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277 result(s) for "Ma, Mengqi"
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A designer rice NLR immune receptor confers resistance to the rice blast fungus carrying noncorresponding avirulence effectors
Plant nucleotide-binding and leucine-rich repeat (NLR) receptors recognize avirulence effectors directly through their integrated domains (IDs) or indirectly via the effector-targeted proteins. Previous studies have succeeded in generating designer NLR receptors with new recognition profiles by engineering IDs or targeted proteins based on prior knowledge of their interactions with the effectors. However, it is yet a challenge to design a new plant receptor capable of recognizing effectors that function by unknown mechanisms. Several rice NLR immune receptors, including RGA5, possess an integrated heavy metal–associated (HMA) domain that recognizes corresponding Magnaporthe oryzae Avrs and ToxB-like (MAX) effectors in the rice blast fungus. Here, we report a designer rice NLR receptor RGA5HMA2 carrying an engineered, integrated HMA domain (RGA5-HMA2) that can recognize the noncorresponding MAX effector AvrPib and confers the RGA4-dependent resistance to the M. oryzae isolates expressing AvrPib, which originally triggers the Pib-mediated blast resistance via unknown mechanisms. The RGA5-HMA2 domain is contrived based on the high structural similarity of AvrPib with two MAX effectors, AVR-Pia and AVR1-CO39, recognized by cognate RGA5-HMA, the binding interface between AVR1-CO39 and RGA5-HMA, and the distinct surface charge of AvrPib and RAG5-HMA. This work demonstrates that rice NLR receptors with the HMA domain can be engineered to confer resistance to the M. oryzae isolates noncorresponding but structurally similar MAX effectors, which manifest cognate NLR receptor–mediated resistance with unknown mechanisms. Our study also provides a practical approach for developing rice multilines and broad race spectrum–resistant cultivars by introducing a series of engineered NLR receptors.
Specific recognition of two MAX effectors by integrated HMA domains in plant immune receptors involves distinct binding surfaces
The structurally conserved but sequence-unrelated MAX (Magnaporthe oryzae avirulence and ToxB-like) effectors AVR1-CO39 and AVR-PikD from the blast fungus M. oryzae are recognized by the rice nucleotide-binding domain and leucine-rich repeat proteins (NLRs) RGA5 and Pikp-1, respectively. This involves, in both cases, direct interaction of the effector with a heavy metal-associated (HMA) integrated domain (ID) in the NLR. Here, we solved the crystal structures of a C-terminal fragment of RGA5 carrying the HMA ID (RGA5_S), alone, and in complex with AVR1-CO39 and compared it to the structure of the Pikp1HMA/AVR-PikD complex. In both complexes, HMA ID/MAX effector interactions involve antiparallel alignment of β-sheets from each partner. However, effector-binding occurs at different surfaces in Pikp1HMA and RGA5HMA, indicating that these interactions evolved independently by convergence of these two MAX effectors to the same type of plant target proteins. Interestingly, the effector-binding surface in RGA5HMA overlaps with the surface that mediates RGA5HMA self-interaction. Mutations in the HMA-binding interface of AVR1-CO39 perturb RGA5HMA-binding, in vitro and in vivo, and affect the recognition of M. oryzae in a rice cultivar containing Pi-CO39. Our study provides detailed insight into the mechanisms of effector recognition by NLRs, which has substantial implications for future engineering of NLRs to expand their recognition specificities. In addition, we propose, as a hypothesis for the understanding of effector diversity, that in the structurally conserved MAX effectors the molecular mechanism of host target protein-binding is conserved rather than the host target proteins themselves.
