Comparison of ovarian cycles of Hungarian riverine fish species representing different spawning strategies

Investigations on the ovarian cycle of fish species that inhabit Hungarian rivers are necessitated by both environmental and economic reasons. The objective of our research was to explore new fundamental knowledge concerning the ovarian cycle of the white bream (Blicca bjoerkna, Linnaeus, 1758), barbel (Barbus barbus, Linnaeus, 1758), orfe (Leuciscus idus, Linnaeus, 1758) and nase (Chondrostoma nasus, Linnaeus, 1758). Histological investigation of ovaries and determination of proportions of oocytes in different stages of development is an appropriate method for the description of spawning characteristics of these species. Our results show that the GSI value for all four investigated species starts to increase at the end of summer and reaches its maximum before spawning. In the barbel and white bream, the presence of oocytes in the stage of cortical alveoli and the heterogeneous size of oocytes in the stage of vitellogenesis in the pre-spawning period indicate that barbel and white bream are multiple spawners. In contrast, in the orfe and nase, the absence of oocytes in the stage of cortical alveoli and the homogeneous size of cells in the stage of vitellogenesis indicate that orfe and nase are single spawners

Transplantacija spermatogonija kao nova metoda u akvakulturi i konzervaciji riba

Poslednjih godina, primena primordijalnih germinativnih ćelija (primordial germ cells - PGCs) i spermatogonijalnih stem ćelija (spermatogonial stem cells - SSCs) riba je postala veoma značajna zbog razvoja metode transplantacije ovih ćelija. Od kada su Brinster i Avarbock (1994) razvili ovu metodu, ona se uspešno koristi za čuvanje genetskog materijala ugroženih vrsta i u stvaranju novih transgenih linija kod miševa i domaćih životinja. Uvođenje ove metode kod riba predstavlja značajan napredak u oblasti reproduktivne biotehnologije, akvakulture, konzervacione biologije, kao i u razvoju novih transgenih linija različitih vrsta riba. Osnovu ove metode predstavlja transplantacija germinativnih ćelija (PGC, SSC) iz donorskog organizma u organizam primaoca. Najinteresantnija u tom smislu je upotreba nediferenciranih spermatogonija A tipa (Aund) koje imaju sposobnost samoobnavljanja ali i proizvodnje ćelija kasnijih faza spermatogeneze. Postoji takođe nekoliko specifičnih osobina SSC koje ih čine pogodnim za transplantaciju: (1) sposobnost da kolonizuju testis primaoca odakle produkuju donorsku spermu, (2) mogućnost da se nakon transplantacije u primaocu muškog pola razviju u spermatogonije, a u primaocu ženskog pola u oogonije i (3) mogućnost genske manipulacije sa ciljem produkcije transgenih riba (Lacerda i sar., 2010). Prilikom transplantacije SSC, posebna pažnja mora biti usmerena ka izboru vrste donora i primaoca. Najbolje bi bilo da donor i primalac ne budu filogenetski previše udaljeni, kao i da primalac ima kratak reproduktivni ciklus i manje dimenzije tela kako bi ekonomski bio pogodniji za gajenje. Donorska vrsta je obično vrsta za koju postoji određneni interes, bilo ekonomski, naučni ili konzervacioni. Tokom transplantacije, kompatibilnost između primaoca i donora može biti ograničavajući faktor u uspehu samog procesa. U najgorem slučaju, primalac, usled imune reakcije, može u potpunosti odbaciti transplantirano tkivo ili ćelije. To je najčešće slučaj ukoliko se vrši transplantacija SSC iz odraslog donora u odraslog primaoca. Kako bi se izbegao problem izazvan transplantacijom između dve odrasle jedinke, koristi se prednost ontogenije primaoca, posebno ontogenije njegovog imunog sistema, tako što se za primaoca koriste embrioni ili larve. Ovi stadijumi kod riba nemaju razvijen imuni sistem niti diferencirane T-ćelije (Takeuchi et al., 2003; Yoshizaki et al., 2011) te s toga nemaju mehanizam pomoću kojeg bi odbacili donorsko tkivo. Takođe, lakše je blokirati razvoj endogenih primordijalnih germinativnih ćelija kod larvi, nego ukloniti SSC iz već razvijenih gonada kod odraslog donora. Pored odabira odgovarajuće vrste donora i primaoca, neophodno je na pravi način izolovati specifične ćelije koje treba da budu transplantirane. Ovaj proces je donekle jednostavniji kada je u pitanju tansplantacija PGC s obzirom na njihov daleko manji broj u odnosu na spermatogonije i na to da one još uvek nisu potpuno razvijene u gonadama. S druge strane, SSC su dobro razvijene u gonadama i najčešće zauzimaju karakteristično mesto unutar pojedinačnih niša u testisu specifičnih za tu vrstu ćelija. Prilikom izolacije nediferenciranih spermatogonija A tipa iz testisa odrasle jedinke, veome je bitno voditi računa od morfologiji tih ćelija kao i specifičnim markerima pomoću kojih ih je moguće razlikovati od ostalih tipova spermatogonija (Adiff, B), spermatocita i spermatida. Osnovne histološke metode u kombinaciji sa imunohistohemijom, in situ hibridizacijom ili in situ PCR metodom se mogu koristiti za identifikaciju spefifičnih molekularnih markera (proteina ili RNK) u ćelijama unutar ćelijskih niša i koji se u daljem toku rada mogu koristiti za izolaciju određenih ćelija. Pre transplantacije PGC ili SSC, neophodno je izolovati željene ćelije iz donorskog tkiva. Nakon multienzimske razgradnje tkiva testisa, ćelije se izoluju na osnovu njihove morfologije i veličine i/ili specifičnih molekularnih markera zbog kojih čitav proces može biti species-specifičan. Kombinacija transplantacije