Transcriptomics and population differentiation in two notothenioid Antarctic fish

Antarctic notothenioids radiated over past millions of years in extremely cold waters, they display a wide range of adaptations to withstand the cold and now dominate the Antarctic fish fauna. These fish may be extremely vulnerable to climate change with possible cascading effects on the entire Antarctic marine ecosystem. Therefore, crucial tasks are the concomitant study of the genomic basis of cold adaptation, the analysis of differentiation processes resulting from past and present climate change and a close survey of the current level of genetic variation and population structure. We considered four species of the Notothenioidei suborder: the three recently derived species of the Chionodraco genus, namely Chionodraco hamatus, Chionodraco rastrospinosus and Chionodraco myersi, and Pleuragramma antarcticum. The Chionodraco genus belongs to the family Channichthyidae (icefish), unique among vertebrates for the lack of hemoglobin and myoglobin expression in skeletal muscle. Oxygen delivery to tissues is ensured by a marked remodeling of the cardio-vascular system and by exceptionally high mitochondrial densities in the muscle. P. antarcticum (Nototheniidae) is the only notothenioid with a complete pelagic life cycle; it is dependent on sea ice and plays a key role in the trophic web of the Antarctic marine ecosystem. Analyses performed in this PhD can be grouped in two major lines of research: 1) the deepening of the knowledge on the genetic and genomic basis of icefish adaptation to the cold; 2) the analysis of patterns of intra- and inter-specific genetic differentiation with particular emphasis on how past and present environmental conditions have shaped and are influencing the fish genetic structure. With regard to the first line of research, we reconstructed and annotated the first normalized transcriptome of C. hamatus skeletal muscle and we exploited deep sequencing information of this energy-dependent tissue to test the hypothesis of duplication of genes involved in mitochondrial function. Using a dedicated bioinformatic pipeline we identified 124 duplicated genes specific to the icefish lineage. Significantly more duplicates were found in C. hamatus when transcriptome data were compared with whole genome data of model fish. Duplicated genes were significantly enriched in proteins with mitochondrial localization, involved in mitochondrial function and biogenesis. The combination of high mitochondrial densities and the maintenance of duplicated genes involved in mitochondrial function might confer a selective advantage in cold conditions and in the absence of oxygen-carrying proteins, by improving oxygen diffusion and energy supply to aerobic tissues. With regard to the second line of research, in the Chionodraco genus we investigated the pattern of intra- and inter- specific genetic differentiation. We found intraspecific homogeneity, but three distinct gene pools corresponding to the nominal species. We searched for putative outlier loci detecting a high level of genetic differentiation between the three species and we identified three loci, possibly influenced by natural selection, showing sequence similarity to a calmodulin transcript, an antifreeze glycoprotein/trypsinogen-like protease gene and to the mRNA of a key component of the super elongation complex. Selective pressures acting on specific loci might reflect past evolutionary processes leading to species divergence and local adaptation. The extent and timing of interspecific gene exchange was also considered to clarify the role of glacial cycles in promoting the divergence and the introgression of the Chionodraco species. We found evidences of past and present introgression: several individuals in each species showed mixed ancestry; evolutionary scenarios excluding hybridization or including it only in ancient times had small or zero posterior probabilities; data supported a scenario of interspecific gene flow associated with the two most recent interglacial periods. These findings may indicate an increased opportunity for speciation in allopatric refugia during glacial periods, followed by secondary contacts and hybridization during warmer intervals. With regard to P. antarcticum, we investigated its population genetic structure along the Antarctic Peninsula (AP), a region highly impacted by regional warming. We found a single gene pool and absence of inter-annual variability in the south-western AP, while significant differences were detected on a geographic scale from samples collected off the tip of the AP, with a signal of increased fragmentation over time. The reduced level of gene flow along the shelf, the increase of differentiation through time, and the inability to capture P. antarcticum in the central-western AP for two consecutive years, all suggest that this sea ice dependent species has been affected by climate change with possible cascading effects on the Antarctic marine food web

Microbe-assisted seedling crop improvement by a seaweed extract to address fucalean forest restoration

