Plants In South America Research Articles

Heat in the news: Geothermal energy in Chilean newspaper coverage

Although Chile has abundant geothermal resources and is home to the first geothermal power plant in South America, the country faces uncertainties regarding the future development of geothermal energy. Lack of economic incentives, insufficient regulatory framework, and social opposition to geothermal power plant projects are some of the main challenges faced in the last years. To reflect on the pitfalls of the geothermal energy public debate and promote the integration of social aspects in the geothermal energy discussion, this study examines how geothermal energy has been portrayed in two influential Chilean newspapers from 2008 to 2021. Based on the idea that the mass media plays a critical role in public perception, this paper presents a framing analysis of 259 newspaper press to reflect on the public discourse of geothermal energy. The study shows that the media focused mainly on deep, high-enthalpy geothermal projects and the energy concession market. Geothermal energy has been mostly part of the finance discussion, and the coverage has been primarily event-driven, with limited visibility beyond specific events. Two events, the controversial exploration project in El Tatio (2009) and the successful commissioning of the first geothermal plant Cerro Pabellón (2017) attracted significant attention and presented geothermal energy from contrasting perspectives. Geothermal energy is mainly portrayed as an abundant, clean, and renewable energy source. However, geothermal development is described as a “business” or a “resource to be exploited”. There is a notable absence of discussion regarding the success of Latin American geothermal initiatives. Instead, European cases are the most prevalent in the discourse, serving as exemplars for potential future action. This result calls for the promotion of a new geothermal narrative and relationship with geothermal energy that acknowledges the experience from Latin American countries such as Costa Rica or El Salvador, the importance that geothermal energy has had for Indigenous peoples and promotes its use in the light of social demands for a more sustainable relationship with the environment, instead the main geothermal frame reproduces the commodification of natural resources in Chile.

Genetic Variability Among U.S.-Sentinel Cotton Plot Cotton Leafroll Dwarf Virus and Globally Available Reference Isolates Based on ORF0 Diversity.

The aphid-transmitted polerovirus, cotton leafroll dwarf virus (CLRDV), first characterized from symptomatic cotton plants in South America, has been identified in commercial cotton plantings in the United States. Here, the CLRDV intraspecific diversity was investigated by comparative sequence analysis of the most divergent CLRDV coding region, ORF0/P0. Bayesian analysis of ORF0 sequences for U.S. and reference populations resolved three well-supported sister clades comprising one U.S. and two South American lineages. Principal component analysis (PCA) identified seven statistically supported intraspecific populations. The Bayesian phylogeny and PCA dendrogram-inferred relationships were congruent. Population analysis of ORF0 sequences indicated most lineages have evolved under negative selection, albeit certain sites/isolates evolved under positive selection. Both U.S. and South American isolates exhibited extensive ORF0 diversity. At least two U.S. invasion foci were associated with their founder populations in Alabama-Georgia and eastern Texas. The Alabama-Georgia founder is implicated as the source of recent widespread expansion and establishment of secondary disease foci throughout the southeastern-central United States. Based on the geographically restricted distribution, spread of another extant Texas population appeared impeded by a population bottleneck. Extant CLRDV isolates represent several putative introductions potentially associated with catastrophic weather events dispersing viruliferous cotton aphids of unknown origin(s).

Natural occurrence of pelargonium flower break virus infecting Pelargonium zonale plants in South America

AbstractIn 2023, virus‐like symptoms were observed in Pelargonium zonale plants in Brazil. Transmission electron microscope analysis revealed the presence of isometric particles measuring ca. 30 nm in diameter in leaf extracts and ultrathin sections of symptomatic field plants. Molecular assays using PFBV‐specific primers and sequencing of amplicons identified the pelargonium flower break virus (PFBV, genus Alphacarmovirus). Mechanically inoculated plants of Chenopodium quinoa and P. zonale exhibited symptoms of chlorotic local lesions and systemic chlorotic spots, respectively. This is the first report of PFBV infecting P. zonale plants in South America (Brazil).

