Visiting Investigators

Permanent URI for this collection

Scores of distinguished biologists from around the world come to the MBL to collaborate and conduct research. They use marine and other organisms as model systems for their research.

These researchers participate in a number of established MBL groups including but not limited to:

  • MBL Summer Research Fellows
  • Dart Scholars
  • Grass Faculty Awardees
  • NeuroImaging Cluster
  • Grass Fellows
  • Whitman Center


Recent Submissions

Now showing 1 - 20 of 288
  • Article
    A complete biomechanical model of Hydra contractile behaviors, from neural drive to muscle to movement
    (National Academy of Sciences, 2023-03-14) Wang, Hengji ; Swore, Joshua ; Sharma, Shashank ; Szymanski, John R. ; Yuste, Rafael ; Daniel, Thomas L. ; Regnier, Michael ; Bosma, Martha M. ; Fairhall, Adrienne L.
    How does neural activity drive muscles to produce behavior? The recent development of genetic lines inthat allow complete calcium imaging of both neuronal and muscle activity, as well as systematic machine learning quantification of behaviors, makes this small cnidarian an ideal model system to understand and model the complete transformation from neural firing to body movements. To achieve this, we have built a neuromechanical model of's fluid-filled hydrostatic skeleton, showing how drive by neuronal activity activates distinct patterns of muscle activity and body column biomechanics. Our model is based on experimental measurements of neuronal and muscle activity and assumes gap junctional coupling among muscle cells and calcium-dependent force generation by muscles. With these assumptions, we can robustly reproduce a basic set of's behaviors. We can further explain puzzling experimental observations, including the dual timescale kinetics observed in muscle activation and the engagement of ectodermal and endodermal muscles in different behaviors. This work delineates the spatiotemporal control space of movement and can serve as a template for future efforts to systematically decipher the transformations in the neural basis of behavior.
  • Article
    Vessel sound causes hearing loss for hummingbird bobtail squid (Euprymna berryi)
    (Frontiers Media, 2023-02-28) Putland, Rosalyn L. ; Mooney, T. Aran ; Mensinger, Allen F.
    Anthropogenic activity and its associated sounds have been shown to incur adverse effects on the behaviour and physiology of a wide range of aquatic taxa, from marine mammals to fishes. Yet, little is known about how invertebrates detect and respond to anthropogenic sound. The hummingbird bobtail squid ( Euprymna berryi ) has a short lifespan (< 6 months), grows to sexual maturity around 90 days post hatching and its small size (< 5 cm mantle length) makes the species an ideal candidate to examine potential effects of sound exposure under laboratory conditions. Hearing and behavioural observations were made before, during and after 15 minutes of vessel sound playback, and aural sensitivity curves were determined using auditory evoked potentials. A significant decrease in relative ventilation rate was observed during and post sound exposure. Auditory sensitivity before and after vessel sound exposure was also examined for three different ages: juveniles, mid- and late adults. Baseline audiograms indicated that there was a decrease in aural sensitivity with age. All three age groups showed similar, significantly decreased hearing sensitivity following sound exposure, however auditory sensitivity recovered within two hours. Globally, anthropogenic sounds have become louder and more persistent, therefore there may be limited time for these animals to recover from sound exposure. Given their ecological and economic importance, cephalopods should be considered in management and policy on underwater noise owing to potential adverse effects of anthropogenic sound on behaviour and physiology.
  • Article
    A gene duplication of a septin reveals a developmentally regulated filament length control mechanism
    (Rockefeller University Press, 2023-02-14) Cannon, Kevin S ; Vargas-Muniz, Jose M. ; Billington, Neil ; Seim, Ian ; Ekena, Joanne ; Sellers, James R. ; Gladfelter, Amy S.
    Septins are a family of conserved filament-forming proteins that function in multiple cellular processes. The number of septin genes within an organism varies, and higher eukaryotes express many septin isoforms due to alternative splicing. It is unclear if different combinations of septin proteins in complex alter the polymers' biophysical properties. We report that a duplication event within the CDC11 locus in Ashbya gossypii gave rise to two similar but distinct Cdc11 proteins: Cdc11a and Cdc1b. CDC11b transcription is developmentally regulated, producing different amounts of Cdc11a- and Cdc11b-complexes in the lifecycle of Ashbya gossypii. Deletion of either gene results in distinct cell polarity defects, suggesting non-overlapping functions. Cdc11a and Cdc11b complexes have differences in filament length and membrane-binding ability. Thus, septin subunit composition has functional consequences on filament properties and cell morphogenesis. Small sequence differences elicit distinct biophysical properties and cell functions of septins, illuminating how gene duplication could be a driving force for septin gene expansions seen throughout the tree of life.
