HMGA1 regulates the mitochondrial apoptosis pathway in sepsis-induced cardiomyopathy.

High mobility group protein AT-hook 1 (HMGA1), an architectural transcription factor, has previously been reportedto play an essential role in architectural remodeling processes. However, its effects on cardiovascular diseases, particularly sepsis-induced cardiomyopathy, have remained unclear. The study aimed to investigate the role of HMGA1 in lipopolysaccharide-induced cardiomyopathy. Mice subjected to lipopolysaccharide for 12 h resulted in cardiac dysfunction. We used an adeno-associated virus 9 delivery system to achieve cardiac-specific expression of the HMGA1 gene in the mice. H9c2 cardiomyocytes were infected with Ad-HMGA1 to overexpress HMGA1 or transfected with si-HMGA1 to knock down HMGA1. Echocardiography was applied to measure cardiac function. RT-PCR was used to detect the transcriptional level of inflammatory cytokines. CD45 and CD68 immunohistochemical staining were used to detect inflammatory cell infiltration and TUNEL staining to evaluate the cardiomyocyte apoptosis, MitoSox was used to detect mitochondrial reactive oxygen species, JC-1 was used todetect Mitochondrial membrane potential. Our findings revealed that the overexpression of HMGA1 exacerbated myocardial inflammation and apoptosis in response to lipopolysaccharide treatment. Additionally, we also observed that H9c2 cardiomyocytes with HMGA1 overexpression exhibited enhanced inflammation and apoptosis upon stimulation with lipopolysaccharide for 12 h. Conversely, HMGA1 knockdown in H9c2 cardiomyocytes attenuated lipopolysaccharide-induced cardiomyocyte inflammation and apoptosis. Further investigations into the molecular mechanisms underlying these effects showed that HMGA1 promoted lipopolysaccharide-induced mitochondrial-dependent cardiomyocyte apoptosis. The study reveals that HMGA1 worsens myocardial inflammation and apoptosis in response to lipopolysaccharide treatment. Mechanically, HMGA1 exerts its effects by regulating the mitochondria-dependent apoptotic pathway.

Role of polyphenols in remodeling the host gut microbiota in polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a common reproductive and metabolic condition in women of childbearing age and a major cause of anovulatory infertility. The pathophysiology of PCOS is complex. Recent studies have reported that apart from hyperandrogenism, insulin resistance, systemic chronic inflammation, and ovarian dysfunction, gut microbiota dysbiosis is also involved in PCOS development and may aggravate inflammation and metabolic dysfunction, forming a vicious cycle. As naturally occurring plant secondary metabolites, polyphenols have been demonstrated to have anticancer, antibacterial, vasodilator, and analgesic properties, mechanistically creating putative bioactive, low-molecular-weight metabolites in the human gut. Here, we summarize the role of gut microbiota dysbiosis in the development of PCOS and demonstrate the ability of different polyphenols - including anthocyanin, catechins, and resveratrol - to regulate gut microbes and alleviate chronic inflammation, thus providing new insights that may assist in the development of novel therapeutic strategies to treat women with PCOS.

Oxytetracycline-induced oxidative liver damage by disturbed mitochondrial dynamics and impaired enzyme antioxidants in largemouth bass (Micropterus salmoides).

Oxytetracycline (OTC), a commonly used tetracycline antibiotic in aquaculture, has been found to cause significant damage to the liver of largemouth bass (Micropterus salmoides). This study revealed that OTC can lead to severe histopathological damage, structural changes at the cellular level, and increased levels of reactive oxygen species (ROS) in M. salmoides. Meanwhile, OTC impairs the activities of antioxidant enzyme (such as T-SOD, CAT, GST, GR) by suppressing the activation of MAPK/Nrf2 pathway. OTC disrupts mitochondrial dynamics and mitophagy through via PINK1/Parkin pathway. The accumulation of damaged mitochondria, combined with the inhibition of the antioxidant enzyme system, contributes to elevated ROS levels and oxidative liver damage in M. salmoides. Further investigations demonstrated that an enzyme-treated soy protein (ETSP) dietary supplement can help maintain mitochondrial dynamic balance by inhibiting the PINK1/Parkin pathway and activate the MAPK/Nrf2 pathway to counteract oxidative damage. In summary, these findings highlight that exposure to OTC disrupts mitochondrial dynamics and inhibits the antioxidant enzyme system, ultimately exacerbating oxidative liver damage in M. salmoides. We propose the use of a dietary supplement as a preventive measure against OTC-related side effects, providing valuable insights into the mechanisms of antibiotic toxicity in aquatic environments.

