Functional state of the liver antioxidant system of the bream <Emphasis Type="Italic">Abramis brama</Emphasis> (L.) from Rybinsk Reservoir regions with different anthropogenic loads

The breams living in five regions of the Rybinsk Reservoir with different degrees of anthropogenic load have been assayed for the characteristics of their antioxidant system (AOS) and lipid peroxidation (LPO) system. Individuals caught at two stations in the Rybinsk Reservoir that maximally differ in the degree of pollution display different qualitative and quantitative compositions of polychlorinated biphenyls (PCBs). At the station at the Sheksninskii Reach, which is located near a local source of pollution (Cherepovets), the total content of PCBs and homologous groups of congeners is one order of magnitude higher than in the bream living at the station of the comparatively clean Molozhskii Reach. The AOS response and the generation intensity of LPO products in the bream (Abramis brama L.) liver caused by different degrees of anthropogenic pollution have been determined. The content of LPO products in the liver of the breams caught in the Sheksninskii Reach is considerably higher and the values of AOS characteristics are considerably lower than in the fish from the Molozhskii Reach. The bream living in the Molozhskii and Volzhskii Reaches are in a more favorable state than those in the Sheksninskii Reach. The AOS and LPO characteristics are an appropriate biomarker for estimating the state of the health of the fish.     

Exploration of the utility of fluctuating asymmetry as an indicator of river condition using larvae of the caddisfly Hydropsyche morosa (Trichoptera: Hydropsychidae)

Organisms are subject to three types of morphological asymmetry: Directional Asymmetry, Antiasymmetry and Fluctuating Asymmetry, but only the latter (FA) is related to the environmental stress acting upon individuals during their development. Larvae of Hydropsyche morosa from five rivers in Ontario, Canada, each exhibiting different degrees of human impact, were examined for FA. Specimens were obtained from collections in the Royal Ontario Museum dating back to 1951, and from fresh collections to 1999. Twelve morphological characters were assessed on both the left and right sides of 297 larvae, and eight of them demonstrated FA. There was a tendency to increase the levels of FA over time. Levels of nitrogen, conductivity and chloride in the river water, used as an index of pollution, were significantly and positively correlated with increasing incidence of FA in four of the characters, the remainder were independent of pollution.     

Effects of carbaryl exposure on the last larval instar of Xanthocnemis zealandica – fluctuating asymmetry and adult emergence

Fluctuating asymmetry (FA), a measure of developmental stability, has been suggested as a monitoring tool for environmental pollution. Aquatic pollution events are often transitional and the level of FA in populations exposed to such incidents has not yet been investigated. Research into the morphological effects of transitional pollution also provides a tool to elucidate the timing and duration of any `window of opportunity' for the determination of FA in the developing organism. The present study was undertaken to investigate if exposure of the last instar of the damselfly Xanthocnemis zealandica (McLachlan) (Zygoptera: Coenagrionidae) to different levels of insecticidal stress resulted in different levels of FA in the wings of the adult insects and if adult emergence was altered by different concentrations of pesticide. Three concentrations of carbaryl (40 ppb, 2 ppb and 0.1 ppb) and a control were used. The emergence success of the damselflies was not affected by any treatment, but the insecticide had a stimulatory effect on the developing larvae. Exposure of the last instar of X. zealandica to carbaryl at 40 ppb had no consistent effect on FA in metric traits and increased FA in meristic traits compared with the control. Segregation of the emerged adults into two groups revealed more details about the `window of opportunity' in the meristic traits. Larvae which had already completed more than half of their development when the experiment started did not show significant differences in the level of FA. In contrast, damselflies which were exposed for more than half of the final instar showed a clear difference in their levels of FA. The greater difference in the latter group was mainly caused by a decrease of FA in the controls rather than by an increase in the treatment. These data suggest that the `window of opportunity' for the determination of the level of FA of the meristic traits in damselfly wings closes approximately halfway through the final larval instar.     

