A combined study of morphology, stem anatomy and isozyme patterns was used to reveal the identity of sterile plants from two rivers on the Germany/France border. A detailed morphological examination proved that the putative hybrid is clearly intermediate between Potamogeton natans and P. nodosus. The stem anatomy had characteristics of both species. The most compelling evidence came from the isozyme analysis. The additive “hybrid” banding patterns of the six enzyme systems studied indicate inheritance from P. natans and P. nodosus. In contrast, other morphologically similar hybrids were excluded: P. ×gessnacensis (= P. natans × P. polygonifolius) by all the enzyme systems, P. ×fluitans (= P. lucens × P. natans) by AAT, EST and 6PGDH, and P. ×sparganiifolius (= P. gramineus × P. natans) by AAT and EST. All samples of P. ×schreberi are of a single multi-enzyme phenotype, suggesting that they resulted from a single hybridization event and that the present-day distribution of P. ×schreberi along the Saarland/Moselle border was achieved by means of vegetative propagation and long-distance dispersal. Neither of its parental species occur with P. ×schreberi or are present upstream, which suggests that this hybrid has persisted vegetatively for a long time in the absence of its parents. The total distribution of this hybrid is reviewed and a detailed account of the records from Germany is given. P. ×schreberi appears to be a rare hybrid. The risk of incorrect determination resulting from the identification of insufficiently developed or inadequately preserved plant material is discussed.
Carbonic anhydrase (CA) is a metalloenzyme that performs interconversion between CO2 and the bicarbonate ion (HCO3-). CAs appear among all taxonomic groups of three domains of life. Wide spreading of CAs in nature is explained by the fact that carbon, which is the major constituent of the enzyme’s substrates, is a key element of life on the Earth. Despite the diversity of CAs, they all carry out the same reaction of CO2/HCO3- interconversion. Thus, CA obviously represents a universal enzyme of the
carbon-based life. Within the classification of CAs, here we proposed the existence of an extensive family of CA-related proteins (γCA-RPs) - the inactive forms of γ-CAs, which are widespread among the Archaea, Bacteria, and, to a lesser extent, in Eukarya. This review focuses on the history of CAs discovery and integrates the most recent data on their classification, catalytic mechanisms, and physiological roles at various organisms., E. Kupriyanova, N. Pronina, D. Los., and Obsahuje bibliografii
The diversity of freshwater and inland saline planktic cyanoprokaryote microflora (cyanobacteria, cyanophytes) in Mexico depends on the wide variation of the biotopes in this country. There are no detailed studies, describing the planktic cyanoprokaryotic species from this region. This paper lists 51 planktic morphospecies, which were found in various water bodies in central Mexico during May 1992 and March-September 1993. Four new species (Cyanobacterium lineatum, Cyanotetras aerotopa, Anabaena fallax, Cylindrospermopsis taverae) are described, and important species commented. Various species characteristic for various types of reservoirs (volcanic lakes, lakes and artificial reservoirs with diverse trophic levels, hypertrophic pools, saline coastal lakes) were found. Taxonomic and ecological elaborations of the planktic cyanobacteria of Mexico (from an ecological, geographical as well as sanitary point of view – eutrofication, biomass production, toxicity) are urgently needed.