Liver fibrosis in fish research: From an immunological perspective.

Liver fibrosis is a pathological process whereby the liver is subjected to various acute and chronic injuries, resulting in the activation of hepatic stellate cells (HSCs), an imbalance of extracellular matrix generation and degradation, and deposition in the liver. This review article summarizes the current understanding of liver fibrosis in fish research. Liver fibrosis is a common pathological condition that occurs in fish raised in aquaculture. It is often associated with poor water quality, stressful conditions, and the presence of pathogens. The review describes the pathophysiology of liver fibrosis in fish, including the roles of various cells and molecules involved in the development and progression of the disease. The review also covers the various methods used to diagnose and assess the severity of liver fibrosis in fish, including histological analysis, biochemical markers, and imaging techniques. In addition, the article discusses the current treatment options for liver fibrosis in fish, including dietary interventions, pharmaceuticals, and probiotics. This review highlights the need for more in-depth research in this area to better understand the mechanisms by which liver fibrosis in fish occurs and to develop effective prevention and treatment strategies. Finally, improved management practices and the development of new treatments will be critical to the sustainability of aquaculture and the health of farmed fish.

Profiling miRNAs of Teleost Fish in Responses to Environmental Stress: A Review.

miRNAs are a class of endogenous and evolutionarily conserved noncoding short RNA molecules that post-transcriptionally regulate gene expression through sequence-specific interactions with mRNAs and are capable of controlling gene expression by binding to miRNA targets and interfering with the final protein output. The miRNAs of teleost were firstly reported in zebrafish development, but there are recent studies on the characteristics and functions of miRNAs in fish, especially when compared with mammals. Environmental factors including salinity, oxygen concentration, temperature, feed, pH, environmental chemicals and seawater metal elements may affect the transcriptional and posttranscriptional regulators of miRNAs, contributing to nearly all biological processes. The survival of aquatic fish is constantly challenged by the changes in these environmental factors. Environmental factors can influence miRNA expression, the functions of miRNAs and their target mRNAs. Progress of available information is reported on the environmental effects of the identified miRNAs, miRNA targets and the use of miRNAs in fish.

Circ_0115118 regulates endometrial functions through the miR-138-1-3p/WDFY2 axis in patients with PCOS†.

To investigate the expression profiles of circular RNAs (circRNAs) in the endometria of women with polycystic ovary syndrome (PCOS) and to explore the role of aberrant circ_0115118 expression in endometrial dysfunction in patients with PCOS. CircRNA microarray hybridization and bioinformatic analyses were performed to determine the expression patterns of circRNAs in the endometria of patients with or without PCOS, the expression of target circRNA was evaluated by real-time polymerase chain reaction (PCR). Cell counting kit-8 and Transwell assays were used to detect cellular proliferative, invasive, and migratory capacities. The influence of the circRNA on decidualization was explored by real-time PCR. Animal models were established to investigate the regulatory effect of the circRNA on embryo implantation. Downstream microRNAs and genes were predicted using bioinformatic websites and verified by dual-luciferase reporter assays, real-time PCR, and western blotting. In the endometria of patients with PCOS, there were 113 differentially expressed circRNAs in the secretory phase and 1119 differentially expressed circRNAs in the proliferative phase. The expression of circ_0115118 was significantly higher in endometrial stromal cells during the proliferative phase in patients with PCOS, leading to inhibition of cellular mobilization and embryo implantation. In addition, circ_0115118 exerted effects by sponging miR-138-1-3p, subsequently increasing the expression of WD repeat and FYVE domain-containing protein 2 (WDFY2). Circ_0115118 expression is dysregulated in the endometria of patients with PCOS and adversely affects endometrial function. Our findings reveal that circ_0115118 may be a potential therapeutic target to improve pregnancy outcomes in women with PCOS.

