Development of a Novel CD8+ T Cell-Associated Signature for Prognostic Assessment in Hepatocellular Carcinoma.

OBJECTIVE: The aim of this study was to analyze the clinical significance and prognostic value of CD8+ T cell-related regulatory genes in hepatocellular carcinoma (HCC). METHODS: This was a retrospective study. We combined TCGA-LIHC and single-cell RNA sequencing data for Lasso-Cox regression analysis to screen for CD8+ T cell-associated genes to construct a novel signature. The expression of the signature genes was detected at cellular and tissue levels using qRT-PCR, immunohistochemistry, and tissue microarrays. The CIBERSORT algorithm was then used to assess the immune microenvironmental differences between the different risk groups and a drug sensitivity analysis was performed to screen for potential HCC therapeutic agents. RESULTS: An 8-gene CD8 + T cell-associated signature (FABP5, GZMH, ANXA2, KLRB1, CD7, IL7R, BATF, and RGS2) was constructed. Survival analysis showed that high-risk patients had a poorer prognosis in all cohorts. Tumor immune microenvironment analysis revealed 22 immune cell types that differed significantly between patients in different risk groups, with patients in the low-risk group having an immune system that was more active in terms of immune function. Patients in the high-risk group were more prone to immune escape and had a poorer response to immunotherapy, and AZD7762 was screened as the most sensitive drug in the high-risk group. Finally, preliminary experiments have shown that BATF has a promoting effect on the proliferation, migration and invasion of HuH-7 cells. CONCLUSIONS: The CD8+ T-cell-associated signature is expected to be a tool for optimizing individual patient decision-making and monitoring protocols, and to provide new ideas for treatment and prognostic assessment of HCC.

Orexin B protects dopaminergic neurons from 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity associated with reduced extracellular signal-regulated kinase phosphorylation.

BACKGROUND: The loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) is a major pathological hallmark of Parkinson's disease (PD). Orexin B (OXB) has been reported to promote the growth of DA neurons. However, the roles of OXB in the degeneration of DA neurons still remained not fully clear. METHODS: An in vivo PD model was constructed by administrating 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice. Pole test was performed to investigate the motor function of mice and the number of DA neurons was detected by immunofluorescence (IF). A PD cell model was established by treating SH-SY5Y cells with 1-methyl-4-phenylpyridinium (MPP+). OXB was added to the culture medium 2 h after MPP + treatment. Microscopic analysis was carried out to investigate the function of OXB in the cell model of PD 24 h after MPP + challenge. RNA-Seq analysis of the PD cell model was performed to explore the possible mechanisms. Western blot was used to detect the phosphorylation levels of extracellular signal-regulated kinase (ERK). RESULTS: OXB significantly decreased the DA neurons death caused by MPTP, alleviated MPP+-induced neurotoxicity in SH-SY5Y cells, and robustly enhanced the weight and motor ability of PD mice. Besides, RNA-Seq analysis demonstrated that the mitogen-activated protein kinase (MAPK) pathway was involved in the pathology of PD. Furthermore, MPP + led to increased levels of phosphorylation of ERK (p-ERK), OXB treatment significantly decreased the levels of p-ERK in MPP+-treated SH-SY5Y cells. CONCLUSIONS: This study demonstrated that OXB exerts a neuroprotective role associated with reduced ERK phosphorylation in the PD model. This suggests that OXB may have therapeutic potential for treatment of PD.

Expression patterns and pathogenesis of Semaphorin class 4 subfamily proteins in solid tumors.

