Anatomical, chemical and endophytic fungal diversity of a Qi-Nan clone of Aquilaria sinensis (Lour.) Spreng with different induction times.

Recently, some new Qi-Nan clones of Aquilaria sinensis (Lour.) Spreng which intensively produces high-quality agarwood have been identified and propagated through grafting techniques. Previous studies have primarily focused on ordinary A. sinensis and the differences in composition when compared to Qi-Nan and ordinary A. sinensis. There are few studies on the formation mechanism of Qi-Nan agarwood and the dynamic changes in components and endophytic fungi during the induction process. In this paper, the characteristics, chemical composition, and changes in endophytic fungi of Qi-Nan agarwood induced after 1 year, 2 years, and 3 years were studied, and Qi-Nan white wood was used as the control. The results showed that the yield of Qi-Nan agarwood continued to increase with the induction time over a period of 3 years, while the content of alcohol extract from Qi-Nan agarwood reached its peak at two years. During the formation of agarwood, starch and soluble sugars in xylem rays and interxylary phloem are consumed and reduced. Most of the oily substances in agarwood were filled in xylem ray cells and interxylary phloem, and a small amount was filled in xylem vessels. The main components of Qi-Nan agarwood are also chromones and sesquiterpenes. With an increasing induction time, the content of sesquiterpenes increased, while the content of chromones decreased. The most abundant chromones in Qi-Nan agarwood were 2-(2-Phenethyl) chromone, 2-[2-(3-Methoxy-4-hydroxyphenyl) ethyl] chromone, and2-[2-(4-Methoxyphenyl) ethyl] chromone. Significant differences were observed in the species of the endophytic fungi found in Qi-Nan agarwood at different induction times. A total of 4 phyla, 73 orders, and 448 genera were found in Qi-Nan agarwood dominated by Ascomycota and Basidiomycota. Different induction times had a significant effect on the diversity of the endophytic fungal community in Qi-Nan. After the induction of agarwood formation, the diversity of Qi-Nan endophytic fungi decreased. Correlation analysis showed that there was a significant positive correlation between endophytic fungi and the yield, alcohol extract content, sesquiterpene content, and chromone content of Qi-Nan agarwood, which indicated that endophytic fungi play a role in promoting the formation of Qi-Nan agarwood. Qi-Nan agarwood produced at different induction times exhibited strong antioxidant capacity. DPPH free radical scavenging activity and reactive oxygen species clearance activity were significantly positively correlated with the content of sesquiterpenes and chromones in Qi-Nan agarwood.

Cordythiazole A, the first member of thiazole alkaloids from Chinese cordyceps, with α-glucosidase inhibitory activity.

Chinese cordyceps, also known as Dong-Chong-Xia-Cao, is widely recognized as a famous precious tonic herb, and used as traditional Chinese medicine for centuries. It is mainly used for regulating the immune system and improving functions of the lung and kidney, with anti-tumor, anti-inflammatory, and anti-diabetic activities. Due to its rarity and preciousness, a few chemical components are isolated and identified. Moreover, most of them are common chemical components and widely distributed in other natural resources, such as nucleosides, sterols, fatty acids, sugar alcohols, and peptides. Therefore, a large number of active substances of Chinese cordyceps is still unclear. During our search for chemical constituents of Chinese cordyceps, a new thiazole alkaloid, cordythiazole A (1), was isolated and identified. Its structure was elucidated by comprehensive spectroscopic analysis and single-crystal X-ray diffraction analysis. This is the first report of the presence of thiazole alkaloid in Chinese cordyceps, which adds a new class of metabolite of Chinese cordyceps. Furthermore, a putative biosynthesis pathway of cordythiazole A was proposed based on possible biogenic precursor, genes, and literatures. In addition, it showed α-glucosidase inhibitory activity with potency close to that of acarbose. The discovery of cordythiazole A with α-glucosidase inhibitory activity adds a new class of potential anti-diabetes ingredient in Chinese cordyceps.

Effect and mechanism of BDNF/TrkB signaling on vestibular compensation.

Brain-derived neurotrophic factor (BDNF) regulates neuronal plasticity by targeting the tyrosine kinase B receptor (TrkB) receptor, but limited researches concentrate on the role of BDNF/TrkB signaling in vestibular compensation. In this study, rats with unilateral vestibular dysfunction were established by unilateral labyrinthectomy (UL) and infusion with siBDNF or 7, 8-Dihydroxyflavone (7,8-DHF, a TrkB receptor agonist). The behavioral scores of rats with vestibular deficits were determined and the rotarod test was performed after UL. BDNF and TrkB levels after UL were determined by western blot and quantitative reverse transcription PCR (qRT-PCR). 5-bromo-2'-deoxyuridine (BrdU)-positive cells (newly generated cells) and GAD67-positive cells (GABAergic neurons) were identified by immunohistochemistry. Glial fibrillary acidic protein (GFAP) (astrocyte marker)-positive cells were identified and GABA type A receptor (GABAAR) expression was detected by immunofluorescence. We found that after UL, BDNF and TrkB levels were up-regulated with a maximum value at 4 h, and then progressively down-regulated during 4 h ~ 7 d. Blocking BDNF/TrkB signaling inhibited the recovery from vestibular deficits, decreased the numbers of newly generated cells and astrocytes in medial vestibular nucleus (MVN), inferior vestibular nerve (IVN), superior vestibular nerve (SVN) and lateral vestibular nucleus (LVN), and disrupted the balances of GABAergic neurons and GABAAR expressions in the left (lesioned) side and right (intact) side of MVN, whereas activation of BDNF/TrkB signaling caused opposite results. The current study indicated that BDNF/TrkB signaling avails vestibular compensation, depending on the number of newly generated cells and astrocytes, the rebalance of GABAergic neurons, and GABAAR expression in bilateral MVN.

Evolution of Grain Interfaces in Annealed Duplex Stainless Steel after Parallel Cross Rolling and Direct Rolling.

Changes in various grain interfaces, including the grain boundary and phase boundary, are a strong indication of microstructural changes, particularly ultra-fined grains achieved by large strain deformation and subsequent annealing. After direct rolling and cross rolling with the same strain of ε = 2, the distributions of the interfaces in annealed UNS S32304 duplex stainless steel were investigated using electron backscatter diffraction (EBSD) in this study. The ferrite experienced continued recovery, and a high density of low-angle grain boundaries (LAGBs) was produced. The percentage and number of twin boundaries (TBs) and LAGBs varied within the austenite. TBs were frequently found within austenite, showing a deviation from the Kurdjumov-Sachs (K-S) orientation relationship (OR) with ferrite matrix. However, LAGBs usually occur in austenite, with the K-S OR in the ferrite matrix. LAGBs were prevalent in the precipitated austenite grains, and therefore a strong texture was introduced in the cross-rolled and annealed samples, in which the precipitated austenite readily maintained the K-S OR in the ferrite matrix. By contrast, more TBs and a less robust texture were found in the precipitated austenite in direct-rolled and annealed samples, deviating from the K-S OR.

BCR-mediated apoptosis associated with negative selection of immature B cells is selectively dependent on Pten.

The molecular basis of B cell receptor (BCR)-induced apoptosis during the negative selection of immature B cells is largely unknown. We use transitional immature B cells that are highly susceptible to BCR-induced apoptosis to show that Pten is selectively required for BCR-mediated initiation of the mitochondrial death pathway. Specifically, deleting Pten, but not other pro-apoptotic molecules, abrogates BCR-elicited apoptosis and improves viability in wild-type immature B cells. We further identify a physiologically and significantly higher intracellular Pten level in immature B cells, as compared to mature B cells, which is responsible for low AKT activity and the propensity towards death in immature B cells. Restoration of AKT activity using a constitutive form of AKT or reduction of Pten to a level comparable with that seen in mature B cells rescues immature B cells from BCR-induced apoptosis. Thus, we provide evidence that Pten is an essential mediator of BCR-induced cell death, and that differential regulation of intracellular Pten levels determines whether BCR ligation promotes cell death or survival. Our findings provide a valuable insight into the mechanisms underlying negative selection and clonal deletion of immature B cells.

