Biology subjects

Le Manach, S.

Publications and source records attributed to Le Manach, S..

3 recordsLinked to original sources

bioRxiv2018

Subcellular localization of microcystin in the liver and the gonad of medaka fish acutely exposed to microcystin-LR

Among the diverse toxic components produced by cyanobacteria, microcystins (MCs) are one of the most toxic and notorious cyanotoxin groups. Besides their potent hepatotoxicity, MCs have been revealed to induce potential reproductive toxicity in various animal studies. However, little is still known regarding the distribution of MCs in the reproductive organ, which could directly affect reproductive cells. In order to respond to this question, an acute study was conducted in adult medaka fish (model animal) gavaged with 10 {micro}g.g-1 body weight of pure MC-LR. The histological and immunohistochemical examinations reveal an intense distribution of MC-LR within hepatocytes along with a severe liver lesion in the toxin-treated female and male fish. Besides being accumulated in the hepatocytes, MC-LR was also found in the connective tissue of the ovary and the testis, as well as in oocytes and degenerative spermatocyte-like structures. Both liver and gonad play important roles in the reproductive process of oviparous vertebrates. This observation constitutes the first observation of the presence of MC-LR in the reproductive cell of a vertebrate model with in vivo study. Our results, which provide intracellular localization of MC-LR in the gonad, advance our understanding of the potential reproductive toxicity of MC-LR in fish.

cell biology↗

bioRxiv2018

Specific metabolic signatures of fish exposed to cyanobacterial blooms

With the increasing impact of the global warming, occurrences of cyanobacterial blooms in aquatic ecosystems are becoming a main ecological concern around the world. Due to their capacity to produce potential toxic metabolites, interactions between the cyanobacteria/cyanotoxin complex and the other freshwater organisms have been widely studied in the past years. Non-targeted metabolomic analyses have the powerful capacity to study a high number of metabolites at the same time and thus to understand in depth the molecular interactions between various organisms in different environmental scenario and notably during cyanobacterial blooms. In this way during summer 2015, liver metabolomes of two fish species, sampled in peri-urban lakes of the ile-de-France region containing or not high concentrations of cyanobacteria, were studied. The results suggest that similar metabolome changes occur in both fish species exposed to cyanobacterial blooms compared to them not exposed. Metabolites implicated in protein synthesis, protection against ROS, steroid metabolism, cell signaling, energy storage and membrane integrity/stability have shown the most contrasted changes. Furthermore, it seems that metabolomic studies will provide new information and research perspectives in various ecological fields and notably concerning cyanobacteria/fish interactions but also a promising tool for environmental monitoring of water pollutions.

ecology↗

bioRxiv2018

Global metabolomic characterizations of Microcystis spp. highlights clonal diversity in natural bloom-forming populations and expands metabolite structural diversity

Cyanobacteria are photosynthetic prokaryotes that are able to synthetize a wild rang of secondary metabolites exhibiting noticeable bioactivity, comprising toxicity. Microcystis represents one of the most common cyanobacteria taxa constituting the intensive blooms that arise nowadays in freshwater ecosystems worldwide. They produce numerous cyanotoxins (toxic metabolites), which are potentially harmful to Human health and aquatic organisms. In order to better understand the variations in cyanotoxins production between clones of the Microcystis, we investigate the diversity of several strains isolated from the same blooms, from different populations in various geographical area.\n\nTwenty-four clonal strains were compared by genotyping with 16S-ITS fragment sequencing and metabolites chemotyping using LC ESI-qTOF mass spectrometry. While, genotyping can only discriminate between the different species, the global metabolomes reveal clear discriminant molecular profiles between strains. These profiles can be clustered primarily according to their global metabolite content, then to their genotype, and finally to their sampling localities. A global molecular network of all metabolites highlights the production of a wide set of chemically diverse metabolites, comprising only few microcystins, but many aeruginosins, cyanopeptolins and microginins, along with a large set of unknown molecules. They represent the molecular biodiversity that still remain to be investigated and characterized at their structure as well as at their potential bioactivity or toxicity levels.

microbiology↗