12/07/2020

Our group's appearance in the Global Aquaculture Advocate


 An interview was published in the online journal Global Aquaculture Advocate with the participation of Professor Goro Yoshizaki of the Tokyo University of Marine Science and Technology and Zoran from our team. The article discusses the newest developments in the culture, cryopreservation and transplantation of germline stem cells (GSC) of fish. Enjoy!


9/18/2020

New paper published in Aquaculture Reports

 A new paper with Betti and Ákos as coauthors was published in the journal Aquaculture Reports. Enjoy!

Ljubobratović, U., Péter, G., Demény, F., Kugyela, N., Horváth, Á., Pataki, B., Horváth, Z., Jakabné Sándor, Z. & Rónyai, A. (2020). Reproductive performance in virgin pikeperch (Sander lucioperca L.) females fed different dietary levels of arachidonic acid with respect to the duration of spawning induction. Aquaculture Reports, 18, 100430.

Abstract

Pikeperch (Sander lucioperca) is a species of significant importance for the further development of intensive aquaculture, what makes the total control over species’ reproductive cycle a high priority task. The present study aimed to assess the effect of arachidonic acid (AA) dietary enrichment on the reproductive performance in virgin females (two-years-old; individual weight 1.0 ± 0.2 kg) kept in fully controlled conditions with respect to different time of hormonal application. Two groups of breeders, ARA (fed AA enriched diet) and CTRL (fed control feed), were reared in two separated tanks of the recirculation system over the course of seven months. Five, six, and seven months after the start of trial, batches of five pairs of breeders (in total 15 pairs per each feeding group) from each group were hormonally treated. Ovulations occurred after six and seven months (oocyte diameter range 912−1030 μm), and samples of dry eggs were taken for the analysis of fatty acid profiles. Among the parameters of reproductive success, the embryo survival was significantly affected by the diet, while induction duration affected latency time only. The CTRL group females showed overall higher embryo survival across both reproduction occasions (p = 0.028) than group fed AA enriched diet (35.7 ± 17.1 % and 18.6 ± 13.6 % in CTRL and ARA group, respectively). A significant accumulation of AA was found in ARA group eggs in both reproduction batches. Virgin pikeperch breeders appear to keep at least one month plasticity towards the duration of spawning induction in controlled conditions and optimal oocyte diameter range for artificial reproduction is between 900−1000 μm. Levelling dietary AA with eicosapentaenoic acid during the entire photothermal protocol negatively altered the egg quality.

New paper published in Dose-Response

 A new paper with Ákos' coauthorship was published in the journal Dose-Response. Enjoy!

Kerekes, F., Kollár, T., Gazsi, G., Kása, E., Urbányi, B., Csenki-Bakos, Z., & Horváth, Á. (2020). Investigation of Fertilizing Capacity of Zebrafish (Danio rerio) Sperm Exposed to Heavy Metals. Dose-Response. https://doi.org/10.1177/1559325820919597 

Abstract

The objective of our study was to investigate the effects of heavy metals on the fertilizing capacity of exposed zebrafish sperm, on embryonic survival, and on occurrence of embryonic deformities following fertilization with exposed sperm. It is important to test heavy metals because they are well-known pollutants. Sperm of externally fertilizing species can get in contact with pollutants found in aquatic environment. Zebrafish sperm, despite its advantages, has seldom been used in in vitro toxicological studies and no reports are available regarding the fertilizing capacity of exposed sperm. Zebrafish sperm was stripped and exposed to concentrations of the tested heavy metals (Zn2+, Cd2+, Cr3+, Cu2+, Ni2+, Hg2+, As3+) for 30 or 120 minutes. Calculated half-maximal effective concentration (EC50) values do not differ significantly from those calculated for motility for any of the tested heavy metals, which means fertilization rate can indicate the toxicity of the given substance following exposure of sperm. Thus, its application as in vitro toxicological end point is reasonable. The survival of embryos and embryonic development have not been affected by the exposure of spermatozoa, which means all alterations in spermatozoa caused by heavy metals have been expressed before 24 hours post fertilization.

New paper published in JoVE

 A new paper with Ákos' coauthorship was published in the Journal of Visualized Experiments (JoVE). Enjoy!