PGS i SSC sa krioprezervacijom daje dodatni značaj ovoj metodi s obzirom da još uvek ne postoji optimizovan protokol za uspešnu krioprezervaciju jaja i embriona riba, pre svega zbog prisustva velike količine žumanceta i masti. Krioprezervacija ćelija kao što su PGS i SSC, koje imaju mogućnost da produkuju spermatozoide ili oocite u zavisnosti od pola jedinke primaoca, ima izuzetno veliku perspektivu primene u konzervacionoj biologiji i akvakulturi. Istraživanja su pokazala da krioprezervirane SSC nakon odmrzavanja i transplantacije u telo primaoca mogu proizvesti spermatozoide i oocite donorske vrste (Kobayashi et al., 2007). Na taj način, čuvanje gameta nije neophodno jer krioprezervacijom germinativnih ćelija i njihovom transplantacijom, moguće je dobiti gamete oba pola.In recent years, the importance of manipulations of primordial germ cells (PGCs) and spermatogonial stem cells (SSCs) in fish has drastically increased due to development of transplantation method of these cells. Since its development by Brinster and Avarbock (1994), this method has been successfully used in the preservation of genetic material of endangered species and in the creation of new transgenic lines of mice and farm animals. Introduction of this method in fish leads to advances in reproductive biotechnology, aquaculture, development of new transgenic lines and conservation biology of fish. The base of this method lies in the transplantation of the germinative cells (PGCs, SSCs) from donor organism into recipient organism. Undifferentiated spermatogonia type A (Aund) which have the ability of self-renewal are the most interesting for transplantation since they have the ability of self-renewal, but can also produce later stage cells. There are several advantages of using SSCs in transplantation process: (1) the capability of SSCs to colonize the testis of the recipients where they are able to produce donor-derived sperm, (2) plasticity in development since SSCs can develop into spermatogonia in male recipients and oogonia in female recipients and (3) the possibility of genetic manipulation in SSCs in order to produce transgenic fish (Lacerda et al., 2010). When transplanting SSCs, special attention must be given to the choice of donors and recipients species. It is best that donor and recipient organisms are phylogenetically not too distant, that recipient organisms have a short reproductive cycle and that they are small for a more economic rearing. Donor species are usually species which attract certain interest, whether its an economic, scientific or conservation interest. During transplantation, compatibility between recipient and donor may be a very limiting factor in transplantation success. In the worst-case scenario, recipients may completely reject the transplanted tissue or cells due to immunological reaction. This is especially the case when transplanting SSCs isolated from adult donors into adult recipients. In order to evade the problems caused by adult-adult transplantations, scientists have taken advantage of the ontogeny of recipients, mainly the ontogeny of their immune system, and used embryos and larvae as recipients. Embryos and larvae do not have a developed immune system nor differentiated T-cells (Takeuchi et al., 2003; Yoshizaki et al., 2011), therefore they do not have mechanisms to reject the donor tissue. Furthermore, it is easier to knock-out larval endogenous PGCs than to deplete SSCs from already developed gonad. Apart from choosing the right donor and recipient organisms, it is necessary to isolate specific cells that need to be transplanted. This is to some extent easier when transplanting PGCs, since there are fewer of them than SSCs, and they have not yet fully developed inside the gonads. On the other hand, SSCs are well developed inside the gonads and usually take their specific place within the spermatogonial stem niche. When isolating undifferentiated spermatogonia type A from adult testis, special attention must be given to their morphology and specific markers that distinguish them from other types of spermatogonia (Adiff, B), spermatocytes and spermatids. Basic histology may be coupled with immunohistochemistry, in situ hybridization or in situ PCR which would enable the identification of specific molecular markers within the cells of the niche (proteins or RNA). All this data can be further used in isolation of particular cells. Prior to transplantation, PGCs and spermatogonia need to be isolated from the donor tissue. After multi-enzymatic digestion it is possible to isolate cells based on their morphology and size, and/or specific molecular markers and the whole process can be species-specific. A great advantage of transplantation of PGCs and SSCs is that this method can be very well combined with cryopreservation. There are still no optimized protocols for cryopreservation of fish eggs and embryos, mostly due to presence of large amount of yolk and fat. Since PGCs and SSCs can develop into both sperm and eggs, cryopreservation of these cells could have a great perspective in conservation biology but also in aquaculture. Studies have shown that frozen/thawed SSCs transplanted into recipients give rise to potent donor sperm and eggs in the recipients (Kobayashi et al., 2007). In this way, there is no need to conserve both sperm and eggs since successful cryopreservation of germ cells can give rise to both sperm and eggs after transplantation

