Hungarian-Belgian collaboration

Between February 13th and 20th, Ákos, Gergő and Dr. Zoltán Bokor visited Belgium and France in the frames of the Hungarian-Belgian (Wallonian) bilateral project. The objectives of the visit were to conduct experiments on the quality of sperm as well as endocrine status of pikeperch males following hormonal induction. In this project we collaborate with our partners Prof. Patrick Kestemont and Dr. Robert Mandiki of the University of Namur in Belgium. This time, we were also joined by our old friends Dr. Daniel Żarski and Dr. Jarosław Król of the University of Warmia and Mazury in Olsztyn, Poland who spent a month in France working on an AQUAEXCEL2020 mission. The sampling went as planned and hopefully the results of the work will be published.

Ákos, Gergő, Sébastien Baekelandt, Zoltán Bokor, Imen Ben Ammar, Daniel Żarski, Jarosław Król and Robert Mandiki


New paper accepted in The Journal of Visualized Experiments (JoVE)

A new paper in collaboration with our collegues from the Polytechnic University of Valencia was accepted for publication in The Journal of Visualized Experiments (JoVE), entitled 'Handling and treatment of male European eels (Anguilla anguilla) for hormonal maturation and sperm cryopreservation'

J.G. Herranz-Jusdado, E. Kása, T. Kollár, V. Gallego, D.S. Peñaranda, C. Rozenfeld, L. Pérez, Á. Horváth, J.F. Asturiano The Journal of Visualized Experiments (JoVE). In press.

During the last years, several research groups have been working on the development and improvement of new protocols for the European eel handling and maturation. As of yet, weekly injections of human chorionic gonadotropin (hCG) have proved to maturate males after just 5-6 weeks of treatment, producing high volumes of high-quality sperm during several weeks. In addition, sperm cryopreservation protocols using different extenders, cryoprotectants and cooling and thawing times have been previously described for European eel. Here, we show that Tanaka´s extender solution can be directly used for fertilization or for cryopreservation, making unnecessary the usage of different types of solutions and dilutions. Furthermore, the use of methanol as a cryoprotectant makes this protocol easy to use as methanol has low toxicity and does not activate the sperm. The sperm does not need to be cryopreserved immediately after the addition of the cryoprotectant, and it can be used long after being thawed. Moreover, sperm motility is still high after thawing although it is lower than that of fresh sperm. The aim of this work is to show the best available protocol for European eel handling, maturation, and sperm cryopreservation.


Work in Lillafüred

On December 14-15th, Jelena, Zoran and Ákos went to Lillafüred to conduct experiments on the transplantation of brown trout spermatogonia to triploid rainbow trout larvae. Triploid rainbow trout eggs were sent by our colleagues working at Pisciculture Expérimentale Inra des Monts d’Arrée (Peima) in Bretagne, France. We managed to transplant spermatogonia into approximately 300 recipients which will be grown to sexual maturity at the Lillafüred Trout Farm. We also had the chance to examine the gonads of adult individuals of the hybrid tiget trout, a potential recipient. As always, we are grateful to György Hoitsy, his family and all his colleagues who did their best to assist us in spite of the usual Christmas fish sale that took all their energies. We are looking for a continued collaboration in the coming year!

Examination of brown trout gonads before isolation of spermatogonia

Triploid rainbow trout larva waiting for transplantation

Zoran conducting transplantation in field conditions


New paper accepted in The Journal of Visualized Experiments (JoVE)

A new paper with the first authorship of Zoran Marinović was accepted for publication in The Journal of Visualized Experiments (JoVE), entitled `Cryopreservation of zebrafish spermatogonia by whole testes needle immersed ultra-rapid cooling`

Marinović Z., Lujić J., Kása E., Csenki Zs., Urbányi B., Horváth Á. 2017. Cryopreservation of zebrafish spermatogonia by whole testes needle immersed ultra-rapid cooling. The Journal of Visualized Experiments (JoVE). In press. DOI: 10.3791/56118

