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Effects of developmental acclimation on adult salinity tolerance in the freshwater-invading copepod Eurytemora affinis.

Invasive species are commonly thought to have broad tolerances that enable them to colonize new habitats, but this assumption has rarely been tested. In particular, the relative importance of acclimation (plasticity) and adaptation for invasion success are poorly understood. This study examined effects of short-term and developmental acclimation on adult salinity tolerance in the copepod Eurytemora affinis. This microcrustacean occurs in estuarine and salt marsh habitats but has invaded freshwater habitats within the past century. Effects of short-term acclimation were determined by comparing adult survival in response to acute versus gradual salinity change to low salinity (fresh water). Effects of developmental acclimation on adult tolerance were determined using a split-brood 4 x 2 factorial experimental design for one brackish-water population from Edgartown Great Pond, Massachusetts. Twenty full-sib clutches were split and reared at four salinities (fresh, 5, 10, and 27 practical salinity units [PSU]). On reaching adulthood, clutches from three of the salinity treatments (no survivors at fresh) were split into low- (fresh) and high- (40 PSU) salinity stress treatments, at which survival was measured for 24 h. Short-term acclimation of adults did not appear to have a long-term affect on low-salinity tolerance, given that gradual transfers to fresh water enhanced survival relative to acute transfers in the short term (after 7 h) but not over a longer period of 8 d. Developmental acclimation had contrasting effects on low- versus high-salinity tolerance. Namely, rearing salinity had a significant effect on tolerance of high-salinity (40 PSU) stress but no significant effect on tolerance of low-salinity (freshwater) stress. In addition, there was a significant effect of clutch on survival under freshwater conditions, indicating a genetic component to low-salinity tolerance but no significant clutch effect in response to high salinity. While developmental acclimation might enhance survival at higher salinities, the minimal effect of acclimation and significant effect of clutch on low-salinity tolerance suggest the importance of natural selection during freshwater invasion events.

Acclimatization↗

PubMed2002

Can the nitrogenous composition of xylem sap be used to assess salinity stress in Casuarina glauca?

It is predicted that dryland salinity will affect up to 17 Mha of the Australian landscape by 2050, and therefore, monitoring the health of tree plantings and remnant native vegetation in saline areas is increasingly important. Casuarina glauca Sieber ex Spreng. has considerable salinity tolerance and is commonly planted in areas with a shallow, saline water table. To evaluate the potential of using the nitrogenous composition of xylem sap to assess salinity stress in C. glauca, the responses of trees grown with various soil salinities in a greenhouse were compared with those of trees growing in field plots with different water table depths and groundwater salinities. In the greenhouse, increasing soil salinity led to increased allocation of nitrogen (N) to proline and arginine in both stem and root xylem sap, with coincident decreases in citrulline and asparagine. Although the field plots were ranked as increasingly saline-based on ground water salinity and depth-only the allocation of N to citrulline differed significantly between the field plots. Within each plot, temporal variation in the composition of the xylem sap was related to rainfall, rainfall infiltration and soil salinity. Periods of low rainfall and infiltration and higher soil salinity corresponded with increased allocation of N to proline and arginine in the xylem sap. The allocation of N to citrulline and asparagine increased following rainfall events where rain was calculated to have infiltrated sufficiently to decrease soil salinity. The relationship between nitrogenous composition of the xylem sap of C. glauca and soil salinity indicates that the analysis of xylem sap is an effective method for assessing changes in salinity stress in trees at a particular site over time. However, the composition of the xylem sap proved less useful as a comparative index of salinity stress in trees growing at different sites.

Arginine↗

PubMed2002

The usefulness of a 10% air-10% blood-80% saline mixture for contrast echocardiography: Doppler measurement of pulmonary artery systolic pressure.

OBJECTIVES: We assessed an air-blood-saline mixture for Doppler measurement of pulmonary artery systolic pressure (PASP) and the mechanism of enhancement of the Doppler signal by this mixture. BACKGROUND: Underestimation of PASP by Doppler echocardiography occurs with inadequate continuous wave (CW) signals of tricuspid regurgitation (TR). METHODS: We assessed in vitro the diameter and concentration of microbubbles of agitated air-saline mixture, air-blood-saline mixture and 10% air-10% plasma-80% saline mixture immediately, 5, 10 and 20 s after agitation. In 20 patients, PASP was estimated by Swan-Ganz catheter and CW Doppler of TR: 1) without contrast injection; 2) with intravenous injection of 10% air-90% saline; and 3) 10% blood-10% air-80% saline mixture. RESULTS: Compared to air-saline, addition of blood or plasma to the air-saline solution significantly increased the concentration of microbubbles (p < 0.001). The air-blood-saline (26.7 +/- 7.2 microm) and air-plasma-saline mixture (25.3 +/- 7.4 microm) had smaller microbubbles than air-saline mixture (31.6 +/- 8.2 microm) (p < 0.001). The correlation between Doppler- and catheter-measured PASP at baseline (r = 0.64) improved with agitated air-saline (r = 0.86). With the air-blood-saline mixture, the correlation further improved (r = 0.92) and the best limits of agreement were obtained. CONCLUSIONS: The combination of the patient's own blood is a method of making a sterile solution of numerous small microbubbles for injection into the right-sided cardiac chambers. Clinically, the air-blood-saline mixture is easily prepared at bedside and is superior to the air-saline mixture in assessing PASP in patients with inadequate CW Doppler signals.

