Silicon composition and stoichiometric ratios with other nutrients in the lower Minjiang River, Southeast China.

Over the past decades, rivers have delivered imbalanced nutrient loads to coastal marine ecosystems due to human activities, which leads to serious regional or global eutrophication problems. The Minjiang River is heavily influenced by human activities. To understand the changing characteristics of nutrient transport ratios in the Minjiang River waters, we measured the seasonal variations of carbon, nitrogen, phosphorus and silicon nutrients in the lower surface waters of the Minjiang River between July 2019 and July 2020. The results showed that the annual average contents of dissolved silicon (DSi), lithogenic silicon (LSi) and biogenic silicon (BSi) in the surface waters of the lower Minjiang River were 5.30, 4.58 and 2.37 mg·L-1, respectively. There were large seasonal differences among these parameters, with higher content of DSi than LSi and BSi in summer, higher content of DSi than BSi and LSi in autumn and higher content of LSi than DSi and BSi in winter. The proportions of DSi in total silicon tended to decrease gradually from land to sea, while the proportion of BSi was on the contrary. In term of stoichiometric ratios, the Minjiang River mostly presented carbon or phosphorus limitation and was unlimited by silicon or nitrogen. About 1.03×1010 mol DSi and 0.46 ×1010 mol BSi were delivered via the Minjiang River to the ocean yearly, showing a decreasing trend year by year. Based on the data in recent years, the nutrient loads of carbon, nitrogen, and phosphorus transported by Minjiang River showed an increasing trend. The imbalanced nutrient loads may lead to changes in the structure and function of the river, estuary, and offshore ecosystems. The study of nutrient stoichiometric ratios can provide a theoretical basis for solving the problems in structural balance of nutrients and eutrophication in Minjiang River estuary and adjacent marine waters.

First Report of Achromobacter Xylosoxidans Causing Stem Soft Rot on Amorphophallus Konjac in China.

Amorphophallus konjac is one of the important commercial crops cultivated in south China and has long been used as a food source and a traditional medicine, because it is the only species with glucomannan and other trace elements (Ban et al. 2009; Melinda et al. 2010). In June of 2021, an outbreak of stem soft rot disease was observed on A. konjac plants in more than 2,000 square meters of agricultural planting fields in the Fuyuan country (25°34'50″N, 104°04'21″E), Qujing City, Yunnan Province, China. The disease incidence ranged from 30 to 35% in severely infested fields. The diseased plants displayed the first symptoms were damp brown spots. As the brown spots expanded, dark brown water stains appeared at the basal part of the stem and the bulbs were rotting with a foul smell, gradually extending to the underground parts. Progressively, the whole plants wilted and collapsed, and even the plants ultimately died. To identify the pathogen, symptomatic stems were cut into pieces, surface sterilized with 75% (v/v) ethanol, and placed on LB (tryptone/yeast extract/NaCl) medium for 24 to 48 hours at 28 ± 2°C. Six single-colony isolates were obtained from the diseased stems. The colonies on LB present a raised milky white opaque colonies moisture on the surface, round and convex in shape, with neat edges. Scanning electron microscopy showed that the cells were short rods (0.3∼0.5) × (1.9∼2.1)µm in size without any flagellum and were often arranged in pairs or clusters at certain angles. The 16S rDNA sequence of the randomly selected strain MY-G1 with primers 27F/1492R (Ying et al. 2012) and the housekeeping genes nusA, eno, lepA and nuoL (Spilker et al. 2012) were amplified and sequenced. The 16S rDNA sequence of the 1326 bp product was deposited in GenBank (accession no. ON786717) and showed a 99.77% similarity to A. xylosoxidans strain E2 (accession no. MK849863.1). The nusA (OP680477), eno (OP680479), lepA (OP680481) and nuoL (OP680482) sequences showed 94.71%, 97.24%, 94.64% and 95.95% similarity to A. xylosoxidans strain DN002 (accession no. CP045222.1), respectively. The phylogenetic trees built based on 16S rRNA and the nusA-eno-lepA-nuoL multilocus analysis showed the isolate MY-G1 to cluster with A. xylosoxidans. Based on morphological and molecular analysis, the isolated MY-G1 was identified as A. xylosoxidans, which indicates that MY-G1 is a new strain of A. xylosoxidans. Pathogenicity tests were confirmed on the stem and petiole of one-year-old A. konjac. The wounds were made by puncturing with a MY-G1 bacteria suspension containing 108 CFU/ml (15ul/inoculation site). As a negative control, control seedlings were injected with the same amount of sterilized distilled water. Control and inoculated seedlings (each six) were kept in greenhouses and watered as needed in controlled conditions: 28°C, 75% relative humidity. Inoculated seedlings presented similar symptoms of stem soft rot, inner medulla disintegration, and wilt of leaves on developed within 3 to 9 days. The bacterial pathogen was re-isolated from inoculated seedlings and identified by morphological and molecular methods to fulfill Koch's postulates test. According to previous research, A. xylosoxidans can cross-kingdom infect animals and plants (Aisenberg et al.,2004; Ye et al.,2018). To the best of our knowledge, this is the first report of A. xylosoxidans causing stem soft rot of A. konjac in China, expanding the known pathogen for the soft rot of A. konjac, and also the host range of A. xylosoxidans.

