Solution structure of a bacterial microcompartment targeting peptide and its application in the construction of an ethanol bioreactor

Targeting of proteins to bacterial microcompartments (BMCs) is mediated by an 18-amino-acid peptide sequence. Herein, we report the solution structure of the N-terminal targeting peptide (P18) of PduP, the aldehyde dehydrogenase associated with the 1,2-propanediol utilization metabolosome from Citrobacter freundii. The solution structure reveals the peptide to have a well-defined helical conformation along its whole length. Saturation transfer difference and transferred NOE NMR has highlighted the observed interaction surface on the peptide with its main interacting shell protein, PduK. By tagging both a pyruvate decarboxylase and an alcohol dehydrogenase with targeting peptides, it has been possible to direct these enzymes to empty BMCs in vivo and to generate an ethanol bioreactor. Not only are the purified, redesigned BMCs able to transform pyruvate into ethanol efficiently, but the strains containing the modified BMCs produce elevated levels of alcohol

Stratigraphy and chronology of a 15ka sequence of multi-sourced silicic tephras in a montane peat bog, eastern North Island, New Zealand.

We document the stratigraphy, composition, and chronology of a succession of 16 distal, silicic tephra layers interbedded with lateglacial and Holocene peats and muds up to c. 15 000 radiocarbon years (c. 18 000 calendar years) old at a montane site (Kaipo Bog) in eastern North Island, New Zealand. Aged from 665 +/- 15 to 14 700 +/- 95 14C yr BP, the tephras are derived from six volcanic centres in North Island, three of which are rhyolitic (Okataina, Taupo, Maroa), one peralkaline (Tuhua), and two andesitic (Tongariro, Egmont). Correlations are based on multiple criteria: field properties and stratigraphic interrelationships, ferromagnesian silicate mineral assemblages, glass-shard major element composition (from electron microprobe analysis), and radiocarbon dating. We extend the known distribution of tephras in eastern North Island and provide compositional data that add to their potential usefulness as isochronous markers. The chronostratigraphic framework established for the Kaipo sequence, based on both site-specific and independently derived tephra-based radiocarbon ages, provides the basis for fine-resolution paleoenvironmental studies at a climatically sensitive terrestrial site from the mid latitudes of the Southern Hemisphere. Tephras identified as especially useful paleoenvironmental markers include Rerewhakaaitu and Waiohau (lateglacial), Konini (lateglacial-early Holocene), Tuhua (middle Holocene), and Taupo and Kaharoa (late Holocene)

The effect of energetic electron precipitation on middle mesospheric night-time ozone during and after a moderate geomagnetic storm

Using a ground-based microwave radiometer at Troll Station, Antarctica (72°S, 2.5°E, L = 4.76), we have observed a decrease of 20–70% in the mesospheric ozone, coincident with increased nitric oxide, between 60 km and 75 km altitude associated with energetic electron precipitation (E > 30 keV) during a moderate geomagnetic storm (minimum Dst of −79 nT) in late July 2009. NOAA satellite data were used to identify the precipitating particles and to characterize their energy, spatial distribution and temporal variation over Antarctica during this isolated storm. Both the ozone decrease and nitric oxide increase initiate with the onset of the storm, and persist for several days after the precipitation ends, descending in the downward flow of the polar vortex. These combined data present a unique case study of the temporal and spatial morphology of chemical changes induced by electron precipitation during moderate geomagnetic storms, indicating that these commonplace events can cause significant effects on the middle mesospheric ozone distribution

Macrofossils and pollen representing forests of the pre-Taupo volcanic eruption (c. 1850 yr BP) era at Pureora and Benneydale, central North Island, New Zealand.

