Range Of Cell Sizes Research Articles

Mechanical strategies supporting growth and size diversity in Filamentous Fungi.

The stereotypical tip growth of filamentous fungi supports their lifestyles and functions. It relies on the polarized remodeling and expansion of a protective elastic cell wall (CW) driven by large cytoplasmic turgor pressure. Remarkably, hyphal filament diameters and cell elongation rates can vary extensively among different fungi. To date, however, how fungal cell mechanics may be adapted to support these morphological diversities while ensuring surface integrity remains unknown. Here, we combined super-resolution imaging and deflation assays to measure local CW thickness, elasticity and turgor in a set of fungal species spread on the evolutionary tree that spans a large range in cell size and growth speeds. While CW elasticity exhibited dispersed values, presumably reflecting differences in CW composition, both thickness and turgor scaled in dose-dependence with cell diameter and growth speeds. Notably, larger cells exhibited thinner lateral CWs, and faster cells thinner apical CWs. Counterintuitively, turgor pressure was also inversely scaled with cell diameter and tip growth speed, challenging the idea that turgor is the primary factor dictating tip elongation rates. We propose that fast-growing cells with rapid CW turnover have evolved strategies based on a less turgid cytoplasm and thin walls to safeguard surface integrity and survival.

Lightweight thermoplastic polyurethane/multi-wall carbon nanotube foams with a continuous gradient cell structure for electromagnetic interference shielding

With the rapid development of portable microelectronic devices, materials with tunable electromagnetic shielding (EMI) performance and comfort of use have become urgently necessary. A lightweight, conductive thermoplastic polyurethane/multi-walled carbon nanotube (TPU/MWCNT) composite foam with a continuous gradient cell structure has been developed to impede electromagnetic wave reflection induced by excessive impedance mismatch. The continuous gradient distribution of cell structure and conductivity provides the TPU/MWCNT composite foams with distinct shielding effects of electromagnetic waves in both front and back gradient directions. The maximum front absorption coefficient (A) reached 0.93, which is higher than any foam with a uniform cell size within the cell size range of the gradient composite foams. At the same time, the gradient composite foams possess the characteristics of lightweight, high elasticity, and extensibility. The weight was decreased by 67.27–85.45 %, the elastic recovery ratio of compression reached 95 %, and the toughness was also excellent. Numerical simulation of the gradient foam model was conducted using CST Microwave Studio to uncover the gradient asymptotic dissipation mechanisms. The lightweight and stretchable continuous gradient foams show great promises for the next-generation portable electronic devices that generate no radiation pollution.

Multi-physics simulation of non-equilibrium solidification in Ti-Nb alloy during selective laser melting

This paper underscores the critical role of temperature distribution in the molten pool on the resulting solidification microstructure during selective laser melting (SLM) process. A powder-resolved computational fluid dynamics (CFD) model of Ti-Nb alloy is established to investigate heat transfer and fluid flow in the molten pool. When comparing the bulk model to the powder bed model, discrepancies in temperature gradient and cooling rate can reach up to 26.29 % and 18.32 %, respectively. Utilizing the powder bed CFD model, temperature gradient and cooling rate data at the molten pool boundary are integrated into the finite interface dissipation phase-field model. The simulation results illuminate the non-equilibrium solidification microstructure in the SLMed Ti-Nb alloy. Results indicate that the rapid solidification fosters a pronounced solute trapping effect, mitigating solute microsegregation. The microstructure manifests as cellular and dendritic structures, with Nb concentration in cellular cores and depletion in intercellular region. Predicted primary dendrite arm spacing (PDAS) or cell size range between 0.4 to 0.6 μm, consistent with experimental observations. In particular, the study reveals a transition from dendritic to cellular and from cellular to planar structures, with an accompanying analysis of the underlying mechanisms.

A facile and efficient strategy for fabrication of silicone rubber foam based on in situ precuring‐supercritical CO2 foaming technology

AbstractIn this work, a facile in situ precuring and supercritical CO2 (sc‐CO2) foaming technology is proposed to fabricate silicone rubber foam (SRF) with a tunable cell structure. Uncured silicone rubber is put into the autoclave to saturate sc‐CO2 directly, which not only shorts the saturation time but also accelerates the curing reaction in the precuring process. In the foaming process, cell nucleation is triggered by rapid release of pressure. The cell structure of SRF samples with cell size range of 9.45 to 128.09 μm, cell density range of 3.5 × 105 cells/cm3 to 5.7 × 108 cells/cm3, and porosity range of 28.35% to 77.28% are successfully fabricated by controlling of precuring time, saturation pressure and foaming temperature. To guarantee the dimensional stability and optimize surface quality of SRF samples, in situ post‐curing process is implemented within the foaming mold. With the increase of cell size from 9.91 to 128.09 μm, the compressive stress at strain of 75% decreases from 2.19 to 0.61 MPa, while the energy loss coefficient reduces from 35.4% to 16.9%, exhibiting excellent compression recovery steady. The new technique integrates the precuring, foaming process and post‐curing into an autoclave to simplify the SRF procedure.

