Biology subjects

Lu, G.

Publications and source records attributed to Lu, G..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

HILIC-Enabled Mass Spectrometric Discovery of Novel Endogenous and Glycosylated Neuropeptides in the American Lobster Nervous System

Neuropeptides are a highly conserved and diverse class of intercellular signaling molecules that regulate a broad range of neural and hormonal processes across animal phyla. The American lobster, Homarus americanus, has long served as a powerful invertebrate model for the discovery and functional investigation of neuropeptides. Among common post-translational modifications (PTMs) found in neuropeptides, glycosylation remains underexplored due to the inherently low in vivo abundance and intrinsically complex structural heterogeneity. In this study, we employed hydrophilic interaction liquid chromatography (HILIC) enrichment coupled with oxonium-ion triggered EThcD fragmentation strategy to simultaneously profile novel endogenous and glycosylated neuropeptides across eight distinct neural tissues and neuroendocrine organs of Homarus americanus. This integrative mass spectrometry-based approach led to the identification of 154 endogenous neuropeptides derived from 25 families, approximately one-third of which are newly reported, and uncovered 24 glycosylated neuropeptides in this species for the first time. These peptides exhibit strong tissue-specific expression, distinct proteolytic cleavage patterns, and confidently localized glycosylation sites. Our results highlight the utility of integrated sampling enrichment and hybrid fragmentation strategies for deep neuropeptidomic profiling and provide a valuable resource for future studies on the functional roles of newly identified neuropeptides and glycosylation in crustacean neuromodulation and peptidergic signaling. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/661634v2_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@9a1745org.highwire.dtl.DTLVardef@6decc4org.highwire.dtl.DTLVardef@d34256org.highwire.dtl.DTLVardef@1a83b4c_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

MONTAGE: A Computation Framework to Identify Spatially Resolved Functional Enrichment Gradients in the Tissue Microenvironment via Spatial Communities

Single-cell spatial-omics has advanced our understanding of how tumor microenvironment contributes to cancer progression. However, most single-cell spatial-omics studies focus on cell types and neighborhoods, offering limited information about functional and clinical relevance of cellular organization. We introduce MONTAGE, a computational framework to reconstruct, functionally analyze, and identify clinically relevant cellular spatial communities (SCs). MONTAGE generates a gene signature matrix of SCs from integrated atlases that offer single-cell resolution with transcriptomics, and reconstructs tissue maps ("montages"), reflecting sequential SC compositional changes along spatial gradients of biological function enrichments. The MONTAGE signature matrix can also be used to deconvolve bulk and spot-based spatial transcriptomic data, and combining with clinical metadata, allows assessing SC clinical relevance. In a head and neck cancer study, MONTAGE reveals SCs enriched with malignant cells and granulocytes shifting to SCs enriched with macrophages and fibroblasts along gradient of epithelial-mesenchymal transition, and clinical prognostic significance of the SCs.

systems biology↗

bioRxiv2025

Rewiring of 3D chromatin topology orchestrates transcriptional reprogramming in muscle fiber-type specification and transformation

The composition of muscle fibers, characterized by distinct contractile and metabolic properties, significantly influences meat quality and glucose homeostasis. However, the mechanisms by which three-dimensional (3D) genome topology integrates with epigenetic states to regulate muscle fiber specification and transformation remain poorly understood. Here, we present an integrative analysis of the transcriptome, epigenome, and 3D genome architecture in the slow-twitch glycolytic extensor digitorum longus (EDL) and fast-twitch oxidative soleus (SOL) muscles. Global remodeling of enhancer-promoter (E-P) interactions emerged as a central driver of transcriptional reprogramming associated with muscle contraction and glucose metabolism. We identified tissue-specific super-enhancers (SEs) that regulate muscle fiber-type specification through cooperation of chromatin looping and transcription factors such as KLF5. Notably, the SE-driven activation of STARD7 facilitated the transformation of glycolytic fibers into oxidative fibers by mitigating reactive oxygen species levels and suppressing ERK MAPK signaling. This study elucidates the principles of 3D genome organization in the epigenetic regulation of muscle fiber specification and transformation, providing a foundation for novel therapeutic strategies targeting metabolic disorders and enhancing meat quality. O_FIG O_LINKSMALLFIG WIDTH=142 HEIGHT=200 SRC="FIGDIR/small/643571v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@990eecorg.highwire.dtl.DTLVardef@a2b491org.highwire.dtl.DTLVardef@1fcd142org.highwire.dtl.DTLVardef@10e4d47_HPS_FORMAT_FIGEXP M_FIG Schematic overview of the study. C_FIG

developmental biology↗

bioRxiv2025

Quantitative phosphoproteomic analysis of testes from Iqcn-deficient mice highlights the significance of calmodulin signaling in spermiogenesis

