Biology subjects

Tedesco, P.

Publications and source records attributed to Tedesco, P..

3 recordsLinked to original sources

bioRxiv2026

Environmental DNA reveals long-term persistence of a Midichloria-like bacterium in a rainbow trout aquaculture and links Ichthyopthirius multifiliis with the red mark syndrome

Red Mark Syndrome (RMS) is a widespread skin disease affecting rainbow trout (Onchorhynchus mykiss). It provokes substantial economic losses in aquaculture, and is putatively caused by a Rickettsiales bacterium named Midichloria-like organism (RMS-MLO), which is strongly associated with RMS lesions. However, RMS-MLO ecology and epidemiology in aquaculture systems remain poorly understood. In this study, we analysed environmental DNA to monitor the presence of RMS-MLO and its putative vector Ichthyophthirius multifiliis in a trout farm in Northern Italy over one year. Water and sediment samples were monthly collected from multiple water tanks. RMS-MLO was consistently detected by PCR throughout the study in all trout-containing tanks, both in water and sediment samples, but never in the trout-free inflow tank. We did not observe an increase in RMS-MLO abundance during the single RMS outbreak recorded nor in relation with the co-occurrence of I. multifiliis. Our findings indicate a long-term persistence of RMS-MLO in the aquaculture, possibly as a consequence of infections with low prevalence or abundance, rather than its entry from the external environment at the time of RMS outbreaks. Additionally, hints were recorded for a potential role of free-living aquatic microeukaryotes as additional occasional reservoirs. In contrast, I. multifiliis was negatively related with RMS-MLO, while it significantly increased in abundance during the RMS outbreak, particularly in the inflow tank. This supports that, rather than a stable reservoir, I. multifiliis may act as a facilitator of RMS outbreaks, which might indeed be triggered by the entry of this parasite in trout farms.

microbiology↗

bioRxiv2026

Metabolic engineering of Escherichia coli strains for the in vivo synthesis of GP-mediated oligosaccharides

Enzymatic synthesis of rare disaccharides by reverse-phosphorolysis is a potentially sustainable route to produce high-value glycosides for human health and nutrition. We report the metabolic engineering of Escherichia coli for in vivo production of {beta}-mannobiose with different osidic linkages from hexose sugars. We demonstrate production of {beta}-1,2-mannobiose with this approach as proof of concept. Phosphotransferase system (PTS) inactivation enables import of non-phosphorylated mannose via heterologous permease GalP, restoring growth on mannose in a PTS- background and allowing mannose into the reverse biosynthetic pathway. Deletion of pfkA, which promotes intracellular accumulation of key sugar phosphates (G1P, M1P), establishes a favorable metabolic chassis for oligosaccharide production using glycoside-phosphorylases. Using this chassis, we expressed two {beta}-mannoside phosphorylases to enable the direct production of {beta}-1,2- and {beta}-1,4-mannobiose from mannose. The same chassis was also employed for laminaribiose production through the expression of a laminaribiose-phosphorylase. pfkA deletion significantly increased product titer (> 0.6 g{middle dot}L-1) and yield (up to 9% g/g mannose), highlighting a favorable redistribution of carbon fluxes toward disaccharide formation. Moreover, a combination of mixed-substrate cultures using glycerol as carbon and energy source and further metabolic engineering enabled partial growth-production decoupling, redirecting mannose utilization primarily toward product synthesis, with a yield of 60%. These results demonstrate the modularity and efficiency of the proposed platform for fermentative production of non-conventional oligosaccharides and expand the scope of metabolic engineering strategies for glycoside biosynthesis.

synthetic biology↗

bioRxiv2021

Drivers of phylogenetic structure in Amazonian freshwater fish assemblages

AimCommunity phylogenetics provides important information about the evolutionary and ecological factors help structure regional species assemblages. Here, we analyze phylogenetic diversity (phylodiversity) patterns among fish species in 97 sub-drainages of the Amazon basin, to evaluate the roles of historical and contemporary processes in generating and maintaining the exceptional richness and endemism of Amazonian fish species assemblages. LocationAmazon River basin TaxonFreshwater fishes MethodsUsing a large comprehensive database of freshwater fish species distributions, and a well-sampled molecular phylogeny of ray-finned (actinopterygian) fishes, we develop of multivariate statistical model to correlate estimated historical and contemporary environmental parameters with sub-drainage phylodiversity patterns. The model employs three phylogenetic metrics: i.e.: phylogenetic diversity (PD) sensu stricto, mean pairwise phylogenetic distance (MPD) between species capturing phylodiversity variation at older evolutionary timescales), and mean nearest taxon distance (MNTD) capturing variation in phylodiversity at younger evolutionary timescales. ResultsThe model recovered significant effects of elevation gradients, contemporary climate, habitat fragmentation, water types, and past marine incursions on assemblage phylodiversity patterns. The model also found significantly negative relationships among the three phylogenetic metrics, and between these metrics and distance to mouth of the Amazon, representing a West-East longitudinal gradient. Main conclusionsOur study revealed a highly non-random spatial and environmental distribution of our three phylogenetic diversity metrics across the 97 sub-drainages of the Amazon basin. Beyond significant regional effects of several environmental and historical drivers, we also found a significant West-East gradient of increasing phylogenetic diversity and phylogenetic relatedness, both patterns suggesting deeper evolutionary divergences among taxa located to the east, and more diverse, more recent radiations in the western sub-drainages. We conclude that western Amazonia can be seen as an evolutionary "cradle" of biodiversity for freshwater fishes in the Amazon basin as a whole. Significance StatementThis manuscript reveals spatial patterns of freshwater fish phylogenetic diversity and relatedness and explains its major contemporary and historical drivers in the Amazon basin. Amazon basin contains the highest freshwater biodiversity on Earth, as so investigate phylogenetic dimension of diversity is extremally relevant from the perspective of understanding the information on the evolutionary processes that had shaped Amazonian contemporary fish assemblages.

ecology↗