Phloem unloading in the potato tuber. Pathways and sites of ATPase

Summary Potential pathways for sucrose unloading in the potato tuber were examined by light and electron microscopy. Abundant plasmodesmata connected sieve elements with surrounding parenchyma elements and also sieve elements with companion cells. Plasmodesmata were rarer, however, between companion cells and parenchyma elements. These observations suggest that sucrose may leave the sieve elements and enter the storage parenchyma cells directly via the symplast and that transport through the companion cell may not be a prerequisite for unloading. Plasmodesmata, grouped together in primary pit fields, were also abundant between storage cells, and isolated storage cells, separated enzymically, showed considerable variation in plasmodesmatal distribution between cells and also on different faces of a single cell. Deposition of starch was found to occur in the tuber cortex while an endodermis with Casparian strip was present external to the phloem, suggesting that assimilates initially enter the cortical storage cells by an entirely symplastic pathway. The possible involvement of ATPase in the unloading process was examined cytochemically, using a lead-salt precipitation method. By contrast with previous findings for phloem no evidence was found for ATPase activity that was unique to the sieve element-companion cell complex. The present observations favour the view that phloem unloading in the potato tuber is a symplastic and passive process.     

Secondary metabolites in transgenic tobacco and potato: high accumulation of 4-hydroxybenzoic acid glucosides results from high expression of the bacterial gene ubiC

The bacterial gene ubiC encodes chorismate pyruvate-lyase (CPL), which converts chorismate to 4-hydroxybenzoate (4HB). The ubiC gene was expressed in tobacco (Nicotiana tabacum L., Solanaceae) and potato (Solanum tuberosum L., Solanaceae) under the control of the very strong constitutive plant promotor (ocs₃) mas. High accumulation of 4HB glucosides as new, artificial secondary metabolites was observed in the transgenic plants. 4HB glucoside content reached 5.1% of dry weight in tobacco cell cultures and 4.0% of dry weight in the leaves of potato shoots. This is the highest content of an artificial secondary metabolite produced by genetic engineering of plants reported so far. Surprisingly, no growth retardation and no phenotypical changes were observed in the transgenic cell cultures and plants. Glucosylation of 4HB was achieved by endogeneous, constitutively expressed glucosyltransferases. The total amount of 4HB glucoside acccumulated showed a strict linear dependence on the expression level of ubiC.     

水菠菜叶乙醇提取物对MG-63骨质疏松相关基因表达的影响

为探讨水菠菜叶乙醇提取物与抗骨质疏松作用的关系及其作用机制,用水菠菜叶乙醇提取物处理人成骨样细胞MG-63 48 h后,提取水菠菜叶乙醇提取处理组和对照组细胞的总RNA,将两组RNA纯化为mRNA,逆转录成cDNA,用Cy3和Cy5两种不同的荧光染料进行线性扩增标记,然后与骨质疏松相关基因表达谱芯片杂交,扫描后对获得的数据用LuxScan 3.0软件分析.研究发现经水菠菜叶乙醇提取物诱导后MG-63细胞的244个骨质疏松相关基因中,有c-Fos、JNK、ODF、c-src、OSCAR、RANKL、Samd4、Samd6、Samd7 9个基因表达明显上调,LRP5、Dkk1、TGFB、OPG 4个基因明显下调.结果表明水菠菜叶乙醇提取物能改变骨质疏松相关基因的表达,抗骨质疏松作用机制可能与Wnt/β-catenin蛋白信号传导途径和骨保护素/核因子受体激活信号传导途径有关,与雌激素内分泌途径无关.     

Expression of the triose phosphate translocator gene from potato is light dependent and restricted to green tissues

The export of primary photosynthesis products from chloroplasts into the cytoplasm is mediated by the triose phosphate translocator. The transporter is an integral membrane protein localized at the inner envelope of chloroplasts. In order to study the expression of the major chloroplast envelope protein gene E29, which is assumed to function as the translocator, we have isolated corresponding cDNA clones from potato. A full-length clone was sequenced and shown to be highly homologous to the E29 gene from spinach. Expression on the RNA level is restricted to green tissues, is light dependent and cannot be induced by sucrose in darkness. The presence of a single-copy gene argues for the existence of different translocator systems responsible for import and export of carbohydrates in chloroplasts and amyloplasts.     

Effects of Thymus kotschyanus var. glabrescens Boiss. extract on mitomycin-C induced chromosomal aberrations and sister chromatid exchanges in human lymphocytes

In this investigation, clastogenic effects of Thymus kotschyanus var. glabrescens Boiss. extract (TE) and anticlastogenic effects of this extract against Mitomycin C (MMC) induced chromosome damage have been evaluated in human peripheral blood lymphocytes in vitro. Two series of experiments were conducted. In the first, only 10⁻⁵, 10⁻⁴, 10⁻³ and 10⁻² μl ml⁻¹ concentrations of TE were used for 48 h to detect potential clastogenicity. In the second, MMC (0.38 μg ml⁻¹) plus 10⁻⁵, 10⁻⁴, 10⁻³ and 10⁻² μl ml⁻¹ concentrations of TE were used for 48 h to determine anticlastogenic effects. TE did not increase sister chromatid exchanges (SCEs) (except 10⁻² μl ml concentration) and chromosome aberrations (CAs) significantly compared with negative and solvent controls. However, it decreased the frequency of MMC induced chromosome aberrations. Decreasing was significant at 10⁻⁴, 10⁻³ and 10⁻² μl ml⁻¹ concentrations. On the other hand, TE significantly increased MMC-induced SCEs for all treatment groups compared with positive control.     

