A Dye-sensitized Nanocrystalline Solid State Photovoltaic Cell

A new type of dye-sensitized nanocrystalline solid state photovoltaic cell based on the wide band gap n-TiO2/p-CuI heterojunction was fabricated. Tetra-carboxyphenyl porphyrine (TPP-(COOH)(4)), squarylium cyanine derivative (SQ-(CH2),(SO3Py+)-Py-.) and ruthenium bipyridyl complex (RuL2(NCS)(2)) were used as photosensitizers. Larger photocurrents and photovoltages were shown in the cell sensitized by ruthenium bipyridyl complex and can be further increased by intercalation of a TiO2 thin underlayer.

An increment of diversity method for cell state trajectory inference of time-series scRNA-seq data

The increasing emergence of the time-series single-cell RNA sequencing(scRNA-seq)data,inferring developmental trajectory by connecting transcriptome similar cell states(i.e.,cell types or clusters)has become a major challenge.Most existing computational methods are designed for individual cells and do not take into account the available time series information.We present IDTI based on the Increment of Diversity for Trajectory Inference,which combines time series information and the minimum increment of diversity method to infer cell state trajectory of time-series scRNA-seq data.We apply IDTI to simulated and three real diverse tissue development datasets,and compare it with six other commonly used trajectory inference methods in terms of topology similarity and branching accuracy.The results have shown that the IDTI method accurately constructs the cell state trajectory without the requirement of starting cells.In the performance test,we further demonstrate that IDTI has the advantages of high accuracy and strong robustness.

Transitions between epithelial and mesenchymal states during cell fate conversions

Cell fate conversion is considered as the changing of one type of cells to another type including somatic cell reprogramming （de-differentiation）, differentiation, and trans-differentiation, Epithelial and mesenchymal cells are two major types of cells and the transitions between these two cell states as epithelial-mesenchymal transi- tion （EMT） and mesenchymal-epithelial transition （MET） have been observed during multiple cell fate conversions including embryonic development, tumor progression and somatic cell reprogramming. In addition, MET and sequential EMT-MET during the generation of induced pluripotent stem cells （iPSC） from fibroblasts have been reported recently. Such observation is consistent with multiple rounds of sequential EMT-MET during embryonic development which could be considered as a reversed process of reprogramming at least partially. Therefore in current review, we briefly discussed the potential roles played by EMT, MET, or even sequential EMT-MET during different kinds of cell fate conversions. We also provided some preliminary hypotheses on the mechanisms that connect cell state transitions and cell fate conversions based on results collected from cell cycle, epigenetic regulation, and sternness acquisition.

Single-Cell Transcriptome Analysis in Plants:Advances and Challenges

The rapid and enthusiastic adoption of single-cell RNA sequencing(scRNA-seq)has demonstrated that this technology is far more than just another way to perform transcriptome analysis.It is not an exaggeration to say that the advent of scRNA-seq is revolutionizing the details of whole-transcriptome snapshots from a tissue to a cell.With this disruptive technology,it is now possible to mine heterogeneity between tissue types and within cells like never before.This enables more rapid identification of rare and novel cell types,simultaneous characterization of multiple different cell types and states,more accurate and integrated understanding of their roles in life processes,and more.However,we are only at the beginning of unlocking the full potential of scRNA-seq applications.This is particularly true for plant sciences,where single-cell transcriptome profiling is in its early stage and has many exciting challenges to overcome.In this review,we compare and evaluate recent pioneering studies using the A rabidopsis root model,which has established new paradigms for scRNA-seq studies in plants.We also explore several new and promising single-cell analysis tools that are available to those wishing to study plant development and physiology at unprecedented resolution and scale.In addition,we propose some future directions on the use of scRNA-seq technology to tackle some of the critical challenges in plant research and breeding.

