Preliminary report of molecular detection of retinoblastoma gene mutations

To develop gene diagnosis for retinoblastoma predisposition, it is necessary to disclose the retinoblastoma gene mutations or deletions in detail. Genomic DNA from tumor and peripheral white blood cells in 33 patients with retinoblastoma was detected with 3.8kb probe derived from 3' end of retinoblastoma gene cDNA. The gene abnormalities, including deletion, partial deletion and rearrangement, were found in 18 patients. Further research will be aimed at microdeletions or mutations for those patients without detectable variations in Southern hybridization.

Retinoma and phthisis bulbi of retinoblastoma. 1. Clinical and genetic analysis

Retinoma and phthisis bulbi of retinoblastoma are rare entities found in retinoblastoma patients and their relatives. Eleven cases of phthisis bulbi of retinoblastoma and 9 cases of retinoma were identified from 1966 to 1991 in our center. The clinic data show that retinoma and phthisis bulbi are closely related to the retinoblastoma gene. Enucleation should be carried out as soon as possible without hesitation for the phthisis of eyes with retinoblastoma. Genetic counseling and frequent observation should be paid attention to retinoma patients and their offspring. The mechanism of retinoma developed is discussed. We propose that the diversity of second mutation might be the cause of retinoma.

Detection of gene alteration for color vision defects by polymerase chain reaction

According to the fact that the abnormalities of visual pigment genes were always involved in the changing of the exon 5, two oligonucleotide primers were designed to amplify the exon 5 of red pigment gene and green pigment gene. After electrophoresis of the PCR products digested with Rsal or Sau3A, the DNA fragments from the exon 5 of red pigment gene (RPG) and green pigment gene (GPG) were separated since there are different restriction endonuclease sites. On the other hand, we analyzed the exon 5 related fragment by Southern blot hybridization with probe out of the 3' end of the fourth intron of green pigment gene. The results of PCR are consistent with nucleic acid hybridization. PCR technique will be of value in prenatal evaluation and genetic counselling.

[Visual pigment genes for color vision defects]

Applying recombinant DNA techniques, the structures of red pigment gene (RPG) and green pigment gene (GPG) were analyzed for 43 patients with protan or deutan (including 3 females), 4 normal relatives and 3 carriers out of 3 families, as well as 11 normal controls. Abnormality of RPG was detected in all 19 protan and that of GPG was found in 14 out of 24 deutan. In about 80% (32/40) of protan and deutan the changing of exon 5 for RPG or GPG was discovered. In protan the normal RPG was replaced by a 5' red -3' green hybrid gene. Some of the deutan had no GPG, some had 5' green -3' red hybrid gene with or without GPG. Furthermore, the exon 5 of RPG and GPG was amplified by polymerase chain reaction (PCR) and further analyzed by Rsa I digestion. The results for PCR are identical to that of Southern blot hybridization.

[Visual pigment genes for color vision defects]

Applying recombinant DNA techniques, the structures of red pigment gene (RPG) and green pigment gene (GPG) were analyzed for 43 patients with protan or deutan (including 3 females), 4 normal relatives and 3 carriers out of 3 families, as well as 11 normal controls. Abnormality of RPG was detected in all 19 protan and that of GPG was found in 14 out of 24 deutan. In about 80% (32/40) of protan and deutan the changing of exon 5 for RPG or GPG was discovered. In protan the normal RPG was replaced by a 5' red -3' green hybrid gene. Some of the deutan had no GPG, some had 5' green -3' red hybrid gene with or without GPG. Furthermore, the exon 5 of RPG and GPG was amplified by polymerase chain reaction (PCR) and further analyzed by Rsa I digestion. The results for PCR are identical to that of Southern blot hybridization.

Measurement of the refractive index and thermal refractive index coefficients of Nd:YAP crystal

The principal refractive indices of yttrium aluminate crystal doping with 1-wt.% neodymium (Nd:YAP) have been measured by a minimum deviation method for the wavelengths 0.5398, 0.6328, and 1.0795 microm in the temperature range of 289-435 K. The thermal refractive index coefficients have been obtained at these wavelengths, and they are all positive and slightly decrease with increased wavelength. The constants of the single term Sellmeier equation are also given for the 273-420 K temperature range. These constants are in linear relationship with temperature in the 4 x 10(-3) error range.

The effect of thiosulphate and other inhibitors of autotrophic nitrification on heterotrophic nitrifiers

It has been found that heterotrophic nitrification by Thiosphaera pantotropha can be inhibited by thiosulphate in batch and chemostat cultures. Allythiourea and nitrapyrin, both classically considered to be specific inhibitors of autotrophic nitrification, inhibited nitrification by Tsa. pantotropha in short-term experiments with resting cell suspensions. Hydroxylamine inhibited ammonia oxidation in chemostat cultures, but was itself fully oxidized. Thus the total nitrification rate for the culture remained the same. Heterotrophic nitrification by another organism, a strain of "Pseudomonas denitrificans" has also been shown to be inhibited by thiosulphate in short term experiments and in the chemostat. During these experiments it became evident that this strain is able to grow mixotrophically (with acetate) and autotrophically in a chemostat with thiosulphate as the energy source.