scholarly journals The Unique Evolutionary Trajectory and Dynamic Conformations of DR and IR/DR- coexisting Plastomes of the Early Vascular Plant Selaginellaceae (Lycophyte)

2018 ◽  
Author(s):  
Hong-Rui Zhang ◽  
Qiao-Ping Xiang ◽  
Xian-Chun Zhang
Keyword(s):  
Homologous Recombination ◽  
Vascular Plant ◽  
Synonymous Substitution ◽  
Inverted Repeats ◽  
Synonymous Substitution Rate ◽  
Direct Repeats ◽  
Evolutionary Trajectory ◽  
Link Type ◽  
The Family ◽  
Gc Contents

AbstractBoth direct repeats (DR) and inverted repeats (IR) are documented in the published plastomes of four Selaginella species indicating the unusual and diverse plastome structure in the family Selaginellaceae. In this study, we newly sequenced complete plastomes of seven species from five main lineages of Selaginellaceae and also re-sequenced three species (S. tamariscina, S. uncinata and S. moellendorffii) to explore the evolutionary trajectory of Selaginellaceae plastomes. Our results showed that the plastomes of Selaginellaceae vary remarkably in size, gene contents, gene order and GC contents. Notably, both DR and IR structure existed in the plastomes of Selaginellaceae with DR structure being an early diverged character. The occurrence of DR structure was right after the Permian-Triassic (P-T) extinction (ca. 246 Ma) and remained in most subgenera of Selaginellaceae, whereas IR structure only reoccurred in the most derived subg. Heterostachys (ca. 23 Ma). The presence of a pair of large repeats psbK-trnQ, together with DR/IR region in S. bisulcata, S. pennata, S. uncinata, and S. hainanensis, could frequently mediate diverse homologous recombination and create approximately equal stoichiometric isomers (IR/DR-coexisting) and subgenomes. High proportion of repeats is presumably responsible for the dynamic IR/DR-coexisting plastomes, which possess a lower synonymous substitution rate (dS) compared with DR-possessing plastomes. We propose that the occurrence of DR structure, together with few repeats, is possibly selected to adapt to the environmental upheaval during the P-T crisis and the IR/DR-coexisting plastomes also reached an equilibrium in plastome organization through highly efficient homologous recombination to maintain stability.Data depositionAll the plastomes were deposited in GenBank under accession numbers MG272483-MG272484, MH598531-MH598537 and MK156800.

scholarly journals Recent host-shifts in ranaviruses: signatures of positive selection in the viral genome

2013 ◽  
Vol 94 (9) ◽  
pp. 2082-2093 ◽  
Author(s):  
A. Jeanine Abrams ◽  
David C. Cannatella ◽  
David M. Hillis ◽  
Sara L. Sawyer
Keyword(s):  
Positive Selection ◽  
Synonymous Substitution ◽  
Detection Methods ◽  
Host Switching ◽  
Synonymous Substitution Rate ◽  
Host Shifts ◽  
Selective Pressures ◽  
The Family ◽  
Viral Genes ◽  
Core Genes

Ranaviruses have been implicated in recent declines in global amphibian populations. Compared with the family Iridoviridae, to which the genus Ranavirus belongs, ranaviruses have a wide host range in that species/strains are known to infect fish, amphibians and reptiles, presumably due to recent host-switching events. We used eight sequenced ranavirus genomes and two selection-detection methods (site based and branch based) to identify genes that exhibited signatures of positive selection, potentially due to the selective pressures at play during host switching. We found evidence of positive selection acting on four genes via the site-based method, three of which were newly acquired genes unique to ranavirus genomes. Using the branch-based method, we identified eight additional candidate genes that exhibited signatures of dN /dS (non-synonymous/synonymous substitution rate) >1 in the clade where intense host switching had occurred. We found that these branch-specific patterns of elevated dN /dS were enriched in a small group of viral genes that have been acquired most recently in the ranavirus genome, compared with core genes that are shared among all members of the family Iridoviridae. Our results suggest that the group of newly acquired genes in the ranavirus genome may have undergone recent adaptive changes that have facilitated interspecies and interclass host switching.

scholarly journals Pathways for Homologous Recombination Between Chromosomal Direct Repeats in Salmonella typhimurium

