Spectrum of phenylketonuria mutations in Western Europe and North Africa,and their relation to polymorphic DNA haplotypes at the phenylalanine hydroxylase locus

Summary A total of 252 chromosomes from 126 patients with phenylalanine hydroxylase (PAH) deficiencies were analyzed for both mutant genotypes and restriction fragment length polymorphism (RFLP) haplotypes at the PAH locus. The mutant genes studied originated either from Western Europe (116 alleles) or from Mediterranean countries (136 alleles). Only 27% of all mutant alleles were found to carry identified mutations, particularly mutations at codon 252 (2.3%), 261 (7.5%), 280 (6.3%), 408 (3.5%) and at the splice donor site of intron 12 (6.3%). The mutant genotypes were associated with RFLP haplotypes 7, 1, 38, 2 and 3 at the PAH locus respectively. Except for the splice mutation of intron 12, these associations were preferential, but not exclusive, since the other four mutations were found on the background of at least two RFLP haplotypes. These results, together with the observation that 85% of PAH deficient patients are heterozygotes for their mutant genotypes, emphasize the great heterogeneity of PAH deficiencies in Mediterranean countries and hamper systematic DNA testing for carrier status in this population.     

Clinical and molecular heterogeneity of phenylalanine hydroxylase deficiencies in France

RFLPs of 68 normal and 74 mutant alleles at the phenylalanine hydroxylase (PAH) locus were determined in 37 French kindreds. A total of 23 haplotypes, including 18 normal and 16 mutant alleles, were observed. Two-thirds of all mutant alleles were confined within only four haplotypes, while the last third was accounted for by 12 haplotypes, including eight haplotypes absent from Caucasian pedigrees reported thus far. Several mutant haplotypes were present in typical phenylketonuria only, others were present in variants only, and some were present in both. In addition, a particular mutant haplotype (haplotype 2) was found to harbor different mutations in our series, resulting in either typical phenylketonuria or in mild hyperphenylalaninemias. The diploid combination of so many mutant haplotypes in PAH-deficient patients and of compound heterozygosity at the PAH locus in southern Europe might account for the broad spectrum of individual phenotypes observed in France.     

Stereological study of the early ultrastructural differentiation of chick embryo neuroepithelial cells during neurulation

The neuroectodermal cells of chick embryos have been analyzed during neurulation by stereological and morphometrical ultrastructural methods in an attempt to describe their cytometric evolution. A profound change of cellular form coefficient was observed which is related to the typical process of columnarization of these cells. At stages 7 and 8, the nucleus appeared round in shape, probably due to a loss of pressure of the vitelline inclusions. In this sense, the volume density of these inclusions falls during this period. There was also a significant increase of the nuclear surface density, the significance of which is discussed on the basis of the nucleo-cytoplasmic interchanges and the differentiation process. At the same time, an increase in the number of mitochondria was observed, which is related to the neural folding process. Simultaneously, the amount of rough endoplasmic reticulum increases, presumably related to the remarkable changes of the embryonic extracellular matrix.     

Spring and summer hosts for Pieris rapae in Southern Spain with special attention to Capparis spinosa

The suitability of different host plants for Pieris rapae L. in the South of the Iberian Peninsula, was studied in relation to host plant phenology, female behaviour, and larval development. Capparis spinosa is the only host plant available during the dry season of the year in the area studied. D. virgata, R. raphanistrum, H. incana and S. alba being suitable spring hosts. Comparative studies on mortality, larval development and larval growth between C. spinosa and the spring hosts revealed no significant differences.

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Résumé L'adéquation de différentes plantes comme hôtes de P. rapae a été examinée en fonction de la phénologie des végétaux, du comportement de la femelle et du développement larvaire dans le sud de la péninsule ibérique. Pendant la saison sèche, C. spinosa est la seule plant convenable dans la zone étudiée. Diplotaxis virgata, Raphanus raphanistrum, Hirschfeldia incana et Sinapis alba sont des hôtes printaniers convenables. La mortalité, le développement et la croissance larvaires ne sont pas différentes sur C. spinosa et sur les hôtes de printemps.

