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Inference of Selection Based on Temporal Genetic Differentiation in the Study of Highly Polymorphic Multigene Families

McMullan, Mark; van Oosterhout, Cock
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 10/08/2012 EN
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26.15%
The co-evolutionary arms race between host immune genes and parasite virulence genes is known as Red Queen dynamics. Temporal fluctuations in allele frequencies, or the ‘turnover’ of alleles at immune genes, are concordant with predictions of the Red Queen hypothesis. Such observations are often taken as evidence of host-parasite co-evolution. Here, we use computer simulations of the Major Histocompatibility Complex (MHC) of guppies (Poecilia reticulata) to study the turnover rate of alleles (temporal genetic differentiation, G'ST). Temporal fluctuations in MHC allele frequencies can be ≥≤order of magnitude larger than changes observed at neutral loci. Although such large fluctuations in the MHC are consistent with Red Queen dynamics, simulations show that other demographic and population genetic processes can account for this observation, these include: (1) overdominant selection, (2) fluctuating population size within a metapopulation, and (3) the number of novel MHC alleles introduced by immigrants when there are multiple duplicated genes. Synergy between these forces combined with migration rate and the effective population size can drive the rapid turnover in MHC alleles. We posit that rapid allelic turnover is an inherent property of highly polymorphic multigene families and that it cannot be taken as evidence of Red Queen dynamics. Furthermore...

Notification of tuberculosis: how many cases are never reported?

Sheldon, C D; King, K; Cock, H; Wilkinson, P; Barnes, N C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1992 EN
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26.15%
BACKGROUND: Notification of tuberculosis is essential for local contact tracing and for assessing the national incidence of tuberculosis. The accuracy of notification figures is uncertain. This study examined the notification rates of all patients diagnosed as having tuberculosis at two hospitals in the East End of London over five years. METHODS: In a retrospective survey of all patients aged 16 years or more presenting with tuberculosis to the London Chest Hospital or the Royal London Hospital from 1 January 1985 to 31 December 1989, cases of tuberculosis were identified from microbiology and histology records, statutory notifications, necropsy reports, coroners' records, hospital activity data, and death certificates. Clinical data were obtained from case notes and notification was determined from the local authority notification lists. RESULTS: Six hundred and nine adult patients with tuberculosis were identified. Notes were available for 580 cases (95%), of which 426 (73%) had been notified. The proportion of cases notified varied according to the specialty of the clinician in charge of the patient at diagnosis. Patients with a past history of tuberculosis and those who died within one year were less likely to have had their tuberculosis notified. Age...

A prop??sito de un ritual. 'Correr el gallo', un rito de iniciaci??n

Benito Riesco, Orlando
Fonte: Pedro G??mez Publicador: Pedro G??mez
Tipo: Artigo de Revista Científica
SPA
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26.15%
Los rituales han sido estudiados de manera amplia desde la antropolog??a y tambi??n desde la terapia familiar sist??mica. La cual, retom?? los rituales del plano descriptivo-antropol??gico para utilizarla como t??cnica psicoterap??utica. En segundo lugar, y aprovechando la revisi??n anterior, el siguiente trabajo describe y analiza un rito de iniciaci??n que se viene realizando de manera tradicional en una serie de pueblos de la provincia de Zamora, aunque ??ltimamente se encuentra amenazada de extinci??n. Esta ceremonia, a??ade adem??s unos elementos narrativos muy importantes: las relaciones (material que se muestra al final del trabajo). Utilizando varios de los conceptos desarrollados por la teor??a sist??mica se analizan las repercusiones y funciones de dicho ritual en el sistema pueblo, que es un sistema m??s amplio que el de familia, al cual engloba.; Rituals have been widely studied from Anthropology as well as systemic family therapy. The latter is examined from a descriptive anthropological level for use as a psychotherapeutic resource. Secondly, taking advantage of previous overview, the following paper describes and analyses an initiation rite which has been traditionally performed in some villages of Zamora (Spain). Although lately threatened with disappearing...