Semaphorins are originally described as regulators of nervous system development. Besides, members of the semaphorin family play important roles in the growth, metastasis, and angiogenesis of solid tumors. In contrast to the other semaphorin subclasses, semaphorin class 4 has both membrane-bound and active soluble forms. Soluble class 4 semaphorins in body fluids (blood and saliva) may serve as potential biomarkers for early diagnosis and prognosis prediction of specific cancers. The class 4 semaphorins also transduce signal in cancer cells in a cell membrane-bound form, thereby regulating cancer progression. In solid tumors, class 4 semaphorins can act as ligands in active soluble forms, regulating cancer progression via autocrine and paracrine to activate signal transduction in cancer cells or endothelial cells in the tumor microenvironment. Targeting class 4 semaphorins may be a novel strategy for specific cancer therapy. However, the expression of class 4 semaphorins in solid tumors and the responsive pathogenesis are still controversial. Therefore, this review summarizes the specific expression regulation of class 4 semaphorin members in different types of solid tumors and the mechanisms involved in cancer progression.

Exploring the seasonality and optimal control strategy of HIV/AIDS epidemic in China: The impact of seasonal testing.

In this work, we investigate how the seasonal variation in the number of individuals who are tested for an HIV antibody in outpatient clinics affects the HIV transmission patterns in China, which has not been well studied. Based on the characteristics of outpatient testing data and reported cases, we establish a periodic infectious disease model to study the impact of seasonal testing on HIV transmission. The results indicate that the seasonal testing is a driving factor for the seasonality of new cases. We demonstrate the feasibility of ending the HIV/AIDS epidemic. We find that the diagnostic rates related to testing play a crucial role in controlling the size of the epidemic. Specifically, when considering minimizing both infected individuals and diagnostic rates, the level of attention paid to undiagnosed infected individuals is always positively correlated with the optimal diagnostic rates, while the optimal diagnostic rates are negatively correlated with the size of the epidemic at the terminal time.

Astragaloside IV protects renal tubular epithelial cells against oxidative stress-induced injury by upregulating CPT1A-mediated HSD17B10 lysine succinylation in diabetic kidney disease.

Tubular injury and oxidative stress are involved in the pathogenesis of diabetic kidney disease (DKD). Astragaloside IV (ASIV) is a natural antioxidant. The effects and underlying molecular mechanisms of ASIV on DKD have not been elucidated. The db/db mice and high-glucose-stimulated HK2 cells were used to evaluate the beneficial effects of ASIV in vivo and in vitro. Succinylated proteomics was used to identify novel mechanisms of ASIV against DKD and experimentally further validated. ASIV alleviated renal dysfunction and proteinuria, downregulated fasting blood glucose, and upregulated insulin sensitivity in db/db mice. Meanwhile, ASIV alleviated tubular injury, oxidative stress, and mitochondrial dysfunction in vivo and in vitro. Mechanistically, ASIV reversed downregulated 17beta-hydroxysteroid dehydrogenase type 10 (HSD17B10) lysine succinylation by restoring carnitine palmitoyl-transferase1alpha (Cpt1a or CPT1A) activity in vivo and in vitro. Molecular docking and cell thermal shift assay revealed that ASIV may bind to CPT1A. Molecular dynamics simulations demonstrated K99 succinylation of HSD17B10 maintained mitochondrial RNA ribonuclease P (RNase P) stability. The K99R mutation of HSD17B10 induced oxidative stress and disrupted its binding to CPT1A or mitochondrial ribonuclease P protein 1 (MRPP1). Importantly, ASIV restored the interaction between HSD17B10 and MRPP1 in vivo and in vitro. We also demonstrated that ASIV reversed high-glucose-induced impaired RNase P activity in HK2 cells, which was suppressed upon K99R mutation of HSD17B10. These findings suggest that ASIV ameliorates oxidative stress-associated proximal tubular injury by upregulating CPT1A-mediated K99 succinylation of HSD17B10 to maintain RNase P activity.

Arabidopsis ZINC FINGER PROTEIN1 Acts Downstream of GL2 to Repress Root Hair Initiation and Elongation by Directly Suppressing bHLH Genes.

