bioRxiv Science⌕ Search

Biology subjects

Umar, M.

Publications and source records attributed to Umar, M..

5 recordsLinked to original sources

Creating a biomedical knowledge base by addressing GPT inaccurate responses and benchmarking context

We created GNQA, a generative pre-trained transformer (GPT) knowledge base driven by a performant retrieval augmented generation (RAG) with a focus on aging, dementia, Alzheimers and diabetes. We uploaded a corpus of three thousand peer reviewed publications on these topics into the RAG. To address concerns about inaccurate responses and GPT hallucinations, we implemented a context provenance tracking mechanism that enables researchers to validate responses against the original material and to get references to the original papers. To assess the effectiveness of contextual information we collected evaluations and feedback from both domain expert users and citizen scientists on the relevance of GPT responses. A key innovation of our study is automated evaluation by way of a RAG assessment system (RAGAS). RAGAS combines human expert assessment with AI-driven evaluation to measure the effectiveness of RAG systems. When evaluating the responses to their questions, human respondents give a "thumbs-up" 76% of the time. Meanwhile, RAGAS scores 90% on answer relevance on questions posed by experts. And when GPT-generates questions, RAGAS scores 74% on answer relevance. With RAGAS we created a benchmark that can be used to continuously assess the performance of our knowledge base. Full GNQA functionality is embedded in the free GeneNetwork.org web service, an open-source system containing over 25 years of experimental data on model organisms and human. The code developed for this study is published under a free and open-source software license at https://git.genenetwork.org/gn-ai/tree/README.md.

scientific communication and education↗

Excitable Rho dynamics drive cell contractions by sequentially inducing ERM protein-mediated actin-membrane attachment and actomyosin contractility

Migration of endothelial and many other cells requires spatiotemporal regulation of protrusive and contractile cytoskeletal rearrangements that drive local cell shape changes. Unexpectedly, the small GTPase Rho, a crucial regulator of cell movement, has been reported to be active in both local cell protrusions and retractions, raising the question of how Rho activity can coordinate cell migration. Here we show that Rho activity is absent in local protrusions and active during retractions. During retractions, Rho rapidly activated ezrin-radixin-moesin proteins (ERMs) to increase actin-membrane attachment, and, with a delay, non-muscle myosin II (NMII). Rho activity was excitable, with NMII acting as a slow negative feedback regulator. Strikingly, inhibition of SLK/LOK kinases, through which Rho activates ERMs, caused elongated cell morphologies, impaired Rhoinduced cell contractions, and reverted Rho-induced blebbing. Together, our study demonstrates that Rho activity drives retractions by sequentially enhancing ERM-mediated actin-membrane attachment for force transmission and NMII-dependent contractility.

cell biology↗

A Fluorogenic-Based Assay to Measure Chaperone-Mediated Autophagic Activity in Cells and Tissues

ObjectivePathologies including cardiovascular diseases, cancer, and neurological disorders are caused by the accumulation of misfolded / damaged proteins. Intracellular protein degradation mechanisms play a critical role in the clearance of these disease-causing proteins. Chaperone mediated autophagy (CMA) is a protein degradation pathway that employs chaperones to bind proteins, bearing a unique KFERQ-like motif, for delivery to a CMA-specific Lysosome Associated Membrane Protein 2a (LAMP2a) receptor for lysosomal degradation. To date, steady-state CMA function has been assessed by measuring LAMP2A protein expression. However, this does not provide information regarding CMA degradation activity. To fill this dearth of tools / assays to measure CMA activity, we generated a CMA-specific fluorogenic substrate assay. MethodsA KFERQ-AMC [Lys-Phe-Asp-Arg-Gln-AMC(7-amino-4-methylcou-marin)] fluorogenic CMA substrate was synthesized from Solid-Phase Peptide Synthesis. KFERQ-AMC, when cleaved via lysosomal hydrolysis, causes AMC to release and fluoresce (Excitation:355 nm, Emission:460 nm). Using an inhibitor of lysosomal proteases, i.e., E64D [L-trans-Epoxy-succinyl-leucylamido(4-guanidino)butane)], responsible for cleaving CMA substrates, the actual CMA activity was determined. Essentially, CMA activity = (substrate)fluorescence - (substrate+E64D) fluorescence. To confirm specificity of the KFERQ sequence for CMA, negative control peptides were used. ResultsHeart, liver, and kidney lysates containing intact lysosomes were obtained from 4-month-old adult male mice. First, lysates incubated with KFERQ-AMC displayed a time dependent (0-5 hour) increase in AMC fluorescence vs. lysates incubated with negative control peptides. These data validate the specificity of KFERQ for CMA. Of note, liver exhibited the highest CMA (6-fold; p<0.05) > kidney (2.4-fold) > heart (0.4-fold) at 5-hours. Second, E64D prevented KFERQ-AMC degradation, substantiating that KFERQ-AMC is degraded via lysosomes. Third, cleavage of KFERQ-AMC and resulting AMC fluorescence was inhibited in Human embryonic kidney (HEK) cells and H9c2 cardiac cells transfected with Lamp2a vs. control siRNA. Further, enhancing CMA using Lamp2a adenovirus upregulated KFERQ degradation. These data suggest that LAMP2A is required for KFERQ degradation. Conclusion. We have generated a novel assay for measuring CMA activity in cells and tissues in a variety of experimental contexts. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/571785v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@7d43d8org.highwire.dtl.DTLVardef@1f11b2eorg.highwire.dtl.DTLVardef@2fa165org.highwire.dtl.DTLVardef@10d276d_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO Proposed mechanism of KFERQ-AMC degradation via CMA C_FIG

