No effects of mobile phone use on cortical auditory change‐detection in children: An ERP study

We investigated the effect of mobile phone use on the auditory sensory memory in children. Auditory event‐related potentials (ERPs), P1, N2, mismatch negativity (MMN), and P3a, were recorded from 17 children, aged 11–12 years, in the recently developed multi‐feature paradigm. This paradigm allows one to determine the neural change‐detection profile consisting of several different types of acoustic changes. During the recording, an ordinary GSM (Global System for Mobile Communications) mobile phone emitting 902 MHz (pulsed at 217 Hz) electromagnetic field (EMF) was placed on the ear, over the left or right temporal area (SAR_1g = 1.14 W/kg, SAR_10g = 0.82 W/kg, peak value = 1.21 W/kg). The EMF was either on or off in a single‐blind manner. We found that a short exposure (two 6 min blocks for each side) to mobile phone EMF has no statistically significant effects on the neural change‐detection profile measured with the MMN. Furthermore, the multi‐feature paradigm was shown to be well suited for studies of perception accuracy and sensory memory in children. However, it should be noted that the present study only had sufficient statistical power to detect a large effect size. Bioelectromagnetics 31:191–199, 2010. © 2009 Wiley‐Liss, Inc.     

Effect of Glycosylation and Additional Domains on the Thermostability of a Family 10 Xylanase Produced by Thermopolyspora flexuosa

