Saline Challenge Research Articles

Osmoregulatory capabilities of the gray snapper, Lutjanus griseus: salinity challenges and field observations

We investigated the osmoregulatory responses (plasma osmolality and blood hematocrit) displayed by the gray snapper 6–192 h after abrupt changes in ambient salinity. Fish were challenged with six different salinity treatments including a control (0, 5, 30, 50, 60, and 70 ppt) and blood samples were collected at various time points post-transfer. Gray snapper across all size classes tested (13.5–24.5 cm total length) acclimated successfully to hypo- and hyper-saline environments (0–60 ppt) after an adjustment period of ∼96 h. However, abrupt transfers to 70 ppt resulted in 100% mortality within 48 h. Laboratory results were then compared with field measurements obtained after fish were captured in low salinity (0–4 ppt) or marine (∼30 ppt) habitats, suggesting that osmoregulatory processes occurred similarly in both settings. Overall, findings suggest that gray snapper possess similar or higher osmoregulatory capabilities compared to many euryhaline species examined to date, and thus should be considered a euryhaline species.

The effect of heparin administration in animal models of sepsis: A prospective study in Escherichia coli-challenged mice and a systematic review and metaregression analysis of published studies*

If thrombosis contributes to sepsis, heparin titrated using activated partial thromboplastin times may be efficacious. We investigated heparin in preclinical models. In unchallenged mice (n = 107), heparin at 100, 500, or 2500 units/kg produced activated partial thromboplastin time levels less than, within, or greater than a prespecified therapeutic range (1.5-2.5 times control), respectively. In animals (n = 142) administered intratracheal Escherichia coli challenge, compared to placebo treatment, heparin at 100, 500, or 2500 units/kg were associated with dose dependent increases in the hazard ratios of death (hazard ratio [95% confidence interval]: 1.08 [0.66, 1.76]; 1.34 [0.80, 2.24]; 3.02 [1.49, 6.10], respectively) (p = .001 for the dose effect). Compared to normal saline challenge, E. coli without heparin (i.e., with placebo) increased the activated partial thromboplastin time (p = .002) close to the therapeutic range. While heparin at 100 and 500 units/kg with E. coli further increased activated partial thromboplastin time (p < .0001 vs. placebo) within or above the therapeutic range, respectively, these did not decrease inflammatory cytokines or lung injury. In metaregression analysis of published preclinical studies, heparin improved survival with lipopolysaccharide (n = 23, p < .0001) or surgically induced infection (n = 14, p < .0001) but not monobacterial (n = 7, p = .29) challenges. Coagulopathy with sepsis or other variables, such as type of infectious source, may influence the efficacy of heparin therapy for sepsis.

Comparative time-course study on pituitary and branchial response to salinity challenge in Mozambique tilapia (Oreochromis mossambicus) and Nile tilapia (O. niloticus)

The physiological response of Mozambique and Nile tilapia transferred from fresh to brackish (15 ppt) water was compared during a one-week time course. Response in the pituitary was measured by the gene expression pattern of prolactin (PRL I), growth hormone (GH), and calcium-sensing receptor (CaSR), while the response in the gills was measured by the gene expression pattern of the prolactin receptor (PRL-R), Na(+)/K(+)/2Cl(-) cotransporter (NKCC) and Na(+)/Cl(-) cotransporter (NCC), and by activity and expression of Na(+)/K(+)-ATPase (NKA). The time-course curves of plasma osmolality levels indicate a rapid elevation 24 h after transfer, which later decreased and maintained at stable level. PRL I expression decreased in both species, but with stronger response in the Nile tilapia, while no differences were found in the slightly elevated levels of GH mRNA. The branchial response demonstrated a faster up-regulation of NKA and NKCC in the Mozambique tilapia, but similar levels after a week, while Nile tilapia had stronger and constant down-regulation of NCC. The time-course response of the measured osmoregulatory parameters indicate that 24 h after transfer is a critical time point for brackish-water adaptation. The differences in responses to saltwater challenge between Mozambique and Nile tilapia shown in this study may be associated with the differences in saltwater tolerance between these two tilapiine species.

