Background:Fibroadenomas and phyllodes tumors may have similar cytological appearances. However, a detailed study of cytomorphology of stromal elements may be helpful in differentiation.Aim:To evaluate the cytological features of phyllodes tumor in our study with special reference to features that can help distinguishing it from fibroadenoma.Materials and Methods:The archival materials of our hospital were searched from January 2006 to January 2009 for histopathologically-diagnosed cases of phyllodes tumor. The cases in which previous cytopathology smears were available were included in the study. The cytomorphology of 10 such cases were compared with 25 cytologically-diagnosed and histopathologically-confirmed cases of fibroadenoma.Results:The size, cellularity of stromal fragments, and the proportion of spindle cells in the background are important features in such differentiation.

In the nematode Caenorhabditis elegans, the gonad acquires two U-shaped arms through the directed migration of its distal tip cells (DTCs), which are located at the tip of the growing gonad arms. A member of the ADAM (a disintegrin and metalloprotease) family, MIG-17, regulates directional migration of DTCs: MIG-17 is synthesized and secreted from the muscle cells of the body wall, and diffuses to the gonad where it is required for DTC migration. The mig-23 mutation causes defective migration of DTCs and interacts genetically with mig-17. Here, we report that mig-23 encodes a membrane-bound nucleoside diphosphatase (NDPase) required for glycosylation and proper localization of MIG-17. Our findings indicate that an NDPase affects organ morphogenesis through glycosylation of the MIG-17 ADAM protease.

The oligosaccharide profiles in glycoproteins are determined by a series of processing reactions catalyzed by Golgi glycosyltransferases and glycosidases. Recently in vivo galactose incorporation in Saccharomyces cerevisiae has been demonstrated through the expression of human ␤-1,4-galactosyltransferase in an alg1 mutant, suggesting the presence of a UDP-galactose transporter in S. cerevisiae (Schwientek, T., Narimatsu, H., and Ernst, J. F. (1996) J. Biol. Chem. 271, 3398 -3405). However, this is quite unexpected, because S. cerevisiae does not have galactose residues in its glycoproteins. To address this question we have constructed S. cerevisiae mnn1 mutant strains expressing Schizosaccharomyces pombe ␣-1,2-galactosyltransferase. The mnn1 mutant of S. cerevisiae provides endogenous acceptors for galactose transfer by the expressed ␣-1,2-galactosyltransferase. We present here three lines of evidences for the existence of UDP-galactose transporter in S. cerevisiae. (i) About 15-20% of the total transformed mnn1 cells grown in a galactose medium were stained with fluorescein isothiocyanate-conjugated ␣-galactose-specific lectin, indicating the presence of ␣-galactose residues on the cell surface. (ii) Galactomannan proteins can be precipitated with agarose-immobilized ␣-galactose-specific lectin from a whole cell lysate prepared from transformed mnn1 cells grown in a galactose medium. (iii) The presence of UDP-galactose transporter was demonstrated by direct transport assay. This transport in S. cerevisiae is dependent on time, temperature, and protein concentration and is inhibited by nucleotide monophosphate and Triton X-100. The overall UDP-galactose transport in S. cerevisiae is comparable with that in S. pombe, indicating a more or less similar reaction velocity, while the rate of GDP-mannose transport is higher in S. pombe than in S. cerevisiae. N-Linked glycosylation is an essential modification that is highly conserved among all eukaryotic cells (1-4). The complex N-linked oligosaccharides have a wide variety of structure in animal cells, while they are relatively simpler in lower eukaryotes, such as Saccharomyces cerevisiae. However, in both cases the initial steps are nearly identical and involve the synthesis of Glc 3 Man 9 GlcNAc 2 -PP-dol, transfer of oligosaccharide from lipid to protein, and subsequent trimming to Man 8 GlcNAc 2 in the endoplasmic reticulum. In the latter stage S. cerevisiae elongates it to polymannose-type structure without adding any N-acetylglucosamine, galactose, and sialic acid residues that are characteristics of complex oligosaccharides in mammalian cells. Recently, interest in glycosyltransferases arose by their potential usefulness as tools for the synthesis of oligosaccharides in vitro (5) and for the remodeling of glycan chains of natural or recombinant glycoproteins. Yeast offers an attractive host for the production of heterologous proteins (6), and a number of recombinant glycoproteins were successfully produced in S. cerevisiae, although the sugars attached to prote...

Chitin is an essential cell wall component, synthesis of which is regulated throughout the cell cycle in the yeast Saccharomyces cerevisiae. We cloned an S. cerevisiae gene, YEA4, whose product is homologous to the Kluyveromyces lactis uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) transporter. An epitope-tagged Yea4p localized mainly in the 10,000 ؋ g pellet (P2), suggesting endoplasmic reticulum (ER) localization. Membrane vesicles from the P2 fraction showed an 8-fold higher UDP-GlcNAc transport activity in cells harboring a multicopy YEA4 plasmid than in cells harboring vector alone. The activity distribution is identical with the protein distribution in P2, whether the gene is overexpressed or not, suggesting its native localization in P2. Immunolocalization of epitope-tagged Yea4p further revealed ER localization. The increase in transport activity due to the YEA4 overexpression is specific for UDP-GlcNAc, but not for UDP-galactose and GDPmannose. ⌬yea4-disrupted cells showed a reduced rate of UDP-GlcNAc transport, contained less chitin, and were larger and rounder in shape than the wild type cells. Our results indicate that YEA4 encodes an ERlocalized UDP-GlcNAc transporter that is required for cell wall chitin synthesis in S. cerevisiae.The cell wall of Saccharomyces cerevisiae is composed of three types of polysaccharides: mannoprotein, ␤-glucan, and chitin. Chitin, a linear homopolymer of ␤-1,4-linked N-acetylglucosamine (GlcNAc) residues, is a relatively minor component, representing only 1-2% of the dry weight of the wall of vegetative cells (1). The biosynthesis of mannoprotein polysaccharides is well established; it initiates in the ER 1 and continues in the Golgi with the transfer of additional mannose units (2). ␤-Glucan synthesis is believed to take place along the secretory pathway in the ER and Golgi compartments and in the plasma membrane (3-5). In contrast, chitin synthesis is a complex process and not yet well understood (6 -8), although the enzymatic synthesis of chitin has been studied extensively (9). Chitin synthesis requires the activities of several different chitin synthases and many different genes for the control of these enzymes (10).S. cerevisiae possesses three chitin synthases. Chitin synthases I and II (CSI and CSII), the products of the CHS1 and CHS2, are closely related proteins and require partial proteolysis for their activity in vitro. In contrast, chitin synthase III (CSIII), the product of CHS3 (recently renamed from CAL1/ CSD2/DIT101/KTI2; Ref. 3), is active without proteolytic treatment and is presumed to be the catalytic subunit of a complex containing the CHS4 (CAL2/CSD4) and CHS5 (CAL3) gene products, which are believed to play regulatory roles (10 -12). The three chitin synthases have unique functions. CSI and CSII make only a small portion (Ͻ10%) of the total chitin, whereas CSIII is responsible for the remainder (Ͼ90%). Hydropathy analysis of the Chs1p, Chs2p, and Chs3p sequences reveals the presence of putative multimembrane-spanning domains in each polyp...

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