Townsend SR et al. (1994) Worm Breeder's Gazette "C. elegans Molecular Genetics and Long PCR."

Finelli AL, Savage C, Xie T, Padgett RW, Townsend SR

[Worm Breeder's Gazette, 1994]

C. elegans Molecular Genetics and Long PCR Scott R. Townsend, Cathy Savage, Alyce L. Finelli, Ting Xie, and Richard W. Padgett, Waksman Institute and Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ 08855

Gaydos, Laura et al. (2013) International Worm Meeting "Epigenetic regulation of fertility in C. elegans males depends on the gamete source and chromatin history of the X chromosome."

Gaydos, Laura, Wang, Wenchao, Strome, Susan, Rechtsteiner, Andreas

[International Worm Meeting, 2013]

Organisms with different numbers of X chromosomes in the two sexes have evolved diverse strategies to regulate X-linked gene expression. Somatic cells compensate for the difference in X dosage by inactivating one X in XX mammals, down-regulating both Xs in XX C. elegans, or up-regulating the single X in XY Drosophila. Germ cells in C. elegans display a more extreme type of regulation, near silencing of both Xs in XX hermaphrodites and the single X in XO males. X repression in the germline is achieved at least in part by the MES proteins, epigenetic regulators that must be maternally provided to progeny to ensure survival of the primordial germ cells. In the adult germline, the MES-2/3/6 complex, which is the worm version of Polycomb Repressive Complex 2, concentrates a repressive histone modification (H3K27me) on the Xs. MES-4 participates in X repression in an indirect manner. MES-4 catalyzes a mark of active chromatin (H3K36me) on germline-expressed genes on autosomes; this repels H3K27me from autosomal regions and helps concentrate H3K27me on the Xs. Recent investigation of whether the MES proteins participate in repression of the single X in XO males has revealed that the answer depends on the gamete source of the X. Maternal MES function is required when the X in males is inherited from the oocyte but not when the X is inherited from the sperm. In the latter case, X repression appears to be mediated by enzymes that generate the repressive histone modification H3K9me. Our studies have shown that the opposing activities of MES-2/3/6 and MES-4 repress transcription from the two Xs in XX germ cells, and that in XO germ cells H3K9me can serve as another mode of repression.

Hajdu-Cronin YM et al. (1998) West Coast Worm Meeting "MUTATIONS AFFECTING SPECIFIC ASPECTS OF MOVEMENT IN C. ELEGANS"

Chen W, Sternberg PW, Hajdu-Cronin YM

[West Coast Worm Meeting, 1998]

Mutations in the C. elegans Go and Gq pathways affect several behaviors, including egg laying and movement. Hyperactive mutants such as goa-1(lf) and syEx125[egl-30(xs)] affect both speed as well as wavelength and amplitude of tracks and are egg laying constitutive. In contrast, sluggish mutations such as egl-30(rf) and syIs9[goa-1(Q205L)] move very slowly, leave tracks with reduced amplitude, and are egg laying defective (1, 2, 3). Since goa-1 is broadly expressed in the nervous system, it is possible that the various aspects of movement affected by Go mutations represent distinct, separable behavioral pathways. Mutations affecting specific aspects of movement are desirable for separating and studying these pathways. Here we present two EMS-generated mutations which apparently affect amplitude of tracks but not speed. sy415 animals leave tracks with increased amplitude, similar to egl-30(xs) animals, but do not exhibit the constitutive egg laying, frequent backing and hyperactivity associated with egl-30(xs) and goa-1(lf). Animals bearing the sy551 mutation leave flattened tracks, but are not sluggish or bloated. Currently we are cloning sy415, and we hope to isolate more mutations affecting specific aspects of movement. References cited: 1. Ségalat et al., Science 267: 1648-1651 (1995) 2. Mendel et al., Science 267: 1652-1655 (1995) 3. Brundage et al., Neuron 16: 999-1009 (1996)

Xie M et al. (2016) PLoS Genet "Correction: The Causative Gene in Chanarian Dorfman Syndrome Regulates Lipid Droplet Homeostasis in C. elegans."

Xie M, Roy R

[PLoS Genet, 2016]

[This corrects the article DOI: 10.1371/journal.pgen.1005284.]. In the title of this article, the words Chanarian Dorfman should read Chanarin-Dorfman. The correct title is: The Causative Gene in Chanarin-Dorfman Syndrome Regulates Lipid Droplet Homeostasis in C. elegans. The correct citation is: Xie M, Roy R (2015) The Causative Gene in Chanarin-Dorfman Syndrome Regulates Lipid Droplet Homeostasis in C. elegans. PLoS Genet 11(6): e1005284. doi:10.1371/journal.pgen.1005284

Wang MC et al. (2011) Nat Methods "RNAi screening for fat regulatory genes with SRS microscopy."

Wang MC, Min W, Freudiger CW, Xie XS, Ruvkun G

[Nat Methods, 2011]

Identification of genes regulating fat accumulation is important for basic and medical research; genetic screening for those genes in Caenorhabditis elegans, a widely used model organism, requires in vivo quantification of lipids. We demonstrated RNA interference screening based on quantitative imaging of lipids with label-free stimulated Raman scattering (SRS) microscopy, which overcomes major limitations of coherent anti-Stokes Raman scattering microscopy. Our screening yielded eight new genetic regulators of fat storage.