The synthetic NLR RGA5HMA5 requires multiple interfaces within and outside the integrated domain for effector recognition
Some plant sensor nucleotide-binding leucine-rich repeat (NLR) receptors detect pathogen effectors through their integrated domains (IDs). Rice RGA5 sensor NLR recognizes its corresponding effectors AVR-Pia and AVR1-CO39 from the blast fungus Magnaporthe oryzae through direct binding to its heavy metal-associated (HMA) ID to trigger the RGA4 helper NLR-dependent resistance in rice. Here, we report a mutant of RGA5 named RGA5 HMA5 that confers complete resistance in transgenic rice plants to the M. oryzae strains expressing the noncorresponding effector AVR-PikD. RGA5 HMA5 carries three engineered interfaces, two of which lie in the HMA ID and the other in the C-terminal Lys-rich stretch tailing the ID. However, RGA5 variants having one or two of the three interfaces, including replacing all the Lys residues with Glu residues in the Lys-rich stretch, failed to activate RGA4-dependent cell death of rice protoplasts. Altogether, this work demonstrates that sensor NLRs require a concerted action of multiple surfaces within and outside the IDs to both recognize effectors and activate helper NLR-mediated resistance, and has implications in structure-guided designing of sensor NLRs. An engineered sensor NLR RGA5 HMA5 carrying multiple resurfaced interfaces was generated to confer complete resistance to the rice blast fungus strains expressing the non-corresponding effector AVR-PikD, paving a way to broaden the resistance spectra of NLRs.
Allelic strengths of encephalopathy-associated UBA5 variants correlate between in vivo and in vitro assays
Protein UFMylation downstream of the E1 enzyme UBA5 plays essential roles in development and endoplasmic reticulum stress. Variants in the UBA5 gene are associated with developmental and epileptic encephalopathy 44 (DEE44), an autosomal recessive disorder characterized by early-onset encephalopathy, movement abnormalities, global developmental delay, intellectual disability, and seizures. DEE44 is caused by at least 12 different missense variants described as loss of function (LoF), but the relationships between genotypes and molecular or clinical phenotypes remain to be established. We developed a humanized UBA5 fly model and biochemical activity assays in order to describe in vivo and in vitro genotype–phenotype relationships across the UBA5 allelic series. In vivo, we observed a broad spectrum of phenotypes in viability, developmental timing, lifespan, locomotor activity, and bang sensitivity. A range of functional effects was also observed in vitro across comprehensive biochemical assays for protein stability, ATP binding, UFM1 activation, and UFM1 transthiolation. Importantly, there is a strong correlation between in vivo and in vitro phenotypes, establishing a classification of LoF variants into mild, intermediate, and severe allelic strengths. By systemically evaluating UBA5 variants across in vivo and in vitro platforms, this study provides a foundation for more basic and translational UBA5 research, as well as a basis for evaluating current and future individuals afflicted with this rare disease. Although rare diseases only impact a small fraction of the population, they still affect hundreds of millions of people around the world. Many of these conditions are caused by variations in inherited genetic material, which nowadays can be readily detected using advanced sequencing technologies. However, establishing a connection between these genetic changes and the disease they cause often requires further in-depth study. One such rare inherited disorder is developmental and epileptic encephalopathy type 44 (DEE44), which is caused by genetic variations within the gene for UBA5 (short for ubiquitin-like modifier activating enzyme 5). For DEE44 to occur, both copies of the gene for UBA5, known as alleles, must contain one or more detrimental variation. Although all these variations prevent UBA5 from working correctly, the level of disruption they cause, known as allelic strength, varies between them. However, it remained unclear whether the severity of the DEE44 disease directly corresponds with the allelic strength of these variants. To answer this question, Pan et al. tested how different genetic variants found in patients with DEE44 affected the behavior and health of fruit flies. These results were then compared against in vitro biochemical assays testing how alleles containing these variants impacted the function of UBA5. When the fly gene for the enzyme was replaced with the human gene containing variations associated with DEE44, flies exhibited changes in their survival rates, developmental progress, lifespan, and neurological well-being. However, not all of the variants caused ill effects. Using this information, the patient variants were classified into three categories based on the severity of their effect: mild, intermediate, and severe. Biochemical assays supported this classification and revealed that the variants that caused more severe symptoms tended to inhibit the activity of UBA5 more significantly. Pan et al. further analyzed the nature of the variants in the patients and showed that most patients typically carried one mild and one strong variant , although some individuals did have two intermediate variants. Notably, no patients carried two severe variants. This indicates that DEE44 is the result of UBA5 only partially losing its ability to work correctly. The study by Pan et al. provides a framework for assessing the impact of genetic variants associated with DEE44, aiding the diagnosis and treatment of the disorder. However, further research involving more patients, more detailed clinical data, and testing other newly identified DEE44-causing variants is needed to solidify the correlation between allelic strength and disease severity.
