Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
1.
Mol Phylogenet Evol ; 58(2): 271-82, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21044888

RESUMO

We present a molecular phylogeny of bullfinches (Pyrrhula Brisson, 1760) based on 2357bp DNA sequence information of mitochondrial genes (cyt-b, 16S rRNA) and nuclear introns (fib-7, GAPDH-11). The genus is clearly a monophyletic group. Within the limits of Pyrrhula, molecular methods support the subdivision of three main groups: (1) "Southeast-Asian bullfinches" (P. nipalensis and P. leucogenis), (2) "Himalayan bullfinches" (P. aurantiaca, P. erythaca, P. erythrocephala), and (3) "Eurasian bullfinches" (P. pyrrhula s.l.). Within the last group there are four different subgroups: (3a) P. (p.) murina, (3b) P. (p.) cineracea, (3c) P. (p.) griseiventris, and (3d) P. pyrrhula s.str. The centre of origin of the genus Pyrrhula was most probably Southeast Asia. Incomplete lineage sorting of both mitochondrial and nuclear genes is observed among two apparently good species (P. erythaca and P. erythrocephala) indicating a very recent speciation event within the Himalayan Mountain chain. According to our estimates, the Pyrrhula ancestors split from the Pinicola ancestors before the Pleistocene. Apart from the subsequent Pre-Pleistocene splits of the three ancestral main groups, most of the diversification of today's representatives probably took place during the past 600,000 years, possibly in interaction with Pleistocene refugia and successive colonization movements after the last glaciation. Thus our work confirms the traditional delimitation of the bullfinches towards the other members of the finch family Fringillidae and corroborates most of the classic intra-generic subdivisions.


Assuntos
Evolução Molecular , Tentilhões/genética , Filogenia , Animais , Ásia , Núcleo Celular/genética , DNA Mitocondrial/genética , Europa (Continente) , Tentilhões/classificação , Variação Genética , Íntrons/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
2.
J Cell Biol ; 115(6): 1535-45, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1757462

RESUMO

The effect of receptor occupancy on insulin receptor endocytosis was examined in CHO cells expressing normal human insulin receptors (CHO/IR), autophosphorylation- and internalization-deficient receptors (CHO/IRA1018), and receptors which undergo autophosphorylation but lack a sequence required for internalization (CHO/IR delta 960). The rate of [125I]insulin internalization in CHO/IR cells at 37 degrees C was rapid at physiological concentrations, but decreased markedly in the presence of increasing unlabeled insulin (ED50 = 1-3 nM insulin, or 75,000 occupied receptors/cell). In contrast, [125I]insulin internalization by CHO/IRA1018 and CHO/IR delta 960 cells was slow and was not inhibited by unlabeled insulin. At saturating insulin concentrations, the rate of internalization by wild-type and mutant receptors was similar. Moreover, depletion of intracellular potassium, which has been shown to disrupt coated pit formation, inhibited the rapid internalization of [125I]insulin at physiological insulin concentrations by CHO/IR cells, but had little or no effect on [125I]insulin uptake by CHO/IR delta 960 and CHO/IRA1018 cells or wild-type cells at high insulin concentrations. These data suggest that the insulin-stimulated entry of the insulin receptor into a rapid, coated pit-mediated internalization pathway is saturable and requires receptor autophosphorylation and an intact juxtamembrane region. Furthermore, CHO cells also contain a constitutive nonsaturable pathway which does not require receptor autophosphorylation or an intact juxtamembrane region; this second pathway is unaffected by depletion of intracellular potassium, and therefore may be independent of coated pits. Our data suggest that the ligand-stimulated internalization of the insulin receptor may require specific saturable interactions between the receptor and components of the endocytic system.


