Effects Of Environmental Stress Factors Research Articles

Effects of environmental stress factors on the actin cytoskeleton of fungi and plants: Ionizing radiation and ROS.

Actin is an abundant and multifaceted protein in eukaryotic cells that has been detected in the cytoplasm as well as in the nucleus. In cooperation with numerous interacting accessory-proteins, monomeric actin (G-actin) polymerizes into microfilaments (F-actin) which constitute ubiquitous subcellular higher order structures. Considering the extensive spatial dimensions and multifunctionality of actin superarrays, the present study analyses the issue if and to what extent environmental stress factors, specifically ionizing radiation (IR) and reactive oxygen species (ROS), affect the cellular actin-entity. In that context, this review particularly surveys IR-response of fungi and plants. It examines in detail which actin-related cellular constituents and molecular pathways are influenced by IR and related ROS. This comprehensive survey concludes that the general integrity of the total cellular actin cytoskeleton is a requirement for IR-tolerance. Actin's functions in genome organization and nuclear events like chromatin remodeling, DNA-repair, and transcription play a key role. Beyond that, it is highly significant that the macromolecular cytoplasmic and cortical actin-frameworks are affected by IR as well. In response to IR, actin-filament bundling proteins (fimbrins) are required to stabilize cables or patches. In addition, the actin-associated factors mediating cellular polarity are essential for IR-survivability. Moreover, it is concluded that a cellular homeostasis system comprising ROS, ROS-scavengers, NADPH-oxidases, and the actin cytoskeleton plays an essential role here. Consequently, besides the actin-fraction which controls crucial genome-integrity, also the portion which facilitates orderly cellular transport and polarized growth has to be maintained in order to survive IR.

Botanical Role, Sources, Bioactive Compounds in Medicinal and Genetically Modified Crops

The chemical compounds extracted from medicinal plants have potential to evoke mental and social sensations in addition to maintain physical health. . Species of Asteraceae and Liliaceae play significant cardiovascular roles irrespective of exploring their toxicological aspects. Carbohydrates, proteins, lipids, nucleotides, fats, and steroids are the primary organic compounds which are involved in metabolism of essential developmental and growth functions of plants. The detrimental effects of environmental stress factors are suppressed by the gene expressions of ion transporters and water channel proteins present in the cell membranes incorporated with the up or downregulation of osmo-proctant osmolytes and essential proteins such as HSP and chaperones. Sunflower (Helianthus annuus L.) is an important crop known for its food, forage, and silage constituents. It is a prominent specie in Asteraceae family. Its seeds are enriched with edible oil-world’s fourth largest oil source. The mineral elements, dietary fibers, and secondary metabolites such as carotenoids, flavonoids, tocopherols, saponins, tannins, alkaloids, chlorogenic acid, caffeic acid, peptides, phytosterols, triterpene glycosides, and vitamins contribute towards nutraceutical roles. Pot marigold (Calendula officinalis) possesses antibiotic, anti-inflammatory, and antifungal properties which allow its applications in preventing muscle spasms, treating sore throat and ulcers of duodenum and stomach, soothing eczema, healing wounds, and relieving rashes.

Proteomic analysis of typical and genetically altered strains of <i>Vibrio cholerae</i> serogroup O1, biovar El Tor

Objective — comparative study of protein expression in typical and genetically altered Vibrio cholerae strains of O1 serogroup, biovar El Tor by means of proteomic analysis.Materials and methods. Clinical V. cholerae strains — typical strain, M106 (Astrakhan, 1970) and genetically altered one, M1509 (Moscow, 2012) — were used as model ones. Strains were cultivated in LB broth (pH7.2). Then, cell and exoprotein lysate fractions were obtained and investigated in 2D electrophoresis. Different protein stains were examined using mass spectrometry. Survivability of V. cholerae strains under osmotic and oxidative stresses was studied during incubation of the strains in 3 M NaCl solution or 20 mM H2O2 solution.Results and discussion. When analyzing cell lysates, significant differences in protein expression with known function between studied strains were not detected. The great majority of identified proteins in the lysates is functionally associated with carbohydrate metabolism, amino acid metabolism, and energy processes in a cell. At the same time, exoprotein fraction of M1509 genovariant contained increased amount of proteins (peroxidase, superoxide dismutase, thioredoxin, outer membrane proteins OmpW, OmpT) protecting the cells of cholera vibrio from effect of stress factors of the environment. Further study of the resistance to osmotic and oxidative stresses revealed better survivability in the genovariant when exposed to the stated factors.Conclusion. The data of proteomic analysis of the typical and genetically altered V. cholera strains, biovar El Tor, testify to high levels of expression of the proteins that provide for vibrio resistance to the effect of environmental stress factors in genovariants, which is possibly one of the causes of their wide dissemination. In addition, the results obtained will allow for identification of new biomarkers which can be used for differentiation of typical strains and genovariants of V. cholerae, biovar El Tor.

