We report an imaging method for fast, sensitive analysis of the orientation of fluorescent molecules by employing a liquid-crystal based universal polarizer in the optical path of a wide-field light microscope. We developed specific acquisition and processing algorithms for measuring the anisotropy and for correcting artifacts caused by fluorescence bleaching, background light, and differential transmission of optical components. We call this approach the Fluorescence LC-PolScope and we used it to analyze the architectural dynamics of septin-green fluorescent protein (septin-GFP) constructs in the neck region of budding yeast. We describe three different states of highly anisotropic septin arrays in which the prevailing orientation of GFP dipoles was either parallel or perpendicular to the mother-bud axis. The transitions between these ordered states were characterized by transient isotropic states. To analyze the patterns of polarized fluorescence, we modeled the alignment of septin-GFP constructs in different stages of septin ring formation. Based on our model, our experimental data are consistent with the formation of paired rather than single filaments and the axis of the α-helical septin terminus linked to a GFP molecule is likely oriented normal to the cell surface. The Fluorescence LC-PolScope combines the molecular specificity of fluorescence tagging with the structural specificity of polarized light analysis.

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Two optically active N-acetyldopamine dimers together with four phenolic monomers were isolated from the crude drug "Zentai," a cast-off shell of the cicada of Cryptotympana sp. (Cicadidae). The former two were 2-(3',4'-dihydroxyphenyl)-1,4-benzodioxane derivatives carrying substituents at the 3 and 6 (or 7) positions, which are known to be components of sclerotized insect cuticles. Their structures including absolute configurations were determined on the basis of NMR and circular dichroism (CD) spectroscopic data.

The so-called resin glycosides are well known as purgative ingredients, which are characteristic of some crude drugs such as Mexican Scammony Root, Orizaba Root, Jalapae Tuber, Pharbitidis Semen, and Rhizoma Jalapae Braziliensis. These drugs all originate from Convolvulaceae plants and can be roughly divided into an ether-soluble resin glycoside called jalapin and an ether-insoluble resin glycoside called convolvulin.1) In a previous paper, 2) we reported the isolation and structural elucidation of a new glycosidic acid called quamoclinic acid A that was obtained along with three organic acids, 2S-methylbutyric, n-decanoic, and n-dodecanoic acids, upon alkaline hydrolysis of the jalapin fraction of the seeds of Quamoclit pennata BOJER. Further, we isolated four genuine jalapins, quamoclins I, II, III, and IV, from the fraction.2) This paper deals with the component organic and glycosidic acids of the convolvulin fraction of the seeds of this plant.The alkaline hydrolysis products of the convolvulin fraction previously obtained 2) were fractionated into organic acid and glycosidic acid fractions. Gas chromatography (GC) of the former revealed the presence of isobutyric, 2-methylbutyric, and tiglic acids. Further, the organic acid fraction was methylated with diazomethane-ether and then examined using GC; it exhibited four peaks assignable to methyl tiglate, methyl nilate, methyl 7-hydroxydecanoate, and methyl 7-hydroxydodecanoate.The organic acid fraction was acylated with p-bromophenacyl bromide followed by chromatographic separation to give p-bromophenacyl 2-methylbutyrate (1), p-bromophenacyl tiglate (2), p-bromophenacyl nilate (3), p-bromophenacyl 7-hydroxydecanoate (4), and p-bromophenacyl 7-hydroxydodecanoate (5) (Fig. 1). The absolute configuration of 1 was defined as S by comparison of the specific rotation with an authentic sample, 3) and that of 3 was considered to be 2R,3R by comparisons of the specific rotation and the 1 H-NMR spectrum of 3 with those of an authentic sample. 3)However, the absolute value of the specific rotation of 3 was approximately 6-fold greater than that of p-bromophenacyl nilate (3Ј) previously obtained in a similar process as that used for 3 from the convolvulin fraction of Pharbitidis Semen.3) Thus the optical purities of 3 and 3Ј were examined using their 1 H-NMR spectra of (Ϫ)-a-methoxy-a-trifluoromethylphenylacetic acid (MTPA) esters 4) (3a from 3; 3Јa from 3Ј), and it was confirmed that 3 did not contain its enantiomer, while 3Ј was a mixture of p-bromphenacyl esters of the 2R,3R-and the 2S,3S-nilic acid in the ratio of approximately 6 : 5 on the basis of the ratio of intensities of signals due to H 3 -5 of the (2R,3R)-form and that of the (2S,3S)-form.The alkaline hydrolysis of 4 and of 5, with subsequent diazomethane-ether treatment, gave methyl 7-hydroxydecanoate (4a) and methyl 7-hydroxydodecanoate (5a), respectively. The configurations at C-7 of 4a and 5a were determined using Mosher's method. 4) Compounds 4a and 5a were converted into the corresponding (Ϫ)-MTPA ester...