Search

Among South American countries, Chile is highly susceptible to climate change impacts on water resources and ecosystems. Chilean lakes and rivers have been impacted by anthropogenic activities leading to chemical pollution and eutrophication. Concerns for conservation and management of water resources have led to the current development of regulations for environmental quality of Northern Patagonian lakes. In this context, we analyze historical limnological databases (1979–2022) for these lakes utilizing random forest (RF) models. After filtering, we retained data for 11 lakes including key variables of dissolved oxygen, conductivity, transparency, temperature, pH, total nitrogen, total phosphorus, and chlorophyll a. This dataset yielded robust results, accurately predicting chlorophyll a concentration. Furthermore, we added lake geomorphological parameters, enhancing the performance of the model. Our study demonstrates the need to improve long-term monitoring programs, optimizing environmental data recording for efficient investment. We conclude that the studied lakes generally maintain their oligotrophic characteristics and are more sensitive to nitrogen than phosphorus loading. Our results highlight the need to implement adaptative management plans at the watershed level to regulate anthropogenic nitrogen contamination from agriculture, pisciculture, and urbanization. The features selected by RF, coupled with the assessment of historical trophic state variation, allow the establishment of permissible concentration thresholds for major nutrients and other sentinel variables, informing the development of regulations for environmental quality. Lastly, the enhanced performance of RF modeling that includes geographical variables demonstrates the need to standardize and integrate geographical data in monitoring practices. [ABSTRACT FROM AUTHOR]

Gracilaria chilensis is the main cultivated seaweed in Chile. The low genetic diversity observed in the Chilean populations has been associated with the over‐exploitation of natural beds and/or the founder effect that occurred during post‐glacial colonization from New Zealand. How these processes have affected its evolutionary trajectory before farming and incipient domestication is poorly understood. In this study, we used 2232 single nucleotide polymorphisms (SNPs) to assess how the species' evolutionary history in New Zealand (its region of origin), the founder effect linked to transoceanic dispersion and colonization of South America, and the recent over‐exploitation of natural populations have influenced the genetic architecture of G. chilensis in Chile. The contrasting patterns of genetic diversity and structure observed between the two main islands in New Zealand attest to the important effects of Quaternary glacial cycles on G. chilensis. Approximate Bayesian Computation (ABC) analyses indicated that Chatham Island and South America were colonized independently near the end of the Last Glacial Maximum and emphasized the importance of coastal and oceanic currents during that period. Furthermore, ABC analyses inferred the existence of a recent and strong genetic bottleneck in Chile, matching the period of over‐exploitation of the natural beds during the 1970s, followed by rapid demographic expansion linked to active clonal propagation used in farming. Recurrent genetic bottlenecks strongly eroded the genetic diversity of G. chilensis prior to its cultivation, raising important challenges for the management of genetic resources in this incipiently domesticated species. [ABSTRACT FROM AUTHOR]

Abstract Background ISAV is a member of the Orthomyxoviridae family that affects salmonids with disastrous results. It was first detected in 1984 in Norway and from then on it has been reported in Canada, United States, Scotland and the Faroe Islands. Recently, an outbreak was recorded in Chile with negative consequences for the local fishing industry. However, few studies have examined available data to test hypotheses associated with the phylogeographic partitioning of the infecting viral population, the population dynamics, or the evolutionary rates and demographic history of ISAV. To explore these issues, we collected relevant sequences of genes coding for both surface proteins from Chile, Canada, and Norway. We addressed questions regarding their phylogenetic relationships, evolutionary rates, and demographic history using modern phylogenetic methods. Results A recombination breakpoint was consistently detected in the Hemagglutinin-Esterase (he) gene at either side of the Highly Polymorphic Region (HPR), whereas no recombination breakpoints were detected in Fusion protein (f) gene. Evolutionary relationships of ISAV revealed the 2007 Chilean outbreak group as a monophyletic clade for f that has a sister relationship to the Norwegian isolates. Their tMRCA is consistent with epidemiological data and demographic history was successfully recovered showing a profound bottleneck with further population expansion. Finally, selection analyses detected ongoing diversifying selection in f and he codons associated with protease processing and the HPR region, respectively. Conclusions Our results are consistent with the Norwegian origin hypothesis for the Chilean outbreak clade. In particular, ISAV HPR0 genotype is not the ancestor of all ISAV strains, although SK779/06 (HPR0) shares a common ancestor with the Chilean outbreak clade. Our analyses suggest that ISAV shows hallmarks typical of RNA viruses that can be exploited in epidemiological and surveillance settings. In addition, we hypothesized that genetic diversity of the HPR region is governed by recombination, probably due to template switching and that novel fusion gene proteolytic sites confer a selective advantage for the isolates that carry them. Additionally, protein modeling allowed us to relate the results of phylogenetic studies with the predicted structures. This study demonstrates that phylogenetic methods are important tools to predict future outbreaks of ISAV and other salmon pathogens.

