http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Tue, 22 Jan 2013 15:49:47 +0000 http://www.hindawi.com/isrn/db/2013/628962/ Delta-like 1 homolog (DLK1) is a noncanonical ligand in the Delta-Notch signalling pathway. Although Dlk1 mRNA is abundantly present embryonically and declines rapidly just before birth, Dlk1 knockouts display a relatively mild phenotype. To assess whether this mild phenotype was due to posttranscriptional regulation, we studied the expression of DLK1 protein in mouse embryos and found abundant expression in liver, lung, muscle, vertebrae, pancreas, pituitary, and adrenal gland(s). DLK1 expression was absent in heart, stomach, intestine, kidney, epidermis, and central nervous system. DLK1 protein expression, therefore, correlates well with the reported Dlk1 mRNA expression pattern, which shows that its expression is mainly regulated at the pretranslational level. The comparison of the reported expression patterns of Notch mRNA and those of DLK1 in organs where lineage commitment and branching morphogenesis are important developmental processes suggests that DLK1 is a ligand that prevents premature Notch-dependent differentiation, possibly by competing with canonical ligands. F. A. Falix, M. R. S. Tjon-A-Loi, I. C. Gaemers, D. C. Aronson, and W. H. Lamers Copyright © 2013 F. A. Falix et al. All rights reserved. Tue, 04 Dec 2012 14:00:07 +0000 http://www.hindawi.com/isrn/db/2013/920265/ We investigated the distribution of -tubulin in zebrafish oocytes and embryos using epifluorescent or confocal microscopy and -tubulin antibodies. During meiotic maturation of zebrafish oocytes, -tubulin begins redistribution from oocyte ooplasm and cortex to the future blastodisc region at the animal pole. In activated eggs, -tubulin was uniformly distributed in the enlarging blastodisc with label emanating from the yolk cell. In newly fertilized eggs, -tubulin was evenly distributed in blastomere cytoplasm, with the presence of pronuclei but initially lacking discernable centrosomes. During early cleavage, especially at the eight-cell stage, striking arc-shaped/rings (A/R) of putative centrosomes were detected. Decreasing -tubulin was seen in yolk cells while early cleavage blastomeres had strong cytoplasmic label along with obvious A/R arrays. In addition, we found the orientation of the A/R array and nuclear division alternated by about 90 degrees for each cell cycle along with alternation of punctate and A/R arrays. Jianxiong Liu and Charles A. Lessman Copyright © 2013 Jianxiong Liu and Charles A. Lessman. All rights reserved.