Project description:Competition is a major determinant of plant community structure consisting of both species-specific and general interactions, either of which may influence competitive competency and plant abundance and size. In certain cases, competitive competency could arise from altered gene expression and plant function when an individual is confronted with new competitors. We explored competition at the molecular level by hybridizing transcripts from Centaurea maculosa (spotted knapweed), one of North America's most invasive exotic plant species, to an Arabidopsis microarray chip. Centaurea was grown in competition with Festuca idahoensis (Idaho fescue), a native grass species that generally has weak competitive effects against Centaurea; Gaillardia aristata (Indian blanketflower), a native herbaceous species that tends to be a much stronger competitor against Centaurea; or alone (control). The expression of some genes was found to be relatively uninfluenced by the type of plant neighbor, whereas other patterns of gene expression appeared to be more neighbor specific. To our knowledge, these results are the first to identify genes in an invasive plant that are induced or repressed by plant neighbors and provide a new avenue of insight into the molecular aspects of plant competitive ability. Keywords: treated vs.untreated First file, Chip 508 (9-9-05) is preliminary hyb data to see if this cross species hybridization is possible using the OAR27K chip Experiment 1 (chip 508): The Arabidopsis OAR27K gene chip was hybridized with labeled cDNA probes produced from samples of Centaurea RNA at the W.M. Keck Foundation Biotechnology Resource Laboratory, Yale University. The OAR27K gene chip consists of 70-mer oligos representing approximately 27,000 genes from Arabidopsis. Leaf and root samples were reverse-transcribed into cDNA and labeled with different fluorescent dyes (Cy3 and Cy5) using the Genisphere Array 900 kit (Cat No.W500180) (Genisphere, Hatfield PA). Labeled cDNAs were hybridized to the OAR27Kchip using the Advalytix ArrayBooster DNA Microarray Incubator (Advalytix, Boston MA). Approximately 10ug of each sample was used for hybridization.Experiment 2: Hybridization and labeling followed the procedure above, except the experimental control was Centaurea plants grown alone, and the test situations were Centaurea grown with Gaillardia or Festuca neighbors. In each experiment, RNA from Centaurea grown alone was used as the control (labeled with Cy3) and RNA from Centaurea grown with a neighbor was used as the test (labeled with Cy5). Two replicates were performed for each test situation.

Project description:This study provides comprehensive proteomic profiles from the venom producing posterior salivary glands of Octopus (superorder Octopodiformes) species. A combined transcriptomic and proteomic approach was used to identify 1,703 proteins from the posterior salivary gland of the southern blue ring octopus, Hapalochlaena maculosa and 1,300 proteins from the posterior salivary gland of the southern sand octopus, Octopus kaurna. The two proteomes were broadly similar, clustering of proteins into orthogroups revealed 1,563 of 2,466 clusters were shared between species. Serine proteases were particularly diverse and abundant in both species. Other abundant proteins included a large number of secreted proteins many of which had no known conserved domains, or homology to proteins with known function. Based on homology to known venom proteins, 23 putative toxins were identified in H. maculosa and 24 in O. kaurna. These toxins span nine protein families: CAP (cysteine rich secretory proteins, antigen 5, parthenogenesis related), chitinase, carboxylesterase, DNase, hyaluronidase, metalloprotease, phospholipase, serine protease and tachykinin. Serine proteases were responsible for 70.9% and 86.3% of putative toxin expression in H. maculosa and O. kaurna respectively as determined using intensity based absolute quantification measurements. Phylogenetic analysis of the putative toxin serine proteases revealed a similar suite of diverse proteins present in both species. Venom composition H. maculosa and O. kaurna differ in several key aspects. While O. kaurna expressed the proteinaceous neurotoxin, tachykinin, this was absent from H. maculosa, perhaps reflecting the acquisition of a potent non-proteinaceous neurotoxin, tetrodotoxin (TTX) produced by bacteria in the salivary glands of that species. Dispersal factors particularly hyaluronidase, were disproportionately high in H. maculosa. Chitinase was abundant in both species and is believed to facilitate envenomation in chitinous/crustacean prey. Cephalopods represent a largely unexplored source of novel proteins distinct from all other venomous taxa and are of interest for further inquiry as novel proteinaceous toxins derived from venoms may contribute to pharmaceutical design.

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Hapalochlaena maculosa

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