Slow muscles guide fast myocyte fusion to ensure robust myotome formation despite the high spatiotemporal stochasticity of fusion events.

Skeletal myogenesis is dynamic, and it involves cell-shape changes together with cell fusion and rearrangements. However, the final muscle arrangement is highly organized with striated fibers. By combining live imaging with quantitative analyses, we dissected fast-twitch myocyte fusion within the zebrafish myotome in toto. We found a strong mediolateral bias in fusion timing; however, at a cellular scale, there was heterogeneity in cell shape and the relationship between initial position of fast myocytes and resulting fusion partners. We show that the expression of the fusogen myomaker is permissive, but not instructive, in determining the spatiotemporal fusion pattern. Rather, we observed a close coordination between slow muscle rearrangements and fast myocyte fusion. In mutants that lack slow fibers, the spatiotemporal fusion pattern is substantially noisier. We propose a model in which slow muscles guide fast myocytes by funneling them close together, enhancing fusion probability. Thus, despite fusion being highly stochastic, a robust myotome structure emerges at the tissue scale.

Shiga toxin-producing Escherichia coli in Peruvian children with bloody diarrhea.

Shiga toxin-producing Escherichia coli (STEC) is not routinely sought in clinical laboratories in developing counties. Among 131 bloody diarrhea samples in Peruvian children <5 years of age, STEC was found in 9.2% and was associated with absence of fever, an observation that may increase suspicion of these pathogens. Because of the significant prevalence of STEC locally, proper diagnostics methods should be implemented in the region.

Aclimatização de mudas micropropagadas de helicônia em ambiente protegido em função do tipo de substrato / Acclimatization of micropropagated heliconia plants in different substrates

A etapa de aclimatização é uma fase crítica da micropropagação vegetal, podendo ser responsável por altos índices de mortalidade, baixas taxas de crescimento e desuniformidade das plantas. Um fator fundamental na aclimatização é tipo de substrato a ser utilizado. Nesse trabalho, objetivou-se avaliar o efeito de diferentes substratos na aclimatização de mudas micropropagadas de helicônia (Heliconia lingulata Ruiz & Pav.). A pesquisa foi conduzida em um túnel alto de cultivo forçado pertencente à Embrapa Agroindústria Tropica,l situada no município de Fortaleza - CE, Brasil (3º44'S e 38º33'W). O delineamento experimental utilizado foi em blocos casualizados com cinco tratamentos e cinco repetições. Os substratos testados foram: T1 -pó-de-coco seco + húmus de minhoca + solo (PCS+H+S); T2 -pó-de-coco verde + vermiculita + composto de cama de frango (PCV+V+CCF); T3 -pó-de-coco verde + húmus de minhoca + solo (PCV+H+S); T4 -pó-de-coco seco + vermiculita + composto de cama de frango (PCS+V+CCF); e T5 - substrato comercial Hortimix® (HORT). As variáveis agronômicas, avaliadas no experimento foram: altura da planta, número de folhas e diâmetro do pseudocaule. Os resultados do experimento evidenciaram o maior desenvolvimento das mudas micropropagadas de helicônia, quando o substrato utilizado foi a combinação pó de coco verde + húmus de minhoca + solo (PCV + H + S).

Acclimatization is the most important and critical plant micropropagation phase. It can be responsible for high mortality rate, low growth rate, and plant heterogeneity. One of the limiting factors in plant acclimatization is the substrate. The objective of this work was to evaluate the effect of different substrates on the acclimatization of micropropagated heliconia plants (Heliconia lingulata Ruiz & Pav.). The research was carried out in a greenhouse at the Embrapa Tropical Agroindustry located in Fortaleza, Ceará, Brazil (3º44' S and 38º33' W). The experimental design was a randomized block with five treatments and five repetitions. The substrates tested were: T1 - dry 'coir' dust + earthworm humus + soil (DCD+EH+S); T2 - green 'coir' dust + vermiculite + poultry litter (GCD+V+PL); T3 - green 'coir' dust + earthworm humus + soil (GCD+EH+S); T4 - dry 'coir' dust + vermiculite + poultry litter (DCD+V+PL) and T5 -Hortimix® (HORT). The variables evaluated in the experiments were plant height, number of leaves, and diameter of the pseudostem. The results revealed that the best development of micropropagated heliconia plants was with a combination of green 'coir' dust + earthworm humus + soil (GCD+EH+S).

Adhesión a la dentina con o sín humedad y presión constante a nivel dentinal comparando diferentes agentes de unión dentinal de resinas compuestas / Dentinal adhesion with humidity and constant pressure in dentine

Se comparó la adhesión a la dentina con humedad y presión constante a nivel dentinal in vitro con tres sistemas de adhesivos dentinales Probond (Dentsply), Optibond (Kerr) y Scotchbond Multipurpose (3M). Los adhesivos se usaron para la unión de la resina en las superficies dentales bucales de 60 dientes entre terceros molares y premolares. Los especímenes fueron almacenados en salivar inmediatamente después de la exodoncia de los 20 de cada grupo 10 tenian humedad y presion constante y 10 no lo tenían. Se prepararon las muestras como lo indica cada fabricante, luego se llevó a un aparato midiendo la resistencia adhesiva tensil para valorar la calidad del adhesivo. Para el grupo Multipurpose (3M) con un valor alto se observaron diferencias estadisticamente significantes comparadas con el grupo Optibond (Kerr) en cuanto a la humedad y no humedad, pero no mostró diferencias estadisticamente significativas con el grupo Probond (Dentsply). Comparando humedad con no humedad, tuvo valores más altos para el grupo de no humedad, por supuesto hubo diferencias estadisticamente significativas. La capa contaminante dentinal fué acondicionada más no removida sin afectar el grado de adhesión