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 751-767 ◽  
Author(s):  
Timothy Galitski ◽  
John R Roth
Keyword(s):  
Homologous Recombination ◽  
Strand Break ◽  
Dna Lesions ◽  
General View ◽  
Direct Repeats ◽  
Sexual Recombination ◽  
Sister Chromosome ◽  
Lactose Utilization ◽  
Recf Pathway ◽  
Chromosome Exchanges

Homologous recombination pathways probably evolved primarily to accomplish chromosomal repair and the formation and resolution of duplications by sister-chromosome exchanges. Various DNA lesions initiate these events. Classical recombination assays, involving bacterial sex, focus attention on double-strand ends of DNA. Sexual exchanges, initiated at these ends, depend on the RecBCD pathway. In the absence of RecBCD function, mutation of the sbcB and sbcC genes activates the apparently cryptic RecF pathway. To provide a more general view of recombination, we describe an assay in which endogenous DNA damage initiates recombination between chromosomal direct repeats. The repeats flank markers conferring lactose utilization (Lac+) and ampicillin resistance (ApR); recombination generates Lac-ApS segregants. In this assay, the RecF pathway is not cryptic; it plays a major role without sbcBC mutations. Others have proposed that single-strand gaps are the natural substrate for RecF-dependent recombination. Supporting this view, recombination stimulated by a double-strand break (DSB) in a chromosomal repeat depended on RecB function, not RecF function. Without RecBCD function, sbcBC mutations modified the RecF pathway and allowed it to catalyze DSB-stimulated recombination. Sexual recombination assays overestimate the importance of RecBCD and DSBs, and underestimate the importance of the RecF pathway.

scholarly journals Genome wide identification and characterization of light-harvesting Chloro a/b binding (LHC) genes reveals their potential role in enhancing drought tolerance in Gossypium hirsutum

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Teame Gereziher MEHARI ◽  
Yanchao XU ◽  
Richard Odongo MAGWANGA ◽  
Muhammad Jawad UMER ◽  
Joy Nyangasi KIRUNGU ◽  
...  
Keyword(s):  
Drought Stress ◽  
Gossypium Hirsutum ◽  
Abiotic Stresses ◽  
Substitution Rate ◽  
Synonymous Substitution ◽  
Synonymous Substitution Rate ◽  
Drought Tolerant ◽  
Genome Wide ◽  
Identification And Characterization

Abstract Background Cotton is an important commercial crop for being a valuable source of natural fiber. Its production has undergone a sharp decline because of abiotic stresses, etc. Drought is one of the major abiotic stress causing significant yield losses in cotton. However, plants have evolved self-defense mechanisms to cope abiotic factors like drought, salt, cold, etc. The evolution of stress responsive transcription factors such as the trihelix, a nodule-inception-like protein (NLP), and the late embryogenesis abundant proteins have shown positive response in the resistance improvement to several abiotic stresses. Results Genome wide identification and characterization of the effects of Light-Harvesting Chloro a/b binding (LHC) genes were carried out in cotton under drought stress conditions. A hundred and nine proteins encoded by the LHC genes were found in the cotton genome, with 55, 27, and 27 genes found to be distributed in Gossypium hirsutum, G. arboreum, and G. raimondii, respectively. The proteins encoded by the genes were unevenly distributed on various chromosomes. The Ka/Ks (Non-synonymous substitution rate/Synonymous substitution rate) values were less than one, an indication of negative selection of the gene family. Differential expressions of genes showed that majority of the genes are being highly upregulated in the roots as compared with leaves and stem tissues. Most genes were found to be highly expressed in MR-85, a relative drought tolerant germplasm. Conclusion The results provide proofs of the possible role of the LHC genes in improving drought stress tolerance, and can be explored by cotton breeders in releasing a more drought tolerant cotton varieties.

Pseudogenized Amelogenin Reveals Early Tooth Loss in True Toads (Anura: Bufonidae)

2021 ◽  
Author(s):  
John Shaheen ◽  
Austin B Mudd ◽  
Thomas G H Diekwisch ◽  
John Abramyan
Keyword(s):  
Tooth Loss ◽  
Tooth Enamel ◽  
Synonymous Substitution ◽  
Bufo Bufo ◽  
Molecular Dating ◽  
Bufo Gargarizans ◽  
The Family ◽  
Synonymous Substitution Rates ◽  
Mandibular Teeth ◽  
Early Tooth Loss

