Biology subjects

Gu, M.

Publications and source records attributed to Gu, M..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Gradual labeling with fluorogenic probes for MINFLUX nanoscopy of densely packed structures

Single-molecule localization in densely packed structures represents a formidable challenge in nanoscopy. Here we develop a gradual labeling method with fluorogenic probes for MINFLUX nanoscopy (GLF-MINFLUX), with which individual proteins in packed structures can be sequential illuminated and quantitatively localized at the nanoscale solely by adjusting probe concentration. With a 1.7-fold localization precision improvement and 2.2-fold faster acquisition, GLF-MINFLUX enables dual-channel nanoscale imaging of densely neuronal microtubules and microfilaments, and three-dimensional quantitative mapping of individual TOM20 proteins in mitochondrial clusters.

biophysics↗

bioRxiv2024

Validation of Enhancer Regions in Primary Human Neural Progenitor Cells using Capture STARR-seq

Genome-wide association studies (GWAS) and expression analyses implicate noncoding regulatory regions as harboring risk factors for psychiatric disease, but functional characterization of these regions remains limited. We performed capture STARR-sequencing of over 78,000 candidate regions to identify active enhancers in primary human neural progenitor cells (phNPCs). We selected candidate regions by integrating data from NPCs, prefrontal cortex, developmental timepoints, and GWAS. Over 8,000 regions demonstrated enhancer activity in the phNPCs, and we linked these regions to over 2,200 predicted target genes. These genes are involved in neuronal and psychiatric disease-associated pathways, including dopaminergic synapse, axon guidance, and schizophrenia. We functionally validated a subset of these enhancers using mutation STARR-sequencing and CRISPR deletions, demonstrating the effects of genetic variation on enhancer activity and enhancer deletion on gene expression. Overall, we identified thousands of highly active enhancers and functionally validated a subset of these enhancers, improving our understanding of regulatory networks underlying brain function and disease.

neuroscience↗

bioRxiv2024

Sarbecovirus RBD indels and specific residues dictating ACE2 multi-species adaptiveness

Sarbecoviruses exhibit varying abilities in using angiotensin-converting enzyme 2 (ACE2) receptor1-3. However, a comprehensive understanding of their multi-species ACE2 adaptiveness and the underlying mechanism remains elusive, particularly for many sarbecoviruses with various receptor binding motif (RBM) insertions/deletions (indels)4-11. Here, we analyzed RBM sequences from 268 sarbecoviruses categorized into four RBM indel types. We extensively examined the capability of 14 representative sarbecoviruses and their derivatives in using ACE2 orthologues from 51 bats and five non-bat mammals. We revealed that most sarbecoviruses with longer RBMs (type-I), present broad ACE2 tropism, whereas viruses with single deletions in Region 1 (type-II) or Region 2 (type-III) generally exhibit narrow ACE2 tropism, typically favoring their hosts ACE2. Sarbecoviruses with double region deletions (type-IV) exhibit a complete loss of ACE2 usage. Subsequent investigations unveiled that both loop deletions and critical RBM residues significantly impact multi-species ACE2 tropism in different ways. Additionally, fine mapping based on type-IV sarbecoviruses elucidated the role of several clade-specific residues, both within and outside the RBM, in restricting ACE2 usage. Lastly, we hypothesized the evolution of sarbecovirus RBM indels and illustrated how loop length, disulfide, and adaptive mutations shape their multi-species ACE2 adaptiveness. This study provides profound insights into the mechanisms governing ACE2 usage and spillover risks of sarbecoviruses.

microbiology↗

bioRxiv2024

Deciphering Endothelial and Mesenchymal Organ Specification in Vascularized Lung and Intestinal Organoids

To investigate the co-development of vasculature, mesenchyme, and epithelium crucial for organogenesis and the acquisition of organ-specific characteristics, we constructed a human pluripotent stem cell-derived organoid system comprising lung or intestinal epithelium surrounded by organotypic mesenchyme and vasculature. We demonstrated the pivotal role of co-differentiating mesoderm and endoderm via precise BMP regulation in generating multilineage organoids and gut tube patterning. Single-cell RNA-seq analysis revealed organ specificity in endothelium and mesenchyme, and uncovered key ligands driving endothelial specification in the lung (e.g., WNT2B and Semaphorins) or intestine (e.g., GDF15). Upon transplantation under the kidney capsule in mice, these organoids further matured and developed perfusable human-specific sub-epithelial capillaries. Additionally, our model recapitulated the abnormal endothelial-epithelial crosstalk in patients with FOXF1 deletion or mutations. Multilineage organoids provide a unique platform to study developmental cues guiding endothelial and mesenchymal cell fate determination, and investigate intricate cell-cell communications in human organogenesis and disease. HighlightsO_LIBMP signaling fine-tunes the co-differentiation of mesoderm and endoderm. C_LIO_LIThe cellular composition in multilineage organoids resembles that of human fetal organs. C_LIO_LIMesenchyme and endothelium co-developed within the organoids adopt organ-specific characteristics. C_LIO_LIMultilineage organoids recapitulate abnormal endothelial-epithelial crosstalk in FOXF1-associated disorders. C_LI

developmental biology↗

bioRxiv2023

Development of compact transcriptional effectors using high-throughput measurements in diverse contexts

Human nuclear proteins contain >1000 transcriptional effector domains that can activate or repress transcription of target genes. We lack a systematic understanding of which effector domains regulate transcription robustly across genomic, cell-type, and DNA-binding domain (DBD) contexts. Here, we developed dCas9-mediated high-throughput recruitment (HT-recruit), a pooled screening method for quantifying effector function at endogenous targets, and tested effector function for a library containing 5092 nuclear protein Pfam domains across varied contexts. We find many effectors depend on target and DBD contexts, such as HLH domains that can act as either activators or repressors. We then confirm these findings and further map context dependencies of effectors drawn from unannotated protein regions using a larger library containing 114,288 sequences tiling chromatin regulators and transcription factors. To enable efficient perturbations, we select effectors that are potent in diverse contexts, and engineer (1) improved ZNF705 KRAB CRISPRi tools to silence promoters and enhancers, and (2) a compact human activator combination NFZ for better CRISPRa and inducible circuit delivery. Together, this effector-by-context functional map reveals context-dependence across human effectors and guides effector selection for robustly manipulating transcription.

