Evaluation of reference-based two-color methods for measurement of gene expression ratios using spotted cDNA microarrays

BACKGROUND: Spotted cDNA microarrays generally employ co-hybridization of fluorescently-labeled RNA targets to produce gene expression ratios for subsequent analysis. Direct comparison of two RNA samples in the same microarray provides the highest level of accuracy; however, due to the number of combinatorial pair-wise comparisons, the direct method is impractical for studies including large number of individual samples (e.g., tumor classification studies). For such studies, indirect comparisons using a common reference standard have been the preferred method. Here we evaluated the precision and accuracy of reconstructed ratios from three indirect methods relative to ratios obtained from direct hybridizations, herein considered as the gold-standard. RESULTS: We performed hybridizations using a fixed amount of Cy3-labeled reference oligonucleotide (RefOligo) against distinct Cy5-labeled targets from prostate, breast and kidney tumor samples. Reconstructed ratios between all tissue pairs were derived from ratios between each tissue sample and RefOligo. Reconstructed ratios were compared to (i) ratios obtained in parallel from direct pair-wise hybridizations of tissue samples, and to (ii) reconstructed ratios derived from hybridization of each tissue against a reference RNA pool (RefPool). To evaluate the effect of the external references, reconstructed ratios were also calculated directly from intensity values of single-channel (One-Color) measurements derived from tissue sample data collected in the RefOligo experiments. We show that the average coefficient of variation of ratios between intra- and inter-slide replicates derived from RefOligo, RefPool and One-Color were similar and 2 to 4-fold higher than ratios obtained in direct hybridizations. Correlation coefficients calculated for all three tissue comparisons were also similar. In addition, the performance of all indirect methods in terms of their robustness to identify genes deemed as differentially expressed based on direct hybridizations, as well as false-positive and false-negative rates, were found to be comparable. CONCLUSION: RefOligo produces ratios as precise and accurate as ratios reconstructed from a RNA pool, thus representing a reliable alternative in reference-based hybridization experiments. In addition, One-Color measurements alone can reconstruct expression ratios without loss in precision or accuracy. We conclude that both methods are adequate options in large-scale projects where the amount of a common reference RNA pool is usually restrictive

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Low handgrip strength is associated with worse functional outcomes in long COVID

Abstract The diagnosis of long COVID is troublesome, even when functional limitations are present. Dynapenia is the loss of muscle strength and power production that is not caused by neurologic or muscular diseases, being mostly associated with changes in neurologic function and/or the intrinsic force-generating properties of skeletal muscle, which altogether, may partially explain the limitations seen in long COVID. This study aimed to identify the distribution and possible associations of dynapenia with functional assessments in patients with long COVID. A total of 113 patients with COVID-19 were evaluated by functional assessment 120 days post-acute severe disease. Body composition, respiratory muscle strength, spirometry, six-minute walk test (6MWT, meters), and hand-grip strength (HGS, Kilogram-force) were assessed. Dynapenia was defined as HGS < 30 Kgf (men), and < 20 Kgf (women). Twenty-five (22%) participants were dynapenic, presenting lower muscle mass (p < 0.001), worse forced expiratory volume in the first second (FEV1) (p = 0.0001), lower forced vital capacity (p < 0.001), and inspiratory (p = 0.007) and expiratory (p = 0.002) peek pressures, as well as worse 6MWT performance (p < 0.001). Dynapenia, independently of age, was associated with worse FEV1, maximal expiratory pressure (MEP), and 6MWT, (p < 0.001) outcomes. Patients with dynapenia had higher intensive care unit (ICU) admission rates (p = 0.01) and need for invasive mechanical ventilation (p = 0.007) during hospitalization. The HGS is a simple, reliable, and low-cost measurement that can be performed in outpatient clinics in low- and middle-income countries. Thus, HGS may be used as a proxy indicator of functional impairment in this population

Origin and dynamics of admixture in Brazilians and its effect on the pattern of deleterious mutations

