Search Results (112)

Invasive fish species are a major driver of freshwater native fish biodiversity loss and their spread and impacts on the native fish are expected to increase within the current freshwater salinization and global warming crisis. In the current study, the upper thermal and salinity tolerance of the geographically range-restricted, threatened killifish Valencia robertae and its alien competitor, the globally invasive Eastern mosquitofish Gambusia holbrooki are compared in an experimental setting. Fish were exposed, after acclimation, to a continuous, dynamic temperature or salinity increase until predefined sub-lethal end points (loss of equilibrium and/or loss of buoyancy). The critical thermal and salinity maxima (CTMax and CSMax) were then calculated as the arithmetic mean of the combined thermal or salinity points at which the endpoint was attained. Finally, thermal and salinity safety margins for the two species were also calculated using abiotic data. Mosquitofish (females and males pooled) showed an average CΤmax of 35.85 °C and the killifish 36.27 °C (sexes pooled). Mosquitofish (male) showed an average CSmax of 40.25‰ and (male) killifish 42.64‰ (sexes also pooled). Killifish safety margins are much higher than those of the mosquitofish. Future impacts of global warming and salinisation on these species and on their interactions under current climate change scenarios are discussed. Full article

The rapid development of marine recirculating aquaculture systems (RASs) worldwide offers an efficient and sustainable approach to aquaculture. However, the slow start-up of the nitrification process under low-temperature conditions remains a significant challenge. This study evaluated multiple start-up strategies for moving bed biofilm reactors (MBBRs) operating at 13–15 °C. Among them, the salinity-gradient (SG) strategy exhibited the best performance, reducing the start-up time by 38 days compared to the control, with microbial richness (Chao1 index) reaching 396 and diversity (Shannon index) of 4.89. Inoculation with mature biofilm (MBI) also showed excellent results, shortening the start-up period by 26 days and achieving a stable total ammonia nitrogen (TAN) effluent concentration below 0.5 mg/L within 132 days. MBI exhibited the highest microbial richness (Chao1 index = 808) and diversity (Shannon index = 5.55), significantly higher than those of the control (Chao1 index = 279, Shannon index = 3.90) and other treatments. The hydraulic retention time-gradient (HRT) strategy contributed to performance improvement as well, with a 24-day reduction in start-up time and a Chao1 index of 663 and a Shannon index is 4.69. In contrast, nitrifying bacteria addition (NBA) and carrier adhesion layer modification (CALM) had limited effects on start-up efficiency or microbial diversity, with Chao1 indices of only 255 and 228, and Shannon indices were both 3.24, respectively. Overall, the results indicate that salinity acclimation, mature biofilm inoculation, and extended HRT are effective approaches for promoting microbial community adaptation and enhancing MBBR start-up under low-temperature marine conditions. Full article

Solute carrier family 12 (SLC12) encodes electroneutral cation-coupled chloride cotransporters responsible for transmembrane ion transport (Na⁺, K⁺, and Cl⁻), which play a critical role in aquatic osmoregulation. However, the SLC12 gene of Exopalaemon carinicauda (EcSLC12) has not been systematically identified or functionally characterized. In this study, six EcSLC12 genes were identified across the genome and classified into N(K)CC, KCC, CCC9, and CIP subfamilies. Three NKCC1 homologous genes (EcSLC12A2.1, EcSLC12A2.2, and EcSLC12A2.3) were reported for the first time in crustaceans. The EcSLC12 family exhibited distinct expression patterns in response to low-salinity, high-alkalinity, and saline–alkaline stress. EcSLC12A2.2 was highly expressed in the gill, and its expression was closely correlated with saline–alkaline acclimation. Additionally, EcSLC12A2.2 knockdown decreased E. carinicauda survival under saline–alkaline stress. Thus, EcSLC12A2.2 plays critical roles in osmotic regulation and saline–alkaline acclimation. This study provides crucial insights into E. carinicauda’s saline–alkaline tolerance mechanisms, and the discovery of multiple NKCC1 homologs fills a gap in the crustacean SLC12 gene family research. Full article

Nile tilapia (Oreochromis niloticus) is a key species due to its rapid growth, high nutritional value, and adaptability to diverse environments. However, changes in water salinity pose significant challenges to tilapia farming. Elucidating the adaptive strategies of tilapia to fluctuating salinity environments is crucial for improving aquaculture efficiency. This study investigated the transcriptional signature of growth-hormone-releasing hormone, somatostatin, growth hormone, and insulin-like growth factor (grhr-sst-gh-igf) axis in Nile tilapia under different salinity conditions (0 g/L, 16 g/L, and 30 g/L). The results showed that in brackish or seawater, Nile tilapia rapidly upregulate brain igfbp5 paralogues and their regulators (sst5, sstr2) to sustain growth-active IGF-1 signaling, while in the liver and gut, they downregulate sstr2b, igfbp1/7, and ghrh to reallocate energy toward osmoregulation. Physiological regulation, such as the use of ligand analogs, or genetic enhancement targeting these genes might hold promise for improving salt acclimation, which would enable profitable farming in brackish or coastal ponds and offer a simple tool for more resilient and efficient tilapia production. Full article

Macrobrachium nipponense represents a commercial decapod species that predominantly inhabits freshwater ecosystems or environments with low salinity. However, the species exhibits normal survival and reproductive capacity in natural aquatic habitats with salinity levels up to 10 parts per thousand (ppt). The present study aimed to elucidate the molecular mechanisms underlying salinity acclimation in M. nipponense by investigating alterations in oxidative stress, morphological adaptations, and hepatopancreatic gene expression profiles following exposure to a salinity level of 10 ppt. The present study demonstrates that glutathione peroxidase and Na⁺/K⁺-ATPase play critical roles in mitigating oxidative stress induced by elevated salinity in M. nipponense. Furthermore, histological analysis revealed distinct pathological alterations in the hepatopancreas of M. nipponense following 7-day salinity exposure, including basement-membrane disruption, luminal expansion, vacuolization, and a marked reduction in storage cells. Transcriptomic profiling of M. nipponense hepatopancreas suggested coordinated activation of both immune (lysosome and protein processing in endoplasmic reticulum pathways) and energy (pyruvate metabolism, glycolysis/gluconeogenesis, and citrate cycle) metabolic processes during salinity acclimation in M. nipponense. Quantitative real-time PCR validation confirmed the reliability of RNA-seq data. This study provides molecular insights into the salinity adaptation mechanisms in M. nipponense, offering potential applications for improving cultivation practices in brackish water environments. Full article

Effective transport strategies are critical for the survival and welfare of juvenile Ictalurus punctatus, but the effects of pre-transport salt bath treatments remain uncertain. In this study, we systematically evaluated the effects of pre-transport salt bath acclimation at 0‰ (S1), 1‰ (S2), 5‰ (S3), and 9‰ (S4) salinity for 30 min on stress resilience and recovery in fingerlings during 12 h of simulated transport and 24 h of recovery. All fish survived, but total ammonia nitrogen (TAN) increased, and pH decreased in all groups, except S3, which showed significantly lower TAN and higher pH (p < 0.05). The S3 and S4 groups showed attenuated increases in serum cortisol and glucose, with S3 exhibiting the fastest return to baseline levels and stable serum sodium and potassium levels. Liver antioxidant enzyme activities in group S3 remained stable, with the lowest malondialdehyde (MDA) accumulation. Integrated biomarker response (IBR) and histological analyses demonstrated that S3 had the lowest systemic stress and tissue damage, whereas S1 and S4 displayed marked cellular disruption. These results indicate that a 5‰ salt bath applied prior to transport may improve water quality, mitigate stress responses, and preserve tissue integrity in juvenile channel catfish. Further studies are needed to confirm these findings in other species and under commercial transport conditions. Full article

