Twenty years of numerical syntaxonomy

The development of numerical syntaxonomy during its first 20 yr is reviewed. The use of methods of numerical classification and ordination is the dominating feature of the development. National and local phytosociological data banks were established, large data sets handled and many important vegetation monographs were methodically based on multivariate data analysis. Particularly the development in Italy, the Netherlands, Czechoslovakia, and Sweden contributed to new theoretical elements of numerical syntaxonomy. Ordination became a common tool of searching for reticulate synsystematic relations between community types. The most popular ordination techniques have been Principal Components Analysis and Detrended Correspondence Analysis. Hierarchical agglomerative techniques of clustering still prevail in classification, although the divisive strategy of TWINSPAN has also become an effective tool for phytosociological clustering and table sorting. Extensive program packages, also for personal computers have now become standard equipment for many vegetation scientists.     

Stand microclimate and physiological activity of tree leaves in an oak-hornbeam forest

Summary In an uneven-aged, multi-species oak-hornbeam forest at Báb, SW Slovakia (former IBP Forest Research Site), a series of micrometeorological and ecophysiological measurements started in 1985. The aims of the work are to improve understanding of physiological processes (photosynthesis, respiration, and transpiration) of adult trees and stand microclimate, to collect data for simulation of the canopy (stand) photosynthesis and for ecological synthesis of the functioning of the forest ecosystem. In this paper, photosynthetically active radiation (PAR), air temperature (AT) and relative humidity (RH), wind speed (WS), and CO₂ concentration ([CO₂]) in and above the forest are characterized for the fully leaved season, using diurnal courses, vertical profiles and isodiagrams (isopleths). Approximately 50% of incident PAR was absorbed by the upper 4–5 m layer of leaves and only approximately 5% or less penetrated to the forest floor. Vertical gradients of AT and RH were generally low, but large differences in diurnal ranges of AT and RH were observed between vertical levels. The upper leaf canopy greatly reduced WS, and at a height of about 14 m above the ground it was close to zero. The highest diurnal [CO₂] maximum and variations occurred at 1 m above the ground, and the lowest above the forest. In good light conditions in the forest, the entire leaf canopy (overstorey and understorey canopy) is a large sink of CO₂. At night the forest stand is a source of CO₂, the largest internal source being the soil and forest floor.     

Paleobotanical studies inFagaceae of the European Tertiary

A systematic reassessment of megafossil records ofFagaceae in Central Europe has been undertaken on the basis of leaf cuticular characters. The oldest representatives date back to the Eocene:Quercus subhercynica spec. nova,Dryophyllum furcinerve (Rossm.)Schmalh.,Trigonobalanopsis rhamnoides (Rossm.) gen. & comb. nov. In the Oligocene other members of extant genera appear:Quercus rhenana (Weyl. & Kilpp.)Knobloch & Kvaek,Fagus attenuata Goepp.,Lithocarpus saxonicus spec. nova. In the Neogene these ancient taxa (except inFagus lineage), are gradually replaced by deciduous species ofQuercus andCastanea. Trigonobalanus andCastanopsis are recorded by fruits (or wood) only.     

Effects of agents affecting Ca2+ homeostasis onTrichoderma viride growth and conidiation

Agents known to influence Ca²⁺ homeostasis affected significantly the vegetative growth and starvation-induced conidiation ofTrichoderma viride. Ca²⁺ in millimolar concentrations stimulated both growth and conidiation; a Ca²⁺ deprivation of the fungus by the chelation of extracellular Ca²⁺ (not Mg²⁺ or divalent trace metals) with EGTA (ethyleneglycolbis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) restricted both the vegetative growth rate and starvation-induced conidiation. Both processes were affected by either Ca²⁺ or EGTA with different efficiencies. Divalent cations (Sr²⁺, Ba²⁺, Co²⁺, Ni²⁺, Mg²⁺, Cd²⁺, Cu²⁺, Mn²⁺) and La³⁺ (inorganic Ca²⁺ blockers) in millimolar concentrations exerted complex (stimulatory, inhibitory, or biphasic) effects on growth and conidiation. In general, their effects on the two processes were mutually different either qualitatively, or quantitatively, or both. Organic Ca²⁺ antagonists (verapamil and dihydropyridines) inhibited the vegetative growth. The results show that Ca²⁺ is required for vegetative growth and conidiation, and that different Ca²⁺-dependent mechanisms may be involved in the two processes. Divalent cations could serve as a tool for investigating the relationship between growth and conidiation.     

