In Vitro Populations of Rotifer Brachionus plicatilis Müller Demonstrate Inhibition When Fed with Copper-Preaccumulating Microalgae

6 páginas, 2 figuras, 5 tablas.Four marine microalgal species (Chlorella autotrophyca, Nannochloropsis gaditana, Tetraiselmis chuii, and Isochrysis aff. galbana) were exposed for 24 h to 1 mg L−1 dissolved copper and then transferred to fresh medium. After that, a group of 10 neonate rotifers were fed with these four microalgal species. The levels of accumulated copper in cellular concentrations of the microalgae were checked, with the result of around 40% of original concentration, with the exception of I. aff. galbana (25% of original concentration). In all cases, cells with preaccumulated metal caused a delay of 1 or 2 days in populational development of rotifers (increase in “lag phase”). The microalgae that were not fed to rotifers (disposed in parallel series) did not significantly transfer metal to the medium after the first day.Peer reviewe

Bone marrow cell transplantation time-dependently abolishes efficacy of granulocyte colony-stimulating factor after stroke in hypertensive rats

Background and Purpose— We aimed to determine a possible synergistic effect of granulocyte colony-stimulating factor (G-CSF) and bone marrow–derived mononuclear cells (BM MNC) after stroke in spontaneously hypertensive rats. Methods— Male spontaneously hypertensive rats were subjected to middle cerebral artery occlusion and randomly assigned to daily injection of 50 μg/kg G-CSF for 5 days starting 1 hour after stroke (groups 1, 2, and 3) with additional intravenous transplantation of 1.5×10E7 BM MNC per kilogram at 6 hours (group 2) or 48 hours (group 3) after stroke, or control treatment (group 4). Circulating leukocyte counts and functional deficits, infarct volume, and brain edema were repeatedly assessed in the first week and first month. Results— G-CSF treatment led to a significant neutrophilia, to a reversal of postischemic depression of circulating leukocytes, and to a significantly improved functional recovery without affecting the infarct volume or brain edema. BM MNC cotransplantation was neutral after 6 hours, but reversed the functional effect of G-CSF after 48 hours. Short-term investigation of combined G-CSF and BM MNC treatment at 48 hours indicated splenic accumulation of granulocytes and transplanted cells, accompanied by a significant rise of granulocytes in the circulation and the ischemic brain. Conclusions— G-CSF improved functional recovery in spontaneously hypertensive rats, but this effect was abolished by cotransplantation of BM MNC after 48 hours. In the spleen, transplanted cells may hinder the clearance of granulocytes that were massively increased by G-CSF. Increased circulation and infiltration of granulocytes into the ischemic brain may be detrimental for stroke outcome

Comparative data about wild type C57Bl/6 <i>GNE</i>+/+ and heterozygous C57Bl/6 <i>GNE</i>+/− mice.

<p>±SD; range in parentheses; n.s., not significant. Data are mean</p><p><i>GNE</i>^{+/+ and} C57Bl/6 <i>GNE</i>^+/− at 24 weeks and at 80 weeks. There was no statistical difference between the parameters in C57Bl/6 </p

Treadmill exercise in the cohort of the wild type C57Bl/6 <i>GNE</i>^+/+ (black) and the C57Bl/6 <i>GNE</i>^+/− (grey)

<p>(<b>A</b>). Electron microscopic findings of 80-week old female mice: depicts subsarcolemmal nucleus and perinuclear vacuole containing abundant dense granular material (unlikely to be lipofuscin) in the wild type mouse. Adjacent to the large vacuole are round structures (arrowhead) of sarcoplasmatic tubules, which are confined by double membranes and contain dark granules and in the centre a corpuscule of medium densitiy (gastrocnemius muscle at 16.700×magnification) (<b>B</b>). The perinuclear vacuole is surrounded by a single membrane in the heterozygous mouse and displays similar features. Note the two rounded structures in the vicinity containing either membranous structures or dense, granular material (arrowhead) (quadriceps muscle at 16.700×magnification) (<b>C</b>). Quantification of sialylation from membrane bound sialic acid in in anterior tibial, gastrocnemic, and quadriceps femoral muscle in wild type C57Bl/6 <i>GNE</i>^+/+ (black bars) and the C57Bl/6 <i>GNE</i>^+/− (gray bars). Values represent means ± 1 SD of three independent experiments (<b>D</b>). Relative sialic acid concentrations in different muscles (anterior tibial, gastrocnemic and quadriceps femoral muscle). Sialic acid concentration after 180 days was set to 100% and all other values were expressed in percent of this value. Note that maximal sialic acid concentration was reached after 180 days and no further increase of sialic acid concentration was observed after that time (<b>E</b>).</p

The Key Enzyme of the Sialic Acid Metabolism Is Involved in Embryoid Body Formation and Expression of Marker Genes of Germ Layer Formation

The bi-functional enzyme UDP-N-acetyl-2-epimerase/N-acetylmannosamine kinase (GNE) is the key enzyme of the sialic acid biosynthesis. Sialic acids are negatively charged nine carbon amino sugars and are found on most glycoproteins and many glycolipids in terminal positions, where they are involved in a variety of biological important molecular interactions. Inactivation of the GNE by homologous recombination results in early embryonic lethality in mice. Here, we report that GNE-deficient embryonic stem cells express less differentiation markers compared to wild-type embryonic stem cells. As a result, GNE-deficient embryonic stem cells fail to form proper embryoid bodies (EB) within the first day of culture. However, when culturing these cells in the presence of sialic acids for three days, also GNE-deficient embryonic stem cells form normal EBs. In contrast, when culturing these cells in sialic acid reduced medium, GNE-deficient embryonic stem cells proliferate faster and form larger EBs without any change in the expression of markers of the germ layers