Biology subjects

Weissbourd, B.

Publications and source records attributed to Weissbourd, B..

6 recordsLinked to original sources

bioRxiv2025

Superresolution imaging of live samples by centroid reassignment microscopy

Superresolution imaging has become one of the most important recent advances in microscopy development. However, most superresolution methods are ill-adapted for live-sample imaging because they are unacceptably slow, susceptible to artifacts, or require the use of specialized fluorophores and labeling protocols. We introduce a superresolution method called centroid reassignment microscopy (CRM) that overcomes these limitations. CRM is a simple variation on confocal microscopy wherein the single-element detector and small pinhole are replaced by a centroid detector and larger pinhole. Superresolution is obtained by reassigning the detected fluorescence to its centroid location of as a function of the scanning excitation focus location. Our method bears resemblance to the method of image scanning microscopy, which involves the use of an array detector, with the advantage that CRM provides improved resolution for the same number of detected photons while being simpler to implement and less sensitive to noise. CRM is light-efficient, fast (single-frame), robust to defocus aberrations, and requires no changes whatsoever in standard fluorescence imaging protocols, making it uniquely attractive for superresolution imaging of live, dynamic samples.

bioengineering↗

bioRxiv2025

Comparison of Activities of Transcription Factor NF-κB from Two Jellyfish Models

Herein, transcription factor Nuclear Factor-kappaB (NF-{kappa}B) is characterized as the downstream effector of putative innate immune signaling pathways from two model jellyfish, Aurelia aurita (Aa) and Clytia hemisphaerica (Ch). Both jellyfish NF-{kappa}B proteins consist primarily of the N-terminal DNA-binding/dimerization domain, and they lack the C-terminal ankyrin repeat inhibitory domain found in vertebrate NF-{kappa}B proteins. Both jellyfish NF-{kappa}B proteins bind to a consensus mammalian NF-{kappa}B binding site, and their AlphaFold3-predicted structures on DNA are similar to that of mouse NF-{kappa}B p50. Neither Aa- nor Ch-NF-{kappa}B activated transcription of an NF-{kappa}B-site reporter gene in human cells; however, Aa-NF-{kappa}B did activate transcription from a GAL4-site reporter gene in yeast, whereas Ch-NF-{kappa}B did not. Aa- and Ch-NF-{kappa}B were both constitutively located in the nucleus when expressed in vertebrate cells. Homologs of I{kappa}B-like proteins from both species interacted with their corresponding NF-{kappa}B proteins in co-immunoprecipitation assays in HEK 293T cells. These I{kappa}B-like proteins influenced the subcellular localization of their cognate NF-{kappa}B proteins in vertebrate cells, and their ankyrin repeat domains were predicted to interact with Ch-NF-{kappa}B in a manner similar to mammalian I{kappa}B and NF-{kappa}B. RNA-sequencing data from Ch animals indicate that Ch-NF-{kappa}B is expressed at high levels in early developmental stages, when Ch-I{kappa}B expression is low, suggesting that active Ch-NF-{kappa}B controls an early developmental process. In contrast, in adult animals the expression of Ch-I{kappa}B is high, suggesting that Ch-NF-{kappa}B requires a signal in order to become active. Overall, these results provide comparative information on the structure, activity, and mRNA expression of jellyfish NF-{kappa}B pathway proteins among jellyfish, and they suggest roles for NF-{kappa}B in developing and adult jellyfish.

molecular biology↗

bioRxiv2021

Functional modules within a distributed neural network control feeding in a model medusa

Jellyfish are free-swimming, radially symmetric organisms with complex behaviors that arise from coordinated interactions between distinct, autonomously functioning body parts. This behavioral complexity evolved without a corresponding cephalization of the nervous system. The systems-level neural mechanisms through which such decentralized control is achieved remain unclear. Here, we address this question using the jellyfish, Clytia, and present it as a new neuroscience model. We describe a coordinated, asymmetric behavior in which food is passed from the umbrellar margin to the central mouth via directed margin folding. Using newly developed transgenic jellyfish lines to ablate or image specific neuronal subpopulations, we find, unexpectedly, that margin folding reflects the local activation of neural subnetworks that tile the umbrella. Modeling suggests that this structured ensemble activity emerges from sparse, local connectivity rules. These findings reveal how an organismal behavior can emerge from local interactions between functional modules in the absence of a central brain.