Current trends in science and biotechnology lead to creation of thousands of new lines in model organisms thereby leading to the necessity for new methods for safe storage of genetic resources beyond the common practices of keeping breeding colonies. The main purpose of this study was to adapt the needle immersed vitrification (NIV) procedure to cryopreserve whole zebrafish testes. Cryopreservation of early-stage germ cells by whole testes NIV offers possibilities for the storage of zebrafish genetic resources, especially since after transplantation they can mature into both male and female gametes. Testes were excised, pinned on an acupuncture needle, equilibrated in two cryoprotective media (equilibration solution containing 1.5 M methanol and 1.5 M propylene glycol; and vitrification solution containing 3 M dimethyl sulfoxide and 3 M propylene glycol) and plunged into liquid nitrogen. Samples were warmed in a series of three consequent warming solutions. The main advantages of this technique are (1) the lack of spermatozoa after digestion of warmed testes thus facilitating downstream manipulations; (2) ultra-rapid cooling enabling the optimal exposure of tissues to liquid nitrogen therefore maximizing the cooling and reducing the required concentration of cryoprotectants, thereby reducing their toxicity; (3) synchronous exposure of several testes to cryoprotectants and liquid nitrogen; and (4) repeatability demonstrated by obtaining viability of above 50% in five different zebrafish strains.


Work on pikeperch

In the period between 13th and 15th November Jelena and Zoran were at National Agricultural Research and Innovation Centre, Research Institute for Fisheries and Aquaculture in Szatvas. They worked together with Uroš Ljubobratović, Research Fellow at that Institute. The main aim of this visit was testing different protocols for conservation of genetic material of pikeperch.  


Master thesis defense of Jovana Lovren

One of our students from Serbia, Jovana Lovren, successfuly finished and defended her Master thesis `Cryopreservation of spermatogonia in Common carp (Cyprinus carpio L.)` at the Department of Biology and Ecology of the Faculty of Sciences at the University of Novi Sad in Serbia. She spent with us more than one month working in our laboratories as well as on field in Hungary and Slovenia. We are  proud on our collaboration and want to congratulate Jovana.
Ákos and Jelena together with dr Desanka Kostić and dr Nebojša Andrić were members of the defense committee, while dr Željko Popović was the supervisor.

Jovana during defense
Committee members (from the left: Jelena Lujić, Ákos Horváth, Desanka Kostić, Željko Popović and Nebojša Andrić )
MSc Jovana Lovren
Jovana with Željko and Jelena after defense


4th World Congress of Reproductive Biology

During September, Jelena and Zoran participated at the 4th World Congress of Reproductive Biology organized by the Society for Reproduction and Development and partners in Okinawa, JAPAN.
We presented results of our collaborative work with colleagues from Japan, Czech Republic and Slovenia on two posters: 

Marinović Z., Lujić J., Kása E., Li Q., Yoshizaki G., Franěk R., Kašpar V., Urbányi B., Horváth Á. 2017. Cryopreservation of spermatogonial stem cells from cyprinid fish species. [Abstract] 4th World Congress of Reproductive Biology (WCRB 2017); 27-29.9.2017; Okinawa, Japan. P6-103.

Lujić J., Marinović Z., Sušnik-Bajec S., Kása E., Urbányi B., Horváth Á. 2017. Cryopreservation and xenotransplantation of germ stem cells of European salmonid species. [Abstract] 4th World Congress of Reproductive Biology (WCRB 2017); 27-29.9.2017; Okinawa, Japan. P6-48.

Okinawa Convention Center
Okinawa Convention Center main hall
Reproductive technology and stem cells session
Poster session
Jelena with her poster
with our dear colleague Somfai Tamás from 
NARO Institute of Livestock and Grassland Science, Tsukuba, Japan
Zoran with his poster
View from Okinawa Convention Center