Inactivity induces increases in abdominal fat.

Previously, inducing inactivity for 53 h after 21 days of voluntary running resulted in a 25 and 48% increase in epididymal and omental fat pad weights, respectively, while rats continued to eat more than a group that never had access to a running wheel (J Physiol 565: 911-925, 2005). We wanted to test the hypothesis that inactivity, independent of excessive caloric intake, could induce an increase in fat pad mass. Twenty-one-day-old rats were given access to voluntary running wheels for 42-43 days so that they were running approximately 9 km/day in the last week of running, after which wheels were locked for 5, 53, or 173 h (WL5, WL53, WL173) before the rats were killed. During the 53 and 173 h of inactivity, one group of animals was pair fed (PF) to match sedentary controls, whereas the other continued to eat ad libitum (AL). Epididymal and retroperitoneal fat masses were significantly increased in the WL173-PF vs. the WL5 group, whereas epididymal, perirenal, and retroperitoneal fat masses were all significantly increased in the WL173-AL group compared with the WL5 group. Additionally, hyperplasia, and not hypertrophy, of the epididymal fat mass was responsible for the increase at WL173-AL as demonstrated by a significant increase in cell number vs. WL5, with no change in cell diameter or volume. Thus two important findings have been elucidated: 1) increases in measured abdominal fat masses occur in both AL and PF groups at WL173, and 2) adipocyte expansion via hyperplasia occurred with an ad libitum diet following cessation of voluntary running.     

The economics of producing sustainable aviation fuel: a regional case study in Queensland,Australia

The airline industry has a strong interest in developing sustainable aviation fuels, in order to reduce their exposure to increasing oil prices and cost liability for greenhouse gas emissions. The feasibility and cost of producing sustainable biomass‐based jet fuels at a sufficient scale to materially address these issues is an enormous challenge. This paper builds directly on the biophysical study by H.T. Murphy, D.A. O'Connell, R.J. Raison, A.C. Warden, T.H. Booth, A. Herr, A.L. Braid, D.F. Crawford, J.A. Hayward, T. Javonovic, J.G. McIvor, M.H. O'Connor, M.L. Poole, D. Prestwidge, N. Raisbeck‐Brown & L. Rye, In review, which examined a 25 year scale‐up strategy to produce 5% of projected jet fuel demand in Australia in 2020 (470 mL) in the Fitzroy region of Queensland, Australia. The strategy was based on the use of a mixed ligno‐cellulosic biomass feedstock and assumed, for the sake of exploring and quantifying the scenario, a simplified two‐step conversion process – conversion of biomass to crude bio‐oil within the region, and upgrade to jet fuel at a central Brisbane facility. This paper provides details on the costs of production in this scenario, focusing on two different strategies for biomass utilization, and two types of novel small–medium scale conversion technologies. The cost analyses have taken into account technology learning curves, different economies of scale and key cost sensitivities. The cost of biomass‐based jet fuels is estimated to be between 0.70 and 1.90 The airline industry has a strong interest in developing sustainable aviation fuels, in order to reduce their exposure to increasing oil prices and cost liability for greenhouse gas emissions. The feasibility and cost of producing sustainable biomass‐based jet fuels at a sufficient scale to materially address these issues is an enormous challenge. This paper builds directly on the biophysical study by H.T. Murphy, D.A. O'Connell, R.J. Raison, A.C. Warden, T.H. Booth, A. Herr, A.L. Braid, D.F. Crawford, J.A. Hayward, T. Javonovic, J.G. McIvor, M.H. O'Connor, M.L. Poole, D. Prestwidge, N. Raisbeck‐Brown & L. Rye, In review, which examined a 25 year scale‐up strategy to produce 5% of projected jet fuel demand in Australia in 2020 (470 mL) in the Fitzroy region of Queensland, Australia. The strategy was based on the use of a mixed ligno‐cellulosic biomass feedstock and assumed, for the sake of exploring and quantifying the scenario, a simplified two‐step conversion process – conversion of biomass to crude bio‐oil within the region, and upgrade to jet fuel at a central Brisbane facility. This paper provides details on the costs of production in this scenario, focusing on two different strategies for biomass utilization, and two types of novel small–medium scale conversion technologies. The cost analyses have taken into account technology learning curves, different economies of scale and key cost sensitivities. The cost of biomass‐based jet fuels is estimated to be between 0.70 and 1.90 $ L^?1 when the efficiency of conversion of biomass to biocrude and subsequently to aviation fuel is varied by ±10% of published values, with an average value of 1.10 $ L^?1. This is within the range of the projected 2035 conventional jet fuel price of 1.50 $ L^?1. Therefore, biomass‐based jet fuel has the potential to contribute to supply of Australia's jet fuel needs in the future.     

Active coping toward predatory stress is associated with lower corticosterone and progesterone plasma levels and decreased methylation in the medial amygdala vasopressin system

An active coping style displayed under stress – which involves proactive investigatory responses toward environmental threats – has been associated with reduced vulnerability to psychiatric illness. However, the neurobiological determinants of coping styles are not well understood. When rats are exposed to a naturalistic stressor (cat fur) in a group, some individuals in the group show robust active investigation of the stimulus while others show a passive response involving retreat, immobility and close aggregation with conspecifics. Here we explored endocrine and epigenetic correlates of these contrasting coping styles. Male Wistar rats (n = 48) were exposed to cat fur in groups of 4 and the passive and active responders were identified and assessed for endocrine and epigenetic differences. Three days after the final cat fur exposure, active responders had substantially lower plasma levels of corticosterone and progesterone than passive responders. Plasma and testicular testosterone levels did not differ between active and passive responders. Active responders had markedly less methylation of the AVP CGCG promoter region located at base 4970 in the posterodorsal region of the medial amygdala but did not differ in the methylation status of the CCGG sequence located at base 2243. This is in agreement with prior research suggesting that AVP and progesterone act in opposition within the medial amygdala to modulate stress-related behaviors. The present study reports striking endocrine and epigenetic differences between active and passive responders, providing insight into potential systems involved in the manifestation of differing coping styles.     

Probing the Structure of the Mechanosensitive Channel of Small Conductance in Lipid Bilayers with Pulsed Electron-Electron Double Resonance

Mechanosensitive channel proteins are important safety valves against osmotic shock in bacteria, and are involved in sensing touch and sound waves in higher organisms. The mechanosensitive channel of small conductance (MscS) has been extensively studied. Pulsed electron-electron double resonance (PELDOR or DEER) of detergent-solubilized protein confirms that as seen in the crystal structure, the outer ring of transmembrane helices do not pack against the pore-forming helices, creating an apparent void. The relevance of this void to the functional form of MscS in the bilayer is the subject of debate. Here, we report PELDOR measurements of MscS reconstituted into two lipid bilayer systems: nanodiscs and bicelles. The distance measurements from multiple mutants derived from the PELDOR data are consistent with the detergent-solution arrangement of the protein. We conclude, therefore, that the relative positioning of the transmembrane helices is preserved in mimics of the cell bilayer, and that the apparent voids are not an artifact of detergent solution but a property of the protein that will have to be accounted for in any molecular mechanism of gating.     

The Role of Currents and Waves in the Dispersal of Submersed Angiosperm Seeds and Seedlings

We tested the hypothesis that currents, waves, and sediment grain size affect the dispersal of seeds and seedlings of the submersed angiosperms Ruppia maritima, Potamogeton perfoliatus and Stuckenia pectinata. Seed settling velocities and initiation of motion of seeds and seedlings and distance transported were quantified on four sediment types under a range of currents and waves in a flume. The rapid settling velocities of R. maritima and S. pectinata seeds and the increased settling velocity of P. perfoliatus in currents above 8 cm/second suggest that primary dispersal of these species is localized to the general area colonized by their parents. Once settled within a bed, seeds are exposed to weak currents and waves, and are likely to be subject to sediment deposition which may further limit dispersal. In contrast, in restoration projects, the absence of vegetation is likely to make seeds more vulnerable to grazing and transport, and may contribute to the lack of plant establishment. If seeds germinate without being buried, they are susceptible to secondary dispersal at relatively low current velocities and small wave heights due to the drag exerted on the cotyledon. Sand grains tend to stick to the seed coat and rootlet of P. perfoliatus seedlings, perhaps a mechanism to reduce the chances of being displaced following germination. These data reveal the close links between sediment, water flow, and submersed angiosperm seedling establishment; these parameters should be considered when using seeds for restoration of submersed angiosperms.     

The Restoration of Phytophagous Beetles in Species‐Rich Chalk Grasslands

This study focuses on the restoration of chalk grasslands over a 6‐year period and tests the efficacy of two management practices, hay spreading and soil disturbance, in promoting this process for phytophagous beetles. Restoration success for the beetles, measured as similarity to target species–rich chalk grassland, was not found to be influenced by either management practice. In contrast, restoration success for the plants did increase in response to hay spreading management. Although the presence of suitable host plants was considered to dictate the earliest point at which phytophagous beetles could successfully colonized, few beetle species colonized as soon as their host plants became established. Morphological characteristics and feeding habits of 27 phytophagous beetle species were therefore tested to identify factors that limited their colonization and persistence. The lag time between host plant establishment and colonization was greatest for flightless beetles. Beetles with foliage‐feeding larvae both colonized at slower rates than seed‐, stem‐, or root‐feeding species and persisted within the swards for shorter periods. Although the use of hay spreading may benefit plant communities during chalk grassland restoration, it did not directly benefit phytophagous beetles. Without techniques for overcoming colonization limitation for invertebrate taxa, short‐term success of restoration may be limited to the plants only.     

The critical role of S-lactoylglutathione formation during methylglyoxal detoxification in Escherichia coli

Survival of exposure to methylglyoxal (MG) in Gram-negative pathogens is largely dependent upon the operation of the glutathione-dependent glyoxalase system, consisting of two enzymes, GlxI (gloA) and GlxII (gloB). In addition, the activation of the KefGB potassium efflux system is maintained closed by glutathione (GSH) and is activated by S-lactoylGSH (SLG), the intermediate formed by GlxI and destroyed by GlxII. Escherichia coli mutants lacking GlxI are known to be extremely sensitive to MG. In this study we demonstrate that a ΔgloB mutant is as tolerant of MG as the parent, despite having the same degree of inhibition of MG detoxification as a ΔgloA strain. Increased expression of GlxII from a multicopy plasmid sensitizes E. coli to MG. Measurement of SLG pools, KefGB activity and cytoplasmic pH shows these parameters to be linked and to be very sensitive to changes in the activity of GlxI and GlxII. The SLG pool determines the activity of KefGB and the degree of acidification of the cytoplasm, which is a major determinant of the sensitivity to electrophiles. The data are discussed in terms of how cell fate is determined by the relative abundance of the enzymes and KefGB.     

Rapid and unexpected effects of piscivore introduction on trophic position and diet of perch (Perca flavescens) in lakes recovering from acidification and metal contamination

1. Yellow perch (Perca flavescens) are often the only surviving fish species in acidified lakes. We studied four lakes along a gradient of recovery from acidification and that had different food web complexities. All had abundant yellow perch, two had low piscivore abundance, one had a well‐established piscivore population and one was manipulated by introducing piscivorous smallmouth bass (Micropterus dolomieu). We hypothesised that there would be strong effects on perch abundance, behaviour and diet induced by the presence of piscivores. 2. In the manipulated lake, the bass reduced yellow perch abundance by 75% over a 2‐year period. Concomitantly, perch use of the pelagic habitat fell from 48 to 40%. 3. In contrast to findings from less disturbed systems, yellow perch in the littoral zone of the manipulated lake did not strongly shift from zooplankton to benthic food sources after the arrival of piscivores. Diet analysis using stable carbon isotopes revealed a strong continued reliance on zooplankton in all lakes, independent of the degree of piscivory. The failure to switch to benthos in the refuge area of the littoral zone is most likely related to the depauperate benthos communities in these formerly acidified lakes. 4. Yellow perch in lakes recovering from acidification face a considerable ecological challenge as the necessary switch to benthic diet is hindered by a low abundance of benthos. The arrival of piscivores in these recovering lakes imposes further restrictions on perch access to food items. We infer that future recovery of perch populations (and higher trophic levels) will have to be preceded by the re‐establishment of diverse benthic macroinvertebrate communities in these lakes.     

A large conformational change couples the ATP binding site of SecA to the SecY protein channel

In bacteria, the SecYEG protein translocation complex employs the cytosolic ATPase SecA to couple the energy of ATP binding and hydrolysis to the mechanical force required to push polypeptides through the membrane. The molecular basis of this energy transducing reaction is not well understood. A peptide-binding array has been employed to identify sites on SecYEG that interact with SecA. These results along with fluorescence spectroscopy have been exploited to characterise a long-distance conformational change that connects the nucleotide-binding fold of SecA to the transmembrane polypeptide channel in SecY. These movements are driven by binding of non-hydrolysable ATP analogues to a monomer of SecA in association with the SecYEG complex. We also determine that interaction with SecYEG simultaneously decreases the affinity of SecA for ATP and inhibitory magnesium, favouring a previously identified active state of the ATPase. Mutants of SecA capable of binding but not hydrolysing ATP do not elicit this conformationally active state, implicating residues of the Walker B motif in the early chain of events that couple ATP binding to the mobility of the channel.     

Alveolar progenitor cells develop in mouse mammary glands independent of pregnancy and lactation

We have previously described pluripotent, parity-induced mammary epithelial cells (PI-MEC) marked by Rosa26-lacZ expression in the mammary glands of parous females. PI-MEC act as lobule-limited epithelial stem/progenitor cells. To determine whether parity is necessary to generate PI-MEC, we incubated mammary explant cultures from virgin mice in vitro with insulin alone (I), hydrocortisone alone (H), prolactin alone (Prl), or a combination of these lactogenic hormones (IHPrl). Insulin alone activated the WAP-Cre gene. Hydrocortisone and prolactin alone did not. Any combination of hormones that included insulin was effective. Only I, H and Prl together were able to induce secretory differentiation and milk protein synthesis. In addition, EGF, IGF-2 and IGF-1 added individually produced activated (lacZ(+)) PI-MEC in explant cultures. Neither estrogen nor progesterone induced WAP-Cre expression in the explants. None of these positive initiators of WAP-Cre expression in PI-MEC were effective in mammospheres or two-dimensional cultures of mammary epithelium, indicating the indispensability of epithelial-stromal interaction in PI-MEC activation. Like PI-MEC, lacZ(+) cells from virgin explants proliferated and contributed progeny to mammospheres in vitro and to epithelial outgrowths in vivo after transplantation. LacZ(+) cells induced in virgin mouse mammary explants were multipotent (like PI-MEC) in impregnated hosts producing lacZ(+) mammary alveolar structures comprised of both myoepithelial and luminal progeny. These data demonstrate PI-MEC, a mammary epithelial sub-population of lobule-limited progenitor cells, are present in nulliparous female mice before parity and, like the PI-MEC observed following parity, are capable of proliferation, self-renewal and the capacity to produce progeny of diverse epithelial cell fates.