Assuntos
Membrana Celular/metabolismo , Endocitose , Receptor de Insulina/metabolismo , Animais , Células CHO , Invaginações Revestidas da Membrana Celular/metabolismo , Cricetinae , Humanos , Insulina/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Fator de Crescimento Insulin-Like II/metabolismo , Cinética , Mutação , Fosforilação , Receptor de Insulina/genética
3.
J Cell Biol ; 118(4): 831-9, 1992 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1500426

RESUMO

We have investigated the role of tyrosine residues in the insulin receptor cytoplasmic juxtamembrane region (Tyr953 and Tyr960) during endocytosis. Analysis of the secondary structure of the juxtamembrane region by the Chou-Fasman algorithms predicts that both the sequences GPLY953 and NPEY960 form tyrosine-containing beta-turns. Similarly, analysis of model peptides by 1-D and 2-D NMR show that these sequences form beta-turns in solution, whereas replacement of the tyrosine residues with alanine destabilizes the beta-turn. CHO cell lines were prepared expressing mutant receptors in which each tyrosine was mutated to phenylalanine or alanine, and an additional mutant contained alanine at both positions. These mutations had no effect on insulin binding or receptor autophosphorylation. Replacements with phenylalanine had no effect on the rate of [125I]insulin endocytosis, whereas single substitutions with alanine reduced [125I]insulin endocytosis by 40-50%. Replacement of both tyrosines with alanine reduced internalization by 70%. These data suggest that the insulin receptor contains two tyrosine/beta-turns which contribute independently and additively to insulin-stimulated endocytosis.


Assuntos
Endocitose , Receptor de Insulina/química , Tirosina/química , Sequência de Aminoácidos , Animais , Células CHO , Cricetinae , Insulina/metabolismo , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Mutação , Fosforilação , Conformação Proteica , Receptor de Insulina/metabolismo
4.
Stud Health Technol Inform ; 124: 801-6, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17108612

RESUMO

This paper proposes a number of revisions to CEN/TS 14463 (ClaML), which is a pre-standard mark-up language for the electronic publication of classification coding schemes. A CEN Taskforce in close collaboration with the WHO network carefully analysed 70 classifications from the healthcare domain. All were transformed in ClaML using a dedicated classification management tool. The proposal removes all formatting elements and adds a number of layout structuring elements. Several elements have been replaced by attributes to enforce internal consistency. A modest number of extensions are proposed to help users and authors in maintenance and version control. A pilot implementation has shown that ICD10 as one of the most complex traditional classifications can be adequately represented to produce quality printed output.


Assuntos
Controle de Formulários e Registros/normas , Informática Médica , Linguagens de Programação , Classificação Internacional de Doenças
5.
Gene ; 163(2): 197-202, 1995 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-7590266

RESUMO

Distribution and variation of two P-element subfamilies designated M-type and O-type elements were investigated in Drosophila bifasciata (Db) and its relatives. PCR screening revealed that full-sized and internally deleted elements of both types occur in three geographic Db strains and in the related species, D. imaii (Di). Molecular analyses indicate differences in the evolutionary behaviour of the two P-element types. Internally deleted M-type elements fall into two size classes present in all three Db strains. In contrast, internally deleted O-type elements vary between the strains in number and length. With respect to genomic location, M-type elements seem to be restricted to conserved euchromatic sites, whereas the positions of O-type elements appear to be geographically variable. In one strain of Db (Italy), O-type elements seem to accumulate in the heterochromatin. Sequencing of a 397-bp segment shows intra- and interspecific divergence of M-type elements. In a 452-bp segment of the O-type elements, no substitutions were found, neither within nor between species. This finding suggests recent introgression of O-type elements via hybridization between Db and Di. Sequence identity and variation in chromosomal locations among different copies imply that O-type elements are transpositionally active. For M-type elements, genomic mobility cannot be proved. In a survey of several other taxa, no O-type-related sequences were detected so far. Therefore, the origin of the O-type subfamily remains unknown, whereas the source of M-type elements can be traced back to the genus Scaptomyza.


