Histological and enzymatic responses of Japanese flounder (Paralichthys olivaceus) and its hybrids (P. olivaceus ♀ × P. dentatus ♂) to chronic heat stress

This study investigated the effects of long-term heat exposure on Japanese flounder (Paralichthys olivaceus) and its hybrids (P. olivaceus ♀ × summer flounder Paralichthys dentatus ♂). From 24 ± 0.5 °C, temperature was increased by 1 ± 0.5 °C in a day and was kept at that temperature for 5 days before next rise. Cumulative survival rate (CSR), cumulative survival rate under different temperature (CSR-T), histological alteration, and related enzyme activities were investigated. In P. olivaceus, mass mortality occurred at 29 and 32 °C (the CSR-T dropped to 42.39 %), and serious gill damages appeared at 30 and 32 °C. Meanwhile, the activities of superoxide dismutase (SOD), catalase (CAT), lysozyme (LZM), and pyruvate kinase (PK) declined around 29 and 32 °C (except for CAT). In comparison with P. olivaceus, the CSR of the hybrids was higher, the gill kept a better structural integrity, and the activities of SOD, CAT, LZM, and PK showed tiny fluctuations. The results suggested that during the process of chronic heat stress, P. olivaceus seemed to be more sensitive to 29 and 32 °C, and the manifestations in survival, histology, and enzyme activity were generally consistent. For the hybrids, the comparatively insensitivity to high temperature might imply its better heat tolerance.     

Physiological responses to starvation in the European eel (Anguilla anguilla): effects on haematological, biochemical, non-specific immune parameters and skin structures

The physiological effects of short-term starvation on some haematological, biochemical and non-specific immune response parameters together with the histological structure of the skin, were investigated in the European eel, Anguilla anguilla. Blood haemoglobin and haematocrit, serum glucose and cortisol, hemolysins, haemagglutinins, and lysozyme in the plasma, kidney and epidermal extract, were measured in fish after 31, 42 and 58 days of starvation, and compared to those of fed fish. Starvation did not affect haemoglobin and haematocrit values, while an increase in glucose and cortisol levels was found in starved eels by day 42. Haemolytic and haemagglutinating activities decreased in starved eels. On the other hand, starvation caused an increase in the lysozyme content in the epidermal extracts, while no significant variations were observed in kidney and plasma. On the whole, no major changes in metabolic, haematological and non-specific immune parameters were observed when short-term (less than 2 months) starvation was applied to the European eel, suggesting an adaptive response to starvation, rather than a typical alarm–stress response, allowing this species to withstand food deprivation.     

Levels of Vitellogenin in Male Japanese Medaka (Oryzias latipes) Exposed to the Chemotherapeutics: Oxytetracycline,Romet-30®, and Copper Sulfate

ABSTRACT

Japanese medaka (Oryzias latipes) were exposed to oxytetracycline and Romet-30^® at daily doses via feed of 0.06 mg, 0.11 mg, and 0.28 mg per gram body weight for 11 days, and at daily doses of 0.05 mg, 0.10 mg, and 0.15 mg per gram body weight for 5 days, respectively. In addition, fish were exposed to copper sulfate in their aquaria water at 1.85 mg/L for 1 h each day (over a span of 1 day, 7 consecutive days, or 1 day in every 3 to 5 days for a total of seven doses). Vitellogenin levels were measured in fish using a sandwich enzyme-linked immunosorbent assay (ELISA). Vitellogenin levels were not induced from exposure to either oxytetracycline or Romet-30® (P > 0.05); however, copper sulfate for 1 h on 1 day showed a decrease in vitellogenin from the control fish and other treatment groups (P = 0.007). Under these test conditions, oxytetracycline, Romet-30, and copper sulfate were not found to act in medaka as estrogenic compounds by inducing vitellogenin.     

Effects of chronic exposure to γ-HCH (Lindane) on brain serotonergic and gabaergic systems,and serum cortisol and thyroxine levels of rainbow trout,Oncorhynchus mykiss

Rainbow trout (Oncorhynchus mykiss) were implanted intraperitoneally with 0.5 ml.100 g^–1 body weight of coconut oil alone (controls) or coconut oil contaning 0.05 mg of -HCH (Lindane). After 18 days, changes in brain serotonin and GABA metabolism, as well as in serum cortisol and thyroxine levels, were measured. A lower final body weight was observed in -HCH treated fish when compared with control fish. No significant differences were found for serum thyroxine levels between control and treated fish, but a significantly higher cortisol level was found in the -HCH-implanted trout. Although GABA levels did not differ significantly in any brain region in the two treatment groups, the activity of the serotonergic system was significantly altered by the pesticide in both the hypothalamus and the telencephalon.     

Comparison of the Channel Catfish,Ictalurus punctatus (NWAC103 Strain) and the Channel × Blue Catfish,I. punctatus × I.furcatus,F1 Hybrid for Growth,Feed Efficiency,Processing Yield,and Body Composition

Abstract

A pond trial was conducted to compare growth, feed efficiency, survival, processing yield, and body composition of the NWAC103 strain of channel catfish, Ictalurus punctatus and the F₁ channel X blue catfish hybrid (CB hybrid), I. punctatus X I. furcatus. Each genotype was stocked into five 0.4-ha earthen ponds at a rate of 14,820 fish/ha. Initial weights were 24.9 and 31.8 g/fish for the NWAC103 strain of channel catfish and the CB hybrid, respectively. Fish were fed a commercial, 28% protein diet once daily to satiation for 160 days. Compared to NWAC103 channel catfish, the CB hybrid consumed more diet, gained more weight, converted diet more efficiently, and had higher net production, survival, carcass yield, nugget yield, visceral fat, fillet moisture and protein, and a lower level of fillet fat. There were no differences in fillet yield and fillet ash concentration between the channel X blue catfish hybrid and the channel catfish. These results suggest that the CB hybrid possesses superior production traits compared with the NWAC103 channel catfish. However, problems of producing a large number of hybrid fingerlings in a cost-effective manner remain to be resolved before the hybrid catfish can be commercially farmed.     