Cys2His2-like fold group (C2H2)-type zinc finger proteins promote root hair growth and development by regulating their target genes. However, little is known about their potential negative roles in root hair initiation and elongation. Here, we show that the C2H2-type zinc finger protein named ZINC FINGER PROTEIN1 (AtZP1), which contains an ERF-associated amphiphilic repression (EAR) motif, negatively regulates Arabidopsis (Arabidopsis thaliana) root hair initiation and elongation. Our results demonstrate that AtZP1 is highly expressed in root hairs and that AtZP1 inhibits transcriptional activity during root hair development. Plants overexpressing AtZP1 lacked root hairs, while loss-of-function mutants had longer and more numerous root hairs than the wild type. Transcriptome analysis indicated that AtZP1 downregulates genes encoding basic helix-loop-helix (bHLH) transcription factors associated with root hair cell differentiation and elongation. Mutation or deletion of the EAR motif substantially reduced the inhibitory activity of AtZP1. Chromatin immunoprecipitation assays, AtZP1:glucocorticoid receptor (GR) induction experiments, electrophoretic mobility shift assays, and yeast one-hybrid assays showed that AtZP1 directly targets the promoters of bHLH transcription factor genes, including the key root hair initiation gene ROOT HAIR DEFECTIVE6 (RHD6) and root hair elongation genes ROOT HAIR DEFECTIVE 6-LIKE 2 (RSL2) and RSL4, and suppresses root hair development. Our findings suggest that AtZP1 functions downstream of GL2 and negatively regulates root hair initiation and elongation, by suppressing RHD6, RSL4, and RSL2 transcription via the GL2/ZP1/RSL pathway.

Transmission risk assessment of HIV/AIDS epidemic resulting from sexual transmission in China, 2013-2017.

To estimate the risk of human immunodeficiency virus (HIV) infection through sexual transmission in China from 2013 to 2017 accurately, we divide the total population into three groups, namely, men who have sex with men (MSM) group; non-marital and commercial sex group: female sex workers (FSW) and their clients (FSWC); non-marital and non-commercial sex group: general women (GW) and general men (GM). First, the risks of HIV infection among men who have contacts with infected men or infected women decrease annually. Second, the number of contacts between susceptible FSWC and infected FSW per unit time is greater than that between susceptible MSM and infected MSM, and also greater than that between susceptible FSW and infected FSWC, which suggests that the intervention for commercial sex of heterosexual men should be strengthened. Third, the effective reproduction numbers of the MSM group and non-commercial sex group decrease annually, while the effective reproduction number of the commercial sex group decreases first, then increases, because the risk of women being infected by men decreases first, then increases. Additionally, the effective reproduction number of the commercial sex group exceeds that of the MSM group after 2015, which indicates that commercial sex contributes more and more to the HIV/AIDS epidemic.

Multilayer directionally arranged silver nanowire networks for flexible transparent conductive films.

Silver nanowire (AgNW) networks have excellent optoelectronic properties and have important applications in various optoelectronic devices. However, the random distribution of AgNWs coated on the substrate will cause problems such as uneven resistance and high surface roughness, which will affect the properties of the film. In order to solve these problems, this paper adopts the method of directional arrangement of AgNWs to prepare conductive films, by mixing AgNW aqueous solution with hydroxypropyl methyl cellulose (HPMC) to prepare conductive ink, and then the AgNWs are oriented on the flexible substrate by using the shear force generated during the Mayer rod coating process. The multilayer crossed three-dimensional (3D) AgNW conductive network is prepared, achieving a sheet resistance of 12.9 Ω sq-1 and a transmittance of 92.2% (λ = 550 nm). In addition, the roughness RMS value of the layered and ordered AgNW/HPMC composite film is only 6.96 nm, which is much lower than that of the randomly arranged AgNW film (RMS = 19.8 nm), and the composite film also has excellent bending resistance and environmental stability. This adjustable coating method is simple to prepare and can realize the large-scale manufacturing of conductive films, which is important for the future development of flexible transparent conductive films.

Modeling Syphilis and HIV Coinfection: A Case Study in the USA.

