Biology subjects

Dufresne, F.

Publications and source records attributed to Dufresne, F..

3 recordsLinked to original sources

bioRxiv2025

Genetic structure of sugar kelp in the St. Lawrence Estuary and Gulf (Quebec, Canada)

The sugar kelp, Saccharina latissima is cultivated at low scale in Quebec, Canada and current practice involve seeding meiospores or gametophyte stocks onto spools carrying twine and transferring these to a seaweed farm site. As the stocks can originate from locations spanning several hundreds of kilometers from the farm sites, such practice could involve genetic contamination and disrupt local adaptations. Assessing genetic structure can inform of the potential risks associated with this practice. Here we characterized the genetic diversity and structure of S. latissima from locations in the St. Lawrence Estuary and Gulf at both microsatellite loci (308 sporophytes at 22 loci in 16 sites) and genomic markers (228 sporophytes at 6578 single nucleotide polymorphisms in 13 sites). Several populations had low heterozygosity values and significant FIS values at microsatellite loci. No genetic structure was found among populations with microsatellite loci but strong genetic structuring was found with the genomic data. Population structure followed a geographic pattern and was congruent with major currents. Individuals from the wild population in the vicinity of the farm site were genetically distinct from the sporophytes on the growing lines that belong to a genetically distinct group. There was no significant genetic differentiation between wild individuals living in proximity of the farm site and another wild population of the same area. Hence aquaculture practices have not resulted in changes in the genetic composition of the wild population at large scale. Our results are important to guide future conservation efforts and for the seaweed farming industry.

evolutionary biology↗

bioRxiv2021

The origin of asexual brine shrimps

Determining how and how often asexual lineages emerge within sexual species is central to our understanding of sex-asex transitions and the long-term maintenance of sex. Asexuality can arise "by transmission" from an existing asexual lineage to a new one, through different types of crosses. The occurrence of these crosses, cryptic sex, variation in ploidy and recombination within asexuals greatly complicates the study of sex-asex transitions, as they preclude the use of standard phylogenetic methods and genetic distance metrics. In this study we show how to overcome these challenges by developing new approaches to investigate the origin of the various asexual lineages of the brine shrimp Artemia parthenogenetica. We use a large sample of asexuals, including all known polyploids, and their sexual relatives. We combine flow cytometry with mitochondrial and nuclear DNA data. We develop new genetic distance measures and methods to compare various scenarios describing the origin of the different lineages. We find that all diploid and polyploid A. parthenogenetica likely arose within the last 80,000 years through successive and nested hybridization events that involved backcrosses with different sexual species. All A. parthenogenetica have the same common ancestor and therefore likely carry the same asexuality gene(s) and reproduce by automixis. These findings radically change our view of sex-asex transitions in this group, and show the importance of considering asexuality "by transmission" scenarios. The methods developed are applicable to many other asexual taxa.

evolutionary biology↗

bioRxiv2018

Anti-inflammatory properties of natural ingredients used in combinations on adjuvant induced arthritis in rats

Background: Rheumatoid arthritis has seen a significant increase in both incidence and prevalence and its treatments show limited efficiency due to their undesirable effects on patient health. Therefore, major interests lie in the development of treatments with drugs derived from plants or other natural sources with little adverse effects as an alternative to current treatments.\n\nHypothesis/Purpose: The present study evaluates the therapeutic effects of glucosamine against rheumatoid arthritis in combination with hyaluronic acid, resin extract of Boswellia serrata or a bark extract of Salix alba on an animal model. We suggest that combinations with plants could improve the attenuation of arthritis symptoms and articular inflammation.\n\nStudy design: We used Freunds complete adjuvant on rats as models of rheumatoid arthritis. Individuals were separated into eight experimental groups: a control group without arthritis, one with arthritis and without treatment, and six other groups receiving a daily therapeutic treatment from days 14 to 29.\n\nMethods: Hind-paw thickness and arthritis scores were measured at days 0, 3, 6 and 9 post-induction, and then every day from days 12 to 29 with a digital caliper and a score system respectively. At the end of the treatment, the mRNA content of three pro-inflammatory cytokines from cartilage was measured using real-time PCR. The total antioxidant activity was evaluated with an Antioxidant Assay Kit.\n\nResults: Treatments with Boswellia serrata and Salix alba (Glu+Hyal A+Bosw, Glu+Bosw+Sal, Glu+Bosw and Glu+Hyal A+Sal) saw significant reductions in hind-paw thickness and arthritis scores at the end of the experiment when compared to the untreated group. Expression of pro-inflammatory gene IL 17A was also reduced, but only the Glu+Hyal A+Sal combination significantly decreased the expression of IL-1{beta} and TNF-. The total antioxidant activity in blood plasma significantly increased in groups treated with plant extracts.\n\nConclusion: The addition of Boswellia serrata and/or Salix alba attenuates clinical signs of rheumatoid arthritis in Freunds complete adjuvant-induced arthritis in rats likely due to both their anti-inflammatory and antioxidant properties.

pharmacology and toxicology↗