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The Twentieth Century
Published in Arturo Castiglioni, A History of Medicine, 2019
Gastrulation had long been recognized as a significant step in the sequence of events associated with organization of the embryo. It was known that a large portion of the ectoderm (the outermost of the three primitive layers) of the blastula swept downward to the blastopore (the mouth of the primitive gut, or archenteron), where it invaginated to produce the mesoderm and roof of the archenteron. Attempts at tracing the subsequent fate of different regions of this presumptive mesoderm were at first confined to the production of an injury in a single region, until W. vogt mapped out the fate of the different surface areas of the amphibian gastrula (1929), by staining circumscribed regions with vital dyes and tracing their subsequent migrations.
Integrin Function in Early Vertebrate Development: Perspectives from Studies of Amphibian Embryos
Published in Yoshikazu Takada, Integrins: The Biological Problems, 2017
Mechanistically, the process of gastrulation may be considered on several levels that include: (1) the “behavior” of the individual cells that collectively serve to “drive” morphogenesis at gastrulation, (2) the molecules mediating the shape changes and adhesive properties of these cells, and (3) the control of the timing and patterning of the cellular movements involved. Following the progression through early cleavage and blastula stages, gastrulation begins with the appearance of a slit-like invagination of bottle cells, termed the blastopore, on the dorsal side of the embryo as illustrated in Figure 1. The involuting mesoderm subsequently comes in contact with the blastocoel roof and travels along it in the direction of the animal pole. The zone of involution initiated at the dorsal lip of the blastopore spreads laterally and ventrally to enclose the endoderm, which remains visible as a yolk plug through late gastrulation. The superficial cells of the animal pole and equatorial marginal zone spread by epiboly during this process, thus covering the entire outer surface of the embryo. Inside the embryo, the endodermally derived archenteron forms as the mesoderm advances, resulting in the displacement of the blastocoel (Figure 1).
Regulation of Cell Functions
Published in Enrique Pimentel, Handbook of Growth Factors, 2017
Sequential expression of homeotic genes is associated with the early stages of limb bud outgrowth in the mouse, with each gene showing a graded transcript distribution along the antero-posterior axis.125 A homeodomain protein, GHF1, is required for pituitary cell proliferation in the mouse.126 Homeobox genes can organize a complete secondary body axis in the dorsal blastopore lip of the early Xenopus laevis gastrula.127 Analysis of HOX gene expression in human hematopoietic cell lines suggests that these genes are switched on or off in blocks at various stages of hematopoietic cell differentiation.128 Lineage- and stage-specific expression of HOX1 genes occurs in the human hematopoietic system.129 Modulation of HOX1 gene expression alters the phenotype of human hematopoietic cell lines.130 A coordinate regulation of HOX genes may play a very important role in lineage determination during early stages of hematopoiesis.
Distribution and translocation of micro- and nanoplastics in fish
Published in Critical Reviews in Toxicology, 2021
Cuizhu Ma, Qiqing Chen, Jiawei Li, Bowen Li, Weiwenhui Liang, Lei Su, Huahong Shi
Endocytosis and membrane penetration are two main pathways for nanomaterials entrance into cells (Li et al. 2013; Chen et al. 2016) (Table 3). In instances, villus endocytosis and paracellular penetration are also responsible for early intestinal uptake of nanomaterials (Coméra et al. 2020). In vitro experiments show that the cell internalization efficiency of manufactured nanomaterials increased with the decrease of particle size (Zhou et al. 2020). For example, the absorption rate of gold nanomaterials by the model intestinal epithelium cells increased due to the decrease of the mean particle diameter of gold nanomaterials (Yao et al. 2015). Researchers found that spherical silver nanomaterials could translocate into embryos through blastopore penetration or endocytosis (5 − 72 nm) and enter fish cells via pinocytosis (about 10 nm) and caveolae-dependent pathway (30 and 100 nm) (Lee et al. 2007, 2012; Quevedo et al. 2021). Graphene oxide nanosheet NMs (0.5–5 μm) also translocate to the eyes, heart, brain of adult fish and even subsequently pass onto their offspring similar to NPs (Chen et al. 2016; Hu et al. 2017).
Antimicrobial sonodynamic and photodynamic therapies against Candida albicans
Published in Biofouling, 2018
Fernanda Alves, Ana Cláudia Pavarina, Ewerton Garcia de Oliveira Mima, Anthony P. McHale, John Francis Callan
The assessment of biofilm morphology and architecture was performed using light and fluorescence microscopy (Figure 3). The image captured in the control group shows a denser biofilm, a high concentration of live cells (blastopore and hypha) and a thickness equivalent to 88.54 μm when measured by CLSM. The biofilms treated with aPDT+SDT mediated by 175 or 200 mg l−1 of PDZ showed a reduction in biofilm density with an equivalent thickness of 45.3 and 44.6 μm, respectively, a smaller number of cells, a reduction in the filamentous form and most of the cell nuclei were stained with TB, indicating cell death. The images obtained in the groups treated with aPDT+SDT mediated by 100 or 200 mg l−1 of RB demonstrated a reduced density (with a thickness equivalent 42.07 and 49.84 μm, respectively), a reduction in hyphae and most of the cell nuclei had stained with TB. The results visualized by microscopy are in accordance with the results obtained in the CFU and total biomass assays, where the combined treatment of SDT and aPDT reduced significantly the viability of C. albicans.