The cleavage program in the 2d cell lineage of Tubifex embryos

Early development in clitellate annelids is characterized by a highly stereotyped sequence of unequal, spiral cleavages. Cell 2d (i.e., the second micromere of the D quadrant) in the oligochaete Tubifex tubifex also undergoes an evolutionarily conserved sequence of cell division to produce four bilateral pairs of ectodermal teloblasts that act as embryonic stem cells. This study was conducted to characterize each of the 15 rounds of cell division that occur in the 2d cell lineage in this clitellate. After its occurrence, cell 2d undergoes three rounds of highly unequal divisions, giving off the first smaller daughter cell toward the posterior right of the larger daughter cell, the second cell toward the posterior left, and the third cell toward the anterior side of the cell; the larger daughter cell that results from the third division (i.e., the great-granddaughter cell of 2d) then divides equally into a bilateral pair of NOPQ proteloblasts. Cell NOPQ on either side of the embryo undergoes 11 rounds of cell division, during which ectoteloblasts N, Q, and O/P are produced in this order. After its appearance, NOPQ undergoes highly unequal divisions twice cutting off the smaller cells toward the anterior end of the embryo and then divides almost equally into ectoteloblast N and proteloblast OPQ. After its appearance, OPQ undergoes highly unequal divisions twice giving off the first smaller cell toward the anterior and the second smaller cell toward the posterior of the embryo and then divides almost equally into ectoteloblast Q and proteloblast OP. Finally, OP undergoes highly unequal division four times after its birth budding off the smaller cells toward the anterior and then cleaves equally into ectoteloblasts O and P. In the unequally dividing cells of the 2d cell lineage, the mitotic apparatus (MA), which forms at the cell's center, moves eccentrically toward the cortical site where the smaller cell will be given off. The moving MA is oriented perpendicular to the surface it approaches, and its peripheral pole becomes closely associated with the cell cortex. In contrast, the MA involved in the equal divisions remains in the cell center throughout mitosis. The key features of the cleavage program in the 2d cell lineage are discussed in light of the present observations. The mechanical aspects of unequal cleavage in the 2d cell lineage and the modes of specification of MA orientation are discussed. A comparison of the cleavage mode in the 2d cell lineage is also performed among six selected clitellate annelid species.     

Cochlear neural degeneration disrupts hearing in background noise by increasing auditory cortex internal noise

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Is monomorphic tachycardia indeed monomorphic?

The dependence of some ECG characteristics on the excitation threshold was studied by mathematical modeling of cardiac arrhythmia in a 2D homogeneous excitable medium. It is shown that monomorphic tachycardias can arise both at elevated and at lowered excitability but the ECG characteristics in these cases are different.     

Effect of lncRNA-ATB/miR-651-3p/Yin Yang 1 pathway on trophoblast-endothelial cell interaction networks

Our previous studies have confirmed that lncRNA-ATB may be involved in the pathogenesis of preeclampsia, however, it is uncertain whether lncRNA-ATB influence the interaction between trophoblast and endothelial cells, which is crucial to the uterine spiral artery remodelling. Scratch wound healing and transwell invasion assay were conducted to test the migration and invasion of trophoblast cells. Co-culture model was used to simulate the physiological environment in vivo. The expression levels of lncRNA-ATB were analyzed in placenta tissues from healthy pregnant women and preeclampsia patients. Subsequently, the binding site of lncRNA-ATB and miR-651-3p was verified using dual-luciferase reporter assay, and the rescue experiment was used to study the effects of these two on the biological function. The direct effects of miR-651-3p and Yin Yang 1 (YY1) were verified using similar methods. LncRNA-ATB was found to be down-regulated in the placenta of preeclampsia patients. LncRNA-ATB knockdown decreased trophoblast migration, invasion and colocalisation with human umbilical vein endothelial cells. MiR-651-3p was a direct target of lncRNA-ATB and they had opposite effects. Moreover, the expression of lncRNA-ATB and miR-651-3p in placental tissues was negatively correlated. MiR-651-3p has been confirmed to directly target the 3′ untranslated region of YY1. The inhibitory effects of YY1 low expression on biological function was rescued by miR-651-3p depletion. Western blot analysis showed that lncRNA-ATB could regulate YY1 expression by sponging miR-651-3p. LncRNA-ATB functioned as a competitive endogenous RNA of miR-651-3p to regulate YY1 on progress of spiral artery remodelling.     

Runx1 controls auditory sensory neuron diversity in mice

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Reproduction of Criconemoides simile, Helicotylenchus pseudorobustus,and Paratylenchus projectus on Soybean

Reproduction of Criconernoides simile, Paratylenchus projectus, and Helicotylenchus pseudorobustus, alone and in certain combinations, was characterized during 50 days on the soybean cultivars Custer and Hood. Custer was the more suitable host for all three nematodes and C. simile was the most vigorous parasite on both cultivars. C. simile and H. pseudorobustus reproduced as well in combination as they did alone; addition of P. projectus to this combination did not alter results. Reproduction by P. projectus was repressed on both cultivars when it was combined with C. simile and H. pseudorobustus. The relative importance of time was assessed, as it relates both to the establishment of parasitism by applied nematodes and to the rate of development of larvae in the various host-parasite combinations. The necessity of characterizing as well as enumerating populations when evaluating population development of ectoparasitic nematodes was demonstrated.     

Pulsatile spiral blood flow through arterial stenosis

Pulsatile spiral blood flow in a modelled three-dimensional arterial stenosis, with a 75% cross-sectional area reduction, is investigated by using numerical fluid dynamics. Two-equation k-ω model is used for the simulation of the transitional flow with Reynolds numbers 500 and 1000. It is found that the spiral component increases the static pressure in the vessel during the deceleration phase of the flow pulse. In addition, the spiral component reduces the turbulence intensity and wall shear stress found in the post-stenosis region of the vessel in the early stages of the flow pulse. Hence, the findings agree with the results of Stonebridge et al. (2004). In addition, the results of the effects of a spiral component on time-varying flow are presented and discussed along with the relevant pathological issues.