Water in cosmetics and Caenorhabditis elegans as an alternative model for lifespan assessment.

OBJECTIVE: Water, often considered a fundamental component of life, is the most commonly used ingredient in the formulation of dermocosmetic products, with waterless products being the exception. Dermocosmetic products can contain anywhere from 50% to 85% water, which contributes to their texture and specific characteristics. The chemical composition of water varies depending on its origin and can be categorized as highly mineralized or low mineralized. These compositions could impact the water's efficacy in anti-aging applications. In this study, the objective is evaluating the anti-aging properties of highly and low mineralized water with the model organism Caenorhabditis elegans. METHODS: In this article, we employed the alternative model organism C. elegans to assess the impact of 5 branded waters, one physiological water and one ultra-pure water on the model's lifespan, using the survival medium conventionally used for C. elegans as a comparison. RESULTS: Waters may have either a positive or a negative impact on the C. elegans lifespan expectancy. Our results indicate that only one of the water brands we assessed (Volvic®) had a significantly positive effect on worm longevity. In contrast, we found that two other brands (Hepar® and Contrex®) had a negative impact on the later stages of the worm's adulthood. Furthermore, we demonstrated that the impact of the brand water samples on lifespan expectancy varied depending on their physicochemical composition, in particular when ion concentrations were most extreme. CONCLUSION: This study shows that the highly mineralized waters studied have a detrimental effect on the survival of C. elegans, and a preliminary test with ultra-pure water could not be completed due to its deleterious effect on the worms. This suggests the hypothesis that both highly mineralized and completely demineralized waters may not be the most suitable for skin formulations.

OBJECTIF: L'eau, élément fondamental à la vie, est l'ingrédient le plus utilisé dans la formulation de produits dermocosmétiques, pour lesquels les produits sans eau restent des exceptions. Les produits dermocosmétiques contiennent 50% à 85% d'eau, contribuant à leurs textures et leurs caractéristiques spécifiques. La composition chimique de l'eau varie en fonction de son origine et peut être catégorisée comme hautement ou faiblement minéralisée. Cette composition peut impacter l'efficacité de l'eau pour ses applications anti-âge. Dans cette étude, l'objectif est d'évaluer les propriétés anti-âge d'eaux fortement ou faiblement minéralisées à l'aide de l'organisme modèle Caenorhabditis elegans. METHODES: Dans ce travail, nous avons utilisé le modèle alternatif C. elegans pour étudier l'impact de 5 marques d'eaux, du sérum physiologique et de l'eau ultrapure sur ce modèle, en utilisant le milieu de culture standard de C. elegans comme contrôle. RESULTATS: Les eaux peuvent avoir un impact positif ou négatif sur la longévité des C. elegans. Nos résultats indiquent que seule l'une des eaux étudiées (Volvic®) a un impact positif sur la longévité des nématodes. Au contraire, nous avons montré que 2 autres eaux (Hepar® and Contrex®) ont un impact négatif sur les derniers stades adultes. De plus, nous avons démontré que l'impact des eaux sur la longévité variait en fonction de leurs compositions physicochimiques, en particulier lorsque les concentrations ioniques sont extrêmes.

Deciphering Differential Life Stage Radioinduced Reproductive Decline in Caenorhabditis elegans through Lipid Analysis.

Wildlife is chronically exposed to various sources of ionizing radiations, both environmental or anthropic, due to nuclear energy use, which can induce several defects in organisms. In invertebrates, reproduction, which directly impacts population dynamics, has been found to be the most radiosensitive endpoint. Understanding the underlying molecular pathways inducing this reproduction decrease can help in predicting the effects at larger scales (i.e., population). In this study, we used a life stage dependent approach in order to better understand the molecular determinants of reproduction decrease in the roundworm C. elegans. Worms were chronically exposed to 50 mGy·h-1 external gamma ionizing radiations throughout different developmental periods (namely embryogenesis, gametogenesis, and full development). Then, in addition to reproduction parameters, we performed a wide analysis of lipids (different class and fatty acid via FAMES), which are both important signaling molecules for reproduction and molecular targets of oxidative stress. Our results showed that reproductive defects are life stage dependent, that lipids are differently misregulated according to the considered exposure (e.g., upon embryogenesis and full development) and do not fully explain radiation induced reproductive defects. Finally, our results enable us to propose a conceptual model of lipid signaling after radiation stress in which both the soma and the germline participate.

