Reliability of a New Test of Balance Function in Healthy and Concussion Populations.

Providing quantitative measures of balance and posture is a valuable aid in clinical assessment and in recent years several devices have been introduced that have demonstrated the accurate measure of balance via deviation of center of mass utilizing software algorithms and mobile devices. The purpose of this study was to assess the accuracy of EQ Balance against the SwayTM Balance System (Sway), another balance device that is currently established as an accurate measure of balance, and to evaluate the test-retest reliability of EQ Balance. Seventy individuals presenting to a sports medicine and concussion clinic volunteered to participate in the assessment of balance utilizing Sway and EQ Balance simultaneously. The group included 25 males and 45 females (mean age: 37.8 ± 14.8, range: 13-65) with and without concussion or other neurological conditions (39 concussed vs. 31 non-neurologically injured, or healthy). Twenty-six of the concussed participants were balance-impaired. Participants performed five postures while holding the mobile device against their chest. Participants held a device holder that secured two devices: one iPhone 6 with EQ Balance and a second iPhone 6 with Sway Balance. The average balance score on all five stances was recorded as the "average balance score". Average balance scores were in statistical agreement between the two methods across the entire group, and for sub-groups according to the Deming regression (p < 0.01). The intra-class correlation (ICC) for the cohort was 0.87 (p < 0.001). Across the cohort, EQ Balance measured significantly worse balance scores in the balance-impaired group, comprised of participants with brain injury who failed a clinical balance screening test, compared to the group without clinically-determined balance impairment (this group includes healthy and some concussed patients). EQ Balance demonstrated safety, as it was considered safe to perform independently (i.e., without an observer) in those with impaired balance, and high test- retest reliability in the healthy and concussed patient population. Statistical agreement was established between the two measures of EQ Balance and Sway Balance for the average balance score across all five stances. The ICC analysis demonstrates strong consistency of the task output between test sessions. Given these results, EQ Balance demonstrates strength as a new balance assessment tool to accurately measure balance performance as part of a unique and novel gamified application in healthy and neurologically injured populations.

Phosphatidylglycerol is implicated in divisome formation and metabolic processes of cyanobacteria.

Phosphatidylglycerol is an essential phospholipid for photosynthesis and other cellular processes. We investigated the role of phosphatidylglycerol in cell division and metabolism in a phophatidylglycerol-auxotrophic strain of Synechococcus PCC7942. Here we show that phosphatidylglycerol is essential for the photosynthetic electron transfer and for the oligomerisation of the photosynthetic complexes, notably, we revealed that this lipid is important for non-linear electron transport. Furthermore, we demonstrate that phosphatidylglycerol starvation elevated the expressions of proteins of nitrogen and carbon metabolism. Moreover, we show that phosphatidylglycerol-deficient cells changed the morphology, became elongated, the FtsZ ring did not assemble correctly, and subsequently the division was hindered. However, supplementation with phosphatidylglycerol restored the ring-like structure at the mid-cell region and the normal cell size, demonstrating the phosphatidylglycerol is needed for normal septum formation. Taken together, central roles of phosphatidylglycerol were revealed; it is implicated in the photosynthetic activity, the metabolism and the fission of bacteria.

Zeaxanthin and echinenone modify the structure of photosystem I trimer in Synechocystis sp. PCC 6803.

The function of xanthophylls in the organisation and structure of the photosynthetic complexes is not completely clarified yet. Recently, we observed a reduced level of the photosystem oligomers upon xanthophyll deficiency, although xanthophylls are not considered to be part of the photosynthetic complexes of cyanobacteria. The present study aimed at further investigating the relationship between xanthophylls and photosytem I (PSI) complex in the cyanobacterium Synechocystis sp. PCC 6803. Interestingly, we recorded the presence of echinenone and zeaxanthin in the isolated PSI trimers. These two xanthophyll species are among the most abundant xanthophylls in this cyanobacterial species. Various xanthophyll biosynthesis mutants were used to investigate the specific role of these xanthophylls. Our spectroscopic results revealed specific structural changes manifested in altered pigment-pigment or pigment-protein interactions within PSI complex in the absence of zeaxanthin and echinenone. These structural modifications of the complexes seem to destabilize the PSI trimeric complexes and eventually result in an increased propensity for monomerization. Our results clearly demonstrate that xanthophylls are important for the fine-tuning of the PSI trimer structure. These xanthophylls could be part of the complex or be embedded in the membrane in the vicinity of PSI.

Lipid and carotenoid cooperation-driven adaptation to light and temperature stress in Synechocystis sp. PCC6803.

