The Ocular Penetration and Intraocular Pressure Lowering Effect of Topical Acetaminophen in the New Zealand White Rabbit.

Purpose: Emerging data suggest that acetaminophen lowers intraocular pressure (IOP) and has the potential to be repurposed as pharmacotherapy to treat open-angle glaucoma. However, pharmacokinetic data are lacking. This study aims to describe the pharmacokinetics of topical acetaminophen and its metabolite [N-arachidonoylaminophenol (AM404)] when administered individually and in combination, and to determine its effect on IOP in the ocular normotensive adult New Zealand White Rabbit (NZWR). Methods: A randomized control trial was conducted using topical 1% acetaminophen and 1% AM404. The study was divided into two sub-studies using both paired-eye and two-eye designs. Results: The mean [95% confidence interval of the mean (95% CI)] concentration of acetaminophen detected in the aqueous humor (AH) was 4.09 ppm (3.18-5.00) at 2 h and 0.92 ppm (0.60-1.24) at 4 h after an immediate dose of topical acetaminophen. The integral IOP, defined as the integral of IOP change from baseline over time, was -5.1 mmHg⋅h (95% CI: -10 to 0.41) for control,-7.5 mmHg⋅h (95% CI: -14 to -1.1) for half-hourly acetaminophen, and -4.4 mmHg⋅h (95% CI: -14 to 5.5) for hourly acetaminophen over a 4-h period. When comparing topical acetaminophen with AM404 dosed half-hourly over a 4-h period, the integral IOP was -2.3 mmHg⋅h (95% CI: -5.9 to 1.3) for control,-2.0 mmHg⋅h (95% CI: -5.6 to 1.7) for AM404, -1.7 mmHg⋅h (95% CI: -4.5 to 1.2) for acetaminophen, and -3.2 mmHg⋅h (95% CI: -5.4 to -0.96) for acetaminophen/AM404 combined. Conclusions: Acetaminophen, but not its metabolite AM404, penetrated the multilayered cornea via passive diffusion in a dose-dependent fashion. There was a nonsignificant tendency to cause a lowering of IOP over the 4-h dosing period with higher AH concentrations of acetaminophen. Topical AM404 did not show a significant IOP-lowering effect.

Review of Binaural Processing With Asymmetrical Hearing Outcomes in Patients With Bilateral Cochlear Implants.

Bilateral cochlear implants (BiCIs) result in several benefits, including improvements in speech understanding in noise and sound source localization. However, the benefit bilateral implants provide among recipients varies considerably across individuals. Here we consider one of the reasons for this variability: difference in hearing function between the two ears, that is, interaural asymmetry. Thus far, investigations of interaural asymmetry have been highly specialized within various research areas. The goal of this review is to integrate these studies in one place, motivating future research in the area of interaural asymmetry. We first consider bottom-up processing, where binaural cues are represented using excitation-inhibition of signals from the left ear and right ear, varying with the location of the sound in space, and represented by the lateral superior olive in the auditory brainstem. We then consider top-down processing via predictive coding, which assumes that perception stems from expectations based on context and prior sensory experience, represented by cascading series of cortical circuits. An internal, perceptual model is maintained and updated in light of incoming sensory input. Together, we hope that this amalgamation of physiological, behavioral, and modeling studies will help bridge gaps in the field of binaural hearing and promote a clearer understanding of the implications of interaural asymmetry for future research on optimal patient interventions.

Chinook salmon depth distributions on the continental shelf are shaped by interactions between location, season, and individual condition.