systems biology↗

bioRxiv2023

APOE-NOTCH Axis Governs Elastogenesis During Human Cardiac Valve Remodeling

BackgroundValve remodeling is a complex process involving extracellular matrix organization, development of trilaminar structures, and physical elongation of valve leaflets. However, the cellular and molecular mechanisms regulating valve remodeling and their roles in congenital valve disorders remain poorly understood. MethodsSemilunar valves and atrioventricular valves from healthy and age-matched human fetal hearts with pulmonary stenosis (PS) were collected. Single-Cell RNA-sequencing (scRNA-seq) was performed to determine the transcriptomic landscape of multiple valvular cell subtypes in valve remodeling and disease. Spatial localization of newly-identified cell subtypes was determined via immunofluorescence and RNA in situ hybridization. The molecular mechanisms mediating valve development was investigated utilizing primary human fetal heart valve interstitial cells (VICs) and endothelial cells (VECs). ResultsscRNA-seq analysis of healthy human fetal valves identified a novel APOE+ elastin-producing VIC subtype (Elastin-VICs) spatially located underneath VECs sensing the unidirectional flow. Knockdown of APOE in fetal VICs resulted in significant elastogenesis defects. In pulmonary valve with PS, we observed decreased expression of APOE and other genes regulating elastogenesis such as EMILIN1 and LOXL1, as well as elastin fragmentation. These findings suggested the crucial role of APOE in regulating elastogenesis during valve remodeling. Furthermore, cell-cell interaction analysis revealed that JAG1 from unidirectional VECs activates NOTCH signaling in Elastin-VICs through NOTCH3. In vitro Jag1 treatment in VICs increased elastogenesis, while similar observations were found in VICs co-cultured with VECs in the presence of unidirectional flow. Notably, we found that the JAG1-NOTCH3 signaling pair was drastically reduced in the PS valves. Lastly, we demonstrated that APOE is indispensable for JAG1-induced NOTCH activation in VICs, reinforcing the presence of a synergistic intrinsic and external regulatory network involving APOE and NOTCH signaling that is responsible for regulating elastogenesis during human valve remodeling. ConclusionscRNA-seq analysis of human fetal valves identified a novel Elastin-VIC subpopulation, and revealed mechanism of intrinsic APOE and external NOTCH signaling in regulating elastogenesis during cardiac valve remodeling. These mechanisms may contribute to deciphering the pathogenesis of elastin malformation in congenital valve diseases. Clinical Perspective What Is New?O_LIHigh-resolution single-cell transcriptome atlas generated from healthy human fetal heart valves and valves affected by pulmonary stenosis during the early phase of valve remodeling prior to birth. C_LIO_LIA unique subset of valve interstitial cells (VICs) that produce elastin (Elastin-VICs) was identified. C_LIO_LIElastin-VICs specifically located underneath the valve endothelial cells (VECs) sensing unidirectional flow, and played a crucial role in elastin maturation via the expression of APOE. C_LIO_LIElastin-VICs communicated with adjacent VECs via the JAG1-NOTCH signaling, facilitating elastin formation and valve remodeling. C_LI What Are the Clinical Implications?O_LIElastin-VICs from patient valvular tissues with Pulmonary Stenosis exhibit decreased APOE-NOTCH signaling and elastin fragmentation. C_LIO_LIDirect targeting of APOE and NOTCH signaling could be a novel approach to promote elastin fiber formation and valve remodeling in patients with valvular defects. C_LI

bioinformatics↗

bioRxiv2023

Rice OsHAK18 mediates shoot-to-root circulation of potassium and sodium and source-to-sink transport of soluble sugar

High-affinity potassium (K+) transporters HAK/KUP/KT have been identified in all genome-sequenced terrestrial plants. They play important role in K+ acquisition, translocation and enhancing salt tolerance. Here we report that the plasma-membrane-located OsHAK18 functions in K+ and sodium (Na+) circulation and sugar translocation in rice. OsHAK18 is expressed mainly, though not exclusively, in vascular tissues and particularly in the phloem. Knockout (KO) of OsHAK18 reduced K+ concentration in phloem sap and in the root but increased K+ accumulation in the shoot of both Nipponbare and Zhonghua11 cultivars, while overexpression (OX) of OsHAK18 driven by its endogenous promoter increased K+ concentration in phloem sap and in roots, and promoted Na+ retrieval from shoot to root under salt stress. Split-root experimental analysis of rubidium (Rb+) uptake and circulation indicated that OsHAK18-OX promoted Rb+ translocation from shoot to root. In addition, OsHAK18-KO increased while OsHAK18-OX reduced soluble sugar content in the shoot and affected oppositely the sugar concentration in the phloem and its content in the root. Moreover, OsHAK18-OX increased dramatically grain yield and physiological K+ utilization efficiency. Taken together, our results suggest that - unlike other OsHAKs analyzed heretofore - OsHAK18 is critical to K+ and Na+ re-circulation from shoot to root and enhances the source-to-sink translocation of a photo-assimilate. One sentence summaryRice potassium transporter OsHAK18 mediates shoot-to-root circulation of potassium and sodium and source-to-sink translocation of soluble sugar which improves potassium use efficiency and grain yield.

plant biology↗

bioRxiv2023

The Voltage-gated sodium channel in Drosophila, Para, localizes to dendrites as well as axons in mechanosensitive chordotonal neurons

The fruit fly Drosophila melanogaster has provided important insights into how sensory information is transduced by Transient Receptor Potential (TRP) channels in the Peripheral Nervous System (PNS). However, TRP channels alone have not been able to completely model mechanosensitive transduction in mechanoreceptive chordotonal neurons (CN). Here we show that, in addition to TRP channels, the sole voltage-gated sodium channel (NaV) in Drosophila, Para, is localized to the dendrites of CNs. Para is localized to the distal tip of the dendrites in all CNs, from embryos to adults, and is colocalized with the mechanosensitive TRP channels No mechanoreceptor potential C (NompC) and Inactive/Nanchung (Iav/Nan). Para localization also demarcates spike initiation zones (SIZ) in axons and the dendritic localization of Para is indicative of a likely dendritic SIZ in fly CNs. Para is not present in the dendrites of other peripheral sensory neurons. In both multipolar and bipolar neurons in the PNS, Para is present in a proximal region of the axon, comparable to the axonal initial segment in vertebrates, 40-60m from the soma in multipolar neurons and 20-40m in bipolar neurons. Whole-cell reduction of para expression using RNAi in CNs of the adult Johnstons organ severely affects sound-evoked potentials. However, the duality of Para localization in the CN dendrites and axons identifies a need to develop resources to study compartment-specific roles of proteins that will enable us to better understand Paras role in mechanosensitive transduction. Significance StatementSeveral transient receptor potential (TRP) channels have been shown to localize to dendrites of Drosophila mechanosensitive chordotonal neurons (CN). Here, we show that the fly voltage-gated sodium channel, Para co-localizes with the TRP channels NompC and iav and a possible dendritic spike initiation zone (SIZ) in CN dendrites. This dendritic localization is unique to CNs, is not seen in other peripheral neurons, and may account for some aspects of mechanotransduction. Para also localizes to a SIZ at an axonal initial segment-like region, which is shared amongst many peripheral neurons.

neuroscience↗

bioRxiv2023

Brain Organoid Computing for Artificial Intelligence

Brain-inspired hardware emulates the structure and working principles of a biological brain and may address the hardware bottleneck for fast-growing artificial intelligence (AI). Current brain-inspired silicon chips are promising but still limit their power to fully mimic brain function for AI computing. Here, we develop Brainoware, living AI hardware that harnesses the computation power of 3D biological neural networks in a brain organoid. Brain-like 3D in vitro cultures compute by receiving and sending information via a multielectrode array. Applying spatiotemporal electrical stimulation, this approach not only exhibits nonlinear dynamics and fading memory properties but also learns from training data. Further experiments demonstrate real-world applications in solving non-linear equations. This approach may provide new insights into AI hardware.

bioengineering↗

bioRxiv2022

DiffDomain enables identification of structurally reorganized topologically associating domains

Topologically associating domains (TADs) are critical structural units in three-dimensional genome organization of mammalian genome. Dynamic reorganizations of TADs between health and disease states are associated with transcription and other essential genome functions. However, computational methods that can identify reorganized TADs are still in the early stages of development. Here, we present DiffDomain, an algorithm leveraging high-dimensional random matrix theory to identify structurally reorganized TADs using chromatin contact maps. Method comparison using multiple real Hi-C datasets reveals that DiffDomain outperforms alternative methods for FPRs, TPRs, and identifying a new subtype of reorganized TADs. The robustness of DiffDomain and its biological applications are demonstrated by applying on Hi-C data from different cell types and disease states. Identified reorganized TADs are associated with structural variations and changes in CTCF binding sites and other epigenomic changes. By applying to a single-cell Hi-C data from mouse neuronal development, DiffDomain can identify reorganized TADs between cell types with reasonable reproducibility using pseudo-bulk Hi-C data from as few as 100 cells per condition. Moreover, DiffDomain reveals that TADs have differential cell-to-population variability and heterogeneous cell-to-cell variability. Therefore, DiffDomain is a statistically sound method for better comparative analysis of TADs using both Hi-C and single-cell Hi-C data.

bioinformatics↗

bioRxiv2022

Engineering human spinal microphysiological systems to model opioid-induced tolerance