A comparative ultrastructure study of the tardigrade Ramazzottius varieornatus in the hydrated state, after desiccation and during the process of rehydration.

Tardigrades can survive hostile environments such as desiccation by adopting a state of anhydrobiosis. Numerous tardigrade species have been described thus far, and recent genome and transcriptome analyses revealed that several distinct strategies were employed to cope with harsh environments depending on the evolutionary lineages. Detailed analyses at the cellular and subcellular levels are essential to complete these data. In this work, we analyzed a tardigrade species that can withstand rapid dehydration, Ramazzottius varieornatus. Surprisingly, we noted an absence of the anhydrobiotic-specific extracellular structure previously described for the Hypsibius exemplaris species. Both Ramazzottius varieornatus and Hypsibius exemplaris belong to the same evolutionary class of Eutardigrada. Nevertheless, our observations reveal discrepancies in the anhydrobiotic structures correlated with the variation in the anhydrobiotic mechanisms.

Targeted Central Nervous System Irradiation with Proton Microbeam Induces Mitochondrial Changes in Caenorhabditis elegans.

Fifty percent of all patients with cancer worldwide require radiotherapy. In the case of brain tumors, despite the improvement in the precision of radiation delivery with proton therapy, studies have shown structural and functional changes in the brains of treated patients with protons. The molecular pathways involved in generating these effects are not completely understood. In this context, we analyzed the impact of proton exposure in the central nervous system area of Caenorhabditis elegans with a focus on mitochondrial function, which is potentially implicated in the occurrence of radiation-induced damage. To achieve this objective, the nematode C. elegans were micro-irradiated with 220 Gy of protons (4 MeV) in the nerve ring (head region) using the proton microbeam, MIRCOM. Our results show that protons induce mitochondrial dysfunction, characterized by an immediate dose-dependent loss of the mitochondrial membrane potential (ΔΨm) associated with oxidative stress 24 h after irradiation, which is itself characterized by the induction of the antioxidant proteins in the targeted region, observed using SOD-1::GFP and SOD-3::GFP strains. Moreover, we demonstrated a two-fold increase in the mtDNA copy number in the targeted region 24 h after irradiation. In addition, using the GFP::LGG-1 strain, an induction of autophagy in the irradiated region was observed 6 h following the irradiation, which is associated with the up-regulation of the gene expression of pink-1 (PTEN-induced kinase) and pdr-1 (C. elegans parkin homolog). Furthermore, our data showed that micro-irradiation of the nerve ring region did not impact the whole-body oxygen consumption 24 h following the irradiation. These results indicate a global mitochondrial dysfunction in the irradiated region following proton exposure. This provides a better understanding of the molecular pathways involved in radiation-induced side effects and may help in finding new therapies.

Ultrastructural analysis of the dehydrated tardigrade Hypsibius exemplaris unveils an anhydrobiotic-specific architecture.

Tardigrades can cope with adverse environmental conditions by turning into anhydrobiotes with a characteristic tun shape. Tun formation is an essential morphological adaptation for tardigrade entry into the anhydrobiotic state. The tun cell structure and ultrastructure have rarely been explored in tardigrades in general and never in Hypsibius exemplaris. We used transmission electron microscopy to compare cellular organization and ultrastructures between hydrated and anhydrobiotic H. exemplaris. Despite a globally similar cell organelle structure and a number of cells not significantly different between hydrated and desiccated tardigrades, reductions in the sizes of both cells and mitochondria were detected in dehydrated animals. Moreover, in anhydrobiotes, secretory active cells with a dense endoplasmic reticulum network were observed. Interestingly, these anhydrobiote-specific cells are in a close relationship with a specific extracellular structure surrounding each cell. It is possible that this rampart-like extracellular structure resulted from the accumulation of anhydrobiotic-specific material to protect the cells. Interestingly, after five hours of rehydration, the number of secretory cells decreased, and the specific extracellular structure began to disappear. Twenty-four hours after the beginning of rehydration, the cellular structure and ultrastructure were comparable to those observed in hydrated tardigrades.

