Participation at the Aquaculture Europe 2022 meeting in Rimini

Between September 27-30th, Ákos with several other colleagues of the Institute of Aquaculture and Environmental Safety of MATE has participated at the Aquaculture Europe 2022 meeting organized by the European Aquaculture Society. Aquaculture Europe is the largest annual gathering of scientists and professionals working in the field of fisheries and aquaculture in Europe. This year's meeting was organized in the beautiful city of Rimini, a popular resort on the Adriatic coast of Italy. For our team its special significance is that in 2023 we will take activ
e part in the organization of this meeting in Vienna, Austria and this year's conference gave us a better insight into the operational aspects of hosting an event of this size.

Ákos had the privilege of co-chairing the section "Broodstock and Hatchery Management" with Nicolas Mace. He also gave a presentation entitled "Cryopreservation and transplantation of germline stem cells in salmonids: What have we learned?"

New paper published in Aquaculture

 Thanks to the efforts of our colleague Dr. Uroš Ljubobratović, a new publication came out in Aquaculture with Nevena, Zoran and Ákos as co-authors. This was a collaborative effort between our group and that of Uroš, both belonging to the Institute of Aquaculture and Environmental Safety as well as Dr. Sylvain Milla of the University of Lorraine in France. Enjoy!

Uroš Ljubobratović, Nevena Kitanović, Sylvain Milla, Zoran Marinović, Georgina Fazekas, Jelena Stanivuk, Zoltán Nagy, Ákos Horváth. 2022. Predicting population's oocyte maturation competence and evaluating individual's latency time using in vitro oocyte maturation in pikeperch (Sander lucioperca). Aquaculture, Volume 562, 15 January 2023, 738851. https://doi.org/10.1016/j.aquaculture.2022.738851

Abstract

Artificial reproduction of pikeperch (Sander lucioperca) is characterized by the unpredictability of latency time (LT) as well as the variability of egg quality depending on the time of hormonal stimulation. To predict latency time and thus enhance fertilization outcomes, the present study evaluated whether in vitro maturation techniques could be utilized to assess the status of oocyte maturation competence (OMC). Oocyte samples from nine pond-reared females originating from the Czech Republic (CZECH) and 12 intensively cultured females originating from river Körös (HAKI) were catheterized at the time of hormonal stimulation and cultured in L15 medium supplied with 100 ng/mL of DHP. The stage of final oocyte maturation (FOM) was monitored both in vivo and in vitro and egg quality features were evaluated. HAKI group was characterized by larger oocytes at the time of stimulation (934.4 ± 32.9 μm vs. 860.0 ± 22.7 μm), as well as higher embryo survival (77.7 ± 10.4% vs 53.5 ± 28.8%), suggesting that artificial reproduction was performed prematurely for CZECH group. Oocytes from HAKI fish displayed a higher share of maturing oocytes (41.4 ± 9.1% vs. 13.8 ± 17.6%) and in all samples germinal vesicle breakdown was noticed, while in the CZECH group it was so only in oocytes of one fish. With respect that all fish ovulated after the gonadoliberin stimulation, gonadotropin-regulated OMC is assumed. A correlation was found between the in vivo and in vitro LTs in the HAKI group only (r = 0.791, P = 0.002), indicating a certain autonomy of ovarian follicle of other parts of the physiological axis after completed OMC. The in vitro techniques show great promise for practical application in hatcheries to evaluate the aptness for hormonal stimulation on both individual and population levels.

Participation at the Gametes Worskhop in Gdańsk

 Nevena and Ákos along with Gergely Bernáth, Borbála Nagy, Tamás Szabó and Uroš Ljubobratović (colleagues from the Institute of Aquaculture and Environmental Safety at MATE) participated at the 8th International Workshop on the Biology of Fish Gametes organized on September 20-23 in Gdańsk, Poland by our friends from the Institute of Animal Reproduction and Food Science of the Polish Academy of Science in Olsztyn. We had a wonderful time discussing science and progress in fish gamete research and of course this was also a good opportunity to see old friends and make new ones. Nevena and Ákos both gave oral presentations and Nevena presented two posters. The venue of the next workshop was al
so decided, thus, everybody is welcome to León, Spain in 2022

Congratulations and Thanks to Andrzej Ciereszko, Daniel Żarski, Sylwia Judycka, Joanna Nynca, Mariola Dietrich and everybody at the host institute for the professional organization and memorable time together.

We are also super-proud of Nevena who won the prize for the best poster presented at the meeting. Congratulations, Nevena!

Zoran's project funded

We have received wonderful news today. Zoran's proposal entitled "Surrogate production of genome edited fish" submitted this February to the Young Researcher Excellence Program of the OTKA projects by the National Research, Technology and Innovation Agency of Hungary has been funded (you can access the announcement in Hungarian here: https://nkfih.gov.hu/.../nkfi-alap/tamogatott-projektek-fk22). We are looking forward to a continued successful research work. Congratulations, Zoran!