BACKGROUND: Ecological and physical conditions vary with depth in aquatic ecosystems, resulting in gradients of habitat suitability. Although variation in vertical distributions among individuals provides evidence of habitat selection, it has been challenging to disentangle how processes at multiple spatio-temporal scales shape behaviour. METHODS: We collected thousands of observations of depth from > 300 acoustically tagged adult Chinook salmon Oncorhynchus tshawytscha, spanning multiple seasons and years. We used these data to parameterize a machine-learning model to disentangle the influence of spatial, temporal, and dynamic oceanographic variables while accounting for differences in individual condition and maturation stage. RESULTS: The top performing machine learning model used bathymetric depth ratio (i.e., individual depth relative to seafloor depth) as a response. We found that bathymetry, season, maturation stage, and spatial location most strongly influenced Chinook salmon depth. Chinook salmon bathymetric depth ratios were deepest in shallow water, during winter, and for immature individuals. We also identified non-linear interactions among covariates, resulting in spatially-varying effects of zooplankton concentration, lunar cycle, temperature and oxygen concentration. CONCLUSIONS: Our results suggest Chinook salmon vertical habitat use is a function of ecological interactions, not physiological constraints. Temporal and spatial variation in depth distributions could be used to guide management decisions intended to reduce fishery impacts on Chinook salmon. More generally, our findings demonstrate how complex interactions among bathymetry, seasonality, location, and life history stage regulate vertical habitat selection.

Sequential activity of CA1 hippocampal cells constitutes a temporal memory map for associative learning in mice.

Sequential neural dynamics encoded by time cells play a crucial role in hippocampal function. However, the role of hippocampal sequential neural dynamics in associative learning is an open question. We used two-photon Ca2+ imaging of dorsal CA1 (dCA1) neurons in the stratum pyramidale (SP) in head-fixed mice performing a go-no go associative learning task to investigate how odor valence is temporally encoded in this area of the brain. We found that SP cells responded differentially to the rewarded or unrewarded odor. The stimuli were decoded accurately from the activity of the neuronal ensemble, and accuracy increased substantially as the animal learned to differentiate the stimuli. Decoding the stimulus from individual SP cells responding differentially revealed that decision-making took place at discrete times after stimulus presentation. Lick prediction decoded from the ensemble activity of cells in dCA1 correlated linearly with lick behavior. Our findings indicate that sequential activity of SP cells in dCA1 constitutes a temporal memory map used for decision-making in associative learning. VIDEO ABSTRACT.

Role of Syndiniales parasites in depth-specific networks and carbon flux in the oligotrophic ocean.

Microbial associations that result in phytoplankton mortality are important for carbon transport in the ocean. This includes parasitism, which in microbial food webs is dominated by the marine alveolate group, Syndiniales. Parasites are expected to contribute to carbon recycling via host lysis; however, knowledge on host dynamics and correlation to carbon export remain unclear and limit the inclusion of parasitism in biogeochemical models. We analyzed a 4-year 18S rRNA gene metabarcoding dataset (2016-19), performing network analysis for 12 discrete depths (1-1000 m) to determine Syndiniales-host associations in the seasonally oligotrophic Sargasso Sea. Analogous water column and sediment trap data were included to define environmental drivers of Syndiniales and their correlation with particulate carbon flux (150 m). Syndiniales accounted for 48-74% of network edges, most often associated with Dinophyceae and Arthropoda (mainly copepods) at the surface and Rhizaria (Polycystinea, Acantharea, and RAD-B) in the aphotic zone. Syndiniales were the only eukaryote group to be significantly (and negatively) correlated with particulate carbon flux, indicating their contribution to flux attenuation via remineralization. Examination of Syndiniales amplicons revealed a range of depth patterns, including specific ecological niches and vertical connection among a subset (19%) of the community, the latter implying sinking of parasites (infected hosts or spores) on particles. Our findings elevate the critical role of Syndiniales in marine microbial systems and reveal their potential use as biomarkers for carbon export.

Top-predator recovery abates geomorphic decline of a coastal ecosystem.

