Estudio de caso de narrativas infantiles en videollamadas: Aportes al análisis de interacciones mediadas por tecnología / Case study of children's narratives in videochats: contributions to the analysis of technology-mediated interactions

Resumen El aislamiento social preventivo y obligatorio por la pandemia del SARS-CoV-2 condujo a las familias a buscar alternativas para mantener el vínculo con sus parientes no convivientes. Una de ellas fue la videollamada, cuyo carácter audiovisual habilita nuevas maneras de comunicación (Ames et al., 2010; Ballagas et al., 2009; McClure y Barr, 2017) que podrían modificar las interacciones en las que adultos/as y niños/as participan y colaboran en la construcción de distintos tipos de discursos. La narración constituye una de las primeras y más relevantes formas de discurso en la infancia que permite reconstruir y comunicar la propia experiencia. En este trabajo se realizó un análisis de caso de 31 narrativas que tuvieron lugar en cinco videollamadas en las que participaban una misma niña residente de la Ciudad de Buenos Aires y sus familiares, pertenecientes al corpus "Contextos naturales de interacción en los hogares en los que los/as niños/as usan tempranamente tecnología"[1], a fin de caracterizar las interacciones que contribuyen a la configuración de las narrativas infantiles en contextos mediados por tecnología. Los resultados mostraron una mayor presencia de narrativas personales y de futuro, frente a pocas de ficción; mientras que estas últimas fueron en su totalidad autorreguladas, la cantidad de narrativas hetero y autorreguladas fue similar para los otros dos tipos de narrativas. Se identificaron distintas estrategias a las que, en el marco de videollamadas, la niña recurrió para participar en la construcción de narrativas.

Abstract The preventive and compulsory social isolation established in Argentina due to the SARS-CoV-2 pandemic led families to look for alternatives to maintain the bond and communicate with their non-cohabitant relatives. One of these alternatives was the use of videochat. Videochat enables new ways of audiovisual communication (Ames et al., 2010; Ballagas et al., 2009; McClure & Barr, 2017) that could affect the interactions in which adults and children collaborate in the construction of different types of discourses. Narratives are one of the first and most relevant forms of discourse, it allows for the reconstruction and communication of one's experience and is one of the ways in which thought is configured. In this work, a case study was conducted of the narratives produced during videochat conversations of a four-year-old girl with non-cohabiting relatives. The aim was to characterize the interactions that help in the configuration of children's narratives during technology-mediated situations. The research question were: (a) how do technology-mediated interactions allow the child to narrate about past and future events and to create fictional narratives?; (b) how does the child participate in the construction of those narrative in the context of these technology-mediated situations? Five videos of videochat interaction belonging to a single four year old girl were selected from the corpus "Contextos naturales de interacción en los hogares en los que los/as niños/as usan tempranamente tecnología". This corpus gathers different technology-mediated interactions collected during daily activities in the home of children aged 0 to 6 years. First, 31 narratives in which the girl participated were identified. Subsequently, used the constant comparative method was used (Strauss & Corbin, 1998) as well as analysis tools developed within the framework of interactive sociolinguistics (Gumperz, 1982, 1984); also, concepts developed in previous research (Arrúe et al., 2014; Labov, 1972; Rosemberg et al., 2010; Stein et al., 2020) were heuristically recovered to answer the research questions. Of the 31 narratives produced in the interactions, 14 were related to personal experience, 13 were of future events, and 4 were fiction narratives. Regarding the posed questions, results showed that children do in fact create personal, future and fictional narratives in technology-mediated interactions with adults. Technology also enables children to decide how much they want to participate in interactions: they can lead the narrative, or they can back off to a yes-or-no answer kind of participation. The child relies on the possibility to share visual information, beyond audio, to provide both events and context information. This interactive and multimodal aspect of videochats was also found to enable the girl to turn to present adults both to scaffold her narrative production and to resolve doubts about unknown words. Even though there are methodological limitations to this study, this first approach to narratives in technology-mediated interactions shows the richness that this type of interaction can have for the development of children's language.

