Light, Temperature, and Desiccation Effects on Photosynthetic Activity, and Drought-Induced Ultrastructural Changes in the Green Alga Klebsormidium dissectum (Streptophyta) from a High Alpine Soil Crust

2011 ◽  
Vol 63 (1) ◽  
pp. 51-63 ◽  
Author(s):  
Ulf Karsten ◽  
Andreas Holzinger
Keyword(s):  
Green Alga ◽  
Photosynthetic Activity ◽  
Ultrastructural Changes ◽  
Soil Crust ◽  
Alpine Soil

Response of short-term heat shock on photosynthetic activity of soil crust cyanobacteria

PROTOPLASMA ◽  
2019 ◽  
Vol 257 (1) ◽  
pp. 61-73
Author(s):  
Jana Kvíderová ◽  
Dhanesh Kumar
Keyword(s):  
Heat Shock ◽  
Photosynthetic Activity ◽  
Soil Crust ◽  
Short Term

Stepwise adaptation to salinity in the green alga Nannochloris bacillaris

1985 ◽  
Vol 63 (2) ◽  
pp. 327-332 ◽  
Author(s):  
Lewis M. Brown
Keyword(s):  
Water Potential ◽  
Green Alga ◽  
Fold Increase ◽  
Ultrastructural Changes ◽  
Intermediate Step ◽  
Volume Changes ◽  
Short Term ◽  
Water Potentials ◽  
Salinity Increase ◽  
Adaptation To Salinity

A severe inhibitory decrease in water potential owing to salinity increase (ψ = −0.2 to −5.5 MPa) was tolerated in Nannochloris bacillaris Naumann if an intermediate salinity step at ψ = −2.6 MPa was provided. Photosynthesis, respiration, and growth were all enhanced by the provision of an intermediate step. The length of time of the application of the intermediate salinity step was critical to the resulting abilities of the cells to exhibit substantial adaptation. Increasing the length of the intermediate step from 10 to 120 min resulted in a 168-fold increase in the rate of photoassimilation of bicarbonate. Adaptation of other functions (e.g., growth) took much longer. The effects of pulse shocks, downward then upward water potentials, indicated that when there was an inhibition of photosynthesis and it was irreversible over the short term. Pulse shocks to noninhibitory water potentials did not cause inhibition. These results were correlated with measurements of volume changes, rates of excretion of solutes, and ultrastructural changes.

scholarly journals The response of desert biocrust bacterial communities to hydration-desiccation cycles

2021 ◽  
Author(s):  
Capucine Baubin ◽  
Osnat Gillor ◽  
Noya Ran ◽  
Hagar Siebner
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
Photosynthetic Activity ◽  
Biological Soil Crust ◽  
Rain Event ◽  
Arid Environments ◽  
Soil Crust ◽  
Bacterial Composition ◽  
Soil Bacterial Communities ◽  
Rain Events

Rain events in arid environments are highly unpredictable, interspersing extended periods of drought. Therefore, following changes in desert soil bacterial communities during hydration-desiccation cycles in the field, was seldom attempted. Here, we assessed rain-mediated dynamics of active community in the Negev Desert biological soil crust (biocrust), and evaluated the changes in bacterial composition, potential function, and photosynthetic activity. We predicted that increased biocrust moisture would resuscitate the phototrophs, while desiccation would inhibit their activity. Our results show that hydration increased chlorophyll content, resuscitated the biocrust Cyanobacteria, and induced potential phototrophic functions. However, decrease in the soil water content did not immediately decrease the phototrophs activity, though chlorophyll levels decreased. Moreover, while the Cyanobacteria relative abundance significantly increased, Actinobacteria, the former dominant taxa, significantly decreased in abundance. We propose that, following a rain event biocrust moisture significantly decreased, almost to drought levels, yet the response of the active bacterial community lagged, in contrast to topsoil. Possible explanations to the described rain-mediated bacteria dynamics are discussed.

Changes in the pigment patterns and the photosynthetic activity during a light-induced cell cycle of the green alga Scenedesmus armatus

2003 ◽  
Vol 41 (4) ◽  
pp. 337-344 ◽  
Author(s):  
Zbigniew Tukaj ◽  
Krystyna Matusiak-Mikulin ◽  
Justyna Lewandowska ◽  
Janusz Szurkowski
Keyword(s):  
Cell Cycle ◽  
Green Alga ◽  
Photosynthetic Activity ◽  
Pigment Patterns

Regulation of Glycinebetaine Accumulation in the Halotolerant Cyanobacterium Aphanothece halophytica

1993 ◽  
Vol 20 (6) ◽  
pp. 693 ◽  
Author(s):  
M Ishitani ◽  
T Takabe ◽  
K Kojima ◽  
T Takabe
Keyword(s):  
Salt Stress ◽  
Co2 Fixation ◽  
Photosynthetic Activity ◽  
Higher Plants ◽  
Control Culture ◽  
Ultrastructural Changes ◽  
Intracellular Level ◽  
Aphanothece Halophytica ◽  
Order Of Magnitude ◽  
Halotolerant Cyanobacterium

When cells of the halotolerant cyanobacterium, Aphanothece halophytica were transferred from control culture medium that contained 0.5 M NaCl to a hypersaline medium with either 1.5 M or 2.0 M NaCl, the rate of photosynthetic CO2 fixation fell instantaneously. Subsequently, the photosynthetic activity returned to almost the original level within 1 day. Under salt stress, ultrastructural changes in the cells were observed by electron microscopy, these cells appeared to recover in parallel with the recovery of their photosynthetic activity. However, the intracellular level of glycinebetaine increased more slowly than the recovery of the photosynthetic CO2 fixation. The maximum rate of accumulation of betaine was estimated to be approximately 60 nmol (mg protein)-1 h-1. This rate is at least one order of magnitude greater than rates reported previously in leaves of salt-stressed higher plants. The accumulation of betaine did not take place in the dark. The intracellular level of betaine decreased as a result of the transfer of the cells to a hypo-osmotic NaCl-containing medium. The accumulation of betaine was also induced by an organic osmoticum, sorbitol. Nitrate enhances the accumulation of betaine under salt stress.

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