Efficiency of pepper seed invigoration through hydrogen peroxide priming to improve in vitro salt and drought stress tolerance

Priming is considered a potential strategy to counteract the adverse effects of environmental stress factors via the exogenous application of chemicals to improve plant tolerance. In this context, herein, the priming of pepper seeds (Capsicum annuum L. Tunisian var. ‘Baklouti Medenine’) using different concentrations of hydrogen peroxide (H2O2; 1–100 mM) was carried out in in vitro culture subjected to abiotic stress. Seed germination was carried out on Murashige and Skoog (MS) medium, supplemented with stress-inducing agents: sodium chloride (NaCl 85.55 mM) or polyethylene glycol (PEG 6000, 3%) for induction of salt or drought conditions, respectively. The results revealed that depending in priming concentration and medium culture, H2O2 priming enables faster germination for both salt- or drought-stressed seeds, associated with the decline of mean germination time (MGT), time taken for cumulative germination to reach 50% of its maximum (t50) and germination rate (GR), and the increase in germination index (GI). The primed seeds showed great uniformity, reflected by a reduction in time interval between 25% and 75% of viable seeds to germinate (U7525). Under both stress-free and drought stress conditions, priming at 10 mM H2O2 showed a significant decrease of MGT, t50, and GR and an increase in GI. Similarly, the best uniformity (U7525) was obtained at this priming level. Following salinity stress, application of a low concentration of H2O2 (1 mM) reduced t50 and increased GI, versus no significant changes for MGT and GR and a regression in uniformity. No positive effect was noted for H2O2 priming in the final germination percentage and seedling vigor for all cultures. This study suggests that H2O2 priming invigorates pepper seed germination and alleviates the negative effects of salt and drought via the enhancement of seed tolerance.

Environmental rearing conditions are key determinants of changes in immune gene expression patterns in shrimp midgut

The super-intensive BioFloc Technology (BFT) system has been highlighted as a promising eco-friendly alternative to the traditional shrimp rearing systems. To gain insight into the impact of environmental rearing conditions on shrimp intestinal immunity, we assessed the expression profile of key immunological genes in the midgut of Litopenaeus vannamei shrimp reared in two contrasting culture systems: the indoor super-intensive BFT and the outdoor intensive Green-Water System (GWS). From the 30 analyzed genes, the expression levels of 25 genes were higher in the midgut of shrimp reared in BFT than in GWS. The main functional categories represented in BFT-shrimp were the prophenoloxidase-activating system, immune signaling, antimicrobial peptides, and RNA interference pathway. Comparatively, only the RNAi pathway gene Dicer-1 (LvDcr1) was more expressed in animals from the GWS group. However, despite the differences in gene expression, the total midgut bacterial abundance was similar between the experimental groups. Altogether, our results suggest that the microbial-rich environment offered by the BFT system can be acting as an immunostimulant by altering the immune expression profile of the midgut. The gene expression level found in GWS animals could be related to the chronic presence of the IMNV in the Brazilian Northeast. Knowing the effects of environmental stress factors on the intestinal immune defenses can provide an in-depth understanding of the relationship between cultivated shrimp and the major pathogens affecting the shrimp industry.

Chemical Composition of Winter Rape Seeds Depending on the Biostimulators Used

Plant growth regulators may reduce the negative effect of environmental stress factors and can contribute to increasing the quality and quantity of the yield. The aim of the research was to determine the effect of biostimulators on the quality of seeds of three winter rape morphotypes. Three varieties of winter rape were used: Poznaniak (population variety), PX104 (hybrid variety restored with a semi-dwarf growth type) and Konkret (hybrid variety restored with a traditional growth type). The varieties were exposed to three treatments: the biostimulator Tytanit®, the biostimulator Asahi®SL and the biostimulator Silvit®, and the control with no biostimulators. Seeds were analysed for content of crude fat, total fat and crude fibres. The biostimulators reduced total protein content (on average from 0.8 to 1.75 g·kg−1 of d.m.) and increased the concentration of crude fat (on average from 0.71 to 1.93 g·kg−1 of d.m.) and crude fibre (on average from 0.15 to 0.84 g·kg−1 of d.m.) compared to the control. PX104 had the highest content of crude fat and total fat protein, and the lowest in crude fibre. The smallest protein content was found in seeds of the long-stem hybrid Konkret, while crude fat was lowest in the population form (Poznaniak), and crude fibre was lowest in long-stem hybrid (Konkret).

Conservation status of Paramuricea clavata (Risso, 1826) (Anthozoa, Alcyonacea) in the Chafarinas Islands (Mediterranean Sea)

The red gorgonian Paramuricea clavata (Risso, 1826) is affected by the combined effects of environmental stress factors and diseases in the Mediterranean area. Samplings at different depths in two sites of Chafarinas Islands (South–Western Mediterranean Sea) were carried out to quantify the degree of injuries on red gorgonian colonies. The results showed that shallow colonies displayed a higher rate of injuries than deep colonies. Overall, the conservation status of the population was worse than previously considered in this area.

Heavy Metal Ion Stress on Halobacterium salinarum R1 Planktonic Cells and Biofilms

Halobacterium salinarum R1 is an extremely halophilic archaeon, able to attach to the surface and to form characteristic biofilm structures under physiological conditions. However, the effect of environmental stress factors like heavy metals on biofilms was still unknown. Here, we report on the first insights into H. salinarum biofilm formation when exposed to copper, nickel and zinc and describe the effects of metal ions on the architecture of mature biofilms. We also studied the effects on gene expression in planktonic cells. Investigation of planktonic growth and cell adhesion in the presence of sub-lethal metal concentrations yielded an up to 60% reduced adhesion in case of copper and a significantly enhanced adhesion in case of zinc, whereas nickel treatment had no effect on adhesion. A PMA-qPCR assay was developed to quantify live/dead cells in planktonic cultures and mature biofilms, enabling the investigation of cell vitality after metal exposure. An increased resistance was observed in biofilms with up to 80% in case of copper- and up to 50% in case of zinc exposure compared to planktonic cells. However, nickel-treated biofilms showed no significant increase of cell survival. Microscopic investigation of the architecture of mature biofilms exposed to lethal metal concentrations demonstrated an increased detachment and the formation of large microcolonies after copper treatment, whereas the number of adherent cells increased strongly in nickel-exposed biofilms. In contrast, zinc exposed-biofilms showed no differences compared to the control. Analysis of the expression of genes encoding putative metal transporters by qRT-PCR revealed specific changes upon treatment of the cells with heavy metals. Our results demonstrate diverse effects of heavy metal ions on H. salinarum and imply a metal-specific protective response of cells in biofilms.

Effect of Environmental Stress Factors and Recycling on the Lipid Composition of Brewer’s Yeast Mitochondria

The aim of this study was to investigate alterations in the content and composition of mitochondrial lipids of brewer’s yeast, which occur during brewing and repetitive recycling. The bottom-fermenting brewer’s yeast of Saccharomyces cerevisiae species obtained from industrial beer production was used throughout the study. The first three generations of recycled yeast were analysed. Differences between the generations were more pronounced in the phospholipid and neutral lipid composition than in fatty acid composition. Squalene was present in all generations in high concentrations. The results give insight into the response of yeast cells to stress factors and recycling

Responses to Drought and Salinity in the Endangered Species Ligularia sibirica (L.) Cass.

The negative effects of environmental stress factors on plant distribution and survival are increasing due to climate change and anthropogenic activities. We have analysed some responses to abiotic stress in Ligularia sibirica, a postglacial relict that is critically endangered in Europe. L. sibirica seedlings were subjected to water or salt stress treatments in the greenhouse. After the treatments, plant material was harvested and several growth parameters were measured; leaf contents of common osmolytes, the degree of oxidative stress affecting the plants and the level of antioxidant phenolic compounds were also determined. Both, drought and, especially, salt stress had a negative effect on the growth of L. sibirica plants. Treated plants showed an increase in proline (Pro) and total soluble sugars (TSS) levels, stronger under salt stress. Malondialdehyde (MDA, an oxidative stress biomarker) contents almost doubled, and antioxidant phenolics increased significantly in salt-stressed, but not in water-stressed plants. Pro accumulation can be used as a salt and drought stress biomarker in L. sibirica and, together with TSS, likely contributes to osmotic adjustment under stress. Increase of antioxidant phenolics appears to partly compensate the salt-induced generation of oxidative stress.