Blood Pressure↗

PubMed2002

Influence of saline irrigation on growth, ion accumulation and partitioning, and leaf gas exchange of carrot (Daucus carota L.).

Like those of many horticultural crop species, the growth and leaf gas exchange responses of carrot (Daucus carota L.) to salinity are poorly understood. In this study ion accumulation in root tissues (periderm, xylem and phloem tissues) and in leaves of different ages was assessed for carrot plants grown in the field with a low level of salinity (5.8 mM Na(+) and 7.5 mM Cl(-)) and in a glasshouse with salinity ranging from 1-80 mM. At low levels of salinity (1-7.5 mM), in both the field and glasshouse, carrot leaves accumulated high concentrations of Cl(-) (140-200 mM); these appear to be the result of a high affinity for Cl(-) uptake and a low retention of Cl(-) in the root system. However, Cl(-) uptake is under tight control, with an 80-fold increase in external salinity resulting in only a 1.5-fold change in the Cl(-) concentration of the shoot and no increase in the Cl(-) concentration of the root xylem tissue. In contrast to Cl(-), shoot Na(+) concentrations were comparatively low (30-40 mM) but increased by seven-fold when salinity was increased by 80-fold. Growth over the 56-d treatment period in the glasshouse was insensitive to salinity less than 20 mM, but at higher concentrations the yield of carrot tap roots declined by 7 % for each 10 mM increase in salinity. At low levels of salinity the accumulation of high concentrations of Cl(-) (150 mM) in carrot laminae did not appear to limit leaf gas exchange. However, photosynthesis and stomatal conductance were reduced by 38 and 53 %, respectively, for plants grown at a salinity of 80 mM compared with those grown at 1 mM. Salinity-induced reductions in both p(i) and carbon isotope discrimination (delta) were small (2.5 Pa and 1.4 per thousand, respectively, at 80 mM) indicating that the reduction in photosynthesis was only marginally influenced by CO(2) supply. At a salinity of 80 mM the photosynthetic capacity was reduced, with a 30 % reduction in the CO(2)-saturated rate of photosynthesis (A(max)) and a 40 % reduction in both the apparent rate of RuBP-carboxylase-limited CO(2) fixation (V(cmax)) and the electron transport rate limiting RuBP regeneration (J(max)). This study has shown that carrot growth and leaf gas exchange are insensitive to the high leaf Cl(-) concentrations that occur at low levels (1-7 mM) of salinity. However, growth is limited at salinity levels above 20 mM and leaf gas exchange is limited at salinity levels above 8 mM.

Biological Transport↗

PubMed1997

Hemodilution, central blood volume, and renal responses after an isotonic saline infusion in humans.

To test the hypothesis that hemodilution is a mediator of the renal responses to an isotonic saline infusion in the supine position, eight males underwent 1) intravenous infusion of 1.5 liter of saline over 21 min (Saline), 2) infusion of 1.5 liter of saline in combination with lower body negative pressure for 3 h (LBNP+Saline) to maintain central blood volume unchanged, and 3) a control study without infusion or LBNP. During the Saline series, central venous pressure (CVP) and left atrial diameter (LAD) increased by 4.4 +/- 0.6 mmHg and 2.6 +/- 0.4 mm (P < 0.05), respectively, whereafter they declined toward preinfusion levels. During LBNP+Saline, CVP and LAD were unchanged. Plasma colloid osmotic pressure remained unchanged during control and showed identical decreases by 5 mmHg (P < 0.05) in the Saline and LBNP+Saline series. During the 3rd h of LBNP, renal sodium excretion (U(Na)V) peaked at 296 +/- 55 micromol/min vs. a higher value of 383 +/- 54 micromol/min (P < 0.05) during Saline. The increase in U(Na)V above that of control during the 3rd h of LBNP+Saline constituted 48% of that during Saline. Plasma renin activity and plasma aldosterone concentration showed similar patterns of decrease after saline infusion irrespective of LBNP, whereas plasma norepinephrine was elevated late in the LBNP period compared with during Saline and control (P < 0.05). It is concluded that the maintenance of a constant CVP and LAD reduces the natriuresis of acute saline loading by about one-half. Thus hemodilution in conjunction with suppression of renin and aldosterone release (independent of change in CVP and LAD) might account for the remaining natriuresis of infusion.