Combined metabolomics and proteomics to reveal beneficial mechanisms of Dendrobium fimbriatum against gastric mucosal injury.

As a dietary and medicinal plant, Dendrobium fimbriatum (DF) is widely utilized in China for improving stomach disease for centuries. However, the underlying mechanisms against gastric mucosal injury have not been fully disclosed. Here, metabolomics and proteomics were integrated to clarify the in-depth molecular mechanisms using cyclophosphamide-induced gastric mucosal injury model in mice. As a result, three metabolic pathways, such as creatine metabolism, arginine and proline metabolism, and pyrimidine metabolism were hit contributing to DF protective benefits. Additionally, γ-L-glutamyl-putrescine, cytosine, and thymine might be the eligible biomarkers to reflect gastric mucosal injury tatus, and DF anti-gastric mucosal injury effects were mediated by the so-called target proteins such as Ckm, Arg1, Ctps2, Pycr3, and Cmpk2. This finding provided meaningful information for the molecular mechanisms of DF and also offered a promising strategy to clarify the therapeutic mechanisms of functional foods.

[Research on in vivo metabolites of Longxue Tongluo Capsules by liquid chromatography coupled with hybrid ion trap/time-of-flight mass spectrometry].

Longxue Tongluo Capsules(LTC) has good efficacy against blood stasis syndrome during the recovery period of ischemic stroke. Its main active ingredient is the phenolic extract of Chinese dragon's blood. In our previous study, the primary mass fragmentation pathways of phenolic derivatives from LTC were clarified. Herein, the metabolites in rat plasma were characterized following the oral administration of loureirin A and loureirin C using liquid chromatography coupled with hybrid ion trap/time-of-flight mass spectro-metry(LC-IT-TOF-MS), with 18 and 55 metabolites identified, respectively. On this basis, with the help of the obtained accurate molecular weight, characteristic fragment ions, reference comparison, combined with LTC database and natural products database self-created in our group, 18 prototypes and 106 metabolites were tentatively identified in rat plasma after oral gavage of LTC at a dose of 500 mg·kg~(-1). Glucuronidation, sulfonation, and methylation were major biotransformation pathways of LTC. This study preliminarily clarified the LTC constituents absorbed into blood and laid the foundation for clarifying the effective substances of LTC.

[Identification of active components of Dendrobium inhibit growth of gastric cancer cells based on component-activity relationship].

Three cancer cell lines including gastric cancer SGC-7901, HGC-27, and MGC-803 cells were employed to evaluate the bioactivity of seven Dendrobium species. Simultaneously, these Dendrobium species were assessed with UPLC-Q-TOF-MS, and 504 common peaks were found. Based on the hypothesis that biological effects varied with differences in components, multivariate relevance analysis for chemical component-activity relationship of Dendrobium, including grey relation(GRA) and partial least squares(PLS) analysis were performed to evaluate the contribution of each identified component. The target peaks were identified by standards toge-ther with databases of Dendrobium, Nature Chemistry, MassBank, etc. Finally, four active components, including 3,5,9-trihydroxy-23-methylergosta-7,22-dien-6-one, diacylglycerol(14∶1/22∶6/0∶0), pipercitine, and 22-tricosenoic acid, might have negative effect on the growth of gastric cancer cells.

First Report of Botryosphaeria dothidea Causing Stem Canker and Dieback of Gleditsia sinensis in China.

Gleditsia Sinensis Lam is a kind of legume perennial woody plant, which is a traditional Chinese medicine with high economic and ecological value. Its planting area is about 0.1 million ha. In July 2018, symptoms of stem blight were observed on G. sinensis in An shun (26.072311°N, 106.097433°E), Guizhou province (southwestern China). Symptoms included stem canker and dieback, twig blight and extensive vascular discoloration, with incidence rate of 45 to 70%. Samples from plants with symptoms were washed with running tap water, surface sterilized with 2% sodium hypochlorite and then 75% ethanol, rinsed in sterile distilled water, plated on potato dextrose agar (PDA) and incubated at 28°C. Fungal isolates developed copious white aerial mycelium that became dark grey after four to five days, and formed black pycnidia after 23 days. Single hyphal tip cultures of putative 27 isolates were stored in the culture collection (CMW) of the Urban Modern Agriculture Engineering Research Center at the Kunming University. Conidia forming on pycnidia were one-celled, hyaline, aseptate, and fusiform, with dimensions of 20.3-25.9 µm x 4.2-6.5 µm (average 22.5 x 5.5 µm) (sixty conidia were measured). DNA sequence analysis of the ribosomal internal transcribed spacer regions ITS1-5.8S-ITS4, ß-tubulin, and the translation elongation factor 1-alpha (EF1-α) were performed. BLAST searches at GenBank showed the highest nucleotide sequence identity with Botryosphaeria dothidea reference sequence (ITS: >99.82%, KR708996; EF1-α: 99.62%, KP183214; ß-tubulin: > 99.67%, KU306116). Representative sequences of isolates from these regions were deposited in GenBank (ITS: Accession No. MT449017; EF1-α: Accession No. MT454342; ß-tubulin: Accession No. MT454343). Morphological and molecular results confirmed this species as B. dothidea (Aguirre et al. 2018). Pathogenicity tests were conducted by stem inoculation of two-year-old G. sinensis seedlings. Mycelial plugs (2-3 mm in diameter) from actively growing colonies of B. dothidea (PDA) were applied to same-size bark wounds on the middle point of the stems. Inoculated wounds were wrapped with Parafilm. Control seedlings received sterile PDA plugs. Inoculated and control seedlings (9 each), and kept in the greenhouse (28℃, 80% humidity); After 10 days, all of the inoculated plants showed dark vascular stem tissue, and the controls remained healthy. After 30 days, all of the inoculated but none of the control G. sinensis seedlings showed leaf wilting and tissue discoloration. B. dothidea was re-isolated from symptomatic tissues, thus fulfilling Koch's postulates. No symptoms were visible in the control seedlings, and no B. dothidea was re-isolated from the control seedlings tissues. B. dothidea is a member of Botryosphaeriaceae, commonly associated with cankers and dieback of woody plants. B. dothidea has been reported as a pathogen causing stem dieback and branch canker on Malosma laurina (Aguirre et al. 2018), Helwingia chinensis (Yu et al. 2012), and blueberry (Choi 2011; Yu et al. 2012). To our knowledge, this is the first report of B. dothidea on G. sinensis in China.

Phenolic constituents, pharmacological activities, quality control, and metabolism of Dracaena species: A review.