Polyunsaturated lipids are important components of photosynthetic membranes. Xanthophylls are the main photoprotective agents, can assist in protection against light stress, and are crucial in the recovery from photoinhibition. We generated the xanthophyll- and polyunsaturated lipid-deficient ROAD mutant of Synechocystis sp. PCC6803 (Synechocystis) in order to study the little-known cooperative effects of lipids and carotenoids (Cars). Electron microscopic investigations confirmed that in the absence of xanthophylls the S-layer of the cellular envelope is missing. In wild-type (WT) cells, as well as the xanthophyll-less (RO), polyunsaturated lipid-less (AD), and the newly constructed ROAD mutants the lipid and Car compositions were determined by MS and HPLC, respectively. We found that, relative to the WT, the lipid composition of the mutants was remodeled and the Car content changed accordingly. In the mutants the ratio of non-bilayer-forming (NBL) to bilayer-forming (BL) lipids was found considerably lower. Xanthophyll to ß-carotene ratio increased in the AD mutant. In vitro and in vivo methods demonstrated that saturated, monounsaturated lipids and xanthophylls may stabilize the trimerization of Photosystem I (PSI). Fluorescence induction and oxygen-evolving activity measurements revealed increased light sensitivity of RO cells compared to those of the WT. ROAD showed a robust increase in light susceptibility and reduced recovery capability, especially at moderate low (ML) and moderate high (MH) temperatures, indicating a cooperative effect of xanthophylls and polyunsaturated lipids. We suggest that both lipid unsaturation and xanthophylls are required for providing the proper structure and functioning of the membrane environment that protects against light and temperature stress.

ß-Carotene influences the phycobilisome antenna of cyanobacterium Synechocystis sp. PCC 6803.

We investigated the relation between the carotenoid composition and the structure of phycobilisome (PBS) antenna of cyanobacterium Synechocystis sp. PCC 6803. PBS is a large soluble protein complex enhances the light harvesting efficiency of the cells. It is composed of a central allophycocyanin core and radial phycocyanin rods, but it does not contain carotenoids. However, the absence or low level of carotenoids were previously shown to lead the co-existence of unconnected rod units and assembled PBS with shorter peripheral rods. Here we show that the lack of ß-carotene, but not of xanthophylls or the distortion of photosystem structure, evoked unconnected rods. Thus, these essential ß-carotene molecules are not bound by Photosystem I or Photosystem II. Our results do not show correlation between the reactive oxygen species (ROS) and PBS distortion despite the higher singlet oxygen producing capacity and light sensitivity of the mutant cells. Reduced cellular level of those linker proteins attaching the rod units together was also observed, but the direct damage of the linkers by ROS are not supported by our data. Enzymatic PBS proteolysis induced by nitrogen starvation in carotenoid mutant cells revealed a retarded degradation of the unconnected rod units.

Effect of ultrasound-assisted crystallization in the diastereomeric salt resolution of tetramisole enantiomers in ternary system with O,O'-dibenzoyl-(2R,3R)-tartaric acid.

The diastereomeric salt resolution of racemic tetramisole was studied using ultrasound irradiation. We examined the effect of power and duration of ultrasonic irradiation on the properties of the crystalline phase formed by ultrasound-assisted crystallization and the result of the whole optical resolution. The results were compared with reference experiment without using ultrasound. The US time (5-30min) caused higher enantiomeric excess. Although yield was lower continuously high resolving efficiency could have been reached through ultrasound. We had the best results with 4.3W ultrasound power when resolvability was even higher than the best of reference. Furthermore, we accomplished a deep and thorough examination of the salts that possibly could form in this resolution. One of the four diastereomeric salts, which have been identified by powder X-ray diffraction, FTIR-spectroscopy, and differential scanning calorimetry (DSC) in the ternary system of the two tetramisole enantiomers and the resolving agent, namely the bis[(S)-tetramisole]-dibenzoyl-(R,R)-tartrate salt have been proven the key compound in the resolution process, and presented the highest melting point of 166°C (dec.) among the four salts. The originally expected diastereomeric bitartrate salts with 1:1M base:acid ratio [(S)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt and (R)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt] and their 'racemic' co-crystal [(RS)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt] showed somewhat lower melting points (152, 145, and 150°C, respectively) and their crystallization was also prevented by application of ultrasound. Based on the melting points and enthalpies of fusion measured by DSC, all the binary and ternary phase diagrams have been newly established and calculated in the system with help of classical modelling equations of liquidus curves.

Lack of Phosphatidylglycerol Inhibits Chlorophyll Biosynthesis at Multiple Sites and Limits Chlorophyllide Reutilization in Synechocystis sp. Strain PCC 6803.

