Publications

4427

A genome-based polyphasic approach was used to determine the taxonomic status of two novel bacterial strains, SCSIO 12594T and SCSIO 12813T, isolated from tissues of a coral. Both strains were Gram-stain-negative and facultatively anaerobic. The genome sizes of strains SCSIO 12594T and SCSIO 12813T were 3.9 Mb and 4.1 Mb, respectively, and they possessed DNA G+C contents of 55.1 and 46.2 mol%, respectively . Both strains were found to be catalase- and oxidase-positive, while SCSIO 12594T also could hydrolyse starch. SCSIO 12594T was observed to grow at between 20 and 37 °C (optimally at 25 °C) and at a pH range from 6 to 7 and in the presence of 3–7 % (w/v) NaCl. The growth of SCSIO 12813T required seawater and occurred at 20–30 °C (optimum, 25 °C), pH 5–8 (optimum, pH 6–7) and in the presence of 3–3.7 % (w/v) NaCl. The results of 16S rRNA gene-based phylogenetic analysis indicated that SCSIO 12594T shared 92.97 % or less sequence similarity with its closest relatives Rhodobium gokarnense JA173T and other members of the order Hyphomicrobiales. The results of 16S rRNA sequences-based phylogenetic analysis of SCSIO 12813T indicated that Croceimicrobium hydrocarbonivorans A20-9T (89.34 %) was the most closely related species. SCSIO 12594T and SCSIO 12813T can be readily separated from their closest relatives, as indicated by the results of phylogenomic analysis, low average nucleotide indexes, average amino acid identity, digital DNA–DNA hybridisation (dDDH) similarities and associated phenotypic and chemical data. Consequently, the two coral isolates are considered to represent two novel genera and species for which the names Coralliovum pocilloporae gen. nov., sp. nov. and Sanyastnella coralliicola gen. nov., sp. nov. are proposed, the type strains are SCSIO 12594T (= JCM 35320T = GDMCC 1.3060T) and SCSIO 12813T (= JCM 35373T = GDMCC 1.3063T), respectively. In addition, two novel families, Coralliovaceae fam. nov. and Sanyastnellaceae fam. nov are proposed to accommodate Coralliovum pocilloporae gen. nov., sp. nov. and Sanyastnella coralliicola gen. nov., sp. nov., respectively.

Terrestrial cyanobacteria are extremely diverse. In urban areas, they can be found as black stains on the surface of building walls, stone monuments, or man-made structures. Many of the terrestrial cyanobacteria are still understudied. To expand knowledge of terrestrial cyanobacterial diversity, a polyphasic characterization was performed to identify 12 strains isolated from campus of University of the Ryukyus, Okinawa, Japan. Multigene phylogenetic analyses based on 16S rRNA gene and 16S-23S rRNA internal transcribed spacer (ITS) region showed that the isolated strains formed two independent subclades within Nodosilinea, and were distantly related to all described Nodosilinea species. The 16S-23S rRNA ITS secondary structures showed variations for D1-D1′ and Box B domain, while V3 domain was almost identical among entire species of Nodosilinea, including the studied strains. In addition, a unique morphological character, i.e. forming nodule or spiral shape, was also observed in certain studied strains. According to polyphasic characterization, Nodosilinea coculeatus sp. nov. and Nodosilinea terrestrialis sp. nov., were proposed as two new species of terrestrial cyanobacteria from Okinawa.

Metcalfa pruinosa (Say, 1830) - новий інвазивний шкідник Humulus lupulus L., який заселяє 130 видів рослин у Києві. Крім того, він є переносником Candidatus Phytoplasma asteris, який інфікує H. lupulus. З огляду на це, ми проаналізували та порівняли літературні дані щодо хазяїв M. pruinosa у Києві та Ca. P. asteris загалом. В результаті ми виявили 13 їхніх спільних рослин-хазяїв: Acer negundo L., Citrus limon (L.) Osbeck, Corylus avellana L., Fraxinus excelsior L., H. lupulus, Musa acuminata Colla, Prunus cerasus L., Prunus domestica L., Rosa canina L., Sonchus oleraceus L., Tilia cordata Mill., Trifolium pratense L., Vitis vinifera L. У подальших дослідженнях слід оцінити інфікованість цих хазяїв Ca. P. asteris.

