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Incluye artículos de investigación escritos por investigadores del Instituto y otras instituciones científicas y de educación superior, que hayan contado con los auspicios de INACH. En sus inicios estos trabajos fueron publicados en la serie Publicaciones Ocasionales y otras fuentes de información.
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Item Diet of grey-headed albatrosses at the Diego Ramírez Islands, Chile: ecological implications(Cambridge Universty Press, 2004) Arata, Javier; Robertson, Graham; Valencia, José; Xavier, José C.; Moreno, Carlos A.The diet of grey-headed albatrosses at Diego Ramírez was analysed and compared to that of the sympatric black-browed albatross. Diet composition was inferred from an analysis of prey hard parts present in 103 chick regurgitates obtained during breeding seasons 2000, 2001 and 2002. The squid Martialia hyadesi predominated in the diet samples in 2001 and 2002 (89% and 81% of reconstituted mass), but was absent from the 2000 samples. Reconstituted mean mass per sample in 2000 was significantly lower than in 2001 and 2002. Chick growth rate during 2000 was also the lowest recorded. This suggests that M. hyadesi plays an important role in the breeding performance of grey-headed albatrosses at Diego Ramírez. Low presence of M. hyadesi in grey-headed albatrosses’ diet at South Georgia in 2000, a year with significant low breeding success, suggests ocean-wide processes affecting the availability of this prey to both populations simultaneously. Overlap in diet composition, and inferred feeding areas, between the sympatric albatross species at Diego Ramírez was minimal. Grey-headed albatrosses fed mainly on species associated with the Antarctic Polar Front, whereas black-browed albatrosses consumed benthopelagic species frequently caught in fishing operations in southern Chile.Item La ballena franca del sur, Eubalaena australis (Desmoulins, 1822) en aguas chilenas: análisis de sus registros desde 1976 a 2008(Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, 2008-12) Aguayo-Lobo, Anelio; Acevedo, Jorge; Brito, José Luis; Olavarría, Carlos; Moraga, Rodrigo; Olave, CarlosSe analizaron los avistamientos de Eubalaena australis en aguas chilenas entre los años 1964 y 2008. Durante estos 44 años se han documentado 124 avistamientos con 232 ejemplares incluyendo a 39 crías. La distribución de los registros muestra tres zonas geográficas: i) aguas al norte de los 47°S, ii) aguas entre el estrecho de Magallanes y canal Beagle, y iii) aguas del paso Drake y Antártica. Mensualmente, una alta frecuencia de avistamientos se registró entre agosto y octubre. La mayoría de las crías se registraron al norte de los 41°S, concentrándose entre los 23°S y 25°S y entre los 32° y 36°S. Los tamaños grupales variaron entre 1 a 7 animales, registrándose en las aguas al norte de los 47°S un porcentaje levemente mayor de grupos en pares, mientras que bajo los 47°S, los grupos estuvieron constituidos mayoritariamente por animales solitarios. La tendencia de la población, considerando el total de animales registrados al norte de los 47°S, mostró una tasa de incremento positivo pero no significativa entre los años 1976 y 2008; sin embargo, en el caso de las crías, la tasa fue cercana a 0, sugiriéndose que ambas tasas estarían subestimadas. En consecuencia, es de absoluta necesidad aumentar el esfuerzo de observación de cetáceos, junto a un programa de estudios sistemático, incluyendo la foto-identificación y estudios moleculares, cuyos resultados permitan conocer la ecología y parámetros demográficos necesarios para evaluar esta especie de ballena catalogada ‘En Peligro Crítico’ en aguas chilenas.Item Isolation and characterization of an antarctic flavobacterium strain with agarase and alginate lyase activities(De Gruyter Open, 2016) Lavin, Paris; Atala, Cristian; Gallardo-Cerda, Jorge; González-Aravena, Marcelo; De la Iglesia, Rodrigo; Oses, Rómulo; Torres-Díaz, Cristian; Trefault, Nicole; Molina-Montenegro, Marco A.; Laughinghouse IV, H. DailSeveral bacteria that are associated with macroalgae can use phycocolloids as a carbon source. Strain INACH002, isolated from decomposing Porphyra (Rhodophyta), in King George Island, Antarctica, was screened and characterized for the ability to produce agarase and alginate-lyase enzymatic activities. Our strain INACH002 was identified as a member of the genus Flavobacterium, closely related to Flavobacterium faecale, using 16S rRNA gene analysis. The INACH002 strain was characterized as psychrotrophic due to its optimal temperature (17 ºC) and maximum temperature (20°C) of growth. Agarase and alginate-lyase displayed enzymatic activities