The recovery of top predators is thought to have cascading effects on vegetated ecosystems and their geomorphology1,2, but the evidence for this remains correlational and intensely debated3,4. Here we combine observational and experimental data to reveal that recolonization of sea otters in a US estuary generates a trophic cascade that facilitates coastal wetland plant biomass and suppresses the erosion of marsh edges-a process that otherwise leads to the severe loss of habitats and ecosystem services5,6. Monitoring of the Elkhorn Slough estuary over several decades suggested top-down control in the system, because the erosion of salt marsh edges has generally slowed with increasing sea otter abundance, despite the consistently increasing physical stress in the system (that is, nutrient loading, sea-level rise and tidal scour7-9). Predator-exclusion experiments in five marsh creeks revealed that sea otters suppress the abundance of burrowing crabs, a top-down effect that cascades to both increase marsh edge strength and reduce marsh erosion. Multi-creek surveys comparing marsh creeks pre- and post-sea otter colonization confirmed the presence of an interaction between the keystone sea otter, burrowing crabs and marsh creeks, demonstrating the spatial generality of predator control of ecosystem edge processes: densities of burrowing crabs and edge erosion have declined markedly in creeks that have high levels of sea otter recolonization. These results show that trophic downgrading could be a strong but underappreciated contributor to the loss of coastal wetlands, and suggest that restoring top predators can help to re-establish geomorphic stability.

Expressive vocabulary word categories of children who are deaf and hard-of-hearing.

This study investigated the acquisition of early expressive vocabulary among young children who are deaf and hard-of-hearing (DHH; n = 68) using auditory technology (hearing aids and cochlear implants). Parents completed a standardized vocabulary checklist, which allowed analyses of (i) the size of their child's spoken vocabulary; (ii) composition of the expressive lexicon (e.g., parts of speech such as nouns and verbs; semantic categories such as routines and body parts); and (iii) demographic and audiologic factors (e.g., chronologic age, degree of hearing access) potentially associated with these metrics. Young children who are DHH and use auditory technology acquired fewer spoken words than peers with typical hearing (TH) matched for chronologic age but more spoken words than peers with TH matched for listening experience. Action verbs-not nouns-significantly increased the odds of a child who is DHH achieving a vocabulary quotient within the normative range. These findings support the exploration of early expressive vocabulary size and composition-especially the number of active verbs-to guide clinical management and decision-making for young children who are DHH.

Nestin-expressing cells are mitotically active in the mammalian inner ear.

Nestin expression is associated with pluripotency. Growing evidence suggests nestin is involved in hair cell development. The objective of this study was to investigate the morphology and role of nestin-expressing cells residing in the early postnatal murine inner ear. A lineage-tracing nestin reporter mouse line was used to further characterize these cells. Their cochleae and vestibular organs were immunostained and whole-mounted for cell counting. We found Nestin-expressing cells present in low numbers throughout the inner ear. Three morphotypes were observed: bipolar, unipolar, and globular. Mitotic activity was noted in nestin-expressing cells in the cochlea, utricle, saccule, and crista. Nestin-expressing cell characteristics were then observed after hair cell ablation in two mouse models. First, a reporter model demonstrated nestin expression in a significantly higher proportion of hair cells after hair cell ablation than in control cochleae. However, in a lineage tracing nestin reporter mouse, none of the new hair cells which repopulated the organ of Corti after hair cell ablation expressed nestin, nor did the nestin-expressing cells change in morphotype. In conclusion, Nestin-expressing cells were identified in the cochlea and vestibular organs. After hair cell ablation, nestin-expressing cells did not react to the insult. However, a small number of nestin-expressing cells in all inner ear tissues exhibited mitotic activity, supporting progenitor cell potential, though perhaps not involved in hair cell regeneration.

Impact on species' online attention when named after celebrities.

Celebrities can generate substantial attention and influence public interest in species. Using a large-scale examination of publicly available data, we assessed whether species across 6 taxonomic groups received more page views on Wikipedia when the species was named after a celebrity than when it was not. We conducted our analysis for 4 increasingly strict thresholds of how many average daily Wikipedia page views a celebrity had (1, 10, 100, or 1000 views). Overall, we found a high probability (0.96-0.98) that species named after celebrities had more page views than their closest relatives that were not named after celebrities, irrespective of the celebrity threshold. The multiplicative effect on species' page views was larger but more uncertain as celebrity page-view thresholds increased. The range for thresholds of 1 to 1000 was 1.08 (95% credible interval [CI] 1.00-1.18) to 1.76 (95% CI 0.96-2.80), respectively. The hierarchical estimates for the taxa tended to be positive. The strongest effects were for invertebrates, followed by amphibians, reptiles, fish, and mammals, whereas the weakest effect was for birds at lower page-view thresholds. Our results suggest that naming species after celebrities could be particularly significant for those belonging to taxonomic groups that are generally less popular than others (e.g., invertebrates). Celebrities may further influence the effectiveness of this marketing strategy, depending on their likability and connection to the species named after them. Eponyms may serve as a reminder of the disproportionate power dynamics between populations and some namesakes' untenable actions. However, they also provide an opportunity to recognize remarkable individuals and promote equity, inclusivity, and diversity in taxonomic practice. We encourage taxonomists to examine whether naming threatened species after celebrities could affect conservation support, especially for species that are otherwise typically overlooked by the public.

Impacto sobre la atención virtual de una especie si lleva el nombre de una celebridad Resumen Las celebridades pueden generar atención considerable e influir sobre el interés público por las especies. Usamos un análisis a gran escala de datos con disponibilidad pública para evaluar si las especies de seis grupos taxonómicos recibían más visitas en Wikipedia cuando el nombre de la especie provenía del de una celebridad que cuando no. Realizamos nuestro análisis en cuatro umbrales cada vez más estrictos de cuántas visitas diarias en promedio tenía la página de Wikipedia de una celebridad (1, 10, 100 or 1000 visitas). En general, descubrimos una probabilidad alta (0.96­0.98) de que las especies con nombres de celebridades tuvieran más visitas que sus parientes más cercanos que no tenían un nombre así, sin importar el umbral de la celebridad. El efecto multiplicativo sobre las visitas a la página de la especie fue mayor pero más incierto si incrementaba el umbral de visitas de la celebridad. El rango para los umbrales de 1 a 1000 fue de 1.08 (95% intervalo creíble [IC] 1.00­1.18) a 1.76 (95% IC 0.96­2.80) respectivamente. Los estimados jerárquicos para los taxones tuvieron una tendencia positiva. Los efectos más fuertes se presentaron en los invertebrados, seguidos de los anfibios, reptiles, peces y mamíferos, mientras que el efecto más débil fue para las aves en los umbrales de menor número de visitas. Nuestros resultados sugieren que nombrar a una especie con el nombre de una celebridad podría ser particularmente importante para aquellas que pertenecen a grupos taxonómicos que generalmente suelen ser menos populares que otros (invertebrados). Las celebridades podrían influir todavía más en la efectividad de esta estrategia de marketing, dependiendo de su popularidad y la conexión con la especie que lleva su nombre. Los epónimos pueden funcionar como recordatorios de las dinámicas disparejas de poder entre las poblaciones y las acciones indefendibles de algunos homónimos. Sin embargo, los epónimos también proporcionan la oportunidad para reconocer individuos destacados y promover la equidad, inclusividad y diversidad en la práctica taxonómica. Alentamos a que los taxónomos analicen si nombrar a una especie amenazada con el nombre de una celebridad podría afectar el apoyo a su conservación, especialmente para las especies que de otra manera suelen ser ignoradas por el público.

Fiber chromatographic enabled process intensification increases monoclonal antibody product yield.

The most straightforward method to increase monoclonal antibody (mAb) product yield is to complete the purification process in less steps. Here, three different fiber chromatographic devices were implemented using a holistic approach to intensify the mAb purification process and increase yield. Fiber protein A (proA) chromatography was first investigated, but traditional depth filtration was not sufficient in reducing the contaminant load as the fiber proA device prematurely fouled. Further experimentation revealed that chromatin aggregates were the most likely reason for the fiber fouling. To reduce levels of chromatin aggregates, a chromatographic clarification device (CCD) was incorporated into the process, resulting in single-stage clarification of harvested cell culture fluid and reduction of DNA levels. The CCD clarified pool was then successfully processed through the fiber proA device, fully realizing the productivity gains that the fiber technology offers. After the proA and viral inactivation neutralization (VIN) hold step, the purification process was further intensified using a novel single-use fiber-based polishing anion exchange (AEX) material that is capable of binding both soluble and insoluble contaminants. The three-stage fiber chromatographic purification process was compared to a legacy five-step process of dual-stage depth filtration, bead-based proA chromatography, post-VIN depth filtration, and bead-based AEX chromatography. The overall yield from the five-step process was 60%, while the fiber chromatographic-enabled intensified process had an overall yield of 70%. The impurity clearance of DNA and host cell protein (HCP) for both processes were within the regulatory specification (<100 ppm HCP, <1 ppb DNA). For the harvest of a 2000 L cell culture, the intensified process is expected to increase productivity by 2.5-fold at clarification, 50-fold at the proA step, and 1.6-fold in polishing. Relative to the legacy process, the intensified process would reduce buffer use by 1088 L and decrease overall process product mass intensity by 12.6%.

The Role of the Gut Microbiome in Cancer: A Review, With Special Focus on Colorectal Neoplasia and Clostridioides difficile.

The gut microbiome has coevolved with humans to aid in physiologic functions and prevent disease. An increasing prevalence of gut dysbiosis in modern society exists and has strong linkages to multiple disease processes common in the developed world. Mechanisms for microbiome-human interactions that impact host homeostasis include bacterial metabolite/toxin production, biofilm formation with mucous layer infiltration, and host immune system modulation. Most of this crosstalk occurs at the epithelial layer of the gut, and as such the role of these interactions in the induction of colorectal cancer-a highly prevalent disease globally and one undergoing significant epidemiologic shifts-is under increasing scrutiny. Although multiple individual gut bacteria have been hypothesized as possible driver organisms in the oncogenic process, no bacterium has been definitively identified as a causal agent of colorectal cancer, suggesting that host lifestyle factors, microbiome community interactions, and the mucosal and/or systemic immune response may play a critical role in the process. Recent evidence has emerged implicating the ubiquitous human pathogen Clostridioides difficile as a possible promoter of colorectal cancer through chronic toxin-mediated cellular changes. Although much remains to be defined regarding the natural history of infections caused by this pathogen and its potential for oncogenesis, it provides a strong model for the role of both individual bacteria and of the gut microbial community as a whole in the development of colorectal cancer.

Single-fly assemblies fill major phylogenomic gaps across the Drosophilidae Tree of Life.

Long-read sequencing is driving rapid progress in genome assembly across all major groups of life, including species of the family Drosophilidae, a longtime model system for genetics, genomics, and evolution. We previously developed a cost-effective hybrid Oxford Nanopore (ONT) long-read and Illumina short-read sequencing approach and used it to assemble 101 drosophilid genomes from laboratory cultures, greatly increasing the number of genome assemblies for this taxonomic group. The next major challenge is to address the laboratory culture bias in taxon sampling by sequencing genomes of species that cannot easily be reared in the lab. Here, we build upon our previous methods to perform amplification-free ONT sequencing of single wild flies obtained either directly from the field or from ethanol-preserved specimens in museum collections, greatly improving the representation of lesser studied drosophilid taxa in whole-genome data. Using Illumina Novaseq X Plus and ONT P2 sequencers with R10.4.1 chemistry, we set a new benchmark for inexpensive hybrid genome assembly at US $150 per genome while assembling genomes from as little as 35 ng of genomic DNA from a single fly. We present 183 new genome assemblies for 179 species as a resource for drosophilid systematics, phylogenetics, and comparative genomics. Of these genomes, 62 are from pooled lab strains and 121 from single adult flies. Despite the sample limitations of working with small insects, most single-fly diploid assemblies are comparable in contiguity (>1Mb contig N50), completeness (>98% complete dipteran BUSCOs), and accuracy (>QV40 genome-wide with ONT R10.4.1) to assemblies from inbred lines. We present a well-resolved multi-locus phylogeny for 360 drosophilid and 4 outgroup species encompassing all publicly available (as of August 2023) genomes for this group. Finally, we present a Progressive Cactus whole-genome, reference-free alignment built from a subset of 298 suitably high-quality drosophilid genomes. The new assemblies and alignment, along with updated laboratory protocols and computational pipelines, are released as an open resource and as a tool for studying evolution at the scale of an entire insect family.

