RESUMEN
The many documented examples of parallel and convergent evolution in similar environments are strong evidence for the role of natural selection in the evolution of trait variation. However, species may respond to selection in different ways; idiosyncrasies of their evolutionary history may affect how different species respond to the same selective pressure. To determine whether evolutionary history affects trait-environment associations in a recently diverged lineage, we investigated within-species trait-environment associations in the white proteas, a closely related monophyletic group. We first used manovas to determine the relative importance of shared response to selection, evolutionary history and unique responses to selection on trait variation. We found that on average, similar associations to the environment across species explained trait variation, but that the species had different mean trait values. We also detected species-specific associations of traits with the environmental gradients. To identify the traits associated uniquely with the environment, we used a structural equation model. Our analysis showed that the species differed in how their traits were associated with each of the environmental variables. Further, in the cases of two root traits (root mass and root length/mass ratio), two species differed in the direction of their associations (e.g. populations in one species had heavier roots in warmer areas, and populations in the other species had lighter roots in warmer areas). Our study shows that even in a closely related group of species, evolutionary history may have an effect on both the size and direction of adaptations to the environment.
Asunto(s)
Adaptación Fisiológica , Ambiente , Proteaceae/fisiología , Evolución Biológica , Raíces de Plantas/fisiología , Selección Genética , Especificidad de la EspecieRESUMEN
In this study, the setting of calcium-sulphate (CS) and -phosphate (CP) based bone cements (BCs) was monitored by ultrasound. The objective was to link acoustic and material properties of ceramic-based BCs from the early stages of the cement curing process. The powder phase of the CS-cement consisted of CS hemihydrate; the CP-cement was a mixture of alpha-tricalcium phosphate, CS dihydrate and hydroxyapatite. For the CS-cement, the acoustic impedance z (c)(t), the speed of sound c (c)(t) and the density ρ(c)(t) were measured at the interval of liquid-to-powder ratios LPRs from 0.20 to 3.00 ml/g. For the CP-cement, the acoustic characteristics obtained were the z (c)(t) and the reflection coefficient R (p,c)(t), and the LPRs ranged from 0.30 to 0.40 ml/g. The resulting acoustic properties indicated that CP- and CS-cements exhibited distinctly different curing behaviour; while CS-cement expanded, CP-cement shrank with time.
Asunto(s)
Cementos para Huesos , Calcio , UltrasonidoRESUMEN
In some ultrasonic measurement situations, an adequate signal separation is difficult to achieve. A typical situation is material characterization of thin media using pulse-echo or through-transmission techniques, when the time-of-flight in the media is shorter than the emitted signal's time support. Separated signals are necessary to obtain accurate estimates of material properties and transit times. In this paper a new method is proposed that enables complete post-separation of measured coinciding signals. The method is based on a combination of hard physical and soft empirical models, which allows for a description of both known and unknown properties making a complete separation possible. The validity and limitations of the model and the separation results are thoroughly addressed. The proposed technique is verified using real measurements on thin dispersive samples and validated using residual analysis. The experimental results show a complete separation with uncorrelated and normally distributed residuals. The method enables characterization and/or flow analysis in difficult overlapping situations.
Asunto(s)
Ensayo de Materiales/métodos , Modelos Teóricos , Ultrasonografía/métodos , Simulación por Computador , Dureza , Dispersión de RadiaciónRESUMEN
In unperturbed mice, the marrow cell numbers correlate with the stem cell numbers. High levels of long-term marrow engraftment are obtained with infusion of high levels of marrow cells in untreated mice. To address the issue of stem cell competition vs 'opening space', knowledge of total murine marrow cellularity and distribution of stem and progenitor cells are necessary. We determined these parameters in different mouse strains. Total cellularity in BALB/c mice was 530+/-20 million cells; stable from 8 weeks to 1 year of age. C57BL/6J mice had 466+/-48 million marrow cells. Using these data, theoretical models of infused marrow (40 million cells) replacing or adding to host marrow give chimerism values of 7.5 and 7.0%, respectively; the observed 8-week engraftment of 40 million male BALB/c marrow cells into female hosts (72 mice) gave a value of 6.91+/-0.4%. This indicates that syngeneic engraftment is determined by stem cell competition. Our studies demonstrate that most marrow cells, progenitors and engraftable stem cells are in the spine. There was increased concentration of progenitors in the spine. Total marrow harvest for stem cell purification and other experimental purposes was both mouse and cost efficient with over a four-fold decrease in animal use and a financial saving.