The effects of different structural features on the thermostability of Thermopolyspora flexuosa xylanase XYN10A were investigated. A C-terminal carbohydrate binding module had only a slight effect, whereas a polyhistidine tag increased the thermostability of XYN10A xylanase. In contrast, glycosylation at Asn26, located in an exposed loop, decreased the thermostability of the xylanase. The presence of a substrate increased stability mainly at low pH.The thermophilic actinomycete Thermopolyspora flexuosa, previously named Nonomuraea flexuosa and before that Actinomadura flexuosa or Microtetraspora flexuosa (15), produces family 11 and family 10 xylanases, which show high thermostability (16, 17, 22). T. flexuosa xylanase XYN10A has a C-terminal family 13 carbohydrate binding module (CBM) (22). Many xylanases have an additional CBM, which can be a cellulose binding domain (CBD) or a xylan binding domain (XBD) (1, 5, 7, 22, 25, 28). XBD typically increases activity against insoluble xylan (1, 5, 24), although some XBDs also bind soluble xylans (21, 25).We studied the thermostability of T. flexuosa xylanase XYN10A and how CBM and other additional groups affect its thermostability. In addition to confirming the previously described importance of terminal regions, our study identified a loop that is important for the thermostability of T. flexuosa XYN10A. In general, identification of sites important for protein stability is necessary for targeted mutagenesis attempts to increase thermostability.The T. flexuosa xyn10A gene (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"AJ508953","term_id":"57897980","term_text":"AJ508953"}}AJ508953) (22), which encodes the full-length XYN10A xylanase (1-AAST… SYNA-448) containing the catalytic domain and CBM, and a truncated gene, which encodes the catalytic domain only (1-AAST… DALN-301) were expressed in Trichoderma reesei as 3′ fusions to a sequence that encodes the Cel6A CBD (A+B) carrier polypeptide and a Kex2 cleavage site (RDKR) (27). In this article, the catalytic domain and the full-length enzyme are referred to as XYN10A and XYN10A-CBM, respectively. The catalytic domain was also produced in Escherichia coli. For production in E. coli, the sequence encoding the catalytic domain was cloned into a pKKtac vector (33) with and without an additional 3′ sequence encoding a 6×His tag at the protein C terminus (… DALNHHHHHH).The proteins were purified by hydrophobic interaction chromatography using a Phenyl Sepharose column and by ion-exchange chromatography using a DEAE Sepharose FF column (Amersham Pharmacia Biotech). The 6×His-tagged XYN10A xylanase produced in E. coli was purified by affinity chromatography using Ni-nitrilotriacetic acid (Ni-NTA) agarose beads (Qiagen).Mass spectrometric (MS) analyses were performed on a high-resolution 4.7-T hybrid quadrupole-Fourier transform ion cyclotron resonance (FT-ICR) instrument (APEX-Qe; Bruker Daltonics), which employs electrospray ionization (ESI) (see supplemental material for details).Xylanase activity was measured with a 3,5-dinitrosalicylic acid assay by using 1% solubilized birchwood xylan as a substrate (33). The optimum temperature, residual activity, and half-life assays were performed as described earlier (36). SWISS-MODEL (4) was used to automatically model T. flexuosa XYN10A and XYN10A-CBM (PDB codes for the modeling templates are 1v6w and 1e0w, respectively [12, 14]).The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that the masses of XYN10A xylanase and XYN10A-CBM produced in Trichoderma reesei were ∼37 kDa and ∼50 kDa, respectively (Fig. ​(Fig.1A).1A). MS analysis of the 6×His-tagged XYN10A produced in E. coli (SDS-PAGE not shown) indicated the presence of a single protein form (Fig. ​(Fig.1B),1B), with a measured mass of 34,943.25 Da. This is consistent with the theoretical mass of 6×His-tagged XYN10A (34,942.93 Da). In contrast, XYN10A produced in T. reesei was heterogeneously modified, and six protein forms (numbered 1 to 6) were detected (Fig. ​(Fig.1B).1B). The mass of form 1 (34,120.76 Da) is in excellent agreement with the calculated mass of XYN10A (34120.73 Da). The masses of forms 2 and 3, with mass increments of ∼203 and ∼162 Da, respectively, suggested protein glycosylation (+203 Da = GlcNAc; +162 Da = Man). There are two potential sites for N-glycosylation in XYN10A, Asn26 and Asn95. These six protein forms were resolved only by the high-resolution FT-ICR MS technique, not by SDS-PAGE (eluted as a single band [Fig. ​[Fig.1A1A]).Open in a separate windowFIG. 1.(A) SDS-PAGE of purified XYN10A and XYN10A-CBM produced in Trichoderma reesei. Lane 1, molecular weight markers; lane 2, catalytic domain (XYN10A); lane 3, full-length enzyme (XYN10A-CBM). (B) ESI FT-ICR mass spectra of XYN10A with a 6×His tag produced in E. coli (bottom) and XYN10A produced in T. reesei (top). Only the expanded view at m/z 1260 to 1300, with the signals representing the most abundant protein ion charge state z = 27+, is presented. For the measured and calculated masses of the protein forms identified, see the supplemental material.In order to locate the glycosylation site or sites, XYN10A proteins produced in E. coli and T. reesei were subjected to on-line pepsin digestion (see supplemental material for details). The sequence coverage for XYN10A xylanase produced in E. coli was 62%. For XYN10A produced in T. reesei, a lower sequence coverage was obtained, but three glycopeptides (residues 20 to 44, 20 to 46, and 20 to 59), carrying one GlcNAc residue, were detected (glycopeptides A to C in Fig. S1B in the supplemental material). A triply charged glycopeptide A was further analyzed by collision-induced dissociation (CID) measurement (see inset in Fig. S1B in the supplemental material). A ladder of b-type fragment ions further identified this peptide and verified Asn26 as the N-glycosylation site in XYN10A, carrying GlcNAc(Man) as a glycan core structure.The additional sequences attached to the catalytic domain affected the thermostability of XYN10A xylanase. The deletion of the native C-terminal CBM domain (XYN10A produced in T. reesei) slightly decreased (∼2°C) the apparent temperature optimum in the region of 70 to 75°C (Table ​(Table11 and Fig. ​Fig.2A).2A). However, at 80°C, the deletion of the CBM domain increased the activity (Fig. ​(Fig.2A).2A). Furthermore, the half-life in the presence of the substrate at 80°C was lower when the CBM was present (Table ​(Table22).Open in a separate windowFIG. 2.Enzyme activity and stability profiles. (A) Enzyme activity as a function of temperature. The enzymes were incubated for 30 min at each temperature at pH 7. (B) Enzyme inactivation as a function of temperature. The enzyme samples were incubated without the substrate for 30 min at each temperature (pH 7), and the residual activity was measured at 70°C. Values are means ± standard deviations (error bars) for three experiments. Symbols: ⧫, XYN10A xylanase produced in T. reesei; ⋄, XYN10A-CBM produced in T. reesei; ▪, XYN10A produced in E. coli; □, XYN10A-6×His produced in E. coli.

