Disentangling evolutionary,environmental and morphological drivers of plant anatomical adaptations to drought and cold in Himalayan graminoids

Understanding what determine plants ability to survive drought and cold is crucial for predicting how plants may respond to ongoing climate change. Plant survival strategies are usually characterized by morphological and physiological adaptations, while their underlying anatomical settings are largely unknown. Woody angiosperms and herbaceous dicots have repeatedly evolved small water transporting conduits and large storage parenchyma tissues at colder or drier places to cope with freezing‐ and drought‐induced damages. However, whether these adaptations are also valid for graminoids remains unclear. Here we show that stem anatomical variations in grasses, sedges and rushes dominating in western Himalayan grasslands are driven by elevation and soil moisture via control over aboveground plant stature and belowground clonal growth, while phylogenetic constraints have only a weak effect. Phylogenetic comparative analyses controlling for confounding factors showed that the elevation‐related cooling controls the conductive system through reduced vessel diameter and extended assimilatory and storage tissues with more chlorenchyma and less sclerenchyma around vessels. The soil moisture deficit, on the other hand, determines stabilization structures by promoting short‐rhizomatous turf graminoids with hollow stems, thicker epidermis and deep adventitious roots in dry steppes and semi‐deserts. Saline wetlands and moist alpine pastures promote long‐rhizomatous short‐stature plants with lower need for mechanical support (absence of hollow stem) and exposure to high evaporative forcing (thinner epidermis). Observed trends of decreasing vessel sizes and lignification rate with elevation supports the existing knowledge that narrower vessels and extensive parenchyma assist plants to grow in cold environments by avoiding freezing‐induced cavitation. Our results bring novel information on ecological drivers influencing the evolution of anatomical adaptations in high mountain graminoids. Distinct grassland types, covering elevations from 2650 to 6150 m, harbor unrelated species with different evolutionary histories that have converged towards similar anatomical structures.     

Clonal growth and plant species abundance

Background and Aims

Both regional and local plant abundances are driven by species'' dispersal capacities and their abilities to exploit new habitats and persist there. These processes are affected by clonal growth, which is difficult to evaluate and compare across large numbers of species. This study assessed the influence of clonal reproduction on local and regional abundances of a large set of species and compared the predictive power of morphologically defined traits of clonal growth with data on actual clonal growth from a botanical garden. The role of clonal growth was compared with the effects of seed reproduction, habitat requirements and growth, proxied both by LHS (leaf–height–seed) traits and by actual performance in the botanical garden.

Methods

Morphological parameters of clonal growth, actual clonal reproduction in the garden and LHS traits (leaf-specific area – height – seed mass) were used as predictors of species abundance, both regional (number of species records in the Czech Republic) and local (mean species cover in vegetation records) for 836 perennial herbaceous species. Species differences in habitat requirements were accounted for by classifying the dataset by habitat type and also by using Ellenberg indicator values as covariates.

Key Results

After habitat differences were accounted for, clonal growth parameters explained an important part of variation in species abundance, both at regional and at local levels. At both levels, both greater vegetative growth in cultivation and greater lateral expansion trait values were correlated with higher abundance. Seed reproduction had weaker effects, being positive at the regional level and negative at the local level.

Conclusions

Morphologically defined traits are predictive of species abundance, and it is concluded that simultaneous investigation of several such traits can help develop hypotheses on specific processes (e.g. avoidance of self-competition, support of offspring) potentially underlying clonal growth effects on abundance. Garden performance parameters provide a practical approach to assessing the roles of clonal growth morphological traits (and LHS traits) for large sets of species.     

Local-Scale Diversity and Between-Year “Frozen Evolution” of Avian Influenza A Viruses in Nature

Influenza A virus (IAV) in wild bird reservoir hosts is characterized by the perpetuation in a plethora of subtype and genotype constellations. Multiyear monitoring studies carried out during the last two decades worldwide have provided a large body of knowledge regarding the ecology of IAV in wild birds. Nevertheless, other issues of avian IAV evolution have not been fully elucidated, such as the complexity and dynamics of genetic interactions between the co-circulating IAV genomes taking place at a local-scale level or the phenomenon of frozen evolution. We investigated the IAV diversity in a mallard population residing in a single pond in the Czech Republic. Despite the relative small number of samples collected, remarkable heterogeneity was revealed with four different IAV subtype combinations, H6N2, H6N9, H11N2, and H11N9, and six genomic constellations in co-circulation. Moreover, the H6, H11, and N2 segments belonged to two distinguishable sub-lineages. A reconstruction of the pattern of genetic reassortment revealed direct parent-progeny relationships between the H6N2, H11N9 and H6N9 viruses. Interestingly the IAV, with the H6N9 subtype, was re-detected a year later in a genetically unchanged form in the close proximity of the original sampling locality. The almost absolute nucleotide sequence identity of all the respective genomic segments between the two H6N9 viruses indicates frozen evolution as a result of prolonged conservation in the environment. The persistence of the H6N9 IAV in various abiotic and biotic environmental components was also discussed.     