Conference in Croatia

 On June 19-24th, Nevena, Betti and Ákos participated at the 57th Croatian and 17th International Symposium of Agriculture in Vodice, Croatia. We were accompanied by our colleagues Dr. Balázs Kovács of the Department of Molecular Ecology, Jelena Stanivuk, PhD student under the joint supervision of Ákos and Dr. Uroš Ljubobratović working at the Research Center of Fisheries and Aquaculture (HAKI), Dr. Mária Kovács-Weber of the Institute of Animal Husbandry Sciences and Dr. István Lehoczky of the National Biodiversity and Gene Conservation Center. A
s usual, the conference had a session on Fiheries, Game Management and  Beekeeping with Ákos co-chairing a part of the morning session on Fisheries together with Dr. Zvjezdana Popović Perković of the University of Split. The conference was an excellent opportunity to strengthen our collaboration with Croatian colleagues and to become acquainted with each other’s work.

The works presented by the members of our team:

Ákos Horváth, Bernadett Pataki, Zoran Marinović, Béla Urbányi: Inherited cryoresistance of fish sperm: is it real? 

Nevena Kitanović, Zoran Marinović, Bernadett Pataki, Balázs Csorbai, Gergely Mészáros, Ákos Horváth: Optimization of Leibovitz L-15 media for in vitro maturation of common carp ovarian follicles 

Bernadett Pataki, Ádám Staszny, Gergely Mészáros, Nevena Kitanović, András Ács, Árpád Hegyi, József Molnár, Balázs Csorbai, Béla Urbányi, Ákos Horváth: Morphological changes in common carp (Cyprinus carpio) progeny induced by the use of cryopreserved sperm 

Jelena Stanivuk , Zoran Marinović, Uroš Ljubobratović, Ákos Horváth: Fixation of histological specimens of juvenile testicular tissue of pikeperch (Sander lucioperca) and Eurasian perch (Perca fluviatilis) 

Ákos giving his presentation

Nevena giving her presentation

Betti presenting her results

Ákos co-chairing the session with Dr. Zvjezdana Popović Perković 

The team after the session (photo by O. Barić)

Another paper published in Aquacultrue Reports

 A new paper has been published in the journal Aquaculture Reports in collaboration with our colleagues from the Department of Animal Science, Biotechnical Faculty, University of Ljubljana and the Lillafüred Trout Farm in Hungary. Enjoy!

Marinović, Z., Lujić, J., Sušnik Bajec, S., Djurdjevič, I., Snoj, A., Hoitsy, G., Urbányi, B., Horváth, Á., 2022. Evaluation of triploid rainbow trout Oncorhynchus mykiss as a surrogate parent for brown trout Salmo trutta m. fario and grayling Thymallus thymallus. Aquac. Reports 24, 101163. https://doi.org/10.1016/j.aqrep.2022.101163

Abstract:

Surrogate production through germline stem cell (GSC) transplantation is becoming a very promising technology in species management and ex situ species conservation. In the present study, we have evaluated if the triploid rainbow trout is a suitable surrogate parent for the production of other salmonid gametes. In three independent trials conducted in two countries, we have transplanted brown trout and grayling GSCs into triploid rainbow trout larvae as recipients. Two months after transplantation, dissection of recipients displayed that both spermatogonial (SSCs) and oogonial (OSCs) stem cells of both species were able to colonize recipient gonads. After three years of rearing, neither male nor female recipients displayed signs of gametogenesis progression. Species-specific (for both donor and recipient species) amplification of mtDNA control region on the other hand displayed a presence of donor-derived germ cells within recipient gonads. This indicated that even though donor cells were able to colonize recipient gonads, they remained in a dormant or quasi-dormant state, and did not progress with gametogenesis. This study displays that the rainbow trout is not a suitable recipient for all salmonid species, and that careful selection of recipients is a crucial step in developing the surrogate production technology.

Work in Croatia

Within the frames of the Hungarian-Croatian bilateral project, between May 9-13th we have enjoyed the hospitality of Ana Gavrilović, her team from the University of Zagreb as well as the staff of the Aquarium Pula in Pula, Croatia. The goal of the project is to develop cryopreservation methods for the gametes and larvae of various bivalvian species found in the Adriatic sea including the European flat oyster (Ostrea edulis), the mediterranean scallop (Pecten jacobaeus) and possibly for the critically endangered noble pen shell (Pinna nobilis) whose populations have been severely affected by the pathogen Haplosporidium pinnae. Ákos and Zoran were accompanied by Dr. Balázs Kovács and Réka Balogh of the Department of Molecular Ecology of our institute who plan to carry out molecular studies on the species. We wish to thank all our Croatian friends and colleagues for their hospitality and help! Within the frames of the Hungarian-Croatian bilateral project, between May 9-13th we have enjoyed the hospitality of Ana Gavrilović, her team from the University of Zagreb as well as the staff of the Aquarium Pula in Pula, Croatia. The goal of the project is to develop cryopreservation methods for the gametes and larvae of various bivalvian species found in the Adriatic sea including the European flat oyster (Ostrea edulis), the mediterranean scallop (Pecten jacobaeus) and possibly for the critically endangered noble pen shell (Pinna nobilis) whose populations have been severely affected by the pathogen Haplosporidium pinnae. Ákos and Zoran were accompanied by Dr. Balázs Kovács and Réka Balogh of the Department of Molecular Ecology of our institute who plan to carry out molecular studies on the species. We wish to thank all our Croatian friends and colleagues for their hospitality and help!

