Transplantation in Lillafüred vol. 2

On March 9-10th, we continued our transplantation work at the Lillafüred Trout Farm. As previously, spermatogonia and oogonia were isolated from rainbow trout and transplanted into newly hatched tiger trout recipients. What made this occasion specias was that this time we enjoyed the company of two students from the University of Novi Sad in Serbia, Nataša Cvetković and Jovana Lovren. They participate in a training stay in Gödöllő and came with us to Lillafüred. Both were very enthusiastic to learn about trout and transplantation. As always, our gratitude goes to Mr. György Hoitsy, the manager of the Lillafüred Trout Farm whose hospitality was overwhelming.
Teamwork in the isolation of rainbow trout gonads

Jovana and...
...Nataša during transplantation

Carp spawning

Our common carp broodstock has finally matured. The first batch of eggs was stripped from the fish on March 7th. The eggs were fertilized with freshly stripped sperm and the first larvae hatched on March 10th. The broodstock is now ready for experiments – at least a year ahead of its sexual maturation in pond farms. It can be stimulated to spawn year-round and larvae can be produced for experiments whenever we want. Thanks to Balázs Csorbai for his assistance in the induced spawning.

Eggs are stripped from a female common carp of the broodstock


New paper accepted in Reproduction in Domestic Animals

A new paper with the first authorship of Gergely Bernáth was accepted for publication in Reproduction in Domestic Animals:
"Chilled and post-thaw storage of sperm in different goldfish types"
The effective storage time of sperm after stripping (for 48 hours in 6 hours intervals) and after thawing (for 6 hours in 2 hours intervals) in Black moor, Oranda and Calico goldfish types was investigated. Variations in sperm density were also measured in all lines. The efficiency of a sperm cryopreservation method formerly developed for common carp was recorded in all three goldfish lines. Motility parameters ((pMOT, %), curvilinear velocity (VCL, µm/s) and straightness (STR, %)) of Black moor sperm did not decrease significantly during 48 hours of storage. A significant reduction in the Oranda type compared to the fresh control was observed in pMOT after 42 (23±2%) and VCL after 36 (94±12 µm/s) hours (pMOT 84±5%, VCL 150±11 µm/s). In the Calico type, pMOT decreased significantly already after 18 (42±26%) and VCL after 6 (105±8µm/s) hours (fresh: pMOT 92±5%, VCL 151±6 µm/s). A high pMOT immediately following thawing was measured in Oranda (46±12%) and Calico (55±15%) types, whereas a reduced pMOT was recorded in Black moor (24±19%). In Calico, pMOT showed a significant reduction after 6 hours (19±11%) in comparison to the initial value, with no changes observed in VCL and STR. None of the parameters changed in the Black moor and Oranda types. Evidence was found that different goldfish lines have different sperm quality and characteristics. Further studies can investigate the possible effects of chilled and post-thaw storage on the fertilizing capacity of sperm in the Black moor, Oranda and Calico goldfish types.


Practical class in our fish system

Master students of our University had part of practical classes of the subject `Thesis preparation, experimental design and scientific writing` in our recirculating fish rearing system. 


Transplantation in Lillafüred

On February 15-16th, Jelena, Zoran and Ákos spent two days at the Lillafüred Trout Farm conducting experiments on the isolation of rainbow trout spermatogonia and their transplantation into tiger trout recipients. Tiger trout is a hybrid of brown trout (Salmo trutta m. fario) and brook trout (Salvelinus fontinalis) and is supposed to be sterile, making it an ideal recipient for transplantation experiments. The transplantation experiments went according to plans, spermatogonia were injected into 205 tiger trout larvae. We are grateful to the manager of the trout farm, Mr. György (Gyuri) Hoitsy and his son Márton (Marci) Hoitsy for their hospitality and assistance during the work and for rearing the fish for our experiments.

