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Instead, the full date and page number is required for a correct reference. Guides Resources Citation styles. How to format your references using the Journal of Financial Economics citation style This is a short guide how to format citations and the bibliography in a manuscript for Journal of Financial Economics. Using reference management software Typically you don't format your citations and bibliography by hand. EndNote Find the style here: output styles overview Mendeley, Zotero, Papers , and others The style is either built in or you can download a CSL file that is supported by most references management programs.

Check the instructions to authors if the publisher offers a LaTeX template for this journal. Journal articles Those examples are references to articles in scholarly journals and how they are supposed to appear in your bibliography. A journal article with 1 author. Felten, D. IRBs: going too far or not far enough?

Science , —9; author reply A journal article with 2 authors. Giovannoni, S. Seasonality in ocean microbial communities. Science , — A journal article with 3 authors. Pichersky, E. A journal article with 4 or more authors. Park, S. Langton, R. Stability and Control of Aircraft Systems. The resulting acetaldehyde, acetate, ethanol and H 2 from acetylene metabolism are secreted into the external milieu by pure cultures, and in mixed associations can then serve as carbon and energy substrates for other opportunist microorganisms present Table 1 and Fig. Acetylenotrophy-driven microbial food web.

Sources of acetylene include known and hypothetical green circles sources. Studies to date have shown that the AH of P. Pelobacter sp. In addition, we experimentally showed that Pelobacter sp. Syntenic map of acetylene hydratase ahy and flanking genes in Pelobacter sp. The acetylene-metabolizing enzymes from aerobic acetylenotrophs have not been fully characterized. Together, these observations indicate that the AH of aerobic acetylenotrophs are unique and that this is a heterogeneous group of enzymes. As stated above, the first report of acetylene-fueled growth dates to for an aerobic mycobacterium isolated from soils in Germany Birch-Hirschfeld Since that finding, 9 papers have documented the consumption of acetylene from soil, sediment, and groundwater samples Table 1 and resulted in the isolation of 15 pure cultures of acetylenotrophs Table 2.

Many of the early incubations of environmental samples where acetylene uptake was observed were originally designed for acetylene-based denitrification or nitrogen-fixation assays, with acetylene consumption being a spurious observation. The observations of acetylenotrophy in environmental samples, summarized in Table 1 , show that this metabolism is distributed widely amongst geochemical conditions, from freshwater to hypersaline, surface to subsurface, soils to aquifers, and anoxic to oxic ecosystems.

In addition, further studies investigated the potential for aerobic or anaerobic acetylene uptake in soils with varying results.

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Terry and Duxbury found that soils could consume acetylene under both anaerobic and aerobic conditions. Tam, Mayfield and Inniss and Topp and Germon compared the ability of stream sediments and soils to consume acetylene and found that only aerobic incubations could do so, whereas under anaerobic conditions no uptake was observed.

This observation has held in other surveys of the ubiquity of acetylene consumption. Acetylenotrophy, e. Application of this primer set to DNA extracts from numerous field samples revealed that ahy was even less common, with only 63 of samples testing 9. A likely source of acetylene at the NAWC site could be attributed to abiotic dehalogenation reactions with TCE and reduced iron minerals. Consumption of acetylene by NAWC groundwater microorganisms was observed in samples collected in and Table 1.

To date, 15 acetylenotrophic bacterial strains have been obtained that either use acetylene as either their sole carbon and energy source or with low concentrations of supplemental yeast extract during anaerobic or aerobic metabolism Table 2. However, this is at odds with the frequency of acetylene degradation observed in environmental samples. Acetylenotrophs span the Actinobacteria, Proteobacteria , and Firmicutes phyla Table 2. However, many of the early strains were identified by phenotypic characteristics and not available in culture collections, therefore, their phylogeny cannot be confirmed use DNA molecular markers.

Of particular interest, is the isolation of an acetylenotrophic strain from the Firmicutes phyla Tam, Mayfield and Inniss This strain is not available in culture collections, so little is known about its ability to transform acetylene or its metabolic versatility. Acetylenotrophic members of the Actinobacteria have been repeatedly isolated under aerobic conditions, although not always reported in the literature, for example, Rhodococcus rhodochrous strain PNKb1 was isolated by Woods in but no peer-reviewed paper documented the finding.

We hypothesize that more acetylenotrophs may be out there but the lack of testing for this metabolism has hindered their discovery. Presence of members of the Actinobacteria was initially surprising as these taxa are typically characterized as aerobic and includes the majority of known aerobic acetylenotrophs Table 2. However, the aerobic acetylenotroph Rhodococcus rhodochrous strain E5 was originally isolated and cultivated under aerobic conditions but was later shown to degrade acetylene under anaerobic conditions Topp and Germon Together this suggests that members of the Actinobacteria may be more versatile in their oxygen requirements and that acetylenotrophy may confer metabolic versatility on these organisms if oxygen becomes limiting.

In addition, although SV7 grew at the expense of acetylene, its DNA did not amplify with Pelobacter -specific ahy primers, and the culture formed different intermediates and end products acetate, formate, carbon dioxide, methane than P.

The Metal-Driven Biogeochemistry of Gaseous Compounds in the Environment

The presence of so many acetylene-consuming environmental samples and strains suggests that this metabolism might be more wide spread than previously known discussed more below. However, to date we lack quantitative information on the abundance of acetylenotrophic organisms as estimates for population size using most-probable-number MPN assays or quantitative PCR for AH genes have not been performed.