Effect of stress experienced during pregnancy on the rate of lipid peroxidation in erythrocytes and brain tissue of newborn rat pups

The rate of lipid peroxidation (LPO) in erythrocytes and brain homogenate has been assessed by the accumulation of malondialdehyde, the degree of erythrocyte autohemolysis, the content of hydrogen peroxide and catalase activity observed in newborn rats aged 1 hour, 1, 15, 20 and 30 days. Pregnant rats were exposed to emotional stress (aggressive interaction of two pregnant rats in an unavoidable conflict situation provoked by nociceptive irritation. Significant age-dependent differences in the rate of LPO (both in erythrocytes and cerebral tissue) have been found. The highest rate was noted in rats 15 days of age. The emotional stress of pregnant females resulted in the changes of behavioural reactions of newborn rats and LPO activity that was characterized by the increase in LPO rate in 1-hour- and 1-day-old rats and by slowing of LPO rate in 15-day-old rats. These phenomena were observed in erythrocytes and brain tissues of test animals.     

Alpha-adrenergic receptors in the hepatic sinusoid of the rat and its relation to portal pressure

The presence of alpha-adrenergic receptors in the hepatic sinusoid of the rat, and its relation to portal pressure (PP), by local and systemic infusion of bolus doses of norepinephrine (NE) (1 microgram/100 g) and phentolamine (FA) (25 micrograms/100 g) have been studied. Fifty-five male Wistar rats with intact nerves have been used in 5 experiments. When NE is injected into the portal vein (PV), it provokes an immediate rise in PP, modified subsequently by the systemic effect is induced earlier and more intensely than if injected into PV. If FA is infused into PV, PP decreases and the effect of posterior infusion of NE is less marked. These results suggest the presence of alpha-adrenergic receptors in the hepatic sinusoid of the rat. When they are stimulated PP raises, indicating that basal PP is maintained not only because of hepatic arterial flow, but also through a distinct sympathetic tone.     

黄腐酸和甜菜碱预处理对干旱胁迫下平邑甜茶生理特性及光合的影响

该研究以平邑甜茶[Malus hupehensis(Pamp.)Rehd.]2年生实生苗为材料,通过盆栽试验于干旱处理前3d分别连续喷施黄腐酸(FA)、甜菜碱(GB)和复配(FA+GB),并以清水为对照(CK)进行预处理,比较分析不同预处理对干旱胁迫下平邑甜茶的生理及光合特性变化,探讨FA和GB对平邑甜茶的抗旱生理机制。结果显示:(1)与对照相比,FA、GB和FA+GB预处理均能够显著提高平邑甜茶叶片相对含水量,且FA的保水性效果最佳。(2)3种预处理均可显著促进干旱胁迫下叶片可溶性蛋白、可溶性糖和脯氨酸含量增加,且FA+GB预处理后在干旱胁迫下叶片可溶性糖和脯氨酸累积量显著高于单施FA或GB。(3)3种预处理均可显著提高干旱胁迫下平邑甜茶幼苗的SOD、POD、CAT活性,并显著降低MDA的积累速度及其累积量,且以FA+GB预处理的MDA含量最低、抗氧化酶活性最高。(4)GB和FA+GB预处理下平邑甜茶的净光合速率、瞬时水分利用率显著高于CK和FA,且FA+GB处理下改善光合特性的效果最佳,GB次之。研究表明,单独喷施黄腐酸和甜菜碱及两者配施预处理均能够增加干旱胁迫下平邑甜茶的渗透调节物质和相对含水量,提高叶片的保水性,调节抗氧化物酶活性,降低丙二醛含量,增加细胞膜稳定性,改善光合性能,进而提高平邑甜茶的抗旱能力,且以复配喷施(FA+GB)预处理的效果最好。     

Hydrostatic pressure affects membrane and storage lipid compositions of the piezotolerant hydrocarbon‐degrading Marinobacter hydrocarbonoclasticus strain #5

