Hypoxia-sonic hedgehog axis as a driver of primitive hematopoiesis development and evolution in cavefish.

The teleost Astyanax mexicanus consists of surface dwelling (surface fish) and cave dwelling (cavefish) forms. Cavefish have evolved in subterranean habitats characterized by reduced oxygen levels (hypoxia) and exhibit a subset of phenotypic traits controlled by increased Sonic hedgehog (Shh) signaling along the embryonic midline. The enhancement of primitive hematopoietic domains, which are formed bilaterally in the anterior and posterior lateral plate mesoderm, are responsible for the development of more larval erythrocytes in cavefish relative to surface fish.

Natural reversal of cavefish heart asymmetry is controlled by Sonic Hedgehog effects on the left-right organizer.

The direction of left-right visceral asymmetry is conserved in vertebrates. Deviations of the standard asymmetric pattern are rare, and the underlying mechanisms are not understood. Here, we use the teleost Astyanax mexicanus, consisting of surface fish with normal left-oriented heart asymmetry and cavefish with high levels of reversed right-oriented heart asymmetry, to explore natural changes in asymmetry determination.

Hypoxia-Sonic Hedgehog Axis as a Driver of Primitive Hematopoiesis Development and Evolution in Cavefish.

Unlabelled: The teleost consists of surface dwelling (surface fish) and cave dwelling (cavefish) forms. Cavefish have evolved in subterranean habitats characterized by reduced oxygen levels (hypoxia) and show constructive and regressive phenotypic traits controlled by increased Sonic hedgehog (Shh) signaling along the embryonic midline. The enhancement of primitive hematopoietic domains, which are formed bilaterally in the anterior and posterior lateral plate mesoderm, are responsible for the development of more larval erythrocytes in cavefish relative to surface fish.

, a Maternal and Zygotic SHARK Family Tyrosine Kinase Gene, Is Disrupted in , a Tailless Ascidian.

AbstractWe describe the cloning and expression of a nonreceptor tyrosine kinase, (), a () gene, identified in a subtractive screen for maternal ascidian cDNAs in , an ascidian species with a tadpole larva. The gene encodes a 4-kb mRNA expressed in gonads, eggs, and embryos in the tailed but is not detected in eggs or embryos of the closely related tailless species . There is a large insertion in in the genome, as shown by transcriptome and genome analyses, resulting in it becoming a pseudogene.