Calmodulin (CaM) plays a crucial role in sperm function. Studies have reported that proteins containing IQ motif interact with CaM, subsequently engaging with downstream target proteins known as calmodulin-binding proteins (CaMBPs). It is reported that the loss of interaction between IQCN and CaM is mainly manifested as decreased motility, leading to fertilization failure and male infertility. However, no relevant reports have been published detailing which CaMBPs exist and the mechanisms by which they are regulated. In this study, we conducted a comprehensive quantitative proteomic and phosphoproteomic analysis of mouse testes from wild-type (WT) and Iqcn knockout (Iqcn-/-) mice. The results indicated that Iqcn deficiency substantially rewires the downstream phosphorylation signaling pathway, while not causing equivalent changes in protein levels. Among the total 577 differentially regulated phosphorylated sites in our results, most of them (494/577) belong to calmodulin-binding proteins (CaMBPs). Gene ontology analysis of these differentially phosphorylated CaMBPs showed enrichment in male gamete generation, actin cytoskeleton organization and microtubule cytoskeleton organization process, demonstrating IQCN regulates sperm function by interacting with CaM, which in turn affects the phosphorylation level of CaMBPs. Further kinase substrate network analysis revealed that most kinases with substrates phosphorylation sites up-regulated were tyrosine kinases, and the inhibition assay showed that FGFR4 and SYK tyrosine kinases are important for sperm motility and progressive motility. In summary, this study reveals the interaction between IQ motif-containing protein IQCN and CaM, which regulates the phosphorylation of downstream CaMBPs and is involved in the related processes of spermiogenesis and sperm function.

developmental biology↗

bioRxiv2024

Structural and functional interrelationship of histone H2A and its variants H2A.Z and H2A.W in Arabidopsis

Multiple histone H2A variants are known in eukaryotes. However, the functional relationship between H2A and its variants in plants remains largely obscure. Using CRISPR/Cas9 editing, we generated a mutant lacking four H2A isoforms in Arabidopsis and analyzed the functional and structural relationship between H2A and its variants H2A.Z and H2A.W. RNA-sequencing and phenotype analyses revealed mild changes in gene transcription and plant development in the mutants lacking H2A, H2A.Z, or H2A.W compared with the wild-type plants. Chromatin immunoprecipitation sequencing analysis showed that H2A is able to substitute for both H2A.Z and H2A.W across the genome, including in euchromatin and heterochromatin regions. However, H2A.Z replaced both H2A and H2A.W primarily within the euchromatin regions. By using DNA and histones derived from Arabidopsis, we constructed nucleosomes containing H2A, H2A.Z, or H2A.W and resolved their cryogenic electron microscopy structures at near-atomic resolution. Collectively, the results reveal the structural similarity and functional redundancy of H2A and H2A variants in Arabidopsis.

plant biology↗

bioRxiv2024

RTF1 mediates epigenetic control of Th17 cell differentiation via H2B monoubiquitination

A gene encoding the transcription factor RTF1 has been associated with an increased risk of ulcerative colitis (UC). In this study, we investigated its function in modulating T cells expressing interleukin-17A (Th17 cells), a cardinal cell type promoting intestinal inflammation. Our results indicate that Rtf1 deficiency disrupts the differentiation of Th17 cells, while leaving regulatory T cells (Treg) unaffected. Mechanistically, RTF1 facilitates histone H2B monoubiquitination (H2Bub1), which requires its histone modification domain (HMD), for supporting Th17 cell function. Impaired Th17 differentiation was also observed in cells lacking the H2Bub1 E3 ligase subunit RNF40, an enzyme known to physically interact with RTF1. Thus, our study underscores the essential role of RTF1 in H2Bub1-mediated epigenetic regulation of Th17 cell differentiation. Understanding this process will likely provide valuable insights into addressing Th17-associated inflammatory disorders. Key PointsO_LIRTF1 is crucial for Th17 cell differentiation via histone H2B monoubiquitination C_LIO_LIRTF1 deficiency impairs Th17 differentiation, similar to H2Bub1 ligase RNF40 deficiency C_LIO_LIRTF1 and H2Bub1 colocalize on genes regulating Th17 cells, indicating an epigenetic role C_LI