neuroscience↗

bioRxiv2021

Whole Animal Multiplexed Single-Cell RNA-Seq Reveals Plasticity of Clytia Medusa Cell Types

We present an organism-wide, transcriptomic cell atlas of the hydrozoan medusa Clytia hemisphaerica, and determine how its component cell types respond to starvation. Utilizing multiplexed scRNA-seq, in which individual animals were indexed and pooled from control and perturbation conditions into a single sequencing run, we avoid artifacts from batch effects and are able to discern shifts in cell state in response to organismal perturbations. This work serves as a foundation for future studies of development, function, and plasticity in a genetically tractable jellyfish species. Moreover, we introduce a powerful workflow for high-resolution, whole animal, multiplexed single-cell genomics (WHAM-seq) that is readily adaptable to other traditional or non-traditional model organisms.

systems biology↗

bioRxiv2018

Connectional architecture of a mouse hypothalamic circuit node controlling social behavior

Type 1 Estrogen receptor-expressing neurons in the ventrolateral subdivision of the ventromedial hypothalamus (VMHvlEsr1) play a causal role in the control of social behaviors including aggression. Here we use six different viral-genetic tracing methods to map the connectional architecture of VMHvlEsr1 neurons. These data reveal a high level of input convergence and output divergence (\"fan-in/fan-out\") from and to over 30 distinct brain regions, with a high degree (~90%) of recurrence. Unlike GABAergic populations in other hypothalamic nuclei controlling feeding and parenting behavior, VMHvlEsr1 glutamatergic neurons collateralize to multiple targets. However, we identify two anatomically distinct subpopulations with anterior vs. posterior biases in their collateralization patterns. Surprisingly, these two subpopulations receive indistinguishable inputs. These studies suggest an overall system architecture in which an anatomically feed-forward sensory-to-motor processing stream is integrated with a dense, highly recurrent central processing circuit. This architecture differs from the \"brain-inspired\" feed-forward circuits used in certain types of artificial intelligence networks.\n\nSIGNIFICANCEHow the cellular heterogeneity of brain nuclei maps onto circuit connectivity, the relationship of this anatomical mapping to behavioral function, and whether there are general principles underlying this relationship, remains poorly understood. Here we systematically map the connectivity of estrogen receptor-1-expressing neurons in the ventromedial hypothalamus (VMHvlEsr1), which control aggression and other social behaviors. We find that a relatively sparse, anatomically feed-forward sensory-to-motor processing stream is integrated with a dense, highly recurrent central processing circuit. Further, the VMHvl contains at least two subpopulations of Esr1+ neurons with different cell body characteristics and locations, with distinct patterns of collateralization to downstream targets. Nevertheless, these projection-defined subpopulations receive similar inputs. This input-output organization appears distinct from those described in other hypothalamic nuclei.

neuroscience↗

bioRxiv2018

Anatomical, Physiological, and Functional Heterogeneity of the Dorsal Raphe Serotonin System

The dorsal raphe (DR) constitutes a major serotonergic input to the forebrain, and modulates diverse functions and brain states including mood, anxiety, and sensory and motor functions. Most functional studies to date have treated DR serotonin neurons as a single, homogeneous population. Using viral-genetic methods, we found that subcortical-vs. cortical-projecting serotonin neurons have distinct cell body distributions within the DR and different degrees of coexpressing a vesicular glutamate transporter. Further, the amygdala-and frontal cortex-projecting DR serotonin neurons have largely complementary whole-brain collateralization patterns, receive biased inputs from presynaptic partners, and exhibit opposite responses to aversive stimuli. Gain-and loss-of-function experiments suggest that amygdala-projecting DR serotonin neurons promote anxiety-like behavior, whereas frontal cortex-projecting neurons promote active coping in face of challenge. These results provide compelling evidence that the DR serotonin system contains parallel sub-systems that differ in input and output connectivity, physiological response properties, and behavioral functions.

neuroscience↗