Assuntos
Elementos de DNA Transponíveis/genética , Drosophila/genética , Animais , Sequência de Bases , Evolução Biológica , Mapeamento Cromossômico , Dados de Sequência Molecular , Reação em Cadeia da Polimerase
6.
J Mol Evol ; 46(5): 542-51, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9545465

RESUMO

RT-PCR was applied to analyze the splicing patterns of P-element-derived mRNAs in Drosophila bifasciata, D. helvetica, and Scaptomyza pallida. D. melanogaster was used as a control. The experiments revealed that P elements are transcribed in all species investigated. However, there are differences in the splicing patterns of IVS3, which has to be removed in order to produce transposase mRNA instead of repressor mRNA. These differences are observed among species as well as between the P element subfamilies, the M and the O type, which coexist in the genomes of D. bifasciata and S. pallida. In D. helvetica M-type transposase mRNA was found in the germline and repressor mRNA in the soma, as has been previously described for the canonical (M-type-related) P element of D. melanogaster. In contrast, in S. pallida only repressor mRNA of M-type elements was detected in all tissues. In D. bifasciata, M-type IVS3, although activated both in the soma and the germline, is never completely excised. Instead, two alternative double-spliced variants occur in which two small introns are removed within the IVS3 region. One of these variants codes for a protein 12 aa longer than the regular transposase. Taking these findings together, transposase production and transpositional activity of M-type elements seem to be limited to D. helvetica and D. melanogaster, whereas M-type elements have become immobile in D. bifasciata and S. pallida. Unlike the M type, the splicing of O-type transcripts in D. bifasciata and S. pallida follows the classical rules of tissue-specific P element regulation: transposase mRNA is produced exclusively in the germline whereas repressor mRNA is formed in somatic cells. Thus O-type elements are thought to be still transpositionally active in both species. This finding is in accordance with the postulated recent transfer of O-type elements between the gene pools of D. bifasciata and S. pallida. In addition, we were able to show that the IVS3 double-spliced variants of both P element types are produced regularily in all species of the genus Drosophila investigated so far, but not in S. pallida.

7.
IEEE Trans Inf Technol Biomed ; 2(4): 229-42, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10719533

RESUMO

A common language, or terminology, for representing what clinicians have said and done is an important requirement for individual clinical systems, and it is a pre-requisite for integrating disparate applications in a distributed telematic healthcare environment. Formal representations based on description logics or closely related formalisms are increasingly used for representing medical terminologies. GALEN's experience in using one such formalism raises two major issues, as follows: how to make ontologies based on description logics easy to use and understand for both clinicians and applications developers; what features are required of the ontology and description logic if they are to achieve their aims. Based on our experience we put forward four contentions: two relating to each of these two issues, as follows: that natural language generation is essential to make a description logic based ontology accessible to users; that the description logic based ontology should be treated as an "assembly language" and accessed via "intermediate representations" oriented to users and "perspectives" adapting it to specific applications; that independence and reuse are best supported by partitioning the subsumption hierarchy of elementary concepts into orthogonal taxonomies, each of which forms a pure tree in which the branches at each level are disjoint but nonexhaustive subconcepts of the parent concept; that the expressivity of the description logic must include support for transitive relations despite the computational cost, and that this computational cost is acceptable in practice. The authors argue that these features will be necessary, though by no means sufficient, for the development of any large reusable ontology for medicine.


Assuntos
Medicina Clínica , Terminologia como Assunto , Doença/classificação
8.
Int J Med Inform ; 48(1-3): 85-101, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9600408

RESUMO

CEN ENV 12381 is a European Prestandard focusing on formal representation and explicit reference of temporal information in healthcare informatics and telematics. One of its merits is not just the possibility to represent natural language expressions containing time-related information in a structured way, but also to give some mechanisms on how clinical language itself can be used to convey meaning unambiguously. As such, CEN ENV 12381 introduces the notion of 'controlled language use' in the domain of healthcare. In this paper the principles behind controlled language design and use are explained. Through a detailed study of the inconsistencies and ambiguities that arise when interpreting Snomed procedure terms in the framework of the Galen-In-Use project, it is shown that most of them can be explained as a violation of sound term-formation principles. A proposal is made to develop a controlled language for health and to use it in subsequent versions of coding and classification systems. It is expected that such an endeavour will lead to a more effective application of linguistic engineering in areas such as automatic knowledge acquisition, automatic translation, and terminology validation in the domain of healthcare informatics.