immunology↗

bioRxiv2024

Tumor Priming by Ultrasound Mechanogenetics for with SynNotch CAR T Therapy

Cell-based cancer immunotherapy holds potential as a therapeutic approach, yet its application for solid tumor treatment remains challenging. We created a system where focused ultrasound (FUS) is able to remotely stimulate gene expressions in a specific tissue area through mechanical induction, gated by a chemical inducer to minimize the background noise. This system, known as CaDox, integrates FUS-triggered mechanical and calcium stimulation with doxycycline-responsive genetic circuits, which allows the localized expression of the clinically validated and specific antigen CD19 within a subpopulation of cancer cells upon FUS stimulation. These CD19-expressing cells can then function as "training centers" that activate synNotch chimeric antigen receptor (CAR) T cells to generate CARs that recognize a less specific but widespread antigen in cancer cells, thereby attacking and suppress the whole cancer cell population nearby at the tumor site. We validated the functionality of this CaDox system in vitro, in organoids, and in vivo, demonstrating its potential for various cell types and as a versatile platform for precisely controllable immunotherapy. Our combinatorial approach thus offers a FUS-controlled remote and non-invasive priming of solid tumors for effective and safe CAR T immunotherapy via the induced production of clinically validated antigens.

synthetic biology↗

bioRxiv2024

SIRT5-mediated GLS and GDH desuccinylation attenuates autophagy in MAC-T cells induced by ammonia

Our previous research revealed that NH3 regulated autophagy dependent on SIRT5 in MAC-T cells. Interestingly, SIRT5 reduced the content of NH3 and glutamate by inhibiting GLS activity, ADP/ATP value also declined. In this study, SIRT5 interacted with endogenous GLS and GDH, and had no effect on endogenous GLS and GDH expression. SIRT5 declined significantly the succinylation levels of GLS and GDH, and further reduced the enzymatic activity of GLS and GDH. SIRT5 declined the glutamine metabolism, which attenuated ammonia release in MAC-T cells, accompanying with cellular autophagy decline, reducing the formation of autophagosome. Deletion of SIRT5 increased the content of NH3 and glutamate, as well as promotes autophagy, which could be alleviated by SIRT5 overexpression. SIRT5 KO was associated with increased succinylation and activity of GLS and GDH, as well as autophagy response in MAC-T cells. Furthermore, SIRT5 promoted the maintenance of mitochondria homeostasis. Mechanistically, SIRT5 modulated the succinylation levels and enzymatic activities of GLS and GDH in mitochondria and promoted the maintenance of mitochondria homeostasis, further attenuating ammonia-stimulated autophagy in MAC-T cells. HighlightsO_LISIRT5 catalyzed lysine desuccinylation of GLS and GDH. C_LIO_LIGLS and GDH enzymatic activity were enhanced by lysine succinylation. C_LIO_LIGLS and GDH were required for SIRT5 to regulate ammonia-induced cellular autophagy. C_LIO_LISIRT5 promoted the maintenance of mitochondrial homeostasis C_LI

physiology↗

bioRxiv2024

Recycling of trans-Golgi SNAREs is essential for apoplastic effector secretion and effective pathogenicity of Magnaporthe oryzae