Csenki, Z., Horváth, Á., Bock, I., Garai, E., Kerekes, F., Vásárhelyi, E., Kovács, B., Urbányi, B., Mueller, F., Bakos, K. Using Tg(Vtg1:mcherry) Zebrafish Embryos to Test the Estrogenic Effects of Endocrine Disrupting Compounds. J. Vis. Exp. (162), e60462, doi:10.3791/60462 (2020).

Summary

Present here is a detailed protocol for the use of zebrafish embryos Tg(vtg1: mCherry) for the detection of estrogenic effects. The protocol covers the propagation of the fish and treatment of embryos, and emphasizes the detection, documentation, and the evaluation of fluorescent signals induced by endocrine disrupting compounds (EDC).


7/30/2020

New paper published in Cryobiology

A new paper with Ilija's first authorship was published in the journal Cryobiology.

Šćekić, I., Marinović, Z., Lujić, J., Müller, T., Kitanović, N., Urbányi, B., Horváth, Á., 2020. A novel strategy for conservation of European eel (Anguilla anguilla) genetic resources: Cryopreservation of ovarian stem cells. Cryobiology 95, 151–156. https://doi.org/10.1016/j.cryobiol.2020.03.009

Enjoy!

Abstract:

The aim of this study was to develop short- and long-term preservation protocols for European eel ovarian stem cells (OSCs) through hypothermic storage and cryopreservation of ovarian fragments that will assist in current conservation programs of this critically endangered species. Firstly, a freezing procedure was developed by testing different cryomedia and technical aspects of freezing. Utilization of 1.5 M of dimethyl sulfoxide (Me2SO), 0.1 M glucose and 1.5% BSA yielded optimal OSCs survival. Additionally, equilibration of 50-mg ovarian fragments for 30 min and plunging into lN2 at −80 °C displayed the highest OSC viability. Different cooling rates ranging from −1 to −40 °C/min did not significantly affect OSC viability when thawing in a 10 °C water bath. In addition, application of needle-immersed vitrification (NIV), combining ES3 (1.5 M PG and 1.5 M Me2SO) with VS3 (3 M PG and 3 M Me2SO) yielded the highest viability rates. Finally, hypothermic storage (4 °C) of ovarian fragments and ovarian cell suspensions displayed favorable viability of ~90% after 48 h of storage and ~65% after 72 h of storage. The development of OSC preservation methods presents an onset of further development of germline stem cell (GSC) manipulation techniques in this species. Cryopreservation of OSCs can enable a continuous supply of cells for either transplantation or in vitro cell culture thus enabling new and improved management and conservation strategies for this endangered species.

5/12/2020

New book chapter published

A chapter was published with the authorship of Ákos and Dr. Béla Urbányi in the book entitled Reproduction in Aquatic Animals: From Basic Biology to Aquaculture Technology edited by Dr. Manabu Yoshida and Dr. Juan F. Asturiano and published by Springer. The book is the final result of the activities of the COST Action FA1205 AQUAGAMETE as well as the International Symposium on “AQUAGAMETE: Reproduction of Aquatic Animals” held in the Joint Meeting of the 22nd International Congress of Zoology and the 87th meeting of the Zoological Society of Japan, which was held from 14th to 19th November 2016 in Okinawa, Japan. The authors wish to thank Dr. Yoshida and Dr. Asturiano for taking care of the book and making it happen. Enjoy!

Horváth Á., Urbányi B. (2020) Chapter 15 Sperm Cryopreservation of Aquatic Species. In: Yoshida M., Asturiano J. (eds) Reproduction in Aquatic Animals. Springer, Singapore, https://doi.org/10.1007/978-981-15-2290-1_16

Cryopreservation of fish sperm is feasible, and methods have been developed for several hundred species. The procedure includes the collection of sperm and assessment of its quality, dilution in suitable extenders, addition of cryoprotectants, loading into freezing devices, cooling, storage, thawing, and finally post-thaw use of sperm. An alternative to traditional freezing methods is the vitrification of sperm which is promising primarily in smaller model fish species. A wide variety of protocols are available in the literature; however, in spite of the significant progress made by the scientific community, commercial application of fish sperm cryopreservation is still very limited.

New paper published in Fish and Shellfish Immunology

A new paper with Ákos' co-authorship was published in the journal Fish and Shellfish Immunology. The paper was a result of a collaboration among Dr. Daniel Żarski of the Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, the team of Dr. Patrick Kestemont of the University of Namur in Belgium, Dr. Pascal Fontaine of the University of Lorraine in France and the Department of Aquaculture of Szent István University. It was also financed by the Hungarian-Walloon bilateral project TÉT_14_VL1-2015-0001. Enjoy!

