departments of 2 hospitals in Granada. Occupational psychosocial risk and perceived stress level were assessed with the ISTAS-21 instrument (validated Spanish version of the Copenhagen Psychosocial Questionnaire) and the State-Trait Anxiety Inventory (trait scale; STAI-T).Salivary cortisol (Salivette) was also measured as a biochemical marker of stress at 3 moments during a work shift. Results: The emergency physicians reported psychosocial risk factors, particularly high demand on psychological resources and low job control. The stress levels in the male physicians were significantly higher than in the general population (P<.017). Cortisol levels were within the normal range. On bivariate analysis, no associations were found between ISTAS-21 findings, STAI-T scores, and cortisol levels. Conclusions: Emergency physicians are in a potentially harmful working situation, although we detected no effect on cortisol as a biochemical marker of stress (AU)

Occurrence, characterization and insecticidal activity of Bacillus thuringiensis strains isolated from argan fields in Morocco.

Soils collected from five locations in the argan forest (an endemic plant) in Morocco were used to form the first collection of Bacillus thuringiensis (Bt) strains from this area (58 strains). Here we found that the argan forest is a major source of Bt, as 90.62% of the samples contained Bt strains. These strains produced mainly spherical or irregular crystals that in some cases remained adhered to the spore after cell lysis. There was no strain producing bipyramidal crystals, suggesting the absence of strains bearing crv1 genes. This was confirmed by PCR analysis using eight primer pairs that can potentially detect 13 different groups of cry and cyt genes. Strains containing cry7/8 were the most abundant (25.53%), followed by strains harbouring cry9A (14.89%), cry11 (8.51%) and cry4 (4.25%). The mixtures of spores and crystals as well as culture supernatants were assayed for toxicity towards Ceratitis capitata (Medfly), showing up to 30% mortality. Our findings suggest that the argan region is a suitable target for future and wider screening programmes looking for strains bearing toxins or combinations of them to develop more efficient Bt-based formulates.

Diversity of Bacillus thuringiensis strains isolated from citrus orchards in spain and evaluation of their insecticidal activity against Ceratitis capitata.

A survey of Bacillus thuringiensis (Berliner) strains isolated from Spanish citrus orchards has been performed, and the strains were tested for insecticidal activity against the Mediterranean fruit fly Ceratitis capitata (Wiedemann), a key citrus pest in Spain. From a total of 150 environmental samples, 376 isolates were selected, recording a total B. thuringiensis index of 0.52. The collection was characterized by means of phase-contrast microscopy, SDS-PAGE, and PCR analysis with primer pairs detecting toxin genes cry1, cry2, cry3, cry4, cry5, cry7, cry8, cry9, cry10, cry11, cry12, cry14, cry17, cry19, cry21, cry27, cry39, cry44, cyt1, and cyt2. Diverse crystal inclusion morphologies were identified: bipyramidal (45%), round (40%), adhered to the spore (7%), small (5%), and irregular (3%). SDSPAGE of spore-crystal preparations revealed 39 different electrophoresis patterns. All primer pairs used in PCR tests gave positive amplifications in strains of our collection, except for primers for detection of cry3, cry19, cry39, or cry44 genes. Strains containing cry1, cry2, cry4, and cry27 genes were the most abundant (48.7%, 46%, 11.2%, and 8.2% of the strains, respectively). Ten different genetic profiles were found, although a total of 109 strains did not amplify with the set of primers used. Screening for toxicity against C. capitata adults was performed using both spore-crystal and soluble fractions. Mortality levels were less than 30%. We have developed a large and diverse B. thuringiensis strain collection with huge potential to control several agricultural pests; however, further research is needed to find out Bt strains active against C. capitata.

Use of NIRS technology with a remote reflectance fibre-optic probe for predicting mineral composition (Ca, K, P, Fe, Mn, Na, Zn), protein and moisture in alfalfa.

In the present work we study the use of near-infrared spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe for the analysis of major (Ca, K, P) and minor (Fe, Mn, Na, Zn) elements, protein and moisture in alfalfa. The method allows immediate analysis of the alfalfa without prior sample treatment or destruction through direct application of the fibre-optic probe on ground samples in the case of the mineral composition and on-ground and compacted (baled) samples in the case of protein and humidity. The regression method employed was modified partial least-squares (MPLS). The calibration results obtained using samples of alfalfa allowed the determination of Ca, K, P, Fe, Mn, Na and Zn, with a standard error of prediction (SEP(C)) and a correlation coefficient (RSQ) expressed in mg/kg of alfalfa of 1.37x10(3) and 0.878 for Ca, 1.10x10(3) and 0.899 for K, 227 and 0.909 for P, 103 and 0.948 for Fe, 5.1 and 0.843 for Mn, 86.2 and 0.979 for Na, and of 1.9 and 0.853 for Zn, respectively. The SEP(C) and RSQ values (in %) for protein and moisture in ground samples were 0.548 and 0.871 and 0.150 and 0.981, respectively; while in the compacted samples they were 0.564 and 0.826 and 0.262 and 0.935, respectively. The prediction capacity of the model and the robustness of the method were checked in the external validation in alfalfa samples of unknown composition, and the results confirmed the suitability of the method.