In the Mediterranean, Cystoseira sensu lato (s.l.) (Phaeophyceae) forests have sharply declined and restoration measures are needed to compensate for the loss. Assisted regeneration through the outplanting of seedlings grown ex-situ has proven to be a sustainable option. Optimizing mesocosm culture can maximize survival of the most critical embryonic stages and reduce long-term maintenance costs. Host-microbiome interactions could also play a crucial role in seedling development and welfare. In this context, we aimed to advance a cultivation protocol that stimulates the growth and fitness of Ericaria amentacea (Phaeophyceae) seedlings and identify the associated microbial biofilm communities. Seedlings were cultured in 6 treatments [i.e., filtered seawater (SW, C, Control), von Stoch-enriched SW (VS), VS + algal extract (VSA), algal extract-enriched SW: A1< A2< A3]. After the field, A2 seedlings had the highest cover (1372 ± 53.66 mm2), which was 1.8 and 1.9 times greater than in VS and VSA, respectively. The addition of the algal extract and nutrients significantly affected the structure and composition of the microbial community that shifted over time in each culture medium. We identified a treatment-specific microbial fingerprint. After the mesocosm phase, A2 was characterized by 4 unique taxa: Postechiella, Winogradskyella, Roseovarius and Arenibacter (Bacteria). Given the success of A2 seedlings, we propose the probiotic consortia candidates characterized by the unique treatment-taxa in conjunction with the shared taxon Psychroserpens (Bacteria, present in A1, A2, VSA, VS) and the reminder community. Within the holobiont concept, the effect of algal extract or nutrients on the algae and/or biofilm could have important consequences for tuning the overall interaction networks. Our study has shown that macroalgal restoration could benefit from both the use of commercial algal extract and tailored nutrient enrichment in ex-situ cultures and the identification of probiotic consortia candidates that promote seedling growth

Histopathological comparison of intramural coronary artery remodeling and myocardial fibrosis in obstructive versus end-stage hypertrophic cardiomyopathy.

Abstract Background Although imaging techniques have demonstrated the existence of microvascular abnormalities in hypertrophic cardiomyopathy (HCM), a detailed histopathological assessment is lacking as well as a comparison between different phases of the disease. We aimed to compare microvasculopathy and myocardial fibrosis in hypertrophic obstructive cardiomyopathy (HOCM) versus end-stage (ES) HCM. Methods 27 myectomy specimens of HOCM patients and 30 ES-HCM explanted hearts were analyzed. Myocardial fibrosis was quantitatively determined with dedicated software and qualitatively classified as scar-like or interstitial. Intramural coronary arteries were evaluated separately according to lumen diameter: 100–500 μ versus Results Median value of fibrosis in the anterobasal septum of explanted hearts was 34.6% as opposed to 10.3% of myectomy specimens (p  Conclusions Microvasculopathy is an intrinsic feature of HCM with similar characteristics across the natural phases of the disease. Conversely, myocardial fibrosis changes over time with ES hearts showing a three-fold greater amount, mainly scar-like. ES showed a closer association between microvasculopathy and replacement fibrosis

Cultivos puente verde como herramienta para manejar la nutrición nitrogenada de maíz

El uso de cultivos puente verde se viene generalizando en la región y resulta muy importante conocer en qué medida se ve afectada la disponibilidad de agua y nitrógeno en el cultivo de maíz. Este artículo nos acerca resultados respecto a ello.EEA BalcarceFil: Crespo, Cecilia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Crespo, Cecilia. Instituto Nacional de Tecnología Agropecuaria (INTA). Chacra Experimental Integrada Barrow; Argentina.Fil: Corral, Raúl Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Chacra Experimental Integrada Barrow; Argentina.Fil: Corral, Raúl A. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Diez, Santiago. Universidad de Buenos Aires. Facultad de Agronomía; Argentina.Fil: Delgado, Santiago. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Domínguez, Germán. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Agostini, María. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Cendoya, Gabriela. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Sainz Rozas, Hernán Rene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.Fil: Sainz Rozas, Hernán Rene. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Sainz Rozas, Hernán Rene. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: García, Gisela. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Studdert, Guillermo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina

Componente 6. Herramientas de información, divulgación y participación : Plan de Acción para la Conservación de los Anfibios de la República Argentina

