Abnormal pattern detected in fragile-X patients by pulsed-field gel electrophoresis.

The fragile-X syndrome is the most frequent inherited form of mental retardation, with an incidence of 1 in 1,500 males. It is characterized by the presence of a fragile site at Xq27.3 induced in vitro by folate deprivation or by inhibitors of deoxynucleotide synthesis. Its mode of inheritance is unusual for an X-linked trait, with incomplete penetrance in both males and females. Some phenotypically normal males transmit the mutation to all their daughters who rarely express any symptoms, but penetrance is high in sons and daughters of these carrier women. Genetic and physical mapping of the Xq27-q28 region has confirmed that the disease locus is located at or very near the fragile site. Hypotheses proposed to account for the abnormalities in the inheritance of the disease include sequence rearrangements by meiotic recombination or a mutation that affects reactivation of an inactive X chromosome during differentiation of female germ cells. To detect such rearrangements, or methylation changes that may reflect a locally inactive X chromosome, we used pulsed-field gel analysis of DNA from fragile-X patients with probes close to the fragile-X locus. The probe Do33 (DXS465) detected abnormal patterns in fragile-X patients, but not in normal controls or in non-expressing male transmitters.     

Truncating mutations in the last exon of NOTCH2 cause a rare skeletal disorder with osteoporosis

Hajdu-Cheney syndrome is a rare autosomal dominant skeletal disorder with facial anomalies, osteoporosis and acro-osteolysis. We sequenced the exomes of six unrelated individuals with this syndrome and identified heterozygous nonsense and frameshift mutations in NOTCH2 in five of them. All mutations cluster to the last coding exon of the gene, suggesting that the mutant mRNA products escape nonsense-mediated decay and that the resulting truncated NOTCH2 proteins act in a gain-of-function manner.     

Immunohistochemical localization of carbonic anhydrase C in the rat central nervous system]

With obtention of specific antibodies against isoenzyme C of Rat carbonic anhydrase it was possible to realize an immunohistochemical localisation in central nervous system of Rat. Results showed that this enzyme was mainly localized in cytoplasm of oligodendroglial cells and in low concentration in myelin sheath.     

Purification of rat brain guanylate cyclase]

The purification of guanylate cyclase has been achieved. After electrophoresis on polyacrylamide gel only one protein band was observed. The low factor of purification must therefore be ascribed to the loss of an activator of guanylate cyclase. Stimulation of the activity by nitroprusside is also lost during purification. The purified enzyme follows Michaelis--Menten kinetics, it is activated by Mn++ ions and inhibited by triphospho nucleotides.     

Purification of calf thymus adenosine diphosphate ribose polymerase]

Calf thymus poly ADPR polymerase has been purified to electrophoretic homogenity. The enzyme has a molecular weight of 120,000 +/- 10,000 dalton. The substrate affinity is very high (apparent Km 82.5 micrometer). The presence of exogenous DNA does not appear to be a requisite for enzymatic activity of the purified enzyme.