Assuntos
Informática Médica/normas , Processamento de Linguagem Natural , Vocabulário Controlado , Inteligência Artificial , União Europeia , Terminologia como Assunto , Fatores de Tempo
9.
Int J Med Inform ; 58-59: 71-85, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10978911

RESUMO

Generalised architecture for languages, encyclopedia and nomenclatures in medicine (GALEN) has developed a new generation of terminology tools based on a language independent model describing the semantics and allowing computer processing and multiple reuses as well as natural language understanding systems applications to facilitate the sharing and maintaining of consistent medical knowledge. During the European Union 4 Th. framework program project GALEN-IN-USE and later on within two contracts with the national health authorities we applied the modelling and the tools to the development of a new multipurpose coding system for surgical procedures named CCAM in a minority language country, France. On one hand, we contributed to a language independent knowledge repository and multilingual semantic dictionaries for multicultural Europe. On the other hand, we support the traditional process for creating a new coding system in medicine which is very much labour consuming by artificial intelligence tools using a medically oriented recursive ontology and natural language processing. We used an integrated software named CLAW (for classification workbench) to process French professional medical language rubrics produced by the national colleges of surgeons domain experts into intermediate dissections and to the Grail reference ontology model representation. From this language independent concept model representation, on one hand, we generate with the LNAT natural language generator controlled French natural language to support the finalization of the linguistic labels (first generation) in relation with the meanings of the conceptual system structure. On the other hand, the Claw classification manager proves to be very powerful to retrieve the initial domain experts rubrics list with different categories of concepts (second generation) within a semantic structured representation (third generation) bridge to the electronic patient record detailed terminology.


Assuntos
Inteligência Artificial , Programas Nacionais de Saúde , Procedimentos Cirúrgicos Operatórios/classificação , Vocabulário Controlado , Indexação e Redação de Resumos , Sistemas Inteligentes , Humanos , Sistemas Computadorizados de Registros Médicos , Processamento de Linguagem Natural , Software , Terminologia como Assunto
10.
Stud Health Technol Inform ; 93: 127-36, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-15058424

RESUMO

Since 1987 several pain clinics in The Netherlands have started with some kind of computer-assisted recording of data, mainly for purposes of quality control. However, this has not yet led to routinely generated reports about the quality of these clinics because a consensus on how to assess quality in pain-treatment is missing. Using classical system-development methods a global specification for an information system for quality assessment was defined on which a prototype application was based. Various changes were adopted into this prototype, which ultimately resulted in explicit requirements stating: 1. Which data to record, 2. What organisational prerequisites to fulfil for such a system, 3. The user-interface, and 4. Interactions with other information systems. The final application was implemented in a number of pain clinics where its usefulness in quality control is currently assessed.


Assuntos
Sistemas Computadorizados de Registros Médicos/organização & administração , Clínicas de Dor/organização & administração , Manejo da Dor , Garantia da Qualidade dos Cuidados de Saúde/organização & administração , Benchmarking , Coleta de Dados , Design de Software , Integração de Sistemas , Interface Usuário-Computador
11.
Stud Health Technol Inform ; 43 Pt A: 441-5, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-10179587

RESUMO

This paper describes a novel approach in classification management where a formal model of medical semantics is being used for manipulations on existing classification systems. The paper addresses the issue of semi-automatically making specialist classifications that are compatible with the source classification. The examples in this paper are from a limited domain. At the time of the presentation results will be shown of the present modelling work within the GALEN-In-Use project. The model will then contain several thousands of medical procedures from four different classification centres.


Assuntos
Classificação , Processamento de Linguagem Natural , Linguagens de Programação , Vocabulário Controlado , Europa (Continente) , Humanos , Cooperação Internacional , Semântica
12.
Stud Health Technol Inform ; 84(Pt 1): 256-60, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11604744

RESUMO

The GALEN technology has matured over more than a decade of use. We describe a set of software tools and associated methodologies that together are supporting ontological engineering in a production, rather than a research setting.


Assuntos
Inteligência Artificial , Vocabulário Controlado , Classificação , Sistemas Integrados e Avançados de Gestão da Informação , Controle de Qualidade , Design de Software , Terminologia como Assunto
13.
Stud Health Technol Inform ; 43 Pt A: 241-5, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-10179546

RESUMO

This paper summarises the process in the GALEN-IN-USE project by which rubrics from traditional medical coding schemes are analysed into an intermediate, relatively informal conceptual representation which is then automatically translated into the GRAIL formalism and its Common Reference Model.


