Amorphous K-Buserite Microspheres for High-Performance Aqueous Zn-Ion Batteries and Hybrid Supercapacitors.

Aqueous Zn-ion batteries (AZIBs) and Zn-ion hybrid supercapacitors (AZHSCs) are considered promising energy-storage alternatives to Li-ion batteries due to the attractive merits of low-price and high-safety. However, the lack of suitable cathode materials always hinders their large-scale application. Herein, amorphous K-buserite microspheres (denoted as K-MnOx ) are reported as cathode materials for both AZIBs and AZHSCs, and the energy-storage mechanism is systematically revealed. It is found that K-MnOx is composed of rich amorphous K-buserite units, which can irreversibly be transformed into amorphous Zn-buserite units in the first discharge cycle. Innovatively, the transformed Zn-buserite acts as active materials in the following cycles and is highly active/stable for fast Zn-diffusion and superhigh pseudocapacitance, enabling the achievement of high-efficiency energy storage. In the AZIBs, K-MnOx delivers 306 mAh g-1 after 100 cycles at 0.1 A g-1 with 102% capacity retention, while in the AZHSCs, it shows 515.0/116.0 F g-1 at 0.15/20.0 A g-1 with 92.9% capacitance retention at 5.0 A g-1 after 20 000 cycles. Besides, the power/energy density of AZHSCs device can reach up to 16.94 kW kg-1 (at 20 A g-1 )/206.7 Wh kg-1 (at 0.15 A g-1 ). This work may provide some references for designing next-generation aqueous energy-storage devices with high energy/power density.

Economic evaluation of FLOT and ECF/ECX perioperative chemotherapy in patients with resectable gastric or gastro-oesophageal junction adenocarcinoma.

OBJECTIVE: The perioperative chemotherapy with fluorouracil, leucovorin, oxaliplatin plus docetaxel (FLOT) was recommended by the Chinese Society of Clinical Oncology Guidelines for gastric cancer (2018 edition) for patients with resectable gastric or gastro-oesophageal junction adenocarcinoma (class IIA). However, the economic impact of FLOT chemotherapy in China remains unclear. The analysis aimed to compare the cost-effectiveness of FLOT versus epirubicin, cisplatin plus fluorouracil or capecitabine (ECF/ECX) in patients with locally advanced resectable tumours. DESIGN: We developed a Markov model to compare the healthcare and economic outcomes of FLOT and ECF/ECX in patients with resectable gastric or gastro-oesophageal junction adenocarcinoma. Costs were estimated from the perspective of Chinese healthcare system. Clinical and utility inputs were derived from the FLOT4 phase II/III clinical trial and published literature. Sensitivity analyses were employed to assess the robustness of our result. The annual discount rate for costs and health outcomes was set at 5%. OUTCOME MEASURES: The primary outcome of incremental cost-effectiveness ratios (ICERs) was calculated as the cost per quality-adjusted life years (QALYs). RESULTS: The base-case analysis found that compared with ECF/ECX, the use of FLOT chemotherapy was associated with an additional 1.08 QALYs, resulting in an ICER of US$851/QALY. One-way sensitivity analysis results suggested that the HR of overall survival and progression-free survival had the greatest impact on the ICER. Probabilistic sensitivity analysis demonstrated that FLOT was more likely to be cost-effective compared with ECF/ECX at a willingness-to-pay threshold of US$31 513/QALY. CONCLUSIONS: For patients with locally advanced resectable tumours, the FLOT chemotherapy is a cost-effective treatment option compared with ECF/ECX in China. TRIAL REGISTRATION NUMBER: NCT01216644.

Identification of tumor antigens and immune subtypes in breast cancer for mRNA vaccine development.

