The FabA-FabB Pathway Is Not Essential for Unsaturated Fatty Acid Synthesis but Modulates Diffusible Signal Factor Synthesis in Xanthomonas campestris pv. campestris.

Most bacteria use type II fatty acid synthesis (FAS) systems for synthesizing fatty acids, of which the conserved FabA-FabB pathway is considered to be crucial for unsaturated fatty acid (UFA) synthesis in gram-negative bacteria. Xanthomonas campestris pv. campestris, the phytopathogen of black rot disease in crucifers, produces higher quantities of UFAs under low-temperature conditions for increasing membrane fluidity. The fabA and fabB genes were identified in the X. campestris pv. campestris genome by BLAST analysis; however, the growth of the X. campestris pv. campestris fabA and fabB deletion mutants was comparable to that of the wild-type strain in nutrient and minimal media. The X. campestris pv. campestris ΔfabA and ΔfabB strains produced large quantities of UFAs and, altogether, these results indicated that the FabA-FabB pathway is not essential for growth or UFA synthesis in X. campestris pv. campestris. We also observed that the expression of X. campestris pv. campestris fabA and fabB restored the growth of the temperature-sensitive Escherichia coli fabA and fabB mutants CL104 and CY242, respectively, under non-permissive conditions. The in-vitro assays demonstrated that the FabA and FabB proteins of X. campestris pv. campestris catalyzed FAS. Our study also demonstrated that the production of diffusible signal factor family signals that mediate quorum sensing was higher in the X. campestris pv. campestris ΔfabA and ΔfabB strains and greatly reduced in the complementary strains, which exhibited reduced swimming motility and attenuated host-plant pathogenicity. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

HetI-Like Phosphopantetheinyl Transferase Posttranslationally Modifies Acyl Carrier Proteins in Xanthomonas spp.

In Xanthomonas spp., the biosynthesis of the yellow pigment xanthomonadin and fatty acids originates in the type II polyketide synthase (PKS II) and fatty acid synthase (FAS) pathways, respectively. The acyl carrier protein (ACP) is the central component of PKS II and FAS and requires posttranslational phosphopantetheinylation to initiate these pathways. In this study, for the first time, we demonstrate that the posttranslational modification of ACPs in X. campestris pv. campestris is performed by an essential 4'-phosphopantetheinyl transferase (PPTase), XcHetI (encoded by Xc_4132). X. campestris pv. campestris strain XchetI could not be deleted from the X. campestris pv. campestris genome unless another PPTase-encoding gene such as Escherichia coli acpS or Pseudomonas aeruginosa pcpS was present. Compared with wild-type strain X. campestris pv. campestris 8004 and mutant XchetI::PapcpS, strain XchetI::EcacpS failed to generate xanthomonadin pigments and displayed reduced pathogenicity for the host plant, Brassica oleracea. Further experiments showed that the expression of XchetI restored the growth of E. coli acpS mutant HT253 and, when a plasmid bearing XchetI was introduced into P. aeruginosa, pcpS, which encodes the sole PPTase in P. aeruginosa, could be deleted. In in vitro enzymatic assays, XcHetI catalyzed the transformation of 4'-phosphopantetheine from coenzyme A to two X. campestris pv. campestris apo-acyl carrier proteins, XcAcpP and XcAcpC. All of these findings indicate that XcHetI is a surfactin PPTase-like PPTase with a broad substrate preference. Moreover, the HetI-like PPTase is ubiquitously conserved in Xanthomonas spp., making it a potential new drug target for the prevention of plant diseases caused by Xanthomonas.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Liquiritigenin attenuates isoprenaline­induced myocardial fibrosis in mice through the TGF­ß1/Smad2 and AKT/ERK signaling pathways.

