共查询到20条相似文献,搜索用时 15 毫秒
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Leanne Pearson Troco Mihali Michelle Moffitt Ralf Kellmann Brett Neilan 《Marine drugs》2010,8(5):1650-1680
The cyanobacteria or “blue-green algae”, as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity. Many aquatic, bloom-forming species of cyanobacteria are capable of producing biologically active secondary metabolites, which are highly toxic to humans and other animals. From a toxicological viewpoint, the cyanotoxins span four major classes: the neurotoxins, hepatotoxins, cytotoxins, and dermatoxins (irritant toxins). However, structurally they are quite diverse. Over the past decade, the biosynthesis pathways of the four major cyanotoxins: microcystin, nodularin, saxitoxin and cylindrospermopsin, have been genetically and biochemically elucidated. This review provides an overview of these biosynthesis pathways and additionally summarizes the chemistry and toxicology of these remarkable secondary metabolites. 相似文献
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Various parameters,e.g. types of microtiter plate for DAS-ELISA (double antibody sandwich-enzyme-linked immunosorbent assay), use of fresh or frozen amplifier solutions for enzyme-amplified-ELISA, and use of sodium diethyldithiocarbamate (NaDIECA) in sample buffer in cocktail-ELISA were evaluated for the detection of potato viruses A, M, S, X, Y and leafroll from potato foliage. Dynatech Immulon immunoplates provided higher readings for all viruses. Fresh amplifier solution in amplifed-ELISA was superior to frozen solutions. Amplified ELISA gave only marginal improvement in the sensitivity over the standard DAS-ELISA. Addition of NaDIECA in sample buffer did not improve the detection of viruses in DAS-, amplified-, or cocktail-ELISA. Cocktail-ELISA can reduce antigen incubation time to as short as 15 min for PVA, PVM and PVX; 1 hr for PVY and PLRV; and 2–4 hr for PVS using pre-coated plates. Although amplified-ELISA is slightly more sensitive than DAS-ELISA for certain potato viruses, it is not suitable for large-scale indexing of potato viruses in Seed Certification Laboratories, in view of the additional steps needed in carrying out this procedure. 相似文献
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Kylie D. Swisher Venkatesan G. Sengoda Jacob Dixon Erik Echegaray Alexzandra F. Murphy Silvia I. Rondon Joseph E. Munyaneza James M. Crosslin 《American Journal of Potato Research》2013,90(6):570-577
‘Candidatus Liberibacter solanacearum’ (Lso) is a bacterium that infects solanaceous crops and causes plant decline and yield losses, especially in potato and tomato. Lso is transmitted to these hosts by the potato psyllid (Bactericera cockerelli Sulc) vector. B. cockerelli host plants are not limited to crop plants, but also include many wild, solanaceous weeds. These wild hosts could potentially impact overwintering and breeding of the psyllids and serve as reservoirs for Lso. In the Pacific Northwestern United States, B. cockerelli was recently reported to overwinter on bittersweet nightshade (Solanum dulcamara L.). The present study utilized high resolution melting analysis of the B. cockerelli mitochondrial cytochrome c oxidase I gene to assess the psyllid populations occurring on S. dulcamara during the summer and winter months in Washington, Oregon, and Idaho. This technique has previously been used to analyze the cytochrome c oxidase I gene of B. cockerelli, and has identified four psyllid haplotypes. Lso infection was also determined for the psyllids collected from S. dulcamara. During both the summer and the winter months in the Pacific Northwest, the Northwestern psyllid haplotype was the predominant population found living on S. dulcamara. However, low levels of the Western psyllid population were also present in Washington and Oregon during the same period. No overwintering psyllids tested were Lso-infected, suggesting that these populations do not pose an imminent threat of Lso transmission to newly emerging potatoes and other solanaceous crops in the region, unless a source of Lso becomes available. 相似文献
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Walid Medhioub Simon Ramondenc Audrey Sophie Vanhove Agnes Vergnes Estelle Masseret Veronique Savar Zouher Amzil Mohamed Laabir Jean Luc Rolland 《Marine drugs》2013,11(12):4799-4814
This study assessed the apoptotic process occurring in the hemocytes of the Pacific oyster, Crassostrea gigas, exposed to Alexandrium catenella, a paralytic shellfish toxins (PSTs) producer. Oysters were experimentally exposed during 48 h to the toxic algae. PSTs accumulation, the expression of 12 key apoptotic-related genes, as well as the variation of the number of hemocytes in apoptosis was measured at time intervals during the experiment. Results show a significant increase of the number of hemocytes in apoptosis after 29 h of exposure. Two pro-apoptotic genes (Bax and Bax-like) implicated in the mitochondrial pathway were significantly upregulated at 21 h followed by the overexpression of two caspase executor genes (caspase-3 and caspase-7) at 29 h, suggesting that the intrinsic pathway was activated. No modulation of the expression of genes implicated in the cell signaling Fas-Associated protein with Death Domain (FADD) and initiation-phase (caspase-2) was observed, suggesting that only the extrinsic pathway was not activated. Moreover, the clear time-dependent upregulation of five (Bcl2, BI-1, IAP1, IAP7B and Hsp70) inhibitors of apoptosis-related genes associated with the return to the initial number of hemocytes in apoptosis at 48 h of exposure suggests the involvement of strong regulatory mechanisms of apoptosis occurring in the hemocytes of the Pacific oyster. 相似文献
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Two new indole-diterpenoids (1 and 2) and a new isocoumarin (3), along with the known β-aflatrem (4), paspalinine (5), leporin B (6), α-cyclopiazonic acid (7), iso-α-cyclopiazonic acid (8), ditryptophenaline (9), aflatoxin B1 (10), 7-O-acetylkojic acid (11) and kojic acid (12), were isolated from the fermentation broth of the marine-derived fungus, Aspergillus flavus OUCMDZ-2205. The structures of Compounds 1–12 were elucidated by spectroscopic analyses, quantum ECD calculations and the chemical method. New Compound 1 exhibited antibacterial activity against Staphylococcus aureus with a MIC value of 20.5 μM. Both new Compounds 1 and 2 could arrest the A549 cell cycle in the S phase at a concentration of 10 μM. Compound 1 showed PKC-beta inhibition with an IC50 value of 15.6 μM. In addition, the absolute configurations of the known compounds, 4–6 and leporin A (6a), were also determined for the first time. 相似文献
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Endogenous gibberellins were measured in extracts of ‘Red Pontiac’ potato tubers sampled during tuber ontogeny. Stolons contained high levels of activity and developing tubers low activity, as indicated by elongation in the dwarf pea and maize mutant bioassays. However, dilution of the extracts of young tubers revealed that low gibberellin-like activity may have been due to the presence of an inhibitor. Based on co-chromatography this inhibitor was found not to be abscisic acid nor did abscisic acid induce tuber formation after treatment of the intact plant, treatment of the developing stolons or after addition to potato stolons grown in tissue culture medium. 相似文献
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Sea cucumbers produce numerous compounds with a wide range of chemical structural diversity. Among these, saponins are the most diverse and include sulfated, non-sulfated, acetylated and methylated congeners with different aglycone and sugar moieties. In this study, MALDI and ESI tandem mass spectrometry, in the positive ion mode, were used to elucidate the structure of new saponins extracted from the viscera of H. lessoni. Fragmentation of the aglycone provided structural information on the presence of the acetyl group. The presence of the O-acetyl group was confirmed by observing the mass transition of 60 u corresponding to the loss of a molecule of acetic acid. Ion fingerprints from the glycosidic cleavage provided information on the mass of the aglycone (core), and the sequence and type of monosaccharides that constitute the sugar moiety. The tandem mass spectra of the saponin precursor ions [M + Na]+ provided a wealth of detailed structural information on the glycosidic bond cleavages. As a result, and in conjunction with existing literature, we characterized the structure of five new acetylated saponins, Lessoniosides A–E, along with two non-acetylated saponins Lessoniosides F and G at m/z 1477.7, which are promising candidates for future drug development. The presented strategy allows a rapid, reliable and complete analysis of native saponins. 相似文献
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Jade d��Alpoim Guedes 《Rice》2011,4(3-4):104-113
Southwest China played a pivotal role in the spread of agriculture across East and Southeast Asia. Both rice and millet were important in the spread of populations and the expansion of agriculture into this region. Recent finds in the mountainous peripheries of Sichuan Province show that the earliest inhabitants of this region practiced a combination of broomcorn and foxtail millet agriculture (ca 4000?C2500 BC). These crops are adapted to high altitude and arid environments, which facilitated their movement across this region and eventually into the Tibetan Plateau. At around 2700 BC, a combined system of rice and foxtail millet agriculture appears suddenly in sites of the Baodun culture on the Chengdu Plain. The use of this double cropping system provided advantages to the inhabitants of this region in both risk reduction and yield. I argue that this had important consequences for spurring population growth, facilitating expansion into new territories and the development of social complexity. 相似文献
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Michael O. Eze A. Uzoechi Ogan 《Plant foods for human nutrition (Dordrecht, Netherlands)》1988,38(2):121-126
The sugar composition of the unfermented sap from oil palm (Elaeis guinensis) trees growing in the plantations of the Nigerian Institute for Oil Palm Research, Benin City, has been determined. While sucrose concentration ranges from 9.59 to 10.59% (w/v) in the pure unfermented sap, that of either glucose or fructose is much less than 1% (w/v) (0.13–0.73% w/v). Raffinose occurs in traces only (0.13–0.35 w/v). These results were derived from our improved methods which eliminate completely, or reduce to a bare minimum, fermentation of the sap during collection. The variation with time of storage of the individual sugars in the sap during fermentation to form palm wine reveals that, as sucrose steadily decreases, fructose reaches a peak at 1.51% (w/v) at the 9th hour, and thereafter declines, while glucose and raffinose remain continuously low; all sugars disappear beyond the 33rd hour. Concomittantly, pH decreases from pH 6.60 at zero time and stabilizes at pH 3.30 after 48 h, while titrable acidity increases continuously up until the 96th hour. These changes account for the variations in the quality of palm wine during storages. 相似文献
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