A new piezotolerant alkane‐degrading bacterium (Marinobacter hydrocarbonoclasticus strain #5) was isolated from deep (3475 m) Mediterranean seawater and grown at atmospheric pressure (0.1 MPa) and at 35 MPa with hexadecane as sole source of carbon and energy. Modification of the hydrostatic pressure influenced neither the growth rate nor the amount of degraded hexadecane (≈ 90%) during 13 days of incubation. However, the lipid composition of the cells sharply differed under both pressure conditions. At 0.1 MPa, M. hydrocarbonoclasticus #5 biosynthesized large amounts (≈ 62% of the total cellular lipids) of hexadecane‐derived wax esters (WEs), which accumulated in the cells under the form of individual lipid bodies. Intracellular WEs were also synthesized at 35 MPa, but their proportion was half that at 0.1 MPa. This lower WE content at high pressure was balanced by an increase in the total cellular phospholipid content. The chemical composition of WEs formed under both pressure conditions also strongly differed. Saturated WEs were preferentially formed at 0.1 MPa whereas diunsaturated WEs dominated at 35 MPa. This increase of the unsaturation ratio of WEs resembled the one classically observed for bacterial membrane lipid homeostasis. Remarkably, the unsaturation ratio of membrane fatty acids of M. hydrocarbonoclasticus grown at 35 MPa was only slightly higher than at 0.1 MPa. Overall, the results suggest that intracellular WEs and phospholipids play complementary roles in the physiological adaptation of strain #5 to different hydrostatic pressures.     

Desaturation of fatty acids as an adaptive response to shifts in light intensity 1

The comparative study of various unicellular algae, characterised by different carbon chain lengths and different numbers of double bonds per fatty acid (FA) chain, exhibited some similarity in the mechanisms of their response to changes in light conditions, in terms of FA metabolism. In all cases, the optimisation of photosynthetic process resulted in some increase in the relative content of the most unsaturated FA, i.e. C16:3Ω3 and C18:3Ω3 acids in Chlorella cells, C16:4Ω3 and C18:3Ω3 in Dunaliella and Chlamydomonas, C20:5Ω3 in Porphyridium, and C18:2Ω6 in Synechocystis sp. As a rule, these FA were esterified to monogalactosyldiacylglycerols (MGDG), the predominant lipids of thylakoid membranes. Such an increase in the relative content of the polyunsaturated FA usually occurred during the period when the photosynthesis, as well as the biosynthesis of FA de novo, were transiently inhibited following shifts in environmental conditions even at their optimisation. The increase in the relative content of the most unsaturated FA could be performed via desaturation of their immediate precursors. In turn, the deterioration of life conditions (decrease in the light intensity, ageing of cells or cultures, and others) resulted in the accumulation of these precursors. As a result, the cell could change its FA composition without alteration of the whole multistage process but only at the rate of this end reaction of polyunsaturated FA biosynthesis. In the majority of algae, these polyunsaturated acids were Ω3-homologues, regardless of the difference in their structures, but in some cyanobacteria (e.g. Synechocystis) the relative content of Ω6-FA increased. The acceleration of Ω3-FA biosynthesis could be observed, regardless of changes in the total index of unsaturation. This FA desaturation was shown to correlate with the activity of photosystem I (PSI). The specificity of this reaction enables us to assume it to be an adaptive response which provides alterations to lipid-protein interactions in the membrane that may be important for the self-assembly of active chlorophyll-protein complexes for photosynthetic akpparatus.     

Folic Acid Treatment Normalizes NOS‐Dependence of Vascular Tone in the Metabolic Syndrome

