Natural Growth Conditions Research Articles

Partial regularity for a nonlinear discontinuous sub-elliptic system with drift on the Heisenberg group: the superquadratic case

ABSTRACT In this paper, we consider a nonlinear discontinuous sub-elliptic system with drift on the Heisenberg group, where the coefficients in system are discontinuous and satisfy the vanishing mean oscillation condition and growth conditions with the growth index 2 < p < ∞ , and the non-homogeneous terms satisfy the controllable growth conditions and the natural growth conditions, respectively. The partial Hölder regularity to weak solutions and the partial Morrey regularity to horizontal gradients of weak solutions are proved by the A -harmonic approximation. One of the difficulties in this paper is how to reasonably define the weak solution and avoid the requirement of integrability of Tu. In fact, we used T = X i X n + i − X n + i X i .

Effect of Sheath Blade Removal on Phyllostachys violascens Shoot Quality

Sheath blades are the first bamboo organ exposed to sunlight after shoots initially emerge. However, it remains uncertain whether sheath blades affect bamboo shoot growth and quality. Accordingly, this study explores variations in Phyllostachys violascens shoot growth and quality, comparing natural growth conditions to periodic sheath blade removal treatments. Results show that sheath blade removal and interactions between sheath blade removal and duration had no significant effect on the morphology, protein nutritional quality, or value of bamboo shoots. However, the length of bamboo shoot was significantly lower 4 d after treatment compared to 4 d after natural growth conditions. Moreover, sheath blade removal did have a significant effect on soluble sugar, total acid, oxalic acid, tannic acid, and cellulose content as well as sugar–acid ratios of bamboo shoots, while having no significant effect on the content and proportion of amino acid flavor compounds. Interactions between sheath blade removal and duration only had a significant effect on total acid and sugar–acid ratios. Soluble sugar, oxalic acid, tannic acid, and sugar–acid ratios increased significantly 2 d after sheath blade removal, while total acid and cellulose content decreased significantly. Lastly, soluble sugar content and sugar–acid ratios increased significantly 4 d after sheath blade removal. Findings from this study indicate that sheath blades affect shoot quality, particularly taste, which is mainly driven by carbon metabolism, but the effect of nitrogen metabolism was not obvious. This study gave a new perspective for revealing the formation mechanism of shoot quality, and also provided possible methods of improvement for the shoot quality.

On the global regularity for minimizers of variational integrals: splitting-type problems in 2D and extensions to the general anisotropic setting

We mainly discuss superquadratic minimization problems for splitting-type variational integrals on a bounded Lipschitz domain Omega subset {mathbb {R}}^2 and prove higher integrability of the gradient up to the boundary by incorporating an appropriate weight-function measuring the distance of the solution to the boundary data. As a corollary, the local Hölder coefficient with respect to some improved Hölder continuity is quantified in terms of the function {text {dist}}(cdot ,partial Omega ).The results are extended to anisotropic problems without splitting structure under natural growth and ellipticity conditions. In both cases we argue with variants of Caccioppoli’s inequality involving small weights.

Potential for the Production of Carotenoids of Interest in the Polar Diatom Fragilariopsis cylindrus.