Defining the viability of tardigrades with a molecular sensor related to death.

The design of experimental protocols that use animal models to assess the impact of a stress on a population or to determine the life span expectancy impact can be time-consuming due to the need for direct observations of dead and living animals. These experiments are usually based on the detectable activity of animals such as food intake or mobility and can sometimes produce either under- or overestimated results. The tardigrade Hypsibius exemplaris is an emerging model for the evolutionary biology of the tardigrade phylum because of its convenient laboratory breeding and the recent introduction of new molecular tools. In this report, we describe the use of a new fluorescent dye that can specifically stain dead tardigrades. Furthermore, we also monitored the absence of a toxic side effect of the death-linked fluorescent dye on tardigrade populations. Finally, we conclude that tardigrade experiments that require survival counting of the Hypsibius exemplaris species can be greatly improved by using this technique in order to limit underestimation of alive animals.

Carbonylation accumulation of the Hypsibius exemplaris anhydrobiote reveals age-associated marks.

Together with nematodes and rotifers, tardigrade belong to micrometazoans that can cope with environmental extremes such as UV and solar radiations, dehydration, supercooling or overheating. Tardigrade can resist the harshest conditions by turning to cryptobiosis, an anhydrobiotic state that results from almost complete dehydration and is characterized by an ametabolic status. Although reports have challenged the molecular basis of the mechanisms underlying genomic injury resistance, little is yet known regarding the possible involvement of other tardigrade macromolecules in injury during a stress experience. In this report, we show that the tardigrade Hypsibius exemplaris can accumulate molecular damages by means of in situ detection of carbonyls. Furthermore, we demonstrate that living tardigrade can accumulate carbonylation. Finally, we reveal that anhydrobiotic tardigrade can be constitutively affected by carbonylation that marks aging in other metazoans.

Crosses prior to parthenogenesis explain the current genetic diversity of tropical plant-parasitic Meloidogyne species (Nematoda: Tylenchida).

The tropical and subtropical parthenogenetic plant-parasitic nematodes Meloidogyne are polyphagous major agricultural pests. Implementing proper pest management approaches requires a good understanding of mechanisms, population structure, evolutionary patterns and species identification. A comparative analysis of the mitochondrial vs nuclear diversity was conducted on a selected set of Meloidogyne lines from various geographic origins. Mitochondrial co2-16S sequences and AFLP markers of total DNA were applied because of their ability to evidence discrete genetic variation between closely related isolates. Several distinct maternal lineages were present, now associated with different genetic backgrounds. Relative discordances were found when comparing mitochondrial and nuclear diversity patterns. These patterns are most likely related to crosses within one ancestral genetic pool, followed by the establishment of parthenogenesis. In this case, they mirror the genetic backgrounds of the original individuals. Another aspect could be that species emergence was recent or on process from this original genetic pool and that the relatively short time elapsed since then and before parthenogenesis settlement did not allow for lineage sorting. This could also be compatible with the hypothesis of hybrids between closely related species. This genetic pool would correspond to a species as defined by the species interbreeding concept, but also including the grey area of species boundaries. This complex process has implications on the way genotypic and phenotypic diversity should be addressed. The phenotype of parthenogenetic lines is at least for part determined by the ancestral amphimictic genetic background. A direct consequence is, therefore, in terms of risk management, the limited confidence one can have on the direct association of an agronomic threat to a simple typing or species delineation. Risk management strategies and tools must thus consider this complexity when designing quarantine implementation, resistance breeding programmes or molecular diagnostic.