Publicaciones

Antarctic Extremophiles: Biotechnological Alternative to Crop Productivity in Saline Soils

Acuña-Rodríguez, I., Hansen, H., Gallardo-Cerda, J., Atala, C., & Molina-Montenegro, M.

Salinization of soils is one of the main sources of soil degradation worldwide, particularly in arid and semiarid ecosystems. High salinity results in osmotic stress and it can negatively impact plant grow and survival. Some plant species, however, can tolerate salinity by accumulating osmolytes like proline and maintaining low Na+ concentrations inside the cells. Another mechanism of saline stress tolerance is the association with symbiotic microorganism, an alternative that can be used as a biotechnological tool in susceptible crops. From the immense diversity of plant symbionts, those found in extreme environments such as Antarctica seems to be the ones with most potential since they (and their host) evolved in harsh and stressful conditions. We evaluated the effect of the inoculation with a consortium of plant growth-promoting rhizobacteria (PGPB) and endosymbiotic fungi isolated from an Antarctic plant on saline stress tolerance in different crops. To test this we established 4 treatments: (i) uninoculated plants with no saline stress, (ii) uninoculated plants subjected to saline stress (200 mM NaCl), (iii) plants inoculated with the microorganism consortium with no saline stress, and (iv) inoculated plants subjected to saline stress. First, we assessed the effect of symbiont consortium on survival of four different crops (cayenne, lettuce, onion, and tomato) in order to obtain a more generalized response of this biological interaction. Second, in order to deeply the mechanisms involved in salt tolerance, in lettuce plants we measured the ecophysiological performance (Fv/Fm) and lipid peroxidation to estimate the impact of saline stress on plants. We also measured proline accumulation and NHX1 antiporter gene expression (involved in Na+ detoxification) to search for possible mechanism of stress tolerance. Additionally, root, shoot, and total biomass was also obtained as an indicator of productivity. Overall, plants inoculated with microorganisms from Antarctica increased the fitness related traits in several crops. In fact, three of four crops selected to assess the general response increased its survival under salt conditions compared with those uninoculated plants. On the other hand, saline stress negatively impacted all measured trait, but inoculated plants were significantly less affected. In control osmotic conditions, there were no differences in proline accumulation and lipid peroxidation between inoculation treatments. Interestingly, even in control salinity, Fv/Fm was higher in inoculated plants after 30 and 60 days. Under osmotic stress, Fv/Fm, proline accumulation and NHX1 expression was significantly higher and lipid peroxidation lower in inoculated plants compared to uninoculated individuals. Moreover, inoculated plants exposed to saline stress had a similar final biomass (whole plant) compared to individuals under no stress. We conclude that Antarctic extremophiles can effectively reduce the physiological impact of saline stress in a salt-susceptible crops and also highlight extreme environments such as Antarctica as a key source of microorganism with high biotechnological potential.

Año: 2019

Palabras claves: Extremophiles, Antarctica, functional symbiosis, crops, food security, salt tolerance

Aves marinas varadas en la bahía de Coquimbo, norte de Chile: ¿Qué especies y cuántas mueren?

Portflitt Toro, M., Miranda Urbina, D., & Luna Jorquera, G.

El monitoreo de las aves varadas en las playas puede proporcionar información sobre sus causas de muerte, tales como la captura incidental en actividades de pesca o derrames de petróleo. Durante un año fue monitoreada mensualmente la Bahía de Coquimbo, norte de Chile para cuantificar el número de aves marinas varadas. Se encontraron 395 aves marinas muertas de las cuales 382 fueron identificadas y agrupadas en 21 especies. Las especies más abundantes fueron los piqueros con 115 individuos (30%), el cormorán guanay con 83 individuos (22%) y la gaviota dominicana con 65 individuos (17%). Las especies más abundantes y frecuentes fueron las que anidan en el Sistema Costero de Coquimbo. La mortalidad afecta principalmente a las aves marinas que se alimentan de la anchoveta, que es el principal recurso objetivo de la pesca con redes de cerco. Se sugiere que la mortalidad incidental causada por la pesca es crónica y relativamente constante durante el año. Se requiere un programa de monitoreo a largo plazo para mejorar la estimación de la mortalidad y los factores que influyen en la interacción de las aves marinas con las artes de pesca.

