How Visual Stimuli Evoked P300 is Transforming the Brain–Computer Interface Landscape: A PRISMA Compliant Systematic Review

Non-invasive Visual Stimuli evoked-EEGbased P300 BCIs have gained immense attention in recent years due to their ability to help patients with disability using BCI-controlled assistive devices and applications. In addition to the medical field, P300 BCI has applications in entertainment, robotics, and education. The current article systematically reviews 147 articles that were published between 2006-2021*. Articles that pass the pre-defined criteria are included in the study. Further, classification based on their primary focus, including article orientation, participants’ age groups, tasks given, databases, the EEG devices used in the studies, classification models, and application domain, is performed. The application-based classification considers a vast horizon, including medical assessment, assistance, diagnosis, applications, robotics, entertainment, etc. The analysis highlights an increasing potential for P300 detection using visual stimuli as a prominent and legitimate research area and demonstrates a significant growth in the research interest in the field of BCI spellers utilizing P300. This expansion was largely driven by the spread of wireless EEG devices, advances in computational intelligence methods, machine learning, neural networks and deep learning

Structural, Functional and Phylogenetic Analysis of Sperm Lysozyme-Like Proteins

<div><p>Sperm lysozyme-like proteins belonging to c-type lysozyme family evolved in multiple forms. Lysozyme-like proteins, <i>viz</i>., LYZL2, LYZL3 or SLLP1, LYZL4, LYZL5 and LYZL6 are expressed in the testis of mammals. Not all members of LYZL family have been uniformly and unambiguously identified in the genome and proteome of mammals. Some studies suggested a role of SLLP1 and LYZL4 in fertilization; however, the function of other LYZL proteins is unknown. We identified all known forms of LYZL proteins in buffalo sperm by LC-MS/MS. Cloning and sequence analysis of the <i>Lyzl</i> cDNA showed 38–50% identity at amino acid level among the buffalo LYZL paralogs, complete conservation of eight cysteines and other signature sequences of c-type lysozyme family. Catalytic residues in SLLP1, LYZL4 and LYZL5 have undergone replacement. The substrate binding residues showed significant variation in LYZL proteins. Residues at sites 62, 101, 114 in LYZL4; 101 in SLLP1; 37, 62, and 101 in LYZL6 were more variable among diverse species. Sites 63 and 108 occupied by tryptophan were least tolerant to variation. Site 37 also showed lower tolerance to substitution in SLLP1, LYZL4 and LYZL5, but more variable in non-testicular lysozymes. Models of LYZL proteins were created by homology modeling and the substrate binding pockets were analyzed in term of binding energies and contacting residues of LYZL proteins with tri-N-acetylglucosamine (NAG)₃ in the A-B-C and B-C-D binding mode. Except LYZL6, LYZL proteins did not show significant difference in binding energies in comparison to hen egg white lysozyme in the A-B-C mode. (NAG)₃ binding energy in the B-C-D mode was higher by 1.3–2.2 kcal/mol than in A-B-C mode. Structural analysis indicated that (NAG)₃ was involved in making more extensive interactions including hydrogen bonding with LYZL proteins in B-C-D mode than in A-B-C mode. Despite large sequence divergence among themselves and with respect to c-type lysozymes, substrate binding residues as well as hydrogen bonding network between (NAG)₃ and proteins were mostly conserved. LYZL5 in buffalo and other mammalian species contained additional 10–12 amino acid sequence at c-terminal that matched with ankyrin repeat domain-containing protein 27. Phylogenetic analysis indicated LYZL2 to be most ancient among all the LYZL proteins and that the evolution of LYZL proteins occurred through several gene duplications preceding the speciation of mammals from other vertebrates as distant as reptiles and amphibians.</p></div

Structural models of lysozyme-like proteins complexed with (NAG)₃ based on several template structures.