Identification of phytochemical components from Aerva lanata (Linn.) medicinal plants and its in-vitro inhibitory activity against drug resistant microbial pathogens and antioxidant properties

This study aimed to determine the phytochemical components, microbial inhibitory effectiveness and antioxidant properties of Aerva lanata plant extracts. The whole plant showed various medicinal applications in folklore and traditional medicine in various parts of the world. The organic extracts such as ethanol, ethyl acetate, chloroform, acetone, water and methanol were subjected for various phytochemical analysis and confirmed for the existence of flavonoids, glycosides, terpenoids and alkaloid containing components. Alternatively, the extracts were performed for the antibacterial activities against the microbial pathogens and antioxidant properties. Results indicated that, the solvent extracts showed prominent activity against the tested strains. The MIC concentrations of plant were detected from 5 mg/ml to 40 mg/ml. The plant extract was highly effective against E. coli and E. aerogenes and the MIC was 5 mg/ml. In addition, the extracts noted promising antioxidant activities. The antioxidant activities were dose dependent manner. In conclusion, A. lanata extracts showed that significant major phytochemicals and effective antioxidant and anti-microbial properties.     

Toward consistent and productive complex media for industrial fermentations: studies on yeast extract for a recombinant yeast fermentation process

Yeast extract (YE) is commonly used as a key component in the complex media for industrial fermentations. However, the lot-to-lot variation of this raw material frequently requires extensive "use testing" of many lots to identify only the few that support desired fermentation performance. Through extensive fermentation studies and chemical analyses, we have identified adenine and two metabolizable carbon sources, trehalose and lactate, as the principle components in YE that affect the production of a recombinant protein antigen by a yeast strain. Adenine is required for culture growth and the relationship between biomass and measured adenine can be expressed by a Michaelis-Menten model, while the slowly metabolized trehalose serves to maintain the energy supply to the continued antigen synthesis. The rapidly utilized lactate exerts an indirect positive effect by sparing some of the accumulated ethanol from being consumed for growth to being utilized in the product formation. The effects of these YE components are mutually dependent. Based on the database generated from 40 lots at laboratory scale, a relatively high level of carbon sources in YE (trehalose plus lactate, >9.5% w/w) and an intermediate level of adenine (0.14-0.24% w/w) appear to be the minimal requirement of a good lot for this recombinant yeast fermentation. Many poor lots were improved in lab fermenters by rational supplementation of trehalose, lactate, or adenine to compensate for their insufficiencies. At the large production scale, predictions based on adenine and trehalose/lactate contents in various YE lots used correlated reasonably well with culture growth and antigen yield, illustrating the feasibility of such a simple chemical/biochemical analysis as a rapid and reliable initial screening tool. Without incurring any compositional change to an established manufacturing medium, this study demonstrates an effective approach to achieve consistency in fermentations employing complex nutrients and to improve fermentation productivities supported by suboptimal lots of raw material.     

Key Odorants in Cured Madagascar Vanilla Beans (Vanilla planiforia) of Differing Bean Quality

The effects of pressure on the enzyme activities of Lacto-bacillus helveticus LHE-511 were examined. Treatment at 400 MPa at 30°C for 10 min completely inhibited acid-producing activity, but the activities of aminopeptidase (AP) and X-prolyl dipeptidyl aminopeptidase (X-PDAP), which are important for acceleration of cheese ripening, increased. These results showed that pressure treatment of L. helveticus LHE-511 selectively inactivates its acid-producing activity.     

Effects of Plantago lanceolata L. extract on full-thickness excisional wound healing in a mouse model

Wound healing requires cells that increase both collagen production as a result of inflammatory events and regeneration of epithelial tissue. The Plantago species of herbs have been used in traditional treatment of skin disorders and infectious diseases, and digestive, respiratory, reproductive and circulatory conditions. We investigated the efficacy of different concentrations of Plantago lanceolata L. extract (PLE) for wound healing owing to its anti-inflammatory, anti-bacterial, anti-fungal, anti-oxidant, anti-ulcerative, analgesic and immunomodulatory properties. We used 72 mice in four groups of 18. An excisional 1 cm wound was created in the skin on the back of the mice in all groups. An ointment containing 10% PLE was applied to the wound in group 1, an ointment containing 20% PLE was applied in group 2 and vaseline was applied in group 3. In group 4, no treatment was applied to the wound. On days 7, 14, and 21 of the experiment, six animals in each group were sacrificed after the wounds were photographed and specimens from the wound sites were examined. On day 14, epithelialization was more prominent in group 2, while vascularization and collagen deposition was more advanced in groups 1 and 2 compared to the other groups. Immunohistochemical examination revealed that TGF-β1 expression was elevated on day 14 in all groups; however, this elevation was more limited in groups 1 and 2 than in groups 3 and 4. Although ANGPT-2 expression increased in groups 1 and 4 on day 14, it decreased significantly in groups 2 and 3. We found that different concentrations of PLE exhibited positive effects on wound healing. Application of 10% PLE ointment may be a useful strategy for wound healing.     

Flavor Components of Roasted Almond

Roasted almond volatiles were separated into basic, carbonyl and non-carbonyl fractions. Each fraction was analyzed by combination gas chromatography-mass spectrometry. Twenty-five compounds, in addition to eighteen known components, were identified. Many of the components identified were considered to contribute to the overall flavor. 2,5-Dimethyl-4- hydroxy-3(2H)-furanone, which was identified from methanol extract of roasted almond, seemed to make the largest contribution to the sweet aroma of roasted almond.