Biology subjects

Brzezinski, M.

Publications and source records attributed to Brzezinski, M..

6 recordsLinked to original sources

bioRxiv2026

Deep tissue removal in wounds facilitates algal colonization and inhibits healing and regeneration in tropical corals

Although corals are highly regenerative, some colonies in reef ecosystems completely recover from sublethal damage while other colonies exhibit partial mortality to similar injuries. To understand factors that might naturally curtail regenerative ability, we experimentally wounded small colonies in three coral genera (Acropora, Pocillopora, Porites) by mimicking natural corallivory using scraping (tissue and skeletal damage) or airbrushing (deep tissue removal with no skeletal injury). We found all scraped wounds regenerated rapidly in Acropora and Porites, while Pocillopora fragments frequently retained open lesions. In stark contrast, airbrushing resulted in algal colonization and delayed tissue healing and regeneration across all corals. Detailed cellular analysis of Porites wounds revealed two general phases comprising tissue regeneration: a healing phase defined by rapid coverage of bare skeleton with coenosarc, pigment cells and gastrodermal reformation, and then a second phase lasting one week ending in polyp regeneration. Red fluorescence appeared transiently in scrape wounds but persisted in tissue at the wound margin surrounding algae in airbrush wounds, suggesting that algal occupation of the wound bed inhibits coenosarc healing. Lastly, histological cross-sections of healing airbrush wounds in Porites revealed progressive loss of deep tissue leading to skeletal breakdown beneath the wound. Together, our results demonstrate the biphasic nature of tissue regeneration in colonial corals and provide a framework for understanding how biotic factors impact tissue repair and regeneration in nature.

zoology↗

bioRxiv2023

Protein-specific crowding accelerates aging in phase-separated droplets

Crowding agents, such as polyethylene glycol (PEG, are often used to mimic the cellular cytoplasm in protein assembly studies. Despite the perception that crowding agents have an inert nature, recent work has shown they are not bystanders while proteins interact. Here, we explore the diverse effects of PEG on the phase separation and maturation of proteins. We use two proteins, the FG domain of Nup98 and bovine serum albumin (BSA), which represent an intrinsically disordered protein and a protein with well-established secondary structure, respectively. PEG expedites the maturation of Nup98, enhancing denser protein packing and fortifying hydrophobic interactions which hasten beta-sheet formation and subsequent droplet gelation. In contrast for BSA, PEG appears to enhance droplet stability and limits available solvent for the protein solubilization, without inducing significant changes to the secondary structure, pointing towards a significantly different behavior of the crowding agent. Interestingly, we detect almost no presence of PEG in Nup droplets whereas PEG is detectable within BSA droplets. Our findings demonstrate a nuanced interplay between crowding agents and proteins. PEG can accelerate protein maturation in LLPS systems but its partitioning and effect on protein structure in droplets is protein specific. This suggests that crowding phenomena are specific to each protein-crowding agent pair.

biophysics↗

bioRxiv2023

Primary production dynamics during the decline phase of the North Atlantic annual spring bloom

The second field campaign of the NASA EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) program was conducted in the late spring of 2021 within the vicinity of the Porcupine Abyssal Plain (49.0{degrees}N, 16.5{degrees}W) in the North Atlantic Ocean. Observations from EXPORTS support previous characterizations of this system as highly productive and organic matter rich, with the majority of primary production occurring in large cells ([≥] 5 {micro}m) such as diatoms that are primarily utilizing nitrate. Rates of total euphotic zone depth-integrated net primary production ranged from 36.4 to 146.6 mmol C m- 2 d-1, with an observational period average f-ratio of 0.74, indicating predominantly new production. Substantial variability in the contribution of small (<5 {micro}m) and large cells occurred over the observation period, coinciding with the end of the annual spring phytoplankton bloom. Physical changes associated with storms appear to have impacted the integrated production rates substantially, enhancing rates by [~]10%. These disturbances altered the balance between contributions of the different phytoplankton size fractions, thus highlighting the important role of mixed layer variability in nutrient entrainment into the upper water column and production dynamics. In diatoms, inputs of silicic acid related to deepening of the mixed layer increased silicic acid uptake rates yet concomitant increases in NPP in large cells was not observed. This campaign serves as the high productivity endmember within the EXPORTS program and as such, elucidates how nutrient concentrations and size class play key roles in both low and high productivity systems, but in differing ways.

ecology↗

bioRxiv2021

Role of Solvent Compatibility in the Phase Behavior of Binary Solutions of Weakly Associating Multivalent Polymers

Condensate formation of biopolymer solutions, prominently those of various intrinsically disordered proteins (IDPs), is determined by "sticky" interactions between associating residues, multivalently present along the polymer backbone. Using a ternary mean field "stickers-and-spacers" model, we demonstrate that if sticker association is of the order of a few times the thermal energy, a delicate balance between specific binding and non-specific polymer-solvent interactions gives rise to a particularly rich ternary phase behavior under physiological circumstances. For a generic system represented by a solution comprising multi-associative scaffold and client polymers, the difference in solvent compatibility between the polymers modulates the nature of isothermal liquid-liquid phase separation (LLPS) between associative and segregative. The calculations reveal regimes of dualistic phase behavior, where both types of LLPS occur within the same phase diagram, either associated with the presence of multiple miscibility gaps, or a flip in the slope of the tie-lines belonging to a single coexistence region.

biophysics↗

bioRxiv2020

Opto-E-Dura: a Soft, Stretchable ECoG Array for Multimodal, Multi-scale Neuroscience

Soft, stretchable materials hold great promise for the fabrication of biomedical devices due to their capacity to integrate gracefully with and conform to biological tissues. Conformal devices are of particular interest in the development of brain interfaces where rigid structures can lead to tissue damage and loss of signal quality over the lifetime of the implant. Interfaces to study brain function and dysfunction increasingly require multimodal access in order to facilitate measurement of diverse physiological signals that span the disparate temporal and spatial scales of brain dynamics. Here we present the Opto-e-Dura, a soft, stretchable, 16-channel electrocorticography array that is optically transparent. We demonstrate its compatibility with diverse optical and electrical readouts enabling multimodal studies that bridge spatial and temporal scales. The device is chronically stable for weeks, compatible with wide-field and 2-photon calcium imaging and permits the repeated insertion of penetrating multi-electrode arrays. As the variety of sensors and effectors realizable on soft, stretchable substrates expands, similar devices that provide large-scale, multimodal access to the brain will continue to improve fundamental understanding of brain function.

neuroscience↗

bioRxiv2020

Complex genetic network underlying the convergent of Rett Syndrome like (RTT-L) phenotype in neurodevelopmental disorders

Mutations of the X-linked gene encoding methyl-CpG-binding protein 2 (MECP2) cause classical forms of Rett syndrome (RTT) in girls. Patients with features of classical Rett syndrome, but do not fulfill all the diagnostic criteria (e.g. absence of a MECP2 mutation), are defined as atypical Rett syndrome. Genes encoding for cyclin-dependent kinase-like 5 (CDKL5) and forkhead box G1 (FOXG1) are more commonly found in patients with atypical Rett syndrome. Nevertheless, a subset of patients who are recognized to have an overlapping phenotype with RTT but are lacking a mutation in a gene that causes typical or atypical RTT are described as having Rett syndrome like phenotype (RTT-L). Whole Exome Sequencing (WES) of 8 RTT-L patients from our cohort revealed mutations in the genes GABRG2, GRIN1, ATP1A2, KCNQ2, KCNB1, TCF4, SEMA6B, and GRIN2A, which are seemingly unrelated to Rett syndrome genes. We hypothesized that the phenotypic overlap in RTT and RTT-L is caused by mutations in genes that affect common cellular pathways critical for normal brain development and function. We annotated the list of genes identified causing RTT-L from peer-reviewed articles and performed a protein-protein interaction (PPI) network analysis. We also investigated their interaction with RTT (typical or atypical) genes such as MECP2, CDKL5, NTNG1, and FOXG1. We found that the RTT-L-causing genes were enriched in the biological pathways such as circadian entrainment, the CREB pathway, and RET signaling, and neuronal processes like ion transport, synaptic transmission, and transcription. We conclude that genes that significantly interact with the PPI network established by RTT genes cause RTT-L, explaining the considerable feature overlap between genes that are indicated for RTT-L and RTT.

genomics↗