Hypermethylation of Smad7 in CD4+ T cells is associated with the disease activity of rheumatoid arthritis.

Background: Smad7 is protective in a mouse model of rheumatoid arthritis. Here we investigated whether Smad7-expressing CD4+ T cells and the methylation of Smad7 gene in CD4+ T cells contribute to the disease activity of RA in patients. Methods: Peripheral CD4+ T cells were collected from 35 healthy controls and 57 RA patients. Smad7 expression by CD4+ T cells were determined and correlated with the clinical parameters of RA including RA score and serum levels of IL-6, CRP, ESR, DAS28-CRP, DAS28-ESR, Swollen joints and Tender joints. Bisulfite sequencing (BSP-seq) was used to determine the DNA methylation in Smad7 promoter (-1000 to +2000) region in CD4+ T cells. In addition, a DNA methylation inhibitor, 5-Azacytidine (5-AzaC), was added to CD4+ T cells to examine the possible role of Smad7 methylation in CD4+ T cell differentiation and functional activity. Results: Compared to the heath controls, Smad7 expression was significantly decreased in CD4+ T cells from RA patients and inversely correlated with the RA activity score and serum levels of IL-6 and CRP. Importantly, loss of Smad7 in CD4+ T cell was associated with the alteration of Th17/Treg balance by increasing Th17 over the Treg population. BSP-seq detected that DNA hypermethylation occurred in the Smad7 promoter region of CD4+ T cells obtained from RA patients. Mechanistically, we found that the DNA hypermethylation in the Smad7 promoter of CD4+ T cells was associated with decreased Smad7 expression in RA patients. This was associated with overreactive DNA methyltransferase (DMNT1) and downregulation of the methyl-CpG binding domain proteins (MBD4). Inhibition of DNA methylation by treating CD4+ T cells from RA patients with 5-AzaC significantly increased Smad7 mRNA expression along with the increased MBD4 but reduced DNMT1 expression, which was associated with the rebalance in the Th17/Treg response. Conclusion: DNA hypermethylation at the Smad7 promoter regions may cause a loss of Smad7 in CD4+ T cells of RA patients, which may contribute to the RA activity by disrupting the Th17/Treg balance.

SUMOylation-modified Pelota-Hbs1 RNA surveillance complex restricts the infection of potyvirids in plants.

RNA quality control nonsense-mediated decay is involved in viral restriction in both plants and animals. However, it is not known whether two other RNA quality control pathways, nonstop decay and no-go decay, are capable of restricting viruses in plants. Here, we show that the evolutionarily conserved Pelota-Hbs1 complex negatively regulates infection of plant viruses in the family Potyviridae (termed potyvirids), the largest group of plant RNA viruses that accounts for more than half of the viral crop damage worldwide. Pelota enables the recognition of the functional G1-2A6-7 motif in the P3 cistron, which is conserved in almost all potyvirids. This allows Pelota to target the virus and act as a viral restriction factor. Furthermore, Pelota interacts with the SUMO E2-conjugating enzyme SCE1 and is SUMOylated in planta. Blocking Pelota SUMOylation disrupts the ability to recruit Hbs1 and inhibits viral RNA degradation. These findings reveal the functional importance of Pelota SUMOylation during the infection of potyvirids in plants.

The relationships of CD8+ T cell subsets in RA patients with disease activity and clinical parameters.

