Partial duplication of the short arm of chromosome 2 (dup(2)(p13----p21) associated with mental retardation and an Aarskog-like phenotype

In this report we describe a 3-year-old boy with partial trisomy of the short arm of chromosome 2 due to a de novo tandem duplication 2(dup(2)(p13----p21)). In addition to severe growth retardation and moderate psychomotor delay he presented a dysmorphic syndrome compatible with the clinical diagnostic of Aarskog syndrome.     

On the occurrence of macroorchidism and mental handicap in the Aarskog syndrome

In this report we present follow-up on two moderately mentally retarded boys with Aarskog syndrome. As 22 other mentally normal Aarskog patients these two boys presented a catch-up after a delayed puberty with a final adult height of 160 cm. A remarkable finding was the development of macroorchidism in two mentally retarded Aarskog patients. The pathogenesis of macroorchidism in the fragile X syndrome and in other X-linked mental retardation syndromes is discussed.     

SCE variability in lymphocytes and fibroblasts

Summary To determine whether the sister chromatid exchange (SCE) distributions obtained in lymphocytes and fibroblasts from different individuals are comparable, a controlled study was set up. Peripheral blood and skin biopsies were taken on the same day from five individuals living for years under the same environmental conditions. All samples were treated in the same fashion, and the SCEs were scored in 50 metaphases of peripheral blood lymphocytes and of skin fibroblasts in an early and in a late passage. A repeat blood sample was taken from the same five indivuduals 1 year later. Based on the results obtained in this first part of the study, five randomly chosen healthy blood donors were sampled at different times and studied in the same fashion. Each chromosome was identified, and the SCE scores were tabulated per chromosome over 50 metaphases. The statistical analysis consisted of fitting log linear models to these scores and examining the best fit by determining the exceedance probabilities (observed significance level). For lymphocytes, the results indicated that the SCE distributions depended only on the chromosome examined, and not on BrdU-exposure time, individuals, or time of sampling. Treatment with ethyl methane sulfonate (EMS) increased the number of SCEs proportionally on all chromosomes. Analysis of the SCE scores on lymphocytes and fibroblasts of the five individuals and on their low and high passage fibroblast cultures revealed the necessity of including higher order interactions in order to fit a suitable model to the data. Therefore comparison of the SCE scores of lymphocytes with those of fibroblasts or comparison of scores on fibroblasts from different individuals could not be done. In practice, to compare samples or individuals, it suffices to score the SCE on a limited number of chromosomes (e.G., the A group) of 50 metaphases.     

X-chromosome polysomy in the male

Summary A review of 569 male patients with X-chromosome polysomies (544 Klinefelter and 25 patients with other types of X-chromosome polysomy) is presented here. These patients were detected among the 77000 persons karyotyped in the Leuven cytogenetic center between the years 1966 and 1987. In the group of 544 Klinefelter patients special attention was paid to (1) the age at diagnosis, (2) social and marital status of the postpubertal males, (3) physical and intellectual abilities of the prepubertal boys, (4) delineation of the concurrence of Klinefelter syndrome and fragile X syndrome, and (5) the frequency of malignancies. In 25 patients with other X-chromosome polysomies (2 n48 chromosomes) genotype/phenotype correlation is reviewed, especially for the patients with 48,XXYY and 49,XXXXY karyotypes. Finally, double aneuploidy and rare structural X-chromosome aberrations are briefly discussed.     

Proteolysis of human alpha 2-macroglobulin without hydrolysis of the internal thiolesters or expression of the receptor recognition site

Proteolysis of human alpha 2-macroglobulin (alpha 2M) in the bait region is the prerequisite and necessary trigger for the trapping of the proteinase by a massive conformational change of alpha 2M. This labilization of the native conformation of alpha 2M is mediated by activation of the internal thiolesters, but the underlying mechanism is unknown. We now describe observations on proteolysis of human alpha 2M without concomitant hydrolysis of the internal thiolesters or conformational change. This proteolysis was obtained with a novel bacterial proteinase we recently used to isolate the receptor-binding domain from alpha 2M (Van Leuven, F., Marynen, P., Sottrup-Jensen, L., Cassiman, J.-J., and Van Den Berghe, H. (1986) J. Biol. Chem. 261, 11369-11373). This proteinase is not inhibited by alpha 2M, and therefore it was possible to study its effect on native alpha 2M at pH 4.5, conditions used previously to produce the receptor-binding domain (Van Leuven, F., Marynen, P., Sottrup-Jensen, L., Cassiman, J.-J., and Van Den Berghe, H. (1986) J. Biol. Chem. 261, 11369-11373). The major observations are that despite extensive proteolysis, alpha 2M largely retained its native conformation as shown by rate electrophoresis, the absence of binding of monoclonal antibody F2B2, and the incorporation of [14C]methylamine into a 145-kDa fragment of alpha 2M. Moreover, the derivative still bound trypsin to 88% of control values. Treatment of the derivative with trypsin or methylamine produced the conformational change as with intact alpha 2M, and concomitantly released the receptor-binding domain. This indicated that proteolysis at Lys1313-Glu also proceeded in native alpha 2M. At least one more major proteolysis site was deduced from the observation of a 27-kDa heat-induced fragment, the 145-kDa [14C]methylamine-labeled fragment, and from the presence of the 20-kDa receptor-binding domain. These results demonstrate indirectly the particular relation of the bait region to the internal thiolesters and illustrate further the domain-structure of alpha 2M and the expression of the receptor-recognition site by activation of the internal thiolesters.     

Post-translational modification of the beta-subunit of the human fibronectin receptor

Monoclonal antibody DH12, directed against the beta-subunit of the fibronectin receptor recognizes a doublet of proteins (100 and 110 kDa) in Western blots of solubilized whole fibroblasts. Pulse-chase experiments with [35S]methionine in human skin fibroblasts suggested that the two proteins might be metabolically related as precursor (100 kDa) and product (110 kDa). Endo H digestion and [3H]fucose labeling suggested that maturation converted the high-mannose oligosaccharides (100 kDa) to the endoglycosidase H resistant complex type (110 kDa). This was supported by N-glycanase digestion and by chemical deglycosylation which showed a single polypeptide. Surface iodination of intact cells labeled only the presumed mature beta-subunit.     

Lycorine: a eukaryotic termination inhibitor?

The effect of the alkaloid lycorine on viral protein synthesis was studied in poliovirus-infected HeLa cells. The incorporation of [3H]leucine was inhibited by lycorine in a dose-dependent way, although lycorine never completely abolished translation. Using polyacrylamide gel electrophoresis, the viral proteins were identified as derived from the P1 (5' terminal), P2 (middle), or P3 (3' terminal) region of the poliovirus translation unit. The residual labeling of viral proteins in the presence of lycorine was mainly due to synthesis of P1 proteins and slightly less to P2 proteins, while virtually no P3-derived proteins were made. It is suggested that lycorine may act at the level of termination.     

Avidin-HRP conjugates in biotin-avidin immunoenzyme cytochemistry

Avidin-HRP conjugates were prepared, analysed and tested for avidin-biotin immunocytochemistry. Suitable biotinylation of enzymes, antigens and antibody was obtained by reacting biotin at equimolar ratio to epsilon aminogroups in proteins. The avidin-biotin interaction was used for immunocytochemical detection of phenomena in the field of immunology, i.e. immune complex trapping, specific antibody forming cells and in serology for the cytochemical detection of human auto-antibodies to basement membrane components. Avidin-HRP conjugation using the two step glutaraldehyde method gave a very small amount of monomeric, low molecular weight conjugate with excellent performance. Avidin-HRP conjugation using the periodate method was modified at two points. The first modification concerns the molar ratio of avidin to HRP in the reaction mixture which was brought to about equimolarity. The second modification concerns the periodate concentration which was decreased five fold, ten fold and twenty fold. Decreasing the periodate concentration decreased the amount of polymeric conjugate. Optimal amounts of monomeric, low molecular weight conjugate were obtained with a ten fold decrease of the periodate concentration. Comparable cytochemical results were obtained with monomeric conjugates obtained using both preparation methods.     

Changes in ascorbic acid content and ascorbate peroxidase activity during the development of Acetabularia mediterranea

We cloned ras-related sequences from goldfish genomic libraries constructed as recombinants using the lambda phage. Restriction enzyme mapping of the clones obtained revealed three kinds of ras-related sequences among approximately 350,000 genomic clones. One of these clones was partially sequenced. Comparison with the nucleotide sequences of mammalian ras genes showed that the determined sequences covered the predicted amino acid coding regions and parts of the intervening regions. The predicted amino acid sequences of the cloned ras-related goldfish gene suggested that the coding region is localized separately in DNA, and that its exon-intron boundaries are exactly the same as those of corresponding mammalian genes. The nucleotide and amino acid sequences of the goldfish ras-related gene may have extensive homologies to mammalian p 21 protein. Among the three mammalian ras proteins, the predicted amino acid sequence of the sequenced ras-related goldfish clone is most closely homologous (96%) to the Kirsten ras protein. Differences in the predicted amino acid sequence were greatest in the sequence predicted from the fourth exon; fewer differences were found in the sequence from the third exon, and only slight or no differences were found in the sequence predicted for the first and second exons. The 12th and 61st amino acids from the N-terminal of the protein, which are thought to be critical positions for GTP binding and catalysis, are both conserved in the goldfish protein.(ABSTRACT TRUNCATED AT 250 WORDS)     

8q24.12 Interstitial deletion in trichorhinophalangeal syndrome type I

Summary In the present report we present the first example of a small interstitial 8q24.12 deletion in a patient with trichorhinophalangeal syndrome type I.