Effect Of Environmental Salinity Research Articles

In silico analysis and effects of environmental salinity in the expression and activity of digestive α-amylase and trypsins from the euryhaline crabNeohelicegranulata

Studies on molecular characteristics and modulation of expression of α-amylase and trypsin in the hepatopancreas of intertidal euryhaline crabs are lacking. In this work, we cloned and studied by in silico approaches the characteristics of cDNA sequences for α-amylase and two trypsins isoforms, as well as the effect of environmental salinity, on gene expression and protein activities in the hepatopancreas of Neohelice granulata (Dana, 1851), which is a good invertebrate model species. The cDNA sequence of α-amylase is 1637 bp long, encoding 459 amino acid residues. Trypsin 1 and 2 are 689 and 1174 bp long, encoding 204 and 151 amino acid residues, respectively. Multiple sequence alignment of deduced protein sequences revealed the presence of conserved motifs found in other invertebrates. In crabs acclimated at 37 psu (hyporegulation), α-amylase mRNA level and total pancreatic amylase activity were higher than at 10 psu (hyperregulation) and 35 psu (osmoconformation). Trypsin 1 mRNA levels increased at 37 psu, while trypsin 2 levels decreased at 10 and 37 psu. Total trypsin activity was similar in all salinities. Our results showed a differential modulation of α-amylase and trypsin expression and total amylase activity by salinity acclimation, suggesting the occurrence of distinct mechanisms of regulation at different levels that could lead to digestive adjustments in relation to hyperregulation and (or) hyporegulation.

The effects of acclimation temperature, salinity, and behavior on the thermal tolerance of Mozambique tilapia (Oreochromis mossambicus).

Mozambique tilapia have been shown to be incredibly stress tolerant with respect to environmental salinity, hypoxia, and ammonia concentrations. Temperature challenges to this species have shown that they have difficulty with cold acclimation. The purpose of this study was to measure the effects of acclimation temperature and salinity on the thermal tolerance of Mozambique tilapia as assessed by critical thermal maxima (CTMax) and critical thermal minima (CTMin). We also monitored fish behavior and quantified ventilation rate. To our knowledge, this study was the first to investigate upper and lower thermal tolerances, and the effect of environmental salinity in this physiologically impressive species. Using predictive regression analyses of the thermal limits, thermal tolerance polygons were constructed and total areas were calculated 678.9°C2 for freshwater (FW)-acclimated tilapia, and 739.4°C2 seawater (SW)-acclimated tilapia. During the thermal challenges, we observed two novel behaviors in response to thermal challenge, ventilation cessation behavior (VCB) and aquatic surface respiration (ASR), and we conclude that the use of these behaviors extended the thermal limits of these fish in both FW and two-thirds SW by limiting the exposure of the gill epithelium to the changing environment.

Effect of environmental salinity on expression of adrenomedullin genes suggests osmoregulatory activity in the medaka, Oryzias latipes.

IntroductionThe adrenomedullins (AMs) comprise a hormonal family in mammals and teleost fishes, with five members (AM1–5) found or predicted in most of the teleosts including Japanese medaka (Oryzias latipes). AM1 is known to have cardiovascular and osmoregulatory functions in mammals, but the roles of most AMs are yet to be determined.ResultsUsing medaka, we first analyzed the tissue distribution of all five AM genes and found detectable expression in all tissues examined, with relatively high levels of AM3 and AM5 in the liver and kidney. To assess the osmoregulatory roles of these AMs, mRNA levels were examined in the brain (including the eyes), gill, liver, kidney and spleen of medaka one week after transfer from isotonic saline (11 ppt) to freshwater (0 ppt) or seawater (33 ppt). Expression of AM1 in the brain-eye increased in freshwater. The central level of AM4 (the paralog of AM1) decreased in seawater; the branchial level of AM4 decreased in freshwater and seawater, but the renal level increased in freshwater. The branchial level of AM2 increased in seawater, whereas the renal level decreased in freshwater and seawater. Expression of AM3, the AM2 paralog, decreased in the brain-eye of seawater-acclimated fish. Expression of AM5 in the brain-eye and kidney decreased in seawater.ConclusionsExcept for branchial AM2, the members of AM family tend to be involved in promotion of hyper-osmoregulation and/or inhibition of hypo-osmoregulation, although each AM may play a distinct role during adaptation to different salinities.

The effect of environmental salinity on the level of heat shock proteins in gill epithelium of Mytilus edilis L. mussel

The composition and the level of heat shock proteins in the gill epithelium cells of mussels Mytilus edulis L. from the White Sea under different levels of environmental salinity were studied by the method of immunoblotting. In mussels maintained under normal salinity (26%), constitutive Hsp70 and protein of about 40 kDa were revealed. After long-term (11–14 days) acclimation to 14 and 35‰ of the level Hsp70 in gill epithelium cells increased. Hsp70 induction was also observed in cells of isolated gills after salinity shock at 14% for 3 and 24 h.

