New paper published in PeerJ

A new paper with the authorship of our alumna Ági and Ákos has been published in the journal PeerJ on the results of our brown trout project.

Ősz Á, Horváth Á, Hoitsy G, Kánainé Sipos D, Keszte S, Sáfrány AJ, Marić S, Palkó C, Tóth B, Urbányi B, Kovács B. (2018) The genetic status of the Hungarian brown trout populations: exploration of a blind spot on the European map of Salmo trutta studies. PeerJ 6:e5152 https://doi.org/10.7717/peerj.5152

Abstract

Background
Analyses of the control region sequences of European brown trout populations’ mitrochondrial DNA have revealed five main evolutionary lineages (Atlantic, Danubian, Mediterranean, Adriatic, Marble) mostly relating to the main water basins; however, the hybridization between lineages were increasingly reported. Due to the hydrogeography of Hungary, wild populations should theoretically belong to the Danubian lineage, however, this has not been verified by genetic studies.

Methods
In our study multiple molecular marker sets (mitochondrial sequence, microsatellites, PCR-RFLP of nuclear markers and sex marker) were used to investigate the genetic composition and population genetics of the brown trout populations in two broodstocks, six wild streams in Hungary and one Serbian population.

Results
The admixture of Atlantic and Danubian lineages in these populations, except the Serbian population with pure Danubian origin, was observed by control region sequences of mitochondrial DNA and PCR-RFLP markers in the nuclear genome, and one unpublished Danubian haplotype was found in Hungarian populations. A sex-specific marker revealed equal gender ratio in broodstocks and Kemence stream, whereas in other wild streams the proportion of female individuals were less than 50%. Structure and principal component analyses based on the alleles of microsatellite loci also revealed overlapping populations, however the populations were still significantly different from each other and were mostly in Hardy-Weinberg equilibrium.

Discussion
Stocking and migration can have a significant genetic impact on trout populations of wild streams, however there are no guidelines or common practices for stocking of small streams in Hungary, thus the genetic background of these populations should be considered when developing conservation actions.

New paper accepted for publication in Animal Reproduction Science

A new paper with Ákos as a co-author was accepted for publication in Animal Reproduction Science. The work was a collaborative effort of our Polish colleagues of the University of Warmia and Mazury in Olsztyn and the Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences in Olsztyn and members of our Department. Thanks to our Polish friends for making this possible.

Effect of urine contamination on semen quality variables in Eurasian perch Perca fluviatilis L.

Jarosław Król, Daniel Żarski, Gergely Bernáth, Katarzyna Palińska-Żarska, Sławomir Krejszeff, Artur Długoński, Ákos Horváth

Animal Reproduction Science 2018, 197:240-246

Abstract

The objectives of the present study were to determine values for semen quality variables in the Eurasian perch (i.e., osmolality of seminal plasma as well as sperm motility characteristics analyzed with CASA system) in response to (1) the method of milt collection (stripping or catheterization) and (2) experimental contamination of catheterized semen with urine (0%, 5%, 10%, 20%, 30% and 50% of contamination). Additionally, the effect of short-term chilled storage of experimentally contaminated semen (during the 24 h post semen collection period) on motility characteristics was investigated. Use of a typical stripping procedure resulted in about 5%–10% contamination of semen with urine, what is much less compared with other species. Markedly lesser values of straight line velocity (VSL) and consequently less linearity of spermatozoa movement (LIN) in perch semen, however, occurred as a result of stripping (46 ± 4 μm/s and 38 ± 4% for VSL and LIN, respectively), when compared to sperm collected by catheterization (87 ± 5 μm/s and 77 ± 2% for VSL and LIN, respectively), indicate that even a 10% contamination of semen with urine may have negative effects on quality. Exposure of semen to urine resulted in a significant dose-dependent decrease in the percentage of motile spermatozoa (MOT) and both velocity variables (VSL and VCL). Amount of urine contamination also affected MOT, VCL, VSL and LIN value during short-term storage. In conclusion, it is important to avoid semen contamination by urine when using the stripping procedure in the Eurasian perch, either for controlled reproduction or sperm preservation.

7th International Workshop on the Biology of Fish Gametes

The 7th International Workshop on the Biology of Fish Gametes will be held in Rennes, France on 2nd-6th September, 2019. Please use this link to receive updates and latest news on the developments related to this event: https://workshop.inra.fr/fishgametes2019/
Looking forward to seeing everyone in Rennes next year!

New paper accepted for publication in Aquaculture

Another paper has been accepted for publication in Aquaculture with the authorship of members of our team. The paper is the results of a collaborative work by the team of Prof. Juan F. Asturiano (Polytecnical University of Valencia, Spain), that of Dr. Catherine Labbé (INRA, Rennes, France) and us. Thanks to both teams for making this possible.

Comparison of European eel sperm cryopreservation protocols with standardization as a target

J.G. Herranz-Jusdado, V. Gallego, M. Morini, C. Rozenfeld, L. Pérez, E. Kása, T. Kollár, A. Depincé, C. Labbé, Á. Horváth, J.F. Asturiano (In press: https://doi.org/10.1016/j.aquaculture.2018.09.006)

Abstract

The critical situation of the European eel (Anguilla anguilla) has urged the development of sperm cryopreservation protocols for reproduction in captivity and cryobanking. In the last years, two research groups have developed their own protocols in Spain and Hungary with positive results, but difficult to compare.

Here, a series of experiments were conducted to test the quality of thawed sperm after using both protocols, determining which of them produce the best results and aiming for standardization. The quality of thawed sperm was assessed by studying the motility and kinetic values of thawed sperm from both cryopreservation protocols using a computer-assisted sperm analysis (CASA-Mot) system. In addition, a viability analysis was performed using flow cytometry to test if the cryoprotectants or the freezing-thawing process led to a reduction in spermatozoa survival. Furthermore, since during cryopreservation the sperm was treated with methylated cryoprotectants (DMSO or methanol) that may induce epigenetic changes in the sperm DNA (cytosine methylation) and could affect the offspring, we conducted a luminometric methylation assay (LUMA) to study the DNA methylation levels induced by both protocols.

In this work, all the above-mentioned parameters were analyzed in fresh and frozen-thawed sperm samples. Our results showed that thawed sperm samples from both protocols presented lower sperm motility and velocity, and lower percentage of live cells than those shown in fresh sperm samples. Furthermore, sperm samples from the methanol based protocol showed significantly higher motility, velocity and percentage of live spermatozoa than the same sperm samples treated with the DMSO based protocol. In addition, the DMSO based protocol induced a hypomethylation of sperm DNA compared to fresh samples whereas the methanol based protocol did not alter sperm DNA methylation level. Our results indicate that the methanol based protocol is a more suitable protocol that preserves better the motility and genetic qualities of the European eel sperm.

Timi's PhD defense

Yesterday, Timi has defended her PhD dissertation entitled "Development of a toxicological test system based on fish sperm analysis". Timi has started her studies at Szent István University in 2008 and has been working under the supervision of Ákos during her BSc and MSc studies. She has enrolled in the PhD School of Animal Husbandry in 2014 and has been working on the development of a model toxicology test system using the sperm of zebrafish and common carp under the supervision of Ákos and our colleague Dr. Zsolt Csenki-Bakos. The committee praised Timi's work and achievements and the final score of her defense was 100%. Congratulations, Timi, we are proud of you.

Timi presenting her results

Timi answering questions of the committee, the two proud supervisors in the foreground

Timi with the proud supervisors