The Drosophila mutant tan (t) shows reciprocal pigmentation defects compared with the ebony (e) mutant. Visual phenotypes, however, are similar in both flies: Electroretinogram (ERG) recordings lack "on" and "off" transients, an indication of impaired synaptic transmission to postsynaptic cells L1 and L2. Cloning of tan revealed transcription of the gene in the retina, apparently in photoreceptor cells. We expressed Tan in Escherichia coli and confirmed by Western blotting and mass spectroscopic analyses that Tan is expressed as preprotein, followed by proteolytic cleavage into two subunits at a conserved --Gly--Cys-- motif like its fungal ortholog isopenicillin-N N-acyltransferase (IAT). Tan thus belongs to the large family of cysteine peptidases. To discriminate expression of Tan and Ebony in retina and optic neuropils, we raised antisera against specific Tan peptides. Testing for colocalization with GMR-driven n-Syb-GFP labeling revealed that Tan expression is confined to the photoreceptor cells R1-R8. A close proximity of Tan and Ebony expression is evident in lamina cartridges, where three epithelial glia cells envelop the six photoreceptor terminals R1-R6. In the medulla, R7/R8 axonal terminals appeared lined up side by side with glial extensions. This local proximity supports a model for Drosophila visual synaptic transmission in which Tan and Ebony interact biochemically in a putative histamine inactivation and recycling pathway in Drosophila.

No abstract

Growing consumer interest in hemp oilseed supplements requires quality control. Therefore, appropriate, effective and verified analytical methods are needed for the determination of some bioactive cannabinoids in them. The aim of the study is to present an extended (compared to our previous research) validated high performance liquid chromatography with diode array detection (HPLC-DAD) method for the determination of four cannabinoids (cannabidiol, cannabidiolic acid, cannabinol and delta-9-tetrahydrocannabinol) in an oil matrix, which was used to determine these cannabinoids in seven commercial hemp oil supplements. In our method, the isolation of the target compounds was based on liquid extraction with acetonitrile combined with the freezing (at −41 °C) of the oil phase. The results show that in some cases, the determined concentrations of cannabinoids in the tested supplements differ significantly from those declared by the manufacturers. As for the main medicinal cannabinoid (CBD) in hemp oil supplements, in two cases, the measured concentration was significantly lower (1.45 and 1.81%) than the declared (5 and 5%), and in the other supplements, the obtained results confirm the declared amount of CBD within the error range from 3.29 to 9.2%. Therefore, to ensure the safe and beneficial use of these supplements by consumers, it is necessary to monitor their cannabinoid composition.

No abstract