Differentiation potential of the fetal rat liver-derived cells

Mesenchymal stem cells derived from bone marrow or several fetal tissues can be expanded and differentiated into other cell lines. The fetal liver is the source of early hematopoietic cells and also, as a fetal tissue, may be considered as a source of pluripotent stem cells. The differentiation potential of fetal rat liver cells have been examined. Freshly isolated liver cells from 14-d fetuses were cultured in Dulbecco medium supplemented with 10% FCS. The plastic-adherent cells were then passaged up to 10 times. Freshly isolated cells and cells from every passage were cultured in hematopoiesis-promoting environment that consists of methylcelulose supplemented with FCS, rat IL-3, human IL-6 and Epo. Parallely these cells were incubated in co-culture with rat muscle satellite cells (Dulbecco medium with 10% FCS and 10% HS) to examine their myogenic potential. Culture in methylcelulose resulted in a high number of GM and Mix colonies in case of freshly isolated liver cells and the number of colonies decreased according to the number of passages. In case of cells from 4th passage, there ware no hematopoietic colonies in culture. In contrast--freshly isolated cells were not able to fuse with rat satellite cells and form the myotubes. This ability appeared in plastic-adherent cells just from the second passage and increases to 5th passage. The cells from every next passage up to 10th when co-cultured with satellite cells participated in myotube formation at the same high level. This result may suggest that in the 14-d rat liver there exist at least two subpopulations of cells: the non-adherent hematopoietic cell population, and the population of plastic-adherent cells capable of differentiating into myotubes. Since the attempts to redifferentiate hematopoietic subpopulation into myopoiesis, or myopoietic subpopulation into hematopoiesis failed, it may be concluded that at least under our experimental conditions the fetal liver cells do not reveal the "plasticity" features.     

Relationship between postillumination burst of CO2 and enhancement of respiration in tall fescue leaves

The postillumination burst (PIB) of CO₂ and light-enhanced dark respiration (LEDR) depending on oxygen concentration, temperature, respiratory substrates and photorespiratory inhibitor aminoacetonitrile (AAN) were investigated in detached leaves of tall fescue (Festuca arundinacea) using a closed circuit system with an infrared gas analyzer. No PIB was observed in 1 % O₂ under temperature over the range from 15 °C to 35 °C. The rate of LEDR was about twice as low in 1 % O₂ as that in 21 and 50 % O₂ under all temperatures applied. The PIB was absent and LEDR decreased at 21 % O₂ following illumination of leaves for 1 hour at 1 % O₂. When 200 mM glycine or malate solutions were introduced into the leaves of tall fescue, the magnitudes of PIB increased by about 60 and 40 % and rate of LEDR by about 70 % and 40 %, respectively. Pyruvate and succinate were less effective in promotion of PIB and LEDR. AAN had a small stimulatory effect on PIB and LEDR (about 20 % and 10 %, respectively). The dependences between magnitudes of PIB and rates of LEDR were highly correlated (r=0.94). The results presented indicate that atmospheric concentration of oxygen during the period of photosynthesis of tall fescue leaves was necessary not only for occurrence of PIB and LEDR but also for production of substrate(s) (glycine and/or malate) for these phenomena.     

Interactive effects of temperature and heavy metals (Cd, Pb) on the elongation growth in maize coleoptiles

The effect of Cd and Pb on endogenous and IAA-induced elongation growth and medium pH of maize coleoptile segments incubated at 20, 25 and 30 °C was studied. It was found that the elongation of coleoptile segments and proton extrusion increased with the temperature and reached its maximum at 30 °C. For Cd, the maximal inhibition of endogenous and IAA-induced growth as well as medium acidification of coleoptile segments was observed at 25 °C. Meanwhile, Pb, irrespective of the temperature, diminished the growth of the segments by ca. 20%, increasing the acidification of the incubation medium. It was also found that in contrast to Cd, Pb accumulation in maize coleoptile segments did not correlate with temperature. The results suggest that the toxic effect of Cd on elongation growth of coleoptile segments is connected with the decrease of the PM H(+)-ATPase activity and probably with Cd-induced high acivity of IAA oxidase, whereas the effect of Pb did not depend on activity of any of the enzymes.     

Influence of 50 Hz magnetic field on human heart rate variability: linear and nonlinear analysis