TABLE 1.

Peaks of the optimum temperatures (30-min assay)^a

A comparison of the genetic and physical size of the streptomycin resistance locus in Pneumococcus.

Summary Polyacrylamide gel electrophoresis of the 30S ribosomal proteins derived from six streptomycin resistant strains indicates that each mutation alters the same ribosomal protein (str-r protein). Preliminary data utilizing SDS gels indicates that thestr-r protein has a molecular weight between 10,000 and 20,000 daltons. No significant differences could be detected between the molecular weight of thestr-r protein when it is derived either from a sensitive or from a resistant strain, including those derived from strains carrying multisite mutations of different genetic size. We have estimated the size of the multisitestr-r mutations to be less than 30 base pairs. Two factor crosses withstr-r markers in the trans position demonstrate recombination frequencies expected of closely linked, intragenic markers although cotransfer frequencies, of these same markers from the cis position, are very low. It is concluded that the cotransfer frequencies represent a marker effect and possible explanations are discussed. A reinterpretation of the genetic map of the pneumococcalstr-r locus is presented.Most of the material is taken from a thesis (ALR) submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the School of Graduate Studies, of the State University of New York, Upstate Medical Center     

Proxy comparison in ancient peat sediments: pollen,macrofossil and plant DNA

We compared DNA, pollen and macrofossil data obtained from Weichselian interstadial (age more than 40 kyr) and Holocene (maximum age 8400 cal yr BP) peat sediments from northern Europe and used them to reconstruct contemporary floristic compositions at two sites. The majority of the samples provided plant DNA sequences of good quality with success amplification rates depending on age. DNA and sequencing analysis provided five plant taxa from the older site and nine taxa from the younger site, corresponding to 7% and 15% of the total number of taxa identified by the three proxies together. At both sites, pollen analysis detected the largest (54) and DNA the lowest (10) number of taxa, but five of the DNA taxa were not detected by pollen and macrofossils. The finding of a larger overlap between DNA and pollen than between DNA and macrofossils proxies seems to go against our previous suggestion based on lacustrine sediments that DNA originates principally from plant tissues and less from pollen. At both sites, we also detected Quercus spp. DNA, but few pollen grains were found in the record, and these are normally interpreted as long-distance dispersal. We confirm that in palaeoecological investigations, sedimentary DNA analysis is less comprehensive than classical morphological analysis, but is a complementary and important tool to obtain a more complete picture of past flora.     

Brood size manipulations within the natural range did not reveal intragenerational cost of reproduction in the Willow Tit Parus montanus

To test for the existence of a reproductive cost, we manipulated brood sizes (-2 and +2 nestlings) over 6 years in a northern population of Willow Tits Parus montanus breeding in natural holes. Possible effects were sought in subsequent survival and fecundity of the parents. Parents given extra chicks made more feeding visits than did parents with reduced and control broods. However, this was not reflected in differences in parental body-weight between groups at the end of the nestling period. Brood size manipulation did not significantly affect female or male survival. In 4 out of 6 years, there was a weak and nonsignificant effect on male survival, consistent with a cost of reproduction. Female and male fecundity in the year following the experiment was not affected by the manipulations. Thus, the data do not give evidence of an intragenerational cost of reproduction in the Willow Tit. Parents appeared unwilling to increase their breeding effort to a level which jeopardized their own survival or future breeding success. It is possible that, because of the time constraints in northern latitudes, females work under their capacity and lay smaller clutches than would otherwise be most profitable. Thus, no costs to the parents would be expected as a consequence of manipulations. These results suggest that the current reproductive rate is not maintained by reproductive cost in the Willow Tit. However, the results do not rule out the possibility that selection has operated outside the current range of reproductive rates during evolutionary history of the species.     

