No abstract

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 aim of this work was to summarize documented preclinical and clinical effects of bryostatin-class compounds. Methods: A literature search was made of Medline and Web of Science databases in 2012. Results and conclusion: Our review showed that bryostatins are potent agonists of protein kinase C. In addition to this, their significant antineoplastic activity against several tumor types has also been established and described. Bryostatin's anticancer activity has been proved against various cancer types. Moreover, significant results have been achieved by using bryostatin-1 in combination with other therapies, including combination with vaccine testing. Concerning other important properties that bryostatins possess, their ability to sensitize some resistant cells to chemotherapy agents, or immunoactivity and further stimulating growth of new neural connections, and enhancing effect on long-term memory are worth mentioning. In particular, some new bryostatin analogs could represent potential therapeutic agent for the treatment of cancer and other diseases in future.

Abstract. Empirical data on many species of terrestrial orchids suggest that their flowering pattern over the years is extremely irregular and unpredictable. A long search for the reason has hitherto proved inconclusive. Irregular flowering was attributed to costs associated with sexual reproduction, to herbivory, or to the chaotic behaviour of the system represented by difference equations describing growth of the vegetative and reproductive organs. Data on the seasonal growth of leaves and inflorescence of Dactylorhiza majalis are used here to test alternative explanations of the irregular flowering patterns of orchids. These patterns are found to be extremely rare in our data set. Neither costs of reproduction nor grazing seem to explain the rare events of a transition from flowering one year to sterility or absence the next year. These transitions are almost exclusively characteristic of one of four experimental sites, the only unmown site, where the mean leaf area and incidence of flowering in the whole population is also in decline. It is therefore hypothesized that irregular flowering regimes may be characteristic of sites with temporarily or steadily declining populations and that they are usually not present in prosperous ones ‐ at least for D. majalis.

Pectinatella magnifica is an invasive freshwater bryozoan with ability to produce large colonies reaching a capacity of up to several tens dm 3 . 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 these locations its occurrence has invasion properties. Pectinatella expanded to some other sandpits, fishponds without intensive pisciculture. Pectinatella colonies are found mainly on submerged branches of willow trees. The differences between biomass in transects with the occurrence of shrub willow and biomass in transects without their presence were statistically significant in the total biomass weight and the number of colonies. The average weight of several colonies did not differ. The most important parameter affecting the occurrence was the low trophy of water. The water temperature is evidently an important factor affecting the seasonal dynamics of occurence. Differences in nitrogen and phosphorous content between the water outside and inside the colonies were statistically significant. The colonies also accumulate other elements, including microelements.

A basis for the identification of potential tourist development areas was defined as a combined use of the model of area load by visitors, the territorially-located database of tourist attractions, and the perception of their attractiveness by visitors. A distinctive inequality was identified in the area load and the distribution of tourist attractions. The areas of development were determined on the basis of a difference between the relative attendance and the relative attractiveness of the partial territorial units of a regular hexagonal network, sized approximately 3 km2, with a concurrent requirement of above-average total attractiveness

Empirical data on many species of terrestrial orchids suggest that their between-year flowering pattern is extremely irregular and unpredictable. A long search for the reason has hitherto proved inconclusive. Here we summarise and critically review the hypotheses that were put forward as explanations of this phenomenon: irregular flowering was attributed to costs associated with sexual reproduction, to herbivory, or to the chaotic behaviour of the system represented by difference equations describing growth of the vegetative and reproductive organs. None of these seems to explain fully the events of a transition from flowering one year to sterility or absence the next year. Data on the seasonal growth of leaves and inflorescence of two terrestrial orchid species, <i>Epipactis albensis</i> and <i>Dactylorhiza fuchsii</i> and our previous results are then used here to fill gaps in what has been published until now and to test alternative explanations of the irregular flowering patterns of orchids

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 effects are probably not marine invertebrates themselves, but microscopic symbionts or food which they feed on. Bryostatins from bryozoan species Bugula neritina are produced by a bacterial symbiont called Candidatus Endobugula sertula. They have significant anti-cancer effects, but also other therapeutic benefits. Compounds with the structure of bryostatins were also discovered in some other invertebrates. Sponges are a source of many compounds, e.g., ara-A (vidarabine), manzamine, lasonolides, spongistatins, peloruside and others with antimicrobial, anti-cancer, immunosuppressive and similar activities. Other important sources of compounds with medical effects are tunicates (Tunicata syn. Urochordata) and some snails (Mollusca). One drug was developed from tunicates &ndash; Yondelis against refractory soft-tissue sarcomas. Certain other drugs originate from snails: e.g., prialt, which acts against chronic pain in spinal cord injury. &nbsp;

Pectinatella magnifica (Leidy 1851) is an invasive freshwater colonial animal belonging to the phylum Bryozoa. It is native to the area east of the Mississippi River, from Ontario to Florida.