Vesicle transport is an essential process that mediates the growth, development and virulence of pathogenic fungi. However, the intricate mechanisms underlying how vesicle transport regulates the secretion of effector proteins remain to be fully elucidated. Here, we unveiled a novel pathway in which retromer and trans-Golgi (TGN) SNARE proteins co-regulate the proper secretion of apoplastic effectors in the rice blast fungus Magnaporthe oryzae. A TGN-associated SNARE complex consisting of MoSnc1, MoTlg1, MoTlg2, and MoVti1 was found to be essential for growth, development and pathogenicity in the fungus. Moreover, the TGN-associated SNARE complex is indispensable for accurate secretion of apoplastic effectors. Furthermore, we have elucidated that the dynamin-like protein MoVps1, an upstream regulator of the retromer complex, regulates the fission of MoVps35-coated vesicle and the proper localization of the TGN-associated SNARE complex. Additionally, we employed prochlorperazine, which identified as a potent dynamin inhibitor, elicits a developmental response in M. oryzae akin to MoVPS1 disruption, highlighting the pivotal regulatory role of dynamin and its potential as a therapeutic target for rice blast disease management. In conclusion, the study uncovered a specific mechanism by which MoVps1 and the retromer complex regulate the positioning of TGN-associated SNARE proteins to effectively promote effector secretion. It provides a deeper understanding of the molecular mechanisms of effector secretion in fungi and underscores the importance of vesicle transport in fungal pathogenesis. ImportanceVesicle transport is essential for pathogenic fungi as it controls the secretion of effectors that modulate interactions with the host and infection processes. The detailed mechanisms of effector secretion via vesicular pathways in these fungi are not yet fully understood. In this study, we have discovered a new regulatory pathway involving the retromer complex and trans-Golgi SNARE proteins that is critical for the proper secretion of apoplast effectors in M. oryzae. We have identified an important TGN-associated SNARE complex, consisting of MoSnc1, MoTlg1, MoTlg2 and MoVti1, which is required for the development and pathogenicity of M. oryzae. Our results emphasize the importance of this SNARE complex for the precise secretion of effectors into the apoplast, a key step in pathogenesis. Additionally, we demonstrated that the dynamin-like protein MoVps1, a protein acting upstream of the retromer complex, is vital for the correct localization of the TGN-associated SNARE complex. Furthermore, our research underscores the critical regulatory role of dynamin in M. oryzae pathogenesis, with prochlorperazine serving as an inhibitor that mimics the phenotypic effects of MoVps1 disruption, thereby highlighting its potential as a biopesticide candidate for rice blast disease management. Our study has uncovered a specific regulatory mechanism in which MoVps1 and the retromer complex control the positioning and function of TGN-associated SNARE proteins, thereby facilitating effector secretion. This work not only advances our understanding of the molecular basis of effector secretion in fungi, but also has implications for the development of novel strategies to control fungal diseases.

microbiology↗

bioRxiv2024

LGR4 is essential for maintaining beta-cell homeostasis through suppression of RANK

Pancreatic {beta}-cell stress contributes to diabetes progression. This study demonstrates that Leucine-rich repeat-containing G-protein-coupled-receptor-4 (LGR4) is critical for maintaining {beta}-cell health and is modulated by stressors. In vitro, Lgr4 knockdown decreases proliferation and survival in rodent {beta}-cells, while overexpression protects against cytokine-induced cell death in rodent and human {beta}-cells. Mechanistically, LGR4 suppresses Receptor Activator of Nuclear Factor Kappa B (NF{kappa}B) (RANK) and its subsequent activation of NF{kappa}B to protect {beta}-cells. {beta}-cell-specific Lgr4-conditional knockout (cko) mice exhibit normal glucose homeostasis but increased {beta}-cell death in both sexes and decreased proliferation only in females. Male Lgr4cko mice under stress display reduced {beta}-cell proliferation and a further increase in {beta}-cell death. Upon aging, both male and female Lgr4cko mice display impaired {beta}-cell homeostasis, however, only female mice are glucose intolerant with decreased plasma insulin. We show that LGR4 is required for maintaining {beta}-cell health under basal and stress-induced conditions, through suppression of RANK. TeaserLGR4 receptor is critical for maintaining {beta}-cell health under basal and stressed conditions, through suppression of RANK.

physiology↗

bioRxiv2024

Structures of transcription-translation coupling complexes at each stage of the translation cycle

In the bacterium Escherichia coli, efficient expression of protein-coding genes is achieved through physical coupling of RNA polymerase (RNAP) synthesizing an mRNA and the first ribosome translating the mRNA, with transcription elongation factors NusG and NusA bridging RNAP and ribosome in a transcription-translation complex (TTC). Recent structural studies suggest that the flexibility in NusG and NusA accommodates the changes in ribosome conformation that occur during the translation cycle, but details have been unclear. Here, we report cryo-EM structures of TTCs at each stage of the translation cycle as an actively translating ribosome approaches to a halted transcription complex. We observe sequential conversion of a loosely coupled TTC (TTC-LC) to a tightly coupled TTC (TTC-B) to a collided TTC (TTC-A) as the ribosome approaches the transcription complex. We show that flexibility of the NusG linker and NusA "pantograph" enable TTC-LC and TTC-B to accommodate ribosome conformation at each stage of the translation cycle. We show that, in TTC-A, steric clash between ribosome and RNAP upon ribosome 30S head swiveling inhibits 30S head swiveling, consistent with translation slowdown, and applies mechanical force to the trailing edge of RNAP, causing transcription termination. Our results define the structures and properties of loosely coupled, tightly coupled, and collided TTCs at each stage of the translation cycle.

