Repositorio Digital Ikiam (Univ. Regional Amazónica)
Not a member yet
850 research outputs found
Sort by
Survival on a semi-arid island: submersion and desiccation tolerances of fiddler crabs from the Galapagos Archipelago
Get PDFDuring tidal cycles, semi-terrestrial fiddler crabs are subject to alternating periods of submersion and desiccation. Here, we compare physiological and biochemical adjustments to forced submersion and desiccation in two fiddler crabs from the Galapagos archipelago: the indigenous Leptuca helleri, and Minuca galapagensis. We examine ecological distributions and habitat characteristics using transect analysis; survival after 6 h forced submersion at different salinities (0, 21 and 42 ‰S), and after 6 or 12 h desiccation challenge, including alterations in hemolymph osmolality; and, oxidative stress responses in the gills and hepatopancreas, accompanying glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) activities, and lipid peroxidase (LPO). We provide an integrated biomarker response (IBR) index for each species based on oxidative stress in each tissue and condition. Our transect study revealed that L. helleri occupies an intertidal niche while M. galapagensis is supralittoral, L. helleri being less resistant to submersion and desiccation. After 6 h submersion, L. helleri survived only at 21 ‰S while M. galapagensis survived at all salinities. Hemolymph osmolality decreased at 0 ‰S in M. galapagensis. After 6 h desiccation, osmolality decreased markedly in L. helleri but increased in M. galapagensis. Enzyme assays were not performed in L. helleri owing to high mortality on submersion/desiccation challenge. After submersion in M. galapagensis, hepatopancreas GPx activities decreased in 0 and 21 ‰S while GR activity was strongly inhibited at all salinities. Gill LPO decreased in 42 ‰S. On desiccation in L. helleri, GPx activity was inhibited in the hepatopancreas but increased in the gills. GST activity increased while LPO decreased in both tissues. After desiccation in M. galapagensis, hepatopancreas GPx activity increased. Both hepatopancreas and gill GST and GR activities and LPO were strongly inhibited. The IBR indexes for L. helleri were highest in fresh caught crabs, driven by gill and hepatopancreas LPO. For M. galapagensis, submersion at 21 ‰S contributed most to IBR, LPO in both tissues responding markedly. Leptuca helleri appears to be a habitat specialist adapted to a narrow set of niche dimensions while M. galapagensis survives over a much wider range, exhibiting little oxidative stress. The species’ physiological flexibilities and limitations provide insights into how fiddler crabs might respond to global environmental change on semi-arid islands
Dinámicas espaciales de la minería de oro y sus efectos sobre la pérdida de los bosques tropicales y afectaciones en los recursos hídricos, aplicando sensores remotos: caso de la cuenca alta del Río Napo, Amazonía, Ecuador.
Get PDFGold mining (GM) impacts are devastating, including landscape change and deforestation,
loss of ecosystem services and native species, contribution of carbon emission and
sediment loads, reduced water quality, and soil and air contamination. The rapid increase
in this activity across the Amazon basin, the scarcity of studies, the difficult detection of
impacts and monitoring require integrated techniques that can assess the impact of GM
on this important ecosystem. Google Earth Engine (GEE) is a useful tool for evaluating
anthropic activities incidence on the dynamics of planetary coverage. Thus, this study
seeks to use a remote sensing technique in GEE to assess land cover and land use changes
dynamics and impacts derived from GM activity over a 6-year period in the Ecuadorian
Amazon and to associate them with quality auxiliary data water and metal contamination
in water and sediment to understand the degree of contamination and its risks to
environmental health. GM doubled its extent from 0.15% (651 ha) to 0.30% (1317 ha) of
the total study area, degrading mainly forested areas and leaving heterogeneous
landscapes covered by grassy or bare soils. The combination of GM area change
indicators with environmental quality data has made it possible to assess the mining
activity impact in an integrative way in 9 GM sites, showing that sites with rapid increase
of its extent and landscape degradation have a direct effect on metal contamination in
water and physicochemical parameters, while places with lower increase have a higher
occurrence of metals in sediments and a greater change in its location than in its
extension
Preliminary Assessment of Plastic Litter and Microplastic Contamination in Freshwater Depositional Areas: The Case Study of Puerto Misahualli, Ecuadorian Amazonia
Get PDFWe quantify plastic litter (PL, > 2 cm) and microplastics (MP, < 5 mm) from the sediments of a beach formed at a riverine depositional area, at the upper Amazon River basin, Ecuador. In the collection area (4400 m2), the PL density was 0.045 items m−2, where low-density polyethylene bags were the prevalent PL. The beach was classified as “very clean” (Clean Coast Index (CCI) of 1.3 items m−2). Regarding MP, in 55 sampling stations, average MP concentrations ranged from 0 to 2200 items kg−1 of dry sediment (0.5–2 mm), and 0–4200 items kg−1 of dry sediment (2–5 mm). Blue fibers were the prevalent MP. Our results represent the first report to show the ubiquitous presence of PL and MP for the area. The monitoring and management of plastic disposal in freshwater beaches are necessary, as here we report a small part of an undocumented issue
Genomic benchmarking studies reveal variations of the polyubiquitination domain of the PSD95 protein in Homo neanderthalensis and other primates of the Hominidae family: Possible implications in cognitive functions?
Get PDFModern humans' unique cognitive abilities regarding Neanderthals and other primate's lineages are frequently
attributed to the differences in brain size development and evolution. However, recent studies have established the critical role of genomic and genetic benchmarking in analyzing the cognitive evolution between modern humans and primates, focused mainly on searching for involved genes in neurogenesis. PSD95 protein (named PSD95p) has a key role in modulating synaptic plasticity, learning, and memory skills. Thus, the present study aimed to determine the possible variations of the PSD95 gene between modern humans, Neanderthals, and other hominid primate species using bioinformatics tools. The results showed 14
polymorphisms compared with the contemporary human PSD95 gene, of which 13 were silent mutations, and only one was a non-silent mutation at the nucleotide position 281. Despite polymorphisms found at the nucleotide sequences, the PSD95p of humans and chimpanzees are 100% identical. Likewise, the gorilla and orangutan PSD95p are 100% identical, although a 103-amino acid deletion characterizes them at the N-terminal end (1-103), suggesting that it behaves like a non-functional protein. Interestingly, the single nucleotide polymorphism (SNP) found at position 281 in the Neanderthal PSD95 gene leads
to a change of the E94 to valine V94 in the polyubiquitination domain (PEST) and variation in the three-dimensional structure of PSD95 protein. We prompt that this structural change in the PEST domain could induce a loss of PSD95p function and, therefore, an alteration in synaptic plasticity forms such as long-term potentiation (LTP) and long-term depression (LTD). These findingsopen a possible hypothesis supporting the idea that humans' cognitive evolution after separating our last common ancestor with Neanderthals lineage could have been accompanied by discrete changes in the PSD95p polyubiquitination domai
Multi-taxa colonisation along the foreland of a vanishing equatorial glacier
Get PDFRetreating glaciers, icons of climate change, release new potential habitats for both aquatic and terrestrial organisms. High-elevation species are threatened by tempera-ture increases and the upward migration of lowlands species. Improving our under-standing of successional processes after glacier retreat becomes urgent, especially in the tropics, where glacier shrinkage is particularly fast. We examined the successional pat-terns of aquatic invertebrates, ground beetles, terrestrial plants, soil eukaryotes (algae, invertebrates, plants) in an equatorial glacier foreland (Carihuairazo, Ecuador). Based on both taxonomical identication and eDNA metabarcoding, we analysed the eects of both environmental conditions and age of deglacierization on community composi-tion. Except for algae, diversity increased with time since deglacierization, especially among passive dispersers, suggesting that dispersal was a key driver structuring the glacier foreland succession. Spatial -diversity was mainly attributed to nestedness for aquatic invertebrates, terrestrial plants and soil algae, likely linked to low environmen-tal variability within the studied glacier foreland; and to turnover for soil invertebrates, suggesting competition exclusion at the oldest successional stage. Pioneer communi-ties were dominated by species exhibiting exible feeding strategies and high dispersal ability (mainly transported by wind), probably colonising from lower altitudes, or from the glacier in the case of algae. Overall, glacier foreland colonisation in the trop-ics exhibit common characteristics to higher latitudes. High-elevation species are nev-ertheless threatened, as the imminent extinction of many tropical glaciers will afect species associated to glacier-inuenced habitats but also prevent cold-adapted and hygrophilous species from using these habitats as refuges in a warming world
On the way to systematize habituation: a protocol to minimize the effects of observer presence on wild groups of Leontocebus lagonotus
Get PDFHabituation is used in most field research with primates to minimize observer effects on their behavior. Despite its importance, there is little published on the methods used to habituate different taxa of primates or how these methods vary in different habitat types. We assessed changes in behavior and space use of two groups of Leontocebus lagonotus in the Ecuadorian Amazon in order to document this process. Although the subjects had not been studied before, visitors and researchers were more frequently in the home range of Group 1 than of Group 2. We followed both groups for 2 months, collecting behavioral data through scan sampling and recording the use of space (ground, understory, subcanopy, and canopy) and the routes along which we followed the groups. We then divided our data into two equivalent stages, randomized the data for each stage and looked for significant differences using Wilcoxon tests. Our results show a significant decrease in submissive behaviors toward the observer for both groups and a significant increase in resting and foraging for Group 1. In addition, Group 2 used the subcanopy significantly less and the understory more during the second stage. The routes the animals used were significantly longer in the second stage for Group 1, but not for Group 2. We conclude that our methodology is adequate to advance in the habituation of L. lagonotus in less than 2 months and that a group will habituate more quickly if it has had some previous neutral exposure to humans
Diseño de nuevos agentes antimicrobianos bioinspirados en el péptido Cruzioseptina-1
Get PDFLa resistencia a los antimicrobianos representa una grave amenaza para la salud mundial.
En la última década, los péptidos antimicrobianos emergen como una alternativa para
combatir esta problemática mundial. En este contexto, cruzioseptina 1, un péptido aislado
de C. calcarifer, es considerado como un agente antimicrobiano novedoso por su alta
potencia antimicrobiana en contra de patógenos bacterianos. Sin embargo, este péptido
presenta una actividad hemolítica moderada. Con el objetivo de reducir la toxicidad y
aumentar la potencia, se diseñaron y evaluaron 3 análogos peptídicos basados en
cruzioseptina 1. [K4K15]CZS-1, un análogo con cationicidad aumentada e hidrofobicidad
reducida, presentó un alto efecto antimicrobiano en contra de S. aureus (CIM = 4 mg/L) y
E. coli (CIM = 8 mg/L). Además, indujo menor hemólisis en comparación a cruzioseptina-1.
Adicionalmente, mediante estudios in sílico se propone que la membrana bacteriana es el
blanco terapéutico de [K4K15]CZS-1. Por lo tanto, estos resultados proveen evidencias que
[K4K15]CZS-1 podría ser considerado como una opción prometedora para el desarrollo de
nuevos fármacos antimicrobiano
Rhizobium Diversity Is the Key to Efficient Interplay with Phaseolus vulgaris. Case of Study of Southern Ecuador
Get PDFPlants acquire different combined forms of nitrogen by addition of ammonia and/or nitrate fertilizer or manure to the soil, during organic matter decomposition, by the conversion of nitrogen into different compounds, or by biological nitrogen fixation (BNF). Diverse soil bacteria collectively called rhizobia are capable to fix N2 from the atmosphere through symbiosis with legume plants. The N2 fixed by the legume crops represents a renewable source of nitrogen for agricultural soils, turning symbiotic nitrogen fixation (SNF) in a natural process of significant importance in world agriculture. Within the legumes carrying out this process, common bean (Phaseolus vulgaris L.) constitutes a staple, being the most important grain legume worldwide, especially for developing countries. However, P. vulgaris is a low nitrogen fixer compared with other legumes, mainly attributed to the presence of high but inefficient diversity of indigenous rhizobia in soil, increasing the promiscuity of bean genotypes and lack of response under field conditions. Rhizobia diversity has been extensively studied. Polyphasic taxonomy and recently the average nucleotide identity approach have allowed to discover about 117 so-called Rhizobium species and the real genetic differences of microsymbionts in ecosystems around the world. Nevertheless, phylogenomic, ecological, and population genetic criteria to delineate biologically meaningful species in interplay with their host are still needed. Therefore, understanding genotypic variabilities between bean genotypes and Rhizobium strains contributes to achieve an efficient interaction, increase plant parameters, nitrogen fixation, and yields of common bean. Here, we discuss about the most recent studies on Rhizobium diversity linked to P. vulgaris in the American continent as the center of origin/diversification and outside this continent. The abiotic and biotic factors mediate the efficiency of the interaction, with special emphasis in the promiscuity of common bean as a constraint to achieve high nitrogen fixation rates and we show a case of study at southern Ecuador where genotypic variability among local bean genotypes and native Rhizobium strains was assessed to seek the efficiency of symbiosis based on its diversity
Environmental risk assessment of metal contamination by mining in the Amazon Basin
Get PDFSeveral anthropogenic pressures contribute to the modification of ecosystems and hydrological regimes in the Amazon basin. Among them, mining is of great concern due to the remobilization and emission of potentially toxic elements, such as metals, which have detrimental consequences for the ecosystem and human health. Our study aimed to establish the background metal concentrations for water and sediments and the increase of metal exposure caused by mining in four geochemical regions of the Amazon basin: 1) Western; 2)
