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Fickian-Based Empirical Approach for Diffusivity Determination in Hollow Alginate-Based Microfibers Using 2D Fluorescence Microscopy and Comparison with Theoretical Predictions.

ABSTRACT: Hollow alginate microfibers (od = 1.3 mm, id = 0.9 mm, th = 400 µm, L = 3.5 cm) comprised of 2% (w/v) medium molecular weight alginate cross-linked with 0.9 M CaCl? were fabricated to model outward diffusion capture by 2D fluorescent microscopy. A two-fold comparison of diffusivity determination based on real-time diffusion of Fluorescein isothiocyanate molecular weight (FITC MW) markers was conducted using a proposed Fickian-based approach in conjunction with a previously established numerical model developed based on spectrophotometric data. Computed empirical/numerical (Dempiricial/Dnumerical) diffusivities characterized by small standard deviations for the 4-, 70- and 500-kDa markers expressed in m²/s are (1.06 × 10-9 ± 1.96 × 10-10)/(2.03 × 10-11), (5.89 × 10-11 ± 2.83 × 10-12)/(4.6 × 10-12) and (4.89 × 10-12 ± 3.94 × 10-13)/(1.27 × 10-12), respectively, with the discrimination between the computation techniques narrowing down as a function of MW. The use of the numerical approach is recommended for fluorescence-based measurements as the standard computational method for effective diffusivity determination until capture rates (minimum 12 fps for the 4-kDa marker) and the use of linear instead of polynomial interpolating functions to model temporal intensity gradients have been proven to minimize the extent of systematic errors associated with the proposed empirical method.

SUBMITTER: Mobed-Miremadi M

PROVIDER: S-EPMC5456451 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Fickian-Based Empirical Approach for Diffusivity Determination in Hollow Alginate-Based Microfibers Using 2D Fluorescence Microscopy and Comparison with Theoretical Predictions.

Mobed-Miremadi Maryam M Djomehri Sabra S Keralapura Mallika M McNeil Melanie M

Materials (Basel, Switzerland) 20141201 12

Hollow alginate microfibers (od = 1.3 mm, id = 0.9 mm, th = 400 µm, L = 3.5 cm) comprised of 2% (w/v) medium molecular weight alginate cross-linked with 0.9 M CaCl₂ were fabricated to model outward diffusion capture by 2D fluorescent microscopy. A two-fold comparison of diffusivity determination based on real-time diffusion of Fluorescein isothiocyanate molecular weight (FITC MW) markers was conducted using a proposed Fickian-based approach in conjunctio ...[more]

PMID: 28788268

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Project description:Sex differences in morphology, physiology, development, and behavior are widespread, yet the sexes inherit nearly identical genomes, causing most traits to exhibit strong and positive cross-sex genetic correlations. In contrast to most other traits, estimates of cross-sex genetic correlations for fitness and fitness components ( r W fm ) are generally low and occasionally negative, implying that a substantial fraction of standing genetic variation for fitness might be sexually antagonistic (i.e., alleles benefitting one sex harm the other). Nevertheless, while low values of r W fm are often regarded as consequences of sexually antagonistic selection, it remains unclear exactly how selection and variation in quantitative traits interact to determine the sign and magnitude of r W fm , making it difficult to relate empirical estimates of cross-sex genetic correlations to the evolutionary processes that might shape them. We present simple univariate and multivariate quantitative genetic models that explicitly link patterns of sex-specific selection and trait genetic variation to the cross-sex genetic correlation for fitness. We show that r W fm provides an unreliable signal of sexually antagonistic selection for two reasons. First, r W fm is constrained to be less than the cross-sex genetic correlation for traits affecting fitness, regardless of the nature of selection on the traits. Second, sexually antagonistic selection is an insufficient condition for generating negative cross-sex genetic correlations for fitness. Instead, negative fitness correlations between the sexes ( r W fm < 0 ) can only emerge when selection is sexually antagonistic and the strength of directional selection on each sex is strong relative to the amount of shared additive genetic variation in female and male traits. These results imply that empirical tests of sexual antagonism that are based on estimates of r W fm will be conservative and underestimate its true scope. In light of these theoretical results, we revisit current data on r W fm and sex-specific selection and find that they are consistent with the theory.

Dataset Information

Fickian-Based Empirical Approach for Diffusivity Determination in Hollow Alginate-Based Microfibers Using 2D Fluorescence Microscopy and Comparison with Theoretical Predictions.

Publications

Fickian-Based Empirical Approach for Diffusivity Determination in Hollow Alginate-Based Microfibers Using 2D Fluorescence Microscopy and Comparison with Theoretical Predictions.

Similar Datasets

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