This paper focuses on the diatom flora colonising subterranean habitats, summarizing the information contained in all the scientific papers published from 1900 up to date. In this paper, the authors ...provide a complete checklist of the diatom taxa recorded in subterranean habitats, including a total of 363 taxa, belonging to 82 genera. The most frequent and abundant species recorded in caves and other low light subterranean habitats are generally aerophilic and cosmopolitan. These are, in order of frequency: Hantzschia amphioxys, Diadesmis contenta, Orthoseira roeseana, Luticola nivalis, Pinnularia borealis, Diadesmis biceps and Luticola mutica. Due to the peculiarity of the subterranean habitats, the record of rare or new species is relatively common. The most important environmental factors driving species composition and morphological modifications observed in subterranean populations are analysed throughout the text and tables. In addition, suggestions to prevent and remove the corrosive biofilms in view of an environmentally sustainable cave management are discussed.
Cyanobacteria with true branching are classified in Subsection V (formerly order Stigonematales) in the phylum CYANOBACTERIA: They exhibit a high degree of morphological complexity and are known from ...particular biotopes. Only a few stigonematalean morphotypes have been cultured, and therefore the high variability of morphotypes found in nature is under-represented in culture. Axenic cultures of Chlorogloeopsis and Fischerella sensu Rippka et al. were, to date, the only representatives of this Subsection in phylogenetic studies. The 16S rDNA sequence analysis data in this report confirm that heterocyst-forming cyanobacteria are a monophyletic group. However, unlike previous studies have suggested, these 16S rDNA data on new Stigonematales strains show that the true branching cyanobacteria are polyphyletic and can be separated into at least two major groups defined by their branching type, the first group being characterized by T-branching and the second group by Y-branching. Cyanobacteria with intercalary heterocysts and either no branching or false-branching also formed separate clusters. In consequence, our phylogenetic data do not correlate with the bacteriological and traditional classifications, which distinguish filamentous heterocystous cyanobacteria with or without true branching (Nostocales/Stigonematales).
Forty unicyanobacterial cultures of the genus Scytonema , isolated from terrestrial habitats worldwide (Europe, America, Southeast Asia, Australia and Africa), were investigated. The pigments ...detected were four phycobiliproteins (allophycocyanin, phycocyanin, phycoerythrocyanin and phycoerythrin), scytonemin, six carotenoids (β-carotene, canthaxanthin, echinenone, isozeaxanthin, myxoxanthophyll and zeaxanthin) and14 different mycosporines, including shinorine, stanierine and asterina-330. Cluster analyses indicated three groups among the isolates which were not related to their biogeographical origins. The first was composed of isolates with allophycocyanin and phycocyanin; β-carotene, canthaxanthin, echinenone and zeaxanthin; and scytonemin but no MAAs. These isolates had disc-shaped or elongated cells with blue-green cytoplasm and slight meristematic zones. The second group comprised isolates containing allophycocyanin, phycocyanin and phycoerythrin; β-carotene, canthaxanthin, echinenone, isozeaxanthin and myxoxanthophyll; and also both MAAs and scytonemin. Here, the cells were elongated with brown-violet cytoplasm and marked meristematic zones. The third group comprised isolates with allophycocyanin, phycocyanin and phycoerythrocyanin; β-carotene, canthaxanthin and echinenone; shinorine-type MAA, but no scytonemin. The cells were elongate with blue-green cytoplasm and marked terminal meristematic zones, and the organisms grew in dimly lit places. Multivariate statistical analyses were performed to identify compounds with especial value for taxonomy. Allophycocyanin, phycocyanin, phycoerythrin and phycoerythrocyanin; scytonemin; isozeaxanthin, myxoxanthophyll and zeaxanthin; and shinorine, asterina-330 and mycosporine 13, showed statistically significant variations among the three groups of Scytonema unicyanobacterial cultures. These results, and the fact that the biomarkers studied were conserved, even during long-term cultivation, suggest that these compounds can be used as chemotaxonomic markers in taxonomic and phylogenetic studies of Scytonema .
