Repeated independent origins of the placenta reveal convergent and divergent organ evolution within a single fish family (Poeciliidae).

An outstanding question in biology is to what extent convergent evolution produces similar, but not necessarily identical, complex phenotypic solutions. The placenta is a complex organ that repeatedly evolved in the livebearing fish family Poeciliidae. Here, we apply comparative approaches to test whether evolution has produced similar or different placental phenotypes in the Poeciliidae and to what extent these phenotypes correlate with convergence at the molecular level.

Insulin-like 3 affects zebrafish spermatogenic cells directly and via Sertoli cells.

Pituitary hormones can use local signaling molecules to regulate target tissue functions. In adult zebrafish testes, follicle-stimulating hormone (Fsh) strongly increases the production of insulin-like 3 (Insl3), a Leydig cell-derived growth factor found in all vertebrates. Little information is available regarding Insl3 function in adult spermatogenesis.

PGE2 inhibits spermatogonia differentiation in zebrafish: interaction with Fsh and an androgen.

Changes in zebrafish testicular gene expression induced by follicle-stimulating hormone (Fsh) or anti-Mullerian hormone (Amh) suggested that Amh inhibition and Fsh stimulation of spermatogenesis involved up and downregulation, respectively, of prostaglandin (PG) signaling. We found that Sertoli cells contacting type A undifferentiated (Aund) and differentiating (Adiff) spermatogonia expressed a key enzyme of PG production (Ptgs2); previous work showed that Sertoli cells contacting Adiff and B spermatogonia and spermatocytes showed ptges3b expression, an enzyme catalyzing PGE2 production. In primary testis tissue cultures, PGE2, but not PGD2 or PGF2α, reduced the mitotic activity of Adiff and their development into B spermatogonia.

Endocrine and local signaling interact to regulate spermatogenesis in zebrafish: follicle-stimulating hormone, retinoic acid and androgens.

Retinoic acid (RA) is crucial for mammalian spermatogonia differentiation, and stimulates expression, a gene required for meiosis. Certain fish species, including zebrafish, have lost the gene. While RA still seems important for spermatogenesis in fish, it is not known which stage(s) respond to RA or whether its effects are integrated into the endocrine regulation of spermatogenesis.

Regulation of spermatogonial development by Fsh: The complementary roles of locally produced Igf and Wnt signaling molecules in adult zebrafish testis.

Spermatogenesis is a cellular developmental process characterized by the coordinated proliferation and differentiation activities of somatic and germ cells in order to produce a large number of spermatozoa, the cellular basis of male fertility. Somatic cells in the testis, such as Leydig, peritubular myoid and Sertoli cells, provide structural and metabolic support and contribute to the regulatory microenvironment required for proper germ cell survival and development. The pituitary follicle-stimulating hormone (Fsh) is a major endocrine regulator of vertebrate spermatogenesis, targeting somatic cell functions in the testes.

Fsh stimulates Leydig cell Wnt5a production, enriching zebrafish type A spermatogonia.

Follicle-stimulating hormone (Fsh) modulates vertebrate spermatogenesis by regulating somatic cell functions in the testis. We have found previously that zebrafish Fsh stimulated the differentiating proliferation of type A undifferentiated spermatogonia (Aund) in an androgen-independent manner by regulating the production of growth factors and other signaling molecules in both Sertoli (SCs) and Leydig cells (LCs). For example, Fsh triggered the release of Igf3 that subsequently activated β-catenin signaling to promote the differentiating proliferation of Aund.

Igf3 activates β-catenin signaling to stimulate spermatogonial differentiation in zebrafish.

Follicle-stimulating hormone (Fsh) is a major regulator of spermatogenesis, targeting somatic cell functions in the testes. We reported previously that zebrafish Fsh promoted the differentiation of type A undifferentiated spermatogonia (A) by stimulating the production of factors that advance germ cell differentiation, such as androgens, insulin-like peptide 3 (Insl3) and insulin-like growth factor 3 (Igf3). In addition, Fsh also modulated the transcript levels of several other genes, including some belonging to the Wnt signaling pathway.

Follicle-Stimulating Hormone Regulates Gene Expression Directly or Downstream Effectors to Modulate Igf3 Effects on Zebrafish Spermatogenesis.

Previous work showed that pharmacological inactivation of Igf-binding proteins (Igfbps), modulators of Igf activity, resulted in an excessive differentiation of type A undifferentiated (A) spermatogonia in zebrafish testis in tissue culture when Fsh was present in the incubation medium. Using this testis tissue culture system, we studied here the regulation of transcript levels by Fsh and two of its downstream effectors, Igf3 and 11-ketotestosterone (11-KT). We also explored how Fsh-modulated expression affected spermatogonial proliferation by adding or removing the Igfbp inhibitor NBI-31772 at different times.

Igf Binding Proteins Protect Undifferentiated Spermatogonia in the Zebrafish Testis Against Excessive Differentiation.

IGF binding proteins (IGFBPs) modulate the availability of IGFs for their cognate receptors. In zebrafish testes, IGF3 promotes the proliferation and differentiation of type A undifferentiated (A) spermatogonia, and igf3 expression is strongly elevated by FSH but also responds to T. Here we report the effects of FSH and T on igfbp transcript levels in adult zebrafish testis.

Nutritional status modulates plasma leptin, AMPK and TOR activation, and mitochondrial biogenesis: Implications for cell metabolism and growth in skeletal muscle of the fine flounder.

Insight of how growth and metabolism in skeletal muscle are related is still lacking in early vertebrates. In this context, molecules involved in these processes, such as leptin, AMP-activated protein kinase (AMPK), target of rapamicyn (TOR), peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α, and oxidative phosphorylation complexes (OXPHOS), were assessed in the skeletal muscle of a fish species. Periods of fasting followed by a period of refeeding were implemented, using the fine flounder as a model (Paralichthys adspersus).

Isolation and selection of suitable reference genes for real-time PCR analyses in the skeletal muscle of the fine flounder in response to nutritional status: assessment and normalization of gene expression of growth-related genes.

In the present study, different reference genes were isolated, and their stability in the skeletal muscle of fine flounder subjected to different nutritional states was assessed using geNorm and NormFinder. The combinations between 18S and ActB; Fau and 18S; and Fau and Tubb were chosen as the most stable gene combinations in feeding, long-term fasting and refeeding, and short-term refeeding conditions, respectively. In all periods, ActB was identified as the single least stable gene.

Dynamic transcriptional regulation of autocrine/paracrine igfbp1, 2, 3, 4, 5, and 6 in the skeletal muscle of the fine flounder during different nutritional statuses.

The IGF-binding proteins (IGFBPs) play a dual role in the regulation of the activity and bioavailability of IGFs in different tissues. Diverse evidence has shown that IGFBPs can inhibit and/or potentiate IGF actions. In this study, igfbp1, 2, 3, 4, 5, and 6 were isolated in the fine flounder, a flat fish species that shows slow growth and inherent Gh resistance in muscle.

Molecular cloning of IGF-1 and IGF-1 receptor and their expression pattern in the Chilean flounder (Paralichthys adspersus).

Insulin-like growth factor-1 and insulin-like growth factor-1 receptor (IGF-1 and IGF-1R) play main roles in vertebrate growth and development. In fish, besides contributing to somatic growth, both molecules exhibit pleiotropic functions. We isolated complete cDNAs sequences encoding for both IGF-1 and IGF-1R in the Chilean flounder by using RT-PCR and rapid amplification of cDNAs ends (RACE) techniques.