Background: Poor prognosis, resistance to chemotherapy, insensitivity to radiotherapy, and a high prevalence of adverse drug reactions remain urgent issues for breast cancer (BC) patients. Increased knowledge of tumor immunobiology and vaccine development suggests the possibility of cancer vaccination. Here, we investigated potential BC-associated antigens for the development of an anti-BC mRNA vaccine and populations suitable for mRNA vaccination. Methods: Gene expression and clinical data were obtained from The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC). The single-cell sequencing data were obtained from the Single Cell Portal platform. cBioPortal was used to visualize and compare genetic alterations. Correlations between immune cell infiltration and antigen expression were visualized with the Tumor Immune Estimation Resource (TIMER). Immune subtypes were identified by consensus clustering and analysis of immune infiltration. Biomarkers for the assessment of mRNA vaccination suitability were investigated. Results: Three tumor-associated antigens, CD74, IRF1, and PSME2, that showed overexpression, amplification, and mutation and were linked with prognosis and immune cell infiltration, were identified. Single-cell sequencing analysis showed the expression of the three tumor-associated antigens in different cells of BC. Three immune subtypes were identified among BC patients, with Cluster B patients having a tumor microenvironment conducive to immunotherapy. These subtypes also showed different expression patterns of immune checkpoints, immune cell death-promoting genes, and response to immune checkpoint inhibitor (ICI) therapy. Thus, we identified five biomarkers that could be applied for assessing vaccination suitability and predicted drugs that would be appropriate for patients unsuited for vaccination. Conclusions: Our findings suggest new directions for the development of mRNA vaccines against breast cancer.

Pulmonary toxicity and RNA sequencing analyses of mouse in response to exposure to cellulose nanofibrils.

OBJECTIVE: The growing applications of nanocelluloses in the fields of advanced nanocomposites, electronics, and medical devices necessitate investigation of their potential adverse effects on human health. The lungs are the primary and the most important route for the entry of nanocelluloses into the human body in occupational settings. However, data on the pulmonary toxicity of cellulose nanofibrils (CNFs) and its molecular mechanism are limited. This study investigated the pulmonary toxicity of CNFs and its genomic expression using the RNA sequencing approach. MATERIALS AND METHODS: Female C57BL/6 mice were administered CNFs at 50 µg/mouse by oropharyngeal aspiration. Samples were collected at 3 and 14 days after exposure to CNFs (DAEC). RESULTS: At three DAEC, the microscopic sections of lungs revealed a significant inflammatory response. In terms of gene expression alterations, 94 genes were up-regulated, and 107 genes were down-regulated. Most of these differentially expressed genes were involved in the inflammatory and immune responses, including chemokines, NK cells, killer cell lectin-like receptors, CD antigens, T cell-specific GTPases, immunity-related GTPase family M members, and interferon-induced proteins encoding genes. However, only 9 and 26 genes at 14 DAEC were significantly up- and down-regulated, respectively. CONCLUSIONS: The pathological analysis of lung sections and the analysis of sequencing data suggested that the homeostasis of mice lungs was restored at 14 DAEC. The findings of this study provide insights into the pulmonary toxicity, and underlying toxicological mechanisms, caused by exposure to CNFs, and are useful for the assessment of the potential toxicity of nanocelluloses.

Inhibitory effects of oxymatrine on hepatic stellate cells activation through TGF-ß/miR-195/Smad signaling pathway.

BACKGROUND: Oxymatrine (OM), a quinolizidine alkaloid extracted from a herb Sophorae Flavescentis Radix, has been used to treat liver fibrotic diseases. However, the mechanism of its anti-fibrosis effects is still unclear. TGF-ß/Smad signaling and miR-195 have been proved to paly an important role in hepatic stellate cells (HSCs) activation and liver fibrosis. In this study, we investigated whether OM could inhibit HSCs activation through TGF-ß1/miR-195/Smads signaling or not. METHODS: First, the effects of OM on HSC-T6 in different concentrations and time points were tested by MTT assay. We choose three appropriate concentrations of OM as treatment concentrations in following experiment. By Quantitative Real-time PCR and Western Blot, then we investigated the effect of OM on miR-195, Smad7 and α-SMA's expressions to prove the correlation between OM and the TGF-ß1/miR-195/Smads signaling. Last, miR-195 mimic and INF-γ were used to investigate the relation between miR-195 and OM in HSC activation. RESULTS: Our results showed that the proliferation of HSC was significantly inhibited when OM concentration was higher than 200 µg/mL after 24 h, 100 µg/mL after 48 h and 10 µg/mL after 72 h. The IC50 of OM after 24, 48 and 72 h were 539, 454, 387 µg/mL respectively. OM could down-regulate miR-195 and α-SMA (P < 0.01), while up-regulate Smad7 (P < 0.05). In HSC-T6 cells transfected with miR-195 mimic and pretreated with OM, miR-195 and α-SMA were up-regulated (P < 0.05), and Smad7 was down-regulated (P < 0.05) . CONCLUSIONS: Given these results, OM could inhibit TGF-ß1 induced activation of HSC-T6 proliferation in a dose-dependent and time-dependent manner to some extent. We proved that OM inhibited HSC activation through down-regulating the expression of miR-195 and up-regulating Smad7.

