Biology subjects

Adhikary, B.

Publications and source records attributed to Adhikary, B..

3 recordsLinked to original sources

bioRxiv2025

PAK4 promotes vertex remodeling to maintain epithelial integrity and barrier function

Cell-cell junctions are essential for epithelial integrity and barrier function, but the mechanisms regulating their remodeling remain unclear. Here, we investigated the role of the junctional kinase PAK4 in vertex remodeling. PAK4 localized to apical junctions and accumulated at multicellular vertices in MCDK cells and Xenopus embryos. Inhibition or knockout of PAK4 increased higher-order vertices, caused junctional discontinuities, and impaired barrier function in MDCK cells. PAK4 recruitment required the scaffolding protein Afadin. Afdn-KO cells exhibited severe junctional defects and reduced barrier function. Artificial targeting of PAK4 in Afdn-KO cells partially restored junctional continuity and barrier function. In Xenopus embryos, live imaging showed dynamic PAK4 accumulation at remodeling vertices, and PAK4 inhibition hindered resolution of multicellular vertices. Expression of an amino-terminal fragment (PAK4-NT) impaired remodeling and induced cytokinetic failure. Live imaging in Xenopus revealed barrier leakage at multicellular vertices upon PAK4 inhibition. These findings indicate that PAK4 and Afadin cooperate to maintain epithelial integrity and barrier function by promoting vertex remodeling. SummaryAdhikary et al. show that PAK4, recruited to epithelial junctions by Afadin, drives dynamic vertex remodeling in cells and embryos. Inhibiting PAK4 disrupts tissue packing and compromises junctional continuity and barrier function, implicating PAK4 and Afadin as critical partners in vertex remodeling to preserve tissue integrity.

cell biology↗

bioRxiv2024

Enhanced Yield and Gentle Purification of HIV for Cryo-Electron Tomography Analysis of Virion Maturation.

HIV is a lentivirus characterized by the formation of its mature core. Visualization and structural examination of HIV requires purification of virions to high concentrations. The yield and integrity of these virions are crucial for ensuring a uniform representation of all viral particles in subsequent analyses. In this study, we present a method for purification of HIV virions which minimizes forces applied to virions while maximizing the efficiency of collection. This method allows us to capture between 1,000 and 5,000 HIV virions released from individual HEK293 cells after transfection with the NL4.3 HIV backbone, a 10 fold advantage over other methods. We utilized this approach to investigate HIV core formation from several constructs: pNL4-3(RT:D185A&D186A) with an inactive reverse transcriptase, NL4.3(IN: V165A&R166A) with a type-II integrase mutation, and NL4.3(: {Delta}(105-278)&{Delta}(301-332)) featuring an edited packaging signal. Notably, virions from NL4.3(: {Delta}(105-278)&{Delta}(301-332)) displayed a mixed population, comprising immature virions, empty cores, and cores with detectable internal density. Conversely, virions derived from NL4.3(IN: V165A&R166A) exhibited a type II integrase mutant phenotype characterized by empty cores and RNP density localized around the cores, consistent with previous studies. In contrast, virions released from pNL4-3(RT:D185A&D186A) displayed mature cores containing detectable RNP density. We suggest that the purification methods developed in this study can significantly facilitate the characterization of enveloped viruses.

microbiology↗

bioRxiv2022

Human-sloth bear conflict in Nepal - case study from an unprotected Churia forest

Human-sloth bear conflict, generally in the form of human attacks, is common throughout most areas where sloth bears co-occur with humans. The situation is more prevalent in multi-use forest landscapes outside protected areas. Although sloth bears are a conflict-prone species in Nepal, there is a clear lack of systematic studies that can inform human safety and conflict mitigation. We used data from questionnaire-based interviews with conflict-affected people and witnesses to provide detailed information about human-sloth bear conflict (1990- 2021) in the Trijuga forest, an important sloth bear stronghold outside protected areas in Nepal. The data were analyzed using descriptive statistics, chi-square tests, and regression analysis. For the time period, 66 conflict incidents involving 69 human individuals were recorded, with an annual average of 2.06 (SD = 1.48) incidents and 1.75 (SD = 1.34) attacks. Conflicts primarily impacted working-age group (25-55 years old) men, whose primary occupation was farming and who frequented the forest regularly. They typically occurred between 0900 and 1500, inside forests, and in habitats associated with poor land cover visibility. Poor visibility was also a significant positive determinant of bear attacks on humans. Fifty-six conflict incidents resulted in attacks that injured 59 people, with a fatality rate of 8.47%. Victims of bear attacks frequently had serious injuries, especially to the head and neck areas of the body. Serious injuries were more likely to occur to lone individuals than to people who were in groups of two or more. We suggest identification of conflict-risk habitats through a participatory mapping approach and education programs for the local people for effective human-sloth bear conflict management in Nepals unprotected forests.

ecology↗