RESUMEN
Rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) represent two salmonid genera separated for 15--20 million years. cDNA sequences were determined for the classical MHC class I heavy chain gene UBA and the MHC class II beta-chain gene DAB from 15 rainbow and 10 brown trout. Both genes are highly polymorphic in both species and diploid in expression. The MHC class I alleles comprise several highly divergent lineages that are represented in both species and predate genera separation. The class II alleles are less divergent, highly species specific, and probably arose after genera separation. The striking difference in salmonid MHC class I and class II evolution contrasts with the situation in primates, where lineages of class II alleles have been sustained over longer periods of time relative to class I lineages. The difference may arise because salmonid MHC class I and II genes are not linked, whereas in mammals they are closely linked. A prevalent mechanism for evolving new MHC class I alleles in salmonids is recombination in intron II that shuffles alpha 1 and alpha 2 domains into different combinations.
Asunto(s)
Evolución Molecular , Genes MHC Clase II , Genes MHC Clase I , Oncorhynchus/genética , Oncorhynchus/inmunología , Alelos , Secuencia de Aminoácidos , Animales , Presentación de Antígeno/genética , Femenino , Variación Genética/inmunología , Humanos , Intrones/inmunología , Datos de Secuencia Molecular , Oncorhynchus mykiss/genética , Oncorhynchus mykiss/inmunología , Filogenia , Primates , Recombinación Genética/inmunología , Homología de Secuencia de AminoácidoRESUMEN
That NK cell receptors engage fast-evolving MHC class I ligands suggests that they, too, evolve rapidly. To test this hypothesis, the structure and class I specificity of chimpanzee KIR and CD94:NKG2 receptors were determined and compared to their human counterparts. The KIR families are divergent, with only three KIR conserved between chimpanzees and humans. By contrast, CD94:NKG2 receptors are conserved. Whereas receptors for polymorphic class I are divergent, those for nonpolymorphic class I are conserved. Although chimpanzee and human NK cells exhibit identical receptor specificities for MHC-C, they are mediated by nonorthologous KIR. These results demonstrate the rapid evolution of NK cell receptor systems and imply that "catching up" with class I is not the only force driving this evolution.
Asunto(s)
Evolución Molecular , Células Asesinas Naturales/metabolismo , Lectinas Tipo C , Pan troglodytes/inmunología , Receptores Inmunológicos/química , Receptores Inmunológicos/fisiología , Animales , Antígenos CD/química , Sitios de Unión de Anticuerpos , Unión Competitiva/inmunología , Linaje de la Célula/genética , Linaje de la Célula/inmunología , Células Clonales , Secuencia Conservada , Antígenos de Histocompatibilidad Clase I/metabolismo , Humanos , Células Asesinas Naturales/inmunología , Glicoproteínas de Membrana/antagonistas & inhibidores , Glicoproteínas de Membrana/química , Datos de Secuencia Molecular , Subfamília C de Receptores Similares a Lectina de Células NK , Subfamília D de Receptores Similares a Lectina de las Células NK , Receptores Inmunológicos/antagonistas & inhibidores , Receptores Inmunológicos/biosíntesis , Receptores KIR , Receptores de Células Asesinas Naturales , Homología de Secuencia de Aminoácido , Relación Estructura-ActividadRESUMEN
BACKGROUND AND AIMS: The predictive value of body mass and functional capacity for 1 year mortality was examined retrospectively in 552 consecutive geriatric patients categorized in 14 diagnosis groups. METHODS: Data on body mass index (BMI, kg/m(2)) was retrievable from 337 subjects. In 532 patients, Katz indexes of activities of daily life (ADL, A-G; A=independent, G total dependence) were registered. The mean age (+/- SD) was 81 +/- 8 years, two-thirds were women and 75% lived alone. Mortality data was obtained from the Swedish population records. RESULTS: Thirty-six per cent of the patients had BMI values < or =43% had BMI 21-25 and 21% > 25. Less than 2% were diagnosed as malnourished. The 1 year mortalities of those with BMI < or = 20, BMI 21-25 and BMI > 25 were 48%, 29% and 18% respectively (P< 0.001). Katz ADL index was significantly worse in those with BMI > 20 as compared with those having BMI < or = 20 (Katz D and C (P< 0.01) respectively). Patients with chronic obstructive lung disease displayed the lowest BMI values, i.e. 20 +/- 4. A logistic regression analysis indicated that BMI, gender and Katz ADL index, but not age, diagnosis or marital status, were independent predictors of 1 year mortality. CONCLUSION: Depletion may still be an overlooked problem in geriatric patients, in whom low body mass index appears to be independently associated with imminent death.
Asunto(s)
Anciano/estadística & datos numéricos , Índice de Masa Corporal , Enfermedad Crónica/mortalidad , Actividades Cotidianas , Anciano de 80 o más Años , Análisis de Varianza , Femenino , Humanos , Masculino , Valor Predictivo de las Pruebas , Estudios Retrospectivos , Análisis de Supervivencia , Suecia/epidemiologíaRESUMEN
Reversed sexual size dimorphism, with males smaller than females, is common in waders. The aerial display hypothesis suggests that sexual selection in males favours aerial agility, and hence small size, in species with male display flights. We tested this hypothesis in the dunlin, Calidris alpinaDisplay flights were uncommon in the early breeding season but increased markedly when females began laying. Male display areas were largely overlapping, and display flight seemed to be mainly an advertising signal to potential mates. Display rate, as well as proportion of time spent in aerial display, increased with decreasing male size. During aerial display, small males also performed costly hovering flights more often and for relatively longer than large males. These results support the aerial display hypothesis.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour