Saline Challenge Research Articles

Three Microbial Musketeers of the Seas: Shewanella baltica, Aliivibrio fischeri and Vibrio harveyi, and Their Adaptation to Different Salinity Probed by a Proteomic Approach.

Osmotic changes are common challenges for marine microorganisms. Bacteria have developed numerous ways of dealing with this stress, including reprogramming of global cellular processes. However, specific molecular adaptation mechanisms to osmotic stress have mainly been investigated in terrestrial model bacteria. In this work, we aimed to elucidate the basis of adjustment to prolonged salinity challenges at the proteome level in marine bacteria. The objects of our studies were three representatives of bacteria inhabiting various marine environments, Shewanella baltica, Vibrio harveyi and Aliivibrio fischeri. The proteomic studies were performed with bacteria cultivated in increased and decreased salinity, followed by proteolytic digestion of samples which were then subjected to liquid chromatography with tandem mass spectrometry analysis. We show that bacteria adjust at all levels of their biological processes, from DNA topology through gene expression regulation and proteasome assembly, to transport and cellular metabolism. The finding that many similar adaptation strategies were observed for both low- and high-salinity conditions is particularly striking. The results show that adaptation to salinity challenge involves the accumulation of DNA-binding proteins and increased polyamine uptake. We hypothesize that their function is to coat and protect the nucleoid to counteract adverse changes in DNA topology due to ionic shifts.

Halopriming Imparts Salt Tolerance by Reducing Oxidative, Osmotic Stress and DNA Damage in Five Different Legume Varieties

Background: Salinity challenges legume production worldwide. To maintain the overall legume production, seed halopriming has been adopted as a cost-effective, farmer friendly technique, minimizing noxious effects of NaCl on plant growth. Methods: Nonprimed and haloprimed seeds were grown under different NaCl concentrations and harvested after 21 days. NaCl-induced alterations on physio-biochemical attributes and DNA damage were studied. Result: NaCl exposure in nonprimed seedlings exhibited growth inhibition, depletion in water contents, increased accumulation of H2O2, MDA and proline causing DNA damage. Conversely, in primed seedlings, these toxic effects were altered and extent of DNA damage reduced. Decreased catalase activity in nonprimed seedlings failed to detoxify the ROS generated under salinity inducing DNA damage whereas in NaCl-treated haloprimed seedlings, improved catalase activity helped to overcome such adversities favouring improved growth of all tested legume varieties.

Review of Soil Salinity and Sodicity Challenges to Crop Production in the Lowland Irrigated Areas of Ethiopia and Its Management Strategies

Ethiopia’s irrigated agriculture productivity has been threatened by severe salinity and sodicity problems which have resulted in significantly lower yields, food insecurity, and environmental degradation. The destructive effects of poor irrigation water management with the absence of drainage and anticipated future climate changes can accelerate the formation of salt-affected soil, potentially expanding the problem to currently unaffected regions. This paper synthesizes the available information on the causes, extent, and effects of salt-affected soils on soil and crop production and suggest chemical, biological, and physical reclamation and management approaches for tackling salinity and sodicity problems. The mitigation approaches (e.g., the addition of amendments, plantation of salt-tolerant crops, appropriate irrigation and drainage management, phytoremediation, and bioremediation) have successfully tackled soil salinity and sodicity problems in many parts of the world. These approaches have further improved the socioeconomic conditions of farming communities in salt-affected areas. The paper also discusses the effectiveness of these mitigation strategies under Ethiopian conditions. The policy interventions for reclamation of soil salinity and sodicity that indicates future research attention to restoring agricultural sustainability are also foci of this paper.

Cell Volume Regulation Mechanisms in Differentiated Astrocytes.

