Carps

A novel potassium ion current induced by muscarinic stimulation (IKACh2) is characterized in atrial cardiomyocytes of teleost fishes (crucian carp, Carassius carassius; rainbow trout, Oncorhynchus mykiss) by means of the whole-cell patch-clamp technique. The current is elicited in atrial, but not ventricular, cells by application of carbamylcholine (CCh) in moderate to high concentrations (10(-7)-10(-4) mol l(-1)). It can be distinguished from the classic IKACh, activated by the βγ-subunit of the Gi-protein, because of its low sensitivity to Ba(2+) ions and distinct current-voltage relationship with a very small inward current component. Ni(2+) ions (5 mmol l(-1)) and KB-R7943 (10(-5) mol l(-1)), non-selective blockers of the sodium-calcium exchange current (INCX), strongly reduced and completely abolished, respectively, the IKACh2. Therefore, IKACh2 was initially regarded as a CCh-induced outward component of the INCX. However, the current is not affected by either exclusion of int...

Blood zinc level, hematological parameters and blood cell morphology were evaluated in common carp immediately after 3 h exposure to 20 mg dm-3 of zinc (ZnO), and in 24, 48 and 96 hours after the end of it (Zn24, Zn48, Zn96). Blood zinc level in the non-exposed fish was 8 mg dm-3, reached a maximum of 20 mg dm-3 in Zn48, while it dropped to 9 mg dm-3 in Zn96. Zinc caused a stress reaction in fish indicated by an increase in hematocrit value in ZnO, and elevated plasma glucose level and trombocytosis which persisted until the end of the experiment. Zinc-exposed fish showed an increased frequency of abnormal erythrocytes, and a compensatory release of immature erythro-cytes to the blood stream. In zinc-treated fish, leukocyte count initially increased and subsequently decreased significantly below the control level due to a drop in lymphocyte number. Lymphocyte viability was reduced, and abnormal lymphocytes appeared. A decreased count of juvenile neutrophiles, and reduced phagocyte activity also occurred. The results indicate possible zinc-induced disturbances in both specific and non-specific immune mechanisms.

A 90-day feeding trial was carried out to determine and compare the effects of duckweed (Lemna minor) and soybean (Glycine max) meals as a source of protein on the growth performance, growth hormone levels and proximate composition of Grass carp, Ctenopharyngodon idella (Valenciennes, 1844) and Silver carp, Hypophthalmichthys molitrix (Valenciennes, 1844) in monoculture as well as polyculture system. In the present study, 35% protein practical diets, FSBM (feed containing 21% soybean meal) and FDW (feed having 21% duckweed) were prepared as a source of protein. At the end of the experiment, Grass carp showed a non-significantly higher growth rate as compared to Silver carp when fed FDW while Silver carp showed a higher growth rate in response to FSBM diet in both culture systems. A similar trend was observed in Percentage weight gain (% WG), specific growth rate (SGR%) and feed conversion efficiency (FCE%). The Grass carp and Silver carp fed with FDW and FSBM diets showed significantly (P<0.05) higher growth hormone levels in polyculture as compare to monoculture system. In this study, proximate composition analysis showed approximately similar composition of both diets. It can be concluded from this study, that duckweed can be used as a protein source in fish feed for the selected fish species. 1. Introduction In a world where millions of people, especially in Asia and Africa suffer from chronic malnutrition, aquaculture will play a significant role to meet the huge challenge of global food security and economic growth [1]. The increasing aquaculture has led to dependence on artificial feeds. Protein is the costly component in fish feeds and also a very essential factor affecting growth performance of fish and feed cost [2]. Fishes have high dietary protein requirement. Reducing the costs of fish feed will be key factor for successful development of aquaculture [3]. Literature from text books shows a lot of difference in protein requirement of fish with special reference to species, age, culture system and overall ecological perspectives [4-6]. Duckweed (Lemna minor) is a natural protein source which has high quality of essential amino acids than most other plant proteins and shows more close resembles to animal proteins [7-11]. The duckweed contains high protein content, about 400 g/kg, closely resembles soybean meal and it has also balanced amino acid profile, particularly lysine (6.9 g/100 g protein) which is a limiting amino acid in other plant proteins [12]. Duckweed leaves contain very low amount of fiber, therefore even monogastric animals can digest it and many fishes, especially herbivorous consume duckweed readily because the cell wall of this plant has low lignin [13]. Thus, duckweed shows enhanced digestibility and is considered as an ideal protein source of fish feed [14-16]. Duckweed grown on nutrient-rich medium has a high concentration of important trace elements such as, phosphorus and potassium. It also contains pigments especially carotene and xanthophyll, which make duckweed important dietary supplement for fish feed [17]. Soybean meal (Glycine max) is one of the common ingredient in fish feed as it contains high protein content and adequate amino acid profile. However, it has many anti-nutritional factors such as; trypsin inhibitor, phytic acid, oligosaccharides (raffinose, stachyose), antigenic factors, lectins, saponins, lipoxidase, phytoestrogens, and goitrogens which limit its use in fish feed [18]. The reduced growth with soybean might be due to its sub optimal amino acid balance and also due to the presence of anti-nutritional factor, especially trypsin inhibitor [19] .

