Comparative analysis of repetitive DNA in dysploid and non-dysploid Phaseolus beans.

Structural karyotype changes result from ectopic recombination events frequently associated with repetitive DNA. Although most Phaseolus species present relatively stable karyotypes with 2n = 22 chromosomes, the karyotypes of species of the Leptostachyus group show high rates of structural rearrangements, including a nested chromosome fusion that led to the dysploid chromosome number of the group (2n = 20). We examined the roles of repetitive landscapes in the rearrangements of species of the Leptostachyus group using genome-skimming data to characterize the repeatome in a range of Phaseolus species and compared them to species of that group (P. leptostachyus and P. macvaughii). LTR retrotransposons, especially the Ty3/gypsy lineage Chromovirus, were the most abundant elements in the genomes. Differences in the abundance of Tekay, Retand, and SIRE elements between P. macvaughii and P. leptostachyus were reflected in their total amounts of Ty3/gypsy and Ty1/copia. The satellite DNA fraction was the most divergent among the species, varying both in abundance and distribution, even between P. leptostachyus and P. macvaughii. The rapid turnover of repeats in the Leptostachyus group may be associated with the several rearrangements observed.

Cytogenetic characterization and karyotype evolution in six Macroptilium species (Leguminosae).

Macroptilium (Benth.) Urb. is a neotropical legume genus from the subtribe Phaseolinae. The investigated species present a stable chromosome number (2n = 22), but differ in their karyotype formulae, suggesting the presence of chromosome rearrangements. In this work, we comparatively analysed the karyotypes of six species (Macroptilium atropurpureum, Macroptilium bracteatum, Macroptilium erythroloma, Macroptilium gracile, Macroptilium lathyroides, and Macroptilium martii) from the two main clades that form the genus. Heterochromatin distribution was investigated with chromomycin A3 (CMA)/4',6-diamidino-2-phenylindole (DAPI) staining and fluorescent in situ hybridization was used to localize the 5S and 35S ribosomal DNA (rDNA) sites. Single copy bacterial artificial chromosomes (BACs) previously mapped in the related genera Phaseolus L. and Vigna Savi were used to establish chromosome orthologies and to investigate possible rearrangements among species. CMA+/DAPI- bands were observed, mostly associated with rDNA sites. Additional weak, pericentromeric bands were observed on several chromosomes. Although karyotypes were similar, species could be differentiated mainly by the number and position of the 5S and 35S rDNA sites. BAC markers demonstrated conserved synteny of the main rDNA sites on orthologous chromosomes 6 and 10, as previously observed for Phaseolus and Vigna. The karyotypes of the six species could be differentiated, shedding light on its karyotype evolution.

Multiple and independent rearrangements revealed by comparative cytogenetic mapping in the dysploid Leptostachyus group (Phaseolus L., Leguminosae).

Polyploidy and dysploidy have been reported as the main events in karyotype evolution of plants. In the genus Phaseolus L. (2n = 22), a small monophyletic group of three species, the Leptostachyus group, presents a dysploid karyotype with 2n = 20. It was shown in Phaseolus leptostachyus that the dysploidy was caused by a nested chromosome fusion (NCF) accompanied by several translocations, suggesting a high rate of karyotype evolution in the group. To verify if this karyotype restructuring was a single event or occurred progressively during the evolution of this group, we analysed P. macvaughii, sister to Phaseolus micranthus + P. leptostachyus. Twenty-four genomic clones of P. vulgaris previously mapped on P. leptostachyus, in addition to the 5S and 35S rDNA probes, were used for fluorescence in situ hybridization. Only a single rearrangement was common to the two species: the nested chromosome fusion (NCF) involving chromosomes 10 and 11. The translocation of chromosome 2 is not the same found in P. leptostachyus, and pericentric inversions in chromosomed 3 and 4 were exclusive of P. macvaughii. The other rearrangements observed in P. leptostachyus were not shared with this species, suggesting that they occurred after the separation of these lineages. The presence of private rearrangements indicates a progressive accumulation of karyotype changes in the Leptostachyus group instead of an instant genome-wide repatterning.