Asunto(s)
Células de la Médula Ósea/citología , Células Madre Hematopoyéticas/citología , Animales , Recuento de Células Sanguíneas , Separación Celular/métodos , Femenino , Supervivencia de Injerto , Trasplante de Células Madre Hematopoyéticas/métodos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BLRESUMEN
Twenty-two highly variable SSR markers were developed in Douglas-fir [ Pseudotsuga menziesii (Mirb.) Franco] from five SSR-enriched genomic libraries. Fifteen PCR primer pairs amplified a single codominant locus, while seven primer pairs occasionally amplified two loci. The Mendelian inheritance of all 22 SSRs was confirmed via segregation analyses in several Douglas-fir families. The mean observed heterozygosity and the mean number of alleles per locus were 0.855 (SE=0.020) and 23 (SE=1.6), respectively. Twenty markers were used in genetic linkage analysis and mapped to ten known linkage groups. Because of their high polymorphism and unambiguous phenotypes, 15 single-locus markers were selected as the most suitable for DNA fingerprinting and parentage analysis. Only three SSRs were sufficient to achieve an average probability of exclusion from paternity of 0.998 in a Douglas-fir seed orchard block consisting of 59 parents.
Asunto(s)
Marcadores Genéticos , Árboles/genética , Secuencia de Bases , Cartilla de ADN , Heterocigoto , Fenotipo , Polimorfismo GenéticoAsunto(s)
Acetiltransferasas/química , Proteínas de Ciclo Celular/química , Fragmentos de Péptidos/química , Isótopos de Carbono , Histona Acetiltransferasas , Isótopos de Nitrógeno , Resonancia Magnética Nuclear Biomolecular , Estructura Terciaria de Proteína , Protones , Factores de Transcripción , Factores de Transcripción p300-CBPRESUMEN
Forty-eight primer pairs for chicken (Gallus gallus) microsatellite loci were tested in polymerase chain reaction (PCR) amplification of Japanese quail (Coturnix japonica) genomic DNA. Amplification products were obtained from 28 primer-pairs (58.3%) after optimizing the PCR conditions. Eleven (22.9%) of these generated specific products and 17 yielded non-specific amplification products. Eight markers (ADL0037, ADL0038, ADL0142, ADL0143, ADL0206, ADL0315, ADL0366, and HUJ0006) were polymorphic and three were monomorphic (ADL0023, ADL0024, and ADL0257) in four Japanese quail populations. Specific amplification products from each of the 11 PCR primers were sequenced. Seven of the eight polymorphic and one of three monomorphic markers contained simple tandem repeats. Six of these microsatellite loci (ADL0037, ADL0315, ADL0142, ADL0143, ADL0366 and ADL0257) may be homologous to the corresponding chicken loci from which the markers were developed.
Asunto(s)
Pollos/genética , Coturnix/genética , Repeticiones de Microsatélite , Alelos , Animales , Secuencia de Bases , Cartilla de ADN , Femenino , Amplificación de Genes , Masculino , Reacción en Cadena de la Polimerasa , Especificidad de la EspecieRESUMEN
Coniferin beta-glucosidase (CBG) catalyzes the hydrolysis of monolignol glucosides to release the cinnamyl alcohols for oxidative polymerization to lignin. Utilizing the N-terminal amino acid sequence of the purified enzyme, the corresponding full-length cDNA sequence was isolated from a Pinus contorta xylem-specific library. The isolated 1909 nucleotide cDNA was confirmed to be that of CBG on the basis of its high homology to family 1 glycosyl hydrolases, the sequence identity with the N-terminal amino acid residues of the purified enzyme, and the coniferin hydrolytic activity and substrate specificity profile displayed by the recombinant protein when expressed in Escherichia coli. The presence of a 23 amino acid N-terminal signal peptide in the deduced 513 amino acid enzyme suggests that CBG is a secretory protein targeted to the ER. The isolation of CBG cDNA will facilitate the evaluation of the importance of this enzyme in the ultimate stages of lignin biosynthesis and could be a valuable tool in manipulating lignin levels in xylem cell walls.
