STRUCTURAL CHARACTERIZATION OF GEMINI-BASED NANOPARTICLES FOR DELIVERY OF DNA

Cationic gemini surfactants have been used for delivery of DNA into cells. These cationic surfactants are known to strongly bind to DNA to form a complex. In the dilute regimen, when the gemini-DNA complexes are mixed with helper neutral lipids, they undergo spontaneous assembly to form particles that are able to transfect DNA into the cells. In this study, the structure of several gemini surfactants, gemini-DNA complexes and gemini-DNA-neutral lipids complexes were systematically examined by small angle x-ray scattering (SAXS). The gemini surfactants were found to form micelles of varying shapes and arrangements modulated by the nature of spacer region and tail lengths. This includes ellipsoidal and worm-like micelles (as in the case of the 12- s-12 series) and disk-shaped hexagonally packed micelles (as in the case of 16-3-16). In addition to the study of the gemini surfactants, the effect of varying the DNA: gemini charge ratio on the DNA-gemini assembly was studied. The scattering pattern has shown that in the presence of excess gemini surfactants, free unbound surfactants exist in the solution. Upon the addition of neutral lipids, DNA-gemini-neutral lipid complexes are formed. The scattering patterns of the latter showed evidence of a strong interaction of the neutral lipids with the free gemini surfactants and the overcharged DNA-gemini complexes. Effectively, overcharging DNA-gemini complexes seem to aid in its incorporation into the neutral lipid matrix. These findings shed the light on the structure of DNA-gemini-neutral lipid systems and provide insights into the factors that influence the spontaneity of the self-assembly process. More importantly, the presented work provides a general strategy that can be applied to the study of similar systems using small angle x-ray scattering. A helium and vacuum chambers were made to enable testing the feasibility of the technique at the Canadian Light Source. Further, a pipeline was written to automate the reduction and analysis of SAXS data

Identification of novel conserved functional motifs across most Influenza A viral strains

Abstract Background Influenza A virus poses a continuous threat to global public health. Design of novel universal drugs and vaccine requires a careful analysis of different strains of Influenza A viral genome from diverse hosts and subtypes. We performed a systematic in silico analysis of Influenza A viral segments of all available Influenza A viral strains and subtypes and grouped them based on host, subtype, and years isolated, and through multiple sequence alignments we extrapolated conserved regions, motifs, and accessible regions for functional mapping and annotation. Results Across all species and strains 87 highly conserved regions (conservation percentage > = 90%) and 19 functional motifs (conservation percentage = 100%) were found in PB2, PB1, PA, NP, M, and NS segments. The conservation percentage of these segments ranged between 94 - 98% in human strains (the most conserved), 85 - 93% in swine strains (the most variable), and 91 - 94% in avian strains. The most conserved segment was different in each host (PB1 for human strains, NS for avian strains, and M for swine strains). Target accessibility prediction yielded 324 accessible regions, with a single stranded probability > 0.5, of which 78 coincided with conserved regions. Some of the interesting annotations in these regions included sites for protein-protein interactions, the RNA binding groove, and the proton ion channel. Conclusions The influenza virus has evolved to adapt to its host through variations in the GC content and conservation percentage of the conserved regions. Nineteen universal conserved functional motifs were discovered, of which some were accessible regions with interesting biological functions. These regions will serve as a foundation for universal drug targets as well as universal vaccine design.</p

Electron Tomography: A Three-Dimensional Analytic Tool for Hard and Soft Materials Research.

Three-dimensional (3D) structural analysis is essential to understand the relationship between the structure and function of an object. Many analytical techniques, such as X-ray diffraction, neutron spectroscopy, and electron microscopy imaging, are used to provide structural information. Transmission electron microscopy (TEM), one of the most popular analytic tools, has been widely used for structural analysis in both physical and biological sciences for many decades, in which 3D objects are projected into two-dimensional (2D) images. In many cases, 2D-projection images are insufficient to understand the relationship between the 3D structure and the function of nanoscale objects. Electron tomography (ET) is a technique that retrieves 3D structural information from a tilt series of 2D projections, and is gradually becoming a mature technology with sub-nanometer resolution. Distinct methods to overcome sample-based limitations have been separately developed in both physical and biological science, although they share some basic concepts of ET. This review discusses the common basis for 3D characterization, and specifies difficulties and solutions regarding both hard and soft materials research. It is hoped that novel solutions based on current state-of-the-art techniques for advanced applications in hybrid matter systems can be motivated

Electron Tomography: A Three-Dimensional Analytic Tool for Hard and Soft Materials Research.

Three-dimensional (3D) structural analysis is essential to understand the relationship between the structure and function of an object. Many analytical techniques, such as X-ray diffraction, neutron spectroscopy, and electron microscopy imaging, are used to provide structural information. Transmission electron microscopy (TEM), one of the most popular analytic tools, has been widely used for structural analysis in both physical and biological sciences for many decades, in which 3D objects are projected into two-dimensional (2D) images. In many cases, 2D-projection images are insufficient to understand the relationship between the 3D structure and the function of nanoscale objects. Electron tomography (ET) is a technique that retrieves 3D structural information from a tilt series of 2D projections, and is gradually becoming a mature technology with sub-nanometer resolution. Distinct methods to overcome sample-based limitations have been separately developed in both physical and biological science, although they share some basic concepts of ET. This review discusses the common basis for 3D characterization, and specifies difficulties and solutions regarding both hard and soft materials research. It is hoped that novel solutions based on current state-of-the-art techniques for advanced applications in hybrid matter systems can be motivated

Interspecies transmission of SARS CoV-2 with special emphasis on viral mutations and ACE-2 receptor homology roles

ABSTRACTCOVID-19 outbreak was first reported in 2019, Wuhan, China. The spillover of the disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), to a wide range of pet, zoo, wild, and farm animals has emphasized potential zoonotic and reverse zoonotic viral transmission. Furthermore, it has evoked inquiries about susceptibility of different animal species to SARS-CoV-2 infection and role of these animals as viral reservoirs. Therefore, studying susceptible and non-susceptible hosts for SARS-CoV-2 infection could give a better understanding for the virus and will help in preventing further outbreaks. Here, we review structural aspects of SARS-CoV-2 spike protein, the effect of the different mutations observed in the spike protein, and the impact of ACE2 receptor variations in different animal hosts on inter-species transmission. Moreover, the SARS-CoV-2 spillover chain was reviewed. Combination of SARS-CoV-2 high mutation rate and homology of cellular ACE2 receptors enable the virus to transcend species barriers and facilitate its transmission between humans and animals