Influence of abiotic factors (water activity and temperature) on growth and aflatoxin production by Aspergillus flavus in a chickpea-based medium.

The effect of water activity (aW; 0.87, 0.90, 0.92, 0.94, 0.96, 0.98 and 0.99), temperature (15, 25, and 30 °C), incubation time (5, 10, 14, and 21 days), and their interactions on mycelial growth and aflatoxin production in a chickpea-based medium by three Aspergillus flavus strains isolated from chickpea grains in Argentina was evaluated. Maximum growth rates were obtained at the highest aW (0.99) and 30 °C, with growth decreasing as the aW of the medium was reduced. Maximum levels of aflatoxins were produced at 0.99 aW and 25 °C after 5 days of incubation for two strains, and at 25 °C and 0.96 aW after 21 days of incubation for the third strain. The aflatoxin concentrations varied considerably depending on the aW and temperature interactions assayed. Two-dimensional profiles of aW by temperature interactions were developed from these data to identify areas where conditions indicate a significant risk from aflatoxin accumulation on chickpea. This study provides useful baseline data on conditions representing a high and a low risk for contamination of chickpea by aflatoxins which is of greater concern because this pulse is destined mainly for human consumption.

Efecto del hilt en el estado de anímo en personas con sobrepeso en un entrenamiento virtual y presencial

Rojas-Ilama, V., Castro-Ramírez, M.L., Víquez-Arce, R., Jiménez-Díaz. y Montero-Herrera, B. (2022). Efecto del HIIT en el estado anímico en personas con sobrepeso en un entrenamiento virtual y presencial. PENSAR EN MOVIMIENTO: Revista de Ciencias del Ejercicio y la Salud, 20(1), 1-17. El principal objetivo fue comparar los efectos de una sesión HIIT de 35 minutos, en modalidad virtual y presencial, en los estados anímicos y en el esfuerzo percibido en personas con sobrepeso. Se reclutaron un total de 13 personas (5 hombres y 8 mujeres) con una edad promedio de 37.85 ± 13.20 años (rango entre 17 y 60 años) los cuales fueron asignados a cada una de las tres condiciones de manera aleatoria (control, entrenamiento presencial y entrenamiento virtual). Previo a, e inmediatamente después de cada una de las intervenciones, se aplicó el test POMS para medir los estados anímicos. En lo que respecta al esfuerzo percibido (EP), su medición se llevó a cabo finalizado cada uno de los ejercicios HIIT (no se evaluó durante el calentamiento y el retorno a la calma). Al aplicar un ANOVA de 2 vías de medidas repetidas (condición (3) x medición (2)), se encontró que tanto la tensión como el vigor después de haber aplicado el tratamiento presencial presentaron un aumento significativo; además, la tensión aumentó en la sesión virtual. Por su parte, los valores de EP reportados en las mediciones de las sesiones presencial y virtuales estuvieron por encima de lo sugerido en la literatura. En conclusión, una sesión de HIIT para personas con sobrepeso de manera presencial o virtual presenta resultados similares en los estados de ánimo, excepto el vigor, el cual incrementa solo en la condición presencial; las otras variables mostraron un comportamiento similar.

Rojas-Ilama, V., Castro-Ramírez, M.L., Víquez-Arce, R., Jiménez-Díaz. & Montero-Herrera, B. (2022). Effects of HIIT on the mood of overweight people in virtual and face-to-face training. PENSAR EN MOVIMIENTO: Revista de Ciencias del Ejercicio y la Salud, 20(1), 1-17. The main objective was to compare the effects of 35-minute HIIT session, in both virtual and face-to- face modes, on the mood and the perceived effort of overweight people. A total 13 people (5 men and 8 women) were recruited, in an average age of 37.85 ± 13.20 years (17-60 year range), who were randomly assigned to each of the three conditions (control, face-to-face training, virtual training). Prior to and immediately after each of the interventions, the POMS test was applied in order to measure mood. The measuring of perceived effort (PE) was carried out at the end of each of the HIIT exercises (it was not assessed during warm-up or return to calm). When a 2-way repeated-measure ANOVA was applied (condition (3) x measurement (2)), it was found that both stress and vigor after applying face-to-face treatment showed a significant increase. In addition, stress increased in the virtual session. For their part, the PE values reported in the measurements of the face-to-face and virtual sessions were above those suggested in the literature. In conclusion, a HIIT session for overweight people, whether face-to-face or virtual, shows similar results in their moods, except for vigor, which only increases in the face-to-face situation. The other variables showed a similar behavior.

