Peruvian nudibranchs (Mollusca, Gastropoda, Heterobranchia): an updated literature review-based list of species.

Nudibranchs, as a group, have received limited attention in terms of scientific study along the coastline of Peru. Here, an updated and comprehensive list of nudibranch species found in the Peruvian sea is presented, compiled through an extensive review of relevant literature. This compilation encompasses a total of 31 species, classified into two suborders, 10 superfamilies, 20 families, and 28 genera. With respect to the biogeographic provinces along the Peruvian coast, 23 species inhabit the Warm Temperate Southeastern Pacific province, 18 species occur in the Tropical Eastern Pacific province, and 10 species are found in both provinces, crossing the transitional zone between them. In terms of distribution patterns, two species exhibit a cosmopolitan distribution (Glaucusatlanticus and Fionapinnata), while two species display a circumtropical distribution (Cephalopygetrematoides and Phylliroebucephala). One species exhibits a bipolar distribution in the Eastern Pacific and possesses an amphi-South American distribution (Rostangapulchra). Additionally, six species exhibit an amphi-South American distribution (Rostangapulchra, Diaululapunctuolata, Dotouva, Tyrinnaevelinae, Tyrinnadelicata, and Dorisfontainii), and two species are endemic to Peru (Corambemancorensis and Felimaresechurana). This study provides comprehensive information on biogeographical aspects, geographical distributions, and taxonomic updates within the nudibranch species documented in Peru. Furthermore, we discuss the status of species listed in previous literature that have not been confirmed by collections, referring to them as potentially occurring species.

Determinants of Copper Resistance in Acidithiobacillus Ferrivorans ACH Isolated from the Chilean Altiplano.

The use of microorganisms in mining processes is a technology widely employed around the world. Leaching bacteria are characterized by having resistance mechanisms for several metals found in their acidic environments, some of which have been partially described in the Acidithiobacillus genus (mainly on ferrooxidans species). However, the response to copper has not been studied in the psychrotolerant Acidithiobacillus ferrivorans strains. Therefore, we propose to elucidate the response mechanisms of A. ferrivorans ACH to high copper concentrations (0-800 mM), describing its genetic repertoire and transcriptional regulation. Our results show that A. ferrivorans ACH can grow in up to 400 mM of copper. Moreover, we found the presence of several copper-related makers, belonging to cop and cus systems, as well as rusticyanins and periplasmatic acop protein in the genome. Interestingly, the ACH strain is the only one in which we find three copies of copB and copZ genes. Moreover, transcriptional expression showed an up-regulation response (acop, copZ, cusA, rusA, and rusB) to high copper concentrations. Finally, our results support the important role of these genes in A. ferrivorans copper stress resistance, promoting the use of the ACH strain in industrial leaching under low temperatures, which could decrease the activation times of oxidation processes and the energy costs.

Aquatic Thermal Reservoirs of Microbial Life in a Remote and Extreme High Andean Hydrothermal System.

Hydrothermal systems are ideal to understand how microbial communities cope with challenging conditions. Lirima, our study site, is a polyextreme, high-altitude, hydrothermal ecosystem located in the Chilean Andean highlands. Herein, we analyze the benthic communities of three nearby springs in a gradient of temperature (42-72 °C represented by stations P42, P53, and P72) and pH, and we characterize their microbial diversity by using bacteria 16S rRNA (V4) gene metabarcoding and 16S rRNA gene clone libraries (bacteria and archaea). Bacterial clone libraries of P42 and P53 springs showed that the community composition was mainly represented by phototrophic bacteria (Chlorobia, 3%, Cyanobacteria 3%, at P42; Chlorobia 5%, and Chloroflexi 5% at P53), Firmicutes (32% at P42 and 43% at P53) and Gammaproteobacteria (13% at P42 and 29% at P53). Furthermore, bacterial communities that were analyzed by 16S rRNA gene metabarcoding were characterized by an overall predominance of Chloroflexi in springs with lower temperatures (33% at P42), followed by Firmicutes in hotter springs (50% at P72). The archaeal diversity of P42 and P53 were represented by taxa belonging to Crenarchaeota, Diapherotrites, Nanoarchaeota, Hadesarchaeota, Thaumarchaeota, and Euryarchaeota. The microbial diversity of the Lirima hydrothermal system is represented by groups from deep branches of the tree of life, suggesting this ecosystem as a reservoir of primitive life and a key system to study the processes that shaped the evolution of the biosphere.

Characterization and Salt Response in Recurrent Halotolerant Exiguobacterium sp. SH31 Isolated From Sediments of Salar de Huasco, Chilean Altiplano.

