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Hantaviruses: molecular biology, evolution and pathogenesis   总被引:14,自引:0,他引:14  
Hantaviruses are tri-segmented negative sense single stranded RNA viruses that belong to the family Bunyaviridae. In nature, hantaviruses are exclusively maintained in the populations of their specific rodent hosts. In their natural host species, hantaviruses usually develop a persistent infection with prolonged virus shedding in excreta. Humans become infected by inhaling virus contaminated aerosol. Unlike asymptomatic infection in rodents, hantaviruses cause two acute febrile diseases in humans: hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The mortality rate varies from 0.1% to 40% depending on the virus involved. Hantaviruses are distributed world wide, with over 150,000 HFRS and HPS cases being registered annually. In this review we summarize current knowledge on hantavirus molecular biology, epidemiology, genetic diversity and co-evolution with rodent hosts. In addition, special attention was given in this review to describing clinical manifestation of HFRS and HPS, and advances in our current understanding of the host immune response, treatment, and prevention.  相似文献   

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The six known Costa Rican species of the campoplegine ichneumonid genus Cryptophion Viereck are described and keyed. The distribution of species throughout Costa Rica is detailed based on data gathered by an intensive Malaise trap survey of the ichneumonids of the country. Five new species are recognized: C. espinozai. C. guillermoi, C. manueli. C. moragai and C. tickelli , and a sixth, C. inaequalipes (Cresson) redescribed. The monophyly of the genus is demonstrated and the phylogeny of the Costa Rican species reconstructed. Host relationships have been established for all species in Costa Rica; they develop as koinobiont endoparasitoids of first to third instar larvae of Sphingidae or Saturniidae. Analysis of the host relationships from a phylogenetic perspective suggested that the genus first evolved using macroglossine sphingid larvae feeding on rubiaceous understorey plants as hosts, and subsequently diversified to utilize sphingine sphingids and ceratocampine saturniids feeding on a variety of food-plants. Most species appear to be monophagous and oligophagy is apparently a derived feature of one sister-species pair, C. espinozai and C. manueli . In Santa Rosa National Park, Costa Rica, only a small proportion of the species of Saturniidae and Sphingidae present are used as hosts by Cryptophion species. No one host species is parasitized by more than one Cryptophion species. No species of Cryptophion is known to parasitize more than one host species feeding on any one plant species. The monophagous species C. inaequalipes is only known to develop in its sphingid host when that host is feeding on one of its two alternative food-plants.  相似文献   

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A few more hypotheses for the evolution of dioecy in figs (Ficus, Moraceae)   总被引:1,自引:0,他引:1  
In figs ( Ficus , Moraceae) there are two breeding systems: monoecy is the ancestral condition but approximately half the 750 odd species are functionally dioecious. Three hypotheses have been proposed for the evolution of dioecy in figs, invoking seasonality (Kjellberg et al. 1987), the reduction of non-pollinating wasp species (Kerdelhue and Rasplus 1996), and the persistence of pollinator populations within small groups of trees (Kameyama et al. 1999). However, there are two major problems with these ideas. Firstly, dioecy has probably evolved only twice (Weiblen 2000), which severely limits our ability to test between alternative hypotheses. Secondly, it is very simple to suggest ways in which dioecy can evolve from monoecy (Charnov 1982). To illustrate this problem, and enlarge on some recent progress in our understanding of functionally dioecious figs, we are proposing a few more hypotheses.  相似文献   

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Bacteriophage research continues to break new ground in our understanding of the basic molecular mechanisms of gene action and biological structure. The abundance of bacteriophages in nature and the diversity of their genomes are two reasons why phage research brims with excitement. The pages of Virology Journal will reflect the excitement of the "New Phage Biology."  相似文献   