Declining freshwater resources have spurred interest in saline–alkali (SA) water aquaculture, with species like tilapia and rainbow trout demonstrating ecological plasticity in such environments. However, the molecular mechanisms underlying fish adaptation and quality impacts remain unclear. This study investigated the hybrid fish “Xianfeng No. 1” (Erythroculter ilishaeformis × Ancherythroculter nigrocauda), a key aquaculture species in China, under 60-day SA exposure. The results showed increased levels of oxidative stress markers (MDA) and antioxidant enzymes (SOD, CAT, GSH-Px), alongside improved quality traits. Transcriptomics revealed differentially expressed genes (DEGs) in muscle tissue associated with oxidative stress (UQCRFS1, UQCR10, CYC1), ion transport (COX5A, COX7C, COX7B), and the immune response (ATG9A, ATG2B, ATG2A, ULK1, ULK2, CFI, CFH). Metabolomics identified increased non-volatile flavors (e.g., glycine, proline) and collagen-related compounds. Integrated analysis highlighted the upregulation of GSR and GGT, and the downregulation of CHDH and GBSA, potentially driving glycine accumulation. These findings suggest that SA stress enhances antioxidant capacity, activates immune pathways, and modulates ion transport, enabling adaptation while improving meat quality. This study elucidates molecular mechanisms of fish acclimation to SA environments, providing insights for sustainable aquaculture development and breeding of stress-tolerant species in SA regions. Full article

While a rapid activation of antioxidant defense mechanisms following the exposure to salt stress has been widely reported in plants, less is known about their role under prolonged ionic stress conditions. This study aimed at investigating whether increased levels of enzymatic antioxidants are required in salt-acclimated plants. Rice, a staple crop for more than half of the world’s population, is very sensitive to excess salt, mainly at the seedling stage. The levels of selected antioxidant enzymes and the non-enzymatic antioxidant glutathione were measured in seedlings of a group of five Italian rice cultivars showing a natural variability in the susceptibility to a moderate saline environment. Up to 15.62 dS/m, the presence of salts caused a progressive growth inhibition, yet thiobarbituric acid reactive substance levels did not significantly increase. Accordingly, chlorophyll content appeared unaffected, suggesting successful acclimation. Immunological analysis showed increases of catalase protein levels in shoots, and of Cu/Zn- and Mn-dependent superoxide dismutases in both roots and shoots, whereas no variations were found for other enzymes. Only slight differences in glutathione content were evident between salt-grown seedlings and untreated controls. The data suggest that an enhancement of antioxidant defenses in different tissues takes place in rice plants to cope with sublethal salt stress conditions. Full article

Macrobrachium nipponense is an important economic freshwater species in China. Previous research has found that M. nipponense can reproduce under salinity conditions of 10 parts per thousand (ppt) and exhibits a strong ability to adapt to salinity changes in the aquatic environment. The aim of the present study was to identify the molecular mechanism of M. nipponense in terms of saline acclimation by identifying changes in immune response, morphology, and gene expression in the gills under a salinity of 10 ppt. The findings revealed that salinity exposure dramatically stimulated the activities of MDA, Ca²⁺Mg²⁺-ATPase, and CAT, reaching a peak on Day 7 (p < 0.05), indicating that these antioxidant enzymes play essential roles in protecting the body from the damage caused by saline treatment. In addition, we found no obvious morphological changes in the gills, indicating that M. nipponense can adapt well to water environments with such salinity. Transcriptome profiling analysis identified 168, 434, and 944 differentially expressed genes (DEGs) when comparing S0 vs. S1, S1 vs. S4, and S4 vs. S7, respectively. Furthermore, lysosome, apoptosis, amino sugar, and nucleotide sugar metabolism; the cGMP-PKG signaling pathway; pancreatic secretion; and the calcium signaling pathway represented the main enriched metabolic pathways of DEGs in the present study. Lysosome, apoptosis, amino sugar, and nucleotide sugar metabolism and the cGMP-PKG signaling pathway are immune-related metabolic pathways, while pancreatic secretion is an energy-metabolism-related metabolic pathway, suggesting that the immune response and energy metabolism play essential roles in the regulation of saline acclimation in this species. The results from the quantitative real-time PCR analyses of the DEGs were consistent with those from RNA-Seq, indicating the accuracy of the present study. This study provides valuable evidence for the acclimation of M. nipponense to high-salinity aquatic environments, thus indicating the potential for this species to be used in aquaculture programs in saline and alkaline water regions. Full article