biochemistry↗

Simple Models For Neuroscience Research Discoveries: How Often Are These Models Used In Africa

Simple animal model systems such as Drosophila, Zebrafish, and C. Elegans have enabled numerous breakthroughs in understanding human health and disease. Their conserved biological processes, ever-expanding established procedures for handling, and amenability for molecular and genetic manipulation, in addition to the minimal ethical concerns, have made these models preferred choices in several life science disciplines globally. Owing to their cheap maintenance cost, adopting these model systems will help bridge the research gap between Africa and the Global North and contribute to advancing scientific knowledge in African universities through practical sessions. However, the extent to which these models are used across Africa is unknown. Here, we analysed the use of Drosophila, Zebrafish, and C. elegans model systems in scientific publications from African laboratories from the year 2000 to 2021. Of 1851 PubMed-indexed publications in which at least one simple animal model was mentioned, 168 used at least one of these models for the actual investigation. With an average of 21 articles per country, South Africa, Nigeria, Kenya, Egypt, Morocco, and Tunisia contributed 75% of these studies. The remaining 25% were contributed by seven other countries at 2-7 articles per country. From here, we extracted and analysed information on funding and international collaboration. This revealed that 24.4 % of the studies were exclusively funded locally, 28.57 % exclusively funded internationally, 15.5% received both local and international funding, and the rest (31.5%) were unfunded, revealing that there is satisfactory access to funds for simple animal model studies, especially from external funders. By analysing the pattern of collaborations, we show that most of these studies had international collaborations, while very few collaborated within Africa. Our work provides data on the current state of research using simple model systems in African laboratories and argues that incorporating these models will advance biomedical science research in Africa.

neuroscience↗

Chlorpyrifos degradation by combined solar photo-Fenton and bacterial metabolism and simultaneous toxicity analysis in zebrafish (Danio rerio)

Chlorpyrifos (CP) is a widely used insecticide that has been used extensively, contributing towards a negative impact on public health concerns and associated ecosystems. Bioremediation is one of the key biological methods used for reducing these environmental toxicants. The present study examined the effectiveness of a combined process including solar photo-Fenton process followed by bacterial degradation using Ochrobactrum sp. CPD-03 for effective CP degradation in wastewater. Results showed that solar photo-Fenton treatment had CP degradation efficiency of ~42% in 4 h with a final degradation efficiency of ~92% in 96 h upon combined bacterial degradation. Simultaneous survivability of zebrafish (Danio rerio) was also studied during CP degradation. Compared to control, adult zebrafishes showed increased survivability following the addition of CPD-03 in water resulting a reduced CP concentration. CP toxicity in wastewater had caused acetylcholinesterase inhibition in zebrafish; however, this inhibition is due to absence of CP degrading bacteria. Therefore, a combined approach would influence for regulating CP degradation in wastewater along with simultaneous survival of Danio rerio.

microbiology↗