Nuclear DNA content variation within the genusTaraxacum (Asteraceae)

Nuclear DNA content was estimated using flow cytometry in 13 sections represented by 18 species of the genusTaraxacum using propidium iodide as the DNA stain. Investigated plants represented diploid, triploid and tetraploid species from sections considered both primitive and advanced, i.e.,T. sect.Dioszegia, Piesis, Glacialia, Mongolica, Scariosa, Obovata, T. pyrenaicum group,T. sect.Coronata, Palustria, Taraxacum (=Crocea),Kashmirana, Ruderalia andErythrosperma. Estimated nuclear 2C DNA content ranged from 1.74 pg in diploidT. linearisquameum (T. sect.Ruderalia) to 6.91 pg in tetraploidT. albidum (T. sect.Mongolica), demonstrating 3.97-fold variation. The lowest monoploid genome size 1C_x=0.87 pg was recorded inT. linearisquameum (T. sect.Ruderalia) together withT. brachyglossum (T. sect.Erythrosperma), and the highest one (1.73 pg) was recorded inT. albidum (T. sect.Mongolica), giving a 1.99-fold difference in the genus. No significant differences in genome size were observed withinT. sect.Ruderalia, similarly no intraspecific variation was observed inT. paludosum (T. sect.Palustria) andT. serotinum (T. sect.Dioszegia). These results indicate a high intraspecific stability of the trait. Preliminary comparisons of genome size in species/sections considered to be close relatives were made. These data give tentative additional evidence for the close phylogenetic relationship between sectionsPalustria andPiesis and against the close relationship between sectionsPiesis andDioszegia.     

A collection of yeast mutants selectively resistant to ionophores acting on mitochondrial inner membrane

Valinomycin and nigericin are potassium ionophores acting selectively on the mitochondrial inner membrane of Saccharomyces cerevisiae [Kovac, L., Bohmerova, E., Butko, P., 1982a. Ionophores and intact cells. I. Valinomycin and nigericin act preferentially on mitochondria and not on the plasma membrane of Saccharomyces cerevisiae. Biochim. Biophys. Acta 721, 341-348]. However, the molecular mechanism of their action is not understood. Here we show that their selective effect on mitochondrial membranes is not caused by the pleiotropic drug resistance system. To identify the molecular components mediating the action of ionophores we isolated several mutants specifically resistant to valinomycin and/or nigericin. In contrast to the parental strain, these mutants do not form respiratory-deficient cells in the presence of ionophores. Moreover, all mutants harbor extensively fragmented mitochondria and these morphological defects can be alleviated by the ionophores. Interestingly, we observed that these mitochondrial defects may be accompanied by changes in vacuolar dynamics. Our results demonstrate that the classical genetic approach can provide a starting point for the analysis of components involved in the action of ionophores on mitochondria-related processes in eukaryotic cell.     

Music as an auditory stimulus in stroke patients

Auditory stimulation increases mean blood flow velocity (MBFV) in the middle cerebral artery (MCA) in healthy individuals. Our aim was to monitor such changes in the affected MCA of patients with acute ischemic stroke (AIS). The study included 66 non-thrombolysed patients with AIS who were divided into groups according to National Institutes of Health Stroke Scale (NIHSS) score. Group I consisted of patients with NIHSS score 10 and group II with NIHSS score > or =11. Affected MCA was insonated with transcranial Doppler (TCD). MCA MBFVs were monitored during listening to music for 30 minutes. The first response of MBFV increase was measured as time (Tmax) and percentage of amplitude change (Amax). Pearson Chi-Square test was used. In 78.85% of patients there was a significant increase in MBFV compared to baseline values as a reaction to the music. There was no significant difference in Tmax or Amax between the two groups. However, a trend of longer Tmax was observed with every 2 NIHSS score increase. Music is an auditory stimulus in stroke patients and can be measured with TCD as MCA MBFV increase. Although our study showed no significant change of reaction time with the severity of stroke, a trend of prolonged Tmax was observed with NIHSS score increase.     

Towards an integration of psychoanalysis and neurobiology in 21st century

The "inner world" of the mind was, in the past, the traditional preserve of psychoanalysis and related disciplines, and it was therefore placed at the margins of neural science. During 1990-ies numerous investigations in the field of neuroscience have led to significant findings, which explain biological correlates ofpsychological functions. There are much scientific evidence that support association between psychoanalysis and neuroscience. Psychoanalysis offers a unique in-depth perspective on the psychology of human motivation, and furthermore has contributions both to make and to receive in the gathering scientific integration.     

Genetic map of AFLP markers in the rat (Rattus norvegicus) derived from the H x B/Ipcv and B x H/Cub sets of recombinant inbred strains

The amplified fragment length polymorphism (AFLP) technique has been used to enhance marker density in a large set of recombinant inbred strains (H × B and B × H) derived from a spontaneously hypertensive rat (SHR/OlaIpcv) and a Brown-Norway (BN.lx/Cub) inbred strain. Thirteen different primer combinations were tested and a total of 191 polymorphic bands were detected. From these polymorphic bands 89 AFLP markers could be assigned to specific chromosomes. Several of these AFLP markers were mapped to regions with low marker density, thus filling up gaps in the existing genetic map of these recombinant inbred strains. These results substantiate the value of the AFLP technology in increasing marker density in genetic maps.     

Hormone replacement therapy--is there a place for its use in neurology?

