A PARylation-phosphorylation cascade promotes TOPBP1 loading and RPA-RAD51 exchange in homologous recombination.

The efficiency of homologous recombination (HR) in the repair of DNA double-strand breaks (DSBs) is closely associated with genome stability and tumor response to chemotherapy. While many factors have been functionally characterized in HR, such as TOPBP1, their precise regulation remains unclear. Here, we report that TOPBP1 interacts with the RNA-binding protein HTATSF1 in a cell-cycle- and phosphorylation-dependent manner. Mechanistically, CK2 phosphorylates HTATSF1 to facilitate binding to TOPBP1, which promotes S-phase-specific TOPBP1 recruitment to damaged chromatin and subsequent RPA/RAD51-dependent HR, genome integrity, and cancer-cell viability. The localization of HTATSF1-TOPBP1 to DSBs is potentially independent of the transcription-coupled RNA-binding and processing capacity of HTATSF1 but rather relies on the recognition of poly(ADP-ribosyl)ated RPA by HTATSF1, which can be blunted with PARP inhibitors. Together, our study provides a mechanistic insight into TOPBP1 loading at HR-prone DSB sites via HTATSF1 and reveals how RPA-RAD51 exchange is tuned by a PARylation-phosphorylation cascade.

tRNA modification enzyme MiaB connects environmental cues to activation of Pseudomonas aeruginosa type III secretion system.

Pseudomonas aeruginosa, a major inhabitant of numerous environmental reservoirs, is a momentous opportunistic human pathogen associated with severe infections even death in the patients suffering from immune deficiencies or metabolic diseases. Type III secretion system (T3SS) employed by P. aeruginosa to inject effector proteins into host cells is one of the pivotal virulence factors pertaining to acute infections caused by this pathogen. Previous studies showed that P. aeruginosa T3SS is regulated by various environmental cues such as calcium concentration and the host signal spermidine. However, how T3SS is regulated and expressed particularly under the ever-changing environmental conditions remains largely elusive. In this study, we reported that a tRNA modification enzyme PA3980, designated as MiaB, positively regulated T3SS gene expression in P. aeruginosa and was essential for the induced cytotoxicity of human lung epithelial cells. Further genetic assays revealed that MiaB promoted T3SS gene expression by repressing the LadS-Gac/Rsm signaling pathway and through the T3SS master regulator ExsA. Interestingly, ladS, gacA, rsmY and rsmZ in the LadS-Gac/Rsm signaling pathway seemed potential targets under the independent regulation of MiaB. Moreover, expression of MiaB was found to be induced by the cAMP-dependent global regulator Vfr as well as the spermidine transporter-dependent signaling pathway and thereafter functioned to mediate their regulation on the T3SS gene expression. Together, these results revealed a novel regulatory mechanism for MiaB, with which it integrates different environmental cues to modulate T3SS gene expression in this important bacterial pathogen.

Retrospective study about clinical severity and epidemiological analysis of the COVID-19 Omicron subvariant lineage-infected patients in Hohhot, China.

BACKGROUND: Fear of a global public health issue and fresh infection wave in the persistent COVID-19 pandemic has been enflamed by the appearance of the novel variant Omicron BF.7 lineage. Recently, it has been seeing the novel Omicron subtype BF.7 lineage has sprawled exponentially in Hohhot. More than anything, risk stratification is significant to ascertain patients infected with COVID-19 who the most need in-hospital or in-home management. The study intends to understand the clinical severity and epidemiological characteristics of COVID-19 Omicron subvariant BF.7. lineage via gathering and analyzing the cases with Omicron subvariant in Hohhot, Inner Mongolia. METHODS: Based upon this, we linked variant Omicron BF.7 individual-level information including sex, age, symptom, underlying conditions and vaccination record. Further, we divided the cases into various groups and assessed the severity of patients according to the symptoms of patients with COVID-19. Clinical indicators and data might help to predict disadvantage outcomes and progression among Omicron BF.7 patients. RESULTS: In this study, in patients with severe symptoms, some indicators from real world data such as white blood cells, AST, ALT and CRE in patients with Omicron BF.7 in severe symptoms were significantly higher than mild and asymptomatic patients, while some indicators were significantly lower. CONCLUSIONS: Above results suggested that the indicators were associated with ponderance of clinical symptoms. Our survey emphasized the value of timely investigations of clinical data obtained by systemic study to acquire detailed information.

Native CRISPR-Cas-based programmable multiplex gene repression in Klebsiella variicola.

Klebsiella variicola is a Gram-negative bacterium that is frequently isolated from a wide variety of natural niches. It is a ubiquitous opportunistic pathogen that can cause diverse infections in plants, animals, and humans. It also has significant biotechnological potential. However, due to the lack of efficient genetic tools, the molecular basis contributing to the pathogenesis and beneficial activities of K. variicola remains poorly understood. In this study, we found and characterized a native type I-E CRISPR-Cas system in a recently isolated K. variicola strain KV-1. The system cannot cleave target DNA sequences due to the inactivation of the Cas3 nuclease by a transposable element but retains the activity of the crRNA-guided Cascade binding to the target DNA sequence. A targeting plasmid carrying a mini-CRISPR to encode a crRNA was designed and introduced into the KV-1 strain, which successfully repurposed the native type I-E CRISPR-Cas system to inhibit the expression of the target gene efficiently and specifically. Moreover, by creating a mini-CRISPR to encode multiple crRNAs, multiplex gene repression was achieved by providing a single targeting plasmid. This work provides the first native CRISPR-Cas-based tool for programmable multiplex gene repression in K. variicola, which will facilitate studying the pathogenic mechanism of K. variicola and enable metabolic engineering to produce valuable bioproducts.

Bacillaene, sharp objects consist in the arsenal of antibiotics produced by Bacillus.

Bacillus species act as plant growth-promoting rhizobacteria (PGPR) that can produce a large number of bioactive metabolites. Bacillaene, a linear polyketide/nonribosomal peptide produced by Bacillus strains, is synthesized by the trans-acyltransferase polyketide synthetase. The complexity of the chemical structure, particularity of biosynthesis, potent bioactivity, and the important role of competition make Bacillus an ideal antibiotic weapon to resist other microbes and maintain the optimal rhizosphere environment. This review provides an updated view of the structural features, biological activity, biosynthetic regulators of biosynthetic pathways, and the important competitive role of bacillaene during Bacillus survival.

STRONG STAYGREEN inhibits DNA binding of PvNAP transcription factors during leaf senescence in switchgrass.

Fine tuning the progression of leaf senescence is important for plant fitness in nature, while the "staygreen" phenotype with delayed leaf senescence has been considered a valuable agronomic trait in crop genetic improvement. In this study, a switchgrass (Panicum virgatum L.) CCCH-type Zinc finger gene, Strong Staygreen (PvSSG), was characterized as a suppressor of leaf senescence as overexpression or suppression of the gene led to delayed or accelerated leaf senescence, respectively. Transcriptomic analysis marked that chlorophyll (Chl) catabolic pathway genes were involved in the PvSSG-regulated leaf senescence. PvSSG was identified as a nucleus-localized protein with no transcriptional activity. By yeast two-hybrid screening, we identified its interacting proteins, including a pair of paralogous transcription factors, PvNAP1/2 (NAC-LIKE, ACTIVATED BY AP3/PI). Overexpression of PvNAPs led to precocious leaf senescence at least partially by directly targeting and transactivating Chl catabolic genes to promote Chl degradation. PvSSG, through protein-protein interaction, repressed the DNA-binding efficiency of PvNAPs and alleviated its transactivating effect on downstream genes, thereby functioning as a "brake" in the progression of leaf senescence. Moreover, overexpression of PvSSG resulted in up to 47% higher biomass yield and improved biomass feedstock quality, reiterating the importance of leaf senescence regulation in the genetic improvement of switchgrass and other feedstock crops.

The NAC factor LpNAL delays leaf senescence by repressing two chlorophyll catabolic genes in perennial ryegrass.