Documenting surface deformation at the first geothermal power plant in South America (Cerro Pabellón, Chile) by satellite InSAR time-series

In 2017, Cerro Pabellón in northern Chile became the first high-enthalpy geothermal power facility to go into service in South America. We evaluated Interferometric Synthetic Aperture Radar (InSAR) data containing 201 SAR scenes from the Sentinel-1A/B satellite mission between 2014 and 2021 to quantify the time-dependent surface deformation in the vicinity of the Cerro Pabellón geothermal plant. Using ascending and descending satellite orbits and the InSAR small baseline subset (SBAS) approach, we detected subsidence rates up to 6.3 mm/yr along the line of sight near the geothermal area, which began in 2017 and persisted through 2020 at which time the deformation rate decreased. We believe that geothermal activity may be responsible for the observed deformation based on the timing of the deformation – there was no detectable deformation in the area until the start of operations of the power plant. We invert the source of ground deformation using multiple analytic elastic half-space models (one or more spheroi ds or a sill-like source). The depth of the inferred sources is between 370 and 660 meters and is similar to the depth of the reservoir as determined by surface geophysics and well data. InSAR time series have not yet detected any tectonic deformation on the faults that encircle the graben where the geothermal plant is located, nor at the graben’s periphery. While the seismic records from a regional network near the geothermal field, analyzed between March 2017 and August 2020, show microseismicity in the graben near the power plant, accurate positions cannot be computed due to sparse and inadequate seismic data. Therefore, any possible correlation between the observed seismicity and the geothermal operations remains uncertain. This study emphasizes the need for an improved seismic network to obtain a better understanding of the geothermal-tectonic interplay.

Contrasting effects of climate change on the invasion risk and biocontrol potential of the invasive Iris pseudacorus L. between Northern and Southern Hemisphere

Iris pseudacorus is both a prized ornamental and an invasive aquatic plant that tends to grow dense monospecific stands, displacing the local vegetation and altering the hydrology of freshwater ecosystems. Originally from Europe, this species has historically invaded North America, China and Japan, and more recently spread through Argentina, South Africa and Australasia, where it is now a target for biological control. Field surveys within its native range have led to the selection of three candidate biocontrol agents. Prioritizing the best candidates for different regions constitutes a critical step, which could save significant time and resources before further cost-intensive experimental studies are conducted. Climate change is seldom taken into consideration in the prioritization process. In this regard, climatic suitability can be used to model the potential distributions of weeds and their candidate agents, both in space and time, thus allowing to identify areas at risk of invasion and predict where agents will be able to establish long-term. Accordingly, the objectives of this work were (i) to predict I. pseudacorus invasions and range shifts in the context of climate change; (ii) to identify wetland areas most at risk of invasion under present and future climatic conditions; and (iii) to prioritize the best suite of candidate biocontrol agents for different invaded ranges, worldwide. To do so, we modelled the present and future (2040–2060) climatic suitability of I. pseudacorus and its candidate agents using the software MaxEnt. Our results highlight a clear distinction between predictions for the Northern and Southern Hemispheres. In North America and eastern Asia, the area climatically suitable for I. pseudacorus is expected to increase and shift northwards. As for its biocontrol agents, very low suitability is predicted across these regions, further decreasing under future climatic conditions. On the other hand, climatically suitable areas for the plant in South America, southern Africa and Australasia are predicted, on average, to reduce in response to climate change. A decrease in climatic suitability is also expected for its candidate biocontrol agents which, however, would still maintain a significant range overlap with their host. These results can be used to prioritize areas most at risk of invasion and identify which combination of candidates could potentially provide the best level of control across different invaded ranges.

Comparison of the Immune Effects of an mRNA Vaccine and a Subunit Vaccine against Herpes Zoster Administered by Different Injection Methods.

