A topoisomerase II cleavage site is associated with a novel mitochondrial DNA deletion

Mitochondrial myopathies and encephalopathies can be caused by nucleotide substitutions, deletions or duplications of the mitochondrial DNA (mtDNA). In one such disorder, Kearns-Sayre Syndrome (KSS), large-scale hetero-plasmic mtDNA deletions are often found. We describe a 14-year-old boy with clinical features of KSS, plus some additional features. Analysis of the entire mitochondrial genome by the polymerase chain reaction and Southern blotting revealed a 7864-bp mtDNA deletion, heteroplasmic in its tissue distribution. DNA sequencing established that the deletion was between nucleotides 6238 and 14103, and flanked by a 4-bp (TCCT) direct repeat sequence. Deletions between direct repeats have been hypothesised to occur by a slipped-mismatching or illegitimate recombination event, or following the DNA cleavage action of topoisomerase II. Analysis of the gene sequence in the region surrounding the mtDNA deletion breakpoint in this patient revealed the presence of putative vertebrate topoisomerase II sites. We suggest that direct repeat sequences, together with putative topoisomerase II sites, may predispose certain regions of the mitochondrial genome to deletions.     

New chromosomal translocations correlate with specific immunophenotypes of childhood acute lymphoblastic leukemia

Cytogenetic analysis of leukemic cells obtained at diagnosis from 122 patients with childhood acute lymphoblastic leukemia (ALL) disclosed chromosomal translocations in 36 cases. Two new nonrandom translocations were identified and found to be associated with specific immunophenotypes of the disease. The first, identified in 4 of 16 cases of T-cell ALL positive for sheep erythrocyte receptors (E+), involved the short arm (p) of chromosome 11 and the long arm (q) of chromosome 14 and was designated t(11;14) (p13;q13). The second, found in 7 of 23 cases with a pre-B-cell phenotype, involved the long arm of chromosome 1 and the short arm of chromosome 19; it was designated t(1;19) (q23;p13.3). A third abnormality involving a common breakpoint on chromosome 12 (band p 12) was also identified. These two new differentiation-specific translocations suggest a mechanism for aberrant expression of genes that influence lymphoid cell growth and development, as well as leukemogenesis.     

The passage of orally fed proteins from mother to foetus in the rat

Pregnant rats were orally fed with a mixture of bovine IgG, bovine albumin, ovalbumin and beta-lactoglobulin. Using immunoprecipitation methods, these proteins were detected in the maternal blood serum, urine and uterine fluids, and also in the foetal blood serum and the amniotic fluid. The results imply that a variety of dietary proteins, still immunoprecipitable, are able to cross the materno-foetal barriers to be detected in the foetal circulation, where they may influence the maturation of the immune system of the foetus.     

Distribution of myosin and the glial fibrillary acidic protein (GFA Protein) in rat spinal cord and in the human frontal cortex as revealed by immunofluorescence microscopy

Summary The glial fibrillary acidic (GFA) protein and myosin were localized in rat spinal cord and human frontal cortex using specific antibodies against GFA protein from human spinal cord and highly purified smooth myosin from chicken gizzard by means of an indirect immunofluorescence microscopical approach. A strong GFA protein and myosin immunoreactivity was found in astrocytes of the white and grey matter and in the external glial limitans membrane. The very fine branches of astrocytic processes stained with antiGFA protein, but not with anti-myosin. Similar results were obtained with the human frontal cortex, where myosin antibodies failed to reveal the very fine branches of protoplasmic astrocytes.As a whole, staining with the GFA protein antiserum was more crisp than with the myosin antibody.Thanks are due to Professor J.R. Wolff, Max-Planck Institute for Biophysical Chemistry, Göttingen, for stimulating discussions, to Ursula König, Christa Mahlmeister and Renate Steffens for skilful technical assistance, and to Heidi Waluk for the photographic workSupported by grants from Deutsche Forschungsgemeinschaft (Br 634/1, Dr 91/1, Un 34/4, Ste 105/19)Dedicated to Prof. Dr. med. H. Leonhardt on the occasion of his 60. birthday     

Construction of Texas coastal foredunes with sea oats (Uniola paniculata) and bitter panicum (Panicum amarum)

Studies were conducted on Padre Island, Texas since 1968 to provide specifications for how to use vegetation to reconstruct destroyed portions of foredunes of Gulf Coast barrier islands. The area has a subtropical, semi-arid climate, moderated by maritime tropical air from the Gulf of Mexico. Annual precipitation averages 670 mm for the island. We established experimental foredunes in broad overwash areas, 1.5 m M.S.L. where foredunes were eroded by hurricanes or destroyed by blowouts and across hurricane overwash channels of lower elevation behind the berm and more susceptible to surges. Most successful establishment of a vegetated dune was by transplanting directly onto the level backbeach to reestablish the original duneline about 125 meters inland. Sea oats and bitter panicum proved best of all species tested. Bitter panicum was the more desirable because of higher transplant survival, a longer planting season, and ease of harvest. Transplant survival was influenced more by soil salinity, soil moisture, and plant vigor, than by planting season as successful plantings occurred during all seasons. December through February plantings were best for sea oats, but survival of bitter panicum transplants different little from November through May. Both species are capable of growth year round during periods of favorable climatic conditions, although little growth occurs from mid-December to mid-February. Transplants placed 0.6 m apart with total planting width of 15 m produced foredunes nearly 6 m high in 6 years. Such plantings trapped sand at the rate of 12.5 m³/m of beach. In hurricane overwash channels, we used 0.6 m high sand fence placed 3 m apart to produce a flat topped dune free of salt for a planting surface. Without this site preparation, no transplants survived due to high soil salinity. Dune width was effectively widened by planting a strip 15 m wide immediately beachward of a previously established 4-year old dune.Presented at the Seventh International Biometeorological Congress, 17–23 August 1975, College Park, Maryland, USA.     

Hereditary mucoepithelial dysplasia: a disease apparently of desmosome and gap junction formation.

A previously unrecognized autosomal dominant syndrome affecting oral, nasal, vaginal, urethral, anal, bladder, and conjunctival mucosa with cataracts, follicular keratosis, nonscarring alopecia, and terminal lung disease is described in a four-generation kindred of German extraction. Severe photophobia, tearing, and nystagmus in infancy heralds the development of keratitis, corneal vascularization, and lens cataracts. Repeated corneal transplants have failed. Red, periorificial mucosal lesions involving the above structures are noted by 1 year of age and may persist throughout life. Chronic rhinorrhea and repeated upper respiratory infections frequently progress to bilateral pneumonia accompanied by loss of hair, diarrhea, occasional melena, enuresis, pyuria, and hematuria. Spontaneous pneumothorax is frequent, terminating in fibrocystic-type lung disease and cor pulmonale. Women have had repeated abnormal vaginal PAP smears. Histologically the mucosal epithelium shows dyshesion, thinning of the epithelial layer, and dyskeratosis. Mucosal PAP smears show lack of epithelial maturation, cytoplasmic vacuoles and inclusions, and individual cell dyskeratosis. Histochemically there is a lack of cornification and keratinization. Ultrastructural studies show lack of keratohyalin granules, a paucity of desmosomes, intercellular accumulations, cytoplasmic vacuolization, and formation of bands and aggregates of filamentous fibers and structures in the cytoplasm resembling desmosomes and gap junctions. The condition is probably a panepithelial cell defect of desmosomal and gap junction structure most prominently affecting mucosal epithelia associated with an increased susceptibility to a variety of adventitious organisms.     

Modified procedure for the recovery of naturally accumulated poliovirus from oysters.

Methods were compared for their ability to recover poliovirus from oysters (Crassostrea gigas) which had been allowed to accumulate virus via normal filtration activities. Clarification procedures included glycine-NaCl and polyelectrolyte extraction methods followed by a variety of acid precipitation concentration methods. Polyelectrolyte flocculation followed by a beef extract-supplemented acid precipitation carried out at pH 3.5 yielded the most efficient recoveries. Direct assay of homogenates was found to be an unreliable method for determining the initial virus concentration in "naturally infected" oysters.     

Metal-directed affinity labeling of zinc(II), cobalt(II) and cadmium(II) horse liver alcohol dehydrogenases

The active site metal in horse liver alcohol dehydrogenase has been studied by metal-directed affinity labeling of the native zinc(II) enzyme and that substituted with cobalt(II) or cadmium(II). Reversible binding of bromoimidazolyl propionic acid to the cobalt enzyme blueshifts the visible absorption band originating from the catalytic cobalt atom at 655 to 630 nm. Binding of imidazole to the cobalt(II) enzyme redshifts the 655 nm band to 667 nm. Addition of bromoimidazolyl propionic acid blueshifts this 667 nm band back to 630 nm. This proves direct binding of the label to the active site metal in competition with imidazole. The affinity of the label for the reversible binding site in the three enzymes follows the order Zn ? Cd ? Co. After reversible complex formation, bromoimidazolyl propionic acid alkylates cysteine-46, one of the protein ligands to the active site metal. The nucleophilic reactivity of this metal-mercaptide bond in each reversible complex follows the order Co ? Zn ? Cd.     

HE TURNOVER RATE OF TUBULIN IN RAT BRAIN

The turnover rate of tubulin in rat brain was determined from the decay in specific radioactivity of the protein after pulse-labeling. When precursors were administered by a parenteral route, the shortest half-life, 9.8 days, was obtained with [¹⁴C]NaHCO₃; the longer half-lives obtained with [U-¹⁴C]glucose or [4,5-³H]leucine suggest significant reutilization of label. Furthermore, with leucine as precursor maximal specific radioactivity of tubulin was not obtained until eight days after administration of label. Labeling and decay kinetics obtained with [4,5-³H]leucine were markedly different when the isotope was administered directly into the lateral ventricle. The difference between the turnover rates of the -α and β subunits of tubulin purified by means of high resolution polyacrylamide gel electrophoresis was not statistically significant. A half-life for tubulin of 6.2 days was measured by continuous intravenous infusion of [U-¹⁴C]tyrosine.