Microlophus atacamensis as a biomonitor of coastal contamination in the Atacama Desert, Chile: An evaluation through a non-lethal technique.

In this report, we investigated the accumulation of heavy metals in the lizard Microlophus atacamensis, in three coastal areas of the Atacama Desert, northern Chile. We captured reptiles in a non-intervened area (Parque Nacional Pan de Azúcar, PAZ), an area of mining impact (Caleta Palitos, PAL) and an active industrial zone (Puerto de Caldera, CAL). Our methods included a non-lethal sampling of reptiles' tails obtained by autotomy and a few sacrificed animals to perform a stomach contents analysis. The concentrations of lead, copper, nickel, zinc and cadmium were measured by atomic absorption spectrophotometry in both soil and prey and compared to those recorded in the lizards' tails. Data obtained from lizard tails captured in PAL showed significantly high concentrations of Pb, Cu, Ni, and Zn compared to the other two sites PAZ and CAL. We did not find statistically significant differences among PAZ, PAL and CAL soils, probably due to the similar geological composition of the sites. However, the regional background values for Pb indicate contamination or at least metal enrichment in soils of the three sites, for Cu the global background values indicate contamination for the three sites, and for Cd both the regional and global backgroud values show high values. The analysis of the stomach content showed differences in the food sources of the lizards among the sites studied. The concentration of heavy metal in lizard tissues versus prey delivered values of the Trophic Transfer Factor higher than one (1), suggesting that food may be a primary source of metals in the tissues of M. atacamensis. Calculations of the Bioaccumulation Factor (BAF) and the Ecological Risk (IR) resulted in values higher than one (1) indicating the relevance of this process in the sites studied. In this article, we report relationships between environmental contaminants, mainly putative preys, and concentrations found in lizard tails, which is more substantial in areas with historical heavy metal contamination such as PAL where the non-lethal technique developed in this research suggests a process of metal bioaccumulation in M. atacamensis.

Data on metal accumulation in the tails of the lizard Microlophus atacamensis in a coastal zone of the Atacama Desert, northern Chile: A non-destructive biomonitoring tool for heavy metal pollution.

In this data article, we investigated the accumulation of heavy metals in the lizard Microlophus atacamensis, in three coastal areas of the Atacama Desert, northern Chile. We captured lizards in a non-intervened area (Parque Nacional Pan de Azucar, PAZ), an area of mining impact (Caleta Palitos, PAL) and an active industrial zone (Puerto de Caldera, CAL). Our methods included a non-lethal sampling of lizard's tails obtained by autotomy. The concentrations of lead, copper, nickel, zinc and cadmium were measured in both soil and prey and compared to those recorded in the lizards' tails. We estimated metal concentrations in the soil, in putative prey and M. atacamensis tails, using atomic absorption spectrophotometry. In order to characterize the trophic ecology of M. atacamensis and to relate it to possible differences in metal loads between sites, we included a few slaughtered animals to perform a stomach contents analysis (SCA). The software R Core Team (2019) was used to carry out all statistical tests to evaluate and analyze the data, applying a priori and a posteriori statistical tests to test the variance and mean hypotheses. Analysis of the data of the content of heavy metals in the tails, prey and soil inhabited by M. atacamensis in PAZ, PAL and CAL showed that the concentration of metals found in the tails and the range of environmental exposure to heavy metals of these animals were related. This article shows for the first time a quantification of the metal concentration on lizard tissues with a non-lethal technique in anthropically disturbed sites in the South Pacific.

Watershed-Induced Limnological and Microbial Status in Two Oligotrophic Andean Lakes Exposed to the Same Climatic Scenario.

Laguna Negra and Lo Encañado are two oligotrophic Andean lakes forming part of the system fed by meltwater from distinct glacial tongues of the Echaurren glacier in central Chile, which is in a recession period. The recent increase in temperature and decline in precipitation have led to an increase of glacial meltwater and sediments entering these lakes. Although the lacustrine systems are also hydrogeologically connected, the limnology of the lakes is strongly controlled by the surface processes related to the respective sub-watersheds and hydrology. Watershed characteristics (area and length, slope, lithology, resistance to erosion, among others) affect the chemical and physical characteristics of both lakes (e.g., nutrient concentration and turbidity). We studied physical and chemical variables and performed 16S rRNA amplicon sequencing to determine the specific microbial signature of the lakes. The transparency, temperature, turbidity and concentrations of chlorophyll-a, dissolved organic matter, nutrients and the total number of cells, revealed the different status of both lakes at the time of sampling. The predominant bacterial groups in both lakes were Proteobacteria, Verrucomicrobia, and Bacteroidetes. Interestingly, the contribution of phototrophs was significantly higher in LN compared to LE (13 and 4% respectively) and the major fraction corresponded to Anoxygenic Phototrophs (AP) represented by Chloroflexi, Alpha, and Betaproteobacteria. Multivariate analyses showed that the nutrient levels and the light availability of both lakes, which finally depend on the hydrological characteristics of the respective watersheds, explain the differential community composition/function. The abundance of a diverse photoheterotrophic bacterioplankton community suggests that the ability to utilize solar energy along with organic and inorganic substrates is a key function in these oligotrophic mountain lakes.

First draft genome sequence of a strain from the genus Fusibacter isolated from Salar de Ascotán in Northern Chile.