Distribution of a word across contexts has proved to be a very useful ap- proximation of the word’s meaning. This paper reflects on the recent attempts to enhance distributional (or vector space) semantics of words with meaning composition, in particular with Fregean compositionality. I discuss the nature and performance of distributional semantic representations and argue against the thesis that semantics is in some sense identical with distribution (which seems to be a strong assumption of the compositional efforts). I propose instead that distribution is merely a reflection of semantics, and a substantially imperfect one. That raises some doubts regarding the very idea of obtaining semantic representations for larger wholes (phrases, sentences) by combining the distributional representations of particular items. In any case, I reject the generally unquestioned assumption that formal semantics provides a good theory of semantic composition, which it would be desirable to combine with distributional semantics (as a theory that is highly successful on the lexical field). I suggest that a positive alternative to the strong reading of the distributional hypothesis can be seen in the philosophy of inferentialism with respect to language meaning. I argue that the spirit of inferentialism is reasonably compatible with the current practice of distributional semantics, and I discuss the motivations for as well as the obstacles in the way of implementing the philosophical position in a computational framework., Ukázalo se, že rozložení slova napříč kontextem je velmi užitečným přiblížením významu slova. Příspěvek se zabývá nedávnými snahami o rozšíření sémantiky slov s významovou skladbou, zejména pak o fregovskou kompozici. Diskutuji o povaze a výkonu distribučních sémantických reprezentací a argumentuji proti té tezi, že sémantika je v určitém smyslu identická s distribucí (což se zdá být silným předpokladem kompozičního úsilí). Místo toho navrhuji, aby distribuce byla pouze odrazem sémantiky a podstatně nedokonalým. To vyvolává určité pochybnosti o samotné myšlence získat sémantické reprezentace pro větší celky (fráze, věty) kombinací distribučních reprezentací jednotlivých položek. V každém případě, Odmítám obecně nezpochybnitelný předpoklad, že formální sémantika poskytuje dobrou teorii sémantické kompozice, kterou by bylo žádoucí kombinovat s distribuční sémantikou (jako teorie, která je na lexikálním poli velmi úspěšná). Navrhuji, že pozitivní alternativu k silnému čtení distribuční hypotézy lze vidět ve filozofii inferenciality s ohledem na jazykový význam. Tvrdím, že duch inferenciality je přiměřeně slučitelný se současnou praxí distribuční sémantiky a diskutuji o motivacích i překážkách ve způsobu implementace filosofické pozice do výpočetního rámce. které by bylo žádoucí kombinovat s distribuční sémantikou (jako teorie, která je na lexikálním poli velmi úspěšná). Navrhuji, že pozitivní alternativu k silnému čtení distribuční hypotézy lze vidět ve filozofii inferenciality s ohledem na jazykový význam. Tvrdím, že duch inferenciality je přiměřeně slučitelný se současnou praxí distribuční sémantiky a diskutuji o motivacích i překážkách ve způsobu implementace filosofické pozice do výpočetního rámce. které by bylo žádoucí kombinovat s distribuční sémantikou (jako teorie, která je na lexikálním poli velmi úspěšná). Navrhuji, že pozitivní alternativu k silnému čtení distribuční hypotézy lze vidět ve filozofii inferenciality s ohledem na jazykový význam. Tvrdím, že duch inferenciality je přiměřeně slučitelný se současnou praxí distribuční sémantiky a diskutuji o motivacích i překážkách ve způsobu implementace filosofické pozice do výpočetního rámce., and Radek Ocelák
There are 20 endemic genera of mosses and three of liverworts in North America, north of Mexico. All are monotypic except Thelia, with three species. General ecology, reproduction, distribution and nomenclature are discussed for each genus. Distribution maps are provided. The Mexican as well as Neotropical genera of bryophytes are also noted without detailed discussion.
Five new records of the scale-bearing chrysophytes Mallomonas multiunca, M. paxillata, M. portae-ferreae, M. prora and M. retifera are reported for the Czech Republic. M. multiunca was found in a mesotrophic oxbow lake of the river Vltava. M. paxillata, M. portae-ferreae and M. prora were found in a mesotrophic to eutrophic floodplain pool of the river Lužnice. M. retifera was recorded from alluvial pools associated with the Vltava and Lužnice rivers, respectively. Autecology and distribution of the species are discussed. Three of the species occur in temperate and subarctic regions, M. paxillata probably has a cosmopolitan distribution and M. portae-ferreae prefers warmer water, occurring most frequently in tropical to subtropical regions.
In this paper we define, by duality methods, a space of ultradistributions G ′ ω(RN ). This space contains all tempered distributions and is closed under derivatives, complex translations and Fourier transform. Moreover, it contains some multipole series and all entire functions of order less than two. The method used to construct G ′ ω(RN ) led us to a detailed study, presented at the beginning of the paper, of the duals of infinite dimensional locally convex spaces that are inductive limits of finite dimensional subspaces.
The distribution of Alisma gramineum in the Czech Republic was determined using herbarium specimens, data in the literature and the authors’ own records. Comparison of records from four periods (before 1900, 1901–1945, 1946–1970, 1971–2001) revealed that the total number of localities has not decreased, but the occurrence changed considerably both in terms of the localities and regions where the species is found. Abundant populations were observed on exposed shores of water reservoirs. It has colonized the Třeboň Basin, S Bohemia, over the last few decades. Effect of water regime, light/darkness regime and temperature on germination and dormancy was studied. A. gramineum is adapted to germinate in water and in the dark; germination occurs in late spring, i.e. a period of high temperature. The high variation in the germination response to particular environmental factors may be accounted for the irregular occurrence of A. gramineum at certain localities. Best conditions for seed production are shallow water and recently exposed shores of water reservoirs, where plants can grow and set seed within one growing season. The ability to survive in a vegetative stage is more important in deep water, but seed banks in the mud at the bottom of reservoirs is the only way the species can persist when adult plants die.
The distribution of four alien Reynoutria taxa (R. japonica var. japonica, R. japonica var. compacta, R. sachalinensis and R. ×bohemica), native to East Asia, and history of their introduction to and spread in the Czech Republic was studied. The most widely distributed representative of the genus, R. japonica var. japonica, was first recorded in 1883 by A. Weidmann in cultivation in S Bohemia. The first record outside cultivation is from N Bohemia in 1902. Up to 2000, it has been recorded in 1335 localities, most frequently in riparian and human-made habitats. The dwarf variety R. japonica var. compacta is of a limited distribution that depends on rare cultivation and subsequent escape. The first herbarium specimen was collected in 1948 and the first record out of cultivation is from 1995. R. sachalinensis was recorded in 261 localities. It was first collected in 1921 in Central Bohemia. A herbarium specimen of a plant cultivated in the Botanical Garden of the Charles University in Prague, collected in 1950, has been re-determined as R. ×bohemica, the hybrid between R. japonica var. japonica and R. sachalinensis, and represents the earliest record of the hybrid in the Czech Republic. Since then, this taxon was observed in 381 localities. Herbarium records were used to compare the rate of spread among the three common taxa in 1952–1995, i.e. since when the hybrid started to appear in herbaria. R. japonica var. japonica has been spreading significantly faster than R. sachalinensis and the hybrid exhibits twice the rate of invasion of its parents.
Larvae (metacestodes) of tapeworms of the cyclophyllidean family Gryporhynchidae (previously included in the Dilepididae) occur in different internal organs of fresh- and brackish water fish (110 fish species of 27 families in 12 orders reported), which serve as the second intermediate hosts. The species composition, spectrum of fish hosts, sites of infection, and geographical distribution of gryporhynchids recorded from fish are reviewed here on the basis of literary data and examination of extensive material from helminthological collections. Metacestodes of the following genera have been found in fish: Amirthalingamia Bray, 1974 (1 species), Ascodilepis Guildal, 1960 (1), Cyclustera Fuhrmann, 1901 (4), Dendrouterina Fuhrmann, 1912 (1), Glossocercus Chandler, 1935 (3), Neogryporhynchus Baer et Bona, 1960 (1), Paradilepis Hsü, 1935 (5), Parvitaenia Burt, 1940 (2), and Valipora Linton, 1927 (3). However, most published records concern only three species, namely Neogryporhynchus cheilancristrotus (Wedl, 1855) from the intestinal lumen, Paradilepis scolecina (Rudolphi, 1819) from the liver and mesenteries, and Valipora campylancristrota (Wedl, 1855) from the gall bladder of cyprinids and other fish in the Palaearctic Region. Data on other species as well as reports from other regions are very scarce and almost no information is available from Australia, tropical Asia and South America. A recent study of gryporhynchid metacestodes from Mexico (Scholz and Salgado-Maldonado 2001), which reported 13 species, suggested that they may be more common than indicated by records in the literature. Although only a few cases of pathogenic influence of larvae on fish hosts have been reported, the veterinary importance of gryporhynchids remains to be assessed on the basis of more detailed studies. The data available indicate a strict host and site specificity of some species whereas others occur in a wide spectrum of fish hosts and are not strictly site-specific. Evaluation of Paradilepis larvae from the liver of salmonid fish from British Columbia, Canada, identified as P. simoni Rausch, 1949 by Ching (1982), has shown that they probably belong to two species, P. simoni and P. rugovaginosus Freeman, 1954. Metacestodes of the latter species and those of Cyclustera magna (Baer, 1959) from the intestinal wall of Tilapia zillii (Gervais) from Kenya are reported from fish for the first time.