BACKGROUND: CD8+ T cells are plentiful in rheumatoid arthritis (RA) and have a important role in it's pathogenesis. Many subsets have been identified in CD8+ T cells, however, the relationship between CD8+ T subpopulations and disease activity of RA is poorly defined. Here we detected different CD8+ T cell subsets in peripheral blood and examined their relationships with clinical features and serological parameters in RA. METHODS: CD8+ T cell phenotypes and percentages in peripheral blood were determined by flow cytometry in 39 patients with RA. The clinical characteristics and serological parameters of RA patients were collected and DAS28-ESR was measured as indicator of disease activity. Linear regression was performed to assess the correlation of CD8+ T cell subsets with RA clinical variables. RESULTS: Naive CD8+ T cells were significantly and negatively correlated with RA disease activity indicator DAS28-ESR(r2 = 0.1027, p = 0.0468), erythrocyte sedimentation rate (ESR)(r2 = 0.1891, p = 0.0057), clinical disease activity index(CDAI)(r2 = 0.1474, p = 0.0158), simplified disease activity index(SDAI)(r2 = 0.1465, p = 0.0255), and duration(r2 = 0.1247, p = 0.0274). And the percent of naive CD8+ T cells were obviously decreased in RA with high disease activity when compared with RA in low disease activity(p < 0.01). In addition, Our results indicated significant positive correlations between CD8+ CD28- T cells and DAS28-ESR(r2 = 0.1881, p = 0.0058), ESR(r2 = 0.2279, p = 0.0021), c reaction protein (CRP)(r2 = 0.2203, p = 0.0051), CDAI (r2 = 0.1778, p = 0.0075), SDAI (r2 = 0.2618, p = 0.0020), rheumatoid factor(RF)(r2 = 0.1823, p = 0.0067), age(r2 = 0.1968, p = 0.0047), as well as similar positive correlations between CD8+ CD27- T cells and DAS28-ESR(r2 = 0.1661, p = 0.01), ESR(r2 = 0.1586, p = 0.012), CRP(r2 = 0.1778, p = 0.013), CDAI (r2 = 0.1622, p = 0.0110), SDAI(r2 = 0.2316, p = 0.0040), RF(r2 = 0.2097, p = 0.0034), age(r2 = 0.1932, p = 0.0051). Furthermore, interesting results showed observable positive correlations between activated CD8+ T cells and total cholesterol(TC)(r2 = 0.2757, p = 0.0007), triglyceride(TG)(r2 = 0.2886, p = 0.0005), low density lipoprotein(LDL-C)(r2 = 0.09643, p = 0.0264) and Krebs yon denlungen-6(KL-6)(r2 = 0.4171, p = 0.0002). And TCRγδ + CD8+ T cells were also found positively related with total cholesterol(TC)(r2 = 0.5015, p < 0.0001), triglyceride(TG)(r2 = 0.2031, p = 0.0045), and KL-6(r2 = 0.2122, p = 0.0136). CONCLUSIONS: Our results suggest that naive CD8+ T cells, CD8+ CD28- T cells, and CD8+ CD27- T cells are obviously correlated with inflammation and disease activity of RA. While activated CD8+ T cells and TCRγδ + CD8+ T cells may involve in lipidmetabolism and lung fibrosis of RA. These CD8+ T cell subsets may be new biomarkers and targets for RA disease evaluation, therapeutic target-selecting, curative effects and prognoses assessment.

Oxidative stress and antioxidant imbalance in ovulation disorder in patients with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disease that is characterized by oligo-ovulation or anovulation, hyperandrogenism, and polycystic ovaries observed using ultrasound with high clinical heterogeneity. At present, the etiology of PCOS is not clear but is thought to be related to genetic, metabolic, endocrine and environmental factors. Hyperandrogenism interacts with insulin resistance and overweight/obesity, forming a vicious cycle of mutual promotion and participating in the occurrence and progression of PCOS. Oxidative stress (OS) refers to the imbalance between the oxidation system and antioxidation system in the human body, which is associated with the occurrence and development of various diseases. Recent studies have shown that OS may be closely related to ovulation disorders in PCOS, and antioxidants can improve the oxidative stress state of PCOS. However, previous studies did not examine the effect of the interaction between OS and hyperandrogenism, insulin resistance or overweight/obesity on ovulation disorders in PCOS. This article reviews the interaction between OS and hyperandrogenism, insulin resistance and overweight/obesity; the effects of OS, hyperandrogenism, insulin resistance and overweight/obesity on ovulation disorders in PCOS; and the application of antioxidants in PCOS.

