4-4-difluoro-4-bora-3a-4a-diaza-s-indacene and 3-3--dioctadecylindocarbocyanine

We follow somite segmentation in living chick embryos and find that the shaping process is not a simple periodic slicing of tissue blocks but a much more carefully choreographed separation in which the somite pulls apart from the segmental plate. Cells move across the presumptive somite boundary and violate gene expression boundaries thought to correlate with the site of the somite boundary. Similarly, cells do not appear to be preassigned to a given somite as they leave the node. The results offer a detailed picture of somite shaping and provide a spatiotemporal framework for linking gene expression with cell movements.

Topics: Animals; Boron Compounds; Carbocyanines; Cell Adhesion; Cell Movement; Cell Size; Central Nervous System; Ceramides; Chick Embryo; Epithelial Cells; Gene Expression; Gene Expression Profiling; Mesoderm; Microscopy, Confocal; Models, Biological; Receptor, EphA4; Somites; Time Factors

To understand the mechanisms for endocytic sorting of lipids, we investigated the trafficking of three lipid-mimetic dialkylindocarbocyanine (DiI) derivatives, DiIC16(3) (1,1'-dihexadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate), DiIC12(3) (1,1'- didodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate), and FAST DiI (1,1'-dilinoleyl-3,3,3', 3'-tetramethylindocarbocyanine perchlorate), in CHO cells by quantitative fluorescence microscopy. All three DiIs have the same head group, but differ in their alkyl tail length or unsaturation; these differences are expected to affect their distribution in membrane domains of varying fluidity or curvature. All three DiIs initially enter sorting endosomes containing endocytosed transferrin. DiIC16(3), with two long 16-carbon saturated tails is then delivered to late endosomes, whereas FAST DiI, with two cis double bonds in each tail, and DiIC12(3), with saturated but shorter (12-carbon) tails, are mainly found in the endocytic recycling compartment. We also find that DiOC16(3) (3,3'- dihexadecyloxacarbocyanine perchlorate) and FAST DiO (3, 3'-dilinoleyloxacarbocyanine perchlorate) behave similarly to their DiI counterparts. Furthermore, whereas a phosphatidylcholine analogue with a BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) fluorophore attached at the end of a 5-carbon acyl chain is delivered efficiently to the endocytic recycling compartment, a significant fraction of another derivative with BODIPY attached to a 12-carbon acyl chain entered late endosomes. Our results thus suggest that endocytic organelles can sort membrane components efficiently based on their preference for association with domains of varying characteristics.

Topics: Animals; Boron Compounds; Carbocyanines; Cell Membrane; CHO Cells; Cricetinae; Endocytosis; Endosomes; Fluorescent Dyes; Humans; Lipid Metabolism; Lipids; Lysosomes; Models, Biological; Receptors, Transferrin