Amazonian White-Sand Forests Show Strong Floristic Links with Surrounding Oligotrophic Habitats and the Guiana Shield

Recognizing and understanding historical patterns and processes that have influenced the diversification of organisms on earth is one of the central goals of evolutionary biology. Within this broad area, studies within the disciplines of molecular systematics (i.e. phylogeography, phylogenetics and population genetics), allow us to address evolutionary questions from different biological, spatial and temporal scales. Phylogeography and molecular phylogenetics help us to understand aspects related to events that have given rise to patterns of genetic variation in organisms, as well as to understand the assembly of biological communities in a given area. These types of studies provide crucial information to increase knowledge about the biodiversity of little-studied ecoregions. One such ecoregion is Colombian Guyana. This ecoregion, which is located between three putative centers of speciation; Amazonia, the Andes and Guyana, is one of the least explored areas of the country. As a result of their geological composition, the western enclaves of the Guiana Shield have been described as a "heterogeneous entity", composed of savannas, catingas, lowland forests, and even white sand forests. Using bats as a biological study group, this paper presents two approaches focused on understanding how biogeographic events that have shaped the diversity of the continent have affected different lineages that inhabit Colombian Guiana. Bats are a group of vertebrates sensitive to biogeographic events that have shaped the diversity of the continent, which play different functional roles in the ecosystems they inhabit. High degrees of association with habitat have been described for numerous bat species, mainly in terms of foraging characteristics and diet types. In a first project, we comparatively analyzed the phylogeographic patterns of three widely distributed bat species, with the aim of identifying the patterns of genetic divergence of the bats that inhabit the area today. Using mitochondrial DNA sequences, we revealed the existence of bat populations established in the area, which showed different degrees of gene flow with surrounding biogeographic areas, especially with the Guiana provinces of Oriente and Pantepui and the Amazon. Additionally, we identified different demographic histories for each species, which were probably influenced to different extents by climatic changes during the Pleistocene and differential ecological characteristics. Our results highlight the influence of Colombian Guiana ecosystems on the formation and spatial configuration of bat diversity and genetic structure, and the importance of these ecosystems for bat conservation. In a second project, from a phylogenetic perspective, we evaluated the phylogenetic structure of bat communities inhabiting different eco-regions of northern South America, using mitochondrial and nuclear DNA sequences. The results of the analysis allowed us to demonstrate that the bat populations of the Western Guayana Province (which includes the Colombian portion of the Guiana Shield), are phylogenetically clustered, that is, the species that compose the communities are evolutionarily closer than expected by chance. We conclude that factors such as the high heterogeneity of habitats in the region, the high diversity of fruit bats in the sampled communities, and interspecific competition have shaped the species composition of the communities in this area. In a final chapter, a general discussion of the results obtained from the two research projects carried out is developed. Chapters one and two of this thesis will be submitted to international indexed journals, which is why they are written in English and in scientific article format.Reconocer y entender patrones y procesos históricos que han influenciado la diversificación de los organismos sobre la tierra, es uno de los objetivos centrales de la biología evolutiva. Dentro de esta gran área, estudios enmarcados en las disciplinas de la sistemática molecular (i.e. filogeografía, filogenética y genética de poblaciones), nos permiten abordar preguntas evolutivas desde diferentes escalas biológicas, espaciales y temporales. La filogeografía y la filogenética molecular nos ayudan a entender aspectos relacionados con eventos que han dado lugar a patrones de variación genética de los organismos, así como entender el ensamblaje de comunidades biológicas en un área determinada. Este tipo de estudios aportan información crucial para aumentar el conocimiento acerca de biodiversidad de eco regiones poco estudiadas. Una de estas eco regiones es la Guyana colombiana. Esta eco región, la cual se encuentra ubicada entre tres centros putativos de especiación; Amazonía, Andes y Guayana, es una de las zonas menos exploradas del país. Como resultado de su composición geológica, los enclaves occidentales del escudo Guayanés han sido descritos como una "entidad heterogénea", compuesta de sabanas, catingas, bosques bajos, e inclusive bosques de arena blanca. Usando como grupo biológico de estudio los murciélagos, este trabajo de grado presentan dos aproximaciones enfocadas a entender como eventos biogeográficos que han moldeado la diversidad del continente, han afectado diferentes linajes que habitan la Guayana colombiana. Los murciélagos son un grupo de vertebrados sensibles a los eventos biogeográficos que han moldeado la diversidad del continente, el cuál cumple diferentes roles funcionales en los ecosistemas que habitan. Altos grados de asociación con el hábitat han sido descritos para numerosas especies de murciélagos, principalmente en cuanto a características de forrajeo y tipos de dieta. En un primer proyecto, analizamos comparativamente los patrones filogeográficos de tres especies de murciélagos de amplia distribución, con el objetivo de identificar los patrones de divergencia genética de los murciélagos que habitan el área en la actualidad. Utilizando secuencias de ADN mitocondrial, revelamos la existencia de poblaciones de murciélagos establecidas en el área, las cuales mostraron diferentes grados de flujo genético con áreas biogeográficas circundantes, en especial con las provincias guayanesas del Oriente y Pantepui y el Amazonas. Adicionalmente identificamos diferentes historias demográficas para cada especie, las cuales probablemente fueron influenciadas en diferente medida por cambios climáticos durante el pleistoceno y características ecológicas diferenciales. Nuestros resultados destacan la influencia de los ecosistemas guayaneses colombianos en la formación y configuración espacial de la diversidad y estructura genética en murciélagos, y la importancia de estos ecosistemas para la conservación dicha diversidad. En un segundo proyecto, desde una perspectiva filogenética, evaluamos la estructura filogenética de la comunidad de murciélagos de diferentes eco-regiones del norte de sur américa, usando secuencia de ADN mitocondrial. Los resultados de los análisis nos permitieron demostrar que las poblaciones de murciélagos de la Provincia Guayanesa del Occidente (la cual incluye la porción colombiana del escudo guayanés), se encuentran filogenéticamente agregadas, es decir, las especies que componen las comunidades son más cercanas evolutivamente de lo esperado por el azar. Concluimos que factores como la alta heterogeneidad de hábitats en la región, la alta diversidad de murciélagos frugívoros en las comunidades muestreadas, y la competencia interespecífica han moldeado la composición de especies de las comunidades en esta zona. En un capítulo final, se desarrolla una discusión general de los resultados obtenidos de los dos proyectos de investigación realizados. Los capítulos uno y dos de esta tesis serán sometidos a revistas indexadas internacionales, razón por la cual están escritos en idioma inglés y en formato de artículo científico.Línea de Investigación: Biología EvolutivaMaestrí

Potential Use of Mango Waste and Microalgae Spirulina sp. for Bioelectricity Generation

Potential use of organic waste and microalgae generates bioelectricity and thereby reduces harmful effects on the environment. These residues are used due to their high content of electron-generating microorganisms. However, so far, they have not been used simultaneously. Therefore, this research uses mango waste and microalgae Spirulina sp. in double-chamber microbial fuel cells to generate bioelectricity. The cells were made at a laboratory scale using zinc and copper electrodes, achieving a maximum current and voltage of 7.5948 ± 0.3109 mA and 0.84546 ± 0.314 V, with maximum electrical conductivity of the substrate being 157.712 ± 4.56 mS/cm and an optimum operating pH being 5.016 ± 0.086. The cells showed a low internal resistance of approximately 205.056 ± 25 Ω, and a maximum power density of 657.958 ± 21.114 mW/cm2 at a current density of 4.484 A/cm2. This research provides an excellent opportunity for mango farmers and exporting and importing companies because they can use their own waste to reduce their electricity costs when this prototype is brought to a large scale

Evidencia de citrato de sildenafilo en formulaciones herbolarias afrodisíacas comercializadas en San Salvador, El Salvador, por metodología HPLC-DAD y RMN 1H

Introduction: Herbal products have been used for the treatment of many diseases and unlike conventional drugs, they are perceived as safe and harmless due to their natural origin. The adulteration of natural products used for the improvement of sexual desire is becoming recurrent nowadays. Objective: This study detects the presence and determines the pharmacological dose of sildenafil citrate, a phosphodiesterase-5 inhibitor, in presumed adulterated natural products, that are commercialized in markets and “sex-shops” type store as stimulants of sexual desire in men. Methodology: The sildenafil content in 21 herbal products was identified and determined, using chromatographic and spectroscopic techniques (CCF, HPLC-DAD, and NMR 1H). Results: There was not evidence of the presence of sildenafil in the evaluated products from the markets. However, in the sex-shop type sales, with high probabilities of acquisition of adulterated products with this active principle, concentrations found were in a range from 12.7-132.2 mg/capsule. Representing lower, intermedium and higher doses than those recommended by the FDA. Conclusion: For consumers of fraudulent herbal products, there may be an interaction of sildenafil with vasodilator medicines such as nitrates, used for angina pectoris, and congestive heart failure. These interactions, together with the adverse cardiac-type (hypotensive) effects of sildenafil, could have serious effect on the health of consumers. Strict regulation of the natural products industry in sampled sites is urgedIntroducción: Los productos herbolarios han sido utilizados para el tratamiento de muchas enfermedades y a diferencia de los fármacos convencionales, se perciben seguros e inofensivos debido a su origen natural. La adulteración de productos naturales usados para la mejora del deseo sexual, se está volviendo recurrente en la actualidad. Objetivo: En este estudio se detecta la presencia y determina la dosis farmacológica de citrato de sildenafilo, un inhibidor de la fosfodiesterasa-5, en productos naturales, presuntamente adulterados, que se comercializan en mercados y tiendas tipo “sex-shop” como estimulantes del deseo sexual en hombres. Metodología: Se identifica y determina el contenido de sildenafilo en 21 productos herbolarios, a través de técnicas cromatográficas y espectroscópicas (CCF, HPLC-DAD y RMN 1H). Resultados: No existen evidencias de la presencia de sildenafilo en los productos evaluados procedentes de mercados, sin embargo, en las ventas tipo sex-shop, con altas probabilidades de adquisición de productos adulterados con este principio activo, se encontraron concentraciones que oscilan entre 12.7-132.2 mg/cápsula, dosis inferiores, próximas y superiores a las recomendadas por la FDA. Conclusión: Para los consumidores de productos herbolarios fraudulentos puede existir una interacción del sildenafilo con medicamentos vasodilatadores tipo nitratos, utilizados para la angina de pecho y la insuficiencia cardíaca congestiva. Estas interacciones aunado a los efectos adversos de tipo cardíaco (hipotensor) del sildenafilo en sí mismo, podría ser muy grave para la salud de los consumidores. Se insta a una estricta regulación de la industria de productos naturales en zonas muestreada

