Role of hydrogen peroxide and apoplastic peroxidase in tomato — Botrytis cinerea interaction

The aim of the research was to estimate the sensitivity of tomato tissue and spore from necrotrophic isolate of B. cinerea on H₂O₂. The influence of exogenic H₂O₂ and B. cinerea on plant tissue and on the activity of peroxidases (PO), catalase (CAT) and superoxide dismutase (SOD) in apoplastic tomato leaves fraction were investigated. It was proved that 40 mM H₂O₂ damaged the cells of a host, and inhibited in vitro germination of B.cinerea spores. Complete inhibition of germination was observed after the use 100 mM H₂O₂. In the presence of spores H₂O₂ was decomposed to H₂O and O₂. Trace activity of catalase was observed in a solution of spores used for inoculation. Necrosis which appeared on the leaves after 40 mM H₂O₂ treatment resembled hypersensitive response. On the leaves pretreated at this concentration the development of infection was observed. The H₂O₂ concentration harmful for the tissues, stimulated the PO activity measured with NADH — responsible for generation of ^·O ₂ ⁻ , as well as with syringaldazine (S) and ferulic acid (FA), substrates characteristics of forms lignifying and strengthening the cell wall. Clear increase in CAT activity, resulting from infection and early pretreatment with H₂O₂ was observed in apoplast. No effect on SOD activity was observed. A hypothesis may be put forward, that germinating spores produce enzymes which allow them to decompose H₂O₂ generated in apoplast, so there is little likelihood that B. cinerea can be directly inhibited by reactive oxygen forms (ROS) during initial stages of infection. Necrotic lesions resembling HR generated by exogenous H₂O₂ as well as induction of activity of apoplastic plant enzymes, particularly PO connected with strengthening and lignification of cell wall, were not sufficient factors to inhibit fungal expansion.     

Effect of salinity and different nitrogen sources on the activity of antioxidant enzymes and indole alkaloid content in Catharanthus roseus seedlings

The activities of antioxidant enzymes viz. glutathione reductase, GR; superoxide dismutase, SOD; peroxidase, POD; catalase, CAT and glutathione-S-transferase, GST and alkaloid accumulation were investigated in leaf pairs (apical, middle, basal) and in roots of Catharanthus roseus seedlings under the conditions of different nitrogen sources (20 mM KNO(3) and 2 mM NH(4)Cl) and salinity, in the absence (non-saline control) and in the presence of 100 mM NaCl in the nutrient solution. Salinity caused a reduction in plant biomass. The biomass production of ammonium-fed plants was lower than that of nitrate-fed plants. The antioxidant enzymes exhibited higher activity in saline-treated plants. Changes in antioxidant enzyme activity caused by different nitrogen sources differed in all leaf pairs, as well as in roots of C. roseus. Ammonium-fed plants showed higher CAT, GR and GST activity in leaf pairs as well as in roots, while POD and SOD activity were higher in nitrate-fed plants. Higher peroxidase activity concomitant with the increased accumulation of alkaloid was found in all leaf pairs, as well as in roots of C. roseus of NO(3)(-) fed plants as compared to NH(4)(+) fed plants.     

Richness and structure of plant communities in temporary pools from western Morocco: influence of human activities

Temporary pools are numerous in coastal plains of Atlantic Morocco and have a rich and diverse flora. These habitats are increasingly under pressure by man impact through grazing by domestic livestock and the development of annual crops in their catchments. The objectives of this work were to evaluate the species richness and the species composition of the vegetation of a sample of 30 pools in this region, in order to assess the structure of the vegetation within pools and to evaluate the role of environmental and anthropogenic factors in their richness and species composition. The results highlighted the species richness of the pools with 300 species found among which annual species were heavily dominant. The structure of the vegetation varied within pools according to a topographical/flooding gradient and between pools in relation with the land use in the surrounding areas. Three vegetation belts were recognized from the centre to the periphery of the pool. The total species richness per pool was not found significantly related to environmental or anthropogenic factors. The species characteristics of the pools were found mostly in the centre and their number affected by hydrological factors and land use in the pool and in the surrounding areas. The species characteristics of woodland habitats and of agriculture crops were found mostly in the peripheral zone. Temporary pools maintain specific communities of both aquatic and amphibious species, probably because of the selection induced by water level variations. The peripheral zone, although often dominated by terrestrial species, is clearly interpreted as part of the pool. It contains amphibious species highly characteristic of the pool for which the irregular flooding is a key environmental factor which decreases competition.     