El público general desconoce que la República Argentina es uno de los países con mayor diversidad de anfibios en América Latina, presentando unas 175 especies, con una gran proporción de endemismos, ciclos de vida únicos y adaptaciones fisiológicas y/o comportamentales a ambientes extremos (entre otras). La visión general es que la diversidad de anfibios se limita solo a sapos, ranas (inclusive, es común que sean consideradas el femenino de los sapos) y escuerzos. Uno de los aspectos más problemáticos a la hora de generar interés en la comunidad sobre la conservación de anfibios, es el desconocimiento del rol que cumplen en los ecosistemas, así como también los beneficios que este grupo puede proveer. También, abundan en el saber popular leyendas o mitos sobre la peligrosidad o características nocivas de los anfibios. En gran parte, esta falta de conocimiento se basa en la dificultad que enfrenta el público general, educadores y/o interesados en la naturaleza para acceder a información de calidad y con un lenguaje simple sobre la fauna de anfibios. Bajo la premisa ?no se conserva lo que no se conoce? es que se debería lograr generar información, sobre la diversidad de especies de anfibios de la Argentina y sus problemáticas de conservación, que involucre un lenguaje claro y resulte accesible a todo tipode público. Por otra parte, los museos, privados o estatales (nacionales, provinciales y municipales), son los lugares más comunes donde el público general concurre a interiorizarse sobre las ciencias naturales. Aunque los anfibios rara vez ocupan lugares preponderantes dentro de las exposiciones permanentes o temporales, esta tendencia se ha revertido en los últimos años, principalmente por iniciativas como "La Noche de los Museos", donde los investigadores pueden comunicar directamente al público concurrente la información sobre sus líneas de investigación y organismos de estudio.Asociación Herpetológica Argentin

Current threats faced by amphibian populations in the southern cone of South America

In this work, we update and increase knowledge on the severity and extent of threats affecting 57 populations of 46 amphibian species from Chile and Argentina in southern South America. We analyzed the intrinsic conservation problems that directly impact these populations. We shared a questionnaire among specialists on threats affecting target amphibian populations with information on i) range, ii) historical occurrence and abundance, iii) population trends, iv) local extinctions, v) threats, and vi) ongoing and necessary conservation/research. We assessed association patterns between reported threats and population trends using multiple correspondence analysis. Since 2010, 25 of 57 populations have declined, while 16 experienced local extinctions. These populations were affected by 81% of the threat categories analyzed, with those related to agricultural activities and/or habitat modifications being the most frequently reported. Invasive species, emerging diseases, and activities related to grazing, ranching, or farming were the threats most associated with population declines. Low connectivity was the most frequent intrinsic conservation problem affecting 68% of the target populations, followed by low population numbers, affecting 60%. Ongoing monitoring activity was conducted in 32 (56%) populations and was the most frequent research activity. Threat mitigation was reported in 27 (47%) populations and was the most frequent ongoing management activity. We found that habitat management is ongoing in 5 (9%) populations. At least 44% of the amphibian populations surveyed in Chile and Argentina are declining. More information related to the effect of management actions to restore habitats, recover populations, and eliminate threats such as invasive species is urgently needed to reverse the conservation crisis facing amphibians in this Neotropical region.Fil: Kacoliris, Federico Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Berkunsky, Igor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto Multidisciplinario de Ecosistemas y Desarrollo Sustentable; ArgentinaFil: Acosta, Juan Carlos. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Acosta, Rodrigo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Agostini, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Akmentins, Mauricio Sebastián. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Arellano, María Luz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Azat, Claudio. Universidad Andrés Bello; ChileFil: Bach, Nadia Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Blanco, Mirta Blanco. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Calvo, Rodrigo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Charrier, Andres. Pontificia Universidad Católica de Chile; ChileFil: Corbalán, Valeria Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Correa, Claudio. Universidad de Concepción. Facultad de Ciencias Naturales y Oceanografía. Departamento de Zoología; ChileFil: Cuello, Maria Elena. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Deutsch, Camila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Di Pietro, Diego Omar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Gastón, María Soledad. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Gomez Alez, Rodrigo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Kaas, Camila. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Kaas, Nicolas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Lobos, Gabriel. Universidad de Chile; ChileFil: Martínez, Tomás Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Martínez Aguirre, Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Mora, Marta. Vida Nativa NGO; ChileFil: Nieva Cocilio, Rodrigo Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Pastore, Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Administración de Parques Nacionales; ArgentinaFil: Pérez Iglesias, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Laboratorio de Biología; ArgentinaFil: Piaggio Kokot, Lia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Rabanal, Felipe. Universidad Austral de Chile; ChileFil: Rodríguez Muñoz, Melina Jesús. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Sanchez, Laura Cecilia. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Tala, Charif. Ministerio del Medio Ambiente de Chile; ChileFil: Ubeda, Carmen Adria. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Vaira, Marcos. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Velasco, Melina Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; ArgentinaFil: Vidal, Marcela. Universidad del Bio Bio. Facultad de Ciencias. Departamento de Ciencias Basicas; ChileFil: Williams, Jorge Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; Argentin