To fully understand the contribution of acetylenotrophs estimates of population size are needed. In addition, from these observations we hypothesize that acetylenotrophs could play an important ecological and biogeochemical role by fueling a microbial food web on modern Earth Fig. Acetylenotrophic strains produce ethanol, acetate, acetaldehyde, and H 2 Table 1B as byproducts of their metabolism. These substrates can, in mixed systems e.

The presence of other organisms might be required for acetylenotrophy to be favorable through a syntrophic relationship. The fact that both anaerobic and aerobic acetylenotrophs have been found around the world in diverse environments and that their capacity to grow on acetylene is dependent on different AHs implies that this trait has been around for quite some time. Admittedly, until very recently these ideas seem a bit tenuous considering that there are so few acetylenotrophic strains Table 2 , and that much of the work on this group of organisms ceased well before the genomics revolution came into its own.

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Yet it is from our genetic studies of P. Neighbor-joining tree showing the relationship between amino acid sequences for known and select putative AH and dehydrogenase proteins. All proteins shown contain both a molybdopterin-binding domain conserved protein domain family cd and a molybdopterin-binding C-terminal cd Putative AH containing a molybdopterin-binding acetylene hydratase cd and a molybdopterin-binding acetylene hydratase C-terminal cd are indicated with green squares and known AH are indicated by red triangles.

The phylogenetic affiliation of the organisms is indicated by color. The tree was constructed by downloading amino acid aa sequences that matched a key-word search of 'acetylene hydratase' in the NCBI GenBank database.

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  4. Additional dehydrogenase sequences were included for reference. Sequences were aligned in Geneious v. The tree was constructed using the Geneious Tree Builder with neighbor-joining methods and Jukes-Cantor distance model. Many complete bacterial genomes and environmental metagenomes now reside in genetic databases where no such information existed until quite recently, providing a wealth of data that can be interrogated for the presence of new acetylenotrophs. Indeed, merely entering the keywords 'acetylene hydratase' into the National Center for Biotechnology Information NCBI database keyword search results in over 2, word-annotations for putative AH proteins whereas there were less than five as recently as two years ago NCBI Resource Coordinators These annotations span the Bacteria and Archaea kingdoms, including uncultured organisms from metagenomes Fig.

    Interestingly, these annotated sequences share fairly low nucleotide and amino acid identities with the sequences of Pelobacter ahy. For example, the ahy of P. These putative AH genes were identified through computational predictions and it is not clear if these sequences actually encode a functional AH or if this diverse array of microorganisms can be sustained by an acetylenotrophic metabolism.

    Nonetheless, the fact that there are now so many plausible 'hits' highlights the need for closer investigation as to the gene sequence and structural nature of these ahy genes and AH proteins. If they were found to be reasonable candidates for viable ahy genes and functional proteins, further experimental effort demonstrating a capacity for acetylenotrophy in some of the annotated species having annotated ahy genes would be warranted.

    Preliminary efforts have begun to investigate whether this growing list of annotated ahy genes in the NCBI database are viable or a just a mis-annotation by the computational pipelines in place to annotate bacterial and archaeal genomes e. The challenge here lies in the low nucleotide identities. An intriguing question is why acetylenotrophy has been maintained in multiple microorganisms when acetylene is found at very low concentrations in the environment.

    It is particularly interesting that Pelobacter strains are maintaining genes for acetylene metabolism that are flanked by HGT elements. We hypothesize that in addition to the known anthropogenic and combustion sources that contribute to low concentrations of acetylene on modern Earth as described above , there may be additional unidentified sources. This transient acetylene could be so rapidly degraded by proximately located acetylenotrophs in nature that it forms a 'hidden' acetylene cycle. Such a hidden acetylene cycle would then favor the maintenance of heterogeneous enzymes for acetylene metabolisms that are found in the phylogenetically diverse aerobic and anaerobic acetylenotrophs.

    In addition, this would also provide an explanation for the fact that Pelobacter sp. The presence of both AH and N 2 ase could provide a competitive advantage for these organisms with each providing the organism carbon and energy and nitrogen source, respectively. In addition, the presence of a hidden acetylene cycle could provide the base of a food web for other organisms, such as methanogens, that utilize end products or intermediates from acetylenotrophy Fig.

    Absent a strong environmental source of free acetylene to the environment, there are several possible routes for acetylene to be created from intermediate precursor materials that after being metabolized is readily consumed by acetylenotrophs, hereby precluding its release into the open environment. Marine algae produce trace amounts 1,2-dibromoethene Gribble ; Gribble , which can be degraded to acetylene by pure cultures of methanogenic bacteria Belay and Daniels An additional potential oceanic source of acetylene-precursors is dimethylsulfoniopropionate DMSP; Fig.

    In the ocean, DMSP is released as a product of phytoplankton cell lysis, which is then broken down into more volatile compounds by other bacteria into dimethyl sulfide DMS , acetate, acetaldehyde, acrylate and ethene Plettner, Steinke and Malin ; Reisch, Moran and Whitman One possible cryptic source of acetylene is conversion of acrylate to acetylene and CO 2 decomposition Fig. Acrylic acid is hypothesized to be microbially oxidized to acetylene thereby potentially fueling a hidden acetylene cycle.