Sun exposure drives Antarctic cryptoendolithic community structure and composition

AbstractThe harsh environmental conditions of the ice-free regions of Continental Antarctica are considered one of the closest Martian analogues on Earth. There, rocks play a pivotal role as substratum for life and endolithism represents a primary habitat for microorganisms when external environmental conditions become incompatible with active life on rock surfaces. Due to the thermal inertia of rock, the internal airspace of lithic substratum is where microbiota find a protected and buffered microenvironment, allowing life to spread throughout these regions with extreme temperatures and low water availability. The high degree of adaptation and specialization of the endolithic communities makes them highly resistant but scarsely resilient to any external perturbation and thus, any shifts in microbial community composition may serve as early-alarm systems of environmental perturbation, including climate change.Previous research concluded that altitude and distance from sea do not play as driving factors in shaping microbial abundance and diversity, while sun exposure was hypothesized as significant parameter influencing endolithic settlement and development. This study aims to explore our hypothesis that changes in sun exposure translate to shifts in community composition and abundances of main biological compartments (fungi, algae and bacteria) in the Antarctic cryptoendolithic communities. We performed a preliminary molecular survey, based on DGGE and qPCR tecniques, of 48 rocks with varying sun exposure, collected in Victoria Land along an altitudinal transect from 834 to 3100 m a.s.l.Our findings demonstrate that differences in sun radiation between north and south exposure influence temperature of rocks surface, availability of water and metabolic activity and also have significant impact on community composition and microbial abundance

A Digital Role-Playing Game for the History of Medicine

Edward Jenner's 1798 smallpox vaccine was a breakthrough against an epidemic disease, and its subsequent role as a public health measure demonstrates the interplay of disease, patient, healers, and social institutions in medical history. Our project, Pox and the City: A Digital Role-Playing Game for the History of Medicine, explores these complex interrelationships in a format that will enhance existing humanities teaching and enable historians of medicine to reach new audiences. The game, a collaboration between historians of medicine and Serious Games specialists, can be played as a smallpox doctor, a virus, or a patient. The grant will be used to create and test the first level of the game for each of these characters. Pox and the City makes use of the world-renowned historical collection of books, ephemera, images, and artifacts held by the College of Physicians in Philadelphia. The outcome will be an open-source, Flash-based RPG for use in web-based and GeoDome applications

Hydrocarbon-Contaminated Sites: Is There Something More Than Exophiala xenobiotica? New Insights into Black Fungal Diversity Using the Long Cold Incubation Method

Human-made hydrocarbon-rich environments are important reservoirs of microorganisms with specific degrading abilities and pathogenic potential. In particular, black fungi are of great interest, but their presence in the environment is frequently underestimated because they are difficult to isolate. In the frame of a biodiversity study from fuel-contaminated sites involving 30 diesel car tanks and 112 fuel pump dispensers (52 diesel and 60 gasoline, respectively), a total of 181 black fungal strains were isolated. The long cold incubation (LCI) of water-suspended samples, followed by plating on Dichloran Rose Bengal Chloramphenicol Agar (DRBC), gave isolation yields up to six times (6.6) higher than those of direct plating on DRBC, and those of enrichment with a phenolic mix. The sequencing of ITS and LSU-rDNA confirmed the dominance of potentially pathogenic fungi from the family Herpotrichiellaceae and Exophiala xenobiotica. Moreover, other opportunistic species were found, including E. opportunistica, E. oligosperma, E. phaeomuriformis, and Rhinocladiella similis. The recurrent presence of E. crusticola, Knufia epidermidis, Aureobasidium melanogenum, Cladosporium spp., and Scolecobasidium spp. was also recorded. Interestingly, 12% of total isolates, corresponding to 50% of taxa found (16/32), represent new species. All the novel taxa in this study were isolated by LCI. These findings suggest that black fungal diversity in hydrocarbon-rich niches remains largely unexplored and that LCI can be an efficient tool for further investigations.info:eu-repo/semantics/publishedVersio

Integrity of the DNA and Cellular Ultrastructure of Cryptoendolithic Fungi in Space or Mars Conditions: A 1.5-Year Study at the International Space Station

