24 research outputs found

    Transcription and Chromatin Organization of a Housekeeping Gene Cluster Containing an Integrated β-Globin Locus Control Region

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    The activity of locus control regions (LCR) has been correlated with chromatin decondensation, spreading of active chromatin marks, locus repositioning away from its chromosome territory (CT), increased association with transcription factories, and long-range interactions via chromatin looping. To investigate the relative importance of these events in the regulation of gene expression, we targeted the human β-globin LCR in two opposite orientations to a gene-dense region in the mouse genome containing mostly housekeeping genes. We found that each oppositely oriented LCR influenced gene expression on both sides of the integration site and over a maximum distance of 150 kilobases. A subset of genes was transcriptionally enhanced, some of which in an LCR orientation-dependent manner. The locus resides mostly at the edge of its CT and integration of the LCR in either orientation caused a more frequent positioning of the locus away from its CT. Locus association with transcription factories increased moderately, both for loci at the edge and outside of the CT. These results show that nuclear repositioning is not sufficient to increase transcription of any given gene in this region. We identified long-range interactions between the LCR and two upregulated genes and propose that LCR-gene contacts via chromatin looping determine which genes are transcriptionally enhanced

    Generalized Klein-Nishina formula

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    Cirugía de pterigión con autoinjerto de limbo conjuntival en una clínica oftalmológica de Villavicencio, Colombia

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    4 páginasObjective: To describe results of pterygium surgery at Clínica de Cirurgía Ocular Villavicencio, in Meta, Colombia. Methods: A retrospective analysis of pterygium surgeries performed between January 2017 and December 2019. Results: Approximately 1,200 records were reviewed, and 1,200 procedures included. The most frequent complications were corneal Dellen, pterygium recurrence, graft retraction and pyogenic granuloma (7.5%, 2.5%, 3% and 0.75% respectively). These were identified within the first 6 months of surgery. Conclusion: Pterygium surgery using conjunctival autografts is an effective technique, with low recurrence rates and very few complications.Objetivo: Describir los resultados de la cirugía de pterigión en la Clínica de Cirurgia Ocular Villavicencio, Meta, Colombia. Métodos: Un análisis retrospectivo de las cirugías de pterigión realizadas entre enero de 2017 y diciembre de 2019. Resultados: Se revisaron aproximadamente 1200 registros y se incluyeron 1200 procedimientos. Las complicaciones más frecuentes fueron Dellen corneal, recurrencia del pterigión, retracción del injerto y granuloma piógeno (7,5%, 2,5%, 3% y 0,75% respectivamente). Estos fueron identificados dentro de los primeros 6 meses de la cirugía. Conclusión: La cirugía de pterigión mediante autoinjertos conjuntivales es una técnica eficaz, con bajas tasas de recurrencia y muy pocas complicaciones

    Phenotypic evaluation of interspecific recombinant inbred lines (RILs) of Phaseolus species for their resistance to aluminum and tolerance to aluminum-toxic acid soil under greenhouse conditions

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    Aluminium (Al) toxicity limits common bean productivity in acid soil regions of the tropics. To improve Al resistance of common bean, Al-sensitive Phaseolus vulgaris (SER16) was crossed to Alresistant P. coccineus (G35346-3Q) to create 94 F5:6 recombinant inbred lines (RILs) of the pedigree SER16 9 (SER16 9 G35346-3Q). RILs were characterized for resistance to Al in a hydroponic system with 0 and 20 lM Al in solution, and for shoot and root growth response to Al-toxic infertile acid soil in 75 cm long soil cylinder system using an oxisol of low Al- (12.5%; pH 4.6; fertilized) and high Al-saturation (77%; pH 4.1; unfertilized). G35346-3Q increased its taproot elongation rate by 3.5% between 24 and 48 h under 20 lM Al in solution, while the best RIL, Andean genotype ICA Quimbaya, and sensitive genotype VAX1 expressed reductions of 2.6, 12.5, and 69.5%, respectively. In the acid soil treatment the correlation between leaf area and total root length was highly significant under high Al saturation (r = 0.70***). Genotypes that were Al resistant in the hydroponic system were not necessarily tolerant to Al-toxic acid soil conditions based on shoot and root growth responses. Phenotypic evaluation using both systems allows the identification of genotypes with Al resistance combined with acid soil adaptation. Two genotypes (ALB88 and ALB91) emerged as lines with multiple traits. Results suggest that inheritance of Al resistance and acid soil tolerance in G35346-3Q is complex. Results from this work will be useful for identification of molecular markers for Al resistance in Phaseolus species and to improve acid soil adaptation in common bean

    Shorebird monitoring in Australia: a successful long-term collaboration between citizen scientists, governments and researchers

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    From its beginnings in the 1960s, shorebird monitoring in Australia has grown into a national effort generating high quality information about a large group of migratory and non-migratory waterbirds. Robust information on trends, combined with detailed demographic monitoring and studies of bird movements, has revealed drastic declines, particularly among the migratory species. From the start, monitoring focused on a broad ecological assemblage meaning that the reasons for these declines could be understood through comparative analyses in partnership with researchers. Threats to migratory and non-migratory species, and the actions necessary for their recovery, are increasingly well resolved. Shorebird monitoring in Australia has been a largely decentralised, volunteer-driven effort, funded from both public and private sources. It exemplifies how the public and private sectors can work together to achieve long term monitoring
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