ABSTRACT
The use of model organisms is important for basic and applied sciences. Several laboratory species of fishes are used to develop advanced technologies, such as the zebrafish (Danio rerio), the medaka (Oryzias latipes), and loach species (Misgurnus spp.). However, the application of these exotic species in the Neotropical region is limited due to differences in environmental conditions and phylogenetic distances. This situation emphasizes the establishment of a model organism specifically for the Neotropical region with the development of techniques that may be applicable to other Neotropical fish species. In this work, the previous research efforts are described in order to establish the yellowtail tetra Astyanax altiparanae as a model laboratory species for both laboratory and aquaculture purposes. Over the last decade, starting with artificial fertilization, the yellowtail tetra has become a laboratory organism for advanced biotechnology, such as germ cell transplantation, chromosome set manipulation, and other technologies, with applications in aquaculture and conservation of genetic resources. Nowadays, the yellowtail tetra is considered the most advanced fish with respect to fish biotechnology within the Neotropical region. The techniques developed for this species are being used in other related species, especially within the characins class.
ABSTRACT
Flow cytometry is a valuable tool in biomedical and animal sciences. However, equipment used for such analysis presents limitations at field conditions, suggesting then preservation procedures for future analysis at laboratory conditions. In this study, freezing at low (-20 °C), ultra-low (-80 °C) and cryogenic temperatures (-196 °C, i.e. liquid nitrogen) were used as preservation procedures of fish tissue. Samples were maintained in 0.9% NaCl or lysing solution, and stored at the temperatures above for 0 (fresh control), 60, 120 and 180 days of storage. After storage, the samples were thawed and proceeded to flow cytometric analysis. Storage at low temperatures (-20 °C), both in lysing and 0.9% NaCl, exhibited poor results when analyzed after 60, 120 and 180 days, showing noisy peaks, deviation in the DNA content and absence of peaks. Ultralow (-80 °C) and cryogenic (-196 °C) temperatures, both in lysing solution and 0.9% NaCl, showed good results and high quality of histograms. Both storage procedures gave similar histograms and DNA content in comparison with control group (fresh) even after 60, 120 and 180 days of storage, exhibiting the main peak at 2C content from diploid cells and a secondary peak at 4C derived from dividing cells. In conclusion, samples may be stored for 180 days at -80 °C and -196 °C in both, 0.9% NaCl or lysing solution. As cryogenic temperatures in liquid nitrogen permits indefinite storage, this procedure should be used for long-term preservation.
Subject(s)
Cold Temperature , Cryopreservation , Animals , Cryopreservation/methods , Flow Cytometry , Freezing , TemperatureABSTRACT
This study aimed to examine the gonadal morphology of diploid and triploid fish through stereological analysis. Triploid individuals were obtained after temperature shock (40°C for 2 min) at 2 min post-fertilization and reared until 175 days post-fertilization (dpf). Intact eggs were used to obtain the diploids. Gonads were collected for histological analysis at 83, 114, 144 and 175 dpf. Diploid females and males presented normal oogenesis and spermatogenesis through all the experimental period. Conversely, stereological analysis revealed that triploid females were sterile and oogonia were the prevalent cell type in the ovaries. Triploid males presented increased amounts of spermatocyte cysts and a large area of lumen when compared with diploids and in addition the amount of spermatozoa was lower than that observed for diploids. However, some triploid males presented spermatogenesis similar to diploids. Therefore, we concluded that triploidization is an interesting alternative to produce sterile individuals in A. altiparanae.