Differential Effects of Vpr on Single-cycle and Spreading HIV-1 Infections in CD4+ T-cells and Dendritic Cells

The Vpr protein of human immunodeficiency virus type 1 (HIV-1) contributes to viral replication in non-dividing cells, specifically those of the myeloid lineage. However, the effects of Vpr in enhancing HIV-1 infection in dendritic cells have not been extensively investigated. Here, we evaluated the role of Vpr during infection of highly permissive peripheral blood mononuclear cells (PBMCs) and CD4+ T-cells and compared it to that of monocyte-derived dendritic cells (MDDCs), which are less susceptible to HIV-1 infection. Infections of dividing PBMCs and non-dividing MDDCs were carried out with single-cycle and replication-competent HIV-1 encoding intact Vpr or Vpr-defective mutants. In contrast to previous findings, we observed that single-cycle HIV-1 infection of both PBMCs and MDDCs was significantly enhanced in the presence of Vpr when the viral stocks were carefully characterized and titrated. HIV-1 DNA quantification revealed that Vpr only enhanced the reverse transcription and nuclear import processes in single-cycle HIV-1 infected MDDCs, but not in CD4+ T-cells. However, a significant enhancement in HIV-1 gag mRNA expression was observed in both CD4+ T-cells and MDDCs in the presence of Vpr. Furthermore, Vpr complementation into HIV-1 virions did not affect single-cycle viral infection of MDDCs, suggesting that newly synthesized Vpr plays a significant role to facilitate single-cycle HIV-1 infection. Over the course of a spreading infection, Vpr significantly enhanced replication-competent HIV-1 infection in MDDCs, while it modestly promoted viral infection in activated PBMCs. Quantification of viral DNA in replication-competent HIV-1 infected PBMCs and MDDCs revealed similar levels of reverse transcription products, but increased nuclear import in the presence of Vpr independent of the cell types. Taken together, our results suggest that Vpr has differential effects on single-cycle and spreading HIV-1 infections, which are dependent on the permissiveness of the target cell

La renovación de la palabra en el bicentenario de la Argentina : los colores de la mirada lingüística

El libro reúne trabajos en los que se exponen resultados de investigaciones presentadas por investigadores de Argentina, Chile, Brasil, España, Italia y Alemania en el XII Congreso de la Sociedad Argentina de Lingüística (SAL), Bicentenario: la renovación de la palabra, realizado en Mendoza, Argentina, entre el 6 y el 9 de abril de 2010. Las temáticas abordadas en los 167 capítulos muestran las grandes líneas de investigación que se desarrollan fundamentalmente en nuestro país, pero también en los otros países mencionados arriba, y señalan además las áreas que recién se inician, con poca tradición en nuestro país y que deberían fomentarse. Los trabajos aquí publicados se enmarcan dentro de las siguientes disciplinas y/o campos de investigación: Fonología, Sintaxis, Semántica y Pragmática, Lingüística Cognitiva, Análisis del Discurso, Psicolingüística, Adquisición de la Lengua, Sociolingüística y Dialectología, Didáctica de la lengua, Lingüística Aplicada, Lingüística Computacional, Historia de la Lengua y la Lingüística, Lenguas Aborígenes, Filosofía del Lenguaje, Lexicología y Terminología

Transcriptomics and population differentiation in two notothenioid Antarctic fish