Obese subjects with the metabolic syndrome (MS+) are more prone to microvascular complications than obese subjects without the metabolic syndrome (MS?). Excessive vascular nitric oxide (NO) production has been demonstrated in MS+ compared to MS?, perhaps driven by increased inflammation or oxidative stress. We tested whether in MS+, folic acid (FA) treatment could normalize NO synthase (NOS)‐dependence of vascular tone in the retina and kidney. MS+ (n = 49) and MS? (n = 26) subjects were included in a randomized, double‐blind, crossover trial. After 4‐weeks' treatment with placebo or FA (5 mg/day), several cytokines (C‐reactive protein (CRP), interleukin‐1β, adiponectin), and markers of oxidative stress (glutathione/oxidized glutathione (GSH/GSSG) ratio, total antioxidant capacity (TAC)) were determined. NOS‐dependence of retinal and renal vascular tone was assessed by retinal scanning laser Doppler flowmetry and renal clearance technique, respectively. FA had no effect on cytokine levels, but increased GSH/GSSG ratio overall (36 ± 76 vs. 102 ± 200, P = 0.04), indicative of a reduction in oxidative stress. In MS+, treatment with FA reduced NOS‐dependence of retinal and renal vascular tone compared to placebo (P = 0.03 and P = 0.04, respectively). FA had no effect in MS?. After treatment with FA, NOS‐dependence of retinal and renal vascular tone was similar between MS+ and MS?. Retinal and renal vascular tone in MS+ subjects is characterized by increased dependence on NOS. NOS‐dependence in MS+ could be corrected by FA treatment to levels not dissimilar in MS?, and this was associated with a reduction in oxidative stress. Future trials should test whether these effects translate into a reduction of microvascular complications.     

Modulation of balance between apoptosis and proliferation by lipid peroxidation (LPO) during rat liver regeneration

BACKGROUND: This work aims to investigate the role of lipid peroxidation (LPO) at early stages of liver regeneration and to evaluate the balance between apoptosis and cell proliferation during this process. METHODS: Sham and partial hepatectomized (PH) male Wistar rats were randomized in seven groups: Control (untreated), E-Control (injected with vitamin E-vehicle), C-Control (injected with vitamin C-vehicle), E1 (vitamin E 100 mg/kg body weight), E2 (vitamin E 600 mg/kg body weight), C1 (vitamin C 30 mg/kg body weight), C2 (vitamin C 100 mg/kg body weight). RESULTS: Vitamin treatments attenuated the increase of LPO level observed in total homogenate and microsomes at 3 and 5 hr after PH. Both antioxidant vitamins attenuated the increase in Bax pro-apoptotic protein and augmented Bcl-xL antiapoptotic protein levels (35%) at 3 and 5 hr post-PH; Bcl-xL/Bax ratio was, therefore, increased. A direct linear relationship between LPO levels and Bax mitochondrial protein levels was seen. Vitamin-treatments diminished the apoptosis index with respect to PH-Control values, so that this parameter showed a linear relationship with LPO levels. At 24 hr after PH, the vitamin treatments increased the peak of [(3) H]-thymidine incorporation into DNA and the proliferative index (PI), measured as PCNA expression; an inverse relationship between PI and LPO levels could be demonstrated. CONCLUSION: Our data show that the diminution of LPO levels by vitamin-treatment post-PH produces both an attenuation of cellular apoptosis and a marked increase in the proliferation process, suggesting that the modulation of LPO has a role in liver regeneration process.     

Lipid peroxidation in microsomes of murine bone marrow after low-doseγ-irradiation

The principal aim of the study was to investigate the effect of low-dose-irradiation on lipid peroxidation (LPO) in murine bone marrow. To this end, the degree of LPO in suspensions of microsomes of murine bone marrow cells (BMC) was determined in terms of malondialdehyde (MDA) formation after whole-body or in vitro exposure to various doses of-radiation. These effects were compared to some extent with similar effects in liver and spleen preparations. As to the effect of-irradiation on LPO in BMC, the response depends on the dose level and on whether whole-body or in vitro exposures are involved. Whole-body irradiation did not result in an increase in LPO in BMC microsomes, even at such high doses as 15 Gy, although hepatic microsomes showed a marked increase. In contrast, in vitro irradiation of BMC microsomes with 0.1, 10 and 50 Gy brought about an increase in LPO. This increase was already significant (P <0.05) at 0.1 Gy following a post-irradiation incubation and substantial at 50 Gy, even without subsequent incubation. The results show that low doses of-irradiation are able to induce an elevation of LPO in murine BMC microsomes, but only after in vitro irradiation. In the case of whole-body irradiation cellular radical scavengers and other metabolic reactions may prevent a measurable increase in LPO. This is partly illustrated by the case of vitamin-E deficiency, where a substantial increase in LPO in BMC microsomes is observed even without-irradiation in comparison with euvitaminotic mice because normally occurring radicals are not scavenged sufficiently.On leave from the University of Rochester, School of Medicine and Dentistry, Rochester, NY 14678, USA     

