Evolution of the nitric oxide synthase family in vertebrates and novel insights in gill development.

Nitric oxide (NO) is an ancestral key signalling molecule essential for life and has enormous versatility in biological systems, including cardiovascular homeostasis, neurotransmission and immunity. Although our knowledge of NO synthases (Nos), the enzymes that synthesize NO in vivo, is substantial, the origin of a large and diversified repertoire of nos gene orthologues in fishes with respect to tetrapods remains a puzzle. The recent identification of nos3 in the ray-finned fish spotted gar, which was considered lost in this lineage, changed this perspective. This finding prompted us to explore nos gene evolution, surveying vertebrate species representing key evolutionary nodes. This study provides noteworthy findings: first, nos2 experienced several lineage-specific gene duplications and losses. Second, nos3 was found to be lost independently in two different teleost lineages, Elopomorpha and Clupeocephala. Third, the expression of at least one nos paralogue in the gills of developing shark, bichir, sturgeon, and gar, but not in lamprey, suggests that nos expression in this organ may have arisen in the last common ancestor of gnathostomes. These results provide a framework for continuing research on nos genes' roles, highlighting subfunctionalization and reciprocal loss of function that occurred in different lineages during vertebrate genome duplications.

Using transcriptomics to enable a plethodontid salamander (Bolitoglossa ramosi) for limb regeneration research.

BACKGROUND: Tissue regeneration is widely distributed across the tree of life. Among vertebrates, salamanders possess an exceptional ability to regenerate amputated limbs and other complex structures. Thus far, molecular insights about limb regeneration have come from a relatively limited number of species from two closely related salamander families. To gain a broader perspective on the molecular basis of limb regeneration and enhance the molecular toolkit of an emerging plethodontid salamander (Bolitoglossa ramosi), we used RNA-Seq to generate a de novo reference transcriptome and identify differentially expressed genes during limb regeneration. RESULTS: Using paired-end Illumina sequencing technology and Trinity assembly, a total of 433,809 transcripts were recovered and we obtained functional annotation for 142,926 non-redundant transcripts of the B. ramosi de novo reference transcriptome. Among the annotated transcripts, 602 genes were identified as differentially expressed during limb regeneration. This list was further processed to identify a core set of genes that exhibit conserved expression changes between B. ramosi and the Mexican axolotl (Ambystoma mexicanum), and presumably their common ancestor from approximately 180 million years ago. CONCLUSIONS: We identified genes from B. ramosi that are differentially expressed during limb regeneration, including multiple conserved protein-coding genes and possible putative species-specific genes. Comparative analyses reveal a subset of genes that show similar patterns of expression with ambystomatid species, which highlights the importance of developing comparative gene expression data for studies of limb regeneration among salamanders.

Reprogramming to pluripotency is an ancient trait of vertebrate Oct4 and Pou2 proteins.

The evolutionary origins of the gene network underlying cellular pluripotency, a central theme in developmental biology, have yet to be elucidated. In mammals, Oct4 is a factor crucial in the reprogramming of differentiated cells into induced pluripotent stem cells. The Oct4 and Pou2 genes evolved from a POU class V gene ancestor, but it is unknown whether pluripotency induced by Oct4 gene activity is a feature specific to mammals or was already present in ancestral vertebrates. Here we report that different vertebrate Pou2 and Oct4 homologues can induce pluripotency in mouse and human fibroblasts and that the inability of zebrafish Pou2 to establish pluripotency is not representative of all Pou2 genes, as medaka Pou2 and axolotl Pou2 are able to reprogram somatic cells into pluripotent cells. Therefore, our results indicate that induction of pluripotency is not a feature specific to mammals, but existed in the Oct4/Pou2 common ancestral vertebrate.

Clioquinol and other hydroxyquinoline derivatives inhibit Abeta(1-42) oligomer assembly.

Soluble oligomeric amyloid-beta (Abeta) species are toxic to many cell types and are a putative etiological factor in Alzheimer's disease. The NINDS-Custom Collection of 1040 drugs and biologically active compounds was robotically screened for inhibitors of Abeta oligomer formation with a single-site biotinylated Abeta(1-42) oligomer assembly assay. Several quinoline-like compounds were identified with IC(50)'s <10 microM, including the antiprotozoal clioquinol that has been reported to have effects on metal ion metabolism. The 2-OH, 4-OH, and 6-OH quinolines do not block Abeta oligomer formation up to a concentration of 100 microM. Analogs of clioquinol have shown activity in reducing Abeta levels and improving behavioral deficits in mouse models of Abeta pathology. The inhibitory effects of clioquinol and other 8-OH quinoline derivatives on oligomer formation in vitro are unrelated to their chelating activity. Crosslinking studies suggest that clioquinol acts at the stage of trimer formation. These preliminary data may suggest that 8-OH quinolines have the potential for suppressing Abeta oligomer formation which should be considered when assessing the effects of these compounds in animal models and clinical trials.