Allopolyploid origin and genome differentiation of the parasitic species Cuscuta veatchii (Convolvulaceae) revealed by genomic in situ hybridization.

Interspecific hybridization and genome duplication to form allopolyploids are major evolutionary events in angiosperms. In the parasitic genus Cuscuta (Convolvulaceae), molecular data suggested the existence of species of hybrid origin. One of them, C. veatchii, has been proposed as a hybrid between C. denticulata and C. nevadensis, both included in sect. Denticulatae. To test this hypothesis, a cytogenetic analysis was performed with CMA/DAPI staining and fluorescent in situ hybridization using 5S and 35S rDNA and genomic probes. Chromosomes of C. denticulata were small with a well-defined centromeric region, whereas C. nevadensis had larger, densely stained chromosomes, and less CMA+ heterochromatic bands. Cuscuta veatchii had 2n = 60 chromosomes, about 30 of them similar to those of C. denticulata and the remaining to C. nevadensis. GISH analysis confirmed the presence of both subgenomes in the allotetraploid C. veatchii. However, the number of rDNA sites and the haploid karyotype length in C. veatchii were not additive. The diploid parentals had already diverged in their chromosomes structure, whereas the reduction in the number of rDNA sites more probably occurred after hybridization. As phylogenetic data suggested a recent divergence of the progenitors, these species should have a high rate of karyotype evolution.

Speeding up chromosome evolution in Phaseolus: multiple rearrangements associated with a one-step descending dysploidy.

The genus Phaseolus L. has been subject of extensive cytogenetic studies due to its global economic importance. It is considered karyotypically stable, with most of its ca. 75 species having 2n = 22 chromosomes, and only three species (Phaseolus leptostachyus, Phaseolus macvaughii, and Phaseolus micranthus), which form the Leptostachyus clade, having 2n = 20. To test whether a simple chromosomal fusion was the cause of this descending dysploidy, mitotic chromosomes of P. leptostachyus (2n = 20) were comparatively mapped by fluorescent in situ hybridization (FISH) using bacterial artificial chromosomes (BACs) and ribosomal DNA (rDNA) probes. Our results corroborated the conservation of the 5S and 45S rDNA sites on ancestral chromosomes 10 and 6, respectively. The reduction from x = 11 to x = 10 was the result of the insertion of chromosome 10 into the centromeric region of chromosome 11, supporting a nested chromosome fusion (NCF) as the main cause of this dysploidy. Additionally, the terminal region of the long arm of chromosome 6 was translocated to this larger chromosome. Surprisingly, the NCF was accompanied by several additional translocations and inversions previously unknown for the genus, suggesting that the dysploidy may have been associated to a burst of genome reorganization in this otherwise stable, diploid plant genus.

COVID-19 in patients with obesity: clinicopathological features and immunological mechanisms associated with adverse clinical outcome / COVID-19 em pacientes com obesidade: características clínico-patológicas e mecanismos imunológicos associados a desfechos clínicos desfavoráveis / COVID-19 en pacientes con obesidad: características clínico-patológicas y mecanismos inmunológicos asociados con resultados clínicos adversos

Justificativa e Objetivos: A infecção pelo novo coronavírus (Sars-CoV-2), causador da COVID-19, ocorre de forma mais grave em pacientes que apresentam fatores de risco, entre os quais se destaca a obesidade, o que os torna mais suscetíveis à ventilação mecânica e à mortalidade. Neste contexto, este trabalho revisa a epidemiologia da obesidade e os possíveis mecanismos imunológicos que fazem dela um dos piores cenários clínicos para a COVID-19. Métodos: Este estudo é uma revisão bibliográfica narrativa de caráter exploratório em que, na coleta de dados, consideraram-se, entre as publicações científicas do tema estudado, artigos publicados nas bases eletrônicas PubMed e Biblioteca Virtual em Saúde (BVS) em inglês, espanhol e português, no período de junho de 2015 a junho de 2020. Os descritores adotados foram: "Sars-CoV-2", "Obesity", "COVID-19" e "Risk Factors". Conteúdo: A obesidade é uma pandemia e sua condição inflamatória crônica é fator de risco para diversas patologias, incluindo pior desfecho em infecções respiratórias virais. A análise imunológica desse estado e seu respectivo papel na imunopatologia do Sars-CoV-2 revelam uma resposta pró-inflamatória desregulada, com acentuado aumento de diversas citocinas, como TNF-α, IL-6 e IL-1ß. Tais mecanismos geram um grande fluxo de citocinas, com consequente piora da resposta imune à infecção pelo novo coronavírus, o que tem sido associado à forma grave da doença. Conclusão: A obesidade é um fator de risco global relevante para a infecção do Sars-CoV-2, pois desregula a resposta imune pró-inflamatória, causando pior desfecho clínico, o que merece atenção especial por parte das políticas de combate à pandemia.(AU)