molecular biology↗

bioRxiv2024

Restricted intake of sulfur-containing amino acids reversed the hepatic injury induced by excess Desulfovibrio through gut-liver axis

Gut-liver axis has been a study focus for liver diseases. Diet is a key player in influencing the gut microbiota. However, the effect of different dietary patterns on gut microbiota and liver functions remains unclear. Here, we used mouse standard chow and purified diet to mimic two common human dietary patterns: healthy grain and planted-based diet and Western style diet, respectively and explored their impacts on the gut microbiota and liver. Gut microbiota experienced a great shift with notable increase in Desulfovibrio, gut bile acid (BA) concentration elevated significantly, and liver inflammation was observed in mice fed with the purified diet. Liver inflammation due to translocation of toxic lipopolysaccharides (LPS) and hydrophobic BAs from the damaged gut barrier was also observed in mice fed with the chow diet after receiving Desulfovibrio desulfuricans ATCC 29577 (DSV). Restricted intake of sulfur-containing amino acids reversed the liver injury due to excess Desulfovibrio through lowering the gut BA concentration and enhancing the hepatic antioxidant and detoxifying ability. Ex vivo fermentation of human fecal microbiota with primary BAs also demonstrated that DSV enhanced production of secondary BAs. Germ-free mice had higher concentration of both conjugated and unconjugated primary BAs in their gut after receiving DSV.

microbiology↗

bioRxiv2024

Tmc7 deficiency causes acrosome biogenesis defects and male infertility in mice

Transmembrane channel-like (TMC) proteins are a highly conserved ion channel family consisting of eight members (TMC1-TMC8) in mammals. TMC1/2 are components of the mechanotransduction channel in hair cells, and mutations of TMC1/2 cause deafness in humans and mice. However, the physiological roles of other TMC proteins remain largely unknown. Here, we show that Tmc7 is specifically expressed in the testis and that it is required for acrosome biogenesis during spermatogenesis. Tmc7-/- mice exhibited abnormal sperm head, disorganized mitochondrial sheaths, and reduced number of elongating spermatids, similar to human oligo-astheno-teratozoospermia. We further demonstrate that TMC7 is colocalized with GM130 at the cis-Golgi region in round spermatids. TMC7 deficiency leads to aberrant Golgi morphology and impaired fusion of Golgi-derived vesicles to the developing acrosome. Moreover, upon loss of TMC7 intracellular ion homeostasis is impaired and ROS levels are increased, which in turn causes Golgi and endoplasmic reticulum (ER) stress. Taken together, these results suggest that TMC7 is required to maintain pH and ion homeostasis, which is needed for acrosome biogenesis. Our findings unveil a novel role for TMC7 in acrosome biogenesis during spermiogenesis.

developmental biology↗

bioRxiv2023

Golgi-associated retrograde protein (GARP) complex recruits retromer to trans-Golgi network for FgKex2 and FgSnc1 recycling, necessary for development and pathogenicity of Fusarium graminearum

In eukaryotic cells, the retromer complex plays a crucial role in orchestrating the sorting and retrograde transport of cargo proteins from endosomes to the trans-Golgi network (TGN). Despite its significance, the molecular details of this intracellular trafficking process remain unclear. Here, we identified a Golgi-associated retrograde protein (GARP) complex as a mediator of vesicular transport, facilitating the recruitment of the retromer complex to TGN to exert its functions. The GARP complex is mainly localized to the TGN, where it interacts with the retromer complex. This interaction is evolutionarily conserved across different species. Furthermore, we identified FgKex2 and Fgsnc1 as cargo proteins in the GARP/retromer-mediated recycling pathway. Loss of GARP or retromer results in a complete mis-sorting of FgKex2 and FgSnc1 to the vacuolar degradation pathway, which affects the growth, development, toxisome biogenesis, and pathogenicity of F. graminearum. In summary, we assert that GARP facilitates the recruitment of retromer from endosomes to the TGN, orchestrating the recycling of FgKex2 and FgSnc1. This is integral to sustaining continuous growth, development and contributes significantly to the pathogenicity of F. graminearum.