Abstract Extant anurans (frogs and toads) exhibit reduced dentition, ranging from a lack of mandibular teeth to complete edentulation, as observed in the true toads of the family Bufonidae. The evolutionary timeline of these reductions remains vague due to a poor fossil record. Previous studies have demonstrated an association between the lack of teeth in edentulous vertebrates and the pseudogenization of the major tooth enamel gene amelogenin (AMEL) through accumulation of deleterious mutations and the disruption of its coding sequence. In the present study we have harnessed the pseudogenization of AMEL as a molecular dating tool to correlate loss of dentition with genomic mutation patterns during the rise of the family Bufonidae. Specifically, we have utilized AMEL pseudogenes in three members of the family as a tool to estimate the putative date of edentulation in true toads. Comparison of AMEL sequences from Rhinella marina, Bufo gargarizans and Bufo bufo, with nine extant, dentulous frogs, revealed mutations confirming AMEL inactivation in Bufonidae. AMEL pseudogenes in modern bufonids also exhibited remarkably high 86–93% sequence identity among each other, with only a slight increase in substitution rate and relaxation of selective pressure, in comparison to functional copies in other anurans. Moreover, using selection intensity estimates and synonymous substitution rates, analysis of functional and pseudogenized AMEL resulted in an estimated inactivation window of 46-60 MYA in the lineage leading to modern true toads, a timeline that coincides with the rise of the family Bufonidae.

Kordia aestuariivivens sp. nov. and Olleya sediminilitoris sp. nov., isolated from a tidal flat

2021 ◽  
Vol 71 (6) ◽  
Author(s):  
Sooyeon Park ◽  
Jung-Sook Lee ◽  
Wonyong Kim ◽  
Jung-Hoon Yoon
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Tidal Flat ◽  
Genomic Sequences ◽  
Rrna Gene ◽  
Phenotypic Properties ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Type Strains

Two Gram-stain-negative and non-flagellated bacteria, YSTF-M3T and YSTF-M6T, were isolated from a tidal flat from Yellow Sea, Republic of Korea, and subjected to a polyphasic taxonomic study. Neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that strains YSTF-M3T and YSTF-M6T belong to the genera Kordia and Olleya of the family Flavobacteriaceae , respectively. The 16S rRNA gene sequence similarities between strain YSTF-M3T and the type strains of Kordia species and between strain YSTF-M6T and the type strains of Olleya species were 94.1–98.4 and 97.3–98.3 %, respectively. The ANI and dDDH values between genomic sequences of strain YSTF-M3T and the type strains of five Kordia species and between those of strain YSTF-M6T and the type strains of three Olleya species were in ranges of 77.0–83.2 and 20.7–27.1 % and 79.4–81.5 and 22.3–23.9 %, respectively. The DNA G+C contents of strain YSTF-M3T and YSTF-M6T from genomic sequences were 34.1 and 31.1 %, respectively. Both strains contained MK-6 as predominant menaquinone and phosphatidylethanolamine as only major phospholipid identified. Differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strains YSTF-M3T and YSTF-M6T are separated from recognized species of the genera Kordia and Olleya , respectively. On the basis of the data presented, strains YSTF-M3T (=KACC 21639T=NBRC 114499T) and YSTF-M6T (=KACC 21640T=NBRC 114500T) are considered to represent novel species of the genera Kordia and Olleya , respectively, for which the names Kordia aestuariivivens sp. nov. and Olleya sediminilitoris sp. nov. are proposed.

Glacieibacterium frigidum gen. nov., sp. nov., a novel member of the family Sphingosinicellaceae isolated from a glacier

2021 ◽  
Vol 71 (7) ◽  
Author(s):  
Qing Liu ◽  
Lei-Lei Yang ◽  
Hong-Can Liu ◽  
Guo-Qing Zhang ◽  
Yu-Hua Xin
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Polar Lipids ◽  
Rrna Gene ◽  
The Tibetan Plateau ◽  
Unidentified Phospholipid ◽  
Content Type ◽  
Link Type ◽  
The Family

