Oscar Vivanco-Galvan
@utpl.edu.ec
Facultad de Ciencias Exactas y Naturales.
Universidad Técnica Particular de Loja
EDUCATION
MSc. Conservation Biology and Tropical Ecology
RESEARCH INTERESTS
Microbiology, Vegetal Biotechnology.
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Juan Pablo Suárez, Paulo Herrera, Carolina Kalinhoff, Oscar Vivanco-Galván, and Selvaraj Thangaswamy
Springer Science and Business Media LLC
Abstract Background Artisanal and small-scale gold mining activities are producing contamination with heavy metals and metalloids (HMM) into soils and water worldwide. The HMM are considered as one of the major abiotic stresses due to their long-term persistence in soil. In this context, arbuscular mycorrhizal fungi (AMF) confer resistance to a variety of abiotic plant stressors including HMM. However, little is known regarding the diversity and composition of AMF communities in heavy metal polluted sites in Ecuador. Methods In order to investigate the AMF diversity, root samples and associated soil of six plant species were collected from two sites polluted by heavy metals, located in Zamora-Chinchipe province, Ecuador. The AMF 18S nrDNA genetic region was analyzed and sequenced, and fungal OTUs were defined based on 99% sequence similarity. Results were contrasted with AMF communities from a natural forest and from reforestation sites located in the same province and with available sequences in GenBank. Results The main pollutants in soils were Pb, Zn, Hg, Cd and Cu with concentrations exceeding the soil reference value for agricultural use. Molecular phylogeny and OTU delimitation showed 19 OTUs, the family Glomeraceae was the most OTU-rich followed by Archaeosporaceae, Acaulosporaceae, Ambisporaceae and Paraglomeraceae. Most of the OTUs (11 of 19) have been found at other locations worldwide, 14 OTUs were proven from nearby non-contaminated sites in Zamora-Chinchipe. Conclusion Our study showed that there are no specialized OTUs at the studied HMM polluted sites, but rather generalists adapted to a wide variety of habitats. Their potential role in phytoremediation approaches remains to be investigated.
Yuliana Jiménez-Gaona, Oscar Vivanco-Galván, Darío Cruz, Angelo Armijos-Carrión, and Juan Pablo Suárez
MDPI AG
Background: The delimitation of species of Tulasnella has been extensively studied, mainly at the morphological (sexual and asexual states) and molecular levels—showing ambiguity between them. An integrative species concept that includes characteristics such as molecular, ecology, morphology, and other information is crucial for species delimitation in complex groups such as Tulasnella. Objectives: The aim of this study is to test evolutionary relationships using a combination of alignment-based and alignment-free distance matrices as an alternative molecular tool to traditional methods, and to consider the secondary structures and CBCs from ITS2 (internal transcribed spacer) sequences for species delimitation in Tulasnella. Methodology: Three phylogenetic approaches were plotted: (i) alignment-based, (ii) alignment-free, and (iii) a combination of both distance matrices using the DISTATIS and pvclust libraries from an R package. Finally, the secondary structure consensus was modeled by Mfold, and a CBC analysis was obtained to complement the species delimitation using 4Sale. Results and Conclusions: The phylogenetic tree results showed delimited monophyletic clades in Tulasnella spp., where all 142 Tulasnella sequences were divided into two main clades A and B and assigned to seven species (T. asymmetrica, T. andina, T. eichleriana ECU6, T. eichleriana ECU4 T. pinicola, T. violea), supported by bootstrap values from 72% to 100%. From the 2D secondary structure alignment, three types of consensus models with helices and loops were obtained. Thus, T. albida belongs to type I; T. eichleriana, T. tomaculum, and T. violea belong to type II; and T. asymmetrica, T. andina, T. pinicola, and T. spp. (GER) belong to type III; each type contains four to six domains, with nine CBCs among these that corroborate different species.
Yuliana Jiménez-Gaona, Oscar Vivanco-Galván, Gonzalo Morales-Larreategui, Andrea Cabrera-Bejarano, and Vasudevan Lakshminarayanan
MDPI AG
(1) Background: Cancer is one of the leading causes of death worldwide, and trends in cancer incidence and mortality are increasing over last years in Loja-Ecuador. Cancer treatment is expensive because of social and economic issues which force the patients to look for other alternatives. One such alternative treatment is ivermectin-based antiparasitic, which is commonly used in treating cattle. This paper analyzed ivermectin use as cancer treatment in the rural area of the Loja province and the medical opinion regarding the use of ivermectin in humans. (2) Methods: The study used a mixed methodology using different sampling techniques such as observation, surveys, and interviews. (3) Results: The main findings show that 19% of the participants diagnosed with cancer take medicines based on ivermectin as alternative therapy to the cancer control and treatment without leaving treatment such as chemotherapy, radiotherapy, or immunotherapy, while 81% use it to treat other diseases. (4) Conclusions: Finally, we identify that the interviewed not only use IVM as anticancer treatment, but it is also used as a treatment against other diseases. Although the participants’ opinions indicate that they feel improvements in their health after the third dose, the specialist considers that there is no authorization to prescribe these alternative treatments. In addition, they confirmed that currently, there is no scientific knowledge about the application of these treatments in humans and they do not recommend their application. Thus, the anticancer mechanism of ivermectin remains to be further investigated; therefore, we consider that it is important to continue with this research by proposing a new stage to evaluate and determine the pharmacological action of this type of drug through an in vitro study in different cultures of cancer cells.
Oscar Vivanco-Galván, Yuliana Jiménez, Darwin Patricio Castillo Malla, and Hernán Lucero
SPIE
Cinchona officinalis L. is one of the most important and historically medicinal plants from which the antimalarial drug known as quinine is extracted. It is currently an endangered species. Thus, in vitro culture techniques are applied to propagate the species and to evaluate the effect of artificial light on the physiological development of C. Officinalis L. under controlled conditions. In that sense, the current study has determined the impact of blue led light on the enhancement of growth and number of shoots of Cinchona officinalis L. In vitro explants of C. Officinalis L were cultured on Murashige and Skoog (MS) medium and cultured under the white (control) and blue light-emitting diodes (LED) light. After eight weeks, growth and bud numbers were determined in C. officinalis L. Interestingly, blue light treatment increased the shoot length and bud numbers in comparison with the control. Incorporating blue light during in vitro propagation of C. Officinalis L can be a beneficial way to increase plant quality. Future perspectives could include the impact of blue light on the production of secondary metabolites, activities of antioxidant enzymes, and protein expression of in vitro-grown C. Officinalis L.
Oscar Vivanco-Galván, Danny Carrión, and Daniel Capa-Mora
Clinical Biotec
El uso de bacterias promotoras de crecimiento vegetal (BPCV), es considerada como una alternativa para sustituir los fertilizantes químicos, ya que favorece la productividad de las especies vegetales. El presente estudio evalúo el efecto de BPCV de los géneros Azospirillum sp. y Azotobacter sp. en el cultivo del Pennisetum clandestinum (kikuyo), sobre altura de la planta, largo máximo de la hoja, largo de raíces, biomasa fresca y proteína total. La aplicación de las bacterias se realizó periódicamente sobre el cultivo, la primera inoculación fue luego del arado del terreno y posterior a ello cada 15 días, hasta el día 45. Los resultados muestran que Azospirillum sp. y Azotobacter sp. influyeron sobre el crecimiento y rendimiento de kikuyo. La aplicación de Azospirillium sp. mostró un incremento significativo en kikuyo sobre los parámetros altura de la planta y el largo de raíz, mientras Azotobacter sp. en la producción de biomasa fresca, largo de raíz y proteína total, por lo cual el uso de estos microorganismos benéficos podría ser de gran importancia en las actividades de producción de pasto para la ganadería, además de ser una alternativa para reducir el uso de productos químicos, con lo que se contribuiría a un mejor manejo de cultivos y al cuidado del medio ambiente.
Guillermin Agüero-Chapin, Yuliana Jiménez, Aminael Sánchez-Rodríguez, Reinaldo Molina-Ruiz, Oscar Vivanco, and Agostinho Antunes
Bentham Science Publishers Ltd.
Background: Molecular phylogenetic algorithms frequently disagree with the approaches considering reproductive compatibility and morphological criteria for species delimitation. The question stems if the resulting species boundaries from molecular, reproductive and/or morphological data are definitively not reconcilable; or if the existing phylogenetic methods are not sensitive enough to agree morphological and genetic variation in species delimitation. Objectives : We propose DISTATIS as an integrative framework to combine alignment-based (AB) and alignment-free (AF) distance matrices from ITS2 sequences/structures to shed light whether Gelasinospora and Neurospora are sister but independent genera. Methods: We aimed at addressing this standing issue by harmonizing genus-specific classification based on their ascospore morphology and ITS2 molecular data. To validate our proposal, three phylogenetic approaches: i) traditional alignment-based, ii) alignment-free and iii) novel distance integrative (DI)-based were comparatively evaluated on a set of Gelasinospora and Neurospora species. All considered species have been extensively characterized at both the morphological and reproductive levels and there are known incongruences between their ascospore morphology and molecular data that hampers genus-specific delimitation. Results: Traditional AB phylogenetic analyses fail at resolving the Gelasinospora and Neurospora genera into independent monophyletic clades following ascospore morphology criteria. In contrast, AF and DI approaches produced phylogenetic trees that could properly delimit the expected monophyletic clades. Conclusions: The DI approach outperformed the AF one in the sense that it could also divide the Neurospora species according to their reproduction mode.