within a range of 10°C to 50°C, with differences in the optimal temperature to hydrolyze agar (50°C), agarose (50°C) and alginate (30°C) during the first 30 min of activity. Strain Flavobacterium INACH002 is a promising Antarctic biotechnological resource; however, further research is required to illustrate the structural and functional bases of the enzymatic performance observed during the degradation of different substrates at different temperatures.Item Recent ice dynamic and surface mass balance of Union glacier in the west antarctic ice sheet(Copernicus Publications, 2014-08-06) Rivera, A.; Zamora, R.; Uribe, J.A.; Jaña, Ricardo; Oberreuter, J.Here we present the results of a comprehensive glaciological investigation of Union Glacier (79°460 S/83°240 W) in theWest Antarctic Ice Sheet (WAIS), a major outlet glacier within the Ellsworth Mountains. Union Glacier flows into the Ronne Ice Shelf, where recent models have indicated the potential for significant grounding line zone (GLZ) migrations in response to changing climate and ocean conditions. To elaborate a glaciological base line that can help to evaluate the potential impact of this GLZ change scenario, we installed an array of stakes on Union Glacier in 2007. The stake network has been surveyed repeatedly for elevation, velocity, and net surface mass balance. The region of the stake measurements is in near-equilibrium, and ice speeds are 10 to 33ma−1. Ground-penetrating radars (GPR) have been used to map the subglacial topography, internal structure, and crevasse frequency and depth along surveyed tracks in the stake site area. The bedrock in this area has a minimum elevation of −858ma.s.l., significantly deeper than shown by BEDMAP2 data. However, between this deeper area and the local GLZ, there is a threshold where the subglacial topography shows a maximum altitude of 190 m. This subglacial condition implies that an upstream migration of the GLZ will not have strong effects on Union Glacier until it passes beyond this shallow ice pinning point.Item Early knowledge of antarctica’s vegetation: expanding past and current evidence(Sociedad de Biología de Chile, 2012) Hebel, Ingrid; Galleguillos, Carolina; Jaña, Ricardo; Dacasa-Rüdinger, María D.C.To commemorate one hundred years of Roald Amundsen’s reaching the South Pole, we provide a summary of early explorations to Antarctica, in which botanists played an almost anonymous role. Based on multiple observations of vegetation they found and recorded, we review the knowledge available at the end of the nineteenth century to compare with contemporary scientifi c beliefs; connecting them with observations we have collected in fi eld-work. Using the aerial photography from the end of the 1950s of sites we visited, it is noted that opportunities are arising for the understanding of colonization phenomena in areas where ice is retreating. Accounts of research on colonization of new ice-free areas are analyzed as well as how molecular genetics attempts to deduce the early settlements. Finally, an analysis of conservation in Antarctica is provided and its outlook discussed.Item Glacier mass changes of lake-terminating Grey and Tyndall glaciers at the southern patagonia icefield derived from geodetic observations and energy and mass balance modeling(Frontiers Media, 2018-06-19) Weidemann, Stephanie S.; Sauter, Tobías; Malz, Phillip; Jaña, Ricardo; Arigony-Neto, Jorge; Casassa, Gino; Scheneider, Christoph; Schuler, Thomas VikhamarIn this study we demonstrate how energy andmass fluxes vary in space and time for Grey and Tyndall glaciers at the Southern Patagonia Icefield (SPI). Despite the overall glacier retreat of most Patagonian glaciers, a recent increase in mass loss has been observed, but individual glaciers respond differently in terms of spatial and temporal changes. In this context, the detailed investigation of the effect of mass balance processes on recent glacier response to climate forcing still needs refinement. We therefore quantify surface energy-fluxes and climatic mass balance of the two neighboring glaciers, Grey and Tyndall. The COupled Snow and Ice energy and MAss balance model COSIMA is applied to assess recent surface energy and climatic mass balance variability with a high temporal and spatial resolution for a 16-year period between April 2000 and March 2016. The model is driven by downscaled 6-hourly atmospheric data derived from ERA-Interim reanalysis and MODIS/Terra Snow Cover and validated against ablation measurements made in single years. High resolution precipitation fields are determined by using an analytical orographic precipitation model. Frontal ablation is estimated as residual of climatic mass balance and geodetic mass