The ability of astrocytes to control extracellular volume homeostasis is critical for brain function and pathology. Uncovering the mechanisms of cell volume regulation by astrocytes will be important for identifying novel therapeutic targets for neurological conditions, such as those characterized by imbalances to hydro saline challenges (as in edema) or by altered cell volume regulation (as in glioma). One major challenge in studying the astroglial membrane channels involved in volume homeostasis in cell culture model systems is that the expression patterns of these membrane channels do not resemble those observed in vivo. In our previous study, we demonstrated that rat primary astrocytes grown on nanostructured interfaces based on hydrotalcite-like compounds (HTlc) in vitro are differentiated and display molecular and functional properties of in vivo astrocytes, such as the functional expression of inwardly rectifying K+ channel (Kir 4.1) and Aquaporin-4 (AQP4) at the astrocytic microdomain. Here, we take advantage of the properties of differentiated primary astrocytes in vitro to provide an insight into the mechanism underpinning astrocytic cell volume regulation and its correlation with the expression and function of AQP4, Transient Receptor Potential Vanilloid 4 (TRPV4), and Volume Regulated Anion Channel (VRAC). The calcein quenching method was used to study water transport and cell volume regulation. Calcium imaging and electrophysiology (patch-clamp) were used for functional analyses of calcium dynamics and chloride currents. Western blot and immunofluorescence were used to analyse the expression and localization of the channel proteins of interest. We found that the increase in water permeability, previously observed in differentiated astrocytes, occurs simultaneously with more efficient regulatory volume increase and regulatory volume decrease. Accordingly, the magnitude of the hypotonic induced intracellular calcium response, typically mediated by TRPV4, as well as the hypotonic induced VRAC current, was almost twice as high in differentiated astrocytes. Interestingly, while we confirmed increased AQP4 expression in the membrane of differentiated astrocytes, the expression of the channels TRPV4 and Leucine-Rich Repeats-Containing 8-A (LRRC8-A) were comparable between differentiated and non-differentiated astrocytes. The reported results indicate that AQP4 up-regulation observed in differentiated astrocytes might promote higher sensitivity of the cell to osmotic changes, resulting in increased magnitude of calcium signaling and faster kinetics of the RVD and RVI processes. The implications for cell physiology and the mechanisms underlying astrocytic interaction with nanostructured interfaces are discussed.

Different transcriptomic architecture of the gill epithelia in Nile and Mozambique tilapia after salinity challenge

Tilapiine fishes of the genus Oreochromis vary in their euryhaline capabilities, therefore inhabiting aquatic environments of different salinities across the African continent. We analyzed the differential gene expression in the gills before and after 6 weeks salinity challenge between the highly tolerant Mozambique tilapia (Oreochromis mossambicus) and the less tolerant Nile tilapia (O. niloticus). The pathways triggered by salinity in both tilapia species reveal immune and cell stress responses as well as turnover of ionocytes. Nevertheless, the actual differential expressed genes vary between these two species, pointing at differential transcriptomic architecture, which likely contribute to the species osmoregulation capabilities in elevated salinities.

Enhanced airway sensory nerve reactivity in non-eosinophilic asthma

BackgroundNeural mechanisms may play an important role in non-eosinophilic asthma (NEA). This study compared airway sensory nerve reactivity, using capsaicin challenge, in eosinophilic asthma (EA) and NEA and non-asthmatics.MethodsThirty-eight asthmatics...

Molecular characterization of a c-Jun NH2-terminal kinase (JNK)-interacting protein 4 (Lv-JIP4) in Litopenaeus vannamei and its potential role in the Lv-p38MAPK pathway in response to low temperature

