Investigation of shallow marine Antarctic environments using the annual increment growth pattern of the bivalve mollusc Aequiyoldia eightsii (Jay, 1839).

The research presented here constitutes the latest advances in the use of the Antarctic bivalve mollusc Aequiyoldia eightsii as a sclerochronological proxy for Antarctic coastal waters. A. eightsii has the potential to provide annually-resolved records for the Antarctic shallow waters beyond the beginning of the instrumental record. A comprehensive study of A. eightsii shell growth was carried out, which highlighted two ontogenetic trends: i) negative exponential and ii) a quasi-cyclic trend of a period of nine years, which may relate to allocation of energetic resources. Using crossmatching techniques, four chronologies from adjacent locations near Rothera Station (West Antarctic Peninsula, WAP) and an additional chronology from historical samples collected near Signy Station (South Orkney Islands, SOIs) were developed. Additionally further work on a pre-existing chronology from the SOIs is presented. Instrumental records and climatic indices were analysed to determine environmental variability and the factors controlling shell growth. Seawater temperature and fast-ice duration seem to be the main environmental drivers of A. eightsii shell growth. Shell growth of South Cove (WAP) specimens seem to better reflect to environmental conditions recorded in the Rothera Biological Time Series. Stable oxygen and carbon isotope (δ18O and δ13C) records were developed from shell carbonate material; these showed sub- and inter-annual variability and all specimens showed similar trends in δ18Oshell and δ13Cshell, with the exception of a deep-collected specimen of the SOIs, which showed much reduced interannual variability and a stronger δ13Cshell negative trend with ontogenetic age. Additionally, stable isotope fractionation depending anatomical part of the shell (anterior, ventral and posterior) was studied, which showed intra-increment variability in δ18Oshell and δ13Cshell. The present work constitutes a comprehensive calibration of A. eightsii as a sclerochronological proxy for Antarctic shallow coastal waters, which will help to expand our understanding of climate trends in the region

Impacto de un incremento de la capacidad de generación de energía a partir de biomasa en plantas de co-generación en Andalucía

The paper estimates the regional economic impact of renewable energy development (inv) based on the use of biomass. The regional level is Andalusia. The analysis is carried out under the assumption that achieves the goal of renewable energy development set in Andalusian Sustainable Energy Plan (PASENER) 2007-2013. To estimate the economic impact, a General Equilibrium Model (CGE) is used based on the Social Accounting Matrix (SAM) updated for Andalusia in 2008. The results show that if the goal of PASENER is met, there might be an increase production of 4.02%.Agricultural and Food Policy, Environmental Economics and Policy, Land Economics/Use, C68, Q43,

Chemical characterization of a hypoglycemic extract from Cucurbita ficifolia bouche that induces liver glycogen accumulation in diabetic mice

Background: The aqueous extract of Cucurbita ficifolia (C. ficifolia) fruit has demonstrated hypoglycemic effect, which may be attributed to some components in the extract. However, the major secondary metabolites in this fruit have not yet been identified and little is known about its extra-pancreatic action, in particular, on liver carbohydrate metabolism. Therefore, in addition to the isolation and structural elucidation of the principal components in the aqueous extract of C. ficifolia, the aim of this study was to determine whether or not the hypoglycemic effect of the aqueous extract of Cucurbita ficifolia (C. ficifolia) fruit is due to accumulation of liver glycogen in diabetic mice.Materials and Methods: The aqueous extract from fruit of C. ficifolia was fractionated and its main secondary metabolites were purified and chemically characterized (NMR and GC-MS). Alloxan-induced diabetic mice received daily by gavage the aqueous extract (30 days). The liver glycogen content was quantified by spectroscopic method and by PAS stain; ALT and AST by spectrometric method; glycogen synthase, glycogen phosphorylase and GLUT2 by Western blot; the mRNA expression of GLUT2 and glucagon-receptor by RT-PCR; while serum insulin was quantified by ELISA method. A liver histological analysis was also performed by H&E stain.Results: Chemical fingerprint showed five majoritarian compounds in the aqueous extract of C. ficifolia: p-coumaric acid, p-hydroxybenzoic acid, salicin, stigmast-7,2,2-dien-3-ol and stigmast-7-en-3-ol. The histological analysis showed accumulation of liver glycogen. Also, increased glycogen synthase and decreased glycogen phosphorylase were observed. Interestingly, the histological architecture evidenced a liver-protective effect due the extract.Conclusion: Five compounds were identified in C. ficifolia aqueous extract. The hypoglycemic effect of this extract may be partially explained by liver glycogen accumulation. The bioactive compound responsible for the hypoglycemic effect of this extract will be elucidated in subsequent studies.Keywords: Cucurbita ficifolia, Cucurbitaceae, liver glycogen, hypoglycemic plants, p-coumaric acid, salicin, p-hydroxybenzoic aci