Salinity-dependent expression of the branchial Na+/K+/2Cl− cotransporter and Na+/K+-ATPase in the sailfin molly correlates with hypoosmoregulatory endurance

In the branchial mitochondrion-rich (MR) cells of euryhaline teleosts, the Na(+)/K(+)/2Cl(-) cotransporter (NKCC) is an important membrane protein that maintains the internal Cl(-) concentration, and the branchial Na(+)/K(+)-ATPase (NKA) is crucial for providing the driving force for many other ion-transporting systems. Hence this study used the sailfin molly (Poecilia latipinna), an introduced aquarium fish in Taiwan, to reveal that the potential roles of NKCC and NKA in sailfin molly were correlated to fish survival rates upon salinity challenge. Higher levels of branchial NKCC were found in seawater (SW)-acclimated sailfin molly compared to freshwater (FW)-acclimated individuals. Transfer of the sailfin molly from SW to FW revealed that the expression of the NKCC and NKA proteins in the gills was retained over 7days in order to maintain hypoosmoregulatory endurance. Meanwhile, their survival rates after transfer to SW varied with the duration of FW-exposure and decreased significantly when the SW-acclimated individuals were acclimated to FW for 21days. Double immunofluorescence staining showed that in SW-acclimated sailfin molly, NKCC signals were expressed on the basolateral membrane of MR cells, whereas in FW-acclimated molly, they were expressed on the apical membrane. This study illustrated the correlation between the gradual reductions in expression of branchial NKCC and NKA (i.e., the hypoosmoregulatory endurance) and decreasing survival rates after hyperosmotic challenge in sailfin molly.

Chronic Antigen Challenge Converts Bronchoconstriction by Inhaled Thromboxane‐mimetic, U46619, to a Bronchodilation in Conscious Sensitized Guinea‐pigs*

The study was undertaken to examine whether chronic repeated challenge of sensitized guinea-pigs with antigen would induce hyper-reactivity to the spasmogen U46619 (9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F2α). Airway function was measured in conscious guinea-pigs by whole-body plethysmography; leucocyte infiltration into the lungs was monitored using bronchoalveolar lavage. Male guinea-pigs were sensitized to ovalbumin by injection (i.p.) of a suspension (1 mL) containing ovalbumin (10 μg) and aluminium hydroxide (100 mg); they were used 14 days later. In sensitized guinea-pigs repeated inhaled antigen challenges (0.5% ovalbumin in saline for 10 min twice weekly for 4 weeks) induced a state of pulmonary inflammation characterized by an enhanced and prolonged late-phase response and a persistent eosinophilia. Inhalation of a threshold dose of the thromboxane-mimetic, U46619 (30 ng mL−1 for 60 s), 72 h after the final saline challenge of control animals caused a threshold bronchoconstriction. Seventy two hours after the final antigen challenge, however, there was a marked bronchodilation to U46619. A persistent hyper-reactivity was expected. Ro 20–1724 (3 mg kg−1 i.p. before and 6 h after each antigen challenge), a selective inhibitor of phosphodiesterase type IV, attenuated both early and late asthmatic responses and the airway eosinophilia associated with this chronic antigen challenge model. There was no evidence of a bronchodilatory response to the same dose of inhaled U46619 in the group treated with Ro 20–1724. These results suggest that inhaled low dose U46619 induces a bronchodilation when delivered to conscious guinea-pigs after a series of repeated antigen challenges and when the airways are presumably in a state of chronic inflammation. This effect is lost when the airway inflammation is attenuated by the concurrent administration of Ro 20–1724. The reason for this remains unexplained.