Carotenoid xanthophyll pigments are receiving growing interest in various industrial fields due to their broad and diverse bioactive and health beneficial properties. Fucoxanthin (Fx) and the inter-convertible couple diadinoxanthin–diatoxanthin (Ddx+Dtx) are acknowledged as some of the most promising xanthophylls; they are mainly synthesized by diatoms (Bacillariophyta). While temperate strains of diatoms have been widely investigated, recent years showed a growing interest in using polar strains, which are better adapted to the natural growth conditions of Nordic countries. The aim of the present study was to explore the potential of the polar diatom Fragilariopsis cylindrus in producing Fx and Ddx+Dtx by means of the manipulation of the growth light climate (daylength, light intensity and spectrum) and temperature. We further compared its best capacity to the strongest xanthophyll production levels reported for temperate counterparts grown under comparable conditions. In our hands, the best growing conditions for F. cylindrus were a semi-continuous growth at 7 °C and under a 12 h light:12 h dark photoperiod of monochromatic blue light (445 nm) at a PUR of 11.7 μmol photons m−2 s−1. This allowed the highest Fx productivity of 43.80 µg L−1 day−1 and the highest Fx yield of 7.53 µg Wh−1, more than two times higher than under ‘white’ light. For Ddx+Dtx, the highest productivity (4.55 µg L−1 day−1) was reached under the same conditions of ‘white light’ and at 0 °C. Our results show that F. cylindrus, and potentially other polar diatom strains, are very well suited for Fx and Ddx+Dtx production under conditions of low temperature and light intensity, reaching similar productivity levels as model temperate counterparts such as Phaeodactylum tricornutum. The present work supports the possibility of using polar diatoms as an efficient cold and low light-adapted bioresource for xanthophyll pigments, especially usable in Nordic countries.

Pseudo-targeted metabolomics analysis of the therapeutic effect of phenolics-rich extract from Se-enriched green tea (Camellia sinensis) on LPS-stimulated murine macrophage (RAW264.7)

Selenium (Se)-enriched green tea (Se-Te) has been recognized as a possible source of Se supplements, while the effect of Se enrichment on function of polyphenols in green tea is still unclear. In this study, a pseudo-targeted metabolomics strategy was carried out to reveal the regulatory mechanism of polyphenols extracted from Se-Te and regular green tea (Re-Te) on inflammatory response at cellular level. A novel analysis strategy using UHPLC/ESI Q-Orbitrap combined with MS-IOP was applied to profile the dynamic changes of metabolites in LPS-stimulated RAW264.7 macrophages during polyphenols incubation. A total of 128 characteristic variables (VIP > 1, p < 0.05) were screened in Se-Te group and the results of bioinformatics analysis and quantitative research indicated that in addition to the 6 conventional immune protective pathways involved in tea polyphenols, Se-enriched polyphenols were also participated in 3 unique antioxidant enzyme activation pathways, including phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism and pantothenate and CoA biosynthesis. The result of weight calculation based on topological analysis indicated that the promoting synthesis of antioxidant enzymes was the main mechanism of Se-Te polyphenols to inhibit inflammation. However, compared with Re-Te group, the intracellular B vitamin pathway in Se-Te group was disturbed, which is related to the fact that Se supplementation can promote the synthesis of selenoprotein and catalyze the reduction of thioredoxin by NADPH, thus blocking the signaling pathways of B vitamins. This study comprehensively explored the immune protective mechanism of polyphenols extracted from Se-Te and Re-Te under natural growth conditions, which could give a better understanding of the potential nutritional value of Se-Te as a widely used Se supplement.

Comparative study on nutritional quality and volatile flavor compounds of muscle in Cyprinus carpio haematopterus under wild, traditional pond and in-pond raceway system culture

This study compared the physical characteristics, nutritional components, mineral elements, and volatile matter of the muscle of the Yellow River carp (Cyprinus carpio haematopterus) grown under the traditional pond system (TPS), in-pond raceway system (IPRS), and wild (WYRC) to reveal the differences in its muscle quality under aquaculture and natural growth conditions. The results demonstrated a significantly lower water-loss rate in the Yellow River carp muscle of both the WYRC and IPRS groups than that in the TPS group (P < 0.05), whereas the cooked rate was significantly higher than that in the TPS group (P < 0.05). The firmness, chewiness, and gumminess relationships were in the order of WYRC > IPRS > TPS, and significant differences (P < 0.05) were observed among the groups. The WYRC group had a significantly higher muscle fibre density than the TPS and IPRS groups (P < 0.05). The crude fat content of the WYRC and IPRS groups was significantly higher than that of the TPS group, whereas their crude protein content was significantly lower than that of the TPS group (P < 0.05). The collagen content was ranked WYRC > IPRS > TPS, and there was a significant difference between the groups (P < 0.05). The EPA (C20: 5n-3) content followed the order WYRC > IPRS > TPS, and the groups exhibited significant differences (P < 0.05). The As and Hg contents in the WYRC group were 8 and 5 times higher, respectively, than those in the cultured group. The content of hexanal, heptanal, octanal, butanal, and other substances did not differ significantly between the IPRS and WYRC groups (P > 0.05). These results suggest that different growth conditions significantly influence the physical characteristics, nutritional components, mineral elements, and volatile substances of the Yellow River carp muscle.

Regularity for a Nonlinear Discontinuous Subelliptic System with Drift on the Heisenberg Group

In this paper, we prove the partial Hölder regularity of weak solutions and the partial Morrey regularity to horizontal gradients of weak solutions to a nonlinear discontinuous subelliptic system with drift on the Heisenberg group by theA-harmonic approximation, where the coefficients in the nonlinear subelliptic system are discontinuous and satisfy the VMO condition forx, ellipticity and growth condition with the growth index1&lt;p&lt;2for the Heisenberg gradient variable, and the nonhomogeneous terms satisfy the controllable growth condition and the natural growth condition, respectively.

Microstructural Mapping of Arctica islandica Shells Reveals Environmental and Physiological Controls on Biomineral Size

The shells of long-lived bivalves record environmental variability in their geochemical signatures and are thus used extensively in marine high-resolution paleoclimate studies. To possibly overcome the limitations of the commonly employed temperature proxy, the δ18Oshell value, which requires knowledge of the seawater δ18O signature and is prone to diagenetic overprint, the shell microstructures and the morphological properties of individual biomineral units (BMUs) recently attracted research interest as an alternative paleoclimate proxy. In shells of A. islandica, one of the most extensively used and best studied sclerochronological archives, the size of the BMUs increases in warmer temperatures under laboratory circumstances. This study assesses whether this relationship persists under natural growth conditions or whether additional environmental and physiological factors control the BMU size and bias temperature reconstructions. For this purpose, shells from the surface waters of NE Iceland and the Baltic Sea, as well as from deeper waters of the North Sea (100 and 243 m) were analyzed by means of SEM. The BMU sizes were measured by means of image processing software. Results demonstrate a strong effect of temperature on the BMU size at NE Iceland and in the North Sea at 100 m depth. At 243 m depth, however, temperature variability was likely too low (1.2°C) to evoke a microstructural change. At the Baltic Sea, the BMUs remained small, possibly due to physiological stress induced by low salinity and/or hypoxia. Thus, the size of BMUs of A. islandica shells only serves as a relative temperature indicator in fully marine habitats, as long as seasonal temperature amplitudes exceed ca. 1°C. Furthermore, BMU size varied through lifetime with the largest units occurring during age seven to nine. This pattern is possibly linked to the shell growth rate or to the amount of metabolic energy invested in shell growth.

The production of laccases by white-rot fungi under solid-state fermentation conditions.

Laccases (E.C. 1.10.3.2) produced by white-rot fungi (WRF) can be widely used, but the high cost prevents their use in large-scale industrial processes. Finding a solution to the problem could involve laccase production by solid-state fermentation (SSF) simulating the natural growth conditions for WRF. SSF offers several advantages over conventional submerged fermentation (SmF), such as higher efficiency and productivity of the process and pollution reduction. The aim of this review is therefore to provide an overview of the current state of knowledge about the laccase production by WRF under SSF conditions. The focus is on variations in the up-stream process, fermentation and down-stream process and their impact on laccase activity. The variations of up-stream processing involve inoculum preparation, inoculation of the medium and formulation of the propagation and production media. According to the studies, the production process can be shortened to 5-7days by the selection of a suitable combination of lignocellulosic material and laccase producer without the need for any additional components of the culture medium. Efficient laccase production was achieved by valorisation of wastes as agro-food, municipal wastes or waste generated from wood processing industries. This leads to a reduction of costs and an increase in competitiveness compared to other commonly used methods and/or procedures. There will be significant challenges and opportunities in the future, where SSF could become more efficient and bring the enzyme production to ahigher level, especially in new biorefineries, bioreactors and biomolecular/genetic engineering.