Rojas-Ilama, V., Castro-Ramírez, M.L., Víquez-Arce, R., Jiménez-Díaz. e Montero-Herrera, B. (2022). Efeito do HIIT no estado anímico de pessoas com sobrepeso em um treinamento virtual e presencial. PENSAR EN MOVIMIENTO: Revista de Ciencias del Ejercicio y la Salud, 20(1), 1-17. O principal objetivo foi comparar os efeitos de uma sessão de HIIT de 35 minutos, em modalidades virtual e presencial, nos estados anímicos e no esforço percebido de pessoas com sobrepeso. Foram recrutadas um total de 13 pessoas (5 homens e 8 mulheres) com idade média de 37,85 ± 13,20 anos (faixa etária entre 17 e 60 anos) que foram designados a cada uma das três condições de maneira aleatória (controle, treinamento presencial e treinamento virtual). Antes e imediatamente depois de cada uma das intervenções, foi aplicado o teste POMS para medir os estados anímicos. Com relação ao esforço percebido (EP), a medição foi feita ao finalizar cada um dos exercícios HIIT (não foi avaliado durante o aquecimento e a volta à calma). Ao aplicar um ANOVA de 2 vias de medidas repetidas (condição (3) x medição (2)), observou-se que tanto a tensão quanto o vigor depois da aplicação do tratamento presencial aumentaram de maneira significativa; além disso, a tensão aumentou na sessão virtual. Por outro lado, os valores de EP relatados nas medições das sessões presenciais e virtuais estiveram acima do sugerido na literatura. Como conclusão, uma sessão de HIIT para pessoas com sobrepeso, seja presencial ou virtual, apresenta resultados semelhantes nos estados de ânimo, exceto o vigor, que aumento somente na condição presencial; as outras variáveis mostraram um comportamento semelhante.

Trichothecene Genotype Profiling of Wheat Fusarium graminearum Species Complex in Paraguay.

Paraguay is a non-traditional wheat-producing country in one of the warmest regions in South America. Fusarium Head Blight (FHB) is a critical disease affecting this crop, caused by the Fusarium graminearum species complex (FGSC). A variety of these species produce trichothecenes, including deoxynivalenol (DON) and its acetylated forms (3-ADON and 15-ADON) or nivalenol (NIV). This study characterized the phylogenetic relationships, and chemotype diversity of 28 strains within FGSC collected from wheat fields across different country regions. Phylogenetic analysis based on the sequence of elongation factor-1α gene (EF-1α) from 28 strains revealed the presence of four species in the FGSC: F. graminearum sensu stricto, F. asiaticum, F. meridionale and F. cortaderiae. Ten strains selected for further analysis revealed that all F. graminearum strains were 15-ADON chemotype, while the two strains of F. meridionale and one strain of F. asiaticum were NIV chemotype. Thus, the 15-ADON chemotype of F. graminearum sensu stricto was predominant within the Fusarium strains isolated in the country. This work is the first report of phylogenetic relationships and chemotype diversity among Fusarium strains which will help understand the population diversity of this pathogen in Paraguay.

COVID-19: Epidemiological Situation of Argentina and its Neighbor Countries after Three Months of Pandemic.

OBJECTIVE: In this work, in order to establish a better comprehension of the association between Argentina and its neighbor countries' capacity, and COVID-19 burden during the first 3 months, different indicators were evaluated. METHOD: We analyzed the association between GHSI, INFORM index and COVID-19 burden (number of confirmed cases and deaths), also the number of tests, lethality and the stringency of Governmental policies were evaluated. RESULTS: Uruguay, Paraguay, and Bolivia started earlier different prevention measures. The number of tests differs, as Chile is the 1 that makes more. Uruguay and Paraguay register fewer positive cases and deaths from COVID-19. The GHS index is led by Brazil, followed by Argentina, and then Chile. However, the INFORM index is led by Uruguay followed by Argentina, while Chile and Paraguay are on par. CONCLUSION: The countries that took preventive measures earlier and carried out a more tests are the ones that are obtaining the best results against COVID-19.

