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1.
Survey of seven strains determined as Septonema ochraceum (Dothideomycetes, inc. sed.) isolated from pine litter or obtained from public collections revealed three new species, Fusicladium cordae, F. sicilianum (Venturiaceae), Cladophialophora matsushimae (Herpotrichiellaceae) and a cryptic species morphologically identical to Devriesia americana (Teratosphaeriaceae), but phylogenetically distinct. Morphological survey and phylogenetic analysis using nucleotide sequence data from the nuclear ribosomal subunit genes indicate a close relationship within three species colonising pine litter needles, F. cordae, F. pini and F. ramoconidii. F. sicilianum is most related to F. rhodense. C. matsushimae represents a species belonging to one of the lineages of the polyphyletic genus Cladophialophora. None of the strains observed can be classified morphologically as S. ochraceum, of which the type material does not exist.  相似文献   

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Using molecular karyotyping and genetic hybridization analysis, two new polymeric β-fructosidase genes, SUC9 and SUC10, were identified in the yeast Saccharomyces cerevisiae, which are located on chromosome XIV and on the chromosome XVI/XIII doublet, respectively. The genes are responsible for fermentation of sucrose and raffinose. The SUC gene genotypes of strains VKM Y-1831 and DBVPG 1340 are SUC2 SUC9 and suc2 0 SUC10, respectively. suc2 0 is a silent sequence. The scientific and applied significance of SUC genes is discussed.  相似文献   

4.
Due to widespread polyembryony, Citrus rootstocks are usually propagated by open-pollinated seed germination, although micropropagation offers many advantages. Encapsulation technology has recently attracted the interest of researchers in the field of plant propagation because it combines the advantages of zygotic or gamic seeds with those of micropropagation. In this study, we examined the encapsulation of Carrizo citrange uninodal microcuttings (3–4 mm long) and evaluated the influence of the calcium alginate coating, a short time storage at cold temperature, and different sowing substrates on the viability and regrowth of the explants. A secondary aim was to develop an efficient protocol to induce root formation in the microcuttings. The results showed that encapsulation did not negatively affect the viability, providing a satisfactory regrowth, and storage potential for 30 days at low temperature. No differences in viability and regrowth were detected between the two different sowing substrates tested (agar-solidified medium and paper filter). To optimize the production of microcuttings required to perform the encapsulation experiments, in a preliminary experiment we assessed different factors affecting the in vitro shoot regeneration from epicotyl segments (obtained from seeds of Carrizo citrange germinated in vitro), including the influence of in vitro organogenesis, explant orientation, cut surface contact with the medium, treatments with different growth regulators, and distance of the organogenic explants from the cotyledonary node. The highest organogenic response was obtained from segments horizontally cultured (particularly from the basal portion), from segments with the cut surface in contact with the medium and from explants cultured on medium supplemented with 6-benzyladenine. No significant difference in regeneration efficiency was found in response to the distance of the epicotyl portions from the cotyledonary node.  相似文献   

5.
The hypothesis to be tested in this study is whether the introduction of the chloro group into diphenyl ditelluride molecule (p,p′-dichlorodiphenyl ditelluride, compound 1b) alters the antioxidant and scavenging activity of diphenyl ditelluride (compound 1a) in vitro. The results revealed that 1a and 1b had a potent antioxidant activity in vitro. However, the introduction of a functional group, chloro, into diphenyl ditelluride molecule (1b) did not cause great alterations in the antioxidant action of diphenyl ditelluride against lipid peroxidation, protein carbonyl, and scavenging of 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) and 2,2′-diphenyl-1-picrylhydrazyl radicals. Based on the in vitro results, different doses (0.25 and 0.75 μmol/kg) of 1a and 1b or vehicle (canola oil, 1 ml/kg) were administered to rats to investigate if the presence of chloro into diphenyl ditelluride molecule reduces its toxicity. The data demonstrate that the chloro group introduced into diphenyl ditelluride molecule did not alter the acute oral toxicity in rats. The administration of compound 1a in rats only altered the urea level, while compound 1b caused alterations in all toxicological parameters analyzed (alanine aminotransferase and aspartate aminotransferase activities, urea and creatinine levels) in plasma of rats. The results of the present investigation support similar antioxidant and scavenging activities of 1a and 1b in rat liver homogenate in vitro. Furthermore, the presence of chloro into diphenyl ditelluride molecule did not alter the mortality index but increased toxicity of diphenyl ditelluride in rats.  相似文献   