Expression of chlorophyll (Chl) catabolic genes during leaf senescence is tightly controlled at the transcriptional level. Here, we identified a NAC family transcription factor, LpNAL, involved in regulating Chl catabolic genes via the yeast one-hybrid system based on truncated promoter analysis of STAYGREEN (LpSGR) in perennial ryegrass (Lolium perenne L.). LpNAL was found to be a transcriptional repressor, directly repressing LpSGR as well as the Chl b reductase gene, NONYELLOWING COLORING1. Perennial ryegrass plants over-expressing LpNAL exhibited delayed leaf senescence or stay-green phenotypes, whereas knocking down LpNAL using RNA interference accelerated leaf senescence. Comparative transcriptome analysis of leaves at 30 d after emergence in wild-type, LpNAL-overexpression, and knock-down transgenic plants revealed that LpNAL-regulated stay-green phenotypes possess altered light reactions of photosynthesis, antioxidant metabolism, ABA and ethylene synthesis and signaling, and Chl catabolism. Collectively, the transcriptional repressor LpNAL targets both Chl a and Chl b catabolic genes and acts as a brake to fine-tune the rate of Chl degradation during leaf senescence in perennial ryegrass.

Pathogen Profile of Klebsiella variicola, the Causative Agent of Banana Sheath Rot.

Banana (Musa spp.) is an important fruit and food crop worldwide. In recent years, banana sheath rot has become a major problem in banana cultivation, causing plant death and substantial economic losses. Nevertheless, the pathogen profile of this disease has not been fully characterized. Klebsiella variicola is a versatile bacterium capable of colonizing different hosts, such as plants, humans, insects, and animals, and is recognized as an emerging pathogen in various hosts. In this study, we obtained 12 bacterial isolates from 12 different banana samples showing banana sheath rot in Guangdong and Guangxi Provinces, China. Phylogenetic analysis based on 16S rRNA sequences confirmed that all 12 isolates were K. variicola strains. We sequenced the genomes of these strains, performed comparative genomic analysis with other sequenced K. variicola strains, and found a lack of consistency in accessory gene content among these K. variicola strains. However, prediction based on the pan-genome of K. variicola revealed 22 unique virulence factors carried by the 12 pathogenic K. variicola isolates. Microbiome and microbial interaction network analysis of endophytes between the healthy tissues of diseased plants and healthy plants of two cultivars showed that Methanobacterium negatively interacts with Klebsiella in banana plants and that Herbaspirillum might indirectly inhibit Methanobacterium to promote Klebsiella growth. These results suggest that banana sheath rot is caused by the imbalance of plant endophytes and opportunistic pathogenic bacteria, providing an important basis for research and control of this disease.[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Overexpression of Lolium multiflorum LmMYB1 Enhances Drought Tolerance in Transgenic Arabidopsis.

Lolium multiflorum is one of the world-famous forage grasses with rich biomass, fast growth rate and good nutritional quality. However, its growth and forage yield are often affected by drought, which is a major natural disaster all over the world. MYB transcription factors have some specific roles in response to drought stress, such as regulation of stomatal development and density, control of cell wall and root development. However, the biological function of MYB in L. multiflorum remains unclear. Previously, we elucidated the role of LmMYB1 in enhancing osmotic stress resistance in Saccharomyces cerevisiae. Here, this study elucidates the biological function of LmMYB1 in enhancing plant drought tolerance through an ABA-dependent pathway involving the regulation of cell wall development and stomatal density. After drought stress and ABA stress, the expression of LmMYB1 in L. multiflorum was significantly increased. Overexpression of LmMYB1 increased the survival rate of Arabidopsis thaliana under drought stress. Under drought conditions, expression levels of drought-responsive genes such as AtRD22, AtRAB and AtAREB were up-regulated in OE compared with those in WT. Further observation showed that the stomatal density of OE was reduced, which was associated with the up-regulated expression of cell wall-related pathway genes in the RNA-Seq results. In conclusion, this study confirmed the biological function of LmMYB1 in improving drought tolerance by mediating cell wall development through the ABA-dependent pathway and thereby affecting stomatal density.

NOL-mediated functional stay-green traits in perennial ryegrass (Lolium perenne L.) involving multifaceted molecular factors and metabolic pathways regulating leaf senescence.

