Nitrogen deprivation in Fusarium oxysporum promotes mycotoxin production via intermediates in the Krebs cycle and unreported methylmalonyl-CoA mutase activity

Metabolomics - The identification of metabolomic dysregulation appears promising for the prediction of type 1 diabetes and may also reveal metabolic pathways leading to beta-cell destruction....     

Population size and identity influence the reaction norm of the rare,endemic plant Cochlearia bavarica across a gradient of environmental stress

Habitat degradation and loss can result in population decline and genetic erosion, limiting the ability of organisms to cope with environmental change, whether this is through evolutionary genetic response (requiring genetic variation) or through phenotypic plasticity (i.e., the ability of a given genotype to express a variable phenotype across environments). Here we address the question whether plants from small populations are less plastic or more susceptible to environmental stress than plants from large populations. We collected seed families from small (<100) versus large natural populations (>1,000 flowering plants) of the rare, endemic plant Cochlearia bavarica (Brassicaceae). We exposed the seedlings to a range of environments, created by manipulating water supply and light intensity in a 2 x 2 factorial design in the greenhouse. We monitored plant growth and survival for 300 days. Significant effects of offspring environment on offspring characters demonstrated that there is phenotypic plasticity in the responses to environmental stress in this species. Significant effects of population size group, but mainly of population identity within the population size groups, and of maternal plant identity within populations indicated variation due to genetic (plus potentially maternal) variation for offspring traits. The environment x maternal plant identity interaction was rarely significant, providing little evidence for genetically- (plus potentially maternally-) based variation in plasticity within populations. However, significant environment x population-size-group and environment x population-identity interactions suggested that populations differed in the amount of plasticity, the mean amount being smaller in small populations than in large populations. Whereas on day 210 the differences between small and large populations were largest in the environment in which plants grew biggest (i.e., under benign conditions), on day 270 the difference was largest in stressful environments. These results show that population size and population identity can affect growth and survival differently across environmental stress gradients. Moreover, these effects can themselves be modified by time-dependent variation in the interaction between plants and their environment.     

Histochemical procedures for the simultaneous visualization of sialic acid,its side chainO-acyl variants andO-sulphate ester

Journal of Molecular Histology -     

Efficient in vitro regeneration systems for Vaccinium species

Efficient protocols for shoot regeneration from leaf explants suitable for micropropagation as well as for the development of transgenic plants were developed for blueberry (Vaccinium corymbosum) and lingonberry (Vaccinium vitis-idaea) cultivars. Nodal segments were used to initiate in vitro shoot cultures of lingonberry cultivar ‘Red Pearl’ and southern highbush blueberry cultivar ‘Ozarkblue’. In order to develop an optimized regeneration procedure, different types and concentrations of plant growth regulators were tested to induce adventitious shoot regeneration on excised leaves from micropropagated shoots of both cultivars. The effect on percentage regeneration and number of shoots per explant was investigated. Results indicated that zeatin was superior to TDZ and meta-topolin in promoting adventitious shoot formation. A concentration of 20 μM zeatin was most effective in promoting shoot regeneration in both cultivars, in case of ‘Red Pearl’ along with 1 μM NAA. Shoots were either allowed to root in vitro on medium containing IBA or NAA or ex vitro in a fog tunnel. IBA was superior to NAA for induction of root development in vitro in both Vaccinium cultivars. Ex vitro rooting under high humidity was tested with cuttings from mature field-grown plants, from acclimatized tissue culture derived plants and with unrooted in vitro proliferated shoots planted directly. It was found that in vitro shoots rooted better under fog than cuttings from the other plant sources and rooting was equivalent to that achieved in vitro.     