  • Article
    Vast heterogeneity in cytoplasmic diffusion rates revealed by nanorheology and Doppelgänger simulations
    (Biophysical Society, 2023-03-07) Garner, Rikki M. ; Molines, Arthur T. ; Theriot, Julie A. ; Chang, Fred
    The cytoplasm is a complex, crowded, actively driven environment whose biophysical characteristics modulate critical cellular processes such as cytoskeletal dynamics, phase separation, and stem cell fate. Little is known about the variance in these cytoplasmic properties. Here, we employed particle-tracking nanorheology on genetically encoded multimeric 40 nm nanoparticles (GEMs) to measure diffusion within the cytoplasm of individual fission yeast (Schizosaccharomyces pombe) cellscells. We found that the apparent diffusion coefficients of individual GEM particles varied over a 400-fold range, while the differences in average particle diffusivity among individual cells spanned a 10-fold range. To determine the origin of this heterogeneity, we developed a Doppelgänger simulation approach that uses stochastic simulations of GEM diffusion that replicate the experimental statistics on a particle-by-particle basis, such that each experimental track and cell had a one-to-one correspondence with their simulated counterpart. These simulations showed that the large intra- and inter-cellular variations in diffusivity could not be explained by experimental variability but could only be reproduced with stochastic models that assume a wide intra- and inter-cellular variation in cytoplasmic viscosity. The simulation combining intra- and inter-cellular variation in viscosity also predicted weak nonergodicity in GEM diffusion, consistent with the experimental data. To probe the origin of this variation, we found that the variance in GEM diffusivity was largely independent of factors such as temperature, the actin and microtubule cytoskeletons, cell-cyle stage, and spatial locations, but was magnified by hyperosmotic shocks. Taken together, our results provide a striking demonstration that the cytoplasm is not “well-mixed” but represents a highly heterogeneous environment in which subcellular components at the 40 nm size scale experience dramatically different effective viscosities within an individual cell, as well as in different cells in a genetically identical population. These findings carry significant implications for the origins and regulation of biological noise at cellular and subcellular levels.
  • Article
    Curvature sensing as an emergent property of multiscale assembly of septins
    (National Academy of Sciences, 2023-02-07) Shi, Wenzheng ; Cannon, Kevin S ; Curtis, Brandy N ; Edelmaier, Christopher ; Gladfelter, Amy S ; Nazockdast, Ehssan
    The ability of cells to sense and communicate their shape is central to many of their functions. Much is known about how cells generate complex shapes, yet how they sense and respond to geometric cues remains poorly understood. Septins are GTP-binding proteins that localize to sites of micrometer-scale membrane curvature. Assembly of septins is a multistep and multiscale process, but it is unknown how these discrete steps lead to curvature sensing. Here, we experimentally examine the time-dependent binding of septins at different curvatures and septin bulk concentrations. These experiments unexpectedly indicated that septins' curvature preference is not absolute but rather is sensitive to the combinations of membrane curvatures present in a reaction, suggesting that there is competition between different curvatures for septin binding. To understand the physical underpinning of this result, we developed a kinetic model that connects septins' self-assembly and curvature-sensing properties. Our experimental and modeling results are consistent with curvature-sensitive assembly being driven by cooperative associations of septin oligomers in solution with the bound septins. When combined, the work indicates that septin curvature sensing is an emergent property of the multistep, multiscale assembly of membrane-bound septins. As a result, curvature preference is not absolute and can be modulated by changing the physicochemical and geometric parameters involved in septin assembly, including bulk concentration, and the available membrane curvatures. While much geometry-sensitive assembly in biology is thought to be guided by intrinsic material properties of molecules, this is an important example of how curvature sensing can arise from multiscale assembly of polymers.
  • Article
    Three-dimensional structured illumination microscopy with enhanced axial resolution
    (Nature Research, 2023-01-26) Li, Xuesong ; Wu, Yicong ; Su, Yijun ; Rey-Suarez, Ivan ; Matthaeus, Claudia ; Updegrove, Taylor B. ; Wei, Zhuang ; Zhang, Lixia ; Sasaki, Hideki ; Li, Yue ; Guo, Min ; Giannini, John P. ; Vishwasrao, Harshad D. ; Chen, Jiji ; Lee, Shih-Jong J. ; Shao, Lin ; Liu, Huafeng ; Ramamurthi, Kumaran S. ; Taraska, Justin W. ; Upadhyaya, Arpita ; La Riviere, Patrick ; Shroff, Hari
    The axial resolution of three-dimensional structured illumination microscopy (3D SIM) is limited to ∼300 nm. Here we present two distinct, complementary methods to improve axial resolution in 3D SIM with minimal or no modification to the optical system. We show that placing a mirror directly opposite the sample enables four-beam interference with higher spatial frequency content than 3D SIM illumination, offering near-isotropic imaging with ∼120-nm lateral and 160-nm axial resolution. We also developed a deep learning method achieving ∼120-nm isotropic resolution. This method can be combined with denoising to facilitate volumetric imaging spanning dozens of timepoints. We demonstrate the potential of these advances by imaging a variety of cellular samples, delineating the nanoscale distribution of vimentin and microtubule filaments, observing the relative positions of caveolar coat proteins and lysosomal markers and visualizing cytoskeletal dynamics within T cells in the early stages of immune synapse formation.
  • Article
    Stereotyped behavioral maturation and rhythmic quiescence in C. elegans embryos
    (eLife Sciences Publications, 2022-08-05) Ardiel, Evan L. ; Lauziere, Andrew ; Xu, Stephen ; Harvey, Brandon J. ; Christensen, Ryan Patrick ; Nurrish, Stephen ; Kaplan, Joshua M. ; Shroff, Hari
    Systematic analysis of rich behavioral recordings is being used to uncover how circuits encode complex behaviors. Here, we apply this approach to embryos. What are the first embryonic behaviors and how do they evolve as early neurodevelopment ensues? To address these questions, we present a systematic description of behavioral maturation for Caenorhabditis elegans embryos. Posture libraries were built using a genetically encoded motion capture suit imaged with light-sheet microscopy and annotated using custom tracking software. Analysis of cell trajectories, postures, and behavioral motifs revealed a stereotyped developmental progression. Early movement is dominated by flipping between dorsal and ventral coiling, which gradually slows into a period of reduced motility. Late-stage embryos exhibit sinusoidal waves of dorsoventral bends, prolonged bouts of directed motion, and a rhythmic pattern of pausing, which we designate slow wave twitch (SWT). Synaptic transmission is required for late-stage motion but not for early flipping nor the intervening inactive phase. A high-throughput behavioral assay and calcium imaging revealed that SWT is elicited by the rhythmic activity of a quiescence-promoting neuron (RIS). Similar periodic quiescent states are seen prenatally in diverse animals and may play an important role in promoting normal developmental outcomes.
  • Article
    Ca2+ entry units in a superfast fish muscle
    (Frontiers Media, 2022-10-28) Kittelberger, J. Matthew ; Franzini-Armstrong, Clara ; Boncompagni, Simona
    Over the past two decades, mounting evidence has demonstrated that a mechanism known as store-operated Ca2+ entry (SOCE) plays a crucial role in sustaining skeletal muscle contractility by facilitating Ca2+ influx from the extracellular space during sarcoplasmic reticulum (SR) Ca2+ depletion. We recently demonstrated that, in exercised fast-twitch muscle from mice, the incidence of Ca2+ entry units (CEUs), newly described intracellular junctions between dead-end longitudinal transverse tubular (T-tubule) extensions and stacks of sarcoplasmic reticulum (SR) flat cisternae, strictly correlate with both the capability of fibers to maintain contractions during fatigue and enhanced Ca2+ influx via SOCE. Here, we tested the broader relevance of this result across vertebrates by searching for the presence of CEUs in the vocal muscles of a teleost fish adapted for extended, high-frequency activity. Specifically, we examined active vs. inactive superfast sonic muscles of plainfin midshipman (Porichthys notatus). Interestingly, muscles from actively humming territorial males had a much higher incidence of CEU SR stacks relative to territorial males that were not actively vocalizing, strengthening the concept that assembly of these structures is dynamic and use-dependent, as recently described in exercised muscles from mice. Our results support the hypothesis that CEUs represent a conserved mechanism, across vertebrates, for enabling high levels of repetitive muscle activity, and also provide new insights into the adaptive mechanisms underlying the unique properties of superfast midshipman sonic muscles.
