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BUPA opens applications for Invited Postdoc Research Colloquium

August 8, 2022 By

IPRC 2022 Speaker

The Brandeis University Postdoctoral Association (BUPA) is organizing its yearly Invited Postdoc Research Colloquium (IPRC) for the academic year 2022-2023. BUPA is inviting two senior neuroscience postdocs to Brandeis to present their research and visit the Brandeis community. Selected speakers will give an hour-long seminar, meet with faculty one-on-one, and engage in informal discussion with Brandeis postdocs over lunch and dinner. This provides a great opportunity for the speakers to receive scientific feedback and increase their visibility in the scientific community, two essential aspects for their future job search. Also, of course, this is an equally great opportunity for the Brandeis community to engage in fruitful scientific discussion and learn about exciting research performed outside of the Brandeis campus.

Interested postdocs should send an updated CV as well as an abstract of their research (maximum 250 words) to BUPA (bupa@brandeis.edu). Seminars will be organized in person and funds for travel, accommodation and food will be provided for the speakers. Virtual presentations will be organized should the need arise. Women and underrepresented minorities are strongly encouraged to apply. The application deadline is August 31, 2022.

For additional information, please contact BUPA at bupa@brandeis.edu.

Filed Under: division of science, division of science, division of science, General, labs, Neuroscience, postdocs Tagged With: , ,

Ordabayev et al. developed an open-source analysis software for colocalization single-molecule fluorescence experiments

April 21, 2022 By

Tapqir analysis

Yerdos Ordabayev et al. in the Department of Biochemistry use Bayesian probabilistic programming to implement computer software “Tapqir” for analysis of colocalization single-molecule spectroscopy (CoSMoS) image data. CoSMoS is a tool widely used in vitro to study the biochemical and physical mechanisms of the protein and nucleic acid macromolecular “machines” that perform essential biological functions. In this method, formation and/or dissociation of molecular complexes is observed by single-molecule fluorescence microscopy as the colocalization of binder and target macromolecules each labeled with a different color of fluorescent dye. Despite the use of the method for over twenty years, reliable analysis of CoSMoS data remains a significant challenge to the effective and more widespread use of the technique.

This work describes a holistic causal probabilistic model of CoSMoS image data formation. This model is physics-based and includes realistic shot noise in fluorescent spots, camera noise, the size and shape of spots, and the presence of both specific and nonspecific binder molecules in the images. Most importantly, instead of yielding a binary spot-/no-spot determination, the algorithm calculates the probability of a colocalization event. Unlike alternative approaches, Tapqir does not require subjective threshold settings of parameters so they can be used effectively and accurately by non-expert analysts. The program is implemented in the state-of-the-art Python-based probabilistic programming language Pyro (open-sourced by Uber AI Labs in 2017), which enables efficient use of graphics processing unit (GPU)-based hardware for rapid parallel processing of data and facilitates future modifications to the model. Tapqir is free, open-source software. We envision that Tapqir program is likely to be adopted by researchers who use single-molecule colocalization methods to study a wide range of different biological systems.

Reference:
Yerdos A Ordabayev, Larry J Friedman, Jeff Gelles, Douglas L Theobald. Bayesian machine learning analysis of single-molecule fluorescence colocalization images. eLife 2022;11:e73860.
Publication Date: March 23, 2022.
Filed Under: Biochemistry, division of science, General, labs, postdocs Tagged With: , , ,

Turrigiano lab uncovers sources of neuronal heterogeneity

December 18, 2020 By

High activity neurons have greater instrinsic excitability and response to local inputs, but no difference in total input type or amount

Mammalian cortex has long been one of the most widely studied systems in neuroscience, dating back to the pioneering work of Santiago Ramon y Cajal in the late 19th century. The cortex is much larger in primates than other mammals, and is thought to be responsible for the advanced cognitive abilities of humans. Today, models of cortical connections and computations form the basis for some of the most powerful deep learning paradigms. However, despite this success, there is still much that is unknown about how cortex functions. One feature of cortex that has recently been discovered is that neurons that appear to be similar to each other can have very different baseline activity levels: some neurons are 100x more active than their neighbors. We don’t know how neurons that are otherwise highly similar in shape and genetic makeup can maintain such different activity levels, or if the neurons with high and low activity levels have different functions in the brain. These neurons are otherwise so similar to each other that it is difficult to tell them apart without recording their activity directly, and current techniques for recording the activity of many neurons simultaneously in live animals do not allow us to later re-identify them for further study.

In a paper recently published in Neuron, the Turrigiano lab, led by postdoctoral researcher Nick Trojanowski, reported a new approach for permanently labeling high and low activity neurons in live animals, and then determining what makes them different. To do this they used a fluorescent protein called CaMPARI2 that changes from green to red as activity increases, but only when exposed to UV light. By shining UV light into the brain, they caused neurons with high activity to turn red, while neurons with low activity remained green. This procedure allowed them to run a series of tests on high and low activity neurons to identify differences between them. They found that high activity neurons would intrinsically generate more activity than low activity neurons when presented with the same stimulus. These high activity neurons also receive more excitatory input specifically from nearby neurons of the same type. Surprisingly, however, they found that the total amount of excitatory and inhibitory input that high and low activity neurons received from other neurons was not a major factor in determining their activity levels. Together, these results tell us that the differences in activity between neurons are due to intrinsic differences, as well as their pattern of connectivity to their nearby partners. This has deep implications for how the networks that underlie cortical computations are built and maintained.

With these tools in hand, it is now possible to further explore the differences between high and low activity neurons. Do these neurons serve different functions? Are the baseline activity levels specified from birth? How do these activity levels affect the mechanisms of plasticity that are responsible for learning and memory? The recently published results represent just the tip of the iceberg of information that can be learned with this new technique, in the mammalian cortex as well as other brain regions.

Filed Under: labs, Neuroscience Tagged With: , , , ,

First Rosbash-Abovich Award Recipients Announced

December 15, 2020 By

Michael Rosbash, the Peter Gruber Endowed Chair in Neuroscience and Professor of Biology and his wife, Nadja Abovich, established the Rosbash-Abovich Award as a way to inspire and acknowledge excellence in research by post-doctoral fellows and graduate students in the Brandeis life sciences. The Rosbash-Abovich award will be awarded annually.

The award honors the most outstanding papers published the previous year that have been authored by a Brandeis postdoctoral fellow and a Brandeis PhD student. In addition to the honor being selected, each winner is presented with a monetary award.

Future winners will present their talks at upcoming Volen Scientific Retreats, but due to COVID restrictions, the 2020 winners will be presenting their talks during the Molecular Genetics Journal Club meetings.

Most outstanding paper by a post-doctoral fellow

Michael O'Donnell

Michael O’Donnell, PhD

The 2020 winner for the most outstanding post-doctoral paper is Michael O’Donnell for the publication titled “A neurotransmitter produced by gut bacteria modulates host sensory behavior“. O’Donnell, is a former postdoc in the Piali Sengupta Lab. Sengupta said

Mike is a remarkable scientist and mentor. He single-handedly and independently established a new research direction in my lab. He also served as an informal mentor to many graduate students and has continued to do so even after he left my lab. I greatly appreciated our long discussions and arguments, and he is very much missed.

Sengupta also noted that O’Donnell was chosen to receive this award

on the basis of the creativity and novelty of his work that was published in Nature. The committee was particularly interested in nominating a researcher who was a driving force behind the work and Mike certainly fulfilled this criteria.

O’Donnell is now an assistant professor at Yale and recently formed the O’Donnell lab. He presented his talk to the Molecular Genetics Journal Club on December 2, 2020. He spoke about his work on neuromodulators produced by different bacteria.

Most outstanding paper by a PhD student

James Haber & Gonen Memisoglu

Professor James Haber & Gonen Memisoglu, PhD

The recipient of the 2020 award for the most outstanding PhD student paper is Gonen Memisoglu for the publication “Mec1 ATR Autophosphorylation and Ddc2 ATRIP Phosphorylation Regulates DNA Damage Checkpoint Signaling.“ She was a PhD student in James Haber’s lab. She received her PhD in 2018 and is currently a postdoctoral fellow at the University of Chicago. She will be presenting her talk at the Molecular Genetics Journal Club on February 2, 2021.

When asked about his former PhD student, Haber said

I was delighted to learn that Gonen was the recipient of the Rosbash/Abovich award for the best publication by a graduate student last year; but I had to ask “which paper” because Gonen made two important discoveries last year about the way cells respond to DNA damage. Gonen helped develop a highly efficient way to edit the yeast genome and to create dozens of very precise mutations in the Mec1 gene that is the master regulator of the DNA damage response.  When there is a chromosome break, the Mec1 protein phosphorylates a number of proteins that creates a cascade of signaling to prevent cells from progressing through mitosis until damage is repaired. Gonen discovered that the extinction of the this signal depended on Mec1’s autophosphorylation of one specific target and that changing that specific amino acid to one that could not be phosphorylated was enough to cause cells to remain arrested. She also identified several alterations of the Ddc2 protein that associates with Mec1 that were also critical for its normal activation.

During her time in my lab Gonen was a super hard-working and exceptionally insightful grad student, but also incredibly generous with her time, helping others in the lab

Filed Under: awards, Biology, grad students, labs, postdocs Tagged With: , , , , , , , ,

Alum, Past Postdoc Receive Awards from Breakthrough Prize Foundation

September 25, 2020 By
Netta Engelhardt

Netta Engelhardt. photo: MIT

Lisa Piccirillo

Lisa Piccirillo. photo: Quanta Magazine.

Lisa Piccirillo, a recent Brandeis postdoc and Netta Engelhardt, a Brandeis undergraduate alumni have received two awards from the Breakthrough Prize Foundation. While the Breakthrough Prizes are intended to help scientific leaders gain financial freedom, the New Horizons award and the Maryam Mirzakhani New Frontiers Prize focus on young scientists early in their careers.

The Maryam Mirzakhani New Frontiers Prize is awarded to early-career women mathematicians. Lisa Piccirillo received this prize for her work in resolving the Conway Knot problem. Piccirillo was a postdoc working with Daniel Ruberman, Professor of Mathematics, from 2019 until her recent appointment as Assistant Professor at Massachusetts Institute of Technology.

Netta Engelhardt, is part of a group that received the 2021 New Horizons in Physics Prize. Netta and three other scientists were awarded for their research in calculating the quantum information content of a black hole and its radiation. Engelhardt is currently an Assistant Professor of Physics at Massachusetts Institute of Technology. She was a 2011 graduate who majored in Physics. She received a NSF Graduate Research Fellowship prior to graduating from Brandeis.

 

Filed Under: awards, labs, Mathematics, Physics Tagged With: , , , ,

Pump without pumps

April 14, 2017 By

By Kun-Ta Wu, Ph.D.

Pumping water through a pipe solves the need to provide water in every house. By turning on faucets, we retrieve water at home without needing to carry it from a reservoir with buckets. However, driving water through a pipe requires external pressure; such pressure increases linearly with pipe length. Longer pipes need to be more rigid for sustaining proportionally-increased pressure, preventing pipes from exploding. Hence, transporting fluids through pipes has been a challenging problem for physics as well as engineering communities.

To overcome such a problem, Postdoctoral Associate Kun-Ta Wu and colleagues from the Dogic and Fraden labs, and Brandeis MRSEC doped water with 0.1% v/v active matter. The active matter mainly consisted of kinesin-driven microtubules. These microtubules were extracted from cow brain tissues. In cells, microtubules play an important role in cell activity, such as cell division and nutrient transport. The activity originates from kinesin molecular motors walking along microtubules. In cargo transport, microtubules are like rail tracks; kinesin motors are like trains. When these tracks and trains are doped in water, their motion drives surrounding fluids, generating vortices. The vortices only circulate locally; there is no global net flow.

Wu-Pump without Pumps

Figure: Increasing the height of the annulus induces a transition from locally turbulent to globally coherent flows of a confined active isotropic fluid. The left and right half-plane of each annulus illustrate the instantaneous and time-averaged flow and vorticity map of the self-organized flows. The transition to coherent flows is an intrinsically 3D phenomenon that is controlled by the aspect ratio of the channel cross section and vanishes for channels that are either too shallow or too thin. Adapted from Wu et al. Science 355, eaal1979 (2017).

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Filed Under: labs, Physics Tagged With: , , , ,

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