A review of the microgastropod genus Systenostoma Bavay & Dautzenberg, 1908 and a new subterranean species from China (Gastropoda,Pulmonata, Hypselostomatidae)

A review of the microgastropod genus Systenostoma is provided. Thai and Malaysian species are transferred to a new genus, Angustopila (type species: Systenostoma tamlod Panha & Burch, 1999). A new subterranean Angustopila species is described here. Conchologically, the new species is most similar to the cave-dwelling, Thai A. tamlod (Panha & Burch, 1999). One Thai species (Systenostoma edentata) is transferred to the genus Hypselostoma. Vietnamese members remain in the genus Tonkinospira (nomen novum) for Systenostoma Bavay & Dautzenberg, 1908 (non Systenostoma Marsson, 1887). A comprehensive map of former Systenostoma species is presented. SEM and NanoCT images, including a video of A. huoyani sp. n. internal shell morphology, provide novel perspectives of the shells of Angustopila and of the scarcely known Vietnamese Tonkinospira species. The biology of these snails is not yet known but collection localities suggest a troglophilic ecology.     

Microbial response to reinjection of produced water in an oil reservoir

The microbial response to produced water reinjection (PWRI) in a North Sea oil field was investigated by a combination of cultivation and culture-independent molecular phylogenetic techniques. Special emphasise was put on the relationship between sulphate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB), and results were used to evaluate the possibility of nitrate treatment as a souring management tool during PWRI. Samples were collected by reversing the flow of the injection water, which provided samples from around the injection area. The backflowed samples were compared to produced water from the same platform and to backflowed samples from a biocide-treated seawater injector, which was the previous injection water treatment of the PWRI well. Results showed that reinjection of produced water promoted growth of thermophilic SRB. Thermophilic fatty acid oxidising NRB and potential nitrate-reducing sulphide-oxidising bacteria were also found. The finding of thermophilic NRB makes nitrate treatment during PWRI possible, although higher nitrate concentration will be necessary to compensate for the increased SRB activity.     

Structural and functional comparison of HemN to other radical SAM enzymes

Radical SAM enzymes have only recently been recognized as an ancient family sharing an unusual radical-based reaction mechanism. This late appreciation is due to the extreme oxygen sensitivity of most radical SAM enzymes, making their characterization particularly arduous. Nevertheless, realization that the novel apposition of the established cofactors S-adenosylmethionine and [4Fe-4S] cluster creates an explosive source of catalytic radicals, the appreciation of the sheer size of this previously neglected family, and the rapid succession of three successfully solved crystal structures within a year have ensured that this family has belatedly been noted. In this review, we report the characterization of two enzymes: the established radical SAM enzyme, HemN or oxygen-independent coproporphyrinogen III oxidase from Escherichia coli, and littorine mutase, a presumed radical SAM enzyme, responsible for the conversion of littorine to hyoscyamine in plants. The enzymes are compared to other radical SAM enzymes and in particular the three reported crystal structures from this family, HemN, biotin synthase and MoaA, are discussed.     

Ecological restoration of cleared agricultural land in Gondwana Link: lifting the bar at 'Peniup'

Summary  Large scale ecological restoration in a highly heterogeneous and species-rich landscape requires big commitment to fine scale planning. In the southwest of Western Australia, in the Fitz-Stirling area of Gondwana Link, the Peniup Restoration project aimed to improve on such works. A multi-faceted approach was employed to re-establish a self-replicating biologically diverse plant system, ecologically informed in its design and consistent with the heterogeneous mosaic of plant associations found in the surrounding landscape. Outcomes from the project included a 950-ha restoration map composed of nine newly developed soil landscape/vegetation associations. A new 6 m wide direct seeding machine was developed to improve delivery and spatial configuration of establishing plants. These two developments were put to the test in 2008 through a 250 ha biodiverse carbon-funded restoration effort. This paper summarises the approaches used and initial results of those works.     

Microbial analysis of backflowed injection water from a nitrate-treated North Sea oil reservoir

Reservoir souring in offshore oil fields is caused by hydrogen sulphide (H₂S) produced by sulphate-reducing bacteria (SRB), most often as a consequence of sea water injection. Biocide treatment is commonly used to inhibit SRB, but has now been replaced by nitrate treatment on several North Sea oil fields. At the Statfjord field, injection wells from one nitrate-treated reservoir and one biocide-treated reservoir were reversed (backflowed) and sampled for microbial analysis. The two reservoirs have similar properties and share the same pre-nitrate treatment history. A 16S rRNA gene-based community analysis (PCR-DGGE) combined with enrichment culture studies showed that, after 6 months of nitrate injection (0.25 mM NO₃ ⁻), heterotrophic and chemolithotrophic nitrate-reducing bacteria (NRB) formed major populations in the nitrate-treated reservoir. The NRB community was able to utilize the same substrates as the SRB community. Compared to the biocide-treated reservoir, the microbial community in the nitrate-treated reservoir was more phylogenetically diverse and able to grow on a wider range of substrates. Enrichment culture studies showed that SRB were present in both reservoirs, but the nitrate-treated reservoir had the least diverse SRB community. Isolation and characterisation of one of the dominant populations observed during nitrate treatment (strain STF-07) showed that heterotrophic denitrifying bacteria affiliated to Terasakiella probably contributed significantly to the inhibition of SRB. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

NirN Protein from Pseudomonas aeruginosa is a Novel Electron-bifurcating Dehydrogenase Catalyzing the Last Step of Heme d1 Biosynthesis

Heme d₁ plays an important role in denitrification as the essential cofactor of the cytochrome cd₁ nitrite reductase NirS. At present, the biosynthesis of heme d₁ is only partially understood. The last step of heme d₁ biosynthesis requires a so far unknown enzyme that catalyzes the introduction of a double bond into one of the propionate side chains of the tetrapyrrole yielding the corresponding acrylate side chain. In this study, we show that a Pseudomonas aeruginosa PAO1 strain lacking the NirN protein does not produce heme d₁. Instead, the NirS purified from this strain contains the heme d₁ precursor dihydro-heme d₁ lacking the acrylic double bond, as indicated by UV-visible absorption spectroscopy and resonance Raman spectroscopy. Furthermore, the dihydro-heme d₁ was extracted from purified NirS and characterized by UV-visible absorption spectroscopy and finally identified by high-resolution electrospray ionization mass spectrometry. Moreover, we show that purified NirN from P. aeruginosa binds the dihydro-heme d₁ and catalyzes the introduction of the acrylic double bond in vitro. Strikingly, NirN uses an electron bifurcation mechanism for the two-electron oxidation reaction, during which one electron ends up on its heme c cofactor and the second electron reduces the substrate/product from the ferric to the ferrous state. On the basis of our results, we propose novel roles for the proteins NirN and NirF during the biosynthesis of heme d₁.     

MX 2 is a novel regulator of cell cycle in melanoma cells

MX2 protein is a dynamin‐like GTPase2 that has recently been identified as an interferon‐induced restriction factor of HIV‐1 and other primate lentiviruses. A single nucleotide polymorphism (SNP), rs45430, in an intron of the MX2 gene, was previously reported as a novel melanoma susceptibility locus in genome‐wide association studies. Functionally, however, it is still unclear whether and how MX2 contributes to melanoma susceptibility and tumorigenesis. Here, we show that MX2 is differentially expressed in melanoma tumors and cell lines, with most metastatic cell lines showing lower MX2 expression than primary melanoma cell lines and melanocytes. Furthermore, high expression of MX2 RNA in primary melanoma tumors is associated with better patient survival. Overexpression of MX2 reduces in vivo proliferation partially through inhibition of AKT activation, suggesting that it can act as a tumor suppressor in melanoma. However, we have also identified a subset of melanoma cell lines with high endogenous MX2 expression where downregulation of MX2 leads to reduced proliferation. In these cells, MX2 downregulation interfered with DNA replication and cell cycle processes. Collectively, our data for the first time show that MX2 is functionally involved in the regulation of melanoma proliferation but that its function is context‐dependent.     

Red fox takeover of arctic fox breeding den: an observation from Yamal Peninsula, Russia

Here, we report from the first direct observation of a red fox (Vulpes vulpes) intrusion on an arctic fox (Vulpes lagopus) breeding den from the southern Arctic tundra of Yamal Peninsula, Russia in 2007. At the same time, as a current range retraction of the original inhabitant of the circumpolar tundra zone the arctic fox is going on, the red fox is expanding their range from the south into arctic habitats. Thus, within large parts of the northern tundra areas the two species are sympatric which gives opportunities for direct interactions including interference competition. However, direct first-hand observations of such interactions are rare, especially in the Russian Arctic. In the present study, we observed one red fox taking over an arctic fox breeding den which resulted in den abandonment by the arctic fox. On July 19, eight arctic fox pups were observed on the den before the red fox was observed on the same den July 22. The pups were never seen at the den or elsewhere after the red fox was observed on the den for as long as we stayed in the area (until August 10). Our observation supports the view that direct interference with red fox on breeding dens may contribute to the range retraction of arctic foxes from the southern limits of the Arctic tundra in Russia.     

DNA Repair Mechanisms in Huntington’s Disease

The human genome is under continuous attack by a plethora of harmful agents. Without the development of several dedicated DNA repair pathways, the genome would have been destroyed and cell death, inevitable. However, while DNA repair enzymes generally maintain the integrity of the whole genome by properly repairing mutagenic and cytotoxic intermediates, there are cases in which the DNA repair machinery is implicated in causing disease rather than protecting against it. One case is the instability of gene-specific trinucleotides, the causative mutations of numerous disorders including Huntington’s disease. The DNA repair proteins induce mutations that are different from the genome-wide mutations that arise in the absence of repair enzymes; they occur at definite loci, they occur in specific tissues during development, and they are age-dependent. These latter characteristics make pluripotent stem cells a suitable model system for triplet repeat expansion disorders. Pluripotent stem cells can be kept in culture for a prolonged period of time and can easily be differentiated into any tissue, e.g., cells along the neural lineage. Here, we review the role of DNA repair proteins in the process of triplet repeat instability in Huntington’s disease and also the potential use of pluripotent stem cells to investigate neurodegenerative disorders.     

Novel RNA chaperone domain of RNA-binding protein La is regulated by AKT phosphorylation

The cellular function of the cancer-associated RNA-binding protein La has been linked to translation of viral and cellular mRNAs. Recently, we have shown that the human La protein stimulates IRES-mediated translation of the cooperative oncogene CCND1 in cervical cancer cells. However, there is little known about the underlying molecular mechanism by which La stimulates CCND1 IRES-mediated translation, and we propose that its RNA chaperone activity is required. Herein, we show that La binds close to the CCND1 start codon and demonstrate that La''s RNA chaperone activity can change the folding of its binding site. We map the RNA chaperone domain (RCD) within the C-terminal region of La in close proximity to a novel AKT phosphorylation site (T389). Phosphorylation at T389 by AKT-1 strongly impairs its RNA chaperone activity. Furthermore, we demonstrate that the RCD as well as T389 is required to stimulate CCND1 IRES-mediated translation in cells. In summary, we provide a model whereby a novel interplay between RNA-binding, RNA chaperoning and AKT phosphorylation of La protein regulates CCND1 IRES-mediated translation.