Do excitatory and inhibitory conditioning processes underlie psychomotor sensitization to amphetamine? An analysis using simple and multiple regressions

Excitatory or inhibitory conditioning processes have been proposed to account for the context-dependent establishment of amphetamine psychomotor sensitization in rodents. The purpose of this study was to test the predictions of these theories in mice. We first assessed the consequence of the extinction of post-sensitization conditioned activity (CR) on the ulterior expression of sensitization. We also assessed the relations between several measures of sensitization and conditioned hyperactivity revealed on a saline challenge using simple and multiple regression analyses. Context-dependent sensitization was induced via 7 amphetamine injections in the test context given alternately with 7 saline injections in another context in paired mice, unpaired mice receiving the converse pretreatment. Context-dependent sensitization (drug challenge) and the CR (saline challenge) were revealed subsequently. After CR extinction (over 7 every-other-day repetition of the saline challenge), mice were tested again for context-dependent sensitization. Against the excitatory conditioning model, CR extinction spared context-dependent sensitization in paired mice, and regression analyses revealed no significant correlations between the size of the CR and several measures of sensitization. In apparent agreement with the inhibitory conditioning model, unpaired mice expressed higher levels of sensitization in the test context after extinction than before. However, regression analyses did not indicate that activity on the saline challenge was related to measures of sensitization in unpaired mice. Therefore, the present results support neither the excitatory nor the inhibitory conditioning models of context-dependent sensitization, but remain compatible with theories proposing that other inhibitory mechanisms modulate sensitization.

Dual oxidase 2 and glutathione peroxidase gene expression are elevated in hyperimmunised sheep challenged with Haemonchus contortus

A sequential biopsy sampling method was used to investigate oxidant and antioxidant gene responses in resistant sheep challenged with Haemonchus contortus larvae or a sham saline challenge. The expression of key sheep oxidant and antioxidant producing genes were measured in sequential samples removed from the abomasums at days 0, 1, 2, 3, 5, 7 and 28 post challenge. Gene expression levels at each time point were compared to expression at day 0, and levels of the various genes were also correlated to other markers of infection including immune cell counts and cytokine gene expression. The early response to larval challenge infection in resistant animals was marked by a divergence of two groups of host oxidant producing genes: the dual oxidase group ( DUOX2/ DUOXA2) showing increases in expression to day 7, while members of the phagocytic NADPH oxidase (PHOX) group showed significant decreases in expression. The change in DUOX2 expression between days zero and seven, when host resistance to infection is mediated, was negatively correlated to final worm burden suggesting NADPH oxidase expression may play a role in parasite expulsion. Expression of the DUOX group oxidants was positively correlated to expression of the Th2 cytokine IL4. Changes in host antioxidant pathways between different members of the glutathione peroxidase family (intestinal and plasma GPX) and genes involved in glutathione metabolism were also observed. This first study of the putative roles of oxidant production by the dual oxidase group, antioxidant glutathione pathways, immune cell populations, and cytokine profiles, in the development of resistance to infection by hyperimmune sheep are discussed.

A comparison of osmoregulatory responses in plasma and tissues of rainbow trout ( Oncorhynchus mykiss) following acute salinity challenges

Euryhaline teleosts regulate their internal osmotic and ionic status across a wide range of external salinities. Studies often rely on measurements on plasma when osmoregulatory status is perturbed, whereas tissue measurements are used for small fish with limited blood volume. However, a direct comparison is lacking for plasma and various tissues. In the present study the relationships between plasma, white muscle and carcass were examined for a range of osmoregulatory variables in rainbow trout ( Oncorhynchus mykiss) following challenge with an acute (24 h) transfer from freshwater to a hyper-osmotic salinity of either 25 or 35. Significant increases in plasma osmolality, [Na +], [Cl −], [Ca 2+], and [Mg 2+] were observed when salinity was increased, but plasma [K +] was unaffected. The water content of both tissues showed reciprocal changes to plasma osmolality. The carcass content of all ions measured showed a significant increase at the highest ambient salinity. In white muscle, Na +, K + and Mg 2+ showed significant increases with external salinity, but Cl − and Ca 2+ were unaffected. Measurements from both tissues can provide reliable surrogates for most of the plasma osmoregulatory variables except Cl − and Ca 2+ when using white muscle tissue. In the case of internal regulation of K + both tissues provide sensitive and quantitatively similar indicators of environmental salinity disturbance, whereas plasma does not.

Immunolocalization of chloride transporters to gill epithelia of euryhaline teleosts with opposite salinity-induced Na+/K+-ATPase responses

Opposite patterns of branchial Na(+)/K(+)-ATPase (NKA) responses were found in euryhaline milkfish (Chanos chanos) and pufferfish (Tetraodon nigroviridis) upon salinity challenge. Because the electrochemical gradient established by NKA is thought to be the driving force for transcellular Cl(-) transport in fish gills, the aim of this study was to explore whether the differential patterns of NKA responses found in milkfish and pufferfish would lead to distinct distribution of Cl(-) transporters in their gill epithelial cells indicating different Cl(-) transport mechanisms. In this study, immunolocalization of various Cl(-) transport proteins, including Na(+)/K(+)/2Cl(-) cotransporter (NKCC), cystic fibrosis transmembrane conductance regulator (CFTR), anion exchanger 1 (AE1), and chloride channel 3 (ClC-3), were double stained with NKA, the basolateral marker of branchial mitochondrion-rich cells (MRCs), to reveal the localization of these transporter proteins in gill MRC of FW- or SW-acclimated milkfish and pufferfish. Confocal microscopic observations showed that the localization of these transport proteins in the gill MRCs of the two studied species were similar. However, the number of gill NKA-immunoreactive (IR) cells in milkfish and pufferfish exhibited to vary with environmental salinities. An increase in the number of NKA-IR cells should lead to the elevation of NKA activity in FW milkfish and SW pufferfish. Taken together, the opposite branchial NKA responses observed in milkfish and pufferfish upon salinity challenge could be attributed to alterations in the number of NKA-IR cells. Furthermore, the localization of these Cl(-) transporters in gill MRCs of the two studied species was identical. It depicted the two studied euryhaline species possess the similar Cl(-) transport mechanisms in gills.

Effects of salinity and temperature on the growth, survival, whole body osmolality, and expression of Na +/K + ATPase mRNA in red porgy ( Pagrus pagrus) larvae

Atlantic red porgy, Pagrus pagrus, is an important reef fish species in the Mediterranean and the snapper–grouper complex off the southeastern United States. Red porgy is a viable candidate for aquaculture with high market value and the ability to spawn freely in captivity. The objective of this study was to examine the combined effects of temperature and salinity on eggs, yolk-sac larvae, and early feeding-stage larvae of red porgy to day 16 post-hatching (d16ph). To determine the optimal temperature and salinity conditions for culture, embryos were reared under four temperatures (17, 19, 21, and 23 °C) and two salinities (24 and 34 g/L) in a 4 × 2 factorial design. Significant effects of temperature and salinity on growth (notochord length, wet and dry weight), survival, whole body osmolality, and expression of Na +/K + ATPase were observed with minimal interactive effects. Under both salinities, growth increased with increasing temperature. On d16ph, wet weights at 21 and 23 °C (2.03 and 2.91 mg, respectively) were significantly higher than at 17 and 19 °C (0.20 and 0.69 mg). Salinity had no effect on growth at any temperature, but had a significant effect on survival to d16ph, with greater survival at 24 g/L (18.4%) than at 34 g/L (6.77%). Salinity significantly affected whole body osmolality on d2ph and d11ph, with 24 g/L having lower whole body osmolality than 34 g/L on both days. Temperature significantly affected whole body osmolality on d6ph, with no clear trends and on d17ph, with 17 °C (534 mOsm/kg) higher than all the higher temperatures (396–411 mOsm/kg). After increasing each tank to 44 g/L to create a sublethal salinity challenge on d16ph, larvae from 34 g/L treatments did not show an increase in levels of Na +/K + ATPase mRNA after 24 or 48 h post transfer. However, fish in the 24 g/L treatments showed a significant increase in expression of Na +/K + ATPase mRNA after 24 h followed by a decrease after 48 h. Within the ranges tested, a temperature of 23 °C and a salinity of 24 g/L appear to be optimal for culture of red porgy embryos, yolk-sac, and first-feeding stage larvae to d16ph.

