2 research outputs found
The modulation of leaf metabolism plays a role in salt tolerance of Cymodocea nodosa exposed to hypersaline stress in mesocosms
Applying proteomics, we tested the physiological responses of the euryhaline seagrass
Cymodocea nodosa to deliberate manipulation of salinity in a mesocosm system.
Plants were subjected to a chronic hypersaline condition (43 psu) to compare protein
expression and plant photochemistry responses after 15 and 30 days of exposure
with those of plants cultured under normal/ambient saline conditions (37 psu). Results
showed a general decline in the expression level of leaf proteins in hypersaline stressed
plants, with more intense reductions after long-lasting exposure. Specifically, the
carbon-fixing enzyme RuBisCo displayed a lower accumulation level in stressed plants
relative to controls. In contrast, the key enzymes involved in the regulation of glycolysis,
cytosolic glyceraldehyde-3-phosphate dehydrogenase, enolase 2 and triose-phosphate
isomerase, showed significantly higher accumulation levels. These responses suggested
a shift in carbon metabolism in stressed plants. Hypersaline stress also induced a
significant alteration of the photosynthetic physiology of C. nodosa by means of a downregulation
in structural proteins and enzymes of both PSII and PSI. However we found
an over-expression of the cytochrome b559 alpha subunit of the PSII initial complex,
which is a receptor for the PSII core proteins involved in biogenesis or repair processes
and therefore potentially involved in the absence of effects at the photochemical level
of stressed plants. As expected hypersalinity also affects vacuolar metabolism by
increasing the leaf cell turgor pressure and enhancing the up-take of Na+ by overaccumulating
the tonoplast specific intrinsic protein pyrophosphate-energized inorganic
pyrophosphatase (H(+)-PPase) coupled to the Na+/H+-antiporter. The modulation of
carbon metabolism and the enhancement of vacuole capacity in Na+ sequestration and
osmolarity changes are discussed in relation to salt tolerance of C. nodosa.Postprin
Experimental simulation of environmental warming selects against pigmented morphs of land snails
H-R.K. and R.T. were gratefully hosted by INRA-PACA, Avignon, France, during the time of fieldwork in 2017. We gratefully acknowledge assistance in the field and with the open-top chamber experiments by Nik Triebskorn and Tim Triebskorn. The 35 field sites were sampled within the 2018 European Theba survey initiated by H-R.K and Thomas Knigge, Le Havre University, France. We also thank Menno Schilthuizen, Leiden University, the Netherlands, and another anonymous reviewer for constructive remarks on a previous manuscript version. Open access funding enabled and organized by ProjektDEAL.In terrestrial snails, thermal selection acts on shell coloration. However, the biological relevance of small differences in the intensity of shell pigmentation and the associated thermodynamic, physiological, and evolutionary consequences for snail diversity within the course of environmental warming are still insufficiently understood. To relate temperature‐driven internal heating, protein and membrane integrity impairment, escape behavior, place of residence selection, water loss, and mortality, we used experimentally warmed open‐top chambers and field observations with a total of >11,000 naturally or experimentally colored individuals of the highly polymorphic species Theba pisana (O.F. MÜLLER, 1774). We show that solar radiation in their natural Mediterranean habitat in Southern France poses intensifying thermal stress on increasingly pigmented snails that cannot be compensated for by behavioral responses. Individuals of all morphs acted neither jointly nor actively competed in climbing behavior, but acted similarly regardless of neighbor pigmentation intensity. Consequently, dark morphs progressively suffered from high internal temperatures, oxidative stress, and a breakdown of the chaperone system. Concomitant with increasing water loss, mortality increased with more intense pigmentation under simulated global warming conditions. In parallel with an increase in mean ambient temperature of 1.34°C over the past 30 years, the mortality rate of pigmented individuals in the field is, currently, about 50% higher than that of white morphs. A further increase of 1.12°C, as experimentally simulated in our study, would elevate this rate by another 26%. For 34 T. pisana populations from locations that are up to 2.7°C warmer than our experimental site, we show that both the frequency of pigmented morphs and overall pigmentation intensity decrease with an increase in average summer temperatures. We therefore predict a continuing strong decline in the frequency of pigmented morphs and a decrease in overall pigmentation intensity with ongoing global change in areas with strong solar radiation.ProjektDEA