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 Files; chip 618 (12-7-05) and chip 623 (1-20-06) are replicates. One channel is root cDNA from Centaurea maculosa grown in isolation and the other channel is root cDNA from Centaurea maculosa grown with a strong competitor, Gaillardia aristata. For each chip, RNA extractions on unique biological samples were performed. Files; chip 720 (2-23-06) and chip 723 (3-17-06) are replicates. One channel is root cDNA from Centaurea maculosa grown in isolation and the other channel is root cDNA from Centaurea maculosa grown with a weak competitor, Festuca idahoensis. For each chip, RNA extractions on unique biological samples were performed.
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.