Detection and characterization of mitochondrial DNA rearrangements in Pearson and Kearns-Sayre syndromes by long PCR

We used a strategy based on long PCR (polymerase chain reaction) for detection and characterization of mitochondrial DNA (mtDNA) rearrangements in two patients with clinical signs suggesting Pearson syndrome and Kearns-Sayre syndrome (KSS), respectively, and one patient with myopathic symptoms of unidentified origin. Mitochondrial DNA rearrangements were detected by amplification of the complete mitochondrial genome (16.6 kb) using long PCR with primers located in essential regions of the mitochondrial genome and quantified by three-primer PCR. Long PCR with deletion-specific primers was used for identification and quantitative estimation of the different forms of rearranged molecules, such as deletions and duplications. We detected significant amounts of a common 7.4-kb deletion flanked by a 12-bp direct repeat in all tissues tested from the patient with Pearson syndrome. In skeletal muscle from the patient with clinical signs of KSS we found significant amounts of a novel 3.7-kb rearrangement flanked by a 4-bp inverted repeat that was present in the form of deletions as well as duplications. In the patient suffering from myopathic symptoms of unidentified origin we did not detect rearranged mtDNA in blood but found low levels of two rearranged mtDNA populations in skeletal muscle, a previously described 7-kb deletion flanked by a 7-bp direct repeat and a novel 6.6-kb deletion with no repeat. These two populations, however, were unlikely to be the cause of the myopathic symptoms as they were present at low levels (10–40 ppm). Using a strategy based on screening with long PCR we were able to detect and characterize high as well as low levels of mtDNA rearrangements in three patients. Received: 10 March 1997 / Accepted: 20 May 1997     

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.     

Anion inhibition studies of a beta carbonic anhydrase from the malaria mosquito Anopheles gambiae

An anion inhibition study of the β-class carbonic anhydrase, AgaCA, from the malaria mosquito Anopheles gambiae is reported. A series of simple as well as complex inorganic anions, and small molecules known to interact with CAs were included in the study. Bromide, iodide, bisulphite, perchlorate, perrhenate, perruthenate, and peroxydisulphate were ineffective AgaCA inhibitors, with K_Is?>?200?mM. Fluoride, chloride, cyanate, thiocyanate, cyanide, bicarbonate, carbonate, nitrite, nitrate, sulphate, stannate, selenate, tellurate, diphosphate, divanadate, tetraborate, selenocyanide, and trithiocarbonate showed K_Is in the range of 1.80–9.46?mM, whereas N,N-diethyldithiocarbamate was a submillimolar AgaCA inhibitor (K_I of 0.65?mM). The most effective AgaCA inhibitors were sulphamide, sulphamic acid, phenylboronic acid and phenylarsonic acid, with inhibition constants in the range of 21–84?µM. The control of insect vectors responsible of the transmission of many protozoan diseases is rather difficult nowadays, and finding agents which can interfere with these processes, as the enzyme inhibitors investigated here, may arrest the spread of these diseases worldwide.     

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.     

A familial mutation in the testis-determining gene SRY shared by both sexes

A familial mutation in SRY, the gene coding for the testis-determining factor TDF, was identified in an XY female with gonadal dysgenesis, her father, her two brothers and her uncle. The mutation consists of a T to C transition in the region of the SRY gene coding for a protein motif known as the high mobility group (HMG) box, a protein domain known to confer DNA-binding specificity on the SRY protein. This point mutation results in the substitution, at amino acid position 109, of a serine residue for phenylalanine, a conserved aromatic residue in almost all HMG box motifs known. This F109S mutation was not found in 176 male controls. When recombinant wildtype SRY and SRY^F109S mutant protein were tested in vitro for binding to the target site AAC AAAG, no differences in DNA-binding activity were observed. These results imply that the F109S mutation either is a rare neutral sequence variant, or produces an SRY protein with slightly altered in vivo activity, the resulting sex phenotype depending on the genetic back-ground or environmental factors.This paper is dedicated by G. S. to Professor Ulrich Wolf on the occasion of his 60th birthday     

A Simple,Flexible Failure Model

A new failure model is introduced in the form of a four-parameter nonlinear differential equation, with failure probability as the dependent variable and failure time as the independent variable. The first parameter characterizes the location, the second the scale, and the other two the shape of the model. The type of the accompanying hazard function is immediately read off the shape parameters. The new model approximates the classical failure models with rather high precision, but also models cases where the failure density is skewed to the left. It can be used to analyze survival data objectively, based on the shape of the failure distribution. The computation of quantiles and moments is easy and fast. Nonlinear regression methods are used to estimate parameter values.