A genetic screen based on in vivo RNA imaging reveals centrosome-independent mechanisms for localizing gurken transcripts in Drosophila

We have screened chromosome arm 3L for ethyl methanesulfonate-induced mutations that disrupt localization of fluorescently labeled gurken (grk) messenger (m)RNA, whose transport along microtubules establishes both major body axes of the developing Drosophila oocyte. Rapid identification of causative mutations by single-nucleotide polymorphism recombinational mapping and whole-genomic sequencing allowed us to define nine complementation groups affecting grk mRNA localization and other aspects of oogenesis, including alleles of elg1, scaf6, quemao, nudE, Tsc2/gigas, rasp, and Chd5/Wrb, and several null alleles of the armitage Piwi-pathway gene. Analysis of a newly induced kinesin light chain allele shows that kinesin motor activity is required for both efficient grk mRNA localization and oocyte centrosome integrity. We also show that initiation of the dorsoanterior localization of grk mRNA precedes centrosome localization, suggesting that microtubule self-organization contributes to breaking axial symmetry to generate a unique dorsoventral axis

Factors Affecting Infestation by Triatoma infestans in a Rural Area of the Humid Chaco in Argentina: A Multi-Model Inference Approach

Vector-borne transmission of Chagas disease remains a major public health problem in parts of Latin America. Triatoma infestans is the main vector in the countries located in the South American Cone, particularly in the Gran Chaco ecoregion where residual insecticide control has achieved only a moderate, irregular impact. To contribute to improved control strategies, we analyzed the factors associated with the presence and abundance of T. infestans in 327 inhabited houses in a well-defined rural area with no recent vector control interventions in the humid Argentine Chaco. Bugs were found mainly in domiciles, kitchens, storerooms, and chicken coops and nests, particularly where adequate refuge and animal hosts (humans, dogs, cats or poultry) were available. Domiciles constructed from mud were the most often infested, but brick-and-cement domiciles, even in good conditions, were also found infested. Availability of refuge and hosts for T. infestans are key targets for vector control. Ten-fold variations in domestic infestation observed across neighboring villages, and differences in the relevant factors for T. infestans presence with respect to other areas of the Gran Chaco region suggest that host management, building techniques and insecticide use need to be tailored to the local environment, socio-economic characteristics, and climatic conditions

A rapid dual staining procedure for the quantitative discrimination of prion amyloid from tissues reveals how interactions between amyloid and lipids in tissue homogenates may hinder the detection of prions

Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative diseases with no cure to this day, and are often associated with the accumulation of amyloid plaques in the brain and other tissues in affected individuals. The emergence of new variant Creutzfeldt-Jakob disease, an acquired TSE with a relatively long asymptomatic incubation period and unknown prevalence or incidence, which could potentially be iatrogenically transmitted, has prompted the need for sensitive and rapid methods of detection of the pathology indicator, the protease-resistant prion protein (PrP(Sc)), in tissues and on surgical instruments. To discriminate between common tissue proteins and amyloid-rich aggregates such as those formed by abnormal prion, we developed a quantitative thioflavin T/SYPRO Ruby dual staining procedure, used in combination with episcopic differential interference contrast/epifluorescence (EDIC/EF) microscopy for rapid scanning of samples. The detection limit of this direct observation technique applied to brain homogenates was greatly enhanced by the addition of Tween 20, as demonstrated in double-blind studies using various proportions of ME7-infected brain mixed with normal brain homogenate. The characteristic thioflavin T signal correlated with the relative amount of prion amyloid and proved at least 2-log more sensitive than the classic Western blot using the same prepared samples. This new sensitive microscopy procedure, which can be easily applied in instrument decontamination surveys, is likely to be more sensitive that Western blot in practice since it does not rely on the elution of resilient PrP(Sc) bound to the instrument surfaces. Our study also demonstrates how interactions between prion and lipid-rich tissue homogenates may reduce the sensitivity of such detection assays