Central; 3) Northern and 4) Southern. Furthermore, we evaluated the environmental risk of mining activities to the aquatic ecosystem and the ecological risk assessment in fish populations. A total of 53 studies spanning mined and non-mined areas reporting metal concentrations for As, Hg, Mn, Fe, Cd, Cu, Cr, Pb, Ni, and Zn were reviewed. The mean background metal concentration values were compared with the environmental quality standards thresholds for the protection of aquatic life in sediment (CCME) and water (CCME
and USEPA). Overall, for non-mined areas, all metals are below the established thresholds allowed for the protection of aquatic life in sediments and water, namely, our metal concentration data for reference sites are within international quality standards. The southern peripheral area has the highest levels of background metal concentration in the entire basin for Cd, Cu, Hg, Mn, and Zn. For mining areas, As, Cu, Fe, Hg, Mn, and Pb exceed the mean background metal concentration, and Cd exceeds the threshold TEL in sediment samples, and for water Cd, Cr, Fe, Hg, Mn and, Zn exceed the mean background value, and Fe and Hg exceed
the short-term threshold and Zn exceeds the long-term threshold. Metals with the highest percentages of environmental risk for the basin in the sediment were Pb (67,12 %), As (76,36%), Mn (91,89%), and in water were Fe (83,33 %), Hg (86,26 %), Mn (100 %) and Zn (100 %), since these metals have an increase in the concentration of 10 to 100 times higher concerning the mean background values. Finally, according to the ecological assessment As, Cd, Cu, Hg and Pb show a high risk of metal concentration in Amazonian fish Populations.Tutora: Vellosa Capparelli, Marian
Allylic Hydroxylation Activity Is a Source of Saponin Chemodiversity in the Genus Glycyrrhiza
Get PDFLicorice (Glycyrrhiza) produces glycyrrhizin, a valuable triterpenoid saponin, which exhibits persistent sweetness and broad pharmacological activities. In the genus Glycyrrhiza, three species, Glycyrrhiza uralensis, Glycyrrhiza glabra and Glycyrrhiza inflata, produce glycyrrhizin as their main triterpenoid saponin, which has a ketone group at C-11. Other Glycyrrhiza species produce mainly oleanane-type saponins, which harbor homoannular or heteroannular diene structures that lack the C-11 ketone. Although the glycyrrhizin biosynthetic pathway has been fully elucidated, the pathway involving saponins with diene structures remains unclear. CYP88D6 from G. uralensis is a key enzyme in glycyrrhizin biosynthesis, catalyzing the sequential two-step oxidation of β-amyrin at position C-11 to produce 11-oxo-β-amyrin. In this study, we evaluated the functions of CYP88D6 homologs from the glycyrrhizin-producing species G. glabra and G. inflata and from the non-glycyrrhizin-producing species Glycyrrhiza pallidiflora and Glycyrrhiza macedonica, using yeast engineered to supply β-amyrin as a substrate. Yeast expressing CYP88D6 homologs from glycyrrhizin-producing species produced 11-oxo-β-amyrin. However, yeast expressing CYP88D6 homologs (such as CYP88D15) from the non-glycyrrhizin-producing Glycyrrhiza species accumulated oleana-9(11),12-dien-3β-ol and oleana-11,13(18)-dien-3β-ol; these diene compounds are non-enzymatic or yeast endogenous enzymatic dehydration derivatives of 11α-hydroxy-β-amyrin, a direct reaction product of CYP88D15. These results suggest that the activities of CYP88D6 homologs, particularly their ability to catalyze the second oxidation, could influence glycyrrhizin productivity and diversify the chemical structures of saponins in Glycyrrhiza plants. A synthetic biological approach to engineer CYP88D15 could enable the production of pharmacologically active saponins with diene structures, such as saikosaponins, whose biosynthetic pathways have yet to be fully characterized