The Terrestrial Environment and the Origin of Land Vertebrates.

Freezing is a widespread ecological challenge, affecting organisms in over half the terrestrial environment as well as both polar seas. With very few exceptions, if a cell freezes internally, it dies. Polar teleost fish in shallow waters avoid freezing by synthesising a range of protein or glycoprotein antifreezes. Terrestrial organisms are faced with a far greater thermal challenge, and exhibit a more complex array of responses. Unicellular organisms survive freezing temperatures by preventing ice nucleating within the cytosol, and tolerating the cellular dehydration and membrane disruption that follows from ice forming in the external environment. Multicellular organisms survive freezing temperatures by manipulating the composition of the extracellular body fluids. Terrestrial organisms may freeze at high subzero temperatures, often promoted by ice nucleating proteins, and small molecular mass cryoprotectants (often sugars and polyols) moderate the osmotic stress on cells. A range of chaperone proteins (dehydrins, LEA proteins) help maintain the integrity of membranes and macromolecules. Thermal hysteresis (antifreeze) proteins prevent damaging recrystallisation of ice. In some cases arthropods and higher plants prevent freezing in their extracellular fluids and survive by supercooling. Vitrification of extracellular water, or of the cell cytosol, may be a more widespread response to very cold temperatures than recognised to date.

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W. E. KRUMBEIN (Editor), Environmental Biogeochemistry and Geomicrobiology. Vol. 1: The Aquatic Environment. XVII + 394 Seiten, 94 Abb., 70 Tab. Vol. 2: The Terrestrial Environment. XVII + 315 Seiten, 76 Abb., 68 Tab. Vol. 3: Methods, Metals, and Assessment. XVII + 339 Seiten. 96 Abb., 52 Tab. Ann Arbor 1978. Science Publishers Inc. $ 32.50

Zeitschrift für allgemeine Mikrobiologie ◽

10.1002/jobm.3630190825 ◽

1979 ◽

Vol 19 (8) ◽

pp. 594-594

Author(s):

W. Schwartz

Keyword(s):

Aquatic Environment ◽

Terrestrial Environment ◽

Ann Arbor ◽

Environmental Biogeochemistry

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The Effect of Abiotic Factors on Abundance and Photosynthetic Performance of Airborne Cyanobacteria and Microalgae Isolated from the Southern Baltic Sea Region

Cells ◽

10.3390/cells10010103 ◽

2021 ◽

Vol 10 (1) ◽

pp. 103

Author(s):

Kinga Wiśniewska ◽

Sylwia Śliwińska-Wilczewska ◽

Anita Lewandowska ◽

Marta Konik

Keyword(s):

Baltic Sea ◽

Abiotic Factors ◽

Photosynthetic Performance ◽

Culture Collection ◽

Terrestrial Environment ◽

Territorial Expansion ◽

Southern Baltic Sea ◽

Baltic Sea Region ◽

Colonization Potential ◽

Southern Baltic

Cyanobacteria and microalgae present in the aquatic or terrestrial environment may be emitted into the air and transported along with air masses over long distances. As a result of staying in the atmosphere, these organisms may develop a greater tolerance to stressful factors, but this topic is still relatively unknown. The main aim was to show an autecological characteristic of some airborne microalgae and cyanobacteria strains by a factorial laboratory experiment approach, including changes in irradiance, temperature, and salinity conditions. The additional purpose of this work was also to present part of the Culture Collection of Baltic Algae (CCBA) collection, which consists of airborne algae (AA) isolated from the atmospheric air of the southern Baltic Sea region. Altogether, 61 strains of airborne cyanobacteria and microalgae from the southern Baltic Sea region were isolated from May 2018 to August 2020. Selected microorganisms were tested in controlled laboratory conditions to identify their response to different irradiance (10–190 µmol photons m−2 s−1), temperature (13–23 °C), and salinity conditions (0–36 PSU). The highest numbers of cells (above 30 × 105 cell mL−1) were recorded for cyanobacterium Nostoc sp., and for diatoms Nitzschia sp., Amphora sp., and Halamphora sp. We found that for cyanobacterium Nostoc sp. as well as for green alga Coccomyxa sp. the maximum cell concentrations were recorded at the salinity of 0 PSU. Moreover, cyanobacteria Planktolyngbya contorta, Pseudanabaena catenata, Leptolyngbya foveolarum, Gloeocapsa sp., and Rivularia sp. were able to grow only at a salinity of 0 PSU. On the other hand, in the range of 16–24 PSU, the highest cell numbers of examined diatoms have been identified. Our research provided that deposited airborne microalgae and cyanobacteria showed full colonization potential. The present experiment suggests that the adaptive abilities of microorganisms, in particular those producing toxins, may contribute to the spread in the future. Thus, it may increase human exposure to their negative health effects. Any distinctive adaptations of the genera give them an additional competitive advantage and a greater chance for territorial expansion.

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Pathogenic and Compensatory Mechanisms in Epidermis of Sphingomyelin Synthase 2-Deficient Mice

Skin Pharmacology and Physiology ◽

10.1159/000515608 ◽

2021 ◽

pp. 1-7

Author(s):

Shota Sakai ◽

Asami Makino ◽

Akihito Nishi ◽

Takeshi Ichikawa ◽

Tadashi Yamashita ◽

...

Keyword(s):

Plasma Membranes ◽

Lamellar Body ◽

Lipid Mediator ◽

Permeability Barrier ◽

Compensatory Mechanisms ◽

Terrestrial Environment ◽

Sphingomyelin Synthase ◽

Epidermal Permeability Barrier ◽

Deficient Mice

Sphingomyelin (SM) is a constituent of cellular membranes, while ceramides (Cer) produced from SM on plasma membranes serve as a lipid mediator that regulates cell proliferation, differentiation, and apoptosis. In the skin, SM also is a precursor of Cer, an important constituent of epidermal permeability barrier. We investigated the role of epidermal SM synthase (SMS)2, an isoform of SMS, which modulates SM and Cer levels on plasma membranes. Although SMS2-knockout (SMS2-KO) mice were not neonatal lethal, an ichthyotic phenotype with epidermal hyperplasia and hyperkeratosis was evident at birth, which persisted until 2 weeks of age. These mice showed abnormal lamellar body morphology and secretion, and abnormal extracellular lamellar membranes in the stratum corneum. These abnormalities were no longer evident by 4 weeks of age in SMS2-KO mice. Our study suggests that (1) exposure to a dry terrestrial environment initiates compensatory responses, thereby normalizing epidermal ichthyotic abnormalities and (2) that a nonlethal gene abnormality can cause an ichthyotic skin phenotype.

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