Preparation of peroxidase: antiperoxidase (PAP) complexes for immunohistological labeling of monoclonal antibodies

The production of mouse peroxidase:antiperoxidase (PAP) complexes suitable for immunohistological use in conjunction with monoclonal antibodies is described. Three approaches were explored: 1) production of conventional polyclonal PAP complexes; 2) conversion of rabbit PAP to "pseudo-mouse PAP" by incubation with monoclonal mouse anti-rabbit immunoglobulin; 3) formation of PAP complexes from monoclonal mouse antiperoxidase. PAP complexes prepared by the latter technique gave the best immunohistological labeling reactions, being stable on storage and compatible with a wide range of human monoclonal antibodies. Gel filtration revealed that monoclonal PAP is of lower molecular weight than conventional PAP complexes (fulfilling theoretical predictions based on the monospecificity of monoclonal antibodies).     

A natural fusion of flavodiiron,rubredoxin, and rubredoxin oxidoreductase domains is a self-sufficient water-forming oxidase of Trichomonas vaginalis

Microaerophilic pathogens such as Giardia lamblia, Entamoeba histolytica, and Trichomonas vaginalis have robust oxygen consumption systems to detoxify oxygen and maintain intracellular redox balance. This oxygen consumption results from H₂O-forming NADH oxidase (NOX) activity of two distinct flavin-containing systems: H₂O-forming NOXes and multicomponent flavodiiron proteins (FDPs). Neither system is membrane bound, and both recycle NADH into oxidized NAD⁺ while simultaneously removing O₂ from the local environment. However, little is known about the specific contributions of these systems in T. vaginalis. In this study, we use bioinformatics and biochemical analyses to show that T. vaginalis lacks a NOX–like enzyme and instead harbors three paralogous genes (FDPF1–3), each encoding a natural fusion product between the N-terminal FDP, central rubredoxin (Rb), and C-terminal NADH:Rb oxidoreductase domains. Unlike a “stand-alone” FDP that lacks Rb and oxidoreductase domains, this natural fusion protein with fully populated flavin redox centers directly accepts reducing equivalents of NADH to catalyze the four-electron reduction of oxygen to water within a single polypeptide with an extremely high turnover. Furthermore, using single-particle cryo-EM, we present structural insights into the spatial organization of the FDP core within this multidomain fusion protein. Together, these results contribute to our understanding of systems that allow protozoan parasites to maintain optimal redox balance and survive transient exposure to oxic conditions.     

Emerging 2D Layered Materials for Perovskite Solar Cells

Perovskite solar cells (PSCs) are now at the forefront of the state‐of‐the‐art photovoltaic technologies due to their high efficiency and low fabrication costs. To further realize the potential of this fascinating class of solar cells, nanostructured functional materials have been playing important roles. 2D layered materials have attracted a great deal of interest due to their fascinating properties and unique structure. Recently, the exploration of a wide range of novel 2D materials for use in PSCs has seen considerable progress, but still a lot remains to be done in this field. In this progress report, the advancements that have recently been made in the application of these emerging 2D materials, beyond graphene, for PSCs are presented. Both the advantages and challenges of these 2D materials for PSCs are highlighted. Finally, important directions for the future advancements toward efficient, low‐cost, and stable PSCs are outlined.     

Sex-specific differences in the prevalence of sarcopenia among pre-frail community-dwelling older adults in Saudi Arabia