Gene flow in the Antarctic bivalve Aequiyoldia eightsii (Jay, 1839) suggests a role for the Antarctic Peninsula Coastal Current in larval dispersal

The Antarctic Circumpolar Current (ACC) dominates the open-ocean circulation of the Southern Ocean, and both isolates and connects the Southern Ocean biodiversity. However, the impact on biological processes of other Southern Ocean currents is less clear. Adjacent to the West Antarctic Peninsula (WAP), the ACC flows offshore in a northeastward direction, whereas the Antarctic Peninsula Coastal Current (APCC) follows a complex circulation pattern along the coast, with topographically influenced deflections depending on the area. Using genomic data, we estimated genetic structure and migration rates between populations of the benthic bivalve Aequiyoldia eightsii from the shallows of southern South America and the WAP to test the role of the ACC and the APCC in its dispersal. We found strong genetic structure across the ACC (between southern South America and Antarctica) and moderate structure between populations of the WAP. Migration rates along the WAP were consistent with the APCC being important for species dispersal. Along with supporting current knowledge about ocean circulation models at the WAP, migration from the tip of the Antarctic Peninsula to the Bellingshausen Sea highlights the complexities of Southern Ocean circulation. This study provides novel biological evidence of a role of the APCC as a driver of species dispersal and highlights the power of genomic data for aiding in the understanding of the influence of complex oceanographic processes in shaping the population structure of marine species

La configuración capitalista de paisajes turísticos

Diversos estudios de caso en diferentes lugares de México relacionados con la generación de algunos procesos particulares. aporte clave para entender la recomposición del mundo rural mexicano, pero también latinoamericano, bajo la dinámica de un nuevo ciclo de acumulación que está transformando sus dinámicas territoriales y sus paisajes. Entender bien lo anterior es fundamental para poder acompañar los anhelos y luchas por otro mundo rural.Aportación para entender el proceso de penetración de una de las vías de acumulación en los territorios rurales. Reúne una serie de materiales teóricos de un alcance más que notable para comprender los procesos de transformación de los territorios rurales bajo el dominio de los capitales turísticos

Genetic variation in a small bivalve along a retreating glacier fjord, King George Island, Antarctica.

Climate change is strongly influencing regions of Antarctica but the consequences on microevolutionary processes have been little studied. Patterns of population genetic diversity were analysed in the Antarctic bivalve Nuculana inaequisculpta (Protobranchia: Nuculanidae) from a fjord with 70 years of documented climate-forced glacier retreat. Thirty-nine individuals from five sites at different distances from the glacier terminus were collected, and the COI gene was sequenced from each individual. No statistically significant genetic differentiation was found between sites nor a significant correlation between the proximity of glaciers and genetic diversity, suggesting a high dispersal capability and therefore, a planktonic larval stage for this species. Nevertheless, we encourage increasing the sample size and number of loci in future studies to confirm our findings

Consenso sobre definición de criterios diagnósticos, terapéuticos y de seguimiento de la acromegalia en pacientes colombianos

