Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on ...germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 – 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.
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•δ-HCH influences the germination success rate of Alnus glutinosa seeds.•Germination efficiency changes are progeny-dependent.•Alder seedling uptake of δ-HCH did not exceed 2.52% of the pollutant dose.•Alder seedling’s presence enhanced the effectiveness of δ-HCH removal by 20.85–35.89%.•Alder seedling’s hormones concentrations changed both negatively and positively to some extent during the exposure to δ-HCH.
The new screening method for rapid evaluation of major phenolic compounds in apples has been developed. Suitability of coupling HPLC/UHPLC separation with the diode-array detection and universal ...charged aerosol detection with respect to the presence of interfering substances was tested. Characteristics of both detection techniques were compared and method linearity, limits of detection and quantitation, and selectivity of them determined. Student t-test based on slopes of calibration plots was applied for the detailed comparison. The diode-array detection provided the best results regarding sensitivity and selectivity of the developed method in terms of evaluation of phenolics profiles. The response of the charged aerosol detector was negatively affected by co-eluting substances during rapid-screening analyses. Coulometric detection was used for advanced characterization of extracts in terms of antioxidant content and strength to obtain more complex information concerning sample composition. This detection also allowed evaluation of unidentified compounds with antioxidant activity. HPLC/UHPLC separation using a combination of diode-array and coulometric detectors thus represented the best approach enabling quick, yet complex characterization of bioactive compounds in apples.
The genomic destabilization associated with the adaptation of human embryonic stem cells (hESCs) to culture conditions or the reprogramming of induced pluripotent stem cells (iPSCs) increases the ...risk of tumorigenesis upon the clinical use of these cells and decreases their value as a model for cell biology studies. Base excision repair (BER), a major genomic integrity maintenance mechanism, has been shown to fail during hESC adaptation. Here, we show that the increase in the mutation frequency (MF) caused by the inhibition of BER was similar to that caused by the hESC adaptation process. The increase in MF reflected the failure of DNA maintenance mechanisms and the subsequent increase in MF rather than being due solely to the accumulation of mutants over a prolonged period, as was previously suggested. The increase in the ionizing-radiation-induced MF in adapted hESCs exceeded the induced MF in nonadapted hESCs and differentiated cells. Unlike hESCs, the overall DNA maintenance in iPSCs, which was reflected by the MF, was similar to that in differentiated cells regardless of the time spent in culture and despite the upregulation of several genes responsible for genome maintenance during the reprogramming process. Taken together, our results suggest that the changes in BER activity during the long-term cultivation of hESCs increase the mutagenic burden, whereas neither reprogramming nor long-term propagation in culture changes the MF in iPSCs.
Although the detection of several components of the fibroblast growth factor (FGF) signaling pathway in human embryonic stem cells (hESCs) has been reported, the functionality of that pathway and ...effects on cell fate decisions are yet to be established. In this study we characterized expression of FGF-2, the prototypic member of the FGF family, and its receptors (FGFRs) in undifferentiated and differentiating hESCs; subsequently, we analyzed the effects of FGF-2 on hESCs, acting as both exogenous and endogenous factors. We have determined that undifferentiated hESCs are abundant in several molecular-mass isoforms of FGF-2 and that expression pattern of these isoforms remains unchanged under conditions that induce hESC differentiation. Significantly, FGF-2 is released by hESCs into the medium, suggesting an autocrine activity. Expression of FGFRs in undifferentiated hESCs follows a specific pattern, with FGFR1 being the most abundant species and other receptors showing lower expression in the following order: FGFR1 --> FGFR3 --> FGFR4 --> FGFR2. Initiation of differentiation is accompanied by profound changes in FGFR expression, particularly the upregulation of FGFR1. When hESCs are exposed to exogenous FGF-2, extracellular signal-regulated kinases are phosphorylated and thereby activated. However, the presence or absence of exogenous FGF-2 does not significantly affect the proliferation of hESCs. Instead, increased concentration of exogenous FGF-2 leads to reduced outgrowth of hESC colonies with time in culture. Finally, the inhibitor of FGFRs, SU5402, was used to ascertain whether FGF-2 that is released by hESCs exerts its activities via autocrine pathways. Strikingly, the resultant inhibition of FGFR suppresses activation of downstream protein kinases and causes rapid cell differentiation, suggesting an involvement of autocrine FGF signals in the maintenance of proliferating hESCs in the undifferentiated state. In conclusion from our data, we propose that this endogenous FGF signaling pathway can be implicated in self-renewal or differentiation of hESCs.
