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1.
After fusion of somatic cells (isolated protoplasts) of Arabidopsis thaliana and Brassica campestris, plants could be regenerated in which genetic material from parents of taxonomically different tribes is combined. Between these regenerants asymmetric hybrids have also been obtained, in which one parental genome is represented by reduced chromosome numbers. Results concerning the analysis and genesis of these plants are used to discuss the question whether such monster plants are of any importance.  相似文献   

2.
Extended screening tests on the cercaricidal activity of various plants from northeast Brazil have shown that the extracts of the leaves and fruits ofPiper marginatum,Protium heptaphyllum, andCapsicum annuum show a remarkable effect on the cercaria ofSchistosoma mansoni. In the case of the oils ofPiper marginatum andCapsicum annuum, 90–96% of the cercaria ofSchistosoma mansoni were killed within 15 min. According to the NMR spectra, the active principles of the extracts seem to be water-soluble unsaturated compounds from the oils or their hydrolysis products. Natural substances provide an attractive alternative for preventive actions against schistosomiasis, as the perturbation of the ecological equilibrium of natural waters can be avoided in this manner.  相似文献   

3.
The electric organ of Torpedo, besides providing abundant amounts of cholinoceptive post-synaptic membrane for the isolation of the acetylcholine receptor protein, is a rich source of cholinergic nerve terminals. Using perfused, innervated tissue blocks from which synaptic vesicles in different functional states can be isolated, much information can be obtained about synaptic-vesicle dynamics. So far this is consistent with the view that the synaptic vesicles are the source of transmitter released on stimulation and that uptake of newly synthesized transmitter by the vesicles is dependent on their having discharged their previous charge of transmitter in at least one cycle of exo- and endocytosis. Studies of the protein composition of the vesicle membrane, especially when combined with similar information about the external presynaptic membrane, purified samples of which are now available from synaptosome (T-sac) preparations, promise to throw new light on the molecular mechanism underlying vesicle exo-/endocytosis.  相似文献   

4.
Disinfection by low-pressure monochromatic ultraviolet (UVC) radiation (253.7 nm) became an important technique to sanitize drinking water and also wastewater in tertiary treatments. In order to prevent the transmission of waterborne viral diseases, the analysis of the disinfection kinetics and the quantification of infectious viral pathogens and indicators are highly relevant and need to be addressed. The families Adenoviridae and Polyomaviridae comprise human and animal pathogenic viruses that have been also proposed as indicators of fecal contamination in water and as Microbial Source Tracking tools. While it has been previously suggested that dsDNA viruses may be highly resistant to UVC radiation compared to other viruses or bacteria, no information is available on the stability of polyomavirus toward UV irradiation. Here, the inactivation of dsDNA (HAdV2 and JCPyV) and ssRNA (MS2 bacteriophage) viruses was analyzed at increasing UVC fluences. A minor decay of 2-logs was achieved for both infectious JC polyomaviruses (JCPyV) and human adenoviruses 2 (HAdV2) exposed to a UVC fluence of 1,400 J/m2, while a decay of 4-log was observed for MS2 bacteriophages (ssRNA). The present study reveals the high UVC resistance of dsDNA viruses, and the UV fluences needed to efficiently inactivate JCPyV and HAdV2 are predicted. Furthermore, we show that in conjunction with appropriate mathematical models, qPCR data may be used to accurately estimate virus infectivity.  相似文献   

5.
The female silkmoth Bombyx mori L. emits a second pheromone component bombykal (E-10, Z-12-hexade-cadien-1-al) in addition to the well-known sexual attractant bombykol (E-10, Z-12-hexadecadien-1-ol). Bombykal stimulates its own specialized and highly sensitive olfactory cells of the male moth. Surprisingly, the aldehyde inhibits the release of the male's wing-fluttering response to bombykol.  相似文献   

