Is the meiofauna a good indicator for climate change and anthropogenic impacts?

Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research

Diagnostic sectoriel de main-d’oeuvre de l’industrie québécoise de l’aménagement forestier 2020-2021

Réalisé aux 3 à 5 ans, le diagnostic sectoriel dresse un portrait de la main-d’oeuvre de l’industrie de l’aménagement forestier. Cette étude permet de cerner les défis auxquels le secteur doit faire face et les besoins, particulièrement en ce qui a trait au développement de la main-d'oeuvre et à la formation. Le diagnostic sectoriel occupe une place centrale dans l’effort de collecte et de diffusion d’informations visant la main-d’oeuvre de l’industrie québécoise de l’aménagement forestier. C’est le document de référence sur lequel s’appuie Forêt Compétences pour définir ses priorités d’action et sa planification stratégique, dans le but de développer des projets qui répondent aux besoins du secteur en matière d’emploi. Les objectifs auxquels le diagnostic sectoriel permet de répondre sont: • Obtenir les statistiques à jour relatives à la main-d’oeuvre du secteur; • Approfondir la connaissance des réalités, enjeux, tendances et pratiques de gestion propres au secteur forestier; • Identifier les besoins de main-d’oeuvre, de formation et de perfectionnement

Portrait des entrepreneurs forestiers du Québec 2020-2021

Cette étude vise à réaliser un portrait de l’entrepreneur forestier au Québec. L’objectif est de décrire la situation des entrepreneurs forestiers en approfondissant leurs caractéristiques sociodémographiques, le rapport qu’ils entretiennent avec leur travail et les obstacles à leur développement

Increased Stiffness in Aged Skeletal Muscle Impairs Muscle Progenitor Cell Proliferative Activity

<div><p>Background</p><p>Skeletal muscle aging is associated with a decreased regenerative potential due to the loss of function of endogenous stem cells or myogenic progenitor cells (MPCs). Aged skeletal muscle is characterized by the deposition of extracellular matrix (ECM), which in turn influences the biomechanical properties of myofibers by increasing their stiffness. Since the stiffness of the MPC microenvironment directly impacts MPC function, we hypothesized that the increase in muscle stiffness that occurs with aging impairs the behavior of MPCs, ultimately leading to a decrease in regenerative potential.</p><p>Results</p><p>We showed that freshly isolated individual myofibers from aged mouse muscles contain fewer MPCs overall than myofibers from adult muscles, with fewer quiescent MPCs and more proliferative and differentiating MPCs. We observed alterations in cultured MPC behavior in aged animals, where the proliferation and differentiation of MPCs were lower and higher, respectively. These alterations were not linked to the intrinsic properties of aged myofibers, as shown by the similar values for the cumulative population-doubling values and fusion indexes. However, atomic force microscopy (AFM) indentation experiments revealed a nearly 4-fold increase in the stiffness of the MPC microenvironment. We further showed that the increase in stiffness is associated with alterations to muscle ECM, including the accumulation of collagen, which was correlated with higher hydroxyproline and advanced glycation end-product content. Lastly, we recapitulated the impaired MPC behavior observed in aging using a hydrogel substrate that mimics the stiffness of myofibers.</p><p>Conclusions</p><p>These findings provide novel evidence that the low regenerative potential of aged skeletal muscle is independent of intrinsic MPC properties but is related to the increase in the stiffness of the MPC microenvironment.</p></div

MPCs in aged myofibers display decreased myogenic activity.

<p><b>(A</b>) Histograms showing the total number of MPCs per myofiber on 5–109 freshly isolated and cultured (6 days) myofibers from adult and aged mice (<i>n</i> = 5 mice per group). <b>(B, C)</b> Histograms showing the percentage of quiescent SCs (Pax7⁺MyoD⁻) and proliferating (Pax7⁺MyoD⁺) and differentiating MPCs (Pax7⁻MyoD⁺) per myofiber on intact <b>(B)</b> and damaged <b>(C)</b> myofibers. The Pax7 and MyoD proteins were immunostained as shown in the photomicrograph on the right. The count includes all parts and depths of the myofibers. The representative image on the right shows that Pax7 and MyoD proteins are expressed at lower levels in aged myofibers. **<i>p</i><0.01 and ***<i>p</i><0.0001 versus adult. ^†††<i>p</i><0.001 versus intact counterparts. All data are expressed as means ± SEM.</p

Damaged myofibers from aged mice display robust stiffness that impairs MPC activity.

<p>Graphs showing Young’s modulus values (kPa) and stiffness measurements of freshly isolated (<b>A</b>) and cultured intact and damaged myofibers (<b>B</b>) from adult (<i>n</i> = 3) and aged (<i>n</i> = 5) muscles. One measurement (three force-indentation curves collected for each measurement) per myofiber was performed on 6–50 myofibers. **<i>p</i><0.01; ***<i>p</i><0.0001 versus adult counterpart. ^†††<i>p</i><0.001 versus intact counterpart. All data are expressed as means ± SEM.</p

Aging is associated with increased skeletal muscle stiffness.

<p><b>(A)</b> Representative images of Masson trichrome-stained TA sections from adult and aged male C57Bl/6 mice. <b>(B)</b> Graph showing the quantification of whole muscle stiffness from 100-μm-thick slices of TA and Quad muscles from adult (<i>n</i> = 4) and aged (<i>n</i> = 7) mice. Ten measurements per slice with three force-indentation curves collected per measurement were performed on 3–5 sections for each mouse. (<b>C</b>) Graph showing the biochemical quantification of total hydroxyproline content of Quad muscles from adult (<i>n</i> = 5) and aged (<i>n</i> = 5) mice. <b>(D)</b> Graph showing hydroxyproline values converted to collagen content. (<b>E</b>) Measurement of total advanced glycation end-product (AGE) content of Quad muscles from adult (<i>n</i> = 5) and aged (<i>n</i> = 5) mice. *<i>p</i><0.05; **<i>p</i><0.01; ***<i>p</i><0.0001 versus adult group. All data are expressed as means ± SEM.</p

Hydrogels mimicking myofiber stiffness recapitulate MPC behavior.

<p>Histograms showing the frequency of quiescent, proliferative, and differentiating MPCs (Pax7⁺MyoD^-, Pax7⁺MyoD⁺ and Pax7⁻MyoD⁺, respectively), as a function of hydrogel stiffness (0.5, 2.0, and 18 kPa). Primary myoblasts from adult (<i>n</i> = 5) mice were used for this experiment. Cells were plated and grown for 48 h. The cells were then fixed and stained with DAPI and immunostained with Pax7 and MyoD antibodies. We counted the number of cells in five random fields in four plates for each stiffness preparation. All data are expressed as means ± SEM (*<i>p</i><0.05; **<i>p</i><0.001).</p

Det tør!: Frozen-Ground Cartoons; Et international samarbejde mellem kunstnere og permafrostforskere

This project started in October 2015 with a crazy idea: prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project