Asunto(s)
Cinamatos/metabolismo , ADN Complementario/genética , beta-Glucosidasa/genética , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , ADN Complementario/química , Escherichia coli/genética , Regulación Enzimológica de la Expresión Génica , Datos de Secuencia Molecular , Filogenia , Análisis de Secuencia de ADN , Árboles/química , Árboles/enzimología , Árboles/genética , beta-Glucosidasa/metabolismoRESUMEN
Histone acetylation is important in chromatin remodelling and gene activation. Nearly all known histone-acetyltransferase (HAT)-associated transcriptional co-activators contain bromodomains, which are approximately 110-amino-acid modules found in many chromatin-associated proteins. Despite the wide occurrence of these bromodomains, their three-dimensional structure and binding partners remain unknown. Here we report the solution structure of the bromodomain of the HAT co-activator P/CAF (p300/CBP-associated factor). The structure reveals an unusual left-handed up-and-down four-helix bundle. In addition, we show by a combination of structural and site-directed mutagenesis studies that bromodomains can interact specifically with acetylated lysine, making them the first known protein modules to do so. The nature of the recognition of acetyl-lysine by the P/CAF bromodomain is similar to that of acetyl-CoA by histone acetyltransferase. Thus, the bromodomain is functionally linked to the HAT activity of co-activators in the regulation of gene transcription.
Asunto(s)
Acetiltransferasas/metabolismo , Compuestos de Bromina/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas de Saccharomyces cerevisiae , Acetiltransferasas/química , Acetiltransferasas/genética , Secuencia de Aminoácidos , Compuestos de Bromina/química , Proteínas de Ciclo Celular/química , Cristalografía por Rayos X , Escherichia coli , Histona Acetiltransferasas , Ligandos , Lisina/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Unión Proteica , Conformación Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Homología de Secuencia de Aminoácido , Factores de Transcripción , Factores de Transcripción p300-CBPRESUMEN
Phenylalanine ammonia-lyase (PAL) catalyzes the first step in phenylpropanoid metabolism and plays a central role in the biosynthesis of phenylpropanoid compounds. We have previously cloned two PAL genes, PALI and PAL2, from a Populus trichocarpa x P. deltoides F1 hybrid. Here, we describe the properties of PALI and PAL2 promoters and their expression patterns in transgenic tobacco and poplar. The promoters were 75% identical in the regions sequenced, and each contained two copies of AC-rich putative cis-acting elements that matched a consensus plant myb transcription factor binding site sequence. In transgenic tobacco, PALI-GUS and PAL2-GUS fusions directed similar patterns of expression in developing primary xylem of leaves, stems, and other organs, and in secondary xylem of stems. Contrary to previously documented patterns of PAL1/2 expression in poplar, no expression of either fusion was detected in epidermal or subepidermal cell layers of young tobacco leaves or stems. In poplar, the PAL2-GUS fusion directed the highest levels of expression in roots and young leaves and stems. In young leaves and stems, high GUS activity was detected in epidermal or subepidermal cells as well as in primary xylem and phloem fibers. GUS activity was low in woody stems, and was weak or absent in developing secondary xylem. The patterns of PAL2-GUS expression in poplar are very similar to those of PAL1/2 mRNA accumulation in poplar. However, the distinct patterns of expression directed by the PAL2 promoter in poplar and tobacco show that PAL2-GUS expression in tobacco does not accurately reflect all aspects of PAL2 expression in poplar.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Fenilanina Amoníaco-Liasa/genética , Regiones Promotoras Genéticas , Árboles/crecimiento & desarrollo , Árboles/genética , Secuencia de Bases , Sitios de Unión , Secuencia Conservada , Regulación del Desarrollo de la Expresión Génica , Genes de Plantas , Isoenzimas/biosíntesis , Isoenzimas/genética , Datos de Secuencia Molecular , Fenilanina Amoníaco-Liasa/biosíntesis , Hojas de la Planta , Tallos de la Planta , Plantas Modificadas Genéticamente , Plantas Tóxicas , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-myb , Mapeo Restrictivo , Alineación de Secuencia , Homología de Secuencia de Ácido Nucleico , Nicotiana/genética , Nicotiana/metabolismo , Transactivadores/metabolismo , Factores de Transcripción , Árboles/metabolismoRESUMEN
BACKGROUND: Orthostatic hypotension, a decline in erect blood pressure, is the result of an impaired hemodynamic response to an upright posture or a depletion intravascular volume. The measurement of orthostatic blood pressure can be done at the bedside and therefore is easily applied to several clinical disorders. Despite its usefulness, the measurement is often neglected, possibly because of confusion regarding the appropriate measurement technique and suitable application to patient care. METHODS: Pertinent recent medical literature was reviewed. RESULTS: The normal physiologic response to the assumption of an upright posture is a small drop in blood pressure and a slight rise in pulse rate. Orthostatic hypotension is detected by measurement of blood pressure in two or more body positions. An abnormal blood pressure response can be observed with disorders such as syncope, falling, intravascular volume depletion, and autonomic dysfunction; with the treatment of maladies such as hypertension and heart failure; and with the use of several medications. CONCLUSIONS: The measurement of orthostatic blood pressure is an essential clinical tool for the assessment and management of patients affected by common medical disorders.