Development of heart failure risk prediction models based on a multi-marker approach using random forest algorithms.

BACKGROUND: The early identification of heart failure (HF) risk may favorably affect outcomes, and the combination of multiple biomarkers may provide a more comprehensive and valuable means for improving the risk of stratification. This study was conducted to assess the importance of individual cardiac biomarkers creatine kinase MB isoenzyme (CK-MB), B-type natriuretic peptide (BNP), galectin-3 (Gal-3) and soluble suppression of tumorigenicity-2 (sST2) for HF diagnosis, and the predictive performance of the combination of these four biomarkers was analyzed using random forest algorithms. METHODS: A total of 193 participants (80 patients with HF and 113 age- and gender-matched healthy controls) were included from June 2017 to December 2017. The correlation and regression analysis were conducted between cardiac biomarkers and echocardiographic parameters. The accuracy and importance of these predictor variables were assessed using random forest algorithms. RESULTS: Patients with HF exhibited significantly higher levels of CK-MB, BNP, Gal-3, and sST2. BNP exhibited a good independent predictive capacity for HF (AUC 0.956). However, CK-MB, sST2, and Gal-3 exhibited a modest diagnostic performance for HF, with an AUC of 0.709, 0.711, and 0.777, respectively. BNP was the most important variable, with a remarkably higher mean decrease accuracy and Gini. Furthermore, there was a general increase in predictive performance using the multi-marker model, and the sensitivity, specificity was 91.5% and 96.7%, respectively. CONCLUSION: The random forest algorithm provides a robust method to assess the accuracy and importance of predictor variables. The combination of CK-MB, BNP, Gal-3, and sST2 achieves improvement in prediction accuracy for HF.

Alterations of secondary sex characteristics, reproductive histology and behaviors by norgestrel in the western mosquitofish (Gambusia affinis).

Synthetic hormones in wastewater effluents released into the aquatic environments may interfere with the normal endocrine systems of fish in receiving streams. Norgestrel (NGT) is a synthetic progestin widely used in oral contraceptives and frequently detected in wastewater effluents. In this study, adult female mosquitofish (Gambusia affinis) were exposed to three environmentally relevant concentrations of norgestrel (NGT) (i.e., 3.6, 35.8, and 368.0 ng L-1) for 42 d, fin morphology, histology of the ovary, and reproductive behaviors were evaluated. The results showed that NGT at all three concentrations caused an increased frequency of atretic follicular cells in ovaries and impaired mating behaviors exhibited by males toward the NGT-exposed females. In mosquitofish exposed to NGT at 35.8 and 368 ng L-1, the anal fin of females had an increased length ratio of ray4/ray 6, an increased width of ray 3, and increased number of segments in ray 3. The histopathological analysis showed that exposure to NGT increased the incidence of spermatogenesis in ovaries. Mating behavior was impaired 58.4%, 65.7%, and 76.4% (P < 0.01 in all cases) when mosquitofish were exposed to NGT at 3.6, 35.6 and 368.0 ng L-1, respectively. The rapid masculinization, the increased frequency of atretic follicles, the incidence of spermatogenesis in the ovary of female fish, and the altered reproductive behaviors suggest that wild populations of mosquitofish could be similarly affected inhabiting in NGT contaminated environments.

Modulation of transcription of genes related to the hypothalamic-pituitary-gonadal and the hypothalamic-pituitary-adrenal axes in zebrafish (Danio rerio) embryos/larvae by androstenedione.