Stroke remains the third leading cause of mortality in developed countries despite declining tendency over the past decades. As the leading cause of disability and second cause of dementia, primary prevention should be the main way to fight the disease, since therapy is not efficient enough. Several observations pointed to estrogen as a protective agent that may reduce stroke risk, however, studies have shown conflicting data. There is no strong evidence that hormone replacement therapy (HRT) increases stroke risk. Several studies have shown that HRT may reduce the risk of fatal stroke. Conflicting results have been found for Alzheimer's disease and HRT as well. An association between higher serum concentration of estradiol and decreased risk of cognitive decline has been found in some studies, supporting the hypothesis that estrogen concentration may play a significant role in brain protection. Having in mind results of recent randomized trials, it is suggested that HRT should not be recommended on general basis for the primary or secondary prevention of cardiovascular/cerebrovascular diseases or for primary prevention of degenerative diseases such as Alzheimer's disease. Osteoporosis, cognitive decline and climacteric symptoms that are likely to impact on quality of life, speak in favor for recommendation of HRT use. On the other side, family history of breast carcinoma, mastopathy, thromboembolism, in certain cases gallbladder disease, will discourage the commencement of HRT. Respecting the patient's preferences and having benefits and risks in mind as well as science advisory statements, individual counseling regarding HRT should be the leading concept in the healthcare of postmenopausal women.     

Biosorption of cadmium ions by different yeast species

Toxicity and accumulation of Cd2+ in yeasts were studied in eight different yeast species. The adaptation to toxic concentration of this metal was dependent on the production of extracellular yeast glycoproteins. The highest concentration of Cd2+ ions in the growth medium was tolerated by a Hansenula anomala, strain while the lowest tolerance was found by the strain of species Saccharomyces cerevisiae. Extracellular glycoproteins of Hansenula anomala absorbed nearly 90% of the total content of Cd2+ ions bound by yeast cells, while extracellular glycoproteins of Saccharomyces cerevisiae bound only 6% of the total amount of cadmium. This difference is caused by the variable composition of the saccharide moiety in the extracellular glycoproteins. The composition of extracellular glycoproteins changed during the adaptation of the yeast cells to the presence of Cd2+ ions.     

Nutrient availability affected shallow-lake ecosystem response along the Late-Glacial/Holocene transition

In temperate headwater streams, intra-annual variation in energy input is critical in influencing aquatic food webs. We used stable isotope analysis to explore how seasonal variation in energy sources likely influenced invertebrate composition together with isotopic niche patterns of a cyprinid minnow, the chubbyhead barb Enteromius anoplus within a southern temperate headwater stream. Basal food sources had lower carbon and nitrogen stable isotope values in winter and spring compared to summer and autumn. Seasonal variations in the aquatic invertebrate communities were depicted by differences in the composition of gatherer and predator groups together with occurrence of scrapers in summer. Temporal changes in the isotopic values of these invertebrate groups appeared to coincide with that of basal food resources. The chubbyhead barb exhibited seasonal variation that was characterised by larger isotopic niches in winter compared to summer. Tissue-specific comparisons revealed larger isotope niche size based on fin tissue than muscle tissue during the cold period but comparable isotope niche sizes in the warm period. Contrasting inter-tissue isotopic niche patterns, the cold period suggested the likelihood of tissue physiological differences. Comparable isotopic niche patterns in summer and autumn suggested the possibility of synchronised physiological processes for both tissues. This suggested the potential for fin tissue as non-lethal alternative when inferring food web dynamics for this species.

     

The role of individual caspases in cell death induction by taxanes in breast cancer cells

Background

In previous study we showed that caspase-2 plays the role of an apical caspase in cell death induction by taxanes in breast cancer cells. This study deals with the role of other caspases. We tested breast cancer cell lines SK-BR-3 (functional caspase-3) and MCF-7 (nonfunctional caspase-3).

Methods and results

Using western blot analysis we demonstrated the activation of initiator caspase-8 and -9 as well as executioner caspase-6 and -7 in both tested cell lines after application of taxanes (paclitaxel, SB-T-1216) at death-inducing concentrations. Caspase-3 activation was also found in SK-BR-3 cells. Employing specific siRNAs after taxane application, suppression of caspase-3 expression significantly increased the number of surviving SK-BR-3 cells. Inhibition of caspase-7 expression also increased the number of surviving SK-BR-3 and MCF-7 cells. On the other hand, suppression of caspase-8 and caspase-9 expression had no significant effect on cell survival. However, caspase-9 seemed to be involved in the activation of caspase-3 and caspase-7. Caspase-3 and caspase-7 appeared to activate mutually. Furthermore, we observed a significant decrease in mitochondrial membrane potential (flow cytometric analysis) and cytochrome c release (confocal microscopy, western blot after cell fractionation) from mitochondria in SK-BR-3 cells. No such changes were observed in MCF-7 cells after taxane treatment.

Conclusion

We conclude that the activation of apical caspase-2 results in the activation of caspase-3 and -7 without the involvement of mitochondria. Caspase-9 can be activated directly via caspase-2 or alternatively after cytochrome c release from mitochondria. Subsequently, caspase-9 activation can also lead to caspase-3 and -7 activations. Caspase-3 and caspase-7 activate mutually. It seems that there is also a parallel pathway involving mitochondria that can cooperate in taxane-induced cell death in breast cancer cells.     

Ergebnisse der Pollen- und Grossrestanalyse des Moors «Velanská cesta» in Südböhmen

Die Abhandlung fasst die Ergebnisse der Pollen- und Grossrestanalyse aus dem Torflager «Velanská cesta» am südlichen Rand des Beckens T?eboňská pánev (Wittingauer Becken) in Südböhmen zusammen. Auf Grund dieser Resultate wurde eine Rekonstruktion der Vegetation des Moors selbst und auch der Vegetation seiner Umgebung ab Beginn der Sedimentation in jüngerer Dryaszeit bis heute vorgenommen.