Żarski, Daniel ; Ben Ammar, Imen ; Bernáth, Gergely ; Baekelandt, Sébastien ; Bokor, Zoltán ; Palińska-Żarska, Katarzyna ; Fontaine, Pascal ; Horváth, Ákos ; Kestemont, Patrick ; Mandiki, Syaghalirwa N.M. Repeated hormonal induction of spermiation affects the stress but not the immune response in pikeperch (Sander lucioperca). Fish and Shellfish Immunology 101 pp. 143-151. , 9 p. (2020)

Hormonal induction of spermiation, previously reported to be immunogenic in fishes, is a common hatchery practice in pikeperch, Sander lucioperca. The aim of the present study was to investigate the effects of repeated induction of spermiation in pikeperch, following application of either human chorionic gonadotropin (hCG) or salmon gonadoliberine analogue (sGnRHa) on sperm quality indices as well as on immune and stress response. Mature males of pikeperch (n = 7 per group) were stimulated twice with five days between injections of either hCG (hCG; 500 IU kg−1), sGnRHa (sGnRHa; 50 μg kg−1) or NaCl (control group; 1 ml kg−1) to assess spermatozoa motility with a computer-assisted sperm analysis (CASA) system. During second sampling, blood plasma was sampled for humoral innate immune (peroxidase and lysozyme activities, ACH50), stress (cortisol, glucose) and endocrine (testosterone) markers. In addition, the head kidney was dissected to assay the expression of several immune genes (such as il1, c3, hamp, tnf-α and lys genes). The results indicate that hormonal treatment significantly increased sperm production. Sperm sampled after the hormonal treatment maintained its quality throughout the study, regardless of the sampling time. However, it appears that the application of hCG induced elevated cortisol and glucose plasma levels compared to the control group. Almost all immune markers, except the relative expression of hepcidin (hamp gene), were unaffected by the two hormones applied. The results showed that the induction treatment of spermiation processes in pikeperch resulted in an important physiological stress response for which the intensity varied according to the hormonal agent used. However, this stress response (more profound following application of hCG) was weakly associated with innate immune functions. On the other hand, a significant negative correlation between the expression of several important immune markers (peroxidase activity, relative expression of c3 and il1 genes) and sperm quality indices indicates significant involvement of immune status on sperm quality. The results obtained shed light on immune-system- induced modifications to sperm quality. The data presented here highlight the need for careful revision of broodstock management and selection practices where welfare status as well as individual predispositions of fish to cope with the stress should be taken under the consideration.

5/11/2020

Conference in Croatia

The 55th Croatian & 15th International Symposium on Agriculture was held on February 16-21st, 2020, in Vodice, Croatia. Ákos has given a presentation entitled:
Ákos Horváth, Jelena Lujić, Zoran Marinović, Márton Hoitsy, Béla Urbányi, György Hoitsy:
The use of the hybrid tiger trout as a recipient for interspecific transplantation of spermatogonia

Ákos giving the presentation (photo by R. Balogh)

A trip to Poland

Although the COVID-19 pandemic has anchored us to Hungary without much opportunities to travel, on February 7-9th, thus before the outbreak we (Nevena, Zoran and Ákos) managed to visit our friend, Dr. Daniel Żarski of the Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences. We also had the opportunity to meet Dr. Andrzej Ciereszko, head of Gamete and Embryo Biology group of the institute and members of his team. Our mission was to bring around 100 Atlantic salmon juveniles to Hungary for scientific experiments on their gonads. The fish arrived successfully after a 14-hour journey.

We wish to thank Daniel, Andrzej, Sylwia and all our friends in Poland for their help!

Strengthening the Polish-Hungarian-Serbian friendship at the dinner (photos by D. Żarski)


1/15/2020

Collaboration with Cornell University

In June-August, 2019 we had the pleasure of hosting Logan Goddard, undergraduate student of the College of Agriculture and Life Sciences (CALS) of Cornell University on a 8-week stay in our lab. Logan has participated in the CALS Global Fellows Program and took part in experiments on cryopreservation of eel gonads and carp sperm. He gave an account of his experiences at the 2019 Global Fellows Program Showcase in November 2019. You can read more about this program here: https://cals.cornell.edu/news/global-fellows-program-celebrates-first-year-undergraduate-research-experiences-hungary