Effect of fungicides commonly used for Fusarium head blight management on growth and fumonisin production by Fusarium proliferatum.

Fumonisin occurrence was reported in wheat grains and F. proliferatum has been suggested to be the main contributor to its presence in wheat. Thus, a survey was performed in order to study the impact of four commercial fungicides used in Argentina for controlling Fusarium head blight disease (epoxiconazole+metconazole, tebuconazole, pyraclostrobin+epoxiconazole, and prothioconazole) on growth and fumonisin production of two F. proliferatum strains in relation to water activity (aW; 0.99, 0.97, 0.95) and temperature (15°C and 25°C). Most fungicides reduced growth rates when compared to the control (reduction increased as fungicide concentration increased), and reduced fumonisin production when they were used at high doses; however, most fungicides enhanced fumonisin production at sublethal doses, with the exception of prothioconazole. Thus, fungicides used for FHB management could enhance fumonisin production by F. proliferatum strains present in wheat grains.

Toxigenic fungal species and natural occurrence of mycotoxins in crops harvested in Argentina.

Mycotoxins are secondary metabolites produced by fungal species that mainly belong to Aspergillus, Fusarium, Penicillium and Alternaria, which can grow in a variety of crops including cereals, oilseeds and fruits. Consequently, their prevalence in foods and by-products not only affects human and animal health but also causes important losses in both domestic and international markets. This review provides data about toxigenic fungal species and mycotoxin occurrence in different crops commonly grown in Argentina. This information will be relevant to establish adequate management strategies to reduce the impact of mycotoxins on human food and animal feed chains and to implement future legislation on the maximum permitted levels of these fungal metabolites.

Influence of water activity and temperature on growth and fumonisin production by Fusarium proliferatum strains on irradiated wheat grains.

Wheat is the most important cereal consumed by the Argentine population. In previous studies performed in durum and common wheat grains in this country it has been observed fumonisin contamination as well as high incidence of Fusarium proliferatum. Fumonisins are toxic fungal metabolites, and consumption of fumonisin-contaminated maize has been epidemiologically associated with oesophageal cancer and neural tube defects in some human populations. Using irradiated wheat-grains, the effects of abiotic factors, temperature (15, 25, and 30°C) and water activity (aW; 0.995, 0.98, 0.96, 0.94, 0.92, and 0.88), on mycelial growth and fumonisin biosynthesis were compared for three F. proliferatum strains isolated from wheat grains in Argentina. Although all isolates showed similar profiles of growth, the fumonisin production profiles were slightly different. Maximum growth rates were obtained at the highest aW (0.995) and 25°C, with growth decreasing as the aW of the medium was reduced. Maximum amounts of total fumonisins (FB1, FB2 and FB3) were produced at 0.995 aW and 15°C for 2 strains, and at 25°C and 0.995 aW for the third one. Fumonisins concentrations varied considerably depending on the aW and temperature interactions assayed. Studied strains showed different fumonisin production profiles. Two-dimensional profiles of aW by temperature interactions were developed from these data to identify areas where conditions indicate a significant risk of fumonisins accumulation on wheat. As a result, temperature and aW conditions that resulted in fumonisins production are those found during wheat grain development (especially milk and dough stages) in the field. This is the first study made using irradiated wheat grains and provides useful baseline data on conditions representing a low or a high risk for fumonisins contamination of wheat grains which is of concern because this cereal is destined mainly for human consumption.