Asunto(s)
Hipotensión Ortostática/diagnóstico , Diagnóstico Diferencial , Humanos , Hipotensión Ortostática/etiología , Síncope/etiologíaRESUMEN
The effects of disability on an aging population's health and welfare are an important issue in gerontological research. The rapid growth of the elderly population and increases in longevity have led to an ongoing debate about whether longer lives can be matched by longer active lives that are free from disability. After a detailed review of current disability literature, the authors discuss the impact of disability in the elderly, defining disability and reviewing three classes of disability--physical, mental, and social. Both subjective and objective disability measures are described, and disability trends and prevalence rates are reviewed and compared cross culturally, by gender, by age, and over time. The path from chronic disease to disability is described and the consequences of living with disability are discussed in terms of family burdens and the increased need for medical care.
Asunto(s)
Personas con Discapacidad , Actividades Cotidianas , Anciano , Causalidad , Costo de Enfermedad , Evaluación de la Discapacidad , Personas con Discapacidad/clasificación , Personas con Discapacidad/psicología , Personas con Discapacidad/estadística & datos numéricos , Evaluación Geriátrica , Humanos , Esperanza de Vida , Prevalencia , Estados Unidos/epidemiologíaRESUMEN
In this 2nd article in the series on older adults (persons aged > or = 65 years), the role of physical activity in preventing disability associated with aging in the absence of specific illnesses is discussed, and different types of activities and the measures of outcome are described. Evidence for physical activity as a prevention measure is restricted to primary and secondary prevention because the application of physical activity for tertiary prevention of disability is limited. Chronic disease is considered in the context of its influence on disability only when physical activity offers some potential benefit to elderly persons.
Asunto(s)
Personas con Discapacidad , Ejercicio Físico/fisiología , Promoción de la Salud/métodos , Inmovilización/efectos adversos , Prevención Primaria/métodos , Actividades Cotidianas , Anciano , Enfermedad Crónica/epidemiología , Conductas Relacionadas con la Salud , Humanos , Evaluación de Resultado en la Atención de Salud , Aptitud Física/fisiologíaRESUMEN
A series of thiol containing derivatives was prepared. Several of these compounds were found to inhibit matrix metalloproteinases 1, 3, and 9 with selectivity towards 3 and 9. Compounds 15, 20, and 22 were administered to rats orally at 75 mumol/kg. Drug levels of compounds 20 and 22 in the plasma were found to exceed the IC50 values for MMP 3 and 9 four hours after administration.
Asunto(s)
Metaloendopeptidasas/antagonistas & inhibidores , Compuestos de Sulfhidrilo/síntesis química , Animales , Relación Dosis-Respuesta a Droga , Diseño de Fármacos , Concentración 50 Inhibidora , Inhibidores de la Metaloproteinasa de la Matriz , Ratas , Compuestos de Sulfhidrilo/administración & dosificación , Compuestos de Sulfhidrilo/sangre , Factores de TiempoRESUMEN
Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] is one of the world's most valuable timber species and is widely used in reforestation. Therefore there is considerable interest in understanding its genetic structure. In conifers approximately 75% of the genome is composed of repetitive DNA. Thus for conifers characterization of repetitive DNA is a significant part of genome analysis. We have characterized the organization of 5S rRNA genes in Douglas-fir at both the molecular and chromosome levels. 5S DNA repeat units containing the coding sequence for 5S rRNA and the nontranscribed spacer (NTS) were cloned using PCR. Sequencing and Southern hybridization revealed repeat units of 888 and 871 bp in length, the latter with a 17 bp deletion in the NTS. The coding region showed high homology with other eukaryotic 5S rRNA genes. A 35 bp region of the NTS immediately upstream of the 5' end of the coding region showed high similarity to other conifers but not to other published plant 5S rDNA sequences. Physical mapping of 5S rDNA by fluorescent in situ hybridization using a biotinilated homologous probe revealed a single subtelomeric site on one pair of large metacentric chromosomes.
Asunto(s)
Mapeo Físico de Cromosoma , ARN Ribosómico 5S/genética , Árboles/genética , Secuencia de Bases , Clonación Molecular , ADN de Plantas , Hibridación Fluorescente in Situ , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Homología de Secuencia de Ácido NucleicoRESUMEN
Repeated DNA families contribute to the large genomes of coniferous trees but are poorly characterized. We report the analysis of a 142 bp tandem repeated DNA sequence identified by the restriction enzyme Sau3A and found in approximately 20,000 copies in Picea glauca. Southern hybridization indicated that the repeated DNA family is specific to the genus, was amplified early in its evolution, and has undergone little structural alteration over evolutionary time. Fluorescence in situ hybridization localized arrays of the Sau3A repeating element to the centromeric regions of different subsets of the metaphase chromosomes of P. glauca and the closely related Picea sitchensis, suggesting that mechanisms leading to the intragenomic movement of arrays may be more active than those leading to mutation of the repeating elements themselves. Unambiguous identification of P. glauca and P. sitchensis chromosomes was made possible by co-localizing the Sau3A tandem repeats and the genes encoding the 5S and 18S-5.8S-26S ribosomal RNAs.
Asunto(s)
ADN de Plantas/genética , ADN Ribosómico/genética , Secuencias Repetitivas de Ácidos Nucleicos , Árboles/genética , Secuencia de Bases , ADN de Plantas/química , ADN Ribosómico/química , Desoxirribonucleasas de Localización Especificada Tipo II , Biblioteca Genómica , Hibridación Fluorescente in Situ , Datos de Secuencia Molecular , Mapeo Restrictivo , Especificidad de la Especie , Árboles/clasificaciónRESUMEN
Patterns of illness in American children have changed dramatically in this century. The ancient infectious diseases have largely been controlled. The major diseases confronting children now are chronic and disabling conditions termed the "new pediatric morbidity"--asthma mortality has doubled; leukemia and brain cancer have increased in incidence; neurodevelopmental dysfunction is widespread; hypospadias incidence has doubled. Chemical toxicants in the environment as well as poverty, racism, and inequitable access to medical care are factors known and suspected to contribute to causation of these pediatric diseases. Children are at risk of exposure to over 15,000 high-production-volume synthetic chemicals, nearly all of them developed in the past 50 years. These chemicals are used widely in consumer products and are dispersed in the environment. More than half are untested for toxicity. Children appear uniquely vulnerable to chemical toxicants because of their disproportionately heavy exposures and their inherent biological susceptibility. To prevent disease of environmental origin in America's children, the Children's Environmental Health Network (CEHN) calls for a comprehensive, national, child-centered agenda. This agenda must recognize children's vulnerabilities to environmental toxicants. It must encompass a) a new prevention-oriented research focus; b) a new child-centered paradigm for health risk assessment and policy formulation; and c) a campaign to educate the public, health professionals, and policy makers that environmental disease is caused by preventable exposures and is therefore avoidable. To anchor the agenda, CEHN calls for long-term, stable investment and for creation of a national network of pediatric environmental health research and prevention centers.
Asunto(s)
Protección a la Infancia , Exposición a Riesgos Ambientales/prevención & control , Salud Ambiental/normas , Promoción de la Salud/métodos , Niño , Protección a la Infancia/estadística & datos numéricos , Exposición a Riesgos Ambientales/efectos adversos , Exposición a Riesgos Ambientales/estadística & datos numéricos , Política de Salud , Transición de la Salud , Humanos , Prevención Primaria/métodos , Investigación/tendencias , Estados UnidosRESUMEN
Functional homeostasis is the ability of an individual to withstand illness without loss of function. We investigate whether the level of functional homeostasis predicts adverse outcomes in the 6 months posthospital discharge in older men and women. A prospective cohort study was conducted in an acute care geriatric inpatient unit of a university hospital. Subjects included a consecutive series of patients admitted to the unit. The Functional Independence Measure (FIM) instrument was used to assess patients at four time points: preillness, hospital admission, hospital discharge, and 6 months postdischarge. Of the 122 subjects available for analysis, 64 (52%) experienced a decline in functional level from preillness to hospital discharge and were defined as having poor functional homeostasis, whereas 58 (48%) experienced no change or an increase in functional status and were defined as having good functional homeostasis. Those with poor functional homeostasis had a higher 6-month readmission rate to the hospital (59.4 v 39.7%; P=0.03) and a higher rate of any adverse outcome (78.1 v 50%; P=0.001) than those with good functional homeostasis. In logistic regressive analyses, functional homeostasis remained a significant and powerful predictor of adverse outcomes independent of actual level of function at discharge, age, gender, living status, and other factors that might influence outcomes. Change in functional status associated with an acute illness is an independent predictor of adverse outcomes and, in this study, a better predictor than actual level of function at discharge. Functional homeostasis is one approach to the quantification of the important but elusive concept of frailty in the elderly.