C-Jun NH2-terminal kinase (JNK)-interacting protein 4 (JIP4) is an essential molecule that organizes and links components of the mitogen-activated protein kinase (MAPK) pathway. In the present study, a novel JIP4 gene was identified in Litopenaeus vannamei and designated Lv-JIP4. The full-length Lv-JIP4 cDNA was 3923 bp in length and contained a 170-bp 5′-untranslated region (UTR), a 72-bp 3′-UTR, and a 3,681-bp open reading frame (ORF). The Lv-JIP4 protein contained three functional domains, including the Jnk-SapK_ap_N, JIP_LZII and WD40 domains. Lv-JIP4 mRNA was broadly distributed in all studied tissues, with the highest level in muscle. The in situ hybridization results showed that the Lv-JIP4 was scattered in muscle fibres and near the sarcolemma. Subcellular localization analysis indicated that Lv-JIP4 was located in the cytoplasm but not in the nucleus. The transcript levels of Lv-JIP4 in muscle were found to be significantly increased by low temperature, low pH, high salinity, poly(I:C), and LPS challenges, indicating that it might play a crucial role in responding to adverse stresses. The transcript levels of Lv-JIP4, Lv-p38aMAPK and Lv-p38bMAPK in muscle were significantly upregulated after challenge with low temperature, suggesting that Lv-JIP4 may be the positive regulator of Lv-p38aMAPK and Lv-p38bMAPK under low temperature stress conditions. In addition, after knockdown of Lv-JIP4 expression, the protein levels of total Lv-p38MAPK and phospho-Lv-p38MAPK in the experimental dsRNA group were attenuated compared with those in the control group after 48 h (h), 60 h and 72 h of low-temperature stress, indicating that it might activate and phosphorylate the Lv-p38MAPK protein in response to cold stress. Here, we elucidated the molecular characteristics and the potential role of Lv-JIP4 and further refined the signal transduction mechanism of L. vannamei in response to low-temperature stress.

Molecular Identification of Anion Exchange Protein 3 in Pacific White Shrimp (Litopenaeus vannamei): mRNA Profiles for Tissues, Ontogeny, Molting, and Ovarian Development and Its Potential Role in Stress-Induced Gill Damage.

Bicarbonate (HCO3–) transport mechanisms play an essential role in the acid-base homeostasis of aquatic animals, and anion exchange protein 3 (AE3) is a membrane transport protein that exchanges Cl–/HCO3– across the cell membrane to regulate the intracellular pH. In this study, the full-length cDNA of AE3 (Lv-AE3) was obtained from the Pacific white shrimp (Litopenaeus vannamei). The Lv-AE3 cDNA is 4,943 bp in length, contains an open reading frame of 2,850 bp, coding for a protein of 949 amino acids with 12 transmembrane domains. Lv-AE3 shows high sequence homology with other AE3 at the protein level. Lv-AE3 mRNA was ubiquitously detected in all tissues selected, with the highest expression level in the gill, followed by the ovary, eyestalk and brain. By in situ hybridization, Lv-AE3-positive cells were shown predominant localization in the secondary gill filaments. The expression levels of Lv-AE3 were further investigated during the essential life processes of shrimp, including ontogeny, molting, and ovarian development. In this case, the spatiotemporal expression profiles of Lv-AE3 in L. vannamei were highly correlated with the activities of water and ion absorption; for example, increased mRNA levels were present after hatching, during embryonic development, after ecdysis during the molt cycle, and in the stage IV ovary during gonadal development. After low/high pH and low/high salinity challenges, the transcript levels of Lv-AE3 were reduced in the gill, while the cell apoptosis rate increased. In addition, knockdown of Lv-AE3 mRNA expression induced cell apoptosis in the gill, indicating a potential link between Lv-AE3 and gill damage. Altogether, this study thoroughly investigated the relationship between the mRNA expression profiles of Lv-AE3 and multiple developmental and physiological processes in L. vannamei, and it may benefit the protection of crustaceans from fluctuated aquatic environments.

Variability in the degree of euryhalinity of neotropical estuarine annelids

Estuaries are highly dynamic, spatially complex systems showing large daily fluctuations in salinity. Estuarine organisms, especially small animals with limited locomotory capacities, are thus expected to have variable ecological and morphophysiological strategies. This paper evaluates the responses to salinity challenges in four species of neotropical annelids along a subtropical estuarine gradient by assessing mortality (i.e., tolerance) and changes in body weight (proxy for water fluxes). We selected the nereidids Alitta sp. and Laeonereis acuta, with broad salinity niches, and the nephtyid Nephtys fluviatilis and the melinnid Isolda pulchella, with either narrow salinity niches or a more restricted spatial range. Worms were weighed, exposed to salinities ranging from fresh water to full-strength seawater (0, 5, 15, 25, and 35) for 1, 6, 12, and 24 h, and weighed again after these exposure times. Their mortality (as absence of body movements or vascular circulation) rates were recorded to assess their ranges of tolerance to these treatments or their degree of euryhalinity. Their integument was characterized histologically to show possible morphological links to their tolerances. Both nereidids displayed stable body weights and thick integuments, compatible with the wide range of salinity tolerance and capacity to maintain body hydration. Body weight of Alitta sp. returned to initial values after 1 h at salinities ≥5. Body weight did not change in L. acuta at salinities ≥15; mortalities occurred only at salinity 0 after 12–24 h. Nephtys fluviatilis showed a thin integument and less variation in weight throughout the whole range of tested salinities, but mortality occurred after 24 h at salinity 0, at its reference salinity (3) and at 35. Isolda pulchella showed a lower capacity to maintain body weight/hydration and a thin integument, compatible with its relative stenohalinity and presence restricted to polyhaline marine sectors. Its weight variation was significant at all salinities except 35; mortality occurred at extreme salinities: 0 and 35. Responses of the four species were compatible with their distribution along the estuarine gradient, as an interesting outcome of their autecological traits, morphophysiological adaptations and evolutionary histories.