Species redistribution creates unequal outcomes for multispecies fisheries under projected climate change.

Climate change drives species distribution shifts, affecting the availability of resources people rely upon for food and livelihoods. These impacts are complex, manifest at local scales, and have diverse effects across multiple species. However, for wild capture fisheries, current understanding is dominated by predictions for individual species at coarse spatial scales. We show that species-specific responses to localized environmental changes will alter the collection of co-occurring species within established fishing footprints along the U.S. West Coast. We demonstrate that availability of the most economically valuable, primary target species is highly likely to decline coastwide in response to warming and reduced oxygen concentrations, while availability of the most abundant, secondary target species will potentially increase. A spatial reshuffling of primary and secondary target species suggests regionally heterogeneous opportunities for fishers to adapt by changing where or what they fish. Developing foresight into the collective responses of species at local scales will enable more effective and tangible adaptation pathways for fishing communities.

Web-based psychoacoustics of binaural hearing: Two validation experiments.

Web-based testing is an appealing option for expanding psychoacoustics research outside laboratory environments due to its simple logistics. For example, research participants partake in listening tasks using their own computer and audio hardware and can participate in a comfortable environment of their choice at their own pace. However, it is unknown how deviations from conventional in-lab testing affect data quality, particularly in binaural hearing tasks that traditionally require highly precise audio presentation. Here, we used an online platform to replicate two published in-lab experiments: lateralization to interaural time and level differences (ITD and ILD, experiment I) and dichotic and contralateral unmasking of speech (experiment II) in normal-hearing (NH) young adults. Lateralization data collected online were strikingly similar to in-lab results. Likewise, the amount of unmasking measured online and in-lab differed by less than 1 dB, although online participants demonstrated higher speech reception thresholds overall than those tested in-lab by up to ∼7 dB. Results from online participants who completed a hearing screening versus those who self-reported NH did not differ significantly. We conclude that web-based psychoacoustics testing is a viable option for assessing binaural hearing abilities among young NH adults and discuss important considerations for online study design.

Ecology and the Origin of Nonephemeral Species.

AbstractResearch over the past three decades has shown that ecology-based extrinsic reproductive barriers can rapidly arise to generate incipient species-but such barriers can also rapidly dissolve when environments change, resulting in incipient species collapse. Understanding the evolution of unconditional, "intrinsic" reproductive barriers is therefore important for understanding the longer-term buildup of biodiversity. In this article, we consider ecology's role in the evolution of intrinsic reproductive isolation. We suggest that this topic has fallen into a gap between disciplines: while evolutionary ecologists have traditionally focused on the rapid evolution of extrinsic isolation between co-occurring ecotypes, speciation geneticists studying intrinsic isolation in other taxa have devoted little attention to the ecological context in which it evolves. We argue that for evolutionary ecology to close this gap, the field will have to expand its focus beyond rapid adaptation and its traditional model systems. Synthesizing data from several subfields, we present circumstantial evidence for and against different forms of ecological adaptation as promoters of intrinsic isolation and discuss alternative forces that may be significant. We conclude by outlining complementary approaches that can better address the role of ecology in the evolution of nonephemeral reproductive barriers and, by extension, less ephemeral species.

Sexual dimorphism in the response to chronic circadian misalignment on a high-fat diet.

Longitudinal studies associate shiftwork with cardiometabolic disorders but do not establish causation or elucidate mechanisms of disease. We developed a mouse model based on shiftwork schedules to study circadian misalignment in both sexes. Behavioral and transcriptional rhythmicity were preserved in female mice despite exposure to misalignment. Females were protected from the cardiometabolic impact of circadian misalignment on a high-fat diet seen in males. The liver transcriptome and proteome revealed discordant pathway perturbations between the sexes. Tissue-level changes were accompanied by gut microbiome dysbiosis only in male mice, biasing toward increased potential for diabetogenic branched chain amino acid production. Antibiotic ablation of the gut microbiota diminished the impact of misalignment. In the United Kingdom Biobank, females showed stronger circadian rhythmicity in activity and a lower incidence of metabolic syndrome than males among job-matched shiftworkers. Thus, we show that female mice are more resilient than males to chronic circadian misalignment and that these differences are conserved in humans.