Monitoring of seabirds stranded on beaches can provide information about their causes of death, such as bycatch in fishing activities or oil spills. During a year we monthly monitored the Coquimbo Bay, north Chile, to quantify the number of seabirds and species stranded. We found 395 dead seabirds, of which 382 were identified and grouped into 21 species. The most abundant were the Peruvian booby with 115 individuals (30%), the Guanay cormorant with 83 individuals (22%) and the Kelp gull with 65 individuals (17%). The most abundant and frequent species were those nesting in the Coastal System of Coquimbo. Mortality mainly affected seabirds that feed on anchoveta, which is the main target resource of purse seine fishing. We suggest that the incidental mortality caused by fishing is chronic and relatively constant during the year. A long-term monitoring program is needed to better estimate the mortality and the factors that influence the interaction of seabirds with fishing gears.

Año: 2018

Palabras claves: Strandings; seabirds; Suliformes; Coastal System of Coquimbo; Chile

Struggling with social-ecological mismatches in marine management and conservation at Easter Island

Aburto, J., & Gaymer, C.

In Easter Island, most of fisheries regulations are top-down implemented by the central fisheries authority located ~4000 km eastwards. This could generate problems in regulations compliance, given the cultural differences between the western worldview and Polynesian culture of Easter Island. A total of 18 issues that must be considered previously to an intervention in the island were identified. Four of them scored the highest difference between Rapanui and public services representatives. Among them, “Integrating traditions and culture” had a little priority for the public services representatives, but was the most important for the Rapanui. According to the public services representatives in Easter Island and local fishermen, there is a little compliance with regulations related to fisheries and, due to cultural aspects, it is not possible to enforce regulations and apply sanctions. The low compliance with fisheries regulations is due to the lack of representativeness of regulations. Interventions in the island are based on western worldview that does not fit with social and ecological domains of social-ecological system. A flexible governance system, based on decision making at local level in line with local tradition is needed to navigate to a resource management and conservation in Easter Island.

Año: 2018

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Effect of high hydrostatic pressure treatment on physical parameters, ultrastructure and shelf life of pre- and post-rigor mortis palm ruff (Seriolella violacea) under chilled storage

Roco, T., Torres, M., Briones-Labarca, V., Reyes, J., Tabilo-Munizaga, G., & Stucken, K., Lemus-Mondaca, R., Pérez-Won, M.

To identify processing conditions that better maintain palm ruff quality attributes, high hydrostatic pressure (HHP) was applied to pre- and post-rigor fillets. Physical parameters as whiteness index (WI), water holding capacity (WHC), texture and ultrastructure and shelf life were evaluated after the application of 450 and 550 MPa (3 and 4 min) and during cold storage. Pre-rigor fillets retained less water and were softer than post-rigor, although the onset of rigor increased palm ruff's WHC and firmness. Application of HHP whitened palm ruff's dark flesh; however, this effect reverted at the end of the storage. Pressurized post-rigor samples retained less water than the control and storage caused a WHC increase in samples pressurized at 550 MPa, independent on the rigor condition. Post-rigor fillets softened at pressures of 450–550 MPa appearing to have a lower threshold than beef or cod (above 600 MPa). Ultrastructural changes revealed a subtle contraction (7.4%) of the myofibrils in the unpressurized post-rigor muscle compared to pre-rigor; after 26 days' storage both samples presented extensive muscle degradation and sarcomere length was reduced in 30%. HHP induced pressure-dependent shortening of the sarcomere and modifications to the structure which after 550 MPa was hardly recognizable. After 26 days' storage, there was only slight degradation of the ultrastructure, showing that beyond the structural modifications caused by HHP, post-mortem deterioration is delayed in HHP-treated fillets. Furthermore, HHP extended palm ruff's shelf life to 14–23 days. Thus, HHP may be considered as a technology that maintains the textural quality and shelf life of fresh and stored fish.

Año: 2018

Palabras claves: Palm ruff, Rigor mortis, High hydrostatic pressure, Shelf life, StorageTexture, Ultrastructure

Optimization of extraction yield, flavonoids and lycopene from tomato pulp by high hydrostatic pressure-assisted extraction

Briones-Labarca, V., Giovagnoli-Vicuña, C., & Cañas-Sarazúa, R.