     

Genetic Controls over Activities of Tyrosinase and Dopachrome Conversion Factor in Murine Melanocytes

We evaluated the three catalytic activities of tyrosinase and one activity of dopachrome conversion factor (DCF) in extracts made from skins of 6-day-old yellow and nonyellow mice. At least one of the catalytic activities of tyrosinase and of DCF correlate with the color of pigment being produced in the hair follicles of the mice. We use these data to evaluate existing hypotheses about the mechanism of the interacting genetic controls over melanogenesis.     

Müllerian inclusions in peritoneal washings. Potential source of error in cytologic diagnosis

Müllerian inclusions in peritoneal washings from female patients may be mistaken for adenocarcinoma. Such findings were studied in the peritoneal washing cytology specimens from eight cases. The inclusions usually presented as tubular or papillary structures, often forming a single layer of epithelium surrounding psammoma bodies. The cells forming these structures often displayed some degree of atypia. Recognition of this entity in peritoneal fluids is important to avoid a misdiagnosis of disseminated cancer. A general outline is proposed for interpreting such findings in peritoneal washings, based on the cytomorphology of these structures as well as the microscopic features of the primary neoplasms.     

Cellular Localization of the Molecular Forms of Acetylcholinesterase in Primary Cultures of Rat Sympathetic Neurons and Analysis of the Secreted Enzyme

The secretion and cellular localization of the molecular forms of acetylcholinesterase (AChE) were studied in primary cultures of rat sympathetic neurons. When cultured under conditions favoring a noradrenergic phenotype, these neurons synthesized and secreted large quantities of the tetrameric G4, and the dodecameric A12 forms, and minor amounts of the G1 and G2 forms. When these neurons adopted the cholinergic phenotype, i.e., in the presence of muscle-conditioned medium, the development of the cellular A12 form was completely inhibited. These neurons secreted only globular, mainly G4, AChE. Both cellular and secreted A12 AChE in adrenergic cultures aggregated at an ionic strength similar to that of the culture medium, raising the hypothesis that this form was associated with a polyanionic component of basal lamina. In noradrenergic neurons, 60-80% of the catalytic sites were exposed at the cell surface. In particular, 80% of G4 form, but only 60% of the A12 form, was external, demonstrating for the A12 form a sizeable intracellular pool. The hydrophobic character of the molecular forms was studied in relation to their cellular localization. As in muscle cells, most of the G4 form was membrane-bound. Whereas 76% of the cell surface A12 form was solubilized in the aqueous phase by high salt concentrations, only 50% of the intracellular A12 form was solubilized under these conditions. The rest of intracellular A12 could be solubilized by detergents and was thus either membrane-bound or entrapped in vesicles originating from, e.g., the Golgi apparatus.     

Dopamine Metabolism in Hypoxanthine-Guanine Phosphoribosyltransferase-Deficient Variants of PC12 Cells

Lesch-Nyhan syndrome results from a deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT). It is manifest by behavioral abnormalities, including self-mutilation, and evidence of abnormal 3,4-dihydroxyphenylethylamine (dopamine) metabolism. To assess whether an HPRT deficiency in a dopaminergic cell can adversely affect dopamine metabolism in that cell, dopamine metabolism was examined in HPRT-deficient variants of PC12 pheochromocytoma cells and in cells that had regained HPRT activity by virtue of transformation with a recombinant retrovirus containing the human gene for HPRT. There was no correlation between HPRT activity and endogenous dopamine levels, dopamine uptake, dopamine release, or monoamine oxidase activity. Transformation with the HPRT retrovirus did not adversely affect dopamine metabolism.     

Permeability of the squid giant axon to organic cations and small nonelectrolytes

Summary The permeability of the Na channel of squid giant axon to organic cations and small nonelectrolytes was studied. The compounds tested were guanidinium, formamidinium, and¹⁴C-labeled urea, formamide, thiourea, and acetone. Permeability was calculated from measurements of reversal potential and influx on internally perfused, voltage clamped squid axons. The project had two objectives: (1) to determine whether different methods of measuring the permeability of organic cations yield similar values and (2) to see whether neutral analogs of the organic cations can permeate the Na channel. Our results show that the permeability ratio of sodium to a test ion depends upon the ionic composition of the solution used. This finding is consistent with the view put forward previously that the Na channel can contain more than one ion at a time. In addition, we found that the uncharged analogs of permeant cations are not measurably permeant through the Na channel, but instead probably pass through the lipid bilayer.