The species richness–productivity relationship in the herb layer of European deciduous forests

Aim In contrast to non‐forest vegetation, the species richness–productivity (SR‐P) relationship in forests still remains insufficiently explored. Several studies have focused on the diversity of the tree layer, but the species richness of temperate deciduous forests is mainly determined by their species‐rich herb layer. The factors controlling herb‐layer productivity may differ from those affecting tree layers or open herbaceous vegetation, and thus the SR‐P relationship and its underlying processes may differ. However, the few relevant studies have reported controversial results. Here we explore the SR‐P relationship in the forest herb layer across different areas from oceanic to continental Europe, and put the effect of habitat productivity on species richness into context with other key factors, namely soil pH and light availability. Location North‐western Germany, Czech Republic, Slovakia and southern Urals (Russia). Methods We measured herb‐layer species richness and biomass, soil pH and tree‐layer cover in 156 vegetation plots of 100 m² in deciduous forests. We analysed the SR‐P relationship and the relative importance of environmental variables using regression models for particular areas and separate forest types. Results We found a consistent monotonic increase in the herb‐layer species richness with productivity across all study areas and all forest types. Soil pH and light availability also affected species richness, but their relative importance differed among areas. Main conclusions We suggest that the monotonically increasing SR‐P relationship in the forest herb layer results from the fact that herb‐layer productivity is limited by canopy shading; competition within the herb layer is therefore not strong enough to exclude many species. This differs fundamentally from open herbaceous vegetation, which is not subject to such productivity limits and consequently exhibits a unimodal SR‐P relationship. We present a conceptual model that might explain the differences in the SR‐P relationship between the forest herb layer and open herbaceous vegetation.     

Results of long-term preservation of Mycobacteria by means of freeze-drying

In 179 strains of 10 different species of Mycobacteria, survival was studied 8–25 years after their lyophilization in different media. A 100% survival was observed in M. avium, M. phlei, M. aquae, M. microti, M. fortuitum, and M. smegmatis. The lowest survival rate was reported in M. kansasii, M. tuberculosis, and M. bovis. Worst growth occurred in the strains of M. bovis BCG. Among the suspending media, medium 2 (defibrinated sheep blood with lactose and gelatine) and medium 3 (1% solution of sodium glutamate) proved to be the most suitable. The study results have revealed that, when the method is well applied and the inoculum is sufficiently large, Mycobacteria survived without any change in their concomitant properties (including virulence) in the lyophilized state for many years.     

Manifestations of non-specific antiviral factor originating in tobacco leaves during virus infection

A non-specific effect of antiviral factor (AVF) was proved by interference of five different viruses (CMV, PVX, PVY, TMVe, TMV vulgare) with CBRV. The non-specific AVF originates in non-infected tissues around TMV lesions. Transmitted mechanically to other plants this AVF exhibits the same suppressive effect on multiplication of TMV and CBRV. The AVF is formed in the non-infected apical part of the leaf which was infected in its basal region. The susceptibility of leaves is decreased even when AVF is added to virus inoculum and applied mechanically on the leaf. The apical part of the leaf the base of which is met with necrotic reaction to TMV, is considerably less susceptible and TMV multiplication in this region is decreased. The necrosis on the leaf base induced by mechanical injury or by cysteine hydrochloride may decrease the susceptibility of the leaf to some extent, but has no effect on multiplication of the virus. The activity of AVF in healthy apical region of the leaf increases till the fifth to the eighth day after its basal part was infected. The apical region then exhibits lower susceptibility (decrease in number of lesions) and the growth of lesions is decreased. This indicates the virus multiplication being suppressed.     

The effect of gametocides on microsporogenesis of winter rye

The effect of gametocides FW-450, maleic hydrazide and Dalapone on the course of microsporogenesis, gametogenesis and starch synthesis in pollen grains of winter rye ev. ‘Esto’ was investigated. Solutions containing various concentrations of tested substances were applied on leaves in amount of 2.5 ml and 5.0 ml per plant at the beginning, at the full and at the end of shooting. The effect of gametocides was detectable already in the phase of microspore formation when a decrease of anther weight, pollen grain size and starch content in grains and an increase of the number of microspores with nonfinished development were observed. The manner and the extent of injuries were dependent on the applied substance, its concentration and on period of its application.     

