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[
Traffic,
2005]
Hermansky-Pudlak syndrome (HPS) is a rare disorder caused by malfunctions of lysosomes and specialized lysosome-related organelles, resulting primarily in oculocutaneous albinism and bleeding diathesis. The majority of the HPS genes have been described as novel, but herein we report the identification of a conserved protein family which includes human HPS4, as well as distant homologs for other HPS genes. Our results suggest that the cellular machinery involved in the HPS syndrome is ancient.
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[
Worm Breeder's Gazette,
1994]
Evolution of vulva-formation: Part II: Species with a central vulva Ralf J. Sommer & Paul W. Sternberg, California Institute of Technology, Division of Biology 156-29, Pasadena, CA 91125
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[
Worm Breeder's Gazette,
1994]
Evolution of vulva formation: Part IV: Variation in AC position can cause a shift of vulva formation towards p(4- 6).p Ralf J. Sommer & Paul W. Sternberg, HHMI & California Institute of Technology, Division of Biology 156-29, Pasadena, CA
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[
Biochemistry,
2012]
Decapping scavenger (DcpS) enzymes catalyze the cleavage of a residual cap structure following 3' 5' mRNA decay. Some previous studies suggested that both m(7)GpppG and m(7)GDP were substrates for DcpS hydrolysis. Herein, we show that mononucleoside diphosphates, m(7)GDP (7-methylguanosine diphosphate) and m(3)(2,2,7)GDP (2,2,7-trimethylguanosine diphosphate), resulting from mRNA decapping by the Dcp1/2 complex in the 5' 3' mRNA decay, are not degraded by recombinant DcpS proteins (human, nematode, and yeast). Furthermore, whereas mononucleoside diphosphates (m(7)GDP and m(3)(2,2,7)GDP) are not hydrolyzed by DcpS, mononucleoside triphosphates (m(7)GTP and m(3)(2,2,7)GTP) are, demonstrating the importance of a triphosphate chain for DcpS hydrolytic activity. m(7)GTP and m(3)(2,2,7)GTP are cleaved at a slower rate than their corresponding dinucleotides (m(7)GpppG and m(3)(2,2,7)GpppG, respectively), indicating an involvement of the second nucleoside for efficient DcpS-mediated digestion. Although DcpS enzymes cannot hydrolyze m(7)GDP, they have a high binding affinity for m(7)GDP and m(7)GDP potently inhibits DcpS hydrolysis of m(7)GpppG, suggesting that m(7)GDP may function as an efficient DcpS inhibitor. Our data have important implications for the regulatory role of m(7)GDP in mRNA metabolic pathways due to its possible interactions with different cap-binding proteins, such as DcpS or eIF4E.
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[
J Infect Dis,
2015]
BACKGROUND: Elimination of onchocerciasis and lymphatic filariasis is targeted for 2020. Given the coincident Loa loa infections in Central Africa and the potential for drug resistance development, the need for new microfilaricides and macrofilaricides has never been greater. With the genomes of L. loa, Onchocerca volvulus, Wuchereria bancrofti, and Brugia malayi available, new drug targets have been identified. METHODS: The effects of the tyrosine kinase inhibitors imatinib, nilotinib, and dasatinib on B. malayi adult males, adult females, L3 larvae, and microfilariae were assessed using a wide dose range (0-100 M) in vitro. RESULTS: For microfilariae, median inhibitory concentrations (IC50 values) on day 6 were 6.06 M for imatinib, 3.72 M for dasatinib, and 81.35 M for nilotinib; for L3 larvae, 11.27 M, 13.64 M, and 70.98 M, respectively; for adult males, 41.6 M, 3.87 M, and 68.22 M, respectively; and for adult females, 42.89 M, 9.8 M, and >100 M, respectively. Three-dimensional modeling suggests how these tyrosine kinase inhibitors bind and inhibit filarial protein activity. CONCLUSIONS: Given the safety of imatinib in humans, plans are underway for pilot clinical trials to assess its efficacy in patients with filarial infections.
