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Extracts from more than 325 different plants have been tested for their effects on larvae of Aedes aegypti, and from these initial tests, 16 plants were selected for further study. Extracts from plant parts of these 16 plants were screened using tlc and the results are tabulated along with the observed biological activity.
INTRODUCTION: A wide range of fungi and medicinal herbs, rich in hallucinogenic substances and widely used for mystic and medicinal purposes, can give rise to neurotoxic symptoms. DEVELOPMENT: We review the toxic syndromes that can arise from the ingestion of hallucinogenic fungi, cacti and plants, together with descriptions of cases of acute poisoning resulting from the use of medicinal herbs and from foodstuffs that are contaminated by mycotoxins. A series of different psychedelic fungi belonging to the Psilocybe, Panaeolus and Stropharia genera contain hallucinogenic alkaloids such as psilocybin. Some of the most notable plants displaying hallucinogenic and sedative properties are Papaver somniferum, Erytroxylum sp. and Cannabis sativa. Infusions of ayahuasca are obtained from the lianas and roots of different plants with psychoactive properties, such as Banisteriopsis caapi and Psychotria viridis, which contain alkaloids derived from tryptamine and from the beta carboline harmala. Peyote, a cactus rich in mescaline, and Claviceps purpurea (a fungus rich in LSD) are strong hallucinogens. We also examine ergotism and mycotoxicosis from Arthrinium sp. Poisoning from mycotoxin containing moulds on sugar cane can give rise to encephalopathy and late dystonia. Some of the more noteworthy medicinal plants for which neurological toxicity has been reported are Hypericum perforatum, kava kava (Piper methysticum), Aconitum sp. and Callilepis laureola. CONCLUSIONS: Because of the increasingly more widespread consumption of herbs and fungi and their potentially neurotoxic effects, in clinical practice there is a need to be aware of the neurological syndromes deriving from their use.
U3 small nucleolar RNA (snoRNA) is an abundant small RNA involved in the processing of pre-ribosomal RNA of eukaryotic cells. U3 snoRNA has been previously characterized from several sources, including human, rat, mouse, frog, fruit fly, dinoflagellates, slime mold, and yeast; in all these organisms, U3 snoRNA contains trimethylguanosine cap structure. In all instances where investigated, the trimethylguanosine-capped snRNAs including U3 snoRNA, are synthesized by RNA polymerase II. However, in higher plants, the U3 snoRNA is synthesized by RNA polymerase III and contains a cap structure different from trimethylguanosine (Kiss, T., and Solymosy, F. (1990) Nucleic Acids Res. 18, 1941-1949; Marshallsay, C., Kiss, T., and Filipowicz, W. (1990) Nucleic Acids Res. 18, 3451-3458; Kiss, T., Marshallsay, C., and Filipowicz, W. (1991) Cell 65, 517-526). In this study, we present evidence that cowpea and, most likely, tomato plant U3 snoRNA contains a methyl-pppA cap structure. These data show that the same U3 snoRNA contains different cap structures in different species and suggest that the kind of cap structure that an uridylic acid-rich small nuclear RNA contains is dependent on the RNA polymerase responsible for its synthesis. In vitro synthesized plant U3 snoRNA, with pppA or pppG as its 5' end, was converted to methyl-pppA/G cap structure in vitro when incubated with extracts prepared from wheat germ or HeLa cells. These data show that the capping machinery is conserved in organisms as evolutionarily distant as plants and mammals. Nucleotides 1-45 of tomato U3 snoRNA, which are capable of forming a stem-loop structure, are sufficient to direct the methyl cap formation in vitro.