Spatial and temporal disturbances in the zone of mining of ferruginous quartzites of the Kostomuksha cluster, NW Russia

The research presents new methods for analyzing spatial and temporal disturbances, focusing on landscape ecology. The study covers the period from the beginning of the development of the field to the present stage. The Land Use and Land Сover (LULC) change analysis is based on processing of Landsat satellite imagery. The method uses landscape metrics, SDI calculation, and mapping to describe the mechanisms of transformation and self-regulation of the system. Landscape metrics include three groups: areas and edges, shape metrics, and diversity metrics. An increase in landscape fragmentation over time is shown. All LULC classes have been changed. The area of the “mining" class has been increased in 7.7% (from 0 to 55.5 thousand km2). The increase in the area of quarries occurs evenly at the expense of all other land use classes. The data obtained confirm several stages of anthropogenic impact. An approach has been developed for mapping disturbances and assessing the impact on geosystemsIt was revealed that in the cell size range from 1500 to 2500 m, the landscape parameters are the most stable. The calculation of the spatial disturbance index is based on principal component analysis data. Factors were identified that indicate external load and the adaptation and self-regulation of the geosystem. Three degrees of disturbance of the territory are defined: low, medium, and high. In 2006, the maximum level of spatial disturbance was found, with the area of heavily disturbed areas being 68%. The results of this study indicate the importance of taking the necessary measures to reduce environmental risks.

Differential cell size reduction of two sympatric Epithemia (Bacillariophyta) taxa in Nakaikemi Wetland, Japan

SUMMARYWe observed contrasting temporal changes in cell size between two Epithemia taxa. The life cycle of diatoms is closely linked to their cell size, with a gradual decrease during the vegetative stage and a recovery through sexual reproduction. Sexual reproduction is triggered when cells become smaller than a species‐specific size threshold and receive species‐specific environmental cues. Few studies have documented the life cycles and frequency of sexual reproduction in diatoms, combining field observations and laboratory culture. We collected two Epithemia taxa, Epithemia gibba var. ventricosa and Epithemia sp. from a pond in Nakaikemi Wetland, and measured their valve lengths monthly for almost 3 years. Additionally, we established cultures of both taxa to examine the rates of cell size reduction, which affect the duration of the vegetative stage. In the field, E. gibba var. ventricosa exhibited a wide range of cell sizes and signs of size recovery. Furthermore, the cultures of this taxon showed a clear decrease in cell size through division, suggesting that sexual reproduction is required for size recovery. On the other hand, Epithemia sp. showed no obvious change in cell size both in the field and in the laboratory. This suggests that either sexual reproduction is not necessary for this taxon to maintain its population or their life cycle extends over several years to several decades. Thus, our findings reveal congeneric taxa sharing a common habitat and substratum, yet exhibiting distinct sexual and asexual strategies. Furthermore, we question the validity of taxonomic classifications previously assigned to these diatoms based on the range of morphological characteristics observed in the present study.

Numerical and experimental study of open-cell foams for the characterization of heat exchangers

A multiscale model of open-cell foams is developed for the characterization of heat exchangers. The model is applicable to a wide range of materials, cell sizes, and porosities. The microscopic geometry is based on a periodic model that is defined by the porosity and the specific surface area of the foam considered. The representative geometrical scales of the model are validated with microscope images and computed tomography scans. The outputs of the microscopic model are the coefficients of the pressure loss curve, the thermal conductivity, and the Nusselt number. These values are used as inputs of the macroscopic model that determines the thermal performance of a macroscopic system. The results given by the models are compared with experimental data obtained from the literature, and from an experimental setup built at CERN. It is concluded that the multiscale model provides accurate results in all open-cell foams considered.

A new microcellular foaming strategy to develop structure-gradient thermoplastic polyurethane foams with enhanced elasticity

Functionally graded polymer foams are advanced materials that exhibit great potential for applications in energy absorption, electromagnetic interference shielding, and high-elasticity due to the graded cellular structure for mechanical performance and functional properties enhancements. However, producing polymer foams with tailored gradient structures remains a significant challenge. Herein, a new microcellular foaming strategy with two-step adsorptions was developed to prepare thermoplastic polyurethane (TPU) foams with gradient cellular structures. The TPU samples were saturated with low-pressure CO2 in the first sorption stage and partially saturated with high-pressure CO2 in the second sorption stage. By regulating CO2 pressure in the first stage and adsorption duration in the second stage, TPU samples with gradient CO2 concentrations were achieved, thereby leading to structure-gradient TPU foams. Finally, a prospective microcellular-macrocellular gradient foam with a cell size range of 30 μm to 400 μm was successfully prepared. The energy loss coefficient of structure-gradient TPU foam can be reduced by 21.5% compared to that of the foam with uniform cellular structure. Structure-gradient TPU foams show significantly enhanced mechanical performance and elasticity, and the underlying mechanism was clarified. The super-elastic TPU foams with tailored gradient structures hold significant promise for broaden applications requiring lightweight, flexibility, and elasticity.

Determining drivers of phytoplankton carbon to chlorophyll ratio at Atlantic Basin scale

We demonstrate the ability of flow cytometry to determine species specific cellular carbon and chlorophyll content in vivo by using laboratory cultures of phytoplankton encompassing a wide range of cell sizes. When applied to the large Atlantic Meridional Transect flow cytometry dataset, we reveal patterns in the species-specific phytoplankton carbon (C), chlorophyll (Chl) and C:Chl ratio. For Prochlorococcus the range of C:Chl is between 2 – 604; for Synechococcus 0.5 – 558. Using a Random Forest machine learning approach, we show that predictability of phytoplankton C:Chl, dominated by the prevalence of Prochlorococcus, is largely driven by silicate and nitrite concentration in the Atlantic Ocean.

Synthesis of metakaolin-based geopolymer foamed materials using municipal solid waste incineration fly ash as a foaming agent

The existence of metallic aluminum in municipal solid waste incineration fly ash (MSWIFA) makes it challenging to recycle MSWIFA into cement materials because expansion occurs in the resultant matrices. Geopolymer-foamed materials (GFMs) are gaining attention in the field of porous materials due to their high-temperature stability, low thermal conductivity and low CO2 emission. This work aimed to utilize MSWIFA as a foaming agent to synthesize GFMs. The physical properties, pore structure, compressive strength and thermal conductivity were analyzed to assess different GFMs which were synthesized with various MSWIFA and stabilizing agent dosages. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis were conducted to characterize the phase transformation of the GFMs. Results showed that when MSWIFA content was increased from 20 to 50%, the porosity of GFMs increased from 63.5 to 73.7%, and bulk density decreased from 890 to 690 kg/m3. The addition of stabilizing agent could trap the foam, refine the cell size, and homogenize the cell size range. With the stabilizing agent increase from 0 to 4%, the porosity increased from 69.9 to 76.8%, and the bulk density decreased from 800 to 620 kg/m3. The thermal conductivity decreased with increasing MSWIFA from 20 to 50%, and stabilizing agent dosage from 0 to 4%. Compared with the collected data from references, a higher compressive strength can be obtained at the same level of thermal conductivity for GFMs synthesized with MSWIFA as a foaming agent. Additionally, the foaming effect of MSWIFA results from the H2 release. The addition of MSWIFA changed both the crystal phase and gel composition, whereas the stabilizing agent dosage had little impact on the phase composition.

Alignment behavior of nerve, vascular, muscle, and intestine cells in two- and three-dimensional strategies.

