-
Physiologia Plantarum Jun 2021Drought stress, which causes a decline in quality and quantity of crop yields, has become more accentuated these days due to climatic change. Serious measures need to be... (Review)
Review
Drought stress, which causes a decline in quality and quantity of crop yields, has become more accentuated these days due to climatic change. Serious measures need to be taken to increase the tolerance of crop plants to acute drought conditions likely to occur due to global warming. Drought stress causes many physiological and biochemical changes in plants, rendering the maintenance of osmotic adjustment highly crucial. The degree of plant resistance to drought varies with plant species and cultivars, phenological stages of the plant, and the duration of plant exposure to the stress. Osmoregulation in plants under low water potential relies on synthesis and accumulation of osmoprotectants or osmolytes such as soluble proteins, sugars, and sugar alcohols, quaternary ammonium compounds, and amino acids, like proline. This review highlights the role of osmolytes in water-stressed plants and of enzymes entailed in their metabolism. It will be useful, especially for researchers working on the development of drought-resistant crops by using the metabolic-engineering techniques.
Topics: Droughts; Osmoregulation; Osmosis; Proline; Stress, Physiological; Water
PubMed: 33280137
DOI: 10.1111/ppl.13297 -
FEMS Yeast Research Aug 2022In response to osmotic dehydration cells sense, signal, alter gene expression, and metabolically counterbalance osmotic differences. The main compatible solute/osmolyte... (Review)
Review
In response to osmotic dehydration cells sense, signal, alter gene expression, and metabolically counterbalance osmotic differences. The main compatible solute/osmolyte that accumulates in yeast cells is glycerol, which is produced from the glycolytic intermediate dihydroxyacetone phosphate. This review covers recent advancements in understanding mechanisms involved in sensing, signaling, cell-cycle delays, transcriptional responses as well as post-translational modifications on key proteins in osmoregulation. The protein kinase Hog1 is a key-player in many of these events, however, there is also a growing body of evidence for important Hog1-independent mechanisms playing vital roles. Several missing links in our understanding of osmoregulation will be discussed and future avenues for research proposed. The review highlights that this rather simple experimental system-salt/sorbitol and yeast-has developed into an enormously potent model system unravelling important fundamental aspects in biology.
Topics: Glycerol; Osmoregulation; Osmotic Pressure; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Water-Electrolyte Balance
PubMed: 35927716
DOI: 10.1093/femsyr/foac035 -
Comprehensive Physiology Apr 2014The article discusses advances in osmoregulation and excretion with emphasis on how multicellular animals in different osmotic environments regulate their milieu... (Review)
Review
The article discusses advances in osmoregulation and excretion with emphasis on how multicellular animals in different osmotic environments regulate their milieu intérieur. Mechanisms of energy transformations in animal osmoregulation are dealt with in biophysical terms with respect to water and ion exchange across biological membranes and coupling of ion and water fluxes across epithelia. The discussion of functions is based on a comparative approach analyzing mechanisms that have evolved in different taxonomic groups at biochemical, cellular and tissue levels and their integration in maintaining whole body water and ion homeostasis. The focus is on recent studies of adaptations and newly discovered mechanisms of acclimatization during transitions of animals between different osmotic environments. Special attention is paid to hypotheses about the diversity of cellular organization of osmoregulatory and excretory organs such as glomerular kidneys, antennal glands, Malpighian tubules and insect gut, gills, integument and intestine, with accounts on experimental approaches and methods applied in the studies. It is demonstrated how knowledge in these areas of comparative physiology has expanded considerably during the last two decades, bridging seminal classical works with studies based on new approaches at all levels of anatomical and functional organization. A number of as yet partially unanswered questions are emphasized, some of which are about how water and solute exchange mechanisms at lower levels are integrated for regulating whole body extracellular water volume and ion homeostasis of animals in their natural habitats. © 2014 American Physiological Society.
Topics: Adaptation, Physiological; Animals; Biological Transport; Osmoregulation; Physiology, Comparative; Water-Electrolyte Balance
PubMed: 24715560
DOI: 10.1002/cphy.c130004 -
Biochimica Et Biophysica Acta.... May 2021This review provides a retrospective on the role of osmotic regulation in the process of eukaryogenesis. Specifically, it focuses on the adjustments which must have been... (Review)
Review
This review provides a retrospective on the role of osmotic regulation in the process of eukaryogenesis. Specifically, it focuses on the adjustments which must have been made by the original colonizing α-proteobacteria that led to the evolution of modern mitochondria. We focus on the cations that are fundamentally involved in volume determination and cellular metabolism and define the transporter landscape in relation to these ions in mitochondria as we know today. We provide analysis on how the cations interplay and together maintain osmotic balance that allows for effective ATP synthesis in the organelle.
