Molecular Cross-Talk between Gravity- and Light-Sensing Mechanisms in Euglena gracilis

Microalgae-Derived Microparticles Improve Immunomodulation via Combined Glycolysis and MAPK Activation

Natural polysaccharides possess potent immunostimulatory properties, but their poor solubility impedes efficiency of cellular delivery. This study focuses on extraction of microparticles (MPs) fromEuglena gracilis, a microalgae species characterized by abundant intracellular β-1,3-glucan and flexible cell membrane. We introduce anE. gracilis-derived MP (MPEG) system as a natural carrier for solubilized β-glucan. The MPEG system enhances β-glucan's solubility and loading efficiency through sequential sonication and cell extrusion. In vitro studies reveal that MPEG utilizes multiple endocytosis pathways, including phagocytosis, clathrin-mediated, and lipid raft-mediated routes, for effective β-glucan delivery into cells. Upon cellular internalization, MPEG components trigger dual activation of the MAPK signaling pathway and glycolysis in macrophages, leading to enhanced production of pro-inflammatory cytokines and lactic acid, ultimately strengthening innate immune responses. This MPEG system offers a promising approach to harnessing the immunostimulatory properties of natural polysaccharides while overcoming their solubility limitations, opening new avenues for targeted cellular delivery in immunomodulation therapies.

Euglena, a Gravitactic Flagellate of Multiple Usages

Human exploration of space and other celestial bodies bears a multitude of challenges. The Earth-bound supply of material and food is restricted, and in situ resource utilisation (ISRU) is a prerequisite. Excellent candidates for delivering several services are unicellular algae, such as the space-approved flagellate Euglena gracilis. This review summarizes the main characteristics of this unicellular organism. Euglena has been exposed on various platforms that alter the impact of gravity to analyse its corresponding gravity-dependent physiological and molecular genetic responses. The sensory transduction chain of gravitaxis in E. gracilis has been identified. The molecular gravi-(mechano-)receptors are mechanosensory calcium channels (TRP channels). The inward gated calcium binds specifically to one of several calmodulins (CaM.2), which, in turn, activates an adenylyl cyclase. This enzyme uses ATP to produce cAMP, which induces protein kinase A, followed by the phosphorylation of a motor protein in the flagellum, initiating a course correction, and, finally, resulting in gravitaxis. During long space missions, a considerable amount of food, oxygen, and water has to be carried, and the exhaled carbon dioxide has to be removed. In this context, E. gracilis is an excellent candidate for biological life support systems, since it produces oxygen by photosynthesis, takes up carbon dioxide, and is even edible. Various species and mutants of Euglena are utilized as a producer of commercial food items, as well as a source of medicines, as it produces a number of vitamins, contains numerous trace elements, and synthesizes dietary proteins, lipids, and the reserve molecule paramylon. Euglena has anti-inflammatory, -oxidant, and -obesity properties.

Microgravity and Space Medicine 2.0

This Special Issue (SI), "Microgravity and Space Medicine 2 [...].