By harnessing structural hierarchical insights, plausibly simulate better ones imagination to figure out the best choice of methods for reaching out the unprecedented developments of the tissue engineering products as a next level. Constructing a functional tissue that incorporates two-dimensional (2D) or higher dimensions requires overcoming technological or biological limitations in order to orchestrate the structural compilation of one-dimensional and 2D sheets (microstructures) simultaneously (in situ). This approach enables the creation of a layered structure that can be referred to as an ensemble of layers or, after several days of maturation, a direct or indirect joining of layers. Here, we have avoided providing a detailed methodological description of three-dimensional and 2D strategies, except for a few interesting examples that highlight the higher alignment of cells and emphasize rarely remembered facts associated with vascular, peripheral nerve, muscle, and intestine tissues. The effective directionality of cells in conjunction with geometric cues (in the range of micrometers) is well known to affect a variety of cell behaviors. The curvature of a cell's environment is one of the factors that influence the formation of patterns within tissues. The text will cover cell types containing some level of stemness, which will be followed by their consequences for tissue formation. Other important considerations pertain to cytoskeleton traction forces, cell organelle positioning, and cell migration. An overview of cell alignment along with several pivotal molecular and cellular level concepts, such as mechanotransduction, chirality, and curvature of structure effects on cell alignments will be presented. The mechanotransduction term will be used here in the context of the sensing capability that cells show as a result of force-induced changes either at the conformational or the organizational levels, a capability that allows us to modify cell fate by triggering downstream signaling pathways. A discussion of the cells' cytoskeleton and of the stress fibers involvement in altering the cell's circumferential constitution behavior (alignment) based on exposed scaffold radius will be provided. Curvatures with size similarities in the range of cell sizes cause the cell's behavior to act as if it was in an in vivo tissue environment. The revision of the literature, patents, and clinical trials performed for the present study shows that there is a clear need for translational research through the implementation of clinical trial platforms that address the tissue engineering possibilities raised in the current revision. This article is categorized under: Infectious Diseases > Biomedical Engineering Neurological Diseases > Biomedical Engineering Cardiovascular Diseases > Biomedical Engineering.

Diatom community dynamics in a tropical brackish coastal ecosystem from an ecological and biogeochemical perspective: A size-fractionated approach

Diatoms are a major, ubiquitous photosynthetic group representing most aquatic ecosystem’s microalgal communities. The species composition encompasses a wide range of cell sizes. Although cell size is vital in aquatic ecology and biogeochemistry, size-based diatom community studies are sparse, especially in tropical ecosystems. This study assesses the size-fractionated brackish diatom community based on the microscopic cell abundance and carbon-biomass metrics. Despite sufficient nutrient availability, the seasonal and spatial relative proportion of abundance and biomass of the three diatom size fractions declined under high turbidity. It increased under higher light and nutrient availability with lower turbidity. Turbulence was a favorable factor irrespective of the size groups. Light availability, increased nutrients, and lower temperature resulted in a higher contribution from the larger size group to the total diatom carbon biomass. The smaller size group dominance during highly turbid conditions could be attributed to the higher surface-to-volume ratios. The intermediate-size groups thrived under reduced turbidity. Seasonal intra-species size variations reflected changes induced either due to life-cycle stages or environmental stress. The size-based metrics permitted an in-depth understanding of the diatom responses at the community and species level, which could have implications on their ecological and biogeochemical roles in aquatic ecosystems.

Regulatory elements coordinating initiation of chromosome replication to the Escherichia coli cell cycle

Escherichia coli coordinates replication and division cycles by initiating replication at a narrow range of cell sizes. By tracking replisomes in individual cells through thousands of division cycles in wild-type and mutant strains, we were able to compare the relative importance of previously described control systems. We found that accurate triggering of initiation does not require synthesis of new DnaA. The initiation size increased only marginally as DnaA was diluted by growth after dnaA expression had been turned off. This suggests that the conversion of DnaA between its active ATP- and inactive ADP-bound states is more important for initiation size control than the total free concentration of DnaA. In addition, we found that the known ATP/ADP converters DARS and datA compensate for each other, although the removal of them makes the initiation size more sensitive to the concentration of DnaA. Only disruption of the regulatory inactivation of DnaA mechanism had a radical impact on replication initiation. This result was corroborated by the finding that termination of one round of replication correlates with the next initiation at intermediate growth rates, as would be the case if RIDA-mediated conversion from DnaA-ATP to DnaA-ADP abruptly stops at termination and DnaA-ATP starts accumulating.

High Growth Rate of Diatoms Explained by Reduced Carbon Requirement and Low Energy Cost of Silica Deposition.

The rapid growth of diatoms makes them one of the most pervasive and productive types of plankton in the world's ocean, but the physiological basis for their high growth rates remains poorly understood. Here, we evaluate the factors that elevate diatom growth rates, relative to other plankton, using a steady-state metabolic flux model that computes the photosynthetic C source from intracellular light attenuation and the carbon cost of growth from empirical cell C quotas, across a wide range of cell sizes. For both diatoms and other phytoplankton, growth rates decline with increased cell volume, consistent with observations, because the C cost of division increases with size faster than photosynthesis. However, the model predicts overall higher growth rates for diatoms due to reduced C requirements and the low energetic cost of Si deposition. The C savings from the silica frustule are supported by metatranscriptomic data from Tara Oceans, which show that the abundance of transcripts for cytoskeleton components in diatoms is lower than in other phytoplankton. Our results highlight the importance of understanding the origins of phylogenetic differences in cellular C quotas, and suggest that the evolution of silica frustules may play a critical role in the global dominance of marine diatoms. IMPORTANCE This study addresses a longstanding issue regarding diatoms, namely, their fast growth. Diatoms, which broadly are phytoplankton with silica frustules, are the world's most productive microorganisms and dominate in polar and upwelling regions. Their dominance is largely supported by their high growth rate, but the physiological reasoning behind that characteristic has been obscure. In this study, we combine a quantitative model and metatranscriptomic approaches and show that diatoms' low carbon requirements and low energy costs for silica frustule production are the key factors supporting their fast growth. Our study suggests that the effective use of energy-efficient silica as a cellular structure, instead of carbon, enables diatoms to be the most productive organisms in the global ocean.

Design, fabrication, and testing of a water-cooled tungsten-foam high-heat flux plasma-facing module

We present a comprehensive study detailing the design, fabrication and testing a new modular “finger” component, featuring a hexagonal tungsten foam armor tile bonded to the top surface of the water-cooled finger unit. The mechanical, thermal, and particle transport properties of the tungsten foam armor were determined for a wide range of porosity and cell size, and then combined in an equivalent solid material with “effective” properties suitable for large-scale simulations. A series of 3-D multiphysics simulations for coupled thermal and mechanical behavior of the “finger” module are used to optimize the design before fabrication. The simulation results show that, for the expected experimental conditions, a safe range of heat flux and foam porosity is possible for both water-cooling and helium-cooling. Based on these multiphysics simulations, an optimum finger cooling module has been fabricated at Ultramet, Inc. A series of experiments were designed to study the thermomechanical performance of the “finger” unit under steady-state and transient thermal loading at surface heat flux up to 16 MW/m2 in the High Energy Flux Test facility (HEFTY) at UCLA. Testing conditions included low-power, steady-state plasma exposure at 6 MW/m2, followed by severe high heat flux cycles at 16 MW/m2. Results of these tests are explained through comparisons with multiphysics simulations. To eliminate the effects of thermomechanical damage carried out on a module on its thermo-mechanical response on a subsequent test, three different yet identically designed and fabricated finger modules were tested. The results show that the current design is capable of cooling the walls of fusion devices at surface heat flux up to 6 MW/m2 without failure, and that the failure heat flux limit is below 16 MW/m2.

Microwave-assisted polyol liquefication from bamboo for bio-polyurethane foams fabrication

In this study, the bamboo powder was liquified under microwave conditions and utilized as a bio-polyol (B-polyol) to synthesize bio-based polyurethane foam (B-PUf). The NMR spectra and GC/MS results showed that the B-polyol mainly comprised carbon derivatives including sugars, phenolic compounds, and other compounds such as ethers and esters. The morphology of B-PUf showed a heterogeneous with a cell size range of 400 − 600 µm and a density lower than 34 kg/m3. The lignin derivatives in B-polyol contributed significantly to improving the thermal stability of B-PUf with a temperature range of 370 − 800 °C. The blocks of B-PUf with 50 × 50 × 25 mm were prepared and burned for flame retardance assessment. These results obtained from this study allow to explain how bamboo can be used as a great potential alternative to fossil fuel and boost the bio-based content in PU foam materials.

Spatial scales in instream flow modeling: Why and how to use ecologically appropriate resolutions

AbstractThis paper discusses why and how to use ecologically appropriate spatial resolutions (e.g., cell size or range of cell sizes) when modeling instream flow effects on aquatic animals. Resolution is important because relations between habitat and animal habitat use vary with spatial resolution, and different habitat variables may best predict habitat use at different resolutions. Using appropriate resolutions consistently would bring clarity and coherence to how we quantify and model habitat characteristics and habitat use by fish, facilitate the use of standard and more credible measures of habitat preference, incorporate more fisheries knowledge to improve models for different kinds of fish, and avoid well‐known (and perhaps unknown) biases. Doing so involves describing habitat, and habitat use by fish, with spatially explicit measures with clear resolutions; using the same resolution for physical habitat and fish habitat use; selecting that resolution for ecological reasons; and using habitat variables and fish observation methods appropriate for the resolution. The choice of resolution considers factors such as how much space fish use for specific activities and the size of important habitat patches. For drift‐feeders, cell sizes and fish habitat use observations should use a resolution no smaller than feeding territories. Piscivores typically hunt over large areas so should be modeled with larger habitat units. Models of small and less‐mobile organisms (e.g., benthic invertivores) may need fine resolutions to capture the small areas of unusual habitat they depend on. Because of such differences, instream flow studies (like any spatial ecology exercise) should clearly state what resolution(s) they use and why.