In this study, we investigated the effect of plant microtubule-associated proteins (MAPs) on microtubule nucleation and growth in vitro. Since it has recently been demonstrated that plant nuclear surface acts as a microtubule-organizing center (MTOC), we tested the effects of plant MAPs using a nucleus-mediated microtubule nucleation assay. Nuclei were isolated from interphase tobacco BY-2 cells, and MAPs were isolated from tobacco BY-2 cells at different stages of the cell cycle. The effects of tobacco MAPs on microtubule nucleation at mammalian centrosomes were also analyzed. Under our experimental conditions, both interphase and mitotic tobacco MAPs promoted microtubule assembly around tobacco nuclei and at mammalian centrosomes below the critical tubulin concentration for spontaneous assembly. Interphase tobacco MAPs increase the mean length of nucleated microtubules in proportion to its molar ratio to tubulin. In contrast, mitotic tobacco MAPs do not induce nucleus- and centrosome-mediated nucleation of microtubules in a dose-dependent manner. Both MAP-fractions possessed microtubule bundling activity. The implications of these plant MAP properties on microtubule nucleation in living cells are discussed.
Nodulin genes are plant genes specifically activated during the formation of nitrogen-fixing nodules on leguminous plants. These genes are interesting to study since they are not only induced in a specific developmental fashion by signals coming directly or indirectly from the rhizobial symbiont, but are also expressed in a tissue-specific manner. By examining the expression of chimeric nodulin-reporter genes in transgenic legume plants it has been shown that nodule specific expression is mediated by DNA sequences present in the 5 upstream region of several nodulin genes. Here we summarize the available data on these cis-acting elements and the trans-acting factors interacting with them. We also review experiments designed to identify rhizobial "signals" which may play a role in nodule specific gene expression.
Rockwool, as an inert medium covered or bagged with polyethylene film, can be effectively used for plant culture in space station. The most important machine is the pump adjusting the dripping rate in the feeding system. Hydro-aeroponics may be adaptable to a space laboratory. The shortening of the light-dark cycles inhibits plant growth and induces an abnormal morphogenesis. A photoperiod of 12-hr-dark may be needed for plant growth.
This paper compares the medicinal and food floras of the native peoples of North America. There is a surprising overlap of these floras by both family and taxon. Yet there are also substantial differences-food and medicine tend to involve different plant parts, plant habit, and plant character. The similarities and differences are considered in an evolutionary context and a theoretical perspective is suggested to account for these facts.
Cellulysin, a crude cellulase from the plant parasitic fungus Trichoderma viride, induces the biosynthesis of volatiles in higher plants (Nicotiana plumbaginifolia, Phaseolus lunatus, and Zea mays) when applied to cut petioles by the transpiration stream. The pattern of the emitted volatiles largely resembles that from a herbivore damage or treatment of the plants with jasmonic acid (JA) indicating that cellulysin acts via activation of the octadecanoid signalling pathway. The treatment with cellulysin raises the level of endogenous JA after 30 min and is followed by a transient emission of ethylene after 2-3 h. Volatile production becomes significant after 12-24 h. Inhibitors of the JA pathway effectively block the cellulysin-dependent volatile biosynthesis.
Transposons are genetic elements that can move, and sometimes spread, within genomes, and that constitute an important fraction of eukaryote genomes. Two types of transposons, long terminal repeat (LTR)-retrotransposons and miniature inverted-repeat transposable elements (MITEs), are highly represented in plant genomes, and can account for as much as 50-80% of the total DNA content. In the last few years it has been shown that, in spite of their mutagenic capacity, both LTR-retrotransposons and MITEs can be found associated to genes, suggesting that their activity has influenced the evolution of plant genes. In this review we will summarise recent data on the control of the activity and the impact of both LTR-retrotransposons and MITEs on the evolution of plant genes and genomes.
The small subunit of ribulose-bisphosphate carboxylase (Rubisco), encoded by rbcS, is essential for photosynthesis in both C3 and C4 plants, even though the cell specificity of rbcS expression is different between C3 and C4 plants. The C3 rbcS is specifically expressed in mesophyll cells, while the C4 rbcS is expressed in bundle sheath cells, and not mesophyll cells. Two chimeric genes were constructed consisting of the structural gene encoding beta-glucuronidase (GUS) controlled by the two promoters from maize (C4) and rice (C3) rbcS genes. These constructs were introduced into a C4 plant, maize. Both chimeric genes were specifically expressed in photosynthetic organs, such as leaf blade, but not in non-photosynthetic organs. The expressions of the genes were also regulated by light. However, the rice promoter drove the GUS activity mainly in mesophyll cells and relatively low in bundle sheath cells, while the maize rbcS promoter induced the activity specifically in bundle sheath cells. These results suggest that the rice promoter contains some cis-acting elements responding in an organ-specific and light-inducible regulation manner in maize but does not contain element(s) for bundle sheath cell-specific expression, while the maize promoter does contain such element(s). Based on this result, we discuss the similarities and differences between the rice (C3) and maize (C4) rbcS promoter in terms of the evolution of the C4 photosynthetic gene.
