Irena Chvatalova

Genetic polymorphisms influence the susceptibility of men to sperm DNA damage associated with exposure to air pollution.

The purpose of the present study was to investigate the impact of carcinogenic polycyclic aromatic hydrocarbons and volatile organic compounds on sperm quality in a group of city policemen in Prague during a period of increased concentrations of ambient air-pollutants (winter season) compared to a period of low exposure (spring). Polymorphisms in metabolic genes (CYP1A1, EPHX1, GSTM1, GSTP1, GSTT1), folic acid metabolism genes (MTR, MTHFR) and DNA repair genes (XRCC1, XPD6, XPD23, hOGG1) were evaluated in these men as potential modifiers of associations between air pollution exposure and changes in sperm quality. The study population was a group of 47 policemen working in the center of the city. Seasonal differences in exposure were verified by ambient and personal monitoring. Markers of sperm injury included semen volume, sperm concentration, sperm morphology, sperm motility, and sperm DNA damage measured with the sperm chromatin structure assay The sperm chromatin structure assay (SCSA) includes a measure of DNA damage called DNA Fragmentation Index (DFI). The % of cells with detectable DFI (detDFI) by this assay includes sperm with either medium or high DNA damage; the term hDFI is used to define the % of sperm with only high DNA damage. The assay also detects immature sperm defined by high density staining (HDS). No significant differences were found in any of the standard semen parameters between the sampling periods except for vitality of sperms. Both DFI and HDS were significantly higher in winter than in spring samples for all men and for non-smokers. At the bivariate level, significant associations between hDFI or detDFI and polymorphisms of the repair genes XRCC1, XPD6 and XPD23 were observed. In multivariate models, polymorphisms of the genes XPD6, XPD23 and CYP1A1MspI were associated with hDFI and HDS. Moreover, HDS was significantly associated with polymorphisms in GSTM1 gene.

Chitin stimulates development and sporulation of arbuscular mycorrhizal fungi

Abstract Chitin added to sand-soil based cultivation substrates stimulated the root colonization, growth of extraradical mycelium and production of spores of arbuscular mycorrhizal fungi (AMF) in three experiments with Allium amppelloprasum , Plantago lanceolata and Lactuca sativa as host plants. Stimulation of AMF sporulation was also observed when autoclaved mycelium of Fusarium oxysporum was used instead of chitin. Increased numbers of actinomycetes in the substrate as a result of chitin treatment were recorded.

EFFECT OF DUAL INOCULATION WITH ARBUSCULAR MYCORRHIZAL FUNGI AND BACTERIA ON GROWTH AND MINERAL NUTRITION OF STRAWBERRY

ABSTRACT Micropropagated plants of Fragaria x ananassa (cv. Senga sengana) were post-vitro inoculated in two experiments with the arbuscular mycorrhizal fungi Glomus fasciculatum, Glomus etunicatum and or Glomus claroideum and with bacterial isolates obtained from plant rhizosphere, from mycorrhizal mycelium and from root-free substrate. In the first experiment, the inoculation with the bacterial isolate M30 (from mycorrhizal mycelium) and with arbuscular mycorrhizal fungi G. fasciculatum and G. etunicatum significantly increased the plant growth. Bacteria frequently stimulated development of mycorrhiza, particularly the growth and dehydrogenase activity of extraradical mycorrhizal mycelium. In the second experiment, the isolate-specific effects of bacteria and mycorrhizal fungi were found at different doses of phosphorus (P) and nitrogen (N). The interaction between nutritional regime, bacteria and the fungi may be a determining factor of mycorrhizal symbiosis efficiency as regards possible benefits in stimulation of plant growth.