Flexible and open-source programs for quantitative image analysis in microbial ecology

Epifluorescence microscopy is an essential tool for obtaining reliable estimates of the abundance of marine microorganisms including viruses. However, computational analysis is required to gain consistent and quantitative data from digital microscopy images. Many imaging programs are proprietary and cost-prohibitive. The currently available free imaging programs are often platform specific and/or lack the flexibility to analyze microscopy images from natural samples, such as the planktonic environment, which can contain challenges such as debris and high background signals. Here we describe two MATLAB-based open-source image analysis programs that work across computer platforms and provide the tools to analyze a range of image types and cell sizes with a user-friendly interface. The Microbial Image Analysis (MiA) program aims to provide flexibility for the selection, identification, and quantification of cells that vary in size and fluorescence intensity within natural microbial communities. The Viral Image Analysis (ViA) program aims to provide an effective means for quantifying viral abundances from epifluorescence images as well as enumerating the intensity of a primary and secondary stain. In this paper, we provide an overview of the functionality of the MiA and ViA programs and highlight specific program features through several microbial image case studies.

Carbon Foams by Solid State Foaming of Short Vermicelli Bonded by Phenol-Formaldehyde for Thermal Insulation and Electromagnetic Interference Shielding

A simple method of production of carbon foams by randomly assembling short vermicelli rods and bonding them using phenol-formaldehyde (PF) followed by foaming in the solid state during carbonization has been reported. The brittle vermicelli becomes ductile in the range of 200–250 °C during carbonization, which facilitates the nucleation and growth of bubbles in the solid state due to the water vapor generated by the -OH condensation of starch. The dense PF coating on the vermicelli surface facilitates the enlargement of cells by restricting the escape of water vapor during the solid state foaming. The dense carbon produced from the PF binds the carbonized vermicelli rods, affording structural integrity and mechanical strength. The foam body consists of open intervermicelli void space and closed cellular pores in the carbonized vermicelli rods. A broad cell size range of 4–142 μm with an average value of 29.2 μm is observed. The density, compressive strength, and thermal conductivity of the carbon foam are modulated in the ranges of 0.30–0.34 g cm–3, 0.63–1.6 MPa, and 0.162–0.222 W m–1 K–1, respectively, by changing the PF solution concentration in the range of 50–90 vol %. The carbon foams exhibit absorption-dominated electromagnetic interference shielding with total shielding effectiveness and specific shielding effectiveness in the ranges of 47.5–65.6 dB and 155.2–192.9 dB cm3 g–1, respectively, for the X band (8.2–12.4 GHz).

Age-related changes of GAD1 mRNA expression in the central inferior colliculus

Encoding sounds with a high degree of temporal precision is an essential task for the inferior colliculus (IC) to perform and maintain the accurate processing of sounds and speech. However, the age-related reduction of GABAergic neurotransmission in the IC interrupts temporal precision and likely contributes to presbycusis. As presbycusis often manifests at high or low frequencies specifically, we sought to determine if the expression of mRNA for glutamic decarboxylase 1 (GAD1) is downregulated non-uniformly across the tonotopic axis or cell size range in the aging IC. Using single molecule in situ fluorescent hybridization across young, middle age and old Fisher Brown Norway rats (an aging model that acquires low frequency presbycusis) we quantified individual GAD1 mRNA in small, medium and large GABAergic cells. Our results demonstrate that small GABAergic cells in low frequency regions had ∼58% less GAD1 in middle age and continued to decline into old age. In contrast, the amount of GAD1 mRNA in large cells in low frequency regions significantly increased with age. As several studies have shown that downregulation of GAD1 decreases the release of GABA, we interpret our results in two ways. First, the onset of presbycusis may be driven by small GABAergic cells downregulating GAD1. Second, as previous studies demonstrate that GAD67 expression is broadly downregulated in the old IC, perhaps the translation of GAD1 to GAD67 is interrupted in large GABAergic IC cells during aging. These results point to a potential genetic mechanism explaining reduced temporal precision in the aging IC, and in turn, presbycusis.