Increased arginase activity contributes to airway remodelling in chronic allergic asthma

Airway remodelling, characterised by increased airway smooth muscle (ASM) mass, subepithelial fibrosis, goblet cell hyperplasia and mucus gland hypertrophy, is a feature of chronic asthma. Increased arginase activity could contribute to these features via increased formation of polyamines and l-proline downstream of the arginase product l-ornithine, and via reduced nitric oxide synthesis. Using the specific arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH), we studied the role of arginase in airway remodelling using a guinea pig model of chronic asthma. Ovalbumin-sensitised guinea pigs were treated with ABH or PBS via inhalation before each of 12 weekly allergen or saline challenges, and indices of arginase activity, and airway remodelling, inflammation and responsiveness were studied 24 h after the final challenge. Pulmonary arginase activity of repeatedly allergen-challenged guinea pigs was increased. Allergen challenge also increased ASM mass and maximal contraction of denuded tracheal rings, which were prevented by ABH. ABH also attenuated allergen-induced pulmonary hydroxyproline (fibrosis) and putrescine, mucus gland hypertrophy, goblet cell hyperplasia, airway eosinophilia and interleukin-13, whereas an increased l-ornithine/l-citrulline ratio in the lung was normalised. Moreover, allergen-induced hyperresponsiveness of perfused tracheae was fully abrogated by ABH. These findings demonstrate that arginase is prominently involved in allergen-induced airway remodelling, inflammation and hyperresponsiveness in chronic asthma.

Increased in vivo [ 11C]raclopride binding to brain dopamine receptors in amphetamine-treated rats

The hypothesis that repeated daily doses of amphetamine increases the number of available dopamine D 2 receptors in vivo in rat striatum, and may enhance the response to subsequent amphetamine challenge doses, was examined. The in vivo binding potentials of [ 11C]raclopride, a D 2 receptor antagonist, were determined in male CD-1 rats under five conditions: (1) drug-naïve with saline challenge, (2) drug naïve with 5 mg/kg amphetamine challenge, (3) amphetamine-dosed (five daily repeated s.c. doses of 5 mg/kg amphetamine) and saline challenge, (4) amphetamine-dosed and amphetamine challenge, and (5) saline treated (five daily repeated s.c. doses) and saline challenged. Radiotracer studies in amphetamine-dosed animals were done after a 10-day drug free interval. In the amphetamine-dosed group the baseline [ 11C]raclopride binding was increased by 63% compared to saline-treated controls. The response to an amphetamine challenge, evidenced by a reduction of [ 11C]raclopride binding, was doubled in amphetamine-dosed animals (40%) compared to drug-naïve controls (20%). These results support increased baseline in vivo dopamine D 2 receptor antagonist radioligand binding after repeated amphetamine administration in rats.

Nasal PMN response to repeated challenge with endotoxin in healthy volunteers

Rationale: We have employed nasal challenge with lipopolysaccharide (LPS) followed by nasal lavage (NL) to experimentally induce and examine upper airway inflammation in human volunteers. It is unclear however whether adaptation within individuals occurs following repeated nasal challenge. This was a pilot study to determine if repeated nasal LPS challenge yields attenuation of markers of inflammation (primarily neutrophil response) in the NL fluid of healthy humans.Methods: We employed a 3-day nasal LPS challenge protocol with NL using a “split nose” design. The control and LPS nares received two consecutive day saline (0.9% saline/day) and LPS (2 µg LPS/day) challenges, respectively followed by an LPS (2 µg/day) challenge to each nare on Day 3. NL was performed immediately pre Day 1 challenges and 6-h post nasal LPS challenges on both Days 1 and 3. Markers of inflammation (PMNs/mg, cytokines) were assessed in NL and the inflammatory response to LPS (measured as the difference between pre and post challenge) was evaluated in both nares on Day 3 and compared to Day 1.Results: Significant (p < 0.05) blunting of the LPS-induced polymorphonuclear leukocyte (PMN) response was observed in the nare that received repeated LPS challenges as compared to the control nare (67.60 ± 22.39 vs. 157.8 ± 76.04 PMN/mg) and initial LPS challenge on Day 1 (121 ± 32 PMN/mg). Decreased soluble CD14 and significantly decreased interleukin-8 were also found in the repeat LPS-treated nare. In the LPS-treated nare, the blunted PMN response on Day 3 correlated well with the observed PMN response on Day1 (r = 0.58, p = 0.02).Conclusions: We show attenuation of PMN response to repeated LPS in the nasal airways in healthy humans. Effect of repeat endotoxin exposure prior to allergen delivery on local airway inflammation in both healthy and atopic subjects can be studied.