Evaluation of blood antioxidant defense and apoptosis in peripheral lymphocytes on exogenous administration of pineal proteins and melatonin in rats

In view of the significant health impact of oxidative stress and apoptosis dysfunction, and further, because of suggestions that administration of antioxidants might reduce apoptosis rate through up-regulation of body antioxidant defense systems, therefore the purpose of this study was to compare the effect of buffalo (Bubalus bubalis) pineal proteins (PP at 100 μg/kg BW, i.p.) with melatonin (MEL at 10 mg/kg BW, i.p.) on blood (erythrocytes) antioxidant defense system and apoptosis in isolated peripheral blood lymphocytes of female Wistar albino rats. The cell viability index (%) and apoptosis index (%), which are directly related to the apoptosis rate of the cells, were used as dependent measures for inferring PP and MEL activity. The total cell viability index did not differ between rats treated with MEL and PP from control animals. The percentage of apoptotic cell death through fluorescence microscopy also did not change in MEL and PP groups as compared with control. DNA fragmentation as an index of apoptosis was detected with propidium iodide staining and assessed by flow cytometry. Pineal proteins and MEL administration caused significant (p < 0.05) reduction in lipid peroxidation and increased level of catalase, superoxide dismutase, glutathione peroxidase, and glutathione in erythrocytes as compared with control. Interestingly, we did not observe increase in the non-viable cells and percentage of apoptotic cell death in PP-treated group, controls or in animals in which MEL had been administered. Therefore, the present study confirmed the up-regulation of erythrocytes (blood) antioxidant defense systems and absence of adverse effect on rate of apoptosis in PP and MEL-administered rats under absence of stress or toxicant exposure. Hence, these test agents can be tested for further therapeutic values against adverse apoptosis rate under stress or toxicants exposures.     

Serum phospholipid fatty acids, adipose tissue, and metabolic markers in obese adolescents

Objective: Fatty acid (FA) composition has a role in adipogenesis. The objective was to study serum phospholipid (PL) FAs in adolescents and their relation to abdominal adipose tissue (AT) compartments and metabolic markers. Research Methods and Procedures: Abdominal AT was measured by magnetic resonance imaging and FA pattern was determined in serum PL of 10 obese adolescents (5 females), median age 12.0 years (range, 10.4 to 16.4) and BMI 30.7 (26.8 to 40.4), and 15 lean control subjects (9 females), median age 12.6 years (range, 11.3 to 15.4), and BMI 19.5 (17.1 to 23.4). Results: Obese adolescents had relatively higher levels of saturated FA (SFA) and nervonic acid compared with controls. Serum PL concentration of n‐3 polyunsaturated fatty acids (PUFA) was lower in the obese vs. lean females (p = 0.01), including docosahexaenoic acid (DHA) (p = 0.01). The ratios of arachidonic acid to DHA and total n‐6/n‐3 FA were increased in obese children (p = 0.02 and 0.01, respectively). n‐3 PUFAs were inversely correlated to all subcutaneous AT compartments except visceral AT. The homeostasis model assessment index of β‐cell function related inversely to DHA concentration (p = 0.03). All changes were more marked in the females. Discussion: Serum FA pattern in obese adolescents differed significantly from that in age‐matched lean controls, reflecting a decrease in n‐3 PUFA, especially DHA, and an increase in SFA. The subcutaneous AT, but not visceral AT, correlated to the changes in PUFA and SFA, suggesting an abnormal essential FA metabolism in obese adolescents.     

