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1.
Curr Biol ; 24(7): 760-5, 2014 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-24631238

RESUMO

Many neurodegenerative disorders are associated with mitochondrial defects [1-3]. Mitochondria can play an active role in degeneration by releasing reactive oxygen species and apoptotic factors [4-7]. Alternatively, mitochondria can protect axons from stress and insults, for example by buffering calcium [8]. Recent studies manipulating mitochondria lend support to both of these models [9-13]. Here, we identify a C. elegans mutant, ric-7, in which mitochondria are unable to exit the neuron cell bodies, similar to the kinesin-1/unc-116 mutant. When axons lacking mitochondria are cut with a laser, they rapidly degenerate. Some neurons even spontaneously degenerate in ric-7 mutants. Degeneration can be suppressed by forcing mitochondria into the axons of the mutants. The protective effect of mitochondria is also observed in the wild-type: a majority of axon fragments containing a mitochondrion survive axotomy, whereas those lacking mitochondria degenerate. Thus, mitochondria are not required for axon degeneration and serve a protective role in C. elegans axons.


Assuntos
Axônios/ultraestrutura , Caenorhabditis elegans/citologia , Mitocôndrias/fisiologia , Degeneração Neural , Animais , Axônios/fisiologia , Axotomia , Caenorhabditis elegans/fisiologia , Caenorhabditis elegans/ultraestrutura , Proteínas de Caenorhabditis elegans/genética , Cálcio/metabolismo , Mutação , Proteínas do Tecido Nervoso/genética , Doenças Neurodegenerativas , Espécies Reativas de Oxigênio/metabolismo
2.
Methods Cell Biol ; 107: 93-149, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22226522

RESUMO

From its inception as a model organism 40 years ago, Caenorhabditis elegans was chosen in part for its suitability for study in serial thin sections by electron microscopy. Recent improvements in electron microscopy technology are making this pursuit more reliable and more powerful. In this chapter, we highlight new methods in specimen preparation, imaging, and data analysis. Accurate three-dimensional information can now be obtained for the whole animal at all stages, down to the level of individual organelles and the cytoskeleton.


Assuntos
Caenorhabditis elegans/ultraestrutura , Citoesqueleto/ultraestrutura , Microscopia Eletrônica de Varredura/métodos , Organelas/ultraestrutura , Animais , Anticorpos Anti-Helmínticos , Microscopia Crioeletrônica/métodos , Tomografia com Microscopia Eletrônica/métodos , Fixadores , Substituição ao Congelamento , Processamento de Imagem Assistida por Computador/métodos , Imuno-Histoquímica , Microtomia , Micro-Ondas , Compostos Organometálicos , Inclusão do Tecido , Fixação de Tecidos
3.
Neuron ; 44(5): 795-807, 2004 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-15572111

RESUMO

Specialized extracellular matrix (ECM) is associated with virtually every mechanosensory system studied. C. elegans touch receptor neurons have specialized ECM and attach to the surrounding epidermis. The mec-1 gene encodes an ECM protein with multiple EGF and Kunitz domains. MEC-1 is needed for the accumulation of the collagen MEC-5 and other ECM components, attachment, and, separately, for touch sensitivity. MEC-1 and MEC-5 bind to touch processes uniformly and in puncta. These puncta colocalize with and localize the mechanosensory channel complex in the touch neurons. In turn, the production of the MEC-1 and MEC-5 puncta appears to rely on interactions with the neighboring epidermal tissue. These and other observations lead us to propose that extracellular, but not cytoskeletal, tethering of the degenerin channel is needed for mechanosensory transduction. Additionally, our experiments demonstrate an important role of the ECM in organizing the placement of the channel complex.


Assuntos
Proteínas de Caenorhabditis elegans/fisiologia , Caenorhabditis elegans/fisiologia , Proteínas da Matriz Extracelular/fisiologia , Mecanorreceptores/fisiologia , Tato/fisiologia , Alelos , Sequência de Aminoácidos , Animais , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Colágeno/metabolismo , Fator de Crescimento Epidérmico/genética , Proteínas da Matriz Extracelular/genética , Proteínas de Membrana/metabolismo , Dados de Sequência Molecular , Estrutura Terciária de Proteína , Distribuição Tecidual
4.
Curr Microbiol ; 46(1): 24-7, 2003 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-12432459

RESUMO

Aspergillus fumigatus NRRL 2346 is the producer of fumagillin, an antitumor antibiotic that inhibits angiogenesis. This strain is very difficult to grow reproducibly in shake flasks owing to an extreme form of pellet growth and extensive wall growth. The effects of carboxymethylcellulose (CMC) and carboxypolymethylene (Carbopol) on growth and fumagillin production by A. fumigatus were investigated. By adding the polymers to the fermentation medium, the growth form of the mold was changed from a single large glob to small reproducible pellets, and wall growth was diminished to a minimum. Carbopol, at a lower concentration, was more effective than CMC in improving both morphology and production. Small pellets were produced which favored fumagillin biosynthesis. 1.5% (wt/vol) CMC and 0.3% (wt/vol) Carbopol were found to be the optimum concentrations; higher levels increased viscosity to an unacceptable level.


Assuntos
Antibacterianos/biossíntese , Aspergillus fumigatus/efeitos dos fármacos , Carboximetilcelulose Sódica/farmacologia , Ácidos Graxos Insaturados/biossíntese , Polivinil/farmacologia , Resinas Acrílicas , Aspergillus fumigatus/citologia , Aspergillus fumigatus/metabolismo , Cicloexanos , Relação Dose-Resposta a Droga , Hifas/fisiologia , Sesquiterpenos , Esporos Fúngicos/fisiologia
5.
Proc Natl Acad Sci U S A ; 99(7): 4355-60, 2002 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-11904372

RESUMO

The misregulation of programmed cell death, or apoptosis, contributes to the pathogenesis of many diseases. We used Nomarski microscopy to screen for mutants containing refractile cell corpses in a C. elegans strain in which all programmed cell death is blocked and such corpses are absent. We isolated a mutant strain that accumulates refractile bodies resembling irregular cell corpses. We rescued this mutant phenotype with the C. elegans mucolipidosis type IV (ML-IV) homolog, the recently identified cup-5 (coelomocyte-uptake defective) gene. ML-IV is a human autosomal recessive lysosomal storage disease characterized by psychomotor retardation and ophthalmological abnormalities. Our null mutations in cup-5 cause maternal-effect lethality. In addition, cup-5 mutants contain excess lysosomes in many and possibly all cell types and contain lamellar structures similar to those observed in ML-IV cell lines. The human ML-IV gene is capable of rescuing both the maternal-effect lethality and the lysosome-accumulation abnormality of cup-5 mutants. cup-5 mutants seem to contain excess apoptotic cells as detected by staining with terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling. We suggest that the increased apoptosis seen in cup-5 mutants is a secondary consequence of the lysosomal defect, and that abnormalities in apoptosis may be associated with human lysosomal storage disorders.


Assuntos
Apoptose , Proteínas de Caenorhabditis elegans , Caenorhabditis elegans/genética , Proteínas de Helminto/genética , Lisossomos/fisiologia , Proteínas de Membrana , Sequência de Aminoácidos , Animais , Caenorhabditis elegans/fisiologia , Proteínas de Helminto/química , Proteínas de Helminto/fisiologia , Marcação In Situ das Extremidades Cortadas , Dados de Sequência Molecular , Mutação
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