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PurposeWith the rapid development of paid online social question and answer (Q&A) communities, monetary social functions have been introduced and have potential benefits for both platforms and users. However, these functions' impact on knowledge contribution remains uncertain. This study proposes a conceptual model based on the stimulus–organism–response framework, according to which monetary and non-monetary social functions can help nurture short-term and long-term relationships among community users, and thereafter improves social identity and knowledge-sharing intentions.Design/methodology/approachThis study selects Zhihu, a famous online social Q&A community in China, and conducts an online survey to collect data from its frequent users. A sample of 286 valid questionnaires was collected to test our research model by using a structural equation modeling method. In addition, a bootstrapping approach is used to test the mediation effect.FindingsResults indicate that monetary social functions help nurture short-term and long-term relationships among community users. However, non-monetary social functions only affect short-term relationships directly. Short-term and long-term relationships both have a positive relationship with social identity and thereafter improve users' knowledge-sharing intentions.Originality/valueThis study focuses on users' knowledge-sharing intentions in Q&A communities from the perspective of social. Specifically, we separated social functions in Q&A platforms into monetary and non-monetary ones and explored their impact on the development of short-term and long-term relationships. Results demonstrate the importance of monetary social functions and explain how monetary and non-monetary social functions affect users' knowledge-sharing intentions in different approaches.

One of the main causes of severe diabetic heart failure and mortality is diabetic cardiomyopathy (DCM), a cardiovascular condition attributable to diabetes with a high incidence, a complicated and unexplained pathophysiology, and poor treatment results. Current findings have demonstrated that the onset of diabetic cardiomyopathy involves autophagy, inflammation, and mitochondrial damage. Myocardial autophagy behaves differently in different states,and one of the targets for the detection and treatment of cardiovascular illnesses like diabetic cardiomyopathy may be the control of autophagy. The role of human umbilical cord Mesenchymal stem cells-derived exosomes (HUCMSC-EXO) as a non-cellular system in the repair of cardiomyocytes, the evolution of diabetic cardiomyopathy and their cardioprotective effects are gradually being recognized. This study's objectives were to assess the therapeutic benefits of HUCMSC-EXO for diabetic cardiomyopathy and to look into their potential mechanisms of action. High-speed centrifugation was used to extract HUCMSC-EXO, and the shape of the exosomes was examined using transmission electron microscopy. Immunoblotting was used to determine the expression of CD9, CD63, and TSG101 molecules on the surface of the exosomes. A high-fat, high-sugar diet mixed with streptozotocin was used to build a rat model of type 2 diabetic cardiomyopathy. Cardiac function, ventricular wall thickness and cardiac histological changes were examined by cardiac ultrasound, serum BNP and histology. In cardiac myocytes, HUCMSC-EXO reduced the levels of autophagy-related protein expression. Additionally, immunoblotting supported our suspicion that this mechanism is strongly tied to the activation of the AMPK-ULK1 signaling pathway. So, we propose that it would be a good strategy to follow for treating diabetic cardiomyopathy. These findings offer both fresh concepts for building a model of diabetic cardiomyopathy and a creative theoretical framework for using HUCMSC-EXO to treat diabetic cardiomyopathy in a clinical setting.

Influenza is an acute respiratory infectious disease that poses a threat to public health. We assessed the association between atmospheric visibility and influenza and influenza-like illness (ILI) in Wuxi city, China. Daily meteorological data, ILI activity, and influenza virus infection rates were collected between 31 December 2012 and 31 December 2017. A distributed lag non-linear model (DLNM) was used to analyze the exposure-lag-response of ILI and influenza activity and daily average visibility. A total of 12,800 cases were detected; 1046 cases (8.17%) were of Flu-A and 527 (4.12%) were of Flu-B infection. Our analysis suggested a non-linear relationship between atmospheric visibility and influenza: U-shaped for ILI, and L-shaped for Flu-A and Flu-B. Comparing low visibility (2.5 km) to ILI cases, the risk appeared between day 1 and day 2. For Flu-A, the risk appeared between days 5 and 9, whereas for Flu-B, the risk effect was much stronger and had a longer reaction delay, staying above zero until day 9. The protective effects of high visibility (14 km) on ILI and Flu-B occurred the same day or one day later. However, we found no association between high visibility and Flu-A. In conclusion, our study contributes novel evidence for the effects of atmospheric visibility on influenza. These findings are important for the development of influenza surveillance and early warning systems in Wuxi city.

Lipid droplets (LDs) are important organelles involved in energy storage and expenditure. LD dynamics has been investigated using genome-wide image screening methods in yeast and other model organisms. For most studies, genes were identified using two-dimensional images with LD enlargement as readout. Due to imaging limitation, reduction of LD size is seldom explored. Here, we aim to set up a screen that specifically utilizes reduced LD size as the readout. To achieve this, a novel yeast screen is set up to quantitatively and systematically identify genes that regulate LD size through a three-dimensional imaging-based approach. Cidea which promotes LD fusion and growth in mammalian cells was overexpressed in a yeast knockout library to induce large LD formation. Next, an automated, high-throughput image analysis method that monitors LD size was utilized. With this screen, we identified twelve genes that reduced LD size when deleted. The effects of eight of these genes on LD size were further validated in fld1 null strain background. In addition, six genes were previously identified as LD-regulating genes. To conclude, this methodology represents a promising strategy to screen for players in LD size control in both yeast and mammalian cells to aid in the investigation of LD-associated metabolic diseases.

