Plant communities of the montane mesophilous grasslands (Polygono bistortae–Trisetion flavescentis alliance) in central Europe: Formalized classification and syntaxonomical revision

Abstract

The research conducted here presents a syntaxonomical revision of the montane mesophilous meadows of the Polygono bistortae-Trisetion flavescentis alliance in central Europe – the Slovak part of the western and eastern Carpathians. These typical semi-natural grasslands occur mainly as small islands over the calcareous bedrocks. Associations of this alliance have tight relationships to the Arrhenatherion, Mesobromion and Nardo-Agrostion alliances. Formal definitions based on combination of the species groups were used regarding the diversity and geographical range of the Polygono bistortae-Trisetion flavescentis alliance. Following the formal definitions from the eight associations reported previously for Slovakia, only four of them can be placed within the Polygono bistortae-Trisetion flavescentis: Campanulo glomeratae-Geranietum sylvatici, Geranio sylvatici-Trisetetum, Crepido mollis-Agrostietum capillaries and Geranio-Alchemilletum crinitae. A comparison of traditional and formalized classification, and the advantages/disadvantages of the formalized classification are discussed.     

Does developmental acclimatization reduce the susceptibility to predation in newt larvae?

Many organisms respond to the heterogeneity of abiotic environmental conditions by plastic modifications of their phenotypes (acclimation or acclimatization). Despite considerable research efforts in this area, the beneficial (adaptive) effect of acclimation or acclimatization is still debated. We examined whether the development of newt larvae (Ichthyosaura alpestris) under different natural light and thermal conditions subsequently altered their susceptibility to predation in sun‐exposed versus shaded tanks in nature. During predation trials in various light and temperature conditions, newt larvae that developed in sun‐exposed warmer tanks consistently suffered from higher predation by dragonfly nymphs (Aeshna cyanea) compared to larvae from shaded or colder tanks. We conclude that higher sun exposure during embryonic and larval development negatively affects antipredator performance even in sun‐exposed tanks: this result is inconsistent with the beneficial acclimation hypothesis. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Design,synthesis, quantum chemical studies and biological activity evaluation of pyrazole–benzimidazole derivatives as potent Aurora A/B kinase inhibitors

Novel pyrazole–benzimidazole derivatives have been designed and synthesized. The entire target compounds were determined against cancer cell lines U937, K562, A549, LoVo and HT29 and were screened for Aurora A/B kinase inhibitory activity in vitro. The compounds 7a, 7b, 7i, 7k and 7l demonstrated significant cancer cell lines and Aurora A/B kinase inhibitory activities. Molecular modeling studies suggested the derivatives have bound in the active site of Aurora A kinase through the formation of four hydrogen bonds. Quantum chemical studies were carried out on these compounds to understand the structural features essential for activity. The cellular activity of 7k was also tested by immunofluorescence.     

Synthesis of Fluorinated Indoles as RNA Analogues

Nucleoside analogues are chemical means to investigate hydrogen bonds, base stacking, and solvation as the three predominant forces that are responsible for the stability of secondary structure of nucleic acids. To obtain deeper insight into the contributions of these interactions to RNA stability apart from the ones exerted by the predominant nucleosides we decided to synthesize some novel nucleic acid analogues where the nucleobases are replaced by fluoroindoles. Fluorinated indoles can be compared to fluorinated benzimidazoles to determine the role of nitrogen in five membered ring system. The synthesis of fluoroindole ribonucleosides is described here.     

Thiopurine S-Methyltransferase Gene Polymorphisms in a Healthy Slovak Population and Pediatric Patients with Inflammatory Bowel Disease

Thiopurine methyltransferase (TPMT) is a key component in thiopurine metabolism. There is an insufficient evidence about the distribution of the genotype frequencies of TPMT variants and frequencies of TPMT alleles associated with intermediate and deficient activity in a healthy Slovak population and pediatric patients with inflammatory bowel disease (IBD). TPMT variant alleles (*1,*2, *3A, *3B, and *3C) were determined in 114 children treated for IBD and in 281 healthy volunteers. Mutant alleles were present in 9/114 (7.89%) in the IBD patients and in 23/281 (8.19%) of probands. The distribution of the most frequent variants of TPMT gene was similar in a healthy population and patients with IBD.     

Enhanced Phase II Detoxification Contributes to Beneficial Effects of Dietary Restriction as Revealed by Multi-platform Metabolomics Studies