Sacha inchi meal as a fish-meal replacer in red hybrid tilapia (Oreochromis niloticus × O. mossambicus) feeds: effects on dietary digestibility,growth metrics,hematology, and liver and intestinal histology

Aquaculture International - The utilization of sustainable and innovative raw materials to substitute for traditional fishmeal (FM) ingredients is required for the aquaculture sector. Sacha inchi...     

Interactions between sea turtles and dredge gear in the U.S. sea scallop (Placopecten magellanicus) fishery, 2001–2008

Since 2006, the National Marine Fisheries Service (NMFS) has mandated gear modifications (“chain mats”) and fishing effort reductions in the U.S. Mid-Atlantic sea scallop dredge fishery to alleviate or minimize interactions with sea turtles. Turtle interactions with gear can be defined as those that are “observable” based on standard fishery observer protocols, plus unobserved interactions, which include both quantifiable and unquantifiable interactions. Once a gear modification is in place, a turtle interaction that was once observable may become unobservable, because the gear modification successfully prevented the turtle from being captured. This paper describes turtle interactions in scallop dredge gear from 2001 to 2008, identifies gear and environmental correlates with observable interaction rates, and reports the average annual number of interactions and adult-equivalent interactions before and after chain mats were mandated in the fishery. Fisheries observer data were used to develop a Generalized Additive Model (GAM) to estimate rates of observable interactions of hard-shelled turtles. These rates were applied to commercial dredge fishing effort to estimate the total number of observable interactions, and to infer the number of unobservable, yet quantifiable interactions after chain mats were implemented. Interaction rates of hard-shelled turtles were correlated with sea surface temperature, depth, and use of a chain mat. The average number of annual observable interactions of hard-shelled turtles in the Mid-Atlantic scallop dredge fishery prior to the implementation of chain mats (1 January 2001 through 25 September 2006) was estimated to be 288 turtles (CV = 0.14, 95% CI: 209–363), which is equivalent to 49 adults. After implementation of chain mats, the average annual number of observable interactions was estimated to be 20 turtles (CV = 0.48, 95% CI: 3–42), equivalent to 4 adults. If the rate of observable interactions from dredges without chain mats had been applied to trips with chain mats, the estimated number of observable and inferred interactions of hard-shelled species after chain mats were implemented would have been 125 turtles per year (CV = 0.15, 95% CI: 88–163). Results from this analysis suggest that chain mats and fishing effort reductions contributed to the decline in estimated turtle interactions after 2006.     

Molecular characterization and expression analysis of hypoxia-inducible factor-1α, factor-2α, and factor-3α and physiological response to hypoxia exposure in Amur minnow (Phoxinus lagowskii)

Aquaculture International - To further enhance our understanding of hypoxia tolerance in the fish Phoxinus lagowskii, hypoxia-inducible-factor (HIF) genes were cloned to analyze their biological...     

Fatty acids as a tool to compare cachara (Pseudoplatystoma reticulatum) (Siluriformes: Pimelodidae) and hybrid (Pseudoplatystoma corruscans?×?Pseudoplatystoma reticulatum) larvae during early development

In this study, we investigated the physiological alterations during ontogeny for cachara (Pseudoplatystoma reticulatum) and their hybrid larvae (Pseudoplatystoma corruscans?×?P. reticulatum) using lipids and fatty acids as physiological tools to elucidate the basis for differences in these groups?? productivity in an industrial setting. Eggs and larvae samples were collected during January and February of 2008 in the city of Bandeirantes, MS, and were divided into three primary phases: phase I (0?C16?h after fertilization); phase II (24?h after fertilization to 6?days after fertilization); and phase III (7?C25?days after fertilization). The larvae of both groups showed a high degree of similarity, suggesting that the hybrid larvae showed a high level of heritability from the cachara broodstock. Analysis of the total lipid content provided evidence that there is no alteration in lipid concentration during ontogeny for both groups (i.e., the cachara and hybrids). However, the fatty acid profile showed that during the endogenous feeding period (phase II), when the larvae must use the energy reserves from the mother, the cachara larvae used mainly monounsaturated fatty acids for development. This is typical for most fish species, though notably, the hybrids preferentially used saturated fatty acids. Furthermore, certain specific changes demonstrate unique patterns of energy utilization and structural substrates, which may aid in elucidating the empirical differences reported by fish farmers (i.e., that the hybrids perform better than cacharas in captivity).     

An enzyme linked immunosorbant assay (ELISA) for testosterone, estradiol, and 17,20β-dihydroxy-4-pregenen-3-one using acetylcholinesterase as tracer: application to measurement of diel patterns in rainbow trout (Oncorhynchus mykiss)

A simple and rapid Enzyme Linked ImmunoSorbant Assay (ELISA) is described and validated for testosterone, estradiol, and 17,20-dihydroxy-4-pregnen-3-one (17,20P). A general procedure for preparation of the acetylcholinesterase labeled steroid is described which is applicable to any steroid. Use of acetylcholinesterase tracer increased the sensitivity of assay so that reliable measurements of each steroid could be achieved with only 10 l of plasma. The ELISA was applied to measurement of all three steroids every hour for over 24 hours in a female trout using cannulation of the dorsal aorta. This high sampling frequency revealed several short-term (<2 h) episodic pulses of testosterone and estradiol.