Examinando por Autor "Soto, Esteban"

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    Detection and virulence of Lactococcus garvieae and L. petauri from four lakes in southern California
    (John Wiley and Sons Inc, 2023-09) Abraham, Taylor; Yazdi, Zeinab; Littman, Eric; Shahin, Khalid; Heckman, Taylor I.; Quijano Cardé, Eva Marie; Nguyen, Diem Thu; Hu, Ruixue; Adkison, Mark; Veek, Tresa; Mukkatira, Kavery; Richey, Christine; Kwak, Kevin; Mohammed, Haitham H.; Ortega, Cesar; Avendaño-Herrera, Ruben; Keleher, William; LePage, Véronique; Gardner, Ian; Welch, Timothy J.; Soto, Esteban
    Objective: The first objective of the study aimed to detect the presence of Lactococcus petauri, L. garvieae, and L. formosensis in fish (n = 359) and environmental (n = 161) samples from four lakes near an affected fish farm in California during an outbreak in 2020. The second objective was to compare the virulence of the Lactococcus spp. in Rainbow Trout Oncorhynchus mykiss and Largemouth Bass Micropterus salmoides. Methods: Standard bacterial culture methods were used to isolate Lactococcus spp. from brain and posterior kidney of sampled fish from the four lakes. Quantitative PCR (qPCR) was utilized to detect Lactococcus spp. DNA in fish tissues and environmental samples from the four lakes. Laboratory controlled challenges were conducted by injecting fish intracoelomically with representative isolates of L. petauri (n = 17), L. garvieae (n = 2), or L. formosensis (n = 4), and monitored for 14 days postchallenge (dpc). Result: Lactococcus garvieae was isolated from the brains of two Largemouth Bass in one of the lakes. Lactococcus spp. were detected in 14 fish (8 Bluegills Lepomis macrochirus and 6 Largemouth Bass) from 3 out of the 4 lakes using a qPCR assay. Of the collected environmental samples, all 4 lakes tested positive for Lactococcus spp. in the soil samples, while 2 of the 4 lakes tested positive in the water samples through qPCR. Challenged Largemouth Bass did not show any signs of infection postinjection throughout the challenge period. Rainbow Trout infected with L. petauri showed clinical signs within 3 dpc and presented a significantly higher cumulative mortality (62.4%; p < 0.0001) at 14 dpc when compared to L. garvieae (0%) and L. formosensis (7.5%) treatments. Conclusion: The study suggests that qPCR can be used for environmental DNA monitoring of Lactococcus spp. and demonstrates virulence diversity between the etiological agents of piscine lactococcosis. © 2023 The Authors. Journal of Aquatic Animal Health published by Wiley Periodicals LLC on behalf of American Fisheries Society.
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    Global Methylation Analysis Using MSAP Reveals Differences in Chilling-Associated DNA Methylation Changes during Dormancy Release in Contrasting Sweet Cherry Varieties
    (MDPI, 2022-10) Narváez, Gabriela; Muñoz Espinoza, Claudia; Soto, Esteban; Rothkegel, Karin; Bastías, Macarena; Gutiérrez, José; Bravo, Soraya; Hasbún, Rodrigo; Meneses, Claudio; Almeida, Andrea Miyasaka
    Dormancy is an adaptive strategy developed by temperate perennial crops to protect overwinter tissues from unfavorable environmental conditions. Sweet cherry (Prunus avium L.), a member of the Rosaceae family, requires chilling to overcome dormancy. The time of harvest is directly correlated with chilling requirements in sweet cherries. Consequently, early and late season varieties have low and high chilling requirements, respectively. There is evidence that the expression of dormancy-related genes is regulated by DNA methylation. In this work, methylation-sensitive amplified polymorphism (MSAP) was applied to study genome-wide DNA methylation changes associated with dormancy in two low-chill varieties, ‘Royal Dawn’ and ‘Glen Red’, and one high-chill variety, ‘Kordia’. Our primary results suggest that the occurrence of progressive DNA demethylation is associated with chilling accumulation during dormancy in the three varieties, independent of their chilling requirements. Genes were identified with different methylation status changes, detected by MSAP, related to cell wall remodeling and energy metabolism. Several MSAP profiles among the varieties were observed, suggesting that fine epigenetic control is required to coordinate hormonal and environmental signals that induce dormancy and its release. © 2022 by the authors.
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    Small RNA Differential Expression Analysis Reveals miRNAs Involved in Dormancy Progression in Sweet Cherry Floral Buds
    (MDPI, 2022-09) Soto, Esteban; Sanchez, Evelyn; Nuñez, Carlos; Montes, Christian; Rothkegel, Karin; Andrade, Paola; Prieto, Humberto; Miyasaka Almeida, Andrea
    In sweet cherry (Prunus avium), as in other temperate woody perennials, bud dormancy allows for survival in adverse environmental conditions during winter. During this process, environmental signals such as short days and/or low temperatures trigger internal signals that enable buds to become tolerant to the cold. The process involves tracking chilling units up to chilling the requirement fulfillment to resume growth, a transition involving transcriptional regulation, metabolic signaling, and epigenetic-related regulatory events. Massive sequencing of small RNAs was performed to identify miRNAs involved in sweet cherry dormancy by comparing their expression in field (regular seasonal) and controlled non-stop (continuous) chilling conditions. miRNAs highlighted by sequencing were validated using specific stem-loop PCR quantification, confirming expression patterns for known miRNAs such as miR156e, miR166c, miR172d, miR391, miR482c, and miR535b, as well as for newly proposed miRNAs. In silico prediction of the target genes was used to construct miRNA/target gene nodes. In particular, the involvement of the sweet cherry version for the miR156/SQUAMOSA PROMOTER-BINDING-LIKE PROTEIN genes whose expression was opposite in the two conditions suggests their involvement on dormancy regulation in sweet cherry. miRNA levels indicate that the regulation of stress-related genes and hormone synthesis modulates the expression of calcium metabolism and cell development-associated genes. Understanding the regulatory networks involved in sweet cherry dormancy, particularly in the context of miRNA involvement, represents the first step in the development of new agricultural strategies that may help overcome the increasing challenges presented by global climate change. © 2022 by the authors.