The Isavirus is an orthomyxovirus with a genome composed of eight segments of negative single‐strand RNA (−ssRNA). It has been proposed that the eight genomic segments of the Isavirus are organized as a ribonucleoprotein (RNP) complex called a minigenome, which contains all the viral RNA segments, a viral heterotrimeric polymerase and multiple copies of the viral nucleoprotein (NP). Here, we develop an Isavirus minigenome system and show the importance of the formation of active RNPs and the role of viral NP R189, R194, R302 and K325 residues in the NP RNA‐binding domain in the context of RNPs. The results indicate it is possible to generate a minigenome in salmon cells, a composite ISAV RNPs with EGFP‐based chimeric vRNA with heterotrimeric polymerase (PB1, PB2, PA) and NP protein using CMV‐based auxiliary plasmids. It was also shown that NP R189, R194, R302 and K325 residues are important to generate viral mRNA from the constituted RNPs and a detectable reporter protein. This work is the first salmon cell‐based minigenome assay for the Isavirus, which was evaluated by a bioinformatic and functional study of the NP protein in viral RNPs, which showed that correct NP‐vRNA interaction is key to the functioning of RNPs. [ABSTRACT FROM AUTHOR]

The small South American marsupial, Dromiciops gliroides, known as the missing link between the American and the Australian marsupials, is one of the few South American mammals known to hibernate. Expressing both daily torpor and seasonal hibernation, this species may provide crucial information about the mechanisms and the evolutionary origins of marsupial hibernation. Here, we compared torpid and active individuals, applying high‐throughput sequencing technologies (RNA‐seq) to profile gene expression in three D. gliroides tissues and determine whether hibernation induces tissue‐specific differential gene expression. We found 566 transcripts that were significantly up‐regulated during hibernation (369 in brain, 147 in liver and 50 in skeletal muscle) and 339 that were down‐regulated (225 in brain, 79 in liver and 35 in muscle). The proteins encoded by these differentially expressed genes orchestrate multiple metabolic changes during hibernation, such as inhibition of angiogenesis, prevention of muscle disuse atrophy, fuel switch from carbohydrate to lipid metabolism, protection against reactive oxygen species and repair of damaged DNA. According to the global enrichment analysis, brain cells seem to differentially regulate a complex array of biological functions (e.g., cold sensitivity, circadian perception, stress response), whereas liver and muscle cells prioritize fuel switch and heat production for rewarming. Interestingly, transcripts of thioredoxin‐interacting protein (TXNIP), a potent antioxidant, were significantly over‐expressed during torpor in all three tissues. These results suggest that marsupial hibernation is a controlled process where selected metabolic pathways show adaptive modulation that can help to maintain homeostasis and enhance cytoprotection in the hypometabolic state. [ABSTRACT FROM AUTHOR]

Piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia, a disease that seriously affects the salmonid industry. Despite efforts to genomically characterize P. salmonis, functional information on the life cycle, pathogenesis mechanisms, diagnosis, treatment, and control of this fish pathogen remain lacking. To address this knowledge gap, the present study conducted an in silico pan-genome analysis of 19 P. salmonis strains from distinct geographic locations and genogroups. Results revealed an expected open pan-genome of 3,463 genes and a core-genome of 1,732 genes. Two marked genogroups were identified, as confirmed by phylogenetic and phylogenomic relationships to the LF-89 and EM-90 reference strains, as well as by assessments of genomic structures. Different structural configurations were found for the six identified copies of the ribosomal operon in the P. salmonis genome, indicating translocation throughout the genetic material. Chromosomal divergences in genomic localization and quantity of genetic cassettes were also found for the Dot/Icm type IVB secretion system. To determine divergences between core-genomes, additional pan-genome descriptions were compiled for the so-termed LF and EM genogroups. Open pan-genomes composed of 2,924 and 2,778 genes and core-genomes composed of 2,170 and 2,228 genes were respectively found for the LF and EM genogroups. The core-genomes were functionally annotated using the Gene Ontology, KEGG, and Virulence Factor databases, revealing the presence of several shared groups of genes related to basic function of intracellular survival and bacterial pathogenesis. Additionally, the specific pan-genomes for the LF and EM genogroups were defined, resulting in the identification of 148 and 273 exclusive proteins, respectively. Notably, specific virulence factors linked to adherence, colonization, invasion factors, and endotoxins were established. The obtained data suggest that these genes could be directly associated with inter-genogroup differences in pathogenesis and host-pathogen interactions, information that could be useful in designing novel strategies for diagnosing and controlling P. salmonis infection. [ABSTRACT FROM AUTHOR]