balance derived from TanDEM-X/SRTM between 2000 and 2014. We simulate a positive glacier-wide mean annual climatic mass balance of +1.02 ± 0.52mw.e. a−1 for Grey Glacier and of +0.68 ± 0.54mw.e. a−1 for Tyndall Glacier between 2000 and 2014. Climatic mass balance results show a high year to year variability. Comparing climatic mass balance results with previous studies underlines the high uncertainty in climatic mass balance modeling with respect to accumulation on the SPI. Due to the lack of observations accumulation estimates differ from previous studies based on the methodological approaches. Mean annual ice loss by frontal ablation is estimated to be 2.07 ± 0.70mw.e. a−1 for Grey Glacier and 3.26 ± 0.82mw.e. a−1 for Tyndall Glacier between 2000 and 2014. Ice loss by surface ablation exceeds ice loss by frontal ablation for both glaciers. The overall mass balance of Grey and Tyndall glaciers are clearly negative with −1.05 ± 0.18mw.e. a−1 and −2.58 ± 0.28mw.e. a−1 respectively.Item HSP70 from the Antarctic sea urchin Sterechinus neumayeri: molecular characterization and expression in response to heat stress(Sociedad de Biología de Chile, 2018) González-Aravena, Marcelo; Calfio, Camila; Mercado, Luis; Morales-Lange, Byron; Bethke, Jorn; De Lorgeril, Julien; Cárdenas, César A.Background: Heat stress proteins are implicated in stabilizing and refolding denatured proteins in vertebrates and invertebrates. Members of the Hsp70 gene family comprise the cognate heat shock protein (Hsc70) and inducible heat shock protein (Hsp70). However, the cDNA sequence and the expression of Hsp70 in the Antarctic sea urchin are unknown. Methods: We amplified and cloned a transcript sequence of 1991 bp from the Antarctic sea urchin Sterechinus neumayeri, experimentally exposed to heat stress (5 and 10 °C for 1, 24 and 48 h). RACE-PCR and qPCR were employed to determine Hsp70 gene expression, while western blot and ELISA methods were used to determine protein expression. Results: The sequence obtained from S. neumayeri showed high identity with Hsp70 members. Several Hsp70 family features were identified in the deduced amino acid sequence and they indicate that the isolated Hsp70 is related to the cognate heat shock protein type. The corresponding 70 kDa protein, called Sn-Hsp70, was immune detected in the coelomocytes and the digestive tract of S. neumayeri using a monospecific polyclonal antibody. We showed that S. neumayeri do not respond to acute heat stress by up-regulation of Sn-Hsp70 at transcript and protein level. Furthermore, the Sn-Hsp70 protein expression was not induced in the digestive tract. Conclusions: Our results provide the first molecular evidence that Sn-Hsp70 is expressed constitutively and is noninduced by heat stress in S. neumayeri.Item Expression pattern of heat shock proteins during acute thermal stress in the antarctic sea urchin, Sterechinus neumayeri(Sociedad de Biología de Chile, 2016) González, Karina; Gaitán-Espitia, Juan; Font, Alejandro; Cárdenas, César A.; González-Aravena, MarceloBackground: Antarctic marine organisms have evolved a variety of physiological, life-history and molecular adaptations that allow them to cope with the extreme conditions in one of the coldest and most temperaturestable marine environments on Earth. The increase in temperature of the Southern Ocean, product of climate change, represents a great challenge for the survival of these organisms. It has been documented that some Antarctic marine invertebrates are not capable of generating a thermal stress response by means of an increase in the synthesis of heat shock proteins, which could be related with their low capacity for acclimatization. In order to understand the role of heat shock proteins as a compensatory response in Antarctic marine species to projected scenarios of increased seawater temperatures, we assessed the expression of the genes Hsp90, Grp78, Hyou1 and Hsc70 in the Antarctic sea urchin Sterechinus neumayeri under three thermal treatments (1 °C, 3 °C and 5 °C), for a period of exposure of 1, 24 and 48 h. Results: The results obtained showed that these genes were expressed themselves in all of the tissues analyzed in a constitutive form. During acute thermal stress, an overexpression of the Hsp90, Grp78 and Hyou1 genes was observed in coelomocyte samples at 3 °C after 48 h, while in esophageal samples, an increase in Hsp90 and Grp78 expression was observed after 48 h. Thermal stress at 5 °C, in general, did not produce a significant increase in the expression of the genes that were studied. The expression of Hsp70 did not show modifications in its expression as a result of thermal stress. Conclusions: S. neumayeri is capable of overexpressing stress