Dietary restriction (DR) has many beneficial effects, but the detailed metabolic mechanism remains largely unresolved. As diet is essentially related to metabolism, we investigated the metabolite profiles of urines from control and DR animals using NMR and LC/MS metabolomic approaches. Multivariate analysis presented distinctive metabolic profiles and marker signals from glucuronide and glycine conjugation pathways in the DR group. Broad profiling of the urine phase II metabolites with neutral loss scanning showed that levels of glucuronide and glycine conjugation metabolites were generally higher in the DR group. The up-regulation of phase II detoxification in the DR group was confirmed by mRNA and protein expression levels of uridinediphospho-glucuronosyltransferase and glycine-N-acyltransferase in actual liver tissues. Histopathology and serum biochemistry showed that DR was correlated with the beneficial effects of low levels of serum alanine transaminase and glycogen granules in liver. In addition, the Nuclear factor (erythroid-derived 2)-like 2 signaling pathway was shown to be up-regulated, providing a mechanistic clue regarding the enhanced phase II detoxification in liver tissue. Taken together, our metabolomic and biochemical studies provide a possible metabolic perspective for understanding the complex mechanism underlying the beneficial effects of DR.It has been known for more than 70 years that dietary restriction (DR)¹ can extend the life span and delay the onset of age-related diseases, based on an early rodent study showing such effects (1). However, not until the 1980s was DR recognized as a good model for studying the mechanism of or inhibitory measures for aging (2). So far, extensive studies employing model organisms such as yeasts, nematodes, fruit flies, and rodents have shown that DR has beneficial effects in most of the species studied (for a review, see Ref. 3). Most notably, a recent 20-year-long study showed that monkeys, the species closest to humans, also benefit from DR similarly (4). Although there has not been (or could not have been) a systematic study on the effects of DR on the human life span, several longitudinal studies strongly suggest that changes in dietary intake can affect the life span and/or disease-associated marker values greatly (5–7).This inverse correlation between dietary intake and long-term health strongly indicates that DR''s effects should involve metabolism, and that DR elicits the reorganization of metabolic pathways. It also seems quite natural that something we eat should affect the body''s metabolism. Despite this seemingly straightforward relationship between diet and metabolism, the mechanisms underlying the beneficial effects of DR are anything but simple. Intensive efforts, spanning decades, to understand the mechanisms of DR have identified several genes that might mediate the effects of DR, such as mTOR, IGF-1, AMPK, and SIRT1 (for a review, see Ref. 8). Still, most of them are involved in early nutrient-sensing steps, and specific metabolic pathways, especially those at the final steps actually responsible for the effects of DR, are largely unknown.This might be at least partially due to the fact that previous studies have focused mostly on genomic or proteomic changes induced by DR, instead of looking at changes in metabolism or metabolites directly. Metabolomics, which has gained much interest in recent years (9–11), might be a good alternative for addressing the mechanistic uncertainty of DR''s effects, with the direct profiling of metabolic changes elicited by environmental factors. In contrast to genomics or proteomics, which often employ DNA or proteins extracted from particular tissues, metabolomics studies mostly employ body fluids (i.e. urine or blood), which can reflect the metabolic status of multiple organs, enabling investigations at a more systemic level. In particular, urine has been used extensively to study the mechanism of external stimuli (i.e. drugs or toxic insults) at most major target organs, such as the lung, kidney, liver, or heart (12–18). Still, metabolomics studies of DR effects have been very limited. A few previous ones reported the changes in phenomenological urine metabolic markers with DR, without identification and/or validation of specific metabolic pathways reflected at the actual tissue or enzyme level (19, 20). Therefore, those studies fell short of providing a mechanistic perspective on DR''s effects. In addition, they employed either NMR or LC/MS approaches without validation across the two analytical platforms.Among the metabolic pathways that can directly affect the integrity of multiple organs, and hence long-term health, are phase II detoxification pathways (21). Typically, lipophilic endo/xenobiotics are metabolized first by a phase I system, such as cytochrome P450, which modifies the compounds so that they have hydrophilic functional groups for increased solubility. In many cases, though, these modifications might increase the reactivity of the compounds, leading to cellular damage. The phase II detoxification systems involve conjugation reactions that attach charged hydrophilic molecular moieties to reactive metabolites, thus facilitating the elimination of the harmful metabolites from body, ultimately reducing their toxicity (22). These systems are thus especially important in protecting cellular macromolecules, such as DNA and proteins, from reactive electrophilic or nucleophilic metabolites. The enzymes involved in these processes include glutathione-S-transferase (GST), sulfotransferase, glycine-N-acyltransferase (GLYAT), and uridinediphospho-glucuronosyltransferase (UGT), with the last enzyme being the most prevalent (23). The beneficial effects of phase II reactions have been particularly studied in relation to the mechanism of healthy dietary ingredients. It is well believed that many such foods can prevent cancers (hence the term “chemoprevention”) by inducing phase II detoxification systems (24–26). Although DR also substantially reduces the incidence of cancers, the exact mechanism remains elusive.Here, we employed multi-platform metabolomics to obtain metabolic perspectives on the beneficial effects of DR on rats. Our results about urine metabolomics markers suggest that DR enhances the phase II detoxification pathway, which was confirmed by means of conjugation metabolite profiling and changes in mRNA/protein expression levels of phase II enzymes in actual liver tissues. A possible molecular mechanism was also addressed through the exploration of Nuclear factor (erythroid-derived 2)-like 2 (Nrf-2) pathway activation upon DR. We believe the current study provides new metabolic insights into DR''s beneficial effects, as well as a workflow for studying DR''s effects from a metabolic perspective.     

Dilation of human atria: Increased diffusion restrictions for ADP,overexpression of hexokinase 2 and its coupling to oxidative phosphorylation in cardiomyocytes

Cardiac energy metabolism with emphasis on mitochondria was addressed in atrial tissue from patients with overload-induced atrial dilation. Structural remodeling of dilated (D) atria manifested as intracellular accumulation of fibrillar aggregates, lipofuscin, signs of myolysis and autophagy. Despite impaired complex I dependent respiration and increased diffusion restriction for ADP, no changes regarding adenylate and creatine kinase occurred. We observed 7-fold overexpression of HK2 gene in D atria with concomitant 2-fold greater activation of mitochondrial oxygen consumption by glucose, which might represent an adaption to increased energy requirements and impaired mitochondrial function by effectively joining glycolysis and oxidative phosphorylation.