Myocardial fibrosis is a pathological process characterized by excessive accumulation of extracellular matrix in myocardial interstitial spaces. Myocardial fibrosis is a fundamental process in ventricular remodeling and a primary contributor to the progression of heart failure. Liquiritigenin (LQ) is a flavanone compound with anti­oxidative, anti­carcinogenic, anti­inflammatory and estrogenic properties. The present study aimed to investigate the regulatory potential of LQ treatment in a mouse model of isoprenaline (ISO)­induced cardiac fibrosis and in cultured H9C2 cardiomyocytes stimulated with angiotensin II (Ang II). The treatment of ISO­induced mice with LQ significantly decreased the levels of cardiac injury­related proteins in the serum and ECM accumulation in mouse heart tissues. LQ treatment also effectively alleviated cardiac dysfunction in ISO­treated mice. Further analyses revealed that LQ inhibited ISO­induced collagen formation and activation of the transforming growth factor­ß1 (TGF­ß1)/Smad2 and protein kinase B (AKT)/extracellular signal­regulated kinase (ERK) signaling pathways. As a major pathological event in myocardial fibrosis, the apoptosis of cardiomyocytes has been considered a key mechanism contributing to impaired left ventricle performance. The pretreatment of rat cardiomyocytes with LQ significantly reduced the apoptosis of H9C2 cells, and inhibited Ang II­induced activation of the TGF­ß1/Smad2 and AKT/ERK pathways. In conclusion, the present study revealed that LQ ameliorated ISO­induced myocardial fibrosis in mice and inhibited the apoptosis of cardiomyocytes in vitro by inhibiting the TGF­ß1/Smad2 and AKT/ERK signaling pathways. These results suggested the anti­fibrotic and cardioprotective potential of LQ in fibrosis, thus supporting the use of LQ for the management of cardiomyocyte injury and myocardial fibrosis in patients with cardiac diseases.

Characterization of 3-Oxacyl-Acyl Carrier Protein Reductase Homolog Genes in Pseudomonas aeruginosa PAO1.

Bacterial 3-oxoacyl-ACP reductase (OAR) catalyzes the 3-oxoacyl-ACP reduction step in the fatty acid synthesis pathway. At least 12 genes in the Pseudomonas aeruginosa genome are annotated as OAR-encoding genes. In this study, we characterized the functions of these genes with biochemical and genetic techniques. With the exception of PA2967, which encodes FabG, an essential protein in fatty acid synthesis, only the PA4389 and PA4786 gene products had OAR activity, and the single deletion of these two genes reduced the ability of P. aeruginosa to produce several specific quorum-sensing (QS) signals. However, PA4389 and PA4786 do not have key roles in fatty acid synthesis. Moreover, although most OAR homologs had no OAR activity, some may function in carbon utilization. The PA3128 product may play a role in the TCA cycle, and PA0182 and PA1470 seem to be required for the utilization of several amino acids. The rest of the OAR homologs have no roles in carbon utilization, but the deletion of one of these genes might affect the production of virulence factors by P. aeruginosa. We conclude that most OAR homolog genes do not encode OAR enzymes, and that these proteins do not function in fatty acid synthesis. IMPORTANCE: We report that although all P. aeruginosa OAR homologs have similar structures and the conserved catalytic triad of the bacterial OAR enzymes, only a few OAR homologs have OAR activity.

miR­15a­3p affects the proliferation, migration and apoptosis of lens epithelial cells.

The present study investigated the effect of microRNA (miR)­15a­3p on the proliferation, migration and apoptosis of lens epithelial cells and its potential mechanism, in order to further elucidate the pathogenesis of age­related cataracts (ARCs). The HLE­B3 human lens epithelial cell line was transfected with miR­15a­3p mimic. Expression of the miR­15a­3p mimic was measured by fluorescence­based reverse transcription­quantitative polymerase chain reaction analysis. Cell proliferation, apoptosis, invasion and migration were investigated using MTT and plate clone formation assays, terminal deoxynucleotidyl transferase dUTP nick end labeling and flow cytometry, and a wound healing assay and Transwell assay, respectively. The protein expression levels of B­cell lymphoma 2 (BCL2) and myeloid cell leukemia sequence 1 (MCL1) were also compared between transfected and wild­type HLE­B3 cells by western blot analysis. The results showed that transfection with the miR­15a­3p mimic significantly suppressed the proliferation of HLE­B3 cells, induced cell apoptosis and increased the proportion of early apoptotic cells. The migration of HLE­B3 cells was significantly inhibited following transfection with miR­15a­3p mimic (P<0.01), whereas cell invasion was unaffected (P>0.05). In addition, reduced protein levels of BCL2 and MCL1 were observed in the miR­15a­3p mimic­transfected HLE­B3 cells (P<0.01). In conclusion, miR­15a­3p may suppress cell proliferation and migration, and induce cell apoptosis in lens epithelial cells through inhibiting the expression of BCL2 and MCL1, which contributes to the onset of ARCs.

