Telomere-binding protein from the nuclear envelope of oocytes of the frog Rana temporaria

The identification of telomere-binding protein on the nuclear envelope (NE) of the frog oocyte is reported here. Nuclei and the NE were isolated manually and extracted, and the extracts were used to search for DNA-protein specific interactions. Fragment of the Tetrahymena telomere sequence (T2G4)130 from the plasmid YAC4 was used as a labeled probe. DNA-protein complexes revealed by gel shift assay were cut out of the gel and injected into a guinea pig. The antibodies obtained have common antigenic determinants with keratins; this was shown on Western-blot under conditions of competitive binding. Antibodies were purified on an affinity column with keratins attached and used in the following work. Antibodies recognize one protein with molecular weight 70 kD among the NE proteins; no signal was obtained to proteins isolated from the inner part of the oocyte, but two polypeptides of 70 and 120 kD were detected in the proteins from frog liver nuclei. The 70-kD protein is situated on the NE in a distinct pattern that looks like a network, probably of double-dots as was shown by immunofluorescence of the NE. Electron-microscope immunogold staining showed that the protein is localized in the outer surface of the oocyte NE within cup-like structures attached to the membrane. Combined in situ hybridization using the mammalian telomeric DNA sequence (T2AG3)135 and immunocytochemistry using antibodies showed them to be colocalized in the frog blood cells, so telomere sequence coexists with the protein in the interphase nuclei. Most of the telomeres are fused in highly differentiated blood cells though a double dot signal is visible. The signal appears to be localized in the outer part of the nuclei. The existence of membrane telomere-binding protein allows a discussion of the attachment of the telemeters to the membrane.     

Simulation and optimization of an organic-impurity oxidization reactor with a fixed porous bed and an electric heating element

A reactor for oxidization of low-caloric-value organic impurities contained in the air has been simulated. It comprises a tube with a recuperator, filled with a porous carcass mix, and includes a heating element. The influence of the heating-element placement, the heat losses through the upper cover of the reactor, the flow rate of a gas mixture, and the power of the heater on the maximum temperatures of the porous carcass and the gas and on the concentration of the incompletely oxidized organic impurity at the output of the reactor has been investigated. It is shown that, to burn an impurity completely, it will suffice to heat the gas δT_e to 300 K. It has been established that it is best to place a heater at the level of the upper cut of the inner tube of the reactor. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 5, pp. 3–10, September–October, 2006.     

Mutation process in mini-satellites

Minisatellites are tandemly repeated DNA sequences with repeat units in the range 6-100 bp. They are preferentially located in subtelomeric euchromatin of chromosomes of higher eukaryotes. Minisatellite loci frequently show variability in allele length. This variability is a consequence of high frequency of mutations which change repeat copy number of locus. The most part of minisatellite mutations are germline specific and possibly meiotic. Examples of different mutations and involved genomic mechanisms are reviewed in this paper. A possible biological role of minisatellites is discussed.     

Effect of smoking on breast cancer in carriers of mutant BRCA1 or BRCA2 genes

BACKGROUND: Smoking has carcinogenic effects, and possibly antiestrogenic effects as well, but it has not been found to be a risk factor for breast cancer in women in the general population. However, hereditary breast cancer is primarily a disease of premenopausal women, and interactions between genes and hormonal and environmental risk factors may be particularly important in this subgroup. METHODS: We conducted a matched case-control study of breast cancer among women who have been identified to be carriers of a deleterious mutation in either the BRCA1 or the BRCA2 gene. These women were assessed for genetic risk at one of several genetic counseling programs for cancer in North America. Information about lifetime smoking history was derived from a questionnaire routinely administered to women who were found to carry a mutation in either gene. Smoking histories of case subjects with breast cancer and age-matched healthy control subjects were compared. Odds ratios for developing breast cancer were determined for smokers versus nonsmokers by use of conditional logistic regression for matched sets after adjustment for other known risk factors. RESULTS: Subjects with BRCA1 or BRCA2 gene mutations and breast cancer were significantly more likely to have been nonsmokers than were subjects with mutations and without breast cancer (two-sided P = .007). In a multivariate analysis, subjects with BRCA1 or BRCA2 mutations who had smoked cigarettes for more than 4 pack-years (i.e., number of packs per day multiplied by the number of years of smoking) were found to have a lower breast cancer risk (odds ratio = 0.46, 95% confidence interval = 0.27-0.80; two-sided P = .006) than subjects with mutations who never smoked. CONCLUSIONS: This study raises the possibility that smoking reduces the risk of breast cancer in carriers of BRCA1 or BRCA2 gene mutations.     

The potentials of indirect calorimetry in the differential assessment of the metabolic status of obese patients with insulin-independent diabetes mellitus

Twenty-one obese patients with non-insulin dependent diabetes mellitus, 16 female and 5 male ones, were fed similar isocaloric rations, differing only by the share of substitution of the traditional protein products (0%, 60%, 30%, 45%) in the Danpro-S, Danpro-Fibre soybean protein concentrate. The parameters tested were daily glycemia, C-peptides, blood hydrocortisone, and urinary excretion of nitrous metabolites. Indirect calorimetry was used to assess the protein, fat, and carbohydrate oxidation rates at rest. Addition of proteins of a plant origin to the diets of such patients was associated with significant changes of the energy metabolism at rest at the expense of increased oxidation of carbohydrates and reduced protein catabolism, that may be regarded as a favorable effect. In this patient population a 30% soybean diet brings about an almost maximal positive effect in patients with the first degree of obesity, whereas in those with the second degree of obesity such effect is attained by the 45% soybean diet.