The black fungi Cryomyces antarcticus and Cryomyces minteri are highly melanized and are resilient to cold, ultra-violet, ionizing radiation and other extreme conditions. These microorganisms were isolated from cryptoendolithic microbial communities in the McMurdo Dry Valleys (Antarctica) and studied in Low Earth Orbit (LEO), using the EXPOSE-E facility on the International Space Station (ISS). Previously, it was demonstrated that C. antarcticus and C. minteri survive the hostile conditions of space (vacuum, temperature fluctuations, and the full spectrum of extraterrestrial solar electromagnetic radiation), as well as Mars conditions that were simulated in space for a 1.5-year period. Here, we qualitatively and quantitatively characterize damage to DNA and cellular ultrastructure in desiccated cells of these two species, within the frame of the same experiment. The DNA and cells of C. antarcticus exhibited a higher resistance than those of C. minteri. This is presumably attributable to the thicker (melanized) cell wall of the former. Generally, DNA was readily detected (by PCR) regardless of exposure conditions or fungal species, but the C. minteri DNA had been more-extensively mutated. We discuss the implications for using DNA, when properly shielded, as a biosignature of recently extinct or extant life

Life beyond Earth: the antarctic black fungus in planetary simulations

The cryptoendolithic black fungus Cryomyces antarcticus inhabits the ice-free area of the Antarctic McMurdo Dry Valleys, one of the best terrestrial analogue environment for Mars. There, conditions on rock surface are often incompatible with life; hence, microbes develop within porous rocks as last chance for survival. The almost complete isolation over a timescale of evolutionary significance led to the evolution of unique, extremely adapted and resistant, genotypes. C. antarcticus is particularly skilled in stress tolerance being able to tolerate injuries well beyond the harsh conditions of its natural environment. Because of its uncommon resistance, the fungus has been chosen as eukaryotic model for astrobiological studies to test the endurance of eukaryotic cells to space conditions. In the experiment here reported, the fungus C. antarcticus was exposed, in the frame of the STARLIFE irradiation campaign, to different types and qualities of ionizing radiation with different linear energy transfer values (0.2 to 200 keV/µm). Irradiation with up to 1 kGy of accelerated He, Ar and Fe ions, and 55.57 kGy of gamma rays (60Cobalt). Single gene PCR, RAPD fingerprinting, qPCR and PMA coupled with qPCR analyses reveal minimal damage to DNA or plasma membranes induced by the treatments. This experiments further confirm the stunning stress tolerance of the fungus and its high relevance in astrobiological investigations, including the search for life on Mars, the reliability of the Lithopanspermia theory, and the estimation of planetary contamination risk

Neonatal treatment with clomipramine induces morphological and cellular changes in the adult rat brain

Clomipramine (CLI) is a tricyclic serotonin reuptake blocker, widely used to treat depression, obsessive compulsive disorder (OCD), and other psychiatric conditions in human patients. Chronic CLI administration in the neonate rodent alters serotonergic circuits and serotonine levels in the brain, and has been reported to cause a complex pattern of behavioral changes in the adult life, including abnormalities of rapid eye movement sleep, decreased aggression and sexual behavior, anhaedonia and helplessness. Such symptoms suggest a parallel with humans endogenous depression and have been proposed as a novel animal model of OCD. The present study was aimed at identifying morphological and cellular changes after chronic neonatal treatment with clomipramine (daily i.p. injections, 20 mg/kg, from P5 to P21) in the brain of 5 month-old male Sprague-Dawley rats, compared to saline-treated littermates, using three distinct experimental approaches. 1) In vivo volumetric analyses based on structural MRI scans performed at 4.7T on 6 CLI-treated and 6 control rats revealed a significant reduction in total brain and hippocampal volume, as well as enlarged ventricles in CLI-treated rats, compared to saline-treated cohorts. 2) In order to investigate treatment-related developmental disorders, we studied the dendritic arborization of newly generated cells in the hippocampus of 7 CLI and 7 control rats. Two-dimensional dendritic tracing diagrams were reconstructed with Neurolucida, and quantitative analyses of total dendritic length and arborization indices in the two groups are still ongoing. 3) Brain-derived neurotrophic factor (BDNF) levels were assessed in the hippocampus and neocortex of 5 CLI and 5 control rats by ELISA assay. Interestingly, we found significant region-specific, between-group differences. In particular, BDNF levels, important for neurogenesis, differentiation and neuronal survival, and highly expressed in brain areas involved in cognitive and emotional behavior, were significantly decreased in the hippocampus of CLI rats compared to controls, whereas no differences were found in the cortex. Taken together, the data suggest that interfering with serotonergic regulation during early postnatal development can produce permanent brain changes. These resemble brain abnormalities repeatedly observed not only in human depression but also in schizophrenia. Further morphological analyses as well as experiments aimed at characterizing the behavioral correlates of early CLI administration are in progress