Microphone array analysis for simultaneous condition detection, localization, and classification in a pipe.

An acoustic method for simultaneous condition detection, localization, and classification in air-filled pipes is proposed. The contribution of this work is threefold: (1) a microphone array is used to extend the usable acoustic frequency range to estimate the reflection coefficient from blockages and lateral connections; (2) a robust regularization method of sparse representation based on a wavelet basis function is adapted to reduce the background noise in acoustical data; and (3) the wavelet components are used to localize and classify the condition of the pipe. The microphone array and sparse representation method enhance the acoustical signal reflected from blockages and lateral connections and suppress unwanted higher-order modes. Based on the sparse representation results, higher-level wavelet functions representing the impulse response are used to localize the position of the sensor corresponding to a blockage or lateral connection with higher spatial resolution. It is shown that the wavelet components can be used to train and to test a support vector machine (SVM) classifier for the condition identification more accurately than with a time domain SVM classifier. This work paves the way for the development of simultaneous condition classification and localization methods to be deployed on autonomous robots working in buried pipes.

Single-stage chromatographic clarification of Chinese Hamster Ovary cell harvest reduces cost of protein production.

A single-stage clarification was developed using a single-use chromatographic clarification device (CCD) to recover a recombinant protein from Chinese Hamster Ovary (CHO) harvest cell culture fluid (HCCF). Clarification of a CHO HCCF is a complex and costly process, involving multiple stages of centrifugation and/or depth filtration to remove cells and debris and to reduce process-related impurities such as host cell protein (HCP), nucleic acids, and lipids. When using depth filtration, the filter train consists of multiple filters of varying ratios, layers, pore sizes, and adsorptive properties. The depth filters, in combination with a 0.2-micron membrane filter, clarify the HCCF based on size-exclusion, adsorptive, and charge-based mechanisms, and provide robust bioburden control. Each stage of the clarification process requires time, labor, and utilities, with product loss at each step. Here, use of the 3M™ Harvest RC Chromatographic Clarifier, a single-stage CCD, is identified as an alternative strategy to a three-stage filtration train. The CCD results in less overall filter area, less volume for flushing, and higher yield. Using bioprocess cost modeling, the single-stage clarification process was compared to a three-stage filtration process. By compressing the CHO HCCF clarification to a single chromatographic stage, the overall cost of the clarification process was reduced by 17%-30%, depending on bioreactor scale. The main drivers for the cost reduction were reduced total filtration area, labor, time, and utilities. The benefits of the single-stage harvest process extended throughout the downstream process, resulting in a 25% relative increase in cumulative yield with comparable impurity clearance.

Digest: The non-redundancy of non-ephemeral reproductive isolation.

What factors determine the stability of intrinsic reproductive barriers in the face of hybridization? In a set of theoretical analyses, Xiong and Mallet (2022) show that intrinsic incompatibilities are more prone to collapse when the incompatible genotypes encode biological functions with redundant genetic bases. These findings suggest that stable reproductive barriers often will be based on non-redundant genetic complexes that evolve among diverging lineages.

The role of divergent ecological adaptation during allopatric speciation in vertebrates.

After decades of debate, biologists today largely agree that most speciation events require an allopatric phase (that is, geographic separation), but the role of adaptive ecological divergence during this critical period is still unknown. Here, we show that relatively few allopatric pairs of birds, mammals, or amphibians exhibit trait differences consistent with models of divergent adaptation in each of many ecologically relevant traits. By fitting new evolutionary models to numerous sets of sister-pair trait differences, we find that speciating and recently speciated allopatric taxa seem to overwhelmingly evolve under similar rather than divergent macro-selective pressures. This contradicts the classical view of divergent adaptation as a prominent driver of the early stages of speciation and helps synthesize two historical controversies regarding the ecology and geography of species formation.