🎉 Congratulations to Needhi Bhalla, UC Santa Cruz (www.bhallalab.com
), named a 2025 #ASCB Fellow! This honor celebrates her outstanding contributions to cell biology, leadership, & service. Fellows will be recognized at #CellBio2025 in Philadelphia this December. #CellBiology
Only a few days left to register to attend virtually the @embl.org symposium on the "Wild Frontier of Model Systems". Don't miss this opportunity if you are interested in exploring unconventional model organisms for a better understanding of biology, ecology and evolution
News! @theroglab.bsky.social Gordon et al. discovers synaptonemal complex wets & aligns chromosomes, a crucial step in sexual reproduction, where errors in chromosome# can be fatal to the embryo. @utah.edu
Read in Science Advances
www.science.org/doi/full/10....
I hope that everyone in the private sector who depends on federal grants to train their researchers and staff, pay for their services and products, or benefits in any other way from federal funding will come out to #standupforscience!
Ofer Rog @theroglab.bsky.social from @utah.edu will talk about "Regulating sister interactions during meiosis" on May 21st
Learn more about Dr. Rog's work :
theroglab.org
--> Register here: meiosis.cornell.edu/mayosis2025/...
Much more inside. As usual, hit us up if you have any feedback!
Finally, we used our kinetic information to derive the total number of DSBs. We found an average of 40 DSBs per nucleus in wild-type meiosis suggesting a ratio of 7:1 of DSBs to crossovers, and more DSBs in mutant scenarios.
Second, strand invasion kinetics were similar for repair events templated by the homolog versus the sister. This was surprising, since a leading hypothesis is that DSBs that don't find the homologs stall and are only repaired at the end of meiosis using the sister chromatid.
We made 3 crucial findings. First, we found that most repair events finish the strand-invasion step in 1-2 hours. This is true for both endogenous (SPO-11-induced) and irradiation-induced DSBs.
The inspiration was beautiful work by Sarit and Nicola, who used auxin-mediated degradation of SPO-11 to extinguish new meiotic DSBs. We used a cytological marker - RAD-51 - which marks strand-invasion and quantified the kinetics of their disappearance.
pubmed.ncbi.nlm.nih.gov/36170820/
New preprint from the lab! We defined the kinetics of strand invasion during meiosis in C. elegans. Great work from Antonia, Henry and Divya.
www.biorxiv.org/content/10.1...
Looking for a summer undergraduate research opportunity? Come work with us! Apply to SPUR at the University of Utah - it including a stipend and funds for travel and housing:
our.utah.edu/research-sch...
our.utah.edu/spur/underst...
Reach out if you have any questions!
We’d love to get feedback and suggestions. Kudos to Kewei, an amazing grad student who developed CheC-PLS over the last 5 years; to Chloe and Lexy (now with her own lab, new-car-smell and all, at UMinnesota); and to Lisa and a super-talented undergrad, Kaan.
So Skp1 has been moonlighting for >100 million years. Which adds a new twist to the SC paradox: how does a highly conserved protein (Skp1) maintains intimate interaction with quickly diverging proteins in a way that does not leave a clear evolutionary mark in their sequence?
In both nematode, Skp1 is not only necessary for assembly of the SC onto chromosomes - without dimerization-competent Skp1, SC proteins are absent.
Lisa turned to the distantly related nematode P. pacificus, and found that the answer is a resounding ‘yes’. Ppa-SKR-1 localize to the middle of the SC, and a conserved dimerization interface in Skp1 is specifically required for SC assembly in Pristi, as it is in elegans.
Recently, Yumi Kim's lab made an intriguing discovery: Skp1, a conserved subunit of the SCF ubiquitin ligase complex (SKR-1 in C. elegans), moonlights as a structural component of the SC. Lisa decided to test whether this function is conserved. 10.1126/sciadv.adl4876
On the other hand, the protein sequence is incredibly divergent between and within clades, so much so that the genes had to be independently cloned in different model organisms. (More on that in Lisa’s previous paper.) elifesciences.org/articles/30823
#3: Skp1 in the SC. SC proteins have intriguing evolutionary history: they build a highly conserved structure AND (almost) all subunits are co-dependent for assembly.
That has crucial implications: ZHP-3 can sample the entire 6um chromosome in tens of minutes, whereas SYP-3 cannot. By extension, ZHP-3 is capable of efficiently transducing a crossover signal, whereas SYP-3 would be unlikely to.
The second important finding came from comparing the diffusion of an SC component (SYP-3) vs a regulator of crossovers (ZHP-3). ZHP-3 diffuses 4-9 times faster than SYP-3 (depending on meiotic stage).
(Black-boxing some amazing tech here; check out the preprint for details.) This finding confirmed a crucial aspect of the coarsening hypothesis.
However, a crucial piece of this model has not been tested: do molecules diffuse within the SC? Lexy directly tested that. By sparsely labeling SC components and crossover regulators, she was able to observe single molecules in live gonads.
This idea, and beautiful data from worms and plants (from Raphael Mercier, Chris Morgan and others) suggested coarsening regulates genetic exchanges (crossovers).
#2: Diffusion within the synaptonemal complex (SC). A few years ago @adernburg.bsky.social and I showed the SC has liquid properties. doi.org/10.7554/eLif...
And perhaps not less important - potential for many future experiments. Should be noted: nothing in the design confines CheC-PLS to budding yeast, so it should be adaptable to other model organisms.
Our data revealed sliding of cohesin on DNA (presumably loop extrusion); positioning of nucleosomes; and, AFAIK, the first binding patterns of cohesins in the rDNA locus. Much more data inside.
We also performed a CheC-PLS on isolated nuclei, using Rec8-GFP and nanobodies targeted to GFP and tethered to a methyltransferase. (This variation is related to recently published techniques like DiMeLo-seq and SAMOSA). cc @astraight.bsky.social
We developed CheC-PLS on meiotic chromosomes in budding yeast. We tagged the cohesin subunit Rec8 and recapitulated ChIP & HiC data.