Biological Functions of ilvC in Branched-Chain Fatty Acid Synthesis and Diffusible Signal Factor Family Production in Xanthomonas campestris.

In bacteria, the metabolism of branched-chain amino acids (BCAAs) is tightly associated with branched-chain fatty acids (BCFAs) synthetic pathways. Although previous studies have reported on BCFAs biosynthesis, more detailed associations between BCAAs metabolism and BCFAs biosynthesis remain to be addressed. In this study, we deleted the ilvC gene, which encodes ketol-acid reductoisomerase in the BCAAs synthetic pathway, from the Xanthomonas campestris pv. campestris (Xcc) genome. We characterized gene functions in BCFAs biosynthesis and production of the diffusible signal factor (DSF) family signals. Disruption of ilvC caused Xcc to become auxotrophic for valine and isoleucine, and lose the ability to synthesize BCFAs via carbohydrate metabolism. Furthermore, ilvC mutant reduced the ability to produce DSF-family signals, especially branched-chain DSF-family signals, which might be the main reason for Xcc reduction of pathogenesis toward host plants. In this report, we confirmed that BCFAs do not have major functions in acclimatizing Xcc cells to low temperatures.

Xanthomonas campestris FabH is required for branched-chain fatty acid and DSF-family quorum sensing signal biosynthesis.

Xanthomonas campestris pv. campestris (Xcc), a Gram-negative phytopathogenic bacterium, causes black rot disease of cruciferous vegetables. Although Xcc has a complex fatty acid profile comprised of straight-chain fatty acids and branched-chain fatty acids (BCFAs), and encodes a complete set of genes required for fatty acid synthesis, there is still little known about the mechanism of BCFA synthesis. We reported that expression of Xcc fabH restores the growth of Ralstonia solanacearum fabH mutant, and this allows the R. solanacearum fabH mutant to produce BCFAs. Using in vitro assays, we demonstrated that Xcc FabH is able to condense branched-chain acyl-CoAs with malonyl-ACP to initiate BCFA synthesis. Moreover, although the fabH gene is essential for growth of Xcc, it can be replaced with Escherichia coli fabH, and Xcc mutants failed to produce BCFAs. These results suggest that Xcc does not have an obligatory requirement for BCFAs. Furthermore, Xcc mutants lost the ability to produce cis-11-methyl-2-dodecenoic acid, a diffusible signal factor (DSF) required for quorum sensing of Xcc, which confirms that the fatty acid synthetic pathway supplies the intermediates for DSF signal biosynthesis. Our study also showed that replacing Xcc fabH with E. coli fabH affected Xcc pathogenesis in host plants.

Mapping of Quantitative Trait Loci for Contents of Macro- and Microelements in Milled Rice (Oryza sativa L.).

Macro- and microelement contents are important traits for nutritional quality in rice. In this study, quantitative trait loci (QTLs) for the contents of seven mineral elements in milled rice were detected using recombinant inbred lines (RILs) of the indica rice cross Zhenshan 97/Milyang 46, followed by the validation and fine mapping of a QTL region on the short arm of chromosome 6. A total of 20 QTLs distributed on chromosomes 1, 3, 5, 6, 10, and 11 were detected in the RIL population. Co-localizations of QTLs for multiple traits were observed, of which the qP3/qMg3/qZn3 region was shown to have the largest effects for the contents of phosphorus, magnesium, and zinc, and the qK6.1/qCa6/qZn6/qMn6/qCu6 region was found to be responsible for five of the seven traits. Using near isogenic lines having sequential segregating region, the target QTL on chromosome 6 was delimitated to a 29.9 kb region flanked by RM19410 and Si2944. This QTL showed major effects for all seven traits, with the enhancing alleles derived from the male parent Milyang 46.

[The effect of gamma interferon gene transfer on airway inflammation in asthmatic mice].

