The effect of chronic hypercapnia on cardioprotection induced by chronic hypoxia was investigated in adult male Wistar rats exposed to isobaric hypoxia (10 % O2) for three weeks. In the first experimental group, CO2 in the chamber was fully absorbed; in the second group, its level was increased to 4.1 %. Normoxic controls were kept in atmospheric air. Anesthetized open-chest animals were subjected to 20-min LAD coronary artery occlusion and 3-h reperfusion for infarct size determination (TTC staining). Chronic hypoxia alone reduced body weight and increased hematocrit; these effects were significantly attenuated by hypercapnia. The infarct size was reduced from 61.9 ± 2.2 % of the area at risk in the normoxic controls to 44.5±3.3 % in the hypoxic group (P<0.05). Hypercapnia blunted the infarct size-limiting effect of hypoxia (54.8±2.4 %; P<0.05). It is concluded that increased CO2 levels in the inspired air suppress the development of the chronic hypoxia-induced cardioprotective mechanism, possibly by interacting with ROS signalling pathways., J. Neckář, O. Szárszoi, J. Herget, B. Ošťádal, F. Kolář., and Obsahuje bibliografii
Photochemical efficiency of PSII of Ctenanthe setosa was investigated to understand the photosynthetic adaptation mechanism under drought stress causing leaf rolling. Stomatal conductance (gs), the levels of photosynthetic pigments and chlorophyll (Chl) fluorescence parameters were determined in leaves that had four different visual leaf rolling scores from 1 to 4, opened after re-watering and mechanically opened at score 4. gs value gradually decreased in adaxial and abaxial surfaces in relation to scores of leaf rolling. Pigment contents decreased until score 3 but approached score 1 level at score 4. No significant variations in effective quantum yield of PSII (ΦPSII), and photochemical quenching (qp) were found until score 3, while they significantly decreased at score 4. Non-photochemical quenching (NPQ) increased at score 2 but then decreased. After re-watering, the Chl fluorescence and other physiological parameters reached to approximately score 1 value, again. As for mechanically opened leaves, gs decreased during drought period. The decrease in adaxial surface was higher than that of the rolled leaves. NPQ was higher than that of the rolled leaves. ΦPSII and qp significantly declined and the decreases were more than those of the rolled leaves. In conclusion, the results indicate that leaf rolling protects PSII functionality from damage induced by drought stress. and H. Nar ... [et al.].
In this paper we present new approach to the problem of conservation the small and endangered populations of black grouse. We elaborated and checked in the field non-invasive methods enabling to obtain the genetic material without removing birds from natal populations. The main idea is to mate the tame, especially accustomed hen from the aviary with wild cock. After mating the hen lays the eggs in the aviary and we obtain the first generation which has a half of the gene pool coming from the population of its father. Consecutive, repeated crossing the females from such broods with next wild males leads in few years to bring the genes from original population to the aviary in non-invasive manner. Another method is to collect semen from wild males using a stuffed female. We describe some technical methods of such manipulations with the birds and present some preliminary results. These methods enable obtaining birds bred in aviary for future program of reintroduction.
As the UAV industry grows all over the world there are many new companies getting involved in various aspects from manufacturing, training, consulting, and providing aerial services. Commercial and recreational use represent unintentional risk to public safety through accidental collisions and crashes and deliberate use of UAVs to inflict harm is largely unmitigated due to the absence of effective UAV detection technology. and Prudký rozvoj bezpilotních prostředků po celém světě způsobil, že mnoho nových společností se zapojilo do vývoje a výroby v této oblasti. Jedná se o široké spektrum služeb, od výroby, ovládání UAV, přes monitoring a vyhodnocování dat až po údržbu těchto prostředků. Komerční a rekreační využití těchto prostředků sebou přináší ohrožení veřejné bezpečnosti prostřednictvím náhodných kolizí a pádů a může docházet i ke zneužití bezpilotních prostředků vzhledem k absenci účinné technologie odhalení UAV.
Traditionally, only two native localities of Ligularia sibirica have been reported from the Czech Republic. In the present paper, a correction is made as to the founder of the locality between Jestřebí and Staré Splavy near Doksy (50°36'23" N, 14°36'54" E) which was discovered by J. Ch. Neumann in 1814 the latest, i.e. earlier than thought. The species has been retreating from this locality because of changes in environmental conditions, with the decrease of groundwater level after amelioration in 1928 being the most important factor. However, the species is not yet endangered in the locality. The second locality is between Bělá pod Bezdězem and Bakov nad Jizerou (50°29'45" N, 14°54'39" E) and it was not discovered by anybody of those reported up to now but by V. J. Sekera; the discovery was not made in 1854 but as early as in 1843. This locality consists of several populations and its size has increased during the last 100 years. Bohemian localities, which are rather distant from the continuous distribution of the species, originated in the early postglacial period (Praeboreal) and represent remnants of former more extensive distribution in this region. The cultivation of the species and its secondary occurrence are rare and mostly unimportant events.
