Understanding the metabolic burden of recombinant antibody production in Saccharomyces cerevisiae using a quantitative metabolomics approach

The cellular changes induced by heterologous protein expression in the yeast Saccharomyces cerevisiae have been analysed on many levels and found to be significant. However, even though high‐level protein production poses a metabolic burden, evaluation of the expression host at the level of the metabolome has often been neglected. We present a comparison of metabolite profiles of a wild‐type strain with those of three strains producing recombinant antibody variants of increasing size and complexity: an scFv fragment, an scFv–Fc fusion protein and a full‐length IgG molecule. Under producing conditions, all three recombinant strains showed a clear decrease in growth rate compared with the wild‐type strain and the severity of the growth phenotype increased with size of the protein. The levels of 76 intracellular metabolites were determined using a targeted (semi) quantitative mass spectrometry based approach. Based on unsupervised and supervised multivariate analysis of metabolite profiles, together with pathway activity profiling, the recombinant strains were found to be significantly different from each other and from the wild‐type strain. We observed the most prominent changes in metabolite levels for metabolites involved in amino acid and redox metabolism. Induction of the unfolded protein response was detected in all producing strains and is considered to be a contributing factor to the overall metabolic burden on the cells.     

Comparisons of methods used for estimating the growth of Tetrahymena pyriformis W

Growth of Tetrahymena pyriformis W was used to assess the relative nutritive value (RNV) of 40 foodstuffs. Growth of the organism was estimated by ammonia-nitrogen (NH₃-N) accumulation, media optical density (OD) and the reduction of triphenyl-tetrazolium chloride (TTC) for triphenyl-formazan. The latter approach was evaluated both on a linear and on a logarithmic scale. All methods used to determine RNC were compared to the microscope cell-counting procedure before and after adjustment by linear regression equations. When compared to cell counts, the measurement of NH₃-N accumulation resulted in the lowest mean difference, followed by the measurements of TTC reduction on a logarithmic scale, OD and then TTC reduction on a linear scale. Mean deviations from cell count values were reduced for all methods after regression equations were used to fit experimental values to the same range as the cell count values. It was concluded that cell counts should be used to calculate RNV and that NH₃-N or OD determinations could increase the efficiency of the RNV procedure for preliminary sample screening.     

Material-related losses of natural rubber composites with surface-modified nanodiamonds

Dielectric elastomer generators (DEGs) offer a solution for the growing sustainable energy needs. Despite the active research on DEGs, currently used materials do not possess the required properties to achieve the full potential performance of such generators, thus, limiting an economical attractiveness of DEGs. Therefore, tailor-made materials for DEGs are in demand. Customizing the natural rubber recipe allows both dielectric and mechanical loss reduction, while the addition of nanodiamonds lowers the stress relaxation and hysteresis loss even further. The effect is most pronounced after chemical modification of nanodiamonds with silane coupling agents. Moreover, such modified nanodiamonds show less dielectric losses compared to unmodified nanodiamonds and allow reducing the dynamic loss tangent of the compound. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48629.     

Vegetable fillers for electric stimuli responsive elastomers

Dielectric elastomer actuators (DEAs) have been studied widely in recent years for artificial muscle applications, but their implementation into production is limited due to high operating voltages required. The actuation behavior of dielectric elastomer under an applied electric field is predicted by Maxwell's pressure and thickness strain equations. According to these equations, the best electromechanical response is achieved when the relative permittivity is high and elastic modulus is low. The potential source for additives increasing the relative permittivity of rubbers can be vegetable powders that have much higher dielectric constant than common elastomers. In the present research, the dielectric and actuation properties of polyacrylate rubber (ACM) were studied after the addition of different vegetable‐based fillers such as potato starch, corn starch, garlic, and paprika. The results were compared to ACM filled with barium titanate. The compounds containing vegetable fillers showed higher relative dielectric permittivity at 1 Hz frequency than the compounds containing barium titanate due to higher interfacial polarization. The actuation studies showed that lower electric fields are required to generate certain actuation forces when the starches and garlic are used in the rubber instead of barium titanate. Therefore, the vegetable‐based fillers can be used to improve actuation performance of DEAs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45081.     

Energy dissipation in natural rubber latex films: The effect of stabilizers,leaching and acetone-treatment

Natural rubber (NR) is a versatile material possessing outstanding mechanical properties, which can be used in multiple applications including the rapidly developing dielectric elastomer generators (DEGs). One of the drawbacks of the existing DEGs is their low efficiency, which can be improved by lowering the dielectric and mechanical losses originating from the material. Therefore, the present research was focusing on assessing the ways to minimize the dielectric and mechanical losses of NR films rather than developing a DEG. In this article, the effect of natural proteins and the rubber stabilizers on energy dissipation of NR films was evaluated. Moreover, the effect of sample posttreatment (with water and acetone), curing and time after cure was discussed. As a result, deproteinized NR stabilized by ammonium caseinate outperformed unmodified NR due to reduced dielectric losses, mechanical hysteresis and stress relaxation. Moreover, the posttreatment methods were found to moderately reduce the material-relates losses.     

