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1.
Sallares R 《History and philosophy of the life sciences》2005,27(2):201-220
Problems concerning the concept of biocoenosis in ecology (the antecedent of the pathocoenosis concept) are discussed first of all. Six main problems are identified: the problem of emergent properties of ecological communities; the problem of ambiguity; the problem of heterogeneity; the boundary problem; the problem of retrospective differential diagnosis; and the problem of explaining change over time. The rest of the paper gives illustrations of these problems in relation to human pathogens drawn mainly from the interactions of malaria with other diseases, particularly but not exclusively in the Mediterranean world, from antiquity through to modern times. 相似文献
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Classical taxonomy and modern methodology 总被引:3,自引:3,他引:0
Classical rotifer taxonomy and recent approaches are reviewed. -taxonomy (morphology) remains the most widely-used technique, and most prone to subjective errors. Computer technology, and genetic or biochemical methods are not widely available in areas of most need — those with developing limnology programs. Strict adherence to the International Code of Zoological Nomenclature, uniform treatment of ecotypic variation and polymorphism, communication with and between systematists, and establishment of a centralized data base are among the points discussed. A standardized nomenclature is proposed. 相似文献
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Microbiology of ancient and modern hydrothermal systems 总被引:14,自引:0,他引:14
Hydrothermal systems have prevailed throughout geological history on earth, and ancient ARCHAEAN hydrothermal deposits could provide clues to understanding earth's earliest biosphere. Modern hydrothermal systems support a plethora of microorganisms and macroorganisms, and provide good comparisons for paleontological interpretation of ancient hydrothermal systems. However, all of the microfossils associated with ancient hydrothermal deposits reported to date are filamentous, and limited STABLE ISOTOPE analysis suggests that these microfossils were probably autotrophs. Therefore, the morphology and mode of carbon metabolism are attributes of microorganisms from modern hydrothermal systems that provide valuable information for interpreting the geological record using morphological and isotopic signatures. 相似文献
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Comparative studies of DNA in recent populations and characterisation of ancient hereditary material have contributed very interesting facts to our understanding of evolution of modern mankind. Analysis of DNA homology in related species, assessment of mutations and polymorphisms in various populations and new DNA sequence data from prehistoric finds allowed - via sophisticated DNA extraction techniques, PCR, sequencing and digitalised processing of genetic information - insights into possible roots of Homo sapiens and related species, migration patterns and ancient cultural habits, thus enrhing the palaeoanthropological discipline. However, a presentation of this development would not be complete without pointing towards the methodological limitations and manifold presentations burdened with artifacts, data misinterpretation and unjustified conclusions. Presently, this modern field of research is in its consolidation phase and new parameters for quality control and authentication are being implemented to avoid spectacular but unfounded reports. It is expected that most of the problems connected to old biomolecules may be closely related to fossilisation parameters. The future challenge will be the full understanding of the complex and multi-faceted processes underlying diagenesis, including the elucidation of nucleic acid postmortem damage". 相似文献
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Butein (2′,3,4,4′-tetrahydroxychalcone), a simple chalcone derivative, occurs in many unrelated genera including Butea Dahlia, Coreopsis and Searsia. It is a reputed food additive and a common ingredient of botanicals used in herbal medicine formulations, particularly in Asian countries. Although a simple polyphenol, this molecule exhibits a range of pharmacological properties, most notably acting as a potent protein tyrosine kinase inhibitor and as an antineoplastic agent. Researchers have convincingly demonstrated that butein inhibits the epidermal growth factor receptor in HepG2 cells and the tyrosine-specific protein kinase activities of the epidermal growth factor receptor. In addition, it also exhibits promising anti-inflammatory, antidiabetic, antinephritic, antithrombin, anti-angiogenic and hepatoprotective activities in various animal models. Although this molecule is endowed with an impressive list of biological properties, which have acted as scientific support for its commercialization, there are no review articles that coherently discuss various aspects of this chalcanoid. This review aims to explore the pharmacological relevance of butein, together with its structure–activity relationships and mechanisms of action. In addition, the occurrence, chemical synthesis and biosynthesis of butein are discussed. 相似文献
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Cereal mycorrhiza: an ancient symbiosis in modern agriculture 总被引:2,自引:0,他引:2
The majority of terrestrial plants live in association with symbiotic fungi that facilitate mineral nutrient uptake. The oldest and most prevalent of these associations are the arbuscular mycorrhizal (AM) symbioses that first evolved approximately 400 million years ago, coinciding with the appearance of the first land plants. Crop domestication, in comparison, is a relatively recent event, beginning approximately 10000 years ago. How has the dramatic change from wild to cultivated ecosystems impacted AM associations, and do these ancient symbioses potentially have a role in modern agriculture? Here, we review recent advances in AM research and the use of breeding approaches to generate new crop varieties that enhance the agronomic potential of AM associations. 相似文献
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The dearth of new antibiotics and escalating emergence of multidrug resistant bacteria have created a global healthcare crisis and highlight the drastic need for novel antimicrobial agents. Complementary and alternative strategies including the investigation of ancient medicinals could address this problem. Natural clay minerals with a long history of medicinal and biomedical applications have become an interest due to their broad-spectrum antimicrobial activity. Such untapped natural sources may provide new therapeutic agents in the battle against infectious diseases in the post-antibiotic era. 相似文献
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A polymorphic noncoding region of chloroplast DNA (cpDNA) was successfully amplified by the polymerase chain reaction (PCR) from various oak wood samples, including recent and more ancient (about 600-years-old) samples from different oak species. Adaptation of DNA isolation and amplification protocols was necessary to obtain this result. Polymorphisms useful to distinguish species or geographical origin of these samples could be scored through sequencing. These polymorphisms include one substitution and two microsatellite-type polymorphisms, due to a variable number of A/T repeats. Identical results were obtained independently in two separate laboratories. 相似文献
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The purpose of this study was to compare the frontal sinus size of ancient Greenlandic Inuit with ancient Inuit of Alaska
and Canada, and to compare sinus size between ancient and modern Greenlandic Inuit. Also, it was analyzed whether cranial
size was a determinant of frontal sinus size.