Effects of Light Intensity on Root Development in a D-Root Growth System.

Plant development is highly affected by light quality, direction, and intensity. Under natural growth conditions, shoots are directly exposed to light whereas roots develop underground shielded from direct illumination. The photomorphogenic development strongly represses shoot elongation whereas promotes root growth. Over the years, several studies helped the elucidation of signaling elements that coordinate light perception and underlying developmental outputs. Light exposure of the shoots has diverse effects on main root growth and lateral root (LR) formation. In this study, we evaluated the phenotypic root responses of wild-type Arabidopsis plants, as well as several mutants, grown in a D-Root system. We observed that sucrose and light act synergistically to promote root growth and that sucrose alone cannot overcome the light requirement for root growth. We also have shown that roots respond to the light intensity applied to the shoot by changes in primary and LR development. Loss-of-function mutants for several root light-response genes display varying phenotypes according to the light intensity to which shoots are exposed. Low light intensity strongly impaired LR development for most genotypes. Only vid-27 and pils4 mutants showed higher LR density at 40 μmol m–2 s–1 than at 80 μmol m–2 s–1 whereas yuc3 and shy2-2 presented no LR development in any light condition, reinforcing the importance of auxin signaling in light-dependent root development. Our results support the use of D-Root systems to avoid the effects of direct root illumination that might lead to artifacts and unnatural phenotypic outputs.

Molecular Breeding of a Novel PTGMS Line of WDR for Broad-Spectrum Resistance to Blast Using Pi9, Pi5, and Pi54 Genes

BackgroundThe two-line method based on the photoperiod and thermo-sensitive genic male sterile (PTGMS) lines is more cost-effective, simple, and efficient than the three-line system based on cytoplasmic male-sterility. Blast and drought are the most prevalent biotic and abiotic stress factors hampering rice production. Molecular techniques demonstrate higher efficacy in the pyramiding of disease resistance genes, providing green performance under the background of water-saving and drought-resistance rice.ResultsThis study employed molecular marker-assisted selection, conventional hybridization, and high-intensity stress screening to integrate three broad-spectrum blast resistance genes Pi9, Pi5, and Pi54 into Huhan 1S. Subsequently, a novel water-saving and drought-resistance rice (WDR) PTGMS line Huhan 74S was developed. The drought resistance of the new PTGMS line Huhan 74S was comparable to that of Huhan 1S. Pathogenicity assays involving the inoculation of 14 blast prevalent isolates in the glasshouse showed that the blast resistance frequency of Huhan 74S was 85.7%. Further evaluation under natural blast epidemic field conditions showed that Huhan 74S and its hybrids were resistant to leaf and neck blast. The critical temperature point of fertility-sterility alteration of Huhan 74S was 23 °C daily mean temperature. The complete male sterility under natural growth conditions in 2017 at Shanghai lasted for 67 days. Also, both the agronomic and grain quality traits met the requirement for two-line hybrid rice production.ConclusionThese results indicate that the newly bred PTGMS line Huhan 74S can be used to breed high-yielding, good-quality, disease-resistant two-line hybrid water-saving and drought-resistance rice (WDR), hence promoting sustainable rice production in China.

