The LysR-type transcriptional factor PacR controls heterocyst differentiation and C/N metabolism in the cyanobacterium Anabaena PCC 7120.

PacR (All3953) has previously been identified as a global transcriptional regulator of carbon assimilation in cyanobacteria. In the facultative diazotrophic and filamentous cyanobacterium Anabaena PCC 7120 (Anabaena), inactivation of pacR has been shown to affect cell growth under various conditions. Nitrogen fixation in Anabaena occurs in heterocysts, cells differentiated semiregularly along the filaments following deprivation of combined nitrogen such as nitrate or ammonium.

A conserved protein inhibitor brings under check the activity of RNase E in cyanobacteria.

The bacterial ribonuclease RNase E plays a key role in RNA metabolism. Yet, with a large substrate spectrum and poor substrate specificity, its activity must be well controlled under different conditions. Only a few regulators of RNase E are known, limiting our understanding on posttranscriptional regulatory mechanisms in bacteria.

Global translational control by the transcriptional repressor TrcR in the filamentous cyanobacterium Anabaena sp. PCC 7120.

Transcriptional and translational regulations are important mechanisms for cell adaptation to environmental conditions. In addition to house-keeping tRNAs, the genome of the filamentous cyanobacterium Anabaena sp. strain PCC 7120 (Anabaena) has a long tRNA operon (trn operon) consisting of 26 genes present on a megaplasmid.

A c-di-GMP binding effector controls cell size in a cyanobacterium.

Cyclic-di-GMP (c-di-GMP) is a ubiquitous bacterial signaling molecule. It is also a critical player in the regulation of cell size and cell behaviors such as cell aggregation and phototaxis in cyanobacteria, which constitute an important group of prokaryotes for their roles in the ecology and evolution of the Earth. However, c-di-GMP receptors have never been revealed in cyanobacteria.

Control of Cell Size by c-di-GMP Requires a Two-Component Signaling System in the Cyanobacterium sp. Strain PCC 7120.

Each bacterial species possesses a specific cell size and morphology, which constitute important and recognizable physical traits. How bacteria maintain their particular cell size and morphology remains an essential question in microbiology. Cyanobacteria are oxygen-evolving photosynthetic prokaryotes.

A proteolytic pathway coordinates cell division and heterocyst differentiation in the cyanobacterium sp. PCC 7120.

The filamentous, multicellular cyanobacterium sp. PCC 7120 () is a prokaryotic model for the study of cell differentiation and cell-cell interactions. Upon combined-nitrogen deprivation, forms a particular cell type, heterocyst, for aerobic nitrogen fixation.

"Life is short, and art is long": RNA degradation in cyanobacteria and model bacteria.

RNA turnover plays critical roles in the regulation of gene expression and allows cells to respond rapidly to environmental changes. In bacteria, the mechanisms of RNA turnover have been extensively studied in the models and , but not much is known in other bacteria. Cyanobacteria are a diverse group of photosynthetic organisms that have great potential for the sustainable production of valuable products using CO and solar energy.

c-di-GMP Homeostasis Is Critical for Heterocyst Development in sp. PCC 7120.

c-di-GMP is a ubiquitous bacterial signal regulating various physiological process. PCC 7120 () is a filamentous cyanobacterium able to form regularly-spaced heterocysts for nitrogen fixation, in response to combined-nitrogen deprivation in 24h. possesses 16 genes encoding proteins for c-di-GMP metabolism, and their functions are poorly characterized, except () whose deletion causes a decrease in heterocyst frequency 48h after nitrogen starvation.

Functions of the Essential Gene in Cellular Morphogenesis and Development of the Filamentous Cyanobacterium PCC 7120.

Bacterial cell shape is determined by the peptidoglycan (PG) layer. The cyanobacterium sp. PCC 7120 () is a filamentous strain with ovoid-shaped cells connected together with incomplete cell constriction.

A CRISPR-Based Method for Constructing Conditional Mutations of Essential Genes in Cyanobacteria.