6.
The staphylinid subfamily Micropeplinae includes small strongly sclerotized beetles with truncate elytra leaving the most part of abdomen exposed. Fossil micropeplines are rare and confined to Cenozoic representatives of extant genera. Here, we describe the oldest micropepline, Protopeplus cretaceus gen. and sp. n., from the Upper Cretaceous Burmese amber. Fluorescence microscope and confocal laser scanning microscopy (CLSM) were both used to reveal diagnostic features of Micropeplinae and some primitive traits that place Protopeplus very basally within Micropeplinae.  相似文献   

7.
Electrophysiologic, morphologic, and biochemical definitions of the synapse will be correlated spatially and temporally. Postsynaptic fatigue and facilitation follow oscillations of the free pool of acetylcholine, predicted by the kinetic theory and observed at the electric organ of Torpedo marmorata. The underlying thermodynamic instability exhibits properties of the Na+—K+-dependent hydrolysis of adenosine triphosphate and represents a necessary condition for synaptic memory.  相似文献   

8.
The relation between fatty acid accumulation, activity of acetyl-CoA carboxylase (ACC), and consequently lipid accumulation was studied in the microalgae Chlorella vulgaris co-immobilized with the plant growth-promoting bacterium Azospirillum brasilense under dark heterotrophic conditions with Na acetate as a carbon source. In C. vulgaris immobilized alone, cultivation experiments for 6 days showed that ACC activity is directly related to fatty acid accumulation, especially in the last 3 days. In co-immobilization experiments, A. brasilense exerted a significant positive effect over ACC activity, increased the quantity in all nine main fatty acids, increased total lipid accumulation in C. vulgaris, and mitigated negative effects of nonoptimal temperature for growth. No correlation between ACC activity and lipid accumulation in the cells was established for three different temperatures. This study demonstrated that the interaction between A. brasilense and C. vulgaris has a significant effect on fatty acid and lipid accumulation in the microalgae.  相似文献   

9.
All xenarthrans known to date are characterized by having permanent teeth that are both high crowned and open rooted, i.e., euhypsodont, and with a type of hypsodonty different from that of the rest of Placentalia: dentine hypsodonty. Also, most xenarthrans lack enamel; however, its presence has been reported in the fossil armadillo Utaetus buccatus and in living Dasypus. Considering the divergence of Xenarthra from other eutherians that possessed enameled teeth, the absence of enamel is a derived character. Diverse specializations are known in the dentition of xenarthrans, but the primitive pattern of their teeth and dentitions is still unknown. Here, we describe the mandible and teeth of a fossil armadillo, Astegotherium dichotomus (Astegotheriini, Dasypodidae), from the early Middle Eocene of Argentine Patagonia, with teeth showing both true enamel and closed roots. It is the oldest xenarthran with mandibular remains exhibiting protohypsodonty and is therefore likely representative of ancestral cingulates and xenarthrans generally. Astegotherium supports a recent hypothesis based on molecular data that enamel loss occurred independently not only within xenarthrans but also within dasypodid armadillos.  相似文献   

10.
Evolutionary history of tRNA is studied by comparative sequence analysis of two specified tRNA's at various phylogenetic levels and of tRNA families within four different species. Criteria are developed that allow 1) to distinguish between convergent and divergent evolution, 2) to determine the mechanism of divergence and 3) to estimate the degree of randomization of the variable parts of the sequences. The conclusion of these investigations is that tRNA's represent ancient molecules that existed in the form of a mutant distribution prior to their integration into genomes.  相似文献   

11.
12.
Infiltration and runoff from manured agricultural fields can result in livestock pathogens reaching groundwater and surface waters. Here, we measured the effectiveness of glass wool filters to simultaneously concentrate enteric viruses and bacteria of bovine origin from water. The recovery efficiencies were determined for bovine viral diarrhea virus types 1 and 2, bovine rotavirus group A, bovine coronavirus, poliovirus Sabin III, toxigenic Escherichia coli ,and Campylobacter jejuni seeded into water with three different turbidity levels (0.5, 215, and 447 NTU). Twenty liters of dechlorinated tap water (pH 7) were seeded with the test organisms, and then passed through a glass wool filter using a peristaltic pump (flow rate = 1 liter min?1). Retained organisms were eluted from the filters by passing beef extract-glycine buffer (pH 9.5) in the direction opposite of sample flow. Recovered organisms were enumerated by qPCR except for C. jejuni, which was quantified by culture. Mean recovery efficiencies ranged from 55 to 33 % for the bacteria and 58 to 16 % for the viruses. Using bootstrapping techniques combined with Analysis of Variance, recovery efficiencies were found to differ among the pathogen types tested at the two lowest turbidity levels; however, for a given pathogen type turbidity did not affect recovery except for C. jejuni. Glass wool filtration is a cost-effective method for concentrating several waterborne pathogens of bovine origin simultaneously, although recovery may be low for some specific taxa such as bovine viral diarrhea virus 1.  相似文献   

13.
The theory of self-reproductive molecular systems involves the consequence that translation must have started from a selected distribution of RNA molecules, that comprised GC-rich sequences of a length < 100 nucleotides. This implies a joint function of messenger and adaptor, which both had to be recruited from the same mutant distribution. The reconstruction of tRNA precursors yields such a molecule showing some reverberation of a codon pattern GNC. These findings suggest that tRNA has been the earliest component of the translation machinery.  相似文献   

14.
Lyophilization of the amber-colored, fluorescent oils obtained via thermolysis of amino acid mixtures (Lys, Ala, Gly) leads to a cellular-structured material—with an average cell diameter of 50 μm. The cellular aggregates show a resemblance to epithel tissues. Single cellular entities find their analogs in Fox microspheres as well as in the microfossilsIsuasphaera. Short-wave UV (254 nm) irradiation of the aqueous suspensions destroys the cells, whereas suspension in saline solutions (NaCl) offers protection against dissolution by UV light. The fluorescence spectrum of the microscopic preparations containing the highly fluorescent cellular material (“lumispheres”) was registered.  相似文献   

15.
Hepatitis A causes substantial morbidity in both industrialized and non-industrialized countries and represents an important health problem in several southern Mediterranean countries. The objectives of the study were as follows: (a) to assess the occurrence of hepatitis A virus (HAV) in Tunisia through the monitoring of urban wastewaters collected at wastewater treatment plants (WTPs); (b) to characterize environmental strains; and (c) to estimate the viral load in raw and treated sewages, in order to evaluate the potential impact on superficial waters receiving discharges. A total of 150 raw and treated wastewaters were collected from three WTPs and analyzed by both qualitative (RT-PCR/nested) and quantitative (qRT-PCR) methods. Of these, 100 (66 %) were found to be positive for HAV by the qualitative assay: 68.3 % in influents and 64.7 % in effluents. The vast majority of HAV sequences belonged to sub-genotype IA, with 11 different strains detected found to be identical to clinical strains isolated from Tunisian patients with acute hepatitis. Five unique variants were also detected, not previously reported in clinical cases. Only two IB strains were found, confirming the rarity of this sub-genotype in this country. The results of the present study indicate a wide circulation of the pathogen in the population, most probably in the form of asymptomatic infections, a finding consistent with the classification of the country as having intermediate/high endemicity. Quantitative data showed high viral loads in influents (3.5E+05 genome copies/liter, mean value) as well as effluents (2.5E+05 genome copies/liter, mean value), suggesting that contaminated water could be a critical element in transmission.  相似文献   

16.
Extensive mineral alteration in the older land surfaces of the eastern Amazonian lowland has led to complete impoverishment of the soils in respect of their inorganic nutrient contents. Large-scale use of this area for agricultural purposes seems impossible. In the western Amazonian lowland, younger land surfaces (Pliocene) have developed along with Pleistocene flood plains. The mineral alteration in the soil profiles of this area, which are partly characterized by poor drainage, has resulted in impoverishment of soils to a lesser degree. These soils can be used to a limited extent for agricultural purposes, especially at the level of a subsistence economy.  相似文献   