Micro- and macrofossil data from the remains of forests overwhelmed and buried at Pureora and Benneydale during the Taupo eruption (c. 1850 conventional radiocarbon yr BP) were compared. Classification of relative abundance data separated the techniques, rather than the locations, because the two primary clusters comprised pollen and litter/wood. This indicates that the pollen:litter/wood within-site comparisons (Pureora and Benneydale are 20 km apart) are not reliable. Plant macrofossils represented mainly local vegetation, while pollen assemblages represented a combination of local and regional vegetation. However, using ranked abundance and presence/absence data, both macrofossils and pollen at Pureora and Benneydale indicated conifer/broadleaved forest, of similar forest type and species composition at each site. This suggests that the forests destroyed by the eruption were typical of mid-altitude west Taupo forests, and that either data set (pollen or macrofossils) would have been adequate for regional forest interpretation. The representation of c. 1850 yr BP pollen from the known buried forest taxa was generally consistent with trends determined by modern comparisons between pollen and their source vegetation, but with a few exceptions. A pollen profile from between the Mamaku Tephra (c. 7250 yr BP) and the Taupo Ignimbrite indicated that the Benneydale forest had been markedly different in species dominance compared with the forest that was destroyed during the Taupo eruption. These differences probably reflect changes in drainage, and improvements in climate and/or soil fertility over the middle Holocene

Contrast Mechanisms for the Detection of Ferroelectric Domains with Scanning Force Microscopy

We present a full analysis of the contrast mechanisms for the detection of ferroelectric domains on all faces of bulk single crystals using scanning force microscopy exemplified on hexagonally poled lithium niobate. The domain contrast can be attributed to three different mechanisms: i) the thickness change of the sample due to an out-of-plane piezoelectric response (standard piezoresponse force microscopy), ii) the lateral displacement of the sample surface due to an in-plane piezoresponse, and iii) the electrostatic tip-sample interaction at the domain boundaries caused by surface charges on the crystallographic y- and z-faces. A careful analysis of the movement of the cantilever with respect to its orientation relative to the crystallographic axes of the sample allows a clear attribution of the observed domain contrast to the driving forces respectively.Comment: 8 pages, 8 figure

A comparison of beliefs about exercise during pregnancy between Chinese and Australian pregnant women

Background: Despite the well-established benefits of exercise during pregnancy, many women remain inactive. This may be related, in part, to women's beliefs about exercise in pregnancy, which are likely influenced by cultural background. Accordingly, the aim of this study was to compare attitudes, subjective norms, and perceived behavioural control toward exercise, together with current levels of exercise participation between Chinese and Australian women during pregnancy. A second aim was to determine the extent to which these factors predict intention to exercise within a Theory of Planned Behaviour framework. Methods: Pregnant women (22 ± 2 weeks of gestation) living in China (n = 240) and Australia (n = 215) completed a questionnaire designed to assess a) maternal beliefs regarding the importance of exercise in relation to other health behaviours, b) attitudes, subjective norms, perceived behavioural control and intentions toward exercise, and c) current levels of physical activity. One-way analyses of variance were used to compare the demographics, maternal beliefs, attitudes, subjective norms, perceived behavioural control, intentions to exercise, and current physical activity levels between the Chinese and Australian samples. Structural equation modelling was used to determine which factors predicted intention to exercise in the two samples. Results: Australian women reported higher levels of current exercise and intentions to exercise in the next four weeks of pregnancy compared with Chinese women. These observations were associated with higher instrumental attitudes, ratings of subjective norm, and perceived behavioural control toward exercise in the Australian women. Instrumental attitudes and perceived behavioural control predicted intention to exercise in the Australian women, while perceived behavioural control was the only predictor of intentions to exercise in the Chinese sample. Conclusions: Beliefs, attitudes, barriers and intentions towards exercise during pregnancy differ between cultures. Understanding these differences may assist in the design of exercise interventions to maximise exercise adherence and lifelong physical activity patterns

Late Holocene palynology and palaeovegetation of tephra-bearing mires at Papamoa and Waihi Beach, western Bay of Plenty, North Island, New Zealand.

The vegetation history of two mires associated with Holocene dunes near the western Bay of Plenty coast, North Island, New Zealand, is deduced from pollen analysis of two cores. Correlation of airfall tephra layers in the peats, and radiocarbon dates, indicate that the mires at Papamoa and Waihi Beach are c. 4600 and c. 2900 conventional radiocarbon years old, respectively. Tephras used to constrain the chronology of the pollen record include Rotomahana (1886 AD), Kaharoa (700 yr B.P.), Taupo (Unit Y; 1850 yr B.P.), Whakaipo (Unit V; 2700 yr B.P.), Stent (Unit Q; 4000 yr B.P.), Hinemaiaia (Unit K; 4600 yr B.P.), and reworked Whakatane (c. 4800 yr B.P.) at Papamoa, and Kaharoa and Taupo at Waihi Beach. Peat accumulation rates at Papamoa from 4600 - 1850 yr B.P. range from 0.94 to 2.64 mm/yr (mean 1.37 mm/yr). At Waihi Beach, from 2900 yr B.P. - present day, they range from 0.11 to 0.21 mm/yr (mean 0.20 mm/yr). Peat accumulation at both sites was slowest from 1850 to 700 yr B.P., suggesting a drier overall climate during this interval. At both sites, the earliest organic sediments, which are underlain by marine or estuarine sands, yield pollen spectra indicating salt marsh or estuarine environments. Coastal vegetation communities declined at both sites, as sea level gradually fell or the coast prograded, and were eventually superseded by a low moor bog at Papamoa, and a mesotrophic swamp forest at Waihi Beach. These differences, and the marked variation in peat accumulation rates, probably reflect local hydrology and are unlikely to have been climatically controlled. The main regional vegetation during this period was mixed northern conifer-angiosperm forest. Kauri (Agathis australis) formed a minor component of these forests, but populations of this tree have apparently not expanded during the late Holocene at these sites, which are near its present southern limit. Occasional shortlived forest disturbances are detectable in these records, in particular immediately following the deposition of Taupo Tephra. However, evidence for forest clearance during the human era is blurred by the downward dislocation of modern adventi ve pollen at these sites, preventing the clear differentiation of the Polynesian and European eras

Si-compatible candidates for high-K dielectrics with the Pbnm perovskite structure

We analyze both experimentally (where possible) and theoretically from first-principles the dielectric tensor components and crystal structure of five classes of Pbnm perovskites. All of these materials are believed to be stable on silicon and are therefore promising candidates for high-K dielectrics. We also analyze the structure of these materials with various simple models, decompose the lattice contribution to the dielectric tensor into force constant matrix eigenmode contributions, explore a peculiar correlation between structural and dielectric anisotropies in these compounds and give phonon frequencies and infrared activities of those modes that are infrared-active. We find that CaZrO_3, SrZrO_3, LaHoO_3, and LaYO_3 are among the most promising candidates for high-K dielectrics among the compounds we considered.Comment: 17 pages, 9 figures, 4 tables. Supplementary information: http://link.aps.org/supplemental/10.1103/PhysRevB.82.064101 or http://www.physics.rutgers.edu/~sinisa/highk/supp.pd

Fetal growth trajectories and measures of insulin resistance in young adults

Context: Events during gestation greatly influence the risk of cardiometabolic diseases including diabetes in offspring during later life. Objective: This study aimed to investigate relationships between serial ultrasound-derived fetal growth trajectories and markers of insulin resistance in young adults in the Raine Study, an Australian pregnancy cohort. Methods: Linear mixed modeling examined the relationship between fetal growth trajectory groups, constructed using serial ultrasound-based abdominal circumference (AC), femur length (FL), and head circumference (HC) from 1333 mother-fetal pairs, and offspring Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), as a marker of diabetes risk, at 20 (n = 414), 22 (n = 385), and 27 (n = 431) years. Analyses were adjusted for age, sex, ethnicity, socioeconomic status, adult lifestyle factors, and maternal factors during pregnancy. Results: The study identified 7 AC, 5 FL, and 5 HC growth trajectory groups. Compared to the average-stable (reference) group, a low-falling AC growth trajectory (26%; P = .005) and 2 low HC growth trajectories (20%; P = .006% and 8%; P = .021) were associated with higher adult HOMA-IR. Trajectories representing a high-stable FL and a rising HC were associated with 12% (P = .002) and 9% (P = .021) lower adult HOMA-IR, respectively, compared to the reference group. Conclusion: Restricted fetal HC and AC from early pregnancy are associated with higher relative insulin resistance in the offspring during adulthood. These data strengthen our understanding of the importance of the intrauterine environment and its effect on the risk of predisposition to adult diabetes and related metabolic disorders