The effect of environmental salinity on H+ efflux in the euryhaline barramundi (Lates calcarifer)

Euryhaline fishes such as the barramundi (Lates calcarifer), have the physiological ability to move between waters of various salinities and are often exposed to rapid changes in ionic gradients that may alter acid–base homeostasis. It has recently been proposed that these species may utilize gill H+ATPase and Na+/H+ exchanger mechanisms to regulate systemic pH, and that the differential expression of the acid/base relevant transporters is governed by environmental salinity. This study examined acid–base regulation in juvenile barramundi adapted to fresh, brackish, or salt water (ranging from 0 to 32ppt) and exposed to 1% environmental hypercapnia. Our findings suggest that barramundi increase net acid excretion in all salinities tested, with a more rapid response observed in fish adapted 22,5 and 32ppt. In contrast, the relative change in net H+ transfers was greatest in the groups adapted to the lower salinities. Fish in 15ppt exhibited an apparent relationship between increased in net H+ excretion and increases in branchial H+ATPase protein expression.

Hematology of great sturgeon (Huso huso Linnaeus, 1758) juvenile exposed to brackish water environment

The effect of environmental salinity on hematological parameters of great sturgeon Huso huso juveniles was studied. Five-month-old juveniles (mean body weight 28.3 +/- 2.1 g) were subjected to 0, 3, 6, 9, and 12 ppt salinities. The hematological parameters were assessed after a period of 20 days rearing at these salinities. After transfer from fresh water to brackish water, red blood cells, hematocrit, haemoglobin and mean corpuscular haemoglobin decreased, but mean corpuscular volume increased. Mean corpuscular haemoglobin concentration, white blood cells, monocyte counts, and eosinophil counts showed no significant variations with increase in environmental salinity. An increase was found in lymphocyte counts according to the increase of salinity from 0 to 12 ppt, while the fresh water control group maintained basal levels. Decrease in neutrophil counts was observed in great sturgeon with increase in environmental salinity. These data show significant effect of salinity on the blood parameters of great sturgeon.

Haematology of great sturgeon (Huso huso Linnaeus, 1758) juvenile exposed to brakish water environment

The effect of environmental salinity on hematological parameters of great sturgeon Huso huso juveniles was studied. Five-month-old juveniles (mean body weight 28.3 ± 2.1 g) were subjected to 0, 3, 6, 9, and 12 ppt salinities. The hematological parameters were assessed after a period of 20 days rearing at these salinities. After transfer from fresh water to brackish water, red blood cells, hematocrit, haemoglobin and mean corpuscular haemoglobin decreased, but mean corpuscular volume increased. Mean corpuscular haemoglobin concentration, white blood cells, monocyte counts, and eosinophil counts showed no significant variations with increase in environmental salinity. An increase was found in lymphocyte counts according to the increase of salinity from 0 to 12 ppt, while the fresh water control group maintained basal levels. Decrease in neutrophil counts was observed in great sturgeon with increase in environmental salinity. These data show significant effect of salinity on the blood parameters of great sturgeon.

Expression of pituitary prolactin, growth hormone and somatolactin is modified in response to different stressors (salinity, crowding and food-deprivation) in gilthead sea bream Sparus auratus

Prolactin (PRL), growth hormone (GH) and somatolactin (SL) expression was studied in gilthead sea bream ( Sparus auratus) in response to several different stressors (salinity, food deprivation or stocking density). In the first experiment, specimens were acclimated during 100 days at three different environmental salinities: low salinity water (LSW, 6 ppt), brackish water (BW, 12 ppt) and seawater (SW, 38 ppt). Osmoregulatory parameters corresponded to those previously reported for this species under similar osmotic conditions. Pituitary PRL expression increased with decreasing environmental salinity, and was significantly different between SW- and LSW-acclimated fish. Pituitary GH expression was similar between SW- and BW-acclimated fish but decreased in LSW-acclimated specimens. Pituitary SL expression had a “U-shaped” relationship to environmental salinity with the lowest expression in BW-acclimated fish. In a second experiment SW-acclimated specimens were randomly assigned to one of four treatments and maintained for 14 days: (1) fed fish under low density (LD, 4 kg m −3); (2) fed fish under high density (HD, 70 kg m −3); (3) food deprived fish under LD; and (4) food deprived fish under HD. Plasma glucose and cortisol levels corresponded to those previously reported in S. auratus under similar experimental conditions. Pituitary PRL and SL expression increased in fish maintained under HD and decreased in food deprived fish. In conclusion, an effect of environmental salinity on pituitary PRL and GH expression has been demonstrated. In addition, crowding stress seems to interact with food deprivation in S. auratus and this is reflected by changes in pituitary PRL, GH and SL expression levels.