proteins as a result of thermal stress, however, this response is delayed and to a lesser degree compared to other Antarctic or temperate species. These results indicate that adult individuals could cope with the expected impacts caused by an increase in coastal sea temperatures in the Southern Ocean.Item Pseudomonas and pedobacter isolates from King George Island inhibited the growth of foodborne pathogens(De Gruyter Open, 2011) Wong, Clemente Michael Vui Ling; Tam, Heng Keat; Alias, Siti Aisyah; González, Marcelo; González-Rocha, Gerardo; Domínguez-Yévenes, MarianaThis report describes the isolation and characterization of bacterial isolates that produce anti−microbial compounds from one of the South Shetland Islands, King George Is− land, Antarctica. Of a total 2465 bacterial isolates recovered from the soil samples, six (BG5, MTC3, WEK1, WEA1, MA2 and CG21) demonstrated inhibitory effects on the growth of one or more Gram−negative or Gram−positive indicator foodborne pathogens (i.e. Escherichia coli 0157:H7, Salmonella spp., Klebsiella pneumoniae, Enterobacter cloacae, Vibrio parahaemolyticus and Bacillus cereus). Upon examination of their 16S rRNA se− quences and biochemical profiles, the six Antarctic bacterial isolates were identified as Gram−negative Pedobacter cryoconitis (BG5), Pseudomonas migulae (WEK1), P. corru− gata (WEA1) and Pseudomonas spp. (MTC3, MA2, and CG21). While inhibitors produced by strains BG5, MTC3 and CG21 were sensitive to protease treatment, those produced by strains WEK1, WEA1, and MA2 were insensitive to catalase, lipase, −amylase, and prote− ase enzymes. In addtion, the six Antarctic bacterial isolates appeared to be resistant to multi− ple antibiotics.Item High similarity in the microbiota of cold- water sponges of the Genus Mycale from two different geographical areas(Peerj Inc, 2018-06-07) Cárdenas, César A.; González-Aravena, Marcelo; Font, Alejandro; Hestetun, Jon T.; Hajdu, Eduardo; Trefault, Nicole; Malmberg, Maja; Bongcam-Rudloff, ErikSponges belonging to genus Mycale are common and widely distributed across the oceans and represent a significant component of benthic communities in term of their biomass, which in many species is largely composed by bacteria. However, the microbial communities associated with Mycale species inhabiting different geographical areas have not been previously compared. Here, we provide the first detailed description of the microbiota of two Mycale species inhabiting the sub-Antarctic Magellan region (53 S) and the Western Antarctic Peninsula (62 64 S), two geographically distant areas (>1,300 km) with contrasting environmental conditions. The sponges Mycale (Aegogropila) magellanica and Mycale (Oxymycale) acerata are both abundant members of benthic communities in the Magellan region and in Antarctica, respectively. High throughput sequencing revealed a remarkable similarity in the microbiota of both sponge species, dominated by Proteobacteria and Bacteroidetes, with both species sharing more than 74% of the OTUs. In contrast, 16% and 10% of the OTUs were found only in either M. magellanica or M. acerata, respectively. Interestingly, despite slight differences in the relative abundance, the most dominant OTUs were present in both species, whereas the unique OTUs had very low abundances (less than 1% of the total abundance). These results show a significant overlap among the microbiota of both Mycale species and also suggest the existence of a low level of specificity of the most dominant symbiont groups.Item The importance of local settings: within-year variability in seawater temperature at south bay, western antarctic peninsula(Peerj Inc, 2018-01-18) Cárdenas, C.A; González-Aravena, Marcelo; Santibáñez, Pamela A.The Western Antarctic Peninsula (WAP) has undergone significant changes in air and seawater temperatures during the last 50 years. Although highly stenotherm Antarctic organisms are expected to be severely affected by the increase of seawater temperature, high-resolution datasets of seawater temperature within coastal areas of the WAP (where diverse marine communities have been reported) are not commonly available. Here we report on within-year (2016 2017) variation in seawater temperature at three sites on Doumer Island, Palmer Archipelago, WAP. Within a year, Antarctic organisms in South Bay were exposed to water temperatures in excess of 2 C for more than 25 days and 2.5 C for more than 10 days. We recorded a temperature range between����1.7 to 3.0 C. Warming of seawater temperature was 3.75 times faster after October 2016 than it was before October. Results from this study indicate that organisms at South Bay are already exposed to temperatures that are being used in