Opioids are commonly used for treating chronic pain. However, with continued use, they may induce tolerance and/or hyperalgesia, which limits therapeutic efficacy. The human mechanisms of opioid-induced hyperalgesia are significantly understudied, in part, because current models cannot fully recapitulate human pathology. Here, we engineered novel human spinal microphysiological systems (MPSs) integrated with plug-and-play neural activity sensing for modeling human nociception and opioid-induced tolerance. Each spinal MPS consists of a flattened human spinal cord organoid derived from human stem cells and a 3D printed organoid holder device for plug-and-play neural activity measurement. We found that the flattened organoid design of MPSs not only reduces hypoxia and necrosis in the organoids, but also promotes their neuron maturation, neural activity, and functional development. We further demonstrated that prolonged opioid exposure resulted in neurochemical correlates of opioid tolerance and hyperalgesia, as measured by altered neural activity, reduced densities of glutamate transporter levels and downregulation of -opioid receptor expression of human spinal MPSs. The MPSs are scalable, cost-effective, easy-to-use, and compatible with commonly-used well-plates, thus allowing plug-and-play measurements of neural activity. We believe the MPSs hold a promising translational potential for studying human pain etiology, screening new treatments, and validating novel therapeutics for human pain medicine.

bioengineering↗

bioRxiv2022

Determinants restricting ACE2 recognition of MERS-related coronaviruses in bats

Phylogenetically distant coronaviruses have evolved to use ACE2 as their common receptors, including NL63 and many Severe acute respiratory syndrome (SARS) coronavirus-related viruses. We recently reported two Middle East respiratory syndrome coronavirus (MERS-CoV) closely related bat merbecoviruses, NeoCoV and PDF-2180, use Angiotensin-converting enzyme 2 (ACE2) for entry. However, their host range and cross-species transmissibility remain unknown. Here, we characterized their species-specific receptor preference by testing ACE2 orthologs from 49 bats and 53 non-bat mammals. Both viruses exhibited broad receptor recognition spectra and are unable to use ACE2 orthologs from 24 species, mainly Yinpterochiropteran bats. Comparative analyses of bat ACE2 orthologs underscored four crucial host range determinants, all confirmed by subsequent functional assays in human and bat cells. Among them, residue 305, participating in a critical interaction, plays a crucial role in host tropism determination. NeoCoV-T510F, a mutation that enhances human ACE2 recognition, further expanded the potential host range via tighter interaction with an evolutionary conserved hydrophobic pocket. Our results elucidated the molecular basis for the species-specific ACE2 usage of MERS-related viruses across mammals and shed light on their zoonotic risks.

microbiology↗

bioRxiv2022

TMEM100, a Lung-Specific Endothelium Gene

The heterogeneity of endothelium across different organs was recently explored using single-cell RNA-sequencing analysis. Compared to other organs, the lung exhibits a distinct structure composed of a thin layer of capillary for efficient gas exchange. In this study, we demonstrate that Tmem100 is a lung-specific endothelium gene.

physiology↗

bioRxiv2022

Frataxin deficiency disrupts mitochondrial respiration and pulmonary endothelial cell function

Deficiency of iron-sulfur (Fe-S) clusters promotes metabolic rewiring of the endothelium and the development of pulmonary hypertension (PH) in vivo. Joining a growing number of Fe-S biogenesis proteins critical to pulmonary endothelial function, recent data highlighted that frataxin (FXN) reduction drives Fe-S-dependent genotoxic stress and senescence across multiple types of pulmonary vascular disease. Trinucleotide repeat mutations in the FXN gene cause Friedreichs ataxia, a disease characterized by cardiomyopathy and neurodegeneration. These tissue-specific phenotypes have historically been attributed to mitochondrial reprogramming and oxidative stress. Whether FXN coordinates both nuclear and mitochondrial processes in the endothelium is unknown. Here, we aim to identify the mitochondria-specific effects of FXN deficiency in the endothelium that predispose to pulmonary hypertension. Our data highlight an Fe-S-driven metabolic shift separate from previously described replication stress whereby FXN knockdown diminished mitochondrial respiration and increased glycolysis and oxidative species production. In turn, FXN-deficient endothelial cells exhibited a vasoconstrictive phenotype consistent with PH. These data were observed in both primary pulmonary endothelial cells after pharmacologic inhibition of FXN and inducible pluripotent stem cell-derived endothelial cells from patients with FXN mutations. Altogether, this study defines FXN as a shared upstream driver of pathologic aberrations in both metabolism and genomic stability. Moreover, our study highlights FXN-specific vasoconstriction, suggesting available and future therapies may be beneficial and targeted for PH subtypes with FXN deficiency. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=166 SRC="FIGDIR/small/504849v1_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@12c5568org.highwire.dtl.DTLVardef@19b5f0borg.highwire.dtl.DTLVardef@17d0157org.highwire.dtl.DTLVardef@1e323a0_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

