dictyNews Electronic Edition Volume 39, number 10 April 5, 2013 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of dictyNews, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. Follow dictyBase on twitter: http://twitter.com/dictybase ========= Abstracts ========= Dictyostelium genes dysregulated in an O-glycosylation mutant identified by mRNA differential display Motonobu Yoshida, Naoya Sakuragi, Eiji Tanesaka, Yutaka Sendai Lab of Plant Breeding and Agrobiotechnology, Department of Agricultural Science, Kinki University, Nakamachi 3327-204, Nara 631-8505, Japan J. Biotechnol. Biomater. doi:10.4172/2155-952X.1000152, in press Seven differentially-expressed cDNA clones were isolated by using an mRNA differential display between a Dictyostelium wild-type AX2 and a mutant HG794 defective in O-glycosylation. Transcript levels for the seven clones were reduced or not detectable in the mutant HG794. Homology search showed that the four cDNA clones, DD-3 and DD-7~9 are novel and that three cDNA clones, DD-4 and DD-5, -6 encode an actin- bundling protein and phosphodiesterase inhibitors, respectively. Full-length cDNAs for DD-3 and -8 were isolated and labeled DD3-3 and DD8-14, respectively. DD3-3 consists of 2,166 bp and DD8-14 of 2,084 bp. DD3-3 was preliminarily reported in a previous paper (Sakuragi et al., 2005). SSL850 was named a clone by the "Dictyostelium cDNA Project in Japan", containing a full-length cDNA for DD-7 and was labeled DD7-1 of 902 bp. It has 60% homology with discoidin Ia. DD8-14 most likely has no direct role in glycosylation, while DD3-3 and DD7-1 very likely are involved in some aspect of recognition of glycosylation. Submitted by Motonobu Yoshida [yoshida_m@nara.kindai.ac.jp] --------------------------------------------------------------------------- Dictyostelium discoideum SecG interprets cAMP mediated chemotactic signals to influence actin organization Rebecca Garcia, Liem Nguyen, and Derrick Brazill Cytoskeleton, in press Tight control of actin cytoskeletal dynamics is essential for proper cell function and survival. ARNO, a mammalian guanine nucleotide exchange factor for Arf, has been implicated in actin cytoskeletal regulation but its exact role is still unknown. To explore the role of ARNO in this regulation as well as in actin-mediated processes, the Dictyostelium discoideum homolog, SecG, was examined. SecG peaks during aggregation and mound formation. The overexpression of SecG arrests development at the mound stage. SecG overexpressing (SecG OE) cells fail to stream during aggregation. Although carA is expressed, SecG OE cells do not chemotax toward cAMP, indicating SecG is involved in the cellular response to cAMP. This chemotactic defect is specific to cAMP-directed chemotaxis, as SecG OE cells chemotax to folate without impairment and exhibit normal cell motility. The chemotactic defects of the SecG mutants may be due to an impaired cAMP response as evidenced by altered cell polarity and F-actin polymerization after cAMP stimulation. Cells overexpressing SecG have increased filopodia compared to wild type cells, implying that excess SecG causes abnormal organization of F-actin. The general function of the cytoskeleton, however, is not disrupted as the SecG OE cells exhibit proper cell-substrate adhesion. Taken together, the results suggest proper SecG levels are needed for appropriate response to cAMP signaling in order to coordinate F-actin organization during development. Submitted by Derrick Brazill [brazill@genectr.hunter.cuny.edu] ============================================================== [End dictyNews, volume 39, number 10]