ObjectivesTo assess sex differences in the prevalence of sarcopenia among pre-frail community-dwelling older adults in Saudi Arabia.MethodsThis was a cross-sectional study conducted at a tertiary-level hospital in Riyadh, Saudi Arabia, in 2019. The study participants were pre-frail community-dwelling older adults, according to the Edmonton Frail Scale. The SARC-F questionnaire was used to diagnose sarcopenia. The Katz Activities of Daily Living (ADL) was used to rank the adequacy of performance in six functions: bathing, dressing, toileting, transferring, continence, and feeding, while the Lawton Instrumental Activities of Daily Living scale was used to assess the more complex ADL necessary for living in the community.ResultsIn total, 283 community-dwelling older adults were recruited for this study, with a mean (±SD) age of 70.77 (±6.26) years; 72.7% of the total were female participants. The majority (85.5%) of the patients reported that they needed home care assistance. The mean ADL score of the participants was high, indicating high function and independence (KATZ-ADL: M 4.60 SD 1.75; Lawton Brody: 60%). The overall prevalence of sarcopenia among the studied participants was 65.7%, which was significantly higher among females (71.9%) than among males (59.1%), with a P-value of 0.007. Among the demographic characteristics of the participants, there was a significant difference in the need for home care assistance in female sarcopenic and non-sarcopenic participants (74.1% vs. 25.9%, p = 0.017), but without demonstrable difference in males. Additionally, there was a significant difference (P < 0.05) in the prevalence of sarcopenia between male and female participants according to ADL scores. The strongest predictor for sarcopenia prevalence in males was an ADL score <2 according to the Katz index, with an odds ratio of 6.5, while the need for home care was the only significant predictor of sarcopenia among female participants (OR 3.25, CI: 1.14–9.25, p = 0.02).ConclusionOverall, almost two-thirds of the studied pre-frail community-dwelling older adult population were sarcopenic. The prevalence of sarcopenia was significantly higher among females than males. The strongest predictor of sarcopenia was an ADL score <2 based on the Katz index in males and the need for home care assistance in females.     

Characterization of archaeal symbionts of sponges from the coral reef ecosystems of the Gulf of Mannar,Southeast coast of India

Sponges accommodate a diverse group of microorganisms with varied metabolic capabilities. The bacterial associates of sponges are widely studied while our understanding of archaeal counterparts is scanty. In the present study, we report the archaeal associates of two sponges, Pseudoceratina purpurea (NCBI barcode: KX454492) and Cinachyra sp. (NCBI barcode: KX454495), found in the coral reef ecosystems of Gulf of Mannar, India. Archaea in the water column was predominated by members of class Halobacteria of Phylum Euryarchaeota (97%) followed by a minor fraction (3%) of Nitrosopumilus sp. of phylum Thaumarchaeota. Interestingly, Thaumarchaeota was identified as the sole archaeal population associated with the two sponges studied, among which Nitrosopumilus sp. occuppied 80 and 100% of the sequences in the clone library of P. purpurea and Cinachyra sp. respectively. Other archaea found in the P. purpurea were Nitrososphaera (10%) and unclassified ones (10%). The study identified Nitrosopumilus sp. as a unique symbiotic archaeon of sponges, P. purpurea and Cinachyra sp. The existence of host driven factors in selecting specific associates from a diverse group of archaea in the environment may need further investigations.     

Is social distancing a boon or bane for persons who stutter during COVID-19 pandemic?

The Covid-19 pandemic is an ongoing crisis and is colloquially known as the corona virus pandemic. As no specific treatment protocol are available for this viral infection, social distancing is considered as one of the remedies to prevent the infection. This study aimed to investigate the anxiety issues in persons who stutter (PWS). A total of 110 (55 PWS and 55 Neuro-typical Adults) were enrolled for the study. A questionnaire comprising of two parts on social anxiety and consequences of social distancing was administered on the participants. The results showed that PWS felt more socially anxious. PWS opined that they were comfortable during the corona virus lockdown period, as the situation demanded them to speak minimally to strangers. Neuro-typical adults, on the other hand, reported that they did not observe any change with respect to the social communication skills during lockdown.     

Dual Substrate Model for Novel Approach Towards a Kinetic Study of Acetylcholinesterase Inhibition by Diazinon

Limited reports as compared to other insecticides appear in the literature for acetylcholinester-ase (AChE) inhibition by diazinon. In the current study, new kinetic parameters of AChE inhibition by diazinon have been investigated. The assay was done with bovine retinal AChE using two different substrate (ASCh) concentrations in the absence and presence of diazinon (0.08-1.28 mM). The optical density was monitored up to 25min (reaction time) for the assay. New kinetic parameters (k¹_oms, k¹_sms, k¹_oms, k¹_sms, k¹_asms and k¹_asms) were calculated from these experimental data.