Adult↗

PubMed1997

Effects of hypertonic saline on regional function and blood flow in canine hearts during acute coronary occlusion.

Small-volume resuscitation using hypertonic saline (7.5%) is effective for various types of shock. Recently, hypertonic saline has been proposed for fluid management in patients with impaired cardiovascular function. Whether hypertonic saline is safe in the compromised heart during coronary occlusion is not known. We examined the effects of hypertonic saline at 4 mL.kg-1 on myocardial function and blood flow during acute coronary occlusion. In anesthetized dogs, the left ventricle (LV) was instrumented with pressure and ultrasonic dimension transducers. Myocardial contractility was assessed using percent of systolic shortenings measured in both normal or ischemic regions. Blood flow distribution was measured using radioactive microspheres. Percent of systolic shortening and blood flow in the normal myocardium, unaltered by coronary occlusion, increased significantly after hypertonic saline from 11.0 +/- 1.1% to 13.7 +/- 1.4% and from 120 +/- 13 mL.min-1.100 g-1 to 169 +/- 13 mL.min-1.100 g-1, respectively. In the ischemic myocardium, occlusion of the left anterior descending coronary artery markedly decreased percent of systolic shortening from 13.0 +/- 1.2% to 9.3 +/- .9% and blood flow from 98 +/- 13 mL.min-1.100 g-1 to 19 +/- 10 mL.min-1.100 g-1. At peak effect of hypertonic saline contractility and blood flow in the ischemic myocardium decreased to 7.4 +/- .8% and 12 +/- 5 mL.min-1.100 g-1, respectively. Five of the nine dogs developed premature ventricular beats during hypertonic saline infusion. However, no significant changes were observed when normal saline was given at equivalent volumes to hypertonic saline in six dogs. Hypertonic saline was associated with significant increases in heart rate (from 116 +/- 3 beats.min-1 to 129 +/- 5 beats.min-1) and cardiac output (from 2.54 +/- .17 L.min-1 to 3.32 +/- .26 L.min-1). Except for an improved perfusion in the skin, hepatic arterial, and coronary beds, blood flow to the muscle, spleen, jejunum, kidney, and brain was not significantly altered by hypertonic saline. Our data demonstrates variant effects of hypertonic saline on either normal or ischemic myocardium. Whereas contractile function and blood flow in the normal myocardium were improved after hypertonic saline infusion, further decreases in blood flow and contractile function in region distal to coronary occlusion could lead to worsening of ischemic injury. These data suggest that hypertonic saline may be deleterious in hearts with impaired contractile function caused by ischemia.

Animals↗

PubMed2004

Hypertonic saline-enhanced postburn gut barrier failure is reversed by inducible nitric oxide synthase inhibition.

OBJECTIVE: To determine whether inhibition of inducible nitric oxide synthase to stabilize endothelial permeability and to retain hypertonic saline in the vascular space will ameliorate burn-induced gut barrier dysfunction. DESIGN: Prospective, experimental study. SETTING: Research laboratory at a university hospital. SUBJECTS: Thermal injury models in the rat. INTERVENTIONS: In experiment 1, specific pathogen free rats underwent 3% total body surface area burn or sham burn and were given 7.5 mL/kg hypertonic saline (7.5% NaCl), 7.5 mg/kg saline, or 50 mL/kg saline (nearly equal sodium load with hypertonic saline) in the right femoral vein for 15 mins for fluid resuscitation at 0, 4, or 8 hrs after burn. In experiment 2, S-methylisothiourea (7.5 mg/kg, intraperitoneally), a specific inducible nitric oxide synthase inhibitor, was given immediately after burn to rats from different groups as in experiment 1. At 24 hrs after burn, the intestinal mucosa was assayed for myeloperoxidase activity and lipid peroxidation, the distribution of fluorescein isothiocyanate-dextran across the lumen of the small intestine was determined, and bacterial translocation to the mesenteric lymph nodes and ileum histology were also examined. MEASUREMENTS AND MAIN RESULTS: Burn induced significant increases in intestinal mucosa inducible nitric oxide synthase expression, myeloperoxidase activity, lipid peroxidation, intestinal permeability, bacterial translocation to mesenteric lymph nodes, and villi sloughing in rats. Hypertonic saline administration at 0 or 4 hrs after burn worsened intestinal mucosa lipid peroxidation, neutrophil sequestration, intestinal permeability, and villi sloughing compared with those of burn + 7.5 mg/kg saline and burn + 50 mL/kg saline rats. To the contrary, burn + S-methylisothiourea rats with hypertonic saline injection at 4 or 8 hrs after burn showed an improvement of gut barrier function compared with burn + S-methylisothiourea + 7.5 mg/kg saline and burn + S-methylisothiourea + 50 mL/kg saline rats. Administration of hypertonic saline at 8 hrs after burn and S-methylisothiourea injection also significantly attenuated the bacterial translocation to mesenteric lymph nodes and villi sloughing. CONCLUSIONS: Using hypertonic saline as a resuscitation fluid in early burn shock markedly augmented the thermal injury-induced intestinal mucosa neutrophil deposition, lipid peroxidation, and intestinal hyperpermeability. Inhibition of inducible nitric oxide synthase not only significantly attenuated neutrophil deposition and mucosa lipid peroxidation but also reversed the deteriorating effects of hypertonic saline on thermal injury-induced gut barrier dysfunction and bacterial translocation.