Imagen de la Psicología como profesión sanitaria entre los estudiantes de Psicología / Image of Psychology as a sanitary profession among Psychology students

Con el objetivo de conocer la opinión de los estudiantes de Psicología acerca del carácter sanitario de la misma, se realiza unestudio de poblaciones mediante encuestas en una amplia muestra de estudiantes de segundo ciclo de Psicología (N = 1.571)de 14 facultades españolas de Psicología. Se aplica el Cuestionario de Opinión sobre la Psicología como Profesión Sanitaria(COPPS). Los resultados muestran que los estudiantes sitúan claramente la Psicología dentro del ámbito sanitario. Otros datosde interés muestran que los estudiantes perciben una alta afinidad entre disciplinas médicas y disciplinas psicológicas, afinidadque no se limita a la Psicología Clínica, lo que respalda la propuesta de que otras disciplinas psicológicas además de laPsicología Clínica deberían ser consideradas sanitarias. Se discuten las implicaciones de estos datos en la percepción socialdel psicólogo como profesional sanitario

The aim of this study is to explore the opinion of Psychology students about Psychology as a sanitary profession. A survey descriptivestudy is conducted. The Questionnaire of Opinion about Psychology as a Sanitary Profession was applied to a sample of1.571 University students taking last Psychology courses from 14 Spanish Universities. Results show that Psychology students considerPsychology as a sanitary profession. Students perceive a high affinity between medical disciplines and psychological disciplinesbeyond Clinical Psychology. It supports that other psychological disciplines beyond Clinical Psychology should be consideredas sanitary professions. Implications for social perception of the psychologist as a sanitary professional are discussed

Toxicity of several delta-endotoxins of Bacillus thuringiensis against Helicoverpa armigera (Lepidoptera: Noctuidae) from Spain.

Toxicity and larval growth inhibition of 11 insecticidal proteins of Bacillus thuringiensis were evaluated against neonate larvae of Helicoverpa armigera, a major pest of important crops in Spain and other countries, by a whole-diet contamination method. The most active toxins were Cry1Ac4 and Cry2Aa1, with LC50 values of 3.5 and 6.3 microg/ml, respectively. At the concentrations tested, Cry1Ac4, Cry2Aa1, Cry9Ca, Cry1Fa1, Cry1Ab3, Cry2Ab2, Cry1Da, and Cry1Ja1, produced a significant growth inhibition, whereas Cry1Aa3, Cry1Ca2, and Cry1Ea had no effect.

On-line determination of fatty acid composition in intramuscular fat of Iberian pork loin by NIRs with a remote reflectance fibre optic probe.

A near infrared spectrometer equipped with a standard 210/210 bundle remote reflectance fibre-optic probe, with a 5×5 cm quartz window type, was used for the determination of fatty acids in the Longissimus dorsi muscle of Iberian breed swine. The fatty acids C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated were determined in samples of intramuscular fat from Iberian breed swine by direct application of the fibre-optic probe onto the loin sample, with no treatment or manipulation of the sample. The regression method employed was modified partial least squares. The calibration results using the fibre-optic probe for 74 loin samples had multiple correlation coefficients (RSQ) for C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated acid of 0.785, 0.798, 0.788, 0.825, 0.762, 0.765, 0.696, 0.859, 0.878, 0.807, 0.943, 0.858, respectively, and standard errors of prediction corrected for the same fatty acids (%) of 0.08, 0.63, 0.26, 0.02, 0.02, 0.51, 0,77, 0.64, 0.05, 1.06, 0.34, 0.70, respectively. The robustness of the method was checked by applying the fibre-optic probe to unknown samples of Iberian breed pork loin in a slaughterhouse, using 15 samples for the external validation.

Estimation of the global evolution of atmospheric pollution in Salamanca (Spain) during the 1993-2001 period according to one global index (ORAQI).

The aim of this study has been to use a global index to measure the air quality in the city, apart from individual assessment of the values of the concentrations of the different pollutants. We calculated the ORAQI with the data obtained at four air-pollution monitoring stations located in the city of Salamanca over the period between 1993 and 2001. For the calculations, SO2, PM10, NO2, CO and O3 were used as the most significant pollutants for the surroundings of the monitoring stations. The evolution of this index over 9 years is reported, and the repercussion of the most characteristic pollutants of each season of the year on the ORAQI along the whole period analysed is studied. The importance of the summer pollution in the characterisation of the least polluted surroundings was observed. At the most polluted sites, a decrease in the values corresponding to winter occurs, leading the ORAQI to take similar values along the whole year. In general, taking into account the surroundings of all the monitoring stations, the quality of the air to which the inhabitants of the city of Salamanca are exposed to can be said to be good.