Syphilis and HIV infections form a dangerous combination. In this paper, we propose an epidemic model of HIV-syphilis coinfection. The model always has a unique disease-free equilibrium, which is stable when both reproduction numbers of syphilis and HIV are less than 1. If the reproduction number of syphilis (HIV) is greater than 1, there exists a unique boundary equilibrium of syphilis (HIV), which is locally stable if the invasion number of HIV (syphilis) is less than 1. Coexistence equilibrium exists and is stable when all reproduction numbers and invasion numbers are greater than 1. Using data of syphilis cases and HIV cases from the US, we estimated that both reproduction numbers for syphilis and HIV are slightly greater than 1, and the boundary equilibrium of syphilis is stable. In addition, we observed competition between the two diseases. Treatment for primary syphilis is more important in mitigating the transmission of syphilis. However, it might lead to increase of HIV cases. The results derived here could be adapted to other multi-disease scenarios in other regions.

Production and Characterization of Cellulose Nanocrystals from Eucalyptus Dissolving Pulp Using Endoglucanases from Myceliophthora thermophila.

Endoglucanase (EG) is a key enzyme during enzymatic preparation of cellulose nanocrystals (CNCs). Myceliophthora thermophila is a thermophilic fungus that has thermal properties and a high secretion of endoglucanases (EGs), and could serve as potential sources of EGs for the preparation of CNCs. In this work, four different GH families (GH5, GH7, GH12, and GH45) of EGs from M. thermophila were expressed and purified, and their enzymatic characteristics and feasibility of application in CNC preparation were investigated. It was shown that the MtEG5A from M. thermophila has good potential in the enzymatic preparation of CNCs using eucalyptus dissolving pulp as feedstock. It was also observed that there was a synergistic effect between the MtEG5A and other MtEGs in the preparation of CNCs, which improved the yield and properties of CNCs obtained by enzymatic hydrolysis. This study provides a reference for understanding the enzymatic characteristics of different families of EGs from M. thermophile and their potential application in nanocellulose production.

Facile synthesis of a novel BaSnO3/MXene nanocomposite by electrostatic self-assembly for efficient photodegradation of 4-nitrophenol.

Photocatalysis is regarded as one of the most effective strategies for the removal of the toxic organic pollutants from aqueous solutions. However, a lack of the efficient photocatalysts prevents the widespread practical application. Herein, the electrostatic self-assembly method has been designed for facile synthesis of a novel BaSnO3/PDDA/MXene (BSO/P/MX) nanocomposite as high efficient photocatalyst. In this nanocomposite, the BaSnO3 (BSO), poly (dimethyl-diallylammonium chloride) (PDDA) and MXene (Ti3C2Tx) act as the active species, structure stabilizer and efficient electron transfer medium, respectively. Due to the strong synergy of the nanocomposite, the electron-transferring ability as well as the charge separation efficiency is boosted and thus high catalytic activity achieves towards the photodegradation of 4-nitrophenol. The superior degradation rate of 98.8% and a rate constant K of 0.09113 min-1 have been realized within 75 min of ultraviolet (UV) light irradiation over the BSO/P/MX-8% catalyst. This as-prepared nanocomposite with the excellent catalytic activity can be employed as a promising photocatalyst for treating the organic pollutants from aqueous solutions.

Pretreatment Strategies to Enhance Enzymatic Hydrolysis and Cellulosic Ethanol Production for Biorefinery of Corn Stover.

There is a rising interest in bioethanol production from lignocellulose such as corn stover to decrease the need for fossil fuels, but most research mainly focuses on how to improve ethanol yield and pays less attention to the biorefinery of corn stover. To realize the utilization of different components of corn stover in this study, different pretreatment strategies were used to fractionate corn stover while enhancing enzymatic digestibility and cellulosic ethanol production. It was found that the pretreatment process combining dilute acid (DA) and alkaline sodium sulfite (ASS) could effectively fractionate the three main components of corn stover, i.e., cellulose, hemicellulose, and lignin, that xylose recovery reached 93.0%, and that removal rate of lignin was 85.0%. After the joint pretreatment of DA and ASS, the conversion of cellulose at 72 h of enzymatic hydrolysis reached 85.4%, and ethanol concentration reached 48.5 g/L through fed-batch semi-simultaneous saccharification and fermentation (S-SSF) process when the final concentration of substrate was 18% (w/v). Pretreatment with ammonium sulfite resulted in 83.8% of lignin removal, and the conversion of cellulose and ethanol concentration reached 86.6% and 50 g/L after enzymatic hydrolysis of 72 h and fed-batch S-SSF, respectively. The results provided a reference for effectively separating hemicellulose and lignin from corn stover and producing cellulosic ethanol for the biorefinery of corn stover.