Atmospheric photochemical transformations enhance 1,3-butadiene-induced inflammatory responses in human epithelial cells: The role of ozone and other photochemical degradation products

Chemistry of hazardous air pollutants has been studied for many years, yet little is known about how these chemicals, once reacted within urban atmospheres, affect healthy and susceptible individuals. Once released into the atmosphere, 1,3-butadiene (BD) reacts with hydroxyl radicals and ozone (created by photochemical processes), to produce many identified and unidentified products. Once this transformation has occurred, the toxic potential of atmospheric pollutants such as BD in the ambient environment is currently unclear. During this study, environmental irradiation chambers (also called smog chambers), utilizing natural sunlight, were used to create photochemical transformations of BD. The smog chamber/in vitro exposure system was designed to investigate the toxicity of chemicals before and after photochemical reactions and to investigate interactions with the urban atmosphere using representative in vitro samples. In this study, we determined the relative toxicity and inflammatory gene expression induced by coupling smog chamber atmospheres with an in vitro system to expose human respiratory epithelial cells to BD, BDs photochemical degradation products, or the equivalent ozone generated within the photochemical mixture. Exposure to the photochemically generated products of BD (primarily acrolein, acetaldehyde, formaldehyde, furan and ozone) induced significant increases in cytotoxicity, IL-8, and IL-6 gene expression compared to a synthetic mixture of primary products that was created by injecting the correct concentrations of the detected products from the irradiation experiments. Interestingly, exposure to the equivalent levels of ozone generated during the photochemical transformation of BD did not induce the same level of inflammatory cytokine release for either exposure protocol, suggesting that the effects from ozone alone do not account for the entire response in the irradiation experiments. These results indicate that BDs full photochemical product generation and interactions, rather than ozone alone, must be carefully evaluated when investigating the possible adverse health effects to BD exposures. The research presented here takes into account that photochemical transformations of hazardous air pollutants (HAPs) does generate a dynamic exposure system and therefore provides a more realistic approach to estimate the toxicity of ambient air pollutants once they are released into the atmosphere.     

Spontaneous Mutation in the Escherichia Coli Laci Gene

To gain more detailed insight into the nature and mechanisms of spontaneous mutations, we undertook a DNA sequence analysis of a large collection of spontaneous mutations in the N-terminal region of the Escherichia coli lacI gene. This region of circa 210 base pairs is the target for dominant lacI mutations (i-d) and is suitable for studies of mutational specificity since it contains a relatively high density of detectable mutable sites. Among 414 independent i-d mutants, 70.8% were base substitutions, 17.2% deletions, 7.7% additions and 4.3% single-base frameshifts. The base substitutions were both transitions (60%) and transversions (40%), the largest single group being G.C----A.T (47% of base substitutions). All four transversions were observed. Among the 71 deletions, a hotspot (37 mutants) was present: an 87-bp deletion presumably directed by an 8-bp repeated sequence at its endpoints. The remaining 34 deletions were distributed among 29 different mutations, either flanked (13/34) or not flanked (21/34) by repeated sequences. The 32 additions comprised 29 different events, with only two containing a direct repeat at the endpoints. The single-base frameshifts were the loss of a single base from either repeated (67%) or nonrepeated (33%) bases. A comparison with the spectrum obtained previously in strains defective in DNA mismatch correction (mutH, mutL, mutS strains) yielded information about the apparent efficiency of mismatch repair. The overall effect was 260-fold but varied substantially among different classes of mutations. An interesting asymmetry was uncovered for the two types of transitions, A.T----G.C and G.C----A.T being reduced by mismatch repair 1340- and 190-fold, respectively. Explanations for this asymmetry and its possible implications for the origins of spontaneous mutations are discussed.     

