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.
Fish Reproduction Group (Hungarian University of Agriculture and Life Sciences, Institute of Aquaculture and Environmental Safety, Department of Aquaculture)
2/18/2017
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.
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| Dissection of rainbow trout for isolation of gonads |
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| Obvious difference between ovaries (left) and testes (right) of juvenile rainbow trout |
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| Team work: Zoran is checking viability of isolated cells while Jelena is preparing the next sample |
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| Transplantation of spermatogonia into tiger trout recipients |
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| And now it is Marci's turn to try transplantation |
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| Tiger trout larvae in anesthesia |
2/17/2017
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"
Abstract
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.
Abstract
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.
2/08/2017
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!
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| Attendees of the meeting |
2/07/2017
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.
Abstract
Background
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.
Methods
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.
Results
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.
Conclusions
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.
Abstract
Background
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.
Methods
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.
Results
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.
Conclusions
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.
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