Publicaciones

Modelling the Water Sorption Isotherms of Quinoa Seeds (Chenopodium quinoa Willd.) and Determination of Sorption Heats.

Miranda, M., Vega-Gálvez, A., Sanders, M., López, J., Lemus-Mondaca, R., Martínez, E., & Di Scala, K.

Adsorption and desorption isotherms of quinoa seeds (Chenopodium quinoa Willd.) were measured using the static gravimetric method at three temperatures (20, 40 and 60 °C). Water activity ranged from 0.118 to 0.937. The moisture sorption behaviour of quinoa was temperature dependent, as indicated by a decrease in equilibrium moisture content, at all levels of aw, with increasing temperature. Eight mathematical equations available in the literature were used to model the experimental data, namely, GAB, BET, Caurie, Henderson, Oswin, Halsey, Smith and Iglesias–Chirife. All the equations showed generally a good fit; however, the Iglesias–Chirife and Oswin equations were considered the best to predict the experimental data for both isotherms. Effect of temperature on model parameters was analysed and studied through an Arrhenius-type equation. The net isosteric heats of desorption and adsorption were determined by applying the Clausius–Clapeyron equation resulting in 69.24 kJ mol−1 for desorption and 61.26 kJ mol−1 for adsorption. The experimental heat data were satisfactorily modelled by Tsami’s equation.

Año: 2012

Palabras claves: Quinoa, Sorption isotherms, Isosteric sorption heat, Mathematical modelling.

Genetic signatures of rafting dispersal in algal-dwelling brooders Limnoria spp. (Isopoda) along the SE Pacific (Chile).

Haye, P., Varela, A., & Thiel, M.

ABSTRACT: Brooding marine isopods of the genus Limnoria inhabit and feed on kelp holdfasts and wood. These substrata have high floating potential, making these species ideal organisms to study the effects of rafting-mediated connectivity on the population structure of brooders living on rafting substrata. It is hypothesized that rafting leaves particular genetic signatures such as low differentiation among distant local populations and absence of isolation by distance (IBD) at a macro-geographic scale (thousands of km). Using cytochrome oxidase I (COI) sequences, we tested the effects of rafting-mediated gene flow with respect to genetic differentiation on L. quadripunctata (from wood and also the holdfasts of the giant kelp Macrocystis pyrifera) and L. chilensis (mainly from the bull kelp Durvillaea antarctica) sampled across 2400 km of the Chilean coast. Analyses of COI data for both species indicated low differentiation between distant locations along the Chilean coast and lack of IBD, bearing the expected genetic signatures of rafting dispersal. Phylogenetic analyses were performed with COI and the nuclear gene 28S to place the genetic diversity of Chilean Limnoria spp. into a wider geographical context. Both markers revealed that L. quadripunctata from Chile is a sister clade to other Limnoria spp. analyzed (L. chilensis, L. segnis, and L. stephenseni), which mainly inhabit D. antarctica. L. chilensis from Chile and subantarctic islands form a tight monophyletic group. Phylogenetic and phylogeographic analyses show that along the studied area, L. quadripunctata and L. chilensis have the genetic signatures of relatively recent or ongoing rafting.

Año: 2012

Palabras claves: Peracarids, Rafting, Biogeography, Mitochondrial DNA, COI, 28S, Phylogeny, Phylogeography

Authentication of commercialized crab-meat in Chile using DNA Barcoding.

Haye, P., Segovia, N., Vera, R., Gallardo, M., & Gallardo-Escárate, C.

Authentication of commercialized marine products has become a market priority. Crustaceans are benthic marine resources highly exploited in Chile. Brachyuran crabs are of particular interest and in Chile are commercialized with different processing and presentations. Generally, Chilean brachyuran crab-meat commercial packages do not include taxonomic information, which in addition to the loss of diagnostic characters during the processing, impedes the identification of species being commercialized. The goal of this study was to determine which brachyuran species are being commercialized in the Chilean market using DNA Barcoding and phylogenetic analysis. For authentication of commercial crab-meat and DNA Barcoding a partial sequence of the Cytochrome Oxidase I (COI) gene of seven commercialized brachyuran species in Chile were used. For authentication, samples were obtained from seven commercial formats available on the local market in Coquimbo, Chile. Most commercial packages contained more than one species of crab. The Species detected in order of frequency are Metacarcinus edwardsii, Romaleon polyodon, Cancer porteri, Cancer plebejus, and Homalaspis plana. Mislabeling was detected in one of the commercial formats that declared including meat from Cancer species. The procedure presented herein, based on standard DNA Barcoding as well as phylogenetic analyses, can be used for the normative control of crab-meat processed products.

Año: 2012

Palabras claves: Food authentication; DNA Barcoding; Crab meat; Species identification; Mislabeling; Conservation genetics

Effect of two temperatures on ammonia excretion rates of Seriolella violacea (Palm fish) juveniles under rearing conditions.

Nerici, C., Silva, A., & Merino, G.