ETHNOPHARMACOLOGICAL RELEVANCE: Dragon's blood (Chinese name: Xuejie), which comprises red resins obtained from several plants (27 species from 4 families), is drawing worldwide interests in medicinal applications owing to its broad pharmacological spectrum such as promoting blood circulation, regenerating muscle, relieving swelling and pain, maintaining hemostasis, etc. AIM OF THE STUDY: This work aims to evaluate current research progress on phenolic constituents, pharmacological activities, quality control, and metabolism of six Dracaena plants, namely, Dracaena cochinchinensis (Lour.) S.C.Chen, D. cambodiana Pierre ex Gagnep., D. cinnabari Balf. f., D. draco (L.) L., D. loureiroi Gagnep., and D. schizantha Baker, figure out the shortcomings of existing studies, and provide meaningful guidelines for future investigations. METHODS: Extensive database retrieval, such as SciFinder, PubMed, CNKI, ChemSpider, etc., was performed by using the keywords "Dracaena," "dragon's blood," as well as the Latin names of the six Dracaena species. In addition, relevant textbooks, patents, reviews, and documents were also employed to ensure sufficient information is collected. RESULTS: Flavonoids and their oligomers are the primary chemical clusters distributed in Dracaena plants. Pharmacological activities including analgesic, anti-inflammatory, antibacterial, hypolipidemic, hypoglycemic, and cytotoxic effects; bi-directional regulation effects on hemorheology; and cardiovascular and cerebrovascular effects have been disclosed by modern pharmacological evaluations. The chemical and metabolic profiles after oral administration of dragon's blood extract were preliminarily characterized. However, some of the pharmacological investigations reported only elementary methodologies and unreliable findings, and even worse, some important aspects were questionable or missing in these articles. CONCLUSIONS: Dragon's blood is a valuable source of bioactive compounds, mainly flavonoids and their oligomers. Its potential therapeutic effects on different diseases are attractive, such as the notable effect on cardiovascular diseases. In future studies, there is an urgent need to test the effect of this extract on appropriate cell lines and animal models to analyze its ethnopharmacological applications; moreover, "composition-effect correlation" methods and omics technologies are demanded for identifying the effective material basis and therapeutic mechanisms before entering into clinical trials. Moreover, attention should be paid to the chemical profiling and quality evaluation of this precious herbal medicine.

[Identification of active components in Longxue Tongluo Capsules against ischemic brain injury based on component-activity relationship].

Ten fractions(A-J) were prepared by separation of Longxue Tongluo Capsules(LTC) by using silica gel column chromatography and orthogonal experimental design,showing similar chemical profiles with different abundances of peaks.These ten samples were assessed with UHPLC-QE OrbitrapHRMS for 97 common peaks.For the pharmacological activity experiment,three kinds of in vitro cell models including lipopolysaccharide(LPS)-induced BV-2 microglial cells NO release model,oxygen-glucose deprivation/reoxygenation(OGD/R)-treated HUVEC vascular endothelial cells injury model,and OGD/R-treated PC-12 nerve cells injury model were employed to evaluated the bioactivity of each fraction.Based on the contribution of each identified component,grey relation analysis and partial least squares(PLS) analysis were performed to establish component-activity relationship of LTC,identify the potential active components.After that,validation of the potential active components in LTC was carried out by using the same models.The results indicated that 4 phenolic compounds including 7,4'-dihydroxyhomoisoflavanone,loureirin C,4,4'-dihydroxy-2,6-dimethoxydihydrochalcone,and homoisosocotrin-4'-ol,might be the active components for anti-neuroinflammation effect;five phenolic compounds such as 3,5,7,4'-tetrahydroxyhomoisoflavanone,loureirin D,7,4'-dihydroxyhomoisoflavane,and 5,7-dihydroxy-4'-methoxy-8-methyflavane,might have positive effects on the vascular endothelial injury;three phenolic compounds including 5,7,4'-trihydroxyflavanone,7,4'-dihydroxy-5-methoxyhomoisoflavane,and loureirin D,might be the active components in LTC against neuronal injury.