Shared binding sites in Lepidoptera for Bacillus thuringiensis Cry1Ja and Cry1A toxins.

Bacillus thuringiensis toxins act by binding to specific target sites in the insect midgut epithelial membrane. The best-known mechanism of resistance to B. thuringiensis toxins is reduced binding to target sites. Because alteration of a binding site shared by several toxins may cause resistance to all of them, knowledge of which toxins share binding sites is useful for predicting cross-resistance. Conversely, cross-resistance among toxins suggests that the toxins share a binding site. At least two strains of diamondback moth (Plutella xylostella) with resistance to Cry1A toxins and reduced binding of Cry1A toxins have strong cross-resistance to Cry1Ja. Thus, we hypothesized that Cry1Ja shares binding sites with Cry1A toxins. We tested this hypothesis in six moth and butterfly species, each from a different family: Cacyreus marshalli (Lycaenidae), Lobesia botrana (Tortricidae), Manduca sexta (Sphingidae), Pectinophora gossypiella (Gelechiidae), P. xylostella (Plutellidae), and Spodoptera exigua (Noctuidae). Although the extent of competition varied among species, experiments with biotinylated Cry1Ja and radiolabeled Cry1Ac showed that Cry1Ja and Cry1Ac competed for binding sites in all six species. A recent report also indicates shared binding sites for Cry1Ja and Cry1A toxins in Heliothis virescens (Noctuidae). Thus, shared binding sites for Cry1Ja and Cry1A occur in all lepidopteran species tested so far.

High genetic variability for resistance to Bacillus thuringiensis toxins in a single population of diamondback moth.

The long-term benefit of insecticidal products based on Cry toxins, either in sprays or as transgenic crops, is threatened by the development of resistance by target pests. The models used to predict evolution of resistance to Cry toxins most often are monogenic models in which two alleles are used. Moreover, the high-dose/refuge strategy recommended for implementation with transgenic crops relies on the assumption that the resistance allele is recessive. Using selection experiments, we demonstrated the occurrence in a laboratory colony of diamondback moth of two different genes (either allelic or nonallelic) that confer resistance to Cry1Ab. At the concentration tested, resistance was dominant in one selection line and partially recessive in the other. Resistant insects from the two selection lines also differed in their cross-resistance patterns. The diamondback moth colony was derived from a field population from the Philippines, which originally showed a different resistance phenotype. This is the first time that an insect population has been directly shown to carry more than one gene conferring resistance to the same Cry toxin.

Variation in susceptibility to Bacillus thuringiensis toxins among unselected strains of Plutella xylostella.

So far, the only insect that has evolved resistance in the field to Bacillus thuringiensis toxins is the diamondback moth (Plutella xylostella). Documentation and analysis of resistant strains rely on comparisons with laboratory strains that have not been exposed to B. thuringiensis toxins. Previously published reports show considerable variation among laboratories in responses of unselected laboratory strains to B. thuringiensis toxins. Because different laboratories have used different unselected strains, such variation could be caused by differences in bioassay methods among laboratories, genetic differences among unselected strains, or both. Here we tested three unselected strains against five B. thuringiensis toxins (Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca, and Cry1Da) using two bioassay methods. Tests of the LAB-V strain from The Netherlands in different laboratories using different bioassay methods yielded only minor differences in results. In contrast, side-by-side comparisons revealed major genetic differences in susceptibility between strains. Compared with the LAB-V strain, the ROTH strain from England was 17- to 170-fold more susceptible to Cry1Aa and Cry1Ac, respectively, whereas the LAB-PS strain from Hawaii was 8-fold more susceptible to Cry1Ab and 13-fold more susceptible to Cry1Da and did not differ significantly from the LAB-V strain in response to Cry1Aa, Cry1Ac, or Cry1Ca. The relative potencies of toxins were similar among LAB-V, ROTH, and LAB-PS, with Cry1Ab and Cry1Ac being most toxic and Cry1Da being least toxic. Therefore, before choosing a standard reference strain upon which to base comparisons, it is highly advisable to perform an analysis of variation in susceptibility among field and laboratory populations.

Biochemical characterization of the third domain from Bacillus thuringiensis Cry1A toxins.

Cry proteins from Bacillus thuringiensis have insecticidal properties. The function of domains I and II has been described but domain III has so far eluded understanding. Domain III from Cry1Ab and Cry1Ac has been cloned, expressed in E. coli and injected to rabbits with the aid of characterizing them immunologically. Interestingly, polyclonal antibodies against Cry1Ab fragment did not recognize either the native Cry1Ab toxin or the Cry1Ac fragment while those against the latter did recognize either the native Cry1Ac toxin or the Cry1Ab protein fragment. A combination of information from sequence comparison and hydrophobicity profile indicates that these protein fragments possibly adopt different spatial dispositions within the respective toxins.