Temporal expression study of miRNAs in the crown tissues of winter wheat grown under natural growth conditions

BackgroundWinter wheat requires prolonged exposure to low temperature to initiate flowering (vernalization). Shoot apical meristem of the crown is the site of cold perception, which produces leaf primordia during vegetative growth before developing into floral primordia at the initiation of the reproductive phase. Although many essential genes for winter wheat cold acclimation and floral initiation have been revealed, the importance of microRNA (miRNA) meditated post-transcriptional regulation in crowns is not well understood. To understand the potential roles of miRNAs in crown tissues, we performed a temporal expression study of miRNAs in crown tissues at the three-leaf stage, winter dormancy stage, spring green-up stage, and jointing stage of winter wheat grown under natural growth conditions.ResultsIn total, 348 miRNAs belonging to 298 miRNA families, were identified in wheat crown tissues. Among them, 92 differentially expressed miRNAs (DEMs) were found to be significantly regulated from the three-leaf stage to the jointing stage. Most of these DEMs were highly expressed at the three-leaf stage and winter dormancy stage, and then declined in later stages. Six DEMs, including miR156a-5p were markedly induced during the winter dormancy stage. Eleven DEMs, including miR159a.1, miR390a-5p, miR393-5p, miR160a-5p, and miR1436, were highly expressed at the green-up stage. Twelve DEMs, such as miR172a-5p, miR394a, miR319b-3p, and miR9676-5p were highly induced at the jointing stage. Moreover, 14 novel target genes of nine wheat or Pooideae-specific miRNAs were verified using RLM-5′ RACE assay. Notably, six mTERFs and two Rf1 genes, which are associated with mitochondrial gene expression, were confirmed as targets of three wheat-specific miRNAs.ConclusionsThe present study not only confirmed the known miRNAs associated with phase transition and floral development, but also identified a number of wheat or Pooideae-specific miRNAs critical for winter wheat cold acclimation and floral development. Most importantly, this study provided experimental evidence that miRNA could regulate mitochondrial gene expression by targeting mTERF and Rf1 genes. Our study provides valuable information for further exploration of the mechanism of miRNA mediated post-transcriptional regulation during winter wheat vernalization and inflorescent initiation.

The response of photosystem I to fluctuating light is influenced by leaf nitrogen content in tomato

Fluctuating light and nitrogen (N) deficiency can occur synchronously under natural growth conditions. However, little is known about the photosynthetic regulation under fluctuating light in plants grown with N deficiency. In the present study, we examined the effect of N supply on the response of photosystem I (PSI) to fluctuating light in tomato. Plants grown under high N concentration (HN-plants) had higher leaf N content, chlorophyll content and saturating CO2 assimilation rate than plants grown under middle and low N concentrations (MN- and LN-plants). After an abrupt increase in illumination for 10 s, all plants could not generate a sufficient proton gradient (ΔpH). Meanwhile, PSI was over-reduced in HN- and MN-plants but was highly oxidized in LN-plants. In LN-plants, the smallest PSII electron flow avoided an over-reduction of PSI under fluctuating light. After transition from low to high light, CEF gradually increased to the peak in 30 s in HN-plants but rapidly increased to the peak in 10 s in MN-plants. Such delayed activation of CEF in HN-plants accelerated the over-reduction of PSI. After fluctuating light treatment, HN-plants displayed the greatest PSI photoinhibition, followed by MN- and LN-plants. These results indicated that leaf N content significantly affected the response of PSI to fluctuating light in tomato.

TaWRKY13-A Serves as a Mediator of Jasmonic Acid-Related Leaf Senescence by Modulating Jasmonic Acid Biosynthesis.

Leaf senescence is crucial for crop yield and quality. Transcriptional regulation is a key step for integrating various senescence-related signals into the nucleus. However, few regulators of senescence implicating transcriptional events have been functionally characterized in wheat. Based on our RNA-seq data, we identified a WRKY transcription factor, TaWRKY13-A, that predominately expresses at senescent stages. By using the virus-induced gene silencing (VIGS) method, we manifested impaired transcription of TaWRKY13-A leading to a delayed leaf senescence phenotype in wheat. Moreover, the overexpression (OE) of TaWRKY13-A accelerated the onset of leaf senescence under both natural growth condition and darkness in Brachypodium distachyon and Arabidopsis thaliana. Furthermore, by physiological and molecular investigations, we verified that TaWRKY13-A participates in the regulation of leaf senescence via jasmonic acid (JA) pathway. The expression of JA biosynthetic genes, including AtLOX6, was altered in TaWRKY13-A-overexpressing Arabidopsis. We also demonstrated that TaWRKY13-A can interact with the promoter of AtLOX6 and TaLOX6 by using the electrophoretic mobility shift assay (EMSA) and luciferase reporter system. Consistently, we detected a higher JA level in TaWRKY13-A-overexpressing lines than that in Col-0. Moreover, our data suggested that TaWRKY13-A is partially functional conserved with AtWRKY53 in age-dependent leaf senescence. Collectively, this study manifests TaWRKY13-A as a positive regulator of JA-related leaf senescence, which could be a new clue for molecular breeding in wheat.