Species-area curves revisited: the effects of model choice on parameter sensitivity to environmental, community, and individual plant characteristics

Species-area curves are often employed to identify factors affecting biodiversity patterns. The aim of this study was to determine how model choice affects biological interpretation of SAC parameters at a small scale in wet, temperate meadows (?elezné hory Mts, Czech Republic). We estimated 88 species-area curves in nested plots on areas ranging from 0.01 to 4?m² at 22 localities using four different models (Arrhenius, Gleason, and their log transformations). Relationships were tested between the parameters of the fitted curves (slope and intercept) and a number of environmental and vegetation characteristics (environmental??water table, pH, nutrient availability, organic matter content; community??productivity, evenness; and individual plant??shoot cyclicity, persistence of connection among ramets, multiplication rate, dispersal ability). Species diversity was calculated for 0.01, 1, and 4?m². The corrected Akaike information criterion was used to identify the best model. The models differed in their sensitivity to environmental, community, and individual plant characteristics. The spatial scale that was the most suitable for revealing the factors underlying species diversity was the smallest considered (0.01?m²). The most important factors were spatial pattern in community structure (evenness, lateral spread), plant mobility (lateral spread and persistence), and soil properties. Although Gleason model showed better fit to data (both non-log and log transformation) and its intercept was more sensitive to tested biological characteristics, the Arrhenius model was more sensitive when correlating biological characteristics and slope. Choice of model according to best fit criteria restricts possibilities of biological interpretation and deserves further study.     

Diversity and ecology of desmids of peat bogs in the Jizerské hory Mts

The present study focuses on diversity and ecological preferences of desmids in peat bogs in the Jizerské hory Mts (Czech Republic). Altogether 76 desmid algae taxa have been recorded at 18 sites of the study area during our investigation in 2003–2006. Taxa Actinotaenium crassiusculum (De Bary) Teiling, Hyalotheca dissiliens var. tatrica Racib., Staurastrum avicula var. subarcuatum (Wolle) West & G. S. West, S. borgeanum Schmidle, S. simonyi var. semicirculare Coesel, Staurodesmus extensus var. isthmosus (Heimerl) Coesel, S. extensus var. vulgaris (Eichler & Racib.) Croasdale and S. spencerianus (Mask.) Teiling are new for the Czech Republic. In addition, several rare and remarkable taxa were also encountered. The species richness was relatively high in comparison to similar localities in the Czech Republic. Desmid distribution was influenced by pH and conductivity. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

Mitochondrial oxidative phosphorylation and energetic status are reflected by morphology of mitochondrial network in INS-1E and HEP-G2 cells viewed by 4Pi microscopy

Mitochondria in numerous cell types, especially in cultured cells, form a reticular network undergoing constant fusion and fission. The three dimensional (3D) morphology of these networks however has not been studied in detail to our knowledge. We have investigated insulinoma INS-1E and hepatocellular carcinoma HEP-G2 cells transfected with mitochondria-addressed GFP. Using 4Pi microscopy, 3D morphology changes responding to decreased oxidative phosphorylation and/or energetic status could be observed in these cells at an unprecedented 100 nm level of detail. In INS-1E cells cultivated at 11 mM glucose, the mitoreticulum appears predominantly as one interconnected mitochondrion with a nearly constant 262+/-26 nm tubule diameter. If cultured at 5 mM glucose, INS-1E cells show 311+/-36 nm tubules coexisting with numerous flat cisternae. Similar interconnected 284+/-38 nm and 417+/-110 nm tubules were found in HEP-G2 cells cultivated at 5 mM and hyperglycaemic 25 mM glucose, respectively. With rotenone inhibiting respiration to approximately 10%, disintegration into several reticula and numerous approximately 300 nm spheres or short tubules was observed. De-energization by uncoupling additionally led to formation of rings and bulky cisternae of 1.4+/-0.4 microm diameter. Rotenone and uncoupler acted synergically in INS-1E cells and increased fusion (ongoing with fission) forming bowl-like shapes. In HEP-G2 cells fission partially ceased with FCCP plus rotenone. Thus we have revealed previously undescribed details for shapes upon mitochondrial disintegration and clearly demonstrate that high resolution 3D microscopy is required for visualization of mitochondrial network. We recommend 4Pi microscopy as a new standard.     

Performance of optimized McRAPD in identification of 9 yeast species frequently isolated from patient samples: potential for automation

Background  

Rapid, easy, economical and accurate species identification of yeasts isolated from clinical samples remains an important challenge for routine microbiological laboratories, because susceptibility to antifungal agents, probability to develop resistance and ability to cause disease vary in different species. To overcome the drawbacks of the currently available techniques we have recently proposed an innovative approach to yeast species identification based on RAPD genotyping and termed McRAPD (Melting curve of RAPD). Here we have evaluated its performance on a broader spectrum of clinically relevant yeast species and also examined the potential of automated and semi-automated interpretation of McRAPD data for yeast species identification.     

Development of a microtiter plate-based method for determination of degradation profile of nitrophenolic compounds

A microtiter plate-based assay was developed for the automatic monitoring of degradation profile of the yellow-coloured nitrophenolic compounds. The method enables to reduce the intervals between measurements of substrate concentration to minutes and to overcome the problem of discontinuity of sampling typical for conventional methods. The concentrations of nitrophenolic compounds were calculated from the absorbance values determined automatically by BIOSCREEN C. Verification of the method was based on the comparison of results with the conventional HPLC method results. The values of the rate and saturation constants were comparable for both the microtiter plate-based assay and the conventional HPLC method. The automatic method described here seems to be efficient for the screening degradation studies, which requires the treatment of quantity of samples.