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1.
Among the Zulus of South Africa a crude root drug of initially unknown botanical origin was used for the treatment of pulmonary diseases and tuberculosis (TB). An English TB patient called “Stevens” heard about it and travelled to South Africa where, according to his account, he was cured by taking an extract of the crude drug. It was extremely difficult to establish the imported crude herbal drug as a “new TB medicine”, as neither the plant from which the drug originated was identified nor were the constituents and pharmacological effects known at that time.It was only after a professional search and initial chemical and taxonomic investigations enabled the identity of the plant to be determined that the requirements were met for comprehensive chemical, pharmacological and clinical research into the crude drug.The following report traces the long and difficult path of this “mystery drug” from the Zululand of South Africa to the laboratories of Europe.  相似文献   

2.
New plant-breeding techniques have been boosting plant breeding, since only a few years but already first promising products are pushing to the market. In contrast to this, in many countries, the current Directives regulating genetically modified organisms have been established more than 25 years ago, especially in the European Union being based on clear differentiation between transgenic plants and conventional breeding. Therefore, the question arises if these Directives are suitable to face the new challenge of genetic engineering or if there is a need for updated regulations.  相似文献   

3.
The EEC is an economic community which must endeavour to unify the regulation of trade and environment among its member states. The establishment of international regulatory standards in biotechnology will be relatively less hindered by entrenched national legislation and practices than in other industrial sectors. Rapid progress towards a common biotechnology market will benefit both manufacturers and research in Europe, and provide common standards of health and environmental protection.  相似文献   

4.
The mechanical sensitivity of vertebrate semicircular canals is directly influenced by the canal dimensions. Three key canal parameters, whose dimensions have been shown to be critical in determining the mechanical sensitivity of semicircular canals, are the streamline length, the cross-sectional area of the canal lumen and the plane area. These parameters were measured in ten specimens of adult T. europaea and compared with the dimensions of the same parameters in R. norvegicus. The major determinant of sensitivity, canal lumen area, is significantly larger in T. europaea.  相似文献   

5.
In the research of binocular vision J. E. Purkyn? pointed out the role of retinal corresponding areas. He observed binocular interaction of pressure phosphenes elicited in them and the fusion of images projected on the corresponding foveal areas even in eyes with artificial divergency. For the first time he proposed the examination of visual fields (perimetry) in several planes and he also introduced the colour perimetry. Purkyn? analyzed profoundly the different functions of direct (foveal) and indirect (peripheral) vision. In indirect vision he anticipated the modern concept of the useful field of view. Of fundamental importance was Purkyn?'s research of the strategy and different types of ocular movements. In analysis of motion perception, he evolved the hypothesis of "general sense of space" which is very close to modern feed-back conception of "corollary discharge".  相似文献   

6.
Saint Birgitta (Saint Bridget of Sweden) lived between 1303 and 1373 and was designated one of Europe''s six patron saints by the Pope in 1999. According to legend, the skulls of St. Birgitta and her daughter Katarina are maintained in a relic shrine in Vadstena abbey, mid Sweden. The origin of the two skulls was assessed first by analysis of mitochondrial DNA (mtDNA) to confirm a maternal relationship. The results of this analysis displayed several differences between the two individuals, thus supporting an interpretation of the two skulls not being individuals that are maternally related. Because the efficiency of PCR amplification and quantity of DNA suggested a different amount of degradation and possibly a very different age for each of the skulls, an orthogonal procedure, radiocarbon dating, was performed. The radiocarbon dating results suggest an age difference of at least 200 years and neither of the dating results coincides with the period St. Birgitta or her daughter Katarina lived. The relic, thought to originate from St. Birgitta, has an age corresponding to the 13th century (1215–1270 cal AD, 2σ confidence), which is older than expected. Thus, the two different analyses are consistent in questioning the authenticity of either of the human skulls maintained in the Vadstena relic shrine being that of St. Birgitta. Of course there are limitations when interpreting the data of any ancient biological materials and these must be considered for a final decision on the authenticity of the remains.  相似文献   

7.
Genetic parameters of body weight at 4 (W4 w), 8 (W8 w) and 22 (W22 w) weeks of age, days from 20 to 100 kg (DT), average backfat thickness at 100 kg (ABT), teat number (TEAT), number of good teats (GTEAT), total number of piglets born (TNB), born alive (NBA) and weaned (NW) per litter, and birth to weaning survival rate (SURV) were estimated in the Chinese × European Tiameslan composite line using restricted maximum likelihood methodology applied to a multiple trait animal model. Performance data from a total of 4 881 males and 4 799 females from 1 341 litters were analysed. Different models were fitted to the data in order to estimate the importance of maternal effects on production traits, as well as genetic correlations between male and female performance. The results showed the existence of significant maternal effects on W4w, W8w and ABT and of variance heterogeneity between sexes for W22w, DT, ABT and GTEAT. Genetic correlations between sexes were 0.79, 0.71 and 0.82, respectively, for W22w, DT and ABT and above 0.90 for the other traits. Heritability estimates were larger than (ABT and TEAT) or similar to (other traits) average literature values. Some genetic antagonism was evidenced between production traits, particularly W4w, W8w and ABT, and reproductive traits.  相似文献   