  • Article
    Mycobacteriophage Tarkin: a Cluster E Phage
    (American Society for Microbiology, 2022-11-21) Cleary, Katherine E. ; Fakhri, Anna M. ; Dionne, Ethan N. ; Warner, Marcie ; DeGiorgis, Joseph A. ; Cornely, Kathleen
    Mycobacteriophage Tarkin is a newly isolated phage that infects Mycobacterium smegmatis mc155. Tarkin was discovered in Providence, RI, and has a 75,998-bp genome sequence. Tarkin is predicted to have 142 protein coding genes and 2 tRNA genes. Based on gene content similarity, Tarkin is grouped with mycobacteriophages in cluster E.
  • Article
    Incorporating the image formation process into deep learning improves network performance
    (Nature Research, 2022-10-31) Li, Yue ; Su, Yijun ; Guo, Min ; Han, Xiaofei ; Liu, Jiamin ; Vishwasrao, Harshad D ; Li, Xuesong ; Christensen, Ryan ; Sengupta, Titas ; Moyle, Mark W ; Rey-Suarez, Ivan ; Chen, Jiji ; Upadhyaya, Arpita ; Usdin, Ted B ; Colón-Ramos, Daniel Alfonso ; Liu, Huafeng ; Wu, Yicong ; Shroff, Hari
    We present Richardson–Lucy network (RLN), a fast and lightweight deep learning method for three-dimensional fluorescence microscopy deconvolution. RLN combines the traditional Richardson–Lucy iteration with a fully convolutional network structure, establishing a connection to the image formation process and thereby improving network performance. Containing only roughly 16,000 parameters, RLN enables four- to 50-fold faster processing than purely data-driven networks with many more parameters. By visual and quantitative analysis, we show that RLN provides better deconvolution, better generalizability and fewer artifacts than other networks, especially along the axial dimension. RLN outperforms classic Richardson–Lucy deconvolution on volumes contaminated with severe out of focus fluorescence or noise and provides four- to sixfold faster reconstructions of large, cleared-tissue datasets than classic multi-view pipelines. We demonstrate RLN’s performance on cells, tissues and embryos imaged with widefield-, light-sheet-, confocal- and super-resolution microscopy.
  • Article
    Electrophysiological responses to conspecific odorants in Xenopus laevis show potential for chemical signaling
    (Public Library of Science, 2022-09-02) Rhodes, Heather J ; Amo, Melanie
    The fully aquatic African clawed frog, Xenopus laevis, has an unusual and highly adapted nose that allows it to separately sample both airborne and waterborne stimuli. The function of the adult water nose has received little study, despite the fact that it is quite likely to receive information about conspecifics through secretions released into the water and could aid the frog in making decisions about social and reproductive behaviors. To assess the potential for chemical communication in this species, we developed an in situ electroolfactogram preparation and tested the olfactory responses of adult males to cloacal fluids and skin secretions from male and female conspecifics. We found robust olfactory responses to all conspecific stimuli, with greatest sensitivity to female cloacal fluids. These results open the door to further testing to identify compounds within cloacal fluids and skin secretions that are driving these responses and examine behavioral responses to those compounds. Understanding the role of chemical communication in social and reproductive behaviors may add to our rich understanding of vocal communication to create a more complete picture of social behavior in this species.
  • Article
    Dissociation and reaggregation of Hydra vulgaris for studies of self-organization
    (Cell Press, 2022-08-18) Lovas, Jonathan R. ; Yuste, Rafael
    The remarkable regenerative abilities of the small cnidarian Hydra vulgaris include the capacity to reassemble itself after dissociation into individual cells. Here, we present a robust protocol for the dissociation and reaggregation of Hydra tissue that addresses many common challenges encountered during the preparation and execution of the dissociation, as well as the formation and care of regenerating cellular aggregates. Analysis of the process provides insight into the mechanisms of nervous system self-organization.For complete details on the use and execution of this protocol, please refer to Lovas and Yuste (2021).[Display omitted]•Amplify experimental Hydra and prepare for the animal’s dissociation•Dissociate Hydra into individual cells, aggregate, and monitor their reassembly•Follow Hydra’s epithelial layer segregation and neural circuit formation•A new polyp emerges from the cellular aggregate after one week of developmentPublisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.The remarkable regenerative abilities of the small cnidarian Hydra vulgaris include the capacity to reassemble itself after dissociation into individual cells. Here, we present a robust protocol for the dissociation and reaggregation of Hydra tissue that addresses many common challenges encountered during the preparation and execution of the dissociation, as well as the formation and care of regenerating cellular aggregates. Analysis of the process provides insight into the mechanisms of nervous system self-organization.
