Shotgun metagenomic analysis of kombucha mutualistic community exposed to Mars-like environment outside the International Space Station

Kombucha is a multispecies microbial ecosystem mainly composed of acetic acid bacteria and osmophilic acid-tolerant yeasts, which is used to produce a probiotic drink. Furthermore, Kombucha Mutualistic Community (KMC) has been recently proposed to be used during long space missions as both a living functional fermented product to improve astronauts' health and an efficient source of bacterial nanocellulose. In this study, we compared KMC structure and functions before and after samples were exposed to the space/Mars-like environment outside the International Space Station in order to investigate the changes related to their re-adaptation to Earth-like conditions by shotgun metagenomics, using both diversity and functional analyses of Community Ecology and Complex Networks approach. Our study revealed that the long-term exposure to space/Mars-like conditions on low Earth orbit may disorganize the KMC to such extent that it will not restore the initial community structure; however, KMC core microorganisms of the community were maintained. Nonetheless, there were no significant differences in the community functions, meaning that the KMC communities are ecologically resilient. Therefore, despite the extremely harsh conditions, key KMC species revived and provided the community with the genetic background needed to survive long periods of time under extraterrestrial conditions.     

Elaphoglossum gemmatum (Elaphoglossaceae), a new species from Colombia

Elaphoglossum gemmatum, a species of proliferous fern from Colombia, is described, illustrated, and compared to the most similar species,E. exsertipes, E. phyllitidis, andE. proliferans.     

Effects of succinylacetone on dimethylsulfoxide-mediated induction of heme pathway enzymes in mouse Friend virus-transformed erythroleukemia cells

Heme has been reported to exert a control over its own biosynthesis and to affect the erythroid differentiation process at different sites. In this study, succinylacetone, a powerful inhibitor of δ-aminolevulinic acid dehydrase was used to block heme synthesis and to study the effects of heme depletion on the dimethylsulfoxide (DMSO)-mediated induction of the heme pathway enzymes in Friend virus-transformed erythroleukemia cells. The presence of succinylacetone in the medium during the DMSO treatment (1) potentiates the induction of δ-aminolevulinic acid synthetase (the first enzyme of the pathway) and this effect is reversed by the addition of exogenous hemin; (2) does not affect the induction of δ-aminolevulinic acid dehydrase (the second enzyme); (3) prevents the induction of porphobilinogen deaminase (the third enzyme), since no increase could be detected in either the enzyme activity or the immunoreactive protein and this effect could not be reversed by the addition of exogenous hemin; (4) does not affect the induction of ferrochelatase. The possible role of heme or of intermediate metabolites of the pathway on the induction of these enzymes during the erythroid differentiation process is discussed.     

Assessment of the impact of photosystem I chlorophyll fluorescence on the pulse-amplitude modulated quenching analysis in leaves of Arabidopsis thaliana

Photosynthesis Research - In their natural environment, plants are exposed to varying light conditions, which can lead to a build-up of excitation energy in photosystem (PS) II. Non-photochemical...     

From the freezer to the clinic: Antifreeze proteins in the preservation of cells,tissues, and organs

Understanding the mechanisms by which natural anti‐freeze proteins protect cells and tissues from cold could help to improve the availability of donor organs for transplantation.

The first successful organ transplant in humans was performed in 1954 by Joseph Murray, who used a patient’s twin as a kidney donor. Murrays’ breakthrough paved the way for organ transplantation and the number of transplanted organs has grown ever since. For example, in 2017, a total of 139.024 solid organs—mostly kidney, liver, heart, lung, pancreas, and small bowel—were transplanted (Fig 1A). But this number only reflects 10% of the worldwide need; many patients still die of end‐stage organ failure while on a waiting list. The limited number of donor organs contributes only partially to this shortage. Many donor organs are not transplanted eventually owing to inefficient preservation techniques that shorten their extracorporeal lifetime. In fact, the percentage of donor organs that are unused is estimated to range from around 25% for kidneys and livers up to 70–80% for hearts and lungs (Giwa et al, 2017); Fig 1B).Open in a separate windowFigure 1Organ transplantation and preservability statusStatistics show a positive correlation between the duration of ex vivo preservation and the number of organ transplants. Number of solid organs transplanted in 2017 (A). Percentage of organs failed to be transplanted (B). Duration of solid organ ex vivo preservation in static cold storage (C). Sources: Data from the Global Observatory on Donation and Transplantation and (Parsons et al, 2014), (Guibert et al, 2011) and (Editorial: Buying time for transplants (2017))

Many donor organs are not transplanted eventually owing to inefficient preservation techniques that shorten their extracorporeal lifetime.

