Superoxide anion scavenging effect and superoxide dismutase activity ofGinkgo biloba extract

Summary Ginkgo biloba extract is known to be efficient in diseases associated with free radical generation. The purpose of this work was to study, under in vitro conditions, the action ofGinkgo biloba extract (Gbe) against superoxide anion ( ), which is directly or indirectly implicated in cell damage.Gbe appears to have both an scavenging effect and also a superoxide dismutase activity. Its antiradical effect was demonstrated by low temperature electron spin resonance and in a non-enzymatic system (phenazine methosulfate-NADH), and its enzymatic activity was shown by polarographic determination.     

Superoxide dismutase activity in the Spanish population

Summary Superoxide dismutase is an enzyme that catalyzes the dismutation of superoxide radicals to hydrogen peroxide and molecular oxygen. This superoxide radical is produced by all aerobic cells as a normal metabolic intermediate of molecular oxygen, and is dangerous for the cell because it induces the inactivation of various enzymes, lipid peroxidation and mutations. Superoxide dismutase can therefore be considered as a protective enzyme. The purpose of this work was to determine the level of superoxide dismutase activity in the Spanish population, and to study the factors that influence this activity. The superoxide dismutase activity of 2397 individuals was determined using the method described by Minami and Yoshikawa. The superoxide dismutase activity level in the adult Spanish population was found to be 4.16±0.89 Units/ml of blood. No significant variations with respect to sex were detected. But it was observed that the superoxide dismutase activity level was 9% higher in the young urban Spanish population.     

Cell adhesion in the life cycle ofDictyostelium

three forms of cell adhesion determine the life cycle ofDictyostelium: i) adhesion of bacteria to the surface of the growing amoebae, as the prerequisite for phagocytosis;ii) cell-substrate adhesion, necessary for both locomotion of the amoebae and migration of the slug;iii) cell-cell adhesion, essential for transition from the unicellular to the multicellular stage. Intercellular adhesion has received the most attention, and fruitful approaches have been developed over the past 25 years to identify, purify and characterize cell adhesion molecules. The csA glycoprotein, in particular, which mediates adhesion during the aggregation stage, is one of the best defined cell adhesion molecules. The molecular components involved in phagocytosis and cell-substratum adhesion are less well understood, but the basis has been laid for a systematic investigation of both topics in the near future.     

Stereological analysis of lipofuscin in the central nervous system ofTorpedo marmorata: correlation with superoxide dismutase distribution

Summary It was observed that superoxide dismutase activity was inversely proportional to the amount of lipofuscin present in the various anatomotopographical areas of theTorpedo marmorata central nervous system. These results support the theory that age pigments are a product of free lipoperoxidation induced by free radicals.Part of the present work was presented at XIIth Int. Pigment Cell Conference, Giessen (FRG), 17–19 September 1983.     

Purification and some properties of hemagglutinin from the Myxomycete,Physarum polycephalum

A new hemagglutinin was isolated from the plasmodium ofPhysarum polycephalum by salting out with ammonium sulphate followed by chromatography on DE-32, DEAE-Toyopearl and hydroxyapatite. This hemagglutinin, named physarumin, was purified 1000-fold over crude extracts. The molecular weight of physarumin was determined to be 22,000 by size exclusion chromatography on Bio-Gel P-60 and 8,700 by SDS-polyacrylamide gel electrophoresis. Physarumin agglutinated rabbit, guinea pig, horse and human erythrocytes. Physarumin-induced hemagglutination was inhibited by fetuin and ₁ glycoprotein, but not by commercially available mono-and disaccharides. Hemagglutinating activity was blocked by EDTA, and was restored by adding Ca²⁺ but not by Mg²⁺.     

Ras proteins in the control of the cell cycle and cell differentiation

The Ras family of small GTPases includes three closely related proteins: H-, K-, and N-Ras. Ras proteins are involved in the transduction of signals elicited by activated surface receptors, acting as key components by relaying signals downstream through diverse pathways. Mutant, constitutively activated forms of Ras proteins are frequently found in cancer. While constitutive Ras activation induces oncogenic-like transformation in immortalized fibroblasts, it causes growth arrest in primary vertebrate cells. Induction of p53 and cyclin-dependent kinase inhibitors such as p15^INK4b, p16^INK4a, p19^ARF, and p21^WAF1 accounts for this response. Interestingly, while ras has usually been regarded as a transforming oncogene, the analysis of Ras function in most of the cellular systems studied so far indicates that the promotion of differentiation is the most prominent effect of Ras. While in some cell types, particularly muscle, Ras inhibits differentiation, in others such as neuronal, adipocytic, or myeloid cells, Ras induces differentiation, in some cases accompanied by growth arrest. Several possible mechanisms for the pleiotropic effects of Ras in animal cells are discussed. Received 8 March 2000; received after revision 24 May 2000; accepted 24 May 2000     

Effect of photoperiod and all-female grouping on the estrous cycle of the bandicoot rat,Bandicota bengalensis

Summary Female bandicoot rats showing irregular cycles in 12L12D, were exposed to light-darkness cycles of 1L23D, 4L20D and 8L16D. Significant regularization of the estrous cycle was observed in 8L16D with most of the rats exhibiting a regular 3-day cycle and the regularity was further enhanced by all-female grouping (4/cage).     