Previous studies have shown that the herpes zoster subunit vaccine Shingrix™ performs well in clinical trials. However, the key ingredient in its adjuvant, QS21, is extracted from rare plants in South America, so vaccine production is limited. Compared with subunit vaccines, mRNA vaccines have the advantages of faster production and not requiring adjuvants, but currently, there is no authorized mRNA vaccine for herpes zoster. Therefore, this study focused on herpes zoster subunit and mRNA vaccines. We prepared a herpes zoster mRNA vaccine and compared the effects of vaccine type, immunization route, and adjuvant use on vaccine immunological efficacy. The mRNA vaccine was injected directly into mice via subcutaneous or intramuscular injection. The subunit vaccine was mixed with adjuvants before immunization. The adjuvants include B2Q or alum. B2Q is BW006S + 2395S + QS21. BW006S and 2395S are phosphodiester CpG oligodeoxynucleotides (CpG ODNs). Then, we compared the cell-mediated immunity (CIM) and humoral immunity levels of the different groups of mice. The results showed that the immune responses of mice inoculated with the mRNA vaccine prepared in this study were not significantly different from those of mice inoculated with the protein subunit vaccine supplemented with the B2Q. The mRNA vaccine-induced immune responses following subcutaneous or intramuscular injection, and the different immunization routes did not lead to significant differences in immune response intensity. Similar results were also observed for the protein subunit vaccine adjuvanted with B2Q but not alum. The above results suggest that our experiment can provide a reference for the preparation of mRNA vaccines against herpes zoster and has certain reference significance for the selection of the immunization route; that is, there is no significant difference in the immune response caused by subcutaneous versus an intramuscular injection, so the injection route can be determined according to the actual situation of individuals.

How studies on curare contributed to the development of neurophysiological research in Brazil

Curare is a poison obtained from different species of plants in South America, which was used in arrows by the natives. Its lethal paralyzing potential and mechanism of action began to be explored in the 19th century. In this article, we highlight the research on this poison and the fruitful exchanges between the Brazilian Emperor Dom Pedro II and the researchers João Baptista de Lacerda, Louis Couty and Alfred Vulpian who contributed to the development of experimental neurophysiology in Brazil. Vulpian found that curare does not affect the nerve itself, but acts between the nerves and the muscle, through a "ligand substance" - this Vulpian's pioneering concept is often wrongly attributed to Claude Bernard. These prestigious scientists contributed to the transnational circulation of knowledge that later yielded in the preparation of curare purified extract used for convulsive therapy and anesthesia.

Clay Minerals in the Deep Reservoir of the Cerro Pabellón Geothermal System (Northern Chile)

This study focuses on hydrothermal alteration, and more specifically clays, in the geothermal reservoir of Cerro Pabellón in Andean Cordillera, Northern Chile. Although it is the first commercial geothermal power plant in South America with 48 MWe installed and an additional 33 MWe during 2022, the alteration mineralogy of the deep reservoir remains poorly investigated. Cuttings from two deep wells drilled between 500 and 3000 m depth were sampled. The fine-grained clay fraction was analyzed using X-ray diffraction to observe the mineral distribution and variations of crystal structure of the clays. Scanning electron microscopy coupled with energy dispersive spectroscopy allowed us to perform microanalysis of the clays. The results suggest a high heterogeneity of the reservoir in term of alteration: a pervasive alteration dominated by trioctahedral clays was observed in all the samples, whereas a fracture-controlled alteration was only observed locally, dominated by dioctahedral clays. Illite-smectite mixed layers with more than 90% illite typically occur in permeable fracture and fault as a typical clay signature. This study completed an integrated conceptual model of the high enthalpy reservoir (>250 °C). Circulations of a neutral pH Na-K-Cl fluid occur in a wide fracture system connected to highly dipping and NW-striking faults and could extend beyond the Pabelloncito graben.

New record of an alien plant, Petrorhagia nanteuilii (Caryophyllaceae) in Korea

Petrorhagia nanteuilii (Burnat) P. W. Ball & Heywood (Caryophyllaceae), native to western Europe and western North Africa and an introduced or alien plant in South America, Australia, and Japan, was newly found in Gyeongsangnam-do, Korea. Petrorhagia is clearly distinguished from other genera by a bract at the base of calyx, which differs from Gypsophila L., and commissures at the sepals, which is different from Dianthus L. Petrorhagia nanteuilii grows on slopes and roadsides, suggesting that it is likely to have been introduced through the installation of green sites and road construction. A precise description, illustration, photographs, and a key to related genera and species is provided.