<p>PDB IDs of template are provided in material method part. For clarity only one model for each LYZL protein is shown. Panels a–LYZL2, b–SLLP1, c–LYZL4, d–LYZL5, e–LYZL6 and f– 1JEF (TEWL as one of the template). The protein part is shown in gray color and (NAG)₃ molecule in ball and stick style has been shown in elemental colors. The substrate binding residues interacting with (NAG)₃ are shown in three letter amino acid codes, while catalytic residues (residues at position 35 and 52 or 53) are labelled with single letter code. The NAG monomer binding subsites are represented by capital letters A, B and C in panel f.</p

Multiple sequence alignment of deduced amino acid sequences of buffalo matured LYZL2, SLLP1, LYZL4, LYZL5, LYZL6 and HEWL.

<p>The sequence shown within the red color box indicates specific signature of lysozyme family. The conserved cysteine and tryptophan residues are highlighted with yellow and green color bars, respectively. The catalytic residues corresponding to positions 35 and 52 of c-type lysozyme are shown in red color and underlined. The residues marked with diamond (♦) in blue color represent substrate binding sites in c-type lysozymes.</p

Substrate binding residues in c-type lysozyme family.

<p>Substrate binding residues in c-type lysozyme family.</p

Structural and functional insights into the catalytic inactivity of the major fraction of buffalo milk xanthine oxidoreductase.

BACKGROUND: Xanthine oxidoreductase (XOR) existing in two interconvertible forms, xanthine dehydrogenase (XDH) and xanthine oxidase (XO), catabolises xanthine to uric acid that is further broken down to antioxidative agent allantoin. XOR also produces free radicals serving as second messenger and microbicidal agent. Large variation in the XO activity has been observed among various species. Both hypo and hyper activity of XOR leads to pathophysiological conditions. Given the important nutritional role of buffalo milk in human health especially in south Asia, it is crucial to understand the functional properties of buffalo XOR and the underlying structural basis of variations in comparison to other species. METHODS AND FINDINGS: Buffalo XO activity of 0.75 U/mg was almost half of cattle XO activity. Enzymatic efficiency (k cat/K m) of 0.11 sec(-1) µM(-1) of buffalo XO was 8-10 times smaller than that of cattle XO. Buffalo XOR also showed lower antibacterial activity than cattle XOR. A CD value (Δε430 nm) of 46,000 M(-1) cm(-1) suggested occupancy of 77.4% at Fe/S I centre. Buffalo XOR contained 0.31 molybdenum atom/subunit of which 48% existed in active sulfo form. The active form of XO in buffalo was only 16% in comparison to ∼30% in cattle. Sequencing revealed 97.4% similarity between buffalo and cattle XOR. FAD domain was least conserved, while metal binding domains (Fe/S and Molybdenum) were highly conserved. Homology modelling of buffalo XOR showed several variations occurring in clusters, especially close to FAD binding pocket which could affect NAD(+) entry in the FAD centre. The difference in XO activity seems to be originating from cofactor deficiency, especially molybdenum. CONCLUSION: A major fraction of buffalo milk XOR exists in a catalytically inactive form due to high content of demolybdo and desulfo forms. Lower Fe/S content and structural factors might be contributing to lower enzymatic efficiency of buffalo XOR in a minor way

Binding energy, contacting residues and hydrogen bonding residues of LYZL with (NAG)₃ in their complex structures.

<p>Binding energy, contacting residues and hydrogen bonding residues of LYZL with (NAG)₃ in their complex structures.</p

Phylogenetic map of lysozyme family.

<p>The phylogenetic tree was constructed by using ML method. The nodes with diamond (♦) in blue color represent duplication event. LYZ-lysozyme, LYZL-lysozyme-like proteins, BoSt-cattle stomach, BuSt-buffalo stomach, ShSt-sheep stomach, BoMlk-cattle milk, BuMlk-buffalo milk, Hu-human, Ch-chimpanzee, Mc-monkey, Rt-rat, Mu-mouse, Bo-cattle, Bu-buffalo, Sh-sheep, Gt-goat, Py-python, Gr-garter snake. Lysozymes from non-mammals such as drosophila (Dr) and <i>Bombyx mori</i> (Bm) were used as outgroups.</p