Can we get from liking to buying? Behavioral differences in hedonic and utilitarian Facebook usage

Companies’ Facebook pages have emerged as a commonly used marketing channel and their importance as a sales channel is likely to increase. Details about consumers’ underlying motivations to use these pages need to be linked to their effect on the host company’s business. This study distinguishes between consumers’ hedonic and utilitarian motivations for using company-hosted Facebook pages and relates them to two types of community usage behavior: browsing and participation. The effects on variables closely linked to business performance are examined. Analysis of data collected from 1162 members of a travel agency’s Facebook page reveals that hedonic motivations indicate a higher propensity to participate in the community whereas utilitarian motivations relate more strongly to merely browsing the community page. The participating members, however, do not show intentions to buy from the host company or refer it to others, while the browsers do. For practitioners, the finding that hedonic community participants are needed to maintain the community, but that they are unlikely to profit the company, is crucial.     

Predictors and outcomes of joint trajectories of callous–unemotional traits and conduct problems in childhood.

Callous–unemotional (CU) traits are associated with antisocial and delinquent behaviors in children and represent a potential risk factor for adult psychopathy. However, there is a paucity of longitudinal research that explores the development of these traits, their longitudinal association with conduct problems (CP), and their psychosocial predictors and outcomes. Using a large sample of children followed longitudinally from the Twins Early Development Study (N = 9,578), we described the joint developmental trajectories of CU traits and CP during childhood (between ages 7 and 12) and examined the child- and family-level predictors (4 years old) and concomitant outcomes (12 years old) associated with the trajectories. The developmental trajectories were characterized with teachers' ratings of CU traits and CP from ages 7 to 12. Using general growth mixture modeling, we identified four trajectories of CU traits (stable high, increasing, decreasing, and stable low) and two trajectories of CP (high and low). Compared with the children who followed a low trajectory of CU traits and CP, those who followed a high trajectory of CU traits and CP had more negative child- and family-level predictors at 4 years (including CP, hyperactivity, negative parental discipline, and chaos in the home). Children with high or increasing levels of CU traits and concomitant high levels of CP presented the most negative outcomes at 12 years (including hyperactivity, peer problems, emotional problems, and negative parental feelings). Children with high CU traits and concomitant high levels of CP in childhood should be prioritized for targeted intervention. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Metabolic effects of lactoferrin during energy restriction and weight regain in diet-induced obese mice

Lactoferrin (LF) is an iron-binding glycoprotein exerting several physiological functions such as antimicrobial activity, modulatory effects on lipid metabolism and anti-inflammatory properties. We examined whether LF prevents diet-induced obesity and development of fatty liver formation in C57Bl/6J mice. Lactoferrin (15% of dietary casein replaced by LF) enhanced weight loss and decreased body fat content during energy restriction compared to casein without influencing energy intake. During the ad libitum feeding after weight loss, LF suppressed weight regain and protected against the development of fatty liver formation compared to casein without influencing energy intake or fecal fat excretion. During the weight regain phase LF also improved glucose tolerance, decreased skeletal muscle leptin mRNA expression, and ameliorated adipose tissue inflammation. In conclusion, LF supplementation enhances the outcome of weight loss and subsequent weight regain, ameliorates fatty liver formation, and exerts beneficial effects on glucose tolerance and adipocyte tissue inflammation without interfering energy intake.     

Load Theory of Selective Attention and Cognitive Control.

A load theory of attention in which distractor rejection depends on the level and type of load involved in current processing was tested. A series of experiments demonstrates that whereas high perceptual load reduces distractor interference, working memory load or dual-task coordination load increases distractor interference. These findings suggest 2 selective attention mechanisms: a perceptual selection mechanism serving to reduce distractor perception in situations of high perceptual load that exhaust perceptual capacity in processing relevant stimuli and a cognitive control mechanism that reduces interference from perceived distractors as long as cognitive control functions are available to maintain current priorities (low cognitive load). This theory resolves the long-standing early versus late selection debate and clarifies the role of cognitive control in selective attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Networking relations of using ICT within a teacher community

The purpose of the present study was to examine the network structure of a teacher community in relation to their use of information and communication technology (ICT). The participants in the study were the 33 members of the teacher community of an upper comprehensive school from a suburban area of Helsinki, Finland. The methodology of the study was social network analysis. The participants were asked to assess their networking relations according to the following five dimensions: (1) providing technical advice regarding ICT, (2) providing pedagogical advice for using ICT, (3) collaboration regarding web-based learning, (4) acquiring new knowledge or ideas of web-based learning, and (5) informal interaction between the members of the community. The results indicated that there were a few central actors in the community who dominated technical and pedagogical knowledge exchange and to whom their colleagues actively turned when seeking advice. Two of the cognitively central actors represented hybrid expertise, a characteristic of which was to merge technological and pedagogical expertise in using ICT in education. These actors also tended to have their own external networking relations that helped them keep up their high level of competence. The participants’ ICT-related egocentric networks differed in size and density. There were some actors central in the network of informal interaction that were, simultaneously, peripheral in ICT-related networking activities. On the other hand, the central actors of ICT were not necessarily the socially central persons in the community. Four patterns of networking were identified in the analysis; The Counsellor offers advice actively without seeking information herself from colleagues; The Inquirer is an active seeker of ICT-related information capitalizing on her social relations; The Collaborator engages in collaborative efforts of web-based learning by using several media; and The Weakly Social prefers media rather than face-to-face contacts in his information seeking.