Vitamin A and retinene, the carotenoid precursors of rhodopsin, occur in a variety of molecular shapes, cis-trans isomers of one another. For the synthesis of rhodopsin a specific cis isomer of vitamin A is needed. Ordinary crystalline vitamin A, as also the commercial synthetic product, both primarily all-trans, are ineffective. The main site of isomer specificity is the coupling of retinene w...

Herbivorous activity induces plant indirect defenses, as the emission of herbivorous-induced plant volatiles (HIPVs), which could be used by parasitoids for host location. Psyttalia concolor is a larval pupal endoparasitoid, attacking a number of tephritid flies including B. oleae. In this research, we investigated the olfactory cues routing host location behavior of P. concolor towards B. olea...

Hydrodistilled leaves and fruits of Hoslundia opposita yielded 0.54% and 0.65%v/w of essentials oils. Investigation by GC and GC-MS revealed that the bulk of the oils were constituted by oxygenated monoterpenes (81.3 and 81.4% for the leaves and fruits, respectively). The principal constituents of the leaf oil were 1, 8-cineole (72.3%), terpineol (7.2%), sabinene (4.5%), thymol (4.2%) and car-3...

We have described experiments involving the use of five crystalline isomers of retinene: the ordinary crystalline substance known previously from the work of Ball, Goodwin, and Morton (1948); neoretinenes a and b, first iso. lated in our laboratory; and isoretinenes a and b, isolated in the Organic Re. search Laboratory of Distillation Products Industries (Hubbard and Wald 1952; 1952-53). By al...

OBJECTIVE To investigate the electrophysiological determinant underlying the electrical induction of counterclockwise and clockwise isthmus dependent atrial flutter. PATIENTS AND METHODS The isthmus bordered by the inferior vena caval orifice-tricuspid annulus-coronary sinus ostium (IVCO-TA-CSO) has been assumed to be the site of both slow conduction and unidirectional block critical to the i...

Five crystalline retinenes have been isolated, which have every appearance of being cis-trans isomers of one another. They are all-trans retinene; three apparently mono-cis isomers: neoretinenes a and b and isoretinene a; and isoretinene b, an apparently di-cis isomer. The absorption spectra of these substances display the relations expected of cis-trans isomers. The main absorption band is dis...