Nitrogenous compounds can be toxic to aquatic animals, especially when they are reared for production purposes at high stocking densities. Seriolella violacea is a pelagic fish, native from the easterly South Pacific Ocean. This species has shown desirable behavioral and metabolic characteristics under captivity conditions, which leaded the Marine Fish Laboratory from the UCN to increase its efforts on the research and development to validate S. violacea as a new aquaculture option. Therefore, the objective of this study is to determine the excretion rates of palm fish juveniles weighing 300–500 g at two different temperatures: 14 °C and 18 °C. Total ammonia as nitrogen (TAN) excreted was 4.4 ± 0.9 and 7.1 ± 1.9 mg TAN/kg fish/h for 14 °C and 18 °C respectively. The experiments were carried out in a recirculating system operating as a farm-like situation. Tests were performed in 1000 L rearing tanks operating as open respirometers. The results of the present study indicate that TAN excretion rates on S. violacea juveniles, is temperature dependent. Data obtained in these experiments are valuable information for the engineering design of land based aquaculture systems for palm fish.

Año: 2012

Palabras claves: Seriolella violacea; Excretion rates; Ammonia; Recirculating aquaculture system; Water quality

Cold-acclimation limits low temperature induced photoinhibition by promoting a higher photochemical quantum yield and a more effective PSII restoration in darkness in the Antarctic rather than the Andean ecotype of Colobanthus quitensis Kunt Bartl (Cariophyllaceae)

Bascuñán-Godoy, L., Sanhueza, C., Cuba, M., Zuñiga, G., Corcuera, L., & Bravo, L.

Ecotypes of Colobanthus quitensis Kunt Bartl (Cariophyllaceae) from Andes Mountains and Maritime Antarctic grow under contrasting photoinhibitory conditions, reaching differential cold tolerance upon cold acclimation. Photoinhibition depends on the extent of photodamage and recovery capability. We propose that cold acclimation increases resistance to low-temperature-induced photoinhibition, limiting photodamage and promoting recovery under cold. Therefore, the Antarctic ecotype (cold hardiest) should be less photoinhibited and have better recovery from low-temperature-induced photoinhibition than the Andean ecotype. Both ecotypes were exposed to cold induced photoinhibitory treatment (PhT). Photoinhibition and recovery of photosystem II (PSII) was followed by fluorescence, CO2 exchange, and immunoblotting analyses.

Año: 2012

Palabras claves: Antarctic plants, Andean plants, Cold-induced-photoinhibition, Recovery, PSII restoration, D1 cycle, Photoprotection

Physiological performance of juvenile Haliotis rufescens and Haliotis discus hannai abalone exposed to the withering syndrome agent.

González, R., Brokordt, K., & Lohrmann, K.

Withering syndrome (WS) is a serious chronic disease caused by infection with the bacterium Candidatus Xenohaliotis californiensis, a Rickettsiales-like organism (WS-RLO) that affects multiple abalone species in both natural and farmed populations. However, there is no available information regarding the effects of this disease on the physiological performance of infected abalone. We studied the effect of different levels of infection on components of energy balance and physiological indices (rates of absorption and assimilation, O/N ratio, and scope for growth) in the abalone species Haliotis rufescens and Haliotis discus hannai. Juveniles were exposed to C. X. californiensis transmission for 130 days, during which time the presence/absence of WS-RLOs was evaluated by PCR (following DNA sequencing-based confirmation of 100% identity with the sequence of C. X. californiensis from California), and the prevalence and intensity of infection were evaluated via histological analysis. Among H. rufescens juveniles exposed to the bacterium, 92% became infected (positive by histology), and the intensity of infection ranged from low (degree 1) to moderate (degree 2). In contrast, no H. discus hannai juveniles were positive for WS-RLO by histology, although 23% were positive by PCR, possibly indicating incipient WS-RLO infection that did not develop during the experimental period or to mere presence of WS-RLO DNA in the sample. Infection of H. rufescens juveniles by WS-RLOs negatively affected all components of the energy balance and physiological indices, such as scope for growth and the O/N ratio, in direct relation to the degree of infection. The most strongly affected functions were the rate of ingestion, standard metabolism, and production of feces, which were reduced by 60–80% in the most highly infected individuals. The reduced energy intake in the organisms produced a strong energy imbalance such that the energy available for growth was reduced by 49% in infected organisms. In contrast, juveniles of H. discus hannai carrying the bacterium developed no infection and showed no alterations of physiological function. Our results indicate that the level of early infection by WS-RLOs may exert a negative effect on physiological activity in H. rufescens, even when the disease is not evident.

Año: 2012

Palabras claves: Withering syndrome; Candidatus Xenohaliotis californiensis; Abalone; Haliotis rufescens; Haliotis discus hannai; Physiological performance

The marine brooder Excirolana braziliensis (Crustacea: Isopoda) is also a complex of cryptic species on the coast of Chile.

Varela, A. & Haye, P.