Saccharomyces cerevisiae contains two genes for each core histone, which are presented as pairs under the control of a divergent promoter, i.e., HHT1-HHF1, HHT2-HHF2, HTA1-HTB1 and HTA2-HTB2. HHT1-HHF1, and HHT2-HHF2 encode histone H3 and H4 with identical amino acid sequences but under the control of differently regulated promoters. Previous mutagenesis studies were carried out by deleting one pair and mutating the other one. Here, we present the design and construction of three additional libraries covering HTA1-HTB1, HTA2-HTB2, and HHT1-HHF1 respectively. Together with the previously described library of HHT2-HHF2 mutants, a systematic and complete collection of mutants for each of the eight core S. cerevisiae histone genes becomes available. Each designed mutant was incorporated into the genome, generating three more corresponding libraries of yeast strains. We demonstrated that, although, under normal growth conditions, strains with single-copy integrated histone genes lacked phenotypes, in some growth conditions, growth deficiencies were observed. Specifically, we showed that addition of a second copy of the mutant histone gene could rescue the lethality in some previously known mutants that cannot survive with a single copy. This resource enables systematic studies of function of each nucleosome residue in plasmid, single-copy, and double-copy integrated formats.

The bacterium Escherichia coli remains the leading host for protein expression in large quantity for the purpose of crystallization or other biochemical studies. However, expression of multicomponent protein complexes remains a challenge, and is often laborious and time-consuming. Here we developed a method named EcoExpress, which allows efficient construction of plasmids to express individual protein with user-defined epitope-tag, followed by one-pot assembly of a single vector to express the entire protein complex for copurification. A versatile set of vectors was designed to provide various choices to control the expression of a protein with different promoters, and to accept different number of components for coexpression. Using EcoExpress, we demonstrated that each subunit within a protein complex could be expressed individually or simultaneously, and the entire complex could be copurified. In addition, to overcome the decreased assembly efficiency with the increasing number of components, a novel oligonucleotides blocking method was designed and tested. EcoExpress provides the scientific community with a toolbox to rapidly investigate the function of protein complexes.

INTRODUCTION It has long been an interesting question whether a living cell can be constructed from scratch in the lab, a goal that may not be realized anytime soon. Nonetheless, with advances in DNA synthesis technology, the complete genetic material of an organism can now be synthesized chemically. Hitherto, genomes of several organisms including viruses, phages, and bacteria have been designed and constructed. These synthetic genomes are able to direct all normal biological functions, capable of self-replication and production of offspring. Several years ago, a group of scientists worldwide formed an international consortium to reconstruct the genome of budding yeast, Saccharomyces cerevisiae . RATIONALE The synthetic yeast genome, designated Sc2.0, was designed according to a set of arbitrary rules, including the elimination of transposable elements and incorporation of specific DNA elements to facilitate further genome manipulation. Among the 16 S. cerevisiae chromosomes, chromosome XII is unique as one of the longest yeast chromosomes (~1 million base pairs) and additionally encodes the highly repetitive ribosomal DNA locus, which forms the well-organized nucleolus. We report on the design, construction, and characterization of chromosome XII, the physically largest chromosome in S. cerevisiae. RESULTS A 976,067–base pair linear chromosome, synXII, was designed based on the native chromosome XII sequence of S. cerevisiae , and chemically synthesized. SynXII was assembled using a two-step method involving, successive megachunk integration to produce six semisynthetic strains, followed by meiotic recombination–mediated assembly, yielding a full-length functional chromosome in S. cerevisiae. Minor growth defect “bugs” detected in synXII were caused by deletion of tRNA genes and were corrected by introducing an ectopic copy of a single tRNA gene. The ribosomal gene cluster (rDNA) on synXII was left intact during the assembly process and subsequently replaced by a modified rDNA unit. The same synthetic rDNA unit was also used to regenerate rDNA at three distinct chromosomal locations. The rDNA signature sequences of the internal transcribed spacer (ITS), often used to determine species identity by standard DNA barcoding procedures, were swapped to generate a Saccharomyces synXII strain that would be identified as S. bayanus. Remarkably, these substantial DNA changes had no detectable phenotypic consequences under various laboratory conditions. CONCLUSION The rDNA locus of synXII is highly plastic; not only can it be moved to other chromosomal loci, it can also be altered in its ITS region to masquerade as a distinct species as defined by DNA barcoding, used widely in taxonomy. The ability to perform “species morphing” reported here presumably reflects the degree of evolutionary flexibility by which these ITS regions change. However, this barcoding region is clearly not infinitely flexible, as only relatively modest intragenus base changes were tolerated. More severe intergenus differences in ITS sequence did not result in functional rDNAs, probably because of defects in rRNA processing. The ability to design, build, and debug a megabase-sized chromosome, together with the flexibility in rDNA locus position, speaks to the remarkable overall flexibility of the yeast genome. Hierarchical assembly and subsequent restructuring of synXII. SynXII was assembled in two steps: First, six semisynthetic synXII strains were built in which segments of native XII DNA were replaced with the corresponding designer sequences. Next, the semisynthetic strains were combined withmultiple rounds ofmating/sporulation, eventually generating a single strain encoding fulllength synXII.The rDNA repeats were removed, modified, and subsequently regenerated at distinct chromosomal locations for species morphing and genome restructuring.