Boron requirement for vegetative growth of Sacha inchi (Plukentia volubilis L.)

Sachi inchi is a useful traditional plant in South America that has recently gained notoriety as a nutritional food crop and hence is being cultivated outside its native range. In Thailand, the crop is being grown on soils where boron (B) may be limiting to growth. To determine the response of early vegetative growth of sacha inchi to B supply, to identify B deficiency symptoms, and to define leaf B concentrations for optimum growth. The two experiments were conducted in sand-culture pot arranged in a randomized complete block design with three independent replications. Plants were grown in the preliminary experiment consisted of complete nutrient solution and complete nutrient solution without B. The main experiment was continued by growing plants in the five series of B rate (0, 2.5, 5.0, 7.5 and 10.0 µM B). Plant growth parameters were recorded and B concentration in different plant parts were analyzed. B deficiency strongly inhibited root and shoot development causing stunting and organ malformation. In a sand-culture experiment, maximum growth was obtained with 7.5 µM B and 10 µM B reduced growth. Leaf B concentration of 27–29 mg kg−1 was associated with 90% of maximum vegetative yield. Symptoms of B deficiency and the foliar B concentrations are useful for extension workers and producers looking to improve the productivity of sacha inchi on nutrient poor soils.

Complete chloroplast genome of Myracrodruon urundeuva and its phylogenetics relationships in Anacardiaceae family.

The online version contains supplementary material available at 10.1007/s12298-021-00989-1.

Peculiarities of tomatillo (Physalis philadelphica) field production in Ukraine with the use of different elements of technology

Tomatillo is a fairly common plant in South America but is rare for the conditions of the European continent. Therefore, in Ukraine there are no recommendations for its cultivation in specialized vegetable farms. Such recommendations should take into account the biological characteristics of the plant and the application of new elements of technology for plant productivity. The article is devoted to the study of the influence of the main elements of the technology of growing tomatillo for open ground conditions. The aim of the research was to find and optimize such elements in the open ground. To achieve this goal, the tasks solved were selection of high-yielding varieties, identification of the most effective factors for pre-sowing seed treatment and the term of planting seedlings is substantiated. This research was conducted during 2016 to 2018 on the research fields of Vinnytsia National Agrarian University (Central part of Ukraine) on gray-podzolic soils. The experimental varieties of tomatillo were divided into two groups (short and tall) according to plant height. Three varieties viz., Ananasovyi, Jemovyi and Kondyter were in the first group with a height of 80.1 to 81.4 cm and the second group included two varieties viz., Marmeladnyi and Korolyok. The varieties of foreign selection including Ananasovyi and Korolyok and, a domestic variety Likhtaryk were characterized by higher yields (30.6 to 32.0 t/ha). By studying the effect of pre-sowing seed treatment with heating the seeds at 40°C for 4 hrs or seed treatment with a magnetic field of 50 E for 12 hrs or Baikal EM-1 solution at a dose of 1.0 l/tonne provides an increase in total yield of tomatillo to 33.0 t/ha. When studying the impact of seedlings planting in the open ground, it was found that planting of seedlings was done in the third week of April or first week of May with a seedling age of 60 days under temporary film shelters. The varieties Likhtaryk and Ananasovyi were characterized by early budding in 47-48 days, flowering in 56-57 days, fruit tying in 69-70 days and fruiting in 101days. These varieties form a higher fruit yield of 33.4 t/ha. The biochemical composition determined a higher content of dry matter, protein and ash in the fruits of the variety Korolyok, with an index of 10.7, 1.6 and 1.0 %, respectively. These studies did not research the impact of tillage, pest control to obtain quality and environmentally friendly products and methods of harvesting, therefore, there is a need to further improve the technology of growing tomatillo in the open ground of Ukraine.