Assuntos
Processamento de Linguagem Natural , Procedimentos Cirúrgicos Operatórios/classificação , Europa (Continente) , Humanos , Cooperação Internacional , Design de Software
14.
Stud Health Technol Inform ; 68: 901-5, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10725030

RESUMO

GALEN has developed a new generation of terminology tools based on a language independent concept reference model using a compositional formalism allowing computer processing and multiple reuses. During the 4th framework program project Galen-In-Use we applied the modelling and the tools to the development of a new multipurpose coding system for surgical procedures (CCAM) in France. On one hand we contributed to a language independent knowledge repository for multicultural Europe. On the other hand we support the traditional process for creating a new coding system in medicine which is very much labour consuming by artificial intelligence tools using a medically oriented recursive ontology and natural language processing. We used an integrated software named CLAW to process French professional medical language rubrics produced by the national colleges of surgeons into intermediate dissections and to the Grail reference ontology model representation. From this language independent concept model representation on one hand we generate controlled French natural language to support the finalization of the linguistic labels in relation with the meanings of the conceptual system structure. On the other hand the classification manager of third generation proves to be very powerful to retrieve the initial professional rubrics with different categories of concepts within a semantic network.


Assuntos
Inteligência Artificial , Programas Nacionais de Saúde , Procedimentos Cirúrgicos Operatórios/classificação , Vocabulário Controlado , Indexação e Redação de Resumos , Sistemas Inteligentes , Humanos , Sistemas Computadorizados de Registros Médicos , Processamento de Linguagem Natural , Software , Terminologia como Assunto
15.
Oper Orthop Traumatol ; 25(4): 388-97, 2013 Aug.
Artigo em Alemão | MEDLINE | ID: mdl-23512177

RESUMO

OBJECTIVE: Cementless total hip arthroplasty with preservation of femoral neck and natural load transmission. Restoration of joint function and alleviation of pain. INDICATIONS: Osteoarthritis of the hip or femoral head necrosis in younger patients. CONTRAINDICATIONS: Patients biologically > 65 years. Destructed or discontinued femoral neck. Pathologic hip formation: short femoral neck, severe enhanced or reduced CCD angle. Body mass index (BMI) > 30 (relative contraindication). Manifest osteoporosis. Necessity of immediate full weight bearing. Heavy smoking (relative contraindication). Ongoing chemotherapy. SURGICAL TECHNIQUE: Anterolateral approach to the hip joint. Exposition of the femoral neck and resection of the femoral head at its lateral margin. Preparation of the acetabulum and insertion of a common acetabular component. Positioning of the center pin into the femoral neck. Face milling of the femoral neck butt. Preparation of the femoral neck with the Spiron drill bit. Insertion of the Spiron prosthesis. Trial reduction with a trial head. Substitution by the definitive head (cone 12/14 mm). Wound closure. POSTOPERATIVE MANAGEMENT: Low centred X-ray of the pelvis and cross table view of the hip joint. Physiotherapy and partial weight bearing for 6 weeks. Prevention of deep vein thrombosis until achievement of full weight bearing. RESULTS: A total of 28 Spiron prosthesis were implanted in 26 patients (15 men, 11 women, mean age 51 years [range 34-64 years], mean BMI 28 kg/m(2) [range 21-39 kg/m(2)]) from August 2009 to January 2012. Diagnoses: 13 cases of primary osteoarthritis, 8 cases of secondary osteoarthritis, 5 cases of femoral head necrosis, and 2 cases of posttraumatic osteoarthritis. The mean surgery length was 93 min (range 70-121 min), the mean hospital stay was 9 days (range 6-16 days). Blood transfusion was not necessary in any of the cases. There were no immediate complications such as deep vein thrombosis, surgery requiring secondary bleeding, wound infection, nerve palsy, or dislocation of the hip. Postoperative radiologic examinations showed an average leg lengthening of 3 mm (range -10-19 mm). No varus deviation of the prosthesis was observed. The Harris Hip Score improved from 55.4 points (range 33.5-76.9 points) preoperative to 90.5 points (range 75.7-99.9 points) 3 months postoperative. In 1 case with aseptic loosening, replacement surgery was performed without complications.


