Population genetic structure of the European kestrel Falco tinnunculus in Central Poland

We analysed the genetic structure of the European kestrel population of Central Poland using nine highly polymorphic microsatellite loci. Samples were collected in two urban locations (Warsaw and ?ód?) and two rural areas. Sampling locations were at nearly equal distances from each other along an east to west line. We performed genotyping in a total of 99 birds. The results revealed the presence of a genetic structure in the population investigated. Bayesian clustering indicated that samples originated from more than one population. Genetic differentiation was less pronounced among the birds nesting in Warsaw and in the two rural sites, whereas all pairwise comparisons with the ?ód? population indicated moderate and significant genetic differentiation. The observed pattern of differentiation might have been caused by two factors: changes in allele frequency between seasons and/or the founding of the urban population of ?ód? from a different source population than the urban population from Warsaw. Additionally, we found a rather high gene flow among kestrels from the Warsaw urban area and the two investigated rural areas.     

Organisation of the endosperm and endosperm–placenta syncytia in bladderworts (Utricularia, Lentibulariaceae) with emphasis on the microtubule arrangement

Multinucleate cells play an important role in higher plants, especially during reproduction; however, the configurations of their cytoskeletons, which are formed as a result of mitosis without cytokinesis, have mainly been studied in coenocytes. Previous authors have proposed that in spite of their developmental origin (cell fusion or mitosis without cytokinesis), in multinucleate plant cells, radiating microtubules determine the regular spacing of individual nuclei. However, with the exception of specific syncytia induced by parasitic nematodes, there is no information about the microtubular cytoskeleton in plant heterokaryotic syncytia, i.e. when the nuclei of fused cells come from different cell pools. In this paper, we describe the arrangement of microtubules in the endosperm and special endosperm–placenta syncytia in two Utricularia species. These syncytia arise from different progenitor cells, i.e. cells of the maternal sporophytic nutritive tissue and the micropylar endosperm haustorium (both maternal and paternal genetic material). The development of the endosperm in the two species studied was very similar. We describe microtubule configurations in the three functional endosperm domains: the micropylar syncytium, the endosperm proper and the chalazal haustorium. In contrast to plant syncytia that are induced by parasitic nematodes, the syncytia of Utricularia had an extensive microtubular network. Within each syncytium, two giant nuclei, coming from endosperm cells, were surrounded by a three-dimensional cage of microtubules, which formed a huge cytoplasmic domain. At the periphery of the syncytium, where new protoplasts of the nutritive cells join the syncytium, the microtubules formed a network which surrounded small nuclei from nutritive tissue cells and were also distributed through the cytoplasm. Thus, in the Utricularia syncytium, there were different sized cytoplasmic domains, whose architecture depended on the source and size of the nuclei. The endosperm proper was isolated from maternal (ovule) tissues by a cuticle layer, so the syncytium and chalazal haustorium were the only way for nutrients to be transported from the maternal tissue towards the developing embryo.     

Effect of hyperthermia and ionizing radiation on the erythrocyte membrane

Spin-label studies of the effects of hyperthermia on the erythrocyte membrane revealed a decrease in the fluidity of lipids and changes in the state of membrane proteins. The rate of haemolysis in iso-osmotic glycerol solution was increased. Changes of most of the parameters studied when plotted in Arrhenius coordinates revealed a discontinuity (critical hyperthermic transition in the membrane) between 46 and 50 degrees C. Studies of the combined action of ionizing radiation (100 Gy) and hyperthermia (43 degrees C) showed the same direction of changes for (Na-K-Mg)-ATPase activity and spectra of membrane-bound maleimide spin label for both agents, but the additivity of changes depended on the parameter studied.     

Flavonoid profiling among wild type and related GM wheat varieties

Pleiotropic effects are one of the main concerns regarding genetically modified organisms (GMOs). This includes unintended side effects of the transgene or its genome insertion site on the regulation of other endogenous genes, which could potentially cause the accumulation of different secondary metabolites that may have not only an impact on diet as repeatedly worried by the public but also on the environment. Regarding amount and possible environmental effects, flavonoids represent the most prominent group of secondary metabolites in wheat. Many flavonoids function as signalling or defence molecules. We used a robust and reproducible analytical method to compare the flavonoid content of genetically modified (GM) wheat (Triticum aestivum L., Gramineae) expressing genes that confer increased fungal resistance with their non-GM siblings. The transgenes provide either a broad-spectrum fungal defence (chitinase/glucanase from barley) or bunt-specific resistance by a viral gene (KP4). Significant differences in flavonoid composition were found between different wheat varieties whereas different lines of GM wheat with increased antifungal resistance showed only minor differences in their flavonoid composition relative to their non-GM siblings. In a field test, no significant differences were detectable between infected and non-infected wheat of the same variety regardless of the presence of the transgene. Our results are in agreement with the hypothesis that the transgenes we used to increase wheat defence to fungal pathogens do not interfere with the flavonoid biosynthesis pathway. More significantly, the genetic background resulting from conventional breeding has a direct impact on the biological composition of flavonoids, and thus possibly on the environment.     

Functional utrastructure of Genlisea (Lentibulariaceae) digestive hairs

BACKGROUND AND AIMS: Digestive structures of carnivorous plants produce external digestive enzymes, and play the main role in absorption. In Lentibulariaceae, the ultrastructure of digestive hairs has been examined in some detail in Pinguicula and Utricularia, but the sessile digestive hairs of Genlisea have received very little attention so far. The aim of this study was to fill this gap by expanding their morphological, anatomical and histochemical characterization. METHODS: Several imaging techniques were used, including light, confocal and electron microscopy, to reveal the structure and function of the secretory hairs of Genlisea traps. This report demonstrates the application of cryo-SEM for fast imaging of whole, physically fixed plant secretory structures. KEY RESULTS AND CONCLUSION: The concentration of digestive hairs along vascular bundles in subgenus Genlisea is a primitive feature, indicating its basal position within the genus. Digestive hairs of Genlisea consist of three compartments with different ultrastructure and function. In subgenus Tayloria the terminal hair cells are transfer cells, but not in species of subgenus Genlisea. A digestive pool of viscous fluid occurs in Genlisea traps. In spite of their similar architecture, the digestive-absorptive hairs of Lentibulariaceae feature differences in morphology and ultrastructure.     