To address the shortage of donor organs and decrease the number of organs that go to waste, biobanks could efficiently store viable tissues and organs until transplantation. Yet, the current standard for ex vivo preservation of donor organs is static cold storage (4–8°C) which, depending on the organ, ensures viable conservation for only some hours; hearts are typically viable for a maximum of only 4 h (Fig 1C). In addition, this approach leads to hypothermic damage and to ischemia/reperfusion injury.Hence, there is an urgent need for strategies that prolong the viable preservation of donor organs. Two main strategies have emerged for cryopreservation and subzero storage, both of which cool tissues below the freezing point. While subzero storage just below 0°C may suffice for short‐term preservation, cryopreservation at −80°C or even lower temperatures is required for long‐term storage in biobanks. A proof‐of‐principle study already demonstrated that subzero preservation extended the preservation of rat hearts up to 24 h after collection (Amir et al, 2004); cryopreservation of whole hearts is currently not possible. The main reason is that lowering the temperature below the freezing point of water leads to ice formation, which causes cell damage and destroys tissues. One of the main challenges in biomedical research for organ transplantation is therefore finding non‐toxic and biocompatible antifreeze compounds that enable subzero storage and cryopreservation without causing tissue damage. An additional benefit is a larger time window to perform evaluation in terms of organ size and human leukocyte antigens matching and preparing the recipient patient to increase the chance of a successful transplantation.     

Distinct sensitivity of fungal freshwater guilds to water quality

Multiple anthropogenic stressors have been shown to impact animal and plant communities in freshwater ecosystems, but the responses of aquatic fungi remain largely unknown. Stressor effects on fungal communities may, however, result in changes of decomposition of plant litter and, thus, impact nutrient cycling, a key process for ecosystem functioning. We tested the impact of increased chloride and sediment levels, as well as reduced water flow velocity, on eukaryotic freshwater communities, with an emphasis on fungi, in a mesocosm experiment. Each of the three stressors was applied individually and in all combinations in a full-factorial design. Litterbags with non-sterilised tree leaves and sterile ceramic tiles were added to the mesocosms, to analyse the responses of communities in decaying plant material and in biofilms. Fungi preferably occurring in biofilms were supposed to represent indigenous aquatic fungi, while litterbag communities should be predominantly composed of fungi known from terrestrial litter. Community composition was assessed by high-throughput sequencing of amplified barcoding regions. Similarity matrices of operational taxonomic unit (OTU) tables calculated by UCLUST and CD-HIT-OTU-Illumina were significantly correlated. Preferred occurrence in biofilm and litter communities, respectively, was used for the grouping of OTUs into three ecological guilds. Stressor sensitivity varied among the guilds. While non-fungal, in particular autotrophic, OTUs responded to several treatments, two of the fungal guilds, i.e. those exclusively colonising litter and those preferably occurring on the ceramic tiles, showed no response to any applied treatment. Only fungi preferably, but not exclusively, colonising litter significantly responded to chloride addition. Their distribution patterns again correlated significantly with those of non-fungal OTUs, indicating possible interdependencies between both groups. The results indicate that eukaryotic freshwater communities are composed of different guilds, with distinctive sensitivity and tolerance to anthropogenic stressors.     

Ghrelin delays premature aging in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal genetic condition that arises from a single nucleotide alteration in the LMNA gene, leading to the production of a defective lamin A protein known as progerin. The accumulation of progerin accelerates the onset of a dramatic premature aging phenotype in children with HGPS, characterized by low body weight, lipodystrophy, metabolic dysfunction, skin, and musculoskeletal age-related dysfunctions. In most cases, these children die of age-related cardiovascular dysfunction by their early teenage years. The absence of effective treatments for HGPS underscores the critical need to explore novel safe therapeutic strategies. In this study, we show that treatment with the hormone ghrelin increases autophagy, decreases progerin levels, and alleviates other cellular hallmarks of premature aging in human HGPS fibroblasts. Additionally, using a HGPS mouse model (Lmna^G609G/G609G mice), we demonstrate that ghrelin administration effectively rescues molecular and histopathological progeroid features, prevents progressive weight loss in later stages, reverses the lipodystrophic phenotype, and extends lifespan of these short-lived mice. Therefore, our findings uncover the potential of modulating ghrelin signaling offers new treatment targets and translational approaches that may improve outcomes and enhance the quality of life for patients with HGPS and other age-related pathologies.