Samuel, Tamika et al. (2009) International Worm Meeting "Characterization of the C. elegans ionome."

Lahner, Brett, Salt, David, Samuel, Tamika, Hamza, Iqbal

[International Worm Meeting, 2009]

The ionome is defined as the complete elemental compositions of an organism, including essential mineral nutrients and trace elements. Ionomics, the study of the ionome, is utilized to uncover the genes and gene networks that regulate the ionome and the physiological stimuli that affect these networks. In ionomics, high throughput elemental analysis is integrated with genetics, genomics, and bioinformatics to gain a comprehensive picture of the ionome of an organism. Because of its invariant and precise somatic cell lineages, C. elegans is an excellent experimental model system to apply the concept of ionomics to gene networks within an intact animal. Wild-type N2 worms were grown axenically in modified CeHR liquid medium to mid L4 stage, collected on cellulose filters, and dried before analysis by inductively coupled plasma-mass spectrometry (ICP-MS) at the Purdue Ionomics Center. Using this approach, we have been able to precisely quantify the concentration of P, Ca, K, Mg, Cu, Fe, Zn, Mn, Co, Ni, B, Se, Mo, Na, As, and Cd in C. elegans. Our ultimate goals are to superimpose the ionome network with the regulatory circuit which defines developmental processes in an animal by combining functional ionomics with genome-wide RNAi screens.

Young-Il Kim et al. (2003) International Worm Meeting "Isolation and characterization of deletion mutant of cytosolic aconitase in C. elegans"

Young-Il Kim, Joohong Ahnn

[International Worm Meeting, 2003]

Cytosolic aconitase converts citrate into isocitrate and regulates iron concentration in the cytosol. In mammals, cytosolic aconitase is known as iron regulation protein (IRP), because it controls the expression of ferritin, which is an iron binding protein. IRP normally represses the translation of ferritin mRNA by binding to its 5'UTR. In high cytosolic iron, IRP is released from ferritin mRNA so the translation of the ferritin is increased. Previously, C. elegans cytosolic aconitase (ACO-1) has been cloned and characterized (ref. Brett L. Gourley et al (2002) J. Biol. Chem.). Interestingly, this study reported that C. elegans cytosolic aconitase (ACO-1) does not bind to ferritin mRNA (ftn-1, 2). Nevertheless, the expression level of aco-1 and ftn-1, 2 is increased when worms were cultivated at high iron concentration. In addition, the life span of N2 was reduced where they grow on the iron-supplemented plates. We have recently isolated a deletion mutant of aco-1 (jh131). It contains a 1.5Kb deletion, which covers from the 950bp upstream of the first exon to the part of third exon. Although it appears to be a null mutant, nut homozygote shows normal development suggesting aco-1 may not be essential for development. We are currently characterizing the detailed phenotypes of this mutant to study the function of cytosolic aconitase.

Brett Roberts et al. (2006) European Worm Meeting "Investigation of Interactions between Mutant Collagens Using C. elegans as a Model Organism"

Genevieve Stapleton, Brett Roberts, Iain Johnstone

[European Worm Meeting, 2006]

Brett Roberts, Genevieve Stapleton and Iain Johnstone. Extracellular matrix (ECM) provides the structural basis of tissues and organs in animals. Collagen proteins form a diverse range of supramolecular components in ECM and mutations in various human collagen genes which result either in a reduction or loss of a collagen species from the ECM, or in some cases insertion of mutant collagen, are responsible for a wide variety of inherited diseases, including osteogenesis imperfecta, Ehlers-Danlos Syndrome and some forms of osteoporosis, osteoarthritis and invertebral disc disease. Excessive collagen synthesis is also detrimental resulting in fibrosis.. In C. elegans the cuticle is an ECM comprised primarily of collagens, encoded by a large gene family, which interact to form distinct substructures within the cuticle. Previously we have demonstrated specific requirements for collagen partners during assembly of cuticle collagen sub-structures. We observe distinct differences between the behaviour of certain classes of mutant collagen. The most common class, Gly substitution mutants within the repetitive Gly-X-Y domains cause retention of the mutant collagen in the ER. However null mutations in some cuticle collagen genes result in neither assembly nor ER retention of obligate partner collagens. We are interested in studying the fate of this partnerless collagen; various approaches will be presented.. We are also interested in the retention of Gly sub collagen in the ER. We have performed a mutant screen in a dpy-7(e88) glycine substitution mutant background to identify modifiers of the dpy-7(e88) phenotype. Two classes of mutants have been isolated: those that significantly enhance the severity of the dpy-7(e88) phenotype, resulting in shorter, fatter animals; and those that display a distinct Roller modifier phenotype. Our preliminary analyses of these new modifier alleles will be described.