Cellulose induced protein 1 (Cip1) from Trichoderma reesei enhances the enzymatic hydrolysis of pretreated lignocellulose.

BACKGROUND: Trichoderma reesei is currently the main strain for the commercial production of cellulase. Cellulose induced protein 1 (Cip1) is one of the most abundant proteins in extracellular proteins of T. reesei. Reported literatures about Cip1 mainly focused on the regulation of Cip1 and its possible enzyme activities, but the effect of Cip1 on the enzymatic hydrolysis of lignocellulose and possible mechanism have not still been reported. RESULTS: In this study, Cip1 from T. reesei was cloned, expressed and purified, and its effects on enzymatic hydrolysis of several different pretreated lignocellulose were investigated. It was found that Cip1 could promote the enzymatic hydrolysis of pretreated lignocellulose, and the promoting effect was significantly better than that of bovine serum albumin (BSA). And especially for the lignocellulosic substrate with high lignin content such as liquid hot water pretreated corn stover and corncob residue, the promoting effect of Cip1 was even better than that of the commercial cellulase when adding equal amount protein. It was also showed that the metal ions Zn2+ and Cu2+ influenced the promoting effect on enzymatic hydrolysis. The Cip1 protein had no lyase activity, but it could destroy the crystal structure of cellulose and reduce the non-productive adsorption of cellulase on lignin, which partly interpreted the promoting effect of Cip1 on enzymatic hydrolysis of lignocellulose. CONCLUSION: The Cip1 from T. reesei could significantly promote the enzymatic hydrolysis of pretreated lignocellulose, and the promotion of Cip1 was even higher than that of commercial cellulase in the enzymatic hydrolysis of the substrates with high lignin content. This study will help us to better optimize cellulase to improve its ability to degrade lignocellulose, thereby reducing the cost of enzymes required for enzymatic hydrolysis.

Modeling and Research on an Immuno-Epidemiological Coupled System with Coinfection.

In this paper, a two-strain model with coinfection that links immunological and epidemiological dynamics across scales is formulated. On the with-in host scale, the two strains eliminate each other with the strain having the larger immunological reproduction number persisting. However, on the population scale coinfection is a common occurrence. Individuals infected with strain one can become coinfected with strain two and similarly for individuals originally infected with strain two. The immunological reproduction numbers [Formula: see text], the epidemiological reproduction numbers [Formula: see text] and invasion reproduction numbers [Formula: see text] are computed. Besides the disease-free equilibrium, there are strain one and strain two dominance equilibria. The disease-free equilibrium is locally asymptotically stable when the epidemiological reproduction numbers [Formula: see text] are smaller than one. In addition, each strain dominance equilibrium is locally asymptotically stable if the corresponding epidemiological reproduction number is larger than one and the invasion reproduction number of the other strain is smaller than one. The coexistence equilibrium exists when all the reproduction numbers are greater than one. Simulations suggest that when both invasion reproduction numbers are smaller than one, bistability occurs with one of the strains persisting or the other, depending on initial conditions.

Gαs protein binds ubiquitin to regulate epidermal growth factor receptor endosomal sorting.