Dissection of Nidogen function in Drosophila reveals tissue-specific mechanisms of basement membrane assembly
Basement membranes (BMs) are thin sheet-like specialized extracellular matrices found at the basal surface of epithelia and endothelial tissues. They have been conserved across evolution and are required for proper tissue growth, organization, differentiation and maintenance. The major constituents of BMs are two independent networks of Laminin and Type IV Collagen in addition to the proteoglycan Perlecan and the glycoprotein Nidogen/entactin (Ndg). The ability of Ndg to bind in vitro Collagen IV and Laminin, both with key functions during embryogenesis, anticipated an essential role for Ndg in morphogenesis linking the Laminin and Collagen IV networks. This was supported by results from cultured embryonic tissue experiments. However, the fact that elimination of Ndg in C. elegans and mice did not affect survival strongly questioned this proposed linking role. Here, we have isolated mutations in the only Ndg gene present in Drosophila. We find that while, similar to C.elegans and mice, Ndg is not essential for overall organogenesis or viability, it is required for appropriate fertility. We also find, alike in mice, tissue-specific requirements of Ndg for proper assembly and maintenance of certain BMs, namely those of the adipose tissue and flight muscles. In addition, we have performed a thorough functional analysis of the different Ndg domains in vivo. Our results support an essential requirement of the G3 domain for Ndg function and unravel a new key role for the Rod domain in regulating Ndg incorporation into BMs. Furthermore, uncoupling of the Laminin and Collagen IV networks is clearly observed in the larval adipose tissue in the absence of Ndg, indeed supporting a linking role. In light of our findings, we propose that BM assembly and/or maintenance is tissue-specific, which could explain the diverse requirements of a ubiquitous conserved BM component like Nidogen.
Investigating the Occurrence of Viruses in Sweet Cherry in China and Developing Multiplex RT-PCR Assays for Their Detection
Sweet cherry (Prunus avium L.) cultivation in China covers an estimated area of 25,600 hectares, representing more than one-third of the global total. Viral diseases present a serious challenge to cherry production worldwide; however, the phytosanitary status of sweet cherry in China has remained poorly understood. In this study, 191 sweet cherry samples were collected from major growing regions and screened using RT-PCR combined with DNA sequencing for the presence of 14 viruses previously reported in China. Results revealed that 80.1% of the tested samples were infected with at least one virus, with mixed infections detected in 51.3% of the samples. Prevalent viruses included cherry virus A (CVA, 53.4%), prunus necrotic ringspot virus (PNRSV, 35.1%), cherry green ring mottle virus (CGRMV, 32.5%), plum bark necrosis stem pitting-associated virus (PBNSPaV, 31.4%), and prune dwarf virus (PDV, 10.5%). Cherry necrotic rusty mottle virus (CNRMV) was found at a very low frequency (0.5%), and the remaining eight viruses were not detected in any sample. Based on these findings, we developed multiplex RT-PCR assays for simultaneous detection of CVA, PNRSV, CGRMV, PBNSPaV, and PDV. Several dual and triplex RT-PCR systems were successfully established, including combinations such as PBNSPaV/PNRSV, CVA/PDV, CVA/CGRMV, PBNSPaV/PDV/CGRMV, and PBNSPaV/PNRSV/PDV. This study identifies CVA, PNRSV, CGRMV, PBNSPaV, and PDV as the prevalent viruses in the investigated Chinese sweet cherry orchards. Accordingly, multiplex RT-PCR assays were developed for their simultaneous detection. Our work advances the understanding of sweet cherry viral diseases in China and provides a valuable complementary tool for the existing diagnostic toolkit.
Nonvolatile Organic Floating-Gate Memory Using N2200 as Charge-Trapping Layer
In this work, floating-gate organic field-effect transistor memory using the n-type semiconductor poly-[N,N′-bis(2-octyldodecyl) naphthalene-1,4,5,8-bis (dicarbo- ximide)-2,6-dili]-alt-5,5′-(2,2′-bithiophene) (N2200) as a charge-trapping layer is presented. With the assistance of a technology computer-aided design (TCAD) tool (Silvaco-Atlas), the storage characteristics of the device are numerically simulated by using the carrier injection and Fower–Nordheim (FN) tunneling models. The shift in the transfer characteristic curves and the charge-trapping mechanism after programming/erasing (P/E) operations under different P/E voltages and different pulse operation times are discussed. The impacts of different thicknesses of the tunneling layer on storage characteristics are also analyzed. The results show that the memory window with a tunneling layer thickness of 8 nm is 16.1 V under the P/E voltage of ±45 V, 5 s. After 1000 cycle tests, the memory shows good fatigue resistance, and the read current on/off ratio reaches 103.
Two lysosomal genes ATP13A2 and GBA1 interact to drive neurodegeneration
Background Parkinson’s disease (PD) is a genetically complex disorder in which combinations of heterozygous risk variants may contribute to pathogenesis. Many PD risk loci encode lysosomal genes, such as GBA1 , a common and potent risk factor, conferring at least a 5-fold increase. However, the mechanisms of GBA1 penetrance remain poorly understood. Methods Using Drosophila melanogaster , we performed a genetic interaction screen of lysosomal storage disorder (LSD) genes to identify dominant modifiers of Gba1b (fly homolog of GBA1 ). Age-dependent locomotor assessments, electroretinograms (ERG), transmission electron microscopy (TEM) analyses and quantification of dopaminergic (DA) neurons were used to assess the neurodegenerative phenotypes of double heterozygous animals. By combining immunostaining, lipidomics, metabolomics and pharmacological approaches we showed how partial loss of anne (fly homolog of ATP13A2 ) and Gba1b drives neurodegeneration. By interrogating genetic data from local and international PD cohorts we identified double heterozygous pathogenic variants in ATP13A2 and GBA1 in individuals with PD. Results We show that anne is expressed in neurons, whereas Gba1b is expressed in glia. Flies heterozygous for anne exhibit mild neurodegenerative phenotypes, and Gba1b strongly enhances this haploinsufficiency. Double heterozygous ( Gba1b T2A /+;anne T2A /+ ) flies exhibit a slow and progressive neurodegeneration associated with accumulation and impaired acidification of lysosomes in photoreceptors and other neurons. Obvious morphological defects are first observed in glia at day 15 after eclosion and include vacuolization and neuronal detachment. These defects are accompanied by an elevation of glucosylceramide (GlcCer) and followed by loss of neuronal function and degenerative features by day 30. These phenotypes are neuronal activity-dependent. The neurodegenerative phenotypes are rescued by: ML-SA1, an agonist of the lysosomal TRPML1 channel that has been reported to promote lysosomal membrane trafficking; myriocin, a compound that inhibits GlcCer production; and DFMO, a drug which inhibits polyamine synthesis. Based on surveys of genetic data, we identify multiple PD cases harboring digenic variants in GBA1 and ATP13A2 . Conclusions Our study reveals that partial loss of Gba1b in glia and anne in neurons synergistically disrupts lysosomal pH and neuron-glia GlcCer homeostasis, triggering neurodegeneration. Our results provide evidence that GBA1 penetrance is influenced by additional genetic modifiers, consistent with a putative digenic mechanism for GBA1 -PD penetrance. These findings highlight lysosomal acidification, sphingolipid clearance, and polyamine regulation as critical intervention points in digenic PD.