Temporal variability in detritus resource maintains diversity of bacterial communities

Competition theory generally predicts that diversity is maintained by temporal environmental fluctuations. One of the many suggested mechanisms for maintaining diversity in fluctuating environments is the gleaner-opportunist trade-off, whereby gleaner species have low threshold resource levels and low maximum growth rates in high resource concentration while opportunist species show opposite characteristics. We measured the growth rates of eight heterotrophic aquatic bacteria under different concentrations of chemically complex plant detritus resource. The growth rates revealed gleaner-opportunist trade-offs. The role of environmental variability in maintaining diversity was tested in a 28-day experiment with three different resource fluctuation regimes imposed on two four-species bacterial communities in microcosms. We recorded population densities with serial dilution plating and total biomass as turbidity. Changes in resource availability were measured from filter-sterilised medium by re-introducing the consumer species and recording short-term growth rates. The type of environmental variation had no effect on resource availability, which declined slowly during the experiment and differed in level between the communities. However, the slowly fluctuating environment had the highest Shannon diversity index, biomass, and coefficient of variation of biomass in both communities. We did not find a clear link between the gleaner-opportunist trade-off and diversity in fluctuating environments. Nevertheless, our results do not exclude this explanation and support the general view that temporal environmental variation maintains species diversity also in communities feeding chemically complex resource.     

SH3BP4 promotes neuropilin-1 and α5-integrin endocytosis and is inhibited by Akt

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Temperature- and growth-phase-regulated changes in lipid fatty acid structures of psychrotolerant groundwater Proteobacteria

Cellular fatty acid compositions of five psychrotolerant groundwater isolates representing alpha- and beta-Proteobacteria were studied at temperatures ranging from 8 to 25 degrees C. Unsaturation of straight-chain fatty acids was the most common response to decreasing temperature and was detected in four of the isolates. On solid media, decrease of temperature resulted in a decrease of cyclopropane fatty acids in beta-proteobacterial isolates. The formation of cyclopropane fatty acids depended, however, to a greater extent on the growth phase than the temperature and increased drastically as the cells entered stationary phase. The alpha-proteobacterial isolates contained a branched C(19:1) fatty acid. The formation of the branched C(19:1) increased during growth in the same way as the cyclopropane fatty acids in beta-proteobacterial strains, indicating possibly an analogous formation of the branched fatty acid by methylation of the 18:1 fatty acid. Sphingomonas sp. K6 possessed a novel temperature-induced modification of lipid fatty acids. As temperature decreased from 25 to 8 degrees C, the fatty acid composition shifted from predominantly even-carbon fatty acids to odd-carbon fatty acids. The results show completely different fatty acid modifications in two strains of the same genus Sphingomonas.     

Structure–function relationships in feedback regulation of energy fluxes in vivo in health and disease: Mitochondrial Interactosome

The aim of this review is to analyze the results of experimental research of mechanisms of regulation of mitochondrial respiration in cardiac and skeletal muscle cells in vivo obtained by using the permeabilized cell technique. Such an analysis in the framework of Molecular Systems Bioenergetics shows that the mechanisms of regulation of energy fluxes depend on the structural organization of the cells and interaction of mitochondria with cytoskeletal elements. Two types of cells of cardiac phenotype with very different structures were analyzed: adult cardiomyocytes and continuously dividing cancerous HL-1 cells. In cardiomyocytes mitochondria are arranged very regularly, and show rapid configuration changes of inner membrane but no fusion or fission, diffusion of ADP and ATP is restricted mostly at the level of mitochondrial outer membrane due to an interaction of heterodimeric tubulin with voltage dependent anion channel, VDAC. VDAC with associated tubulin forms a supercomplex, Mitochondrial Interactosome, with mitochondrial creatine kinase, MtCK, which is structurally and functionally coupled to ATP synthasome. Due to selectively limited permeability of VDAC for adenine nucleotides, mitochondrial respiration rate depends almost linearly upon the changes of cytoplasmic ADP concentration in their physiological range. Functional coupling of MtCK with ATP synthasome amplifies this signal by recycling adenine nucleotides in mitochondria coupled to effective phosphocreatine synthesis. In cancerous HL-1 cells this complex is significantly modified: tubulin is replaced by hexokinase and MtCK is lacking, resulting in direct utilization of mitochondrial ATP for glycolytic lactate production and in this way contributing in the mechanism of the Warburg effect. Systemic analysis of changes in the integrated system of energy metabolism is also helpful for better understanding of pathogenesis of many other diseases.