Nutrients and disturbance history in two Plantago species: maternal effects as a clue for observed dichotomy between resprouting and seeding strategies

We assessed the role of nutrients and disturbance experienced by mothers (maternal effects) in the growth of progeny in a pot experiment using two Plantago species. Photosynthetic capacity, biomass allocation and fecundity were measured. Offspring of plants grown in nutrient poor conditions produced more leaves, spikes and longer leaves and in case of P. lanceolata , they had also higher photosynthetic capacity. The progeny of P. media mothers that had resprouted after disturbance was favored in nutrient poor conditions whereas the progeny of undisturbed plants was favored in nutrient rich conditions.
This study demonstrates that maternal effects may play a role in the success of either a seeding or a resprouting strategy in environments with different nutrient availability. Moreover, we showed that alteration of photosynthetic capacity, even during adult stages, is a mechanism through which maternal plants may impact their progeny.     

Clonal growth and sexual reproduction: tradeoffs and environmental constraints

Clonal growth confers a number of benefits on plants, but involves some costs as well. We examined whether seed reproduction is reduced in clonal plants due to these costs. Further, we investigated whether this relationship differs for species with optima at stressful or low‐productivity sites, as a possible indication that clonality acts as insurance against reduced seed reproduction in such conditions. We evaluated 472 species for which seed production per unit area had been determined, and employed this information together with data on seed mass, height at maturity, clonal traits and optimum habitat conditions (using Ellenberg indicator values). There was a strong hyperbolic relationship between seed output and seed mass, with a scaling coefficient of ?1, indicative of a simple tradeoff relationship. We performed analyses both with and without taking phylogeny into account. Reproductive output (i.e. the product of seed output and seed size) of was lower in clonal than in non‐clonal plants (in both with and without phylogeny incorporated in the analyses); within non‐clonal species, it was high in annuals and monocarpic plants relative to nonclonal perennials. Reproductive output was lower in clonal plants with extensive lateral spread. This may be due to lower mortality of such plants, which should favor reduced reproductive output, but direct resource tradeoff may also be involved. Reproductive output in all clonal and non‐clonal plants increased with the nutrient status and light level of the species’ optimum, and decreased with moisture. Because the proportion of clonal plants in vegetation is known to decrease along the same gradients, we can infer that as sexual reproduction becomes increasingly difficult in terms of these characteristics, clonal plants may capitalize on their capacity to bypass it. However, the relationships with habitat parameters disappeared in the phylogenetically corrected analysis, indicating that habitat preferences and reproductive output evolved together.     

Molecular modeling of glycosyltransferases involved in the biosynthesis of blood group A,blood group B,Forssman, and iGb3 antigens and their interaction with substrates

A terminal alpha1-3 linked Gal or GalNAc sugar residue is the common structure found in several oligosaccharide antigens, such as blood groups A and B, the xeno-antigen, the Forssman antigen, and the isogloboside 3 (iGb3) glycolipid. The enzymes involved in the addition of this residue display strong amino acid sequence similarities, suggesting a common fold. From a recently solved crystal structure of the bovine alpha3-galactosyltransferase complexed with UDP, homology modeling methods were used to build the four other enzymes of this family in their locked conformation. Nucleotide-sugars, the Mn2+ ion, and oligosaccharide acceptors were docked in the models. Nine different amino acid regions are involved in the substrate binding sites. After geometry optimization of the complexes and analysis of the predicted structures, the basis of the specificities can be rationalized. In the nucleotide-sugar binding site, the specificity between Gal or GalNAc transferase activity is due to the relative size of two clue amino acids. In the acceptor site, the presence of up to three tryptophan residues define the complexity of the oligosaccharide that can be specifically recognized. The modeling study helps in rationalizing the crystallographic data obtained in this family and provides insights on the basis of substrate and donor recognition.     

Comparative analysis of root sprouting and its vigour in temperate herbs: anatomical correlates and environmental predictors

Background and AimsRoot sprouting (RS), i.e. the ability to form adventitious buds on roots, is an important form of clonal growth in a number of species, and serves as both a survival strategy and a means of spatial expansion, particularly in plants growing in severely and recurrently disturbed habitats. Occurrence and/or success of plants in severely and recurrently disturbed habitats are determined by two components, namely the ability to produce adventitious buds on roots and the vigour of their production. As mechanisms behind different magnitudes of RS remain unclear, our study investigates: (1) whether the presence or absence of specific tissues in roots can promote or limit RS; and (2) whether there is some relationship between RS ability, RS vigour and species niche.MethodsWe studied RS ability together with RS vigour in 182 Central European herbaceous species under controlled experimental conditions. We used phylogenetic logistic regressions to model the presence of RS, RS vigour, the relationship between RS and anatomical traits and the relationship between RS and parameters of species niches.Key ResultsA quarter of herbs examined were able to produce adventitious buds on roots. They were characterized by their preference for open dry habitats, the presence of secondary root thickening and the occurrence of sclerified cortical cells in roots. Root sprouting vigour was not associated with any specific anatomical pattern, but was correlated with the environmental niches of different species, indicating that preferred disturbed and dry habitats might represent a selection pressure for more vigorous root sprouters than undisturbed and wet habitats.ConclusionsOur study shows that sprouting from roots is quite common in temperate dicotyledonous herbs. Two components of RS – ability and vigour – should be considered separately in future studies. We would also like to focus more attention on RS in herbs from other regions as well as on external forces and internal mechanisms regulating evolution and the functions of RS in both disturbed and undisturbed habitats.     

Macleya cordata and Prunella vulgaris in oral hygiene products - their efficacy in the control of gingivitis

A double-blind, placebo-controlled clinical trial was performed to investigate the effectiveness of a herbal-based dentifrice in the control of gingivitis. Forty volunteers completed the 84-day study. All subjects were balanced for parameters measured - plaque index (PI), community periodontal index of treatment needs (CPITN) and papillary bleeding index (PBI). The dentifrice was effective in reducing symptoms of gingivitis as evaluated by the CPITN and PBI indexes.     

VDAC2 and aldolase A identified as membrane proteins of K562 cells with increased expression under iron deprivation

We have shown previously that iron deprivation significantly stimulates the uptake of non-transferrin ferric iron from ferric citrate by erythroleukemia K562 cells and that this stimulation depends on protein synthesis. However, we have not detected increased expression of any known iron transport protein (Kovar J. et al. (2006) Blood Cells Mol Dis 37:95–99). Therefore, in order to identify membrane proteins of K562 cells with increased expression under iron deprivation, we employed the isolation of membrane proteins by two-phase partitioning system, protein separation by high-resolution 2D electrophoresis, computer differential analysis, and tandem mass spectrometry. Employing these techniques we identified two proteins with statistically significant upregulation, i.e., aldolase A (ALDA) and voltage-dependent anion channel 2 (VDAC2). The upregulation of aldolase A and VDAC2 in K562 cells under iron deprivation was also confirmed by western blot analysis. This is the first time when the control of aldolase A and VDAC2 levels by iron status of the cell is demonstrated.