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.     

Family studies of hereditary hemochromatosis in Denmark and the Faroe Islands

Summary Pedigree studies were performed based on one Faroese and four Danish probands with overt idiopathic hemochromatosis (IH). The study consisted of HLA typing and determination of biochemical iron status indicators (serum transferrin saturation, serum ferritin). In total, 130 persons were evaluated. The screening identified 6 homozygous (h/h) subjects with preclinical IH, 46 heterozygous (h/n), and 8 normal (n/n) subjects, while 39 subjects were classified as normal or heterozygous (n/h?). One family demonstrated both a homozygous x heterozygous as well as a heterozygous x heterozygous mating. Recombination between the HLA region and IH locus occurred possibly in three subjects in three different families. The significance of detailed screening in families with probands with IH is discussed.     

Immunolocalization of the Na,K-ATPase in photoreceptor cells of the moth Manduca sexta-evidence for Na,K-ATPase on both the nonmicrovillar and the microvillar domains of the plasma membrane

Immunohistochemical and physiological studies on various insect photoreceptors have demonstrated that the Na,K-ATPase (sodium pump) is restricted to the nonreceptive nonmicrovillar area of the plasma membrane. Here, we examined the distribution of the Na,K-ATPase in photoreceptor cells of the superposition-type compound eye in the moth Manduca sexta. Using immunofluorescent and immunogold cytochemistry, we show that the Na,K-ATPase is localized to both the nonmicrovillar and the microvillar parts of the plasma membrane. Manduca photoreceptors thus deviate from the common concept that the sodium pump and the molecular components of the photoreceptive machinery reside on different domains of the plasma membrane.     

Reversible beta-pleated sheet formation of a phosphorylated synthetic tau peptide.

Serine416 of human tau protein is believed to be phosphorylated in Alzheimer neurofibrillary tangles. We synthesized a fragment of tau, consisting of amino acids 408-421 in both non-phosphorylated and serine416-phosphorylated forms. Circular dichroism in a trifluoroethanol-water mixture indicated a beta-turn----beta-pleated sheet conformational transition upon phosphorylation. The beta-structure formation is intermolecular and can be inhibited by addition of Ca2+ ions or a phosphorylated tripeptide, but not with its non-phosphorylated analog. The presence of the phosphorylated tau peptide did not facilitate the formation of beta-pleated sheets of a phosphorylated neurofilament fragment. Multivalent cations induced a conformational transition of this phosphorylated neurofilament peptide, but the effect was less specific than the transition induced in the tau fragment, and it could also be reversed with the competing phosphorylated tripeptide.     

Genetic instability of industrial strains of Penicillium chrysogenum

Summary It has shown that several characteristics of high-producing industrial strains of Penicillium chrysogenum tend to segregate in the course of cultivation (slant-to-slant transfer). Segregation includes a decrease in the yield of penicillin, mean conidial size, mean size of the nuclei, and an increase in the proportion of morphologically wild-type colonies. These lower-producing segregants also have a higher sensitivity against ultraviolet radiation and, as shown by cytofluorometric methods, a lower DNA content in the condia, a decrease in phosphate uptkae and in the activity of extracellular alkaline phosphatases compared to high-producing strains. Obviously, during mutagenesis/selection programmes ploidy mutants have been selected, which entails an increase in the number of genes coding enzymes responsible for penicillin biosynthesis. In the absence of selection pressure these high-producing strains segregate to lower-producing strains by chromosome losses in the course of slant-to-slant transfers. Offprint requests to: W. Künkel     

Evaluation of SYPRO Ruby total protein stain for the normalization of two-dimensional Western blots

Due to post-translational modifications such as phosphorylation, proteins exist as distinct charge variants. Two-dimensional (2D) gel electrophoresis followed by immunoblotting enables the detection of these isoforms. For their accurate relative quantitation in different samples, a loading control is necessary to compensate for technical errors such as imprecise sample loading or transfer. The study reveals that the combinatory approach of SYPRO Ruby and chemiluminescence-based 2D Western blot analysis exhibits high linearity and excellent reproducibility and is applicable for limited sample amounts.     

Biochemical composition of the parasitic amphipod Hyperia galba in relation to age and starvation

Summary Hyperia galba was collected in the waters around Helgoland and in the Weser-Elbe-estuary during autumn. Its mode of life is a temporary but obligatory parasitism. The basal biochemical composition of the adults was analyzed in detail and related to the fresh, dry, and ash-free dry weight as well as sex and body length. Hyperia galba (males/females) consists of 85/86% water; the dry matter contains approximately 64/61% protein, 10/11% lipid, 1.2/1.5% carbohydrate, 10/8% chitin, and 23/23% ash. The analyses of basal elemental composition yielded approximately 38% C, 9% N and 6% H. Under natural conditions, individuals may encounter at least two periods of food shortage during their lives. Therefore, the analyses were carried out on individuals of different developmental stages also under food deprivation. The data are discussed with respect to the special mode of life of the species and compared with those found by other authors in several related crustacean species.Abbreviations AFDW ash-free dry weight - BL body length - DW dry weight - SD standard deviation - WW wet weight