Cyanobacteria, a group of diverse bacteria capable of oxygenic photosynthesis, are excellent models for investigating many important cellular processes, such as photosynthesis, nitrogen fixation, and prokaryotic cell differentiation. They also have great potential to become the next-generation cell factories for sustainable biosynthesis of valuable products. However, genetic manipulation in cyanobacteria is not as convenient as in other model bacteria.

The developmental regulator PatD modulates assembly of the cell-division protein FtsZ in the cyanobacterium Anabaena sp. PCC 7120.

FtsZ is a tubulin-like GTPase that polymerizes to initiate the process of cell division in bacteria. Heterocysts are terminally differentiated cells of filamentous cyanobacteria that have lost the capacity for cell division and in which the ftsZ gene is downregulated. However, mechanisms of FtsZ regulation during heterocyst differentiation have been scarcely investigated.

HetF Protein Is a New Divisome Component in a Filamentous and Developmental Cyanobacterium.

Bacterial cell division, with a few exceptions, is driven by FtsZ through a treadmilling mechanism to remodel and constrict the rigid peptidoglycan (PG) layer. Yet different organisms may differ in the composition of the cell division complex (divisome). In the filamentous cyanobacterium sp.

RNA Interference by Cyanobacterial Feeding Demonstrates the Gene Is Essential for Ciliogenesis during Oral Apparatus Regeneration in .

In the giant ciliate , oral apparatus (OA) regeneration is an experimentally tractable regeneration paradigm that occurs via a series of morphological steps. OA regeneration is thought to be driven by a complex regulatory system that orchestrates the temporal expression of conserved and specific genes. We previously identified a -specific gene (named ) that was significantly upregulated during the ciliogenesis stages of OA regeneration, with an expression peak at the stage of the first OA cilia appearance.

The Proposed Neurotoxin β--Methylamino-l-Alanine (BMAA) Is Taken up through Amino-Acid Transport Systems in the Cyanobacterium PCC 7120.

Produced by cyanobacteria and some plants, BMAA is considered as an important environmental factor in the occurrence of some neurodegenerative diseases. Neither the underlying mechanism of its toxicity, nor its biosynthetic or metabolic pathway in cyanobacteria is understood. Interestingly, BMAA is found to be toxic to some cyanobacteria, making it possible to dissect the mechanism of BMAA metabolism by genetic approaches using these organisms.

RNase II binds to RNase E and modulates its endoribonucleolytic activity in the cyanobacterium Anabaena PCC 7120.

In Escherichia coli, the endoribonuclease E (RNase E) can recruit several other ribonucleases and regulatory proteins via its noncatalytic domain to form an RNA degradosome that controls cellular RNA turnover. Similar RNA degradation complexes have been found in other bacteria; however, their compositions are varied among different bacterial species. In cyanobacteria, only the exoribonuclease PNPase was shown to bind to the noncatalytic domain of RNase E.

, a Gene Regulated by NtcA, Is Involved in the Optimization of Heterocyst Frequency in the Cyanobacterium sp. Strain PCC 7120.

In the filamentous multicellular cyanobacterium sp. strain PCC 7120, 5 to 10% of the cells differentiate into heterocysts, which are specialized in N fixation. Heterocysts and vegetative cells are mutually dependent for filament growth through nutrient exchange.

The Influence of Culture on Attitudes Towards Humorous Advertising.

Humor has been widely used in advertising in recent decades. Various studies found that humor could significantly improve advertising performance. However, most of these studies were conducted in a Eastern context and did not consider cultural factors.

Matrine suppresses lung metastasis of human hepatocellular carcinoma by directly targeting matrix metalloproteinase-9.

Matrine is a natural compound derived from Radix Sophora flavescens which is a commonly used Chinese herb. Herein, we report that matrine may inhibit lung metastasis in liver cancer in mice. Invasion chamber assay, scratch-wound assay and orthotopic liver tumor implantation mice were introduced to investigate the potential pharmacological effects of matrine on human hepatocellular carcinoma (HCC).

Expanding the Potential of CRISPR-Cpf1-Based Genome Editing Technology in the Cyanobacterium Anabaena PCC 7120.