The effect of dietary ethanol on the composition of lipids of Drosophila melanogaster larvae

At a moderate concentration (2.5%, v/v) dietary ethanol reduced the chain length of total fatty acids (FA) and increased the desaturation of short-chain FA in Drosophila melanogaster larvae with a functional alcohol dehydrogenase (ADH). The changes in length in total FA were postulated to be due to the modulation of the termination specificity of fatty acid synthetase. Because the ethanol-stimulated reduction in the length of unsaturated FA was blocked by linoleic acid, it was thought to reflect the properties of FA 9-desaturase. Although the ethanol-stimulated reduction in chain length of unsaturated FA was also observed in ADH-null larvae, ethanol promoted an increase in the length of total FA of the mutant larvae. Thus, the ethanolstimulated change in FA length was ADH dependent but the ethanol effect on FA desaturation was not. Ethanol also stimulated a decrease in the relative amount of phosphatidylcholine and an increase in phosphatidylethanolamine. Because similar ethanol-induced changes have been found in membrane lipids of other animals, ethanol may alter the properties of membranes in larvae. It is proposed that ethanol tolerance in D. melanogaster may be dependent on genes that specify lipids that are resistant to the detrimental effects of ethanol.This research was supported by National Institutes of Health Grant GM-28779 to B.W.G. and a Monash University Research Grant to S.W.M.     

FLUCTUATING ASYMMETRY: AN EPIGENETIC MEASURE OF STRESS

(1) Fluctuating asymmetry (FA) is a useful trait for monitoring stress in the laboratory and in natural environments.
(2) Both genomic and environmental changes can increase FA which represents a deterioration in developmental homeostasis apparent in adult morphology. Genetic perturbations include intense directional selection and certain specific genes. Environmental perturbations include temperature extremes in particular, protein deprivation, audiogenic stress, and exposure to pollutants.
(3) There is a negative association between FA and heterozygosity in a range of taxa especially fish, a result consistent with FA being a measure of fitness.
(4) Scattered reports on non-experimental populations are consistent with experiments under controlled laboratory conditions. FA tends to increase as habitats become ecologically marginal; this includes exposure to environmental toxicants.
(5) In our own species, FA of an increasing range of traits has been related to both environmental and genomic stress.
(6) Domestication increases FA of the strength of homologous long bones of vertebrate species due to a relaxation of natural selection.
(7) FA levels are paralleled by the incidence of skeletal abnormalities in stressful environments.
(8) Increased FA is a reflection of poorer developmental homeostasis at the molecular, chromosomal and epigenetic levels.     

Potential use of seaweeds in the laying hen ration to improve the quality of n-3 fatty acid enriched eggs

An association between dietary fish oil and decreased yolk weight and reduced sensory quality of eggs has been reported when eggs are enriched with n-3 FA from fish oil. Seaweeds are an important source of compounds that seem to increase egg weight when included in the laying hen diet. The objectives of this study were to determine the influence of the dietary seaweeds Macrocystis pyrifera, Sargassum sinicola and Enteromorpha sp. on the physical quality, lipid composition and consumer acceptability of n-3 FA enriched eggs. One-hundred and forty-four 35-week-old Leghorn hens were randomly distributed in four treatments that consisted of the inclusion of 2% of sardine oil (SO) and 10% of each marine alga (MA) in laying hens' diets; a control diet (C) was also prepared. The study lasted 8 weeks and egg physical quality, egg lipids and sensory attributes were evaluated. The results showed that incorporation of 10% M. pyrifera in the diets is an effective way of increasing the n-3 FA content, the albumen height and yolk color, but not the egg weight, when these are enriched with n-3 FA from fish oil. The egg flavor was also not affected.     