Loss of chlorophyll (Chl) is a hallmark of leaf senescence, which may be regulated by Chl catabolic genes, including NON-YELLOW COLORING 1 (NYC1)-like (NOL). The objective of this study was to determine molecular factors and metabolic pathways underlying NOL regulation of leaf senescence in perennial grass species. LpNOL was cloned from perennial ryegrass (Lolium perenne L.) and found to be highly expressed in senescent leaves. Transient overexpression of LpNOL accelerated leaf senescence and Chl b degradation in Nicotiana benthamiana. LpNOL RNA interference (NOLi) in perennial ryegrass not only significantly blocked Chl degradation in senescent leaves, but also delayed initiation and progression of leaf senescence. This study found that NOL, in addition to functioning as a Chl b reductase, could enact the functional stay-green phenotype in perennial grass species, as manifested by increased photosynthetic activities in NOLi plants. Comparative transcriptomic analysis revealed that NOL-mediated functional stay-green in perennial ryegrass was mainly achieved through the modulation of Chl catabolism, light harvesting for photosynthesis, photorespiration, cytochrome respiration, carbohydrate catabolism, oxidative detoxification, and abscisic acid biosynthesis and signaling pathways.

RasI/R Quorum Sensing System Controls the Virulence of Ralstonia solanacearum Strain EP1.

Quorum sensing (QS) is a widely conserved bacterial regulatory mechanism that relies on production and perception of autoinducing chemical signals to coordinate diverse cooperative activities, such as virulence, exoenzyme secretion, and biofilm formation. In Ralstonia solanacearum, a phytopathogen causing severe bacterial wilt diseases in many plant species, previous studies identified the PhcBSR QS system, which plays a key role in regulation of its physiology and virulence. In this study, we found that R. solanacearum strain EP1 contains the genes encoding uncharacterized LuxI/LuxR (LuxI/R) QS homologues (RasI/RasR [designated RasI/R here]). To determine the roles of the RasI/R system in strain EP1, we constructed a specific reporter for the signals catalyzed by RasI. Chromatography separation and structural analysis showed that RasI synthesized primarily N-(3-hydroxydodecanoyl)-homoserine lactone (3-OH-C12-HSL). In addition, we showed that the transcriptional expression of rasI is regulated by RasR in response to 3-OH-C12-HSL. Phenotype analysis unveiled that the RasI/R system plays a critical role in modulation of cellulase production, motility, biofilm formation, oxidative stress response, and virulence of R. solanacearum EP1. We then further characterized this system by determining the RasI/R regulon using transcriptome sequencing (RNA-seq) analysis, which showed that this newly identified QS system regulates the transcriptional expression of over 154 genes associated with bacterial physiology and pathogenic properties. Taken together, the findings from this study present an essential new QS system in regulation of R. solanacearum physiology and virulence and provide new insight into the complicated regulatory mechanisms and networks in this important plant pathogen. IMPORTANCE Quorum sensing (QS) is a key regulator of virulence factors in many plant-pathogenic bacteria. Previous studies unveiled two QS systems (i.e., PhcBSR and SolI/R) in several R. solanacearum strains. The PhcBSR QS system is known for its key roles in regulation of bacterial virulence, and the LuxI/LuxR (SolI/R) QS system appears dispensable for pathogenicity in a number of R. solanacearum strains. In this study, a new functional QS system (i.e., RasI/R) was identified and characterized in R. solanacearum strain EP1 isolated from infected eggplants. Phenotype analyses showed that the RasI/R system plays an important role in regulation of a range of biological activities associated with bacterial virulence. This QS system produces and responds to the QS signal 3-OH-C12-HSL and hence regulates critical bacterial abilities in survival and infection. To date, multiple QS signaling circuits in R. solanacearum strains are still not well understood. Our findings from this study provide new insight into the complicated QS regulatory networks that govern the physiology and virulence of R. solanacearum and present a valid target and clues for the control and prevention of bacterial wilt diseases.

Knock down of NON-YELLOW COLOURING 1-like gene or chlorophyllin application enhanced chlorophyll accumulation with antioxidant roles in suppressing heat-induced leaf senescence in perennial ryegrass.

Loss of chlorophyll and oxidative damage co-occur during heat-induced leaf senescence. This study aimed to determine the functions of a chlorophyll catabolic gene, NON-YELLOW COLOURING 1 (NYC1)-like (NOL), in regulating heat-induced leaf senescence and to characterize antioxidant roles of a chlorophyll derivative, sodium copper chlorophyllin (SCC), in suppressing heat-induced leaf senescence. In two separate experiments, one by comparing NOL RNAi transgenic and wild-type plants, and the other by analysing the effects of SCC treatment, perennial ryegrass (Lolium perenne) was exposed to heat stress (38/35 °C, day/night) or optimal temperature (25/20 °C). Results showed that both knock down of LpNOL and application of SCC suppressed heat-induced leaf senescence, as manifested by increased chlorophyll content, reduced electrolyte leakage, down-regulation of chlorophyll-catabolic genes and senescence-related genes, as well as enhanced antioxidant capacity in the peroxidase pathway for H2O2 scavenging. Ex vivo SCC incubation protected membranes from H2O2 damage in mesophyll protoplasts of perennial ryegrass. The suppression of leaf senescence by knocking down NOL or chlorophyllin application was associated with enhanced chlorophyll accumulation playing antioxidant roles in protecting leaves from heat-induced oxidative damage.