This study aimed to determine the effects of Androstenodione (AED) on the transcriptional expression of genes involved in the hypothalamic-pituitary-gonadal (HPG) and the hypothalamic-pituitary-adrenal (HPA) axes in the zebrafish embryos/larvae. Zebrafish embryos were exposed to 0, 4.0, 45.0, 487.0, and 980.0 ng/L of AED from the day of fertilization to 144 h post fertilization (hpf), during which the transcriptional profiles of key genes related to the HPG and HPA axes were examined daily using quantitative real-time PCR. The AED exposure significantly up-regulated several receptor signaling pathways and the key genes involved in various steps of the steroidogenic pathways were also affected. In addition, the AED exposure could significantly modulate the transcriptional profiles of the other target genes related to hypothalamic and pituitary hormones. The findings of this study suggest that AED, at environmentally relevant concentrations, affects the adrenal endocrine systems and the reproduction of zebrafish by interrupting the HPG and HPA axes.

MicroRNA-195 Activates Hepatic Stellate Cells In Vitro by Targeting Smad7.

BACKGROUND AND AIM: Aberrant activation of the TGF-ß1/Smad pathway contributes to the activation of hepatic stellate cells (HSCs). MicroRNA-195 has been shown to regulate the activation of HSCs. The aim of this study was to investigate the role of miRNA-195 in HSCs activation. METHODS: A liver fibrotic rat model induced by diethylnitrosamine was established. Dual luciferase reporter assays were performed to verify that Smad7 was the target of miRNA-195. The expression levels of miR-195, Smad7, and α-SMA in HSC-T6 transfected, respectively, with miR-195 mimic, inhibitor, or control were measured by qRT-PCR. The protein expression of Smad7 was detected by Western blot analysis. RESULTS: Enhanced miR-195 and decreased Smad7 were observed in diethylnitrosamine-induced liver fibrotic rats (P < 0.05). Dual luciferase reporter assays showed that the miR-195 mimic significantly suppressed the luciferase activity of a reporter plasmid carrying the binding site of miR-195 on the 3'UTR of Smad7 (P < 0.05). The miR-195 mimics activated HSCs, further elevated miR-195 and α-SMA (P < 0.01), and reduced the Smad7 level (P < 0.05). The miR-195 inhibitors blocked the activation of HSCs, reduced the expression of miR-195 and α-SMA (P < 0.01), and upregulated the expression of Smad7 (P < 0.05). CONCLUSION: Collectively, we demonstrated that miRNA-195 activated HSCs by targeting Smad7.

A meta-analysis comparing the efficacy of entecavir and tenofovir for the treatment of chronic hepatitis B infection.

The efficacy of entecavir and tenofovir in patients with chronic hepatitis B virus (HBV) is inconsistent. To address this issue, we conducted a meta-analysis based on a current review of the literature addressing the efficacy and safety of entecavir and tenofovir. Electronic databases were searched through June 2014 for relevant clinical trials. We included 2 randomized controlled trials, 2 prospective cohort studies, and 7 case-control studies that included 1,656 patients. In the entecavir group, 842 of 992 were nucleos(t)ide-naïve chronic HBV patients, and in the tenofovir group 481 of 664 were nucleos(t)ide-naïve. The virological response to tenofovir was superior to entecavir (RR: 0.82; 95%CI: 0.72-0.93), especially in nucleos(t)ide-naïve chronic HBV patients at 48 weeks (RR: 0.78; 95%CI: 0.65-0.92). Additionally, there was no difference between entecavir and tenofovir for virological response at 24 weeks (RR: 0.87, 95%CI: 0.71-1.05). The alanine aminotransferase normalization rate, serological response, and adverse event rate were also not significantly different between entecavir and tenofovir at 24 or 48 weeks after treatment. These results suggest that tenofovir is a better choice to treat chronic HBV patients than entecavir as it is better able to suppress HBV viral load and has a similar safety profile.

Identification of the substrate recognition region in the Δ6-fatty acid and Δ8-sphingolipid desaturase by fusion mutagenesis.

Δ8-sphingolipid desaturase and Δ6-fatty acid desaturase share high protein sequence identity. Thus, it has been hypothesized that Δ6-fatty acid desaturase is derived from Δ8-sphingolipid desaturase; however, there is no direct proof. The substrate recognition regions of Δ6-fatty acid desaturase and Δ8-sphingolipid desaturase, which aid in understanding the evolution of these two enzymes, have not been reported. A blackcurrant Δ6-fatty acid desaturase and a Δ8-sphingolipid desaturase gene, RnD6C and RnD8A, respectively, share more than 80 % identity in their coding protein sequences. In this study, a set of fusion genes of RnD6C and RnD8A were constructed and expressed in yeast. The Δ6- and Δ8-desaturase activities of the fusion proteins were characterized. Our results indicated that (1) the exchange of the C-terminal 172 amino acid residues can lead to a significant decrease in both desaturase activities; (2) amino acid residues 114-174, 206-257, and 258-276 played important roles in Δ6-substrate recognition, and the last two regions were crucial for Δ8-substrate recognition; and (3) amino acid residues 114-276 of Δ6-fatty acid desaturase contained the substrate recognition site(s) responsible for discrimination between ceramide (a substrate of Δ8-sphingolipid desaturase) and acyl-PC (a substrate of Δ6-fatty acid desaturase). Substituting the amino acid residues 114-276 of RnD8A with those of RnD6C resulted in a gain of Δ6-desaturase activity in the fusion protein but a loss in Δ8-sphingolipid desaturase activity. In conclusion, several regions important for the substrate recognition of Δ8-sphingolipid desaturase and Δ6-fatty acid desaturase were identified, which provide clues in understanding the relationship between the structure and function in desaturases.

Usefulness of lumen area parameters determined by intravascular ultrasound to predict functional significance of intermediate coronary artery stenosis.

BACKGROUND: Coronary artery disease is the leading cause of death in China. Percutaneous coronary intervention is a recent milestone technology for treatment coronary artery disease. However, clinical decision making for patients with intermediate coronary stenosis is still controversial. We designed this study to assess the optimal intravascular ultrasound (IVUS) criteria for predicting functional significance of intermediate coronary lesions. METHODS: We enrolled 141 patients with 165 intermediate coronary lesions located in vessels with a diameter ≥ 2.50 mm. IVUS of intermediate coronary lesions were performed before intervention. Pressure-derived fractional flow reserve (FFR) was measured at maximal hyperemia induced by adenosine infusion. An FFR < 0.80 was considered as abnormal functional significance. RESULTS: For the overall 165 lesions, the mean FFR value was 0.84 ± 0.09. The diameter of the stenosis by visual estimation on angiogram was (59.63 ± 11.29)%. Minimum lumen diameter (MLD), minimum lumen area (MLA) and plaque burden (PB) were (2.00 ± 0.36) mm, (3.88 ± 1.34) mm(2), (67.28 ± 9.89)% respectively by IVUS measurements. An FFR < 0.80 was seen in 43 lesions (30.5%). There was a moderate correlation between IVUS parameters and FFR, including MLD (r = 0.372, P < 0.001), MLA (r = 0.442, P < 0.001) and PB (r = -0.172, P < 0.05). MLA was a predictor for FFR as a continuous variable independent of possible confounding variables (P < 0.05), and MLA and PB, were predictors for FFR < 0.80 as binary variables (P < 0.05). The best cutoff value of MLA to predict FFR < 0.80 was < 3.15 mm(2), with a 73.6% diagnostic accuracy; sensitivity 71.4%, specificity 67.0%, AUC = 0.709, and P < 0.001. The cutoff value of the PB to predict FFR < 0.80 was 65.45%; sensitivity 82.6%, specificity 41.2%, AUC = 0.644, and P < 0.01. If both MLA and PB were taken into account, the negative predictive value and the positive predictive value were 88.7% and 64.8% respectively. CONCLUSIONS: Anatomic measurements of intermediate coronary lesions obtained by IVUS showed a moderate correlation to FFR values. IVUS-derived MLA ≥ 3.15 mm(2) may be useful to exclude FFR < 0.80, but poor specificity limits its applicability for physiological assessment of lesions < 3.15 mm(2). MLA was one of many factors affecting coronary flow hemodynamics. Both MLA and PB should be taken into account when determining functional ischemia.

The role of C-terminal amino acid residues of a Δ6-fatty acid desaturase from blackcurrant.

Δ6-fatty acid desaturase is an important enzyme in the catalytic synthesis of polyunsaturated fatty acids. Using domain swapping and a site-directed mutagenesis strategy, we found that the region of the C-terminal 67 amino acid residues of Δ6-fatty acid desaturase RnD6C from blackcurrant was essential for its catalytic activity and that seven different residues between RnD6C and RnD8A in that region were involved in the desaturase activity. Compared with RnD6C, the activity of the following mutations, V394A, K395I, F411L, S436P, VK3945AI and IS4356VP, was significantly decreased, whereas the activity of I417T was significantly increased. The amino acids N, T and Y in the last four residues also play a certain role in the desaturase activity.

Isolation and functional characterisation of the genes encoding Δ(8)-sphingolipid desaturase from Brassica rapa.

Δ(8)-Sphingolipid desaturase is the key enzyme that catalyses desaturation at the C8 position of the long-chain base of sphingolipids in higher plants. There have been no previous studies on the genes encoding Δ(8)-sphingolipid desaturases in Brassica rapa. In this study, four genes encoding Δ(8)-sphingolipid desaturases from B. rapa were isolated and characterised. Phylogenetic analyses indicated that these genes could be divided into two groups: BrD8A, BrD8C and BrD8D in group I, and BrD8B in group II. The two groups of genes diverged before the separation of Arabidopsis and Brassica. Though the four genes shared a high sequence similarity, and their coding desaturases all located in endoplasmic reticulum, they exhibited distinct expression patterns. Heterologous expression in Saccharomyces cerevisiae revealed that BrD8A/B/C/D were functionally diverse Δ(8)-sphingolipid desaturases that catalyse different ratios of the two products 8(Z)- and 8(E)-C18-phytosphingenine. The aluminium tolerance of transgenic yeasts expressing BrD8A/B/C/D was enhanced compared with that of control cells. Expression of BrD8A in Arabidopsis changed the ratio of 8(Z):8(E)-C18-phytosphingenine in transgenic plants. The information reported here provides new insights into the biochemical functional diversity and evolutionary relationship of Δ(8)-sphingolipid desaturase in plants and lays a foundation for further investigation of the mechanism of 8(Z)- and 8(E)-C18-phytosphingenine biosynthesis.

Enhanced tolerance to NaCl and LiCl stresses by over-expressing Caragana korshinskii sodium/proton exchanger 1 (CkNHX1) and the hydrophilic C terminus is required for the activity of CkNHX1 in Atsos3-1 mutant and yeast.

Sodium/proton exchangers (NHX antiporters) play important roles in plant responses to salt stress. Previous research showed that hydrophilic C-terminal region of Arabidopsis AtNHX1 negatively regulates the Na(+)/H(+) transporting activity. In this study, CkNHX1 were isolated from Caragana korshinskii, a pea shrub with high tolerance to salt, drought, and cold stresses. Transcripts of CkNHX1 were detected predominantly in roots, and were significantly induced by NaCl stress in stems. Transgenic yeast and Arabidopsisthalianasos3-1 (Atsos3-1) mutant over-expressing CkNHX1 and its hydrophilic C terminus-truncated derivative, CkNHX1-ΔC, were generated and subjected to NaCl and LiCl stresses. Expression of CkNHX1 significantly enhanced the resistance to NaCl and LiCl stresses in yeast and Atsos3-1 mutant. Whereas, compared with expression of CkNHX1, the expression of CkNHX1-ΔC had much less effect on NaCl tolerance in Atsos3-1 and LiCl tolerance in yeast and Atsos3-1. All together, these results suggest that the predominant expression of CkNHX1 in roots might contribute to keep C. korshinskii adapting to the high salt condition in this plant's living environment; CkNHX1 could recover the phenotype of Atsos3-1 mutant; and the hydrophilic C-terminal region of CkNHX1 should be required for Na(+)/H(+) and Li(+)/H(+) exchanging activity of CkNHX1.

Newly identified essential amino acid residues affecting Δ8-sphingolipid desaturase activity revealed by site-directed mutagenesis.

In order to identify amino acid residues crucial for the enzymatic activity of Δ(8)-sphingolipid desaturases, a sequence comparison was performed among Δ(8)-sphingolipid desaturases and Δ(6)-fatty acid desaturases from various plants. In addition to the known conserved cytb(5) (cytochrome b(5)) HPGG motif and three conserved histidine boxes, they share additional 15 completely conserved residues. A series of site-directed mutants were generated using our previously isolated Δ(8)-sphingolipid desaturase gene from Brassica rapa to evaluate the importance of these residues to the enzyme function. The mutants were functionally characterized by heterologous expression in yeast, allowing the identification of the products of the enzymes. The results revealed that residues H63, N203, D208, D210, and G368 were obligatorily required for the enzymatic activity, and substitution of the residues F59, W190, W345, L369 and Q372 markedly decreased the enzyme activity. Among them, replacement of the residues W190, L369 and Q372 also has significant influence on the ratio of the two enzyme products. Information obtained in this work provides the molecular basis for the Δ(8)-sphingolipid desaturase activity and aids in our understanding of the structure-function relationships of the membrane-bound desaturases.

Genes encoding the biotin carboxylase subunit of acetyl-CoA carboxylase from Brassica napus and parental species: cloning, expression patterns, and evolution.

Comparative genomics is a useful tool to investigate gene and genome evolution. Biotin carboxylase (BC), an important subunit of heteromeric acetyl-CoA carboxylase (ACCase) that is a rate-limiting enzyme in fatty acid biosynthesis in dicots, catalyzes ATP, biotin carboxyl carrier protein, and CO2 to form carboxybiotin carboxyl carrier protein. In this study, we cloned four genes encoding BC from Brassica napus L. (namely BnaC.BC.a, BnaC.BC.b, BnaA.BC.a, and BnaA.BC.b), and two were cloned from each of the two parental species Brassica rapa L. (BraA.BC.a and BraA.BC.b) and Brassica oleracea L. (BolC.BC.a and BolC.BC.b). Sequence analyses revealed that in B. napus the genes BnaC.BC.a and BnaC.BC.b were from the C genome of B. oleracea, whereas BnaA.BC.a and BnaA.BC.b were from the A genome of B. rapa. Comparative and cluster analysis indicated that these genes were divided into two major groups, BnaC.BC.a, BnaA.BC.a, BraA.BC.a, and BolC.BC.a in group-1 and BnaC.BC.b, BnaA.BC.b, BraA.BC.b, and BolC.BC.b in group-2. The divergence of group-1 and group-2 genes occurred in their common ancestor 13-17 million years ago (MYA), soon after the divergence of Arabidopsis and Brassica (15-20 MYA). This time of divergence is identical to the previously reported triplicated time of paralogous subgenomes of diploid Brassica species and the divergence date of group-1 and group-2 genes of α-carboxyltransferase, another subunit of heteromeric ACCase, in Brassica. Reverse transcription PCR revealed that the expression level of group-1 and group-2 genes varied in different organs, and the expression patterns of the two groups of genes were similar in different organs, except in flower. However, two paralogs of group-2 BC genes from B. napus could express differently in mature plants tested by generating BnaA.BC.b and BnaC.BC.b promoter-ß-glucuronidase (GUS) fusions. The amino acid sequences of proteins encoded by these genes were highly conserved, except the sequence encoding predicted plastid transit peptides. The plastid transit peptides on the BC precursors of Brassica (71-72 amino acid residues) were predicted based on AtBC protein, compared, and confirmed by fusion with green fluorescent protein. Our results will be helpful in elucidating the evolution and the regulation of ACCase in the genus Brassica.

Genes encoding the alpha-carboxyltransferase subunit of acetyl-CoA carboxylase from Brassica napus and parental species: cloning, expression patterns, and evolution.