Lippia alba (Mill.) N.E.Br. ex Britton and P. Wilson is a native plant of Colombia, widespread throughout Central and South America, used for thousands of years by pre-Columbian populations, who already knew the many beneficial properties of this species (e.g., antifungal, antibacterial, antiviral and anti-inflammatory activities). The essential oil of L. alba is rich in phytochemicals with antioxidant activity that could be very useful both for pharmacology and biotechnology application, such as the protection of horticultural crops sensitive to salinity. To enhance salt tolerance, seed-priming treatment with the essential oil of L. alba was performed. We evaluated the effect of this biostimulant on the response to salt stress in a sensitive bean species, Phaseolus acutifolius L. (cv Blue Tepary), native to Mexico, and used by pre-Columbians as well as nowadays. Bean seeds were primed in a solution of 0.5 mL/L of essential oil of L. alba, germinated and after 2 weeks of acclimation, the seedlings were subjected to salt stress, by watering with 40 mM and 80 mM NaCl solutions. Four weeks later, many biochemical parameters were evaluated in order to test the effects of the treatments on plant fitness. Primed seeds showed an increase in salt tolerance during germination, as well as primed plants revealing a higher water uptake, increased chlorophylls, proline content and salt tolerance index. The treatments also improved the Ca²⁺ concentration in the shoots of stressed primed plants, more quickly activating enzymatic responses to salinity—in particular superoxide dismutase, polyphenol oxidase, catalase, peroxidase and ascorbate peroxidase—compared to unprimed stressed plants. In conclusion, L. alba was found to be a strong elicitor of responses against osmotic and oxidative stress, as induced by salinity, suggesting the possibility of its future utilization in agriculture. Full article

This study investigated the effects of salinity on the growth and cell morphotype of the coral-associated dinoflagellate Durusdinium glynnii under two acclimation strategies: abrupt saline shock (S5) and gradual reduction (S2). Results revealed optimal growth rates (µ = 0.22–0.35 day⁻¹) at salinities of 20–30 g L⁻¹, while extreme conditions (10 and 40 g L⁻¹) significantly inhibited development. The S2 strategy enabled adaptation to salinities as low as 16 g L⁻¹, maintaining higher cell densities compared to the S5 method. Gradual salinity reduction also influenced cellular morphology: below 12 g L⁻¹, a predominant shift occurred from motile forms (mastigotes) to non-motile spherical structures (coccoid), suggesting an adaptive response to osmotic stress, gradually reducing the growth rate due to the lower reproductive rate of coccoid cells, as previously reported in studies. The findings conclude that D. glynnii is a euryhaline species, tolerant of moderate salinity variations (16–30 g L⁻¹) but limited under extreme conditions. Its morphological plasticity and gradual acclimation capacity highlight its potential for cultivation in brackish environments and biomass production for biotechnological applications, such as antioxidants and antimicrobials. The data provide a foundation for future studies on molecular mechanisms of salinity tolerance, essential for coral conservation strategies and bioprospecting efforts. Full article

Grass carp (Ctenopharyngodon idella) is a key aquaculture species, and understanding its adaptation mechanisms to saline environments is crucial for addressing the global freshwater salinization challenge. In this study, juvenile grass carp were acclimated to three salinity levels (0, 4, and 8 ppt) for 30 days, after which gill and intestinal tissues were sampled to quantify cortisol concentrations and conduct RNA-seq. Results showed that cortisol levels exhibited a salinity-dependent increase, with significantly higher concentrations in gill tissues than in intestinal tissues, suggesting that cortisol plays an important role in the salt adaptation of grass carp. RNA-seq revealed that ion transport-related genes were upregulated in gills, whereas biosynthesis, oxygen transport, and energy metabolism genes were downregulated. In the intestine, genes involved in taurine transport and intercellular junctions were highly expressed, while immune-related genes showed reduced expression. These findings suggest that high salinity suppresses respiration and energy metabolism efficiency, with ion exchange primarily occurring in gills. Functional annotation identified seven candidate genes (LOC127513882, aqp9b, ca4a, ca5a, igfbp1b, slc12a2, and slc12a4) as key regulators of salinity adaptation. Overall, our study provides valuable insights into the mechanisms underlying the salt tolerance of grass carp. Full article