In vitro cell growth of marine archaeal-bacterial consortia during anaerobic oxidation of methane with sulfate

Anoxic sediment from a methane hydrate area (Hydrate Ridge, north-east Pacific; water depth 780 m) was incubated in a long-term laboratory experiment with semi-continuous supply of pressurized [1.4 MPa (14 atm)] methane and sulfate to attempt in vitro propagation of the indigenous consortia of archaea (ANME-2) and bacteria (DSS, Desulfosarcina/Desulfococcus cluster) to which anaerobic oxidation of methane (AOM) with sulfate has been attributed. During 24 months of incubation, the rate of AOM (measured as methane-dependent sulfide formation) increased from 20 to 230 micromol day(-1) (g sediment dry weight)(-1) and the number of aggregates (determined by microscopic counts) from 0.5 x 10(8) to 5.7 x 10(8) (g sediment dry weight)(-1). Fluorescence in situ hybridization targeting 16S rRNA of both partners showed that the newly grown consortia contained central archaeal clusters and peripheral bacterial layers, both with the same morphology and phylogenetic affiliation as in the original sediment. The development of the AOM rate and the total consortia biovolume over time indicated that the consortia grew with a doubling time of approximately 7 months (growth rate 0.003 day(-1)) under the given conditions. The molar growth yield of AOM was approximately 0.6 g cell dry weight (mol CH(4) oxidized)(-1); according to this, only 1% of the consumed methane is channelled into synthesis of consortia biomass. Concentrations of biomarker lipids previously attributed to ANME-2 archaea (e.g. sn-2-hydroxyarchaeol, archaeol, crocetane, pentamethylicosatriene) and Desulfosarcina-like bacteria [e.g. hexadecenoic-11 acid (16:1omega5c), 11,12-methylene-hexadecanoic acid (cy17:0omega5,6)] strongly increased over time (some of them over-proportionally to consortia biovolume), suggesting that they are useful biomarkers to detect active anaerobic methanotrophic consortia in sediments.     

Analysis of oxygen transport in a diffusion-limited model of engineered heart tissue

Cardiac tissue engineering has made notable progress in recent years with the advent of an experimental model based on neonatal cardiomyocytes entrapped in collage gels and purified basement membrane extract, known as "engineered heart tissues" (EHTs). EHTs are a formidable display of tissue-level contractile function and cellular-level differentiation, although they suffer greatly from mass transport limitations due to the high density of metabolically active cells and the diffusion-limited nature of the hydrogel. In this report, a mathematical model was developed to predict oxygen levels inside a one-dimensional, diffusion-limited model of EHT. These predictions were then compared to values measured in corresponding experiments with a hypoxia-sensitive stain (pimonidazole). EHTs were cast between two plastic discs, which allowed for mass transfer with the culture medium to occur in only the radial direction. EHTs were cultured for up to 36 h in the presence of pimonidazole, after which time they were snap-frozen, histologically sectioned, and stained for bound pimonidazole. Quantitative image analysis was performed to measure the distance from the culture medium at which hypoxia first occurs under various conditions. As tested by variation of simple design parameters, the trends in oxygen profiles predicted by the model are in reasonable agreement with those obtained experimentally, although a number of ambiguities related to the specific model parameters led to a general overprediction of oxygen concentrations. Based on the sensitivity analysis in the present study, it is concluded that diffusion-reaction models may offer relatively precise predictions of oxygen concentrations in diffusion-limited tissue constructs.     

Lectin binding in human skeletal muscle: a comparison of 15 different lectins

Summary Fifteen lectin-horseradish peroxidase conjugates have been used in a comprehensive histochemical study of human skeletal muscle. The staining patterns of many lectins were found to be coincident with the known distributions of types I, III, IV and V collagen, fibronectin and laminin. One lectin,Bandeiraea simplicifolia (BSA I), selectively stained capillaries in a blood group-specific manner, the significance of which is unknown. The results show that although lectins are useful cytochemical probes for identifying tissue glycoconjugates, lectin binding is not solely determined by monosaccharide specificity as lectins which interact with the same sugars may have completely different staining patterns. Factors such as accessibility, glycan conformation and oligosaccharide sequence also affect lectin binding in tissues. For these reasons, we conclude that a comprehensive histochemical investigation of tissue glycoconjugates should employ a large number of lectins, preferably with overlapping sugar specificities.