A novel Gram-stain-negative, rod-shaped, yellow bacterium, designated as LB1R16T, was isolated from the Laigu glacier on the Tibetan Plateau, PR China. Strain LB1R16T was catalase-positive, oxidase-negative and grew at 0–28 °C, pH 6.0–8.0 and in the absence of NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain LB1R16T belongs to the family Sphingosinicellaceae but formed an independent lineage. The highest level of 16S rRNA gene sequence similarities were found to Polymorphobacter arshaanensis DJ1R-1T (95.24 %), Sphingoaurantiacus capsulatus YLT33T (94.78 %) and Sandarakinorhabdus limnophila DSM 17366T (94.67 %). The genomic DNA G+C content was 68.8 mol%. The main cellular fatty acids were summed feature 8 (C18 : 1  ω7c/C18 : 1  ω6c), summed feature 3 (C16 : 1  ω7c/C16 : 1  ω6c), C16 : 0 and C12 : 0-OH. The respiratory quinone was ubiquinone-10. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, one sphingoglycolipid, one unidentified aminolipid, one unidentified phospholipid and two unidentified polar lipids, which were different from the type strains of Polymorphobacter arshaanensis , Sphingoaurantiacus capsulatus and Sandarakinorhabdus limnophila . Based on a polyphasic approach, a novel species of a new genus, Glacieibacterium frigidum gen. nov., sp. nov., within the family Sphingosinicellaceae is proposed. The type strain is LB1R16T (=CGMCC 1.11941T=NBRC 113873T).

Sediminihaliea albiluteola gen. nov., sp. nov., a new member of the family Halieaceae, isolated from marine sediment

2021 ◽  
Vol 71 (8) ◽  
Author(s):  
Shan Jiang ◽  
Feng-Bai Lian ◽  
You-Yang Sun ◽  
Xiao-Kui Zhang ◽  
Zong-Jun Du
Keyword(s):  
Type Species ◽  
Phylogenetic Analyses ◽  
Rrna Gene ◽  
Gene Sequences ◽  
Unidentified Phospholipid ◽  
Respiratory Quinone ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Sequence Similarities

A Gram-stain-negative, rod-shaped and facultatively aerobic bacterial strain, designated F7430T, was isolated from coastal sediment collected at Jingzi Wharf in Weihai, PR China. Cells of strain F7430T were 0.3–0.4 µm wide, 2.0–2.6 µm long, non-flagellated, non-motile and formed pale-beige colonies. Growth was observed at 4–40 °C (optimum, 30 °C), pH 6.0–9.0 (optimum, pH 7.5–8.0) and at NaCl concentrations of 1.0–10.0 % (w/v; optimum, 1.0 %). The sole respiratory quinone of strain F7430T was ubiquinone 8 and the predominant cellular fatty acids were summed feature 8 (C18 : 1  ω7c / C18 : 1  ω6c; 60.7 %), summed feature 3 (C16 : 1  ω7c/C16 : 1  ω6c; 30.2 %) and C15 : 0 iso (13.9 %). The polar lipids of strain F7430T consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unidentified phospholipid and three unidentified lipids. Results of 16S rRNA gene sequences analyses indicated that this strain belonged to the family Halieaceae and had high sequence similarities to Parahaliea aestuarii JCM 51547T (95.3 %) and Halioglobus pacificus DSM 27932T (95.2 %) followed by 92.9–95.0 % sequence similarities to other type species within the aforementioned family. The rpoB gene sequences analyses indicated that the novel strain had the highest sequence similarities to Parahaliea aestuarii JCM 51547T (82.2 %) and Parahaliea mediterranea DSM 21924T (82.2 %) followed by 75.2–80.5 % sequence similarities to other type species within this family. Phylogenetic analyses showed that strain F7430T constituted a monophyletic branch clearly separated from the other genera of family Halieaceae . Whole-genome sequencing of strain F7430T revealed a 3.3 Mbp genome size with a DNA G+C content of 52.6 mol%. The genome encoded diverse metabolic pathways including the Entner–Doudoroff pathway, assimilatory sulphate reduction and biosynthesis of dTDP-l-rhamnose. Based on results from the current polyphasic study, strain F7430T is proposed to represent a novel species of a new genus within the family Halieaceae , for which the name Sediminihaliea albiluteola gen. nov., sp. nov. is proposed. The type strain of the type species is F7430T (=KCTC 72873T=MCCC 1H00420T).