Local allergic rhinitis: Allergen tolerance and immunologic changes after preseasonal immunotherapy with grass pollen

Local allergic rhinitis: Allergen tolerance and immunologic changes after preseasonal immunotherapy with grass pollen

The A142V Polymorphism of the G Protein Coupled Receptor Kinase 4 Gene Predicts Natriuretic Response to Saline Challenge in Young Normotensive Lean Black and White South African Men

Sensitivity to salt is common in Blacks. We aimed to determine if blood pressure (BP) and natriuretic responses were different in indigeneous Africans (Blacks) compared to Caucasians (Whites), and if this was related to G-protein coupled receptor kinase 4 (GRK-4)polymorphisms. Sixty healthy White and Black men received 2 liters normal saline over 2 h. Baseline demographics, sodium (Na), potassium (K), renin, and aldosterone were recorded. BP, urine output, and urinary Na were measured hourly for 4 h, and renin and aldosterone repeated at 4 h. The R65L and A142V polymorphisms of the GRK-4 gene were determined. At baseline, Blacks had significantly higher diastolic BP (77 vs 71.2 mm Hg, P&lt;0.002) and K (4.57 vs 4.32 mmol/L, P=0.01), and lower aldosterone levels (132.6 vs 298.3 pmol/L, P&lt;0.0001). After saline challenge, the incremental increase of Na excretion was blunted in Blacks, and there was greater suppression of aldosterone levels. The R65L polymorphism had no effect on natriuresis or aldosterone. Incremental Na excretion was highest in the CC, intermediate in the CT and lowest in the TT of the A142V polymorphisms (P&lt;0.001). Aldosterone levels were highest in the CC group, intermediate in the CT, and lowest in the TT (P&lt;0.001). The CT/TT genotypes were significantly more common in Blacks (P&lt;0.001). Black subjects have different natriuretic and aldosterone responses to saline challenge. This appears to be determined by A142V polymorphisms.

CHARACTERIZATION OF LEPTIN AND ITS PUTATIVE RECEPTOR (LEPR) IN EURYHALINE TILAPIA: A NOVEL LINK BETWEEN ENERGY STATUS AND OSMOREGULATORY FUNCTION?