Potential of corn distiller’s dried grains with solubles (DDGS) in the diet of European catfish (Silurus glanis)

Two experiments were conducted to evaluate the suitability of corn DDGS as a protein source for European catfish (Silurus glanis). The first experiment consisted of an in vivo digestibility assessment to determine apparent digestibility coefficients for protein, lipid, phosphorus and amino acids available in DDGS. One hundred twenty juveniles (average weight, 154.29 ± 2.73 g) were distributed in recirculation water system equipped with six 1m3 fiberglass tanks (20 fish per tank), which were allotted to two experimental group in triplicates. Juveniles were fed either of the two diets, with or without DDGS (DDGS diet or reference diet) ad libitum till saturation 3 times per day for two weeks. Apparent digestibility coefficient of dry matter, crude protein, crude fat and phosphorus of DDGS ingredient for Europeean catfish were found 49.42 %, 73.39 %, 77.38 % and 87.98 % respectively. The second experiment was conducted for eight weeks to evaluate the effect of corn DDGS on growth, nutrient utilization and metabolism of European catfish. Two hundred forty juveniles of European catfish (average weight, 272.7 ± 37.8 g) were stocked in 1000 L glass fibre tanks in a recirculation system in triplicates. Juveniles were fed with either of the four iso-nitrogenous and iso-caloric (37 % crude protein and 6 % crude fat) experimental diets formulated with the inclusion of 0, 10, 20 and 30 % corn DDGS with partial replacement of soybean and wheat. No significant differences were found between the experimental groups regarding growth performance and plasma biochemical parameters. The liver histopathological observations showed that 20 and 30 % DDGS groups had less vacuolized hepatocytes than the other groups. Both experiments conclude that apparent digestibility of corn DDGS is auspicious for European catfish and 30 % DDGS can be included in the diet of European catfish without compromising the growth performance and nutrient utilization

Carp Breeding in the Carpathian Basin with a Sustainable Utilization of Renewable Natural Resources

In the Central European region, there is a long tradition of breeding fish in artificially constructed ponds. As the area belongs to the temperate zone, farmed fish need to survive cold winter periods. Common carp (Cyprinus carpio L.), which is an omnivorous, bioturbating species, is well adapted to warm and cold periods and the alluvial water environment. Since the Middle Ages, a large scale, efficient carp farming methodology has been developed in the region, where production is based on natural resources (protein and fatty acid sources) of renewable water ecosystems. This summary aims to present this well-developed breedi:ng method through discussing aspects of hydrobiology and energy transfer through the food chain as well. Capabilities and effects of agro-technical treatments such as liming and organic manuring, zooplankton management and possible supplementary feedings are also reviewed. Analysing chemical processes of waters uncovers that biological production has no carbon footprint; no carbon dioxide is released into the atmosphere. In contrast, gaseous carbon dioxide diffuses into pond water containing calcium and/or magnesium, then it accumulates in algae production and, through energy migration to upper trophic levels, increases carp production. Thus, it can be declared that pond-farmed carp provides an environmentally friendly, delicious meat among products of animal origin

A fokozottan veszélyeztetett hévízi törpenövésű magyar vadpontynál (Cyprinus carpio carpio morpha hungaricus) észlelt sajátságos gazda-parazita kapcsolat vizsgálata (előzetes eredmények)

Őshonos hévízi törpenövésű vadponty (Cyprinus carpio carpio morpha hungaricus) kopoltyúféreg fertőzöttségét tanulmányoztuk különös tekintettel Dactylogyrus minutus fajra vonatkozóan. A szezonális vizsgálataink során a prevalencia magas volt (>90 %) a vizsgált halaknál, valamint a kopoltyúféreg paraziták Dactylogyrus minutus fajnak bizonyultak a határozóbélyegek alapján

Haemangioma in the oesophagus of a red-eared slider (Trachemys scripta elegans)

A haemangioma developing in the wall of the oesophagus and protruding into its cavity is reported for the first time from a Red-eared Slider (Trachemys scripta elegans). As the tumour mechanically hampered swallowing, the animal was unable to eat and consequently developed a poor condition. Histopathology of the tumour revealed all characteristics of a haemangioma: the blood-filled blood-vessels having an irregular cross-section were lined with endothelial cells. Claudin-5 immunohistochemical antibodies were employed for characterising the tumour, and this examination confirmed our initial diagnosis of a haemangioma