Background and objectives: The infection with the new coronavirus (SARS-CoV-2), which causes COVID-19, is more severe in patients with risk factors, increasing these patients' susceptibility to mechanical ventilation and mortality, among them, obesity stands out. This study reviews the epidemiology of obesity and the possible immunological mechanisms that make it one of the worst clinical scenarios in COVID-19. Methods: This study consists of an exploratory narrative review. Data collection considered articles in English, Spanish and Portuguese, published between June 2015 and June 2020, in the electronic databases PubMed and Virtual Health Library (BVS). The indexing terms used were "SARS-CoV-2," "Obesity," "COVID-19," "Risk Factors." Content: Obesity is a pandemic and its chronic inflammatory condition is a risk factor for several pathologies, including worse outcome in viral respiratory infections. The immunological analysis of this risk factor and its role in the immunopathology of SARS-CoV-2 reveals a deregulated pro-inflammatory response, with a marked increase in several cytokines, such as TNF-α, IL-6 and IL-1ß. Such mechanisms result in a cytokine storm, with a consequent deterioration of the immune response for the new coronavirus infection that have been linked to the severe form of disease. Conclusion: Obesity is a global relevant risk factor for SARS-CoV-2 infection because it disrupts the pro-inflammatory immune response, resulting in a worse clinical outcome, which deserves special attention in the fight against the pandemic.(AU)

Justificación y Objetivos: La infección por el SARS-CoV-2, causante de la COVID-19, se presenta de forma más grave en pacientes portadores de factores de riesgo, entre los cuales se destaca la obesidad, que los predispone a la ventilación mecánica y la mortalidad. En este contexto, el presente trabajo revisa la epidemiología de la obesidad y los posibles mecanismos inmunológicos que asocian la obesidad como uno de los peores escenarios clínicos en la COVID-19. Métodos: Este estudio consiste en una revisión bibliográfica narrativa de carácter exploratorio. En la recolección de datos, se consideraron, entre las publicaciones científicas del tema estudiado, artículos publicados en los idiomas inglés, español y portugués en el periodo de junio de 2015 a junio de 2020, en las bases electrónicas PubMed y Biblioteca Virtual de Salud (BVS). Los descriptores adoptados fueron: "SARS-CoV-2", "Obesity", "COVID-19", "Risk Factors". Contenido: La obesidad es una pandemia y su condición inflamatoria crónica es un factor de riesgo para diversas patologías, que incluye un peor desenlace en infecciones respiratorias virales. El análisis inmunológico de ese estado y su respectivo papel en la inmunopatología del SARS-CoV-2 revela una respuesta proinflamatoria desregulada, con acentuado aumento de diversas citocinas, como TNF-α, IL-6 e IL-1ß. Tal mecanismo tiene como resultado un gran flujo de citocinas, con el consecuente empeoramiento de la respuesta inmune frente a la infección por el nuevo coronavirus, lo que se ha relacionado con la forma grave de la enfermedad. Conclusión: La obesidad configura un factor de riesgo relevante global para la infección del SARS-CoV-2 por proporcionar la desregulación de la respuesta inmune proinflamatoria que resulta en un peor desenlace clínico y merece una atención especial por parte de las políticas para combatir la pandemia.(AU)