Role of the Phenylalanine-Hydroxylating System in Aromatic Substance Degradation and Lipid Metabolism in the Oleaginous Fungus Mortierella alpina

Mortierella alpina is a filamentous fungus commonly found in soil that is able to produce lipids in the form of triacylglycerols that account for up to 50% of its dry weight. Analysis of the M. alpina genome suggests that there is a phenylalanine-hydroxylating system for the catabolism of phenylalanine, which has never been found in fungi before. We characterized the phenylalanine-hydroxylating system in M. alpina to explore its role in phenylalanine metabolism and its relationship to lipid biosynthesis. Significant changes were found in the profile of fatty acids in M. alpina grown on medium containing an inhibitor of the phenylalanine-hydroxylating system compared to M. alpina grown on medium without inhibitor. Genes encoding enzymes involved in the phenylalanine-hydroxylating system (phenylalanine hydroxylase [PAH], pterin-4α-carbinolamine dehydratase, and dihydropteridine reductase) were expressed heterologously in Escherichia coli, and the resulting proteins were purified to homogeneity. Their enzymatic activity was investigated by high-performance liquid chromatography (HPLC) or visible (Vis)-UV spectroscopy. Two functional PAH enzymes were observed, encoded by distinct gene copies. A novel role for tetrahydrobiopterin in fungi as a cofactor for PAH, which is similar to its function in higher life forms, is suggested. This study establishes a novel scheme for the fungal degradation of an aromatic substance (phenylalanine) and suggests that the phenylalanine-hydroxylating system is functionally significant in lipid metabolism.     

Assembly of rhizosphere microbial communities in Artemisia annua: recruitment of plant growth‐promoting microorganisms and inter‐kingdom interactions between bacteria and fungi

Plant and Soil - Plant roots assemble unique microbial communities in rhizosphere, which are critical for plant adapting to natural environment. Given the pivotal importance of plant-microbe...     

Endophytes isolated from Panax notoginseng converted ginsenosides

Endophytes may participate in the conversion of metabolites within medicinal plants, influencing the efficacy of host. However, the distribution of endophytes within medicinal plants P. notoginseng and how it contributes to the conversion of saponins are not well understood. Here, we determined the distribution of saponins and endophytes within P. notoginseng compartments and further confirm the saponin conversion by endophytes. We found metabolites showed compartment specificity within P. notoginseng. Potential saponin biomarkers, such as Rb1, Rg1, Re, Rc and Rd, were obtained. Endophytic diversity, composition and co-occurrence networks also showed compartment specificity, and bacterial alpha diversity values were highest in root compartment, consistently decreased in the stem and leaf compartments, whereas those of fungi showed the opposite trend. Potential bacterial biomarkers, such as Rhizobium, Bacillus, Pseudomonas, Enterobacter, Klebsiella, Pantoea and fungal biomarkers Phoma, Epicoccum, Xylariales, were also obtained. Endophytes related to saponin contents were found by Spearman correlation analysis, and further verification experiments showed that Enterobacter chengduensis could convert ginsenoside Rg1 to F1 at a rate of 13.24%; Trichoderma koningii could convert ginsenoside Rb1 to Rd at a rate of 40.00% and to Rg3 at a rate of 32.31%; Penicillium chermesinum could convert ginsenoside Rb1 to Rd at a rate of 74.24%.     

Cervical Spondylotic Myelopathy Caused by Single-Level Vertebral Spontaneous Fusion

Purpose

To evaluate the clinical features, imaging characteristics, surgical options, and clinical outcomes of patients with Cervical spondylotic myelopathy (CSM) caused by single-level vertebral spontaneous fusion (SLVSF).

Methods

Sixteen consecutive patients with SLVSF who underwent anterior surgery were included in this study and 38 patients with CSM caused by spinal degeneration were enrolled as a control group. Demographic features, clinical presentations, imaging characteristics, surgery strategy, Nurick grade, Japanese Orthopedic Association (JOA) score, neck disability index (NDI), and complications were evaluated.

