More Like this

1. Biogenic structures and cable bacteria interactions: redox domain residence times and the generation of complex pH distributions

   https://doi.org/10.3354/meps13722  

   Yin, H ; Aller, RC ; Zhu, Q ; Aller, JY ( July 2021 , Marine Ecology Progress Series)

   null (Ed.)

   Cable bacteria are multicellular filamentous bacteria that conduct electrons nonlocally between anoxic and oxic sediment regions, creating characteristic electrogenic pH fingerprints. These microbes aggregate in 3D patterns near biogenic structures, and filament fragments are also dispersed throughout deposits. Utilizing pH-sensitive planar optodes to investigate the dynamic response of electrogenic pH fingerprints to sediment reworking, we found that mobile bioturbators like nereid polychaetes (ragworms) can disturb the pH signatures. Sudden sediment disturbance associated with burrows at sub- to multi-centimeter scales eliminates detection of pH signatures. However, electrogenic pH fingerprints can recover in as little as 13 h near abandoned, closed burrows. Sequential collapse and regeneration of electrogenic pH fingerprints are associated with occupied and dynamic burrow structures, with the response time positively related to the scale of disturbance. In the case of relatively stable tube structures, built by benthos like spionid polychaetes and extending mm to cm into deposits, the electrogenic pH fingerprint is evident around the subsurface tubes. Cable filaments clearly associate with subsurface regions of enhanced solute exchange (oxidant supply) and relatively stable biogenic structures, including individual tubes and patches of tubes (e.g. made by Sabaco , a bamboo worm). Physically stable environments, favorable redox gradients, and enhanced organic/inorganic substrate availability promote the activity of cable bacteria in the vicinity of tubes and burrows. These findings suggest complex interactions between electrogenic activity fingerprints and species-specific patterns of bioturbation at multiple spatial and temporal scales, and a substantial impact of electrogenic metabolism on subsurface pH and early diagenetic reaction distributions in bioturbated deposits. 

   more » « less
2. Reconstructing the paleoenvironment of an oxygenated Mesoproterozoic shoreline and its record of life

   https://doi.org/10.1130/B36634.1  

   Slotznick, Sarah P. ; Swanson-Hysell, Nicholas L. ; Zhang, Yiming ; Clayton, Katherine E. ; Wellman, Charles H. ; Tosca, Nicholas J. ; Strother, Paul K. ( August 2023 , Geological Society of America Bulletin)

   The Nonesuch Formation microbiota provide a window into ca. 1075 Ma life within the interior of ancient North America. The Nonesuch water body formed following the cessation of widespread volcanism within the Midcontinent Rift as the basin continued to subside. In northern Michigan and Wisconsin, USA, the Copper Harbor Conglomerate records terrestrial alluvial fan and fluvial plain environments that transitioned into subaqueous lacustrine deposition of the Nonesuch Formation. These units thin toward a paleotopographic high associated with the Brownstone Falls angular unconformity. Due to these “Brownstone Highlands,” we were able to explore the paleoenvironment laterally at different depths in contemporaneous deposits. Rock magnetic data constrain that when the lake was shallow, it was oxygenated as evidenced by an oxidized mineral assemblage. Oxygen levels were lower at greater depth—in the deepest portions of the water body, anoxic conditions are recorded. An intermediate facies in depth and redox between these endmembers preserves detrital magnetite and hematite, which can be present in high abundance due to the proximal volcanic highlands. This magnetic facies enabled the development of a paleomagnetic pole based on both detrital magnetite and hematite that constrains the paleolatitude of the lake to 7.1 ± 2.8°N. Sediments of the intermediate facies preserve exquisite organic-walled microfossils, with microfossils being less diverse to absent in the anoxic facies where amorphous organic matter is more likely to be preserved. The assemblage of cyanobacteria and eukaryotes (both photoautotrophs and heterotrophs) lived within the oxygenated waters of this tropical Mesoproterozoic water body. 

   more » « less
3. Non-dispersive phloem-protein bodies (NPBs) of Populus trichocarpa consist of a SEOR protein and do not respond to cell wounding and Ca 2+

   https://doi.org/10.7717/peerj.4665  

   Mullendore, Daniel L. ; Ross-Elliott, Timothy ; Liu, Yan ; Hellmann, Hanjo H. ; Roalson, Eric H. ; Peters, Winfried S. ; Knoblauch, Michael ( April 2018 , PeerJ)