experimental studies to evaluate physiological responses to thermal stress in WAP organisms. Continuous measurements of short to long-term variability in seawater temperature provides important information for parametrizing meaningful experimental treatments that aim to assess the local effects of environmental variation on Antarctic organisms under future climate scenarios.Item Synthesis delivering 21st century antarctic and southern ocean science(Cambridge Universty Press, 2016-10-21) Kennicutt, M.C.; Kim, Y.D.; Rogan-Finnemore, R.; Anandakrishnan, S.; Chown, S.L.; Colwell, S.; Cowan, D.; Escutia, C.; Frenot, Y.; Hall, J.; Ligget, D.; Mcdonald, A.J.; Nixdorf, U.; Siegert, M.J.; Storey, J.; Walhlin, A.; Weatherwax, A.; Cárdenas, C.A; Wilson, G.S.; Wilson, T.; Wooding, R.; Ackley, S.; Biebow, N.; Blankenship, D.The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process ‘big data’ collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets essential. Future research will require continentand ocean-wide environmentally responsible access to coastal and interior Antarctica and the Southern Ocean. Year-round access is indispensable. The cost of future Antarctic science is great but there are opportunities for all to participate commensurate with national resources, expertise and interests. The scope of future Antarctic research will necessitate enhanced and inventive interdisciplinary and international collaborations. The full promise of Antarctic science will only be realized if nations act together.Item Antibacterial activity of the antarctic bacterium Janthinobacterium sp. SMN 33.6 against multi-resistant Gram-negative bacteria(Pontificia Universidad Católica de Valparaíso, 2014) Asencio, Geraldine; Lavin, Paris; Alegria, Karen; Domínguez, Mariana; Bello, Helia; González-Rocha, Gerardo; González-Aravena, MarceloBackground: The increment of resistant strains to commonly used antibiotics in clinical practices places in evidence the urgent need to search for newcompounds with antibacterial activity. The adaptations that Antarctic microorganisms have developed, due to the extreme environment that they inhabit, promote themas a potential new source of active compounds for the control of microorganisms causing infections associated with health care. The aimof this studywas to evaluate the antibacterial activity of an ethanol extract of the Antarctic bacterium Janthinobacterium sp., strain SMN 33.6, against nosocomial multi-resistant Gram-negative bacteria. Results: Inhibitory activity against human Gram-negative bacterial pathogens, with concentrations that varied between 0.5 and 16 μg ml-1, was demonstrated. Conclusions: The ethanolic extract of Janthinobacterium sp. SMN 33.6 possesses antibacterial activity against a chromosomal AmpC beta-lactamase-producing strain of Serratia marcescens, an extended-spectrum beta-lactamase-producing Escherichia coli and also against carbapenemase-producing strains of Acinetobacter baumannii and Pseudomonas aeruginosa. This becomes a potential and interesting biotechnological tool for the control of bacteria with multi-resistance to commonly used antibiotics.Item Marine debris: global and regional impacts(Universidad de Magallanes, 2011) Torres N., Daniel; Berguño Barnes, JorgeA synthesis on the Marine Debris problem is given upon de basis of the general knowledge on the matter as well as that obtained at Cape Shirreff, Livingston Island, South Shetland, Antarctica. It is suggested to improve the database on marine debris through permanent scientific research as well as with monitoring activities. It is necessary to coordinate key groups to apply strategies to identify types, sources, amount, interactions and socio-economic aspects of this global and regional problem. It would be necessary to develop basic marine indices with the purpose to share a wide knowledge and information about the problem in a transparent way. The Global Programme of Action for the Protection of the Marine Environment from Land-Based Activities (GPA) has some objectives related to the marine debris problem that it is necessary to be applied to all sources, based on the information given by several organizations in a cooperative way. Measurements to prevent and reduce the impact of marine debris are mentioned, especially taken into account the special nature of the marine environment and vulnerable condition. International legal instruments are cited, including waste management, facilities to garbage reception at ports. Education and awareness is a key aspect to reduce and prevent future marine debris problems, taking into account the legal aspects and vulnerability of the Southern Ocean. It is concluded that the CEP would adopt measures to reduce