Conversion of DNA Sequences: From a Transposable Element to a Tandem Repeat or to a Gene.

Eukaryotic genomes are rich in repetitive DNA sequences grouped in two classes regarding their genomic organization: tandem repeats and dispersed repeats. In tandem repeats, copies of a short DNA sequence are positioned one after another within the genome, while in dispersed repeats, these copies are randomly distributed. In this review we provide evidence that both tandem and dispersed repeats can have a similar organization, which leads us to suggest an update to their classification based on the sequence features, concretely regarding the presence or absence of retrotransposons/transposon specific domains. In addition, we analyze several studies that show that a repetitive element can be remodeled into repetitive non-coding or coding sequences, suggesting (1) an evolutionary relationship among DNA sequences, and (2) that the evolution of the genomes involved frequent repetitive sequence reshuffling, a process that we have designated as a "DNA remodeling mechanism". The alternative classification of the repetitive DNA sequences here proposed will provide a novel theoretical framework that recognizes the importance of DNA remodeling for the evolution and plasticity of eukaryotic genomes.

A novel satellite DNA sequence in the Peromyscus genome (PMSat): Evolution via copy number fluctuation.

Satellite DNAs (satDNA) are tandemly arrayed repeated sequences largely present in eukaryotic genomes, which play important roles in genome evolution and function, and therefore, their analysis is vital. Here, we describe the isolation of a novel satellite DNA family (PMSat) from the rodent Peromyscus eremicus (Cricetidae, Rodentia), which is located in pericentromeric regions and exhibits a typical satellite DNA genome organization. Orthologous PMSat sequences were isolated and characterized from three species belonging to Cricetidae: Cricetus cricetus, Phodopus sungorus and Microtus arvalis. In these species, PMSat is highly conserved, with the absence of fixed species-specific mutations. Strikingly, different numbers of copies of this sequence were found among the species, suggesting evolution by copy number fluctuation. Repeat units of PMSat were also found in the Peromyscus maniculatus bairdii BioProject, but our results suggest that these repeat units are from genome regions outside the pericentromere. The remarkably high evolutionary sequence conservation along with the preservation of a few numbers of copies of this sequence in the analyzed genomes may suggest functional significance but a different sequence nature/organization. Our data highlight that repeats are difficult to analyze due to the limited tools available to dissect genomes and the fact that assemblies do not cover regions of constitutive heterochromatin.

A High-Resolution Comparative Chromosome Map of Cricetus cricetus and Peromyscus eremicus Reveals the Involvement of Constitutive Heterochromatin in Breakpoint Regions.

Compared to humans and other mammals, rodent genomes, specifically Muroidea species, underwent intense chromosome reshuffling in which many complex structural rearrangements occurred. This fact makes them preferential animal models for studying the process of karyotype evolution. Here, we present the first combined chromosome comparative maps between 2 Cricetidae species, Cricetus cricetus and Peromyscus eremicus, and the index species Mus musculus and Rattus norvegicus. Comparative chromosome painting was done using mouse and rat paint probes together with in silico analysis from the Ensembl genome browser database. Hereby, evolutionary events (inter- and intrachromosomal rearrangements) that occurred in C. cricetus and P. eremicus since the putative ancestral Muroidea genome could be inferred, and evolutionary breakpoint regions could be detected. A colocalization of constitutive heterochromatin and evolutionary breakpoint regions in each genome was observed. Our results suggest the involvement of constitutive heterochromatin in karyotype restructuring of these species, despite the different levels of conservation of the C. cricetus (derivative) and P. eremicus (conserved) genomes.