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The phytophagous insect fauna of ferns has often been described as depauperate, and some have pointed to the paucity of evidence for adaptive radiation of insect groups feeding specifically on ferns. This paper examines the world's species of fern‐specific Macrosiphum aphids and attempts to determine whether fern‐feeding is a monophyletically derived trait in Macrosiphum. All sixteen species reported to feed on ferns, including three new species, were included in a cladistic analysis, along with fifteen other Macrosiphum species selected to represent the diversity of the genus, Papulaphis sleesmani (Pepper), because of its similarity to fern‐feeding Macrosiphum, and Sitobion avenae (Fabricius), which was used as outgroup. The results gave good support for the monophyly of fifteen of the sixteen fern‐feeders, and also supported a clade consisting of these fifteen fern‐feeders plus Macrosiphum equiseti (Holman), an Equisetum‐specific aphid. One species, Macrosiphum lapponicum Shaposhnikov, from northern Russia, was concluded to be unrelated to other fern‐feeding Macrosiphum. Whether this species truly feeds on a fern requires confirmation. Taxonomic and biological notes are provided for all fern‐feeding Macrosiphum of the world. These include one new combination, Macrosiphum cyatheae (Holman) comb.n., and three new species: Macrosiphum longirostratum sp.n. on Woodsia mollis and Woodsia sp. from Mexico (Michoacán), Macrosiphum miho sp.n. on ‘Aspidium’ sp. from the U.S.A. (Illinois) and Macrosiphum rebecae sp.n. on Adiantum sp. from Mexico (Michoacán). Keys to apterous and alate viviparae of Macrosiphum living on ferns are given.  相似文献   

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Artabotrys comprises a species-poor early divergent grade (EDG) and a main species-rich clade (“main Artabotrys clade,” MAC). All members of the MAC exhibit a remarkably well-conserved floral Bauplan characterized by a tightly enclosed floral chamber with an elaborate rim between the inner petal blade and claw. Conversely, EDG resembles the sister genus Xylopia in lacking the inner petal rim, with one species (Artabotrys brachypetalus) bearing petals that lack the distinction between blade and claw altogether. The floral phenology and pollination ecology of two exemplar species—Artabotrys brachypetalus from the EDG and Artabotrys blumei from the MAC—are compared, including assessment of effective pollinators and their activity patterns, scent chemistry and thermogenesis. Our study revealed that Artabotrys blumei exhibits abbreviated anthesis (c. 27 hr), with a floral phenology and morphology that are clearly consistent with pollinator trapping, and may be pollinated by small beetles. Artabotrys brachypetalus has a typical anthetic duration (c. 45 hr), lacks a pollinator trapping mechanism, and is pollinated by honey bees and curculionid beetles. The “xylopioid” traits of the EDG are likely to be plesiomorphic, whereas the tightly enclosed floral chamber is likely to be apomorphic for the MAC and functionally significant in trapping pollinators.  相似文献   

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The announcement in 2004 that a small-brained hominin, Homo floresiensis, had been discovered on the island of Flores, Indonesia, was hailed as a major scientific breakthrough because it challenged preconceptions about the evolution of our closest relatives. Now, just over two years later, questions raised by the interpretation of the fossil abound. In a series of recent papers, critics have questioned the interpretation of the small brain volume of the fossil as that of a new hominin species, suggesting instead that it was due to microcephaly. The arguments raised by critics and advocates alike prompt a re-examination of ideas about what is possible during the evolution of the brain.  相似文献   

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A biological context for understanding human pathogens and parasites emanates from evolutionary studies among tapeworms of the genus Taenia. Human taeniasis and cysticercosis represent archaic associations and remain significant challenges for socioeconomic development, public health and food safety, and a continuing threat to animal production on a global basis.  相似文献   

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The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) has convened an expert working group which consisted of the authors of this paper and their respective committees, consulting groups and task forces. Two ICH guidances regarding genotoxicity testing have been issued: S2A, `Guidance on Specific Aspects of Regulatory Genotoxicity Tests' and S2B, `Genotoxicity: A Standard Battery for Genotoxicity Testing of Pharmaceuticals.' Together, these guidance documents now form the regulatory backbone for genotoxicity testing and assessment of pharmaceuticals in the European Union, Japan, and the USA. These guidances do not constitute a revolutionary new approach to genotoxicity testing and assessment, instead they are an evolution from preexisting regional guidelines, guidances and technical approaches. Both guidances describe a number of specific criteria as well as a general test philosophy in genotoxicity testing. Although these guidances were previously released within the participating regions in their respective regulatory communiqués, to ensure their wider distribution and better understanding, the texts of the guidances are reproduced here in their entirety (see Appendix A) and the background for the recommendations are described. The establishment of a standard battery for genotoxicity testing of pharmaceuticals was one of the most important issues of the harmonisation effort. This battery currently consists of: (i) a test for gene mutation in bacteria, (ii) an in vitro test with cytogenetic evaluation of chromosomal damage with mammalian cells or an in vitro mouse lymphoma tk assay, (iii) an in vivo test for chromosomal damage using rodent hematopoietic cells. A major change in testing philosophy is the acceptance of the interchangeability of testing for chromosomal aberrations in mammalian cells and the mouse lymphoma tk assay. This agreement was reached on the basis of the extensive review of databases and newly generated experimental data which are in part described in this publication. The authors are fully aware of the fact that some of the recommendations given in these ICH guidances are transient in nature and that the dynamic qualities and ongoing evolution of genetic toxicology makes necessary a continuous maintenance process that would serve to update the guidance as necessary.  相似文献   

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Plasmids of IncQ-family are distinguished by having a unique strand-displacement mechanism of replication that is capable of functioning in a wide variety of bacterial hosts. In addition, these plasmids are highly mobilizable and therefore very promiscuous. Common features of the replicons have been used to identify IncQ-family plasmids in DNA sequence databases and in this way several unstudied plasmids have been compared to more well-studied IncQ plasmids. We propose that IncQ plasmids can be divided into four subgroups based on a number of mutually supportive criteria. The most important of these are the amino acid sequences of their three essential replication proteins and the observation that the replicon of each subgroup has become fused to four different lineages of mobilization genes. This review of IncQ-family plasmid diversity has highlighted several events in the evolution of these plasmids and raised several questions for further research.  相似文献   

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The relationship between polyploidy and breeding system is of critical importance for understanding evolution and improving the taxonomy of large Rosaceous genera. Reviewing the data available for the family and for tribe Pyreae (formerly subfamily Maloideae) in particular, it appears that hybridization, pseudogamous gametophytic apomixis, polyploidy, and self-compatibility are closely linked. Studies of the evolutionary significance of any one or two of these factors need to consider the others as well. Taxonomic decisions likewise need to be informed by knowledge of how these factors affect patterns of phenetic and genetic variation.  相似文献   

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The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) has convened an expert working group which consisted of the authors of this paper and their respective committees, consulting groups and task forces. Two ICH guidances regarding genotoxicity testing have been issued: S2A, 'Guidance on Specific Aspects of Regulatory Genotoxicity Tests' and S2B, 'Genotoxicity: A Standard Battery for Genotoxicity Testing of Pharmaceuticals.' Together, these guidance documents now form the regulatory backbone for genotoxicity testing and assessment of pharmaceuticals in the European Union, Japan, and the USA. These guidances do not constitute a revolutionary new approach to genotoxicity testing and assessment, instead they are an evolution from preexisting regional guidelines, guidances and technical approaches. Both guidances describe a number of specific criteria as well as a general test philosophy in genotoxicity testing. Although these guidances were previously released within the participating regions in their respective regulatory communiqués, to ensure their wider distribution and better understanding, the texts of the guidances are reproduced here in their entirety (see Appendix A) and the background for the recommendations are described. The establishment of a standard battery for genotoxicity testing of pharmaceuticals was one of the most important issues of the harmonisation effort. This battery currently consists of: (i) a test for gene mutation in bacteria, (ii) an in vitro test with cytogenetic evaluation of chromosomal damage with mammalian cells or an in vitro mouse lymphoma tk assay, (iii) an in vivo test for chromosomal damage using rodent hematopoietic cells. A major change in testing philosophy is the acceptance of the interchangeability of testing for chromosomal aberrations in mammalian cells and the mouse lymphoma tk assay. This agreement was reached on the basis of the extensive review of databases and newly generated experimental data which are in part described in this publication. The authors are fully aware of the fact that some of the recommendations given in these ICH guidances are transient in nature and that the dynamic qualities and ongoing evolution of genetic toxicology makes necessary a continuous maintenance process that would serve to update the guidance as necessary.  相似文献   

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Musicality can be defined as a natural, spontaneously developing trait based on and constrained by biology and cognition. Music, by contrast, can be defined as a social and cultural construct based on that very musicality. One critical challenge is to delineate the constituent elements of musicality. What biological and cognitive mechanisms are essential for perceiving, appreciating and making music? Progress in understanding the evolution of music cognition depends upon adequate characterization of the constituent mechanisms of musicality and the extent to which they are present in non-human species. We argue for the importance of identifying these mechanisms and delineating their functions and developmental course, as well as suggesting effective means of studying them in human and non-human animals. It is virtually impossible to underpin the evolutionary role of musicality as a whole, but a multicomponent perspective on musicality that emphasizes its constituent capacities, development and neural cognitive specificity is an excellent starting point for a research programme aimed at illuminating the origins and evolution of musical behaviour as an autonomous trait.  相似文献   

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