Results

There were significant differences between the two groups in the mean age and the average duration of neck pain. There was no significant difference between the two groups in length of cervical spine. In the SLVSF group, 13 patients had upper segment translational instability and none had rotational instability. Pre- and postoperative Nurick grades were 2.94±0.77 and 2.19±0.54 in the SLVSF group, and 2.97±0.72 and 2.16±0.64 in the control group. Pre- and postoperative JOA scores were 9.25±2.02 and 11.69±1.62 in the SLVSF group, and 9.87±2.58 and 12.53±2.69 in the control group. Pre- and postoperative NDI values were 28.5±7.75 and 15.56±5.51 in the SLVSF group, and 16±6.13 and 11.29±4.58 in the control group.

Conclusions

Patients with SLVSF have necks of normal lengths, which can be used to distinguish this disorder from Klippel-Feil syndrome. There are three main features of SLVSF: (1) hypoplasia at both of the spontaneously fused vertebral bodies; (2) a major pathological feature of translational instability of the upper vertebra to the fused level; and (3) severe neck pain. Anterior surgery has a good therapeutic effect for patients with cervical SLVSF.     

The mitochondrial membrane protein FgLetm1 regulates mitochondrial integrity,production of endogenous reactive oxygen species and mycotoxin biosynthesis in Fusarium graminearum

Deoxynivalenol (DON) is a mycotoxin produced in cereal crops infected with Fusarium graminearum. DON poses a serious threat to human and animal health, and is a critical virulence factor. Various environmental factors, including reactive oxygen species (ROS), have been shown to interfere with DON biosynthesis in this pathogen. The regulatory mechanisms of how ROS trigger DON production have been investigated extensively in F. graminearum. However, the role of the endogenous ROS‐generating system in DON biosynthesis is largely unknown. In this study, we genetically analysed the function of leucine zipper‐EF‐hand‐containing transmembrane 1 (LETM1) superfamily proteins and evaluated the role of the mitochondrial‐produced ROS in DON biosynthesis. Our results show that there are two Letm1 orthologues, FgLetm1 and FgLetm2, in F. graminearum. FgLetm1 is localized to the mitochondria and is essential for mitochondrial integrity, whereas FgLetm2 plays a minor role in the maintenance of mitochondrial integrity. The ΔFgLetm1 mutant demonstrated a vegetative growth defect, abnormal conidia and increased sensitivity to various stress agents. More importantly, the ΔFgLetm1 mutant showed significantly reduced levels of endogenous ROS, decreased DON biosynthesis and attenuated virulence in planta. To our knowledge, this is the first report showing that mitochondrial integrity and endogenous ROS production by mitochondria are important for DON production and virulence in Fusarium species.     

发菜耐旱相关蛋白NXL-01的基因克隆与表达分析

在发菜耐旱差异蛋白质组学研究中,发现假定蛋白(Hypothetical protein NXL-01)在干旱胁迫条件下表达量逐渐增加。根据已知氨基酸序列设计简并引物克隆NXL-01基因,长度为327bp(GenBank登录号为HM854288)。生物信息学分析表明,该基因具有较高保守性,蛋白质二级结构主要由α螺旋和随机卷曲构成,是亲水性的膜外蛋白,有5个Ser磷酸化位点,1个Thr磷酸化位点。将NXL-01基因在大肠杆菌中表达,获得预期大小的重组蛋白(12.4kD)。RT-PCR分析表明,NXL-01mRNA在干旱胁迫条件下表达量逐渐增加,与NXL-01蛋白的表达趋势一致。     

Development of bioreactor systems with functional bio-carrier modified by disperse turquoise blue S-GL for disperse scarlet S-BWFL decolorization

The effect of redox mediator has been studied in details in the bio-decolorization processes, but there are little literatures about bioreactor systems with functional bio-carrier modified by redox mediator. Two different bioreactor configurations (bioreactor R1 with functional bio-carrier modified by disperse turquoise blue S-GL (as redox mediator) and bioreactor R2 with non-modified bio-carrier) were designed and tested for disperse scarlet S-BWFL decolorization by Halomonas sp. GYW (EF188281) in this study. Influencing factors such as co-substrate, temperature and pH were optimized through batch experiments. Compared to bioreactor R2, bioreactor R1 exhibited good decolorization efficiency and performance ability for the disperse scarlet S-BWFL decolorization, which showed higher decolorization efficiency (over 96% color removal with 0.8 g L(-1) dye concentration) and less hydraulic retention time to attain the same decolorization efficiency. The combinational technology of redox mediator and bio-carrier was a new bio-treatment concept and a great improvement for the application of redox mediator.