Somite Division and New Boundary Formation by Mechanical Strain.

Somitogenesis, the primary segmentation of the vertebrate embryo, is associated with oscillating genes that interact with a wave of cell differentiation. The necessity of cell-matrix adherence and embryonic tension, however, suggests that mechanical cues are also involved. To explicitly investigate this, we applied surplus axial strain to live chick embryos. Despite substantial deformations, the embryos developed normally and somite formation rate was unaffected. Surprisingly, however, we observed slow cellular reorganizations of the most elongated somites into two or more well-shaped daughter somites. In what appeared to be a regular process of boundary formation, somites divided and fibronectin was deposited in between. Cell counts and morphology indicated that cells from the somitocoel underwent mesenchymal-epithelial transition; this was supported by a Cellular Potts model of somite division. Thus, although somitogenesis appeared to be extremely robust, we observed new boundary formation in existing somites and conclude that mechanical strain can be morphologically instructive.

Ameloblastoma folicular extensivo em mandíbula / Extensive follicular ameloblastoma in the mandible

O ameloblastoma é um tumor odontogênico benigno, de grande variação histológica, com alguns tipos apresentando alta propensão para recorrência. Diversos tratamentos são indicados, incluindo uma abordagem mais conservadora, desde a curetagem e a marsupialização até as mais radicais, como ressecções parciais ou totais da área afetada. O presente trabalho tem como objetivo proceder a uma revisão de literatura, abordando aspectos, a exemplo dos diferentes tipos de tratamento, algumas limitações e vantagens das técnicas, bem como apresentar um relato de um caso clínico conduzido pela equipe de Cirurgia e Traumatologia Buco-Maxilo-Facial no Hospital Nossa Senhora da Conceição (Tubarão/SC) de um paciente submetido à exérese de ameloblastoma multicístico e reconstrução imediata com enxerto de costela flutuante livre do lado direito, com resultado satisfatório na reabilitação do caso, restabelecendo o contorno anatômico e a função condilar... (AU)

The ameloblastoma is a benign tumor that has a great histological variation, being that in some types show high tendency of being recurring. Several treatments are indicated, including a more conservative approach, like curettage and marsupialization, even the most radical ones, like partial or total resection of the infected area. This paper aims to make a revision of literature, approaching aspects like the different types of treatment, some of its limitations and technical advantages, as well as show a clinical case conducted by the Oral and Maxillofacial surgery and traumatology team at NossaSenhora da Conceição Hospital (Tubarão /SC) of a patient subjected to exeresis of multicisticameloblastoma and immediate reconstruction with right side floating rib graft, showing a satisfactory result on the rehabilitation of the case, reestablishing the anatomic shaping and condylar function... (AU)

A Submerged Filter Paper Sandwich for Long-term Ex Ovo Time-lapse Imaging of Early Chick Embryos.

Due to its availability, low cost, flat geometry, and transparency, the ex ovo chick embryo has become a major vertebrate animal model for the study of morphogenetic events, such as gastrulation2, neurulation3-5, somitogenesis6, heart bending7,8, and brain formation9-13, during early embryogenesis. Key to understanding morphogenetic processes is to follow them dynamically by time-lapse imaging. The acquisition of time-lapse movies of chick embryogenesis ex ovo has been limited either to short time windows or to the need for an incubator to control temperature and humidity around the embryo14. Here, we present a new technique to culture chick embryos ex ovo for high-resolution time-lapse imaging using transmitted light microscopy. The submerged filter paper sandwich is a variant of the well-established filter paper carrier technique (EC-culture)1 and allows for the culturing of chick embryos without the need for a climate chamber. The embryo is sandwiched between two identical filter paper carriers and is kept fully submerged in a simple, temperature-controlled medium covered by a layer of light mineral oil. Starting from the primitive streak stage (Hamburger-Hamilton stage 5, HH5)15 up to at least the 28-somite stage (HH16)15, embryos can be cultured with either their ventral or dorsal side up. This allows the acquisition of time-lapse movies covering about 30 hr of embryonic development. Representative time-lapse frames and movies are shown. Embryos are compared morphologically to an embryo cultured in the standard EC-culture. The submerged filter paper sandwich provides a stable environment to study early dorsal and ventral morphogenetic processes. It also allows for live fluorescence imaging and micromanipulations, such as microsurgery, bead implantation, microinjection, gene silencing, and electroporation, and has a strong potential to be combined with immersion objectives for laser-based imaging (including light-sheet microscopy).

Structural purity of magnetite nanoparticles in magnetotactic bacteria.

Magnetosome biomineralization and chain formation in magnetotactic bacteria are two processes that are highly controlled at the cellular level in order to form cellular magnetic dipoles. However, even if the magnetosome chains are well characterized, controversial results about the microstructure of magnetosomes were obtained and its possible influence in the formation of the magnetic dipole is to be specified. For the first time, the microstructure of intracellular magnetosomes was investigated using high-resolution synchrotron X-ray diffraction. Significant differences in the lattice parameter were found between intracellular magnetosomes from cultured magnetotactic bacteria and isolated ones. Through comparison with abiotic control materials of similar size, we show that this difference can be associated with different oxidation states and that the biogenic nanomagnetite is stoichiometric, i.e. structurally pure whereas isolated magnetosomes are slightly oxidized. The hierarchical structuring of the magnetosome chain thus starts with the formation of structurally pure magnetite nanoparticles that in turn might influence the magnetic property of the magnetosome chains.