Biology subjects

Xu, P.

Publications and source records attributed to Xu, P..

At least 217 records · Page 12Linked to original sources

bioRxiv2020

Intracellular accumulation and secretion of hydrophobin-enriched vesicles aid the rapid sporulation of molds

Fungi can rapidly produce large amounts of spores suitable for aerial dispersal. The hydrophobicity of spores is provided by the unique amphiphilic and superior surface-active proteins - hydrophobins (HFBs) - that self-assemble at hydrophobic/hydrophilic interfaces and thus change surface properties. Using the HFB-enriched mold Trichoderma and the HFB-free yeast Pichia pastoris, we revealed a distinctive HFB secretory pathway that includes an intracellular accumulation of HFBs in lipid bodies (LBs) that can internalize in vacuoles. The resulting vacuolar multicisternal structures (VMS) are stabilized by HFB layers that line up on their surfaces. These HFB-enriched VMSs can move to the periplasm for secretion or become fused in large tonoplast-like organelles. The latter contributes to the maintenance of turgor pressure required for the erection of sporogenic structures and rapid HFB secretion by squeezing out periplasmic VMSs through the cell wall. Thus, HFBs are essential accessory proteins for the development of aerial hyphae and colony architecture.

microbiology↗

bioRxiv2020

Manganese depletion leads to multisystem changes in the transcriptome of the opportunistic pathogen Streptococcus sanguinis

1Streptococcus sanguinis is a primary tooth colonizer and is typically considered beneficial due to its antagonistic relationship with the cariogenic pathogen Streptococcus mutans. However, S. sanguinis can also act as an opportunistic pathogen should it enter the bloodstream and colonize a damaged heart valve, leading to infective endocarditis. Studies have implicated manganese acquisition as an important virulence determinant in streptococcal endocarditis. A knockout mutant lacking the primary manganese import system in S. sanguinis, SsaACB, is severely attenuated for virulence in an in vivo rabbit model. Manganese is a known cofactor for several important enzymes in S. sanguinis, including superoxide dismutase, SodA, and the aerobic ribonucleotide reductase, NrdEF. To determine the effect of manganese depletion on S. sanguinis, we performed transcriptomic analysis on a {Delta}ssaACB mutant grown in aerobic fermentor conditions after the addition of the metal chelator EDTA. Despite the broad specificity of EDTA, analysis of cellular metal content revealed a decrease in manganese, but not in other metals, that coincided with a drop in growth rate. Subsequent supplementation with manganese, but not iron, zinc, or magnesium, restored growth in the fermentor post-EDTA. Reduced activity of Mn-dependent SodA and NrdEF likely contributed to the decreased growth rate post-EDTA, but did not appear entirely responsible. With the exception of the Dps-like peroxide resistance gene, dpr, manganese depletion did not induce stress response systems. By comparing the transcriptome of {Delta}ssaACB cells pre- and post-EDTA, we determined that manganese deprivation led to altered expression of diverse systems, including ethanolamine utilization, CRISPR/Cas, and a type IV pilus. Manganese depletion also led to an apparent induction of carbon catabolite repression in a glucose-independent manner. The combined results suggest that manganese limitation produces effects in S. sanguinis that are diverse and complex, with no single protein or system appearing entirely responsible for the observed growth rate decrease. This study provides further evidence for the importance of this trace element in streptococcal biology. Future studies will focus on determining mechanisms for regulation, as the multitude of changes observed in this study indicate that multiple regulators may respond to manganese levels.

microbiology↗

bioRxiv2020

A fluorescent L-2-hydroxyglutarate biosensor

L-2-Hydroxyglutarate (L-2-HG) plays important roles in diverse physiological processes, such as carbon starvation response, tumorigenesis, and hypoxic adaptation. Despite its importance and intensively studied metabolism, regulation of L-2-HG metabolism remains poorly understood and a regulator specifically responded to L-2-HG has never been identified. Based on the genomic neighborhood analysis of the gene encoding L-2-HG oxidase (LhgO), LhgR, which represses the transcription of lhgO, was identified in Pseudomonas putida W619 in this study. LhgR was demonstrated to recognize L-2-HG as its specific effector molecule, and this allosteric transcription factor was then used as a biorecognition element for construction of L-2-HG-sensing FRET sensor. The newly developed L-2-HG sensor can conveniently monitor the concentrations of L-2-HG in various biological samples. In addition to bacterial L-2-HG generation during carbon starvation, biological functions of the L-2-HG dehydrogenase and hypoxia induced L-2-HG accumulation were also revealed by using the L-2-HG sensor in human cells.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biochemistry↗

bioRxiv2020

Mass-spectrometry-based near complete draft of the Saccharomyces cerevisiae proteome

Proteomics approaches designed to catalogue all open reading frames (ORFs) under a defined set of growth conditions of an organism have flourished in recent years. However, no proteome has been sequenced completely so far. Here we generate the largest yeast proteome dataset, including 5610 identified proteins using a strategy based on optimized sample preparation and high-resolution mass spectrometry. Among the 5610 identified proteins, 94.1% are core proteins, which achieves near complete coverage of the yeast ORFs. Comprehensive analysis of missing proteins in our dataset indicate that the MS-based proteome coverage has reached the ceiling. A review of protein abundance shows that our proteome encompasses a uniquely broad dynamic range. Additionally, these values highly correlate with mRNA abundance, implying a high level of accuracy, sensitivity and precision. We present examples of how the data could be used, including re-annotating gene localization, providing expression evidence of pseudogenes. Our near complete yeast proteome dataset will be a useful and important resource for further systematic studies.

biochemistry↗

bioRxiv2020

The Axenfeld-Rieger syndrome gene FOXC1 contributes to left-right patterning

Normal body situs requires precise spatiotemporal expression of the Nodal-Lefty-Pitx2 cascade in the lateral plate mesoderm. The ultimate output of this patterning is establishment of the left-right axis, which provides vital cues for correct organ formation and function. Mutations, deletions and duplications in PITX2 and FOXC1 lead to the rare genetic disease Axenfeld-Rieger syndrome (ARS). While situs defects are not a recognised feature of ARS, partial penetrance of cardiac septal defects and valve incompetence is observed; both of these congenital heart defects (CHDs) also occur following disruption of left-right patterning. Here we investigated whether foxc1 genes have a critical role in specifying organ situs. We demonstrate that CRISPR/Cas9 generated mutants for the zebrafish paralogs foxc1a and foxc1b recapitulate ARS phenotypes including craniofacial dysmorphism, hydrocephalus and intracranial haemorrhage. Furthermore, foxc1a-/-; foxc1b-/- mutant animals display cardiac and gut situs defects. Modelling FOXC1 duplication by transient mRNA overexpression revealed that increased foxc1 dosage also results in organ situs defects. Analysis of known left-right patterning genes revealed a loss in expression of the NODAL antagonist lefty2 in the lateral plate mesoderm. Consistently, LEFTY2 mutations are known to cause human cardiac situs defects. Our data reveal a novel role for the forkhead-box transcription factor foxc1 in patterning of the left-right axis, and provide a plausible mechanism for the incidence of congenital heart defects in Axenfeld-Rieger syndrome patients. Author SummaryThis manuscript investigates the functional consequences of abrogating the activity of Foxc1 (Forkhead Box C1). We demonstrate that loss of zebrafish foxc1a and foxc1b results in phenotypes that resemble human patients with deletions in the FOXC1 locus. Notably, such phenotypes include alterations to the morphology of the heart. Investigations into the mechanisms underlying this phenotype led to the discovery that Foxc1 functions as a regulator of left-right patterning. Most components of left-right specification function normally in foxc1a/b mutants, but there is a pronounced loss of lefty2, a known inhibitor of Nodal signaling. This supports a model in which Foxc1 regulates situs of the heart via the regulation of Lefty2.

genetics↗

bioRxiv2020

Integrative proteomics reveals principles of dynamic phospho-signaling networks in human erythropoiesis

Human erythropoiesis is exquisitely controlled at multiple levels and its dysregulation leads to numerous human diseases. Despite many functional studies focused on classical regulators, we lack a global, system-wide understanding of post-translational mechanisms coordinating erythroid maturation. Using the latest advances in mass spectrometry (MS)-based proteomics we comprehensively investigate the dynamics of protein and post-translational regulation of in vitro reconstituted CD34+ HSPC-derived erythropoiesis. This quantifies and dynamically tracks 7,400 proteins and 27,000 phosphorylation sites. Our data reveals differential temporal protein expression encompassing most protein classes and numerous post-translational regulatory cascades. Drastic cell surface remodeling across erythropoiesis include numerous orchestrated changes in solute carriers, providing new stage-specific markers. The dynamic phosphoproteomes combined with a kinome-targeting CRISPR/Cas9 screen reveal coordinated networks of erythropoietic kinases and downregulation of MAPK signaling subsequent to c-Kit attenuation as key drivers of maturation. Our global view of erythropoiesis establishes a central role of post-translational regulation in terminal differentiation.

systems biology↗

bioRxiv2020

Higher prevalence of Bacteroides fragilis in Crohn's disease exacerbations and strain-dependent increase of epithelial resistance

Bacteroides fragilis has previously been linked to Crohns disease (CD) exacerbations, but results are inconsistent and underlying mechanisms unknown. This study investigates the epidemiology of B. fragilis and its virulence factors bft (enterotoxin) and ubiquitin among 181 CD patients and the impact on the intestinal epithelial barrier in vitro. The prevalence of B. fragilis was significantly higher in active (n=69/88, 78.4%) as compared to remissive (n=58/93, 62.4%, p=0.018) CD patients. Moreover, B. fragilis was associated with intestinal strictures. Interestingly, the intestinal barrier function, as examined by transepithelial electrical resistance (TEER) measurements of Caco-2 monolayers, improved when exposed to secretomes of bft-positive (increased TEER [~]160%, p<0.001) but not when exposed to bft- negative strains. Whole metagenome sequencing and metabolomics, respectively, identified 19 coding sequences and two metabolites that discriminated TEER-increasing from non-TEER-increasing strains. This study revealed a higher B. fragilis prevalence during exacerbation. Surprisingly, bft-positive secretomes improved epithelial resistance.

microbiology↗

bioRxiv2020

Coupling metabolic addiction with negative autoregulation to improve strain stability and pathway yield

Metabolic addiction, an organism that is metabolically addicted with a compound to maintain its growth fitness, is an underexplored area in metabolic engineering. Microbes with heavily engineered pathways or genetic circuits tend to experience metabolic burden leading to degenerated or abortive production phenotype during long-term cultivation or scale-up. A promising solution to combat metabolic instability is to tie up the end-product with an intermediary metabolite that is essential to the growth of the producing host. Here we present a simple strategy to improve both metabolic stability and pathway yield by coupling chemical addiction with negative autoregulatory genetic circuits. Naringenin and lipids compete for the same precursor with inversed pathway yield in oleaginous yeast. Negative autoregulation of the lipogenic pathways, enabled by CRISPRi and fatty acid-inducible promoters, repartitioned malonyl-CoA to favor flavonoid synthesis and increased naringenin production by 74.8%. With flavonoid-sensing hybrid promoters to control leucine synthesis, this flavonoid addiction phenotype confers a selective growth advantage to the naringenin-producing cell. The engineered yeast persisted 90.9% of naringenin titer up to 324 generations. Cells without flavonoid addiction regained growth fitness but lost 94.5% of the naringenin titer after cell passage beyond 300 generations. Metabolic addiction and negative autoregulation may be generalized as basic tools to eliminate metabolic heterogeneity, improve strain stability and pathway yield.

synthetic biology↗

bioRxiv2020

Optimizing mevalonate pathway for squalene production in Yarrowia lipolytica

Squalene is the gateway molecule for triterpene-based natural products and steroids-based pharmaceuticals. As a super lubricant, it has been used widely in health care industry due to its skin compatibility and thermostability. Squalene is traditionally sourced from shark-hunting or oil plant extraction, which is cost-prohibitive and not sustainable. Reconstitution of squalene biosynthetic pathway in microbial hosts is considered as a promising alternative for cost-efficient and scalable synthesis of squalene. In this work, we reported the engineering of the oleaginous yeast, Y. lipolytica, as a potential host for squalene production. We systematically identified the bottleneck of the pathway and discovered that the native HMG-CoA reductase led to the highest squalene improvement. With the recycling of NADPH from the mannitol cycle, the engineered strain produced about 180.3 mg/l and 188.2 mg/L squalene from glucose or acetate minimal media, respectively. By optimizing the C/N ratio, controlling the media pH and mitigating the acetyl-CoA flux competition from lipogenesis, the engineered strain produced about 502.7 mg/L squalene in shake flaks, a 28-fold increase compared to the parental strain (17.2 mg/L). We also profiled the metabolic byproducts citric acid and mannitol level and observed that they are reincorporated into cell metabolism at the late stage of fermentation. This work may serve as a baseline to harness Y. lipolytica as an oleaginous cell factory for production of squalene or terpene-based chemicals.

