ABSTRACT
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.
Subject(s)
Evolution, Molecular , Genes, MHC Class II , Genes, MHC Class I , Oncorhynchus/genetics , Oncorhynchus/immunology , Alleles , Amino Acid Sequence , Animals , Antigen Presentation/genetics , Female , Genetic Variation/immunology , Humans , Introns/immunology , Molecular Sequence Data , Oncorhynchus mykiss/genetics , Oncorhynchus mykiss/immunology , Phylogeny , Primates , Recombination, Genetic/immunology , Sequence Homology, Amino AcidABSTRACT
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.
Subject(s)
Evolution, Molecular , Killer Cells, Natural/metabolism , Lectins, C-Type , Pan troglodytes/immunology , Receptors, Immunologic/chemistry , Receptors, Immunologic/physiology , Animals , Antigens, CD/chemistry , Binding Sites, Antibody , Binding, Competitive/immunology , Cell Lineage/genetics , Cell Lineage/immunology , Clone Cells , Conserved Sequence , Histocompatibility Antigens Class I/metabolism , Humans , Killer Cells, Natural/immunology , Membrane Glycoproteins/antagonists & inhibitors , Membrane Glycoproteins/chemistry , Molecular Sequence Data , NK Cell Lectin-Like Receptor Subfamily C , NK Cell Lectin-Like Receptor Subfamily D , Receptors, Immunologic/antagonists & inhibitors , Receptors, Immunologic/biosynthesis , Receptors, KIR , Receptors, Natural Killer Cell , Sequence Homology, Amino Acid , Structure-Activity RelationshipABSTRACT
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.
Subject(s)
Aged/statistics & numerical data , Body Mass Index , Chronic Disease/mortality , Activities of Daily Living , Aged, 80 and over , Analysis of Variance , Female , Humans , Male , Predictive Value of Tests , Retrospective Studies , Survival Analysis , Sweden/epidemiologyABSTRACT
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