Animals↗

PubMed1996

Comparison between hypertonic and isotonic saline-induced sputum in the evaluation of airway inflammation in subjects with moderate asthma.

BACKGROUND: Hypertonic saline-induced sputum has recently been used for the evaluation of airway inflammation in asthma. OBJECTIVE: To assess the effect of hypertonicity on airway inflammation. METHODS: We compared the inflammatory cell composition of hypertonic saline-induced sputum with that of isotonic saline-induced sputum in 21 asthmatic subjects and, at baseline and 30 min after each sputum induction, we measured bronchial hyper-responsiveness to methacholine as an indirect marker to detect increased airway inflammation. On two different days, the patients inhaled hypertonic saline (3-5% NaCl) or isotonic saline (0.9% NaCl) for 30 min via an ultrasonic nebulizer, while monitoring FEV1. Sputum was collected for inflammatory cell analysis. RESULTS: There was no difference in inflammatory cell percentages obtained with the two methods. Eosinophils were > 1% in 20 subjects after hypertonic saline and in 16 subjects after isotonic saline, but this difference was not statistically significant. Intraclass correlation coefficients for sputum inflammatory cells obtained with the two methods were +0.642 for eosinophils, +0.644 for neutrophils, +0.544 for lymphocytes and +0.505 for macrophages. Hypertonic saline induced bronchoconstruction in a significantly greater number of subjects than isotonic saline. Also, hypertonic saline increased bronchial responsiveness to methacholine, while isotonic saline did not. CONCLUSION: We conclude that hypertonicity does not affect sputum cell composition, suggesting that inflammatory cells in hypertonic saline-induced sputum are probably preexisting and not acutely recruited in the airways by the hypertonic stimulus. However, the bronchoconstriction and the increase in bronchial hyper-responsiveness after hypertonic saline inhalation may imply the release of inflammatory mediators. This fact must be considered in the evaluation of soluble markers of inflammation in hypertonic saline-induced sputum.

Adolescent↗

PubMed2006

Salinity and light interactively affect neotropical mangrove seedlings at the leaf and whole plant levels.

We have studied the interactive effects of salinity and light on Avicennia germinans mangrove seedlings in greenhouse and field experiments. We hypothesized that net photosynthesis, growth, and survivorship rates should increase more with an increase in light availability for plants growing at low salinity than for those growing at high salinity. This hypothesis was supported by our results for net photosynthesis and growth. Net daily photosynthesis did increase more with increasing light for low-salinity plants than for high-salinity plants. Stomatal conductance, leaf-level transpiration, and internal CO(2) concentrations were lower at high than at low salinity. At high light, the ratio of leaf respiration to assimilation was 2.5 times greater at high than at low salinity. Stomatal limitations and increased respiratory costs may explain why, at high salinity, seedlings did not respond to increased light availability with increased net photosynthesis. Seedling mass and growth rates increased more with increasing light availability at low than at high salinity. Ratios of root mass to leaf mass were higher at high salinity, suggesting that either water or nutrient limitations may have limited seedling growth at high salinity in response to increasing light. The interactive effects of salinity and light on seedling size and growth rates observed in the greenhouse were robust in the field, despite the presence of other factors in the field--such as inundation, nutrient gradients, and herbivory. In the field, seedling survivorship was higher at low than at high salinity and increased with light availability. Interestingly, the positive effect of light on seedling survivorship was stronger at high salinity, indicating that growth and survivorship rates are decoupled. In general, this study demonstrates that environmental effects at the leaf-level also influence whole plant growth in mangroves.