8.
This paper examines the US Atomic Energy Commission’s radioisotope distribution program, established in 1946, which employed the uranium piles built for the wartime bomb project to produce specific radioisotopes for use in scientific investigation and medical therapy. As soon as the program was announced, requests from researchers began pouring into the Commission’s office. During the first year of the program alone over 1000 radioisotope shipments were sent out. The numerous requests that came from scientists outside the United States, however, sparked a political debate about whether the Commission should or even could export radioisotopes. This controversy manifested the tension between the aims of the Marshall Plan and growing US national security concerns after World War II. Proponents of international circulation of radioisotopes emphasized the political and scientific value of collaborating with European scientists, especially biomedical researchers. In the end, radioisotopes were shipped from the Commission’s Oak Ridge facility to many laboratories in England and continental Europe, where they were used in biochemical research on animals, plants, and microbes. However, the issue of radioisotope export continued to draw political fire in the United States, even after the establishment of national atomic energy facilities elsewhere.  相似文献   

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10.
The macromorphology and epidermal anatomy of three Late Carboniferous-Early Permian pteridosperm species, conventionally assigned to the form-genus Pseudomariopteris Danzé-Corsin, are described from the Stephanian of the Blanzy-Montceau Basin (Central France). The generic diagnosis of Pseudomariopteris is emended, and P. busquetii is designated as the type species of the genus. The combination P. cordato-ovata (Weiss) Gillespie et al. is validated to replace the illegitimate name P. ribeyronii (Zeiller) Danzé-Corsin. The species diagnoses of P. busquetii and P. cordato-ovata are emended. On the basis of its epidermal anatomy, P. paleaui, another species orininally described from Central France, is transferred to the newly established genus Helenopteris Krings et Kerp, and the new combination Helenopteris paleaui is introduced. Lectotypes of P. busquetii and H. paleaui are selected. In addition, specimens from other basins are (re-)examined and illustrated. Seeds attached to a P. busquetii specimen suggest a callistophytalean relationship for Pseudomariopteris. Compression fossils and cuticles of Pseudomariopteris and Helenopteris are interpreted in terms of palaeoecology: Pseudomariopteris busquetii and P. cordato-ovata had climbing/scrambling growth habits; specialized climber hooks can be demonstrated for both species, either in compression or in cuticular preservation. Although the growth habit of H. paleaui is not yet entirely clear, the size of its fronds suggests that this taxon most probably was also a scrambler/climber. Finally, based on epidermal features, a tentative reconstruction of stages of the pinnule ontogeny of H. paleaui is provided.  相似文献   

11.
Telomerase activation. One step on the road to cancer?   总被引:15,自引:0,他引:15  
Ever since the discovery that telomeres are short in cancer cells and telomerase is activated in immortal cells, telomerase has been an oncogene wannabe. Oncogenes have been the glamour genes of molecular biology for 20 years, garnering flashy headlines and name recognition. More recently, tumor-suppressor genes have joined oncogenes on center stage. Recent evidence has shown that MYC upregulates the catalytic subunit of telomerase, TERT, and that TERT cooperates with HPV E7 in cell immortalization. This evidence now supports the placement of telomerase among the cancer gene elite.  相似文献   

12.
Mikhail E. Lobashev (1907–1971), Head of the Department of Genetics and Breeding with the Leningrad (now, St. Petersburg) State University from 1957 to 1971, had traveled a long way from a homeless to an Honored Scientist of the Russian Federation. Lobashev was among the discoverers of chemical mutagenesis in Drosophila; he pioneered in connecting the mutation process and the repair of genetic material and developed the concept of signal inheritance. Through the entire Great Patriotic War, he served with the field forces, and defended his doctoral dissertation on the physiological hypothesis of mutation process in 1946 on the return to the University. In 1948, Mikhail Efimovich was discharged from the University, where he was the Dean of the Biological Faculty, as a Morganist. On his return to the University in 1957, Lobashev devoted all his energies to the restoration of genetic education in this country, wrote the first domestic genetic textbook in the post-Lysenko period, organized the research at the Department of Genetics and Breeding, and created the scientific school, whose representatives are still successfully working in the field of genetics.  相似文献   