microbiology↗

bioRxiv2023

Human Pancreatic α-Cell Heterogeneity and Trajectory Inference Analysis Using Integrated Single Cell- and Single Nucleus-RNA Sequencing Platforms

Prior studies have shown that pancreatic -cells can transdifferentiate into {beta}-cells, and that {beta}-cells de-differentiate and are prone to acquire an -cell phenotype in type 2 diabetes (T2D). However, the specific human -cell and {beta}-cell subtypes that are involved in -to-{beta}-cell and {beta}-to--cell transitions are unknown. Here, we have integrated single cell RNA sequencing (scRNA-seq) and single nucleus RNA-seq (snRNA-seq) of isolated human islets and human islet grafts and provide additional insight into -{beta} cell fate switching. Using this approach, we make seven novel observations. 1) There are five different GCG-expressing human -cell subclusters [1, 2, -{beta}-transition 1 (AB-Tr1), -{beta}-transition 2 (AB-Tr2), and -{beta} (AB) cluster] with different transcriptome profiles in human islets from non-diabetic donors. 2) The AB subcluster displays multihormonal gene expression, inferred mostly from snRNA-seq data suggesting identification by pre-mRNA expression. 3) The 1, 2, AB-Tr1, and AB-Tr2 subclusters are enriched in genes specific for -cell function while AB cells are enriched in genes related to pancreatic progenitor and {beta}-cell pathways; 4) Trajectory inference analysis of extracted - and {beta}-cell clusters and RNA velocity/PAGA analysis suggests a bifurcate transition potential for AB towards both - and {beta}-cells. 5) Gene commonality analysis identifies ZNF385D, TRPM3, CASR, MEG3 and HDAC9 as signature for trajectories moving towards {beta}-cells and SMOC1, PLCE1, PAPPA2, ZNF331, ALDH1A1, SLC30A8, BTG2, TM4SF4, NR4A1 and PSCK2 as signature for trajectories moving towards -cells. 6) Remarkably, in contrast to the events in vitro, the AB subcluster is not identified in vivo in human islet grafts and trajectory inference analysis suggests only unidirectional transition from -to-{beta}-cells in vivo. 7) Analysis of scRNA-seq datasets from adult human T2D donor islets reveals a clear unidirectional transition from {beta}-to--cells compatible with dedifferentiation or conversion into -cells. Collectively, these studies show that snRNA-seq and scRNA-seq can be leveraged to identify transitions in the transcriptional status among human islet endocrine cell subpopulations in vitro, in vivo, in non-diabetes and in T2D. They reveal the potential gene signatures for common trajectories involved in interconversion between - and {beta}-cells and highlight the utility and power of studying single nuclear transcriptomes of human islets in vivo. Most importantly, they illustrate the importance of studying human islets in their natural in vivo setting.

cell biology↗

bioRxiv2023

Co-existence of blaKPC-2 and blaVIM-2 in highly carbapenem-resistant Pseudomonas aeruginosa isolated in the ICU of a public hospital

