Biology subjects

Kaspar, V.

Publications and source records attributed to Kaspar, V..

4 recordsLinked to original sources

bioRxiv2022

Developmental changes of opsin gene expression in ray-finned fishes (Actinopterygii)

Fish often change their habitat and trophic preferences during development. Dramatic functional differences between embryos, larvae, juveniles and adults also concern sensory systems, including vision. Here we focus on the photoreceptors (rod and cone cells) in the retina and their gene expression profiles during the development. Using comparative transcriptomics on 63 species, belonging to 23 actinopterygian orders, we report general developmental patterns of opsin expression, mostly suggesting an increased importance of the rod opsin (RH1) gene and the long-wavelength sensitive (LWS) cone opsin, and a decreasing importance of the shorter wavelength sensitive cone opsin throughout development. Furthermore, we investigate in detail ontogenetic changes in 14 selected species (from Polypteriformes, Acipenseriformes, Cypriniformes, Aulopiformes and Cichliformes), and we report examples of expanded cone opsin repertoires, cone opsin switches (mostly within RH2) and increasing rod:cone ratio as evidenced by the opsin and phototransduction cascade genes. Our findings provide molecular support for developmental stage-specific visual palettes of ray-finned fishes and shifts between, which most likely arose in response to ecological, behavioural and physiological factors.

evolutionary biology↗

bioRxiv2021

Who is the best surrogate for germ stem cell transplantation in fish?

Surrogate reproduction technology in fish has potential for aquaculture as well as endangered species preservation and propagation. Species with some unfavourable biological characteristics for culturing such as a late maturation or a large body size are ideal candidates for surrogate reproduction using smaller and faster-maturing host. One of the general prerequisites for the successful surrogacy and the pure donor-derived gamete production is the sterility of the host. Various sterilization methods have been developed and used in fish surrogacy; however, a direct comparison of available methods is missing. Such a knowledge gap hinders choice for the surrogate in various fish species, including those in high commercial demand such as tuna or sturgeons, where is a particular limitation from the point of the live material availability and difficulty to perform a high throughput assessment of different surrogates. Yet, large sturgeons or tuna species are one of the most prominent candidates for surrogacy. Zebrafish was utilized in this study as a model species to answer whether and to which extent different sterilization strategies can affect the surrogacy. Germ cell-depleted recipients (produced using knockdown of dead end gene), triploid recipients, and zebrafish x pearl danio hybrid recipients were tested as they represent the most frequently used types of surrogates. Spermatogonia isolated from vas::EGFP transgenic strain were intraperitoneally transplanted into swim-up 5-day old zebrafish. Transplantation success, survival, gonadal development, and reproductive output of the fish was analyzed. Germ cell-depleted recipients with empty gonads were identified as the most convenient among tested sterilization methods considering surrogacy induction success and reproductive output. The present study stands as significant aid for selecting suitable surrogates in various fish species.

cell biology↗

bioRxiv2020

Production of common carp donor-derived offspring from goldfish surrogate broodstock

BackgroundCommon carp is the fourth most-produced species in worldwide aquaculture. Significant efforts are invested in breeding and preservation of genetic integrity of this important species. However, maintaining carp gene bank in situ can be considered as demanding due to its big body size. Recent progress in reproductive biotechnologies in fish allows improving some unfavourable characteristics of a target species using surrogate reproduction. Germ stem cells (gamete precursors) from one species are transplanted into different surrogate species with small body size. After maturation, surrogates are producing donor-derived progeny. Efficient protocols for cryopreservation of carp male and female germ stem cells have been developed lately. Thus, the next logical goal was to assess the potential of goldfish surrogate to produce donor-derived gametes of common carp after intraperitoneal transplantation of testicular cells. ResultsHigh transplantation success was achieved when 44% of the surviving goldfish produced pure donor-derived gametes of common carp. More importantly, both viable eggs and sperm giving rise to pure common carp progeny were produced, witnessing sustainability of the presented method. Donor-derived identity of the offspring was confirmed by genotyping and typical phenotype corresponding to the donor species. Reproductive performance of chimeras was similar to goldfish controls. Assessment of gamete characteristics showed that the size of donor-derived eggs is between control carp and goldfish eggs. Interestingly, flagellum length in donor-derived spermatozoa was comparable to common carp flagellum and significantly shorter than goldfish flagellum. ConclusionsIn this study, we succeeded in the production of pure common carp progeny from surrogate goldfish recipients transplanted intraperitoneally by testicular germ cells. Here we reported production of viable eggs between most distant species up to date. Good reproductive performance of goldfish germline chimeras gives a promising prospect for further analysis about the long-term reproductive performance of surrogates, recovery of cryopreserved germ cells or production of monosex stocks. Presented technology is ready to ease needs for carp breeds preservation and their recovery using many times smaller goldfish surrogates.

cell biology↗

bioRxiv2018

Cryopreservation and transplantation of common carp spermatogonia

Common carp (Cyprinus carpio) is one of the most cultured fish species over the world with many different breeds and plenty of published protocols for sperm cryopreservation, however, data regarding preservation of gonadal tissue and surrogate production is still missing. A protocol for freezing common carp spermatogonia was developed through varying different factors along a set of serial subsequent experiments. Among the six cryoprotectants tested, the best survival was achieved with dimethyl sulfoxide (Me2SO). In the next experiment, a wide range of cooling rates (0.5-10 {degrees}C/min) and different concentrations of Me2SO were tested resulting in the highest survival using 2 M Me2SO and cooling rate of -1 Q59 A When testing different tissue sizes and incubation times in the cryomedium, the highest viability was observed when incubating 100 mg tissue fragments for 30 min. Finally, sugar supplementation did not yield significant differences. When testing different equilibration (ES) and vitrification solutions (VS) used for needle-immersed vitrification, no significant differences were observed between the tested groups. Additionally, varied exposure time to VS did not improve the vitrification outcome where the viability was 4-fold lower than that of freezing. The functionality of cryopreserved cells was tested by interspecific transplantation into sterilized goldfish recipients. The exogenous origin of the gonads in goldfish recipients was confirmed by molecular markers and incorporation rate was over 40% in both groups at 3 months post transplantation. Results of this study can serve as an alternative way for long-term preservation of germplasm in carp which can be recovered in a surrogate recipient.

bioengineering↗