dictyNews Electronic Edition Volume 35, number 10 October 15, 2010 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 ========= Development of twelve polymorphic microsatellite markers from the social amoeba Dictyostelium giganteum suitable for genetic diversity studies on cellular slime moulds. Santosh Sathe1*, Albert Lalremruata2, Ramesh K Aggarwal2 1Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India. 2Centre for Cellular and Molecular Biology, Hyderabad 500007, India. (*E-mail: santosh_sathe@ces.iisc.ernet.in) Molecular Ecology Resources, in press Knowledge of the genetic structure of social groups formed by cellular slime mould amoebae is essential for understanding the importance of genetic relatedness in the evolution of their social behaviour. Only a few studies have examined genetic heterogeneity in naturally-occurring cellular slime mould groups, and they have been restricted to Dictyostelium discoideum, D. giganteum and D. purpureum. Part of the reason for this state of affairs is the paucity of genetic markers. We have developed twelve new microsatellite DNA markers from a partial genomic DNA library of D. giganteum. We studied the utility of these markers by genotyping the DNA isolated from 57 strains of cellular slime moulds. Most of the strains belonged to D. giganteum; the rest were D. macrocephalum, D. discoideum, D. purpureum, D. mucoroides, D. rosarium and Polysphondylium pallidum. The markers successfully amplified DNA from all the species listed above and yielded 2 to 9 alleles per marker. The high levels of polymorphism seen and the fact that DNA from several species could be amplified show that the markers are well-suited for addressing questions related to species relationships, genetic diversity and kinship in the cellular slime moulds. Submitted by Santosh Sathe [santosh_sathe@ces.iisc.ernet.in] -------------------------------------------------------------------------------- Prolyl hydroxylation- and glycosylation-dependent functions of Skp1 in O2-regulated development of Dictyostelium Zhuo A. Wang, Divyendu Singha, Hanke van der Wel, and Christopher M. West Department of Biochemistry and Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104 USA Devel. Biol., in press O2 regulates multicellular development of the social amoeba Dictyostelium, suggesting it may serve as an important cue in its native soil environment. Dictyostelium expresses an HIFalpha-type prolyl 4-hydroxylase (P4H1) whose levels affect the O2-threshold for culmination implicating it as a direct O2-sensor, as in animals. But Dictyostelium lacks HIFalpha, a mediator of animal prolyl 4-hydroxylase signaling, and P4H1 can hydroxylate Pro143 of Skp1, a subunit of E3SCFubiquitin-ligases. Skp1 hydroxyproline then becomes the target of five sequential glycosyltransferase reactions that modulate the O2-signal. Here we show that genetically induced changes in Skp1 levels also affect the O2-threshold, in opposite direction to that of the modification enzymes suggesting that the latter reduce Skp1 activity. Consistent with this, overexpressed Skp1 is poorly hydroxylated and Skp1 is the only P4H1 substrate detectable in extracts. Effects of Pro143 mutations, and of combinations of Skp1 and enzyme level perturbations, are consistent with pathway modulation of Skp1 activity. However, some effects were not mirrored by changes in modification of the bulk Skp1 pool, implicating a Skp1 subpopulation and possibly additional unknown factors. Altered Skp1 levels also affected other developmental transitions in modification-dependent fashion. Whereas hydroxylation of animal HIFalpha results in its polyubiquitination and proteasomal degradation, Dictyostelium Skp1 levels were little affected by its modification status. These data indicate that Skp1 and possibly E3SCFubiquitin-ligase activity modulate O2-dependent culmination and other developmental processes, and at least partially mediate the action of the hydroxylation/glycosylation pathway in O2-sensing. Submitted by Chris West [Cwest2@ouhsc.edu] ============================================================== [End dictyNews, volume 35, number 10]