Antioxidative and prooxidative effects of quercetin on A549 cells

Quercetin, a common plant polyphenol, has been reported to show both antioxidant and prooxidant properties. We studied the effects of quercetin on A549 cells in in vitro culture. We found that low concentrations of the flavonoid stimulated cell proliferation and increased total antioxidant capacity (TAC) of the cells; while higher concentrations of the flavonoid decreased cell survival and viability, thiol content, TAC and activities of superoxide dismutase, catalase and glutathione S-transferase. Quercetin decreased production of reactive oxygen species in the cells but produced peroxides in the medium. The cellular effects of quercetin are therefore complex and include both antioxidant effects and induction of oxidative stress due to formation of reactive oxygen species in the extracellular medium.     

Does the cellular labile iron pool participate in the oxidation of 2',7'-dichlorodihydrofluorescein?

The fluorogenic probe 2',7'-dichlorodihydrofluorescein diacetate (H₂DCF-DA) is widely used for the estimation of oxidative stress in cells. It is known that 2',7'-dichlorodihydrofluorescein (H₂DCF), product of intracellular hydrolysis of H₂DCF-DA, is oxidized to the fluorescent compound, DCF, mainly by hydrogen peroxide (H₂O₂) in the presence of catalysts. The present study was aimed at answering the question whether the labile iron pool (LIP) may contribute to the oxidation of H₂DCF in cellular systems. The membrane-permeable lipophilic iron chelator salicylaldehyde isonicotinoyl hydrazone (SIH) was found to inhibit oxidation of the probe by H₂O₂ dependent on ferrous ions but not by peroxidase or superoxide dismutase in defined in vitro systems. When applied to cells, the probe inhibited considerably oxidation of H₂DCF in V79 Chinese hamster fibroblasts and two murine lymphoma L5178Y(LY) sublines (LY-R, LY-S) differing in LIP level, the extent of inhibition being greater in the LY-R line of higher LIP level. These results demonstrate that LIP is a significant factor determining the rate of intracellular H₂DCF oxidation.     

Upregulation and Mitochondrial Sequestration of Hemoglobin Occur in Circulating Leukocytes during Critical Illness,Conferring a Cytoprotective Phenotype

The classical role of hemoglobin in the erythrocytes is to carry oxygen from the lungs to the tissues via the circulation. However, hemoglobin also acts as a redox regulator and as a scavenger of the gaseous mediators nitric oxide (NO) and hydrogen sulfide (H₂S). Here we show that upregulation of hemoglobin (α, β and δ variants of globin proteins) occurs in human peripheral blood mononuclear cells (PBMCs) in critical illness (patients with severe third-degree burn injury and patients with sepsis). The increase in intracellular hemoglobin concentration is a result of a combination of enhanced protein expression and uptake from the extra-cellular space via a CD163-dependent mechanism. Intracellular hemoglobin preferentially localizes to the mitochondria, where it interacts with complex I and, on the one hand, increases mitochondrial respiratory rate and mitochondrial membrane potential, and on the other hand, protects from H₂O₂-induced cytotoxicity and mitochondrial DNA damage. Both burn injury and sepsis were associated with increased plasma levels of H₂S. Incubation of mononuclear cells with H₂S induced hemoglobin mRNA upregulation in PBMCs in vitro. Intracellular hemoglobin upregulation conferred a protective effect against cell dysfunction elicited by H₂S. Hemoglobin uptake also was associated with a protection from, and induced the upregulation of, HIF-1α and Nrf2 mRNA. In conclusion, PBMCs in critical illness upregulate their intracellular hemoglobin levels by a combination of active synthesis and uptake from the extracellular medium. We propose that this process serves as a defense mechanism protecting the cell against cytotoxic concentrations of H₂S and other gaseous transmitters, oxidants and free radicals produced in critically ill patients.     

Genetic validation of Aspergillus fumigatus phosphoglucomutase as a viable therapeutic target in invasive aspergillosis

Aspergillus fumigatus is the causative agent of invasive aspergillosis, an infection with mortality rates of up to 50%. The glucan-rich cell wall of A. fumigatus is a protective structure that is absent from human cells and is a potential target for antifungal treatments. Glucan is synthesized from the donor uridine diphosphate glucose, with the conversion of glucose-6-phosphate to glucose-1-phosphate by the enzyme phosphoglucomutase (PGM) representing a key step in its biosynthesis. Here, we explore the possibility of selectively targeting A. fumigatus PGM (AfPGM) as an antifungal treatment strategy. Using a promoter replacement strategy, we constructed a conditional pgm mutant and revealed that pgm is required for A. fumigatus growth and cell wall integrity. In addition, using a fragment screen, we identified the thiol-reactive compound isothiazolone fragment of PGM as targeting a cysteine residue not conserved in the human ortholog. Furthermore, through scaffold exploration, we synthesized a para-aryl derivative (ISFP10) and demonstrated that it inhibits AfPGM with an IC₅₀ of 2 μM and exhibits 50-fold selectivity over the human enzyme. Taken together, our data provide genetic validation of PGM as a therapeutic target and suggest new avenues for inhibiting AfPGM using covalent inhibitors that could serve as tools for chemical validation.