The ubiA gene from E. coli codes for 4-hydroxybenzoate: polyprenyldiphosphate 3-polyprenyltransferase, an integral membrane protein involved in ubiquinone biosynthesis. This prokaryotic membrane protein was stably expressed in tobacco using Agrobacterium tumefaciens-mediated transformation. Transgenic lines containing a direct fusion of the ubiA structural gene to a 35S-derived promoter gave very low enzyme activity levels (average 0.16 pkat/mg). Inclusion of an N-terminal ER-specific signal peptide from a lectin gene from Phaseolus vulgaris resulted in an average activity of 1.08 pkat/mg in the transgenic tobacco lines. The additional inclusion of a C-terminal HDEL tetrapeptide, responsible for the retention of proteins in the endoplasmic reticulum of eukaryotic cells, increased the activity to 18.6 pkat/mg. When the promotor of this construct was changed from the 35S derivative to the recently described very strong plant promoter (ocs)3mas, the activity increased further to 128.6 pkat/mg. The most active tobacco line showed activities of the introduced enzyme which exceeded those of wild-type E. coli (the source of ubiA) by a factor of 1100. These results demonstrate the efficacy of plant ER-specific signal peptides for the active expression of a prokaryotic membrane protein in plants.
A ferredoxin-NADP+ oxidoreductase (FNR) cDNA from tobacco (Nicotiana tabacum cv. Samsun) was cloned and sequenced. Comparison of the deduced amino acid sequence revealed high identity to FNR proteins from Capsicum annuum, Pisum sativum, Spinacia oleracea and Vicia faba. Transgenic tobacco plants were generated that constitutively express the FNR cDNA in reverse orientation between the CaMV 35S promoter and the polyadenylation signal of the octopine synthase gene. Plants expressing the FNR antisense gene showed lower levels of FNR mRNA and protein accumulation, which was paralleled by a decrease in FNR activity. As a consequence, NADPH levels declined whereas NADP+ levels increased, leading to an unaltered NADP(H) pool. Growth rates, chlorophyll content and net CO2 uptake rates at high and low irradiances were strongly reduced in FNR antisense tobacco plants. These changes were accompanied by an over-reduced state of P700 as estimated by absorption changes at 820 nm. FNR control coefficients determined for the photosynthetic rate at saturating (C(R) = 0.94) and limiting (C(R) = 0.70) light conditions revealed a prominent role of this reductase in the regulation of photosynthesis.
The review focuses on recent evidence that two classes of cell-surface protein, one consisting largely of proteoglycans and the other of glycoproteins, may function during plant development. One class, the arabinogalactan proteins (AGPs), includes some of the extracellular proteoglycans in plant secretions, as well as related molecules that are found at the outer face of the plasma membrane where they present an array of complex carbohydrate structures to the extracellular matrix (cell wall). Recent evidence implicates cell-surface AGPs in the control of cell proliferation and morphogenesis. For example, immunodetection methods have shown that the developmentally regulated appearance of carbohydrate epitopes in these proteoglycans correlates with the formation of anatomical patterns. Likewise, the members of a second class, the hydroxyproline-rich glycoproteins (HRGPs, or extensins) of the cell wall, are developmentally regulated and their occurrence also correlates with changes in anatomy. Recent observations suggest that HRGP-like domains are present in plasma membrane proteins that bridge the wall and cytoskeleton. The roles of oxidative cross-linking and wall protein insolubilization during development and defense responses are also discussed, with particular reference to the roles of hydrogen peroxide, oxidases, and HRGPs in the processes. The survey emphasizes the value of monoclonal antibodies for revealing molecular and developmental changes in AGPs and HRGPs at the plant cell surface.
In plants, the role of mitogen-activated protein kinase (MAPK) in reactive oxygen species (ROS)-based signal transduction processes is elusive. Despite the fact that ROS can induce MAPK activation, no direct genetic evidence has linked ROS-induced MAPK activation with the hypersensitive response, a form of programmed cell death. In tobacco, the major ROS-induced MAPK is salicylate-induced protein kinase (SIPK). We found through gain-of-function and loss-of-function approaches that both overexpression and RNA interference-based suppression of SIPK render the plant sensitive to ROS stress. Transgenic lines overexpressing a nonphosphorylatable version of SIPK were not ROS sensitive. Analysis of the MAPK activation profiles in ROS-stressed transgenic and wild-type plants revealed a striking interplay between SIPK and another MAPK (wound-induced protein kinase [WIPK]) in the different kinotypes. During continuous ozone exposure, abnormally prolonged activation of SIPK was seen in the SIPK-overexpression genotype, without WIPK activation, whereas strong and stable activation of WIPK was observed in the SIPK-suppressed lines. Thus, one role of activated SIPK in tobacco cells upon ROS stimulation appears to be control of the inactivation of WIPK.
Sugar signalling cascades are important components of regulatory networks in cells. Compared with the situation in bacteria, yeast and animals, participants of the sugar signalling pathways in plants are poorly understood. Several genes involved in starch synthesis are known to be sugar inducible, although the signal transduction pathways remain undisclosed. We reported recently the isolation of SUSIBA2, a transcription factor involved in sugar-mediated regulation of starch synthesis. Here, we used antisense oligodeoxynucleotide (ODN) inhibition, a powerful approach in medical sciences, to block the effects of SUSIBA2 in sugar-treated barley leaves. The uptake and intracellular trafficking of an 18-mer susiba2 antisense ODN in leaves were followed by confocal microscopy. Administration of the antisense ODN to the leaves impeded susiba2 expression by RNase H activation. This dramatically diminished the ectopic expression of the iso1 and sbeIIb genes and resulted in altered starch synthesis. This study illustrates the successful exploitation of the antisense ODN technology in plant biology, e.g. as a rapid antecedent to time-consuming transgenic studies, and identifies SUSIBA2 as a transcriptional activator in plant sugar signalling. Based on our findings, we propose a model for sugar-signalling control of starch synthesis.
The production of safe pharmaceuticals at affordable costs is one of the great challenges of our times. Research has proven that transgenic plants can fulfill this need. This review focuses on the peculiar features of plant cells that allow high accumulation of recombinant proteins. The endomembrane system and the secretory pathway of plant cells in themselves offer a fascinating model of protein sorting, and in practical terms, represent the potential for the facile and very low-cost purification of recombinant pharmaceutical proteins.
We developed a quantitative method, analogous to those used in statistical mechanics, to predict how biodiversity will vary across environments, which plant species from a species pool will be found in which relative abundances in a given environment, and which plant traits determine community assembly. This provides a scaling from plant traits to ecological communities while bypassing the complications of population dynamics. Our method treats community development as a sorting process involving species that are ecologically equivalent except with respect to particular functional traits, which leads to a constrained random assembly of species; the relative abundance of each species adheres to a general exponential distribution as a function of its traits. Using data for eight functional traits of 30 herbaceous species and community-aggregated values of these traits in 12 sites along a 42-year chronosequence of secondary succession, we predicted 94% of the variance in the relative abundances.
Among the heat-shock proteins (HSPs) induced in response to heat-shock (HS) in all organisms, the low-molecular-mass (LMM) HSPs are the most abundant and unique in plants. The HSP genes at the transcriptional and the translational levels have been well-characterized; however, relatively little is known about the physiological function of HSPs. We have been studying the biological role of plant LMM HSPs based on the suggestion by Minton, Karmin, Hahn and Minton ([1982] Proc. Natl. Acad. Aci. U.S.A. 79, 7107-711) that HSPs may act as heat-stable proteins to non-specifically stabilize other proteins which are highly susceptible to inactivation or denaturation by heat. For the future, LMM-HSP gene transfer into organisms that do not synthesize plant LMM HSPs would be a way of determining the function of LMM HSPs, and success could be of practical importance.