Abnormal Endometrial Receptivity and Oxidative Stress in Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder in women of childbearing age. Individual heterogeneity is evident, and the prevalence rate ranges between 6 and 15% globally. The prevalence rate of PCOS in Chinese women of childbearing age is 5.6%. The main manifestations are infertility, sparse menstruation, irregular vaginal bleeding, long-term endometrial hyperplasia, and endometrial cancer. PCOS is often associated with hyperandrogenemia, insulin resistance, hyperinsulinemia, obesity, metabolic syndrome, and intestinal flora disorder. Although there have been many studies in the past, the underlying pathophysiological mechanism of the disease is still unclear. Studies have shown that PCOS diseases and related complications are closely related to local oxidative stress imbalance in the endometrium, leading to poor endometrial receptivity and effects on pregnancy. Previous reviews have mainly focused on the abnormal mechanism of ovarian oxidative stress in women with PCOS, while reviews on endometrial receptivity and oxidative stress are relatively insufficient. This study reviews the abnormal cellular and molecular mechanisms of oxidative stress due to comorbidities in women with PCOS, leading to a downregulation of endometrial receptivity.

An Altered Microbiota in the Lower and Upper Female Reproductive Tract of Women with Recurrent Spontaneous Abortion.

Recurrent spontaneous abortion (RSA) is a complex multifactorial disease. Recently, the microbiota of the female reproductive tract, as an emerging factor in RSA, has gradually attracted the attention of many clinical researchers. Here, we reported that the microbiota of the lower and upper female reproductive tracts from patients with RSA showed no significant differences in alpha diversity compared to that of controls. Beta diversity was significantly higher in the RSA group than in the control group in the vaginal microbiota (P = 0.036), cervical microbiota (P = 0.010) and microbiota from uterine lavage fluid (P = 0.001). In addition, dramatic decreases in gamma interferon and interleukin-6 cytokine levels were observed in the RSA group. In conclusion, our data suggested altered microbial biodiversity in the vagina, cervix and uterine lavage fluid in the RSA group. Alterations in the microbiota in the uterine cavity could be associated with altered cytokine levels, which might be a risk factor for RSA pathogenesis. Moreover, the microbiota composition differed markedly from the lower genital tract to the uterine cavity, and the microbiota in the uterine cavity also distinctly varied between endometrial tissue and uterine lavage fluid in the RSA group. Hence, sampling with these two methods simultaneously allowed a more comprehensive perspective of microbial colonization in the uterine cavity. IMPORTANCE As an obstacle to pregnancy, recurrent spontaneous abortion (RSA) can be caused by a variety of factors, and a current understanding of the etiology of RSA is still lacking; half of cases have an unknown cause. A substantial fraction of patients show no improvement after treatment. Since the microbiota of the female reproductive tract has been proposed as an emerging factor in RSA patients, further investigation is needed to provide guidance for clinical therapy. In general, this is the first report describing the distinct alterations of the vaginal, cervical, and uterine microbiota in RSA, not just that in the vagina. Furthermore, another major strength of this study derived from the further in-depth investigation and analysis of the characteristics of the microbiota colonizing the upper female genital tract in RSA, which provided a more comprehensive view for investigating the uterine microbiota.

Abscisic Acid Connects Phytohormone Signaling with RNA Metabolic Pathways and Promotes an Antiviral Response that Is Evaded by a Self-Controlled RNA Virus.

A complex network of cellular receptors, RNA targeting pathways, and small-molecule signaling provides robust plant immunity and tolerance to viruses. To maximize their fitness, viruses must evolve control mechanisms to balance host immune evasion and plant-damaging effects. The genus Potyvirus comprises plant viruses characterized by RNA genomes that encode large polyproteins led by the P1 protease. A P1 autoinhibitory domain controls polyprotein processing, the release of a downstream functional RNA-silencing suppressor, and viral replication. Here, we show that P1Pro, a plum pox virus clone that lacks the P1 autoinhibitory domain, triggers complex reprogramming of the host transcriptome and high levels of abscisic acid (ABA) accumulation. A meta-analysis highlighted ABA connections with host pathways known to control RNA stability, turnover, maturation, and translation. Transcriptomic changes triggered by P1Pro infection or ABA showed similarities in host RNA abundance and diversity. Genetic and hormone treatment assays showed that ABA promotes plant resistance to potyviral infection. Finally, quantitative mathematical modeling of viral replication in the presence of defense pathways supported self-control of polyprotein processing kinetics as a viral mechanism that attenuates the magnitude of the host antiviral response. Overall, our findings indicate that ABA is an active player in plant antiviral immunity, which is nonetheless evaded by a self-controlled RNA virus.

microRNA-520c-3p suppresses NLRP3 inflammasome activation and inflammatory cascade in preeclampsia by downregulating NLRP3.

BACKGROUND: The pathogenesis of preeclampsia (PE) is suggested to be a consequence of inflammation. Previously conducted investigations on nod-like receptor pyrin domain-containing 3 (NLRP3) have shed light to its crucial role in PE. Furthermore, microRNA-520c-3p (miR-520c-3p) is observed to be implicated in inflammation. Therefore, the current study aimed to explore the role of miR-520c-3p in inflammatory cascade of PE by targeting NLRP3. METHODS: Microarray analyses were performed to screen differentially expressed genes associated with PE, and the potential relationship between miR-520c-3p and NLRP3 was analyzed. PE and normal placenta tissues were collected to determine the levels of inflammatory cytokines (IL-18, IL-33, IL-1ß, IL-10, and TNF-α), miR-520c-3p and NLRP3. Hypoxic HTR8/SVneo cells were transfected with oe-NLRP3, si-NLRP3 or miR-520c-3p mimic to elucidate the functional role of NLRP3 or miR-520c-3p in the inflammatory cascade in PE, followed by the evaluation of levels of inflammatory cytokines and NLRP3 inflammasomes (NLRP3, ASC and caspase-1). Additionally, the HTR8/SVneo cell migration and invasion were evaluated. RESULTS: An upregulation of NLRP3, IL-18, IL-1ß and TNF-α, and downregulation of miR-520c-3p, IL-33 and IL-10 were observed in PE placenta tissues. NLRP3 was found to be a target gene of miR-520c-3p. HTR8/SVneo cells after hypoxia transfected with si-NLRP3 or miR-520c-3p mimic exhibited decreased levels of inflammatory cytokines and NLRP3 inflammasomes, in addition to increased IL-10 and IL-33 levels. Moreover, enhanced migration and invasion abilities were observed in cells transfected with si-NLRP3. CONCLUSION: Collectively, miR-520c-3p could potentially inhibit NLRP3 inflammasome activation and inflammatory cascade in PE by downregulating NLRP3, highlighting the potential of miR-520c-3p as a therapeutic target for PE treatment.

An autoimmune disease variant of IgG1 modulates B cell activation and differentiation.

The maintenance of autoreactive B cells in a quiescent state is crucial for preventing autoimmunity. Here we identify a variant of human immunoglobulin G1 (IgG1) with a Gly396→Arg substitution (hIgG1-G396R), which positively correlates with systemic lupus erythematosus. In induced lupus models, murine homolog Gly390→Arg (G390R) knockin mice generate excessive numbers of plasma cells, leading to a burst of broad-spectrum autoantibodies. This enhanced production of antibodies is also observed in hapten-immunized G390R mice, as well as in influenza-vaccinated human G396R homozygous carriers. This variant potentiates the phosphorylation of the IgG1 immunoglobulin tail tyrosine (ITT) motif. This, in turn, alters the availability of phospho-ITT to trigger longer adaptor protein Grb2 dwell times in immunological synapses, leading to hyper-Grb2-Bruton's tyrosine kinase (Btk) signaling upon antigen binding. Thus, the hIgG1-G396R variant is important for both lupus pathogenesis and antibody responses after vaccination.

Plant Viral Proteases: Beyond the Role of Peptide Cutters.

