Distal tip cell

Lehmann, R. (2001) Cell migration in invertebrates clues from border and distal tip cells. Curr. Opin. Genet. Dev. 11, 457-463. 

Nishiwaki, K. (1999) Mutations affecting symmetrical migration of distal tip cells in Caenorhabditis elegans. Geneties 152, 985-997. 

So far, we have focused mainly on the potential pathways of carotenoid uptake by the RPE from the choroidal blood supply. As mentioned earlier, POS contain lutein and zeaxanthin, and their distal tips are phagocytosed by the RPE. Therefore POS is another source of xanthophylls in the RPE and this pathway of carotenoid delivery and their further fate can be easily tested in cultured RPE. It has been shown that exposure of RPE cells in vitro to HDL stimulates efflux of phospholipids from phagocytosed POS out of the cell (Ishida et al., 2006). Thus it is of interest to determine whether that transport may potentially include xanthophylls and whether other types of lipoproteins may... 

At the distal tip of the axon are voltage-gated Ca2+ channels. When the wave of depolarization reaches these channels, they open, and Ca2+ enters from the extracellular space. The rise in cytoplasmic [Ca2+] then triggers release of acetylcholine by exocy-tosis into the synaptic cleft (step (3) in Fig. 12-5). Acetylcholine diffuses to the postsynaptic cell (another... 

Fig. 8. Labeling the endoderm of 7.0-d embryo by electroporation. A The embryo is first bathed in plasmid DNA solution before transfer to the electroporation drop on the culture dish. To electroporate the distal tip, the embryo is held at the extraembryonic ectoderm by suction using the holding pipet (hp) and positioned between the platinum plate (cathode) and tungsten needle (anode). The electrodes are connected to an Electro Square Porator and the electroporation is focused at the tissue closest to the needle tip. B Fluorescent cells in the distal region of the embryo following electroporation with a P-actin-eGFP construct and cultured for 3h.

The localization of the IP, receptor has been compared to the localization of other luminal or membrane components of the endoplasmatic reticulum related to Ca "" homeostasis. The membrane pump Ca -ATPase, immunolabelled with antibodies against cardiac Ca -ATPase, was found to be located in regular cisternae of the endoplasmatic reticulum, the lateral tips of cisternae of the Golgi complex and in calciosomes of Purkinje cells (Kaprielian, 1989 Michelangeli et al., 1991 Villa et al., 1991 Takei et al., 1992) (Fig. 27). Distal axons of Purkinje cells, however, lacked Ca "-ATPase im-munoreactivity (Takei et al., 1992). Appreciable levels of calsequestrin, the main intraluminal calcium-binding protein of muscle, were present in Purkinje cells of the chicken. Calsequestrin-immunoreactivity was present over the lumen (Villa et al., 1991) and membranes (Takei et al., 1992) of stacked and isolated cisternae of the endoplasmatic reticulum and in a subpopulation of calciosomes (Volpe et al., 1988 Volpe and Villa,... 

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