OBJECTIVE: To study the effect of airway gamma interferon (IFN-gamma) plasmid gene transfer on airway inflammation in asthmatic mice. METHODS: Forty C57BL/6 mice were randomly divided into four groups: a control group (group A), an asthmatic group (group B), a plasmid group (group C) and an IFN-gamma plasmid group (group D), 10 mice in each group. Except group A, other groups were sensitized with 0.1 ml 0.1% ovalbumin (OVA) by a combination of intraperitoneal injection and repeated 50 microl 1% OVA intranasal challenges to establish the mouse asthma model. In group A, normal saline of the equal volume was given instead of 0.1% OVA 0.1 ml and 1% OVA 50 microl. Group C was intranasally administered 50 microl mixture of plasmid pcDNA3.1(-) and Lipofectamine 2000, while 50 microl mixture of IFN-gamma plasmid and Lipofectamine 2000 was administered for the mice of group D. Bronchoalveolar lavage fluid (BALF) cell count and differential were studied. Interleukin-4 (IL-4), interleukin-5 (IL-5) and IFN-gamma in BALF were determined. Pathologic changes in lung tissues were observed. RESULTS: The differences were significant (P < 0.05) when the numbers of inflammation cells, eosinophils, neutrophils and lymphocytes in BALF of group B [(0.102 +/- 0.020) x 10(9)/L, (0.0193 +/- 0.0047) x 10(9)/L, (0.0107 +/- 0.0039) x 10(9)/L, (0.0255 +/- 0.0042) x 10(9)/L, respectively] were compared with those of group A [(0.082 +/- 0.012) x 10(9)/L, (0.0041 +/- 0.0009) x 10(9)/L, (0.0051 +/- 0.0016) x 10(9)/L, (0.0201 +/- 0.0019) x 10(9)/L, respectively]. The numbers of inflammation cells, eosinophils, neutrophils and lymphocytes in BALF of group D [(0.086 +/- 0.016) x 10(9)/L, (0.0116 +/- 0.0031) x 10(9)/L, (0.0062 +/- 0.0018) x 10(9)/L, (0.0182 +/- 0.0041) x 10(9)/L, respectively] were also significantly different (P < 0.05) as compared with those of group B. The IL-4, IL-5 and IFN-gamma levels in BALF of group B [(39.2 +/- 5.1) pg/ml, (83.7 +/- 4.7) pg/ml, (15.7 +/- 2.7) pg/ml, respectively] were significantly different (P < 0.05) as compared with those of group A [(13.3 +/- 1.9) pg/ml, (12.1 +/- 2.3) pg/ml, (31.8 +/- 7.9) pg/ml, respectively]. The IL-4, IL-5 and IFN-gamma levels of group D [(16.4 +/- 3.2) pg/ml, (26.3 +/- 3.4) pg/ml, (65.4 +/- 10.4) pg/ml] were also different (P < 0.05) from those of group B. Lung inflammation was examined in HE stained sections. There was no obvious infiltration of inflammatory cells in the airways of group A. However, there were a great number of inflammatory cells in the interstitial and peribronchovascular regions of group B and group C. Group D exhibited reduced epithelial damage and less infiltration of mononuclear cells and polymorphs in the interstitial and peribronchovascular regions, as compared with group B or group C. CONCLUSIONS: These findings suggest that transtracheal IFN-gamma gene transfer is effective in modulating the imbalance of Th1/Th2 in BALF and inhibiting airway inflammation of asthmatic mice. The result provides experimental data for developing a novel therapeutic approach to asthma.

[Clinical study of surgical treatment of ankylosis of temporomandibular joint].

OBJECTIVE: To analyze the clinical feature of temporomandibular joint (TMJ) ankylosis and to investigate the advantage and disadvantage of all kind of surgery methods of TMJ ankylosis for supplying references to the treatment of TMJ ankylosis. METHODS: Aetiology, sex, age at time of treatment, clinical features, radiographic findings, surgical treatment was reviewed and analyzed. RESULTS: Trauma (66.86%, n = 117) and infection (24.57%, n = 43) were the primary causes of TMJ ankylosis. The 10 approximately 19 years age group (44.57%, n =78) occupied the highest frequency in five age groups, one hundred and fourteen (65.14%, n = 114) of the patients presented with lateral ankylosis. They were carried out different surgery method according to their difference of age, aetiology, and so on. CONCLUSIONS: The person at 10 approximately 19 years old had the more feasibility of TMJ ankylosis than others. Trauma was the commonest cause of ankylosis. Different surgical method should be choose according to the different patient.