Speciation is a direct consequence of isolated populations in taxa with low dispersal potential. The brooding crustacean Excirolana braziliensis, with a presumably wide geographic range of distribution (~16° N-41° S in the Pacific and ~19° N-35° S in the Atlantic), has been detected to correspond to cryptic species on the coast of Panama. Latitudinal variations in reproductive features in E. braziliensis have been attributed to phenotypic plasticity, however, the differences may be the result of divergent populations. Considering that the taxon has been reported to be a complex of cryptic species in other geographic areas and given the phenotypic differences detected along its distribution range, we hypothesized that E. braziliensis is a complex of species in the coast of Chile. We used partial cytochrome c oxidase subunit I (COI) sequences from 132 individuals with the diagnostic morphology of E. braziliensis collected along ~2200 km of coast to determine the genetic structure of E. braziliensis. Phylogenetic and phylogeographic analyses showed three distinct clades with 14 to 19 % of genetic divergence and high values of genetic differentiation. Intra and inter-clade divergence revealed the existence of a species complex of E. braziliensis on the coast of Chile, supporting growing evidence of the high abundance of cryptic species in marine invertebrate taxa.

Año: 2012

Palabras claves: cryptic species, genetic differentiation, genetic distance, marine peracarids, phylogenetics.

Nutritional Aspects of Six Quinoa (Chenopodium quinoa Willd.) Ecotypes from three Geographical Areas of Chile. Chilean

Miranda, M., Vega-Gálvez, A., Quispe-Fuentes, I., Rodríguez, M., Maureira, H., & Martínez, E.

This study explored the diversity of the quinoa crop in Chile from a nutritional perspective. Nutritional properties, minerals, vitamins, and saponin content were assessed in seeds of six Chilean quinoa (Chenopodium quinoa Willd.) ecotypes grown in three main production areas with distinctive climatic and edaphic conditions: Ancovinto and Cancosa in the North-Altiplano or High Plateau, Cáhuil and Faro in the central coastal area, and Regalona and Villarrica in the south of the country. There were significant differences (P < 0.05) in all the nutritional properties of the quinoa seeds in all three areas. Quinoa of the Villarrica ecotype showed the highest protein content (16.10 g 100 g-1 DM) and the highest content of vitamins E and C (4.644 ± 0.240 and 23.065 ± 1.119 mg 100 g-1 DM, respectively). The highest content of vitamins B1 (0.648 ± 0.006 mg 100 g-1 DM) and B3 (1.569 ± 0.026 mg 100 g-1 DM) was found in the Regalona ecotype, while the highest value of vitamin B2 (0.081 ± 0.002 mg 100 g-1 DM) occurred in the Ancovinto ecotype. Potassium was the most abundant mineral with a maximum value of 2325.56 mg 100 g-1 DM in the Cancosa ecotype. Saponin content varied from 0.84 g 100 g-1 DM in the Villarrica ecotype to 3.91 g 100 g-1 DM in the Cáhuil ecotype. Significant differences were found among the Chilean quinoa ecotypes grown under different climatic conditions; however, all the quinoa seeds exhibited a high nutritional value. These results are compatible with the genetic differences previously observed in the three geographical areas under study. Thus, if more studies are conducted to show the particular properties of quinoa from specific areas, it would be possible in the future to coin the term "controlled designation of origin" (appellation d'origine contrólée) and add commercial value to Chilean quinoa seeds in the domestic and international markets.

Año: 2012

Palabras claves: Quinoa, vitamins, minerals, saponin content, nutritional properties.

Morphological variability of intertidal Eisenia arborea (Laminariales, Ochrophyta) at Punta Eugenia, Baja California Sur

Parada, G., Riosmena-Rodriguez, R., Martinez, E., & Hernandez-Carmona, G.

Water motion is one of the main drivers in morphological variability in species within de order Laminariales, and most of our current knowledge is based on subtidal populations. is a dominant kelp species in the North Pacific, widely distributed along the Baja California Peninsula from mid intertidal down to subtidal areas. This species presents great variability in the intertidal zone but it has not been yet evaluated such variability according to wave exposure. The present work also identifies the spatial / temporal variation, particularly respect to the presence of stipes without medulla (hollow stipes) a feature common among other brown seaweeds. We evaluated the effects of wave action in morphological variation of intertidal (Laminariales, Ochrophyta) at Punta Eugenia. The spatial and temporal variation sampling was surveyed between February, May, July, and August 2004 in the intertidal of Punta Eugenia, Baja California Sur. Our results have shown that exposed sites correlate with increased length and width of stipes as compared to more protected sites. Hollow stipes frequency changed more in association with temporal variation than with spatial heterogeneity suggesting nutrient limitation for thalli development. Our results suggest that compensate by morphological modifications the stress of living in the intertidal zone by showing larger stipes. Hollow stipes might be are also a mechanical adaptation to increase survival in high energy environments.

Año: 2012

Palabras claves: Eisenia arborea;intertidal;Laminariales;morphological variability