Characterization of undifferentiated spermatogonia and the spermatogonial niche in the lambari fish Astyanax altiparanae

Abstract

Undifferentiated type A spermatogonia are the foundation of fish spermatogenesis. This cell population includes the spermatogonial stem cell population, which is able to either self-renew or differentiate into cells that will generate the male gamete - the spermatozoa. Spermatogonia stem cells are located in a specific region of the testes known as the spermatogonial niche, which regulates spermatogonial stem cell function. This study characterizes undifferentiated type A spermatogonia and their S-phase label-retaining cell properties in Astyanax altiparanae testes. This is a fish species of substantial commercial, environmental, and academic importance. Two types of undifferentiated spermatogonia have been described in A. altiparanae testis: A and A. Among the main differences observed, A spermatogonia have an irregular nuclear envelope, decondensed chromatin, one or two nucleoli, and nuages in the cytoplasm; meanwhile, type A have a round nucleus. A is preferentially distributed in areas neighboring the interstitial compartment, whereas A is located in the intertubular area. Finally, this study found that undifferentiated type A spermatogonia were able to retain BrdU over a long chase period, suggesting that these cells have a long cell cycle and potential stem cell candidates among them. Based on these findings, undifferentiated type A spermatogonia may be characterized as putative stem cells in A. altiparanae testis. This work will contribute to further studies on thestem cell biology of this promising Neotropical experimental model.

Spermatogonial Stem Cells in Fish: Characterization, Isolation, Enrichment, and Recent Advances of In Vitro Culture Systems

“…These observations suggest that the androgens; growth factors; and vascular supplies of oxygen, nutrients, and hormones may play essential roles in SSC maintenance and self-renewal vs. differentiation in the fish testis niche [10,21]. With respect to whether spermatogonia display a preferential distribution within the fish testes, studies of zebrafish [22] and Astyanax altiparane [45] have shown that both Aund* and Aund spermatogonia are located near the interstitial compartment, in contact with androgen-producing Leydig cells and blood vessels (Figure 4A,B,C). These observations suggest that the androgens; growth factors; and vascular supplies of oxygen, nutrients, and hormones may play essential roles in SSC maintenance and self-renewal vs. differentiation in the fish testis niche [10,21].…”

Effects Caused by the Ingestion of Microplastics: First Evidence in the Lambari Rosa (Astyanax altiparanae)

“…They are commonly found in rivers, lakes, and reservoirs throughout South America [21,22]. The lambari rosa (Astyanax altiparanae) is a species widely used as an experimental model in the fields of biology, ecotoxicology, and reproductive physiology [23][24][25], since its anatomical and behavioral characteristics allow for an interesting comparison with other similar species. In the laboratory, they have characteristics such as ease of handling, acceptance of artificial feeding, prolificacy, and a fast life cycle (reaching the adult stage in around ten weeks) [22,26].…”

GnRHa implants and temperature modulate Lambari‐do‐rabo‐amarelo, Astyanax altiparanae (Characiformes: Characidae) induced reproduction out of the reproductive season

“…A . altiparanae have been used as a model to study reproductive biology (Abreu et al, 2021; Cassel, Chehade, et al, 2017; Cassel, de Paiva Camargo, et al, 2017; Chehade et al, 2020; Costa et al, 2014; De Paiva Camargo et al, 2017; Gomes et al, 2013; Jesus et al, 2017); however, few studies focused on applying physiological tools to enhance the production of this fish species (Brambila‐Souza et al, 2019).…”