So far, these substances have brought us important drugs such as the angiotensin-converting enzyme inhibitors captopril and its derivates for treating hypertension and some types of congestive heart failure, and the glucagon-like peptide-1 receptor agonist exenatide for treating type 2 diabetes mellitus. The venoms of lizards and snakes are complex mixtures of dozens of pharmacalogically active compounds. ![]() This not only involves bioactive constituents from marine and terrestrial invertebrates such as insects and arthropods, but also those from amphibians and other 'higher' vertebrates such as reptiles. In the search for structurally novel and mechanistically unique lead compounds, these progams are increasingly turning to the bioactive molecules provided by the animal biodiversity. The fungus Penicillium rubens (Trichocomaceae) and the actinomycete bacterial species Saccharopolyspora erythraea (Pseudonocardiaceae) gave the antibacterial agents penicillin and erythromycin Abstract New drug discovery and development efforts have traditionally relied on ethnopharmacological information and have focused on plants with medicinal properties. Other important sources of novel drugs were microorganisms. Since then, many more breakthrough drugs have been developed from plants, including the antineoplastic agents vincristine and paclitaxel from the periwinkle plant Catharanthus roseus (Apocynaceae) and the Pacific yew Taxus brevifolia (Taxaceae), respectively the phytoestrogen diosgenin from yam species in the genus Dioscorea (Dioscoreaceae) that serves as precursor for, among others, oral contraceptives and cortisone and the oral antihyperglycemic biguanide metformin from the French lilac Galega officinalis (Fabaceae). somniferum was soon followed by many others such as, among others, the central nervous system stimulant caffeine from the beans of the coffee plant Coffea arabica (Rubiaceae) in 1819, the antimalarial quinine from the bark of the cinchona tree Cinchona officinalis (Rubiaceae) in 1820, and the analgesic salicin from the bark of the white willow Salix alba (Salicaceae) in 1828. Currently, morphine is used for, among others, the palliation of severe chronic pain in, for instance, terminal cancer patients, and serves as a precursor for a large number of opioid medications such as the antitussive codeine and the antidiarreal agent loperamide. Only in 1806, a pharmacologically active ingredient (morphine) from a plant (the opium poppy Papaver somniferum (Papaveraceae)) was for the first time isolated from a plant. This is understandable when considering that plants have been the main, if not the only sources of therapeutics for managing human diseases for millennia. Introduction New drug discovery and development programs have historically relied on the identification of novel lead compounds from plant origin. Thus, although Texas horned lizards rely strongly on crypsis, they make escape decisions based on degree of predation risk. They reacted primarily by immediate flight or jumping, possibly reflecting preparation to use alternative defensive strategies at close quarters or to delay escape while further assessing risk. cornutum assess themselves as being in immediate peril when suddenly covered by a shadow. We interpret these novel findings as indicating that P. Some lizards fled when the shadow fell on them. When a model accipiter passed overhead, lizards were much more likely to move and jump if and when the model cast a shadow directly on them than if the shadow passed nearby without falling on them. We also investigated responses to a shadow passing over a lizard, which might be a cue to imminent risk. ![]() Effect size was larger for approach speed than for directness of approach, in part because the difference between minimum bypass distances was small (0.0 m for direct and 0.6 m for indirect approaches). ![]() Flight initiation distance was greater for rapid than slow and direct than indirect approach, verifying the predictions for prey that do not rely exclusively on crypsis, forgoing escape. We predicted that, despite relying on crypsis, Texas horned lizards (Phrynosoma cornutum) would have greater flight initiation distances when approached rapidly than slowly and when approached directly than indirectly. Escape theory predicts that flight initiation distance (predator–prey distance when escape begins) increases as predation risk increases. Horned lizards are difficult to detect because of their cryptic coloration and behavior, but often flee from approaching predators and use specialized behavioral, morphological, and physiological defenses at close quarters.
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