Paraoxonase 1 (PON1) and its relationship to lipid variables, age and gender in healthy volunteers

Recent studies implied that low-density lipoprotein (LDL) modified predominantly by oxidation or glycation, significantly contributes to the formation of atherosclerotic lesions. In contrast to oxidized LDL (ox-LDL), high-density lipoprotein (HDL) is able to prevent accumulation of ox-LDL in arterial walls. This antiatherogenic property of HDL is attributed in part to several enzymes associated with the lipoprotein, including HDL-associated paraoxonase 1 (PON1). In this study we analyzed PON1 arylesterase/paraoxonase activities in relation to serum lipid profile, gender and age in thirty clinically healthy Slovak volunteers. Our results showed that PON1 arylesterase and paraoxonase activities were lower in citrated plasma than in serum by 16.6% and 27.3%, respectively. Among serum lipoproteins, only HDL-cholesterol level showed significant positive correlation with PON1 arylesterase activity (p = 0.042). Likewise, we found a significant relationship between atherogenic index (AI = total cholesterol/HDL-cholesterol) and PON1 arylesterase activity (p = 0.023). No significant correlation could be demonstrated between PON1 paraoxonase activity and serum lipid profile, age or gender. Furthermore, it was found that PON1 paraoxonase/arylesterase activities were higher in women compared with both investigated activities in men, but these differences were not statistically significant. These results confirmed a positive correlation between HDL-cholesterol and PON1 arylesterase activity. Moreover, it was found out that PON1 paraoxonase activity is not influenced either by gender or by age. PON1 arylesterase activity was however affected by gender to a limited extent.     

Differences in trait compositions between rocky natural and artificial habitats

Question: What are the differences in trait compositions that enable native plants to colonise comparable natural and man‐made habitats? Are these traits independent of phylogenetic relationships between species? Location: Czech Republic. Methods: The relative importance of biological, ecological and distributional traits of native species was studied, using a dataset of 75 species growing in rock and wall habitats in the Czech Republic. Species preferences for individual habitats due to climatic conditions and proportions of different vegetation types in their surroundings were partialled out using partial canonical correspondence analysis. The pattern of plant traits along a gradient from natural rock habitats to secondary wall habitats was analysed using regression trees and generalized linear models with and without phylogenetic correction. Results: The most common native species colonising rock habitats are phanerophytes, mostly woody juveniles, with a CSR life strategy and most are adapted to epizoochory. Summer green leaves, annual life span, CR life strategy, reproduction mostly by seeds and dispersal by ants are all traits positively associated with the ability of species to colonise wall habitats. These species are also characterised by their high demand for nutrients, temperature, base‐rich substrates and light. Biological and ecological traits are more important for colonising new habitats than traits related to species dispersal ability or phylogenetic relationships between species. Biological and ecological traits alone explained 29.3% of variability in the species dataset, while dispersal characteristics and phylogeny alone explained 9.1% and 4.8%, respectively. Conclusions: We outline how the process of environmental filtering determines native species assemblages and identify a set of species traits that enable them to persist in particular habitats. We conclude that although urbanisation generally results in loss of natural habitats, there are new, man‐made habitats potentially suitable for native species.     

New Embryo Lethals in Arabidopsis thaliana: Basic Genetic and Morphological Study

Six different mutations with defects in immature seed development have been identified during screening of a T-DNA collection of Arabidopsis thaliana. The mutations were confirmed to be monogenic and recessive-lethal by genetic analysis. Mutant embryos were blocked in certain steps in the process necessary for embryo viability and development, and therefore they belong to the embryo-lethal class of mutants. The genetic and morphological studies of T-DNA mutations affecting embryo development are presented. The youngest embryos with a defect were observed at the globular stage in the VIII-64 mutation. Externally located cells, precursor of the protoderm, were characterised by abnormal cell division. VIII-41 mutation with a defect at the late globular stage was arrested at the globular-heart stage transition. VIII-111 mutation showed defect at heart stage of embryogenesis with atypical development of cotyledon primordia. The defect was associated with abnormal pattern of cell division constituting the precursor of the shoot apical meristem. In VIII-82 mutation defect in torpedo stage with asymmetric cotyledons was observed. Cotyledon stage of embryos and chlorophyll defect were observed in VIII-75 mutant. Abnormal suspensor consisting of two columns of cells was observed in 280-4-4 mutation. Newly identified embryo-lethals can serve as starting material for more detailed genetic and molecular studies.