The Gαs subunit is classically involved in the signal transduction of G protein-coupled receptors (GPCRs) at the plasma membrane. Recent evidence has revealed noncanonical roles for Gαs in endosomal sorting of receptors to lysosomes. However, the mechanism of action of Gαs in this sorting step is still poorly characterized. Here, we report that Gαs interacts with ubiquitin to regulate the endosomal sorting of receptors for lysosomal degradation. We reveal that the N-terminal extremity of Gαs contains a ubiquitin-interacting motif (UIM), a sorting element usually found in the endosomal sorting complex required for transport (ESCRT) machinery responsible for sorting ubiquitinated receptors into intraluminal vesicles (ILVs) of multivesicular bodies (MVBs). Mutation of the UIM in Gαs confirmed the importance of ubiquitin interaction for the sorting of epidermal growth factor receptor (EGFR) into ILVs for lysosomal degradation. These findings demonstrate a role for Gαs as an integral component of the ubiquitin-dependent endosomal sorting machinery and highlight the dual role of Gαs in receptor trafficking and signaling for the fine-tuning of the cellular response.

Visible-light-induced deboronative alkylarylation of acrylamides with organoboronic acids.

A visible-light-induced deboronative alkylarylation of acrylamides with organoboronic acids was developed. In this transformation, boronic acids could be activated by the organic photocatalyst of eosin Y, generating alky free radicals in high efficiency. A broad range of substrate scope was examined and a number of 3,3-disubstituted oxindoles were synthesized in high yields.

Rapid determination of nosiheptide in feed based on dispersive SPE coupled with HPLC.

A novel, simple, and reliable method based on high-performance liquid chromatography coupled with fluorescence detection has been developed for the determination of nosiheptide in feed. The feed samples were extracted with acetonitrile 0.1% formic acid aqueous solution and then purified via a dispersive solid-phase extraction procedure using silica gel powder as the sorbent. Using a mixture of acetonitrile and 5 mM ammonium acetate solution (containing 0.1% formic acid) as the mobile phase, good separation and peak shape were obtained for nosiheptide on a Poroshell C8 column (250 × 4.6 mm id, 4 µm) via the isocratic elution program. The resulting calibration curve shows high levels of linearity (r2  > 0.999) for nosiheptide concentrations of 50-1000 µg/L. At three spiked levels, i.e., 0.500, 2.50 and 5.00 mg/kg, the intra- and interday recoveries of nosiheptide in five types of feed ranged from 78.5-96.8 and 84.9-94.2%, respectively. The intra- and interday relative standard deviations were less than 10.8%. The limits of quantification for nosiheptide in complete feed and premixes were measured as 50 and 100 µg/kg, respectively. Compared with other common adsorbents, silica gel presents stronger recovery and purification results for feed samples during the dispersive solid-phase extraction process.

[Effects of Electroacupuncture and Intracerebral Injection of VEGF on Caspase12, Caspase3, and GRP78 Genes in Rats with Cerebral Ischemia-Reperfusion Injury].

OBJECTIVE: To determine the effects of electroacupuncture (EA) and intracerebral injection of vascular endothelial growth factor (VEGF) on caspase12, caspase3, and glucose regulated protein 78 kD (GRP78) genes of rats with cerebral ischemia reperfusion injury. METHODS: 60 SD rats were randomly divided into sham-operation group, model group, EA group and EA+VEGF group with 15 rats in each group. Middle cerebral artery occlusion (MCAO) method was used to establish the model of cerebral ischemia reperfusion injury. Electro-acupuncture intervention was introduced 1 day after the injury in the EA group and EA+VEGF group: 30 minutes each session and once a day for a total of 14 d [acupoint selection: Baihui (GV 20), Quchi(Li 11), Zusanli (ST36)]. The rats in the EA+VEGF group were also injected with 10 µL of VEGF165 (0.025 µg/µL) into the lateral ventricle after the first session of EA. Five rats in each group were sacrificed after obtaining a neurological function score (mNSS) at day 0 (1 d after modeling, before EA intervention), day 7 and day 14, respectively. Nissl staining was used to observe the histomorphology of cerebral infarction areas. Immunohistochemistry was used to CM(155mm]detect GRP78 activity in the ischemic brain tissues. Real-time fluorescence quantitative PCR (real-time PCR) was used to detect the expressions of caspase12, caspase3 and GRP78 mRNA in the ischemic brain tissues. RESULTS: Compared with the sham-operation group, rats in the model group had higher mNSS scores ( P<0.05), showed signs of cerebral infarction (with reduced numbers of and disordered Nissl bodies and unclear structure), increased GRP78 immunopositive cells, increased expression of GRP78 mRNA ( P<0.05), and increased expressions of caspase12 and caspase3 mRNA ( P<0.05). Compared with the model group, EA and EA+VEGF decreased mNSS scores at day 7 and 14 ( P<0.05), showing alleviated signs of cerebral infarction, increased GRP78 immunopositive cells ( P<0.05), increased GRP78 mRNA expression ( P<0.05), and decreased caspase12 and caspase3 mRNA expressions ( P<0.05). The most obvious changes were found in the EA+VEGF group ( P<0.05). No significant changes were observed in the sham-operation group over time ( P<0.05). In comparison, mNSS scores, the signs of cerebral infarction, and the expressions of caspase12 and caspase3 decreased over time in the other groups ( P<0.05), accompanied with increased GRP78 immunopositive cells and the expression of GRP78 gene ( P<0.05). CONCLUSION: Electroacupuncture and intracerebral injection of VEGF promote tissue repair of rats with cerebral ischemic injury, possibly through down-regulating the expressions of caspase12 and caspase3 genes and up-regulating the expression of GRP78 gene. The effect of electroacupuncture in combination with intracerebral injection of VEGF is superior to that of the single use of electroacupuncture.

