Intact calcium signaling in adrenergic-deficient embryonic mouse hearts

Mouse embryos that lack the ability to produce the adrenergic hormones, norepinephrine (NE) and epinephrine (EPI), due to disruption of the dopamine beta-hydroxylase (Dbh^?/-) gene inevitably perish from heart failure during mid-gestation. Since adrenergic stimulation is well-known to enhance calcium signaling in developing as well as adult myocardium, and impairments in calcium signaling are typically associated with heart failure, we hypothesized that adrenergic-deficient embryonic hearts would display deficiencies in cardiac calcium signaling relative to adrenergic-competent controls at a developmental stage immediately preceding the onset of heart failure, which first appears beginning or shortly after mouse embryonic day 10.5 (E10.5). To test this hypothesis, we used ratiometric fluorescent calcium imaging techniques to measure cytosolic calcium transients, [Ca²⁺]_i in isolated E10.5 mouse hearts. Our results show that spontaneous [Ca²⁺]_i oscillations were intact and robustly responded to a variety of stimuli including extracellular calcium (5?mM), caffeine (5?mM), and NE (100?nM) in a manner that was indistinguishable from controls. Further, we show similar patterns of distribution (via immunofluorescent histochemical staining) and activity (via patch-clamp recording techniques) for the major voltage-gated plasma membrane calcium channel responsible for the L-type calcium current, I_Ca,L, in adrenergic-deficient and control embryonic cardiac cells. These results demonstrate that despite the absence of vital adrenergic hormones that consistently leads to embryonic lethality in vivo, intracellular and extracellular calcium signaling remain essentially intact and functional in embryonic mouse hearts through E10.5. These findings suggest that adrenergic stimulation is not required for the development of intracellular calcium oscillations or extracellular calcium signaling through I_Ca,L and that aberrant calcium signaling does not likely contribute to the onset of heart failure in this model.     

LEAF VASCULATURE IN BARLEY,HORDEUM VULGARE (POACEAE)

The vascular system of the Hordeum vulgare L. leaf consists of multiple longitudinal strands interconnected by transverse bundles. In any transverse section, the longitudinal strands can be categorized into three bundle types: small, intermediate, and large. Individual longitudinal strands intergrade structurally from one bundle type into another as they descend the leaf. At their distal ends, they have the anatomy of a small bundle. As they descend the leaf, most intergrade into intermediate bundle and then into large bundle types. All strands with large bundle anatomy extend basipetally into the stem. Typically, the other longitudinal strands, which do not intergrade structurally into large bundles, do not enter the sheath, but fuse with other longitudinal strands above the junction of the blade with the sheath. Despite the decrease in number of longitudinal bundles entering the sheath, an increase takes place in the total crosssectional area of sieve tubes and tracheary elements. A linear relationship exists between leaf width and total bundle number in the blade but not in the sheath. Moreover, a linear relationship exists between cross-sectional area of vascular bundles and both total and mean cross-sectional area of tracheary elements and thin-walled sieve tubes.     

A Multivariate Re-Examination of Experimental Condition Effects on Acyloin-Type Condensation Mediated by Saccharomyces Cerevisiae

Statistical methods of optimization were applied to the stereoselective synthesis of (2S,3R)-5-phenylpent-4-en-2,3-diol mediated by baker's yeast. The quantitative effects of seven variables, i.e. pH, temperature, concentration of cinnamaldehyde, yeast and glucose, addition of pyruvate and acetaldehyde were investigated using a fractional factorial design. This approach gave informations about the chemical behaviour of the yeast. Response surface methodology was employed to describe the variability of the yield in the experimental domain.