RESUMEN
Non-motile primary cilia are dynamic cellular sensory structures and are expressed in adipose-derived stem cells (ASCs). We have previously shown that primary cilia are involved in chemically-induced osteogenic differentiation of human ASC (hASCs) in vitro. Further, we have reported that 10% cyclic tensile strain (1 Hz, 4 hours/day) enhances hASC osteogenesis. We hypothesize that primary cilia respond to cyclic tensile strain in a lineage dependent manner and that their mechanosensitivity may regulate the dynamics of signaling pathways localized to the cilium. We found that hASC morphology, cilia length and cilia conformation varied in response to culture in complete growth, osteogenic differentiation, or adipogenic differentiation medium, with the longest cilia expressed in adipogenically differentiating cells. Further, we show that cyclic tensile strain both enhances osteogenic differentiation of hASCs while it suppresses adipogenic differentiation as evidenced by upregulation of RUNX2 gene expression and downregulation of PPARG and IGF-1, respectively. This study demonstrates that hASC primary cilia exhibit mechanosensitivity to cyclic tensile strain and lineage-dependent expression, which may in part regulate signaling pathways localized to the primary cilium during the differentiation process. We highlight the importance of the primary cilium structure in mechanosensing and lineage specification and surmise that this structure may be a novel target in manipulating hASC for in tissue engineering applications.
Asunto(s)
Subunidad alfa 1 del Factor de Unión al Sitio Principal/genética , Mecanotransducción Celular/genética , Células Madre Mesenquimatosas/metabolismo , Osteogénesis/genética , Adipocitos/citología , Adipocitos/metabolismo , Adipogénesis/genética , Diferenciación Celular/genética , Linaje de la Célula/genética , Células Cultivadas , Cilios/genética , Regulación del Desarrollo de la Expresión Génica/genética , Humanos , Células Madre Mesenquimatosas/citología , Resistencia a la Tracción , Ingeniería de TejidosRESUMEN
There is a growing class of elementary particle detectors, large-water Cerenkov detectors, that have a body of water (thousands of tons) as a sensitive medium. Particles are detected when they interact with the water and produce Cerenkov light, so detection efficiency relies on the transparency of the water. These detectors are active typically for many years, so biological activity (primarily bacterial growth) is one of the means by which the transparency of the water may be reduced. We present the results of a measurement of light scattering and absorption from a population of Escherichia coli in water, which is used as a model for bacteria in general. One can separate the scattering and absorption by varying the refractive index of the medium by using a solute of high molecular weight. We show that the results can be understood simply in terms of light scattering from small spheres (radius ≈ wavelength) with an effective refractive index, n(b), plus a small amount of absorption in the ultraviolet. We compare his scattering with Rayleigh scattering in pure water.
RESUMEN
Developmental stages of fish and amphibians were used to evaluate reproductive impairments produced by environmental contaminants. Using static-renewal and flow-through procedures, exposure was initiated at, or soon after, fertilization and maintained through 4 days posthatching. Trace concentrations of many environmental toxicants produced high frequencies of mortality and teratogenesis. When developmental stages of the trout were exposed to inorganic mercury, 10% control-adjusted mortality was observed at 1 microgram/L and frequencies of terata in hatched populations ranged from 8% to 43% for exposure concentrations of 2 to 25 micrograms/L. In similar tests with the narrow-mouthed toad, 45% mortality occurred when mercury was administered at 1 microgram/L; frequencies of teratogenesis ranged from 8% to 17% at exposure concentrations of 1 to 5 micrograms/L; and complete mortality occurred at 7 micrograms/L. Boron-induced teratogenesis in trout ranged from 5% at 1 microgram/L to 51% at higher exposure levels. When catfish embryos were exposed to atrazine at 0.06, 4.8, and 46.7 mg/L, terata appeared in surviving populations at frequencies of 4%, 69%, and 100%, respectively. Fish and amphibian developmental stages constitute simple and effective models for 1) investigating mechanisms of teratogenesis, 2) evaluating the impact of environmental toxicants on aquatic biota, and 3) identifying environmental teratogens which may be of concern to human health.
Asunto(s)
Anfibios/embriología , Peces/embriología , Teratógenos , Toxicología/métodos , Animales , Atrazina/toxicidad , Larva/efectos de los fármacos , Mercurio/toxicidad , Metales/toxicidadRESUMEN
Morphine was detected in equine biological fluids by a combination of liquid-liquid extraction and column chromatography, followed by derivatization and gas-liquid chromatographic assay, using electron capture detector. Recovery of morphine from the equine biological samples was poor. However, despite an overall recovery of less than 20%, this method had a detection limit of 0.2 ng/ml. Addition of 5,000 U of bovine liver beta-glucuronidase/ml of urine enabled detection of the drug in urine for up to 144 hours after horses were given 0.1 mg of morphine/kg of body weight. Morphine was found for at least 24 hours in serum samples. An adaptation of logit-log transformation of gas-liquid chromatographic data for linearization over 3 log units suggested a simple adaptation to existing semiautomated data handling systems.