THE EFFECT OF SELECTED PLANT HORMONES ON IN VITRO PROLIFERATION OF HYPHAE OF GLOMUS FISTULOSUM

Effects of N6-benzyladenine, kinetin, zeatin, N6-benzyladenosine, kinetin riboside, zeatin riboside, jasmonic acid, indole-3-acetic acid, indole-3-butyric acid, indole-3-propionic acid, abscisic acid and gibberellic acid on proliferation of hyphae of arbuscular mycorrhizal (AM) fungus Glomus fistulosum were studied under axenic conditions in vitro. The growth of intraradical hyphae of G. fistulosum was fully suppressed by 30 µM indole-3-acetic acid, but a perceptible decrease in the proliferation of the hyphae was observed already at 3 µM. Because such concentration is near the concentrations common in root tissues in vivo, the effect may be biologically significant. Similar effect was also observed for Glomus mosseae. Inhibitory effects of abscisic acid and cytokinins occurred only at very high, non-physiological concentrations. Ribosylated cytokinins showed stronger inhibition effects than their non-ribosylated counterparts. No stimulation of proliferation of hyphae by any plant hormone tested was observed.

Correlation of abundance of arbuscular mycorrhizal fungi, bacteria and saprophytic microfungi with soil carbon, nitrogen and phsophorus

A significant positive correlation between the concentration of CFU of soil saprophytic microfungi and total soil carbon content, organic matter (oxidizable carbon) and available phosphorus was observed in field collected soil samples. Concentration of CFU of culturable bacteria correlated negatively with soil organic matter. Specific length of hyphae of arbuscular mycorrhizal fungi in the soil correlated only with soil respiration rate. The results indicate that arbuscular mycorrhizal fungi are associated with soil microsites rich in some easily mineralizable fraction of soil, organic matter rather than with total or oxidizable organic carbon.

In vitro proliferation of Glomus fistulosum intraradical hyphae from mycorrhizal root segments of maize

Proliferation of intraradical hyphae of the arbuscular mycorrhizal fungus Glomus fistulosum was observed and measured in surface disinfected mycorrhizal maize root segments in an aseptic cultivation system. The maximum growth of hyphae proliferating from the root segments was observed at pH 6·3, and low concentrations of buffering substances stabilized the pH of the incubation medium (0·9 m m MES, 1 m m BIS-TRIS). The proliferation of intraradical hyphae was not influenced but the germination of chlamydospores of the mycorrhizal fungus was inhibited by an artificial inorganic soil solution at lowest dilutions. The percentage of root segments bearing proliferating hyphae and the growth of hyphae decreased with increasing concentration of phosphate in the incubation medium. All reduced sulphur-containing compounds tested (sulphite, dithionite and metabisulphite) suppressed the proliferation of hyphae completely.

Hybrid Sterility Locus on Chromosome X Controls Meiotic Recombination Rate in Mouse

Meiotic recombination safeguards proper segregation of homologous chromosomes into gametes, affects genetic variation within species, and contributes to meiotic chromosome recognition, pairing and synapsis. The Prdm9 gene has a dual role, it controls meiotic recombination by determining the genomic position of crossover hotspots and, in infertile hybrids of house mouse subspecies Mus m. musculus (Mmm) and Mus m. domesticus (Mmd), it further functions as the major hybrid sterility gene. In the latter role Prdm9 interacts with the hybrid sterility X 2 (Hstx2) genomic locus on Chromosome X (Chr X) by a still unknown mechanism. Here we investigated the meiotic recombination rate at the genome-wide level and its possible relation to hybrid sterility. Using immunofluorescence microscopy we quantified the foci of MLH1 DNA mismatch repair protein, the cytological counterparts of reciprocal crossovers, in a panel of inter-subspecific chromosome substitution strains. Two autosomes, Chr 7 and Chr 11, significantly modified the meiotic recombination rate, yet the strongest modifier, designated meiotic recombination 1, Meir1, emerged in the 4.7 Mb Hstx2 genomic locus on Chr X. The male-limited transgressive effect of Meir1 on recombination rate parallels the male-limited transgressive role of Hstx2 in hybrid male sterility. Thus, both genetic factors, the Prdm9 gene and the Hstx2/Meir1 genomic locus, indicate a link between meiotic recombination and hybrid sterility. A strong female-specific modifier of meiotic recombination rate with the effect opposite to Meir1 was localized on Chr X, distally to Meir1. Mapping Meir1 to a narrow candidate interval on Chr X is an important first step towards positional cloning of the respective gene(s) responsible for variation in the global recombination rate between closely related mouse subspecies.