Effect of Salinity on Cr(VI) Bioremediation by Algal-Bacterial Aerobic Granular Sludge Treating Synthetic Wastewater

Heavy metal-containing wastewater with high salinity challenges wastewater treatment plants (WWTPs) where the conventional activated sludge process is widely applied. Bioremediation has been proven to be an effective, economical, and eco-friendly technique to remove heavy metals from various wastewaters. The newly developed algal-bacterial aerobic granular sludge (AGS) has emerged as a promising biosorbent for treating wastewater containing heavy metals, especially Cr(VI). In this study, two identical cylindrical sequencing batch reactors (SBRs), i.e., R1 (Control) and R2 (with 1% additional salinity), were used to cultivate algal-bacterial AGS and then to evaluate the effect of salinity on the performance of the two SBRs. The results reflected that less filamentation and a rougher surface could be observed on algal-bacterial AGS when exposed to 1% salinity, which showed little influence on organics removal. However, the removals of total inorganic nitrogen (TIN) and total phosphorus (TP) were noticeably impacted at the 1% salinity condition, and were further decreased with the co-existence of 2 mg/L Cr(VI). The Cr(VI) removal efficiency, on the other hand, was 31–51% by R1 and 28–48% by R2, respectively, indicating that salinity exposure may slightly influence Cr(VI) bioremediation. In addition, salinity exposure stimulated more polysaccharides excretion from algal-bacterial AGS while Cr(VI) exposure promoted proteins excretion.

Response to Salinity Challenge in Non-native Cichlid Fishes of the Genus Herichthys Introduced in the Gulf Coast Region of the United States

The Rio Grande Cichlid, Herichthys cyanoguttatus, is native to northeastern Mexico and southern Texas and has been introduced at many places in the US. Recent research has indicated that the true identity of at least some populations of Herichthys cf. cyanoguttatus in Louisiana is H. carpintis and not H. cyanoguttatus. In both their native and introduced ranges, H. carpintis seems to occupy a more lowland/coastal distribution than does Herichthys cyanoguttatus, suggesting that the two species may differ physiologically or ecologically in their ability to invade new environments. Previous research has found that Herichthys cf. cyanoguttatus from Louisiana (which were most likely H. carpintis) have a high tolerance to salinity and pose a threat to both fresh and brackish waters, but the osmoregulatory capacity of H. cyanoguttatus from Texas is unknown. To determine if H. cyanoguttatus from Texas might also have a high tolerance to salinity and pose a threat to both fresh and brackish waters, we performed three experiments to assess response to salinity challenges in H. cyanoguttatus from Texas and in H. carpintis from Louisiana. In response to acute moderate salinity challenge, we found a non-significant salinity*species interaction in change in body mass, a species difference in hematocrit, and no differences in plasma chloride or osmolality. In a 120-day chronic salinity exposure, salinity concentration was inversely related to growth rate, but there was no difference in growth between the two species. In an acute challenge, high salinity concentrations had a strong negative effect on survival, but survival was not different between the two species. Both species were highly tolerant of salinity, indicating that both species might be able to use brackish waters in coastal areas to expand their ranges in the US. Finally, we found that H. cyanoguttatus from Texas spent more time swimming than did H. carpintis from Louisiana, suggesting that the two species could differ in the way they interact behaviorally with native fish communities.

