scholarly journals Prokaryote diversity and taxonomy: current status and future challenges

2004 ◽  
Vol 359 (1444) ◽  
pp. 623-638 ◽  
Author(s):  
Aharon Oren
Keyword(s):  
Small Subunit ◽  
Current Status ◽  
Environmental Significance ◽  
Species Classification ◽  
Phenotypic Properties ◽  
Species Definition ◽  
Small Subunit Rdna ◽  
Future Challenges ◽  
Living Organisms

The prokaryotes are by far the most abundant organisms inhabiting planet Earth. They are also by far the most diverse, both metabolically and phylogenetically; they encompass the Bacteria and the Archaea, two out of the three major divisions of living organisms. The current prokaryote species classification is based on a combination of genomic and phenotypic properties. The recommended cut–off value of 70% DNA–DNA similarity to delineate species signifies an extremely broad species definition for the prokaryotes compared with the higher eukaryotes. The number of validly named species of prokaryotes is currently slightly more than 6200. However, on the basis of small–subunit rDNA characterization of whole communities and other approaches, the more exact number of species present can be inferred to be at least two orders of magnitude larger. Classic culturing methods based on colony formation on agar are generally unsatisfactory for the recovery of bacteria from the environment. Many of the most abundant prokaryotes in nature have not yet been brought into culture. Some of these may thrive by means of as yet unknown modes of energy generation. Several novel methods have recently enabled the isolation of some interesting organisms of environmental significance. A better coverage of the prokaryote diversity on Earth depends on such innovative approaches, combined with appropriate funding.

scholarly journals Characterization of the marine propionate-degrading, sulfate-reducing bacterium Desulfofaba fastidiosa sp. nov. and reclassification of Desulfomusa hansenii as Desulfofaba hansenii comb. nov.

2004 ◽  
Vol 54 (2) ◽  
pp. 393-399 ◽  
Author(s):  
Lone Abildgaard ◽  
Niels Birger Ramsing ◽  
Kai Finster
Keyword(s):  
Small Subunit ◽  
Phenotypic Traits ◽  
Rrna Gene ◽  
Sulfate Reducing ◽  
Dissimilatory Sulfite Reductase ◽  
Small Subunit Rdna ◽  
Reductase Gene ◽  
Morphological And Physiological Traits ◽  
Dissimilatory Sulfite Reductase Gene

A rod-shaped, slightly curved sulfate reducer, designated strain P2T, was isolated from the sulfate–methane transition zone of a marine sediment. Cells were motile by means of a single polar flagellum. The strain reduced sulfate, thiosulfate and sulfite to sulfide and used propionate, lactate and 1-propanol as electron donors. Strain P2T also grew by fermentation of lactate. Propionate was oxidized incompletely to acetate and CO2. The DNA G+C content was 48·8mol%. Sequence analysis of the small-subunit rDNA and the dissimilatory sulfite reductase gene revealed that strain P2T was related to the genera Desulfonema, Desulfococcus, Desulfosarcina, ‘Desulfobotulus’, Desulfofaba, Desulfomusa and Desulfofrigus. These genera include incomplete as well as complete oxidizers of substrates. Strain P2T shared important morphological and physiological traits with Desulfofaba gelida and Desulfomusa hansenii, including the ability to oxidize propionate incompletely to acetate. The 16S rRNA gene similarities of P2T to Desulfofaba gelida and Desulfomusa hansenii were respectively 92·9 and 91·5%. Combining phenotypic and genotypic traits, we propose strain P2T to be a member of the genus Desulfofaba. The name Desulfofaba fastidiosa sp. nov. (type strain P2T=DSM 15249T=ATCC BAA-815T) is proposed, reflecting the limited number of substrates consumed by the strain. In addition, the reclassification of Desulfomusa hansenii as a member of the genus Desulfofaba, Desulfofaba hansenii comb. nov., is proposed. A common line of descent and a number of shared phenotypic traits support this reclassification.