The seasonal variability of Drosophila population according to the individual asymmetry

The natural Drosophila population is characterized by the presence of directional (DA) and fluctuating (FA) asymmetry of individuals. It was found that genotype has an effect on DA-level. FA evaluated in spring, summer and autumn periods had its maximum value in summer period. Genetically determined seasonal decrease in size of individuals was accompanied with increase in their FA. The structure of FA population variability is defined by genotypes of individuals. The phenotype and genotype structures of Drosophila population were investigated by FA of the individuals. There was regrouping of lineages number within of each frequency class in period from spring to autumn. Investigating central frequency class with least FA values in spring to summer period we observed the decrease in number of lineages for all traits with the exception of sternoupleral bristles (SB). At the same time the increase in number of lineages in the central and extreme frequency class with maximal FA values of sternoupleral bristles (SB). At the same time the increase in number of lineages in the central and extreme frequency class with maximal FA values of lines is observed. The number of lineages in the central frequency class of genotype structure is prevailing to all traits, without dependence on season. Individuals with rather high FA value acquire advantages in summer period whereas the individuals with low FA--in spring and autumn periods. Annual dynamics of FA is defined by this population parameters reorganization. The reasons of seasonal change of FA are discussed.     

The effect of industrial biocides on sulphate-reducing bacteria under high pressure

This study was undertaken to determine the influence of temperature (20, 37, and 50°C) and pressure (1, 100 and 200 atm) on a strain of sulphate-reducing bacteria (SRB), isolated from an oil reservoir in Alaska. The effect of different concentrations (100, 200 and 500 ppm) of biocides isothiazolone (ITZ) and formaldehyde (FA) on planktonic population of SRB was tested in order to determine the efficacy of biocides under these conditions.The highest bacterial growth rate was 0.26±0.03 h⁻¹ at 37°C under pressure of 100 atm. Statistical evaluation showed that although both temperature and pressure had exerted an effect on bacteria by significantly increasing their growth rate; temperature rather than pressure had greater influence on bacterial proliferation.The effectiveness of both FA and ITZ in controlling planktonic populations of SRB was comparable except at 37°C/200 atm, under which conditions FA proved to be more potent. The effectiveness of both biocides decreased with an increase in cell number, as observed at 37°C/100 atm.     

Effects of seawater acidification and salinity alterations on metabolic,osmoregulation and oxidative stress markers in Mytilus galloprovincialis

The impacts of seawater acidification and salinity shifts on metabolism, energy reserves, and oxidative status of mussels have been largely neglected. With the aim to increase the current knowledge for the mussel Mytilus galloprovincialis a 28-day chronic test was conducted during which mussels were exposed to two pH (7.8 and 7.3; both at control salinity 28) and three salinity (14, 28 and 35, at control pH, 7.8) levels. After exposure to different conditions, mussels electron transport system activity, energy reserves (protein and glycogen content) carbonic anhydrase activity, antioxidant defences and cellular damage were measured. Results obtained showed that mussels exposed to seawater acidification presented decreased metabolic capacity that may have induced lower energy expenditure (observed in higher glycogen, protein and lipids content at this condition). Low pH condition induced the increase of carbonic anhydrase activity that was related to acid-base balance, while no significant activation of antioxidant defence mechanisms was observed resulting in higher LPO. Regarding the impacts of salinity, the present study showed that at the highest salinity (35) mussels presented lower metabolic activity (also related to lower energetic expenditure) and an opposite response was observed at salinity 14. Carbonic anhydrase slightly increased at stressful salinity conditions, a mechanism of homeostasis maintenance. Lower metabolic activity at the highest salinity, probably related to valves closure, helped to mitigate the increase of LPO in this condition. At low salinity (14), despite an increase of antioxidant enzymes activity, LPO increased, probably as a result of ROS overproduction from higher electron transport system activity. The present findings demonstrated that Mytilus galloprovincialis oxidative status and metabolic capacity were negatively affected by low pH and salinity changes, with alterations that may lead to physiological impairments namely on mussels reproductive output, growth performance and resistance to disease, with ecological and economic implications.Indicators: Physiological and biochemical changes in Mytilus galloprovincialis in response to low pH and salinity changes