Revisiting retinoblastoma protein phosphorylation during the mammalian cell cycle

It is widely accepted that phosphorylation of the retinoblastoma (Rb) protein during the G1 phase of the mammalian division cycle is a major control element regulating passage of cells into S phase and through the division cycle. The experiments supporting G1-phase-specific Rb phosphorylation and the historical development of this idea are reviewed. By making a rigorous distinction between 'growth cessation' and the phenomena of 'cell cycle exit' or 'G1-phase arrest', the evidence for the G1-phase-specific phosphorylation of Rb protein is reinterpreted. We show that the evidence for G1-phase phosphorylation of Rb rests on few experiments and a chain of reasoning with some weak links. Evidence is reviewed that growth conditions regulate the phosphorylation of Rb. A growth-regulated control system that is independent of the cell cycle explains much of the evidence adduced to support cycle-specific phosphorylation of Rb. We propose that additional experimental evidence is needed to decide whether there is a G1-phase-specific phosphorylation of Rb protein. Received 16 October 2000; received after revision 13 November 2000; accepted 15 November 2000     

Optical monitoring of activity of many neurons in invertebrate ganglia during behaviors

Summary Optical methods for monitoring neuron activity were developed because these methods lend themselves to simultaneous multiple-site measurements. With the use of new voltage-sensitive dyes, the dye-related pharmacology and photodynamic damage appear to be relatively unimportant. Using multiple-site measurements made with a 124-element photodiode array, we estimated that approximately 30 of the 200 neurons present in theNavanax buccal ganglion make action potentials during feeding and that approximately 300 of the 1100 neurons present in theNavanax buccal ganglion make are active during the gill-withdrawal reflex. The fact that a light mechanical touch to the siphon skin activated such a large number of neurons in the abdominal ganglion suggests that understanding the neuronal basis of the gill-withdrawal reflex and its behavioral plasticity may be forbiddingly difficult.     

Genetic and photoperiodic control of an avian reproductive cycle

European blackcaps,Sylvia atricapilla, with one breeding season per year, have a single-peaked annual testes cycle. However, African conspecifics from the Cape Verde Islands with two breeding seasons per annum demonstrate a two-peaked cycle. Both population-specific cycles reflect differences in the respective endogenous circannual rhythms. Experimental hybridization of birds of the two populations resulted in an intermediate pattern of testes cycle, thus demonstrating that there are genetic components for some temporal aspects in an avian reproductive cycle. Another characteristic of the African birds, their extremely rapid juvenile development and early sexual maturity (at an age of 5–6 months) proved largely to be a photoperiodic (short-day) effect in birds hatched in autumn. The same effect could also be induced in European conspecifics exposed to correspondingly short day-lengths.     

Titers of ecdysone, 20-hydroxyecdysone and juvenile hormone III throughout the life cycle of a hemimetabolous insect,the ovoviviparous cockroachNauphoeta cinerea

Summary Titers of ecdysone, 20-hydroxyecdysone and juvenile hormone III were measured in whole body extracts or hemolymph of embryos, first, penultimate and last stadium nymphs, and adult females ofNaupoheta cinerea. We used a gas-chromatography/mass spectrometry method for quantifying juvenile hormone and a radio-immunoassay for ecdysteroid determination. Juvenile hormone III is particularly abundant in the embryonic stage (up to 960 ng/g), at a low level in first and penultimate stadium nymphs (2–10 ng/ml) and almost absent in the last nymphal stadium; in the adult female the juvenile hormone titer rises to 180 ng/ml in hemolymph during rapid oocyte growth. The titers of ecdysone and 20-hydroxyecdysone undergo similar fluctuations in the embryonic and nymphal stages, being highest at the time of cuticle formation in the embryo and a few days before the nymphal and adult molts (around 100–200 ng/ml for exdysone and 2–4 g/ml for 20-hydroxyecdysone).Acknowledgments. We thank Mrs A. Tschan for rearing the cockroaches, Mr M. Kaltenrieder for drawing the graphs, Mr G.C. Jamieson and Mrs C. Reuter for GC/MS analyses. We are also grateful to the Swiss National Science Foundation (grant no. 3.291-0.82 to B. Lanzrein) and the United States National Science Foundation (grant no. PCM 82-08665 to D.A. Schooley) for their financial support.     

Mitotic cell cycle time in root meristems of tetraploid and related diploid pearl millet

Summary Mitotic cell cycle time was estimated from root meristems of tetraploid and related diploid stock (IP 1475) of pearl millet (Pennisetum typhoides). There is 38% increase in cell cycle time in tetraploid meristems compared of their related diploid stocks.Acknowledgment. The authors thank Dr. M. Krishna Rao for useful suggestions and UGC for financial assistance.     