Contexto: la acromegalia es una enfermedad rara en la población general y habitualmente tiene una evolución clínica insidiosa, lo cual genera un reto para diagnosticar al paciente a partir de la sospecha clínica y posterior confirmación con las ayudas diagnósticas. La mayoría de pacientes con acromegalia tienen como origen de la enfermedad un tumor hipofisario secretor de hormona del crecimiento y en consecuencia el tratamiento debe estar dirigido a lograr el control bioquímico y la reducción de la masa tumoral. Finalmente, el seguimiento del paciente resulta clave para lograr el control de la enfermedad y detectar las comorbilidades asociadas. Objetivo: definir criterios para el diagnóstico, tratamiento y seguimiento de la acromegalia en pacientes colombianos. Materiales y métodos: se realizó un consenso tipo Delphi modificado. Participaron 10 expertos en el manejo del paciente con acromegalia (endocrinólogos y neurocirujanos) y un grupo desarrollador. Los resultados fueron analizados y discutidos. A partir de este ejercicio, se presentaron las recomendaciones en los diferentes apartados. Resultados: se obtuvieron recomendaciones acerca del seguimiento al paciente colombiano con acromegalia y el abordaje del paciente desde el sistema de salud local, la sospecha clínica, el diagnóstico bioquímico e imagenológico, el tratamiento mediante intervención quirúrgica, el tratamiento farmacológico y la radioterapia. Conclusiones: en Colombia es importante el fortalecimiento del conocimiento médico desde la atención primaria hasta el especialista en el correcto diagnóstico, manejo y seguimiento del paciente con acromegalia para lograr la detección temprana de la enfermedad y disminuir la progresión de las comorbilidades asociadas

CHEMICAL CHARACTERIZATION OF A HYPOGLYCEMIC EXTRACT FROM CUCURBITA FICIFOLIA BOUCHE THAT INDUCES LIVER GLYCOGEN ACCUMULATION IN DIABETIC MICE.

Background: The aqueous extract of Cucurbita ficifolia (C. ficifolia) fruit has demonstrated hypoglycemic effect, which may be attributed to some components in the extract. However, the major secondary metabolites in this fruit have not yet been identified and little is known about its extra-pancreatic action, in particular, on liver carbohydrate metabolism. Therefore, in addition to the isolation and structural elucidation of the principal components in the aqueous extract of C. ficifolia, the aim of this study was to determine whether or not the hypoglycemic effect of the aqueous extract of Cucurbita ficifolia (C. ficifolia) fruit is due to accumulation of liver glycogen in diabetic mice. Materials and Methods: The aqueous extract from fruit of C. ficifolia was fractionated and its main secondary metabolites were purified and chemically characterized (NMR and GC-MS). Alloxan-induced diabetic mice received daily by gavage the aqueous extract (30 days). The liver glycogen content was quantified by spectroscopic method and by PAS stain; ALT and AST by spectrometric method; glycogen synthase, glycogen phosphorylase and GLUT2 by Western blot; the mRNA expression of GLUT2 and glucagon-receptor by RT-PCR; while serum insulin was quantified by ELISA method. A liver histological analysis was also performed by H&E stain. Results: Chemical fingerprint showed five majoritarian compounds in the aqueous extract of C. ficifolia: p-coumaric acid, p-hydroxybenzoic acid, salicin, stigmast-7,2,2-dien-3-ol and stigmast-7-en-3-ol. The histological analysis showed accumulation of liver glycogen. Also, increased glycogen synthase and decreased glycogen phosphorylase were observed. Interestingly, the histological architecture evidenced a liver-protective effect due the extract. Conclusion: Five compounds were identified in C. ficifolia aqueous extract. The hypoglycemic effect of this extract may be partially explained by liver glycogen accumulation. The bioactive compound responsible for the hypoglycemic effect of this extract will be elucidated in subsequent studies