Promotion by 5-Aminolevulinic Acid of Germination of Pakchoi (Brassica campestris ssp. chinensis var. communis Tsen et Lee) Seeds Under Salt Stress

The seed germination and seedling growth of pakchoi (Brassica campestris ssp. chinensis var.communis Tsen et Lee cv. Hanxiao) were not significantly inhibited until the concentration of NaCl was increased to150 mmol/L. Treatment of pakchoi seeds with exogenous 5-aminolevulinic acid (ALA), at concentrations ranging from 0.01 to 10.00 mg/L, promoted seed germination when seeds were stressed by salinity, whereas levulinic acid (LA), an inhibitor of ALA dehydrase, significantly inhibited seed germination and seedling growth, suggesting that metabolism of ALA into porphyrin compounds was necessary for seed germination and seedling growth. Determination of respiratory rate during seed germination showed that ALA increased seed respiration under both normal conditions and salt stress. Furthermore, salt stress decreased levels of endogenous ALA, as well as heme, in etiolated seedlings. More salt-tolerant cultivars of pakchoi contained higher relative levels of endogenous ALA and heme under conditions of salt stress.These results indicate that salt stress may inhibit the biosynthesis of endogenous ALA and then heme,which is necessary for seed germination, and treatment of seeds with exogenous ALA prior to germination may be associated with the biosynthesis of heme.     

Functional analysis and tissue-differential expression of four FAD2 genes in amphidiploid Brassica napus derived from Brassica rapa and Brassica oleracea

Fatty acid desaturase 2 (FAD2), which resides in the endoplasmic reticulum (ER), plays a crucial role in producing linoleic acid (18:2) through catalyzing the desaturation of oleic acid (18:1) by double bond formation at the delta 12 position. FAD2 catalyzes the first step needed for the production of polyunsaturated fatty acids found in the glycerolipids of cell membranes and the triacylglycerols in seeds. In this study, four FAD2 genes from amphidiploid Brassica napus genome were isolated by PCR amplification, with their enzymatic functions predicted by sequence analysis of the cDNAs. Fatty acid analysis of budding yeast transformed with each of the FAD2 genes showed that whereas BnFAD2-1, BnFAD2-2, and BnFAD2-4 are functional enzymes, and BnFAD2-3 is nonfunctional. The four FAD2 genes of B. napus originated from synthetic hybridization of its diploid progenitors Brassica rapa and Brassica oleracea, each of which has two FAD2 genes identical to those of B. napus. The BnFAD2-3 gene of B. napus, a nonfunctional pseudogene mutated by multiple nucleotide deletions and insertions, was inherited from B. rapa. All BnFAD2 isozymes except BnFAD2-3 localized to the ER. Nonfunctional BnFAD2-3 localized to the nucleus and chloroplasts. Four BnFAD2 genes can be classified on the basis of their expression patterns.     

Alpha lipoic acid inhibits oxidative stress‐induced apoptosis by modulating of Nrf2 signalling pathway after traumatic brain injury

Alpha lipoic acid (ALA) is a powerful antioxidant which has been widely used in the treatment of different system diseases, such as cardiovascular and cerebrovascular diseases. But, there are few studies that refer to protective effects and potential mechanisms on traumatic brain injury (TBI). This study was carried out to investigate the neuroprotective effect following TBI and illuminate the underlying mechanism. Weight drop‐injured model in rats was induced by weight‐drop. ALA was administrated via intraperitoneal injection after TBI. Neurologic scores were examined following several tests. Neurological score was performed to measure behavioural outcomes. Nissl staining and TUNEL were performed to evaluate the neuronal apoptosis. Western blotting was engaged to analyse the protein content of the Nuclear factor erythroid 2‐related factor 2 (Nrf2) and its downstream protein factors, including hemeoxygenase‐1 (HO‐1) and quinine oxidoreductase‐1 (NQO1). ALA treatment alleviated TBI‐induced neuron cell apoptosis and improved neurobehavioural function by up‐regulation of Nrf2 expression and its downstream protein factors after TBI. This study presents new perspective of the mechanisms responsible for the neuronal apoptosis of ALA, with possible involvement of Nrf2 pathway.     

Oxygen‐dependent delayed fluorescence of protoporphyrin IX measured in the stomach and duodenum during upper gastrointestinal endoscopy

Protoporphyrin IX‐triplet state lifetime technique (PpIX‐TSLT) is a method used to measure oxygen (PO₂) in human cells. The aim of this study was to assess the technical feasibility and safety of measuring oxygen‐dependent delayed fluorescence of 5‐aminolevulinic acid (ALA)‐induced PpIX during upper gastrointestinal (GI) endoscopy. Endoscopic delayed fluorescence measurements were performed 4 hours after oral administration of ALA in healthy volunteers. The ALA dose administered was 0, 1, 5 or 20 mg/kg. Measurements were performed at three mucosal spots in the gastric antrum, duodenal bulb and descending duodenum with the catheter above the mucosa and while applying pressure to induce local ischemia and monitor mitochondrial respiration. During two endoscopies, measurements were performed both before and after intravenous administration of butylscopolamine. Delayed fluorescence measurements were successfully performed during all 10 upper GI endoscopies. ALA dose of 5 mg/kg showed adequate signal‐to‐noise ratio (SNR) values >20 without side effects. All pressure measurements showed significant prolongation of delayed fluorescence lifetime compared to measurements performed without pressure (P < .001). Measurements before and after administration of butylscopolamine did not differ significantly in the duodenal bulb and descending duodenum. Measurements of oxygen‐dependent delayed fluorescence of ALA‐induced PpIX in the GI tract during upper GI endoscopy are technically feasible and safe.     