Submitted by Nuzia Santos ([email protected]) on 2016-02-19T13:11:37Z No. of bitstreams: 1 Origin and dynamics of admixture in Brazilians and its effect on the pattern of deleterious mutations..pdf: 501572 bytes, checksum: 45f5ed2fc0a7c2cb73e047a75457edae (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2016-02-19T13:37:09Z (GMT) No. of bitstreams: 1 Origin and dynamics of admixture in Brazilians and its effect on the pattern of deleterious mutations..pdf: 501572 bytes, checksum: 45f5ed2fc0a7c2cb73e047a75457edae (MD5)Made available in DSpace on 2016-02-19T13:37:09Z (GMT). No. of bitstreams: 1 Origin and dynamics of admixture in Brazilians and its effect on the pattern of deleterious mutations..pdf: 501572 bytes, checksum: 45f5ed2fc0a7c2cb73e047a75457edae (MD5) Previous issue date: 2015Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade de São Paulo. Instituto do Coração. São Paulo, SP, BrasilUniversidade Federal de Pelotas. Programa de Pós-Graduação em Epidemiologia. Pelotas, RS, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade de São Paulo. Instituto do Coração. São Paulo, SP, BrasilUniversidade de São Paulo. Instituto do Coração. São Paulo, SP, BrasilUniversidade Federal da Bahia. Instituto de Matemática. Departamento de Estatística. Salvador, Bahia, BrasilUniversidade Federal da Bahia. Instituto de Ciências da Saúde. Departamento de Ciências da Biointeração. Salvador, Bahia, BrasilUniversidade Federal da Bahia. Instituto de Saúde Coletiva. Salvador, BA, BrasilUniversidade Federal da Bahia. Instituto de Saúde Coletiva. Salvador, BA, BrasilUniversity of Leicester. Department of Genetics. Leicester, United KingdomWashington University School of Medicine. Department of Molecular Microbiology. St. Louis, MO/University of California. Department of Medicine. San Diego, CAAsociación Benéfica Proyectos en Informática, Salud, Medicina y Agricultura. Biomedical Research Unit. Lima, PeruUniversidade Federal de Santa Catarina. Embriologia e Genética. Departamento de Biologia Celular. Florianópolis, SC, BrasilUniversidade Federal de Minas Gerais. Departamento de Estatística. Belo Horizonte, MG, BrasilUniversità di Ferrara. Dipartimento di Scienze della Vita e Biotecnologie. Ferrara, ItalyJohns Hopkins University. International Health. Bloomberg School of Public Health. Baltimore, MD, USA/Universidade Peruana Cayetano Heredia. Laboratorio de Investigación de Enfermedades Infecciosas. Lima, PeruUniversity of Toronto. Center for Addiction and Mental Health. Department of Psychiatry and Neuroscience Section. Toronto, ON, CanadaUniversidade Federal de Santa Catarina. Embriologia e Genética. Departamento de Biologia Celular. Florianópolis, SC, BrasilUniversidade Federal de Santa Catarina. Embriologia e Genética. Departamento de Biologia Celular. Florianópolis, SC, BrasilInnsbruck Medical University. Molecular and Clinical Pharmacology. Department of Medical Genetics. Division of Genetic Epidemiology. Innsbruck, AustriaFrederick National Laboratory for Cancer Research. Leidos Biomedical Research. Cancer Genomics Research Laboratory. Frederick, MDLondon School of Hygiene and Tropical Medicine. Faculty of Epidemiology. Department of Infectious Disease Epidemiology. London, United KingdomUniversidade Federal da Bahia. Instituto de Saúde Coletiva. Salvador, BA, BrasilFundação Oswaldo Cruz. Instituto de Pesquisa Rene Rachou. Belo Horizonte, MG, BrasilUniversidade de São Paulo. Instituto do Coração. São Paulo, SP, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, BrasilUniversidade Federal da Bahia. Instituto de Ciências da Saúde. Departamento de Ciências da Biointeração. Salvador, BA, Brasil.Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Laboratório de Computação Científica. Belo Horizonte, MG, Brasil.Universidade Federal da Bahia. Instituto de Saúde Coletiva. Salvador, BA, Brasil.Fundação Oswaldo Cruz. Instituto de Pesquisa Rene Rachou. Belo Horizonte, MG, Brasil.Universidade Federal de Pelotas. Programa de Pós-Graduação em Epidemiologia. Pelotas, RS, Brasil.Universidade Federal de Rio Grande do Sul. Centro Nacional de Supercomputação. Porto Alegre, RS, Brasil.Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto de Pesquisa Rene Rachou. Grupo de Genômica e Biologia Computacional. Belo Horizonte, MG, Brasil.Universidade Federal de Pelotas. Programa de Pós-Graduação em Epidemiologia. Pelotas, RS, Brasil.Fundação Oswaldo Cruz. Instituto de Pesquisa Rene Rachou. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Instituto de Pesquisa Rene Rachou. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Laboratório de Computação Científica. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, Brasil.Universidade Federal da Bahia. Instituto de Saúde Coletiva. Salvador, BA, Brasil.Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Biologia Geral. Belo Horizonte, MG, Brasil.While South Americans are underrepresented in human genomic diversity studies, Brazil has been a classical model for population genetics studies on admixture.We present the results of the EPIGEN Brazil Initiative, the most comprehensive up-to-date genomic analysis of any Latin-American population. A population-based genomewide analysis of 6,487 individuals was performed in the context of worldwide genomic diversity to elucidate how ancestry, kinship, and inbreeding interact in three populations with different histories from the Northeast (African ancestry: 50%), Southeast, and South (both with European ancestry >70%) of Brazil. We showed that ancestry-positive assortative mating permeated Brazilian history. We traced European ancestry in the Southeast/South to a wider European/Middle Eastern region with respect to the Northeast, where ancestry seems restricted to Iberia. By developing an approximate Bayesian computation framework, we infer more recent European immigration to the Southeast/South than to the Northeast. Also, the observed low Native-American ancestry (6–8%) was mostly introduced in different regions of Brazil soon after the European Conquest. We broadened our understanding of the African diaspora, the major destination of which was Brazil, by revealing that Brazilians display two within-Africa ancestry components: one associated with non-Bantu/western Africans (more evident in the Northeast and African Americans) and one associated with Bantu/eastern Africans (more present in the Southeast/South). Furthermore, the whole-genome analysis of 30 individuals (42-fold deep coverage) shows that continental admixture rather than local post-Columbian history is the main and complex determinant of the individual amount of deleterious genotypes

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved