Pablo Castillejo

Dr. Pablo Castillejo

Universidad de Las Américas, Quito, Pichincha, Ecuador
orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 February 2014 in The Plant Journal
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Journal Article
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ACAlberto Coego
Alberto Coego
EBEsther Brizuela
Esther Brizuela
PCPablo Castillejo
Pablo Castillejo
SRSandra Ruíz
Sandra Ruíz
CKCsaba Koncz
Csaba Koncz
Jose M RomeroJose M Romero
Jose M Romero
Summary: Transcription factors (TFs) are key regulators of gene expression in all organisms. In eukaryotes, TFs are often represented by functionally redundant members of large gene families. Overexpression might prove a means to unveil the biological functions of redundant TFs; however, constitutive overexpression of TFs frequently causes severe developmental defects, preventing their functional characterization. Conditional overexpression strategies help to overcome this problem. Here, we report on the TRANSPLANTA collection of Arabidopsis lines, each expressing one of 949 TFs under the control of a β–estradiol‐inducible promoter. Thus far, 1636 independent homozygous lines, representing an average of 2.6 lines for every TF, have been produced for the inducible expression of 634 TFs. Along with a GUS‐GFP reporter, randomly selected TRANSPLANTA lines were tested and confirmed for conditional transgene expression upon β–estradiol treatment. As a proof of concept for the exploitation of this resource, β–estradiol‐induced proliferation of root hairs, dark‐induced senescence, anthocyanin accumulation and dwarfism were observed in lines conditionally expressing full‐length cDNAs encoding RHD6, WRKY22, MYB123/TT2 and MYB26, respectively, in agreement with previously reported phenotypes conferred by these TFs. Further screening performed with other TRANSPLANTA lines allowed the identification of TFs involved in different plant biological processes, illustrating that the collection is a powerful resource for the functional characterization of TFs. For instance, ANAC058 and a TINY/AP2 TF were identified as modulators of ABA‐mediated germination potential, and RAP2.10/DEAR4 was identified as a regulator of cell death in the hypocotyl–root transition zone. Seeds of TRANSPLANTA lines have been deposited at the Nottingham Arabidopsis Stock Centre for further distribution.

1 January 2021 in Neotropical Biodiversity
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Journal Article
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IBIsabel Ballesteros
Isabel Ballesteros
PTPaulina Terán
Paulina Terán
CGCristina Guamán-Burneo
Cristina Guamán-Burneo
NGNory González
Nory González
ACAlejandra Cruz
Alejandra Cruz
PCPablo Castillejo
Pablo Castillejo
The use of suitable DNA barcodes and the generation of databases with reference sequences have been considered a promissory approach for the identification of Chlorophyta and Cyanophyta microalgae. In this study, we carried out a molecular characterization and identification of strains isolated from freshwater systems in Ecuador using a dual barcode method. The target sequences for Chlorophyta were 18S rDNA and rbcL genes, and 16S rDNA and 16S–23S rDNA intergenic spacer (ITS) for Cyanophyta. We reported these DNA barcodes for 20 different Molecular Operational Taxonomic Units (MOTUs) for Chlorophyta and 10 for Cyanophyta. Our results show that the 18S V4 hypervariable region (300 bp) is sufficient for differentiating between isolates, but rbcL is a determinant for genus identification in Scenedesmaceae and Chlorellaceae strains. In Cyanophyta, both barcodes enabled the genus-level assignment of 9 out of 10 MOTUs. These results highlight the necessity of a second barcode additional to small ribosomal subunit sequences to improve molecular identification. Furthermore, the present study significantly contributes to the body of Ecuadorian barcode sequences of microalgae that are currently documented, making them available for future comparative diversity studies.

1 April 2018 in Comptes Rendus. Biologies
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Journal Article
Closed access
PCPablo Castillejo
Pablo Castillejo
SCSusana Chamorro
Susana Chamorro
LPLuis Paz
Luis Paz
CHCarla Heinrich
Carla Heinrich
ICIvonne Carrillo
Ivonne Carrillo
ELEduardo A. Lobo
Eduardo A. Lobo
Epilithic diatom communities are particularly suitable for the evaluation of freshwater quality. In Ecuador, however, no water quality index includes this biotic parameter. This work is the first attempt in the country to determine the composition of epilithic diatom communities associated with different degrees of eutrophication. This was accomplished by measuring physical, chemical and microbiological variables at five sampling sites along the Pita River, Ecuador, from August to December 2016. The results indicate a clear gradient of eutrophication from sampling sites P1 (good water) in the upper reaches to P5 (bad water) located in the lower reaches. Concerning diatom analyses, the results indicated a high diversity for tropical areas in terms of species richness, varying from S = 34 in headwaters to S = 42 downstream. Moreover, the results obtained suggest a lack of concordance with the trophic values given to some of the epilithic diatoms in the literature. There were also species that seem to be sensitive to downstream nutrient increases that were not considered as bioindicators in previous studies. We concluded that the trophic values of diatom species available in the scientific literature are not directly applicable to their sites in the Pita River. Hence, it is necessary to establish a trophic diatom index for the Andean region of Ecuador.

12 July 2023 in Hydrobiologia
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PCPablo Castillejo
Pablo Castillejo
SOSofia Ortiz
Sofia Ortiz
GJGabriela Jijón
Gabriela Jijón
ELEduardo A. Lobo
Eduardo A. Lobo
CHCarla Heinrich
Carla Heinrich
BRBlanca Rios-Touma
Blanca Rios-Touma
Population growth and increasing production demands threaten the highly diverse Andean freshwater ecosystems. Biological indicators constitute a valuable tool for evaluating the ecological quality of freshwater ecosystems under different pressures. Diatom and macroinvertebrate assemblages are the most used bioindicators to assess water pollution, whereby these biotic groups occupy the first and second trophic levels and respond to habitat pollution. Several studies have explored the response of these communities to water pollution in other regions, but no studies have examined their performance in Andean rivers. In this context, this research aimed to evaluate the responses and relationships of both groups of bioindicators in the Upper Guayllabamba basin. We collected macroinvertebrate and diatom samples from nine sites in this basin during the dry and wet seasons, calculated trophic indices for both groups, and related them to environmental characteristics. The results indicated that both bioindicators were sensitive to changes in land use and nutrients. Epilithic diatoms were more sensitive to changes in water chemistry and macroinvertebrates to changes in fluvial habitat and land use. The index based on macroinvertebrates better-detected changes in quality classes between sites and seasons. Therefore, both indices gave complementary information, and their joint use seems suitable in Andean streams.

1 January 2021 in Neotropical Biodiversity
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Journal Article
Open access
MDMagdalena Díaz
Magdalena Díaz
PJPablo Jarrín-V.
Pablo Jarrín-V.
RSRaquel Simarro
Raquel Simarro
PCPablo Castillejo
Pablo Castillejo
Gabriela N. TeneaGabriela N. Tenea
Gabriela N. Tenea
CMC. Alfonso Molina
C. Alfonso Molina
A technological revolution provides nations with access to unprecedented quantities of molecular information, and this is particularly evident in the vast and yet poorly understood realm of the microbiome. Traditionally, many developing countries in Asia, Africa, and South America remain marginal participants in the global flow of biodata, which will eventually affect their productivity and economies. Here, we present the Ecuadorian Microbiome Project (EcuMP) as an integrative initiative to close the research gap in the microbiome for Ecuador. We discuss the relevance that the study of the microbiome has for our understanding of diversity and new forms of production and biocapital. We also evaluate the state of research in metagenomics and the microbiome for South America, with emphasis on Ecuador as a small but biodiverse country. In the strict sense of access, understanding, and technological innovation based on molecular data, we propose the definition of bioliteracy. As indirect estimates of bioliteracy, we measured the number of indexed publications, BioProjects, monthly global internet traffic to GenBank, and patent applications in Espacenet. South America has a notable unevenness in scientific productivity related to the microbiome and metagenomics. Brazil leads productivity, with most of the measured parameters remaining one order of magnitude higher than other countries in the region. Participation of South American countries in the global flow of genomic information dwarfs when compared to the US. To reduce the effects of technological dependency and the associated lack of economic productivity, Ecuador should address the technological gap in the study of the microbiome. Our assessment reveals the urgency to translate the study of microbiomes into a source of technological prowess and the basis for local biocapitals.

25 November 2022 in Veterinary Sciences
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MHMaría P. Huilca-Ibarra
María P. Huilca-Ibarra
DVDavid Eduardo Vasco
David Eduardo Vasco
YLYanua Gabriela Ledesma
Yanua Gabriela Ledesma
MGMónica Salomé Guerrero-Freire
Mónica Salomé Guerrero-Freire
JZJeannete Zurita
Jeannete Zurita
JWJacobus H. De Waard
Jacobus H. De Waard
The genus Prototheca, a unicellular, non-photosynthetic, yeast-like microalgae, is a pathogen of concern for the dairy industry. It causes bovine mastitis that currently cannot be cured, and hence generates significant economic losses in milk production. In this study, for the first time in Ecuador, we identify Prototheca bovis as the etiologic agent of chronic mastitis in dairy cattle. Milk samples (n = 458) of cows with chronic mastitis were cultured on Sabouraud Dextrose Agar (SDA). Microscopy and cytB gene sequencing were used to identify Prototheca, whereby Prototheca bovis was isolated from 15.1% (n = 69) of the milk samples, one of the highest infection rates that can be found in the literature in a “non-outbreak” situation. No other Prototheca species were found. We were unable to isolate the alga from environmental samples. We showed that P. bovis was relatively resistant to disinfectants used to sterilize milking equipment on the cattle farms where it was isolated. We discuss how to avoid future infection and also hypothesize that the real prevalence of Prototheca infection in bovine mastitis is probably much higher than what was detected. We recommend a protocol to increase the diagnostic yield in the bacteriology laboratory.