Biology subjects

Silva, S. S.

Publications and source records attributed to Silva, S. S..

3 recordsLinked to original sources

bioRxiv2026

Smolt migration in relation to latitude, season and migratory distance

Downstream migration and sea entry are periods of high mortality for sea trout smolts and migration timing is a critical aspect of survival. We aimed to investigate migration timing of PIT-tagged sea trout smolts across a latitudinal gradient in five freshwater systems across Europe: Norway, Sweden, Denmark, France and Portugal. In two systems, smolt migration was further examined to assess a) differences in sex, body size and condition between autumn and spring migrants; b) the influence of spatial origin within the stream; and c) relationships between individual body size and migration date. Tagged smolts were not detected migrating in the Portuguese watershed. Spring migration timing differed significantly between watersheds in Norway, Sweden, Denmark and France. Generally, there was a trend of earlier migration at lower latitudes. Autumn vs spring migration was examined in Gudso-Denmark. Autumn migrants were larger in both length and mass, with no differences were found in sex ratios or body condition. In terms of spatial origin, fish originating from an upstream site were more likely to migrate in the autumn compared to the spring and vice versa. Size dependent migration was found in the Swedish system, Haga [a]-Sweden, with larger individuals migrating earlier in the spring than smaller individuals. Outward-migrating smolts were also more likely to originate from a downstream site than an upstream site. Overall, these results show both large-scale geographic and fine-scale individual influences on migration timing. Given that climate change may have large impacts on migration patterns in sea trout, understanding variability in migratory patterns across a latitudinal gradient is an important tool for predicting responses to environmental changes.

ecology↗

bioRxiv2025

An evolved strain of Spathaspora passalidarum produces ethanol from sugarcane bagasse and switchgrass lignocellulosic hydrolysates

Lignocellulosic hydrolysates, derived from plant biomass, contain various inhibitors that can hinder microbial growth. This study aimed to enable the growth and ethanol production by the xylose-fermenting yeast Spathaspora passalidarum in the presence of lignocellulosic hydrolysate inhibitors, particularly acetic acid. Ultraviolet (UV)-induced mutagenesis and adaptive laboratory evolution (ALE) were used to select for mutants with higher tolerance to these inhibitors. The initial mutant strain, MT01, was selected for increased growth in medium containing xylose and acetic acid. This strain underwent further evolution, resulting in the strain ME3.5.5, which showed significant improvements in both growth and ethanol production compared to the parental strain when tested in sugarcane bagasse hemicellulosic hydrolysate (SBHH). Genomic analysis identified non-synonymous and frameshift mutations in four genes, including CYR1 (encoding adenylate cyclase). These findings suggest that genetically optimized S. passalidarum strains could play a crucial role in advancing industrial bioethanol production from lignocellulosic biomass by overcoming the inhibitory effects of compounds found in lignocellulosic hydrolysates.

genomics↗

bioRxiv2022

Arabidopsis thaliana rosette growth habit is a photomorphogenic trait controlled by the TALE homeodomain protein ATH1 and involves TOR kinase

Here, we demonstrate that Arabidopsis rosette habit is a bona fide photomorphogenic trait controlled by the homeodomain protein ATH1. In light, ATH1 expression at the SAM is induced by broad wavelengths, mediated through multiple photoreceptors, and requires inactivation of COP1 and PIF photomorphogenesis inhibitors. Such induced ATH1 prevents elongation of rosette internodes by maintaining the rib zone area of the SAM in an inactive state. In the absence of light, Arabidopsis plants cannot complete seedling establishment after germination due to inactivity of the shoot apical meristem (SAM). Light requirement for SAM activation can be overcome by availability to the meristem of metabolizable sugars, such as sucrose. However, under these conditions plants fail to establish a typical compact rosette and display a caulescent growth habit. We show that this is due to insufficient expression of ATH1 at the SAM. ATH1 induction restores rosette habit in dark-grown plants through inhibition of PIF gene expression. Together, this suggests that a SAM-specific, double-negative ATH1-PIF feedback loop is at the basis of Arabidopsis rosette habit. Induction of ATH1 expression and restoration of rosette habit in darkness also occurs at increased levels of sucrose. Both sugar and light signals that induce ATH1 are mediated by TOR kinase. Overall, these results support a fundamental role for ATH1 in Arabidopsis rosette habit and further strengthen a role for TOR kinase as a central hub for integration of energy and light signals controlling organogenesis at the SAM.

plant biology↗