11 research outputs found
Recommended from our members
A new method for measuring the kinetics of transmembrane calcium-45 efflux in the smooth muscle of the guinea pig tanea coli
A simple technique has been developed for resolving cellular
45Ca efflux from intestinal smooth muscle into two exponential components. Strips of taenia coli from guinea pig are labeled with
45Ca for three hours and then washed in an ice-cold, oxygenated medium containing 5 mM CaEGTA and 1.5 mM excess Ca
2+ for 40 minutes in order to remove extracellularly bound label. Tissues subsequently placed in a control physiological solution at 37°C exhibit an efflux profile of
45Ca which can be resolved into two exponential components. The apparent magnitudes and rate constants of these components are sensitive to ionic alterations of the medium and to biochemical manipulation of the Ca
2+ compartmentalization within the cells
Performance of Fast Repetition Rate fluorometry based estimates of primary productivity in coastal waters
Capturing the variability of primary productivity in highly dynamic coastal ecosystems remains a major challenge to marine scientists. To test the suitability of Fast Repetition Rate fluorometry (FRRf) for rapid assessment of primary productivity in estuarine and coastal locations, we conducted a series of paired analyses estimating 14C carbon fixation and primary productivity from electron transport rates with a Fast Repetition Rate fluorometer MkII, from waters on the Australian east coast. Samples were collected from two locations with contrasting optical properties and we compared the relative magnitude of photosynthetic traits, such as the maximum rate of photosynthesis (Pmax), light utilisation efficiency (α) and minimum saturating irradiance (EK) estimated using both methods. In the case of FRRf, we applied recent algorithm developments that enabled electron transport rates to be determined free from the need for assumed constants, as in most previous studies. Differences in the concentration and relative proportion of optically active substances at the two locations were evident in the contrasting attenuation of PAR (400–700 nm), blue (431 nm), green (531 nm) and red (669 nm) wavelengths. FRRF-derived estimates of photosynthetic parameters were positively correlated with independent estimates of 14C carbon fixation (Pmax: n = 19, R2 = 0.66; α: n = 21, R2 = 0.77; EK: n = 19, R2 = 0.45; all p < 0.05), however primary productivity was frequently underestimated by the FRRf method. Up to 81% of the variation in the relationship between FRRf and 14C estimates was explained by the presence of pico-cyanobacteria and chlorophyll-a biomass, and the proportion of photoprotective pigments, that appeared to be linked to turbidity. We discuss the potential importance of cyanobacteria in influencing the underestimations of FRRf productivity and steps to overcome this potential limitation
Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study
10.1371/journal.pone.0139981PLoS ONE1010e013998