Topics: Animals; Cations; Evolution, Molecular; Humans; Ion Transport; Mitochondria; Osmoregulation
PubMed: 33422486
DOI: 10.1016/j.bbabio.2021.148368 -
The Journal of Endocrinology May 1988
Review
Topics: Animals; Humans; Thirst; Water-Electrolyte Balance
PubMed: 3288704
DOI: 10.1677/joe.0.1170155 -
Comparative Biochemistry and... Mar 2021In his early career, August Krogh made fundamental discoveries of the properties of cutaneous respiration in fish, frogs and other vertebrates. Following Krogh's... (Review)
Review
In his early career, August Krogh made fundamental discoveries of the properties of cutaneous respiration in fish, frogs and other vertebrates. Following Krogh's example, the study of amphibious fishes provides an excellent model to understand how the skin morphology and physiological mechanisms evolved to meet the dual challenges of aquatic and terrestrial environments. The skin of air-exposed fishes takes on many of the functions that are typically associated with the gills of fish in water: gas exchange, gas sensing, iono- and osmoregulation, and nitrogen excretion. The skin of amphibious fishes has capillaries close to the surface in the epidermis. Skin ionocytes or mitochondrial-rich cells (MRCs) in the epidermis are thought to be responsible for ion exchange, as well as ammonia excretion in the amphibious mangrove rivulus Kryptolebias marmoratus. Ammonia gas (NH) moves down the partial pressure gradient from skin capillaries to the surface through ammonia transporters (e.g., Rhcg) and NH is volatilized from the mucus film on the skin. Future studies are needed on the skin of amphibious fishes from diverse habitats to understand more broadly the role of the skin as a multifunctional organ.
Topics: Animals; Cyprinodontiformes; Ecosystem; Gills; Models, Biological; Nitrogen; Osmoregulation; Respiratory Physiological Phenomena; Skin Physiological Phenomena; Water
PubMed: 33301892
DOI: 10.1016/j.cbpa.2020.110866 -
Comparative Biochemistry and... Mar 2021August Krogh's studies of the frog identified the respiratory function of the skin in 1904 and the osmoregulatory function of the skin in 1937. It is the thesis of my... (Review)
Review
August Krogh's studies of the frog identified the respiratory function of the skin in 1904 and the osmoregulatory function of the skin in 1937. It is the thesis of my review that the osmoregulatory function of the skin has evolved for meeting quite different demands. In freshwater the body fluid homeostasis is challenged by loss of ions to the environment. This is compensated for by active ion uptake energized by the sodium-pump ATPase and the V-type proton pump ATPase. I conclude that Krogh's astonishing observation of cutaneous chloride uptake from μM concentrations of NaCl is compatible with the free energy changes of ATP hydrolysis catalyzed by the sodium‑potassium pump ATPase and the V-type proton pump ATPase operating in series, and in parallel with experimentally verified vanishingly small leak fluxes. On land the frog is challenged by evaporative water loss through the highly water permeable skin, similar to the water permeable conducting airways of terrestrial vertebrates including man. The epithelia serving respiratory gas exchanges are heterocellular and have molecular, structural and functional properties in common. The cutaneous surface liquid of amphibians evolved for protecting the skin epithelium from desiccation like the airway surface liquid of the lung. Published studies of ion transport mechanisms of acinar cells and the two types of epithelial cells, lead to the hypothesis that subepithelial gland secretion, evaporative water loss, and ion reabsorption by the epithelium regulate composition and volume of the cutaneous surface liquid.
Topics: Animals; Anura; Epithelial Cells; Epithelium; Ion Transport; Osmoregulation; Skin Physiological Phenomena; Sodium-Potassium-Exchanging ATPase; Vacuolar Proton-Translocating ATPases; Water-Electrolyte Balance
PubMed: 33326845
DOI: 10.1016/j.cbpa.2020.110869 -
Annual Review of Entomology Jan 2024Water is essential to life. Terrestrial insects lose water by evaporation from the body surface and respiratory surfaces, as well as in the excretory products, posing a... (Review)
Review
Water is essential to life. Terrestrial insects lose water by evaporation from the body surface and respiratory surfaces, as well as in the excretory products, posing a challenge made more acute by their high surface-to-volume ratio. These losses must be kept to a minimum and be offset by water gained from other sources. By contrast, insects such as the blood-sucking bug consume up to 10 times their body weight in a single blood meal, necessitating rapid expulsion of excess water and ions. How do insects manage their ion and water budgets? A century of study has revealed a great deal about the organ systems that insects use to maintain their ion and water balance and their regulation. Traditionally, a taxonomically wide range of species were studied, whereas more recent research has focused on model organisms to leverage the power of the molecular genetic approach. Key advances in new technologies have become available for a wider range of species in the past decade. We document how these approaches have already begun to inform our understanding of the diversity and conservation of insect systemic osmoregulation. We advocate that these technologies be combined with traditional approaches to study a broader range of nonmodel species to gain a comprehensive overview of the mechanism underpinning systemic osmoregulation in the most species-rich group of animals on earth, the insects.
Topics: Animals; Osmoregulation; Earth, Planet; Insecta; Water
PubMed: 37758224
DOI: 10.1146/annurev-ento-040323-021222 -
The Journal of Experimental Biology May 2017Osmoregulation is by no means an energetically cheap process, and its costs have been extensively quantified in terms of respiration and aerobic metabolism. Common... (Review)
Review
Osmoregulation is by no means an energetically cheap process, and its costs have been extensively quantified in terms of respiration and aerobic metabolism. Common products of mitochondrial activity are reactive oxygen and nitrogen species, which may cause oxidative stress by degrading key cell components, while playing essential roles in cell homeostasis. Given the delicate equilibrium between pro- and antioxidants in fueling acclimation responses, the need for a thorough understanding of the relationship between salinity-induced oxidative stress and osmoregulation arises as an important issue, especially in the context of global changes and anthropogenic impacts on coastal habitats. This is especially urgent for intertidal/estuarine organisms, which may be subject to drastic salinity and habitat changes, leading to redox imbalance. How do osmoregulation strategies determine energy expenditure, and how do these processes affect organisms in terms of oxidative stress? What mechanisms are used to cope with salinity-induced oxidative stress? This Commentary aims to highlight the main gaps in our knowledge, covering all levels of organization. From an energy-redox perspective, we discuss the link between environmental salinity changes and physiological responses at different levels of biological organization. Future studies should seek to provide a detailed understanding of the relationship between osmoregulatory strategies and redox metabolism, thereby informing conservation physiologists and allowing them to tackle the new challenges imposed by global climate change.
Topics: Acclimatization; Animals; Aquatic Organisms; Ecosystem; Energy Metabolism; Invertebrates; Osmoregulation; Oxidative Stress; Salinity
PubMed: 28515169
DOI: 10.1242/jeb.135624 -
Journal of Neuroendocrinology Mar 2021Part of the life cycle of several fish species includes important salinity changes, as is the case for the sea bass (Dicentrarchus labrax) or the Atlantic salmon (Salmo... (Review)
Review
Part of the life cycle of several fish species includes important salinity changes, as is the case for the sea bass (Dicentrarchus labrax) or the Atlantic salmon (Salmo salar). Salmo salar juveniles migrate downstream from their spawning sites to reach seawater, where they grow and become sexually mature. The process of preparation enabling juveniles to migrate downstream and physiologically adapt to seawater is called smoltification. Daily and seasonal variations of photoperiod and temperature play a role in defining the timing of smoltification, which may take weeks to months, depending on the river length and latitude. Smoltification is characterised by a series of biochemical, physiological and behavioural changes within the neuroendocrine axis. This review discusses the current knowledge and gaps related to the neuroendocrine mechanisms that mediate the effects of light and temperature on smoltification. Studies performed in S. salar and other salmonids, as well as in other species undergoing important salinity changes, are reviewed, and a particular emphasis is given to the pineal hormone melatonin and its possible role in osmoregulation. The daily and annual variations of plasma melatonin levels reflect corresponding changes in external photoperiod and temperature, which suggests that the hormonal time-keeper melatonin might contribute to controlling smoltification. Here, we review studies on (i) the impact of pinealectomy and/or melatonin administration on smoltification; (ii) melatonin interactions with hormones involved in osmoregulation (e.g., prolactin, growth hormone and cortisol); (iii) the presence of melatonin receptors in tissues involved in osmoregulation; and (iv) the impacts of salinity changes on melatonin receptors and circulating melatonin levels. Altogether, these studies show evidence indicating that melatonin interacts with the neuroendocrine pathways controlling smoltification, although more information is needed to clearly decipher its mechanisms of action.
Topics: Animals; Fishes; Fresh Water; Melatonin; Osmoregulation; Salmo salar; Seasons; Seawater
PubMed: 33769643
DOI: 10.1111/jne.12955