Establishing a model fish for the Neotropical region: The case of the yellowtail tetra Astyanax altiparanae in advanced biotechnology

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.

Keywords: chromosome set manipulation; experimental fish; germline chimera; laboratory fish; micromanipulation; polyploids.

FIGURE 1

Adult male and female yellowtail tetra Astyanax altiparanae. The male presents bony hooks in the anal fin, which are not present in the females. Bar scale is 1 cm for the fish, 50 µm for the male fin, and 100 µm for the female fin.

FIGURE 2

Cytological and ultrastructural images from the oocytes and spermatozoa of the yellowtail tetra Astyanax altiparanae. Ultrastructural analysis (scanning electron microscopy,SEM) of the oocyte micropyle (A) showing grooves that guide the sperm entry. DAPI staining of the fertilized oocyte showing male and female pronucleus (B). Second polar body extrusion (C). Spermatozoon of the yellowtail tetra (D). This information was important to develop chromosome set manipulation techniques.

FIGURE 3

Transplantation of spermatogonial stem cells from endangered Brycon orbignyanus through the papillae of sterile juvenile yellowtail tetra Astyanax altiparanae (A). Detached area indicates the testis containing transplanted cells stained with PKH26 and observed under fluorescence microscopy (B). Same histological section visualized under normal light, and hematoxylin-eosin staining shows spermatocytes and spermatogonia from B. orbignyanus. Scale (B–C): 50 µm. Below is a yellowtail tetra embryo injected with GFP-nos1 3′UTR mRNA from Danio rerio, observed under normal light (D).Same embryo, observed under fluorescence microscopy, shows the presumptive primordial germ cells (PGCs) with GFP expression (E). Gonadal ridge area in detail (F).