Genetic, Biochemical, and Environmental Factors Associated with Pregnancy Outcomes in Newborns from the Czech Republic

Background Oxidative damage to placental DNA can result in negative pregnancy outcomes, including intrauterine growth restriction (IUGR) and low birth weight (LBW). Objective We investigated associations between the levels of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), a marker of oxidative DNA damage, in placental DNA, exposure to air pollutants during pregnancy, genetic polymorphisms in 94 selected genes, and pregnancy outcomes. Methods We studied 891 newborns who were IUGR- or LBW-affected or normal weight and were born between 1994 and 1999 in the Czech Republic in two districts with different levels of air pollution. Results We found nonsignificantly elevated 8-oxodG levels in the IUGR-affected group compared with the non-IUGR group (p = 0.055). Similarly, slightly elevated 8-oxodG levels were found in the LBW-affected group compared with the non-LBW group (p < 0.050). In univariate analyses, we identified single nucleotide polymorphisms associated with 8-oxodG levels, IUGR, and LBW. Exposure to particulate matter < 2.5 μm was associated with increased 8-oxodG levels in placental DNA and LBW. However, multivariate-adjusted logistic regression revealed that above-median 8-oxodG levels were the only factor significantly associated with IUGR [OR = 1.56; 95% confidence interval (CI), 1.07–2.37; p = 0.022]. Above-median levels of 8-oxodG were associated with LBW (OR = 1.88; 95% CI, 1.15–3.06; p = 0.011). Other variables associated with LBW included sex and gestational age of the newborn, maternal smoking, and haplotypes in the promoter region of the gene encoding mannose-binding lectin 2 (MBL2). The role of air pollutants in the risk of adverse pregnancy outcomes seemed to be less important. Conclusions Levels of 8-oxodG in placental DNA were associated with the risk of IUGR as well as LBW. Newborn’s sex, gestational age, maternal smoking, and genetic polymorphisms in the promoter region of the MBL2 gene were associated with LBW incidence.

Acrylonitrile exposure: the effect on p53 and p21WAF1 protein levels in the blood plasma of occupationally exposed workers and in vitro in human diploid lung fibroblasts

Acrylonitrile (ACN) is a compound widely used in the synthesis of a variety of organic products. It has been found that ACN is carcinogenic in rats, and some epidemiological studies also suggest a possible carcinogenic effect of ACN in humans. The aim of the present study was to assess the effect of ACN exposure on the expression of p53 and p21(WAF1) proteins in vitro as well as in vivo. In vitro ACN exposure of human lung fibroblasts resulted in the induction of both p53 and p21(WAF1) proteins. To evaluate the effect of ACN on the levels of p53 and p21(WAF1) proteins in the blood plasma of ACN-exposed workers, samples from 49 subjects (average age 44 years, 88% males, 12% females) exposed to ACN in the petrochemical industry (ACN concentration ranged from 0.05 to 0.3mg/m(3)) were analyzed. Subjects living in the same area (N=24, average age 43 years, 92% males, 8% females), but not working in the petrochemical industry were used as controls. No significant differences in either p53, or p21(WAF1) levels between the exposed and control groups were found. The expression of p53 was significantly higher in exposed non-smokers as compared with smokers (P=0.02). No effect of GSTM1 and GSTT1 genotypes on the expression of either protein was observed. Subjects with an EPHX high activity genotype had significantly higher p21(WAF1) expression as compared with genotypes with low or medium EPHX activity. We conclude that plasma levels of both proteins are not relevant biomarkers for occupational ACN exposure.

Effect of free-soil-inhabiting or root-associated microfungi on the development of arbuscular mycorrhizæ and on proliferation of intraradical mycorrhizal hyphæ

Colonization of maize roots by the arbuscular mycorrhizal fungusGlomus fistulosum and proliferation of intraradical distributive hyphæ was influenced by the free-soil-inhabiting sterile microfungus SC. Inoculation with this isolate significantly increased the percentage of the infected root length and changed the composition of population of microfungi in the cultivation substratum. Compared to a control without inoculation with any saprophytic microfungus, inoculation with the isolate SC significantly (by approx. 100%) increased the percentage of root segments showing the proliferation of mycorrhizal fungus, the mean number of proliferating hyphæ per active (proliferating) root segment being increased by approx. 200%. The plant growth was not affected by inoculation with any of the saprophytes tested.