"¿Sabés qué es ?" Explicaciones de niños tutores en torno a vocabulario no familiar. Un estudio con niños de poblaciones urbano marginadas de Argentina / "Do you know what it is ?" Explanations of child tutors about non familiar vocabulary. A study with children from marginalized urban populations of Argentina

Resumen En el presente estudio se analizan situaciones de alfabetización entre díadas de niños de 12 años, que asistían a la escuela primaria y niños de 5 años de jardín de infantes generadas en el marco del programa de niños tutores en alfabetización "De niño a niño" (Rosemberg y Alam, 2009) orientado a promover el aprendizaje de la lectura y la escritura de niños, quienes viven en poblaciones urbano marginadas de Argentina. El análisis se focaliza en las secuencias de intercambio en las que los niños mayores (tutores) explican palabras poco familiares a los niños pequeños (aprendices) durante dis tintos tipos de actividades: lectura de cuentos y actividades focalizadas en el sistema de escritura y el vocabulario. Durante el año escolar, se llevaron a cabo 7 sesiones y las sesiones de 8 díadas fueron filmadas y transcriptas. Se identificaron 89 secuencias donde el tutor explicaba una palabra al apren diz. Para el análisis, se elaboró una categorización que da cuenta de la estructura conversacional de las secuencias de explicación -modalidad monologal o dialogal- y del tipo de información empleada -estrategias que recurren a aspectos semánticos y de contextualización. A fin de comparar cómo se despliegan estas secuencias en cada tipo de actividad, se emplearon pruebas estadísticas no paramé tricas. Los resultados mostraron una preeminencia de la modalidad monologal y un mayor empleo de estrategias que recurren a aspectos semánticos en las situaciones de lectura. En las otras actividades de alfabetización, prevaleció la modalidad dialogal y el empleo de estrategias de contextualización.

Abstract: This study analyzes literacy situations between dyads of 12-year-olds attending primary school and 5-year-old kindergarten children generated in the framework of the "De niño a niño" program (Rosemberg & Alam, 2009). The goal of this program is to promote reading and writing learning among children living in urban-marginalized populations in Argentina. The analysis focuses on the interventions used by older children (tutors) to explain un familiar words to younger children (apprentices) in the context of different types of activities: reading stories and activities focused on the writing system and vocabulary. During the school year, 7 sessions were held. The tutoring sessions of 8 dyads were videotaped and transcribed. Eighty-nine exchanges in which a tutor explained a word to the apprentice were identified. For the analysis, a categorization was elaborated focusing on the conversational structure of the explanation sequence modality - monologal or dialogal - and the type of information used for the explanation -strategies that resort to semantic and contextual aspects. In order to compare how these sequences were deployed in each type of activity, nonparametric statistical tests were used. The results showed a pre-eminence of the monologal modality and a greater use of strategies that resort to semantic aspects in reading situations. In the other literacy activities, the dialogal modality and the use of contextual aspects prevailed.

Two-dimensional environmental profiles of growth and fumonisin production by Fusarium proliferatum on a wheat-based substrate.

The effect of water activity (aW; 0.995, 0.99, 0.98, 0.96, 0.94, 0.92, and 0.90), temperature (15, 25, and 30°C), incubation time (7, 14, 21 and 28days), and their interactions on mycelial growth and fumonisin production on wheat-based medium by three Fusarium proliferatum strains isolated from wheat in Argentina was evaluated. Maximum growth rates were obtained at the highest aW (0.995) and 30°C, with growth decreasing as the aW of the medium was reduced. Maximum amounts of total fumonisins (FB1, FB2 and FB3) were produced at 0.99 aW and 25°C after 21 and 28days of incubation for 2 strains, and at 15°C and 0.98 aW after 28days of incubation for the third strain. The fumonisin concentrations varied considerably depending on the aW and temperature interactions assayed. The studied strains had different fumonisin production profiles. F. proliferatum ITEM 15661 and ITEM 15664 produced FB1 and FB2 whereas F. proliferatum ITEM 15654 was able to produce FB1, FB2 and FB3. Interestingly, fumonisin production profiles for each particular strain were related to incubation temperatures. Fumonisins were produced from 15 to 30°C and at aW values of 0.92 to 0.995 after 21 to 28days of incubation. However at 7 and 14days of incubation small amounts of fumonisin were produced at aW lower than 0.94. Two-dimensional profiles of aW by temperature interactions were developed from these data to identify areas where conditions indicate a significant risk from fumonisin accumulation on wheat. Temperature and aW conditions that resulted in fumonisin production are those found during wheat grain development (especially milk and dough stages) in the field. This study provides useful base line data on conditions representing a high and a low risk for contamination of wheat by fumonisins which is becoming of greater concern because this cereal is destined mainly for human consumption.

Toxigenic profile and AFLP variability of Alternaria alternata and Alternaria infectoria occurring on wheat.

The objectives of this study were to evaluate the ability to produce alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by A. alternata and A. infectoria strains recovered from wheat kernels obtained from one of the main production area in Argentina; to confirm using AFLPs molecular markers the identify of the isolates up to species level, and to evaluate the intra and inter-specific genetic diversity of these two Alternaria species. Among all the Alternaria strains tested (254), 84% of them were able to produce mycotoxins. The most frequent profile of toxin production found was the co-production of AOH and AME in both species tested. TA was only produced by strains of A. alternata. Amplified fragment polymorphism (AFLPs) analysis was applied to a set of 89 isolates of Alternaria spp (40 were A. infectoria and 49 were A. alternata) in order to confirm the morphological identification. The results showed that AFLPs are powerful diagnostic tool for differentiating between A. alternata and A. infectoria. Indeed, in the current study the outgroup strains, A. tenuissima was consistently classified. Characteristic polymorphic bands separated these two species regardless of the primer combination used. Related to intraspecific variability, A. alternata and A. infectoria isolates evaluated seemed to form and homogeneous group with a high degree of similarity among the isolates within each species. However, there was more scoreable polymorphism within A. alternata than within A. infectoria isolates. There was a concordance between morphological identification and separation up to species level using molecular markers. Clear polymorphism both within and between species showed that AFLP can be used to asses genetic variation in A. alternata and A. infectoria. The most important finding of the present study was the report on AOH and AME production by A. infectoria strains isolated from wheat kernels in Argentina on a semisynthetic media for the first time. Also, specific bands for A. alternata and A. infectoria have been identified; these may be useful for the design of specific PCR primers in order to differentiate these species and to detect them in cereals.

Evaluation of ability of ferulic acid to control growth and fumonisin production of Fusarium verticillioides and Fusarium proliferatum on maize based media.

The aim of this study was to evaluate the efficacy of ferulic acid (1, 10, 20 and 25 mM) at different water activity (aw) values (0.99, 0.98, 0.96 and 0.93) at 25 °C on growth and fumonisin production by Fusarium verticillioides and Fusarium proliferatum on maize based media. For both Fusarium species, the lag phase significantly decreased (p ≤ 0.001), and the growth rates increased (p ≤ 0.001) at the lowest ferulic acid concentration used (1mM), regardless of the aw. However, high doses of ferulic acid (10 to 25 mM) significantly reduced (p ≤ 0.001) the growth rate of both Fusarium species, regardless of the a(w). In general, growth rate inhibition increased as ferulic acid doses increased and as media aw decreased. Fumonisin production profiles of both Fusarium species showed that low ferulic acid concentrations (1-10mM) significantly increased (p ≤ 0.001) toxin production, regardless of the aw. High doses of ferulic acid (20-25 mM) reduced fumonisin production, in comparison with the controls, by both Fusarium species but they were not statistically significant in most cases. The results show that the use of ferulic acid as a post-harvest strategy to reduce mycotoxin accumulation on maize needs to be discussed.

Toxigenic profile and AFLP variability of Alternaria alternata and Alternaria infectoria occurring on wheat

The objectives of this study were to evaluate the ability to produce alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by A. alternata and A. infectoria strains recovered from wheat kernels obtained from one of the main production area in Argentina; to confirm using AFLPs molecular markers the identify of the isolates up to species level, and to evaluate the intra and inter-specific genetic diversity of these two Alternaria species. Among all the Alternaria strains tested (254), 84% of them were able to produce mycotoxins. The most frequent profile of toxin production found was the co-production of AOH and AME in both species tested. TA was only produced by strains of A. alternata. Amplified fragment polymorphism (AFLPs) analysis was applied to a set of 89 isolates of Alternaria spp (40 were A. infectoria and 49 were A. alternata) in order to confirm the morphological identification. The results showed that AFLPs are powerful diagnostic tool for differentiating between A. alternata and A. infectoria. Indeed, in the current study the outgroup strains, A. tenuissima was consistently classified. Characteristic polymorphic bands separated these two species regardless of the primer combination used. Related to intraspecific variability, A. alternata and A. infectoria isolates evaluated seemed to form and homogeneous group with a high degree of similarity among the isolates within each species. However, there was more scoreable polymorphism within A. alternata than within A. infectoria isolates. There was a concordance between morphological identification and separation up to species level using molecular markers. Clear polymorphism both within and between species showed that AFLP can be used to asses genetic variation in A. alternata and A. infectoria. The most important finding of the present study was the report on AOH and AME production by A. infectoria strains isolated from wheat kernels in Argentina on a semisynthetic media for the first time. Also, specific bands for A. alternata and A. infectoria have been identified; these may be useful for the design of specific PCR primers in order to differentiate these species and to detect them in cereals.

Influence of water activity and temperature on growth and mycotoxin production by Alternaria alternata on irradiated soya beans.

The aim of this study was to determine the effects of water activity (a(w)) (0.99-0.90), temperature (15, 25 and 30°C) and their interactions on growth and alternariol (AOH) and alternariol monomethyl ether (AME) production by Alternaria alternata on irradiated soya beans. Maximum growth rates were obtained at 0.980 a(w) and 25°C. Minimum a(w) level for growth was dependent on temperature. Both strains were able to grow at the lowest a(w) assayed (0.90). Maximum amount of AOH was produced at 0.98 a(w) but at different temperatures, 15 and 25°C, for the strains RC 21 and RC 39 respectively. Maximum AME production was obtained at 0.98 a(w) and 30°C for both strains. The concentration range of both toxins varied considerably depending on a(w) and temperature interactions. The two metabolites were produced over the temperature range 15 to 30°C and a(w) range 0.99 to 0.96. The limiting a(w) for detectable mycotoxin production is slightly greater than that for growth. Two-dimensional profiles of a(w)× temperature were developed from these data to identify areas where conditions indicate a significant risk from AOH and AME accumulation on soya bean. Knowledge of AOH and AME production under marginal or sub-optimal temperature and a(w) conditions for growth can be important since improper storage conditions accompanied by elevated temperature and moisture content in the grain can favour further mycotoxin production and lead to reduction in grain quality. This could present a hazard if the grain is used for human consumption or animal feedstuff.

Trichothecene genotypes and chemotypes in Fusarium graminearum strains isolated from wheat in Argentina.

Argentina is the fourth largest exporter of wheat in the world. The main pathogen associated with Fusarium Head Blight (FHB) of wheat in Argentina is Fusarium graminearum lineage 7 also termed F. graminearum sensu stricto in the F. graminearum species complex, which can produce the Type B trichothecenes, usually deoxynivalenol (DON) and its acetylated forms (3-ADON and 15-ADON) or nivalenol (NIV). We used a multiplex PCR assay of Tri3, Tri7, and Tri13 to determine the trichothecene genotype of 116 strains F. graminearum collected from three locations in Argentina and then verified the chemotype by chemical analysis. PCR assays and chemical analyses gave the same results for all strains that produced trichothecenes. Most strains (> 92%) had the 15-ADON genotype, with the remaining strains having the DON/NIV genotype. We observed neither the NIV nor the 3-ADON genotypes amongst the strains evaluated. The nine strains with the DON/NIV genotype produced DON when analyzed chemically. Thus, the Argentinean populations of F. graminearum are similar to those from wheat elsewhere in the world, in that all the strains produced DON/15-ADON and belong to lineage 7. However approximately 8% of the strains tested were incorrectly diagnosed as DON/NIV producers with the current multiplex PCR and were only DON producers by chemical analysis.