Antarctic notothenioids radiated over past millions of years in extremely cold waters, they display a wide range of adaptations to withstand the cold and now dominate the Antarctic fish fauna. These fish may be extremely vulnerable to climate change with possible cascading effects on the entire Antarctic marine ecosystem. Therefore, crucial tasks are the concomitant study of the genomic basis of cold adaptation, the analysis of differentiation processes resulting from past and present climate change and a close survey of the current level of genetic variation and population structure. We considered four species of the Notothenioidei suborder: the three recently derived species of the Chionodraco genus, namely Chionodraco hamatus, Chionodraco rastrospinosus and Chionodraco myersi, and Pleuragramma antarcticum. The Chionodraco genus belongs to the family Channichthyidae (icefish), unique among vertebrates for the lack of hemoglobin and myoglobin expression in skeletal muscle. Oxygen delivery to tissues is ensured by a marked remodeling of the cardio-vascular system and by exceptionally high mitochondrial densities in the muscle. P. antarcticum (Nototheniidae) is the only notothenioid with a complete pelagic life cycle; it is dependent on sea ice and plays a key role in the trophic web of the Antarctic marine ecosystem. Analyses performed in this PhD can be grouped in two major lines of research: 1) the deepening of the knowledge on the genetic and genomic basis of icefish adaptation to the cold; 2) the analysis of patterns of intra- and inter-specific genetic differentiation with particular emphasis on how past and present environmental conditions have shaped and are influencing the fish genetic structure. With regard to the first line of research, we reconstructed and annotated the first normalized transcriptome of C. hamatus skeletal muscle and we exploited deep sequencing information of this energy-dependent tissue to test the hypothesis of duplication of genes involved in mitochondrial function. Using a dedicated bioinformatic pipeline we identified 124 duplicated genes specific to the icefish lineage. Significantly more duplicates were found in C. hamatus when transcriptome data were compared with whole genome data of model fish. Duplicated genes were significantly enriched in proteins with mitochondrial localization, involved in mitochondrial function and biogenesis. The combination of high mitochondrial densities and the maintenance of duplicated genes involved in mitochondrial function might confer a selective advantage in cold conditions and in the absence of oxygen-carrying proteins, by improving oxygen diffusion and energy supply to aerobic tissues. With regard to the second line of research, in the Chionodraco genus we investigated the pattern of intra- and inter- specific genetic differentiation. We found intraspecific homogeneity, but three distinct gene pools corresponding to the nominal species. We searched for putative outlier loci detecting a high level of genetic differentiation between the three species and we identified three loci, possibly influenced by natural selection, showing sequence similarity to a calmodulin transcript, an antifreeze glycoprotein/trypsinogen-like protease gene and to the mRNA of a key component of the super elongation complex. Selective pressures acting on specific loci might reflect past evolutionary processes leading to species divergence and local adaptation. The extent and timing of interspecific gene exchange was also considered to clarify the role of glacial cycles in promoting the divergence and the introgression of the Chionodraco species. We found evidences of past and present introgression: several individuals in each species showed mixed ancestry; evolutionary scenarios excluding hybridization or including it only in ancient times had small or zero posterior probabilities; data supported a scenario of interspecific gene flow associated with the two most recent interglacial periods. These findings may indicate an increased opportunity for speciation in allopatric refugia during glacial periods, followed by secondary contacts and hybridization during warmer intervals. With regard to P. antarcticum, we investigated its population genetic structure along the Antarctic Peninsula (AP), a region highly impacted by regional warming. We found a single gene pool and absence of inter-annual variability in the south-western AP, while significant differences were detected on a geographic scale from samples collected off the tip of the AP, with a signal of increased fragmentation over time. The reduced level of gene flow along the shelf, the increase of differentiation through time, and the inability to capture P. antarcticum in the central-western AP for two consecutive years, all suggest that this sea ice dependent species has been affected by climate change with possible cascading effects on the Antarctic marine food web.I nototenioidei antartici si sono evoluti per milioni di anni nelle acque gelide che caratterizzano l’Oceano Meridionale; essi presentano una vasta gamma di adattamenti per resistere al freddo e ora dominano la fauna ittica antartica sia per numero di specie che per biomassa. Per la loro estrema stenotermia, questi pesci potrebbero essere fortemente vulnerabili ai cambiamenti climatici con possibili effetti a cascata sull’intero ecosistema marino antartico. Pertanto, è di fondamentale importanza investigare le basi genetiche e