The ultrastructure of leucocytes in carp (Cyprinus carpio)

Leucocytes from anterior kidney, middle kidney, spleen, thymus and peripheral blood of Common carp were examined. Lymphocytes were found to have a similar fine structure to that of mammals. Thrombocytes had a similar appearance to lymphocytes, but the former were sometimes distinguishable by vesicles in series and/or microtubules below the plasma membrane. Blast cells, monocytes and clearly identifiable plasma cells were also seen. Neutrophils had varying proportions of at least two types of granules, which often presented inclusions. Owing to their different granules, eosinophils and basophils were morphologically distinguishable, but differentiated cells with equal proportions of the two types of granules were also seen. In addition, cells of uncertain nature, possessing rod-shaped granules, were observed. The different leucocyte types showed the same morphology in the different lymphoid organs and in peripheral blood, although they were present in different proportions.     

Efficacy of quinine against ichthyophthiriasis in common carp Cyprinus carpio

Ichthyophthiriasis, caused by Ichthyophthirius multifiliis, is an economically important worldwide parasitic disease that infects all freshwater fish. Since the banning of malachite green for use in food fish, there has been a great need for alternative therapeutants. The goal of this study was to investigate the efficacy of quinine against I. multifiliis. Parasite developmental stages from our laboratory-established life cycle in rainbow trout Oncorhynchus mykiss were exposed to quinine in vitro, and a dual fluorescent staining technique was used to allow a clear distinction between viable and damaged parasites. Furthermore, the effect of quinine was assessed in vivo by oral administration and intraperitoneal injections in common carp Cyprinus carpio. The results of the in vitro experiments proved quinine to be effective against the parasite. Quinine injected at a dosage of 60 mg kg(-1) body weight resulted in a significantly lower number of trophonts. In contrast, in-feed trials did not show a significant reduction of trophonts after treatment commencing 1 d after infection with concentrations of up to 20 g quinine kg(-1) feed for 3 d. After a 14-d treatment at concentrations of up to 10 g quinine kg(-1) feed prior to theront exposure, there was also no significant difference in parasite numbers between treated and control groups. The results of oral versus parenteral application of quinine indicate that the substance is not completely absorbed from the intestinal tract of common carp. However, medicated feed containing higher concentrations of quinine was less readily accepted by the fish, presumably due to the bitter taste.     

Microridges of oral mucosal epithelium in carp,Cyprinus carpio

Summary The surface of carp oral mucosa is characterized by various patterns of microridges about 0.3 m wide, 0.1 m high, and of various lengths. To elucidate the derivation and function of these microridges, the oral epithelium was examined by light- and electron microscopy. Microridges were present only on the surfaces of the superficial cells. Therefore, microridges on renewed superficial cells are presumed to be formed after old superficial cells have been discarded, and the various patterns of microridges found on the cell surface appear to indicate the progress of their development. In thin sections, the outer leaflet of the plasma membranes of microridges stained strongly with ruthenium red, and the underlying cytoplasm was packed with many fine filaments. The superficial cells contained many secretory vesicles that were PAS-positive but Alcian blue-negative at pH 2.5 and pH 1.0. However, after sulfation the vesicles gave a positive reaction with toluidine blue. These vesicles are secreted by exocytosis at the free surface of the cells. After release, the membranes of the vesicles are thought to be utilized for formation of microridges. On the basis of these observations, the possible function of microridges is discussed.This study was supported by grants from the Ministry of Education, Science and Culture, Japan     

Cadmium-binding to transferrin in the plasma of the common carp Cyprinus carpio

In this study, it was investigated by autoradiography with radioactive cadmium after Western blotting of two-dimensional electrophoresis gels, to which proteins cadmium is mainly bound in plasma of common carp Cyprinus carpio. The obtained results demonstrate that in carp plasma, cadmium is primarily bound to two high molecular weight proteins. Relative small amounts are bound to a protein with M(r) approximately 60000. The other metal-binding protein, with M(r) approximately 70000 and pI approximately 6.7 was identified as transferrin. The conditional equilibrium constants for the binding of cadmium ions to the two metal-binding sites of this protein were calculated as logK(1)=5.40+/-0.12 and logK(2)=4.66+/-0.21, which are comparable to those of human transferrin under the same experimental conditions. Transport of cadmium in plasma of carp was found to be different from that of brown trout Salmo trutta and man, where cadmium is mainly bound to albumin and transferrin. The prominent binding of cadmium to transferrin can be explained by the absence or at least the very low concentrations in which albumin is present in carp plasma.     

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.     

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.     

Induction of immunosuppression to bacterial antigens in carp, Cyprinus carpio

Typical primary antibody responses were found after injecting carp maintained at 25°C with formalin-killed (Fk) Vibrio anguillarum bacteria, but not in fish injected with the same antigen held at 12° C. There were no significant increases over the primary responses in fish receiving a second injection 60 days after the first injection.
The differences in the results between fish groups receiving three V. anguillarum antigens at two dosages were found to be insignificant in most of the experiments. A comparison of the antibody titres of fish groups after challenge with Fk bacteria showed no difference from control fish receiving a single injection similar to the challenge dose or fish receiving a previous injection with the antigens emulsified in complete Freund's adjuvant (CFA) at 25° C. However, significant immunosuppression was found in fish that were given the primary injection intracardially at 25° C or 12° C, or with CFA emulsion at 12° C.     

Proteinase activity in the early developmental stages of the carp, Cyprinus carpio

Embryonic and early postembryonic development of the carp is associated with an increase in the content of soluble proteins and nitrogen of non-protein nitrogenous components. Simultaneously, the activity of trypsin-like and chemotrypsin-like peptide hydrolases increases together with the increase in the degree of proteolysis. These data suggest that the development of carp embryos and early larva is accompanied by intensification of two opposite processes--synthesis and catabolism of proteins. The observed changes are more evident in early postembryonic period as compared with the early stages of embryogenesis.     

Electrocardiograms recorded from the body surface of the carp, Cyprinus carpio

The electrocardiograms (ECGs) in five kinds of bipolar leads were recorded from the body surface of the carp under water. Each component constituting the ECG wave could be detected by the present method. The potentials of the ECGs recorded by the present method were relatively small, the values being 2-64 microV. The electrical axis in most carp was directed toward the right lateral side.     

The energetics of feeding strikes in larval carp, Cyprinus carpio

The prey intake of larval carp is described from high-speed (200–1250 frames s⁻¹) films with synchronous lateral and ventral views. Even in first-feeding carp larvae, the operculars are functional in sealing effectively the opercular slit until the moment of prey intake, and the maxillaries close off the corners of the mouth, preventing leak flow. In reducing the distance between larva and prey during attack, the relative importance of sucking the prey towards the mouth and swimming forward is variable; overall they are about equally important. The volume and the velocity of the water sucked into the mouth cavity during prey uptake are calculated. The energy costs of suction, i.e., accelerating the water sucked into the mouth cavity, during prey intake are estimated from these values. The energy costs of suction and swimming are in the same order of magnitude. Together they form only a fraction of 1% of the energetic content of the prey, so considerations about energy expenditure seem unimportant in a strategy to optimize the prey attack. During searching, however, they will be important. Power requirements during attack may also be important.     

Immunoreactive methionine-enkephalin in the caudal neurosecretory system of the carp,Cyprinus carpio

Summary Methionine-enkephalin (Met-enk) was detected by immunocytochemistry and radioimmunoassay in the caudal neuro-secretory system of the carp Cyprinus carpio. Some cells showing urotensin I (UI)-immunoreactivity reacted to Met-enk antiserum, but others did not. Neurons with urotensin II (UII)-immunoreactivity did not react to Met-enk antiserum; neurons with both UI and UII immunoreactivities also displayed a negative Met-enk reaction. Met-enk was detected by radioimmunoassay in the urophysis, although the content was relatively small compared with that found in other parts of the central nervous system and in the pituitary.     

Different modes of swimming of the carp, Cyprinus carpio L.

An electromyographical study has been made of carp swimming muscles at various points along the body length during sustained and burst locomotion. During sustained swimming, red muscles show a constant time lag between activation of anterior and posterior segments which is practically independent of the speed of locomotion. In contrast, anterior and posterior homolateral segments are activated simultaneously during bursts of rapid movement. This pattern of co-ordination between body segments differs from that reported for other species.     

Effects of a parasite-induced nephritis on osmoregulation in the common carp Cyprinus carpio

Carp Cyprinus carpio infected with the haemoflagellate Trypanoplasma borreli undergo progressive nephritis associated with a destruction of approx. 40% of the nephric tubules. In an attempt to analyse the effect of the nephritis on the osmoregulation of affected carp, the clinical chemical properties of plasma and urine samples were analysed. Parasitised carp excreted greater amounts of electrolytes in their urine than uninfected carp which excreted highly diluted urine with an osmolality of about 10% of plasma osmolality. During the course of the infection, urine osmolality increased up to 26% of plasma osmolality by Day 21 post-infection (p.i.). The plasma:urine ratio of Na+ also increased, while concomitant losses of Mg2+, Ca2+, K+ and inorganic phosphate were less pronounced. Infected carp were able to maintain a normal solute balance in their plasma. Plasma hydration (indicated by decreased protein contents) occurred on Day 21 p.i. Our data indicate that in T. borreli-infected carp, reabsorption processes of the distal renal tubule were disturbed, while secretory and absorption processes in the proximal tubule appeared to be less affected. In addition, infected carp were able to compensate their increased ion losses, probably by (energy-consuming) active absorption processes. The energy budget of infected carp was additionally affected by a substantial direct consumption of plasma glucose by the parasite.     

Molecular characterization of cathepsin L from hepatopancreas of the carp Cyprinus carpio

Purified cathepsin L from carp, Cyprinus carpio, consists of a 28 kDa single-chain form that is different from the 24 and 5 kDa mammalian two-chain form. We cloned cathepsin L from carp hepatopancreas. The sequence consisted of a 1490 bp cDNA and a 1014 bp open reading frame, encoding a deduced protein of 337 amino acids that is likely processed to an active enzyme (single-chain form) with 222 amino acids. Its similarity to other types of vertebrate cathepsin L is less than 69%. Mammalian cathepsin L is further processed to a two-chain form, but possibly this is not the case with carp cathepsin L: the P1 site where cleavage occurred in the two-chain form of mammalian cathepsin L contains a serine, while carp cathepsin L processes a valine. Therefore, carp cathepsin L may have a different mechanism of action from mammalian cathepsin L.     

Actin filaments in microridges of the oral mucosal epithelium in the carp Cyprinus carpio

Summary Actin filaments in the microridges on the surface of the fish oral mucosa taken from Cyprinus carpio were examined by electron microscopy after detergent extraction and decoration with myosin subfragment 1. After extraction with saponin, an irregular and densely packed meshwork of actin filaments was observed in the bases of the microridges, just lateral to the tight junctions with their fibrous undercoats. Actin filaments formed cores in the microridges and numerous linkages were seen between the filaments and the plasma membrane. Extraction with Triton X-100 and decoration with myosin subfragment 1 showed the ends of the actin filaments to be associated with the plasma membrane of the microridges, and in the bases of microridges the filament ends were anchored to intermediate filaments. Some actin filaments interconnected with the fibrous undercoats of the tight junctions. On the basis of these observations, the mechanism of the formation of microridges, including their pattern, is discussed.