Early developmental stages of fish are particularly sensitive to water pollution. Heavy metals may affect various developmental processes during the embryonic period, which results in a reduction of offspring quantity and quality. Waterborne metals may accumulate in the gonads of spawners and adversely affect gamete production and viability, or exert direct toxic influence upon developing embryos. The egg shell does not fully protect the embryo against metal penetration, particularly during the swelling phase; thus, metals may accumulate in the egg. The results depend on metal concentration and range from developmental disturbances to death of the embryo. Metals disturb various processes of fish embryonic development and affect the development rate. Early stages just after fertilization are particularly sensitive to metal intoxication, when most disturbances and the highest embryonic mortality occur. Waterborne metals also promote developmental anomalies during organogenesis, including body malformations. Heavy metals often induce a delay in the hatching process, premature hatching, deformations and death of newly hatched larvae. All these disturbances result in reduced numbers and poor quality of the larvae, which show small body size, high frequency of malformations and reduced viability.

The immune response to mixed whole cell antigens of Aeromonas hydrophila, Edwardsiella tarda and Pseudomonas fluorescens, the common Gram negative bacterial pathogens associated with diseases of Indian major carps were evaluated for their efficacy in triggering antibody responses in rohu, Labeo rohita (Ham.). The rohu yearlings were either immunized with antigens from single bacterial strain, A. hydrophila, E. tarda and P. fluorescens or a combination of all three. An antibody response was detected at 1st week post immunization that rose significantly (p&amp;lt;0.05) at 4th week post immunization in all the immunized groups. The antibody level started declining after 8th week but persisted up to 10th week post immunization in all the immunized groups. Similarly, no significant difference (p&amp;gt;0.05) in the antibody level was found between groups immunized with single and mixed bacterial antigens. Moreover, the use of mixed bacterial antigens did not jeopardize the specific immune response to the vaccine components. Upon challenge with single pathogen, a high relative percent survival was recorded in the group immunized with mixed bacterial antigens and was comparable to those fish immunized with the single bacteria.

A study was conducted to determine whether changes in thyroid and vitamin A dynamics were induced in ranch mink exposed to environmentally relevant concentrations of polyhalogenated aromatic hydrocarbons. Adult female mink were fed diets that contained 0% (control), 10%, 20%, or 30% wild carp (Cyprinus carpio) collected from the Saginaw River, Michigan, USA. Total polychlorinated biphenyls concentrations were 0.03, 0.83, 1.05, and 1.69 mg/kg feed, respectively; the 2,3,7,8-tetrachlorodibenzo-p-diozin toxic equivalents were 3.4, 27.9, 47.6, and 73.2 ng/kg, respectively. Diets were fed 3 weeks prior to breeding and throughout gestation and lactation. When the kits were weaned at 6 weeks of age, they were continued on their respective diets until 27 weeks of age. Plasma thyroid hormone concentrations, thyroid gland activity and structure, and vitamin A dynamics were assessed in young mink at 6 and 27 weeks of age. Plasma total T4 and free T4 in 6-week-old female and male kits fed the 10% carp diet were significantly higher than those of controls, while kits fed the 20% and 30% carp diet had nonsignificant decreases relative to the control mink. Plasma total T3 concentrations in 27-week-old juvenile males fed the 30% carp diet were significantly lower than those in individuals fed the 10% carp diet. No overt thyroid toxicity was apparent as thyroid weight, activity, and structure in kits and juveniles of both sexes were similar among diet groups. Plasma retinol and total ester concentrations in both kits and juveniles were reduced in mink fed the 30% carp diet relative to controls. The ratio of retinol to retinyl palmitate in livers of juveniles fed the 30% carp diet was two times higher than that in control mink. Significant reductions in kidney retinol and fatty acyl retinyl esters were observed in kits and juveniles fed the 30% carp diet relative to control values.

The crucian carp ( Carassius carassius ) seems unique among vertebrates in its ability to maintain cardiac performance during prolonged anoxia. We investigated whether this phenomenon arises in part from a myocardium tolerant to severe acidosis or because the anoxic crucian carp heart may not experience a severe extracellular acidosis due to the fish&#39;s ability to convert lactate to ethanol. Spontaneously contracting heart preparations from cold-acclimated (6–8°C) carp were exposed (at 6.5°C) to graded or ungraded levels of acidosis under normoxic or anoxic conditions and intrinsic contractile performance was assessed. Our results clearly show that the carp heart is tolerant of acidosis as long as oxygen is available. However, heart rate and contraction kinetics of anoxic hearts were severely impaired when extracellular pH was decreased below 7.4. Nevertheless, the crucian carp heart was capable of recovering intrinsic contractile performance upon reoxygenation regardless of the ...

In this study which was carried out between March 2003 and February 2005 Fe, Cu, Zn, Mn, Cr, Pb and Cd contents were determined in muscle, liver and gill of carp (Cyprinus carpio L., 1758) caught from Beyşehir Lake. Among the heavy metals analyzed Cr, Pb and Cd were below the detection limit (<0.03). Heavy metal concentrations varied significantly depending on the type of the tissue and season. The highest metal concentrations were found in the liver, followed by gill and muscle. Heavy metal levels in tissues of carp were increased in summer and winter, while were decreased in autumn and spring. The present study shows that precautions need to be taken in Beyşehir Lake in order to prevent heavy metal pollution that can occur in the future.

Immersion vaccination is common practice in aquaculture, because of its convenience for mass vaccination with sufficient protection. However, the mechanisms of antigen uptake and presentation, resulting in a protective immune response and the role of the innate immune system therein are largely unknown. The impact of immersion vaccination on fish physiology and on the ensuing innate and specific immune response was characterized with fluorescently labeled particulate and soluble model antigens. Vaccination of common carp by direct immersion (DI) or hyperosmotic immersion (HI; direct immersion, preceded by a brief immersion in a hypertonic solution) greatly enhanced the uptake of soluble, but not particulate antigen through temporary disruption of the integrity of the epithelia of gills and skin. Damage induced is mild and does not impose additional stress over the handling associated with immersion vaccination. Especially HI briefly but strongly activates the innate immune system. W...