Avicennia↗

PubMed2005

A method to determine which nutrient is limiting for plant growth in estuarine waters--at any salinity.

A method, utilising overlaid graphs for nutrients vs salinity, was developed in order to determine which nutrient is limiting for plant growth in estuarine waters-at any salinity. Dissolved inorganic nitrogen (DIN=NO(3)(-)+NO(2)(-)+NH(4)(+)) and o-phosphate (PO(4)(-)) are the main forms of N and P that are readily bio-available for plant growth in waters and these have a Redfield atomic ratio of N:P=16:1 (i.e. aquatic plants absorb N and P in the average ratio of 16 atoms of N to 1 atom of P). Graphs are prepared for (i) DIN vs salinity and (ii) o-phosphate vs salinity with the vertical scales for DIN and o-phosphate set at a ratio of N:P=16:1; when these graphs are overlaid on each other then the lowermost trendline denotes the limiting nutrient for plant/algal growth-at any salinity. The graphs also indicate the extent by which one or other of the nutrients is limiting--at any salinity. Furthermore, if there is a transition from P to N limitation somewhere along the salinity gradient, then this occurs at the salinity where the trendlines intersect. The concept was applied to three estuaries in the southeast of Ireland and the results show that, in all of these circumstances, P is the limiting nutrient throughout--except for the higher salinities (i.e. salinities 30 per thousand), where either (i) N and P may become equally limiting at salinity approximately 35 per thousand or (ii) N may become limiting at salinity 30 per thousand. Overlaid nutrients vs salinity graphs were also used to demonstrate that, in the estuaries in southeast Ireland, carbon (as dissolved inorganic carbon, DIC=CO(2)+H(2)CO(3)+HCO(3)(-)+CO(3)(2-)) is not the limiting nutrient--at any salinity.

Carbon↗

PubMed2006

Salinity tolerance of 'Valencia' orange trees on rootstocks with contrasting salt tolerance is not improved by moderate shade.

The effects of shading in combination with salinity treatments were studied in citrus trees on two rootstocks with contrasting salt tolerance to determine if shading could reduce the negative effects of salinity stress. Well-nourished 2-year-old 'Valencia' orange trees grafted on Cleopatra mandarin (Cleo, relatively salt tolerant) or Carrizo citrange (Carr, relatively salt sensitive), were grown either under a 50% shade cloth or left unshaded in full sunlight. Half the trees received no salinity treatment and half were salinized with 50 mM Cl- during two 9 week salinity periods in the spring and autumn interrupted by an 11 week rainy period. The shade treatment reduced midday leaf temperature and leaf-to-air vapour pressure deficit regardless of salinity treatments. In non-salinized trees, shade increased midday CO2 assimilation rate (A(CO2)) and stomatal conductance, but had no effect on leaf transpiration (E(lf)). Shade also increased leaf chlorophyll and photosynthetic water use efficiency (A(CO2)/E(lf)) in leaves on both rootstocks and increased total plant dry weight in Cleo. The salinity treatment reduced leaf growth and leaf gas exchange parameters. Shade decreased Cl- concentrations in leaves of salinized Carr trees, but had no effect on leaf or root Cl- of trees on Cleo. There were no significant differences in leaf gas exchange parameters of shaded and unshaded salinized plants but the growth reduction from salinity stress was actually greater for shaded than for unshaded trees. Shaded trees on both rootstocks had higher leaf Na+ than unshaded trees after the first salinity period, and this shade-induced elevated leaf Na+ persisted after the second salinity period in trees on Carr. Thus, shading did not alleviate the negative effects of salinity on growth and Na+ accumulation.

Carbon Dioxide↗

PubMed2002

Resuscitation from severe hemorrhagic shock after traumatic brain injury using saline, shed blood, or a blood substitute.