The negatively charged lipid phosphatidylglycerol (PG) constitutes up to 10% of total lipids in photosynthetic membranes, and its deprivation in cyanobacteria is accompanied by chlorophyll (Chl) depletion. Indeed, radioactive labeling of the PG-depleted ΔpgsA mutant of Synechocystis sp. strain PCC 6803, which is not able to synthesize PG, proved the inhibition of Chl biosynthesis caused by restriction on the formation of 5-aminolevulinic acid and protochlorophyllide. Although the mutant accumulated chlorophyllide, the last Chl precursor, we showed that it originated from dephytylation of existing Chl and not from the block in the Chl biosynthesis. The lack of de novo-produced Chl under PG depletion was accompanied by a significantly weakened biosynthesis of both monomeric and trimeric photosystem I (PSI) complexes, although the decrease in cellular content was manifested only for the trimeric form. However, our analysis of ΔpgsA mutant, which lacked trimeric PSI because of the absence of the PsaL subunit, suggested that the virtual stability of monomeric PSI is a result of disintegration of PSI trimers. Interestingly, the loss of trimeric PSI was accompanied by accumulation of monomeric PSI associated with the newly synthesized CP43 subunit of photosystem II. We conclude that the absence of PG results in the inhibition of Chl biosynthetic pathway, which impairs synthesis of PSI, despite the accumulation of chlorophyllide released from the degraded Chl proteins. Based on the knowledge about the role of PG in prokaryotes, we hypothesize that the synthesis of Chl and PSI complexes are colocated in a membrane microdomain requiring PG for integrity.

Carotenoids are essential for the assembly of cyanobacterial photosynthetic complexes.

In photosynthetic organisms, carotenoids (carotenes and xanthophylls) are important for light harvesting, photoprotection and structural stability of a variety of pigment-protein complexes. Here, we investigated the consequences of altered carotenoid composition for the functional organization of photosynthetic complexes in wild-type and various mutant strains of the cyanobacterium Synechocystis sp. PCC 6803. Although it is generally accepted that xanthophylls do not play a role in cyanobacterial photosynthesis in low-light conditions, we have found that the absence of xanthophylls leads to reduced oligomerization of photosystems I and II. This is remarkable because these complexes do not bind xanthophylls. Oligomerization is even more disturbed in crtH mutant cells, which show limited carotenoid synthesis; in these cells also the phycobilisomes are distorted despite the fact that these extramembranous light-harvesting complexes do not contain carotenoids. The number of phycocyanin rods connected to the phycobilisome core is strongly reduced leading to high amounts of unattached phycocyanin units. In the absence of carotenoids the overall organization of the thylakoid membranes is disturbed: Photosystem II is not formed, photosystem I hardly oligomerizes and the assembly of phycobilisomes remains incomplete. These data underline the importance of carotenoids in the structural and functional organization of the cyanobacterial photosynthetic machinery.

Metagenome changes in the mesophilic biogas-producing community during fermentation of the green alga Scenedesmus obliquus.

A microalgal biomass offers a potential alternative to the maize silage commonly used in biogas technology. In this study, photoautotrophically grown Scenedesmus obliquus was used as biogas substrate. This microalga has a low C/N ratio of 8.5 relative to the optimum 20-30. A significant increase in the ammonium ion content was not observed. The methane content of the biogas generated from Sc. obliquus proved to be higher than that from maize silage, but the specific biogas yield was lower. Semi-continuous steady biogas production lasted for 2 months. Because of the thick cell wall of Sc. obliquus, the biomass-degrading microorganisms require additional time to digest its biomass. The methane concentration in the biogas was also high, in co-digestion (i.e., 52-56%) as in alga-fed anaerobic digestion (i.e., 55-62%). These results may be related to the relative predominance of the order Clostridiales in co-digestion and to the more balanced C/N ratio of the mixed algal-maize biomass. Predominance of the order Methanosarcinales was observed in the domain Archaea, which supported the diversity of metabolic pathways in the process.

Elevated growth temperature can enhance photosystem I trimer formation and affects xanthophyll biosynthesis in Cyanobacterium Synechocystis sp. PCC6803 cells.

In the thylakoid membranes of the mesophilic cyanobacterium Synechocystis PCC6803, PSI reaction centers (RCs) are organized as monomers and trimers. PsaL, a 16 kDa hydrophobic protein, a subunit of the PSI RC, was previously identified as crucial for the formation of PSI trimers. In this work, the physiological effects accompanied by PSI oligomerization were studied using a PsaL-deficient mutant (ΔpsaL), not able to form PSI trimers, grown at various temperatures. We demonstrate that in wild-type Synechocystis, the monomer to trimer ratio depends on the growth temperature. The inactivation of the psaL gene in Synechocystis grown phototropically at 30°C induces profound morphological changes, including the accumulation of glycogen granules localized in the cytoplasm, resulting in the separation of particular thylakoid layers. The carotenoid composition in ΔpsaL shows that PSI monomerization leads to an increased accumulation of myxoxantophyll, zeaxanthin and echinenone irrespective of the temperature conditions. These xanthophylls are formed at the expense of ß-carotene. The measured H2O→CO2 oxygen evolution rates in the ΔpsaL mutant are higher than those observed in the wild type, irrespective of the growth temperature. Moreover, circular dichroism spectroscopy in the visible range reveals that a peak attributable to long-wavelength-absorbing carotenoids is apparently enhanced in the trimer-accumulating wild-type cells. These results suggest that specific carotenoids are accompanied by the accumulation of PSI oligomers and play a role in the formation of PSI oligomer structure.