The Didymellaceae is one of the most species-rich families in the fungal kingdom, and includes species that inhabit a wide range of ecosystems. The taxonomy of Didymellaceae has recently been revised ...on the basis of multi-locus DNA sequence data. In the present study, we investigated 108 Didymellaceae isolates newly obtained from 40 host plant species in 27 plant families, and various substrates from caves, including air, water and carbonatite, originating from Argentina, Australia, Canada, China, Hungary, Israel, Italy, Japan, South Africa, the Netherlands, the USA and former Yugoslavia. Among these, 68 isolates representing 32 new taxa are recognised based on the multi-locus phylogeny using sequences of LSU, ITS, rpb2 and tub2, and morphological differences. Within the Didymellaceae, five genera appeared to be limited to specific host families, with other genera having broader host ranges. In total 19 genera are recognised in the family, with Heracleicola being reduced to synonymy under Ascochyta. This study has significantly improved our understanding on the distribution and biodiversity of Didymellaceae, although the placement of several genera still need to be clarified.
When tunnels are excavated in karst areas, the existence of karst caves in the surrounding rock usually results in the collapse failure of tunnels. Tunnel collapse has always been a challenging issue ...because it seriously threatens the safety of tunnel builders. To investigate the collapse of a deep tunnel under a karst cave, we constructed the collapse mechanisms of the rectangular and circular tunnels under a karst cave, and obtained the expressions of the collapse failure in tunnel considering seismic force and seepage force by means of the variational principle and limit analysis theory. Compared with previous results and numerical solutions, it is found that the results in this paper are consistent with those results and numerical solutions, which indicates that the proposed method in this work is rational. According to the analytical solutions, the shape of the collapsing blocks of the deep rectangular and circular tunnels under a karst cave are drawn, and the effects of different parameters, especially the vertical seismic coefficient kv, on the collapsing blocks are analyzed. The findings in this paper indicate that the range of collapsing blocks decreases with increased kv. The two formulas for calculating the critical height between the tunnel and the karst cave are given by derivation.
Due to insufficient research on the collapsing range of karst rectangular and circular tunnels:•We constructed a new failure mechanism of rectangular and circular tunnels under a karst cave.•The effect of seismic force is considered in this paper.•The expressions of the collapsing block of deep tunnels under a karst cave can be obtained.•The influence of various parameters on the collapsing range is demonstrated.
This paper investigates the dynamic responses of bottom karst caves on the shield tunnels under oblique SV waves according to the project of Dalian Metro Line 5. The viscous-spring artificial ...boundaries are employed and validated to assure the accuracy of seismic input. The characteristics of deformation and stress, damage evolution process and damage state of the tunnel are discussed, such as under different filling conditions of karst caves, incident angles of SV waves, the elastic modulus of grouting materials, and the combination of multiple karst caves. According to the relationship between tensile damage value and crack width, the damage state classification is divided. The results show that the tunnel’s displacement and stress increase and the damage state is from no damage to severe damage with the increasing incident angle. When the incident angle is 30°, the tunnel’s displacement and stress reach to the maximum, and the axial cracks width higher than 0.2 mm appear on the outer surface of the vault and bottom. The filling conditions of the bottom karst caves can influence the tunnel’s circumferential damage. The structural dynamic response does not change significantly when the elastic modulus of the grouting material is greater than 10 GPa. Compared with one single cave, the damage severity of the inner surface under the multiple karst caves with a large clear distance is weakened and tends to be averaged.
Palaeolithic cave art in Borneo Aubert, M; Setiawan, P; Oktaviana, A A ...
Nature (London),
12/2018, Letnik:
564, Številka:
7735
Journal Article
Recenzirano
Figurative cave paintings from the Indonesian island of Sulawesi date to at least 35,000 years ago (ka) and hand-stencil art from the same region has a minimum date of 40 ka
. Here we show that ...similar rock art was created during essentially the same time period on the adjacent island of Borneo. Uranium-series analysis of calcium carbonate deposits that overlie a large reddish-orange figurative painting of an animal at Lubang Jeriji Saléh-a limestone cave in East Kalimantan, Indonesian Borneo-yielded a minimum date of 40 ka, which to our knowledge is currently the oldest date for figurative artwork from anywhere in the world. In addition, two reddish-orange-coloured hand stencils from the same site each yielded a minimum uranium-series date of 37.2 ka, and a third hand stencil of the same hue has a maximum date of 51.8 ka. We also obtained uranium-series determinations for cave art motifs from Lubang Jeriji Saléh and three other East Kalimantan karst caves, which enable us to constrain the chronology of a distinct younger phase of Pleistocene rock art production in this region. Dark-purple hand stencils, some of which are decorated with intricate motifs, date to about 21-20 ka and a rare Pleistocene depiction of a human figure-also coloured dark purple-has a minimum date of 13.6 ka. Our findings show that cave painting appeared in eastern Borneo between 52 and 40 ka and that a new style of parietal art arose during the Last Glacial Maximum. It is now evident that a major Palaeolithic cave art province existed in the eastern extremity of continental Eurasia and in adjacent Wallacea from at least 40 ka until the Last Glacial Maximum, which has implications for understanding how early rock art traditions emerged, developed and spread in Pleistocene Southeast Asia and further afield.