Heteromeric acetyl coenzyme A carboxylase (ACCase), a rate-limiting enzyme in fatty acid biosynthesis in dicots, is a multi-enzyme complex consisting of biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase (alpha-CT and beta-CT). In the present study, four genes encoding alpha-CT were cloned from Brassica napus, and two were cloned from each of the two parental species, B. rapa and B. oleracea. Comparative and cluster analyses indicated that these genes were divided into two major groups. The major divergence between group-1 and group-2 occurred in the second intron. Group-2 alpha-CT genes represented the ancestral form in the genus Brassica. The divergence of group-1 and group-2 genes occurred in their common ancestor 12.96-17.78 million years ago (MYA), soon after the divergence of Arabidopsis thaliana and Brassica (15-20 MYA). This time of divergence is identical to that reported for the paralogous subgenomes of diploid Brassica species (13-17 MYA). Real-time reverse transcription PCR revealed that the expression patterns of the two groups of genes were similar in different organs, except in leaves. To better understand the regulation and evolution of alpha-CT genes, promoter regions from two sets of orthologous gene copies from B. napus, B. rapa, and B. oleracea were cloned and compared. The function of the promoter of gene Bnalpha-CT-1-1 in group-1 and gene Bnalpha-CT-2-1 in group-2 was examined by assaying beta-glucuronidase activity in transgenic A. thaliana. Our results will be helpful in elucidating the evolution and regulation of ACCase in oilseed rape.

Lead and cadmium induced alterations of cellular functions in leaves of Alocasia macrorrhiza L. Schott.

Alocasia macrorrhiza is a fast growing and propagating herbaceous species commonly found in South China. To determine its physiological responses to Pb and Cd stresses, the biochemical, histochemical and cytochemical changes under PbAC2 and CdCl2 phytotoxicity were detected using leaf discs as an experimental model. After leaf discs were infiltrated in different concentrations of PbAC2 and CdCl2 solutions (0, 50, 100, 150, 200 microM) for 72 h, the formation of reactive oxygen species (H2O2 and O2-) in plant tissue were found to be exaggerated together with elevated OH concentration and cell death. Changes in chlorophyll fluorescence (Fv/Fm, PhiPSII, qP and NPQ) imaging colours/areas of leaf discs indicated decreased photosystem II functions by both heavy metal treatments and positive reactions of antioxidants under Pb2+ stress. Results showed that fluorescent detection of hydroxylated terephthlate using terephthalic acid as OH trap is a simple, yet valuable and specific method for monitoring OH generation in plant tissue under heavy metal stresses. As compared with Cd2+, Pb2+ was found to be less toxic, indicating that A. macrorrhiza tissue might have a potential tolerance to Pb.

Identification and functional analysis of the genes encoding Delta6-desaturase from Ribes nigrum.

Gamma-linolenic acid (gamma-linolenic acid, GLA; C18:3 Delta(6, 9, 12)) belongs to the omega-6 family and exists primarily in several plant oils, such as evening primrose oil, blackcurrant oil, and borage oil. Delta(6)-desaturase is a key enzyme involved in the synthesis of GLA. There have been no previous reports on the genes encoding Delta(6)-desaturase in blackcurrant (Ribes nigrum L.). In this research, five nearly identical copies of Delta(6)-desaturase gene-like sequences, named RnD8A, RnD8B, RnD6C, RnD6D, and RnD6E, were isolated from blackcurrant. Heterologous expression in Saccharomyces cerevisiae and/or Arabidopsis thaliana confirmed that RnD6C/D/E were Delta(6)-desaturases that could use both alpha-linolenic acids (ALA; C18:3 Delta(9,12,15)) and linoleic acid (LA; C18:2 Delta(9,12)) precursors in vivo, whereas RnD8A/B were Delta(8)-sphingolipid desaturases. Expression of GFP tagged with RnD6C/D/E showed that blackcurrant Delta(6)-desaturases were located in the mitochondrion (MIT) in yeast and the endoplasmic reticulum (ER) in tobacco. GC-MS results showed that blackcurrant accumulated GLA and octadecatetraenoic acids (OTA; C18:4 Delta(6,9,12,15)) mainly in seeds and a little in other organs and tissues. RT-PCR results showed that RnD6C and RnD6E were expressed in all the tissues at a low level, whereas RnD6D was expressed at a high level only in seeds, leading to the accumulation of GLA and OTA in seeds. This research provides new insights to our understanding of GLA synthesis and accumulation in plants and the evolutionary relationship of this class of desaturases, and new clues as to the amino acid determinants which define precise enzyme activity.