Reclassification of Haloactinobacterium glacieicola as Occultella glacieicola gen. nov., comb. nov., of Haloactinobacterium album as Ruania alba comb. nov, with an emended description of the genus Ruania, recognition that the genus names Haloactinobacterium and Ruania are heterotypic synonyms and description of Occultella aeris sp. nov., a halotolerant isolate from surface soil sampled at an ancient copper smelter

2021 ◽  
Vol 71 (4) ◽  
Author(s):  
Peter Schumann ◽  
Franziska Kalensee ◽  
Jialan Cao ◽  
Alexis Criscuolo ◽  
Dominique Clermont ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Type Species ◽  
Copper Smelter ◽  
Amino Acid Identity ◽  
Content Type ◽  
Link Type ◽  
Average Amino Acid Identity ◽  
The Family ◽  
Emended Description ◽  
Copper Mines

In the course of screening the surface soils of ancient copper mines and smelters (East Harz, Germany) an aerobic, non-motile and halotolerant actinobacterium forming small rods or cocci was isolated. The strain designated F300T developed creamy to yellow colonies on tryptone soy agar and grew optimally at 28 °C, pH 7–8 and with 0.5–2 % (m/v) NaCl. Its peptidoglycan was of type A4α l-Lys–l-Glu (A11.54). The menaquinone profile was dominated by MK-8(II, III-H4) and contained minor amounts of MK-8(H2), MK-8(H6) and MK-9(H4). The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, mono and diacylated phosphatidylinositol dimannosides, and components that were not fully characterized, including two phospholipids, two glycolipids and an uncharacterized lipid. Major whole-cell sugars were rhamnose and ribose. The fatty acid profile contained mainly iso and anteiso branched fatty acids (anteiso-C15 : 0, iso-C14 : 0) and aldehydes/dimethylacetals (i.e. not fatty acids). Sequence analysis of its genomic DNA and subsequent analysis of the data placed the isolate in the group currently defined by members of the genera Ruania and Haloactinobacterium (family Ruaniaceae , order Micrococcales ) as a sister taxon to the previously described species Haloactinobacterium glacieicola , sharing an average nucleotide identity and average amino acid identity values of 85.3 and 85.7 %, respectively. Genotypic and chemotaxonomic analyses support the view that strain F300T (=DSM 108350T=CIP 111667T) is the type strain of a new genus and new species for which the name Occultella aeris gen. nov., sp. nov. is proposed. Based on revised chemotaxonomic and additional genome based data, it is necessary to discuss and evaluate the results in the light of the classification and nomenclature of members of the family Ruaniaceae , i.e. the genera Haloactinobacterium and Ruania . Consequently, the reclassification of Haloactinobacterium glacieicola as Occultella glacieicola comb. nov. and Haloactinobacterium album as Ruania alba comb. nov., with an emended description of the genus Ruania are proposed.

Muriicola soli sp. nov., isolated from soil

2021 ◽  
Vol 71 (7) ◽  
Author(s):  
Hye Jeong Kang ◽  
Min-Kyeong Kim ◽  
Su Gwon Roh ◽  
Seung Bum Kim
Keyword(s):  
Related Species ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Optimum Ph ◽  
Genomic Characterization

A Gram-stain-negative, oxidase-positive, catalase-positive, aerobic, orange-pigmented, rod-shaped and non-motile bacterium designated strain MMS17-SY002T was isolated from island soil. The isolate grew at 20–37 °C (optimum, 30 °C), at pH 6.0–9.5 (optimum, pH 7) and in the presence of 0.5–4.0 % (w/v) NaCl (optimum, 2.0 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MMS17-SY002T was mostly related to the genus Muriicola of the family Flavobacteriaceae and had highest sequence similarity of 96.82 % to Muriicola marianensis A6B8T and Muriicola jejuensis EM44T, but formed a distinct phylogenetic line within the genus. Chemotaxonomic analyses showed that menaquinone 6 was the predominant isoprenoid quinone, the major fatty acids were iso-C15 : 1 G and iso-C15 : 0, and the diagnostic polar lipid was phosphatidylethanolamine. The genomic DNA G+C content was 42.4 mol%. Strain MMS17-SY002T could be distinguished from related species by the combination of trypsin, α-chymotrypsin, acid phosphatase, naphthol-AS-BI-phosphohydrolase, α-galactosidase, β-galactosidase and β-glucosidase activities. The orthologous average nucleotide identity between the genomes of strain MMS17-SY002T and M. jejuensis and that between the strain and M. marianensis A6B8T were 73.26 and 73.33%, respectively, thus confirming the separation of the strain from related species at species level. Based on the phenotypic, phylogenetic, chemotaxonomic and genomic characterization, MMS17-SY002T should be recognized as a novel species of the genus Muriicola , for which the name Muriicola soli sp. nov. is proposed. The type strain is MMS17-SY002T (=KCTC 62790T=JCM 32370T).

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