•A biofilm-like microbial community from a pristine cave in New Guinea was studied.•Metagenomic analyses revealed the predominance of Proteobacteria and Actinobacteria.•Chemoorganotrophy was the main ...metabolism of microbial community members.•Antibiotic resistance was predicted by metagenome analysis and confirmed in vitro.•Several unassignable taxonomic entities were isolated from the community.
Caves are extreme environments inhabited by microbial communities adapted to thrive oligotrophic conditions. Cave microbes are organised in complex ecological networks and have developed survival strategies involving the production and release of a large variety of secondary metabolites, including antibiotic-like compounds. In this study, the structure and the metabolic features of a biofilm-like microbial community lining the walls of a pristine karst cavity (the Yumugi river cave) located in a remote region of the Western New Guinea were investigated. 16S rRNA and shotgun sequence analyses highlighted the prevalence of chemoorganotrophic phyla (Proteobacteria, Actinobacteria, Firmicutes and Acidobacteria), consistent with metabolic predictions inferred from the cave metagenome analysis. Few clinically relevant antimicrobial resistance genes were detected. A culture-based approach allowed the isolation of some heterotrophic members of the bacterial community, and antimicrobial susceptibility testing revealed an overall high level of resistance to different antimicrobials classes. Isolates presumptively representing new uncharacterized members of genus Pseudomonas displayed interesting antibiotic properties against Gram-positive indicator strains. Our work supports the hypothesis that caves represent a reservoir for new bacterial species and drug discovery research.
Coal is the major energy source in China. Many coal mines in Southwest China have arranged the excavation roadway system in the Maokou limestone in coal seam floor because of its special ...hydrogeological conditions. Since karst is widely distributed in Maokou limestone and water-filled karst caves are also developed commonly there, once a strongly water-filled karst cave is exposed during roadway excavation, the water inrush disaster occurs easily. In order to reveal the phenomenon of water inrush disasters from covered karst caves more effectively, the water inrush that occurred during the roadway excavation process of Jiyuan coal mine in northern Guizhou was taken as a research object in this study. Based on the regional geological structure, the hydrogeological condition and the fluid-structure interaction theory, a fluid-structure interaction model of water inrush in the roadway excavation was established, and variation laws of stress field, displacement field and seepage field of surrounding rock during the process of water inrush from karst cave were analyzed. Besides, the influence of different geological conditions on water inrush from karst cave was discussed from aspects of the size of karst cave, the water pressure of karst cave and the thickness of aquiclude.
Fouling communities with the dominance of phototrophs such as cyanobacteria, algae, bryophytes, and ferns are formed in the illuminated zone of the caves. These communities includes also ...heterotrophic species—bacteria and micromycetes, often with the high abundance of the latter, indicating significant role of micromycetes for the developing of fouling communities.In this study we examined the micromycete species composition in the phototrophic communities of five caves, i.e., Golubinja Pećina, Veluštica Pećina, Njegoš Pećina, Vrbačka jama, Jama ER-1 located on the territory of Lovćen National Park in the southwestern Montenegro. Species identification was performed using standard approaches and cultivation methods. In total, 35 species of micromycetes were identified from the phototroph communities of the studied caves. Our study revealed that the species composition of micromycetes was unique for each of the investigated cave. The most frequent species was Rhizopus stolonifer, identified from Golubinja Pećina, Vrbačka jama, and Jama ER-1. Two species, i.e., Aspergillus terreus (found in Veluštica Pećina and Jama ER-1), and Cladosporium oxysporum (found in Golubinja Pećina and Veluštica Pećina) were found each in two caves, whereas all other species were reported from a single cave.
Karst caves are a natural oligotrophic subsurface biosphere widely distributed in southern China. Despite the progress in bacterial and fungal diversity, the knowledge about interactions between ...bacteria, fungi, and minerals is still limited in caves. Hence, for the first time, we investigated the interaction between bacteria and fungi living on weathered rocks in the Heshang Cave
via
high-throughput sequencing of 16S rRNA and ITS1 genes, and co-occurrence analysis. The mineral compositions of weathered rocks were analyzed by X-ray diffraction. Bacterial communities were dominated by
Actinobacteria
(33.68%), followed by
Alphaproteobacteria
(8.78%), and
Planctomycetia
(8.73%). In contrast, fungal communities were dominated by
Sordariomycetes
(21.08%) and
Dothideomycetes
(14.06%). Mineral substrata, particularly phosphorus-bearing minerals, significantly impacted bacterial (hydroxyapatite) and fungal (fluorapatite) communities as indicated by the redundancy analysis. In comparison with fungi, the development of bacterial communities was more controlled by the environmental selection indicated by the overwhelming contribution of deterministic processes. Co-occurrence network analysis showed that all nodes were positively linked, indicating ubiquitous cooperation within bacterial groups and fungal groups, as well as between bacteria and fungi under oligotrophic conditions in the subsurface biosphere. In total, 19 bacterial ASVs and 34 fungal OTUs were identified as keystone taxa, suggesting the fundamental role of fungi in maintaining the microbial ecosystem on weathered rocks.
Ascomycota
was most dominant in keystone taxa, accounting for 26.42%, followed by
Actinobacteria
in bacteria (24.53%). Collectively, our results confirmed the highly diverse bacterial and fungal communities on weathered rocks, and their close cooperation to sustain the subsurface ecosystem. Phosphorus-bearing minerals were of significance in shaping epipetreous bacterial and fungal communities. These observations provide new knowledge about microbial interactions between bacteria, fungi, and minerals in the subterranean biosphere.
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