Endogenous stress-related signal directs shoot stem cell fate in Arabidopsis thaliana.

Stem cell populations in all multicellular organisms are situated in a niche, which is a special microenvironment that defines stem cell fate. The interplay between stem cells and their niches is crucial for stem cell maintenance. Here, we show that an endogenous stress-related signal (ESS) is overrepresented in the shoot stem cell niche under natural growth conditions, and the vast majority of known stem-cell-specific and niche-specific genes responded to stress signals. Interference with the ESS in the stem cell niche by blocking ethylene signalling impaired stem cell maintenance. Ethylene-insensitive 3 (EIN3), the key transcription factor in ethylene signalling, directly actives the expression of the stress hub transcription factor AGAMOUS-LIKE 22 (AGL22) in the stem cell niche and relays ESS signals to the WUSCHEL/CLAVATA network. Our results provide a mechanistic framework for ESS signalling control of the stem cell niche and demonstrate that plant stem cells are maintained by a native stress microenvironment in vivo.

RNA viruses in the house dust mite Dermatophagoides pteronyssinus, detection in environmental samples and in commercial allergen extracts used for in vivo diagnosis.

Allergy to house dust mites (HDM), the most important source of indoor allergens worldwide, is diagnosed and treated using natural extracts from cultures that can contain immunoactive components from the HDM microbiome, including mite-infecting viruses. This study aimed to contribute to the discovery and characterization of RNA viruses from Dermatophagoides pteronyssinus, followed by their detection in different mite-derived sources. Viruses were assembled after in silico metatranscriptomic analysis of D.pteronyssinus RNA samples, visualized by electron microscopy, and RNA detected by direct RT-PCR or data mining. Mite culture performance was evaluated in vivo. Seven RNA viruses were identified in our laboratory stock colony. Picornavirus-like viral particles were detected in epithelial cells of the digestive system and in fecal pellets. Most of these viruses could be persistently transmitted to an inbred virus-free colony by inoculating fecal material from the stock colony. Upon viral infection, no significant effect could be seen on mite population growth. Transcriptomic screening confirmed the presence of homolog sequences to these viruses in independent laboratory stocks of D.pteronyssinus and in other Astigmata mites. Noteworthy, RNA from most of the viruses could be detected by RT-PCR on house dust samples, reference standards, and/or commercial diagnostic D.pteronyssinus extracts. Our results show that viral infections are common and widespread in D.pteronyssinus, both in natural and culture-based growth conditions. Potential effects on the mites themselves and consequences toward allergenicity in humans whether exposed naturally or after immunotherapy are discussed.

Investigating the Impact of Cerium Oxide Nanoparticles Upon the Ecologically Significant Marine Cyanobacterium Prochlorococcus