The effect of environmental salinity on the proteome of the sea bass (Dicentrarchus labrax L.)

The European sea bass, Dicentrarchus labrax L., tolerates a range of salinities from freshwater to hyper-saline. To study differences in protein expression, fish were reared in both freshwater and seawater. After 3-month acclimation, gill and intestine epithelia were collected and the soluble protein extracted. In all, 362 spots were differentially expressed in the gills and intestines of fishes reared in seawater compared to those from freshwater. Fifty differential protein spots were excised from a colloidal Coomassie-stained gel. Nine separate protein spots were identified unambiguously by mass spectrometry and database searching. Among the six proteins over-expressed in gill cells in seawater, five were cytoskeleton proteins and one was the aromatase cytochrome P450. In gill cells under freshwater conditions, the two over-expressed proteins identified were the prolactin receptor and the major histocompatibility complex class II beta-antigen. In intestinal cells under freshwater conditions, the Iroquois homeobox protein Ziro5 was upregulated over ninefold. The expression of these proteins, their possible direct or indirect roles in the adaptation of D. labrax to salinity, and their correspondences with a previous study are discussed.

The effect of environmental salinity on the protein expression of Na+/K+-ATPase, Na+/K+/2Cl− cotransporter, cystic fibrosis transmembrane conductance regulator, anion exchanger 1, and chloride channel 3 in gills of a euryhaline teleost, Tetraodon nigroviridis

Chloride transport mechanisms in the gills of the estuarine spotted green pufferfish (Tetraodon nigroviridis) were investigated. Protein abundance of Na(+)/K(+)-ATPase (NKA) and the other four chloride transporters, i.e., Na(+)/K(+)/2Cl(-) cotransporter (NKCC), cystic fibrosis transmembrane conductance regulator (CFTR), Cl(-)/HCO(3)(-) anion exchanger 1 (AE1), and chloride channel 3 (CLC-3) in gills of the seawater- (SW; 35 per thousand) or freshwater (FW)-acclimatized fish were examined by immunoblot analysis. Appropriate negative controls were used to confirm the specificity of the antibodies to the target proteins. The relative protein abundance of NKA was higher (i.e., 2-fold) in gills of the SW group compared to the FW group. NKCC and CFTR were expressed in gills of the SW group but not in the FW group. In contrast, the levels of relative protein abundance of branchial AE1 and CLC-3 in the FW group were 23-fold and 2.7-fold higher, respectively, compared to those of the SW group. This study is first of its kind to provide direct in vivo evidence of the protein expression of CLC-3 in teleostean gills, as well as to examine the simultaneous protein expression of the Cl(-) transporters, especially AE1 and CLC-3 of FW- and SW-acclimatized teleosts. The differential protein expression of NKA, chloride transporters in gills of the FW- and SW-acclimatized T. nigroviridis observed in the present study shows their close relationship to the physiological homeostasis (stable blood osmolality), as well as explains the impressive ionoregulatory ability of this euryhaline species in response to salinity challenges.

Effect of environmental salinity on sea lice Lepeophtheirus salmonis settlement success

The sea louse Lepeophtheirus salmonis (Krøyer, 1837) (Copepoda: Caligidae) is an ectoparasite of salmonid fish. It has earlier been proposed that the free-swimming infectious copepodid stage of L. salmonis gather at river mouths to infect wild Atlantic salmon Salmo salar L. and sea trout S. trutta L. smolts during their seaward migration. This study used aquarium-based methods to investigate the survival, infective ability and behaviour of L. salmonis copepodids exposed to short periods of low salinity levels, such as those encountered at river mouths. Survival of free-swimming copepodids was found to be severely compromised at salinity levels below 29 parts per thousand (ppt). Attachment to an S. salar host did not aid copepodid survival during post-infection exposure to low salinity environment, and a reduction in salinity appears to reduce the ability of copepodids to remain attached to S. salar smolts. Pre-infection exposure of copepodids to reduced salinity levels reduced infection of S. salar. Infection levels at reduced salinity were lower than predicted from the free-swimming survival experiment, suggesting that low salinity compromises the copepodids' ability to sense or respond to the presence of a host. In salinity gradients, copepodids demonstrated avoidance of salinities below 27 ppt, by both altering their swimming behaviour and changing the orientation of passive sinking. Avoidance of low salinity levels may be due to their adverse effects on copepodid physiology, as suggested by the reduction in survival. Sinking rates were also faster in reduced salinity, suggesting that remaining in the water column would be more energetically demanding for the copepodids at reduced salinity. These results show that both survival and host infectivity of L. salmonis are severely compromised by short-term exposure to reduced salinity levels.