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[
European Worm Meeting,
2000]
More than 50 genes involved in vulva development have been characterized in the rhabditid C. elegans. The extensive characterization of this model system provides a framework for studying the genetic basis of evolutionary modifications. Cell fate specification during vulva formation differs significantly between C. elegansand the diplogasterid nematode Pristionchus pacificus. Cell ablation experiments in P. pacificus demonstrate the existence of several novel cell-cell interactions (Sigrist and Sommer, 1999; Sommer and Sternberg, 1996). To understand the molecular mechanisms underlying vulval pattern formation in P. pacificus, we performed several TMP/UV and EMS mutagenesis screens. The mutants isolated in these screens fall into two categories: I) "generation-vulvaless" mutants do not generate Pn.p cells; II) "induction-vulvaless" mutants generate Pn.p cells, but these fail to differentiate. We have isolated and characterized a new class of induction vulvaless mutants, in which P6.p differentiates as a normal 1 cell, but P5.p and P7.p adopt a non-vulval fate (3). In wild type P. pacificus, as in C. elegans, P6.p adopts the 1 fate, whereas P5.p and P7.p generate the 2 lineage. Four mutants,
tu114(TMP/UV),
tu132(EMS),
tu48(EMS) and
tu51 (EMS), display this defect to different extents. Complementation test among these mutants are in progress. We are using a PCR-based genomic substraction strategy (RDA) to identify the deletion associated with the
tu114 mutant. The identification of the genes involved in the induction of the vulva in P. pacificus may help us understand how molecular mechanisms change during evolution. Sigrist, C. B., and Sommer, R. J. (1999). Vulva formation in Pristionchus pacificus relies on continuous gonadal induction. Dev Genes Evol 209, 451-9. Sommer, R. J., and Sternberg, P. W. (1996). Apoptosis and change of competence limit the size of the vulva equivalence group in Pristionchus pacificus: a genetic analysis. Curr Biol 6, 52-9.
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[
European Worm Meeting,
2000]
More than 50 genes involved in vulva development have been characterized in the rhabditid C. elegans. The extensive characterization of this model system provides a framework for studying the genetic basis of evolutionary modifications. Cell fate specification during vulva formation differs significantly between C. elegansand the diplogasterid nematode Pristionchus pacificus. Cell ablation experiments in P. pacificus demonstrate the existence of several novel cell-cell interactions (Sigrist and Sommer, 1999; Sommer and Sternberg, 1996). To understand the molecular mechanisms underlying vulval pattern formation in P. pacificus, we performed several TMP/UV and EMS mutagenesis screens. The mutants isolated in these screens fall into two categories: I) "generation-vulvaless" mutants do not generate Pn.p cells; II) "induction-vulvaless" mutants generate Pn.p cells, but these fail to differentiate. We have isolated and characterized a new class of induction vulvaless mutants, in which P6.p differentiates as a normal 1 cell, but P5.p and P7.p adopt a non-vulval fate (3). In wild type P. pacificus, as in C. elegans, P6.p adopts the 1 fate, whereas P5.p and P7.p generate the 2 lineage. Four mutants,
tu114 (TMP/UV),
tu132 (EMS),
tu48 (EMS) and
tu51 (EMS), display this defect to different extents. Complementation test among these mutants are in progress. We are using a PCR-based genomic substraction strategy (RDA) to identify the deletion associated with the
tu114 mutant. The identification of the genes involved in the induction of the vulva in P. pacificus may help us understand how molecular mechanisms change during evolution. Sigrist, C. B., and Sommer, R. J. (1999). Vulva formation in Pristionchus pacificus relies on continuous gonadal induction. Dev Genes Evol 209, 451-9. Sommer, R. J., and Sternberg, P. W. (1996). Apoptosis and change of competence limit the size of the vulva equivalence group in Pristionchus pacificus: a genetic analysis. Curr Biol 6, 52-9.