This study investigated the problem of the influence of 50 Hz magnetic field (MF) on human heart rate variability (HRV). The exposure system was a commercial device for magnetotherapy, generating field of the strength of 500 microT at the center of the coil, 150-200 microT at the position of human subjects' heart and 20-30 microT at the position of subjects' head. The exposure protocols, applied randomly, were either "half hour MF-off/half hour MF-on" or "half hour MF-off/half hour MF-off." The phonocardiographic (PhCG) signal of 15 volunteers were obtained during exposure and used for calculation of time-domain HRV parameters (mean time between heart beats (N-N), standard deviation of time between heart beats (SDNN), and the number of differences of successive beat-to-beat intervals greater than 50 ms, divided by the total number of beat-to-beat intervals (pNN50)) and nonlinear HRV measures (approximate entropy (ApEn), detrended fluctuation scaling exponents). The protocol MF-off/MF-on was applied in nine subjects. Repeated measures ANOVA (RMANOVA) performed for Mf-off/MF-off protocol indicated no statistical difference among four 15 min intervals of HRV data (P value >20% for all parameters except for N-N, where P = 3.7%). RMANOVA followed by the post hoc Tukey test performed for Mf-off/MF-on protocol indicated a statistically significant difference during MF on for N-N (8% increase, P <.1%), SDNN (40% increase, P = 1.1%), and pNN50 (110% increase, P <.1%). The results of the analysis indicate that the changes of these parameters could be associated with the influence of MF.     

Nonhematopoietic stem cells of fetal origin--how much of today's enthusiasm will pass the time test?

Stem cells originating at fetal age are for many reasons superior as a material for the regenerative medicine purposes, when compared to their adult counterparts. While hematopoietic cells, isolated from fetal liver or cord blood, have been well known for a long time and have passed practical tests as clinical transplantation material, the non-hematopoietic cells are newly recognized, and the knowledge of their phenotype and differentiation potential is rather insufficient. We, and the others, have identified a subpopulation of cord blood cells phenotypically different from hematopoietic cells (CD34-, CD45-, CD29+, CD44+, CD51+, CD105+, SH-2, SH-3), in vitro plastic adherent, and capable of multilineage differentiation. The other candidates for multipotential stem cells are cells extracted from umbilical cord or placental tissue. The preliminary observations suggest, that these cells, phenotypically similar to the nonhematopoietic cord blood cells, are capable of extensive replication in vitro and of multilineage differentiation into a variety of tissues including cardiac muscle, bone and cartilage, adipocytes, and nerve cells. The other possible medical applications include "rejuvenation" of selected tissues and systems in senile patients, and therapeutical cloning - for both purposes, cells at the fetal stage of genetic regulation may be more useful than cells collected from adult donors. There is still, however, a high level of uncertainty concerning future medical applications of fetal stem cells. Their numbers and characteristics may differ from the preliminary observations, and their behavior in vivo may not fulfill the expectations originating from the in vitro studies. Finally, the autologous applications of stem cells collected at the stage of birth may need the involvement of technical and financial resources for the storage of frozen cell samples throughout the period of life of their potential user. Such procedure seems possible from technical point of view, but may be inadequately substantiated by the eventual advantages.     

Verzeichnis und ökologische Charakteristik der Fische der Donau

Ohne Zusammenfassung     

Biominerals and waxes of <Emphasis Type="Italic">Calamagrostis epigejos</Emphasis> and <Emphasis Type="Italic">Phragmites australis</Emphasis> leaves from post-industrial habitats

Vascular plants are able to conduct biomineralization processes and collect synthesized compounds in their internal tissues or to deposit them on their epidermal surfaces. This mechanism protects the plant from fluctuations of nutrient levels caused by different levels of supply and demand for them. The biominerals reflect both the metabolic characteristics of a vascular plant species and the environmental conditions of the plant habitat. The SEM/EDX method was used to examine the surface and cross-sections of the Calamagrostis epigejos and Phragmites australis leaves from post-industrial habitats (coal and zinc spoil heaps). The results from this study have showed the presence of mineral objects on the surfaces of leaves of both grass species. The calcium oxalate crystals, amorphous calcium carbonate spheres, and different silica forms were also found in the inner tissues. The high variety of mineral forms in the individual plants of both species was shown. The waxes observed on the leaves of the studied plants might be the initializing factor for the crystalline forms and structures that are present. For the first time, wide range of crystal forms is presented for C. epigejos. The leaf samples of P. australis from the post-industrial areas showed an increased amount of mineral forms with the presence of sulfur.     

Different strategies of Cd tolerance and accumulation in Arabidopsis halleri and Arabidopsis arenosa

Pseudometallophytes are commonly used to study the evolution of metal tolerance and accumulation traits in plants. Within the Arabidopsis genus, the adaptation of Arabidopsis halleri to metalliferous soils has been widely studied, which is not the case for the closely related species Arabidopsis arenosa. We performed an in-depth physiological comparison between the A. halleri and A. arenosa populations from the same polluted site, together with the geographically close non-metallicolous (NM) populations of both species. The ionomes, growth, photosynthetic parameters and pigment content were characterized in the plants that were growing on their native site and in a hydroponic culture under Cd treatments. In situ, the metallicolous (M) populations of both species hyperaccumulated Cd and Zn. The NM population of A. halleri hyperaccumulated Cd and Zn while the NM A. arenosa did not. In the hydroponic experiments, the NM populations of both species accumulated more Cd in their shoots than the M populations. Our research suggests that the two Arabidopsis species evolved different strategies of adaptation to extreme metallic environments that involve fine regulation of metal homeostasis, adjustment of the photosynthetic apparatus and accumulation of flavonols and anthocyanins.