The southern tip of South America and Antarctica are particularly interesting due to many genera and also species currently sharing between both areas. The genus Nacella (Patellogastropoda: Nacellidae) is distributed in different regions of South America and Antarctica living preferentially on rocks and boulders and grazing on algae, diatoms and bacterial films. We described the transcriptomes of three Nacella species, Nacella concinna (Strebel, 1908), inhabiting the Antarctic Peninsula; Nacella magallanica (Gmelin, 1791), from Patagonia and Nacella clypeater (Lesson, 1831), from central Chile. In total, we obtained over 20,000 contigs with an average length of 583 bp. Homologous protein coding genes (PCGs) for mitochondrial genome of the three species were characterized and a database of molecular markers was also generated. This study represents the first publicly available report on pyrosequencing data for patellogastropod species, and provides an important comparative resource for studies in ecophysiology and evolutionary adaptation in marine invertebrate species. [ABSTRACT FROM AUTHOR]

Monarch butterflies in North America migrate south each autumn, but the mechanisms that initiate their migratory flight remain incompletely understood. We investigated environmental, developmental, and genetic factors that contribute to directional flight by testing summer and autumn-generation monarchs in three flight simulators: two at ground level (with and without wind blockage) and a novel balloon-based system that raised butterflies 30 meters into the air. Monarchs reared under autumn-like conditions in a growth chamber during the summer were also tested to explore the influence of developmental cues. Autumn generation monarchs demonstrated significant southwestern flight orientation, observed exclusively in the balloon simulator, underscoring the importance of high-altitude flight for migratory behavior. Summer generation monarchs reared under autumn-like conditions displayed southward orientation, larger wing sizes, and partial reproductive diapause, indicating specific seasonal environmental cues that are sufficient to induce migratory traits. In contrast, a lab line of monarchs reared in captivity since 2016 exhibited diminished wing size and reduced orientation ability, even when raised outdoors in the autumn, consistent with a loss of migratory traits in the absence of migration. Surprisingly, butterflies in the balloon simulator tended to orient upwind, which suggests that wind may also serves as a directional cue during migration. These findings highlight the critical roles of altitude, wind, and environmental cues in monarch migration and validate the balloon flight simulator as a powerful tool for studying migratory behavior. This research advances our understanding of the initiation of monarch migration and informs strategies for conservation efforts amidst environmental change.

Conditional gene regulation in Drosophila through binary expression systems like the LexA-LexAop system provides a superb tool for investigating gene and tissue function. To increase the availability of defined LexA enhancer trap insertions, we present molecular, genetic, and tissue expression studies of 301 novel Stan-X LexA enhancer traps derived from mobilization of the index SX4 line. This includes insertions into distinct loci on the X, II, and III chromosomes that were not previously associated with enhancer traps or targeted LexA constructs, an insertion into ptc, and seventeen insertions into natural transposons. A subset of enhancer traps was expressed in CNS neurons known to produce and secrete insulin, an essential regulator of growth, development, and metabolism. Fly lines described here were generated and characterized through studies by students and teachers in an international network of genetics classes at public, independent high schools, and universities serving a diversity of students, including those underrepresented in science. Thus, a unique partnership between secondary schools and university-based programs has produced and characterized novel resources in Drosophila, establishing instructional paradigms devoted to unscripted experimental science., Competing Interests: Conflicts of interest statement The author(s) declare no conflict of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Genetics Society of America.)

It has been proposed that sub-inhibitory concentrations of antibiotics play a role in virulence modulation. In this study, we evaluated the ability of Salmonella enterica serovar Typhimurium (hereafter S. Typhimurium) to colonize systemically BALB/c mice after exposure to a sub-inhibitory concentration of cefotaxime (CTX). In vivo competition assays showed a fivefold increase in systemic colonization of CTX-exposed bacteria when compared to untreated bacteria. To identify the molecular mechanisms involved in this phenomenon, we carried out a high-throughput genetic screen. A transposon library of S. Typhimurium mutants was subjected to negative selection in the presence of a sub-inhibitory concentration of CTX and genes related to anaerobic metabolism, biosynthesis of purines, pyrimidines, amino acids and other metabolites were identified as needed to survive in this condition. In addition, an impaired ability for oxygen consumption was observed when bacteria were cultured in the presence of a sub-inhibitory concentration of CTX. Altogether, our data indicate that exposure to sub-lethal concentrations of CTX increases the systemic colonization of S. Typhimurium in BALB/c mice in part by the establishment of a fitness alteration conducive to anaerobic metabolism., (© 2015 The Authors.)

Every day, the emergency departments in our country receive a large number of patients that have thought about or attempted suicide. Unfortunately, these patients are very often reluctant to maintain a regular follow-up in mental health services. In this study we describe an original program to encourage assessment and treatment of suicidal patients, particularly when they receive medical treatment in public places. We summarize the application of the program and compare the results of a specific follow-up between two groups of patients: suicidal patients assessed by emergency services in public places and all other suicidal patients assessed in the emergency department of a tertiary hospital.

We report here the draft genome sequence of a lethal pathogen of farmed salmonids, Piscirickettsia salmonis strain AUSTRAL-005. This virulent strain was isolated in 2008 from Oncorhynchus mykiss farms, and multiple genes involved in pathogenicity, environmental adaptation, and metabolic pathways were identified., (Copyright © 2014 Yañez et al.)