Biology subjects

Francis, M. L.

Publications and source records attributed to Francis, M. L..

2 recordsLinked to original sources

bioRxiv2021

Colistin resistance in Acinetobacter baumannii is driven by multiple genomic traits: Evaluating the role of ISAba1-driven eptA overexpression among Indian isolates

Colistin resistance in Acinetobacter baumannii is mediated by multiple mechanisms. Recently, mutations within pmrAB two component system and overexpression of eptA due to upstream insertion of ISAba1 play a major role.To characterize colistin resistance mechanisms among the clinical isolates of A. baumannii in India. A total of 224 clinical isolates of A. baumannii collected from 2016 to 2019 were included in this study. Mutations within lipid A biosynthesis and pmrAB genes were characterized by Whole Genome Shotgun sequencing. Twenty eight complete genomes were further characterized for insertional inactivation of lpx genes and the association of ISAba1-eptA using hybrid assembly approach. Non-sysnonymous mutations like M12I in pmrA, A138T and A444V in pmrB and E117K in lpxD were identified. Four of the five colistin resistant A.baumannii isolates had insertion of ISAba1 upstream eptA. No mcr genes were identified.Overall, the present study highlights the diversity of colistin resistance mechanisms in A. baumannii. ISAba1-driven eptA overexpression could be responsible for colistin resistance among Indian isolates of colistin resistant A. baumannii.

microbiology↗

bioRxiv2019

Varying crosslinking motifs drive the mesoscale mechanics of actin-microtubule composites

The cytoskeleton dynamically tunes its mechanical properties by altering the interactions between semiflexible actin filaments, rigid microtubules, and crosslinking proteins. Here, we use optical tweezers microrheology and confocal microscopy to characterize how varying crosslinking motifs impact the microscopic and mesoscale mechanics and mobility of actin-microtubule composites. We show that, upon subtle changes in the crosslinking pattern, composites separate into two distinct classes of force response - primarily elastic versus more viscous behavior. For example, a composite in which actin and microtubules are crosslinked to each other is markedly more elastic than one in which both filaments are crosslinked but cannot link together. Notably, this distinction only emerges at mesoscopic scales in response to nonlinear forcing, whereas varying crosslinking motifs have little impact on the microscale mechanics and steady-state mobility of composites. Our unexpected scale-dependent results not only inform the physics underlying key cytoskeleton processes and structures, but, more generally, provide valuable perspective to materials engineering endeavors focused on polymer composites.

biophysics↗