6.
The mechanism for the decarbonylation of (E)-2-butenal and (E)-2-methyl-3-pheny-2-propenal was studied with different levels of ab initio and DFT methods. Reactants, products and transition structures were optimized for two kinds of reaction channel: a one-step reaction which involves a three-membered cyclic transition state, and a two-step reaction which involves an initial four-membered cyclic transition state. According to our calculations, these two possible mechanisms entail similar energetic costs, and there are only small differences depending on the reactant. The elimination of (E)-2-methyl-3-pheny-2-propenal yields different products depending on the channel followed. Only one of the three possible one-step mechanisms leads directly to (E)-β-methylstyrene (the main product according to experiment). This fact is reasonably well reproduced by our results, since the corresponding transition state gave rise to the lowest activation Gibbs free energy.  相似文献   

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Differences in the timing of cell death, differentiation and function among three different types of ray parenchyma cells in the hardwood Populus sieboldii × P. grandidentata which form uniseriate and homocellular rays were examined and clarified. Ray parenchyma cells died within 5 years, and the disappearance of nuclei from ray parenchyma cells did not occur successively from the pith side, even within individual radial cell lines of a given ray. Cell death occurred earliest in contact cells, which were connected to adjacent vessel elements through pits, in the fourth annual ring from the cambium. Cell death occurred next in intermediate cells, which were located within the same cell lines as contact cells but were not adjacent to vessel elements, in the fourth annual ring from the cambium. Finally, isolation cells, which were located within the other cell lines of a given ray, died in the fifth annual ring from the cambium. Secondary wall thickenings in contact cells and intermediate cells were initiated before those in isolation cells in the current year’s xylem. Most starch grains were localized in intermediate cells, and there were more lipid droplets in contact cells and intermediate cells than in isolation cells. In addition, the largest quantities of protein were found in contact cells. Our results indicate that the position within a ray and neighboring short-lived vessel elements might affect the timing of cell death and differentiation and, thus, the function of long-lived ray parenchyma cells in Populus sieboldii × P. grandidentata.  相似文献   

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We investigated the relevance of the relationship between the compactness of β-galactosidase inclusion bodies (β-gal IBs) and their enhanced enzymatic activity with or without the addition of D-fucose (inducer analog) or methyl α-D-glucopyranoside (α-MG, catabolite repressor) after induction in the araBAD promoter system of Escherichia coli. Experiments conducted to evaluate the solubilization of β-gal IBs in guanidine hydrochloride as well as their trypsin degradation and temperature stability revealed that β-gal IBs expressed in response to the addition of D-fucose or α-MG had a looser structure. Additionally, β-gal IBs expressed when D-fucose or α-MG was added were more quickly solubilized in guanidine hydrochloride or degraded by trypsin-treatment than those produced when these compounds were not added. Moreover, the activity of β-gal IBs expressed when D-fucose or α-MG were added was less stable at various temperatures. Consequently, we deduced that the looser structure of β-gal IBs resulted in enhanced enzymatic activity of β-gal IBs upon addition of D-fucose or α-MG after induction.  相似文献   

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The character of inheritance of the morphological traits of spike and grain color and morphometric parameters of the grain in simple and backcross F1 and F2 hybrids of spelt and soft wheat has been investigated. The experiments confirmed that single homologous genes determine the trait of grain width in different species of wheat. Incomplete dominance of the gene that determines the trait of grain length has been revealed. The increase of the dosage of genes from one wheat species in a backcross hybrid has been shown to increase the deviation from the other species and to bring the values of the quantitative parameters of the grain closer to the values for the saturating species. Splitting of the spike color trait in the F2 offspring has been shown to follow the 15: 1 dihybrid cross scheme and to be controlled by two dominant homologous genes.  相似文献   

13.
A putative β-glucosidase gene from the genome of Bacillus halodurans C-125 was expressed in E. coli under the regulation of T7lac promoter. On induction with isopropyl-β-D-1-thiogalactopyranoside, the enzyme expressed at ∼40% of the cell protein producing 238 mg/liter culture. With increase in culture cell density to A 600 12 in auto-inducing M9NG medium, β-glucosidase production increased 3-fold. Approximately 70% of the expressed enzyme was in a soluble form, while the rest was in an insoluble fraction of the cell lysate. The soluble and active form of the expressed enzyme was purified by ammonium sulfate precipitation followed by ion-exchange chromatography to a purity >98%. The mass of the enzyme as determined by MALDI-TOF mass spectrometry was 51,601 Da, which is nearly the same as the calculated value. Phylogenetic analysis of the β-glucosidase of B. halodurans was found to cluster with members of the genus Bacillus. Temperature and pH optima of the enzyme were found to be 45°C and 8.0, respectively, under the assay conditions. K m and k cat against p-nitrophenyl-β-D-glucopyranoside were 4 mM and 0.75 sec−1, respectively. To our knowledge, this is the first report of high-level expression and characterization of a β-glucosidase from B. halodurans.  相似文献   