Tomato pulp is a useful source of antioxidants, which can be extracted by high hydrostatic pressure (HHPE). This study aimed to optimize the individual and interactive effect of operating high pressure and solvent polarity (solvent mixture) on yield extraction, flavonoid and lycopene content from tomato pulp (Solanum lycopersicum) by using response surface methodology (RSM). The results showed that the selected factors (high pressure and solvent mixture) have a significant influence on extraction yield, flavonoid and lycopene content. Extraction at 450 MPa and 60% hexane concentration in the solvent mixture was considered the optimal HHPE condition since it provided the maximum extraction yield (8.71%), flavonoid (21.52 ± 0.09 mg QE/g FW) and lycopene content (2.01 ± 0.09 mg QE/100 g FW). Therefore, HHPE could be a useful tool improve the extraction and release of potentially health-related compounds while providing information on the cumulative effect of solvent polarity and high-pressure extraction on antioxidant compounds of fruits.

Año: 2018

Palabras claves: Tomato, High hydrostatic pressure, Antioxidant capacity, Response surface methodology

Partitioning genetic and species diversity refines our understanding of species–genetic diversity relationships

Pfeiffer, V., Ford, B., Housset, J., McCombs, A., Blanco‐Pastor, J., & Gouin, N., Manel, S., Bertin, A

Disentangling the origin of species–genetic diversity correlations (SGDCs) is a challenging task that provides insight into the way that neutral and adaptive processes influence diversity at multiple levels. Genetic and species diversity are comprised by components that respond differently to the same ecological processes. Thus, it can be useful to partition species and genetic diversity into their different components to infer the mechanisms behind SGDCs. In this study, we applied such an approach using a high‐elevation Andean wetland system, where previous evidence identified neutral processes as major determinants of the strong and positive covariation between plant species richness and AFLP genetic diversity of the common sedge Carex gayana. To tease apart putative neutral and non‐neutral genetic variation of C. gayana, we identified loci putatively under selection from a dataset of 1,709 SNPs produced using restriction site‐associated DNA sequencing (RAD‐seq). Significant and positive relationships between local estimates of genetic and species diversities (α‐SGDCs) were only found with the putatively neutral loci datasets and with species richness, confirming that neutral processes were primarily driving the correlations and that the involved processes differentially influenced local species diversity components (i.e., richness and evenness). In contrast, SGDCs based on genetic and community dissimilarities (β‐SGDCs) were only significant with the putative non‐neutral datasets. This suggests that selective processes influencing C. gayana genetic diversity were involved in the detected correlations. Together, our results demonstrate that analyzing distinct components of genetic and species diversity simultaneously is useful to determine the mechanisms behind species–genetic diversity relationships.

Año: 2018

Palabras claves: Genetic outlier, high Andean wetlands, SNP, species–genetic diversity correlation

Assessment of oxytetracycline baths as therapeutic treatment for the control of the agent of withering syndrome (WS) in red abalone (Haliotis rufescens)

Winkler, F., García, R., Valdivia, M., & Lohrmann, K.

Withering Syndrome (WS) is a lethal disease that affects abalone species in both wild and farmed populations. This infection, caused by the rickettsial-like intracellular organism (RLO) Candidatus Xenohaliotis californiensis, can severely impair the normal development of affected animals, and ultimately, their survival. The most common line of action against the WS has been the use of antibiotics, specifically oxytetracycline (OTC), administered via intramuscular injection and per os via medicated feed. In the present study, we have assessed the effectiveness of OTC baths as therapeutic treatment for the control of the WS agent in H. rufescens. Clinical signs of infection were monitored for 11 months in treated juveniles, in addition to feed consumption rate, growth patterns and gonad development. Abalones were asymptomatic until the end of the experiment, when a small number of non-treated animals exhibited clinical signs of infection. Gonad maturity was not observed. OTC treated animals grew significantly less than their non-treated counterparts, being 4.3% shorter and 13.6% lighter at the end of the experiment. They also displayed negative allometry, i.e. for the same shell length, they were lighter than non-treated groups. Furthermore, the weight of muscle and soft tissues in OTC treated animals was lighter than in the other groups, while no differences were found in shell weight. The feed consumption rate was the same for all groups, thus the observed growth patterns cannot be attributed to a decreased feed intake. One possible explanation is that antibiotic treatment may have impacted gut microflora, thus preventing efficient nutrient digestion and absorption and, indirectly, reducing growth. Prevalence of RLOs causing WS (WS-RLO) and the variant form (RLOv), infected with a bacteriophague and non virulent, were significantly lower in the OTC-treated group than in the other groups. Similar results were observed for the mean intensity of RLOv, while for WS-RLO, the intensity in the OTC-treated group was higher, although not statistically significant, than the rest of the groups. These observations may be the consequence of an increased bacterial sensitivity to OTC effects associated with the phage infection or faster reproduction of WS-RLOs than RLOv after OTC treatment. Our results let us infer that the prophylactic use of OTC in abalone to avoid the negative effects of WS on abalone farms could have an undesired negative effect on the biological control exerted by the phage on the bacteria after OTC treatment.