RNAi and CRISPR/Cas9 as Functional Genomics Tools in the Neotropical Stink Bug, Euschistus heros.

Simple SummaryUnderstanding the biology of insect pests is an important step towards developing appropriate control strategies. In this study, a CRISPR/Cas9 gene knockout work flow was established for the first time and was together with RNAi used as tools to study gene functions in the Neotropical stink bug, Euschistus heros. RNAi was first employed to study the function of three genes, abnormal wing disc (awd), tyrosine hydroxylase (th) and yellow (yel). Targeting awd and th resulted in distinct malformed phenotypes such as a deformed wing or a lighter cuticle pigmentation/defects in cuticle sclerotization, respectively. However, no distinct phenotype was observed for yel. To further investigate the function of yel, a CRISPR/Cas9 gene editing protocol was developed for E. heros. A total of 719 eggs were microinjected with single-guide (sgRNA) and Cas9 and total of six insects hatched. Out of these six nymphs, one insect showed mutation in yel but no clear phenotype was visible. Although, we were unable to generate insects with a distinct phenotype for yel, a successful gene editing workflow was established to complement RNAi for future functional gene studies in E. heros. Additionally, we provided recommendations to improve the established gene editing workflow.The Neotropical brown stink bug, Euschistus heros, is one of the most important stink bug pests in leguminous plants in South America. RNAi and CRISPR/Cas9 are important and useful tools in functional genomics, as well as in the future development of new integrated pest management strategies. Here, we explore the use of these technologies as complementing functional genomic tools in E. heros. Three genes, abnormal wing disc (awd), tyrosine hydroxylase (th) and yellow (yel), known to be involved in wing development (awd) and the melanin pathway (th and yel) in other insects, were chosen to be evaluated using RNAi and CRISPR/Cas9 as tools. First, the genes were functionally characterized using RNAi knockdown technology. The expected phenotype of either deformed wing or lighter cuticle pigmentation/defects in cuticle sclerotization was observed for awd and th, respectively. However, for yel, no obvious phenotype was observed. Based on this, yel was selected as a target for the development of a CRISPR/Cas9 workflow to study gene knockout in E. heros. A total of 719 eggs were injected with the Cas9 nuclease (300 ng/µL) together with the sgRNA (300 ng/µL) targeting yel. A total of six insects successfully hatched from the injected eggs and one of the insects showed mutation in the target region, however, the phenotype was still not obvious. Overall, this study for the first time provides a useful CRISPR/Cas9 gene editing methodology to complement RNAi for functional genomic studies in one of the most important and economically relevant stink bug species.

Abstract 3455: Preclinical evidences of antitumoral properties of a Yerba mate extract on breast and colon cancer models