CRISPR systems, such as CRISPR-Cas9 and CRISPR-Cpf1, have been successfully used for genome editing in a variety of organisms. Although the technique of CRISPR-Cpf1 has been applied in cyanobacteria recently, its use was limited without exploiting the full potential of such a powerful genetic system. Using the cyanobacterium Anabaena PCC 7120 as a model strain, we improved the tools and designed genetic strategies based on CRISPR-Cpf1, which enabled us to realize genetic experiments that have been so far difficult to do in cyanobacteria.

Pancreatic Stellate Cells Activation and Matrix Metallopeptidase 2 Expression Correlate With Lymph Node Metastasis in Pancreatic Carcinoma.

Background: This study aimed to investigate the correlation between pancreatic stellate cell activation, matrix metallopeptidase 2 (MMP2) expression and lymph node metastasis in pancreatic carcinoma.

Methods: Alpha-smooth muscle actin (ACTA2), Desmin (DES) and MMP2 were detected in 40 pancreatic carcinoma patients and 10 cases of normal pancreas tissues using immunohistochemistry. Then MMP2 and ACTA2 expression profiles in pancreatic cancer were obtained from UCSC (University of California, Santa Cruz) and SurvExpress.

Diversity of Growth Patterns Probed in Live Cyanobacterial Cells Using a Fluorescent Analog of a Peptidoglycan Precursor.

Cyanobacteria were the first oxygenic photosynthetic organisms during evolution and were ancestors of plastids. Cyanobacterial cells exhibit an extraordinary diversity in their size and shape, and bacterial cell morphology largely depends on the synthesis and the dynamics of the peptidoglycan (PG) layer. Here, we used a fluorescence analog of the PG synthesis precursor D-Ala, 7-Hydroxycoumarin-amino-D-alanine (HADA), to probe the PG synthesis pattern in live cells of cyanobacteria with different morphology.

Coordinating carbon and nitrogen metabolic signaling through the cyanobacterial global repressor NdhR.

The coordination of carbon and nitrogen metabolism is essential for bacteria to adapt to nutritional variations in the environment, but the underlying mechanism remains poorly understood. In autotrophic cyanobacteria, high CO levels favor the carboxylase activity of ribulose 1,5 bisphosphate carboxylase/oxygenase (RuBisCO) to produce 3-phosphoglycerate, whereas low CO levels promote the oxygenase activity of RuBisCO, leading to 2-phosphoglycolate (2-PG) production. Thus, the 2-PG level is reversely correlated with that of 2-oxoglutarate (2-OG), which accumulates under a high carbon/nitrogen ratio and acts as a nitrogen-starvation signal.

RNase E forms a complex with polynucleotide phosphorylase in cyanobacteria via a cyanobacterial-specific nonapeptide in the noncatalytic region.

RNase E, a central component involved in bacterial RNA metabolism, usually has a highly conserved N-terminal catalytic domain but an extremely divergent C-terminal domain. While the C-terminal domain of RNase E in Escherichia coli recruits other components to form an RNA degradation complex, it is unknown if a similar function can be found for RNase E in other organisms due to the divergent feature of this domain. Here, we provide evidence showing that RNase E forms a complex with another essential ribonuclease-the polynucleotide phosphorylase (PNPase)-in cyanobacteria, a group of ecologically important and phylogenetically ancient organisms.

A transcriptional-switch model for Slr1738-controlled gene expression in the cyanobacterium Synechocystis.

Background: Protein-DNA interactions play a crucial role in the life of biological organisms in controlling transcription, regulation, as well as DNA recombination and repair. The deep understanding of these processes, which requires the atomic description of the interactions occurring between the proteins and their DNA partners is often limited by the absence of a 3D structure of such complexes.

Results: In this study, using a method combining sequence homology, structural analogy modeling and biochemical data, we first build the 3D structure of the complex between the poorly-characterized PerR-like regulator Slr1738 and its target DNA, which controls the defences against metal and oxidative stresses in Synechocystis.