The original purpose of this study was to compare initial resuscitation of hemorrhagic hypotension after traumatic brain injury (TBI) with saline and shed blood. Based on those results, the protocol was modified and saline was compared to a blood substitute, diaspirin cross-linked hemoglobin (DCLHb). Two series of experiments were performed in anesthetized and mechanically ventilated (FiO2 = 0.4) pigs (35-45 kg). In Series 1, fluid percussion TBI (6-8 ATM) was followed by a 30% hemorrhage. At 120 min post-TBI, initial resuscitation consisted of either shed blood (n = 7) or a bolus of 3x shed blood volume as saline (n = 13). Saline supplements were then administered to all pigs to maintain a systolic arterial blood pressure (SAP) of >100 mmHg and a heart rate (HR) of <110 beats/min. In Series 2, TBI (4-5 ATM) was followed by a 35% hemorrhage. At 60 min post-TBI, initial resuscitation consisted of either 500 mL of DCLHb (n = 6) or 500 mL of saline (n = 5). This was followed by saline supplements to all pigs to maintain a SAP of >100 mmHg and a HR of <110 beats/min. In Series 1, most systemic markers of resuscitation (e.g., SAP, HR, cardiac output, filling pressures, lactate, etc.) were normalized, but there were 0/7 vs. 5/13 deaths within 5 h (P = 0.058) with blood vs. saline. At constant arterial O2 saturation (SaO2), mixed venous O2 saturation (SvO2), cerebral perfusion pressure (CPP), and cerebral venous O2 saturation (ScvO2) were all higher, intracranial pressure (ICP) was lower, and CO2 reactivity was preserved with blood vs. saline (all P < 0.05). In Series 2, SAP, ICP, CPP, and lactate were higher with DCLHb vs. saline (all P< 0.05). Cardiac output was lower even though filling pressure was markedly elevated with DCLHb vs. saline (both P< 0.05). Neither SvO2 nor cerebrovascular CO2 reactivity were improved, and ScvO2 was lower with DCLHb vs. saline (P < 0.05). All survived at least 72 h with neuropathologic changes that included sub-arachnoid hemorrhage, midline cerebellar necrosis, and diffuse axonal injury. These changes were similar with DCLHb vs. saline. Thus, whole blood was more effective than saline for resuscitation of TBI, whereas DCLHb was no more, and according to many variables, less effective than saline resuscitation. These experimental results are comparable to those in a recent multicenter trial using DCLHb for the treatment of severe traumatic shock. Further investigations in similar experimental models might provide some plausible explanations why DCLHb unexpectedly increased mortality in patients.

Animals↗

PubMed1996

Salinity change and cell volume: the response of tissues from the estuarine mussel Geukensia demissa.

The response of cell volume to changes in external salinity was assessed in four tissues (gill, mantle, hemolymph cells and ventricle) of the estuarine mussel Geukensia demissa by using one or more of the following three indicators of cell volume response: changes in cell dimensions, cell water space and cell solute content. All three techniques indicated that short-term volume regulation was generally absent from gill tissue. Lateral cell height in gills, measured using differential interference contrast (DIC) microscopy, increased by approximately 20% after an abrupt exposure to reduced salinity (60% artificial sea water, ASW). There was significant variability in the observance of a regulatory volume decrease (RVD) subsequent to the initial swelling; cells remained swollen for 1 h after low-salinity exposure in two-thirds of the trials, while there was a return of cell volume towards control values in the remaining one-third of the trials. Lateral cell height increased linearly when salinity was gradually decreased from 100 to 60% ASW over 135 min. Cell height then returned to control values when the salinity was abruptly returned to 100% ASW, indicating that an RVD was not elicited by a slow change in salinity of the type normally encountered by estuarine mussels. Cumulative cell water space in gills increased by 47% after exposure to 60% ASW and the cells remained swollen for at least 4 h, returning to control values when gills were returned to 100% ASW. Consistent with the overall lack of an RVD, there was only a small decrease (approximately 5%) in cumulative osmolyte content (primarily taurine, betaine and K+) after 4 h in 60% ASW. Decreases in both cell water space and osmolyte content after 3 weeks of acclimation to 60% ASW indicated a long-term RVD of approximately 60%. Individual cells in the mantle epithelium also generally lacked an RVD in response to lowered salinity. Both abrupt and gradual decreases in salinity caused an increase in mantle cell height to a maximum of 25-30%, and cell height returned to the control height when salinity was abruptly returned to 100% ASW. Corresponding with the lack of an RVD in individual mantle cells, there was no change in solute content of the mantle tissue after 4 h of exposure to low salinity. The response of the volume of spherical hemolymph cells to 1 h of abrupt exposure to low salinity, calculated from measured cell diameters, likewise indicated that an RVD is generally lacking in these hemolymph cells. In the ventricle, however, there was a significant decrease in amino acid and betaine content after 4 h of exposure to low salinity, suggesting tissue-specific variability in the cellular response to salinity change. The consistent lack of a short-term RVD in many tissues may serve to avoid large energetic expenditures associated with repeated volume regulation in the face of the frequent, short-term changes in salinity encountered by estuarine mussels.

Adaptation, Physiological↗

PubMed2005

Molecular analysis of halophilic bacterial community for high-rate denitrification of saline industrial wastewater.

