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Fatty acid (FA) composition of the fillet and the intestinal content of dwarf common carp (Cyprinus carpio carpio) living in Lake Hévíz was determined in wintertime collected samples and results were compared to widespread literature data on carp. Fillet FA profile of the thermally adapted (28 °C) Hévíz dwarf carps differed from profiles originated from divergent culture and feeding conditions in the overall level of saturation. Fillet myristic acid proportions largely exceeded all literature data in spite of poor dietary supply. Fillet fatty acid results indicate the effects of thermal adaptation (high saturation level) and the correlative effects of feed components rich in omega-3 fatty acids, with special respect to docosahexaenoic acid. With the application of discriminant factor analysis the Hévíz sample was accurately differentiated from the literature data on carp fillet fatty acid profile, mostly based on C14:0, C18:1 n9, C18:2 n6, C20:1 n9 and C20:4 n6 FAs. In summary, fillet FA profile suggested thermal adaptation, location specificity and the ingestion of algal and bacterial material.

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Experiments were carried out on sperm cryopreservation of two European percid fish species, the pikeperch (Sander lucioperca) and the Volga pikeperch (S. volgensis) . Two experiments were conducted on pikeperch sperm. In the first, the effects of three extenders (Glucose, KCl, Sucrose) and two cryoprotectants (dimethyl-sulfoxide: DMSO, methanol: MeOH) were tested on motility and fertilization. In the second, the effects of two dilution ratios (1: 1, 1: 9) and two cryoprotectants (DMSO, MeOH) on hatching were investigated. In the experiment on Volga pikeperch the suitability of using cryopreservation for fertilization was investigated. In the first experiment on pikeperch the highest post-thaw motility (28 ± 21%) and fertilization rate (43 ± 12%) was found with DMSO as cryoprotectant in combination with Glucose extender. In the second, the highest hatch rate (41 ± 22%) was observed with MeOH as cryoprotectant and 1: 1 sperm dilution ratio, however no significant difference was found among the results. In the experiment on Volga pikeperch hatch rates with cryopreserved sperm (60 ± 2%) did not significantly differ from the control (60 ± 6%). Contamination of sperm with urine seems to be a key problem in the success of sperm cryopreservation of these species.

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Experiments were carried out on the sperm cryopreservation of artificially induced eels. The effects of several extenders and two cryoprotectants on the motility of spermatozoa were investigated. The highest post-thaw motility was observed with the combination of Tanaka's extender and DMSO as cryoprotectant. Further dilution after thawing resulted in complete loss of motility in samples frozen in presence of DMSO while sperm frozen with methanol as cryoprotectant retained its motility after further dilution.

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Acta Biologica Hungarica
Authors: T. Müller, T. Molnár, A. Szabó, E. Yamaha, Éva Járási, M. Bercsényi, A. Specziár, B. Urbányi, and R. Romvári

The present study aimed in vivo tracking of maturation of male eel by computed tomography (CT). Additionally, individually monitored testes sizes were correlated with the conventionally used external maturity indicators (i.e. eye and nose indexes) in order to test and improve their usefulness at individual level. Testes could be clearly identified with the CT from the end of the third week of hCG administration routinely used to induce maturation in fish. The volume of testes increased exponentially during hormone treatment, and by the end of the sixth week of maturation procedure all males produced motilable spermatozoa. Present results prove that testes size can noninvasively be monitored with CT from maturity level where testes size rich 3000 mm3 volume. Eye and nose indexes are in close correlation with testes volume and thus can also be effectively used to monitor maturaty level of male eel, but preferably only at stock level. However, due to their high individual variability, these indexes can be applied only with caution at individual level and should be supplemented with other noninvasive techniques such as CT.

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Thiols are known to play crucial roles in plant defense responses, e.g. against pathogens. In the present study, the efficiency of these molecules was evaluated in regenerated Cucurbita pepo L. subsp. pepo var. styriaca Greb. plants in response to compatible Zucchini yellow mosaic virus infection. Thiol contents were modulated by applying the cysteine precursor L-2-oxothiazolidine-4-carboxylic acid (OTC) to callus cells. Cytological and biochemical methods were used for determination of glutathione within callus cells and leaves of plants regenerated via somatic embryogenesis. Reduced glutathione levels (GSH) significantly increased in callus cells one week after 1.0 mM OTC treatment by about 56% and resulted in enhanced GSH levels throughout the investigation period of 13 weeks. Three weeks after ZYMV infection untreated plants regenerated from callus culture exhibited stunted growth forms, yellowing, mosaic and blistering on the leaves whereas 68% of 1.0 mM OTC pretreated regenerated plants were characterized by a complete absence of symptoms. Treatment with OTC stimulated the synthesis, conversion and translocation of thiols during advanced ZYMV infection. Compared to untreated infected leaves, a graduate increase in cysteine (cys) and γ-glutamyl-cysteine (γ-glucys) contents was measured in 0.5 mM and 1.0 mM OTC treated older leaves, whereas total glutathione (tGSH) decreased significantly after infection. In OTC treated younger leaves cys and tGSH concentrations remained at control levels and were unaffected by ZYMV. In contrast, OTC treatment caused a dramatic induction of γ-glucys, up to 191% in younger infected leaves. The results show that altered levels of thiols by OTC were accompanied by enhanced tolerance against ZYMV, suppression of ZYMV induced symptoms as well as delayed symptom development.

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Acta Biologica Hungarica
Authors: Á. Staszny, Enikő Havas, R. Kovács, B. Urbányi, G. Paulovits, Dóra Bencsik, Á. Ferincz, T. Müller, A. Specziár, Katalin Bakos, and Zs. Csenki

Intraspecific morphological variability may reflect either genetic divergence among groups of individuals or response of individuals to environmental circumstances within the frame of phenotypic plasticity. Several studies were able to discriminate wild fish populations based on their scale shape. Here we examine whether the variations in the scale shape in fish populations could be related to genetic or environmental factors, or to both of them. In the first experiment, two inbred lines of zebrafish, Danio rerio (Hamilton 1822) reared under identical environmental conditions were compared. Secondly, to find out what effect environmental factors might have, offsprings were divided into two groups and reared on different diets for 12 weeks. Potential recovery of scales from an environmental effect was also assessed. Experimental groups could successfully be distinguished according to the shape of scales in both experiments, and the results showed that both genetic and environmental factors may notably influence scale shape. It was concluded that scale shape analysis might be used as an explanatory tool to detect potential variability of environmental influences impacting genetically homogeneous groups of fish. However, due to its sensitivity to environmental heterogeneity, the applicability of this technique in identifying intraspecific stock membership of fish could be limited.

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