Excessive production of oxygen free radicals has been regarded as a causative common denominator of many pathological processes in the animal kingdom. Hydroxyl and nitrosyl radicals represent the major cause of the destruction of biomolecules either by a direct reaction or by triggering a chain reaction of free radicals. Scavenging of free radicals may act preventively or therapeutically. A number of substances that preferentially react with free radicals can serve as scavengers, thus increasing the internal capacity/activity of endogenous antioxidants and protecting cells and tissues against oxidative damage. Molecular hydrogen (H2) reacts with strong oxidants, such as hydroxyl and nitrosyl radicals, in the cells, that enables utilization of its potential for preventive and therapeutic applications. H2 rapidly diffuses into tissues and cells without affecting metabolic redox reactions and signaling reactive species. H2 reduces oxidative stress also by regulating gene expression, and functions as an anti-inflammatory and anti-apoptotic agent. There is a growing body of evidence based on the results of animal experiments and clinical observations that H2 may represent an effective antioxidant for the prevention of oxidative stress-related diseases. Application of molecular hydrogen in situations with excessive production of free radicals, in particular, hydroxyl and nitrosyl radicals is relatively simple and effective, therefore, it deserves special attention., J. Slezák, B. Kura, K. Frimmel, M. Zálešák, T. Ravingerová, C. Viczenczová, Ľ. Okruhlicová, N. Tribulová., and Obsahuje bibliografii
Four lamprey species and 55 fish species are considered autochthonous taxa in the Czech Republic. In recent years, as a result of spontaneous migrations, the native ichthyofauna has been increased by three species Sander volgensis, Gymnocephalus baloni, Proterorhinus marmoratus) which, in view of their autochthonous occurrence in the Central European region, are evaluated as native. At present, according to the criteria of the IUCN (2001) version 3.1, two lamprey species and 6 fish species are evaluated as “regionally extinct”. Most of these taxons are denoted as anadromous. One species has been classified in the category “Extinct in the wild”. Two lamprey species and 25 fish species are considered to be endangered to various extent: one lamprey species and 10 fish species are classified as “Critically endangered”; one lamprey species and 5 fish species as “Endangered”; ten fish species as “Vulnerable”. In the course of the past two centuries, attempts have been made at introducing about 30 fish species (see Lusk et al. 1998, Hanel 2003); of these, the introduction of 11 species can be evaluated as successful. Only four non-native species have established stable and naturally reproducing populations in natural conditions (Pseudorasbora parva, Carassius auratus, Ameiurus nebulosus, Gasterosteus aculeatus).
Flavonoids are thought to participate in protection of the photosynthetic apparatus against photoinhibition under excessive light. Flavone glycoside, scutellarin, is a main active ingredient extracted from Erigeron breviscapus, the plant used in Chinese medicine. Shade-developed leaves of E. breviscapus were transferred from shade to full sunlight to quantify a relationship between the concentration of leaf scutellarin and tolerance to high radiation stress or the recovery from photoinhibition. The maximal quantum yield of PSII photochemistry showed a diurnal fluctuation in both shaded and sunlit leaves throughout the day. It indicated dynamic photoinhibition in the leaves of Erigeron, i.e., higher photoinhibition at solar noon and lower one in the morning and late afternoon. The sun-developed leaves reached the higher scutellarin content and values of nonphotochemical quenching coefficient with a lower degree of photoinhibition than the shade-developed leaves. When the shade-developed leaves were transferred to full sunlight, the content of scutellarin was declining continuously for 10 d and then was increasing for 15 d. After 50 d, all leaves became the sun-developed leaves with their scutellarin contents of about 138.5 ± 5.2 mg g-1(dry mass, DM) which was significantly higher than that of the shade-developed leaves [107.8 ± 9.8 mg g-1(DM)]. During acclimatization, the degree of photoinhibition was negatively correlated with the scutellarin content. Our results demonstrated a synchronous fluctuation between the flavonoid content and degree of protection against photoinhibition., R. Zhou, W. H. Su, G. F. Zhang, Y. N. Zhang, X. R. Guo., and Obsahuje seznam literatury
The article focuses on social context and consequences of Descartes´s method. The method demands rejection of human society as an intrusion into the development of human rationality. Though a declared acceptance of human society in its historically established facility makes part of this rejection, it is necessary to defend oneself against it at first. The philosopher of method defends himself against society not only by means of isolation, but by external integration as well. When thus secured, he convinces the authorities not only about social harmlessness of his method, but also about its usefulness. He presents his method as ready to contribute a great deal to stability or to solid foundation of hitherto society. But even this cautious claim is guided by a pursuit of protection - now of the protection by authorities - for the benefit of the most important thing in the human world, the method itself, and the freedom of reason., Richard Zika., and Obsahuje seznam literatury