genomiche dell’adattamento al freddo, analizzare i processi di differenziamento derivanti dai cambiamenti climatici del passato e attuali e, allo stesso tempo, indagare il livello di variabilità e di differenziamento genetico presente a livello di specie e di popolazione. In questo dottorato sono state prese in considerazione quattro specie di nototenioidei antartici: le tre specie di derivazione recente appartenenti al genere Chionodraco, Chionodraco hamatus, Chionodraco rastrospinosus e Chionodraco myersi, e Pleuragramma antarcticum. Il genere Chionodraco appartiene alla famiglia Channichthyidae (icefish), unica tra i vertebrati per l’assenza di emoglobina e l’incapacità di esprimere mioglobina nel muscolo scheletrico. Un adeguato rifornimento di ossigeno ai tessuti è permesso da un marcato rimodellamento del sistema cardio-vascolare e da un’elevata densità mitocondriale a livello muscolare. P. antarcticum (Nototheniidae) è l'unico nototenioideo caratterizzato da un ciclo vitale completamente pelagico, è dipendente dal ghiaccio marino e svolge un ruolo chiave nella catena trofica dell’ecosistema marino antartico. Le analisi svolte in questo dottorato possono essere raggruppate in due principali linee di ricerca: 1) l'approfondimento della conoscenza sulle basi genetiche e genomiche dell’adattamento al freddo degli icefish; 2) l'analisi del pattern di differenziamento genetico presente a livello intra- e inter-specifico, con particolare enfasi su come le condizioni ambientali del passato e del presente abbiano plasmato e stiano influenzando la struttura genetica delle specie. Per quanto riguarda la prima linea di ricerca, è stato ricostruito e annotato il primo trascrittoma normalizzato del muscolo scheletrico di C. hamatus e l’informazione di sequenza così ottenuta è stata utilizzata per verificare l'ipotesi di duplicazione di geni coinvolti nella funzione mitocondriale. Utilizzando una pipeline bioinformatica sviluppata ad hoc, sono stati identificati 124 geni duplicati specifici del lineage di C. hamatus. La proporzione di duplicazioni lineage-specifiche identificate in C. hamatus è risultata significativamente maggiore a quella presente in specie modello di pesci teleostei. Un’analisi di arricchimento funzionale ha mostrato come l’insieme dei geni duplicati in C. hamatus fosse significativamente arricchito in proteine con localizzazione mitocondriale, coinvolte nella funzione e nella biogenesi mitocondriale. La presenza di elevate densità mitocondriali e il mantenimento a livello genomico di geni duplicati con funzione mitocondriale potrebbero conferire un vantaggio selettivo agli icefish in un ambiente freddo e in assenza di proteine di trasporto per l’ossigeno, migliorando la diffusione dell’ossigeno e la produzione di energia nei tessuti aerobici. Per quanto riguarda la seconda linea di ricerca, è stato studiato il pattern di differenziamento genetico presente a livello intra- e inter-specifico nel genere Chionodraco. E’ stata rilevata omogeneità intraspecifica, ma la presenza di tre pool genici distinti corrispondenti alle tre specie. Sono stati ricercati putativi loci outlier, in grado di rilevare un elevato livello di differenziamento genetico tra specie. Sono stati identificati tre loci, probabilmente soggetti a selezione naturale, con similarità di sequenza per la calmodulina, per una proteasi antifreeze glycoprotein/trypsinogen-like e per un componente fondamentale del super elongation complex. Pressioni selettive, agenti su loci specifici, potrebbero riflettere processi evolutivi del passato che hanno portato alla divergenza tra specie e all’adattamento locale. È stata inoltre investigata la presenza e l’entità del flusso genico, passato e presente, tra le tre specie del genere Chionodraco, anche per chiarire il ruolo dei cicli glaciali nel processo di divergenza e d’introgressione tra specie. Sono state rilevate molteplici evidenze d’introgressione, associata ai due periodi interglaciali più recenti (Eemiano e Olocene), che potrebbe indicare una maggiore opportunità di speciazione allopatrica in rifugi durante i periodi glaciali, seguita da contatti secondari e ibridazione durante gli intervalli più caldi. Nella specie P. antarcticum, è stata studiata la struttura genetica di popolazione a livello della Penisola Antartica, una regione molto influenzata dal surriscaldamento climatico. Lungo la costa sud-occidentale della penisola è stato rilevato un pool genico unico e assenza di variabilità su scala temporale. Differenze significative sono state evidenziate, invece, su scala geografica tra campioni raccolti nella regione sud-occidentale e quelli ottenuti dalla punta settentrionale della penisola, con un segnale di incremento del differenziamento nel tempo. Molteplici evidenze, quali il ridotto livello di flusso genico lungo la piattaforma continentale della penisola, l'aumento del differenziamento su scala temporale e l'incapacità di catturare P. antarcticum lungo la costa centro-occidentale per due anni consecutivi, suggeriscono che questa specie, dipendente dal ghiaccio marino, sia stata colpita dai cambiamenti climatici con possibili effetti a cascata sull’intera catena alimentare dell’ecosistema marino antartico

Geomorfologia applicata alla pianificazione di aree dell'Appennino settentrionale

Dottorato di ricerca in scienze della terra. 11. ciclo. A.a. 1998-1999. Coordinatore Gian Battista Vai. Tutore Enzo FarebegoliConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal