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Research

Molecular biology

This thematic group has been organized in 2007 in the laboratory operated by support from the Department of Fish Culture and the Regional University Center of Excellence of Szent István University (KÖRET). The objective of the thematic group is to put the collected theoretical and practical knowledge at the disposal of Hungarian fish farming and fish biology research. Thus, several molecular biology topics are covered by the group, including the assessment of population genetics and genetic values of natural and farmed fish stocks, for environmental, aquacultural, economic and scientific purposes in Hungarian and international cooperation. Our long-term research objectives include the search for molecular markers suitable for the study of genetic background and sex-related DNA markers and genes in cyprinid and siluriform fish as well as species with increasing importance in intensive systems (e.g.: Sander lucioperca, Perca fluviatilis, etc.) that can later be used for studies of the genetic structure of fish. Methods used and developed during our work can further be used in aquaculture research and genetic improvement for example in modernization and improvement of qualification criteria in broodstocks.. Another important part of the work carried out by the thematic group is molecular biology support of environmental and toxicology research conducted on fish at the Department of Fish Culture, including immunology, DNA, RNA and protein analyses. All apparel necessary for this work can be found in the laboratory of KÖRET (incubators, thermostats, centrifuges, ultrasound homogenizers, automatic sequencer, PCR and quantitative PCR thermal cyclers, gel electrophoresis and gel documentation systems, sterile cabinets, fermentors, photometers, refrigerators, autoclaves, freeze-dryers, Toxalert and Microtox devices, etc.).

 

Pond aquaculture research

The Department of Fish Culture in cooperation with the companies Cikk Halas Halastavi Kft and Iszapfaló Kft has initiated a large-scale pond farm experiment in 2007. The objective of this study was the reduction of soft mud that represents a constant problem in pond farms using biological methods. A mixture of Effective Microorganisms (EM) was used for the reduction of soft mud. This mixture contains photosynthesizing bacteria, lactic acid bacteria, yeast, Actinomycetes, fermenting fungi in of various species and in an adequate portion. The depth of soft mud was measured with a deep-sea Sonar device before and after the treatment. Beside the treated pond, a control pond was studied in both years of investigations to allow comparisons of results. As a result of the two-year treatment the amount of soft mud has decreased by 57,834 m3. Beside soft mud reduction, composition of the mud, algal and planktonic composition, fish body composition and quality, blood parameters, weight gain and gonadal development was also investigated. According to the results, a significant improvement was observed in the treated pond in comparison to the control pond.

 

Histology research

The Department owns a histology laboratory since 2006. The laboratory is equipped for histological processing and staining of animal (in particular fish) organs, tissues as well as the analysis of samples. This allows accurate observation of diseases or developmental defects in experimental stocks or individuals, organ malformations resulting from toxicology tests conducted in our zebra fish facility as well as the tracing of annual gonad cycle in fish through changes in the gonad tissues. Sections suitable for microscopy analysis are made at the laboratory from organs removed from dissected experimental individuals. Samples are most often stained with hematoxylin and eosin but sometimes other special protocols such as specific stains or cryosection are required. Special staining is also applied when specific experimental results are evaluated (accumulation of heavy metals in the organism, tracing of glycogen synthesis, etc.). Digital images are made of histological sections and stored for use at lectures, seminars, publications and other purposes.

 

Zebrafish recirculation system

Zebrafish (Danio rerio) is currently one of the most popular vertebrate experimental animals in several areas of science. Scientists working with zebrafish hold several meetings annually, their articles are published in leading scientific journals almost on a daily basis and an increasing number of zebrafish facilities is built each year. Processes of the living organism including ageing, cancer, understanding of the malfunctions of the hematopoietic system and different organs as well as genetic determination of diseases is greatly facilitated by investigations made on zebrafish. Our department owns its zebrafish laboratory since 2006 which is currently the only facility of its type not only in Hungary but in the entire Central European area. Primarily toxicology tests are carried out in the laboratory. Toxicology investigations are conducted for partner institutions, units, research groups and companies including 96-hour acute tests and chronic accumulation tests. Beside classical mortality parameters changes in behavior can also be monitored in the laboratory. In cooperation with the histology laboratory of our department histology sections can also be made of experimental fish and analyzed which greatly contributes to the complete understanding of the physiological effect of a chemical compound or active ingredient. Other experiments conducted at the laboratory: - oocyte transplantation and investigation of other possibilities of oocyte manipulation - sperm cryopreservation - development of a nano method for fructosamine detection in order to facilitate diabetes research - application and development of genetic and molecular biology methods The laboratory provides sufficient amount of healthy fish for different experiments, represents an opportunity for students to prepare their work for the Scientific Conference of Students and their thesis and functions as a reference laboratory.

 

Laboratory works related to fatty acid analysis

The Department of Fish Culture of Szent István University has been cooperating with several fish farms on the development of pond fish farming technology. Quality of carp meat and fat content of carp stocks grown on cereals are the factors determining the market value of fish. Joint experiments have been carried out together with the laboratory of the National Institute for Food Safety and Nutrition (OÉTI) since 2005 and this cooperation was formalized in the form of an agreement in the summer of 2008. Several experiments can be conducted at the analytical laboratory of OÉTI and the results are evaluated at the Department.

 

Joint chemical investigations:

- Determination of free fatty acids with gas chromatography;

- Composition and ratio of saturated, mono- and poly-unsaturated fatty acids;

- Detection of trans fatty acids in fish fillets;

- Detection of fat content;

- Lipid peroxidation parameters (malonaldehyde and conjugated dienes);

- Microelement content determination (Zn, Cu, Mg, Fe);

- Full body composition (crude protein, crude fat, dry matter and ash).

 

Analytical investigations of fish are conducted according to the Hungarian Standards. Essential microelement content of samples is determined using the AAS protocol while lipid peroxidation indicators (MDA, conjugated dienes) are analyzed using a spectrophotometric (Perkin–Elmer Lambda 25 UV/VIS) protocol at the Lipid Department of the Institute. The volume of fatty acids is measured in a capillary column GC system following esterification with methyl ester. The capillary column gas chromatograph which is one of the most advanced ones in the country is able to identify 37 different fatty acids in a single run including cys- and trans- versions. Investigations include analyses of fresh, frozen and processed products.

 

Cryopreservation of fish sperm

The cryopreservation of fish sperm has been one of the major research activities of the Department for more than 15 years. The Department is fully equipped with labware and apparel required for the cryopreservation of sperm, including storage and shipping dewars, liquid nitrogen containers, straws and other miscellaneous equipment. Research on cryopreservation follows 3 main directions at the department: 1. commercialization of sperm cryopreservation and promotion of its application to aquaculture practice; 2. development of cryopreservation protocols for the sperm of several fish species including threatened and endangered ones (e.g. Cyprinus carpio, Silurus glanis, Sander lucioperca, Polyodon spathula, Acipenser ruthenus, Carassius carassius); 3. investigations related to the process of freezing and the damages attributed to cooling and thawing of cryopreserved material.