The effects of temperature and busulfan (Myleran) on the yellowtail tetra Astyanax altiparanae (Pisces, Characiformes) spermatogenesis

Abstract

We aimed to standardize a protocol to suppress spermatogenesis in the characiform fish, Astyanax altiparanae, for future use as a host in germ cell transplant research, opening opportunities for a range of studies, such as spermatogenesis analyses and transgenesis because this species presents livestock characteristics to be used as a biological model. The effects of the chemotherapeutic busulfan (formulated as Myleran), which is used as medicine, therefore not as toxic to humans manipulation as analytical grade busulfan (Fluka) used in previous studies, were evaluated at physiological temperature of 28 °C, ideal for growth and reproduction of A altiparanae, and also at increased temperature 35 °C. The temperature groups were divided into three treatment groups: busulfan, DMSO only, and an untreated control. Macroscopic, histologic, stereological, and ultrastructure analysis showed that, at 28 °C, busulfan did not cause depletion of germ cells in A altiparanae. However, at 35 °C, sterilization was observed 3 weeks after the initial application. Similar results were obtained with maintenance of fish at 35 °C for a longer period with no accompanying Myleran treatment. This procedure allows reduction in stress and lower mortality resulting from manipulation during busulfan injection and is also suitable for mass treatment because large numbers of fish can be incubated in warm water.

From gametogenesis to spawning: How climate‐driven warming affects teleost reproductive biology

“…Although fewer works have investigated the impacts of warmer‐than‐optimal temperature on male than female reproductive development and gamete quality, some trends appear consistent between the species studied. For example, in several species elevated temperature causes a partial or complete gonadal regression (decrease in or lower GSI, and arrested development) (de Siqueira‐Silva et al ., 2015; Dorts et al ., 2012; Elisio et al ., 2012, 2015; Hani et al ., 2019; Shahjahan et al ., 2017). High temperature has also been associated with a reduction in early‐stage gamete proportion (Spg and Spc) in several species, reflecting a lack of capacity to initiate spermatogenesis, associated with GSI decrease, for example in O. bonariensis exposed to high but natural temperature fluctuations (Elisio et al ., 2012).…”

Triploid Induction in the Yellowtail Tetra, Astyanax altiparanae, Using Temperature Shock: Tools for Conservation and Aquaculture

“…This is interesting because several endangered species and species with critical reproduction exist in characin. Previous research (Siqueira‐Silva et al ) aimed to establish sterile host species but did not achieve sterility in 100% of the fish. Currently, there is not a successful protocol to achieve 100% sterility in both males and females in A. altiparanae .…”

“…This technology requires the host species to be sterile in order to ensure the production of exogenous gametes (from the donor). Previous work focused on establishing sterilization of the yellowtail tetra (Siqueira‐Silva et al ) by chronic exposure at high temperatures, but sterilization was maintained only for a few weeks. One hundred percent sterile fish may be obtained using triploid fish (Piferrer et al ).…”

Depletion of endogenous germ cells in striped catfish Pangasianodon hypophthalmus (Sauvage, 1878) by heat–chemical treatments

“…elevated water temperature: Byerly, Fat‐Halla, Betsill, & Patino, ; Ito, Yamashita, Takahashi, & Strüssmann, ; Pandit, Bhandari, Kobayashi, & Nakamura, ; Strüssmann, Saito, & Takashima, ) or combination of treatments (e.g. heat–chemical: Lacerda, Batlouni, Silva, Homem, & Franca, ; Majhi, Hattori, Rahman, Suzuki, & Strüssmann, ; Majhi, Rasal, Kushwaha, & Raizada, ; de Siqueira‐Silva, Santos Silva, Ninhaus‐Silveira, & Veríssimo‐Silveira, ). In teleost fishes, irrespective of developmental stages, the gonad sterilization is comparatively faster than mammals, especially while combining two treatments such as heat and chemical (Lacerda et al, ; Majhi et al, , ; Pacchiarini, Olague, Sarasquete, & Cabrita, ).…”