the impact in the Antarctic marine ecosystem, such as requesting to IAATO to establish a Code of Conduct to minimize the problem; to support the CCAMLR initiative to maintain, improve and expand the monitoring activities in other CEMP Sites; recommend the development of educational strategies upon the basis of APEC, CCAMLR, FAO, GPA; and include an especial section of the Final Report of the ATCM Meetings in order to be sent to the consideration of the UN Secretary General as a contribution to discussions to be held at the annual United Nations Open-ended Informal Consultative Process on Oceans and the Law of the Sea.Item Ophiuroideos colectados por la XIX Expedición Antártica Chilena(Instituto Antártico Chileno, 1967) Castillo, Jorge; Instituto Antártico ChilenoEn el presente trabajo se hace un estudio sistemático de la colección de ofiuroídeos obtenidos durante el transcurso de la Décimo Novena Expedición Antártica chilena, que reúne ejemplares de las Islas Shetland del Sur y Tierra de O'Higgins. Para esto se determinó la posición sistemática de las diez especies presentes en la colección y posteriormente se hizo la descripción de cada una de ellas. También se describe una nueva variedad de la especie Ophiacantha antarctica, KOEHLER, 1901. Se acompañan las descripciones con tres láminas de fotografías de las especies estudiadas y tres con dibujos de las placas orales y dentales de estas especies, por estimarse que ellas son de importancia para la taxonomía de este grupo.Item Estudios ecológicos en Isla Robert (Shetland del Sur) 2. Distribución altitudinal de los artropodos terrestres(Instituto Antártico Chileno, 1968) Schlatter, Roberto; Hermosilla, Wladimir; Di Castri, Francesco; Instituto Antártico ChilenoEn la isla Robert (Shetland del Sur) se realizaron recolecciones cuantitativas de Artrópodos terrestres, extraídos mediante embudos de Berlese-Tullgren. La zona estudiada fue el cerro Triplet (140 m) y algunos lugares planos de la isla. La diversidad específica, expresada en bits por individuo, es en general más alta en el cerro que en las zonas bajas. En cuanto a la densidad, expresada en individuos por 1000 cc, ésta disminuye hacia las partes superior es del cerro.Item Estudios ecológicos en Isla Robert (Shetland del Sur) 1. Observaciones de temperatura en nidos de petrel gigante macronectes giganteus (Gmelin)(Instituto Antártico Chileno, 1968) Saiz, Francisco; Hajek, ErnstEn la Isla Robert (Shetland del Sur) se controlaron temperaturas en nidos de petrel gigante (Macronectes giganteus) durante 45 días, incluyendo parte de las fases de incubación y cría. Las mediciones se realizaron mediante termistores cada 6 horas. Los resultados se discuten comparativamente con la situación en nidos de Sterna vittata.Item Estudio Cristalográfico de Minerales de la Antártica. 1ra Parte(Instituto Antártico Chileno, 1966) Villaroel, Hugo; Instituto Antártico ChilenoSe ha hecho el estudio por difracción de rayos X de muestras extraídas en las islas Greenwich, Robert y Media Luna, pertenecientes a las Shetland del Sur. Se determinaron 28 compuestos y se incluye la lista de los espaciados interplanares con sus intensidades.Item Bryozoa colectados durante la Expedición Antártica Chilena 1964 - 65. II. Familia Corymboporidea Smitt, 1866 (Bryozoa, Cyclostomata)(Instituto Antártico Chileno, 1966) Moyano, Iván; Instituto Antártico ChilenoLos bryozoos ciclostomados, posiblemente sean los más difíciles de abordar, debido a la variabilidad de sus especies y a que el carácter de mayor valor sistemático, la ovicela, no siempre se encuentra presente en los ejemplares colectados. El presente trabajo describir justamente este importante carácter para, la especie que WATERS (1904: 98) denominó Heteropora claviformis, hecho que viene a arrojar nuevas luces sobre su posición sistemática. También ha sido nuestra intención señalar de qué manera puede variar la forma zoarial con la edad, con los epizoos o con los daños que sufra la colonia durante su desarrollo. La gran variación zoarial de la especie que consideramos habría hecho pensar en la existencia de más de una especie o subespecie, si se hubiese colectado en lugares geográficamente muy apartados. Pero como todos nuestros ejemplares proceden de un solo lugar, pensamos y estamos seguros que se trata de una sola especie, existiendo todas las formas intermedias entre colonias muy irregulares y otras simétricamente fungiformes. El estudio de los ejemplares nos permite dar a conocer nuevas observaciones sobre la especie de WATERS y nos da otro punto de vista sobre su posición sistemática.Item Revista de difusión n°11-12(Instituto Antártico Chileno, 1978) Instituto Antártico Chileno
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