1,721,027 research outputs found
Response of Antarctic soil fungal assemblages to experimental warming and reduction of UV radiation.
No full textAbstract This paper reports the effects of nutrient
availability, UV radiation and temperature on the taxa
composition and abundance of Antarctic soil mycobiota.
Two sites at Edmonson Point were studied: the first
was poor in nutrients, near the glacier, and the second
was close to bird nesting sites. The highest abundance of
soil fungi was recorded at the site adjacent to the bird
nesting sites. Phoma herbarum was the most abundant
taxon. Lecytophora lignicola and Ascotricha erinacea are
new records for continental Antarctica. The fungal
assemblage from the nutrient-deficient site was characterized
by a dominance-diversity curve approaching the
broken-stick model, the assemblage from the soil influenced
by birds was characterized by a lognormal distribution.
Plastic cloches were used in experiments
designed to assess differences in fungal assemblages
subjected to altered temperature and/or UV exposure.
Dominance-diversity curves and diversity values of soil
fungal mycobiota were compared in their natural condition
as compared with manipulated conditions. Under
the walled cloches, at both sites, artificial warming led to
stress on Antarctic soil fungal assemblages. In contrast,
UV protection led to a higher equilibrium in the
assemblage structure. On the basis of the results
obtained, it could be proposed that UV radiation is the
most important limiting ecological factor for soil mycobiota
in continental Antarctica
Recolonization dynamics of marble monuments after cleaning treatments: A nine-year follow-up study
No full textThe prevention and control of biological patinas on outdoor stone monuments represent a demanding challenge for the conservation of cultural heritage also due to some microorganisms, particularly resistant to treatments, such as black meristematic fungi, an eco-physiological group well known for its tolerance to extreme conditions. Even if several methods and eco-friendly products have been proposed as new alternatives, traditional biocides are still far from being completely replaced. Recolonization is a natural process that occurs sooner or later after cleaning. The time that elapses until its occurrence can vary considerably depending on environmental conditions and the used products; unfortunately, the papers describing the effect of treatments over time are rare. This work aims to shed light on the recolonization process of marble surfaces in the ancient monumental cemetery of Bonaria (Cagliari) after nine years from treatments, evaluating the long-term efficiency of two different cleaning methods, namely dimethyl sulfoxide-based gel (DMSO-based gel) and Biotin T (a didecyldimethylammonium chloride-based product-). In this context, the microflora present before treatments and in the following years was assessed by culture-based methods and identified by molecular techniques, with attention on black meristematic fungi, which were used as reference for the most resistant lithobiontic organisms. Different environmental parameters, such as temperature, exposition, dominant winds, and rainfall, were considered, and infrared thermography, portable light microscopy, and image analysis were used. This research evidenced the influence of water availability and lightning in recolonization processes, the transition from the pioneer fungal community versus more resistant black fungal species after Biotin T treatment, and the long-lasting efficiency of the DMSObased gel. These findings prove that this low-impact method deserves more attention in the conservation of outdoor marble monuments, emphasizing the importance of long-term studies
Dark-pigmented biodeteriogenic fungi in etruscan hypogeal tombs: New data on their culture-dependent diversity, favouring conditions, and resistance to biocidal treatments
No full textSubterranean Cultural Heritage sites are frequently subject to biological colonization due to the high levels of humidity, even in conditions of low irradiance and oligotrophy. Here microorganisms form complex communities that may be dangerous through mineral precipitation, through the softening of materials or causing frequent surface discolorations. A reduction of contamination’s sources along with the control of microclimatic conditions and biocide treatments (overall performed with benzalkonium chloride) are necessary to reduce microbial growths. Dark discolorations have been recorded in the painted Etruscan tombs of Tarquinia, two of which have been analyzed to collect taxonomical, physiological, and ecological information. Eighteen dark-pigmented fungi were isolated among a wider culturable fraction: nine from blackening areas and nine from door sealings, a possible route of contamination. Isolates belonged to three major groups: Chaetothyriales, Capnodiales (Family Cladosporiaceae), and Acremonium-like fungi. Exophiala angulospora and Cyphellophora olivacea, a novelty for hypogea, were identi!ed, while others need further investigations as possible new taxa. The metabolic skills of the detected species showed their potential dangerousness for the materials. Their tolerance to benzalkonium chloride-based products suggested a certain favouring effect through the decreasing competitiveness of less resistant species. The type of covering of the dromos may in"uence the risk of outer contamination. Fungal occurrence can be favoured by root penetration
Black Fungi In Etruscan Tombs Of Tarquinia: New Findings From Different Tombs
No full textThe high humidity characterizing subterranean environments promotes biological growth, de- spite their low irradiance and oligotrophy. Microbial metabolism can have a negative impact on cultural heritage artworks, necessitating the use of effective biocides to control them. Among biodeteriogens, fungi are particularly difficult to manage due to their diverse metabolic pat- terns and high dissemination rate. In a recent study performed on two painted Etruscan tombs in Tarquinia some dark discolorations were investigated to determine the possible causative agents of color changes, and tomb door seals were investigated as a possible route of contam- ination. Among the widest culturable fraction found we focused on eighteen dark-pigmented fungi. Assessing their metabolic skills and tolerance to two formulations of benzalkonium chlo- ride-based products revealed a risk for hypogea that extends far beyond their color
Roots Damages In Etruscan Tombs And Biomolecular Tools For Their Identification
No full textPlant roots represent a treat for building structures and especially for underground historical artefacts. Etruscan tombs and their fragile painted walls are root-endangered heritages due to their proximity to the ground level. For this reason, as a preventive measure in the archaeolog- ical sites trees and bushes are generally rare and monitored, instead of spontaneous herbs are subject to periodic mowing. Nevertheless, root penetration in the burial chambers is a quite frequent phenomenon and customized measures are needed. The first step in customizing new control measures is tied to identifying the most dangerous herbaceous species through root identification. In this study, recent data and evidence are reported and discussed
Fungi Affecting Wall Paintings of Historical Value: A Worldwide Meta-Analysis of Their Detected Diversity
Full text linkWall paintings have been a cultural expression of human creativity throughout history. Their degradation or destruction represents a loss to the world’s cultural heritage, and fungi have been identified as a major contributor to their decay. We provide a critical review of fungi isolated from worldwide wall paintings between 1961–2021. One‐hundred three scientific papers were reviewed focusing on fungal diversity, isolation protocols, and spatial distribution of data. The study sites were grouped into five environmental categories on the basis of the expected major microclimatic conditions (temperature, relative humidity, ventilation), and the possible relationship with the species found was investigated. The highest number of records were localized in Europe, with 38 sites on a total of 74, 20 of which were from Italy. A total of 378 fungal entries were obtained, consisting of 1209 records, belonging to 260 different species and 173 genera. The accuracy level in taxa determination was highly variable among different papers analyzed. Data showed a dominance of Ascomycota, mainly of orders Eurotiales and Hypocreales probably due to their wide distribution and easily air dispersed spores and due to the possible pitfalls linked to the isolation methods, favoring rapidly growing taxa. Statistical analyses revealed that fungal communities were not strictly linked to environmental categories with different ventilation, temperature, and humidity. Such findings may be due to the wide geographical area, the wide heterogeneity of the data, and/or the absence of standardized sampling and analyses protocols. They could also be the result of the dominance of some prevailing factors in the various sites that mask the influence one of each other
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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