bioengineering↗

bioRxiv2020

Engineering Yarrowia lipolytica as a chassis for de novo synthesis of aromatic-derived natural products and chemicals

AbstractsYarrowia lipolytica is a novel microbial chassis to upgrade renewable low-cost carbon feedstocks to high-value commodity chemicals and natural products. In this work, we systematically characterized and removed the rate-limiting steps of the shikimate pathway and achieved de novo synthesis of five aromatic chemicals in Y. lipolytica. We determined that eliminating amino acids formation and engineering feedback-insensitive DAHP synthases are critical steps to mitigate precursor competition and relieve the feedback regulation of shikimate pathway. Further overexpression of heterologous phosphoketolase and deletion of pyruvate kinase provided a sustained metabolic driving force that channels E4P (erythrose 4-phosphate) and PEP (phosphoenolpyruvate) precursors through the shikimate pathway. Precursor competing pathways and byproduct formation pathways were also blocked by inactivating chromosomal genes. To demonstrate the utility of our engineered chassis strain, three natural products, 2-phenylethanol (2-PE), p-coumaric acid and violacein, which were derived from phenylalanine, tyrosine and tryptophan, respectively, were chosen to test the chassis performance. We obtained 2426.22 {+/-} 48.33 mg/L of 2-PE, 593.53 {+/-} 28.75 mg/L of p-coumaric acid, 12.67 {+/-} 2.23 mg/L of resveratrol, 366.30 {+/-} 28.99 mg/L of violacein and 55.12 {+/-} 2.81 mg/L of deoxyviolacein from glucose in shake flask. The 2-PE production represents a 286-fold increase over the initial strain (8.48 {+/-} 0.50 mg/L). Specifically, we obtained the highest 2-PE, violacein and deoxyviolacein titer ever reported from the de novo shikimate pathway in yeast. These results set up a new stage of engineering Y. lipolytica as a sustainable biorefinery chassis strain for de novo synthesis of aromatic compounds with economic values.

synthetic biology↗

bioRxiv2020

Characterization of Met25 as a Color Associated Genetic Market in Yarrowia lipolytica

Yarrowia lipolytica offers an ideal host for biosynthesis of high value natural products and oleochemicals through metabolic engineering despite being restricted to a limited number of selective markers, and counter-selection achieved primarily with URA3. In this work, we investigate MET25, a locus of sulfide housekeeping within the cell, to be exploited as a standard genetic marker. Divalent lead supplemented in media induces lead sulfide (PbS) aggregation in MET25-deficient cells such that deficient cells grow brown/black, and cells with functional copies of MET25 grow white. Loss of MET25 did not induce strict auxotrophic requirements for methionine in Y. lipolytica, indicating MET25 deficiency could be rescued by alternative pathways. Plasmid and chromosomal-based complementation of MET25 deficient cells on a double layer agar plate with nutrient gradients demonstrates delayed phenotype (white morphology) restoration, indicating post-transcriptional feedback regulation of methionine biosynthesis in this yeast. MET25 deficient Y. lipolytica could be used as an efficient whole-cell lead sensor with detection limit as low as 10 ppm of lead in drinking water. We further tested whether MET25 deficiency can be exploited to confer resistance to methyl-mercury through chemical neutralization and detoxification. Kinetic growth curves of wild type and MET25-deficient cells were obtained under varying concentrations of methylmercury and cellular toxicity to methyl mercury was calculated from the Hill equation. Our results indicate that methylmecury may not be used as the counter-selectable marker due to insignificant changes of growth fitness. This work demonstrates the utility of using MET25 as a sensitive lead sensor and the challenges of using MET25 as a counter-selectable genetic marker, as well as the complex regulation of methionine biosynthesis in Y. lipolyitca, which may shed lights for us to develop valuable biotechnological applications centering around the sulfur house-keeping metabolism of the nonconventional yeast.