Resveratrol attenuates atherosclerotic endothelial injury through the Pin1/Notch1 pathway.

The present study investigates whether resveratrol could modulate the endothelial dysfunction of atherosclerosis via the Pin1/Notch1 signaling pathway. To assess the vascular endothelial cell (VECs) injury in mice, the levels of serum soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble E-selectin (sE-selectin), soluble thrombomodulin (sTM), and von Willebrand factor (vWF) were measured. Expressions of Pin1 and Notch1 intracellular domain (NICD1), both mRNA and protein, were also measured. Human umbilical vein endothelial cells (HUVECs) treated with 100 µg/mL oxidized low-density lipoprotein (ox-LDL) were incubated with resveratrol at doses from 10 µM to 40 µM. Cell function was evaluated by measuring apoptosis, cell viability, lipid accumulation, and adherent human myeloid leukemia mononuclear (THP-1) cells. Resveratrol intervention in AS mice decreased the expression of serum sVCAM-1, sICAM-1, sE-selectin, sTM, and vWF and dose-dependently down-regulated Pin1 and NICD1 mRNA and protein expression in endothelial cells. Resveratrol intervention reversed ox-LDL-induced cell dysfunction by increasing viability and decreasing apoptosis, lipid accumulation, and the adhesion of THP-1 cells. These beneficial effects were reversed by the overexpression of Pin1. Resveratrol regulates endothelial cell injury of atherosclerosis by inhibiting the Pin1/Notch1 signaling pathway, suggesting novel therapeutic targets for atherosclerosis treatment.

Endophytic Bacillus subtilis TR21 Improves Banana Plant Resistance to Fusarium oxysporum f. sp. cubense and Promotes Root Growth by Upregulating the Jasmonate and Brassinosteroid Biosynthesis Pathways.

The banana (Musa spp.) industry experiences dramatic annual losses from Fusarium wilt of banana disease, which is caused by the fungus Fusarium oxysporum f. sp. cubense (FOC). Pisang Awak banana 'Fenza No. 1' (Musa spp. cultivar Fenza No. 1), a major banana cultivar with high resistance to F. oxysporum f. sp. cubense race 4, is considered to be ideal for growth in problematic areas. However, 'Fenza No. 1' is still affected by F. oxysporum f. sp. cubense race 1 in the field. TR21 is an endophytic Bacillus subtilis strain isolated from orchids (Dendrobium sp.). Axillary spraying of banana plants with TR21 controls Fusarium wilt of banana, decreasing the growth period and increasing yields in the field. In this study, we established that TR21 increases root growth in different monocotyledonous plant species. By axillary inoculation, TR21 induced a similar transcriptomic change as that induced by F. oxysporum f. sp. cubense race 1 but also upregulated the biosynthetic pathways for the phytohormones brassinosteroid and jasmonic acid in 'Fenza No. 1' root tissues, indicating that TR21 increases Fusarium wilt of banana resistance, shortens growth period, and increases yield of banana by inducing specific transcriptional reprogramming and modulating phytohormone levels. These findings will contribute to the identification of candidate genes related to plant resistance against fungi in a nonmodel system and facilitate further study and exploitation of endophytic biocontrol agents.

DNA aptamers specific for Legionella pneumophila: systematic evolution of ligands by exponential enrichment in whole bacterial cells.