Frontal sinus size was evaluated in terms of absence frequency and planimetrically. Absence was defined as a frontal sinus
not exceeding a line drawn between the supraorbital rims.
A significant increase in absence frequency was noted from Alaska over Canada to Greenland (males: p<0.03; females p<0.0001).
This is in accordance with earlier studies, indicating that although these Inuit populations once have been commonly related
to the Old Bering Sea population, the Greenland Inuit represent an endpoint in an eastward migration. There was a significant
increase (p<0.0001) in frontal sinus size from ancient to modern Greenlandic Inuit, probably indicative of a high degree of
admixture with non-Inuit after modern colonization. The results regarding craniofacial size parameters and frontal sinus side
were inconclusive. No single craniofacial variable showed significant effect on frontal sinus size, but the area displayed
sexual dimorphism, females having smaller frontal sinuses. 相似文献
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R.J. Berry 《Journal of human evolution》1979,8(7):669-677
The relative value of morphometrics and non-metrical variant incidences for providing genetical information from skeletons are compared. It is concluded that non-metrical variant studies are the best method currently available for paleogenetical studies. The scientific background to non-metrical variant work is reviewed, and criticisms discussed. It is pointed out that a number of variants classified on the same skeleton screen a large number of loci, and some of these are likely to label adaptive chromosome segments, i.e. studies of non-metrical variants are capable of giving information about population dynamics as well as population differentiation. 相似文献
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Keyser-Tracqui C Crubézy E Pamzsav H Varga T Ludes B 《American journal of physical anthropology》2006,131(2):272-281
In the present study, nuclear (autosomal and Y-chromosome short tandem repeats) and mitochondrial (hypervariable region I) ancient DNA data previously obtained from a 2,300-year-old Xiongnu population of the Egyin Gol Valley (south of Lake Baikal in northern Mongolia) (Keyser-Tracqui et al. 2003 Am. J. Hum. Genet. 73:247-260) were compared with data from two contemporary Mongolian populations: one from the same location (Egyin Gol Valley plus a perimeter of less than 100 km around the valley), and one from the whole of Mongolia. The principal objective of this comparative analysis was to assess the likelihood that genetic continuity exists between ancient and present-day Mongolian populations. Since the ancient Xiongnu sample might have been composed of some of the ancestors of the present-day Yakuts, data from a present-day Yakut population, as well as published data from Turkish populations, were also included in the comparative analysis. The main result of our study was the genetic similarity observed among Mongolian samples from different periods and geographic areas. This result supports the hypothesis that the succession over time of different Turkic and Mongolian tribes in the current territory of Mongolia resulted in cultural rather than genetic exchanges. Furthermore, it appears that the Yakuts probably did not find their origin among the Xiongnu tribes, as we previously hypothesized. 相似文献
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Genome-wide data, both from SNP arrays and from complete genome sequencing, are becoming increasingly abundant and are now even available from extinct hominins. These data are providing new insights into population history; in particular, when combined with model-based analytical approaches, genome-wide data allow direct testing of hypotheses about population history. For example, genome-wide data from both contemporary populations and extinct hominins strongly support a single dispersal of modern humans from Africa, followed by two archaic admixture events: one with Neanderthals somewhere outside Africa and a second with Denisovans that (so far) has only been detected in New Guinea. These new developments promise to reveal new stories about human population history, without having to resort to storytelling. 相似文献
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Tanya Das Gaurisankar Sa Baisakhi Saha Kaushik Das 《Molecular and cellular biochemistry》2010,336(1-2):85-95
Although safe in most cases, ancient treatments are ignored because neither their active components nor their molecular targets are well defined. This is not the case, however, with curcumin, a yellow-pigment substance and component of turmeric (Curcuma longa), which was identified more than a century ago. Recently, extensive research has addressed the chemotherapeutic potential of this relatively nontoxic-plant-derived polyphenol. Because most cancers are caused by deregulation of as many as 500 different genes, agents that target multiple gene products are needed for prevention and treatment of cancer. In this regard, curcumin has been reported to have immense potentiality for being used in cancer chemotherapy because of its control over the machineries of cell survival, proliferation, invasion, and angiogenesis. The mechanisms implicated are diverse and appear to involve a combination of cell signaling pathways at multiple levels. This review seeks to summarize the unique multifocal signal modulatory properties of the “ancient weapon,” curcumin, which may be exploited for successful clinical cancer prevention. 相似文献