Charles University Faculty of Pharmacy in Hradci Králové Deparment of Analytical Chemistry Candidate: Bc. Stanislava Košková Supervisor: Doc. PharmDr. Hana Sklenářová, Ph.D. Consultant: Ing. Radek ...Vávra, Ph.D. (VŠÚO Holovousy) Title of diploma thesis: Evaluation of selected substances in fruit by HPLC-DAD-CAD method Thisdiploma thesis was focused on determination of seven phenolic compounds, namely gallic acid, chlorogenic acid, epicatechin, rutin, phloridzin, quercetin, phloretin in twenty apple cultivars, that have been delivered by the Research and Breeding Institute of Pomology Holovousy s.r.o. For this purpose HPLC separation in reverse mode was used, using the column Omega Polar C 18 (150 mm x 4.6 mm; 5 µm). As the mobile phase the mixture of an ultrapure water acidified with the acetic acid to pH 2.8 and acetonitrile was used. A linear gradient was chosen with a gradual increase of the organic component from the initial 10 % to 50 % during 10 min of separation.This was followed with column equilibration - up to 12.50 min to 10 % organic component. The overall separation time was 12.50 min at a flow rate of 1 ml/min. Column temperature was set to 30 řC. Detection was performed using DAD (254, 280, 320 nm) and CAD detector (nebulizer temperature 25 řC). Part of this thesis is system...
Signals via fibroblast growth factor receptors (FGFRs) are involved in mesoderm induction events and may be also critical for early hematopoietic specification and proliferation of the hemangioblast. ...In vitro differentiated embryonic stem cells represent excellent system for the study of early hematopoietic commitment, particularly for understanding signals regulating the onset of hematopoietic differentiation. We have used human embryonic stem cells (hESCs) to study the expression of FGFR1, 2, 3, and 4 in undifferentiated cells and their differentiated progeny. Culturing hESCs i/ in high densities (protocol 1), ii/ without feeder layer of mouse embryonal fibroblasts and basic fibroblast growth factor (protocol 2), and iii/ in three-dimensional aggregates called embryoid bodies (protocol 3), was used to induce the differentiation. To achieve more directed and homogenous differentiation feeder-free hESCs were first subjected to the aggregation step (formation of embryoid bodies) that resembles the gastrulation process. This was followed by differentiation in monolayer in the presence of basic fibroblast growth factor (protocol 4). Such two-step differentiation protocol (5 + 10 days) was shown to activate ectodermal and mesodermal genes and form ectodermal and mesodermal cells (Schuldiner et al., PNAS 97:11307, 2000). The gene expression levels for all FGFRs were determined by quantitative real-time RT-PCR. Real-time RT-PCR results were normalized by comparison to the expression of ABL gene. We revealed that undifferentiated hESCs that were cultured with feeder cells and in low density express all four FGFRs in the following pattern: FGFR1 is highly expressed and dominant; FGFR3 is also strongly expressed; FGFR4 shows lower expression; and FGFR2 is only weakly expressed. This expression pattern was changed when hESCs grew and started to differentiate in high densities (protocol 1) or have initiated differentiation either by feeder cells and basic fibroblast growth factor withdrawal or by aggregation step (protocol 2 and 3). Two-fold upregulation of FGFR1 and FGFR4, and downregulation of FGFR3 characterize such changed expression pattern. Notably, the expression levels for all four FGFRs were increased when hESCc were subjected to the two-step differentiation protocol (protocol 4). Compared to the undifferentiated hESCs, FGFR1 and 4 exhibited 7-fold increase, and FGFR2 and 3 were found to be upregulated more than twice. In summary our results show that the expression of FGFRs tightly follows changing culture conditions that may direct hESCs to differentiate. Furthermore, strong upregulation of FGFR1 and 4 in prospective hESC-derived mesodermal cells suggests their involvement in the earliest stages of hematopoiesis. This research was supported in part by the Grant Agency of the Czech Republic (301/03/1122), Ministry of Health (MZ 00065269705), Ministry of Education, Youth, and Sports (MSM 432100001, LN 00A065), and Academy of Sciences of the Czech Republic (AV 0Z5039906).
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