Gel electrophoretic mobility evaluation of a necklace-like DNA nanostructure

DNA nanotechnologies have been highlighted as a promising synthetic tool for the creation of new shaped materials. They have developed a variety of materials in different shapes and sizes [1]. Inspired by these advancements, we sought to design a ring-shaped DNA nanostructure connected by X-DNA blocks. Six XDNA blocks were ligated together to form a circular nanostructure with a diameter of approximately 30 nm. Each DNA block possesses different overhang sequences in its terminal. It was sequentially built up onto each block platform in the line and later clipped into a necklace shape via enzymatic ligation. It was finally evaluated by a gel electrophoretic migration shift assay. It was concluded that the complete set of the necklace shaped DNA nanostructure was the most slowly retarded relative to other forms of incompleteness.     

The composition and structural characteristics of polysaccharides of the brown alga Eisenia bicyclis

The present study examines the polysaccharide composition of the brown alga Eisenia bicyclis. The major polysaccharide of E. bicyclis is shown to be sodium alginate (15.8% of the dry defatted alga weight). The yields of laminaran and fucoidan were 1.4% and 1.3% of the dry defatted alga weight, respectively. The alga contains laminaran (1,3;1,6-β-D-glucan) that has a unique structure, a high content of 1,6-linked D-glucose residues (the ratio of 1,3: 1,6 linkage is 1.5: 1), and an unusually high molecular weight (19–27 kDa). The fucoidan fractions isolated from E. bicyclis are sulfated and acetylated heteropolysaccharides that differ in their sulfate content and monosaccharide composition.     

Genomic analysis of SARS-CoV-2 reveals local viral evolution in Ghana

The confirmed case fatality rate for the coronavirus disease 2019 (COVID-19) in Ghana has dropped from a peak of 2% in March to be consistently below 1% since May 2020. Globally, case fatality rates have been linked to the strains/clades of circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within a specific country. Here we present 46 whole genomes of SARS-CoV-2 circulating in Ghana, from two separate sequencing batches: 15 isolates from the early epidemic (March 12–April 1 2020) and 31 from later time-points ( 25–27 May 2020). Sequencing was carried out on an Illumina MiSeq system following an amplicon-based enrichment for SARS-CoV-2 cDNA. After genome assembly and quality control processes, phylogenetic analysis showed that the first batch of 15 genomes clustered into five clades: 19A, 19B, 20A, 20B, and 20C, whereas the second batch of 31 genomes clustered to only three clades 19B, 20A, and 20B. The imported cases (6/46) mapped to circulating viruses in their countries of origin, namely, India, Hungary, Norway, the United Kingdom, and the United States of America. All genomes mapped to the original Wuhan strain with high similarity (99.5–99.8%). All imported strains mapped to the European superclade A, whereas 5/9 locally infected individuals harbored the B4 clade, from the East Asian superclade B. Ghana appears to have 19B and 20B as the two largest circulating clades based on our sequence analyses. In line with global reports, the D614G linked viruses seem to be predominating. Comparison of Ghanaian SARS-CoV-2 genomes with global genomes indicates that Ghanaian strains have not diverged significantly from circulating strains commonly imported into Africa. The low level of diversity in our genomes may indicate lower levels of transmission, even for D614G viruses, which is consistent with the relatively low levels of infection reported in Ghana.     

Characterization of filamentous bacteriophage PE226 infecting Ralstonia solanacearum strains

Aims: The aim of this study was to isolate and characterize new bacteriophages that infect a wide range of plant pathogenic Ralstonia solanacearum strains. Methods and Results: Fifteen bacteriophages were isolated from pepper, tomato and tobacco plant rhizospheres infected with R. solanacearum. A host specificity analysis of the isolated phages using nine strains of R. solanacearum indicated great phage diversity in a single soil. Two phages, PE226 and TM227, showed clear plaques on all nine bacterial hosts tested and were virtually identical in morphology and genome. PE226, an Inovirus, is a long, flexible, filamentous phage carrying a circular (+) sense single‐strand DNA genome of 5475 nucleotides. DNA sequences of PE226 exhibited nine open reading frames (ORF) that were not highly similar to those of other phages infecting R. solanacearum. The genome organization of PE226 was partially similar to that of p12J of Ralstonia pickettii. One ORF of PE226 showed identity to the zot gene encoding zonula occludens toxin of Vibrio cholera. Orf7 of PE226 was also present in the genome of R. solanacearum strain SL341. However, SL341, a highly virulent strain in tomato, was still sensitive to phage PE226. Conclusions: A new, flexible, filamentous phage PE226 infected wide range of R. solanacearum strains and carried unique circular single‐strand DNA genome with an ORF encoding Zot‐like protein. Significance and Impact of the Study: PE226 may be a new type of temperate phage, based on its lytic nature on a wide range of hosts and the presence of a zot homologue in a host bacterial genome.     

The antifouling potentiality of galactosamine characterized from Vibrio vulnificus exopolysaccharide

To gain a better insight into biofilm composition, the exopolysaccharide (EPS) of the Gram-negative bacterium Vibrio vulnificus was studied. Monosaccharide composition analysis of the wild-type and mutant V. vulnificus EPS carried out with Bio-liquid chromatography revealed the presence of d-glucosamine, d-galactose, d-glucose and d-xylose in both strains. d-Galactosamine was found only in the mutant that formed less biofilm compared to its wild-type. The influence of galactosamine on biofilm formation was then studied by adding this substance gradually to six different Gram-negative/positive bacteria associated with various autoinducers. Four bacterial species known to use the autoinducer type-2 signaling system produced less biofilm in the presence of galactosamine. No significant inhibition of biofilm formation was observed in bacteria that produce autoinducer type-1 signal molecules. Galactosamine was also immobilized on polymeric nanofibers to determine its re-usability for the study of biofilm inhibition. The immobilized galactosamine retained >65% of its initial antifouling activity after 10 repeated uses. The results of this study suggest the antifouling role of galactosamine for bacteria that produce AI-2.     

LAR-RPTPs: synaptic adhesion molecules that shape synapse development

The synapse is the most elementary operating unit in neurons, creating neural circuits that underlie all brain functions. Synaptic adhesion molecules initiate neuronal synapse connections, promote their stabilization and refinement, and control long-term synaptic plasticity. Leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs) have previously been implicated as essential elements in central nervous system (CNS) development. Recent studies have demonstrated that LAR-RPTP family members are also involved in diverse synaptic functions, playing a role in synaptic adhesion pathways together with a host of distinct transmembrane proteins and serving as major synaptic adhesion molecules in governing pre- and postsynaptic development, dysfunctions of which may underlie various disorders. This review highlights the emerging role of LAR-RPTPs as synapse organizers in orchestrating synapse development.