Abstract Yerba Mate (Ilex Paraguariensis) belongs to the Aquifoliaceae family and is a native plant of South America. This plant are enriched in bioactive compounds with biological activities. This study investigated the antitumor activity of Yerba Mate extract (YM) using in vitro and in vivo colon and breast cancer models. YM was generated by aqueous extraction and standardized to total phenolics content, antioxidant activity and Chlorogenic acid content. The HPLC analysis of the YM allowed us to quantify the main polyphenols: Chlorogenic acid (66.3 ± 0.05 mg/g dry sample), Rutin (6.783 ± 0.05 mg/g dry sample), Gallic acid (6.665 ± 0.321 mg/g dry sample), Caffeic acid (0.533 ± 0.04 mg/g dry sample) and Quercetin (0.229 ± 0.02 mg/g dry sample). To investigate the antitumoral activity of YM, we first evaluated its effect on cell proliferation of colon (CT26 and COLO205) and breast (MDA-MB 231, MCF7, F3II and 4T1) cancer cell lines. YM reduced tumor cell viability and induced apoptosis. In addition, YM showed negative modulatory effect on cell adhesion and migration of tumor cells and reduced their invasiveness capacity. The use of herbal products requires previous toxicity studies to identify the dose ranges that are safe for subsequent studies. Acute toxicity was evaluated in rats and chronic toxicity test was conducted in rabbits. Animals exposed showed no statistical changes in weight gain. Clinical examination and macroscopic analysis did not show any changes that indicate toxicity. We found a YM LD50 value above 5000 mg/kg. The effect of YM on tumor progression was also studied in vivo using different syngeneic tumor models. Animals received YM by oral administration in a dose of 1.6 g/kg/day before and after tumor cell inoculation. Orthotopic and heterotopic breast cancer models in BALB/c mice was performed. In the heterotopic F3II model the treatment with YM significantly reduced tumor volumes when compared with control group. In addition, the consumption of YM significantly increased the survival of animals in both models. We also studied the inhibition of spontaneous metastatic activity by YM. Diet with YM resulted in a reduced number of lung metastases compared to control in both models. On the other hand, in the heterothopic colorectal cancer model we observed that oral administration of YM reduced angiogenesis, delayed tumor onset and showed a reduction of tumor volume. The effects of the combination of YM extract with 5-fluorouracil (5-FU) was also evaluated in mice. The results suggest that this combination increased susceptibility of the colon cancer cells to the cytotoxicity of 5-Fu. In conclusion, our findings suggest that YM may be a promising agent for the treatment of breast and colon cancer in chemoprevention schemes or in combinatory schedules with standard-of-care therapeutics. Citation Format: Rocío S. García Lázaro, Humberto Lamdan, Norailys Lorenzo Perez, Lorena G. Caligiuri, Andrea L. Berengeno, Hugo H. Ortega, Daniel F. Alonso, Hernan G. Farina. Preclinical evidences of antitumoral properties of a Yerba mate extract on breast and colon cancer models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3455.

Nanomineralogy of evaporative precipitation of efflorescent compounds from coal mine drainage

Efflorescent nanophases (NPs) are found as a transitory accumulation of potentially hazardous elements (PHEs), particularly in tropical climates. The central objective of this study was to investigate the distribution of PHEs with NPs through the evaporative formation structures (EFS) of enormously PHEs-rich coal-mine drainages (CMD). The EFS were studied in natural coal mine drainage for five months in order to determine their geochemical and ecological structures and to assess their position in the reduction of PHEs in nature. The largest coal-fired power plant in South America, located in south Brazil, is used as an example of such a problem. In this work, a novel methodology for the analysis of PHEs in CMD precipitates is proposed for this affected coal area. The analytical method, combining X-Ray Diffraction (XRD) and advanced electron microscopies, shows the importance of nanomineralogy in understanding different circumstances of coal contamination. Several ultrafine-nanoparticles (UNPs) were identified in the sampled soils and river sediments together with the PHEs. A decrease in PHEs was identified in association with UNPs. However, further investigations are required with regard to the mobility of PHEs in water, atmosphere, soils, and sediments. The EPS was thoroughly studied, acquiring suitable understanding with investigational facts for Ca and Fe-sulphates, pickeringite, and several amorphous phases.

A tool for realistic study of nanoparticulate coal rejects

Pollution caused by hazardous and carcinogenic inorganic elements and organic compounds from coal may be more severe when coupled by other sources of pollution. In addition, the modes of occurrence of potential hazardous elements (PHEs) in coal cleaning rejects (CCRs) have been widely investigated using different methods, including statistical methods, which, however, in some cases resulted in misleading interpretations. In order to verify this potential problem and find an effective solution, we selected a data set, which contained comprehensive analyses of CCRs. The secondary products in sulphides-bearing coal mine rejects were studied in demand to determine their geochemical and ecological structures and to assess their position in the reduction of PHEs in the nature. A zone located in south Brazil, which is the major coal power plant in South America, can be given as an example of such a problem. In this work, a novel methodology for the analysis of PHEs in soils and sediments is proposed for this affected coal area. The analytical method combining X-Ray Diffraction (XRD) and advanced electron microscopies shows the importance of nanomineralogy in understanding different circumstances of coal contamination. Several ultrafine-nanoparticles (UNPs) were identified in the sampled soils and river sediments together with the PHEs. A decrease in PHEs was identified in association with UNPs. However, still further investigations are required with regard to the mobility of PHEs in water, atmosphere, soils, and sediments. The site studied around the coal power plant showed the highest sorption capacity possibly due to the high retention ability of components of soil and sediments such as carbon and clay. These observations of the coal-derived nanoparticles confirm their capability of regulating the mobility of hazardous elements, implying the need for restoring complex abandoned coal areas.