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[
International Worm Meeting,
2013]
Embryo development requires precise coordination of mechanical forces and their failure can lead to diseases. During the morphogenesis of C. elegans embryo, the cooperation of epidermal acto-myosin network and muscle contractions is essential. The acto-myosin activity in the epidermis, which has been shown to be more important in lateral than in dorsal-ventral cells, squeeze the embryo and make it elongate [1]. Muscle contractions become active around 1.7-1.8 fold stage. They have been showed to induce a mechano-transduction pathway [2], which is important for elongation. However, it is unclear how the contractions along the anterior-posterior axis help to increase the length of the embryo. Our project aims to elucidate the mechanical role of muscle contractions and its coordination with acto-myosin forces. The experiments are designed following a working model where muscle contractions induce a change in the elasticity of the embryo. We are using a laser nano-dissection technique to investigate cortical tension and elasticity of epidermal cells before and after the onset of muscle contractions. In parallel, we are evaluating the relative changes of acto-myosin forces with a FRET sensor [3] inserted in HMP-1 - a component of the adherens junctions. I will present our observations and preliminary results of the epidermal cortex nano-dissection experiments and measures of acto-myosin forces exerted on adherens junctions. References 1.Gally C, Wissler F, Zahreddine H, Quintin S, Landmann F, Labouesse M. Myosin II regulation during C. elegans embryonic elongation: LET-502/ROCK, MRCK-1 and PAK-1, three kinases with different roles. Development. 2009 Sep;136(18):3109-19. Epub 2009 Aug 12. 2.Zhang H, Landmann F, Zahreddine H, Rodriguez D, Koch M, Labouesse M. A tension-induced mechanotransduction pathway promotes epithelial morphogenesis. Nature. 2011 Mar 3;471(7336):99-103. 3.Grashoff C, Hoffman B, Brenner M, Zhou R, Parsons M, Yang M, McLean M, Sligar S, Chen C, Ha T, Schwartz M. Measuring mechanical tension across vinculin reveals regulation of focal adhesion dynamics. Nature. 2010 July 8; 466(7303): 263-266.
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[
Worm Breeder's Gazette,
1976]
We have studied maternal effects in 23 zyg ts mutants to estimate the times of expression of genes whose products are required in embryogenesis. We have used the following three tests, called arbitrarily A, B, and C. A test: Heterozygous (m/+) L4's are shifted to 25 C and allowed to self-fertilize. If 100% of their eggs yield larvae (25% of which express the mutant phenotype as adults), then the mutant is scored as maternal (M). If 25% of the F1 eggs fail to hatch, then the mutant is scored as non-maternal (N). An M result indicates that expression of the + allele in the parent allows m/m zygotes to hatch and grow to adulthood. A result of N indicates the opposite: that the + allele must be expressed in the zygote for hatching to occur. Out of 23 zyg mutants tested, 3 were scored N and 20 were scored M in the A test. Therefore, for most of the genes defined by these mutants, expression in the parent is sufficient for zygote survival, even if the gene is not expressed in the zygote. B test: Homozygous (m/m) hermaphrodites reared at 25 C are mated with N2 (+/+) males. If eggs fail to hatch at 25 C, but mated hermaphrodites shifted to 16 C produce cross progeny to give proof of mating, then the mutant is scored M. If cross progeny appear in the 25 C mating, then the mutant is scored N. An M result indicates that expression of the + allele in the zygote is not sufficient to allow m/+ progeny of an m/m hermaphrodite to survive. Conversely an N result indicates either that zygotic expression of the + allele is sufficient for survival, or that a sperm function or factor needed for early embryogenesis can be supplied paternally (see C test below). Out of the 23 zyg mutants tested, 11 were scored M and 12 were scored N. The combined results of A and B tests and their simplest interpretation are as follows. Ten mutants are M,M; the genes defined by these mutants must be expressed in the hermaphrodite parent for the zygote to survive. Ten mutants are M,N; these genes can be expressed either in the parent or in the zygote. Two mutants are N,N; these genes must be expressed in the zygote. One mutant is N,M; this gene must be expressed both in the maternal parent and in the zygote. C test: Homozygous (m/m) hermaphrodites reared at 25 C are mated with heterozygous (m/+) males. If rescue by a +/+ male in the B test depends on the + allele, then only half the cross progeny zygotes of a C test mating (m/+ male x m/m hermaphrodite) should survive. However, if rescue depends on a function or cytoplasmic component from the male sperm, then all the cross progeny zygotes in a C test should survive. Of the 10 M,N mutants, 6 have been C tested; one exhibited paternal rescue independent of the + allele. The A and B tests also were carried out on 16 mutants that arrest before the L3 molt (acc mutants). In the A test on 2 of these mutants, all m/m progeny of m/+ parents grew to adulthood at 25 C. Therefore, parental contributions are sufficient to overcome a progeny mutational block as late as the L2 stage. All 16 acc mutants scored N in the B test.
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[
Worm Breeder's Gazette,
1994]
cej-1 Encodes a Novel Protein with Poly-Threonine Motif M. L. A. Khanl, M. Tabish, T. Fukushigel1 S. Tsukita2, M. Itoh , Sh. Tsukita , and S. S. Siddiqui. (1): Lab. of Molecular Biology, Dept of Ecological Engg. Toyohashi Univ. Technology, Toyohashi 441, and (2). National Institute for Physiological Sciences, Okazaki 444, Japan.