Almost half of known plant viral species rely on proteolytic cleavages as key co- and post-translational modifications throughout their infection cycle. Most of these viruses encode their own endopeptidases, proteases with high substrate specificity that internally cleave large polyprotein precursors for the release of functional sub-units. Processing of the polyprotein, however, is not an all-or-nothing process in which endopeptidases act as simple peptide cutters. On the contrary, spatial-temporal modulation of these polyprotein cleavage events is crucial for a successful viral infection. In this way, the processing of the polyprotein coordinates viral replication, assembly and movement, and has significant impact on pathogen fitness and virulence. In this mini-review, we give an overview of plant viral proteases emphasizing their importance during viral infections and the varied functionalities that result from their proteolytic activities.

Truncation of a P1 leader proteinase facilitates potyvirus replication in a non-permissive host.

The Potyviridae family is a major group of plant viruses that includes c. 200 species, most of which have narrow host ranges. The potyvirid P1 leader proteinase self-cleaves from the remainder of the viral polyprotein and shows large sequence variability linked to host adaptation. P1 proteins can be classified as Type A or Type B on the basis, amongst other things, of their dependence or not on a host factor to develop their protease activity. In this work, we studied Type A proteases from the Potyviridae family, characterizing their host factor requirements. Our in vitro cleavage analyses of potyvirid P1 proteases showed that the N-terminal domain is relevant for host factor interaction and suggested that the C-terminal domain is also involved. In the absence of plant factors, the N-terminal end of Plum pox virus P1 antagonizes protease self-processing. We performed extended deletion mutagenesis analysis to define the N-terminal antagonistic domain of P1. In viral infections, removal of the P1 protease antagonistic domain led to a gain-of-function phenotype, strongly increasing local infection in a non-permissive host. Altogether, our results shed new insights into the adaptation and evolution of potyvirids.

The Potyviridae P1a leader protease contributes to host range specificity.

The P1a protein of the ipomovirus Cucumber vein yellowing virus is one of the self-cleavage serine proteases present in Potyviridae family members. P1a is located at the N-terminal end of the viral polyprotein, and is closely related to potyviral P1 protease. For its proteolytic activity, P1a requires a still unknown host factor; this might be linked to involvement in host specificity. Here we built a series of constructs and chimeric viruses to help elucidate the role of P1a cleavage in host range definition. We demonstrate that host-dependent separation of P1a from the remainder of the polyprotein is essential for suppressing RNA silencing defenses and for efficient viral infection. These findings support the role of viral proteases as important determinants in host adaptation.

[Identification and primary application of TSNA degrading bacterial strain AS97 isolated from aging tobacco leaves].

OBJECTIVE: The purpose of this work was to screen strains having tobacco-specific nitrosamines (TSNA) deteriorating activity, isolated from the inner and superficial of tobacco plants. Then strain AS97 was isolated and identified for further application. METHODS: Strain AS97, with the highest conversion ability against both nitrate and nitrite, was screened by enrichment and selective medium. The strain was identified by morphological, physio-biochemical characteristics and 16S rRNA gene sequence analysis. The concentration of 4-(methylnitrosamino)-1-(3-pyridy)-1-butanone (NNK), N-nitrosonicotine (NNN), N-nitrosoanatabine (NAT) and N-nitrosoanabasine (NAB) were determined by LC-MS/MS. The fermentation broth of strain AS97 was spraied on the leaves of tobacco to define inoculum concentration and fermentation condition. RESULTS: AS97 was identified as Pseudomonas fluorescens (Genbank accession number: JF 449445). Under the optimal growth conditions with inoculum concentration of 5%, at 30 degrees C for 10 d, AS97 had high biological activity against NNK and NNN with a degradation rate of 59.08% and 38.79%, respectively. The correlation analysis displayed a pronounced correlation (p > 0.01) among the concentration of nitrate, nitrite and TSNA. Furthermore, the results also exhibited that nitrate and nitrite were antecedent substance of TSNA. CONCLUSION: These results indicated that Pseudomonas fluorescens AS97 could be a promising microorganism in the practice of non-harmful cigarette production.