Identification of genes and pathways involved in the synthesis of Mead acid (20:3n − 9), an indicator of essential fatty acid deficiency

In mammals, 5,8,11-eicosatrienoic acid (Mead acid, 20:3n − 9) is synthesized from oleic acid during a state of essential fatty acid deficiency (EFAD). Mead acid is thought to be produced by the same enzymes that synthesize arachidonic acid and eicosapentaenoic acid, but the genes and the pathways involved in the conversion of oleic acid to Mead acid have not been fully elucidated. The levels of polyunsaturated fatty acids in cultured cells are generally very low compared to those in mammalian tissues. In this study, we found that cultured cells, such as NIH3T3 and Hepa1–6 cells, have significant levels of Mead acid, indicating that cells in culture are in an EFAD state under normal culture conditions. We then examined the effect of siRNA-mediated knockdown of fatty acid desaturases and elongases on the level of Mead acid, and found that knockdown of Elovl5, Fads1, or Fads2 decreased the level of Mead acid. This and the measured levels of possible intermediate products for the synthesis of Mead acid such as 18:2n − 9, 20:1n − 9 and 20:2n − 9 in the knocked down cells indicate two pathways for the synthesis of Mead acid: pathway 1) 18:1n − 9 → (Fads2) → 18:2n − 9 → (Elovl5) → 20:2n − 9 → (Fads1) → 20:3n − 9 and pathway 2) 18:1n − 9 → (Elovl5) → 20:1n − 9 → (Fads2) → 20:2n − 9 → (Fads1) → 20:3n − 9.     

外源ALA、SNP和Spd对NaCl胁迫下桔梗种子萌发特性的影响

以药用植物桔梗为研究对象,通过测定不同浓度的ALA、SNP和Spd对NaCl胁迫下桔梗种子发芽势、发芽率、萌发指数和平均根长等萌发指标的影响,寻找提高桔梗种子及幼苗在盐胁迫条件下抗性能力的途径.实验结果表明,75 mmol·L-1 NaCl胁迫下的桔梗种子萌发受到显著抑制,但是用不同浓度的ALA、SNP和Spd对桔梗种...     

Arrest of chlorophyll accumulation prior to anthocyanin formation in Euphorbia pulcherrima

Euphorbia pulcherrima Klotz plants exposed to short days (11 h light/13 h dark) for a period of eight weeks, developed flowers and a red canopy consisting of bracts and few true leaves. Plants maintained for three weeks under short day conditions, failed to produce flower primordia or a red canopy in the following 5 weeks in continuous light. Between the 4th and 5th short day week, the youngest leaves began to accumulate anthocyanin and turned red while the apical meristems differentiated into flower primordia. Chlorophyll accumulation ceased at the onset of anthocyanin synthesis and the protein content per unit leaf area declined. mRNA for glutamyl-tRNA^Glu synthetase (EC 6.1.1.17) and glutamyl-tRNA^Glu reductase also declined during this period. Western blot analysis revealed a loss of glutamyl-tRNA^Glu reductase, glutamate 1-semialdehyde (EC 5.4.3.8) and the Mg-chelatase subunits, Olive and CH42, in the last 2 to 4 weeks of the photoperiod.     

Activatable fluorescent probes in fluorescence-guided surgery: Practical considerations

Fluorescence-guided imaging during surgery is a promising technique that is increasingly used to aid surgeons in identifying sites of tumor and surgical margins. Of the two types of fluorescent probes, always-on and activatable, activatable probes are preferred because they produce higher target-to-background ratios, thus improving sensitivity compared with always-on probes that must contend with considerable background signal. There are two types of activatable probes: 1) enzyme-reactive probes that are normally quenched but can be activated after cleavage by cancer-specific enzymes (activity-based probes) and 2) molecular-binding probes which use cancer targeting moieties such as monoclonal antibodies to target receptors found in abundance on cancers and are activated after internalization and lysosomal processing (binding-based probes). For fluorescence-guided intraoperative surgery, enzyme-reactive probes are superior because they can react quickly, require smaller dosages especially for topical applications, have limited side effects, and have favorable pharmacokinetics. Enzyme-reactive probes are easier to use, fit better into existing work flows in the operating room and have minimal toxicity. Although difficult to prove, it is assumed that the guidance provided to surgeons by these probes results in more effective surgeries with better outcomes for patients. In this review, we compare these two types of activatable fluorescent probes for their ease of use and efficacy.     

Brain protection by rapeseed oil in magnesium-deficient mice

Diets given for 30 days with various mono-(MUFA) and poly-(PUFA) unsaturated fatty acid contents were evaluated for brain protection in magnesium-deficient mice: a commercial and three synthetic diets (n-6PUFA, n-3PUFA and MUFA-based chows enriched with 5% corn/sunflower oils 1:3, with 5% rapeseed oil and with 5% high oleic acid sunflower oil/sunflower oil 7:3, respectively). Unlike magnesium deprivation, they induced significant differences in brain and erythrocyte membrane phospholipid fatty acid compositions. n-3PUFA but not other diets protected magnesium-deficient mice against hyperactivity and moderately towards maximal electroshock- and NMDA-induced seizures. This diet also inhibited audiogenic seizures by 50%, preventing animal deaths. Because, like n-6PUFA diet, matched control MUFA diet failed to induce brain protections, alpha-linolenate (ALA) rather than reduced n-6 PUFA diet content is concluded to cause n-3PUFA neuroprotection. Present in vivo data also corroborate literature in vitro inhibition of T type calcium channels by n-3 PUFA, adding basis to ALA supplementation in human anti-epileptic/neuroprotective strategies.