A denitrification system for saline wastewater utilizing halophilic denitrifying bacteria has not been developed so far. In this study, denitrification performance and microbial community under various saline conditions were investigated using denitrifying sludge acclimated under low-salinity condition for a few years as seed sludge. A continuous denitrification experiment showed that denitrification performance and microbial community at 10% salinity was higher than that at 1% salinity. The microbial community in the denitrification sludge that was acclimated under low salinity was monitored by terminal-restriction fragment length polymorphism (T-RFLP) analysis during acclimation to high-salinity condition. T-RFLP profiles and clone analysis based on 16S rRNA-encoding genes in the sludge of the denitrification system with 10% salinity indicated that the gamma-Proteobacteria, particularly Halomonas spp., were predominant species, suggesting that these bacterial members were possibly responsible for a high denitrification activity under high-salinity conditions. Furthermore, the investigation of denitrification performance under various saline conditions revealed that 4-10% salinity results in the highest denitrification rate, indicating that this salinity was optimal for predominant bacterial species to exhibit denitrification activity. These results indicate the possibility that an appropriate denitrification system for saline wastewater can be designed using acclimated sludge with a halophilic community.

Bacteria↗

PubMed1999

Metamorphosis in the summer flounder, Paralichthys dentatus: thyroidal status influences salinity tolerance.

Metamorphosis in the summer flounder (Paralichthys dentatus) is controlled by thyroid hormones (TH) and takes place as the larvae move from a salinity of about 35 parts per thousand (ppt) in the ocean to salinity ranging from 0-35 ppt in estuaries. Historically, the role of TH in juvenile and adult teleost osmoregulation has been ambiguous, and it is not known if TH influences larval teleost osmoregulatory development. This study addresses the influence of thyroxine (T4) on the development of tolerance to low (5 ppt) and high salinity (45 and 50 ppt) as determined by salinity tolerance tests. In untreated larvae, tolerance to both low and high salinity was high during early premetamorphosis (early pre-M) and decreased or was very low from late prometamorphosis (late pro-M) through mid-metamorphic climax (mid-MC). Salinity tolerance increased 2-3-fold during late MC when whole-animal T4 levels are highest, and reached maximum tolerance at the juvenile stage. The early induction of metamorphosis by exposing larvae in pre-M to exogenous T4 reduced tolerance to low salinity during early and mid-MC, though tolerance of fish that had developed into juveniles was not impaired. In contrast, T4 increased high salinity tolerance during early and mid-MC, and the juvenile stage. This T4-induced heterochrony in salinity tolerance with regards to developmental stage suggests that the effects of T4 on salinity tolerance may be uncoupled from accelerated metamorphosis. Treatment of larvae with thiourea (TU, an inhibitor of T4 synthesis) inhibited metamorphosis and reduced tolerance to high salinity, but did not affect tolerance to low salinity. Reduced tolerance to high salinity by TU was only partially counteracted by T4 treatment, suggesting that TU also affects hypoosmoregulatory activity by an extrathyroidal mechanism. Our findings suggest that in the summer flounder T4 plays a more important role in the development of hypoosmoregulatory ability than hyperosmoregulatory ability. J. Exp. Zool. 284:414-424, 1999.

Adaptation, Physiological↗

PubMed1997

Saline-filled breast implants: a Plastic Surgery Educational Foundation multicenter outcomes study.

In 1993, the Plastic Surgery Educational Foundation commissioned the senior author (Cunningham) to design an 11-center retrospective cohort outcomes study to obtain physician- and patient-reported data on saline-filled breast implants. Data were obtained from 504 patients with 995 saline-filled breast implants placed between January 1, 1980 and December 31, 1989, with a mean follow-up of 6 years. Most (93.8 percent) saline-filled breast implants were placed for breast augmentation. Of the 504 patients, 104 (20.6 percent) required reoperation for open capsulotomy or for replacement or removal of a deflated implant. Complications occurred in 22 patients (4.4 percent), with hematoma being most common. Implant deflation occurred in 55 implants (5.5 percent) and affected 51 patients (10.1 percent) but was underreported by chart abstraction alone. Risk factors for implant deflation included underfilling the implant by more than 25 cc (odds ratio 3.3, p = 0.0400), the use of model 1800 saline-filled breast implants (odds ratio 3.1, p = 0.0010), intraluminal antibiotics (odds ratio 2.6, p = 0.0183), and intraluminal steroids (odds ratio 2.4, p = 0.0711). Based on 44 of 55 saline-filled breast implants with known deflation dates, actuarial survival is 95.7 to 98.0 percent at 5 years and 90.2 to 95.2 percent at 10 years (95 percent confidence interval). Significant periprosthetic capsular contracture affected 103 patients (20.4 percent) during follow-up. Risk factors for capsular contracture included omitting intraluminal antibiotics (odds ratio 16.7, p = 0.0001), omitting intraluminal steroids (odds ratio 12.5, p = 0.0001), submammary placement of the saline-filled breast implant (odds ratio 7.8, p = 0.0001), and use of antibiotics in the implant pocket (odds ratio 6.1, p = 0.0001). Overall patient satisfaction with saline-filled breast implants was rated as high by 94.2 percent, and 94.8 percent of patients would choose saline-filled breast implants again. Dissatisfaction with their saline-filled breast implants was more frequent in patients with significant breast firmness (odds ratio 22.9, p = 0.0001), those undergoing prophylactic mastectomy (odds ratio 8.2, p = 0.0005), and those desiring smaller implants (odds ratio 6.9, p = 0.0001). In conclusion, saline-filled breast implants are a safe alternative to silicone gel-filled breast implants and demonstrate a high rate of patient satisfaction. Underfilling of saline-filled breast implants should be avoided because it contributes to deflation. Although intraluminal antibiotics and steroids protect against capsular contracture, they also contribute to saline-filled breast implant deflation. The incidence of capsular contracture is decreased by placing the saline-filled breast implant in the subpectoral position. Finally, patients should be aware of the possible need for reoperations related to their implants.