Biofilms colonizing surfaces inside drinking water distribution networks may provide a habitat and shelter to pathogenic viruses and parasites. If released from biofilms, these pathogens may ...disseminate in the water distribution system and cause waterborne diseases. Our study aimed to investigate the interactions of protozoan parasites (Cryptosporidium parvum and Giardia lamblia oocysts) and viruses (vaccinal poliovirus type 1, φX174, and MS2) with two contrasting biofilms. First, attachment, persistence, and detachment of the protozoan parasites and the viruses were assessed with a drinking water biofilm. This biofilm was allowed to develop inside a rotating annular reactor fed with tap water for 7 months prior to the inoculation. Our results show that viable parasites and infectious viruses attached to the drinking water biofilm within 1 h and persisted within the biofilm. Indeed, infectious viruses were detected in the drinking water biofilm up to 6 days after the inoculation, while viral genome and viable parasites were still detected at day 34, corresponding to the last day of the monitoring period. Since viral genome was detected much longer than infectious particles, our results raise the question of the significance of detecting viral genomes in biofilms. A transfer of viable parasites and viruses from the biofilm to the water phase was observed after the flow velocity was increased but also with a constant laminar flow rate. Similar results regarding parasite and virus attachment and detachment were obtained using a treated wastewater biofilm, suggesting that our observations might be extrapolated to a wide range of environmental biofilms and confirming that biofilms can be considered a potential secondary source of contamination.
Fusarium culmorum is one of the most harmful pathogens of durum wheat and is the causal agent of foot and root rot (FRR) disease. F. culmorum produces the mycotoxin deoxynivalenol (DON) that is ...involved in the pathogenic process. The role of the gene FcStuA, a StuA ortholog protein with an APSES domain sharing 98.5% homology to the FgStuA protein (FGSG10129), was determined by functional characterisation of deletion mutants obtained from two F. culmorum wild-type strains, FcUk99 (a highly pathogenic DON producer) and Fc233B (unable to produce toxin and with a mild pathogenic behavior). The ΔFcStuA mutants originating from both strains showed common phenotypic characters including stunted vegetative growth, loss of hydrophobicity of the mycelium, altered pigmentation, decreased activity of polygalacturonic enzymes and catalases, altered and reduced conidiation, delayed conidial germination patterns and complete loss of pathogenicity towards wheat stem base/root tissue. Glycolytic process efficiency measured as growth on glucose as sole carbon (C) source was strongly impaired and growth was partially restored on glutamic acid. Growth on pectin-like sources ranked in between glucose and glutamic acid with the following order (the lowest to the highest growth): beechwood xylan, sugarbeet arabinan, polygalacturonic acid, citrus pectin, apple pectin, potato azogalactan. DON production in the mutants originating from FcUK99 strain was significantly decreased (-95%) in vitro. Moreover, both sets of mutants were unable to colonise non-cereal plant tissues, i.e. apple and tomato fruits and potato tubers. No differences between mutants, ectopic and wild-type strains were observed concerning the level of resistance towards four fungicides belonging to three classes, the demethylase inhibitors epoxiconazole and tebuconzole, the succinate dehydrogenase inhibitor isopyrazam and the cytochrome bc1 inhibitor trifloxystrobin. StuA, given its multiple functions in cell regulation and pathogenicity control, is proposed as a potential target for novel disease management strategies.
A new instrument has been setup at the Centre de Recherche Public-Gabriel Lippmann to measure spectral emissivity values of typical earth surface samples in the 8 to 12 μm range at a spectral ...resolution of up to 0.25 cm−1. The instrument is based on a Hyper-Cam-LW built by Telops with a modified fore-optic for vertical measurements at ground level and a platform for airborne acquisitions. A processing chain has been developed to convert calibrated radiances into emissivity spectra. Repeat measurements taken on samples of sandstone show a high repeatability of the system with a wavelength dependent standard deviation of less than 0.01 (1.25% of the mean emissivity). Evaluation of retrieved emissivity spectra indicates good agreement with reference measurements. The new instrument facilitates the assessment of the spatial variability of emissivity spectra of material surfaces—at present still largely unknown—at various scales from ground and airborne platforms and thus will provide new opportunities in environmental remote sensing.
Enteroviruses and noroviruses are pathogenic viruses excreted by infected individuals. Discharged in wastewaters, some of these viruses can be captured by biofilms. In the present study, we assessed ...the occurrence and persistence of these viruses in wastewaters and in corresponding biofilms. Natural wastewaters and biofilms were analyzed monthly from January to July using real-time RT-PCR. Enterovirus RNA was detected in wastewater in June while norovirus RNA was detected from January to March. In contrast, biofilm analysis revealed the presence of both enterovirus and norovirus genomes throughout the study period. For instance, enterovirus and norovirus genogroups (GG) I and II were detected in 50, 46 and 37% of the biofilm samples, respectively (
n
=
24). In a laboratory experiment, persistence of norovirus GGI RNA (quantified using molecular techniques) and F-specific bacteriophages (quantified using both culture and molecular techniques) was assessed in wastewater and corresponding naturally-contaminated biofilms at both 4 and 20
°C. The concentrations of viral genomes (norovirus GGI and F-specific RNA phage) were very stable in biofilms. Indeed, no significant decrease was observed during the persistence experiment that lasted 49 days. Furthermore, regardless of our experimental conditions, viral genome and infectious F-specific bacteriophages persisted longer in biofilm than in wastewater. According to our results, wastewater biofilms may contribute to the persistence and dispersal of pathogenic viruses outside of epidemic periods.
Agmatine and other putrescines are known for being strong inducers of deoxynivalenol (DON) production in Fusarium graminearum. Other important species produce DON and/or other trichothecene type B ...toxins (3 acetylated DON, 15 acetylated DON, Fusarenon-X, Nivalenol), such as F. culmorum and F. poae. In order to verify whether the mechanism of the regulation of trichothecene type B induction by agmatine is shared by different species of Fusarium, we tested the hypothesis on 19 strains belonging to 3 Fusarium species (F. graminearum, F. culmorum, F. poae) with diverse genetic chemotypes (3ADON, 15ADON, NIV) by measuring trichothecene B toxins such as DON, NIV, Fusarenon-X, 3ADON and 15ADON. Moreover, we tested whether other toxins like zearalenone were also boosted by agmatine. The trichothecene type B boosting effect was observed in the majority of strains (13 out of 19) in all the three species. Representative strains from all three genetic chemotypes were able to boost toxin production after agmatine treatment. We identified the non-responding strains to the agmatine stimulus, which may contribute to deciphering the regulatory mechanisms that link toxin production to agmatine (and, more generally, polyamines).
Many health beneficial functions of dietary ingredients, including antimutagenity and anticarcinogenity, have been discussed in relation to their antioxidant properties. In this study, antioxidative ...mechanisms of whole-apple antioxidants (from seven varieties) were investigated using the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity assay, the ferric-reducing antioxidant power (FRAP) assay, and the ferrous iron(II) chelating activity assay. Results indicated the ability of primary antioxidants to act as hydrogen or electron donors, with considerable differences depending on variety, with ABTS and FRAP values ranging from 270 to 1,142 mg of vitamin C equivalents/100 g and from 695 to 3,143 μmol of Fe/100 g, respectively. However, varieties did not display measurable chelating activity except for Florina and Graham, exhibiting a weak activity (0.1-0.2 μg of EDTA equivalents/100 g). Correlation analyses showed that polyphenols were major primary antioxidants contributing to antioxidative mechanisms (r>0.99, P<.001), whereas their involvement as secondary antioxidants (i.e., as chelating compounds) was negligible. Our findings further showed that the intake of 100 g of apple fruits can provide antioxidants equivalent to approximately 270-1,140 mg of vitamin C, with highest antioxidant concentrations for the older varieties Grauapfel and Goldparmäne.
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