Wide divergence of fungal communities inhabiting rocks and soils in a hyper‐arid Antarctic desert

Highly simplified microbial communities colonise rocks and soils of continental Antarctica ice-free deserts. These two habitats impose different selection pressures on organisms, yet the possible filtering effects on the diversity and composition of microbial communities have not hitherto been fully characterised. We hence compared fungal communities in rocks and soils in three localities of inner Victoria Land. We found low fungal diversity in both substrates, with a mean species richness of 28 across all samples, and significantly lower diversity in rocks than in soils. Rock and soil communities were strongly differentiated, with a multinomial species classification method identifying just three out of 328 taxa as generalists with no affinity for either substrate. Rocks were characterised by a higher abundance of lichen-forming fungi (typically Buellia, Carbonea, Pleopsidium, Lecanora, and Lecidea), possibly owing to the more protected environment and the porosity of rocks permitting photosynthetic activity. In contrast, soils were dominated by obligate yeasts (typically Naganishia and Meyerozyma), the abundances of which were correlated with edaphic factors, and the black yeast Cryomyces. Our study suggests that strong differences in selection pressures may account for the wide divergences of fungal communities in rocks and soils of inner Victoria Land

Antarctic Cryptoendolithic Fungal Communities Are Highly Adapted and Dominated by Lecanoromycetes and Dothideomycetes

Endolithic growth is one of the most spectacular microbial adaptations to extreme environmental constraints and the predominant life-form in the ice-free areas of Continental Antarctica. Although Antarctic endolithic microbial communities are known to host among the most resistant and extreme-adapted organisms, our knowledge on microbial diversity and composition in this peculiar niche is still limited. In this study, we investigated the diversity and structure of the fungal assemblage in the cryptoendolithic communities inhabiting sandstone using a meta-barcoding approach targeting the fungal Internal Transcribed Sequence region 1 (ITS1). Samples were collected from 14 sites in the Victoria Land, along an altitudinal gradient ranging from 1,000 to 3,300 m a.s.l. and from 29 to 96 km distance to coast. Our study revealed a clear dominance of a ‘core’ group of fungal taxa consistently present across all the samples, mainly composed of lichen-forming and Dothideomycetous fungi. Pareto-Lorenz curves indicated a very high degree of specialization (F0 approximately 95%), suggesting these communities are highly adapted but have limited ability to recover after perturbations. Overall, both fungal community biodiversity and composition did not show any correlation with the considered abiotic parameters, potentially due to strong fluctuations of environmental conditions at local scales

Biosignature stability in space enables their use for life detection on Mars

Two rover missions to Mars aim to detect biomolecules as a sign of extinct or extant life with, among other instruments, Raman spectrometers. However, there are many unknowns about the stability of Raman-detectable biomolecules in the martian environment, clouding the interpretation of the results. To quantify Raman-detectable biomolecule stability, we exposed seven biomolecules for 469 days to a simulated martian environment outside the International Space Station. Ultraviolet radiation (UVR) strongly changed the Raman spectra signals, but only minor change was observed when samples were shielded from UVR. These findings provide support for Mars mission operations searching for biosignatures in the subsurface. This experiment demonstrates the detectability of biomolecules by Raman spectroscopy in Mars regolith analogs after space exposure and lays the groundwork for a consolidated space-proven database of spectroscopy biosignatures in targeted environments