Fusibacter sp. 3D3 (ATCC BAA-2418) is an arsenate-reducing halotolerant strain within the Firmicutes phylum, isolated from the Salar de Ascotán, a hypersaline salt flat in Northern Chile. This high-Andean closed basin is an athalassohaline environment located at the bottom of a tectonic basin surrounded by mountain range, including some active volcanoes. This landscape can be an advantageous system to explore the effect of salinity on microorganisms that mediate biogeochemical reactions. Since 2000, microbial reduction of arsenic has been evidenced in the system, and the phylogenetic analysis of the original community plus the culture enrichments has revealed the predominance of Firmicutes phylum. Here, we describe the first whole draft genome sequence of an arsenic-reducing strain belonging to the Fusibacter genus showing the highest 16S rRNA gene sequence similarity (98%) with Fusibacter sp. strain Vns02. The draft genome consists of 57 contigs with 5,111,250 bp and an average G + C content of 37.6%. Out of 4780 total genes predicted, 4700 genes code for proteins and 80 genes for RNAs. Insights from the genome sequence and some microbiological features of the strain 3D3 are available under Bioproject accession PRJDB4973 and Biosample SAMD00055724. The release of the genome sequence of this strain could contribute to the understanding of the arsenic biogeochemistry in extreme environments.

Targeting Cx43 and N-cadherin, which are abnormally upregulated in venous leg ulcers, influences migration, adhesion and activation of Rho GTPases.

BACKGROUND: Venous leg ulcers can be very hard to heal and represent a significant medical need with no effective therapeutic treatment currently available. PRINCIPAL FINDINGS: In wound edge biopsies from human venous leg ulcers we found a striking upregulation of dermal N-cadherin, Zonula Occludens-1 and the gap junction protein Connexin43 (Cx43) compared to intact skin, and in stark contrast to the down-regulation of Cx43 expression seen in acute, healing wounds. We targeted the expression of these proteins in 3T3 fibroblasts to evaluate their role in venous leg ulcers healing. Knockdown of Cx43 and N-cadherin, but not Zonula Occludens-1, accelerated cell migration in a scratch wound-healing assay. Reducing Cx43 increased Golgi reorientation, whilst decreasing cell adhesion and proliferation. Furthermore, Connexin43 and N-cadherin knockdown led to profound effects on fibroblast cytoskeletal dynamics after scratch-wounding. The cells exhibited longer lamelipodial protrusions lacking the F-actin belt seen at the leading edge in wounded control cells. This phenotype was accompanied by augmented activation of Rac-1 and RhoA GTPases, as revealed by Förster Resonance Energy Transfer and pull down experiments. CONCLUSIONS: Cx43 and N-cadherin are potential therapeutic targets in the promotion of healing of venous leg ulcers, by acting at least in part through distinct contributions of cell adhesion, migration, proliferation and cytoskeletal dynamics.

Overexpression of the gap junction protein Cx43 as found in diabetic foot ulcers can retard fibroblast migration.

Poor healing of DFUs (diabetic foot ulcers) is a major clinical problem that can be extremely debilitating and lead to lower limb amputation. In the normal acute wound, the Cx43 (connexin 43) gap junction protein is down-regulated at the wound edge as a precursor to cell migration and healing. In fibroblasts from the human chronic DFU wound edge there was a striking and significant 10-fold elevation of Cx43 protein, as well as a 6-fold increase in N-cadherin and a 2-fold increase in ZO-1 (zonular occludin-1), compared with unwounded skin. In streptozotocin diabetic rats, Cx43 was found to be up-regulated in intact dermal fibroblasts in direct proportion to blood glucose levels and increased 2-fold further in response to wounding of the skin. To mimic diabetes, NIH 3T3 fibroblasts were cultured under different concentrations of glucose or mannitol and Cx43 protein intercellular communication and migration rates were determined. Cultures of fibroblasts in very high (40 mM) glucose conditions showed significantly elevated Cx43 protein levels, as shown by immunostaining and Western blotting, and significantly increasing gap junctional communication, as shown by dye transfer. In scratch wound-healing assays, increased levels of Cx43 from high glucose resulted in repressed filopodial extensions and significantly slower migration rates than in either standard conditions (5.5 mM glucose) or the osmotic control of mannitol. Conversely, when glucose-induced Cx43 up-regulation was prevented with Cx43shRNA (Cx43 short-hairpin RNA) transduction, the fibroblasts extended long filopodia and migrated significantly faster. Cx43 protein was up-regulated in fibroblasts in DFUs as well as after high glucose exposure in culture which correlated with inhibition of fibroblast migration and is likely to contribute to impaired wound healing.

Interleukin 10 decreases MICA expression on melanoma cell surface.

Natural-killer group 2, member D (NKG2D) binds to a variety of ligands, including the major histocompatibility complex (MHC) class I chain-related proteins (MIC) and UL16-binding proteins (ULBP). It is regarded as a co-activating receptor on NK cells, having an important role in the cell-mediated immune response to tumours. We studied the influence of interleukin (IL)-10 on the regulation of MIC and ULBP expression on melanoma cells, and its effect on the cytotoxic function of NK cells in vitro. Here, we show that, in the presence of IL-10, FMS mel and BL mel cell lines decreased MICA and ULBP2 surface expression, whereas MHC class I did not change substantially on the cell surface. MICA mRNA levels decreased in IL-10-treated FMS and IL-10-transduced BL cell lines. Interestingly, we observed that MICB surface expression and its mRNA levels increased upon IL-10 treatment in a melanoma cell line. These changes in NKG2D ligands surface expression patterns owing to IL-10 treatment resulted in an effect on lysis susceptibility mediated by lymphocyte-activated killer cells, as tumour cell lines that displayed a higher decrease of MICA on their surface had lower levels of lysis. In addition, expression of CD107a was downregulated on the surface of NK cells following stimulation with IL-10-treated FMS cells. Our results suggest a novel function for IL-10 in the modulation of NKG2D ligand expression and in the control of cytotoxicity mediated by NKG2D/NKG2D ligand axis.