Event Abstract Back to Event CHARACTERIZATION OF LEPTIN AND ITS PUTATIVE RECEPTOR (LEPR) IN EURYHALINE TILAPIA: A NOVEL LINK BETWEEN ENERGY STATUS AND OSMOREGULATORY FUNCTION? David A. Baltzegar1, Emily S. Brune1, William M. Johnstone1 and Russell J. Borski1* 1 North Carolina State University, Department of Biology, United States Leptin is secreted by adipocytes and acts via its cytokine receptor (LepR) to reduce appetite. Additionally, leptin has multiple peripheral actions including stimulation of reproductive maturity, immunity, and epithelial tissue development. In teleost fishes, the actions of leptin remain poorly described, however similar effects upon appetite have been reported. Leptin stimulates pituitary prolactin secretion in tilapia (Oreochromis mossambicus), and in mammals may itself be responsive to elevated cortisol. As prolactin and cortisol are major hormones controlling osmoregulation, leptin may be a critical link in the integrated endocrine network controlling growth, reproduction, and osmotic homeostasis. Here, we describe the molecular sequence of leptin and its putative receptor (LepR). Tilapia leptin and LepR share 46-56% sequence identity with Fugu, but only 24-28% identity with human orthologs, suggesting a significant evolutionary divergence in vertebrates. In basal teleosts, two leptins have been described likely arising from genome duplication. Gene synteny and Northern blotting suggests the presence of only a single leptin homolog in Perciformes, the largest order of vertebrates. In tilapia, leptin is expressed in both liver and adipose tissue, but at lower levels in gill, kidney, skin and hypothalamus/brain. LepR expression was detected in all tissues examined, supporting pleiotropic actions for leptin in teleosts. To ascertain potential osmoregulatory functions gill leptin gene expression was measured in tilapia during 24-hr salinity challenge. An 8-fold higher abundance of gill leptin mRNA was found in freshwater (FW) compared with seawater (SW) tilapia (P<0.01). No significant change in gill leptin mRNA was observed after FW or SW transfer, albeit levels increased over the first 3 hr of FW challenge. Elevated production of leptin in the gill of FW tilapia may be associated with paracrine-mediated gill remodulation to a FW phenotype. Keywords: Fishes, Leptin, leptin receptor, osmoregulation, teleosts Conference: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011. Presentation Type: Oral Presentation Topic: Ion and water balance Citation: Baltzegar DA, Brune ES, Johnstone WM and Borski RJ (2011). CHARACTERIZATION OF LEPTIN AND ITS PUTATIVE RECEPTOR (LEPR) IN EURYHALINE TILAPIA: A NOVEL LINK BETWEEN ENERGY STATUS AND OSMOREGULATORY FUNCTION?. Front. Endocrinol. Conference Abstract: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology. doi: 10.3389/conf.fendo.2011.04.00108 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Jul 2011; Published Online: 09 Aug 2011. * Correspondence: Prof. Russell J Borski, North Carolina State University, Department of Biology, Raleigh, NC, 27695, United States, russell_borski@ncsu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers David A Baltzegar Emily S Brune William M Johnstone Russell J Borski Google David A Baltzegar Emily S Brune William M Johnstone Russell J Borski Google Scholar David A Baltzegar Emily S Brune William M Johnstone Russell J Borski PubMed David A Baltzegar Emily S Brune William M Johnstone Russell J Borski Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Molecular Characterization and Expression of α‐Globin and β‐Globin Genes in the Euryhaline Flounder (Platichthys flesus)

In order to understand the possible role of globin genes in fish salinity adaptation, we report the molecular characterization and expression of all four subunits of haemoglobin, and their response to salinity challenge in flounder. The entire open reading frames of α1-globin and α2-globin genes were 432 and 435 bp long, respectively, whereas the β1-globin and β2-globin genes were both 447 bp. Although the head kidney (pronephros) is the predicted major site of haematopoiesis, real-time PCR revealed that expression of α-globin and β-globin in kidney (mesonephros) was 1.5 times higher than in head kidney. Notably, the α1-globin and β1-globin mRNA expression was higher than α2-globin and β2-globin in kidney. Expression levels of all four globin subunits were higher in freshwater- (FW-) than in seawater- (SW-)adapted fish kidney. If globins do play a role in salinity adaptation, this is likely to be more important in combating the hemodilution faced by fish in FW than the dehydration and salt loading which occur in SW.

Blockade of cysteinyl leukotriene-1 receptors suppresses airway remodelling in mice overexpressing GATA-3

We demonstrated previously that GATA-3 overexpression markedly enhanced allergen-induced airway inflammation and airway remodelling, including subepithelial fibrosis, and smooth muscle cell hyperplasia, in transgenic mice. Because cysteinyl leukotrienes (cysLTs) have been shown to be involved in such structural changes, the effects of a specific cysLT1 receptor antagonist, montelukast, were evaluated in a mouse model of chronic asthma. GATA-3-overexpressing mice and wild-type Balb/c mice were sensitized and repeatedly challenged by ovalbumin (OVA) or saline. The effects of montelukast on the development of airway remodelling were compared between the two mouse genotypes. CysLTs in the lung were increased after repeated allergen challenges, and significantly enhanced in GATA-3-overexpressing mice. The enhanced cysLT levels were accompanied by the development of eosinophilia, smooth muscle cell hyperplasia, and increased stromal cell-derived factor-1 gene expression with a small increase in pro-collagen gene expression in OVA-challenged GATA-3-overexpressing mice, but not in wild-type mice. Montelukast significantly decreased lung cysLT levels and inhibited the GATA-3-overexpression-related airway remodelling, potently preventing smooth muscle cell hyperplasia, but partially suppressed the increased pro-collagen gene expression and eosinophilic inflammation. Increases in the levels of IL-4, IL-5, IL-13, and eotaxin in bronchial lavage and TGF-β gene expression in the lungs were induced by OVA in both mouse genotypes. Montelukast treatment also significantly reduced these levels to the levels seen after saline challenges in GATA-3-overexpressing mice. Montelukast efficaciously prevented airway inflammation and remodelling in a GATA-3-overexpression antigen challenge mouse model by decreasing the cysLT-driven Th2 cytokine cycle of amplification of airway pathologies.