13.
van Breemen  N  Boyer  E.W.  Goodale  C.L.  Jaworski  N.A.  Paustian  K.  Seitzinger  S.P.  Lajtha  K.  Mayer  B.  van Dam  D.  Howarth  R.W.  Nadelhoffer  K.J.  Eve  M.  Billen  G. 《Biogeochemistry》2002,(1):267-293
To assess the fate of the large amounts of nitrogen (N) brought into the environment by human activities, we constructed N budgets for sixteen large watersheds (475 to 70,189 km2) in the northeastern U.S.A. These watersheds are mainly forested (48–87%), but vary widely with respect to land use and population density. We combined published data and empirical and process models to set up a complete N budget for these sixteen watersheds. Atmospheric deposition, fertilizer application, net feed and food inputs, biological fixation, river discharge, wood accumulation and export, changes in soil N, and denitrification losses in the landscape and in rivers were considered for the period 1988 to 1992. For the whole area, on average 3420 kg of N is imported annually per km2 of land. Atmospheric N deposition, N2 fixation by plants, and N imported in commercial products (fertilizers, food and feed) contributed to the input in roughly equal contributions. We quantified the fate of these inputs by independent estimates of storage and loss terms, except for denitrification from land, which was estimated from the difference between all inputs and all other storage and loss terms. Of the total storage and losses in the watersheds, about half of the N is lost in gaseous form (51%, largely by denitrification). Additional N is lost in riverine export (20%), in food exports (6%), and in wood exports (5%). Change in storage of N in the watersheds in soil organic matter (9%) and wood (9%) accounts for the remainder of the sinks. The presence of appreciable changes in total N storage on land, which we probably under-rather than overestimated, shows that the N budget is not in steady state, so that drainage and denitrification exports of N may well increase further in the future.  相似文献   

14.
Synthetic calcitonin injected into the lateral ventricles (ICV) of rats at picomolar concentration restores the “fasted” motility pattern of the small intestine in fed rats at doses as low as 0.083 picomoles. This effect which appeared in less than 5 min and persisted at least 2 hours for 0.83 picomole, was blocked by a previous intraventricular administration of 10 μg of calcium gluconate. At 0.83 picomole ICV, calcitonin also suppressed the disruption of the “fasted” pattern induced by intravenous infusion of Pentagastrin (6 μg·kg?1·h?1) but not that induced by insulin (0.5 U·kg?1). These findings support the hypothesis that calcitonin acts centrally to control the pattern of intestinal motility by inhibiting the digestive influences responsible for the “fed” pattern. All of these peripheral influences are mediated by a Ca++ sensitive central structure.  相似文献   

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17.
The importance of harmonizing the group of terms used to indicate ‘natural’ forests is reported in several studies. In a recent paper the term virgin forest is proposed as a unifying concept for forests which are not influenced by man in their development. In response to that paper my aim is to clarify the terms virgin and old-growth. My response focuses on two points: the term virgin forest is generally used to indicate forests that have not been influenced by people even in the distant past, therefore something different from what described by the authors; the definition drawn up for the proposed term substantially overlaps with the definition of old-growth forest resulting from a long history of studies on this theme. I think that the overlap between the two analyzed terms can ultimately only increase the existing confusion on this group of forest terms.  相似文献   

18.
To examine the relationship between freshwater entry and otolith annular structures, a total of 113 naturally recruited European eels Anguilla anguilla from Lithuania and Latvia that entered fresh water at least once were collected. In some individuals (8·3–11·3%), the first freshwater entry coincided with a dark check that was distinctly different from neighbouring annuli. In most individuals (81·7–84·9%), the first freshwater entry occurred on rings and increments indistinguishable from other annuli. For the remaining individuals (3·8–10%), the first freshwater entry did not correspond to any otolith ring, band or annulus. According to recent evidence, the observed high correspondence between the first freshwater entry and otolith annuli was more likely due to the movement into fresh water during winter when the annulus was deposited, rather than stress resulting from habitat change. Consequently, the age estimation based on otoliths might be less influenced by this habitat change during the yellow eel stage.  相似文献   

19.
Spatial and temporal dynamics of macroinvertebrate communities have usually been linked to several environmental and anthropic factors. The aim of this study is to elucidate how important are these factors in structuring macroinvertebrate communities from temperate regions. Regarding the macroinvertebrate number of taxa, the Habitat Template Model, the Dynamic Equilibrium Hypothesis and the Intermediate Disturbance Hypothesis will be tested in order to know how important the diversity of instream elements and the hydrological disturbance frequency are in defining the macroinvertebrate taxonomic richness. Thus, the structure and composition of macroinvertebrate communities were analysed in nine sites of the Pas River basin, a temperate Atlantic basin in northern Spain, during winter, spring, summer and autumn 2005, together with water physicochemical and environmental characteristics. Macroinvertebrate abundance increased downstream and during summer, probably favoured by lower hydraulic stress and water organic enrichment. As predicts the Habitat Template Model, the macroinvertebrate number of taxa was related to habitat heterogeneity. However, no clear relationship amongst macroinvertebrate richness and water quality was found. The macroinvertebrate taxonomic richness did not correspond exactly with the Dynamic Equilibrium Hypothesis and the Intermediate Disturbance Hypothesis because it was relatively high in the absence of hydrological disturbances (summer). Thus, disturbance events may play a secondary role in determining the seasonal dynamic of the number of taxa. However, hydrological disturbances can be considered the most important factors explaining the seasonal pattern of macroinvertebrate abundance. On the other hand, spatial patterns of macroinvertebrate community structure and composition were mainly determined by resource availability, hydraulic conditions, habitat heterogeneity and human alterations, whilst hydrological predictability and resource availability might play a major role in determining seasonal dynamics.  相似文献   

20.
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