Osmotic adjustment in marine yeast

The effect of environmental salinity on cell growth, and on the composition and accumulation of compatible solutes, or osmotica, of five yeast strains (Aureobasidium pullulans, Candida sp., Cryptococcus albidus var. albidus, Debaryomyces hansenii and Rhodotorula rubra) was compared. All these yeast were isolated from manne environments, but were able to grow in the absence of salt and should therefore be considered as halotolerant strains. According to their specific cell growth rates at different salt concentrations, these strains vary in their capacity to osmotically adjust to modifications in external salinity. Candida sp. appears to be the most sensitive since the maximum salt concentration at which it can grow is 1.54 mol 1-1 NaCl; however, it showed the highest specific cell growth in the range of 0 to 1.54 mol 1-1 NaCl. Aureobasidium pullulans, on the other hand, showed the lowest specific growth rate, but the highest halotolerance range from 0 to 5.13 mol 1-1 NaCl. Debaryomyces hansenii, in contrast, showed higher specific growth at this salinity range Cryptococcus albidus var. albidus and Rhodotorula rubra showed similar specific cell growth rate values and halotolerance between 0 and 2.45 mol 1-1 NaCl. The protein and carbohydrate content of the biomass of the different yeast cells, as a result of external salinity vanation, remained practically constant. The most important effects of the increase in salt concentration in the culture medium were the reduction of cell volume and the accumulation of low-molecular-weight metabolites (LMWM). which appear to act as osmoregulators. Glycerol was found as the major compatible solute in the different marine yeasts studied herein with a total contribution of 64–96% of the internal cell osmolarity. Other LMWM, like carbohydrates and amino acids, contributed to a lesser extent to compensate for the rise in osmotic pressure promoted by the salinity of the external environment.

Effect of Environmental Salinity on Sensory Characteristics of Penaeid Shrimp

ABSTRACTWhite shrimp, Penaeus vannamei, acclimated to 10, 30 and 50 parts per thousand (ppt) salinities were evaluated for flavor by a trained sensory panel. The shrimp were also analyzed for tissue moisture, chloride, free amino acid concentration and free amino acid profile. Results of triangle tests showed a significant flavor difference between shrimp held at 10 and 50 ppt and 30 and 50 ppt but not between 10 and 30 ppt. On a wet weight basis, the free amino acid concentration was 81% higher in shrimp held at 50 ppt than at 10 ppt and 63% higher in shrimp held at 50 as compared to 30 ppt. However, between shrimp held at 30 as compared to 10 ppt the difference was only 11%. The difference in flavor intensity of shrimp held at different salinities appeared to be a direct reflection of the concentration of tissue free amino acids which serve as osmoregulators in shrimp tissue.

Environmental salinity and the thyroidal response to thyrotropin in juvenile coho salmon (Oncorhynchus kisutch).

The effect of environmental salinity on the thyroidal response, measured by plasma concentrations of thyroxine (T4), to exogenous bovine thyrotropin (bTSH) was assessed early and late in the smoltification of coho salmon (Oncorhynchus kisutch). A single injection of 100 mIU bTSH significantly increased plasma T4 concentrations in fish in both fresh water and seawater, and both early (March 19) and late (May 24) in smoltification. In fish transferred to seawater, the increase in T4 titers was somewhat earlier and its duration shorter, suggesting an environmentally induced change in the kinetics of T4 entry and exit from the blood stream. The overall response to TSH was greater near the beginning (March 19) of the smoltification-associated T4 increase than near the end (May 24), suggesting a development-related change in thyroid function.

Effect of Environmental Salinity on the Free Amino Acid Composition and Concentration in Penaeid Shrimp

ABSTRACTWhite shrimp, Penaeus vannamei, kept in laboratory aquaria at a salinity of 35 parts per thousand (ppt) were subjected to increased and decreased salinity changes by either 5, 15 or 25 ppt. Shrimp were periodically removed from the aquaria and analyzed for total free amino acid nitrogen and also specific free amino acid composition. Decreasing salinities resulted in corresponding decreases in free amino acid concentration; minimum values were reached after 24 ‐ 48 hr. Increasing salinities were likewise shown to result in corresponding increases in the tissue free amino acid concentration with maximum values being reachedin 24 hr. Glycine, proline, arginine, serine/threonine, and alanine were the most significant contributors, comprising from 93 ‐ 96% of the total free amino acid pool.

Effect of environmental salinity on the L-response of the S-potential as an index of spectral sensitivity

1. 1. The influence or effect of salinity as an environmental factor contributing to the differences in the spectral sensitivities of marine and freshwater fishes was studied using the L-response of the S-potential as a criterion. 2. 2. The present data show that both the Ayu-fish (sea-run form) and the Japanese eel collected from freshwater gave the L-response, that of characteristic of marine fishes. 3. 3. No wavelength shift of the spectral sensitivity from the marine- to freshwater-type or vice versa, was produced by changing the salinity of the environment.