   Differentiating sieve elements in the phloem of angiosperms produce abundant phloem-specific proteins before their protein synthesis machinery is degraded. These P-proteins initially form dense bodies, which disperse into individual filaments when the sieve element matures. In some cases, however, the dense protein agglomerations remain intact and are visible in functional sieve tubes as non-dispersive P-protein bodies, or NPBs. Species exhibiting NPBs are distributed across the entire angiosperm clade. We found that NPBs in the model tree,Populus trichocarpa, resemble the protein bodies described from other species of the order Malpighiales as they all consist of coaligned tubular fibrils bundled in hexagonal symmetry. NPBs of all Malpighiales tested proved unresponsive to sieve tube wounding and Ca²⁺. TheP. trichocarpaNPBs consisted of a protein encoded by a gene that in the genome database of this species had been annotated as a homolog ofSEOR1(sieve element occlusion-related 1) inArabidopsis. Sequencing of the gene in our plants corroborated this interpretation, and we named the genePtSEOR1. Previously characterized SEOR proteins form irregular masses of P-protein slime in functional sieve tubes. We conclude that a subgroup of these proteins is involved in the formation of NPBs at least in the Malpighiales, and that these protein bodies have no role in rapid wound responses of the sieve tube network.

    

   more » « less
4. Drug‐Eluting Endotracheal Tubes for Preventing Bacterial Inflammation in Subglottic Stenosis

   https://doi.org/10.1002/lary.29769  

   Aronson, Matthew R. ; Ali Akbari Ghavimi, Soheila ; Gehret, Paul M. ; Jacobs, Ian N. ; Gottardi, Riccardo ( July 2021 , The Laryngoscope)

   Subglottic stenosis (SGS) results from dysregulated extracellular matrix deposition by laryngotracheal fibroblasts causing scar tissue formation following intubation. Recent work has highlighted a relationship between this inflammatory state and imbalances in the upper airway microbiome. Herein, we engineer novel drug‐eluting endotracheal (ET) tubes to deliver a model antimicrobial peptide Lasioglossin‐III (Lasio) for the local modulation of the microbiome during intubation.

   Controlledin vitrostudy.

   ET tubes were coated with a water‐in‐oil (w/o) emulsion of Lasio in poly(d,l‐lactide‐co‐glycolide) (PLGA) by dipping thrice. Peptide release was quantified over 2 weeks via fluorometric peptide assays. The antibacterial activity was tested against airway microbes (Staphylococcus epidermidis,Streptococcus pneumoniae, and pooled human microbiome samples) by placing Lasio/PLGA‐coated tubes and appropriate controls in 48 well plates with diluted bacteria. Bacterial inhibition and tube adhesion were tested by measuring optical density and colony formation after tube culture, respectively. Biocompatibility was tested against laryngotracheal fibroblasts and lung epithelial cells.

   We achieved a homogeneous coating of ET tubes with Lasio in a PLGA matrix that yields a prolonged, linear release over 1 week (typical timeframe before the ET tube is changed). We observed significant antibacterial activity againstS. epidermidis,S. pneumoniae, and human microbiome samples, and prevention of bacterial adherence to the tube. Additionally, the released Lasio did not cause any cytotoxicity toward laryngotracheal fibroblasts or lung epithelial cellsin vitro.

   Overall, we demonstrate the design of an effective‐eluting ET tube to modulate upper‐airway bacterial infections during intubation which could be deployed to help prevent SGS.

   NALaryngoscope, 132:1356–1363, 2022

    

   more » « less
5. The dynamics of cable bacteria colonization in surface sediments: a 2D view

   https://doi.org/10.1038/s41598-021-86365-1  

   Yin, Hang ; Aller, Robert C. ; Zhu, Qingzhi ; Aller, Josephine Y. ( March 2021 , Scientific Reports)

   Cable bacteria that are capable of transporting electrons on centimeter scales have been found in a variety of sediment types, where their activity can strongly influence diagenetic reactions and elemental cycling. In this study, the patterns of spatial and temporal colonization of surficial sediment by cable bacteria were revealed in two-dimensions by planar pH and H₂S optical sensors for the first time. The characteristic sediment surface pH maximum zones begin to develop from isolated micro-regions and spread horizontally within 5 days, with lateral spreading rates from 0.3 to ~ 1.2 cm day⁻¹. Electrogenic anodic zones in the anoxic sediments are characterized by low pH, and the coupled pH minima also expand with time. H₂S heterogeneities in accordance with electrogenic colonization are also observed. Cable bacteria cell abundance in oxic surface sediment (0–0.25 cm) kept almost constant during the colonization period; however, subsurface cell abundance apparently increased as electrogenic activity expanded across the entire surface. Changes in cell abundance are consistent with filament coiling and growth in the anodic zone (i.e., cathodic snorkels). The spreading mechanism for the sediment pH–H₂S fingerprints and the cable bacteria abundance dynamics suggest that once favorable microenvironments are established, filamentous cable bacteria aggregate or locally activate electrogenic metabolism. Different development dynamics in otherwise similar sediment suggests that the accessibility of reductant (e.g., dissolved phase sulfide) is critical in controlling the growth of cable bacteria.

    

   more » « less