microbiology↗

bioRxiv2020

DeepDigest: prediction of protein proteolytic digestion with deep learning

In shotgun proteomics, it is essential to accurately determine the proteolytic products of each protein in the sample for subsequent identification and quantification, because these proteolytic products are usually taken as the surrogates of their parent proteins in the further data analysis. However, systematical studies about the commonly used proteases in proteomics research are insufficient, and there is a lack of easy-to-use tools to predict the digestibilities of these proteolytic products. Here, we propose a novel sequence-based deep learning model - DeepDigest, which integrates convolutional neural networks and long-short term memory networks for digestibility prediction of peptides. DeepDigest can predict the proteolytic cleavage sites for eight popular proteases including trypsin, ArgC, chymotrypsin, GluC, LysC, AspN, LysN and LysargiNase. Compared with traditional machine learning algorithms, DeepDigest showed superior performance for all the eight proteases on a variety of datasets. Besides, some interesting characteristics of different proteases were revealed and discussed.

bioinformatics↗

bioRxiv2020

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

There are two Fe-uptake strategies for maintaining Fe homeostasis in plants. As a special graminaceous plant, rice applies both strategies. However, it remains unclear how these two strategies are regulated in rice. IRON-RELATED BHLH TRANSCRIPTION FACTOR 2 (OsIRO2) is critical for regulating Fe uptake in rice. In this study, we identified an interacting partner of OsIRO2, Oryza sativa FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT), which encodes a bHLH transcription factor. The OsIRO2 protein is localized in the cytoplasm and nucleus, but OsFIT facilitates the accumulation of OsIRO2 in the nucleus. Loss-of-function mutations to OsFIT result in decreased Fe accumulation, severe Fe-deficiency symptoms, and disrupted expression of Fe-uptake genes. In contrast, OsFIT overexpression promotes Fe accumulation and the expression of Fe-uptake genes. Genetic analyses indicated that OsFIT and OsIRO2 function in the same genetic node. Further analysis suggested that OsFIT and OsIRO2 form a functional transcription activation complex to initiate the expression of Fe-uptake genes. Our findings provide a mechanism understanding of how rice maintains Fe homeostasis. One-sentence summaryOsFIT interacts with and facilitates the accumulation of OsIRO2 in the nucleus where the OsFIT-OsIRO2 transcription complex initiates the transcription of Fe deficiency responsive genes.

plant biology↗

bioRxiv2020

Dynamics of microbial competition, commensalism and cooperation and its implications for coculture and microbiome engineering

Microbial consortium is a complex adaptive system with higher order dynamic characteristics that are not present by individual members. To accurately predict the social interactions, we formulate a set of unstructured kinetic models to quantitatively capture the dynamic interactions of multiple microbial species. By introducing an interaction coefficient, we analytically derived the steady state solutions for the interacting species and the substrate profile in the chemostat. We analyzed the stability of the possible co-existing states defined by competition, parasitism, amensalism, commensalism and cooperation. Our model predicts that only parasitism, commensalism and cooperation could lead to stable co-existing state. We also determined the optimal social interaction criteria of microbial coculture with sequential metabolic reactions compartmentalized into two distinct species. Coupled with Luedeking-Piret and Michaelis-Menten equations, accumulation of metabolic intermediates in one species and formation of end-product in another species could be derived and assessed. We discovered that parasitism consortia disfavor the bioconversion of intermediate to final product; and commensalism consortia could efficiently convert metabolic intermediates to final product and maintain metabolic homeostasis with a broad range of operational conditions (i.e., dilution rates); whereas cooperative consortia leads to highly nonlinear pattern of precursor accumulation and end-product formation. The underlying dynamics and emergent properties of microbial consortia may provide critical knowledge for us to engineer efficient bioconversion process, deliver effective gut therapeutics as well as elucidate probiotic-pathogen interactions in general.

microbiology↗

bioRxiv2020

Cumulus cell acetyl-CoA metabolism from acetate is associated with maternal age but only partially with oocyte maturity