Integrative single-cell analysis of cardiogenesis identifies developmental trajectories and non-coding mutations in congenital heart disease

Congenital heart defects, the most common birth disorders, are the clinical manifestation of anomalies in fetal heart development - a complex process involving dynamic spatiotemporal coordination among various precursor cell lineages. This complexity underlies the incomplete understanding of the genetic architecture of congenital heart diseases (CHDs). To define the multi-cellular epigenomic and transcriptional landscape of cardiac cellular development, we generated single-cell chromatin accessibility maps of human fetal heart tissues. We identified eight major differentiation trajectories involving primary cardiac cell types, each associated with dynamic transcription factor (TF) activity signatures. We identified similarities and differences of regulatory landscapes of iPSC-derived cardiac cell types and their in vivo counterparts. We interpreted deep learning models that predict cell-type resolved, base-resolution chromatin accessibility profiles from DNA sequence to decipher underlying TF motif lexicons and infer the regulatory impact of non-coding variants. De novo mutations predicted to affect chromatin accessibility in arterial endothelium were enriched in CHD cases versus controls. We used CRISPR-based perturbations to validate an enhancer harboring a nominated regulatory CHD mutation, linking it to effects on the expression of a known CHD gene JARID2. Together, this work defines the cell-type resolved cis-regulatory sequence determinants of heart development and identifies disruption of cell type-specific regulatory elements as a component of the genetic etiology of CHD.

genomics↗

bioRxiv2022

Real-time feeding behavior monitoring by electrical penetration graph rapidly reveals host plant susceptibility to crapemyrtle bark scale (Hemiptera: Eriococcidae)

Host range confirmation of invasive hemipterans relies on the evaluation of plant susceptibility though greenhouse or field trials, which are inefficient and time-consuming. When the green industry faces the fast-spreading threat of invasive pests such as crapemyrtle bark scale (Acanthococcus lagerstroemiae), it is imperative to timely identify potential host plants and evaluate plant resistance/susceptibility to pest infestation. In this study, we developed an alternative technology to complement the conventional host confirmation methods. We used electrical penetration graph (EPG) based technology to monitor the A. lagerstroemiae stylet-tip position when it was feeding on different plant tissues in real-time. The frequency and relative amplitude of insect feeding waveforms (recorded by EPG) were extracted by an R programming-based software written to generate eleven feeding parameters for comparative analysis between plant species. The results demonstrated that the occurrences of phloem phase and xylem phase offered conclusive evidence for host plant evaluation. Furthermore, parameters including the percentage of insects capable of accessing phloem tissue, time duration spent on initiating phloem phase and ingesting phloem sap, provided insight into why host plant susceptibility differs among similar plant species. In summary, this study developed a novel real-time diagnostic tool for quick A. lagerstroemiae host confirmation, which laid the essential foundation for effective pest management. Simple SummaryCrapemyrtle bark scale (CMBS; Acanthococcus lagerstroemiae), an invasive polyphagous sap feeder in the United States, has spread across 16 U.S. states in less than two decades, posing potential risks to the Green Industry. Confirming the host range is crucial for effective pest management of invasive insects. However, host range confirmation relying on greenhouse or field trials is often inefficient and time-consuming. In this study, we used the electrical penetration graph (EPG) to monitor the stylet penetration of CMBS in plant tissue in real-time. An R programming-based application was developed to better characterize the insect feeding waveforms recorded by EPG. By analyzing EPG-based feeding parameters, we demonstrated that CMBS have difficulty accessing the phloem tissue (salivation and ingestion) of a resistant plant compared to a susceptible plant. Importantly, we hereby present CMBS typical feeding behaviors on susceptible and non-susceptible plants comparatively, which provides direct evidence for revealing unknown hosts rapidly.