Legionella pneumophila is the major causative agent of Legionnaires' disease and Pontiac fever, which pose major public health problems. Rapid detection of L. pneumophila is important for global control of these diseases. Aptamers, short oligonucleotides that bind to targets with high affinity and specificity, have great potential for use in pathogenic bacterium detection, diagnostics, and therapy. Here, we used a whole-cell SELEX (systematic evolution of ligands by exponential enrichment) method to isolate and characterize single-stranded DNA (ssDNA) aptamers against L. pneumophila. A total of 60 ssDNA sequences were identified after 17 rounds of selection. Other bacterial species (Escherichia coli, Bacillus subtilis, Pseudomonas syringae, Staphylococcus aureus, Legionella quateirensis, and Legionella adelaidensis) were used for counterselection to enhance the specificity of ssDNA aptamers against L. pneumophila. Four ssDNA aptamers showed strong affinity and high selectivity for L. pneumophila, with Kd values in the nanomolar range. Bioinformatic analysis of the most specific aptamers revealed predicted conserved secondary structures that might bind to L. pneumophila cell walls. In addition, the binding of these four fluorescently labeled aptamers to the surface of L. pneumophila was observed directly by fluorescence microscopy. These aptamers identified in this study could be used in the future to develop medical diagnostic tools and public environmental detection assays for L. pneumophila.

Comparative genomics analysis of two banana Fusarium wilt biocontrol endophytes Bacillus subtilis R31 and TR21 provides insights into their differences on phytobeneficial trait.

Fusarium wilt of banana is considered one of the most destructive plant diseases. Bacillus subtilis R31 and TR21, isolated from Dendrobium sp. leaves, exhibit different phytobeneficial effects on banana Fusarium wilt bio-controlling. Here, we performed genome sequencing and comparative genomics analysis of R31 and TR21 to enhance our understanding of the different phytobeneficial traits. These results revealed that the strain-specific genes of R31 involved in sporulation, quorum sensing, and antibiotic synthesis allow R31 to present a better capacity of sporulation, rhizosphere adaptation, and quorum sensing than TR21. Selective pressure analysis indicated that the glycosylase and endo-alpha-(1- > 5)-L-arabinanase genes were strong positive selected, which may contribute to the TR21 to colonize well in banana's vascular bundles. Altogether, our findings presented here should advance further agricultural application of R31 and TR21 as two promising resources of plant growth promotion and biological control via genetic engineering.

LpNOL-knockdown suppression of heat-induced leaf senescence in perennial ryegrass involving regulation of amino acid and organic acid metabolism.

The nonyellow COLORING 1-like gene (NOL) is known for its roles in accelerating leaf senescence, but the underlying metabolic mechanisms for heat-induced leaf senescence remain unclear. The objectives of this study were to identify metabolites and associated metabolic pathways regulated by knockdown of NOL in perennial ryegrass (Lolium perenne) and to determine the metabolic mechanisms of NOL controlling heat-induced leaf senescence. Wild-type (WT; cv. "Pinnacle") and two lines (Noli-1 and Noli-2) of perennial ryegrass with LpNOL knockdown were exposed to heat stress at 35/33°C (day/night) or nonstress control temperatures at 25/22°C (day/night) for 30 days in growth chambers. Leaf electrolyte leakage, chlorophyll (Chl) content, photochemical efficiency (Fv /Fm ), and net photosynthetic rate (Pn) were measured as physiological indicators of leaf senescence, while gas chromatography-mass spectrometry was performed to identify metabolites regulated by LpNOL. Knockdown of LpNOL suppressed heat-induced leaf senescence and produced a stay-green phenotype in perennial ryegrass, as manifested by increased Chl content, photochemical efficiency, net photosynthetic rate, and cell membrane stability in Noli-1 and Noli-2. Five metabolites (valine, malic acid, threonic acid, shikimic acid, chlorogenic acid) were uniquely upregulated in LpNOL plants exposed to heat stress, and six metabolites (aspartic acid, glutamic acid, 5-oxoproline, phenylalanine, proline, tartaric acid) exhibited more pronounced increases in their content in LpNOL plants than the WT. LpNOL could regulate heat-induced leaf senescence in perennial ryegrass through metabolic reprogramming in the pathways of respiration, secondary metabolism, antioxidant metabolism, and protein synthesis.

Genomics and lipidomics analysis of the biotechnologically important oleaginous red yeast Rhodotorula glutinis ZHK provides new insights into its lipid and carotenoid metabolism.