Assuntos
Artroplastia de Quadril/instrumentação , Necrose da Cabeça do Fêmur/cirurgia , Colo do Fêmur/cirurgia , Prótese de Quadril , Osteoartrite do Quadril/cirurgia , Adulto , Artroplastia de Quadril/métodos , Cimentação , Análise de Falha de Equipamento , Feminino , Necrose da Cabeça do Fêmur/diagnóstico por imagem , Necrose da Cabeça do Fêmur/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Osteoartrite do Quadril/complicações , Osteoartrite do Quadril/diagnóstico por imagem , Desenho de Prótese , Radiografia , Amplitude de Movimento Articular , Resultado do Tratamento
16.
Mol Phylogenet Evol ; 45(3): 840-62, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17920300

RESUMO

Intraspecific genetic diversity and phylogeography of Corvus corone was investigated using the mitochondrial (mt) control region as a molecular marker. A split into two distinct mt lineages was observed. One represents individuals from a wide geographic range spanning from England to the Russian Far East (Kamchatka), while the other one was found in the Primorye and Khabarovsk regions (southern parts of Russian Far East) as well as Japan. For comparison, we investigated several widespread Palearctic corvid taxa with respect to their phylogeographic patterns. A deep split into two lineages was revealed in five cases: Besides C. corone, within Corvus frugilegus, Pica pica, and between the species pairs Corvus monedula-Corvus dauuricus and Cyanopica cyanus-Cyanopica cooki. Although these taxa display a variety of distribution patterns, from disjunct, para/allopatric to continuous, the genetic pattern and level of divergence between clades is very similar. This implies that the differentiation started in about the same time range. In contrast, no differentiation into highly divergent lineages was detected in Corvus corax, Perisoreus infaustus, and Nucifraga caryocatactes. We try to explain the two phylogeographic patterns in corvid birds with ecological factors accompanying the changing climatic conditions during the Pleistocene. The deep genetic splits within several widely distributed Palearctic corvids are discussed with respect to taxonomic questions.


Assuntos
Aves/genética , Filogenia , Animais , Ásia , Aves/classificação , Ecologia , Europa (Continente)
17.
J Mol Evol ; 51(6): 577-86, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11116331

RESUMO

P elements of two different subfamilies designated as M- and O-type are thought to have invaded host species in the Drosophila obscura group via horizontal transmission from external sources. Sequence comparisons with P elements isolated from other species suggested that the horizontal invasion by the O-type must have been a rather recent event, whereas the M-type invasion should have occurred in the more distant past. To trace the phylogenetic history of O-type elements, additional taxa were screened for the presence of O- and M-type elements using type-specific PCR primers. The phylogeny deduced from the sequence data of a 927-bp section (14 taxa) indicate that O-type elements have undergone longer periods of regular vertical transmission in the lineages of the saltans and willistoni groups of Drosophila. However, starting from a species of the D. willistoni group they were transmitted horizontally into other lineages. First the lineage of the D. affinis subgroup was infected, and finally, in a more recent wave of horizontal spread, species of three different genera were invaded by O-type elements from the D. affinis lineage: Scaptomyza, Lordiphosa, and the sibling species D. bifasciata/D. imaii of the Drosophila obscura subgroup. The O-type elements isolated from these taxa are almost identical (sequence divergence <1%). In contrast, no such striking similarities are observed among M-type elements. Nevertheless, the sequence phylogeny of M-type elements is also not in accordance with the phylogeny of their host species, suggesting earlier horizontal transfer events. The results imply that P elements cross species barriers more frequently than previously thought but require a particular genomic environment and thus seem to be confined to a rather narrow spectrum of host species. Consequently, different P element types acquired by successive horizontal transmission events often coexist within the same genome.


