Mutation analysis and prenatal diagnosis in a Lesch-Nyhan family showing non-random X-inactivation interfering with carrier detection tests

Summary A nonsense mutation at the CpG-site in the codon for Arg(169) in the gene for hypoxanthine phosphoribosyltransferase (hprt) was identified by genomic polymerase chain reaction (PCR) and DNA sequencing in cultured fibroblasts from two brothers with Lesch Nyhan's syndrome. The recurrence of mutation at this CpG-site in several unrelated Lesch-Nyhan families suggests that deamination of 5-methylcytosine is a possible mechanism for mutagenesis. The level of hprt-mRNA in the fibroblasts of the patients was similar to that in healthy controls, whereas hprt-enzyme activity was not detectable. The mutation in this family was also identified in five female relatives and prenatally in a male fetus. Unexpectedly, results from hair follicle analyses and fibroblast selection studies in 8-azaguanine and 6-thioguanine medium showed a non-carrier phenotype in three of the female heterozygotes, whereas X-inactivation mosaicism was demonstrated in one heterozygote. A possible explanation for the apparent non-random X-inactivation in this family is the co-existence of the hprt mutation with an undefined X-linked lethal mutation. This observation is of practical relevance for carrier detection in other Lesch-Nyhan families.     

Survey of allergic respiratory symptoms in grain terminal workers in the Port of Genoa

Summary Fifty workers from two grain elevator terminals were examined to evaluate the prevalence of respiratory symptoms and their relationship with grain dust exposure.Fifty per cent of subjects complained of respiratory symptoms (rhinitis, asthma, chronic cough and dyspnea on exertion). In 34% of the workers the ventilatory function revealed some abnormalities (slight or moderate obstruction).Twenty-two (44%) showed a positive cutaneous reaction to one or more of the allergens tested, mostly towardsDermatophagoides and storage mites. The self-measurement of PEF over 14 days in 27 workers, showed significant differences between symptomatic and asymptomatic subjects. In particular, the results obtained from the cutaneous reactions could suggest a bronchial hypereactivity, worsened by the working exposure to dusts. The monitoring of PEF appears to be a simple and useful method for investigating the relationship between respiratory symptoms and the working environment.     

The picoplankton in Antarctic lakes of northern Victoria Land during summer 1989–1990

Summary Photoautotrophic picoplankton is reported from some lakes located near the Italian Antarctic station of Terra Nova. Observations, carried out by both flow cytometry on water samples and electron microscopy on micro-organisms in cultures from each lake, have confirmed the occurrence in all the environments studied of this fraction accounting, in several cases, for more than the 50% of the phytoplankton, measured as chlorophyll. Cultures of the picoplankton fraction from these waters contained known prokaryotic (Synechococcus) and eukaryotic (Chlorella) genera as well as two unidentified entities, possibly prochlorophytes.     

Study of the amniotic fluid from smokers and non-smokers in the Ames test

Amniotic fluid from smokers and non-smokers was tested by the Salmonella/mammalian microsome test. Concentrated amniotic fluid from heavy smokers at term showed an increase in the number of revertants with increasing exposure to tar. However, some of the non-smokers had a higher number of revertants than the smokers. No significant differences were found between second-trimester samples from smokers and non-smokers, but the limited volumes available at this stage of pregnancy may be a source of error.     

Protein G: a powerful tool for binding and detection of monoclonal and polyclonal antibodies

Protein G is an immunoglobulin (IgG)-binding bacterial cell wall protein recently isolated from group G streptococci. We have investigated the avidity of protein G for various monoclonal and polyclonal Ig of the IgG class, and compared it with the binding properties of protein A, the staphylococcal Fc-binding protein. Radiolabeled Ig were mixed with Sepharose-coupled protein G or protein A, and the amounts of radioactivity bound to the matrix-coupled bacterial proteins were determined. The avidity was found to be greater for protein G than for protein A for all examined Ig. Protein G bound all tested monoclonal IgG from mouse IgG1, IgG2a, and IgG3, and rat IgG2a, IgG2b, and IgG2c. In addition, polyclonal IgG from man, cow, rabbit, goat, rat, and mouse bound to protein G, whereas chicken IgG did not. The binding property of protein G was additionally exploited in the Western blot assay, in which iodine-labeled protein G was used successfully for the detection of a rat monoclonal antibody against ovalbumin, and for the detection of rabbit and goat polyclonal whole antisera against human urinary proteins. In these experimental situations, protein G was found to be a powerful reagent for the detection of IgG, and consequently the antigen against which these antibodies are directed.     

Nesting holes and food supply in relation to forest bird densities on islands and mainland

Summary Bird densities were estimated on 41 small islands and two mainland plots at a South Swedish lake both in 1976 and 1983. In the latter year, three additional plots were also censused. The ratio between combined densities of hole-nesting birds on the mainland and on islands was 3:1 both in plots without and with nest boxes. In plots with boxes combined densities of hole-nesting birds doubled compared with control plots. This increase was caused by a tenfold increase of pied flycatcher Ficedula hypoleuca. Territories of this species were on average established about a week later on the islands compared with the mainland. Furthermore, 50% of the males on the islands did not attract a female. Densities of great tit Parus major, marsh tit Parus palustris and nuthatch Sitta europaea were unaffected by increased nesthole availability. For P. major this result contrasts with those in other studies.The density of chaffinch Fringilla coelebs in habitats with similar height and vertical structure was two times higher on the islands compared to the mainland. On the islands the density was the same on islands with only one pair and on those with two or more pairs. In spring, there were no significant differences between islands and the mainland in the proportion of leaves with insect feeding traces. The proportion of Salix leaves with feeding traces increased with island size, but this was not so for Alnus and Betula leaves. In late summer, the proportion of leaves with feeding traces were halved inside a plot with nest boxes and hence increased bird densities compared to a nearby control plot. This result was the same along the lake shore and about 150 m away from the shore.The discussion centers on the effect of man on the food-and nest site-availability of hole-nesting birds, food limitation of insectivorous birds and density compensation on islands.     

Seasonal variation in catabolic enzyme activities in breast muscle of some migratory birds

Summary Five bird species were examined in order to ascertain if any changes in flight muscle catabolism take place between breeding season and migration. Two different patterns were discovered. The first consists of a high oxidative capacity and a low glycolytic and anaerobic capacity during migration. The converse occurs during the breeding season, i.e. low oxidative, high glycolytic and anaerobic capacity. The pattern was found in those species that deposit large amounts of fat prior to migration. The second pattern was similar to the first, but there was no change in fatty acid oxidation capacity between breeding season and migration. The pattern was found in those species that do not deposit much fat towards migration. These changes are believed to reflect differences in migration strategy and differences in locomotory activity during different seasons. Deviations from these patterns are discussed.     

Amino acid sequence homologies between rabbit, rat, and human serum retinol-binding proteins

The main transporting protein for vitamin A in rabbit serum, the retinol-binding protein (RBP), was isolated and its amino acid sequence determined. Rabbit RBP was found to be highly homologous to human RBP, whose amino acid sequence was elucidated earlier, and to rat RBP. The rat RBP sequence was obtained by combining information deduced from the nucleotide sequences of two overlapping cDNA clones with the NH2-terminal sequence of the isolated protein determined by automated Edman degradation. The identity between the three proteins is approximately 90%. The high degree of homology between RBP molecules from different species is probably explained by the fact that RBP participates in at least three types of molecular interactions: in the binding of prealbumin, in the interaction with retinol, and in the recognition of a specific cell surface receptor. All these interactions should lead to a conservation of RBP structure. The amino acid differences between rabbit, rat, and human RBP are discussed in light of the recent elucidation of the three-dimensional structure of human RBP. Hybridization of a probe isolated from a rat RBP cDNA clone to restriction enzyme-digested genomic DNA from rat and mouse suggests that RBP is encoded by a single gene.     

Distribution of calcium,magnesium and inorganic phosphate in plasma of estradiol-17β treated rainbow trout

Summary Freshwater rainbow trout,Salmo gairdneri, were injected with different doses of estradiol-17 in order to induce the synthesis of a protein, regarded as identical to vitellogenin. The plasma levels of free and protein-bound calcium, magnesium and inorganic phosphate were studied in control and estradiol-17 treated fish, using an ultrafiltration method. Estradiol-17 caused a dose-dependent increase in plasma vitellogenin levels, which strongly correlated to protein-bound levels of calcium and magnesium in plasma. Calcium and magnesium were bound to vitellogenin in a ratio of 9:1, which was considerably higer than the protein-binding ratio of these ions in normal plasma (5.2:1). The dose-dependent increase in total plasma levels of calcium, magnesium and inorganic phosphate during estradiol-17 treatment was solely due to an increase in the protein-bound fraction of these ions. It is concluded that the physiologically important plasma levels of free calcium, magnesium and inorganic phosphate are effectively regulated at normal levels during vitellogenin synthesis.     

Implementation of periodic acid-thiosemicarbazide-silver proteinate staining for ultrastructural assessment of muscle glycogen utilization during exercise

Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these depleted type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed.