Abstract INTRODUCTION: Benzimidazoles are commonly used for the control of veterinary nematodes. Resistance to benzimidazoles has been associated with three single nucleotide polymorphisms in the β-tubulin gene of common nematodes. However, these mutations are infrequent in the genus Ascaris spp. METHODS: In order to determine mutations associated with benzimidazole resistance in Ascaris suum, worms were collected from slaughtered pigs and a partial region of the β-tubulin gene was sequenced. RESULTS: All parasites showed the wildtype genotype for codons 167, 198, and 200 of the β-tubulin gene. CONCLUSIONS: This is the first report of genetic sequences associated with benzimidazole resistance in A. suum.

Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt “CVMNK” genotype in codons 72-76.

El tracto digestivo de orugas constituye un microambiente extremo, debido a su elevado pH y presencia de sustancias antimicrobianas secretadas por el insecto o derivadas del tejido vegetal ingerido. Al mismo tiempo, el intestino alberga gran cantidad de alimento, por el cual los microorganismos presentes podrían competir entre sí y con su hospedero. Existe poca información sobre la microbiota asociada con el intestino de orugas tropicales, aunque se ha demostrado la presencia de bacterias de diversos géneros tanto en el intestino como en el interior de pupas. El estudio de las actividades enzimáticas de estos microorganismos constituye un punto de partida en la comprensión de la posible relación metabólica y fisiológica que establecen con sus hospederos, a la vez que permite investigar enzimas con potenciales aplicaciones biotecnológicas. En este trabajo se evaluó la presencia de actividades gelatinolítica, caseinolítica, esterásica, lipolítica, quitinolítica, amilásica, celulolítica y xilanolítica en dos colecciones de aislamientos bacterianos provenientes de tractos digestivos de orugas y de pupas de los lepidópteros Automeris zugana y Rothschildia lebeau. Se utilizaron ensayos bioquímicos tradicionales para detectar enzimas secretadas en condiciones aerobias, en las que ambas colecciones exhibieron un comportamiento enzimático similar. Ningún aislamiento produjo un resultado positivo en todas las pruebas, pero como conjunto ambas colecciones fueron capaces de utilizar todos los sustratos evaluados. Los aislamientos obtenidos de pupas presentaron prácticamente las mismas actividades que sus homólogos provenientes de intestinos. En ambas colecciones fue posible agrupar los aislamientos de acuerdo con su patrón de producción de enzimas. Además de un conjunto heterogéneo de aislamientos poco activos (dos o menos actividades), se destacan dos grupos muy activos (al menos cinco actividades), que manifiestan una aparente especialización en los sustratos que utilizan. El primero de ellos está constituido exclusivamente por miembros de la familia Enterobacteriaceae, los cuales exhibieron un alto porcentaje de positividad en actividades lipolítica y quitinolítica, pero no demostraron la expresión de las actividades amilásica, celulolítica ni xilanolítica. El segundo grupo, formado en su gran mayoría por bacilos Gram-positivos, presenta la situación opuesta: alta positividad en actividades amilásica, celulolítica y xilanolítica, no detección de actividad quitinolítica y pocos aislamientos con actividad lipolítica. Este trabajo pretende ser la base de futuras investigaciones que exploren el potencial biotecnológico de aislamientos bacterianos provenientes del tracto digestivo de orugas.

Enzymatic activities of bacteria isolated from the digestive tract of caterpillars and the pupal content of Automeris zugana and Rothschildia lebeau (Lepidoptera: Saturniidae). The enzymatic activities of bacteria isolated from the digestive tracts of caterpillars and the pupal contents of Automeris zugana and Rothschildia lebeau was studied. This digestive tract represents an extreme microenvironment due to its high pH and presence of antimicrobial substances secreted by the insect or derived from ingested plant tissue. At the same time, it contains large amounts of nutrient-rich food, for which microbes may compete among themselves and with the caterpillar. There is little information about the microbiota associated with tropical caterpillar guts, although bacteria from different genera have been isolated from gut and pupae samples. The study of the enzymatic activities generated by these organisms constitutes a starting point to understand their metabolic and physiological relationships with their hosts, and to find enzymes that have potential biotechnological applications. In this study we evaluated several enzymatic activities in two collections of bacteria isolated from caterpillar guts and pupae of the tropical lepidopteran species A. zugana and R. lebeau. Bacteria grown under aerobic conditions were tested for an array of enzymes, including gelatinases, caseinases, lipases, esterases, cellulases, xylanases, amylases and chitinases. Both collections displayed similar patterns of enzymatic activity. No isolate showed activity for all enzymatic tests, but as a whole, at least some bacteria in each collection were able to degrade each substrate tested. Isolates with the same taxonomic identification obtained from caterpillar guts and pupae had almost the same enzymatic activities. In both collections, it was possible to group bacterial isolates according to their enzyme activity pattern. In addition to a heterogeneous ensemble of isolates exhibiting two or less enzymatic activities, there were two groups with at least five activities that showed an apparent specialization for the substrates they were able to use. The first consisted exclusively of isolates of the family Enterobacteriaceae, which were positive for lipolytic and chitinolytic activities, but completely lacked amylasic, cellulolytic and xylanolytic activities. The second group, composed mainly of Gram-positive rods, exhibited the opposite pattern: they were positive for amylasic, cellulolytic and xylanolytic activities, lacked chitinolytic activity and had few isolates with lipolytic activity. This work forms the foundation for future research to explore the biotechnological potential of bacterial isolates from caterpillar guts. Rev. Biol. Trop. 55 (2): 401-415. Epub 2007 June, 29.