Water-Limiting Conditions Alter the Structure and Biofilm-Forming Ability of Bacterial Multispecies Communities in the Alfalfa Rhizosphere

Biofilms are microbial communities that adhere to biotic or abiotic surfaces and are enclosed in a protective matrix of extracellular compounds. An important advantage of the biofilm lifestyle for soil bacteria (rhizobacteria) is protection against water deprivation (desiccation or osmotic effect). The rhizosphere is a crucial microhabitat for ecological, interactive, and agricultural production processes. The composition and functions of bacterial biofilms in soil microniches are poorly understood. We studied multibacterial communities established as biofilm-like structures in the rhizosphere of Medicago sativa (alfalfa) exposed to 3 experimental conditions of water limitation. The whole biofilm-forming ability (WBFA) for rhizospheric communities exposed to desiccation was higher than that of communities exposed to saline or nonstressful conditions. A culture-dependent ribotyping analysis indicated that communities exposed to desiccation or saline conditions were more diverse than those under the nonstressful condition. 16S rRNA gene sequencing of selected strains showed that the rhizospheric communities consisted primarily of members of the Actinobacteria and α- and γ-Proteobacteria, regardless of the water-limiting condition. Our findings contribute to improved understanding of the effects of environmental stress factors on plant-bacteria interaction processes and have potential application to agricultural management practices.

Effect of environmental stress factors on ecophysiological traits and susceptibility to pathogens of five Populus clones throughout the growing season

The variability of ecophysiological traits associated with productivity (e.g., water relations, leaf structure, photosynthesis and nitrogen (N) content) and susceptibility to fungal and insect infection were investigated in five poplar clones (Populus deltoides Batr.-Lux clone; Populus nigra L.-58-861 clone and Populus × canadensis Mönch.-Luisa Avanzo, I-214 and Adige clones) during their growing season. The objective of the study was to determine their physiological responses under summer constraints (characteristic of the Mediterranean climate) and to propose clone candidates for environmental restoration activities such as phytoremediation. Relative water content, the radiometric water index and (13)C isotope discrimination (Δ(13)C) results reflected improved water relations in Adige and Lux during summer drought. Leaf structural parameters such as leaf area, leaf mass per area, density (D) and thickness (T) indicated poorer structural adaptations to summer drought in clone 58-861. Nitrogen content and Δ(13)C results pointed to a stomatal component as the main limitant of photosynthesis in all clones. Adige and Lux showed enhanced photoprotection as indicated by the size and the de-epoxidation index of the xanthophyll-cycle pool, and also improved antioxidant defence displayed by higher ascorbate, reduced glutathione, total phenolics and α-tocopherol levels. Photoprotective and antioxidative responses allowed all clones to maintain a high maximum quantum yield of PSII (Fv/Fm) with the exception of Luisa Avanzo and 58-861 which experienced slight photoinhibition in late spring. The study of susceptibility to rust (Melampsora sp.) and lace bug (Monosteira unicostata Muls. and Rey) infections showed Adige and Lux to be the most tolerant. Overall, these two clones presented high adaptability to summer conditions and improved resistance to abiotic and biotic stress, thereby making them highly commendable clones for use in environmental remediation programmes.

Effect of environmental stress factors on the uptake and survival of Campylobacter jejuni in Acanthamoeba castellanii