BACKGROUND: Rhodotorula glutinis is recognized as a biotechnologically important oleaginous red yeast, which synthesizes numerous meritorious compounds with wide industrial usages. One of the most notable properties of R. glutinis is the formation of intracellular lipid droplets full of carotenoids. However, the basic genomic features that underlie the biosynthesis of these valuable compounds in R. glutinis have not been fully documented. To reveal the biotechnological potential of R. glutinis, the genomics and lipidomics analysis was performed through the Next-Generation Sequencing and HPLC-MS-based metabolomics technologies. RESULTS: Here, we firstly assemble the genome of R. glutinis ZHK into 21.8 Mb, containing 30 scaffolds and 6774 predicted genes with a N50 length of 14, 66,672 bp and GC content of 67.8%. Genome completeness assessment (BUSCO alignment: 95.3%) indicated the genome assembly with a high-quality features. According to the functional annotation of the genome, we predicted several key genes involved in lipids and carotenoids metabolism as well as certain industrial enzymes biosynthesis. Comparative genomics results suggested that most of orthologous genes have underwent the strong purifying selection within the five Rhodotorula species, especially genes responsible for carotenoids biosynthesis. Furthermore, a total of 982 lipids were identified using the lipidomics approaches, mainly including triacylglycerols, diacylglyceryltrimethylhomo-ser and phosphatidylethanolamine. CONCLUSION: Using whole genome shotgun sequencing, we comprehensively analyzed the genome of R. glutinis and predicted several key genes involved in lipids and carotenoids metabolism. By performing comparative genomic analysis, we show that most of the ortholog genes have undergone strong purifying selection within the five Rhodotorula species. Furthermore, we identified 982 lipid species using lipidomic approaches. These results provided valuable resources to further advance biotechnological applications of R .glutinis.

Knockdown of STAYGREEN in Perennial Ryegrass (Lolium perenne L.) Leads to Transcriptomic Alterations Related to Suppressed Leaf Senescence and Improved Forage Quality.

Chl breakdown is a hallmark of leaf senescence. Protein degradation is tightly associated with accelerated Chl catabolism during leaf senescence. Therefore, blocking or reducing Chl breakdown and thereby improving Chl and leaf protein contents is desirable for agronomic improvement in perennial forage grasses. Perennial ryegrass (Lolium perenne L.) is one principle cool-season forage grass in temperate areas throughout the world. In this study, the perennial ryegrass STAY-GREEN gene (LpSGR) was cloned and characterized. LpSGR was highly expressed in developmentally or dark-induced senescent leaves. LpSGR was subcellularly localized in chloroplast and interacted with the other Chl catabolic enzymes. RNA interference (RNAi) of LpSGR in perennial ryegrass blocked the degradation of Chl, resulting in increased Chl content and photochemical efficiency in senescent leaves. The RNAi transgenic plants had significantly improved forage quality, with up to 46.1% increased protein content in the harvested biomass. Transcriptome comparison revealed that suppression of LpSGR led to multiple alterations in metabolic pathways in locations inside the chloroplast. Most transcription factors of senescence-associated hormonal signaling pathways (e.g. ABA, ethylene and jasmonic acid) had decreased expression levels in the RNAi plants. These results provided a foundation for the further study on the regulatory mechanism of LpSGR in perennial ryegrass for the purpose of forage improvement with delayed leaf senescence and higher forage quality.

A wearable pressure sensor based on ultra-violet/ozone microstructured carbon nanotube/polydimethylsiloxane arrays for electronic skins.

Pressure sensors with high performance (e.g., a broad pressure sensing range, high sensitivities, rapid response/relaxation speeds, temperature-stable sensing), as well as a cost-effective and highly efficient fabrication method are highly desired for electronic skins. In this research, a high-performance pressure sensor based on microstructured carbon nanotube/polydimethylsiloxane arrays was fabricated using an ultra-violet/ozone (UV/O3) microengineering technique. The UV/O3 microengineering technique is controllable, cost-effective, and highly efficient since it is conducted at room temperature in an ambient environment. The pressure sensor offers a broad pressure sensing range (7 Pa-50 kPa), a sensitivity of âˆ¼ -0.101 ± 0.005 kPa-1 (<1 kPa), a fast response/relaxation speed of ∼10 ms, a small dependence on temperature variation, and a good cycling stability (>5000 cycles), which is attributed to the UV/O3 engineered microstructures that amplify and transfer external applied forces and rapidly store/release the energy during the PDMS deformation. The sensors developed show the capability to detect external forces and monitor human health conditions, promising for the potential applications in electronic skin.