RESUMO
Relict species, like coelacanth, gingko, tuatara, are the remnants of formerly more ecologically and taxonomically diverse lineages. It raises the questions of why they are currently species-poor, have restrained ecology, and are often vulnerable to extinction. Estimating heterozygosity level and demographic history can guide our understanding of the evolutionary history and conservation status of relict species. However, few studies have focused on relict invertebrates compared to vertebrates. We sequenced the genome of Baronia brevicornis (Lepidoptera: Papilionidae), which is an endangered species, the sister species of all swallowtail butterflies, and is the oldest lineage of all extant butterflies. From a dried specimen, we were able to generate both long-read and short-read data and assembled a genome of 406â Mb for Baronia. We found a fairly high level of heterozygosity (0.58%) compared to other swallowtail butterflies, which contrasts with its endangered and relict status. Taking into account the high ratio of recombination over mutation, demographic analyses indicated a sharp decline of the effective population size initiated in the last million years. Moreover, the Baronia genome was used to study genome size variation in Papilionidae. Genome sizes are mostly explained by transposable elements activities, suggesting that large genomes appear to be a derived feature in swallowtail butterflies as transposable elements activity is recent and involves different transposable elements classes among species. This first Baronia genome provides a resource for assisting conservation in a flagship and relict insect species as well as for understanding swallowtail genome evolution.
Assuntos
Borboletas , Animais , Borboletas/genética , Tamanho do Genoma , Filogenia , Elementos de DNA Transponíveis/genética , Genômica , DemografiaRESUMO
In comparison with other molluscs and bilaterians, the genomes of coleoid cephalopods (squid, cuttlefish, and octopus) sequenced so far show remarkably different genomic organization that presumably marked the early evolution of this taxon. The main driver behind this genomic rearrangement remains unclear. About half of the genome content in coleoids is known to consist of repeat elements; since selfish DNA is one of the powerful drivers of genome evolution, its pervasiveness could be intertwined with the emergence of cephalopod-specific genomic signatures and could have played an important role in the reorganization of the cephalopod genome architecture. However, due to abundant species-specific repeat expansions, it has not been possible so far to identify the ancient shared set of repeats associated with coleoid divergence. By means of an extensive repeat element re-evaluation and annotation combined with network sequence divergence approaches, we are able to identify and characterize the ancient repeat complement shared by at least four coleoid cephalopod species. Surprisingly, instead of the most abundant elements present in extant genomes, lower-copy-number DNA and retroelements were most associated with ancient coleoid radiation. Furthermore, evolutionary analysis of some of the most abundant families shared in Octopus bimaculoides and Euprymna scolopes disclosed within-family patterns of large species-specific expansions while also identifying a smaller shared expansion in the coleoid ancestor. Our study thus reveals the apomorphic nature of retroelement expansion in octopus and a conserved complement composed of several DNA element types and fewer LINE families.
RESUMO
Se presentan los resultados bacteriológicos obtenidos en examen de 759 catéteres colocados a 500 pacientes quirúrgicos con el fin de administrar nutrición parenteral. Se encontró que a pesar de que 318 pacientes tenían un foco séptico, sólo en 10 (1,3%) se puede explicar la sepsis como punto de partida del cateter. Con técnica de colocación y cuidados rigurosos de asepsia, se puede obtener la incidencia baja de sepsis por cateter
Assuntos
Animais , Masculino , Infecção Hospitalar , Nutrição ParenteralRESUMO
Se presenta la experiencia en el tratamiento y manejo de 41 fístulas enterocutáneas por la Unidad de Soporte Nutricional del Hospital Universitario de Caracas, durante 1985-1987. Con el enfoque multidisciplinario se obtuvo 80.4% de cierre de las fístulas. La sepsis no controlada sigue siendo la mayor causa de fracasos y muertes con 19.5%. Aún así es una mejoría dramática de lo que era la incidencia de muerte antes de la aparición del Soporte Nutricional