Time-course changes in the regulation of ions and amino acids in the hard clam Meretrix lusoria upon lower salinity challenge.

In this study, we examined ion and amino acid regulation in the gill and mantle of the hard clam Meretrix lusoria. We found that the osmolality and Na+ and Cl- concentrations of hard clam hemolymph were significantly reduced after transferring clams from the salinity of their natural habitat [20‰ saltwater (SW)] to a lower salinity environment (10‰ SW). Specific activities of Na+ , K+ -ATPase (NKA), which provides the driving force for the secondary ion transport associated with cell osmoregulation in gills and mantles, were unaffected during the acclimation to lower salinity. In contrast, there was a significant decline in the contents of free amino acids (FAAs) in the gills and mantles of hard clams during lower salinity acclimation. Taurine was established to be the dominant FAA, the content of which is considerably higher than that of other FAAs in the hard clam. Following acclimation to the lower salinity environment, mRNA expression of the taurine transporter (TAUT), which plays a pivotal role in regulating intracellular taurine contents, was significantly upregulated in the gill and downregulated in the mantle of hard clams at different time points. However, the relative abundance of TAUT protein in the gill and mantle was significantly increased after transfer from 20‰ SW to 10‰ SW, which may reflect feedback regulation in response to reduced taurine contents in the gill and mantle of hard clams. Collectively, the findings of this study provide important insights on the dynamic processes of ion and amino acid regulation in the peripheral tissues of bivalves.

Empagliflozin Inhibits Proximal Tubule NHE3 Activity, Preserves GFR, and Restores Euvolemia in Nondiabetic Rats with Induced Heart Failure.

SGLT2 inhibitors reduce the risk of heart failure (HF) mortality and morbidity, regardless of the presence or absence of diabetes, but the mechanisms underlying this benefit remain unclear. Experiments with nondiabetic HF rats tested the hypothesis that the SGLT2 inhibitor empagliflozin (EMPA) inhibits proximal tubule (PT) NHE3 activity and improves renal salt and water handling. Male Wistar rats were subjected to myocardial infarction or sham operation. After 4 weeks, rats that developed HF and sham rats were treated with EMPA or untreated for an additional 4 weeks. Immunoblotting and quantitative RT-PCR evaluated SGLT2 and NHE3 expression. Stationary in vivo microperfusion measured PT NHE3 activity. EMPA-treated HF rats displayed lower serum B-type natriuretic peptide levels and lower right ventricle and lung weight to tibia length than untreated HF rats. Upon saline challenge, the diuretic and natriuretic responses of EMPA-treated HF rats were similar to those of sham rats and were higher than those of untreated HF rats. Additionally, EMPA treatment prevented GFR decline and renal atrophy in HF rats. PT NHE3 activity was higher in HF rats than in sham rats, whereas treatment with EMPA markedly reduced NHE3 activity. Unexpectedly, SGLT2 protein and mRNA abundance were upregulated in the PT of HF rats. Prevention of HF progression by EMPA is associated with reduced PT NHE3 activity, restoration of euvolemia, and preservation of renal mass. Moreover, dysregulation of PT SGLT2 may be involved in the pathophysiology of nondiabetic HF.

Age-Dependent Decline in Salinity Tolerance in a Euryhaline Fish.

Euryhaline teleost fish are characterized by their ability to tolerate a wide range of environmental salinities by modifying the function of osmoregulatory cells and tissues. In this study, we experimentally addressed the age-related decline in the sensitivity of osmoregulatory transcripts associated with a transfer from fresh water (FW) to seawater (SW) in the euryhaline teleost, Mozambique tilapia, Oreochromis mossambicus. The survival rates of tilapia transferred from FW to SW were inversely related with age, indicating that older fish require a longer acclimation period during a salinity challenge. The relative expression of Na+/K+/2Cl− cotransporter 1a (nkcc1a), which plays an important role in hyposmoregulation, was significantly upregulated in younger fish after SW transfer, indicating a clear effect of age in the sensitivity of branchial ionocytes. Prolactin (Prl), a hyperosmoregulatory hormone in O. mossambicus, is released in direct response to a fall in extracellular osmolality. Prl cells of 4-month-old tilapia were sensitive to hyposmotic stimuli, while those of >24-month-old fish did not respond. Moreover, the responsiveness of branchial ionocytes to Prl was more robust in younger fish. Taken together, multiple aspects of osmotic homeostasis, from osmoreception to hormonal and environmental control of osmoregulation, declined in older fish. This decline appears to undermine the ability of older fish to survive transfer to hyperosmotic environments.