In this study, highly carbapenem-resistant Pseudomonas aeruginosa (h-CRPA) 18102011 [the minimum inhibitory concentration (MIC) value of carbapenem antimicrobial imipenem (IP) for h-CRPA is 4,096 g/mL] was isolated from the bile of an intensive care unit (ICU) burn patient in China, and genomic sequencing revealed a complete genome. The genomes molecular characteristics were analyzed to assess the genetic environment of blaKPC-2 and blaVIM-2. Average nucleotide identity (ANI) comparisons were used for precise species-level identification, while serotyping, multi-locus sequence typing, and the identification of acquired resistance genes, and virulence genes were also carried out. The h-CRPA 18102011 strain carrying blaKPC-2 and blaVIM-2 was identified as strain ST2374 and the O4 serotype. Virulence genes (plcH, exoST) and resistance genes (aph(3)-IIb, aac(6)-Ib-cr, ant(2)-Ia, blaOXA-396, blaPAO, blaKPC-2, blaVIM-2, blaPER-1, sul1, catB7, qnrVC6, fosA) were both identified in the genome. In addition, the IncpRBL16 type mega-plasmid pP2011-1 carrying blaVIM-2 and the IncP6 type plasmid pP2011-2 carrying blaKPC-2 were identified in the strain. The genetic environment of blaVIM-2 and blaKPC-2 was specifically evaluated to assess their origins. blaVIM-2 was located in the region of In2075 (a novel type 1 integron) that was inserted into plasmid pP2011-1, this plasmid contained 3 novel recombination sites, as well as the typical recombination site 2 (umuC) observed for IncpRBL16 type plasmids. However, the core module Tn3-ISKpn27-blaKPC-{Delta}ISKpn6 was identified as the blaKPC-2 platform in plasmid pP2011-2. Conjugation experiments revealed that the plasmids pP2011-1 and pP2011-2 of the h-CRPA 18102011 strain could be transferred into Escherichia coli with a conjugation transfer efficiency of 10-6. The E. coli transconjugant carried blaKPC-2 and blaVIM-2 from the donor and the MIC value of IP to the E. coli transconjugant was 4,096 g/mL, which was the same as observed for the donor. Overall, this study revealed the molecular characteristics of a VIM-2 and KPC-2-co-producing strain that was typed as O4 and ST2374. The continuous monitoring of bacteria, such as the strain investigated here, that co-harbor different types of carbapenemase genes is critical for preventing the spread of these genes.

genomics↗

bioRxiv2023

Potential intrahospital dissemination of Pseudomonas aeruginosa carrying the blaIMP-1 gene within a Tn7-like transposon

We aimed to determine the molecular characteristics of carbapenem-resistant Pseudomonas aeruginosa 18081308 and 18083286 isolated from the urine and sputum of two Chinese patients respectively, and analyzed the formation mechanism of the genetic environment in which it carries blaIMP-1. Bacterial genome sequencing was carried out on strains 18081308 and 18083286 to obtain their whole genome sequence. Average nucleotide identity (ANI) was used for their precise species identification. Serotyping and multilocus sequence typing were performed. Furthermore, the acquired resistance genes, and virulence factors of these strains were identified. The carbapenem-resistant P. aeruginosa strains isolated in the present study were of sequence type ST865 and serotype O6. They all carried the same virulence factors (PLC, ExoSTY) and resistance genes (aacC2, tmrB, and blaIMP-1). Tn6411, a Tn7-like transposon carrying blaIMP-1, was found in both strains. Detailed genetic dissection was applied to this transposon to display the genetic environment of blaIMP-1. The aacC2-tmrB region remnant-Tn6411 backbone was the original structure of this type of transposon. A Tn402-like type 1 integron (intl1-aac(6)-II-blaIMP-1) was inserted into it and formed a stable structure, which was localized in the chromosome by TnsD for transmission within P. aeruginosa; the original structure of Tn7-like transposon was localized on the plasmid by TnsE for horizontal transmission between bacterial species. The intrahospital dissemination of P. aeruginosa ST865 isolated in this study was episodic. The blaIMP-1-carrying Tn7-like transposon might enhance their ability to survive under drug selection pressure and aggravate the difficulty in treating infections.

genomics↗

bioRxiv2023

Diversity and adaptability of RNA viruses in rice planthopper, Laodelphax striatellus

Although a large number of insect-specific viruses (ISVs) have recently been discovered from hematophagous insect, studies on ISV diversity and their association with phytophagous insect hosts were still insufficient. A systematic RNA virome investigation was performed for an important plant virus vector, small brown planthopper (SBPH), Laodelphax striatellus. A total number of 22 RNA viruses (including 17 novel viruses) belonging to various families were successfully identified and characterized. Subsequent analysis indicated that the overall RNA virus transcripts per million (TPM) in SBPH was relatively consistent throughout various different developmental stages of the insects, although the titers of individual viruses differ among different insect tissues, suggesting a delicate balance between ISVs and insect hosts. Moreover, analysis of virus-derived small interfering RNA (siRNA) demonstrated that siRNA mediated antiviral immune response of SBPH was activated in response to the replication of the discovered RNA viruses. Additionally, evaluation for potential cross-species ability of SBPH-ISVs showed that certain SBPH ISVs could successfully infect and replicate in another two rice planthoppers, the brown planthopper and the white-backed planthopper, through microinjection. In conclusion, the RNA virome and their adaptability in SBPH revealed in this study will contribute to a better understanding of the intimate relationship between ISVs and the host insects.

microbiology↗