A monoclonal antibody specific for diploid epithelial cells in Drosophila

Results from various experiments suggest that the cell surface has an important role in development. However, there is relatively little information on the specific surface molecules involved in developmental processes. In an effort to characterize cell-surface components that may be involved in Drosophila development, we have been making monoclonal antibodies against D. melanogaster imaginal disks. The holometabolous insects are unusual in that scattered among the larval tissues are groups of undifferentiated imaginal cells which, during metamorphosis, will form most of the adult insect. The imaginal disks, which we use as an immunogen, are hollow sacs of cells; each disk will form a specific part of the adult cuticle. Other imaginal cells are found as nests or rings in various larval organs. We describe here results indicating that one of the clones we have isolated, DA.1B6, makes an antibody against an antigen which, in larvae, is generally restricted to the undifferentiated sheets of imaginal epithelial cells. This and other results indicate that the antigen is specific for the diploid epithelia in Drosophila.     

ELAM-1 is an adhesion molecule for skin-homing T cells.

Endothelial cell leukocyte adhesion molecule-1 (ELAM-1) has been described as an inducible endothelial cell-adhesion molecule for neutrophils, and is believed to have a key role in the extravasation of these cells at sites of acute inflammation. Here we report that ELAM-1-transfected COS cells also bind a unique skin-associated subset of circulating memory T cells defined by the expression of the cutaneous lymphocyte-associated antigen. T cells expressing this antigen bind at least as well as neutrophils to expressed ELAM-1, whereas other lymphocytes in the peripheral blood bind poorly, or not at all. Immunohistological survey of chronically inflamed tissue specimens revealed that vascular expression of ELAM-1 occurs at cutaneous sites in preference to noncutaneous sites. We conclude that at sites of chronic inflammation, ELAM-1 may function as a skin vascular addressin, a tissue-selective endothelial cell-adhesion molecule for skin-homing memory T lymphocytes.     

Reversible inhibition of translation by Xenopus oocyte-specific proteins

A characteristic of growing oocytes of all animal species is the synthesis and accumulation of messenger RNA which is destined to be used primarily by the early embryo. The mechanism(s) which regulates the translation of this maternal mRNA remains unknown. However, the inability of the oocyte to translate all of its putative mRNA has been attributed to at least three limitations: (1) The rate of translation is limited by the availability of components of the translational apparatus other than mRNA, (2) the structural organization of the mRNA prevents translation, and (3) proteins associated with the mRNA prevent translation. Several investigators have suggested that proteins associated with maternal mRNA suppress translation in sea urchin eggs, although others claim that such results may be due to experimental artefacts. Oocyte-specific proteins have been identified in association with non-translating poly(A)+ mRNAs from Xenopus laevis oocytes, and we report here that when these proteins are reconstituted with mRNAs in vitro the translation of the mRNAs in vitro is reversibly repressed. The implication is that these proteins are involved in the regulation of translation of stored maternal mRNAs.