Intrauterine Growth Restriction Promotes Postnatal Airway Hyperresponsiveness Independent of Allergic Disease

Introduction: Intrauterine growth restriction (IUGR) is associated with asthma. Murine models of IUGR have altered airway responsiveness in the absence of any inflammatory exposure. Given that a primary feature of asthma is airway inflammation, IUGR-affected individuals may develop more substantial respiratory impairment if subsequently exposed to an allergen. This study used a maternal hypoxia-induced mouse model of IUGR to determine the combined effects of IUGR and allergy on airway responsiveness.Methods: Pregnant BALB/c mice were housed under hypoxic conditions (10.5% O2) from gestational day (GD) 11-GD 17.5 (IUGR group; term = GD 21). Following hypoxic exposure, mice were returned to a normoxic environment (21% O2). A second group of pregnant mice were housed under normoxic conditions throughout pregnancy (Control). All offspring were sensitized to ovalbumin (OVA) and assigned to one of four treatment groups: Control – normoxic and saline challenge; IUGR – hypoxic and saline challenge; Allergy – normoxic and OVA challenge; and IUGR + Allergy – hypoxic and OVA challenge. At 8 weeks of age, and 24 h post-aerosol challenge, mice were tracheostomised for methacholine challenge and assessment of lung mechanics by the forced oscillation technique, and lungs subsequently fixed for morphometry.Results: IUGR offspring were lighter than Control at birth and in adulthood. Both Allergy and IUGR independently increased airway resistance after methacholine challenge. The IUGR group also exhibited an exaggerated increase in tissue damping and elastance after methacholine challenge compared with Control. However, there was no incremental effect on airway responsiveness in the combined IUGR + Allergy group. There was no impact of IUGR or Allergy on airway structure and no effect of sex on any outcome.Conclusion: IUGR and aeroallergen independently increased bronchoconstrictor response, but when combined the pathophysiology was not worsened. Findings suggest that an association between IUGR and asthma is mediated by baseline airway responsiveness rather than susceptibility to allergen.

Environmental Salinity Modifies Mucus Exudation and Energy Use in European Sea Bass Juveniles.

Simple SummaryChanges in skin mucus production and composition offer a new means to study how fish cope with changes in the environment. We explored the utility of skin mucus as an indicator of physiological responses and energy use in a reference fish species, the European sea bass. We evaluated the exudation volume of skin mucus and the main stress- and osmoregulation-related biomarkers in both mucus and plasma. We demonstrate the viability to study the exuded volume of skin mucus composition and its parameters as an informative tool of the fish energy waste at different environmental salinities. This study is of great interest for both aquaculture and ecological studies.The European sea bass (Dicentrarchus labrax) is a euryhaline marine teleost that can often be found in brackish and freshwater or even in hypersaline environments. Here, we exposed sea bass juveniles to sustained salinity challenges for 15 days, simulating one hypoosmotic (3‰), one isosmotic (12‰) and one hyperosmotic (50‰) environment, in addition to control (35‰). We analyzed parameters of skin mucus exudation and mucus biomarkers, as a minimally invasive tool, and plasma biomarkers. Additionally, Na+/K+-ATPase activity was measured, as well as the gill mucous cell distribution, type and shape. The volume of exuded mucus increased significantly under all the salinity challenges, increasing by 130% at 50‰ condition. Significantly greater amounts of soluble protein (3.9 ± 0.6 mg at 50‰ vs. 1.1 ± 0.2 mg at 35‰, p < 0.05) and lactate (4.0 ± 1.0 µg at 50‰ vs. 1.2 ± 0.3 µg at 35‰, p < 0.05) were released, with clear energy expenditure. Gill ATPase activity was significantly higher at the extreme salinities, and the gill mucous cell distribution was rearranged, with more acid and neutral mucin mucous cells at 50‰. Skin mucus osmolality suggested an osmoregulatory function as an ion-trap layer in hypoosmotic conditions, retaining osmosis-related ions. Overall, when sea bass cope with different salinities, the hyperosmotic condition (50‰) demanded more energy than the extreme hypoosmotic condition.

