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     

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.     

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 effects of peripherally injected serotonin on feeding and locomotor activities in carp Cyprinus carpio L.

The influence of intraperitoneal (IP) and intramuscular (IM) injections of serotonin (5-hydroxytryptamine or 5-HT, 10 μg/g body weight) on a number of parameters of feeding behavior and locomotor activity in carp Cyprinus carpio L. has been investigated. It was shown that exogenous serotonin decreased various parameters of feeding and locomotor activities, and IM injections caused stronger inhibitory effect than IP injections. IP administration of this biogenic amine reduced the food intake in fishes of different age groups, induced an increase of the search reaction time (the latency to leave the starting chamber after its front wall was raised, or latency period for feeding of fish) in carp fingerlings in the experiments with “single” feeding. IM injections significantly lowered food intake of carp fingerlings in 1, 5 and 53 h, two other parameters—during all period of observation. In the experiments with “group” feeding food intake, duration of “group” feeding and total duration of feeding decreased during all period of observation after IM administration and in 1 h after IP injections only. Duration of “single” feeding and locomotor activity were changed less distinctly. The strongest effect of serotonin (up to 100%) was shown for duration of “group” feeding. It was supposed that inhibitory effects of exogenous serotonin on feeding and locomotor activities in carps were caused by its peripheral effects as well as by partial involving of central effect.     

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.     

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.     

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.     

Occurrence of aneuploidy in radiation gynogenesis of carp, Cyprinus carpio L.

DNA content and chromosome numbers were studied in gynogenetic and normal carp embryos. Gynogenetic embryos showed the haploid chromosome number; the occurrence of spontaneous diploidization was rare. Early cold shock treatment of the gynogenetic zygotes resulted in the retention of the second polar body producing a much higher proportion of normally developing viable larvae. The appearance of large numbers of aneuploid embryos in the cold-treated gynogenetic group is explained by the loss or breakdown of chromosomes that are caused in their turn by the absorbtion of the second polar body through the cold treatment.     

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.     

The effect of digested sludge on the common carp, Cyprinus carpio L.

The effects of sewage sludge on the survival of the common carp, Cyprinus carpio, were investigated. It was noted that, when the concentrations of the sludge used for rearing carp exceeded 0.6%, the fish died within 42 days, whereas those reared in 0.2% sludge remained alive and healthy during the trial period. The body and the gills of the dead fish were covered by a veil-like film which looked like coagulated mucus and was formed by the heavy metal ions from the sludge reacting with some constituents of the mucus secreted by the gill. The histopathological symptoms of the various organs further demonstrated that internal injury in liver and kidney was also an important feature of the intoxicants as well as external damage, especially the particles observed around the gills. It was concluded that the optimum concentration of sludge to any species of fish should be determined by testing a series of concentrations before using it as a supplementary fish feed or fish pond fertilizer.     

One-step, non-denaturing purification method of carp (Cyprinus carpio) vitellogenin

A new single-step purification procedure was developed to purify carp (Cyprinus carpio) vitellogenin (VTG), from estradiol-treated carp plasma. This method was performed by high performance liquid weak anion-exchange chromatography, using a discontinuous elution gradient of NaCl (0-0.5 M, steps of 12.5 mM/4 min). SDS and native-PAGE analysis, of treated-fish plasma and purified solution, showed the appearance of a 370 kDa phospholipoprotein, composed of two 130 kDa monomers, with all VTG characteristics. The sequencing of a 130 kDa monomer confirmed that it was carp VTG. Consequently, this procedure is a rapid method, permitting high quantities of non-denatured carp VTG to be obtained.     

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.