Root-Associated Fungal Communities in Two Populations of the Fully Mycoheterotrophic Plant Arachnitis uniflora Phil. (Corsiaceae) in Southern Chile.

The microbiological interactions of the roots of non-photosynthetic plants in South America have been scarcely explored. This study analyzes culturable fungal diversity associated with the mycoheterotrophic plant Arachnitis uniflora Phil. (Corsiaceae) in southern Chile, growing in two different understoreys of native (Nothofagus-dominated) and mixed forest (native, Cupressus sempervirens, and Pinus radiata). Rhizospheric and endophytic fungi were isolated, cultured, and purified to identify microorganisms associated with A. uniflora roots. We showed the different fungi associated with the plant, and that these distributions are influenced by the sampling site. We isolated 410 fungal strains (144 endophytic and 266 from the rhizosphere). We identified 13 operative taxonomical units from plants sampled in the mixed forest, while 15 were from the native forest. Rhizospheric microorganisms were mainly related to Penicillium spp., whereas some pathogenic and saprophytic strains were more frequent inside the roots. Our results have also shown that the fungal strains are weak for phosphate solubilization, but other pathways such as organic acid exudation and indole acetic acid production can be considered as major mechanisms to stimulate plant growth. Our results point to new fungal associates of A. uniflora plants reported in Andean ecosystems, identifying new beneficial endophytic fungi associated with roots of this fully mycoheterotrophic plant.

Environmental impacts of a reduced flow stretch on hydropower plants.

In Brazil, given its privileged hydrology, the unexplored economic use of water resources has many dimensions, such as hydroelectric power. This energy will face increasingly rigorous social and environmental impact assessments (40% of potential is located in the Amazon region). Hydropower inventory studies conducted over decades, with solutions such as ecological river flows, that flood smaller areas and reduce natural river flows modifications, are being reviewed. The river extension from dam to the point where the waters are returned after the powerhouse is known as the Reduced Flow Stretch (RFS). Even mega-projects, such as the 11.3 GW Belo Monte dam, are designed with deviating flows reaching an astounding 13,000 m 3/s (excavated material higher than Panama Canal). RFS requires to be carefully studied to achieve appropriate ecological flows, since RFS flows increased reduces the plant's electricity production to the same installed capacity. Balancing RFS requirements and hydroelectric power remains a challenge and, clearly, there is no consensus. Here, we performed an analysis of the main environmental impacts caused by RFS requirements, considering the multiple water use specific for each dam site. The natural variability of river flows provides diversity of habitats and maintains the richness and complexity of biological communities. Therefore, the present study has great ecological, social and economic relevance, since proper evaluation of the RFS requirements avoids potential destabilization of biological communities and even loss of biodiversity. This type of arrangement was more common in dams located in headwaters of rivers, as in the slopes of the Andes mountain range, and in regions like the Alps. There are many hydroelectric plants in South America and Europe that have this type of arrangement of engineering works. But the times are different and the environmental impacts have to be better evaluated. A final aspect also involves the maintenance of ecological flows downstream of dams. Regularization reservoirs need to keep downstream, even if they do not have a TVR, adequate flows that represent minimally the seasonality of the river, with floods and droughts, that propitiate the maintenance of the ecosystems downstream. There are cases such as the Sobradinho Plant in the São Francisco River that has been much questioned in this regard, especially when the climate is changing in the basin, with long periods of drought, and with increasing water use. So this is a very important and increasingly current issue.