Hydration Mechanism of Solid Waste Gelling Materials Containing Semi-Dry Desulfurization Ash
This study investigated the feasibility of using semi-dry desulfurization ash (DA) in combination with blast furnace slag (BFS) to prepare gelling materials, aiming to improve the resource utilization of DA. The effects of DA dosage and mechanical grinding on the compressive strength and hydration mechanism of BFS-DA gelling materials were investigated. The results showed that the optimum BFS-DA ratio was 60:40, and the compressive strengths were 14.21 MPa, 20.24 MPa, 43.50 MPa, and 46.27 MPa at 3, 7, 28, and 56 days, respectively. Mechanical grinding greatly improved the activity of the gel materials, with the greatest increase in compressive strength at 3, 7, 28, and 90 days for the BFS and DA mixed milled for 30 min, with increases of 89.86%, 66.36%, 24.56%, and 25.68%, respectively, and compressive strength of 26.22 MPa, 35.6 MPa, 58.33 MPa, and 63.97 MPa, respectively. The cumulative heat of hydration of BFS-DA slurry was about 120 J/g. The hydration mechanism showed that the main hydration products formed were ettringite, C-S-H gel, AFm, and Friedel’s salt. Calcium sulfite in DA was participated in the hydration, and a new hydration product, Ca4Al2O6SO3·11H2O, was formed. DA can be effectively used to prepare BFS-based gelling materials, and its performance meets the requirements of GB/T 28294-2024 standard, which provides a potential solution for the utilization of DA resources and the reduction in the impact on the environment.
Heterozygous variants in PLCG1 affect hearing, vision, cardiac, and immune function
Phospholipase C isozymes (PLCs) hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP 2 ) into inositol 1,4,5-trisphosphate (IP 3 ) and diacylglycerol (DAG), important signaling molecules involved in many cellular processes including Ca 2+ release from the endoplasmic reticulum (ER). PLCG1 encodes the PLCγ1 isozyme that is broadly expressed. Hyperactive somatic mutations of PLCG1 are observed in multiple cancers, but only one germline variant has been reported. Here, we describe seven individuals with heterozygous missense variants in PLCG1 [p.(Asp1019Gly), p.(His380Arg), p.(Asp1165Gly), and p.(Leu597Phe)] who present with hearing impairment (5/7), ocular pathology (4/7), cardiac septal defects (3/6), and various immunological issues (5/7). To model these variants in vivo , we generated the analogous variants in the Drosophila ortholog, small wing ( sl ). We created a null allele sl T2A and assessed its expression pattern. sl is broadly expressed, including wing discs, eye discs, and a subset of neurons and glia. sl T2A mutant flies exhibit wing size reductions, ectopic wing veins, and supernumerary photoreceptors. We document that mutant flies also exhibit a reduced lifespan and age-dependent locomotor defects. Expressing wild-type sl in sl T2A mutant flies rescues the loss-of-function phenotypes, whereas the variants increase lethality. Ectopic expression of an established hyperactive PLCG1 variant, p.(Asp1165His) in the wing pouch causes elevated Ca 2+ activity and severe wing phenotypes. These phenotypes are also observed when the p.(Asp1019Gly) or p.(Asp1165Gly) variants are overexpressed in the wing pouch, arguing that these are gain-of-function variants. However, the wing phenotypes associated with p.(His380Arg) or p.(Leu597Phe) overexpression are either mild or only partially penetrant. Our data suggest that the heterozygous missense variants reported here affect protein function differentially and contribute to the clinical features observed in the affected individuals.