Dissection of rainbow trout for isolation of gonads

Obvious difference between ovaries (left) and testes (right) of juvenile rainbow trout

Team work: Zoran is checking viability of isolated cells while Jelena is preparing the next sample

Transplantation of spermatogonia into tiger trout recipients

And now it is Marci's turn to try transplantation

Tiger trout larvae in anesthesia


New paper accepted in Zoological Studies

A new paper with the first authorship of Jelena was accepted for publication in Zoological Studies, entitled "Phylogeographic Identification of Tench Tinca tinca (L., 1758) (Actinopterygii: Cyprinidae) from the Northern Balkans and Adjacent Regions and its Implications for Conservation"

The tench, Tinca tinca, is an endangered freshwater fish species in the Balkans. However, there are no management and conservation strategies developed for this species so far. In order to be able to develop such strategies, we first determined the phylogeographic identity of 70 tench individuals from four countries (Serbia, FYRO Macedonia, Hungary and Croatia) by PCR-RFLP analyses of two nuclear markers (Act and RpS7) and one mitochondrial marker (Cytb). All makers enabled the identification of two major geographic clades of tench (Western and Eastern), while nuclear markers additionally enabled the identification of hybrids between the two clades. Based on the mitochondrial marker Cytb, tench populations can be separated into two distinct areas: areas north of the Danube River with the dominant Western origin, and areas south of the Danube River with the dominant Eastern origin. Data obtained for the Act gene demonstrated Eastern origin for most individuals (88.23%) while data obtained for the RpS7 gene demonstrated mixed origin with a high percentage of hybrids. The presence of high numbers of individuals with Western alleles for the RpS7 gene in areas south of the Danube may indicate a natural invasion of this phylogroup. According to these results, areas north and south of the Danube are identified as two main management units. Additionally, we identified the rare western haplotype W2 based on the Cytb marker which clearly indicated human-aided dispersals of tench in the investigated region and since some individuals with W2 origin were cultured, attention must be given to the genetic structure and identity of the introduced individuals, whether during introduction or reintroduction since biological and ecological consequences of the hybridization between the two major clades are still unknown. Finally, we propose and discuss management and conservation strategies for tench of both management areas.


Kick-off meeting of the new GOODFISH project

The kick-off meeting of the GINOP-2.3.2.-15-2016-00025 GOODFISH project was held in Gödöllő on February 6th, 2017 with the attendance of all Consortium Members as well as prospective subcontractors. Attendees discussed the scientific activities that lie ahead, issues related the the budget and consortium agreement. The project is an unprecedented collaborative effort by the leading aquaculture research and education institutions in Hungary and targets the complex development of the culture conditions and management of genetic resources of three autochthonous farmed fish species, the wels catfish, common carp and the pikeperch. For more details, please consult the Projects menu of this blog. We are looking forward to a successful collaboration with our partners!

Attendees of the meeting


New paper accepted in PLOS ONE

A new paper with the shared first authorship of Tímea Kollár was accepted for publication in PLOS ONE, entitled Stimulus-triggered enhancement of chilling tolerance in zebrafish embryos.



Cryopreservation of zebrafish embryos is still an unsolved problem despite market demand and massive efforts to preserve genetic variation among numerous existing lines. Chilled storage of embryos might be a step towards developing successful cryopreservation, but no methods to date have worked.


In the present study, we applied a novel strategy to improve the chilling tolerance of zebrafish embryos by introducing a preconditioning hydrostatic pressure treatment to the embryos. In our experiments, 26-somites and Prim-5 stage zebrafish embryos were chilled at 0°C for 24 hours after preconditioning. Embryo survival rate, ability to reach maturation and fertilizing capacity were tested.


Our results indicate that applied preconditioning technology made it possible for the chilled embryos to develop normally until maturity, and to produce healthy offspring as normal, thus passing on their genetic material successfully. Treated embryos had a significantly higher survival and better developmental rate, moreover the treated group had a higher ratio of normal morphology during continued development. While all controls from chilled embryos died by 30 day-post-fertilization, the treated group reached maturity (~90–120 days) and were able to reproduce, resulting in offspring in expected quantity and quality.


Based on our results, we conclude that the preconditioning technology represents a significant improvement in zebrafish embryo chilling tolerance, thus enabling a long-time survival. Furthermore, as embryonic development is arrested during chilled storage this technology also provides a solution to synchronize or delay the development.


