Guarana Provides Additional Stimulation over Caffeine Alone in the Planarian Model

The stimulant effect of energy drinks is primarily attributed to the caffeine they contain. Many energy drinks also contain other ingredients that might enhance the tonic effects of these caffeinated beverages. One of these additives is guarana. Guarana is a climbing plant native to the Amazon whose seeds contain approximately four times the amount of caffeine found in coffee beans. The mix of other natural chemicals contained in guarana seeds is thought to heighten the stimulant effects of guarana over caffeine alone. Yet, despite the growing use of guarana as an additive in energy drinks, and a burgeoning market for it as a nutritional supplement, the science examining guarana and how it affects other dietary ingredients is lacking. To appreciate the stimulant effects of guarana and other natural products, a straightforward model to investigate their physiological properties is needed. The planarian provides such a system. The locomotor activity and convulsive response of planarians with substance exposure has been shown to provide an excellent system to measure the effects of drug stimulation, addiction and withdrawal. To gauge the stimulant effects of guarana we studied how it altered the locomotor activity of the planarian species Dugesia tigrina. We report evidence that guarana seeds provide additional stimulation over caffeine alone, and document the changes to this stimulation in the context of both caffeine and glucose.     

Medullary structure differences in Gelidium and Pterocladia (Gelidiales, Rhodophyceae): Taxonomic meaning

Study of the apical portions of vegetative thalli of 21 species of the genera Gelidium and Pterocladia (Gelidiales-Rhodophyta) revealed the existence of six patterns of medullary structure. Each pattern is characterized by the organization of the medullary tissue and the changes in cellular dimensions from apex to subapex. These characters can be used to separate groups of species within each genus.     

The γ-subunit of the rod photoreceptor cGMP-binding cGMP-specific PDE is expressed in mouse lung

The type 6 phosphodiesterase (PDE-6) from retinal rod photoreceptors is an αβγ[in2] heterotetramer. The α-and β-subunits contain catalytic sites for cGMP hydrolysis, whereas the γ-subunits (Pγ) serve as a protein inhibitor of the enzyme. Pγ is believed to be expressed only in photoreceptors. Using RT-PCR, we have amplified the complete coding sequence for Pγ from mouse lung RNA. The expression of Pγ in this tissue may be related to its ability to interact the type 5 phosphodiesterase (PDE-5), which is the predominant cGMP binding protein in lung. We therefore suggest that Pγ may have a wider signaling role in mammalian cells than previousl y appreciated.