Freudiger CW et al. (2011) Nat Photonics "Highly specific label-free molecular imaging with spectrally tailored excitation stimulated Raman scattering (STE-SRS) microscopy."

Freudiger CW, Xie XS, Dantus M, Xu B, Min W, Holtom GR

[Nat Photonics, 2011]

Label-free microscopy with chemical contrast and high acquisition speed up to video-rate has recently been made possible by stimulated Raman scattering (SRS) microscopy. While SRS imaging offers superb sensitivity, the spectral specificity of the original narrowband implementation is limited, making distinguishing chemical species with overlapping Raman bands difficult. Here we present a highly specific imaging method that allows mapping of a particular chemical species in the presence of interfering species based on tailored multiplex excitation of its vibrational spectrum. This is done by spectral modulation of a broadband pump beam at a high-frequency (>1MHz), allowing detection of the stimulated Raman gain signal of the narrowband Stokes beam with high sensitivity. Using the scheme, we demonstrate quantification of cholesterol in the presence of lipids, and real-time three-dimensional spectral imaging of protein, stearic acid and oleic acid in live C. elegans.

Laurel Bender et al. (2002) Mid-west Worm Meeting "Regulation of the different chromatin states of autosomes and X chromosomes in the germ line of C. elegans."

Susan Strome, Youyi Fong, Wenchao Wang, Laurel Bender

[Mid-west Worm Meeting, 2002]

Recent observations support the hypothesis that in the C. elegans germ line, the X chromosomes differ in chromatin state from the autosomes and are globally repressed during most of germline development. Specifically, microarray analysis of genes whose expression is enriched in the germ line revealed that genes involved in germline proliferation, meiosis, and spermatogenesis are virtually absent from the X chromosome (1). Also, histone modifications correlated with active gene expression are present on the autosomes but not detected on the Xs in the germ line (2,3).

Sharma R et al. (2014) Genes Dev "Differential spatial and structural organization of the X chromosome underlies dosage compensation in C. elegans."

Kind J, Vaillant C, Meister P, Jost D, Askjaer P, Sharma R, Gomez-Saldivar G, van Steensel B

[Genes Dev, 2014]

The adjustment of X-linked gene expression to the X chromosome copy number (dosage compensation [DC]) has been widely studied as a model of chromosome-wide gene regulation. In Caenorhabditis elegans, DC is achieved by twofold down-regulation of gene expression from both Xs in hermaphrodites. We show that in males, the single X chromosome interacts with nuclear pore proteins, while in hermaphrodites, the DC complex (DCC) impairs this interaction and alters X localization. Our results put forward a structural model of DC in which X-specific sequences locate the X chromosome in transcriptionally active domains in males, while the DCC prevents this in hermaphrodites.

Lau AC et al. (2015) Curr Opin Genet Dev "Balancing up and downregulation of the C. elegans X chromosomes."

Lau AC, Csankovszki G

[Curr Opin Genet Dev, 2015]

In Caenorhabditis elegans, males have one X chromosome and hermaphrodites have two. Emerging evidence indicates that the male X is transcriptionally more active than autosomes to balance the single X to two sets of autosomes. Because upregulation is not limited to males, hermaphrodites need to strike back and downregulate expression from the two X chromosomes to balance gene expression in their genome. Hermaphrodite-specific downregulation involves binding of the dosage compensation complex to both Xs. Advances in recent years revealed that the action of the dosage compensation complex results in compaction of the X chromosomes, changes in the distribution of histone modifications, and ultimately limiting RNA Polymerase II loading to achieve chromosome-wide gene repression.

Fu D et al. (2014) J Am Chem Soc "In vivo metabolic fingerprinting of neutral lipids with hyperspectral stimulated Raman scattering microscopy."

Xie XS, Yu Y, Fu D, Currie E, Farese Jr RV, Folick A, Tsai TH, Wang MC

[J Am Chem Soc, 2014]

Metabolic fingerprinting provides valuable information on the physiopathological states of cells and tissues. Traditional imaging mass spectrometry and magnetic resonance imaging are unable to probe the spatial-temporal dynamics of metabolites at the subcellular level due to either lack of spatial resolution or inability to perform live cell imaging. Here we report a complementary metabolic imaging technique that is based on hyperspectral stimulated Raman scattering (hsSRS). We demonstrated the use of hsSRS imaging in quantifying two major neutral lipids: cholesteryl ester and triacylglycerol in cells and tissues. Our imaging results revealed previously unknown changes of lipid composition associated with obesity and steatohepatitis. We further used stable-isotope labeling to trace the metabolic dynamics of fatty acids in live cells and live Caenorhabditis elegans with hsSRS imaging. We found that unsaturated fatty acid has preferential uptake into lipid storage while saturated fatty acid exhibits toxicity in hepatic cells. Simultaneous metabolic fingerprinting of deuterium-labeled saturated and unsaturated fatty acids in living C. elegans revealed that there is a lack of interaction between the two, unlike previously hypothesized. Our findings provide new approaches for metabolic tracing of neutral lipids and their precursors in living cells and organisms, and could potentially serve as a general approach for metabolic fingerprinting of other metabolites.