Methamphetamine-induced locomotor changes are dependent on age, dose and genotype

Adolescence is a critical age for addiction formation as a large percentage of pathological drug-seeking behaviors manifest during this time. The extent to which the neurotoxic effects of drugs of abuse influence subsequent drug seeking behaviors and impulsivity is an understudied area of research. Methamphetamine (METH) is a widely abused drug that produces locomotor responses ranging from behavioral sensitization to tolerance, both of which are behaviors that may relate to risk of abuse. Here we investigated the effects of age, genotype, METH dose, including a neurotoxic dose, and METH metabolism on open-field activity (OFA) to gain insight into the complex disease of drug abuse. C57Bl/6 (B6), DBA/2 (D2), and 129S6SvEv/Tac (129) mouse strains were administered saline or either a high dose (4×5mg/kg in 2h intervals for 2days) or low dose (2×1mg/kg in 24h intervals) METH pretreatment during adolescence (post natal day (PND) 40) or early adulthood (PND 80) followed by behavioral testing with a METH (1mg/kg) or saline challenge 40days later. Striatal concentrations of METH and AMPH were also determined. Significant findings include: 1) METH pretreated adolescent B6 mice displayed significant sensitization for horizontal locomotion due to high dose METH pretreatment; 2) METH pretreated B6 adults showed significant tolerance for the vertical activity measure caused by low dose METH pretreatment; 3) METH pretreated adult D2 mice exhibited significant sensitization for vertical activity induced by low dose METH pretreatment, and 4) 129 mice metabolized METH significantly faster than the B6 and D2 mice, but METH pretreatment did not alter metabolism. No significant behavioral responses to either METH pretreatment dose were observed for the D2 adolescent studies or either 129 age group. Our results highlight the importance of the interactions of age, strain and METH dose on locomotor behavioral outcomes.

A novel GRAIL E3 ubiquitin ligase promotes environmental salinity tolerance in euryhaline tilapia

BackgroundTilapia (Oreochromis mossambicus) are euryhaline fishes capable of tolerating large salinity changes. In a previous study aimed to identify genes involved in osmotolerance, we isolated an mRNA sequence with similarity to GRAIL (Gene Related to Anergy In Lymphocytes), which is a critical regulator of adaptive immunity and development. Tilapia GRAIL contains a PA (protease associated) domain and a C3H2C3 RING finger domain indicative of E3 ubiquitin ligase activity. Scope of reviewWestern blots analysis was used to assess GRAIL expression pattern and responses to hyperosmotic stress. Immunohistochemistry was used to reveal the cellular localization of GRAIL in gill epithelium. Overexpression in HEK293 T-Rex cells was used to functionally characterize tilapia GRAIL. Salinity stress causes strong up-regulation of both mRNA and protein levels of tilapia GRAIL in gill epithelium. Tissue distribution of GRAIL protein is mainly confined to gill epithelium, which is the primary tissue responsible for osmoregulation of teleost fishes. Overexpression of tilapia GRAIL in HEK293 cells increases cell survival (cell viability) while decreases apoptosis during salinity challenge. Major conclusionsOur data indicate that tilapia GRAIL is a novel E3 ubiquitin ligase involved in osmotic stress signaling, which promotes environmental salinity tolerance by supporting gill cell function during hyperosmotic stress. General significanceInvolvement of tilapia GRAIL in the osmotic stress response suggests that GRAIL E3 ubiquitin ligases play a broader role in environmental stress responses, beyond their documented functions in adaptive immunity and development.