BackgroundCampylobacter jejuni is a major cause of bacterial food-borne illness in Europe and North America. The mechanisms allowing survival in the environment and transmission to new hosts are not well understood. Environmental free-living protozoa may facilitate both processes. Pre-exposure to heat, starvation, oxidative or osmotic stresses encountered in the environment may affect the subsequent interaction of C. jejuni with free-living protozoa. To test this hypothesis, we examined the impact of environmental stress on expression of virulence-associated genes (ciaB, dnaJ, and htrA) of C. jejuni and on its uptake by and intracellular survival within Acanthamoeba castellanii.ResultsHeat, starvation and osmotic stress reduced the survival of C. jejuni significantly, whereas oxidative stress had no effect. Quantitative RT-PCR experiments showed that the transcription of virulence genes was slightly up-regulated under heat and oxidative stresses but down-regulated under starvation and osmotic stresses, the htrA gene showing the largest down-regulation in response to osmotic stress. Pre-exposure of bacteria to low nutrient or osmotic stress reduced bacterial uptake by amoeba, but no effect of heat or oxidative stress was observed. Finally, C. jejuni rapidly lost viability within amoeba cells and pre-exposure to oxidative stress had no significant effect on intracellular survival. However, the numbers of intracellular bacteria recovered 5 h post-gentamicin treatment were lower with starved, heat treated or osmotically stressed bacteria than with control bacteria. Also, while ~1.5 × 103 colony forming unit/ml internalized bacteria could typically be recovered 24 h post-gentamicin treatment with control bacteria, no starved, heat treated or osmotically stressed bacteria could be recovered at this time point. Overall, pre-exposure of C. jejuni to environmental stresses did not promote intracellular survival in A. castellanii.ConclusionsTogether, these findings suggest that the stress response in C. jejuni and its interaction with A. castellanii are complex and multifactorial, but that pre-exposure to various stresses does not prime C. jejuni for survival within A. castellanii.

Influences of simultaneous physicochemical stresses on injury and subsequent heat and acid resistances of Salmonella Enteritidis in apple juice

The effects of prior simultaneous pH (3.0–8.0), water activity, aw (0.93–0.99) and temperature (3.0–62.0 °C) stresses on injury and subsequent resistance of Salmonella Enteritidis to acid (pH 3.78, 25 °C) and heating (pH 3.78, 55 °C) in apple juice were determined. Injury rates were significantly (P < 0.05) influenced by the linear effects of aw and temperature. Exposure to combinations (pH 4.0, aw 0.98, 15 °C) and (pH 5.5, aw 0.99, 32.5 °C) resulted in acid adaptation. Only the linear influence of prior aw stress significantly affected the subsequent acid resistance. Heat resistance was greatest after previous exposure to pH, aw and temperature ranges of 4.0–5.5, 0.96–0.98, and 15–50 °C, respectively. None of the stress factors significantly influenced subsequent heat resistance. These results provide a more realistic simulation of the effects of environmental stress factors on the behavior of S. Enteritidis in food and food processing ecologies; and contribute in further understanding the behavior of the pathogen for the improvement of evaluation and control of safety of apple juice and similar products.

Acoustic wave network and multivariate analysis for biosensing in space

Bioanalytical techniques play an important role in monitoring the effects of environmental stress factors on fundamental life processes. In terms of space flight and extraterrestrial research, radiation, altered and microgravity are known to induce changes in gene expression. We report the use of an on-line transverse shear mode (TSM) acoustic wave biosensor to detect the initiation of gene transcription and DNA — drug binding. Since this biosensor offers real-time, label free monitoring of biological processes, it is possible to detect sequential binding steps as demonstrated in this paper. Furthermore, this sensor responds to several factors in the liquid phase such as viscosity, elasticity, surface tension, charge distribution and mass loading, which can in turn be influenced by specific gravity. The sensing device is a piezoelectric quartz crystal onto which the probe molecule (DNA in this case) is immobilized. Change in resonance frequency of the crystal in response to the binding of the target molecule(s), RNA polymerase and actinomycin-D, is fit to an equivalent circuit model from which multidimensional data is extracted. By performing multivariate analysis on this data we are able to observe interactions between several of these data series representing parameters such as motional resistance and capacitance. As well, we are able to observe the dominating parameters (for instance, frequency vs. motional resistance, which in turn can correspond to mass loading vs. energy dissipation) during the course of the experiment, as they vary between the different steps. Such advantages offered by the TSM sensor along with multivariate analysis are indispensable for biotechnological work under the influence of microgravity as several variables come into play.

Effects of environmental stress factors on ectomycorrhizal fungi in vitro

The reaction of various ectomycorrhizal fungi to environmental stress factors was examinated in a screening program. Tolerance to acid and heavy metals, resistance to antagonists, and reactions to automobile exhaust fumes were tested. Differences in reaction between the several ectomycorrhizal species and strains were observed. These results confirm that the susceptibility of ectomycorrhizal fungi to environmental stress factors varies from species to species, but also from strain to strain within a species. Pure culture synthesis with Picea abies showed the symbiotic potential of the selected fungi. Key words: ectomycorrhizal fungi, Picea abies.