Conhecimento de gestantes e lactantes sobre aleitamento materno exclusivo / Pregnant and lactating women?s knowledge of exclusive breastfeeding / Conocimiento de embarazadas y lactantes sobre lactancia materna exclusiva

Identificar o que as gestantes e lactantes afirmam sobre o que é aleitamento materno exclusivo, qual sua duração e quais seus benefícios para a mãe e o bebê. Métodos:Estudo descritivo, com abordagem quantitativa, realizado em 2011, em um Centro de Saúde da Família, em Fortaleza-CE. Foram avaliadas as seguintes variáveis: características socioeconômicas, conhecimento e atitudes sobre aleitamento materno e seus benefícios para a mãe e o bebê. A coleta ocorreu por meio de um questionário e foi constituída por uma amostra não probabilística de 45 mulheres, com análise estatística descritiva simples, através de proporção. Resultados: Das entrevistadas, 40 (88,9%) estavam gestantes e 5(11,1%), amamentando. A média das idades foi de 24 anos. Com relação às características socioeconômicas, 12 (30%) afirmaram ser empregadas domésticas, 9 (22,5%), do lar e 6 (15%), desempregadas. Quanto à definição de amamentação exclusiva, 25 (55,6%) responderam que ela consiste apenas no leite materno, 5 (11,1/%), em leite materno, água e chá, e 12 (26,7%) não conheciam o significado do termo. Sobre os benefícios, 16 (35,7%) afirmaram o aumento do vínculo com o filho. Conclusão: Observou-se que as mães avaliadas apresentaram conhecimento sobre definição, tempo e benefícios do aleitamento materno exclusivo, no entanto, apresentam fatores que favorecem o desmame precoce...

To identify what pregnant and lactating women say about what is exclusive breastfeeding, its duration and benefits for moms and babies. Methods: This is a quantitative,descriptive study that took place in 2011 at a Family Health Center in Fortaleza-CE. The following variables were analyzed: socioeconomic characteristics, knowledge and attitude regarding breastfeeding and its benefits for the mom and baby. Data collection was performed using a questionnaire and consisted of a non-probability sample of 45 women with simple descriptive statistical analysis using proportion. Results: In all, 40 (88.9%) respondents were pregnant and 5 (11.1%) were breastfeeding. Mean age was 24 years. Regarding socioeconomic characteristics, 12 (30%) women said they were housemaids, 9 (22.5%) were housewives and 6 (15%) were unemployed. Concerning the definition of exclusive breastfeeding, 25 (55.6%) women considered breast milk as the only form of breastfeeding, five (11.1%) respondents considered breast milk, water and tea and 12 (26.7%) women did not know the meaning of the term. Considering the benefits, 16 (35.7%) women reported the strengthening of the bond with the child. Conclusion: It was observed that the assessed moms had knowledge of the definition, duration and benefits of exclusive breastfeeding; however, they presented some factors that contributed to early weaning...

Identificar qué las embarazadas y lactantes apuntan como lactancia materna exclusiva y su duración y cuales SUS beneficios para la madre y el bebé. Métodos: Estudio descriptivo con abordaje cuantitativo realizado en 2011en un Centro de Salud de la Familia en Fortaleza-CE. Fueron evaluadas la siguientes variables: características socio-económicas, conocimiento y actitudes sobre lactancia materna y sus beneficios para La madre y el bebé. La recogida de datos ocurrió a través de um cuestionario y se constituyó de una muestra no probabilística de 45 mujeres, con análisis estadístico descriptivo simple a través de proporción. Resultados: De las entrevistadas, 40 (88,9%) estaban embarazadas y cinco (11,1%) estaban amamantando. La media de edad fue de 24 años. Sobre las características socio-económicas, doce (30%) afirmaron ser empleadas de hogar, 9 (22,5%) amas de casa y 6 (15%) estaban paradas. Sobre la definición de lactancia materna exclusiva 25 (55,6%) contestaron que es apenas la leche materna, 5 (11,1/%) en la leche materna, agua y té y 12 (26,7%) no conocen el significado del término. Cuanto a los beneficios de la madre, 16 (35,7%) afirmaron que era el aumento del vínculo con el hijo. Conclusión: Se observó que las madres evaluadas presentaron conocimiento de la definición, tiempo y beneficios de la lactancia materna exclusiva, sin embargo, ellas presentaron factores que favorecen el desmame precoz...