Vanadate inhibits the production and/or release of secondary metabolites without impairing growth in several fungal species

Vanadate (NaVO₃) in concentrations between 0.1–3.0 mmol/L inhibited the production of secondary metabolites (SMs) of strains of the following species:Trichoderma viride, Penicillium purpurogenum, Penicillium citrinum, Talaromyces avellaneus, andVerticillium psalliotœ. Growth was either not affected by NaVO₃, or the inhibition of the SM production occurred at lower NaVO₃, concentrations than that of the growth. Thus, at some NaVO₃ concentration the SM production was inhibited but the growth remained unaffected. The results suggest that NaVO₃ exerts a specific action either on the SM biosynthetic pathway(s) or on the export of SMs from cells.     

Euglena gracilis as a supplementary test organism for detecting biologically active compounds

The mutagenic activity of more than 120 antimicrobial agents and protective components was investigated. Only Kathon showed a consistent increase in revertant counts in the Ames test onSalmonella typhimurium. The hereditary bleaching test onEuglena gracilis used for detecting extranuclear mutations, showed positive results for Kathon, triethanolamine and diamine silver tetraborate.     

Ordovician (Dobrotivá Formation) ostracodes and trilobites from Ejpovice (Bohemia) and their relations to faunas of northern and western Europe

For the first time a complete ostracode and trilobite fauna is described from the Dobrovitá Formation (Ordovician) of Perunica. In contrast to the trilobite fauna the ostracode fauna evidences close relations to both Armorica and Baltica. The trilobite fauna comprises 11 species out of 11 genera, the ostracode fauna comprises 15 (5 new) species out of 15 (1 new) genera.     

Oxidation and amidation of salicylate by Streptomyces species

Seven streptomycete strains were tested for biotransformation of salicylate. The products were identified by nuclear magnetic resonance spectroscopy and three types of conversion were found. Streptomyces cinnamonensis and Streptomyces spectabilis formed gentisate and salicylamide concurrently. Streptomyces rimosus transformed salicylate to salicylamide. Streptomyces lividans, Streptomyces coelicolor, Streptomyces griseus and Streptomyces avermitilis produced only gentisate. Time course studies of salicylate conversion by thin-layer chromatography and high pressure liquid chromatography showed that salicylamide was accumulated in the culture broth, whereas gentisate was further metabolized.Key words: salicylate, gentisate, salicylamide, biotransformation, Streptomyces spp.     

Growth and fecundity of Daphnia after diapause and their impact on the development of a population

Laboratory and field investigations revealed that the life history traits of exephippial and parthenogenetic generations of Daphnia differ substantially. Daphniids hatching from resting eggs grow faster and their definitive body sizes are bigger than of hatchlings from subitaneous eggs. Size at maturity for exephippial animals is significantly larger. In spite of this, they mature a few days earlier than parthenogenetic females. In this study, the difference was 3–4 days for the laboratory experiments and 1–3 days for the field. Fecundity of the exephippial generation is markedly higher. Here, the clutch size for this generation was up to 3.5–4.0 times as large as for the parthenogenetic generation. Moreover, obtained results suggest that the relationship between clutch size and body length for both generations differ significantly.Estimates of the intrinsic rate of increase for field Daphnia populations demonstrated that life history traits of exephippial animals lead to a two or threefold higher rate of increase in the conditions of invertebrate predation pressure. Under moderate fish pressure, obtained r values for the daphniids hatching from resting eggs were larger than those from subitaneous. High growth rate of exephippial females is disadvantageous only under the conditions of severe pressure by fish. Obtained results suggest that hatchlings from diapausing eggs an acceleration of population increase by several times during the beginning of the development of a population with periodical re-establishment from resting eggs.     

Transfer of the broad-host-range IncQ plasmid RSF1010 and other plasmid vectors to the Gram-positive methylotroph Brevibacterium methylicum by electrotransformation

Gram-positive facultative methylotrophic coryneform bacterium Brevibacterium methylicum was efficiently transformed with various plasmids using electroporation of intact cells. In addition to the plasmid vectors pEC71 and pZ6-1 constructed on the basis of cryptic plasmids from coryneform bacteria, broad-host-range plasmids pLS5 (derivative of plasmid pMV158 from Streptococcus agalactiae) and RSF1010 belonging to the incompatibility group IncQ from Gram-negative bacteria were found to be present as autonomous structurally unchanged DNA molecules in B. methylicum transformants. With the exception of pZ6-1, all these plasmids were stably maintained in B. methylicum cells grown under non-selective conditions. When plasmid DNAs isolated from B. methylicum were used, the highest efficiency of transformation (10⁵ transformants/g DNA) was achieved. Correspondence to: J. Nevera