Characterization and mapping of the Xiphophorus maculatus (Teleostei: Poeciliidae) RPS15 gene
CYTOGENETICS AND CELL GENETICS
Authors: Walter, RB; Obermoeller, RD; Moore, DD; Lacson, JM; DellaColetta, L; McEntire, BB; Morizot, DC; Nairn, RS
Abstract
We have determined the nucleotide sequence and gene map location of the Xiphophorus maculatus homologue of RPS15 (ribosomal protein S15, alias RIG). The Xiphophorus RPS15 cDNA encodes 145 amino acids, which show 94% identity compared to deduced mammalian and avian RPS15 amino acid sequences. At the nucleotide level, 84% sequence identity is maintained between the fish and human gene, while homologous amphibian and avian sequences show about 80% nucleotide identity compared to the Xiphophorus sequence. Nucleotide identity substantially decreases when the fish gene is compared to Arabidopsis S15 (64%) and yeast S21 (55%) genes. Genetic linkage analysis of an RPS15 restriction fragment length polymorphism in backcross hybrids generated from the cross X. helleri x (X. maculatus Jp 163 B x X. helleri) demonstrated linkage of Xiphophorus RPS15 to the EGFR, UMPK and YES loci in Xiphophorus Linkage Group VI.
Resolving the phylogenetic position of Ombrocharis (Lamiaceae), with reference to the molecular phylogeny of tribe Elsholtzieae
TAXON
Authors: Chen, Ya-Ping; Drew, Bryan T.; Li, Bo; Soltis, Douglas E.; Soltis, Pamela S.; Xiang, Chun-Lei
Abstract
Ombrocharis is the only incertae sedis genus within Lamiaceae that has not been included in a published molecular phylogenetic study. Here, we adopt a two-step approach to resolve the phylogenetic placement of the genus. Initially, the subfamilial affiliation of Ombrocharis was determined based on a combined ndhF and rbcL dataset covering all seven subfamilies of Lamiaceae. Results show that Ombrocharis is a member of Nepetoideae, a placement that is also supported by its hexacolpate pollen grains. In the second set of analyses, two nrDNA (ITS, ETS) and four cpDNA (ycf1, rps15-ycf1, trnL-F, rpl32-trnL) markers were used to explore the position of Ombrocharis within Nepetoideae. Our results demonstrate that Ombrocharis and another monotypic genus, Perillula, form a clade that is sister to the remaining genera of tribe Elsholtzieae. Ombrocharis and other taxa within Elsholtzieae share divergent stamens, a weakly 2-lipped corolla, and an asymmetric disc with an elongate anterior lobe, but it is unclear whether these features are apomorphic. This study represents both the most comprehensive phylogenetic analysis of Elsholtzieae to date and the only study to include all genera of Elsholtzieae. The monophyly of Elsholtzieae (including Ombrocharis) is well supported, and there is weak support for Elsholtzieae as sister to the rest of Nepetoideae. Additionally, our results do not support the merging of Keiskea with Collinsonia, and Elsholtzia may be polyphyletic.