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1.
Fusarium, graminearum KF 370 isolate is able to simultaneous biosynthesis of three toxic metabolites, namely: fusarenone-X (FUS), nivalenol (NIV) and zearalenone (F-2). After metabolites extraction with methanol — water (3:1) and defatting with n-heptane toxins were partitioned into chloroform layer. Purification of the? compounds was performed on Celite 545 — charcoal — Aluminiumoxid 90 column then metabolites were separated on Kieselgel 60 (200–300 mesh) column with developing solvent chloroform — methanol. This way FUS, NIV and F-2 were obtained as crystalline or high purity standards. 相似文献
2.
Object recognition and classification by sensory pathways is rooted in spike trains provided by sensory neurons. Nervous systems had to evolve mechanisms to extract information about relevant object properties, and to separate these from spurious features. In this review, problems caused by spike train variability and counterstrategies are exemplified for the processing of acoustic signals in orthopteran insects. Due to size limitations of their nervous system we expect to find solutions that are stripped to the computational basics. A key feature of auditory systems is temporal resolution, which is likely limited by spike train variability. Basic strategies to reduce such variability are to integrate over time, or to average across several neurons. The first strategy is constrained by its possible interference with temporal resolution. Grasshoppers do not seem to explore temporal integration much, in spite of the repetitive structure of their songs, which invites for multiple looks at the signal. The benefits of averaging across neurons depend on uncorrelated responses, a factor that may be crucial for the performance and evolution of small nervous systems. In spite of spike train variability the temporal information necessary for the recognition of conspecifics is preserved to a remarkable degree in the auditory pathway.Abbreviations dB decibel - CV coefficient of variation - SNR signal to noise ratio 相似文献
3.
Kevin Reinert Member HERA Editorial Board Larry Andrews Russell Keenan 《人类与生态风险评估》2006,12(5):811-818
Not a day passes where nanotechnology does not make headlines in the popular press, scientific journals, as well as in the regulatory arena. Environmental and public health activists are voicing a growing concern and focus on the risks potentially posed by nanotechnology and the ability of the government to regulate these new and exciting technologies. Whereas such concerns state the need for stringent, precautionary, and almost exclusionary approaches to the regulation of nanotechnology, many entities believe that a voluntary approach to these often novel materials and technologies is the appropriate and sensible path. In this editorial, we discuss the importance of nanotechnology, who cares, and the available options for approaching the regulation of this often novel technology. We focus on the U.S. Environmental Protection Agency (USEPA) and its voluntary regulatory data submission program as the preferred alternative. 2 相似文献
4.
Chemotactic properties of amino acids (L-alanine, glycine and L-lysine) and their oligopeptides (10–6M) and binding sites to these ligands were investigated in two unicellular models, the heterotrophicTetrahymena pyriformis and the auxotrophicDunaliella salina. Chemotaxis ofDunaliella induced by simple amino acids and their derivatives demonstrated that binding sites (receptors) for food molecules are not only present in the membrane but are also able to induce their basic physiological response. InTetrahymena, substances with special molecular structure and properties (polar, hydrophilic character of the signal peptide chain)-5-L-Lys, 5-Glywere required for chemoattraction, other peptides tested, lacking the required structure, were repellent. Divergences in chemotaxis and binding assays of both species suggest that trends of functional and binding parameters do not run parallel at this level of evolution. 相似文献
5.
Leonid K. Kudersky Juha Jurvelius Markku Kaukoranta Pekka Tuunainen Kyösti Mäkinen 《Hydrobiologia》1996,322(1-3):57-64
The post-war fishery of Lake Ladoga can be divided according to its catch level into four periods. In the years 1945–1954 the total annual catch increased, and reached the level of 4000 tonnes. In this period the fish stocks that had increased during the war years were intensively exploited. However, this fishery was not in balance with the stocks during the period 1955–1963. As a consequence, the catch decreased drastically, being sometimes less than 2000 tonnes.Controlling the fishery restored the abundance of whitefish Coregonus lavaretus (L.) and zander Stizostedion lucioperca (L.). This increased the total annual catch to about 5500 tonnes in 1964–1989. However, the fishery control measures have not been sufficient to achieve the conservation of salmon Salmo solar L. m. sebago, brown trout Salmo trutta L. and the migratory lake whitefish stocks.A decrease in the total fish catch has been observed since 1990. This decrease may be related to the deterioration of the environment of Lake Ladoga, caused by anthropogenic factors. The unfavourable state of the ecosystem has led to decline of the whitefish stocks and, especially during the last few years, to drastical decline of zander.Acute problems, to be faced in the near future, are connected with the hatchery maintenance of several river-spawning stocks, e.g. salmon, brown trout and migratory whitefish, because the existing fish hatcheries are insufficient in capacity and technically outdated. 相似文献
6.
The Society for Mathematical Biology (SMB) owns the Bulletin of Mathematical Biology (BMB). This is an international journal devoted to the interface of mathematics and biology. At the 2003 SMB annual meeting
in Dundee the Society asked the editor of the BMB to produce an analysis of impact factor, subject matter of papers, submission
rates etc. Other members of the society were interested in the handling times of articles and wanted comparisons with other
(appropriate) journals. In this article we present a brief history of the journal and report on how the journal impact factor
has grown substantially in the last few years. We also present an analysis of subject areas of published papers over the past
two years. We finally present data on times from receipt of paper to acceptance, acceptance to print (and to online publication)
and compare these data with some other journals.
This is an expanded version of a report published in the Society for Mathematical Biology Newsletter, Volume 16, Number 3, pp. 9–12, 2003.
These authors contributed equally. 相似文献
7.
Potatoes (Solanum tuberosum L., cv. Bintje) were grown in a naturally lit glasshouse. Laboratory measurements on leaves at three insertion levels showed a decline with leaf age in photosynthetic capacity and in stomatal conductance at near saturating irradiance. Conductance declined somewhat more with age than photosynthesis, resulting in a smaller internal CO2 concentration in older relative to younger leaves. Leaves with different insertion number behaved similarly. The changes in photosynthesis rate and in nitrogen content with leaf age were closely correlated. When PAR exceeded circa 100 W m–2 the rate of photosynthesis and stomatal conductance changed proportionally as indicated by a constant internal CO2 concentration. The photosynthesis-irradiance data were fitted to an asymptotic exponential model. The parameters of the model are AMAX, the rate of photosynthesis at infinite irradiance, and EFF, the slope at low light levels. AMAX declined strongly with leaf age, as did EFF, but to a smaller extent. During drought stress photosynthetic capacity declined directly with decreasing water potential (range –0.6 to –1.1 MPa). Initially, stomatal conductance declined faster than photosynthetic capacity.Abbreviations LNx
leaf number x, counted in acropetal direction
- DAP
days after planting
- DALA
days after leaf appearance
- Ci
CO2 concentration in the leaf
- Ca
CO2 concentration in ambient air
- LWP
leaf water potential
- OP
osmotic potential
- PAR
photosynthetically active radiation 相似文献
8.
J. P. Kahn 《The Western journal of medicine》1957,86(5):314-320
It is only through the love and approval of the significant adults in a child''s life that he is able to give up his primitive behavior for that which meets the demands of social living. Conflict over authority is only one of many conflicts. There are conflicts which arise inherently in a child''s development. The task of the parents in the education of the child in our society is to enable the child to tolerate a certain amount of frustration and also a necessary degree of control of impulses so that he can live in a group and in conformity with the required standards.Increased rebelliousness and defiance are normally characteristic of certain periods of development in healthy children. These are when concerted discipline begins, and in early adolescence. But other events also may reactivate or stimulate attitudes of defiance and rebellion. Even in his rebellion, a child needs and expects his parents to stand for order, as well as for love. He expects that the parent will save him from the consequences of his own destructive impulses, which he as yet may not have the strength to withstand.Deep-seated or submerged factors in the parents may play a significant role in the discipline to which they subject their children. True permissiveness means allowing a child to develop according to his own rate of speed and his own potentialities as a unique individual. It includes refusing the child any type of behavior that will bring danger to him or to others.A parent who uses harsh and rigid forms of discipline may force a child into submission, rather than acceptance and understanding. This produces only surface conformity which hides insecurity and violent underlying destructiveness. 相似文献
9.
《Endocrine practice》2011,17(2):271-280
ObjectiveTo compare how the rapid-acting insulin analogues (RAIAs) aspart, lispro, and glulisine perform in continuous subcutaneous insulin infusion (CSII) therapy regarding (1) pharmacokinetic properties, (2) chemical and physical stability, and (3) pump compatibility.MethodsPubMed was searched for articles pertaining to the use of RAIAs in CSII, without a restriction on the time period.ResultsThese RAIAs have pharmacokinetic profiles that more closely mimic endogenous insulin in comparison with regular human insulin and tend to produce less hypoglycemia. Among these RAIAs, the rates of absorption and clinical efficacy in terms of glycemic control were similar. Although glulisine showed a faster onset of action in some studies with aspart and lispro, this advantage lasted only for a maximum of 1 hour, after which results were similar for glulisine and aspart or lispro. Each RAIA is created by making minor amino acid substitutions to the regular human insulin molecule and adding a stabilizer to help prevent fibrillation. A series of chemical and covalent changes affecting the primary structure of an insulin preparation, however, may cause decomposition during storage, handling, and use, diminishing the potency of the insulin molecule while contained in an insulin pump. Precipitation, fibrillation, and occlusion may ensue, undermining compatibility for CSII pump use. Aspart has demonstrated the greatest chemical and physical stability in the insulin pump, with the lowest rates of overall occlusion in comparison with lispro and glulisine (aspart 9.2%, lispro 15.7%, and glulisine 40.9%; P < .01).ConclusionAspart is the most compatible of the 3 RAIAs for pump use. (Endocr Pract. 2011;17:271-280) 相似文献
10.
Hiroko Fujita Yaeko Igarashi Stefan Hotes Masayuki Takada Takashi Inoue Masami Kaneko 《Plant Ecology》2009,200(1):9-36
Hokkaido Island is located in the cool temperate zone, and its climate conditions facilitated the formation of a variety of
wetland types, the majority of them peat-forming mires. Most of these remained in a natural state until the early 20th century.
However, drainage and subsequent conversion mostly to agricultural land have since destroyed more than 70% of the original
wetland ecosystems. This paper (1) provides an overview of mire types, (2) reviews the development process of mires in Hokkaido
during the Holocene, (3) analyzes the causes of losses of wetland areas, and (4) gives a summary of the current conservation
and management status. Basic mire types that have been described in other parts of the northern hemisphere can also be recognized
in Hokkaido, although there are floristic differences, and the frequency and intensity of volcanic impact and tsunamis is
higher than in most other regions with abundant mire formation. Mire formation started at various points during the postglacial
period; a few mountain mires in southwest Hokkaido date back to the Lateglacial, but most mountain mires formed during the
mid to late Holocene. Most lowland mires developed at altitudes below 20 m and were influenced by the Jomon transgression
that peaked ca. 6,000 years BP. The largest lowland mires started forming after the sea retreated, and many are not older
than ca. 3,000 years. In 1996, the total number of wetlands (including peat-forming mires, freshwater marshes, and saltmarshes)
greater than 1 ha was 150, with a total area of 59,881 ha. In 1928, when many wetlands were yet undeveloped, their total area
was 200,642 ha. Most losses occurred between the 1950s and 1970s, when post-war development economics promoted agriculture
and large-scale reclamation projects. Currently, 90.7% of mountain wetlands are public land, while 81.3% of the lowland wetlands
are private or in mixed ownership. The ownership condition affects the possibilities for the protection of complete mire complexes
especially in the lowlands. For effective conservation of wetland ecosystems it is necessary to include the catchment area
in the planning of protected areas. 相似文献
11.
12.
Rainer Schmidt 《Mycotoxin Research》1986,2(1):39-43
A high pressure liquid chromatographic (HPLC) method is described for the isolation of trichothecenes formed on moldy rice. Extraction of the cultures was followed by purification and fractionation with a C18-Sep Pak cartridge. The polar fraction contained neosolaniol, 4,8-diacetoxy-12,13-epoxytrichothec-9-ene-3,15-diol (NT-1) and 4-acetoxy-12,13-epoxytrichothec-9ene-3,8,15-triol (NT-2), while in another fraction HT-2 toxin, T-2 toxin and acetyl-T-2 toxin were eluted. A high pressure liquid chromatograph equipped with a C18 μ Bondapak column and an R I-detector (differential refractometer) were used for the isolation procedure. 相似文献
13.
14.
73 adventive wild species occur in the flora of Israel: 39 are of tropical origin, 20 are North American. The geographical
distribution pattern suggests that about two thirds of the species reached Israel through neighbouring countries, while only
one third arrived directly from their countries of origin. — Three patterns of population dynamics can be recognized: accidental
species (7), colonizing species (30), and species penetrating into natural habitats (3). There is insufficient information
about the remaining species. — About 20 species are widespread noxious weeds which now have economic significance in Israel,
20 others are known to have similar ecological tendencies in other countries. These species soon may become aggressive weeds
in Israel. 相似文献
15.
16.
Matrix metalloproteinases (MMPs) are a family of extracellular proteases capable of degrading various proteinaceous components of the extracellular matrix(ECM).They have been implicated to play important roles in a number of developmental and pathological processes,such as tumor metastasis and inflammation.Relatively few studies have been carried out to investigate the function of MMPs during postembryonic organ-development.Using Xenopus laevis development as a model system,we demonstrate here that three MMPs,stromelysin-3(ST3),collagenases-3(Col3),and Col4,have distinct spatial and temporal expression profiles during metamorphosis as the tadpole transforms into a frog.In situ hybridizations reveal a tight,but distinct,association of individual MMPs with tissue remodeling in the tail and intestine during metamorphosis.In particular,ST3 expression is strongly correlated with apoptosis in both organs as demonstrated by analyses of serial sections with in situ hybridization for ST3 mRNA and TUNEL (terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end labeling)for apoptosis,respectively.On the other hand,Col3 and Col4 are present in regions where extensive connective tissue remodeling take place.These results indicate that ST3 is likely to play a role in ECM-remodeling that facilitate apoptotic tissue remodeling or resorption while Col3 and Col4 appear to participate in connective tissue degradation during development. 相似文献
17.
E. F. Annison R. E. Brown R. A. Leng D. B. Lindsay C. E. West 《The Biochemical journal》1967,104(1):135-147
1. Rates of entry and oxidation of a range of metabolites have been measured in tracheostomized sheep (diet, 800g. of lucerne chaff and 100g. of maize/day) by combining isotope-dilution techniques with the continuous measurement of total respiratory gas exchange, and 14CO2 production during the intravenous or intraruminal infusion of 14C-labelled substrates. 2. Mean entry rates in fed and starved (24hr.) sheep respectively, expressed as mg./min./kg. body wt.0·75, were: glucose, 5·0 (range 4·8–5·1, 2 observations) and 3·8 (3·2–4·2, 4); acetate, 10·8 (9·1–13·5, 4) and 5·8 (1); d(−)-β-hydroxybutyrate, 1·4 (1) and 1·5 (0·8–2·4, 4); palmitate, oleate and stearate (starved sheep only) 1·0 (0·6–1·9, 7), 0·9 (0·2–1·6, 10) and 0·9 (0·5–1·1, 11) respectively. 3. Production rates of propionate and butyrate in continuously feeding sheep were 6·4 (4·7–8·3, 4) and 4·3 (3·4–6·1, 4) mg./min./kg.0·75 respectively, and in starved (24hr.) sheep were 2·5 (2·2–2·9, 2) and 1·0 (0·8–1·2, 2) mg./min./kg.0·75 respectively. 4. Calculated terminal values for the specific radioactivity of respiratory 14CO2 during measurements of entry rates and production rates were used to calculate the contributions of individual substrates to overall oxidative metabolism. Mean values for fed and starved sheep respectively were: glucose, 9·1 (8·6–9·6, 2) and 11·2 (5·9–15·1, 4)%; acetate, 31·6 (26·8–38·1, 4) and 22·1 (1)%; d(−)-β-hydroxybutyrate, 10·4 (1) and 4·8 (1·9–7·7, 4)%; propionate, 23·0 (13·8–29·9, 4) and 7·1 (6·8–7·4, 2)%; butyrate, 16·5 (13·7–20·5, 4) and 5·3 (5·2–5·3, 2)%; palmitate, oleate and stearate (starved sheep only), 4·7 (2·0–7·7, 7), 4·0 (1·2–6·6, 10) and 4·4 (3·8–5·8, 9)% respectively. The sum of these values for individual substrates in fed and starved sheep, excluding that of β-hydroxybutyrate and after correction of the glucose value for the known interrelations of this substrate with propionate, accounted for 76% and 58% respectively of total production of carbon dioxide. 5. Calculations based on the proportion of substrate entry directly oxidized indicated that the substrates studied accounted for 63% (fed sheep) and 43% (starved sheep) of total energy expenditure measured by oxygen uptake. The contribution of β-hydroxybutyrate was excluded, and corrections were made for glucose–propionate interrelations, and for the different rates of oxidation of the methyl and carboxyl fragments of acetate. 6. The present results have been combined with those obtained earlier in this Laboratory to examine the relationships between rates of substrate entry and oxidation, and concentrations of substrate in blood. Rates of entry of acetate, glucose, d(−)-β-hydroxybutyrate, palmitate and oleate (but not stearate) were well correlated with concentration in blood, and substrate contribution to production of carbon dioxide showed a similar correlation to blood concentration, except with glucose. 7. It was concluded that the general technique is of potential value in providing valid quantitative parameters of animal metabolism. 相似文献
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19.
The present study aimed at identifying the fluoride-endemic areas in five different blocks in Agra district, Uttar Pradesh, India. A total of 365 groundwater samples from 73 villages were analyzed for establishing the concentration range of fluoride in drinking water. The fluoride level in the study area varied from 0.14 to 4.88 mg/L. Out of 73, the fluoride levels in 45 villages did not meet the permissible Word Health Organization standards. The Baroli Ahir block was found the highly fluoride-endemic area followed by Saiyan, Bichpuri, Achnera and Etmadpur. Chronic daily intake of fluoride in adults was 1.25 and 1.5 times higher than those in children and infants, respectively. The probability of dental fluorosis in infants was higher (42%) while adults were more prone to bone and skeletal fluorosis (60%). The hazard quotient analysis revealed that children were found to be at maximum risk followed by infants and adults. Sensitivity analysis revealed that the fluoride concentration is the major influencing parameter responsible for different types of fluorosis in various age groups. 相似文献
20.
Haojie Mao King H. Yang Albert I. King Kai Yang 《Biomechanics and modeling in mechanobiology》2010,9(6):763-772
The controlled cortical impact (CCI) model is widely used in many laboratories to study traumatic brain injury (TBI). Although
external impact parameters during CCI tests could be clearly defined, little is known about the internal tissue-level mechanical
responses of the rat brain. Furthermore, the external impact parameters tend to vary considerably among different labs making
the comparison of research findings difficult if not impossible. In this study, a design of computer experiments was performed
with typical external impact parameters commonly found in the literature. An anatomically detailed finite element (FE) rat
brain model was used to simulate the CCI experiments to correlate external mechanical parameters (impact depth, impact velocity,
impactor shape, impactor size, and craniotomy pattern) with rat brain internal responses, as predicted by the FE model. Systematic
analysis of the results revealed that impact depth was the leading factor affecting the predicted brain internal responses.
Interestingly, impactor shape ranked as the second most important factor, surpassing impactor diameter and velocity which
were commonly reported in the literature as indicators of injury severity along with impact depth. The differences in whole
brain response due to a unilateral or a bilateral craniotomy were small, but those of regional intracranial tissue stretches
were large. The interaction effects of any two external parameters were not significant. This study demonstrates the potential
of using numerical FE modeling to engineer better experimental TBI models in the future. 相似文献