For many years, polyclonal antibodies raised against the plant glycoprotein horseradish peroxidase have been used to specifically stain the neural and male reproductive tissue of Drosophila melanogaster. This epitope is considered to be of carbohydrate origin, but no glycan structure from Drosophila has yet been isolated that could account for this cross-reactivity. Here we report that N-glycan core ␣1,3-linked fucose is, as judged by preabsorption experiments, indispensable for recognition of Drosophila embryonic nervous system by anti-horseradish peroxidase antibody. Further, we describe the identification by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry and high performance liquid chromatography of two Drosophila N-glycans that, as already detected in other insects, carry both ␣1,3-and ␣1,6-linked fucose residues on the proximal core GlcNAc. Moreover, we have isolated three cDNAs encoding ␣1,3-fucosyltransferase homologues from Drosophila. One of the cDNAs, when transformed into Pichia pastoris, was found to direct expression of core ␣1,3-fucosyltransferase activity. This recombinant enzyme preferred as substrate a biantennary core ␣1,6-fucosylated N-glycan carrying two non-reducing N-acetylglucosamine residues (GnGnF 6 ; K m 11 M) over the same structure lacking a core fucose residue (GnGn; K m 46 M). The Drosophila core ␣1,3-fucosyltransferase enzyme was also shown to be able to fucosylate N-glycan structures of human transferrin in vitro, this modification correlating with the acquisition of binding to anti-horseradish peroxidase antibody.Glycoproteins from plants and invertebrates are often highly immunogenic and many antibodies (both IgG and IgE) directed against them bind to core ␣1,3-fucose and/or ␤1,2-xylose residues of their N-linked oligosaccharides (1-7); since these modifications are present across plant species and one or the other modification is present in a number of invertebrates, these antibodies are highly cross-reactive. Indeed, polyclonal antibodies to horseradish peroxidase (anti-HRP) 1 have been used for nearly two decades to specifically stain neurons, and their growth pathways, in Drosophila melanogaster (8 -11); similar staining has also been described in grasshopper (11), whereas in Caenorhabditis elegans 10% of neurons are stained by this antibody (12). A number of proteins in Drosophila, such as an Na ϩ ,K ϩ ATPase christened Nervana, a receptor tyrosine phosphatase, and cell adhesion molecules (e.g. fasciclin I and II, neurotactin and neuroglian), have been found to bind anti-HRP (9 -11, 13, 14); however, no data on their glycosylation have been described. A number of Drosophila nac (neurally altered carbohydrate) mutants have been described, which are defective in anti-HRP staining of adult flies and display wing morphological defects (15) and, when under cold stress, some minor behavioral and eye developmental abnormalities (9). Neither the affected gene(s) nor the underlying biochemical defect(s) have been identified.As compared with the amount o...

p27(Kip1) plays an important role in cell cycle regulation by inhibiting cyclin-CDK complex activity in the nucleus. p27(Kip1) is regulated by its concentration as well as by its subcellular localization. Tuberin, encoded by the tuberous sclerosis tumor suppressor gene TSC2, is a potent negative cell cycle regulator. We show herein, that tuberin induces nuclear p27 localization by inhibiting its 14-3-3-mediated cytoplasmic retention. Tuberin interferes with 14-3-3's counteracting effects on p27-mediated cell cycle arrest. Akt-mediated phosphorylation of p27, but not of tuberin, negatively regulates tuberin's potential to trigger p27 nuclear localization. In G0 cells, tuberin binds p27 triggering downregulation of p27's binding to 14-3-3 and of its cytoplasmic retention. At transition to S phase p27 is phosphorylated by Akt, tuberin/p27 complex levels are downregulated and binding of p27 to 14-3-3 increases triggering cytoplasmic retention of p27. These findings demonstrate p27 localization during the mammalian cell cycle to be under the control of the tumor suppressor tuberin.

The discovery of amniotic fluid stem cells initiated a new and very promising field in stem cell research. In the last four years amniotic fluid stem cells have been shown to express markers specific to pluripotent stem cells, such as Oct-4. Due to their high proliferation potential, amniotic fluid stem cell lineages can be established. Meanwhile, they have been shown to harbor the potential to differentiate into cells of all three embryonic germ layers. It will be a major aim for the future to define the potential of this new source of stem cells for therapies related to specific diseases.

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