Actuarial Analysis↗

PubMed2006

Characteristics of bacteria showing high denitrification activity in saline wastewater.

AIMS: Denitrification efficiency at 10% salinity was compared with that at 2% salinity. The characteristics of bacterial strains isolated from the denitrification system, where an improvement of denitrification efficiency was observed at a high salinity were investigated. METHODS AND RESULTS: Two continuous feeding denitrification systems for saline solutions of 2% and 10% salinity, were operated. Denitrification efficiency at 10% salinity was higher than that at 2% salinity. The bacterial strains were isolated using the trypticase soy agar (TSA) medium at 30 degrees C. The phylogenetic analysis of 16S rRNA gene sequences of isolates indicated that halophilic species were predominant at 10% salinity. CONCLUSIONS: The improvement of denitrification efficiency at a high salinity was demonstrated. The strains isolated from the denitrifying system with 10% salinity were halophilic bacteria, Halomonas sp. and Marinobacter sp., suggesting that these bacteria show a high denitrifying activity at 10% salinity. SIGNIFICANCE AND IMPACT OF THE STUDY: The long-term acclimated sludge used in this study resulted in high denitrification performance at a high salinity, indicating that the design of a high-performance denitrification system for saline wastewater will be possible.

Alteromonadaceae↗

PubMed1996

The effects of salinity change on the exercise performance of two Atlantic cod (Gadus morhua) populations inhabiting different environments

The objective of this study was to determine whether differences in exercise physiology between Atlantic cod (Gadus morhua) populations from different salinity environments could be changed by acclimating individuals of each population to the natural salinity of the comparison population. The exercise-associated blood chemistry of cod from the brackish Bras d'Or lakes, which had previously been shown to be quite different from that of 'open-ocean' cod, changed to resemble the blood chemistry of their oceanic relatives after only 2 months of acclimation to full-strength salinity. In contrast, the blood chemistry of cod from the Scotian Shelf of the Northwest Atlantic Ocean showed little change after 2 months of acclimation to brackish water. These results demonstrate that the degree of osmoconformity to changes in environmental salinity is a population-specific not a species-specific trait. The blood chemistry differences between populations and salinities did not translate into differences in exercise performance: i.e. critical swimming speeds were statistically uniform across all combinations of population and salinity, although performance was more varied in fish swimming in 'non-native' waters. Other 'whole-animal' physiological characteristics, such as metabolic rate and the aerobic cost of transport, were dependent upon both population origin and the environmental salinity. Vigorous swimming was more energetically expensive at full-strength salinity than at 20 salinity, yet estimates of standard (i.e. resting) metabolic rate were lower for full-strength salinity. Environmental salinity also influenced the relative appearance of lactate and metabolic acid in the extracellular fluid compartment, with full-strength salinity favouring the relative appearance of lactate in the blood. Multivariate statistical analyses of this data set showed that, in contrast to other fish species and studies, differences in blood oxygen transport appear to account for some of the swimming performance differences seen in Atlantic cod at 2 °C. The two experimental populations were cleanly separated by a principal components analysis, regardless of the salinity to which they were acclimated, confirming our earlier contention that these cod populations are physiologically distinct. A key feature of that distinctness is the greater phenotypic plasticity exhibited by the population from the more euryhaline, more eurythermal environment.

Journal Article↗