The stability of foreign protein production in genetically modified plant cells

Summary The stability of foreign protein production in genetically engineered plant cells was studied. A cultured tobacco cell line was transformed with a chimeric molecule carrying a bacterial gene, ß-glucuronidase (GUS), under plant regulatory sequences. The specific GUS activity was monitored for 294 days with ten independently transformed cell lines either in the presence or the absence of selectable antibiotics. Specific GUS activity was stably maintained in five lines. About a two-to four-fold increase in the GUS activity was observed from three cell lines. The remaining two cell lines lost the activity within the first 70 to 210 days. The presence of antibiotics did not significantly alter the stability of the foreign protein production in all cell lines examined.     

Analysis of centromere size in human chromosomes 1, 9, 15, and 16 by electron microscopy.

Human chromosomes were treated with 5-azacytidine and analyzed by whole-mount electron microscopy. This base analogue produces undercondensation of heterochromatin and separation of the centromere from the bulk of pericentromeric heterochromatin in chromosomes 1, 9, 15, and 16, which allows clear delimitation of the centromere regions. A quantitative analysis of centromeres showed that chromosomes 1, 9, and 16 have centromeres of different size. The centromere of chromosome 15 is similar in size to that of chromosome 9 and different from those of chromosomes 1 and 16. No interindividual variation for centromere size was found. A positive correlation between centromere and chromosome size was found for the chromosomes analyzed.     

The beta-adrenergic receptor-regulated 1,4-dihydropyridine calcium channel receptor sites in coronary artery smooth muscle.

The cross-regulatory communication from beta-adrenergic receptors to 1,4-dihydropyridine (DHP) Ca2+ channel agonist and antagonist binding sites and cooperativity between DHP binding sites were studied in microsomal membranes of canine coronary artery (purified to a factor 2.9 for DHPs). The maximal number of binding sites (Bmax) identified in coronary artery microsomal membranes (CAM) with Ca2+ channel agonist (-)-S-(3H)BAY K 8644 was two times higher than Bmax of sites labelled with Ca2+ channel antagonist (+)-(3H)PN 200-110. The exposure of CAM to isoprenaline was accompanied with down-regulation of beta-adrenergic receptors and with increase in binding capacity for DHPs. The increase in Bmax was proportional in both groups of experiments and was related to increased affinity of DHPs. The 1,4-DHP binding sites identified in vascular smooth muscle showed characteristics typical for classification of specific 1,4-DHP receptor on Ca2+ channels. The binding was of high affinity, saturable and reversible, it showed stereoselectivity and it was positively modulated by beta-adrenergic stimulation and its showed cAMP and GTP sensitivity. The results support the hypothesis that beta-receptors also regulate the mode of Ca2+ channels in coronary artery smooth muscle.     

Hemopoiesis stimulating and radioprotective effects of carboxymethylglucan.

Carboxymethylglucan, a novel soluble derivative of beta-1,3-glucan, was found to enhance hemopoietic recovery in sublethally gamma-irradiated mice and to increase survival in lethally irradiated animals when given 24 hours prior to irradiation. Postirradiation treatment with carboxymethylglucan also induced favourable effects in terms of survival when used in combination with preirradiation cystamine administration.     

Renal amino acid excretion and aging

The urinary excretion and serum concentration of amino acids were studied in 62 healthy individuals aged 15 to 70 years. In elderly subjects (61-70 years), it was found that renal amino acid clearance per 100 ml GFR (fractional excretion, FE) rose significantly in the following amino acids: CYS, VAL, MET, ILE and LEU. Since the serum concentrations of these amino acids showed no significant changes, but the GFR was reduced, it can be concluded that the raised FE of these amino acids was due to a decrease in their effective tubular reabsorption. A significant correlation was found between FENa and FE of most amino acids including those mentioned above. The findings support the assumption that changes in tubular Na+ transport probably participate in the changes of tubular amino acid transport in elderly individuals.     

The effect of experimental hyperthyroidism on renal and adrenal weight increase in mice.

