Biology subjects

Gallardo, J. A.

Publications and source records attributed to Gallardo, J. A..

3 recordsLinked to original sources

bioRxiv2021

RNA-Seq analysis and transcriptome assembly of Salicornia neei reveals powerful system for ammonium detoxification

BackgroundSalicornia neei is a halophyte plant that has been proposed for use in the phytoremediation of the saline wastewater generated by land-based aquaculture, which usually contains elevated concentrations of ammonium resulting from protein metabolism. To identify the molecular mechanisms related to ammonium response, we analyzed the transcriptome of S. neei in response to growth in saline water containing 3 mM ammonium and the Michaelis-Menten ammonium removal biokinetics. ResultsThe RNA sequencing generated a total of 14,680,108 paired-end reads from the control and stressed conditions. De novo assembly using the CLC Genomic Workbench produced 86,020 transcripts and a reference transcriptome with an N50 of 683 bp. A total of 45,327 genes were annotated, representing 51.2% of the contig predicted from de novo assembly. As regards DEGs, a total of 9,140 genes were differentially expressed in response to ammonium in saline water; of these, 7,396 could be annotated against functional databases. The upregulated genes were mainly involved in cell wall biosynthesis, transmembrane transport and antiporter activities, including biological KEGG pathways linked to the biosynthesis of secondary metabolites, plant hormone signal transduction, autophagy, and nitrogen metabolism. In addiction, a set of 72 genes was directly involved in ammonium metabolism, including glutamine synthetase 1 (GLN1), glutamate synthase 1 (GLT1), and ferredoxin-dependent glutamate synthase chloroplastic (Fd-GOGAT). Finally, we observed that the ammonium uptake rate increased with increasing ammonium concentrations, and tended toward saturation in the range of 3 to 4 mM. ConclusionOur results support the hypothesis that an ammonium detoxification system mediated by glutamine and glutamate synthase was activated in S. neei when exposed to ammonium and saline water. The present transcriptome profiling method could be useful when investigating the response of halophyte plants to saline wastewater from land-based aquaculture.

genomics↗

bioRxiv2021

Commercial vaccines do not confer protection against two genetic strains of Piscirickettsia salmonis, LF-89-like and EM-90-like, in Atlantic salmon.

In Atlantic salmon, vaccines have failed to control and prevent Piscirickettsiosis, for reasons that remain elusive. In this study, we report the efficacy of a commercial vaccine developed with the Piscirickettsia salmonis isolate AL100005 against other two isolates which are considered highly and ubiquitously prevalent in Chile: LF-89-like and EM-90-like. Two cohabitation trials were performed to mimic real-life conditions and vaccine performance: 1) post smolt fish were challenged with a single infection of LF-89-like, 2) adults were coinfected with EM-90-like and a low coinfection of sea lice. In the first trial, the vaccine delayed smolt mortalities by two days; however, unvaccinated and vaccinated fish did not show significant differences in survival (unvaccinated: 60.3%, vaccinated: 56.7%; p = 0.28). In the second trial, mortality started three days later for vaccinated fish than unvaccinated fish. However, unvaccinated and vaccinated fish did not show significant differences in survival (unvaccinated: 64.6%, vaccinated: 60.2%, p= 0.58). Thus, we found no evidence that the evaluated vaccines confer effective protection against of LF-89-like or EM-90-like with estimated relative survival proportions (RPSs) of -9% and -12%, respectively. More studies are necessary to evaluate whether pathogen heterogeneity is a key determinant of the vaccine efficacy against P. salmonis.

immunology↗

bioRxiv2020

Efficiency of Salicornia neei in removing nitrogen and producing biomass from a hypersaline and artificial wetland to treat aquaculture effluent

In this study we evaluated the potential of Salicornia neei, a halophyte plant native to South America, to treat saline effluents with simulated concentration of ammonium-N (Amm) and nitrate-N (Nit) similar to land-based marine aquaculture effluents. Plants were cultivated for 74 days in drainage lysimeters under three treatments of seawater fertilized with: 1) Nit+Amm, 2) Nit, or 3) without fertilizer (Control). Over 5 repetitions, nitrogen removal efficiency (RE) was high in both treatments (Nit + Amm = 89.6{+/-} 1,0 %; Nit 88.8 {+/-} 0.9 %). While nitrogen removal rate (RR) was non linear and concentration-dependent (RRday 1-4: Nit+Amm= 2.9 {+/-} 0.3 mg L-1 d-1, Nit = 2.4 {+/-} 0.5mg L-1 d-1; RRday5-8: Nit + Amm = 0.8 {+/-} 0.2mg L-1 d-1, Nit=1.0 {+/-} 0.2mg L-1 d-1). Effluent salinity increased from 40.6 to 49.4 g L-1 during the experiment, with no observed detrimental effects on RE or RR. High nitrogen removal efficiency and significant biomass production observed, Nit+Amm = 11.3 {+/-} 2.0 kg m-2; Nit = 10.0 {+/-} 0.8 kg m-2; Control = 4.6 {+/-} 0.6 kg m-2, demonstrate that artificial wetlands of S. neei can be used for wastewater treatment in saline aquaculture in South America.

plant biology↗