Assuntos
Elementos de DNA Transponíveis , Drosophila/genética , Evolução Molecular , Animais , Sequência de Bases , Primers do DNA , Reação em Cadeia da Polimerase
18.
Genetica ; 98(1): 43-51, 1996 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8765681

RESUMO

Two distinct P element subfamilies, designated M-type and O-type, reside in the genome of D. bifasciata. PCR-screening of 65 Drosophila species revealed that only D. bifasciata and its closest relative D. imaii possess O-type elements. Outside the genus, O-type elements were detected in Scaptomyza pallida. Restriction analyses show that the general structure of the O-type elements from S. pallida and D. bifasciata is the same. Sequence divergence turned out to be extremely low (0.43%). These results suggest that the O-type subfamily of D. bifasciata has been received by horizontal transfer from an external source, most probably from the genus Scaptomyza, as has been previously suspected for the M-type family. Since the sequence divergence between M-type elements from S. pallida and D. bifasciata is eighteen-fold higher than that between O-type elements, two independent intergeneric transfer events have to be postulated. In order to re-examine the taxonomic status of S. pallida, a partial sequence (489 bp) of the Adh gene was analysed. The data clearly prove that S. pallida has to be placed far outside the D. obscura group.


Assuntos
Elementos de DNA Transponíveis/genética , Drosophila/genética , Drosophilidae/genética , Filogenia , Álcool Desidrogenase/genética , Animais , Sequência de Bases , Genes de Insetos , Variação Genética/genética , Dados de Sequência Molecular , Mapeamento por Restrição , Análise de Sequência de DNA , Especificidade da Espécie
19.
Genome ; 39(5): 978-85, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8890523

RESUMO

A new P element subfamily, designated T-type, was found in the genomes of the three closely related species Drosophila ambigua, Drosophila obscura, and Drosophila tristis. The subfamily comprises both full-sized and internally deleted P elements. The T-type element of D. ambigua is longer than the canonical P elements owing to a 300-bp insertion in the 3' noncoding region. Tandemly arranged T-type elements were detected in D. ambigua and D. tristis. The overall structure of T-type elements resembles that of the Drosophila melanogaster P element and the termini are formed by perfect inverted repeats of 33 bp. However, none of the elements studied so far have intact reading frames. Sequence comparisons with other P element subfamilies from the obscura group indicate that the T-type elements are most closely related to the terminally truncated P homologues of Drosophila guanche and Drosophila subobscura. Therefore they can be considered as the lineage-specific P transposons of the obscura group. Furthermore, this finding indicates that the clustered P homologues of D. guanche and D. subobscura must be derived from transpositionally active P elements rather than from an immobile genomic sequence.


Assuntos
Elementos de DNA Transponíveis , Drosophila/genética , Sequências Repetitivas de Ácido Nucleico , Animais , Sequência de Bases , Mapeamento Cromossômico , DNA/genética , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase
20.
Mamm Genome ; 9(3): 214-9, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9501305

RESUMO

We have determined the canine and feline N-, K-, and H-ras gene sequences from position +23 to +270 covering exons I and II which contain the mutational hot spot codons 12, 13, and 61. The results were used to assess the degree of similarity between ras gene DNA regions containing the critical domains affected in neoplastic disorders in different mammalian species. The comparative analyses performed included human, canine, feline, murine, rattine, and, whenever possible, bovine, leporine (rabbit), porcelline (guinea pig), and mesocricetine (hamster) ras gene sequences within the region of interest. Comparison of feline and canine nucleotide sequences with the corresponding regions in human DNA revealed a sequence similarity greater than 85% to the human sequence. Contemporaneous analysis of previously published ras DNA sequences from other mammalian species showed a similar degree of homology to human DNA. Most nucleotide differences observed represented synonymous changes without effect on the amino acid sequence of the respective proteins. For assessment of the phylogenetic evolution of ras gene family, a maximum parsimony dendrogram based on multiple sequence alignment of the common region of exons I and II in the N-, K-, and H-ras genes was constructed. Interestingly, a higher substitution rate among the H-ras genes became apparent, indicating accelerated sequence evolution within this particular clade. The most parsimonious tree clearly shows that the duplications giving rise to the three ras genes must have occurred before the mammalian radiation.


Assuntos
Éxons , Genes ras , Animais , Sequência de Bases , Gatos , Bovinos , Sequência Conservada , DNA Complementar , Cães , Humanos , Mamíferos , Dados de Sequência Molecular , Filogenia , Pseudogenes
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA