Antigens Associated with N- and L-Type Calcium Channels in Lambert-Eaton Myasthenic Syndrome

Abstract: In Lambert-Eaton myasthenic syndrome neurotransmitter release is reduced by an autoimmune response directed against the calcium channel complex of the nerve terminal. Autoantibodies were detected by immunoprecipitation assays using solubilized receptors labeled with ligands selective for N-type (¹²⁵I-ω conotoxin GVIA) and L-type ([³H]PN200-110) calcium channels. Sera with a high antibody titer (>3 n M ) against rat brain N-type channels contained autoantibodies that immunoprecipitated neuronal and muscle L-type channels. These IgG fractions stained a 55-kDa protein in immunoblots of purified skeletal muscle dihydropyridine receptor, suggesting that they contain autoantibodies against the β subunit of the calcium channel. A distinct antibody population in the same fractions reacted with a nerve terminal 65-kDa protein that is unrelated to the β subunit and displays properties similar to those of synaptotagmin.     

Chromosomal localization of the major histocompatibility complex (MHC) in the rhesus monkey and chimpanzee by fluorescence in situ hybridization.

Genes for the major histocompatibility complex (MHC) were localized by fluorescence in situ hybridization to the long arm of rhesus monkey chromosome 5. This localization contradicts previous reports, based on genetic investigation of somatic cell hybrids, that placed the MHC on chromosome 2 of this species. In the chimpanzee, the MHC loci were localized to 5p21.3, corresponding precisely to their location on human chromosome 6p21.3.     

Molecular and Biochemical Characterization of Three Anthocyanin Synthetic Enzymes from Gentiana triflora

Full length cDNA clones of flavonoid 3',5'-hydroxylase, dihydroflavonol4-reductase and flavonoid 3-glucosyltransferase were clonedfrom petals of Gentiana triflora. Their sequences were homologousto counterparts from other plants. Flavonoid 3',5'-hydroxylaseand flavonoid 3-glucosyltransferase were enzymatically characterizedby expressing cDNAs in heterologous expression systems. (Received May 21, 1996; Accepted June 4, 1996)     

Repetitive DNA (TGGA)n 5' to the human myelin basic protein gene: a new form of oligonucleotide repetitive sequence showing length polymorphism.

DNA 5' to the human myelin basic protein (MBP) gene, mapped to 18q22----qter, is known to manifest multiallelic DNA length variation with heterozygosity of at least 45%. Isolation of genomic DNA containing the MBP gene first exon and its 5' flanking region reveals that this polymorphism arises from a 994-bp region of the diverged tandem repeat (TGGA)249. This sequence is located from 1082 to 2075 bp upstream of the MBP initiator methionine. The repetitive sequence is 18% diverged from (TGGA)249 and from analysis of higher order subsequence reiterations appears to have undergone extensive recombination. The pattern of higher order repetition suggests that multiple crossover and gene conversion events have occurred within a 1.0-kb region. Molecular clones of this sequence represent essentially the longest allelic form of this region seen in Southern transfer analysis. This repetitive DNA is similar to a sequence 5' to the human myoglobin gene.     

Synthesis of chimeric RNAs between U6 small nuclear RNA and (-)sTRSV and analysis of their cleavage activities against the substrate RNA.

U6 small nuclear RNA (U6 snRNA) is one of the spliceosomal RNAs essential for pre-mRNA splicing. Highly conserved region of U6 snRNA shows a structural similarity with the catalytic center of the negative strand of the satellite RNA of tobacco ring spot virus [(-)sTRSV], supporting the hypothesis that U6 snRNA has a catalytic role in pre-mRNA splicing. To test this hypothesis, we examined in vitro whether synthetic RNAs consisting of the sequence of the highly conserved region of U6 snRNA or various chimeric RNAs between the U6 region and the catalytic center of (-)sTRSV could cleave a substrate RNA that can partially base-pair with them and has a GU sequence between the pairing regions. Chimeric RNAs with 70 to 83% sequence identity with the conserved region of S. pombe U6 snRNA cleaved the substrate RNA at the 5' side of the GU sequence. In addition, we found that the highly conserved region of U6 snRNA is similar in structure to the catalytic core region of the group I self-splicing intron in cyanobacteria. These results support the hypothesis that U6 snRNA catalyzes the pre-mRNA splicing reaction and U6 snRNA may originate from the catalytic domain of an ancient self-splicing intron.     

Visualization of the microbody division inCyanidioschyzon merolae with the fluorochrome brilliant sulfoflavin

Summary A novel procedure is described for fluorescence staining of microbodies, which can be applied quickly and easily. We developed this technique of microbody staining with the unicellular red algaCyanidioschyzon merolae. Cyanidioschyzon merolae only contains a single chloroplast, mitochondrion, and microbody per cell, and the mitotic cycle and the organelle division cycle are easily synchronized. Knowing that the concentration of H₂O₂ in the microbody is higher than it is in the cytosol and other cell components, we attempted to visualize the microbody by using fluorescence microscopy to detect H₂O₂. Brilliant sulfoflavin (BSF), used for detecting Fe²⁺ in analytical chemistry, fluoresces when it reacts with Fe²⁺ and H₂C₂. We were able to specifically stain microbodies with BSF, under acidic conditions (pH 3.0 or pH 2.5) with blue-light excitation. Using this procedure, we observed division of the microbody and the effect of aphidicolin on the microbody. We also discovered that microbody division is regulated by the cell nucleus and follows division of the cell nucleus.     

A Highlights from MBoC Selection: Regulation of the formin Bnr1 by septins anda MARK/Par1-family septin-associated kinase

Formin-family proteins promote the assembly of linear actin filaments and are required to generate cellular actin structures, such as actin stress fibers and the cytokinetic actomyosin contractile ring. Many formin proteins are regulated by an autoinhibition mechanism involving intramolecular binding of a Diaphanous inhibitory domain and a Diaphanous autoregulatory domain. However, the activation mechanism for these Diaphanous-related formins (DRFs) is not completely understood. Although small GTPases play an important role in relieving autoinhibition, other factors likely contribute. Here we describe a requirement for the septin Shs1 and the septin-associated kinase Gin4 for the localization and in vivo activity of the budding yeast DRF Bnr1. In budding yeast strains in which the other formin, Bni1, is conditionally inactivated, the loss of Gin4 or Shs1 results in the loss of actin cables and cell death, similar to the loss of Bnr1. The defects in these strains can be suppressed by constitutive activation of Bnr1. Gin4 is involved in both the localization and activation of Bnr1, whereas the septin Shs1 is required for Bnr1 activation but not its localization. Gin4 promotes the activity of Bnr1 independently of the Gin4 kinase activity, and Gin4 lacking its kinase domain binds to the critical localization region of Bnr1. These data reveal novel regulatory links between the actin and septin cytoskeletons.     

Tracing the invasion characteristics of the yellow-legged hornet,Vespa velutina nigrithorax (Hymenoptera: Vespidae), in Korea using newly detected variable mitochondrial DNA sequences

The yellow-legged hornet, Vespa velutina nigrithorax (Hymenoptera: Vespidae), invaded South Korea in 2003 through Busan metropolitan city, which is located in the southeast region of the country. Previous studies aiming to trace the origin of V. velutina in Korea used a portion of mitochondrial (mt) COI and detected a single haplotype common to the site of origin. However, no subsequent study on invasive dynamics such as additional entry and/or another site of entry has been performed. In this study, segments of mt COI, CytB, and lrRNA were sequenced from 238 individuals collected in 11 Korean and two Japanese localities, but no variation in each gene was observed. Thus, we developed two intergenic spacer (IGS) sequences from the publicly available mt genome of V. velutina, which provided substantially increased variability (i.e., 19 haplotypes with 1.74% maximum sequence divergence in 1,129–1,146-bp-long concatenated sequences). Population genetic analyses using the concatenated sequences unexpectedly provided higher genetic diversity estimates in the northwest and southwest regions, both of which also harbor international cargo ports, than in the southeast region, in which Busan is located. Furthermore, this genetic result was roughly concordant with our questionnaire survey demonstrating that V. velutina was observed in apiaries located in the northwest and southwest regions up to 2012, when there was no reported prevalent distribution of the hornet beyond the southeast region. These results collectively suggest that the northwest and southwest regions of Korea are additional sites of V. velutina entry to the country, independent from the southeast region origin.