Josef Rajchard

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CONTEXT Bryostatins represent an important group of pharmaceutically promising substances. These compounds are produced by commensal microorganisms naturally occurring in marine invertebrates, mainly in bryozoans. The most frequently investigated substance is bryostatin-1, which is a highly oxygenated macrolide with a polyacetate backbone. OBJECTIVE The(More)
The ability to perceive the near ultraviolet part of the light spectrum (the wavelength 320–400 nm) has been detected in many bird species. This ability is an important bird sense. The ecological importance of UV perception has been studied mainly in the context of intraand inter-sexual signalling, common species communication and also in foraging. Some(More)
Bird skin has a number of specific properties. The uropygial gland is a significant skin gland in many species. The secretion of this gland is particularly necessary for maintaining physical characteristics, including feather waterproofing. In some bird species this gland secretion has a repellent effect against potential mammalian predators; in other(More)
Amphibians are interesting animals, very often kept by aquarists and vivarists. Their ability of intraspecific chemical signalization belongs to very interesting biological features. The skin glands of anurans secrete various biologically active compounds. The pheromones are peptides consisting of various numbers of amino acid residues and their synthesis(More)
Specific chemosignals (pheromones) have an important role in the antipredator behaviour in amphibians and other vertebrates. However, relatively little is known about the occurrence of chemical alarm cues just in amphibians. The site of chemosignals perception is vomeronasal system. The presence of the vomeronasal system in aquatic amphibians indicates that(More)
Th e goal of this paper is the assessment of the impact of personal experience on visitors' perceptions of the environments of selected tourist attractions. Th e cognitive paradigm of environmental perception research was chosen and the Mehrabian-Russell general measure of information rate was used. Students from the University of South Bohemia from three(More)
Pectinatella magnifica is an invasive freshwater bryozoan with ability to produce large colonies reaching a capacity of up to several tens dm3. In the Protected Landscape Area and Biosphere reserve Třeboňsko the bryozoan was first found in 2003 in one mesotrophic sandpit. The species gradually spread to many other sites around the Třeboň area and at most of(More)
Some species of invertebrates especially bryozoans (Bryozoa syn. Ectoprocta) and marine sponges (Porifera) are very important sources of pharmacologically exploitable compounds. These substances are probably produced to protect themselves from fish predators and may be an advantage in competition. The real sources of compounds with these antipredatory(More)
The perception of exogenous chemical substances, olfactory navigation and the use of the olfactory sense by birds to search for food are reviewed. Many results suggest that the olfactory sense is one of the important components of the navigation system in birds. The olfactory mechanisms used by homing pigeons to navigate homeward from distant sites have(More)