Abstract Diaphorina citri serves as the primary vector for ‘Candidatus Liberibacter asiaticus’ (CLas), the bacterium associated with the severe Asian form of huanglongbing. CLas-positive D. citri are more fecund than their CLas-negative counterparts and require extra energy expenditure. Therefore, understanding the molecular mechanisms linking metabolism and reproduction is of particular importance. In this study, we found adipokinetic hormone (DcAKH) and its receptor (DcAKHR) were essential for increasing lipid metabolism and fecundity in response to CLas infection in D. citri. Knockdown of DcAKH and DcAKHR not only resulted in the accumulation of triacylglycerol and a decline of glycogen, but also significantly decreased fecundity and CLas titer in ovaries. Combined in vivo and in vitro experiments showed that miR-34 suppresses DcAKHR expression by binding to its 3’ untranslated region, whilst overexpression of miR-34 resulted in a decline of DcAKHR expression and CLas titer in ovaries and caused defects that mimicked DcAKHR knockdown phenotypes. Additionally, knockdown of DcAKH and DcAKHR significantly reduced juvenile hormone (JH) titer and JH signaling pathway genes in fat bodies and ovaries, including the JH receptor, methoprene-tolerant (DcMet), and the transcription factor, Krüppel homolog 1 (DcKr-h1), that acts downstream of it, as well as the egg development related genes vitellogenin 1-like (DcVg-1-like), vitellogenin A1-like (DcVg-A1-like) and the vitellogenin receptor (DcVgR). As a result, CLas hijacks AKH/AKHR-miR-34-JH signaling to improve D. citri lipid metabolism and fecundity, while simultaneously increasing the replication of CLas, suggesting a mutualistic interaction between CLas and D. citri ovaries.

ABSTRACT Bacterial endosymbionts of eukaryotic hosts typically experience massive genome reduction, but the underlying evolutionary processes are often obscured by the lack of free-living relatives. Endomicrobia, a family-level lineage of host-associated bacteria in the phylum Elusimicrobiota that comprises both free-living representatives and endosymbionts of termite gut flagellates, are an excellent model to study evolution of intracellular symbionts. We reconstructed 67 metagenome-assembled genomes (MAGs) of Endomicrobiaceae among more than 1,700 MAGs from the gut microbiota of a wide range of termites. Phylogenomic analysis confirmed a sister position of representatives from termites and ruminants, and allowed to propose eight new genera in the radiation of Endomicrobiaceae . Comparative genome analysis documented progressive genome erosion in the new genus Endomicrobiellum , which comprises all flagellate endosymbionts characterized to date. Massive gene losses were accompanied by the acquisition of new functions by horizontal gene transfer, which led to a shift from a glucose-based energy metabolism to one based on sugar phosphates. The breakdown of glycolysis and many anabolic pathways for amino acids and cofactors in several subgroups was compensated by the independent acquisition of new uptake systems, including an ATP/ADP antiporter, from other gut microbiota. The putative donors are mostly flagellate endosymbionts from other bacterial phyla, including several, hitherto unknown lineages of uncultured Alphaproteobacteria , documenting the importance of horizontal gene transfer in the convergent evolution of these intracellular symbioses. The loss of almost all biosynthetic capacities in some lineages of Endomicrobiellum suggests that their originally mutualistic relationship with flagellates is on its decline. IMPORTANCE Unicellular eukaryotes are frequently colonized by bacterial and archaeal symbionts. A prominent example are the cellulolytic gut flagellates of termites, which harbor diverse but host-specific bacterial symbionts that occur exclusively in termite guts. One of these lineages, the so-called Endomicrobia, comprises both free-living and endosymbiotic representatives, which offers the unique opportunity to study the evolutionary processes underpinning the transition from a free-living to an intracellular lifestyle. Our results revealed a progressive gene loss in energy metabolism and biosynthetic pathways, compensated by the acquisition of new functions via horizontal gene transfer from other gut bacteria, and suggest the eventual breakdown of an initially mutualistic symbiosis. Evidence for convergent evolution of unrelated endosymbionts reflects adaptations to the intracellular environment of termite gut flagellates.