To ameliorate plants’ response to environmental stresses, seed priming can be a useful tool; it consists of the pre-exposure of the seeds to mild stress, which improves plant adaptation to future exposure to adverse growth conditions. In our previous studies, seed priming with polyamines (2.5 mM putrescine, 2.5 mM spermine, and 2.5 mM spermidine) and salt acclimation have been proven to be an effective treatment in enhancing salt tolerance of tomato cultivars since they induced a better physiological response to salt stressful condition. The persistence of the memory of the first (priming) stress and retrieval of such remembered information upon exposure to later new stress play an important role in the applicability of seed priming in agriculture. Therefore, the aim of this work was the detection of the persistence of a stress memory induced by polyamine priming in tomatoes. Primed and not-primed seeds were stored at +4 °C for 2 years after the original priming treatment; then, germinated seeds were sown in non-saline soil and irrigated with 80 and 160 mM NaCl salt solutions until fruit production. The results confirm the increase in salt tolerance in primed plants compared to not-primed ones, indicating the presence of long-term somatic memory. In comparison with not primed, the primed plants produced better quality fruits, i.e., higher weight, water content, and higher amount of carotenoids, soluble sugars, and phenols. To determine if the memory can be inherited by the offspring, seeds were then collected from primed and not-primed plants (generation G1), and further experiments were undertaken by growing G1 plants under the same irrigation regime as the parental generation. After 45 days of growth, both antioxidants and osmolyte amounts were enhanced, leading to an improvement in the tolerance to saline conditions in the offspring of primed plants and confirming the results already observed in the parental generation. These results demonstrate, for the first time, the presence of both long-term somatic and intergenerational priming memory in tomatoes and may pave the pathway to future agricultural application of seed priming. Full article

In the natural environment, plants are simultaneously exposed to multivariable abiotic and biotic stresses. Typical abiotic stresses are changes in temperature, light intensity and quality, water stress (drought, flood), microelements availability, salinity, air pollutants, and others. Biotic stresses are caused by other organisms, such as pathogenic bacteria and viruses or parasites. This review presents the current state-of-the-art knowledge on programmed cell death in the cross-tolerance phenomena and its conditional molecular and physiological regulators, which simultaneously regulate plant acclimation, defense, and developmental responses. It highlights the role of the absorbed energy in excess and its dissipation as heat in the induction of the chloroplast retrograde phytohormonal, electrical, and reactive oxygen species signaling. It also discusses how systemic- and network-acquired acclimation and acquired systemic resistance are mutually regulated and demonstrates the role of non-photochemical quenching and the dissipation of absorbed energy in excess as heat in the cross-tolerance phenomenon. Finally, new evidence that plants evolved one molecular system to regulate cell death, acclimation, and cross-tolerance are presented and discussed. Full article

The previously available coding region for the spiny dogfish (Squalus acanthias) AQP3-2 gene was amplified from cDNAs using PCR. Agarose gel electrophoresis gave a band of the AQP3-2 coding region, as well as multiple smaller splice variant bands. The main AQP3-2 band and the largest and most fluorescently intense pair of these splice variant bands were cloned and sequenced. Amplifications were performed on a range of tissue cDNAs, but AQP3-2 was only expressed in the kidney and brain. Quantitative PCR amplifications using pre-existing kidney cDNA from an environmental salinity acclimation experiment showed that the abundance of mRNA from both the main AQP3-2 transcript and the largest splice variant (Splice Variant 1) was lower in 120% seawater (SW) acclimated fish, although only the values for Splice Variant 1 were statistically significant. A custom-made affinity-purified rabbit polyclonal AQP3-2 antibody was produced, and this gave four bands of around the correct sizes (which were 27 and 32 kDa) for the complete AQP3-2 and Splice Variant 1 proteins. Two of the bands may have been N-glycosylated forms of these proteins. Other bands were also present on the Western blot. No bands were present when the antibody was pre-blocked by the peptide antigen. In tissue sections of the dogfish kidney, immunohistochemical localization experiments showed that AQP3-2 was expressed in the early distal tubule (EDT) and late distal tubule (LDT) nephron segments. The results suggest that AQP3-2 may be involved in cell volume regulation in the EDT and water and urea absorption in the LDT nephron segment. Full article