Heterogeneous localisation of membrane proteins in Staphylococcus aureus

The bacterial cytoplasmic membrane is the interface between the cell and its environment, with multiple membrane proteins serving its many functions. However, how these proteins are organised to permit optimal physiological processes is largely unknown. Based on our initial findings that 2 phospholipid biosynthetic enzymes (PlsY and CdsA) localise heterogeneously in the membrane of the bacterium Staphylococcus aureus, we have analysed the localisation of other key membrane proteins. A range of protein fusions were constructed and used in conjunction with quantitative image analysis. Enzymes involved in phospholipid biosynthesis as well as the lipid raft marker FloT exhibited a heterogeneous localisation pattern. However, the secretion associated SecY protein, was more homogeneously distributed in the membrane. A FRET-based system also identified novel colocalisation between phospholipid biosynthesis enzymes and the respiratory protein CydB revealing a likely larger network of partners. PlsY localisation was found to be dose dependent but not to be affected by membrane lipid composition. Disruption of the activity of the essential cell division organiser FtsZ, using the inhibitor PC190723 led to loss of PlsY localisation, revealing a link to cell division and a possible role for FtsZ in functions not strictly associated with septum formation

Protective Coatings in the Power Boilers which are Used to Combust Waste – Surfacing Anticorrosive Layers

General requirements and technological solutions of incinerating plants were presented. Heat processing of waste in fluidized and stoker-fired boilers were described. A problem of corrosion and the methods of preventing it in boilers used to combust waste were shown. Materials of increased resistance to corrosion used in power industry were characterised

Protective Coatings in the Power Boilers Used to Incinerate Waste – Fuel Characteristics of Waste as the Source of Energy

A general characteristics of waste management was presented. Municipal waste was characterised and its fuel properties were provided. Numerous thermal processes of waste utilisation were described such as an incinerating process, free-oxygen technology - pyrolysis, technology with oxygen deficiency - gasification and the plasma technology

Effects of periodic photoinhibitory light exposure on physiology and productivity of Arabidopsis plants grown under low light

This work examined the long-term effects of periodic high light stress on photosynthesis, morphology, and productivity of low-light-acclimated Arabidopsis plants. Significant photoinhibition of Arabidopsis seedlings grown under low light (100 μmol photons m-2 s-1) was observed at the beginning of the high light treatment (three times a day for 30 min at 1800 μmol photons m-2 s-1). However, after 2 weeks of treatment, similar photosynthesis yields (Fv/Fm) to those of control plants were attained. The daily levels of photochemical quenching measured in the dark (qPd) indicated that the plants recovered from photoinhibition within several hours once transferred back to low light conditions, with complete recovery being achieved overnight. Acclimation to high light stress resulted in the modification of the number, structure, and position of chloroplasts, and an increase in the average chlorophyll a/b ratio. During ontogenesis, high-light-exposed plants had lower total leaf areas but higher above-ground biomass. This was attributed to the consumption of starch for stem and seed production. Moreover, periodic high light exposure brought forward the reproductive phase and resulted in higher seed yields compared with control plants grown under low light. The responses to periodic high light exposure of mature Arabidopsis plants were similar to those of seedlings but had higher light tolerance

Loss of the SPHF homologue Slr1768 leads to a catastrophic failure in the maintenance of thylakoid membranes in synechocystis sp. PCC 6803

Background: In cyanobacteria the photosystems are localised to, and maintained in, specialist membranes called the thylakoids. The mechanism driving the biogenesis of the thylakoid membranes is still an open question, with only two potential biogenesis factors, Vipp1 and Alb3 currently identified. Methodology/Principal Findings: We generated a slr1768 knockout using the pGEM T-easy vector and REDIRECT. By comparing growth and pigment content (chlorophyll a fluoresence) of the Delta slr1768 mutant with the wild-type, we found that Dslr1768 has a conditional phenotype; specifically under high light conditions (130 mu mol m(-2) s(-1)) thylakoid biogenesis is disrupted leading to cell death on a scale of days. The thylakoids show considerable disruption, with loss of both structure and density, while chlorophyll a density decreases with the loss of thylakoids, although photosynthetic efficiency is unaffected. Under low light (30 mu mol m(-2) s(-1)) the phenotype is significantly reduced, with a growth rate similar to the wildtype and only a low frequency of cells with evident thylakoid disruption. Conclusions/Significance: This is the first example of a gene that affects the maintenance of the thylakoid membranes specifically under high light, and which displays a phenotype dependent on light intensity. Our results demonstrate that Slr1768 has a leading role in acclimatisation, linking light damage with maintenance of the thylakoids

Fluorescence emission spectra measured at 77K.

<p>Spectra recorded for frozen suspensions of cells grown in high light (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0019625#s4" target="_blank">Materials and Methods</a> for details). Spectra are means from 3 separate samples, normalised at 725 nm (in A) or 665 nm (in B). A: excitation at 435 nm, mainly exciting chlorophyll <i>a</i>. B: excitation at 600 nm, mainly exciting phycocyanin.</p

Photoautotrophically grown <i>slr1768</i> cells exhibit a loss of pigment.

<p>Black  = WT and red  = Δ<i>slr1768</i>. A, C and E whole cell absorption spectrum of wild-type and Δ<i>slr1768</i> cells grown under low light (30 µmol m⁻²⋅s⁻¹) at 15 hours (A) 48 hours (C) and 90 hours (E). Similarly, B, D and F grown under high light conditions (130 µmol m⁻² s⁻¹) at 15 hours (B), 48 hours (D) and 90 hours (F). All samples were normalised to OD₇₅₀.</p

Photoautotrophically grown wild-type <i>Synechocystis</i> and Δ<i>slr1768</i> cultures under phosphate deprivation.

<p>(A) Graph shows growth of wild-type and Δ<i>slr1768</i> cells grown in BG11-P and BG11 over 192 hours under low light (30 µmol m⁻²s⁻¹). (B) Whole-cell absorption spectra of wild-type and Δ<i>slr1768</i> cells grown under low light (30 µmol m⁻²s⁻¹) in BG11-P and BG11 for 90 hours.</p

Laser scanning confocal microscopy images of wild type and Δ<i>slr1768</i> cells grown under high light.

<p>Cells were grown under high-light (130 µmol m⁻²s⁻¹) for 48 hrs. Chlorophyll <i>a</i> fluorescence is shown in purple and auto fluorescence from predominantly dead and dying cells is green. Chlorophyll <i>a</i> fluorescence was collected over the emission wavelength range 670–720 nm. Green auto fluorescence was collected at 500–527 nm. A significant loss in fluorescence was observed in the Δ<i>slr1768</i> cells (B) compared to the wild-type (A).</p