Molecular Phylogeny and Evolutionary Relationships between the Ciliate Genera Peniculistoma and Mytilophilus (Peniculistomatidae, Pleuronematida)

Peniculistoma mytili and Mytilophilus pacificae are placed in the pleuronematid scuticociliate family Peniculistomatidae based on morphology and ecological preference for the mantle cavity of mytiloid bivalves. We tested this placement with sequences of the small subunit rRNA ( SSUrRNA) and cytochrome c oxidase subunit 1 ( cox1) genes. These species are very closely related sister taxa with no distinct genetic difference in the SSUrRNA sequence but about 21% genetic difference for cox1, supporting their placement together but separation as distinct taxa. Using infection frequencies, M. pacificae, like its sister species P. mytili, does not interact with Ancistrum spp., co-inhabitants of the mantle cavity. On the basis of these ecological similarities, the fossil record of host mussels, and features of morphology and stomatogenesis of these two ciliates, we argue that M. pacificae derived from a Peniculistoma-like ancestor after divergence of the two host mussels. Our phylogenetic analyses of pleuronematid ciliates includes the SSUrRNA gene sequence of Sulcigera comosa, a Histiobalantium-like ciliate from Lake Baikal. We conclude: ( i) that the pleuronematids are a monophyletic group; ( ii) that the genus Pleuronema is paraphyletic; and ( iii) that S. comosa is a Histiobalantium species. We transfer S. comosa to Histiobalantium and propose a new combination Histiobalantium comosa n. comb

SLC6A14 Is a Genetic Modifier of Cystic Fibrosis That Regulates Pseudomonas aeruginosa Attachment to Human Bronchial Epithelial Cells

Cystic fibrosis (CF) is caused by mutations in the CFTR gene and is associated with progressive and ultimately fatal infectious lung disease. There can be considerable variability in disease severity among individuals with the same CFTR mutations, and recent genome-wide association studies have identified secondary genetic factors that contribute to this. One of these modifier genes is SLC6A14, which encodes an amino acid transporter. Importantly, variants of this gene have been associated with age at first acquisition of Pseudomonas aeruginosa. In this study, we aimed to determine the function of SLC6A14 in airway epithelia and how it might affect colonization by P. aeruginosa. We show that SLC6A14 is expressed in respiratory epithelial cells and transports l-arginine out of the airway surface liquid (ASL). Exposure of airway epithelia to flagellin from P. aeruginosa led to upregulation of SLC6A14 expression and increased SLC6A14-dependent uptake of l-arginine from the ASL. In support of the hypothesis that l-arginine affects P. aeruginosa attachment, we showed that l-arginine supplementation promoted P. aeruginosa attachment to an abiotic surface in a dose-dependent manner. In a coculture model, we found that inhibition of SLC6A14-dependent l-arginine transport enhanced P. aeruginosa attachment. In Slc6a14−/y (knockout) mice, P. aeruginosa attachment to lung tissue was also significantly enhanced. Together, these findings suggest that SLC6A14 activity plays a role in the modification of the initial stages of airway infection by altering the level of l-arginine in the ASL, which in turn affects the attachment of P. aeruginosa

Ciliates — Protists with complex morphologies and ambiguous early fossil record

Since ciliates rarely possess structures that easily fossilize, we are limited in our ability to use paleontological studies to reconstruct the early evolution of this large and ecologically important clade of protists. Tintinnids, a group of loricate (house-forming) planktonic ciliates, are the only group that has a significant fossil record. Putative tintinnid fossils from rocks older than Jurassic, however, possess few to no characters that can be found in extant ciliates; these fossils are best described as ‘incertae sedis eukaryotes’. Here, we review the Devonian fossil Nassacysta reticulata and propose that it is likewise another incertae sedis eukaryote due to the lack of any unambiguous ciliate characters. Future tintinnid fossil descriptions would be most helpful if: (i) neutral terminology is used in the descriptions but ciliate-specific terminology in the interpretations; (ii) the current ciliate classification is used, although fossil data may expand or modify classifications based on modern forms; (iii) close collaboration with specialists studying extant ciliates is done; and (iv) editors include an expert of extant ciliates in the review process