The Arabidopsis catalase triple mutant reveals important roles of catalases and peroxisome-derived signaling in plant development.

Hydrogen peroxide (H2 O2 ) is generated in many metabolic processes. As a signaling molecule, H2 O2 plays important roles in plant growth and development, as well as environmental stress response. In Arabidopsis, there are three catalase genes, CAT1, CAT2, and CAT3. The encoded catalases are predominately peroxisomal proteins and are critical for scavenging H2 O2 . Since CAT1 and CAT3 are linked on chromosome 1, it has been almost impossible to generate cat1/3 and cat1/2/3 mutants by traditional genetic tools. In this study, we constructed cat1/3 double mutants and cat1/2/3 triple mutants by CRISPR/Cas9 to investigate the role of catalases. The cat1/2/3 triple mutants displayed severe redox disturbance and growth defects under physiological conditions compared with wild-type and the cat2/3 double mutants. Transcriptome analysis showed a more profound transcriptional response in the cat1/2/3 triple mutants compared to the cat2/3 mutants. These differentially expressed genes are involved in plant growth regulation as well as abiotic and biotic stress responses. In addition, expression of OXI1 (OXIDATIVE SIGNAL INDUCIBLE 1) and several MAPK cascade genes were changed dramatically in the catalase triple mutant, suggesting that H2 O2 produced in peroxisomes could serve as a peroxisomal retrograde signal.

An aldonolactonase AltA from Penicillium oxalicum mitigates the inhibition of ß-glucosidase during lignocellulose biodegradation.

Efficient deconstruction of lignocellulose is achieved by the synergistic action of various hydrolytic and oxidative enzymes. However, the aldonolactones generated by oxidative enzymes have inhibitory effects on some cellulolytic enzymes. In this work, D-glucono-1,5-lactone was shown to have a much stronger inhibitory effect than D-glucose and D-gluconate on ß-glucosidase, a vital enzyme during cellulose degradation. AltA, a secreted enzyme from Penicillium oxalicum, was identified as an aldonolactonase which can catalyze the hydrolysis of D-glucono-1,5-lactone to D-gluconic acid. In the course of lignocellulose saccharification conducted by cellulases from P. oxalicum or Trichoderma reesei, supplementation of AltA was able to relieve the decrease of ß-glucosidase activity obviously with a stimulation of glucose yield. This boosting effect disappeared when sodium azide and ethylenediaminetetraacetic acid (EDTA) were added to the saccharification system to inhibit the activities of oxidative enzymes. In summary, we describe the first heterologous expression of a fungal secreted aldonolactonase and its application as an efficient supplement of cellulolytic enzyme system for lignocellulose biodegradation.