Sealing capacity of clay-cap units above the Cerro Pabellón hidden geothermal system (northern Chile) derived by soil CO2 flux and temperature measurements

Cerro Pabellón is a hidden high-enthalpy geothermal system (reservoir temperature up to 250°C) located in the Pampa Apacheta (northern Chile), where the first geothermal power plant in South America is currently operating. A fumarolic field, located on the summit of Apacheta Volcano, about 3.5kmW of Pampa Apacheta, is the only evidence of the presence of a degassing magma connected to the surface. CO2 soil flux and temperatures, on a grid of ~430 points, were measured to understand the absence of any other thermal manifestations. More than 90% of the measured CO2 flux values were below background, estimated at 1.35g·m−2·day−1 whereas the associated soil temperatures (mean value=19.4°C) carried out at ~10cm depth were related, at least partially, to an endogenous, though weak, thermal anomaly. No spatial correlation was observed between soil CO2 flux and temperature measurements, suggesting a minimal role played by the volcano-tectonic structures in the circulation of geothermal fluids. Soil temperature gradients measured on a grid of 85 points in the active fumarolic field (where acid waters and magmatic gases are discharged) revealed the only strong thermal anomaly (temperatures up to ~83°C) of the area. The thick argillic clay-cap (~300m) located above the geothermal reservoir, has a pivotal role in preventing the resurgence of fluids, whereas an efficient interaction between the rising magmatic fluids and the liquid-dominated reservoir favours acidic gas scrubbing processes, thus allowing the ascent of a steam depleted in magmatic compounds. This steam interacts with the shallower, discontinuous aquifer(s) below Pampa Apacheta, with the consequent nearly complete dissolution of CO2 and H2S, and heating of the shallow groundwater. This results in low CO2 fluxes and extended slight thermal anomaly at the surface. Finally, an integrated conceptual model using our results and available geological, mineralogical, geochemical and geophysical data of the Cerro Pabellón hidden geothermal system is presented, with the aim of providing criteria for geothermal exploration of similar high-enthalpy geothermal systems in the Andes that also exhibit a lack of thermal surface features.

Target guided isolation of potential tyrosinase inhibitors from Otholobium pubescens (Poir.) J.W. Grimes by ultrafiltration, high-speed countercurrent chromatography and preparative HPLC

Otholobium pubescens (Poir.) J.W. Grimes (O. pubescens) is a commercial and multiple therapeutic medicinal plant in South America, yet its phytochemicals are rarely studied. In the present study, a combination of affinity-based ultrafiltration, HSCCC, and preparative HPLC was applied for the efficient screening and isolation of ten tyrosinase inhibitors from the O. pubescens methanol extract and eight of them were successfully identified as daidzin, isoorientin, vitexin, isovitexin, isoorientin 3′-methyl ether, daidzein, genistein, and a novel compound 3-(5-hydroxybenzofuran-6-yl) propanoic acid by EI-MS and NMR; all of these compounds are first reported in O. pubescens and possessed tyrosinase inhibitory activities by in vitro tyrosinase inhibition assay. Among the inhibitors, vitexin, isovitexin, 3-(5-hydroxybenzofuran-6-yl) propanoic acid, and daidzein revealed higher tyrosinase inhibitory activities than the positive control β-arbutin, with IC50 values of 0.35 mM, 1.73 mM, 1.33 mM, 1.57 mM, and 1.83 mM, respectively. Moreover, a long time tyrosinase inhibition duration, up to 150 min, was observed for compounds vitexin, daidzein, and particularly 3-(5-hydroxybenzofuran-6-yl) propanoic acid, which was assessed as a special mixed-type tyrosinase inhibitor because of its capability of inhibiting tyrosinase almost in an irreversible inhibition manner, through tyrosinase inhibition duration, inhibition kinetics, and dialysis studies. In addition, the major nonpolar compound from O. pubescens methanol extract was also purified by silica gel column chromatography and identified as bakuchiol. Results suggested that vitexin, isovitexin, daidzein, and particularly the novel compound 3-(5-hydroxybenzofuran-6-yl) propanoic acid are promising tyrosinase inhibitors with the potential for pharmaceutical, cosmetic, and food industrial applications.