Resuscitation of hemorrhagic shock attenuates intrapulmonary nitric oxide formation.

Hemorrhagic shock has been shown to upregulate intrapulmonary inducible nitric oxide (NO) synthase (iNOS) expression. Increased intrapulmonary iNOS expression is reflected by increases in concentrations of NO in the airways. The purpose of this study was to examine the effects of resuscitation on this induction of intrapulmonary NO formation caused by hemorrhage. Eighteen rats were randomized to one of three groups. One group of rats was simply sham-instrumented and monitored. Two other groups experienced hemorrhagic shock (mean systemic blood pressure of 40-45 mmHg) for 60 min. In one of the hemorrhagic shock groups, resuscitation was performed by re-infusing the shed blood and supplementing it with normal saline. Compared with sham-instrumented rats, those exposed to hemorrhagic shock without subsequent resuscitation exhibited a 10-fold increase in exhaled NO concentrations. Additionally, concentrations of both intrapulmonary iNOS protein and mRNA increased. Resuscitation attenuated the hemorrhage-induced upregulation of exhaled NO, iNOS protein and iNOS mRNA. This data suggests that resuscitation attenuates the hemorrhagic shock-induced formation of intrapulmonary NO by downregulating iNOS transcription. We believe that exhaled NO concentrations provide a useful, non-invasive method of monitoring the intrapulmonary inflammatory sequelae of hemorrhagic shock.

Environmental pH regulates LPS-induced nitric oxide formation in murine macrophages.

This study was designed to determine how pH affects nitric oxide (NO) formation induced by lipopolysaccharide (LPS) in cultured murine macrophages (RAW 264.7). The initial pH of LPS-containing culture media was adjusted to one of eight values (6.8, 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, and 8.2). After exposure to LPS for eighteen hours, the cultures were harvested for analysis of mRNA, protein, and nitrate/nitrite (stable by-products of NO). Analyses for these substances were performed using semiquantitative RT-PCR, immunoblotting, and colorimetric Griess assays, respectively. We found that acidic culture media favored expression of inducible nitric oxide synthase (iNOS) mRNA. However, alkaline media favored expression of iNOS protein. Our findings suggest that post-transcriptional mechanisms predominate over transcriptional ones in order to regulate pH-mediated effects on NO formation by murine macrophages. The optimal pH for NO formation by iNOS was found in our study to be around 7.2.

Interleukin-10 inhibition of nitric oxide biosynthesis involves suppression of CAT-2 transcription.

Interleukin-10 (IL-10) has been shown to attenuate lipopolysaccharide (LPS) stimulation of inducible nitric oxide synthase (iNOS) in various cell types. Guanosine triphosphate cyclohydrolase I (GTPCH) and type-2 cationic amino acid transporter (CAT-2) are enzymes that regulate iNOS activity. We therefore sought to assess the effects of IL-10 on the expression of these regulatory enzymes in LPS-stimulated macrophages that are known to express iNOS. Five minutes after adding LPS to these macrophage cultures, various doses of recombinant human IL-10 were also added. The samples were harvested for analysis 18 h after exposure to both LPS and IL-10. In LPS-stimulated macrophages, IL-10 attenuated the upregulation of nitric oxide and iNOS protein but not iNOS mRNA. IL-10 also attenuated the LPS-induced upregulation of CAT-2 mRNA. However, IL-10 and LPS had no effect on GTPCH mRNA expression. We therefore conclude that IL-10 inhibits nitric oxide formation in LPS-stimulated macrophages partly by decreasing iNOS protein expression. Moreover, our data suggests that transcriptional control of CAT-2 plays a role in IL-10 mediated influences upon nitric oxide biosynthesis.