scholarly journals Current status and future challenges for molecular imaging

2017 ◽  
Vol 375 (2107) ◽  
pp. 20170023 ◽  
Author(s):  
Carolyn J. Anderson ◽  
Jason S. Lewis
Keyword(s):  
Molecular Imaging ◽  
Molecular Biology ◽  
Royal Society ◽  
Molecular Level ◽  
Current Status ◽  
Timely Manner ◽  
Society Meeting ◽  
Non Invasive ◽  
Future Challenges ◽  
Living Organisms

Molecular imaging (MI), used in its wider sense of biology at the molecular level, is a field that lies at the intersection of molecular biology and traditional medical imaging. As advances in medicine have exponentially expanded over the last few decades, so has our need to better understand the fundamental behaviour of living organisms in a non-invasive and timely manner. This commentary draws from topics the authors addressed in their presentations at the 2017 Royal Society Meeting ‘Challenges for chemistry in molecular imaging’, as well as a discussion of where MI is today and where it is heading in the future. This article is part of the themed issue ‘Challenges for chemistry in molecular imaging’.

Morphological and molecular characterization of Aphelenchoides fujianensis n. sp. (Nematoda: Aphelenchoididae) from Pinus massoniana in China

Zootaxa ◽  
2010 ◽  
Vol 2509 (1) ◽  
pp. 39 ◽  
Author(s):  
KAN ZHUO ◽  
RUQIANG CUI ◽  
WEIMIN YE ◽  
MEI LUO ◽  
HONGHONG WANG ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Pinus Massoniana ◽  
Small Subunit ◽  
Mt Dna ◽  
Lateral Field ◽  
Small Subunit Rdna ◽  
Aphelenchoides Besseyi ◽  
Group 3 ◽  
Morphological And Molecular Characterization

Aphelenchoides fujianensis n. sp. is described and illustrated from a dead Pinus massoniana based on morphology and molecular analyses of the near-full-length small subunit rDNA gene and partial cytochrome oxidase subunit I of mitochondrial DNA. This new species belongs to the Group 3 of Aphelenchoides species sensu Shahina with star-shaped tail terminus and is characterised by a relatively long body (653–843 μ m in the male and 803–941 μ m in the female) and four lateral incisures in the lateral field. The male has relatively large spicules (24–30 μ m). The female has elongate postvulval uterine sac (extending ca 32–44% of vulva-anus distance), usually with sperms. Both male and female have star-shaped mucro. It is distinguished from other species by postvulval uterine sac length, a and c ratios, and spicule size and shape. Molecular analysis reveals that this species has unique 18S and mt-DNA sequences, and is closest to Aphelenchoides besseyi in dendrograms inferred using both markers. The identification codes of OEPP/EPPO for A. fujianensis n. sp. are: A1-B2-C1-D1/3-E1-F1/2.

scholarly journals Identification and Characterization of Verticillium longisporum Lineage A1/D1 from Brassica Crops in Manitoba, Canada

2020 ◽  
Vol 21 (10) ◽  
pp. 3499
Author(s):  
Zhongwei Zou ◽  
Vikram Bisht ◽  
W. G. Dilantha Fernando
Keyword(s):  
Small Subunit ◽  
Pathogenicity Test ◽  
Brassica Napus L ◽  
Gene Characterization ◽  
5.8S Rdna ◽  
Verticillium Longisporum ◽  
Brassica Crops ◽  
Small Subunit Rdna ◽  
Pcr Rflp

Verticillium stripe in canola (Brassica napus L.) caused by Verticillium longisporum was first reported in Manitoba in 2014. In this study, Brassica crops including canola, mustard (Brassica juncea) and radish (Raphanus sativus) with visible symptoms of Verticillium stripe were collected from Portage La Prairie, Manitoba, and the pathogens were isolated. Isolates from canola and radish were identified to V. longisporum, which produced longer conidia (7.92–12.00 µm) than Verticillium dahliae (4.32–7.04 µm). An isolate derived from mustard was characterized as V. dahliae. Molecular diagnostics with 18S rDNA, 5.8S rDNA and mating-type marker primers were used to confirm the identification of Verticillium isolates. PCR-RFLP of the mitochondrial small subunit rDNA and the cytochrome b gene were also employed to distinguish V. longisporum isolates from V. dahliae. The multi-gene characterization approach allowed for lineage determination, and V. longisporum isolates from canola and radish were in the A1/D1 group. Isolates of Verticillium longisporum from canola inoculated onto the canola cultivar ‘Westar’ caused symptoms of stem striping, stunting and short plants. Re-isolated fungal strains from infected stems were again inoculated onto canola plants, in order to confirm that V. longisporum was the causal agent of Verticillium stripe disease in the pathogenicity test.