Poly-extremophiles microorganisms have the capacity to inhabit hostile environments and can survive several adverse conditions that include as variations in temperature, pH, and salinity, high levels UV light and atmospheric pressure, and even the presence of toxic compounds and the formation of reactive oxygen species (ROS). A halotolerant Exiguobacterium strain was isolated from Salar de Huasco (Chilean Altiplano), a well-known shallow lake area with variable salinity levels, little human intervention, and extreme environmental conditions, which makes it ideal for the study of resistant mechanisms and the evolution of adaptations. This bacterial genus has not been extensively studied, although its cosmopolitan location indicates that it has high levels of plasticity and adaptive capacity. However, to date, there are no studies regarding the tolerance and resistance to salinity and osmotic pressure. We set out to characterize the Exiguobacterium sp. SH31 strain and describe its phenotypical and genotypical response to osmotic stress. In this context, as a first step to characterize the response to the SH31 strain to salinity and to establish the bases for a molecular study, we proposed to compare its response under three salt conditions (0, 25, and 50 g/l NaCl). Using different physiology, genomic, and transcriptomic approaches, we determined that the bacterium is able to grow properly in a NaCl concentration of up to 50 g/l; however, the best growth rate was observed at 25 g/l. Although the presence of flagella is not affected by salinity, motility was diminished at 25 g/l NaCl and abolished at 50 g/l. Biofilm formation was induced proportionally with increases in salinity, which was expected. These phenotypic results correlated with the expression of related genes: fliG and fliS Motility); opuBA and putP (transport); glnA, proC, gltA, and gbsA (compatible solutes); ywqC, bdlA, luxS y pgaC (biofilm and stress response); and therefore, we conclude that this strain effectively modifies gene expression and physiology in a differential manner when faced with different concentrations of NaCl and these modifications aid survival.

Isolation and characterization of a novel Acidithiobacillus ferrivorans strain from the Chilean Altiplano: attachment and biofilm formation on pyrite at low temperature.

Microorganisms are used to aid the extraction of valuable metals from low-grade sulfide ores in mines worldwide, but relatively little is known about this process in cold environments. This study comprises a preliminary analysis of the bacterial diversity of the polyextremophilic acid River Aroma located in the Chilean Altiplano, and revealed that Betaproteobacteria was the most dominant bacterial group (Gallionella-like and Thiobacillus-like). Taxa characteristic of leaching environments, such Acidithiobacillus and Leptospirillum, were detected at low abundances. Also, bacteria not associated with extremely acidic, metal-rich environments were found. After enrichment in iron- and sulfur-oxidizing media, we isolated and identified a novel psychrotolerant Acidithiobacillus ferrivorans strain ACH. This strain can grow using ferrous iron, sulfur, thiosulfate, tetrathionate and pyrite, as energy sources. Optimal growth was observed in the presence of pyrite, where cultures reached a cell number of 6.5 · 10(7) cells mL(-1). Planktonic cells grown with pyrite showed the presence of extracellular polymeric substances (10 °C and 28 °C), and a high density of cells attached to pyrite grains were observed at 10 °C by electron microscopy. The attachment of cells to pyrite coupons and the presence of capsular polysaccharides were visualized by using epifluorescence microscopy, through nucleic acid and lectin staining with Syto(®)9 and TRITC-Con A, respectively. Interestingly, we observed high cell adhesion including the formation of microcolonies within 21 days of incubation at 4 °C, which was correlated with a clear induction of capsular polysaccharides production. Our data suggests that attachment to pyrite is not temperature-dependent in At. ferrivorans ACH. The results of this study highlight the potential of this novel psychrotolerant strain in oxidation and attachment to minerals under low-temperature conditions.

Endovenous laser and echo-guided foam ablation in great saphenous vein reflux: one-year follow-up results.

BACKGROUND: Great saphenous vein (GSV) reflux is the most frequent form of venous insufficiency in symptomatic patients and is commonly responsible for varicose veins of the lower extremity. This non-randomized prospective controlled study was designed to test the hypothesis that 1) endovenous laser treatment is more effective than foam sclerotherapy in the closure of the refluxing GSV (as measured by degree of great saphenous vein reflux and venous clinical severity score changes) and 2) to record the associated complications of echo-guided endovenous chemical ablation with foam and endovenous laser therapy for the treatment of great saphenous vein reflux and to further identify risk factors associated with treatment failure. METHODS: Between January 1, 2006 and June 25, 2006, patients seeking treatment of varicose veins at a private practice of vascular medicine were assessed for the study. Inclusion criteria were: 1) presence of great saphenous vein reflux and 2) C2-6, Epr, A s, according to the CEAP classification. The selected patients consented into the study and were allowed to choose between foam (53 patients) or laser (45 patients) treatment. Duplex examinations were performed prior to treatment and at seven and 14 days, four weeks, six months, and one year after treatment. Venous clinical severity score was assessed pre-treatment and at one year post-procedure. RESULTS: The cohorts showed no statistically significant differences in age, sex, clinical and anatomical presentation, great saphenous vein diameter, and venous clinical severity score before the treatments. After one year follow up, occlusion of the great saphenous vein was confirmed in 93.4% (42/45) of limbs studied in the laser group and 77.4% (41/53) of limbs in the foam group (P < .0465). Venous clinical severity score significantly improved in both groups (P < .0001). Procedure associated pain was higher in the laser group (P < .0082). Induration, phlebitis, and ecchymosis were the most common complications. Logistical regression and subgroups analysis shown that a larger great saphenous vein diameter measured before treatment was associated with treatment failure in the foam (odds ratio 1.68, 95% CI 1.24-2.27, P < .0008) and in the laser group (odds ratio 1.91, 95% CI 1.02-3.59, P < .0428). A 90% treatment success is predicted for veins <6.5 mm in the foam group versus veins <12 mm in the laser group. CONCLUSIONS: Overall, endovenous laser ablation achieved higher occlusion rates than echo-guided chemical ablation with foam after one year follow-up. Matching the patient to the technique based on great saphenous vein diameter measured before treatment may assist in boosting the treatment success rate to >90%. A larger patient cohort followed and compared over a longer period of time would be required to confirm these findings.