Taking a nuanced look at adolescent technology use and negative affect: the protective role of preparedness.

Adolescents are online more than any other age group, with the majority of their time on social media. Increases in technology use among adolescents have heightened conversations regarding its effects on their negative affect. There have been mixed findings regarding the relationship between technology use and adolescent negative affect; some studies present a negative association or no association, and some show a positive association. To clarify this relationship, we propose moving away from asking only how much adolescents use technology to asking how and what they use it for. We employed the Multidimensional Healthy Technology Use and Social Media Habits Scale (MTECH) and adapted forms of the Positive and Negative Affect Schedule (PANAS) in a sample of 7,234 middle and high school students to assess the extent to which students feel prepared to use technology safely and successfully and whether this impacts the association between the amount of various types of technology they use and their negative affect. We conducted eight moderated regression analyses that, in some models, revealed preparedness had a protective role in the association between technology use and negative affect. In these models, at all levels of technology use, adolescents with higher levels of preparedness experienced lower levels of negative affect than their peers; however, in some instances, this effect was diminished for those using technology with high frequency. These findings support the notion that the association between technology and negative affect is not best modeled as a direct relationship, and instead that we must consider important moderators of this complex association.

Digital and In-Person Interpersonal Emotion Regulation: The Role of Anxiety, Depression, and Stress.

Interpersonal emotion regulation (IER) is the process by which individuals change their emotional experiences by socially interacting with others. While the literature on IER for in-person settings is growing, there is a dearth of research exploring IER in digital social interactions (i.e., via technology) - especially when considering the presence of psychopathology. The aim of this study was to compare perceived IER efficacy and use in digital versus in-person contexts and explore the impact that anxiety, depression, and stress have on IER. A sample of 93 university undergraduate students showed that participants perceived in-person IER as more efficacious than digital IER, and participants high in anxiety, depression, and stress tended to use both modalities of IER more than those low anxiety, depression, and stress. This study addresses a critical gap in our understanding of emotion regulation in digital environments and sheds light on how this is related to psychopathology and the psychotherapy experience.

Quantitative tRNA-sequencing uncovers metazoan tissue-specific tRNA regulation.

Transfer RNAs (tRNA) are quintessential in deciphering the genetic code; disseminating nucleic acid triplets into correct amino acid identity. While this decoding function is clear, an emerging theme is that tRNA abundance and functionality can powerfully impact protein production rate, folding, activity, and messenger RNA stability. Importantly, however, the expression pattern of tRNAs is obliquely known. Here we present Quantitative Mature tRNA sequencing (QuantM-tRNA seq), a technique to monitor tRNA abundance and sequence variants secondary to RNA modifications. With QuantM-tRNA seq, we assess the tRNA transcriptome in mammalian tissues. We observe dramatic distinctions in isodecoder expression and known tRNA modifications between tissues. Remarkably, despite dramatic changes in tRNA isodecoder gene expression, the overall anticodon pool of each tRNA family is similar across tissues. These findings suggest that while anticodon pools appear to be buffered via an unknown mechanism, underlying transcriptomic and epitranscriptomic differences suggest a more complex tRNA regulatory landscape.

Gene-centric functional dissection of human genetic variation uncovers regulators of hematopoiesis.

Genome-wide association studies (GWAS) have identified thousands of variants associated with human diseases and traits. However, the majority of GWAS-implicated variants are in non-coding regions of the genome and require in depth follow-up to identify target genes and decipher biological mechanisms. Here, rather than focusing on causal variants, we have undertaken a pooled loss-of-function screen in primary hematopoietic cells to interrogate 389 candidate genes contained in 75 loci associated with red blood cell traits. Using this approach, we identify 77 genes at 38 GWAS loci, with most loci harboring 1-2 candidate genes. Importantly, the hit set was strongly enriched for genes validated through orthogonal genetic approaches. Genes identified by this approach are enriched in specific and relevant biological pathways, allowing regulators of human erythropoiesis and modifiers of blood diseases to be defined. More generally, this functional screen provides a paradigm for gene-centric follow up of GWAS for a variety of human diseases and traits.

High-throughput combinatorial screening reveals interactions between signaling molecules that regulate adult neural stem cell fate.

Advancing our knowledge of how neural stem cell (NSC) behavior in the adult hippocampus is regulated has implications for elucidating basic mechanisms of learning and memory as well as for neurodegenerative disease therapy. To date, numerous biochemical cues from the endogenous hippocampal NSC niche have been identified as modulators of NSC quiescence, proliferation, and differentiation; however, the complex repertoire of signaling factors within stem cell niches raises the question of how cues act in combination with one another to influence NSC physiology. To help overcome experimental bottlenecks in studying this question, we adapted a high-throughput microculture system, with over 500 distinct microenvironments, to conduct a systematic combinatorial screen of key signaling cues and collect high-content phenotype data on endpoint NSC populations. This novel application of the platform consumed only 0.2% of reagent volumes used in conventional 96-well plates, and resulted in the discovery of numerous statistically significant interactions among key endogenous signals. Antagonistic relationships between fibroblast growth factor 2, transforming growth factor ß (TGF-ß), and Wnt-3a were found to impact NSC proliferation and differentiation, whereas a synergistic relationship between Wnt-3a and Ephrin-B2 on neuronal differentiation and maturation was found. Furthermore, TGF-ß and bone morphogenetic protein 4 combined with Wnt-3a and Ephrin-B2 resulted in a coordinated effect on neuronal differentiation and maturation. Overall, this study offers candidates for further elucidation of significant mechanisms guiding NSC fate choice and contributes strategies for enhancing control over stem cell-based therapies for neurodegenerative diseases.