Cumulus cell (CC) clumps that associate with oocytes provide the oocytes with growth and signaling factors. Thus, the metabolism of the CCs may influence oocyte function and CC metabolism may be predictive of oocyte competence for in vitro fertilization. CCs are thought to be highly glycolytic but data on other potential carbon substrates are lacking in humans. This was a prospective and blinded cohort study that was designed to examine the substrate utilization of CCs by age and oocyte competence. Individual sets of CC clumps from participants were removed after oocyte retrieval procedure, incubated with stable isotope labeled substrates, and analyzed using liquid chromatography-high resolution mass spectrometry (LC-HRMS) for isotopologue enrichment of major metabolic intermediates, including acetyl-CoA. The acyl-chain of acetyl-CoA contains 2 carbons that can be derived from 13C-labeled substrates resulting in a M+2 isotopologue that contains 2 13C atoms. Comparing the fate of three major carbon sources, mean enrichment of M+2 acetyl-CoA (mean, standard deviation) was for glucose (3.6, 7.7), for glutamine (9.4, 6.2), and for acetate (20.7, 13.9). Due to this unexpected high and variable labeling from acetate, we then examined acetyl-CoA mean % enrichment from acetate of in 278 CCs from 21 women [≤]34 (49.06, 12.73) decreased with age compared to 124 CCs from 10 women >34 (43.48, 16.20) (p=0.0004, t test). The CCs associated with the immature prophase I oocytes had significantly lower enrichment in M+2 acetyl CoA compared to the CCs associated with the metaphase I and metaphase II oocytes (difference: -6.02, CI: -1.74,-13.79, p=0.013). Acetate metabolism in individual CC clumps was positively correlated with oocyte maturity and decreased with maternal age. These findings indicate that CC metabolism of non-glucose substrates should be investigated relative to oocyte function and age-related fertility.

biochemistry↗

bioRxiv2020

The Omics Discovery REST interface

The Omics Discovery Index is an open source platform that can be used to access, discover and disseminate omics datasets. OmicsDI integrates proteomics, genomics, metabolomics, models and transcriptomics datasets. Using an efficient indexing system, OmicsDI integrates different biological entities including genes, transcripts, proteins, metabolites and the corresponding publications from PubMed. In addition, it implements a group of pipelines to estimate the impact of each dataset by tracing the number of citations, reanalysis and biological entities reported by each dataset. Here, we present the OmicsDI REST interface to enable programmatic access to any dataset in OmicsDI or all the datasets for a specific provider (database). Clients can perform queries on the API using different metadata information such as sample details (species, tissues, etc), instrumentation (mass spectrometer, sequencer), keywords and other provided annotations. In addition, we present two different libraries in R and Python to facilitate the development of tools that can programmatically interact with the OmicsDI REST interface.

bioinformatics↗

bioRxiv2020

Connectome-based predictive modeling of individual anxiety

Anxiety-related illnesses are highly prevalent in human society. Being able to identify neurobiological markers signaling high trait anxiety could aid the assessment of individuals with high risk for mental illness. Here, we applied connectome-based predictive modeling (CPM) to whole-brain resting-state functional connectivity (rsFC) data to predict the degree of anxiety in 76 healthy participants. Using a computational "lesion" method in CPM, we then examined the weights of the identified main brain areas as well as their connectivity. Results showed that the CPM could predict individual anxiety from whole-brain rsFC, especially from limbic areas-whole brain and prefrontal cortex-whole brain. The prediction power of the model significantly decreased from (simulated) lesions of limbic areas, lesions of the connectivity within the limbic system, and lesions of the connectivity between limbic regions and the prefrontal cortex. Although the same model also predicted depression, anxiety-specific networks could be identified independently, centered at the prefrontal cortex. These findings highlight the important role of the limbic system and the prefrontal cortex in the prediction of anxiety. Our work provides evidence for the usefulness of connectome-based modeling of rsFC in predicting individual personality differences and indicates its potential for identifying personality structures at risk of developing psychopathology.

neuroscience↗

bioRxiv2020

Evolution of vertebrate gill covers via shifts in an ancient Pou3f3 enhancer

Whereas the gill chambers of extant jawless vertebrates (lampreys and hagfish) open directly into the environment, jawed vertebrates evolved skeletal appendages that promote the unidirectional flow of oxygenated water over the gills. A major anatomical difference between the two jawed vertebrate lineages is the presence of a single large gill cover in bony fishes versus separate covers for each gill chamber in cartilaginous fishes. Here we find that these divergent gill cover patterns correlate with the pharyngeal arch expression of Pou3f3 orthologs. We identify a Pou3f3 arch enhancer that is deeply conserved from cartilaginous fish through humans but undetectable in lampreys, with minor sequence differences in the bony versus cartilaginous fish enhancers driving the corresponding single versus multiple gill arch expression patterns. In zebrafish, loss of Pou3f3 gene function disrupts gill cover formation, and forced expression of Pou3f3b in the gill arches generates ectopic skeletal elements resembling the multiple gill cover pattern of cartilaginous fishes. Emergence of this Pou3f3 enhancer >430 mya and subsequent modifications may thus have contributed to the acquisition and diversification of gill covers and respiratory strategies during gnathostome evolution.

developmental biology↗