Yuliana Jiménez, Oscar Vivanco, Darwin Castillo, Pablo Torres, and Marco Jiménez
Springer International Publishing
Darwin P. Castillo, Rene J. Samaniego, Yuliana Jimenez, Luis A. Cuenca, Oscar A. Vivanco, Juan M. Alvarez-Gomez, and Maria J. Rodriguez-Alvarez
IEEE
Brain Magnetic Resonance Images are a very useful tool for the diagnosis of brain diseases and analyse brain changes. The appropriate processing (neuroimaging) can help to identify, measure and classify different lesions or abnormalities. The principal aim of this project is to develop an algorithm that can identify and differentiate ischemic disease than the demyelinating disease in the brain through the processing of magnetic resonance images. The damage and deterioration of the myelin layer of nerve fibers (brain demyelination) is the cause of pathologies like multiple sclerosis. Ischemic stroke is produced by the interruption of the blood supply to the brain. The dataset used was composed of images T1, T2 and FLAIR modalities of 90 patients from the hospital. For the segmentation of the features, the identification and the classification of the lesions have used the methods of Discrete Wavelet Transform (DWT), principal component analysis (PCA) and support vector machine (SVM). The results present 60 to 80% of accuracy to identify and differentiate the diseases.
Oscar A. Vivanco-Galván, Yuliana D. Jimenez, and Darwin P. Castillo
SPIE
The effect of laser irradiation is one of the most important factors that affect the bacteria survival due to the wavelengths that emit the different light sources. The high-intensity broadband visible light (400–800nm) can reduce viability of bacterial strains. The main objective is to assess the most effective wavelengths of visible light in growth of four beneficial rhizobacteria. The survival of bacterial cells following illumination was monitored by optical density after exposure of the suspended bacteria to light at different time of incubation. Bacterial grow under the same conditions but without light exposure as controls. The visible light with wavelength between 450-590nm increase the bacterial growth in vitro conditions.
Darwin P. Castillo Malla, María José Rodríguez, René Samaniego, Yuliana Jiménez, Luis Cuenca, and Oscar Vivanco
SPIE
Brain demyelination lesions occur due to damage of the myelin layer of nerve fibers, this deterioration is the cause of pathologies such as multiple sclerosis, leukodystrophy, encephalomyelitis. Brain ischemia is the interruption of the blood supply to the brain, and the flow of oxygen and nutrients needed to maintain the correct functioning of brain cells. This project presents the results of an algorithm processing images with the the main objective of identify and differentiate between demyelination and ischemic brain diseases through the automatic detection, classification and identification of their features found in the magnetic resonance images. The sequences of images used were T1, T2, and FLAIR and with a dataset of 300 patients with and without these or other pathologies, respectively. The algorithm in this stage uses Discrete Wavelet Transform (DWT), principal component analysis (PCA) and a kernel support vector machine (SVM). The algorithm developed indicates a 75% of accuracy, for that reason, with an effective validation could be applied for the fast diagnosis and contribute to an effective treatment of these brain diseases especially in the rural places.
Yuliana Jiménez, Oscar Vivanco, Luis Cuenca, César Granda, Darwin P. Castillo Malla, and Aramis A. Sánchez Juárez
SPIE
The present work shows the teaching and motivation of University students to think about optics and color effects. The methodology consists of studying the different optical phenomena that occur through the sunsets and then do a correlation of this information with the phenomena and optical effects of the color of class presentations; to determine the motivation and attention of students.
Darwin P. Castillo Malla, René Samaniego, María José Rodríguez-Álvarez, Yuliana Jiménez, Oscar Vivanco, and Luis Cuenca
SPIE
This work presents the advance to development of an algorithm for automatic detection of demyelinating lesions and cerebral ischemia through magnetic resonance images, which have contributed in paramount importance in the diagnosis of brain diseases. The sequences of images to be used are T1, T2, and FLAIR. Brain demyelination lesions occur due to damage of the myelin layer of nerve fibers; and therefore this deterioration is the cause of serious pathologies such as multiple sclerosis (MS), leukodystrophy, disseminated acute encephalomyelitis. Cerebral or cerebrovascular ischemia is the interruption of the blood supply to the brain, thus interrupting; the flow of oxygen and nutrients needed to maintain the functioning of brain cells. The algorithm allows the differentiation between these lesions.