Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Real-time study of the effect of different stress factors on lactic acid bacteria by electrochemical optical waveguide lightmode spectroscopy

Lactic acid bacteria play an important role in the fermentation of different food products. During the fermentation processes, lactobacilli are confronted with many inhibitor factors. These factors by themselves or in combination can influence the growth of lactic acid bacteria and their acidification capacity. The subject of our study was to monitor with a newly developed biosensing technique how the different chemical stress factors influence the survival of lactic acid bacteria. Electrochemical optical waveguide lightmode spectroscopy combines evanescent-field optical sensing with electrochemical control of surface adsorption processes. For optical sensing, a layer of indium tin oxide served as a high refractive index waveguide and as a conductive electrode, as well. Lactobacillus plantarum 2142 suspended in Jerusalem artichoke syrup was used in the experiments. Electrochemical optical waveguide lightmode spectroscopy measurements were undertaken by using OW 2,400c indium tin oxide coated waveguide sensors (MicroVacuum, Budapest, Hungary) and were performed in a flow-injection analyzer system. The bacterial cells were adsorbed in native form without any chemical binding on the surface of the sensor by ensuring polarizing potential (1V) and were exposed to different concentration of acetic acid/Jerusalem artichoke syrup, lactic acid/Jerusalem artichoke syrup and hydrogen peroxide/Jerusalem artichoke syrup solution for 1h, respectively, and the effect on bacteria cells was monitored. Results were compared to the traditional micro-assay method, and it can be assumed that after further investigations this new technique could be used in real-time application.     

Multidimensional Epistasis and the Transitory Advantage of Sex

Identifying and quantifying the benefits of sex and recombination is a long-standing problem in evolutionary theory. In particular, contradictory claims have been made about the existence of a benefit of recombination on high dimensional fitness landscapes in the presence of sign epistasis. Here we present a comparative numerical study of sexual and asexual evolutionary dynamics of haploids on tunably rugged model landscapes under strong selection, paying special attention to the temporal development of the evolutionary advantage of recombination and the link between population diversity and the rate of adaptation. We show that the adaptive advantage of recombination on static rugged landscapes is strictly transitory. At early times, an advantage of recombination arises through the possibility to combine individually occurring beneficial mutations, but this effect is reversed at longer times by the much more efficient trapping of recombining populations at local fitness peaks. These findings are explained by means of well-established results for a setup with only two loci. In accordance with the Red Queen hypothesis the transitory advantage can be prolonged indefinitely in fluctuating environments, and it is maximal when the environment fluctuates on the same time scale on which trapping at local optima typically occurs.     

Alterations in the subcellular distribution of 17β-estradiol dehydrogenase in porcine endometrial cells over the course of the estrous cycle

The uteri of German landrace gilts slaughtered at different days of the cycle were processed for immunocytochemistry and biochemical analyses. Plasma was collected for hormone assays. The monoclonal antibody F1 against the structure-bound 17-estradiol dehydrogenase of porcine endometrial epithelium was applied to rehydrated paraffin sections either as a direct, peroxidase-linked probe or in combination with a fluorescing secondary antibody. The oxidation of estradiol was measured in homogenates of tissue powdered in liquid nitrogen. Immunoreactivity was restricted to endometrial epithelium. In the glandular epithelium, faint dots of fluorescence became visible at day 4, which apparently coalesced to spherical structures of 2–4 m diameter at the cell basis between days 11 through 17 before disappearing by day 18. A similar distribution was observed for the oxidation products of diaminobenzidine beginning with a faint uniform staining and followed by the appearance of intensely stained basal bodies persisting until day 17. Essentially the same time course was seen in the luminal epithelium but with a different distribution. Immunoreactive material amassed in the apical region of the cells, but the conspicuous aggregations were absent. Time course and intensities of the immunological responses are matched by the enzymatic activity measured in parallel. Both correlate with the plasma progesterone levels, suggesting an induction of the enzyme by the hormone. An involvement of the cytoskeleton in the sequence of subcellular distribution patterns is discussed.     

Development of immunosensor based on OWLS technique for determining Aflatoxin B1 and Ochratoxin A

