Revision of the phylogeny of Placididea (Stramenopiles): Molecular and morphological diversity of novel placidid protists from extreme aquatic environments

Recent studies suggested that the diversity of microbial eukaryotes in hypersaline environments is widely underestimated. Placidids are a group of heterotrophic stramenopile flagellates that are frequently found in these environments, but up to now only very few species were isolated and fully described, mostly from marine or brackish water sites. In this study, we extend the known diversity of Placididea by three new genera (Allegra, Haloplacidia, and Placilonga) compromising nine new species, isolated from athalassic, mostly hypersaline environments (Allegra dunaii, Allegra atacamiensis, Allegra hypersalina, Haloplacidia cosmopolita, Suigetsumonas keniensis) and marine waters (Placilonga atlantica, Placidia azorensis, Placidia abyssalis, Wobblia pacifica) including a description of their morphology and molecular phylogeny. In total, 36 strains were comparatively analysed. Studies from athalassic waters revealed an especially high number of different genotypes. A multigene analysis based on a ten genes dataset revealed a clear separation into marine, athalassic and brackish water clades. Several representatives were found to cope with hypersaline conditions from 20 to 250 PSU, even up to 284 PSU, suggesting that they may form a halotolerant group.

Venturiales

Members of Venturiales (Dothideomycetes) are widely distributed, and comprise saprobes, as well as plant, human and animal pathogens. In spite of their economic importance, the general lack of cultures and DNA data has resulted in taxa being poorly resolved. In the present study five loci, ITS, LSU rDNA, tef1, tub2 and rpb2 are used for analysing 115 venturialean taxa representing 30 genera in three families in the current classification of Venturiales. Based on the multigene phylogenetic analysis, morphological and ecological characteristics, one new family, Cylindrosympodiaceae, and eight new genera are described, namely Bellamyces, Fagicola, Fraxinicola, Fuscohilum,Neofusicladium, Parafusicladium, Pinaceicola and Sterila. In addition, 12 species are described as new to science, and 41 new combinations are proposed. The taxonomic status of 153 species have been re-evaluated with 20 species excluded from Venturiales. Based on this revision of Venturiales, morphological characteristics such as conidial arrangement (solitary or in chains) or conidiogenesis (blastic-solitary, sympodial or annellidic), proved to be significant at generic level. Venturia as currently defined represents a generic complex. Furthermore, plant pathogens appear more terminal in phylogenetic analyses within Venturiaceae and Sympoventuriaceae, suggesting that the ancestral state of Venturiales is most likely saprobic.

Increased IL-17A/IL-17F expression ratio represents the key mucosal T helper/regulatory cell-related gene signature paralleling disease activity in ulcerative colitis

BACKGROUND

T helper (T_h) and regulatory T (T_reg) cell-related cytokines are implicated in inflammatory bowel diseases, including ulcerative colitis (UC). While these cytokines are generally upregulated in inflamed mucosae, the key cytokine profile explaining disease severity has not been determined.

METHODS

The Rachmilewitz endoscopic index (REI) was assessed in 61 UC patients undergoing colonoscopy. Biopsies obtained from inflamed (REI 3-12) and noninflamed (REI 0-2) areas were analyzed by quantitative PCR for expression of mRNAs encoding cytokines and transcription factors related to Th1 (TNF-α, IFN-γ, IL-12p35, IL-12p40, and T-bet), Th2 (IL-4, IL-13, IL-33, and GATA3), Th17 (IL-17A, IL-17F, IL-21, IL-22, IL-23p19, IL-6, and RORC), Th9 (IL-9, IRF4, and PU.1), and Treg (TGF-β and Foxp3). Expression patterns associated with higher REI were determined by univariate and multivariate analyses.

RESULTS

Despite general upregulation, none of these mRNAs showed univariate correlation with REI in inflamed samples. Multiple regression analysis, however, found that joint expression of IL-17A, IL-17F, IL-21, RORC, and TGF-β was significantly predictive of REI (P < 0.0002, R² = 0.380), with major individual contributions by IL-17A (P < 0.0001) and IL-17F (P < 0.0001), which were associated with increased and decreased REI, respectively. Partial correlation analysis, validating this model, indicated differences between IL-17A and IL-17F in correlating with other targets. The IL-17A/IL-17F ratio showed a significant correlation with REI (r = 0.5124, P < 0.0001), whereas no other mRNAs were essentially predictive of REI.

CONCLUSIONS

Mucosal IL-17A/IL-17F ratio significantly correlates with endoscopic score in UC patients, accompanied by their disparate interactions with other T_h/T_reg-related genes.