233 research outputs found

    Effect of 17 Days of Bed Rest on Peak Isometric Force and Unloaded Shortening Velocity of Human Soleus Fibers

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    The purpose of this study was to examine the effect of prolonged bed rest (BR) on the peak isometric force (Po) and unloaded shortening velocity (Vo) of single Ca2+-activated muscle fibers. Soleus muscle biopsies were obtained from eight adult males before and after 17 days of 6° head-down BR. Chemically permeabilized single fiber segments were mounted between a force transducer and position motor, activated with saturating levels of Ca2+, and subjected to slack length steps. Vo was determined by plotting the time for force redevelopment vs. the slack step distance. Gel electrophoresis revealed that 96% of the pre- and 87% of the post-BR fibers studied expressed only the slow type I myosin heavy chain isoform. Fibers with diameter \u3e100 μm made up only 14% of this post-BR type I population compared with 33% of the pre-BR type I population. Consequently, the post-BR type I fibers (n = 147) were, on average, 5% smaller in diameter than the pre-BR type I fibers (n = 218) and produced 13% less absolute Po. BR had no overall effect on Po per fiber cross-sectional area (Po/CSA), even though half of the subjects displayed a decline of 9–12% in Po/CSA after BR. Type I fiber Vo increased by an average of 34% with BR. Although the ratio of myosin light chain 3 to myosin light chain 2 also rose with BR, there was no correlation between this ratio and Vo for either the pre- or post-BR fibers. In separate fibers obtained from the original biopsies, quantitative electron microscopy revealed a 20–24% decrease in thin filament density, with no change in thick filament density. These results raise the possibility that alterations in the geometric relationships between thin and thick filaments may be at least partially responsible for the elevated Vo of the post-BR type I fibers

    Calongea, un nuevo género de trufas en las Pezizaceae (Pezizales)

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    Phylogenetic analysis of the ITS and LSU rDNA of Pachyphloeus species from Europe and North America revealed a new truffle genus. These molecular analyses plus sequences downloaded from a BLAST search in GenBank indicated that Pachyphloeus prieguensis is within the Pezizaceae but well outside of the genus Pachyphloeus. Morphological differences in the peridial and glebal hyphae and spores distinguish this genus from Pachyphloeus. We here propose the monotypic new genus Calongea, with the type species C. prieguensis comb. nov., in honor of Prof. Francisco de Diego Calonge, who has long studied the truffle fungi of Spain and participated in describing the type species of Calongea.El análisis filogenético del ITS y LSU rDNA de especies europeas y norteamericanas de Pachyphloeus revelan un género nuevo de trufa. Los datos moleculares de este estudio, además de las secuencias obtenidas de una búsqueda BLAST en GenBank, indican que Pachyphloeus prieguensis es un miembro de la familia Pezizaceae pero no está relacionado con ninguna otra especie hipogea o epigea de dicha familia. Encontramos diferencias morfológicas en las hifas del peridio y gleba así como en las esporas que morfológicamente distinguen éste de Pachyphloeus. Proponemos el nuevo género monotípico Calongea, con C. prieguensis comb. nov. como la especie tipo, en honor a uno de los descubridores originales, Prof. Francisco de Diego Calonge

    Australasian Sequestrate Fungi 19: Hysterangium colossum sp. nov.

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    Hysterangium colossum sp. nov, with extraordinarily large basidiomata for the genus, is described from dry Eucalyptus woodlands in the Australian Capital Territory and southeastern New South Wales. It typically grows in confluent clusters and has a thick peridium often invaginated into the gleba

    Animal-fungal interactions 2: First report of mycophagy by the Eastern European Hedgehog, Erinaceus concolor Martin, 1837 (Mammalia: Eulipotyphla: Erinaceidae)

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    Mycophagy (fungivory) performs numerous important ecosystem functions for fungi, plants, and animals. Fungi serve as food for diverse mammals, ranging from bears, Ursus spp., to shrews, Sorex spp. However, among the many mammals reported to eat fungi, hedgehogs and other insectivores have been poorly studied. Based on microscopic examination of a fecal sample collected from an Eastern European Hedgehog (Erinaceus concolor) near Ula-MuÄŸla, Turkey, we provide the first confirmed evidence of mycophagy by hedgehogs and review the literature on hedgehog mycophagy
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