Outlier SNPs enable food traceability of the southern rock lobster, Jasus edwardsii

Recent advances in next-generation sequencing have enhanced the resolution of population genetic studies of non-model organisms through increased marker generation and sample throughput. Using double digest restriction site-associated DNA sequencing (ddRADseq), we investigated the population structure of the commercially important southern rock lobster, Jasus edwardsii, in Australia and New Zealand with the aim of identifying a panel of SNP markers that could be used to trace country of origin. Four ddRADseq libraries comprising a total of 88 individuals were sequenced on the Illumina MiSeq platform, and demultiplexed reads were used to create a reference catalog of loci. Individual reads were then mapped to the reference catalog, and variant calling was performed. We have characterized two single-nucleotide polymorphism (SNP) panels comprised in total of 656 SNPs. The first panel contained 535 neutral SNPs and the second, 121 outlier SNPs that were characteristic of being putatively under selection. Both neutral and outlier SNP panels showed significant differentiation between the two countries, with the outlier loci demonstrating much larger F(ST) values (F(ST) outlier SNP panel = 0.134, P < 0.0001; F(ST) neutral SNP panel = 0.022, P < 0.0001). Assignment tests performed with the outlier SNP panel allocated 100 % of the individuals to country of origin, demonstrating the usefulness of these markers for food traceability of J. edwardsii

Vasoactive agents for the management of acute variceal bleeding: A systematic review and meta-analysis

Background & Aims: Vasoactive agents with endoscopic therapy are used to treat acute variceal bleeding (AVB). There are two main groups of vasoactive agents: terlipressin and vasopressin (T-V), and octreotide and somatostatin (O-S). However, the benefit/harm balance is unclear. Our aim was to assess the efficacy and safety of T-V versus O-S for the management of AVB. Methods: We performed a systematic search for randomized controlled trials (RCTs) in PubMed, Scopus, and CENTRAL. Our main outcomes were mortality and adverse events. Secondary outcomes were bleeding control, rebleeding, blood transfusion, hospital stay. We evaluated the certainty of evidence using GRADE methodology. Results: We included 21 RCTs. The risk of mortality (RR: 1.01; 95%CI: 0.83-1.22), bleeding control (RR: 0.96; 95%CI: 0.91-1.02; I2=53%), early rebleeding (RR: 0.91; 95%CI: 0.66-1.24: I2=0%), late rebleeding (RR: 0.94; 95 CI: 0.56-1.60; I2=0%), blood transfusion (MD: 0.04; 95%CI:-0.31-0.39; I2=68%) and hospital stay (MD:-1.06; 95%CI:-2.80-0.69; I2=0%) were similar between T-V and O-S groups. Only 15 studies reported adverse events, which were significantly higher in the T-V compared to the O-S group (RR 2.39; 95%CI: 1.58-3.63; I2=57%). The certainty of evidence was moderate for the main outcomes, and low or very low for others. Conclusions: In cirrhotic patients with AVB, those treated with T-V had similar mortality risk compared to O-S. However, the use of T-V showed an increased risk of adverse events compared to O-S.Revisión por pare

Reducing adverse impacts of Amazon hydropower expansion

Proposed hydropower dams at more than 350 sites throughout the Amazon require strategic evaluation of trade-offs between the numerous ecosystem services provided by Earth\u27s largest and most biodiverse river basin. These services are spatially variable, hence collective impacts of newly built dams depend strongly on their configuration. We use multiobjective optimization to identify portfolios of sites that simultaneously minimize impacts on river flow, river connectivity, sediment transport, fish diversity, and greenhouse gas emissions while achieving energy production goals. We find that uncoordinated, dam-by-dam hydropower expansion has resulted in forgone ecosystem service benefits. Minimizing further damage from hydropower development requires considering diverse environmental impacts across the entire basin, as well as cooperation among Amazonian nations. Our findings offer a transferable model for the evaluation of hydropower expansion in transboundary basins