Pyridine Nucleotide Cycling and Control of Intracellular Redox State in Relation to Poly （ADP-Ribose） Polymerase Activity and Nuclear Localization of Glutathione during Exponential Growth of Arabidopsis Cells in Culture

Pyridine nucleotides, ascorbate and glutathione are major redox metabolites in plant cells, with specific roles in cellular redox homeostasis and the regulation of the cell cycle. However, the regulation of these metabolite pools during exponential growth and their precise functions in the cell cycle remain to be characterized. The present analysis of the abundance of ascorbate, glutathione, and pyridine nucleotides during exponential growth of Arabidopsis cells in culture provides evidence for the differential regulation of each of these redox pools. Ascorbate was most abundant early in the growth cycle, but glutathione was low at this point. The cellular ascorbate to dehydroascorbate and reduced glutathione （GSH） to glutathione disulphide ratios were high and constant but the pyridine nucleotide pools were largely oxidized over the period of exponential growth and only became more reduced once growth had ceased. The glutathione pool increased in parallel with poly （ADP-ribose） polymerase （PARP） activities and with increases in the abundance of PARP1 and PARP2 mRNAs at a time of high cell cycle activity as indicated by transcriptome information. Marked changes in the intracellular partitioning of GSH between the cytoplasm and nucleus were observed. Extension of the exponential growth phase by dilution or changing the media led to increases in the glutathione and nicotinamide adenine dinucleotide, oxidized form （NAD）-plus-nicotinamide adenine dinucleotide, reduced form （NADH） pools and to higher NAD/NADH ratios but the nicotinamide adenine dinucleotide phosphate, oxidized form （NADP）-plus-nicotinamide adenine dinucleotide phosphate, reduced form （NADPH） pool sizes, and NAPD/NADPH ratios were much less affected. The ascorbate, glutathione, and pyridine nucleotide pools and PARP activity decreased before the exponential growth phase ended. We conclude that there are marked changes in intracellular redox state during the growth cycle but that redox homeostasis is maintained by interplay of the major redox pyridine nucleotides, glutathione, and ascorbate pools. The correlation between PARP expression and activity and GSH accumulation and the finding that GSH can be recruited to the nucleus suggest a relationship between redox regulation and nuclear enzyme activity.

Significant differences of function and expression of microRNAs between ground state and serum-cultured pluripotent stem cells

Serum- and 2i-cultured embryonic stem cells （ESCs） show different epigenetic landscapes and tran- scriptomic profiles. The difference in the function and expression of microRNAs （miRNAs） between these two states remains unclear. Here, we showed that 2i- and serum-cultured ESCs exhibited distinctive miRNA expression profiles with 〉100 miRNAs differentially expressed, and the expression changes were largely due to transcriptional regulation. We further characterized the function of miRNAs differentially expressed under two conditions and found that ESCs exhibited higher degree of dependency on miRNAs for rapid proliferation; since Dgcr8-/- or Dicerl-I- but not wild-type ESCs showed slower growth rate and more accumulation in the G1 phase under 2i than serum condition. More interestingly, introduction of various self-renewal-silencing miRNAs in wild-type or Dgcr8/- ESCs failed to silence the self-renewal in 2i medium, but regained the ability to silence the self-renewal upon the addition of serum. Our findings reveal significant differences in the expression and function of miRNAs between serum- and 2i- cultured ESCs.

SuperFeat:Quantitative Feature Learning from Single-cell RNA-seq Data Facilitates Drug Repurposing

In this study,we devised a computational framework called Supervised Feature Learning and Scoring(SuperFeat)which enables the training of a machine learning model and evaluates the canonical cellular statuses/features in pathological tissues that underlie the progression of disease.This framework also enables the identification of potential drugs that target the presumed detrimental cellular features.This framework was constructed on the basis of an artificial neural network with the gene expression profiles serving as input nodes.The training data comprised single-cell RNA sequencing datasets that encompassed the specific cell lineage during the developmental progression of cell features.A few models of the canonical cancer-involved cellular statuses/features were tested by such framework.Finally,we illustrated the drug repurposing pipeline,utilizing the training parameters derived from the adverse cellular statuses/features,which yielded successful validation results both in vitro and in vivo.SuperFeat is accessible at https://github.com/weilin-genomics/rSuperFeat.