Chromosome-breaking activity of extracts of the mushroomPaxillus involutus Fries ex Batsch

Summary Dry and presoaked seeds ofNigella damascena were treated with aqueous extracts of the mushroomPaxillus involutus. At the first mitosis after the onset of germination, metaphase chromosomes showed damage independent of the origin of the mushrooms. The damaging substance(s) is (are) thermostable. Except a few achromatic gaps, all the lesions observed are of the chromosome type, i.e. are induced at the pre-synthetic G1 stage.     

Cycles of juvenile hormone esterase activity during the juvenile hormone-driven cycles of oxygen consumption in pupal diapause of flesh flies

Summary During diapause O₂ consumption in fly pupae is a cyclic event (4-day periodicity at 25°C) driven by cycles of juvenile hormone activity. Levels of juvenile hormone esterase activity change systematically during the cycle, with highest activity observed at the nadir of the O₂ consumption cycle.Supported in part by grant 88-37153-3473 from the USDA Competitive Grants Office and grant 23-088 from the USDA Forest Service. Thanks to Dr Ming Tu Chang for her helpful advice.     

Acetylcholinesterase in intestinal cell differentiation involves G2/M cell cycle arrest

Here we examine differentiation of the intestinal cell line Caco-2 following exposure to sodium butyrate (NaBT), using alkaline phosphatase (ALP) activity and carcinoembryonic antigen (CEA) levels as markers of differentiation. We show that acetylcholinesterase (AChE) activity and RNA levels increase during differentiation. Treatment with AChE inhibitors or knockdown of AChE levels by shRNA markedly decrease ALP and CEA levels in a concentration- and time-dependent manner. Finally, our observations suggest that NaBT-induced differentiation of intestinal cells involves AChE-induced cell cycle arrest.     

The effect of head heating on the flight activity of the cockroach

Summary Internal head heating restricted the flight activity in the cockroachPeriplaneta americana. Heating the metathoracic ganglion did not have any pronounced effect on the flight. It is concluded that in the cockroach the head nervous centers are very heat-susceptible and might be the coordinating center for temperature responses.     

Agglutinins from aquatic insects—tumor cell agglutination activity

Agglutinins were identified in whole body extracts of aquatic insects by means of murine tumor cell agglutination, using sarcoma 180 ascites, Ehrlich, and MM-46 cells. Screening revealed agglutinins in 5 of 10 of the larvae tested, and in 2 of 6 of the water-dwelling adult insects;Gerris paludum insularis andGyrinus japonicus. Only the agglutinin from adultG. paludum also agglutinated human erythrocytes. An ascites tumor was converted into a solid form in vivo after administration ofG. paludum agglutinin. The observation that these aquatic insect agglutinins preferentially agglutinate tumor cells has considerable implications in terms of anti-tumor effects such as inhibition of cell proliferation and metastasis.Deceased.     

‘Waldsterben’, part IV (continuing series)

Summary Peroxidase and superoxide dismutase activities, and ascorbic acid content, were measured in both intercellular fluid and cell material of current and 1-year-old needles of Norway spruce saplings treated with ozone, ambient air and activated carbon-filtered air in outdoor fumigation chambers. Ethylene evolution was also compared. Plants from carbon-filtered air treatments had significantly lower enzyme activities and higher ascorbic acid content. These changes were more marked in intercellular fluid than in cell material. Significant changes were noted at ozone levels typical of ambient air quality in a typical urban area. These results suggest the need for simultaneous screening of several biochemical markers as a way of overcoming the lack of specificity of any single marker for the identification of a perturbation by a particular stress, such as ozone.Acknowledgments. This work was supported in part by Grant Number 4849-0.85 (NFP 14) from the Swiss National Fund of Scientific Research. We thank Dr. F. Cupelin and Dr. J. Cl. Landry from the Service d'Ecotoxicologie, Genève, who provided the facilities for the monitoring of ozone levels. We also thank A. Mesrobian, A. Rossier and D. Voluntaru for technical assistance. Du Pont de Nemours International is gratefully acknowledged for the gift of TEDLAR (polyvinyl fluoride film) to build up the fumigation chambers.     

Cell cycle changes after denervation of the newt limb regenerate,studied in vitro

Summary The proliferation of the mesenchyme of medium bud stage blastemas ofPleurodeles, measured by³H-thymidine incorporation and mitotic index, decreases about 40–50% under denervated conditions when cultivated in vitro for 4 days; epidermis is not affected in this case. Autoradiography of blastemas after³H-thymidine long term labeling shows that 3/4 of the mesenchymal cells and 1/4 of the epidermal cells are cycling when the blastema is innervated; there is no significant change of these percentages when the blastema is denervated. The results show, contrary to in vivo experiments, that denervation does not provoke an exiting from the cell-cycle but only lengthening of the cycle of the mesenchymal cells (probably of the G₁ phase).