Substrate Flexibility of the Flavin-Dependent Dihydropyrrole Oxidases PigB and HapB Involved in Antibiotic Prodigiosin Biosynthesis

In the biosynthesis of the tripyrrolic pigment prodigiosin, PigB is a predicted flavin-dependent oxidase responsible for the formation of 2-methyl-3-amylpyrrole (MAP) from a dihydropyrrole. To prove which dihydropyrrole is the true intermediate, both possibilities, 5-methyl-4-pentyl-3,4-dihydro-2H-pyrrole ( 5 a , resulting from transamination of the aldehyde of 3-acetyloctanal) and 2-methyl-3-pentyl-3,4-dihydro-2H-pyrrole ( 6 , resulting from transamination of the ketone), were synthesised. Only 5 a restored pigment production in a strain of Serratia sp. ATCC 39006 blocked earlier in MAP biosynthesis. PigB is membrane-associated and inactive when its transmembrane domain was deleted, but HapB, its homologue in Hahella chejuensis, lacks the transmembrane domain and is active in solution. Two colourimetric assays for PigB and HapB were developed, and the HapB-catalysed reaction was kinetically characterised. Ten analogues of 5 a were synthesised, varying in the C2 and C3 side chains, and tested as substrates of HapB in vitro and for restoration of pigment production in Serratia ΔpigD in vivo. All lengths of side chain tested at C3 were accepted, but only short side chains at C2 were accepted. The knowledge that 5 a is an intermediate in prodigiosin biosynthesis and the ease of synthesis of analogues of 5 a makes a range of prodigiosin analogues readily available by mutasynthesis.     

Alpha‐Lipoic Acid Supplementation Reduces mTORC1 Signaling in Skeletal Muscle from High Fat Fed,Obese Zucker Rats

The mammalian target of rapamycin (mTOR) signaling pathway is hyperactive in liver, adipose and skeletal muscle tissues of obese rodents. Alpha‐lipoic acid (αLA) has been well accepted as a weight‐loss treatment, though there are limited studies on its effect on mTOR signaling in high‐fat fed, obese rodents. Therefore, the goal of this study was to determine mTOR signaling and oxidative protein alterations in skeletal muscle of high‐fat fed, obese rats after αLA supplementation. Phosphorylation of the mTOR substrate, eukaryotic initiation factor (eIF) 4E‐binding protein 1 (4E‐BP1) and eIF4B were significantly reduced (p < 0.05) in muscle from αLA supplemented rats. Activation of AMP‐activated protein kinase (AMPK), an mTOR inhibitory kinase, was higher (p < 0.05) in the αLA group. Protein expression of markers of oxidative metabolism, acetyl CoA carboxylase (ACC), cytochrome c oxidase IV (COX IV), peroxisome proliferator‐activated receptor (PPAR), and PPAR gamma coactivator 1‐alpha (PGC‐1α) were significantly higher (p < 0.05) after αLA supplementation compared to non‐supplemented group. Our findings show that αLA supplementation limits the negative ramifications of consuming a high fat diet on skeletal muscle markers of oxidative metabolism and mTORC1 signaling.     

SEM-EDX analysis in the source apportionment of particulate matter on Hypogymnia physodes lichen transplants around the Cu smelter and former mining town of Karabash, South Urals, Russia

Scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) of particulate matter on lichen transplant thalli (Hypogymnia physodes) was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminants. Transplants (2 month exposure) stationed in the Cu smelter and former mining town of Karabash were compared with those from a control site 30 km south. Particulate matter in Karabash samples (715 analyses) showed higher levels of S, Pb, Cu, Sn and Zn compared with the control (598 analyses). Complex element associations among the particles confounded detailed mineralogical identifications, and therefore a simplified particle classification scheme was devised for source apportionment. Karabash samples contained high levels of particles classified as mining-related (MRP), and these were also identified in control samples, indicating wide spatial dispersion from the smelter and highlighting the sensitivity of the method. It was noted that MRP <2.5-microm diameter were poorly represented on lichen surfaces suggesting this may limit the usefulness of Hypogymnia transplants as proxies when assessing human health impacts from airborne particulates. Analyses of the lichen thallus surface (away from surface particulates) revealed high levels of Cu, Zn, Fe and Pb associated with organics in the Karabash samples compared with the control, with a proportionate loss of K, interpreted as being due to a stress-related increase in cell membrane permeability. This type of analysis may provide a novel SEM-EDX-based method for assessing lichen vitality. The techniques developed are presented and further implications of the study are discussed.     

Combined aerobic heterotrophic oxidation, nitrification and denitrification in a permeable-support biofilm

A biofilm reactor, termed the permeable-support biofilm (PSB), was developed in which oxygen was supplied to the interior of the biofilm through a permeable membrane. The reactor was tested on filtered sewage supplemented with nutrient broth; the bulk solution was anoxic and the interior of the biofilm was supplied with pure oxygen. All tests were performed on a non-steady state biofilm with a depth of 1 mm. Mass balances on total organic carbon, ammonia, organic nitrogen and nitrate showed that combined heterotrophic oxidation of organics, denitrification and nitrification occurred simultaneously within the biofilm. The advantages of such a reactor are discussed.     

Using Social Network Analysis to Visualize the Social-Media Networks of Community Groups: Two Case Studies from Sydney

Community participation in planning is generally considered crucial for the delivery of positive outcomes; however, the network structures that can be created by community groups that use social media and participate in the network are not widely understood. This paper explores the use of social media, specifically Twitter, by two community groups in Sydney. In the context of this study, community groups are self-created and organized groups of citizens that form to oppose a proposal to amend planning controls for a specific site. Employing the research technique of Social Network Analysis (SNA), this paper seeks to visualize community group social media networks, as well as understand who is connected and who is participating within the networks. For the two community groups investigated, it was found that they do not attract large numbers of friends and followers on Twitter and key stakeholders play a passive listening role in the networks.     

Development and evaluation of an intervention to reduce rip current related beach drowning

The objective of this research was to evaluate a campaign to improve beachgoer recognition of calm-looking rip currents, known to contribute to surf drowning. Posters, postcards, and brochures conveying the message “Don’t get sucked in by the rip” were distributed in an intervention area. Beachgoers were interviewed in this and a similar control area one year before and immediately after the intervention (respective response rates: 69.9% and 82.3%), Consenting respondents were sent follow-up questionnaires after approximately 6 months and 55% responded. In the intervention area, 28.8% of post-intervention, and 57.2% of follow-up respondents, had seen our campaign. At post-intervention, intervention respondents demonstrated improvement (relative to baseline) in intentions to swim away from a calm-looking rip, ability and confidence in identifying a rip, intention never to swim at unpatrolled beaches, and responses to being caught in a rip, compared to the control respondents. Similar improvements were observed post-intervention for respondents in the intervention area who had seen our campaign (relative to those who had not), and at 6 month follow-up for intervention respondents (relative to control respondents). The relatively brief print-based campaign was effective in warning beachgoers about calm-looking rips.