Cerium oxide nanoparticles (nCeO2) are used at an ever-increasing rate, however, their impact within the aquatic environment remains uncertain. Here, we expose the ecologically significant marine cyanobacterium Prochlorococcus sp. MED4 to nCeO2 at a wide range of concentrations (1 μg L–1 to 100 mg L–1) under simulated natural and nutrient rich growth conditions. Flow cytometric analysis of cyanobacterial populations displays the potential of nCeO2 (100 μg L–1) to significantly reduce Prochlorococcus cell density in the short-term (72 h) by up to 68.8% under environmentally relevant conditions. However, following longer exposure (240 h) cyanobacterial populations are observed to recover under simulated natural conditions. In contrast, cell-dense cultures grown under optimal conditions appear more sensitive to exposure during extended incubation, likely as a result of increased rate of encounter between cyanobacteria and nanoparticles at high cell densities. Exposure to supra-environmental nCeO2 concentrations (i.e., 100 mg L–1) resulted in significant declines in cell density up to 95.7 and 82.7% in natural oligotrophic seawater and nutrient enriched media, respectively. Observed cell decline is associated with extensive aggregation behaviour of nCeO2 upon entry into natural seawater, as observed by dynamic light scattering (DLS), and hetero-aggregation with cyanobacteria, confirmed by fluorescent microscopy. Hence, the reduction of planktonic cells is believed to result from physical removal due to co-aggregation and co-sedimentation with nCeO2 rather than by a toxicological and cell death effect. The observed recovery of the cyanobacterial population under simulated natural conditions, and likely reduction in nCeO2 bioavailability as nanoparticles aggregate and undergo sedimentation in saline media, means that the likely environmental risk of nCeO2 in the marine environment appears low.

Strongly nonlinear elliptic problem with measure data in Musielak-Orlicz spaces

ABSTRACT In this paper, we investigate the existence theorem of entropy solutions for nonlinear elliptic problem of the type in Ω, in the setting of Musielak-Orlicz spaces. The lower order term Φ verifies the natural growth condition, the nonlinearity g has a natural growth with respect to its third argument and with sign condition, no -condition is assumed on the Musielak function, and the datum μ is assumed to belong to .

Elicitation of Antimicrobial Active Compounds by Streptomyces-Fungus Co-Cultures.

The bacteria of the genus Streptomyces and Basidiomycete fungi harbor many biosynthetic gene clusters (BGCs) that are at the origin of many bioactive molecules with medical or industrial interests. Nevertheless, most BGCs do not express in standard lab growth conditions, preventing the full metabolic potential of these organisms from being exploited. Because it generates biotic cues encountered during natural growth conditions, co-culture is a means to elicit such cryptic compounds. In this study, we explored 72 different Streptomyces-fungus interaction zones (SFIZs) generated during the co-culture of eight Streptomyces and nine fungi. Two SFIZs were selected because they showed an elicitation of anti-bacterial activity compared to mono-cultures. The study of these SFIZs showed that co-culture had a strong impact on the metabolic expression of each partner and enabled the expression of specific compounds. These results show that mimicking the biotic interactions present in this ecological niche is a promising avenue of research to explore the metabolic capacities of Streptomyces and fungi.

Temporal Changes in Ozone Concentrations and Their Impact on Vegetation

Tropospheric concentrations of phytotoxic ozone (O3) have undergone a great increase from preindustrial 10–15 ppbv to a present-day concentration of 35–40 ppbv in large parts of the industrialised world due to increased emissions of O3 precursors including NOx, CO, CH4 and volatile organic compounds. The rate of increase in O3 concentration ranges between 1 ppbv per decade in remote locations of the Southern hemisphere and 5 ppbv per decade in the Northern hemisphere, where largest sources of O3 precursors are located. Molecules of O3 penetrating into the leaves through the stomatal apertures trigger the formation of reactive oxygen species, leading thus to the damage of the photosynthetic apparatus. Accordingly, it is assumed, that O3 increase reduces the terrestrial carbon uptake relative to the preindustrial era. Here we summarise the results of previous manipulative experiments in laboratory growth cabinets, field open-top chambers and free-air systems together with O3 flux measurements under natural growth conditions. In particular, we focus on leaf-level physiological responses in trees, variability in stomatal O3 flux and changes in carbon fluxes and biomass production in forest stands. As the results reported in the literature are highly variable, ranging from negligible to severe declines in photosynthetic carbon uptake, we also discuss the possible interactions of O3 with other environmental factors including solar radiation, drought, temperature and nitrogen deposition. Those factors were found to have great potential to modulate stomata openness and O3 fluxes.