Ribosome Levels Selectively Regulate Translation and Lineage Commitment in Human Hematopoiesis.

Blood cell formation is classically thought to occur through a hierarchical differentiation process, although recent studies have shown that lineage commitment may occur earlier in hematopoietic stem and progenitor cells (HSPCs). The relevance to human blood diseases and the underlying regulation of these refined models remain poorly understood. By studying a genetic blood disorder, Diamond-Blackfan anemia (DBA), where the majority of mutations affect ribosomal proteins and the erythroid lineage is selectively perturbed, we are able to gain mechanistic insight into how lineage commitment is programmed normally and disrupted in disease. We show that in DBA, the pool of available ribosomes is limited, while ribosome composition remains constant. Surprisingly, this global reduction in ribosome levels more profoundly alters translation of a select subset of transcripts. We show how the reduced translation of select transcripts in HSPCs can impair erythroid lineage commitment, illuminating a regulatory role for ribosome levels in cellular differentiation.

Developmentally-faithful and effective human erythropoiesis in immunodeficient and Kit mutant mice.

Immunodeficient mouse models have been valuable for studies of human hematopoiesis, but high-fidelity recapitulation of erythropoiesis in most xenograft recipients remains elusive. Recently developed immunodeficient and Kit mutant mice, however, have provided a suitable background to achieve higher-level human erythropoiesis after long-term hematopoietic engraftment. While there has been some characterization of human erythropoiesis in these models, a comprehensive analysis from various human developmental stages has not yet been reported. Here, we have utilized cell surface phenotypes, morphologic analyses, and molecular studies to fully characterize human erythropoiesis from multiple developmental stages in immunodeficient and Kit mutant mouse models following long-term hematopoietic stem and progenitor cell engraftment. We show that human erythropoiesis in such models demonstrates complete maturation and enucleation, as well as developmentally appropriate globin gene expression. These results provide a framework for future studies to utilize this model system for interrogating disorders affecting human erythropoiesis and for developing improved therapeutic approaches.

High-Throughput Toxicity and Phenotypic Screening of 3D Human Neural Progenitor Cell Cultures on a Microarray Chip Platform.

A 3D cell culture chip was used for high-throughput screening of a human neural progenitor cell line. The differential toxicity of 24 compounds was determined on undifferentiated and differentiating NPCs. Five compounds led to significant differences in IC50 values between undifferentiated and differentiating cultures. This platform has potential use in phenotypic screening to elucidate molecular toxicology on human stem cells.

Assembly of bacteriophage into functional materials.

For the last decade, the fabrication of ordered structures of phage has been of great interest as a means of utilizing the outstanding biochemical properties of phage in developing useful materials. Combined with other organic/inorganic substances, it has been demonstrated that phage is a superior building block for fabricating various functional devices, such as the electrode in lithium-ion batteries, photovoltaic cells, sensors, and cell-culture supports. Although previous research has expanded the utility of phage when combined with genetic engineering, most improvements in device functionality have relied upon increases in efficiency owing to the compact, more densely packable unit size of phage rather than on the unique properties of the ordered nanostructures themselves. Recently, self-templating methods, which control both thermodynamic and kinetic factors during the deposition process, have opened up new routes to exploiting the ordered structural properties of hierarchically organized phage architectures. In addition, ordered phage films have exhibited unexpected functional properties, such as structural color and optical filtering. Structural colors or optical filtering from phage films can be used for optical phage-based sensors, which combine the structural properties of phage with target-specific binding motifs on the phage-coat proteins. This self-templating method may contribute not only to practical applications, but also provide insight into the fundamental study of biomacromolecule assembly in in vivo systems under complicated and dynamic conditions.

Coupling molecular beacons to barcoded metal nanowires for multiplexed, sealed chamber DNA bioassays.

We have combined molecular beacon (MB) probes with barcoded metal nanowires to enable no-wash, sealed chamber, multiplexed detection of nucleic acids. Probe design and experimental parameters important in nanowire-based MB assays are discussed. Loop regions of 24 bases and 5 base pair stem regions in the beacon probes gave optimal performance. Our results suggest that thermodynamic predictions for secondary structure stability of solution-phase MB can guide probe design for nanowire-based assays. Dengue virus-specific probes with predicted solution-phase DeltaG of folding in 500 mM buffered NaCl of approximately -4 kcal/mol performed better than those with DeltaG > -2 or < -6 kcal/mol. Buffered 300-500 mM NaCl was selected after comparison of several buffers previously reported for similar types of assays, and 200-500 mM NaCl was found to be the optimal ionic strength for the hybridization temperatures (25 and 50 degrees C) and probe designs used here. Target binding to the surface as a function of solution concentration fit a Sips isotherm with Kd = 1.7 +/- 0.3 nM. The detection limit was approximately 100 pM, limited by incomplete quenching. Single base mismatches could be discriminated from fully complementary targets. Oligonucleotide target sequences specific for human immunodeficiency, hepatitis C, and severe acute respiratory viruses were assayed simultaneously in a no-wash, sealed chamber, multiplexed experiment in which each of three probe sequences was attached to a different pattern of encoded nanowires. Finally, we demonstrated that probe-coated nanowires retain their selectivity and sensitivity in a triplexed assay after storage for over 3 months.