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The investigation into airborne fungal spore concentrations was conducted in Szczecin (Poland) between 2004 and 2009. The objective of the studies was to determine a seasonal variation in concentrations of amerospores on the basis of meteorological parameters. The presence of spores in Szczecin was recorded using a volumetric method. Fungal spores were present in the air in high numbers in late summer and early autumn. The highest concentrations were noted in September, October and November. The peak period was recorded in August, September, October and November. The highest annual number of spores occurred in 2005 and 2007 and the lowest in 2006. High values of daily concentration of amerospores occurred during the afternoon and late at night. In 2005 and 2007 the late-night maximum was overdue about 1 or 2 h. For daily values of dew point temperature and relative humidity, the coefficients were positive, significant for p = 0.001 and ranged from 0.342 to 0.258. The average wind speed was positively correlated for p = 0.01 and the coefficient was 0.291. The similar relations were noted for hourly values of spore concentrations for p = 0.05, p = 0.01 and p = 0.001. For these spore types, the dew point temperature and relative humidity appeared to be the most influential factor.  相似文献   

16.
Pineapple is one of the most important tropical fruits, but the availability of planting material is insufficient to agricultural demands. Therefore, several pineapple micropropagation protocols have been developed. However, acclimatization of in vitro plants continues to take a prolonged period. Biofertilizers have been found as safe alternatives to improve the agricultural performances of many crops. This study highlights some of the effects of the application of Azotobacter chroococcum (INIFAT5 strain) on in vitro pineapple plants during acclimatization. The bacteria were sprayed immediately after transplanting to the ex vitro environment; the plants were then sprayed every 4 wk. A control group of plants was established. Subsequently, after 5 mo, the evaluated variables included fresh and dry plant weight, plant height (cm), and root length (cm). The anatomy of middle-aged leaves and roots was also studied: transversal thickness and width of cuticle, epidermis, hypodermis, aquiferous parenchyma, and photosynthetic parenchyma. Thickness of root exoderm, external cortex, internal cortex, and stele were also evaluated. In general, the INIFAT5 strain improved the plant development. Results showed that the bacteria significantly provoked changes in the plant fresh weight, the thickness of the leaf abaxial and adaxial cuticles, and the root exoderm width. Contrastingly, A. chroococcum did not affect the thickness of the leaf photosynthetic parenchyma.  相似文献   

17.
Using extracellular recording of evoked potentials, we examined the effect of an agonist of β2 adrenoreceptors, metaproterenol (MPT), on GABA-ergic transmission in the CA1 zone of slices of the rat hippocampus. Isolated application of GABA evoked in these slices rapid reversible suppression of orthodromic population discharges recorded from the pyramidal layer of the above hippocampal zone after electrical stimulation of Schaffer collaterals in the radial layer. In most cases (13 of 19 preparations), combined application of GABA and MPT interfered with the development of the inhibitory GABA effect. In the case of the action of both of the above agents, the amplitude and duration of evoked responses decreased, but these changes were significantly weaker than those observed upon isolated GABA application. Our experiments showed that the noradrenergic system is capable of modulating GABA-ergic inhibition via β2 adrenoreceptors and, in such a way, is probably involved in regulation of the inhibition level in the hippocampus. Noradrenaline-induced effects on inhibitory neuronal networks in the hippocampus, similarly to those exerted by several other cerebral neurotransmitter systems, underlie the involvement of the noradrenergic cerebral system in a few physiological processes (emotions, attention, and memory) and are related to some pathological states (Alzheimer’s disease, schizophrenia, epilepsy, etc.).  相似文献   

18.
The paper studies the introgressive hybridization between the Gmelin’s larch and Cajander larch. The obtained data confirm the indisputable specific independence of the Cajander larch, which occupies about 48% of the total area of the larch forests in Russia. Its specific independence has been doubted by some experts. Once again more reliable and vast material shows the presence of wide transitional belt of hybrid populations at the juncture of the hybridizing species. Some forestry characteristics of the Gmelin’s larch and Cajanderi larch are studied that play important role in their natural restoration.  相似文献   

19.
Size-age structure and food composition of tube-nosed goby Proterorhinus marmoratus in the Rybinsk Reservoir have been studied. It was shown that food spectra changed in the process of dispersal of this species over the water body and considerably vary during the season. In the period of naturalization, feeding of the tube-nosed goby is characterized by group specialization; the object of specialization is Gmelinoides. Having dispersed over the water body and naturalized, it manifested itself as a generalist; its food composition became diverse and was determined by the seasonal dynamics of the population and biomass of food items.  相似文献   

20.
Thousands of behavioral mutants of Caenorhabditis elegans have been studied. I suggest a set of criteria by which some genes important in the evolution of behavior might be recognized, and identify neuropeptide signaling pathways as candidates.  相似文献   

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