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The tropane alkaloid (TA) scopolamine is suggested to protect Brugmansia suaveolens (Solanaceae) against herbivorous insects. To test this prediction in a natural environment, scopolamine was induced by methyl jasmonate (MJ) in potted plants which were left 10?days in the field. MJ-treated plants increased their scopolamine concentration in leaves and herbivory decreased. These findings suggest a cause?Ceffect relationship. However, experiments in laboratory showed that scopolamine affect differently the performance of the specialist larvae of the ithomiine butterfly Placidina euryanassa (C. Felder & R. Felder) and the generalist fall armyworm Spodoptera frugiperda (J. E. Smith): the specialist that sequester this TA from B. suaveolens leaves was not negatively affected, but the generalist was. Therefore, scopolamine probably acts only against insects that are not adapted to TAs. Other compounds that are MJ elicited may also play a role in plant resistance against herbivory by generalist and specialist insects, and deserve future investigations. 相似文献
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MN Kaggwa N Straubinger-Gansberger M Schagerl 《African Journal of Aquatic Science》2018,43(2):123-129
Nine small artificial dams located in different climatic regions of Kenya were studied. The local communities use the stored water for various purposes, such as irrigation, domestic use, watering of livestock and cage fish farming. Such intense use is commonly accompanied by eutrophication, including fast growth of cyanobacteria, which at times produce cyanotoxins threatening human and animal life. We studied the pelagic community, analysed abiotic variables and identified microcystins by means of high performance liquid chromatography and ELISA kits at monthly intervals over a period of one year. Mass spectrometry (MALDI-TOF MS) was used to identify structural variants of microcystins by their protonated masses (M + H). Three dams contained microcystins, with the highly toxic Microcystin-LR being identified as the most prominent substance. Cell content of the toxin varied from 7.2 to 686.7 fg cell?1. Basic limnological variables that indicate the probability of toxin presence were also recorded. Non-parametric Mann–Whitney U-test revealed significant differences in soluble reactive phosphorous, nitrate-N, water depth, total hardness and post-Nauplii stages sampled between toxin-producing and non-toxin-producing dams. Although most of the samples did not contain high amounts of cyanobacteria, the cyanotoxin-problem was evident, suggesting the need for regular cyanotoxin monitoring programs. 相似文献
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Thirty five females and 15 males of New Zealand White mature rabbits about 6 months of age, were assigned to 1–5 dietary treatments (7 does+3 bucks for each): uncontaminated control diet, naturally aflatoxin contaminated diet without or with 1,2 and 3% bentonite. Rabbit fed with the aflatoxin-diet had a decreased (P<0.01 or 0.05) physical semen characteristics of bucks and a reproductive performance traits of does. The values of conception rate (%), gestation length (days), litter size (n) and litter weights (g) at birth and viability (%) of litters of doe rabbits, fed with the aflatoxin-diet, recorded, respectively: 64.5; 31.0; 4.4; 275.0 and 57.1 versus 85.6; 30.3; 7.9; 508.0; and 100 for those fed with the uncontaminated diet. Addition of bentonite to the aflatoxin contaminated diet improved in general the physical semen characteristics of buck and reproductive performance traits of doe rabbits. The results of the study demonstrate that adding 1% of Egyptian raw bentonite to the naturally aflatoxin contaminated rabbit diets can provide an effective, cheap and safe practical technique for preventing the aflatoxicosis in mature rabbits. 相似文献
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Matthieu Bensussan Valérie Lefebvre Alo?se Ducamp Jacques Trouverie Emilie Gineau Marie-No?lle Fortabat Alexia Guillebaux Aurélie Baldy Delphine Naquin Stéphane Herbette Catherine Lapierre Gregory Mouille Christine Horlow Mylène Durand-Tardif 《Plant physiology》2015,168(2):452-463
eskimo1-5 (esk1-5) is a dwarf Arabidopsis (Arabidopsis thaliana) mutant that has a constitutive drought syndrome and collapsed xylem vessels, along with low acetylation levels in xylan and mannan. ESK1 has xylan O-acetyltransferase activity in vitro. We used a suppressor strategy on esk1-5 to screen for variants with wild-type growth and low acetylation levels, a favorable combination for ethanol production. We found a recessive mutation in the KAKTUS (KAK) gene that suppressed dwarfism and the collapsed xylem character, the cause of decreased hydraulic conductivity in the esk1-5 mutant. Backcrosses between esk1-5 and two independent knockout kak mutants confirmed suppression of the esk1-5 effect. kak single mutants showed larger stem diameters than the wild type. The KAK promoter fused with a reporter gene showed activity in the vascular cambium, phloem, and primary xylem in the stem and hypocotyl. However, suppression of the collapsed xylem phenotype in esk1 kak double mutants was not associated with the recovery of cell wall O-acetylation or any major cell wall modifications. Therefore, our results indicate that, in addition to its described activity as a repressor of endoreduplication, KAK may play a role in vascular development. Furthermore, orthologous esk1 kak double mutants may hold promise for ethanol production in crop plants.Today, the fields of agriculture and forestry must address challenging issues, particularly in the context of fluctuating environmental conditions, such as ensuring that food and feed production remain efficient, meeting societal demands to reduce inputs, including water, and creating new products, such as biofuel. The demand for biofuel, a renewable alternative to fossil fuel, further increases the need to develop biomass amenable to alcohol fermentation. Second-generation biofuels are based on the fermentation of sugars extracted from lignocellulosic biomass, which is produced from the residues of food crops or from nonfood crops; therefore, its production does not compete with food crops (Sims et al., 2010). This lignocellulosic biomass is made up of secondary cell walls, mostly found in vascular tissues.Vascular tissues consist of a network of conduits, spanning an entire plant and connecting biosynthetically active leaves to the soil via the root and the shoot. There are two main vascular tissues, the xylem and the phloem, which arise from a lateral meristem called the procambium during primary growth. When dicot plants undergo secondary growth and cell walls are thickening, a secondary meristem, called the cambium or vascular cambium, emerges, giving rise to secondary vascular tissues (Esau, 1965; Buvat, 1989). The xylem is responsible for the upward transport of water and nutrients from the soil to the whole plant. The phloem, positioned parallel to the xylem, supplies sink organs (roots, etc.) with leaf photoassimilates. In angiosperms, such as Arabidopsis (Arabidopsis thaliana), the xylem is composed of two main cellular types, tracheary elements, involved in the transport of water, and fibers, playing a major role in plant support (Turner and Sieburth, 2003). The function of the xylem depends on the plant’s capacity to form thick secondary cell walls that confer mechanical strength to resist gravity and withstand negative pressure, allowing sap to travel upward through vessels. Xylem tissue is a major carbon sink that incorporates sugars into biopolymers (Ragni et al., 2011). Xylem secondary cell walls are mainly composed of cellulose embedded in a matrix of lignin and hemicelluloses. Xylan is a major hemicellulose in monocot and dicot secondary cell walls (Faik, 2010). Xylan has a linear backbone of β-(1,4)-linked d-Xyl residues that can be mono- or di-O-acetylated at positions O-2 and O-3 of the xylosyl residues (Ebringerova and Heinze, 2000).O-Acetylation of polysaccharides reportedly has a negative effect on the utilization of lignocellulose, such as in the production of paper and bioethanol (Biely, 1985; Grohmann et al., 1989). A major xylan acetyltransferase was recently identified in Arabidopsis: TRICHOME BIREFRINGENCE-LIKE29/ESKIMO1 (TBL29/ESK1; Urbanowicz et al., 2014). esk1 knockout mutants show a 60% reduction in xylan acetylation and a lesser reduction in mannan acetylation (Xiong et al., 2013; Yuan et al., 2013). esk1 has been described previously as a genotype with drought stress symptoms (Bouchabke-Coussa et al., 2008; Lugan et al., 2009); its collapsed xylem vessels (irregular xylem [irx] phenotype) are assumed to be the cause of the drastic hydraulic conductivity drop, and thus the drought stress syndrome, including dwarfism (Lefebvre et al., 2011).To identify new mutations that restore plant stature but maintain a low xylan O-acetylation level, we explored the possibility of producing this combination by screening an esk1-5 ethyl methanesulfonate (EMS)-mutagenized population for nondwarf phenotypes. The suppressors of esk1 were called beem, for biomass enhancement in esk1-5 mutation background. Here, we describe the identification of one BEEM gene as KAKTUS/UBIQUITIN PROTEIN LIGASE3 (KAK/UPL3), which encodes a protein belonging to the E3-ubiquitin protein ligase family (Downes et al., 2003). 相似文献
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Masanori?Nakaem-nakae@cc.kochi-u.ac.jp; KS fishssk@cc.kochi-u.ac.jp" title="MN m-nakae@cc.kochi-u.ac.jp; KS fishssk@cc.kochi-u.ac.jp" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Kunio?Sasaki 《Ichthyological Research》2004,51(4):327-336
Homologies of the adductor mandibulae muscles in eight families of Tetraodontiformes were hypothesized from the branching patterns of ramus mandibularis trigeminus. Insertions of the muscles to the upper or lower jaw were weak indicators of homology, migrations of the sites occurring frequently in A1, A2, A2, and A3. In monacanthids, tetraodontids, and diodontids, A1 tended to be split into numerous subsections, whereas in aracanids and ostraciids, A3 was highly developed, comprising three or four subsections. In tetraodontids, A2 was found to be a composite of A1 subsection and A2. The methods of and limits to applying nerve branching patterns to muscle homology are discussed. A new naming system that reflects both muscle homologies and insertions is proposed. 相似文献
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Postsynaptic density antigens: preparation and characterization of an antiserum against postsynaptic densities 总被引:6,自引:3,他引:3
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Long-term immunization of rabbits with postsynaptic densities (PSD) from bovine brain produced an antiserum specific for PSD as judged by binding to subcellular fractions and immunohistochemical location at the light and electron microscope levels. (a) The major antigens of bovine PSD preparations were three polypeptides of molecular weight 95,000 (PSD-95), 82,000 (PSD-82), and 72,000 (PSD-72), respectively. Antigen PSD-95, also present in mouse and rat PSDs was virtually absent from cytoplasm, myelin, mitochondria, and microsomes from rodent or bovine brain. Antigens PSD-82 and PSD-72 were present in all subcellular fractions from bovine brain, especially in mitochondria, but were almost absent from rodent brain. The antiserum also contained low-affinity antibodies against tubulin. (b)Immunohistochemical studies were performed in mouse and rat brain, where antigen PSD-95 accounted for 90 percent of the antiserum binding after adsorption with purified brain tubulin. At the light microscope level, antibody binding was observed only in those regions of the brain where synapses are known to be present. No reaction was observed in myelinated tracts, in the neuronal cytoplasm, or in nonneuronal cells. Strong reactivity was observed in the molecular layer of the dentate gyrus, stratum oriens and stratum radiatum of the hippocampus, and the molecular layer of the cerebellum. Experimental lesions, such as ablation of the rat entorhinal cortex or intraventricular injection of kainic acid, which led to a major loss of PSD in well- defined areas of the hippocampal formation, caused a correlative decrease in immunoreactivity in these areas. Abnormal patterns of immunohistochemical staining correlated with abnormal synaptic patterns in the cerebella of reeler and staggerer mouse mutants. (c) At the electron microscopic level, immunoreactivity was detectable only in PSD. The antibody did not bind to myelin, mitochondria or plasma membranes. (d) The results indicate that antigen PSD-95 is located predominantly or exclusively in PSD and can be used as a marker during subcellular fractionation. Other potential uses include the study of synaptogenesis, and the detection of changes in synapse number after experimental perturbations of the nervous system. 相似文献
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James A Mbah Moses N Ngemenya Ashime Louis Abawah Smith B Babiaka Lina N Nubed Kennedy D Nyongbela Njimoh Dieudonne Lemuh Simon MN Efange 《Annals of clinical microbiology and antimicrobials》2012,11(1):1-10