Environmental significance of atrazine in aqueous systems and its removal by biological processes: an overview

2013 ◽  
Vol 8 (2) ◽  
pp. 159-178 ◽  
Keyword(s):  
Drinking Water ◽  
Ground Water ◽  
Water Environment ◽  
Biological Processes ◽  
Biological Degradation ◽  
Environmental Significance ◽  
Carbon And Nitrogen ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio ◽  
Living Organisms

Atrazine, a chlorinated s-triazine group of herbicide is one of the most widely used pesticides in the World. Due to its extensive use, long half-life and various toxic properties, it has very high environmental significance. Up to 22 mg l-1 of atrazine was found in ground water whereas permissible limit of atrazine is in ppb level in drinking water. As per Indian standard there should not be any pesticide present in drinking water. Among many other treatment processes available, Incineration, adsorption, chemical treatment, phytoremediation and biodegradation are the most commonly used ones. Biological degradation of atrazine depends upon various factors like the operating environment, external carbon and nitrogen sources, carbon/ nitrogen ratio (C/N), water content and the bacterial strain. Although, general atrazine degradation pathways are available, the specific pathways in specific conditions are not yet clearly defined. In this paper extensive review has been made on the occurrence of atrazine in surface and ground water bodies, probable sources and causes of its occurrence in water environment, the toxicity of atrazine on various living organisms and its removal by biological processes.

Theileria parva ribosomal internal transcribed spacer sequences exhibit extensive polymorphism and mosaic evolution: application to the characterization of parasites from cattle and buffalo

Parasitology ◽  
1999 ◽  
Vol 118 (6) ◽  
pp. 541-551 ◽  
Author(s):  
N. E. COLLINS ◽  
B. A. ALLSOPP
Keyword(s):  
Genetic Recombination ◽  
Large Subunit ◽  
Small Subunit ◽  
Internal Transcribed Spacers ◽  
Rrna Genes ◽  
Gene Pools ◽  
Theileria Parva ◽  
Causative Agents ◽  
Internal Transcribed Spacer Sequences

We sequenced the rRNA genes and internal transcribed spacers (ITS) of several Theileria parva isolates in an attempt to distinguish between the causative agents of East coast fever and Corridor disease. The small subunit (SSU) and large subunit (LSU) rRNA genes from a cloned T. p. lawrencei parasite were sequenced; the former was identical to that of T. p. parva Muguga, and there were minor heterogeneities in the latter. The 5·8S gene sequences of 11 T. parva isolates were identical, but major differences were found in the ITS. Six characterization oligonucleotides were designed to hybridize within the variable ITS1 region; 93·5% of T. p. parva isolates examined were detected by probe TPP1 and 81·8% of T. p. lawrencei isolates were detected by TPL2 and/or TPL3a. There was no absolute distinction between T. p. parva and T. p. lawrencei and the former hybridized with fewer of the probes than did the latter. It therefore seems that a relatively homogenous subpopulation of T. parva has been selected in cattle from a more diverse gene pool in buffalo. The ITSs of both T. p. parva and T. p. lawrencei contained different combinations of identifiable sequence segments, resulting in a mosaic of segments in any one isolate, suggesting that the two populations undergo genetic recombination and that their gene pools are not completely separate.

scholarly journals Ligand-protected gold/silver superatoms: current status and emerging trends

2020 ◽  
Vol 11 (45) ◽  
pp. 12233-12248
Author(s):  
Haru Hirai ◽  
Shun Ito ◽  
Shinjiro Takano ◽  
Kiichirou Koyasu ◽  
Tatsuya Tsukuda
Keyword(s):  
Current Status ◽  
Synthesis And Characterization ◽  
Emerging Trends ◽  
Gold Silver

This perspective summarizes the current status and emerging trends in synthesis and characterization of ligand-protected gold/silver superatoms.

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