Tracking of microinjected DNA in live cells reveals the intracellular behavior and elimination of extrachromosomal genetic material

We here addressed the basic question, how does extrachromosomal DNA behave when it is placed in the nuclear or the cytoplasmic environment and how is it eliminated? To do this, we tracked microinjected DNA molecules in live cells. In the cytoplasm, the diffusion of microinjected DNA was inhibited in a size- and linearity-dependent manner, probably by the intermediate filament. This was followed by the rapid disappearance of the DNA fluorescent signal. In the nucleus, the diffusion was also dependent on the size of the molecule and was accompanied by the aggregation of the DNA. The aggregation may be due to a putative DNA-binding molecule, whose level is high during the G(1) phase. Surprisingly, the injected DNA could move across the nuclear membrane and appeared in the cytoplasm, which suggests the presence of a transport system. The intracytoplasmic behavior and the elimination of such DNA was obviously different from the DNA that was directly injected at the cytoplasm. The DNA remaining in the nucleus appeared to be stable and persisted in the nucleus or, after cell division, in the cytoplasm, for more than one cell cycle. These findings provide a novel and basic understanding of the behavior and elimination of a wide variety of extrachromosomal genetic material

ESTÁGIO SUPERVISIONADO EM SERVIÇO SOCIAL: reflexões críticas sobre a supervisão de campo

Este estudo tem como escopo apresentar um relato de experiência sobre o Estágio Curricular Obrigatório em Serviço Social realizado no Centro de Referência Especializado de Assistência Social – CREAS do município de Parintins/Amazonas. A investigação procura analisar as relações que o assistente social/supervisor de campo estabelece com a instituição e os usuários dos serviços sociais e como sua prática tem papel influenciador na vida do acadêmico estagiário. Este artigo é fruto de uma pesquisa qualitativa do tipo bibliográfica e pesquisa de campo realizada para elaboração de Trabalho de Conclusão de Curso na Universidade Federal do Amazonas-UFAM. Busca-se com este estudo contribuir para a formação de acadêmicos e futuros profissionais

VLBI Astrometry of the Semiregular Variable RX Bootis

We present distance measurement of the semiregular variable RX Bootis (RX Boo) with its annual parallax. Using the unique dual-beam system of the VLBI Exploration of Radio Astrometry (VERA) telescope, we conducted astrometric observations of a water maser spot accompanying RX Boo referred to the quasar J1419+2706 separated by 1.69 degrees from RX Boo. We have measured the annual parallax of RX Boo to be 7.31 +/- 0.50 mas, corresponding to a distance of 136 +10/-9 pc, from the one-year monitoring observation data of one maser spot at VLSR = 3.2 km/s. The distance itself is consistent with the one obtained with Hipparcos. The distance uncertainty is reduced by a factor of two, allowing us to determine the stellar properties more accurately. Using our distance, we discuss the location of RX Boo in various sequences of Period-Luminosity (PL) relations. We found RX Boo is located in the Mira sequence of PL relation. In addition, we calculated the radius of photosphere and the mass limitation of RX Boo and discussed its evolutionary status.Comment: 8 pages, 4figure

Neuregulin 1 Type II-ErbB Signaling Promotes Cell Divisions Generating Neurons from Neural Progenitor Cells in the Developing Zebrafish Brain.

Post-mitotic neurons are generated from neural progenitor cells (NPCs) at the expense of their proliferation. Molecular and cellular mechanisms that regulate neuron production temporally and spatially should impact on the size and shape of the brain. While transcription factors such as neurogenin1 (neurog1) and neurod govern progression of neurogenesis as cell-intrinsic mechanisms, recent studies show regulatory roles of several cell-extrinsic or intercellular signaling molecules including Notch, FGF and Wnt in production of neurons/neural progenitor cells from neural stem cells/radial glial cells (NSCs/RGCs) in the ventricular zone (VZ). However, it remains elusive how production of post-mitotic neurons from neural progenitor cells is regulated in the sub-ventricular zone (SVZ). Here we show that newborn neurons accumulate in the basal-to-apical direction in the optic tectum (OT) of zebrafish embryos. While neural progenitor cells are amplified by mitoses in the apical ventricular zone, neurons are exclusively produced through mitoses of neural progenitor cells in the sub-basal zone, later in the sub-ventricular zone, and accumulate apically onto older neurons. This neurogenesis depends on Neuregulin 1 type II (NRG1-II)-ErbB signaling. Treatment with an ErbB inhibitor, AG1478 impairs mitoses in the sub-ventricular zone of the optic tectum. Removal of AG1478 resumes sub-ventricular mitoses without precedent mitoses in the apical ventricular zone prior to basal-to-apical accumulation of neurons, suggesting critical roles of ErbB signaling in mitoses for post-mitotic neuron production. Knockdown of NRG1-II impairs both mitoses in the sub-basal/sub-ventricular zone and the ventricular zone. Injection of soluble human NRG1 into the developing brain ameliorates neurogenesis of NRG1-II-knockdown embryos, suggesting a conserved role of NRG1 as a cell-extrinsic signal. From these results, we propose that NRG1-ErbB signaling stimulates cell divisions generating neurons from neural progenitor cells in the developing vertebrate brain