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A short essay on anatomy, ultrastructure and larval development, life cycles, classification, palaeontology and phylogenetic relationships of Pentastomida is given. Currently, the Pentastomida are usually placed within Crustacea, as sister group of Branchiura (Crustacea, Maxillopoda). The grounds are striking similarities in ultrastructures of spermatozoa and congruence in the 18S rRNA nucleotide sequence. Both taxa are however sharply disparate in all other characters concerning morphology, embryology, life cycles and geological history. A direct introduction of Pentastomida in the system of Crustacea implies an unjustified inflation of the taxonomic diagnosis of the latter group; hence it is unacceptable. Two alternative hypotheses are suggested as tentative phylogenetic relationships to be tested. Each hypothesis infers however a very complex and unlikely evolutionary scenario. 1) Pentastomida and Branchiura are true sister groups as justified by coincidence in spermatozoan ultrastructure and sequence of ribosomal RNA. Since their divergence, the evolutions of pentastomids and branchiurans ran in different milieus, in different shapes and with different rates. To present time, the pentastomids lost nearly all characters of maxillopods and crustaceans as well as majority of anthropod features. 2) Pentastomida and Branchiura are not close related. The similarity in ultrastructural details of spermatozoa may be occasional or resulted from convergent evolution with unknown factors. Coincidence in nucleotide sequences or ribosomal RNA should be reexamined and tested with other pentastomid species. The second hypothesis seems to be more likely.  相似文献   

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The review of scientific periodicals relevant to research on the mycobacteria of the tuberculosis complex with the use of modern methods of molecular biology is presented. The main mechanisms of the intraspecific variability of mycobacteria and the updated view on the tuberculosis complex mycobacteria evolution are described.  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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Dawson A 《Bioethics》2004,18(6):515-530
This paper seeks to critically review a traditional objection to preventive medicine (which I call here the 'prevention problem'). The prevention problem is a concern about the supposedly inequitable distribution of benefits and risks of harm resulting from preventive medicine's focus on population-based interventions. This objection is potentially applicable to preventive vaccination programmes and could be used to argue that such programmes are unethical. I explore the structure of the prevention problem by focusing upon two different types of vaccination (therapeutic vaccination and preventive vaccination). I argue that the 'prevention problem' cannot be fairly applied to the case of preventive vaccination because such programmes do not just focus upon benefits at the level of populations (as is claimed by the prevention problem). Most such preventive vaccination programmes explicitly seek to create and maintain herd protection. I argue that herd protection is an important public good which is a benefit shared by all individuals in the relevant population. This fact can then be used to block the 'prevention problem' argument in relation to preventive vaccination programmes. I conclude by suggesting that whilst the future development and use of therapeutic vaccines does raise some interesting ethical issues, any ethical objections to prophylactic vaccination on the basis of the 'prevention problem' will not be overcome through the substitution of therapeutic vaccines for preventive vaccines; indeed, the 'prevention problem' fails on its own terms in relation to preventive vaccination programmes.  相似文献   

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Transgenic fishes are the object for the specialists in different research fields. It seems very promising to cultivate the rapidly growing objects resistant to diseases and negative environmental factors as well as the indicators of pollutions, models for oncological investigations etc. Some methodical, piscicultural, medical, ecological and others aspects of investigations of transgenic fishes as well as the legislative basis of Ukraine on this problem are discussed in the article.  相似文献   

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Collagens, which compose 1/3 of total proteins in the organism, have unique chemical structure and biological role. Current state of the investigation of these proteins biosynthesis and catabolism, role of shaperones, prolyl- and lysiloxydases, glycosyltransferases, metalloproteinases and other enzymes in collagens metabolism, as well as biological activities of collagens and their fragments have been considered in the review.  相似文献   

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