Student recruitment trip to Novi Sad

On Monday, January 23rd, Eszti, Jelena, Zoran and Ákos visited Dr. Željko Popović at the Department of Biology and Ecology of the Faculty of Sciences at the University of Novi Sad in Serbia. The purpose of the visit was to meet with two candidates for the Hungarian state scholarship "Stipendium Hungaricum" and discuss with them the possibilities of pursuing their PhD in Hungary. It was agreed that the two candidates (Nataša Cvetković and Jovana Lovren) will visit our lab in Hungary in March for a one-month training in fish biotechnology. We enjoyed the wonderful hospitality of our Serbian colleagues and looking forward to a continued collaboration.

Meeting with the candidates at the Department of Biology and Ecology (from left to right: Dr. Željko Popović, Jelena, Nataša Cvetković, Jovana Lovren, Zoran, Eszti and Ákos)


Air spawning trial in Tolmin

Ákos has participated in a trial of air spawning of marble trout (Salmo marmoratus) at the fish farm of the Angling Club of Tolmin conducted by Dr. Radosław Kowalski and his team – Beata Cejko, Sylwia Judycka and Michał Blitek – from the Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences in Olsztyn, Poland on January 15-18th, 2017. Dr. Kowalski has applied and perfected this technology in many salmonid species previously and it worked fine on the marble trout, as well (see the video below). Air spawning is claimed to be less stressful for the fish than manual stripping, results in higher egg quality and more complete removal of eggs from the body cavity.
In addition to the air spawning trial, experiments were conducted on the cryopreservation of marble trout sperm. Information was exchanged by the Slovenian and Polish partners on the production of fish products such as trout caviar and trout pâté. Finally, we enjoyed the company of our Polish partners at our department in Gödöllő, too. We conducted experiments on the cryopreservation of common carp sperm which was also a good test of our carp broodstock for sexual maturity.
We would like to thank our partners in Slovenia and Poland for this truly international cooperation. We very much hope to continue this work in the future.

Radek preparing marble trout caviar while Robi from the Angling Club of Tolmin is taking notes
Happy customers tasting marble trout caviar
The team on the famous Napoleon bridge in Kobarid 
High expectations from cryopreserved common carp sperm in Gödöllő

Radek showing their well-equipped laboratory-van

our collegues from the Department of Aquaculture listening to Radek's presentation

sightseeing in Budapest (Michał, Eszti, Radek, Sylwia, Beata, Jelena, with the statue of the Hungarian poet Attila József)


Happy Holidays!

The end of the year is nearing. It has been a very exciting one for our group with successes, exciting travels, lots of work, nice publications but also sad losses. We are looking forward to the new year with hope for more interesting discoveries, meetings with fellow scientists and friends and new collaborations. We wish everyone Merry Christmas and a very Happy New Year of 2017!


Colleagues from Slovenia visited our lab

Dr Simona Sušnik-Bajec and Dr Aleš Snoj from the Biotechnical Faculty of the University of Ljubljana, Slovenia, spent one week in our as a part of our join project regarding transplantation of  spermatogonia among salmonid species. This time we checked success of transplantation which we did during autumn. 

Simona preparing everything for work
Preparing the sample for checking
Aleš collecting samples for molecular analysis 
Team work
Cute company


Broodstock review

On Friday December 9th, we reviewed our common carp broodstock. Fish were harvested from their tank, anesthetized, their PIT tags were scanned and then their standard length and weight was measured and their sex determined. The goal of this review was to check their growth since June as well as to determine which individual is ready for spawning. Most fish have doubled their size and males already have sperm. We hope to attempt the first spawning in February.

Our colleague Balázs and Zoran are harvesting fish from the tank

The sex of fish was checked by the presence of sperm

All fish are weighed and measured before sex determination


Colleagues from Vodnany visited our lab

Dr Vojtěch Kašpar and Roman Franěk from the Faculty of Fisheries and Protection of Waters, University of South Bohemia, Czech Republic, spent one week in our lab for joint research on carp testis cryopreservation.  

 preparing cryomedia

 cutting tissue

more cutting

weighting of tissue pieces

one happy bunch with controlled rate freezer