The mouse kidneys are enlarged after the administration of thyroxine and this influence is not mediated through androgens. The administration of thyroxine increased the weight of the adrenals and the level of plasma corticosterone. Besides the direct effect of the thyroid hormones on the kidney, our findings indicate that the excess of triiodothyronine and thyroxine stimulates the activity of adrenals indirectly and evokes hyperadrenocorticism which could be related to the action of adrenal steroids on kidney function and kidney growth. In accordance with the above mentioned hypothesis it has been shown that aminoglutethimide, a potent blocker of adrenal steroidogenesis, decreases the level of plasma corticosterone and inhibits the enlargement of the kidney in hyperthyroid mice in spite of the high serum thyroxine values.     

Regulation by estrogen through the 5'-flanking region of the transforming growth factor alpha gene.

Expression of transforming growth factor alpha (TGF alpha) mRNA and protein can be stimulated by estrogens such as 17 beta-estradiol (E2) in estrogen-responsive rodent and human breast cancer cells. To ascertain if E2 can directly regulate TGF alpha expression through the 5'-flanking region of the human TGF alpha gene, E2-responsive MCF-7 or ZR-75-1 human breast cancer cells or E2-nonresponsive MDA-MB-231 breast cancer cells were transiently transfected with a plasmid containing an 1140-base pair (bp) Sac-I fragment of the TGF alpha 5'-flanking region ligated to the chloramphenicol acetyltransferase (CAT) gene. Cells that were transfected and subsequently treated with physiological concentrations of E2 (10(-11)-10(-8) M) for 24 h exhibited a 2- to 10-fold increase in CAT activity. The E2 stimulation of CAT activity was dose-dependent with an increase first found at 10(-10) M E2. The increase in CAT activity could be detected within 24-36 h after the addition of E2. There was no significant change in CAT activity in transiently transfected MDA-MB-231 cells as mediated through the TGF alpha 5'-flanking region after E2 treatment. MCF-7 cells were also transiently transfected with different fragments of the TGF alpha 5'-flanking region ligated to the luciferase gene. In the absence of E2 treatment, no detectable luciferase activity was found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic and developmental analyses of chaetae pattern formation in Drosophila tergites

Summary The role of the achaete-scute complex and extramacrochaetae, Notch, Delta, Enhancer of split and Hairless genes in chaeta patterning in Drosophila tergites was studied in genetic mosaics and in mutant combinations. The mutant phenotypes of different alleles of each gene can be ordered in characteristic topographical seriations. These seriations are related to the pattern of proliferation of histoblasts and the time of singularization of sensory organ mother cells from surrounding epidermal cells. Genetic mosaics of lethal alleles show that these genes are fundamentally involved in this singularization and subsequent differentiation. The study of mutant combinations of alleles of these genes reveals specific relationships of epistasis and synergism between them. The results suggest that spatial and temporal variations in achaete-scute complex functional products in cells, modulated by the activity of other genes involved in signal transduction, define the patterned differentiation of sensory organs in tergites. Offprint requests to: A. García-Bellido     

Oenanthe aquatica (L.)Poir.: Seed reproduction,population structure,habitat conditions and distribution in Czechoslovakia

The paper summarizes data concerning the biology and ecology ofOenanthe aquatica. The species is commonly distributed all over Czechoslovakia, from lowlands to the submontane belt, especially in fishpond and river basins.O. aquatica shows no special relationship to the chemical and physical soil properties, and is well adapted to habitats with a changing water level. The reproduction ofO. aquatica depends on emerging of the bottom. The most developed populations are formed by biennial plants and arise in the year following summer or autumn drainage.     

Quercus ilex browse utilization by Caprini in Sierra de Cazorla and Segura (Spain)

The impact of domestic and wild Caprini browsing on Quercus ilex has been examined in an area of the Sierra de Cazorla. Vegetation as a herbivore food supply, herbivore feeding regime and density in the study area during six sampling periods throughout two years, has been quantified. Wild Caprini show diets similar to the available vegetation, whereas domestic Caprini tend more towards the trophic specialities (browsing or grazing) of their genus. Nevertheless, this tendency was more pronounced in domestic goats than in sheep. A hypothetical estimate of Q. ilex intake by each species under the study conditions was carried out. It was found that domestic Caprini have a greater impact on the holm oak than wild Caprini, density and feeding-niche deviations being the main factors responsible for this situation.Abbreviations DM= dry matter