蛹虫草研究进展

蛹虫草（Cordyceps militaris）作为一种药（食）用菌已经被广泛接受,在药理作用、有效成分、人工栽培等方面得到了广泛而深入的研究,具有重要开发价值。依据近年来的有关研究成果,就以上3个方面的研究进展状况展开论述,为蛹虫草进一步的研究与开发提供参考。     

Amino acids 15-28 in the ectodomain of SARS coronavirus 3a protein induces neutralizing antibodies

A synthetic peptide corresponding to amino acids (aa) 15-28 of the severe acute respiratory syndrome coronavirus (SARS-CoV) 3a protein was used to raise polyclonal antibodies in rabbits. This anti-3a N-terminal antibody could detect 3a protein in infected cells, as did an anti-3a C-terminal antibody previously described. The latter targeted the C-terminal cytoplasmic domain of 3a (aa 134-274). The anti-3a N-terminal antibody could detect intracellular 3a as well as 3a expressed on the cell surface. Interestingly, only the anti-3a N-terminal antibody can inhibit SARS-CoV propagation in Vero E6 culture although the binding affinity of the anti-3a N-terminal antibody was lower than the anti-3a C-terminal antibody.     

The current and future applications of microorganism in the bioremediation of cyanide contamination

Inorganic cyanide and nitrile compounds are distributed widely in the environment, chiefly as a result of anthropogenic activity but also through cyanide synthesis by a range of organisms including higher plants, fungi and bacteria. The major source of cyanide in soil and water is through the discharge of effluents containing a variety of inorganic cyanide and nitriles. Here the fate of cyanide compounds in soil and water is reviewed, identifying those factors that affect their persistence and which determine whether they are amenable to biological degradation. The exploitation of cyanides by a variety of taxa, as a mechanism to avoid predation or to inhibit competitors has led to the evolution in many organisms of enzymes that catalyse degradation of a range of cyanide compounds. Microorganisms expressing pathways involved in cyanide degradation are briefly reviewed and the current applications of bacteria and fungi in the biodegradation of cyanide contamination in the field are discussed. Finally, recent advances that offer an insight into the potential of microbial systems for the bioremediation of cyanide compounds under a range of environmental conditions are identified, and the future potential of these technologies for the treatment of cyanide pollution is discussed.     

Involvement of lignocellulolytic enzymes in the decomposition of leaf litter in a subtropical forest

The involvement of ligninolytic and cellulolytic enzymes, such as laccase, lignin peroxidase, manganese peroxidase, carboxymethylcellulase (CMCase), and filter paper activity (FPA), in the decomposition process of leaf litter driven by 6 soil-inhabiting fungi imperfecti was studied under solid-state fermentations. All the tested fungi exhibited varied production profiles of lignocellulolytic enzymes and each caused different losses in total organic matter (TOM) during decomposition. Based on the results, the 6 fungi could be divided into 2 functional groups: Group 1 includes Alternaria sp., Penicillium sp., Acremonium sp., and Trichoderma sp., and Group 2 includes Pestalotiopsis sp. and Aspergillus fumigatus. Group 1, with higher CMCase and FPA activities, showed a higher decomposition rate than the fungi of Group 2 over the first 16 d, and thereafter the cellulolytic activities and decomposition rate slowed down. Group 2 showed the maximum and significantly higher CMCase and FPA activities than those of the Group 1 fungi during the later days. This, combined with the much higher laccase activity, produced a synergistic reaction that led to a much faster average mass loss rate. These results suggest that the fungi of Group 1 are efficient decomposers of cellulose and that the fungi of Group 2 are efficient decomposers of lignocellulose. During cultivation, Pestalotiopsis sp. produced an appreciable amount of laccase activity (0.56+/-0.09 U/ml) without the addition of inducers and caused a loss in TOM of 38.2%+/-3.0%, suggesting that it has high potential to be a new efficient laccase-producing fungus.     

Isolation and characterization of a trypsin fraction from the pyloric ceca of chinook salmon (Oncorhynchus tshawytscha)

A trypsin fraction was isolated from the pyloric ceca of New Zealand farmed chinook salmon (Oncorhynchus tshawytscha) by ammonium sulfate fractionation, acetone precipitation and affinity chromatography. The chinook salmon enzyme hydrolyzed the trypsin-specific synthetic substrate benzoyl-dl-arginine-p-nitroanilide (dl-BAPNA), and was inhibited by the general serine protease inhibitor phenyl methyl sulfonyl fluoride (PMSF), and also by the specific trypsin inhibitors — soybean trypsin inhibitor (SBTI) and benzamidine. The enzyme was active over a broad pH range (from 7.5 to at least pH 10.0) at 25 °C and was stable from pH 4.0 to pH 10.0 when incubated at 20 °C, with a maximum at pH 8.0. The optimum temperature for the hydrolysis of dl-BAPNA by the chinook salmon enzyme was 60 °C, however, the enzyme was unstable at temperatures above 40 °C. The molecular mass of the chinook salmon trypsin was estimated as 28 kDa by SDS–PAGE.     

Recent ecophysiological,biochemical and evolutional insights into plant carnivory

BackgroundCarnivorous plants are an ecological group of approx. 810 vascular species which capture and digest animal prey, absorb prey-derived nutrients and utilize them to enhance their growth and development. Extant carnivorous plants have evolved in at least ten independent lineages, and their adaptive traits represent an example of structural and functional convergence. Plant carnivory is a result of complex adaptations to mostly nutrient-poor, wet and sunny habitats when the benefits of carnivory exceed the costs. With a boost in interest and extensive research in recent years, many aspects of these adaptations have been clarified (at least partly), but many remain unknown.ScopeWe provide some of the most recent insights into substantial ecophysiological, biochemical and evolutional particulars of plant carnivory from the functional viewpoint. We focus on those processes and traits in carnivorous plants associated with their ecological characterization, mineral nutrition, cost–benefit relationships, functioning of digestive enzymes and regulation of the hunting cycle in traps. We elucidate mechanisms by which uptake of prey-derived nutrients leads to stimulation of photosynthesis and root nutrient uptake.ConclusionsUtilization of prey-derived mineral (mainly N and P) and organic nutrients is highly beneficial for plants and increases the photosynthetic rate in leaves as a prerequisite for faster plant growth. Whole-genome and tandem gene duplications brought gene material for diversification into carnivorous functions and enabled recruitment of defence-related genes. Possible mechanisms for the evolution of digestive enzymes are summarized, and a comprehensive picture on the biochemistry and regulation of prey decomposition and prey-derived nutrient uptake is provided.     

Hormonal control of enzyme activity during the plasma membrane transformation of uterine epithelial cells

Ultrastructural and light microscopic catalytic histochemical methods were used to study the distribution and changes in distribution of four phosphatase enzymes; alkaline phosphatase, 5'-nucleotidase, thiamine pyrophosphatase and adenosine triphosphatase in uterine epithelial cells in response to the ovarian hormones, oestrogen, progesterone or a combination of both used in different regimes on ovariectomised rats. Reaction product for all four enzymes was clearly localised in the epithelial cells, especially with oestrogen priming. However, the four enzymes showed markedly different patterns of organisation of reaction product in response to other hormonal treatments.Our findings clearly show that the expression of these enzymes is under ovarian hormonal control. However, while all of the enzymes are upregulated by oestrogen, the response to progesterone is variable, which can upregulate or downregulate different enzymes. The findings are particularly obvious at the electron microscopic level on the apical plasma membrane of the uterine epithelial cells, which was the main focus of our study.