Effect of a Black Soldier Fly Ingredient on the Growth Performance and Disease Resistance of Juvenile Pacific White Shrimp (Litopenaeus vannamei).

This study was performed as part of developing a functional feed ingredient for juvenile Pacific white shrimp (Litopenaeus vannamei). Here we assess the effects of dietary inclusion of a Black Soldier Fly Ingredient (BSFI) from defatted black soldier fly (Hermetia illucens) larvae meal on growth performance, tolerance to salinity stress, and disease resistance when challenged with Vibrio parahaemolyticus or a strain of white spot syndrome virus (WSSV). A control diet was used for comparison with three test diets including 4.5, 7.5, and 10.5% of BSFI (BSFI4.5, BSFI7.5, and BSFI10.5). After 28 days, all diets with BSFI had improved weight gain, feed conversion ratio (FCR) and specific growth rate (SGR) compared to control. Indeed, SGR was significantly improved from inclusion of 4.5% in the diet, whilst FCR was significantly improved at 7.5% (p < 0.05). During the growth trial, survival was not affected by diet. Shrimp health performance was not significantly affected by the diets across the disease and salinity challenges. Overall, the results indicate that the inclusion of BSFI from H. illucens improves the performance of juvenile L. vannamei.

Osmotic and ionic regulation, and kinetic characteristics of a posterior gill (Na+, K+)-ATPase from the blue crab Callinectes danae on acclimation to salinity challenge

Salt tolerance reflects ecophysiological adaptation, and the wide-ranging distribution of the Brachyura mirrors their ability to adjust body fluid concentrations. The gill (Na+, K+)-ATPase underpins such hyper/hypo-regulatory mechanisms. We evaluate osmotic and chloride regulation in Callinectes danae after 10 days acclimation to a wide salinity range (5–50 ‰S), accompanying alterations in hemolymph osmolality and [Cl−] during hypo- (15 ‰S) or hyper- (45 ‰S) osmotic challenge. Further, we investigate posterior gill (Na+, K+)-ATPase kinetics, α-subunit immunolocalization and its mRNA and protein expression (15, 30 and 40 or 45 ‰S). The crab is a moderate, asymmetrical hyper/hypo-osmoregulator but is a strong, asymmetrical hyper/hypo-chloride regulator. Hyper-regulation at low salinity is sustained by a threefold increase in (Na+, K+)-ATPase activity, a 3.5-fold increase in α-subunit mRNA expression and 1.6-fold increase in protein expression. α-Subunit signal is highest in 15 ‰S-acclimated crabs, and is uniformly distributed throughout the ionocytes and pillar cells. Activity in 30- and 40% S-acclimated crabs is similar. Affinity for ATP and Na+ increases on high salinity acclimation but decreases for ouabain. K+ apparent affinity is independent of salinity, while that for Mg2+ decreases and for NH4+ increases with increasing salinity. A high-affinity ATP-binding site disappears on acclimation at any salinity. FOF1- and Na+- or K+-ATPase activities decrease with increased salinity. Hemolymph chloride hypo-regulation depends little on gill (Na+, K+)-ATPase activity. Hyper-, and hypo-osmotic and ionic regulatory capabilities in C. danae are intricate physiological processes underpinned by multifarious gill (Na+, K+)-ATPase kinetics and altered mRNA and protein expressions.

Sequential Afferent‐Targeted and Total Renal Denervation and Impact on Regulation of Arterial Pressure, Glomerular Filtration, and Sodium Handling in Sprague Dawley Male Rats

Renal denervation (RDNx) is often reported to chronically decrease mean arterial pressure (MAP) in conscious, unchallenged Sprague Dawley (SD) rats, but has no effect of salt-sensitivity of MAP. Although these findings indicate an important role of renal nerves in long-term regulation of MAP under unchallenged conditions, the individual contributions of sympathetic and afferent renal nerves in MAP and renal homeostasis remain unclear. The present study was conducted to test the hypothesis that efferent (sympathetic) renal nerves are the primary contributors both MAP and renal function responses to RDNx in normotensive Sprague Dawley rats. To test this hypothesis, 12 adult male Sprague Dawley rats (300-325g) were subjected to sequential denervation procedures to ablate afferent and efferent nerves separately by subjecting rats to the following surgical sequence: Sham, then afferent-targeted RDNx (A-RDNx), then complete (T)-RDNx. A-RDNx was achieved by periaxonal application of 33mM capsaicin, and T-RDNx was achieved by surgical dissection followed by perivascular application of 10%(v/v) phenol in ethanol. One week was permitted for recovery from surgery before cardiovascular and renal measurements were collected. 24-hour mean arterial pressure (MAP) was recorded by implanted telemetry. Glomerular filtration rate (GFR) was assessed in unrestrained, conscious rats by acute FITC-sinistrin clearance. Renal excretory function was assessed by measuring the urinary sodium excretion response to an acute saline challenge (150mM PBS, 10% bodyweight, i.p.) over four hours. Data was analyzed by one-way repeated-measures ANOVA with Bonferroni post-hoc test (α=0.05). Data presented as mean±SEM. Sham surgery had no significant effect on MAP, GFR or Na Clearance. Following A-RDN treatment, MAP increased ∆5.4±0.9mmHg; (p<0.01); however, no significant changes in GFR or the excretory response to acute sodium load were detected. In contrast, following T-RDN, MAP was decreased 4.9±0.9mmHg (p<.01) following T-RDN vs. compared to A-RDN. Regarding renal function, GFR increased (1.20±0.05 vs. 1.06±0.04 mL/min/100gBWT; p<.01) as did the sodium excretory response to a saline load (28.2±2.3 vs. 18.6±1.0% Na load excreted per 4 hours; p<.01). Together, these data partly support our hypothesis and solidify the role for renal efferent (sympathetic) nerves contribute to long-term regulation of MAP, GFR, and sodium handling in the conscious SD rat. Contrary to our hypothesis, A-RDNx resulted in a small, yet significant, increase in MAP; however, no impact on renal function was observed. We speculate that the increased GFR and decrease in MAP are likely due to a decrease in renal vascular resistance and dilation of the renal afferent arterioles. Moreover, renal afferent nerves appear to contribute to maintenance of MAP in Sprague Dawley rats, which we speculate is through a tonic sympatho-inhibition due to the increase MAP following A-RDNx. These data highlight the important, yet differential roles of efferent and afferent renal nerves, and further studies are underway to further test this hypothesis.

Salt-induced recruitment of specific root-associated bacterial consortium capable of enhancing plant adaptability to salt stress.

Salinity is a major abiotic stress threatening crop production. Root-derived bacteria (RDB) are hypothesized to play a role in enhancing plant adaptability to various stresses. However, it is still unclear whether and how plants build up specific RDB when challenged by salinity. In this study, we measured the composition and variation in the rhizosphere and endophyte bacteria of salt-sensitive (SSs) and salt-resistant (SRs) plants under soil conditions with/without salinity. The salt-induced RDB (both rhizobiomes and endophytes) were isolated to examine their effects on the physiological responses of SSs and SRs to salinity challenge. Moreover, we examined whether functional redundancy exists among salt-induced RDB in enhancing plant adaptability to salt stress. We observed that although SSs and SRs recruited distinct RDB and relevant functions when challenged by salinity, salt-induced recruitment of specific RDB led to a consistent growth promotion in plants regardless of their salinity tolerance capacities. Plants employed a species-specific strategy to recruit beneficial soil bacteria in the rhizosphere rather than in the endosphere. Furthermore, we demonstrated that the consortium, but not individual members of the salt-induced RDB, provided enduring resistance against salt stress. This study confirms the critical role of salt-induced RDB in enhancing plant adaptability to salt stress.