Lethal polymalformative syndrome with 13q deletion secondary to a maternal X; 13 translocation

The authors report the case of a newborn full term delivered by cesarean section for evolutive hydrocephalus, in the last month of pregnancy. This hydrocephalus was confirmed by echography after birth. This also having ambiguous genitalia and atresia ani, he died a few hours later. No evidence of infectious or toxic embryofetopathy was found out as an etiologic factor, but the karyotype of the baby showed a 13 q deletion and that of the mother a non reciprocal Xqter; 13q31.3 translocation. The study of inactivation of X indicated that the inactivated X chromosome in each cell was normal. On this occasion, the authors try to bring together the main points of "13q-syndrome" and discuss on the practical approach of antenatal diagnosis which they could propose to the couple.     

Chromosome banding and genome compartmentalization in fishes

The diploid chromosome number of the Chinese raccoon dog varies from 54 (no B chromosomes) to 58 (4 B chromosomes). The B chromosomes are totally heterochromatic. An electron microscopic study was made of the synaptonemal complexes (SC) in spermatocytes of these animals. The SC karyotype consists of 27 regular chromosome pairs (autosomes and the sex chromosomes) plus the B chromosomes. The Bs pair effectively with one another at pachytene, but the SC axes of the B chromosomes are much denser than those of the A chromosomes. Depending on the number of Bs, both bivalents and multivalents have been observed. When three B chromosomes are present in a cell, parallel alignment of all three SCs can be seen. Formation of multivalents indicates high homology among these supernumerary heterochromatic chromosomes. Fusiform bulges are found along unpaired regions of all chromosomes which are particularly pronounced in diplotene.     

Mini-F E protein: the carboxy-terminal end is essential for E gene repression and mini-F copy number control

Mini-F is a segment of the conjugative plasmid F consisting of two origins of replication flanked by regulatory regions, which ensure a normal control of replication and partitioning. Adjacent to the ori-2 origin is a complex coding region that consists of the E gene overlapped by three open reading frames with the coding potential for 9000 Mr polypeptides here designated 9 kd-1, 9 kd-2 and 9 kd-3. In this paper, we show that open reading frame 9 kd-3 is preceded by active promoter and Shine-Dalgarno sequences. The E coding region specifies: an initiator of replication, which acts at the ori-2 site; a function that negatively regulates the expression of the E gene; and a function involved in mini-F copy number control. To assign one of these functions to one of the overlapping coding sequence, we have isolated, characterized and sequenced mutations mapping in the E coding region. In this paper, we analyse two mutations (cop5 and pla25) that abolish the repression of the E gene. As these mutations affect the primary structure of protein E itself but not the 9 kd polypeptides, we conclude that protein E takes part in the negative regulation of its own synthesis. In addition, the localization of the cop5 and pla25 mutations indicates that the carboxy-terminal end of the E protein is involved in the autorepression function. The cop5 mutation causes an eightfold increase of the mini-F copy number. The pla25 mutation leads to the inability of the derived mini-F plasmid to give rise to plasmid-harbouring bacteria. The ways in which the cop5 and pla25 mutations may lead to such phenotypes are discussed in relation to the different functions mapping in the E coding sequence.     

Effect of vitamin on 2-deoxy-d-glucose uptake in human fibroblast cultures

Summary 2-Deoxy-d-glucose (2-DOG) uptake was tested in human fibroblast cultures in the presence and absence of vitamin E. Addition of 10 μg/ml vitamin E to the culture medium significantly reduced this uptake for 2-DOG concentrations of 0.005, to 10 mmol/liter (P≤0.01). The decrease of 2-DOG uptake was inversely proportional to the rise in 2-DOG concentration (P≤0.01). The presence of vitamin E reduced by 71% the average cellular level of lipid peroxides (expressed as thiobarbituric acid reactive substances) and caused a small but significant decrease in the cholesterol concentration (P≤0.01). These last results might explain the decrease in 2-DOG uptake observed in the presence of vitamin E.     

Comparative use of fructose and glucose in human liver and fibroblastic cell cultures

Summary The effect of fructose as a substitute for glucose in cell culture media was investigated in human skin fibroblast and liver cell cultures. Cells were grown for between 2 and 10 days in identical flasks in four different media, containing 5.5, mmol·1⁻¹ and 27.5 mmol·I⁻¹ glucose and fructose, respectively. In the presence of fructose, cell growth was stimulated, but less in liver cells than fibroblasts. At Day 6, increases were observed in [³H]thymidine incorporation, protein levels, and amino acid consumption, and a reduction was noted in ATP levels. In media containing 5.5, mmol·1⁻¹ glucose or fructose, consumption of fructose was four times lower than that of glucose at Day 3 and did not rise until Day 6. In fructose media, the lactate production was very low (four to five times less than that of glucose) and the pH values were always higher. Some findings were different for the fibroblasts and liver cells, owing to the specific characteristics of these two cell types in culture; this applied especially to the effects of glucose and fructose concentrations of 27.5 mmol·1⁻¹. Several possible explanation for the stimulation of cell growth in fructose medium were discussed. This work was supported by grants for the Institut National de la Santé et de la Recherche Médicale (ATP 82-79-114) and the Unité d'Enseignement et de Recherche, Le Kremlin-Bicêtre, Université Paris-Sud (C. R. 848).     

Detailed cell cycle analysis in human lymphocytes; Application to γ-irradiated cells

Summary A method based on BrdU incorporation for analyzing in detail the kinetics of the cell cycle is described. The S phase has been subdivided into five subphases, each recognizable by their BrdU incorporation pattern at metaphase. The method can be useful for the study of abnormal cell cycles, and may have particular application in mutagenesis studies concerning the various subphases of the S phase, without using synchronization techniques. An application of the method is described, showing that -irradiation, during the course of the S phase, leads to a lack of cells which were in early S phase at the time of irradiation. This finding can be related either to a higher lethality at this stage of the cell cycle or to a delay in completion of DNA replication after irradiation.Hoider of a C.E.C. scholarship