Zoran and Ákos demostrating the two-pipette dilution technique

Réka and Balázs taking samples from oyster for molecular analysis

Balázs and Zoran analyzing the survival of cryopreserved oyster larvae

The team in front of the famous Arch of Sergii in Pula

Preparing for Aquaculture Europe 2023

 Last week, Ákos and Professor Béla Urbányi, director of the Institute of Aquaculture and Environmental Safety has attended the meeting hosted by the European Aquaculture Society (EAS) to initiate preparation for the most important annual EAS event, the Aquaculture Europe conference in 2023. The meeting will be held in Vienna, Austria and is scheduled for September, 2023. The main theme of the meeting will be balanced diversity in aquaculture development.

As Vienna lies in the heart of Central Europe, the preparatory activities also involved the participation of several parties, including colleagues from Austria, Hungary, Czech Republic and Germany. Participants discussed various issues related to the organization, including the venue, program, conference sessions, student involvement and distribution of tasks to various committees. Béla has assumed the role of program co-chair of the meeting while Ákos is a member of the Local Organizing Committee charged with publicizing the event on various platforms. 

We would like to thank Alistair Lane, Mario Stael and John Cooksey for the organization and we are looking forward to our continued collaboration.

Return to Slovenia

After a 5-year hiatus, we finally were able to return to beautiful Slovenia! Thanks to the invitation by our colleague, Dr. Simona Sušnik Bajec of the Department of Animal Science, Biotechnical Faculty, University of Ljubljana we were able to collaborate with her and her PhD student Tjaša Kodela on the reproduction of the grayling (Thymallus thymallus). Betti and Ákos spent 3 days working at the hatchery of the Fisheries Research Institute of Slovenia in Kobarid, stripping sperm and eggs and checking sperm quality using CASA. Grayling spawning has drastically reduced during the last decade in the Soča river and the Institute puts a considerable effort into the culture and repopulation of this fish species. Hopefully, we will be able to assist Tjaša in her scientific studies.

Grayling males waiting to be stripped

Ákos and Betti in the hatchery

Ákos and Tjaša at work

New paper published in Aquaculture Reports

A new paper with Betti's first authorship has been published in Aquaculture Reports. Enjoy: 

Bernadett Pataki, Ákos Horváth, Gergely Mészáros, Nevena Kitanović, András Ács, Árpád Hegyi, József Molnár, Balázs Csorbai, Béla Urbányi. 2022. Adjustment of common carp sperm concentration prior to cryopreservation: Does it matter? Aquaculture Reports Volume 24, June 2022, 101109 https://doi.org/10.1016/j.aqrep.2022.101109 

Abstract 

Absorbance and computer-assisted sperm analysis (CASA) was used to assess the sperm concentration of common carp (Cyprinus carpio) as an alternative to hemocytometer counting. Also the effect of different sperm concentrations on post-thaw sperm parameters and fertilizing capacity were tested. The main goal of the research was to find out whether the tested methods are suitable for fast measurement of sperm concentration and if the pre-setting of sperm concentration before cryopreservation offers any advantages over dilution of sperm to a given ratio. A linear relationship of sperm concentration measured with CASA (N = 12) as well as sperm absorbance assessed with a microplate reader with spectrophotometry module (N = 18) with sperm concentration counted in a Bürker-Türk type hemocytometer was established. For cryopreservation, 4 sperm concentrations were used (0.5; 1; 2; 4 × 109 spermatozoa per ml) and compared to dilution to a ratio of 1:9. A significant positive relationship was found between the absorbance and sperm concentration (p < 0.0001, r2 = 0.8289) as well as between immotile cell concentration measured with CASA and that counted in a hemocytometer (p < 0.0001, r2 = 0.8559). No significant main effect of sperm concentration was found on any post-thaw motility parameters measured by CASA with the exception of linearity (p = 0.0056). Sperm concentration had a significant main effect (p = 0.0156) on the fertilizing capacity of sperm samples diluted to various concentrations prior to cryopreservation. Only the highest concentration of 4 × 109 spermatozoa per ml (66 ± 6% fertilization) showed a significant difference (p = 0.0121) in comparison to the pre-set dilution ratio (49 ± 5% fertilization). The results show that both spectrophotometry and CASA are suitable for the assessment of common carp sperm concentration and that maximizing sperm concentration prior to cryopreservation results in higher fertilization.