17.
This study provides guidelines for strategic management in industrial oil plants linked to uncertainties of climate change through the development of integrated planning methodology with focus on coastal flooding events caused by relative sea level rise (RSLR). The research site is in Redonda Island, located in Guanabara Bay, Rio de Janeiro City, Brazil, and since 1960, it constitutes an industrial oil plant facility. The region suffers interaction with storms and meteorological tides from extratropical cyclones over the South Atlantic Ocean, being vulnerable to risks of disasters, floods, and coastal erosion. A Program on Vulnerability and Adaptation Assessments to Relative Sea Level Rise (“Programa de Avaliação e Adaptação às Vulnerabilidades de Elevação do Nível Relativo do Mar—PAAVENRM”) was developed to avoid compromising the regional and local development in the industrial system of the island, which is an ad hoc instrument designed to anticipate and reduce risks, damages, and losses by occurrence of extreme climatic events in coastal areas prone to flooding caused by RSLR. Results from computer simulation modeling indicate 37 prospective qualitative scenarios that consolidate the conditions of future climate vulnerability of the plant, starting from United Nations Intergovernmental Panel on Climate Change (IPCC) information for RSLR up to 2100. Three quantitative forecasting scenarios were simulated, under boundary conditions preset for different altimetric ranges subject to submersion, based upon ordinary and extraordinary tides measured in the area in relation to RSLR, which allowed the evaluation of the industrial infrastructure at risk. Furthermore, three thematic maps were elaborated for the planning of specific coastal protection interventions. Percentages of physical damage and property losses were estimated. The importance of applying guidelines for medium and long-term corporate strategy management, integrating the risk of flooding, the rigging of civil defense systems, meteorology, and of the plans, programs, and existing systems and others to be developed is highlighted. From this perspective, the proposed scenarios help to identify the most relevant alternatives for mitigation and adaptation under technical criteria for decision making in the study area.  相似文献   

18.
Plant matter from a beech forest, leaves, and soil were extracted and analyzed by GC-MS technique. The amount of the extract varies with the CPI value. Characteristic compounds like phytadienes, plant alcohols, polycyclic aromatics, sterols, and triterpenes are observed in different samples at various concentrations. It seems there is a rapid change in the composition of extracts from recent plant material during early diagenesis based on reactions such as hydrolysis, dehydration, oxidation, and polymerization.  相似文献   

19.
Farmers in rural Africa use a number of adaptive strategies to cope with observed climatic changes and their impacts on agriculture. Most studies on adaptive capacity focus on socio-economic parameters (such as poverty or education), and few provide detailed analysis on the role played by different institutions at local level, and the effects of how these institutions are perceived on farmers’ adaptation. Semi-structured interviews were conducted among 46 households from seven villages in southern Benin (West Africa), and among representatives of several institutions at the local level. Half the participants were involved in Non Governmental Organizations (NGOs) development projects and half were independent farmers. Results indicate that independent farmers mostly use non-agricultural coping strategies (loans, work in town) while project farmers mainly use agricultural adaptive strategies (improved seed varieties). Lack of adaptive capacity of independent farmers is linked to weak State institutions at the local level. Due to their lack of efficiency and high corruption rates, local State representatives are mistrusted. NGOs are trusted and seek for help, even by independent farmers. Even if NGOs do not have climate change adaptation in their agendas, they promote activities, which help reduce farmers’ vulnerability. Although our results are limited to south-western Benin, they question the way adaptation is promoted today, for instance through the United Nations Framework Convention for Climate Change (through the National Adaptation Programmes of Action).  相似文献   

20.
Triboluminescence is the light emitted when mechanical energy is applied to a crystal. Many common substances such as sugar and copper sulfate are triboluminescent. The origin of the light and the mechanical, chemical, and crystallographic requirements of the phenomenon are described in this paper.  相似文献   

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