Heterosigma akashiwo is a unicellular microalga which can cause massive mortality in both wild and cultivated fish worldwide, resulting in substantial economic losses. Environmental parameters such ...as salinity, light, and temperature showed a significant effect on bloom initiation and the toxicity of H. akashiwo. While in previous studies a one-factor-at-a-time (OFAT) approach was utilized, which only changes one variable at a time while keeping others constant, in the current study a more precise and effective design of experiment (DOE) approach, was used to investigate the simultaneous effect of three factors and their interactions. The study employed a central composite design (CCD) to investigate the effect of salinity, light intensity, and temperature on the toxicity, lipid, and protein production of H. akashiwo. A yeast cell assay was developed to assess toxicity, which offers rapid and convenient cytotoxicity measurements using a lower volume of samples compared to conventional methods using the whole organism. The obtained results showed that the optimum condition for toxicity of H. akashiwo was 25 °C, a salinity of 17.5, and a light intensity of 250 μmol photons msup.−2 ssup.−1. The highest amount of lipid and protein was found at 25 °C, a salinity of 30, and a light intensity of 250 μmol photons msup.−2 ssup.−1. Consequently, the combination of warm water mixing with lower salinity river input has the potential to enhance H. akashiwo toxicity, which aligns with environmental reports that establish a correlation between warm summers and extensive runoff conditions that indicate the greatest concern for aquaculture facilities.
The Nasup.+/Hsup.+ antiporter NhaC family protein is a kind of Nasup.+/Hsup.+ exchanger from the ion transporter (IT) superfamily, which has mainly been identified in the halophilic bacteria of ...Bacillus. However, little is known about the Nasup.+/Hsup.+ antiporter NhaC family of proteins in the extremely halophilic archaea. In this study, two Nasup.+/Hsup.+ antiporter genes, nhaC1 and nhaC2, were screened from the genome of Natronorubrum daqingense based on the gene library and complementation of salt-sensitive Escherichia coli KNabc. A clone vector pUC18 containing nhaC1 or nhaC2 could make KNabc tolerate 0.6 M/0.7 M NaCl or 30 mM/40 mM LiCl and a pH of up to 8.5/9.5, respectively. Functional analysis shows that the Nasup.+(Ksup.+, Lisup.+)/Hsup.+ antiport activities of NhaC1 and NhaC2 are both pH-dependent in the range of pH 7.0–10.0, and the optimal pH is 9.5. Phylogenetic analysis shows that both NhaC1 and NhaC2 belong to the Nasup.+/Hsup.+ antiporter NhaC family of proteins and are significantly distant from the identified NhaC proteins from Bacillus. In summary, we have identified two Nasup.+(Ksup.+, Lisup.+)/Hsup.+ antiporters from N. daqingense.
•Salinity impacts on soils, crops and the environment.•Modelling salinity and leaching requirements.•The FAO56 approach to assess crop ET and its partition when affected by salinity.•Appropriate ...water and irrigation management issues to cope with salinity in agriculture.
Soil and water salinity and associated problems are a major challenge for global food production. Strategies to cope with salinity include a better understanding of the impacts of temporal and spatial dynamics of salinity on soil water balances vis-à-vis evapotranspiration (ET) and devising optimal irrigation schedules and efficient methods. Both steady state and transient models are now available for predicting salinity effects on reduction of crop growth and means for its optimization. This paper presents a brief review on the different approaches available, focusing on the FAO56 framework for coping with the effects of soil salinity on crop ET and yields. The FAO56 approach, applied widely in soil water balance models, is commonly used to compute water requirements, including leaching needs. It adopts a daily stress coefficient (Ks) representing both water and salt stresses to adjust the crop coefficient (Kc) when it is multiplied by the grass reference ETo to obtain the actual crop ET values for saline environments (ETc act = Ks Kc ETo). The same concept is also applied to the dual Kc approach, with Ks used to adjust the basal crop coefficient (Kcb). A review on applications of Ks is presented showing that the FAO56 approach may play an interesting role in water balance computations aimed at supporting irrigation scheduling. Transient state models, through alternative formulations, provide additional solutions for quantification of the salinity build-up in the root zone. These include irrigation-induced salinity, upward movement of salts from saline ground water-table, and sodification processes. Regardless of the approach, these models are now very much capable of supporting irrigation water management in saline stress conditions. For maintaining crop growth under salinity environments, soil-crop-water management interventions consistent with site-specific conditions are then discussed. Adequateness of irrigation methods, cyclic uses of multi-salinity waters and proper irrigation scheduling are further analyzed as examples of efficient means to obviate the effects of salinity.
How to control the frequent occurrence of cyanobacteria, especially the outbreak of toxin-producing Microcystis aeruginosa, has been a subject of constant research. This investigation focused on the ...effect of Moina mongolica on restricting M. aeruginosa blooms under different variables (temperature, light intensity, and salinity) and its growth at the molecular level. The results of batch experiments showed that the range of M. mongolica feeding rates was from 4.02 ± 0.81 × 10sup.3~182.23 ± 5.37 × 10sup.3 cells/ind·h in the whole experiment, where the highest feeding rates of larva M. mongolica and adult M. mongolica were 133.21 ± 5.24 × 10sup.3 vs. 182.23 ± 5.37 × 10sup.3 cells/ind·h at 30 °C, 85.88 ± 0.44 × 10sup.3 vs. 143.15 ± 14.07 × 10sup.3 cells/ind·h at 3000 lx and 88.18 ± 0.32 × 10sup.3 vs. 84.49 ± 4.95 × 10sup.3 cells/ind·h at 0‰ salinity, respectively. The results of transcriptomics further demonstrated that the response of M. mongolica to M. aeruginosa toxicity was caused by the downregulation of relevant functional genes (cell components, cell processes, metabolic processes, and protein complexes) and related signaling pathways (apoptosis, phagosome, lysosome, ribosome, oxidative phosphorylation, amino and nucleoside sugar metabolism, and PPAR signaling pathways). The findings show that M. mongolica can be released to low-salinity lakes and coastal areas (the subtropic and temperate zones) to prevent and inhibit M. aeruginosa blooms in the early summer phase. Additionally, the results achieved by the investigation will provide the relevant technology for inhibiting cyanobacteria blooms because M. mongolica even resists the produced toxin by M. aeruginosa.
Sonneratia caseolaris is a pioneer species in mangrove. It can naturally grow in both saltwater and freshwater. The study was aimed at investigating and comparing the anatomical character of the S. ...caseolaris plants growing in different conditions and how they coped with salinity. The anatomical characteristics of roots, stems, petioles and leaf blade were investigated. The plant samples were prepared into permanent slides using a paraffin method, while the wood samples were made into permanent slides using a sliding microtome technique. Tissue clearing of leaf blade and scanning electron microscopic analysis of wood were performed. In addition, sodium chloride content in various organs and tissues was examined. It was found that cable root, stem and leaf blade showed some different anatomical characteristics between the two conditions. Periderm is a prominent tissue in saltwater roots. Tanniferous cells were observed in pneumatophores, petioles, stems and leaf blades of saltwater plants, but not found in pneumatophores and lamina of freshwater plants. Mesophyll thickness was lower in the saltwater condition. The vessel density was significantly higher in the saltwater condition than in the freshwater condition, whereas the vessel diameters in the freshwater condition were significantly higher than those in the saltwater condition. From the results, it can be concluded that root periderm plays an important role in salt exclusion, and the occurrence of tanniferous cells is associated with salt elimination.
This Special Issue gathers papers reporting research on various aspects of remote sensing of Sea Surface Salinity (SSS) and the use of satellite SSS in oceanography. It includes contributions ...presenting improvements in empirical or theoretical radiative transfer models; mitigation techniques of external interference such as RFI and land contamination; comparisons and validation of remote sensing products with in situ observations; retrieval techniques for improved coastal SSS monitoring, high latitude SSS and the assessment of ocean interactions with the cryosphere; and data fusion techniques combining SSS with sea surface temperature (SST). New instrument technology for the future of SSS remote sensing is also presented.
Fruit-tree rootstock selection is a challenge under a scenario of growing environmental stresses in which the soil and climate are greatly affected. Salinization is an increasing global process that ...severely affects soil fertility. The selection of rootstocks with the ability to tolerate salt stress is essential. Excised root cultures may be an excellent experimental approach to study stress physiology and a predictive tool to assess possible tolerance. In this study, we show how protein changes in response to salt stress evaluated in excised root cultures of Prunus cerasus (moderate salt-sensitive cultivar) could be representative of these changes in the roots of whole plants. The 2D electrophoresis of root extracts and subsequent spot identification by MALDI-TOF/TOF-MS show 16 relevant proteins differentially expressed in roots as a response to 60 mM NaCl. Cytoplasmic isozyme fructose 1,6-bisphosphate aldolase shows relevant changes in its relative presence of isoforms as a response to saline stress, while the total level of enzymes remains similar. Ferredoxin-NADPsup.+ reductase increases as a response to salinity, even though the measured activity is not significantly different. The observed changes are congruent with previous proteomic studies on the roots of whole plants that are involved in protection mechanisms against salt stress.
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