Mycotoxins are toxic secondary metabolites produced by a number of different fungi, and can be present in a wide range of food and feed commodities including cereal grains, oil seeds, dried fruits, apple juice, wine and meat products from animals fed contaminated meal. Many mycotoxins are highly resistant, and survive food processing, and therefore enter the food chain and provide a threat to human health. The optical waveguide lightmode spectroscopy (OWLS) technique has been applied to the detection of Aflatoxin and Ochratoxin in both competitive and in direct immunoassays. After immobilizing the antibody or antigen conjugate for the direct or indirect measurement, respectively, the sensor chip was used in flow-injection analyser (FIA) system. When using non-competitive method, sensor responses were obtained first only at analyte concentrations of 5-10 ng ml(-1). In both cases, the responses were very unstable. For competitive sensor investigation with the sensitized chip first the optimal dilution rate of monoclonal antibodies was determined, for the measurement of Ochratoxin A and Aflatoxin B1 the monoclonal antibody stock solution was diluted to 1 microg ml(-1) and to a 1:400 dilution, respectively. During the competitive measurement standard solutions were mixed with monoclonal antibodies at the appropriate concentration, the mixture was incubated for 1 min and injected into the OWLS system. The sensitive detection range of the competitive detection method was between 0.5 and 10 ng ml(-1) in both cases. After the establishment of the indirect method, barley and wheat flour samples were measured, and the results were in good correlation by those measured by enzyme linked immuno-sorbent assay (ELISA). Regression coefficient between the two methods for Ochratoxin and Aflatoxin was determined as 0.96 and 0.89, respectively.     

Patterns of molecular and phenotypic diversity in pearl millet [<Emphasis Type="Italic">Pennisetum glaucum</Emphasis>(L.) R. Br.] from West and Central Africa and their relation to geographical and environmental parameters

Background  

The distribution area of pearl millet in West and Central Africa (WCA) harbours a wide range of climatic and environmental conditions as well as diverse farmer preferences and pearl millet utilization habits which have the potential to lead to local adaptation and thereby to population structure. The objectives of our research were to (i) assess the geographical distribution of genetic diversity in pearl millet inbreds derived from landraces, (ii) assess the population structure of pearl millet from WCA, and (iii) identify those geographical parameters and environmental factors from the location at which landraces were sampled, as well as those phenotypic traits that may have affected or led to this population structure. Our study was based on a set of 145 inbred lines derived from 122 different pearl millet landraces from WCA.     

Quantifying the adaptive potential of an antibiotic resistance enzyme

For a quantitative understanding of the process of adaptation, we need to understand its "raw material," that is, the frequency and fitness effects of beneficial mutations. At present, most empirical evidence suggests an exponential distribution of fitness effects of beneficial mutations, as predicted for Gumbel-domain distributions by extreme value theory. Here, we study the distribution of mutation effects on cefotaxime (Ctx) resistance and fitness of 48 unique beneficial mutations in the bacterial enzyme TEM-1 β-lactamase, which were obtained by screening the products of random mutagenesis for increased Ctx resistance. Our contributions are threefold. First, based on the frequency of unique mutations among more than 300 sequenced isolates and correcting for mutation bias, we conservatively estimate that the total number of first-step mutations that increase Ctx resistance in this enzyme is 87 [95% CI 75-189], or 3.4% of all 2,583 possible base-pair substitutions. Of the 48 mutations, 10 are synonymous and the majority of the 38 non-synonymous mutations occur in the pocket surrounding the catalytic site. Second, we estimate the effects of the mutations on Ctx resistance by determining survival at various Ctx concentrations, and we derive their fitness effects by modeling reproduction and survival as a branching process. Third, we find that the distribution of both measures follows a Fréchet-type distribution characterized by a broad tail of a few exceptionally fit mutants. Such distributions have fundamental evolutionary implications, including an increased predictability of evolution, and may provide a partial explanation for recent observations of striking parallel evolution of antibiotic resistance.     

Evidence for a role of Smad6 in chick cardiac development.

Bone morphogenetic proteins (BMPs), members of the transforming growth factor-beta (TGF-beta) superfamily, are obligatory growth factors for early embryogenesis and heart formation. SMAD proteins transduce signals of the TGF-beta superfamily. We isolated chicken Smad6 (cSmad6), a member of inhibitory SMADs, and found its expression to be remarkably restricted to the developing heart, eyes, and limbs. cSmad6 expression was detected in the cardiogenic region of stage 5 embryos and overlapped Nkx2-5 and bmp-2, -4, and -7 expression. Throughout development, cSmad6 was expressed strongly in the heart, primarily in the myocardium, endocardium, and endocardial cushion tissue. Myocardial expression of cSmad6 was stronger in the forming septum, where highly localized expression of bmp-2 and -4 was also observed. Ectopically applied BMP-2 protein induced the expression of cSmad6, a putative negative regulator of BMP-signaling pathway, in anterior medial mesoendoderm of stage 4-5 embryos. In addition, blocking of BMP signaling using Noggin downregulated cSmad6 in cardiogenic tissue. cSmad1, one of the positive mediators of BMP signaling, was also expressed in cardiogenic region, but was not BMP-2 inducible. Our data suggest that cSmad6 has a role in orchestrating BMP-mediated cardiac development. We propose the possible mechanism of action of cSmad6 as modulating BMP signal by keeping a balance between constitutively expressed pathway-specific cSmad1 and ligand-induced inhibitory cSmad6 in the developing heart.