Source: DOAJ

ABSTRACT Objective. To determine plasma cortisol procedure in fish using competitive enzymelinkedimmunosorbent assay (ELISA). Materials and methods. Two plasma samplesof juveniles rainbow trout Oncorhynchus mykiss were analized by using ELISA humankit for cortisol assay. For standard curve calibration seven standard solutions ofcortisol in human plasma (0, 20, 50, 100, 200, 400 and 800 were used. Forthe recovery test 50, 100 and 200 standard solutions of cortisol were used;for the linearity test four dilutions of the fish plasma samples (1/2, 1/4, 1/8 and 1/16)were prepared. To each well fish plasma samples and standard solutions were addedand its content were conjugated to peroxidase and subsequently enzyme substratewas added. The enzymatic reaction was stopped by addition of phosphoric acid 0.5 Mand the absorbance was read at 450 nm. The accuracy of the pipetting procedurewas assessed previously. The recovery and linearity percentages, the standard curveand parallelism were determined. Results. The standard curve showed a highcorrelation coefficient (r2 = 0.998). The cortisol concentration of two samplesfluctuated between 64 and 72 Only the 200 standard solution showeda recovery percentage superior to 80%; in contrast, in 50 and 100 therecovery percentage fluctuated between 52 and 71%. In the dilution of 1/2 to 1/8were observed a good linearity (86 to 168%); the samples showed parallelism withthe standard curve. Conclusions. The use of human plasma cortisol for ELISAprocedure is an accuracy and efficiency test for fish cortisol plasma determination

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    ABSTRACT: Different taxa of fish have different tolerances to stress. This implies that for a particular stressor, severity may vary depending on the species to which it was applied. Species may differ in the nature of their physiological response and reproductive consequences to stressors. For example, disturbance or handling may affect the timing of reproduction—accelerating or delaying it as the case may be—in species such as rainbow trout (Oncorhynchus mykiss); however, tilapia (Oreochromis niloticus) respond by acceleration or complete inhibition of reproduction, depending on the maturational stage when the stressor is experienced. Strategies for coping with stress affect reproductive fitness either in terms of gamete or progeny quality. The physiology associated with maturation and spawning appears tightly coupled with stress physiology. Environmental variables, particularly nutrition, are ultimately important in affecting gamete quality and reproductive timing. The physiological response to stressors is also quite polymorphic, within and between species. For example, the circulating concentration of the primary stress response factor cortisol varies greatly among resting and among stressed rainbow trout stocks. Immunocapacity can be influenced by stress, reducing reproductive fitness of broodfish. We propose that maternal systems have been developed to buffer eggs from deleterious consequences of stressors, including regulation of transfer of substances of maternal origin to the egg and in mechanisms controlling the timing of reproduction. Effects of nutritional stressors are moderated by effects on timing of first maturity or subsequent reproductive events and/or by maintenance of quality of some eggs via atresia of others. Deleterious overload of eggs with substances such as cortisol is likely prevented by limiting entry of these compounds into the eggs. Barriers to vertical transmission of numerous pathogens seem to exist, while maternally derived immune protection is provided to assist with disease prevention of pathogenic organisms acquired from parents or by direct post-spawning infection. Timing of reproductive events including puberty, atresia, maturation and ovulation are influenced by other physiological variables responsive to stressors. Knowledge of how a stressor might affect the physiology of a species can help in development of management tactics that lessen the impact of a stressor or even in the development of therapeutants.
    Aquaculture 06/2001; 197(1-197):3-24. DOI:10.1016/S0044-8486(01)00580-4 · 1.88 Impact Factor
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    ABSTRACT: Data on the concentrations of some blood constituents of captive Adriatic sturgeon, Acipenser naccarii, a primitive bony fish, are reported. Serum osmolality, Na+, K+, Cl−, Ca2+, cortisol, glucose and total protein concentrations were measured. The effects of anaesthesia, temperature, crowding and prolonged handling stress were tested on a group of 12 4-year-old sturgeons sampled repeatedly. The anaesthetic dose of MS 222 (140 mg l−1) induced significant osmolality elevation in the sturgeon. After exposure to colder temperature (17 versus 25°C), cortisol and Cl− concentrations significantly decreased. The cultured sturgeon did not seem susceptible to crowding and prolonged handling stress, since neither the serum cortisol and glucose levels nor the other blood parameters were affected by these stressors. Results are compared with the few available data on other chondrostean fish and with those on teleosts.
    Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology 12/1998; 121(4-121):351-354. DOI:10.1016/S1095-6433(98)10134-4 · 1.97 Impact Factor
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    ABSTRACT: Atlantic salmon parr and smolts reared under a natural temperature and photoperiod regime were subjected to an acute handling and confinement stress in early May. Smolts had a mean plasma cortisol concentration of 10 ng/ml before stress and 242 ng/ml 3 h after initiation of stress which returned to pre-stress levels within 8 h. Parr had a plasma cortisol concentration of 4 ng/ml prior to stress which increased to 11 ng/ml 3 h after initiation of stress and returned to pre-stress levels within 8 h. Plasma glucose was significantly higher in parr and smolts 3 h after initiation of stress; in parr, plasma glucose returned to pre-stress levels within 8 h, but not until 48 h in smolts. Plasma chloride concentration in smolts decreased from 139 to 124 mM 3 h after initiation of stress but returned to pre-stress levels within 24 h; plasma chloride in parr was not altered by stress. Plasma thyroxine of parr and smolts peaked at 3 h after initiation of stress and returned to pre-stress levels within 8 h, but smolts had 72% higher levels at 3 h. Pre-smolts (February) and smolts (May) reared under constant temperature (8–10°C) were also subjected to a handling and confinement stress. Although peak levels of plasma cortisol 3 h after initiation of stress were twice as high in smolts, other physiological and endocrine responses were not substantially different between pre-smolts and smolts. The results demonstrate that Atlantic salmon smolts are more responsive to stress than parr and that developmental differences are more important than seasonal changes.
    Aquaculture 10/1998; 168(1-168):237-253. DOI:10.1016/S0044-8486(98)00352-4 · 1.88 Impact Factor