A mev-1(kn1) mutant of the nematode Caenorhabditis elegans is defective in the cytochrome b large subunit (Cyt-1/ceSDHC) in complex II of the mitochondrial electron transport chain. We have previously shown that a mutation in mev-1 causes shortened life span and rapid accumulation of aging markers such as fluorescent materials and protein carbonyls in an oxygen-dependent fashion. However, it remains unclear as to whether this hypersensitivity is caused by direct toxicity of the exogenous oxygen or by the damage of endogenous reactive oxygen species derived from mitochondria. Here we report important biochemical changes in mev-1 animals that serve to explain their abnormalities under normoxic conditions: (i) an overproduction of superoxide anion from mitochondria; and (ii) a reciprocal reduction in glutathione content even under atmospheric oxygen. In addition, unlike wild type, the levels of superoxide anion production from mev-1 mitochondria were significantly elevated under hyperoxia. Under normal circumstances, it is well known that superoxide anion is produced at complexes I and III in the electron transport system. Our data suggest that the mev-1(kn1) mutation increases superoxide anion production at complex II itself rather than at complexes I and III. The mev-1 mutant also had a lactate level 2-fold higher than wild type, indicative of lactic acidosis, a hallmark of human mitochondrial diseases. These data indicate that Cyt-1/ceSDHC plays an important role not only in energy metabolism but also in superoxide anion production that is critically involved in sensitivity to atmospheric oxygen.

Glia are essential components of nervous systems. However, genetic programs promoting glia development and regulating glianeuron interactions have not been extensively explored. Here we describe transcriptional programs required for development and function of the C. elegans cephalic sheath (CEPsh) glia. We demonstrate ventral-and dorsal-restricted roles for the mls-2/Nkx/Hmx and vab-3/Pax6/Pax7 genes, respectively, in CEPsh glia differentiation and expression of the genes hlh-17/Olig and ptr-10/Patchedrelated. Using mls-2 and vab-3 mutants, as well as CEPsh glia-ablated animals, we show that CEPsh glia are important for sensory dendrite extension, axon guidance/branching within the nerve ring, and nerve ring assembly. We demonstrate that UNC-6/Netrin, expressed in ventral CEPsh glia, mediates glia-dependent axon guidance. Our results suggest possible similarities between CEPsh glia development and oligodendrocyte development in vertebrates, and demonstrate that C. elegans provides a unique environment for studying glial functions in vivo.

BackgroundNationwide surveys conducted in Japan over the past thirty years have revealed a four-fold increase in the estimated number of multiple sclerosis (MS) patients, a decrease in the age at onset, and successive increases in patients with conventional MS, which shows an involvement of multiple sites in the central nervous system, including the cerebrum and cerebellum. We aimed to clarify whether genetic and infectious backgrounds correlate to distinct disease phenotypes of MS in Japanese patients.Methodology/Principal FindingsWe analyzed HLA-DRB1 and -DPB1 alleles, and IgG antibodies specific for Helicobacter pylori, Chlamydia pneumoniae, varicella zoster virus, and Epstein-Barr virus nuclear antigen (EBNA) in 145 MS patients and 367 healthy controls (HCs). Frequencies of DRB1*0405 and DPB1*0301 were significantly higher, and DRB1*0901 and DPB1*0401 significantly lower, in MS patients as compared with HCs. MS patients with DRB1*0405 had a significantly earlier age of onset and lower Progression Index than patients without this allele. The proportion and absolute number of patients with DRB1*0405 successively increased with advancing year of birth. In MS patients without DRB1*0405, the frequency of the DRB1*1501 allele was significantly higher, while the DRB1*0901 allele was significantly lower, compared with HCs. Furthermore, DRB1*0405-negative MS patients were significantly more likely to be positive for EBNA antibodies compared with HCs.ConclusionsOur study suggests that MS patients harboring DRB1*0405, a genetic risk factor for MS in the Japanese population, have a younger age at onset and a relatively benign disease course, while DRB1*0405-negative MS patients have features similar to Western-type MS in terms of association with Epstein-Barr virus infection and DRB1*1501. The recent increase of MS in young Japanese people may be caused, in part, by an increase in DRB1*0405-positive MS patients.

Our results suggest that HLA-DRB1*1602 and DPB1*0501 alleles and H pylori and Chlamydia pneumonia infection are risk factors only for anti-AQP4 antibody positive NMO/NMOSD but not for anti-AQP4 antibody negative NMO/NMOSD.

Death is a vital developmental cell fate. In Caenorhabditis elegans, programmed death of the linker cell, which leads gonadal elongation, proceeds independently of caspases and apoptotic effectors. To identify genes promoting linker-cell death, we performed a genome-wide RNA interference screen. We show that linker-cell death requires the gene pqn-41, encoding an endogenous polyglutamine-repeat protein. pqn-41 functions cell autonomously, and is expressed at the onset of linker-cell death. pqn-41 expression is controlled by the MAP kinase kinase SEK-1, which functions in parallel to the Zn-finger protein LIN-29 to promote cellular demise. Linker-cell death is morphologically similar to cell death associated with normal vertebrate development and polyglutamine-induced neurodegeneration. Our results may, therefore, provide molecular in-roads to understanding non-apoptotic cell death in metazoan development and disease.