Effects of gut-associated yeasts on Drosophila melanogaster performance

I used Drosophila melanogaster as a model to study the role of the gut microbiota, specifically yeasts, in animal physiology. I used Saccharomyces cerevisiae, the yeast commonly included in Drosophila diet, and Lachancea kluyveri, isolated from some Drosophila in the wild, and generated axenic (germ-free) and gnotobiotic (yeast-fed) flies. I found that L. kluyveri persists in the crop, as ascospores and vegetative cells, longer than S. cerevisiae. Some L. kluyveri vegetative cells survive passage through the gut. Egg to adult development time is reduced by 14% in vials containing live L. kluyveri or S. cerevisiae, whereas heat-killed yeasts reduced development time by 3.5-4.5%. Chill coma recovery time was decreased from 27 to 17 minutes by live L. kluyveri, but not heat-killed yeast. I conclude that there is a biological interaction between D. melanogaster and gut yeast, and that this system is suitable to explore the role of gut-associated yeasts on animal physiology

Comparing apples and oranges (and blueberries and grapes): fruit type affects development and cold-susceptibility of immature Drosophila suzukii

Drosophila suzukii is a cosmopolitan polyphagous pest on unripe soft-skinned fruits. We sought to determine 1) temperature treatments that could be used to kill immature D. suzukii in fruit or packaging, and 2) whether development on different fruits led to differences in cold tolerance of immature D. suzukii. We reared animals from egg on a banana-based laboratory diet and diets made of apple, blueberry, cherry, grape, orange, raspberry, or strawberry homogenate in agar, and measured development time, adult body size, and cold tolerance. Diet type had complex effects on development time; in particular, flies reared on apple- or blueberry-based diets developed more slowly to a smaller adult body size than those on other diets. Cold exposure killed eggs and both first- and second-instar larvae. Survival of 24h at +4°C by feeding third-instar larvae was lowest in blueberry and cherry. Five days at +0.6°C killed all feeding third-instar larvae; this treatment is likely sufficient for targeting D. suzukii in fruit. Two hours at -5 or -6°C killed all wandering third-instar larvae and pupae; this exposure could be sufficient for sanitation of packaging

Persistence of diet effects on the Drosophila suzukii microbiota

The insect commensal microbiota consists of prokaryotes and eukaryotes. The effect of diet and the persistence of the gut microbiota in Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) are not well-understood. We transferred subsets of a single population of D. suzukii to different fruit-based diets (blueberry, raspberry, and strawberry) for three generations and then returned them to a common, banana-based, laboratory diet. We used 16S (bacteria) and ITS (fungi) sequencing of female endosymbiont-free flies to identify the microbiota. We identified 2700 bacterial and 350 fungal OTUs; there was no correlation between the number of bacterial and fungal OTUs in a sample. Bacterial communities were dominated by Proteobacteria (especially Acetobacteraceae); Ascomycota dominated the fungal communities. Species diversity of both bacteria and fungi differed among diets, but there were no differences in species-level diversity when these flies were returned to a control diet. A Principle Coordinates Analysis revealed no differences in the bacterial or fungal community in the first generation on fruit diets, but that the communities diverged over the next two generations; neither fungal and bacterial communities converged after one generation on control food. We conclude that diet changes the D. suzukii microbiota, and that these changes persist for more than one generation

Gut yeasts do not improve desiccation survival in Drosophila melanogaster

A healthy gut microbiota generally improves the performance of its insect host. Although the effects can be specific to the species composition of the microbial community, the role of gut microbiota in determining water balance has not been well explored. We used axenic and gnotobiotic (reared with a known microbiota) Drosophila melanogaster to test three hypotheses about the effects of gut yeasts on the water balance of adult flies: 1) that gut yeasts would improve desiccation survival in adult flies; 2) that larval yeasts would improve adult desiccation survival; 3) that the effects would be species-specific, such that yeasts closely associated with D. melanogaster in nature are more likely to be beneficial than those rarely found in association with D. melanogaster. We used Saccharomyces cerevisiae (often used in Drosophila cultures, but rarely associated with D. melanogaster in nature), Lachancea kluyveri (associated with some species of Drosophila, but not D. melanogaster), and Pichia kluyveri (associated with D. melanogaster in nature). Adult inoculation with yeasts had no effect on survival of desiccating conditions. Inoculation with P. kluyveri as larvae did not change desiccation survival in adults; however, rearing with L. kluyveri or S. cerevisiae reduced adult desiccation survival. We conclude that adult inoculation with gut yeasts has no impact on desiccation survival, but that rearing with yeasts can have either no or detrimental effect. The effects appear to be species-specific: P. kluyveri did not have a negative impact on desiccation tolerance, suggesting some level of co-adaptation with D. melanogaster. We note that S. cerevisiae may not be an appropriate species for studying the effects of gut yeasts on D. melanogaster

Reflexiones desde el Aula de Clases en Arquitectura

Las líneas que siguen a continuación son el resultado de un ejercicio académico de estudiantes de noveno semestre del Programa de Arquitectura de la Universidad de la Costa, en el marco de la asignatura Electiva en Proyecto de Investigación II dirigida por el profesor Samuel Padilla-Llano, donde se aborda la investigación como un proceso de coproducción del conocimiento a través de metodologías y estrategias pedagógicas en el aula que permiten al estudiante deconstruir conceptos y elaborar colectivamente posturas y argumentación que aporten a la elaboración de ejercicios investigativos que decantan en productos de investigación y que reflejan en aprendizaje y el dominio de las competencias genéricas y específicas que consolidan su formación académica y profesional. La metodología de este ejercicio rápido de escritura está basada en las lecturas previas de fuentes primarias y bibliografía estructurada en las temáticas desarrolladas en la asignatura las cuales tienen un enfoque en la relación existente entre la arquitectura y los saberes relacionados con la salud y la medicina. Durante una sesión de clases de 3 horas se realiza un debate para socializar y puesta en común de las ideas. Posteriormente cada estudiante dedica un tiempo de la misma sesión a la elaboración del escrito bajo los parámetros indicados (ser reflexiones inéditas, usar citas bibliográficas a partir de las lecturas, tener control del sistema de citación APA). Luego se socializa el resultado y se organiza en documento colectivo y se prepara la publicación conjunta como resultado del trabajo reflexivo. Esta serie de lecturas realizadas durante el curso plantea la lectura semanal de dos artículos. Estos artículos que referencian trabajos locales, nacionales e internacionales, abordan elementos que ponen en discusión las formas de habitar del ser humano y la calidad de vida en los espacios donde trascurre el habitar. Preguntarnos sobre la calidad del hábitat humano y los aspectos que la definen, también es un acto que los arquitectos desde una disciplina concentrada en el hacer espacios para habitar (la casa, la calle, el barrio, la ciudad, etc.), debemos asumir con vocación y conciencia del efecto y la importancia que tiene sobre la vida del ser (o seres) que habitan el espacio. Y desde esa conciencia, el hacer la arquitectura es el arte de pensar, proyectar y configurar formas de habitar en el mudo