Año: 2018

Palabras claves: Withering syndrome, Rickettsial-like organism, Hyperparasitic phage, Antibiotic, Growth, RLO

Heritability, genetic correlations and genotype-environment interactions for growth and survival of larvae and post-larvae of the Caribbean scallop, Argopecten nucleus (Mollusca: Bivalvia)

Barros, J., Winkler, F., & Velasco, L.

The Caribbean scallop Argopecten nucleus is a species with a great potential for commercial aquaculture in the Caribbean given its fast growth and the availability of culture technology. However, its production relies completely on hatchery-reared seed, and the survival in early stages, particularly during the settling process, is the main limitation for this activity to become cost effective. Thus, in order to assess the feasibility of improving survival of larvae and post-larvae of A. nucleus through genetic selection without affecting growth, it was estimated the heritability and the genotype-environment interactions for such traits, as well as the genetic correlations between them. These parameters were estimated based on intraclass correlations of 40 full-sib families (10 half-sib families) at 1, 11 and 75 days post fertilization. Heritability values were very high for the post-larvae survival (0.49), while it was low and not significant for larvae survival (≤0.07) and medium to high for growth traits of larvae and post-larvae (>0.3). The traits analyzed in post-larvae exhibited significant genotype-environment interactions in relation to culture depth in the sea. No significant genetic correlations between the measured traits were found. The results suggest the existence of an important genetic component in the variation of post-larval survival, and larval and post-larval growth, as well as a high potential response to direct genetic selection, especially for post-larval survival (50% increase per generation), without affecting the growth traits.

Año: 2018

Palabras claves: Shell length, Shell height, Post-larvae recovery, Genetic improvement, Selective breeding, Genetic gain, Pectinid

Landscape connectivity among remnant populations of guanaco (Lama guanicoe Müller, 1776) in an arid region of Chile impacted by global change

Espinosa, M., Gouin, N., Squeo, F., López, D., & Bertin, A.

Connectivity between populations plays a key role in the long-term persistence of species in fragmented habitats. This is of particular concern for biodiversity preservation in drylands, since water limited landscapes are typically characterized by little suitable habitat cover, high habitat fragmentation, harsh matrices, and are being rapidly degraded at a global scale. In this study, we modelled landscape connectivity between 11 guanaco Lama guanicoe populations in Chile’s arid Norte Chico, a region that supports the last remnant coastal populations of this emblematic herbivore indigenous to South America. We produced a habitat suitability model to derive a regional surface resistance map, and used circuit theory to map functional connectivity, investigate the relative isolation between populations, and identify those that contribute most to the patch connectivity network. Predicted suitable habitat for L. guanicoe represented about 25% of the study region (i.e., 29,173 km2) and was heterogeneously distributed along a continuous stretch along the Andes, and discontinuous patches along the coast. As a result, we found that high connectivity current flows in the mid and high Andes formed a wide, continuous connectivity corridor, enabling connectivity between all high Andean populations. Coastal populations, in contrast, were more isolated. These groups demonstrate no inter-population connectivity between themselves, only with higher altitude populations, and for two of them, animal movement was linked to the effectiveness of wildlife crossings along the Pan-American highway. Our results indicate that functional connectivity is an issue of concern for L. guanicoe in Chile’s Norte Chico, implying that future conservation and management plans should emphasize strategies aimed at conserving functional connectivity between coastal and Andean populations, as well as the protection of habitat patches likely to act as stepping stones within the connectivity network.

Año: 2018

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