  • Article
    Oceanic lobate ctenophores possess feeding mechanics similar to the impactful coastal species Mnemiopsis leidyi
    (Association for the Sciences of Limnology and Oceanography, 2022-09-23) Cordeiro, Malaika ; Costello, John H. ; Gemmell, Brad J. ; Sutherland, Kelly R. ; Colin, Sean P.
    Lobate ctenophores are often numerically dominant members of oceanic epipelagic and midwater ecosystems. Despite this, little is known about their trophic ecology. Multiple, co‐occurring species are often found in these ecosystems and appear to feed similarly via feeding currents that entrain prey. We quantified the hydrodynamics, morphology, and behavior of four co‐occurring, cosmopolitan lobate species (Eurhamphaea vexilligera, Ocyropsis crystallina, Bolinopsis vitrea, and Leucothea multicornis) to evaluate whether their feeding mechanics lead to differential feeding rates and prey selection. We compared the feeding characteristics of these four oceanic species to the coastal lobate ctenophore, Mnemiopsis leidyi, which is known as a voracious zooplanktivore. We found that despite their morphological diversity, the five lobate species used the same mechanism to generate their feeding current—the hydrodynamics of their feeding currents were similarly laminar and with very low fluid deformation rates. Despite having similar feeding current traits, the species had different in situ swimming behaviors and feeding postures. We show that these different behaviors and postures lead to different prey encounter rates and that several of the oceanic species have the potential to feed at rates similar to or greater than M. leidyi. As such, the individual and combined trophic impact of oceanic lobate ctenophores is likely to be much greater than previously predicted.
  • Article
    Would Antarctic marine benthos survive alien species invasions? What chemical ecology may tell us
    (MDPI, 2022-08-24) Avila, Conxita ; Buñuel, Xavier ; Carmona, Francesc ; Cotado, Albert ; Sacristán-Soriano, Oriol ; Angulo-Preckler, Carlos
    Many Antarctic marine benthic macroinvertebrates are chemically protected against predation by marine natural products of different types. Antarctic potential predators mostly include sea stars (macropredators) and amphipod crustaceans (micropredators) living in the same areas (sympatric). Recently, alien species (allopatric) have been reported to reach the Antarctic coasts, while deep-water crabs are suggested to be more often present in shallower waters. We decided to investigate the effect of the chemical defenses of 29 representative Antarctic marine benthic macroinvertebrates from seven different phyla against predation by using non-native allopatric generalist predators as a proxy for potential alien species. The Antarctic species tested included 14 Porifera, two Cnidaria, two Annelida, one Nemertea, two Bryozooa, three Echinodermata, and five Chordata (Tunicata). Most of these Antarctic marine benthic macroinvertebrates were chemically protected against an allopatric generalist amphipod but not against an allopatric generalist crab from temperate waters. Therefore, both a possible recolonization of large crabs from deep waters or an invasion of non-native generalist crab species could potentially alter the fundamental nature of these communities forever since chemical defenses would not be effective against them. This, together with the increasing temperatures that elevate the probability of alien species surviving, is a huge threat to Antarctic marine benthos.
  • Article
    How many individuals consider themselves to be cell biologists but are informed by the journal that their work is not cell biology
    (Wiley, 2022-09-09) Worliczek, Hanna Lucia
    Abstract What can we gain from co-analyzing experimental cultures, regionalization, and disciplinary phenomena of late twentieth century life sciences under our historiographic looking glass? This essay investigates the potential of such a strategy for the case of cell biology after 1960. By merging perspectives from historical epistemology inspired by the work of Hans-Jörg Rheinberger with a focus on boundary work in the realm of scientific publishing, community building, and disciplinary norms, a set of understudied scientific practices is exposed. These practices, historically subsumed under the label descriptive, have been as central in cell biology as hypothesis-driven research aiming at mechanistic explanations of cellular function. Against the background of an increasing molecular-mechanistic imperative in cell biology since the late 1960s, knowledge from descriptive practices was often judged as having low value but was nonetheless frequently cited and considered essential. Investigating the underlying epistemic practices and their interactions with disciplinary gatekeeping phenomena (as policed by journals and learned societies) provides historiographic access to the plurality of experimental cultures of cell biology, scattered into many interdisciplinary research fields?with some of them only partially engaged with mechanistic questions.
  • Article
    Chronic exposure to insecticides impairs honeybee optomotor behaviour
    (Frontiers Media, 2022-08-17) Parkinson, Rachel H. ; Fecher, Caroline ; Gray, John R.
    Honeybees use wide-field visual motion information to calculate the distance they have flown from the hive, and this information is communicated to conspecifics during the waggle dance. Seed treatment insecticides, including neonicotinoids and novel insecticides like sulfoxaflor, display detrimental effects on wild and managed bees, even when present at sublethal quantities. These effects include deficits in flight navigation and homing ability, and decreased survival of exposed worker bees. Neonicotinoid insecticides disrupt visual motion detection in the locust, resulting in impaired escape behaviors, but it had not previously been shown whether seed treatment insecticides disrupt wide-field motion detection in the honeybee. Here, we show that sublethal exposure to two commonly used insecticides, imidacloprid (a neonicotinoid) and sulfoxaflor, results in impaired optomotor behavior in the honeybee. This behavioral effect correlates with altered stress and detoxification gene expression in the brain. Exposure to sulfoxaflor led to sparse increases in neuronal apoptosis, localized primarily in the optic lobes, however there was no effect of imidacloprid. We propose that exposure to cholinergic insecticides disrupts the honeybee’s ability to accurately encode wide-field visual motion, resulting in impaired optomotor behaviors. These findings provide a novel explanation for previously described effects of neonicotinoid insecticides on navigation and link these effects to sulfoxaflor for which there is a gap in scientific knowledge.
  • Article
    Trapping of nicotinic acetylcholine receptor ligands assayed by in vitro cellular studies and in vivo PET imaging
    (Society for Neuroscience, 2023-01-04) Zhang, Hannah J. ; Zammit, Matthew ; Kao, Chien-Min ; Govind, Anitha P. ; Mitchell, Samuel J. ; Holderman, Nathanial ; Bhuiyan, Mohammed ; Freifelder, Richard ; Kucharski, Anna ; Zhuang, Xiaoxi ; Mukherjee, Jogeshwar ; Chen, Chin-Tu ; Green, William N.
    A question relevant to nicotine addiction is how nicotine and other nicotinic receptor membrane-permeant ligands, such as the anti-smoking drug varenicline (Chantix), distribute in brain. Ligands, like varenicline, with high pKa and high affinity for α4β2-type nicotinic receptors (α4β2Rs) are trapped in intracellular acidic vesicles containing α4β2Rs in vitro. Nicotine, with lower pKa and α4β2R affinity, is not trapped. Here, we extend our results by imaging nicotinic PET ligands in vivo in male and female mouse brain and identifying the trapping brain organelle in vitro as Golgi satellites (GSats). Two PET 18F-labeled imaging ligands were chosen: [18F]2-FA85380 (2-FA) with varenicline-like pKa and affinity and [18F]Nifene with nicotine-like pKa and affinity. [18F]2-FA PET-imaging kinetics were very slow consistent with 2-FA trapping in α4β2R-containing GSats. In contrast, [18F]Nifene kinetics were rapid, consistent with its binding to α4β2Rs but no trapping. Specific [18F]2-FA and [18F]Nifene signals were eliminated in β2 subunit knock-out (KO) mice or by acute nicotine (AN) injections demonstrating binding to sites on β2-containing receptors. Chloroquine (CQ), which dissipates GSat pH gradients, reduced [18F]2-FA distributions while having little effect on [18F]Nifene distributions in vivo consistent with only [18F]2-FA trapping in GSats. These results are further supported by in vitro findings where dissipation of GSat pH gradients blocks 2-FA trapping in GSats without affecting Nifene. By combining in vitro and in vivo imaging, we mapped both the brain-wide and subcellular distributions of weak-base nicotinic receptor ligands. We conclude that ligands, such as varenicline, are trapped in neurons in α4β2R-containing GSats, which results in very slow release long after nicotine is gone after smoking.
  • Article
    Genomes from uncultivated Pelagiphages reveal multiple phylogenetic clades exhibiting extensive auxiliary metabolic genes and cross-family multigene transfers
    (American Society for Microbiology, 2022-08-16) Wittmers, Fabian ; Needham, David M. ; Hehenberger, Elisabeth ; Giovannoni, Stephen J. ; Worden, Alexandra Z.
