Events

4:00-5:00pm Chen 130
5:00-5:30pm Socializing (snacks and drinks will be provided)

"In a Pinch: Efficient guayule stembark removal for latex extraction"

Guayule (Parthenium argentatum) is a promising domestic source of natural rubber, but scalable latex and resin recovery requires efficient stem preprocessing. Current laboratory methods rely on labor intensive manual peeling. This work investigates rolling as a scalable strategy for stembark removal and identifies the geometric and mechanical conditions governing successful separation. Stems were passed through controlled roller gaps and classified from no removal to successful stembark separation and core crushing. Operating maps relating stem geometry to roller gap were constructed to predict debarking behavior. Complementary transverse compression experiments identified the mechanical response associated with bark opening and core crushing.

"Embryonic preparation for long-term symbiosis"

The long-term symbiosis between the host Euprymna scolopes and its bacterial symbiont Vibrio fischeri provides a model for host-microbe interactions. Although much is known about the establishment of this symbiosis after hatching, less is known about the host factors involved in preparing and maintaining the light organ for its future symbiont. Galaxin is an antimicrobial protein associated with the light organ and is one of several host factors that may be involved in this process. Using transcriptomic analysis and confocal microscopy, we examined galaxin expression and localization during embryonic development and early symbiosis to understand what role it may play.

"Impact of symbiosis on host and microbe protein synthesis through Bioorthogonal Noncanonical Amino Acid Tagging (BONCAT)"

The squid-vibrio system is a model system used to study symbiosis due to the binary symbiotic relationship between the host Euprymna scolopes and its bacterial symbiont Vibrio fischeri. Studying the onset of symbiosis typically employs methods such as RNAseq or bulk proteomics however the results of these methods can be misrepresentative of the interactions between host and symbiont. By applying bioorthogonal noncanonical amino acid tagging (BONCAT) to the squid-vibrio system, newly synthesized proteins were localized and identified from both host and symbiont offering a deeper insight into host-microbe interactions during the establishment of symbiosis.

Nicolina Ranieri and Brandon Jatico
McFall-Ngai and Ruby Labs

Special ChE Seminar

Nir Livne (Hebrew University)
Faculty host: Sujit Datta

"Chemotaxis drives rapid bacterial community formation"

Abstract: It is often beneficial for bacteria to live in communities, but how do these communities form? I will show that chemotaxis—the directed movement of motile bacteria along chemical gradients—enables rapid community formation. By locally modifying their chemical environment, cells generate gradients that they themselves chemotactically follow, effectively attracting one another; this self-attraction drives the spontaneous condensation of a population into macroscopic focal points composed of hundreds of thousands of individuals. In swimming E. coli, such condensates can form far faster than the timescale of cell multiplication, allowing populations to collectively mitigate stress and seed biofilm-like aggregates. Yet swimming proves to be a double-edged sword: as cells accumulate, their density becomes high enough to trigger correlated swimming and active turbulence. This collective motion generates macroscopic fluid flows with an outward component directed down the cell-density gradient, broadening the condensate and fundamentally limiting further accumulation. In porous environments, however, these flows are suppressed, allowing cells to self-organize into extremely dense communities. Preliminary results suggest that under growth conditions these communities further develop into stable, macroscopic structures and may improve the cells' antibiotic tolerance.

Biography: Nir Livne is a Milner Fellow and physics PhD candidate at the Hebrew University, studying bacterial chemotaxis in Prof. Ady Vaknin's lab. He completed his B.Sc. in physics through Amirim (the Faculty of Science's excellence program) and his M.Sc. in physics at the Hebrew University, and is a recipient of the Racah Prize for Excellence in Teaching.