Larval development of carp, Cyprinus carpio L., in acidic water

Laboratory experiments measuring survival and growth at various pH levels and two temperatures indicate that the threshold of pH of water below which larval development of carp is stopped is 5.0–5.2, the development of some individuals being stopped within the pH range 5.0–5.5. Inhibition of development is due to the inability of a larva to fill its swimbladder with air, this preventing swimming and leading to death from starvation. In water of pH 5.5–6.0 the development may be undisturbed, though slower. The effect of water acidification is reflected in slower growth rate and prolongation of the larval stages of development.     

In vivo levels of aminoacyl-tRNA species during acclimatization of the carp Cyprinus carpio

• 1.1. The behaviour of the tRNA population during the acclimatization process was studied, examining the intracellular levels of aminoacylated-tRNAs in livers from summer and winter adapted carps (Cyprinus carpio).
• 2.2. The in vivo content of Val-tRNA, Ala-tRNA and Met-tRNA decreased significantly during the summer season, in which Val was 80%, Ala 47% and Met 54% with respect to the values attained in winter.
• 3.3. The half-life for the nonenzymic deacylation showed significant variations for the two populations of aminoacyl-tRNA obtained from summer and winter acclimatized fish.

     

Induced triploidy in carp, Cyprinus carpio L.

A method for mass production of triploid carp was developed by the cold treatment of eggs after fertilization. Triploidy was demonstrated by cytophotometry and chromosome preparation techniques. Of the haploid embryos, 100% showed morphological abnormalities and died soon after hatching. Haploid embryos of maternal and paternal origin occurring in the course of cold treatment were distinguished by using a genetic marker. Among morphologically normal larvae, the frequency of triploidy was 100%, and the viability of the triploid embryos, larvae and the juvenile fish did not differ from the diploid control. Sex differentiation started in the triploid fish, but was greatly retarded. Gonad size and the small number of growing oocytes suggest that most of the triploid individuals will be sterile. Triploid carp grew at the same rate as diploid controls in the laboratory test.     

Vascularization and related distribution of leucocytes in carp, Cyprinus carpio L., head kidney

The distribution of lymphoid cells in the carp head kidney was investigated in relation to the vascular system. Blood vessels in the head kidney were histologically identified into arteries, sinusoids and two types of veins: renal veins and portal, which were distinguished by India ink injection into the caudal vein. By histological and histoplanimetrical observations it was found that the head kidney contained a number of lymphoid cells, which mainly aggregate around the connections between the portal veins and sinusoids, and that the cellular density of the aggregations was higher than in the thymus.
Pigment-containing cell clusters were also observed around these connections. This arrangement of the blood vessels suggests that it is one of the structures able to trap foreign materials, and the occurrence of the lymphoid clusters around the portal veins is a phylogenetic sign of the morphological division between granulopoietic and lymphatic tissues in the carp head kidney.     

Investigation on carp, Cyprinus carpio L. gynogenesis

A reliable method for gynogenetic mass-production has been developed in carp ( Cyprinus carpio L.). The effect of different cold shock treatments applied after fertilization were examined. The yield of viable diploid gynogenetic animals could be significantly increased when the cold shock was applied 5 min or 15 min after fertilization. A negative correlation has been found between the effectiveness of these two treatments, so both were used on separate batches of eggs. By means of gynogenesis, the crossover frequency and map distance of the transferrin locus have been determined. Successful pilot experiments were made on grass carp ( Ctenopharyngodon idella Val.) and sheatfish ( Silurus glanis L.) with respect to gynogenetic mass production.     

The immune response of carp, Cyprinus carpio L., following injection of antigen-antibody complexes

Cyprinus carpio immunized with antigen-antibody complexes formed at equivalence were found to have both good memory and enhanced serum antibody responses compared with fish primed with antigen alone. Only priming with antigen or complex in adjuvent produced comparable results. Complexes formed in antigen excess gave better precipitation responses during the secondary response than in corresponding control groups injected antigen alone or in adjuvant. The role of antigen-antibody complexes in the fish immune system and the possibility of using such complexes to vaccinate fish are discussed.     

The secondary immune response of young carp, Cyprinus carpio L., following injection of cortisol

Cyprinus carpio immunized at 9 weeks after hatching with either human gamma globulin or trinitrophenylated sheep red blood cells either fail to respond or respond poorly on secondary exposure at 17 weeks of age. Injection of cortisol either simultaneously with the antigen, or 3 days prior to, or 3 days after antigen, permits the antibody response to proceed upon subsequent challenge. The implication of these results for the ontogeny of the fish immune response is discussed.     

The effect of temperature on survival of carp fry, Cyprinus carpio L., in acidic water

Studies of carp fry, Cyprinus carpio , showed that temperature elevation within the range of 18–26° C increases the mortality caused by lowering the pH of water. It was found that 26-h acclimation in acidic water (mean pH 4.22) prolongs the survival of fish in water at pH 4.02–4.20. Carp fry obtained less oxygen in water at pH 4–0, as compared to pH 7–0. The differences–though insignificant–pointed to an adverse effect of acidification on the respiratory processes.     

A comparison of the pond culture of carp, Cyprinus carpio L., in Britain and mainland Europe

In recent years the requirement for carp in the U.K. has escalated, mainly due to the restocking market. This demand cannot be met from mainland Europe because of import restrictions and home production has increased. Freshwater coarse fish farming has been historically unimportant in Britain and few scientific data exist for pond culture under British conditions. In general, continental guidelines are followed but the growing-on ponds are smaller. The climate and the nature of the sites have often resulted in unreliable spawning. First year survival and growth tends to be poorer but growth rates in the second year are comparable. Carp for restocking ( c. 300 g) can be reared in 2 years and carp for the table ( c. 1000 g) can sometimes be produced in 3 years. Levels of production, however, compare favourably with more traditional carp culture, up to 480 kg ha⁻¹ per year using extensive cultivation and up to 2200 kg ha⁻¹ per year with intensive rearing and pelleted foods. The sites in Britain for which data exist have, however, been eutrophic in contrast to the more mesotrophic sites on the mainland. This apparent difference in base, line productivity may explain the relatively good production performance so far in Britain.     

Bone resorption and bone remodelling in juvenile carp, Cyprinus carpio L.

The present study considers the important role of bone resorption for bone growth in general, and aims to clarify if and how bone resorption contributes to the skeletal development of carp, Cyprinus carpio L., a teleost species with ‘normal’ osteocyte‐containing (cellular) bone. To ensure the identification of osteoclasts and sites of bone resorption independently from the morphology of the bony cells, bones were studied by histological procedures, and by demonstration of the enzymes which serve as osteoclast markers, viz. tartrate resistant acid phosphatase (TRAP), ATPase and a vacuolar proton pump. Two types of bone‐resorbing cells were observed in juvenile carp: (1) multinucleated giant cells displaying morphological and biochemical attributes which are known from mammalian osteoclasts; and (b) flat cells which lack a visible ruffled border and for which identification requires the performance of enzyme histochemical procedures. Bone resorption performed by osteoclasts mainly occurs at endosteal bone surfaces. To a lesser extent, bone resorption also takes place at periosteal bone surfaces, but without an apparent connection to bone growth. The latter observation, and the occurrence of bone remodelling, suggest that the endoskeleton of juvenile carp might be involved in mineral metabolism. Morphological differences and biochemical similarities to bone resorption in teleosts with acellular bone are discussed.     

Microsatellite markers in common carp (Cyprinus carpio L.)

Microsatellite markers of the poly (CA) type in common carp ( Cyprinus carpio L.) are described. Clones containing a (CA) repeat were isolated from a common carp genomic library and sequenced. The number of repeats found was high compared to mammals but comparable with other teleost fishes. Classification of the repeats (perfect, imperfect and compound) are compared with the Atlantic cod ( Gadus morhua L.), rainbow trout ( Oncorhynchus mykiss ), and Atlantic salmon ( Salmo salar L.). A total of 41 primer sets were designed and tested for polymorphism on a test panel of eight animals (derived from outbred lines, inbred lines and gynogenetic clones). Thirty-two markers were found to be polymorphic. The heterozygosity in the outbred animals was 60·4%, 51·1% in the inbred animals and 0% in the gynogenetic clones. The average number of alleles among the eight animals was 4·7 per marker. Six markers (18·8%) gave an additional polymorphic amplification product besides the polymorphic amplification product in the expected size range. The possibility that these loci are tetraploid is discussed. The polymorphic loci described for common carp will be valuable as genetic markers for use in population, breeding, and evolutionary studies.     

Cardio-respiratory synchronization and myocardial function in hypoxic carp, Cyprinus carpio L.

Moderate hypoxia (Pio₂, = 50 mmHg) caused tachycardia in carp, Cyprinus curpio Linnaeus, whereas severe hypoxia (Pio₂, from 30 to 5 mmHg) coincided with bradycardia accompanied by alterations of the waveforms of the electrocardiogram. A cardio respiratory synchronization developed during hypoxia and was maintained during bradycardia. The data raised the question: Does hypoxic bradycardia in part result from myocardial dysfunction or only from regulatory adjustments?     

Differential macrophage polarisation during parasitic infections in common carp (Cyprinus carpio L.)

In many parasitic infections both classically activated macrophages (caMF) and alternatively activated macrophages (aaMF) play a pivotal role. To investigate if both types of macrophages also play an important role during parasitic infections in fish, we infected carp with either Trypanoplasma borreli or Trypanosoma carassii and determined the activation state of the head kidney leukocytes (HKL). Nitrite production was used as read-out for caMF and arginase activity as read-out for aaMF. Basal nitrite production and arginase activity of HKL were moderately different between the two infections. Differences were observed, however, after ex vivo re-stimulation of HKL. Re-stimulation with LPS and T. borreli lysates increased nitrite production by HKL of T. borreli-infected fish. Re-stimulation with cAMP increased arginase activity in HKL of T. carassii-infected fish. Our results indicate that T. borreli-infected carp are more prone to increase nitrite production by caMF while T. carassii-infected fish are more prone to increase arginase activity by aaMF.     

Effects of temperature, oxygen and carbon dioxide on osmotic fragility of carp, Cyprinus carpio L., erythrocytes

The in vitro effects of gases and temperature on the osmotic fragility of carp erythrocytes were studied. At the three different temperatures analyzed (5, 11 and 20°C) there was no noticeable modification in erythrocyte membrane osmotic resistance. Osmotic fragility of red blood cells was altered by CO₂ and air treatment, as compared to the standard procedure. This suggests the need to take into account a possible moderate hypoxia that develops in the routine procedure of nucleated erythrocyte osmotic fragility tests.     

The effects of starvation and refeeding on plasma amino acid levels in carp, Cyprinus carpio L., 1758

Plasma amino acid (AA) levels of carp, Cyprinus carpio L., 1758, were analysed after various periods of starvation as well as after 12 days of refeeding. The levels were compared to control groups, which had been previously fasted for 24 h. A positive correlation between dietary and plasma essential amino acid (EAA) concentrations was observed in all of the control groups.
The effect of starvation on the dynamics of AA concentration was different according to the period of starvation. Fasting already produced a decrease of total α-AA levels at 2 days, and these low levels were maintained until 5 and 8 days. These short periods of fasting affected the levels of EAA (especially branched-chain AA) more than those of non-essential amino acids (NEAA). The only AA that increased was Ala, which rose at 5 days of starvation, surpassing the levels of the control group. These high levels were maintained until 19 days of starvation.
A different situation was observed at 19 days, when an important increase of total α-AA levels was produced, the branched-chain AA being the most notable among EAA and Glu/Gln among NEAA. Later, at 50 days of starvation, total α-AA, EAA (except Leu and Ile) and NEAA decreased.
After 50 days of starvation, 12 days of refeeding did not modify the levels of EAA and NEAA, and their concentrations were lower than those of the control group, which presented an increase of total AA at this time. The differences observed on the changes of individual AA levels are discussed.