plant biology↗

bioRxiv2022

Green Lacewing Chrysoperla rufilabris (Neuroptera: Chrysopidae) is a potential biological agent for controlling crapemyrtle bark scale (Hemiptera: Eriococcidae)

Crapemyrtle bark scale (CMBS; Acanthococcus lagerstroemiae), an invasive sap-sucking hemipteran, has spread across 16 U.S. states. Infestation of CMBS negatively impacts the flowering of crapemyrtles and reduces the aesthetic quality of ornamental plants. The widespread use of soil-applied neonicotinoid insecticides to repress the CMBS infestation could threaten important beneficial insects; therefore, using natural enemies to control CMBS is greatly needed. This study evaluated larval green lacewing (Chrysoperla rufilabris) as a biocontrol agent of CMBS. Predatory behavior of the larval C. rufilabris upon CMBS was documented under a stereomicroscope using infested crapemyrtle samples collected from different locations in College Station. Predation potential of C. rufilabris upon CMBS eggs and foraging performance using Y-maze assay were both investigated in laboratory conditions. Results confirmed that larval C. rufilabris preyed on CMBS nymphs, eggs, and adult females. The evaluation of predation potential results showed that the number of CMBS eggs consumed in 24 hours by 3rd instar C. rufilabris (176.4 {+/-}6.9) was significantly higher than by 2nd instar (151.5{+/-}6.6) and by 1st instar (11.8{+/-}1.3). The foraging performance results showed that larval C. rufilabris could target CMBS under dark, indicating that some cues associated with olfactory response were likely involved when preying on CMBS. This study is the first report that validated C. rufilabris as a natural predator of CMBS and its potential as a biological agent to control CMBS. Future investigation about the olfactory response of larval C. rufilabris to CMBS would benefit the development of environmental-friendly strategies to control CMBS spread.

ecology↗

bioRxiv2022

Antiviral DExD/H-box helicase 60 selectively inhibits translation from type II internal ribosome entry sites

During viral infection, competition ensues between viruses and their host cells to control the protein synthesis machinery. In response, certain host defense proteins globally limit mRNA translation. However, this is also detrimental for host protein synthesis. Here we describe an interferon-stimulated helicase, DDX60, that specifically inhibits translation from type II viral internal ribosome entry sites (IRESs). IRESs are RNA structures that enable mRNAs to recruit ribosomes directly, bypassing translation initiation using a 5 cap. DDX60 was previously observed to inhibit replication of a reporter hepatitis C virus (HCV). We show that DDX60 likely does not inhibit HCV replication, but surprisingly, inhibits the type II IRES used in the reporter HCV genomic RNA. Using firefly luciferase mRNAs translationally driven by different viral IRESs or a 5 cap analog, we show that DDX60 selectively reduces translation driven by type II IRESs of encephalomyocarditis virus (EMCV) and foot and mouth disease virus (FMDV), but not other IRES types or a 5 cap analog. Correspondingly, DDX60 reduces EMCV and FMDV (type II IRES) replication, but not poliovirus or bovine enterovirus 1 (type I IRES) replication. Furthermore, replacing the IRES of poliovirus with a type II IRES is sufficient for DDX60 to inhibit poliovirus replication. Finally, we demonstrate that DDX60 specifically reduces polysome binding on type II IRES mRNA, but not 5 cap-dependent mRNA. Our data demonstrate that the cellular defense factor DDX60 counteracts viral takeover of host translation by blocking ribosome access to type II IRES elements specifically.

microbiology↗