    For the abundant marine Alphaproteobacterium Pelagibacter (SAR11), and other bacteria, phages are powerful forces of mortality. However, little is known about the most abundant Pelagiphages in nature, such as the widespread HTVC023P-type, which is currently represented by two cultured phages. Using viral metagenomic data sets and fluorescence-activated cell sorting, we recovered 80 complete, undescribed Podoviridae genomes that form 10 phylogenomically distinct clades (herein, named Clades I to X) related to the HTVC023P-type. These expanded the HTVC023P-type pan-genome by 15-fold and revealed 41 previously unknown auxiliary metabolic genes (AMGs) in this viral lineage. Numerous instances of partner-AMGs (colocated and involved in related functions) were observed, including partners in nucleotide metabolism, DNA hypermodification, and Curli biogenesis. The Type VIII secretion system (T8SS) responsible for Curli biogenesis was identified in nine genomes and expanded the repertoire of T8SS proteins reported thus far in viruses. Additionally, the identified T8SS gene cluster contained an iron-dependent regulator (FecR), as well as a histidine kinase and adenylate cyclase that can be implicated in T8SS function but are not within T8SS operons in bacteria. While T8SS are lacking in known Pelagibacter, they contribute to aggregation and biofilm formation in other bacteria. Phylogenetic reconstructions of partner-AMGs indicate derivation from cellular lineages with a more recent transfer between viral families. For example, homologs of all T8SS genes are present in syntenic regions of distant Myoviridae Pelagiphages, and they appear to have alphaproteobacterial origins with a later transfer between viral families. The results point to an unprecedented multipartner-AMG transfer between marine Myoviridae and Podoviridae. Together with the expansion of known metabolic functions, our studies provide new prospects for understanding the ecology and evolution of marine phages and their hosts.
  • Article
    Dynein-dependent collection of membranes defines the architecture and position of microtubule asters in isolated, geometrically confined volumes of cell-free extracts
    (American Society for Cell Biology, 2022-09-07) Sami, Abdullah Bashar ; Gatlin, Jesse C.
    It is well established that changes in the underlying architecture of the cell’s microtubule (MT) network can affect organelle organization within the cytoplasm, but it remains unclear whether the spatial arrangement of organelles reciprocally influences the MT network. Here we use a combination of cell-free extracts and hydrogel microenclosures to characterize the relationship between membranes and MTs during MT aster centration. We found that initially disperse ER membranes are collected by the aster and compacted near its nucleating center, all while the whole ensemble moves toward the geometric center of its confining enclosure. Once there, aster MTs adopt a bull’s-eye pattern with a high-density annular ring of MTs surrounding the compacted membrane core of lower MT density. Formation of this pattern was inhibited when dynein-dependent transport was perturbed or when membranes were depleted from the extracts. Asters in membrane-depleted extracts were able to move away from the most proximal wall but failed to center in cylindrical enclosures with diameters greater than or equal to 150 µm. Taken as whole, our data suggest that the dynein-dependent transport of membranes buttresses MTs near the aster center and that this plays an important role in modulating aster architecture and position.
  • Article
    Farm-waste-derived recyclable photothermal evaporator
    (Cell Press, 2021-08-20) Tian, Yanpei ; Liu, Xiaojie ; Li, Jiansheng ; Deng, Yichen ; DeGiorgis, Joseph A. ; Zhou, Shiyu ; Caratenuto, Andrew ; Minus, Marilyn L. ; Wan, Yinsheng ; Xiao, Gang ; Zheng, Yi
    Interfacial solar steam generation is emerging as a promising technique for efficient desalination. Although increasing efforts have been made, challenges exist for achieving a balance among a plethora of performance indicators—for example, rapid evaporation, durability, low-cost deployment, and salt rejection. Here, we demonstrate that carbonized manure can convert 98% of sunlight into heat, and the strong capillarity of porous carbon fibers networks pumps sufficient water to evaporation interfaces. Salt diffusion within microchannels enables quick salt drainage to the bulk seawater to prevent salt accumulation. With these advantages, this biomass-derived evaporator is demonstrated to feature a high evaporation rate of 2.81 kg m−2 h−1 under 1 sun with broad robustness to acidity and alkalinity. These advantages, together with facial deployment, offer an approach for converting farm waste to energy with high efficiency and easy implementation, which is particularly well suited for developing regions.