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31.
32.
Jens M. Olesen Yoko L. Dupont Bodil K. Ehlers Alfredo Valido Dennis M. Hansen 《Nordic Journal of Botany》2003,23(5):537-539
Jasminum odoratissimum is a Madeira and Canary Islands endemic showing classic heterostyly, i.e. with long-styled flowers with anthers at a low level in the corolla tube and short-styled flowers with anthers at a high level in the corolla tube. Short-styled flowers have large pollen, whereas long-styled flowers have small pollen. The two types are present in equal frequencies in the population. 相似文献
33.
Cullen-McEwen LA Armitage JA Nyengaard JR Moritz KM Bertram JF 《American journal of physiology. Renal physiology》2011,300(6):F1448-F1453
Low glomerular (nephron) endowment has been associated with an increased risk of cardiovascular and renal disease in adulthood. Nephron endowment in humans is determined by 36 wk of gestation, while in rats and mice nephrogenesis ends several days after birth. Specific genes and environmental perturbations have been shown to regulate nephron endowment. Until now, design-based method for estimating nephron number in developing kidneys was unavailable. This was due in part to the difficulty associated with unambiguously identifying developing glomeruli in histological sections. Here, we describe a method that uses lectin histochemistry to identify developing glomeruli and the physical disector/fractionator principle to provide unbiased estimates of total glomerular number (N(glom)). We have characterized N(glom) throughout development in kidneys from 76 rats and model this development with a 5-parameter logistic equation to predict N(glom) from embryonic day 17.25 to adulthood (r(2) = 0.98). This approach represents the first design-based method with which to estimate N(glom) in the developing kidney. 相似文献
34.
Stefan U. Weber Andreas Koch Jens Kankeleit Jens-Christian Schewe Ullrich Siekmann Frank Stüber Andreas Hoeft Stefan Schröder 《Apoptosis : an international journal on programmed cell death》2009,14(1):97-107
During therapeutic hyperbaric oxygenation lymphocytes are exposed to high partial pressures of oxygen. This study aimed to
analyze the mechanism of apoptosis induction by hyperbaric oxygen. For intervals of 0.5–4 h Jurkat-T-cells were exposed to
ambient air or oxygen atmospheres at 1–3 absolute atmospheres. Apoptosis was analyzed by phosphatidylserine externalization,
caspase-3 activation and DNA-fragmentation using flow cytometry. Apoptosis was already induced after 30 min of hyperbaric
oxygenation (HBO, P < 0.05). The death receptor Fas was downregulated. Inhibition of caspase-9 but not caspase-8 blocked apoptosis induction
by HBO. Hyperbaric oxygen caused a loss of mitochondrial membrane potential and caspase-9 induction. The mitochondrial pro-survival
protein Bcl-2 was upregulated, and antagonizing Bcl-2 function potentiated apoptosis induction by HBO. In conclusion, a single
exposure to hyperbaric oxygenation induces lymphocyte apoptosis by a mitochondrial and not a Fas-related mechanism. Regulation
of Fas and Bcl-2 may be regarded as protective measures of the cell in response to hyperbaric oxygen. 相似文献
35.
Christina Krabbe† Elise Courtois‡ Pia Jensen Jesper R. Jørgensen† Jens Zimmer Alberto Martínez-Serrano‡ Morten Meyer 《Journal of neurochemistry》2009,110(6):1908-1920
Neural stem cells constitute a promising source of cells for transplantation in Parkinson's disease, but a protocol for controlled dopaminergic differentiation is not yet available. Here we investigated the effect of the anti-apoptotic protein Bcl-xL and oxygen tension on dopaminergic differentiation and survival of a human ventral mesencephalic stem cell line (hVM1). hVM1 cells and a Bcl-xL over-expressing subline (hVMbcl-xL ) were differentiated by sequential treatment with fibroblast growth factor-8, forskolin, sonic hedgehog, and glial cell line-derived neurotrophic factor. After 10 days at 20% oxygen, hVMbcl-xL cultures contained proportionally more tyrosine hydroxylase(TH)-positive cells than hVM1 control cultures. This difference was significantly potentiated from 11 ± 0.8% to 17.2 ± 0.2% of total cells when the oxygen tension was lowered to 3%. Immunocytochemistry and Q-PCR-analysis revealed expression of several dopaminergic markers besides of TH just as dopamine was detected in the culture medium by HPLC analysis. Although Bcl-xL -over-expression reduced cell death in the cultures, it did not alter the relative content of GABAergic, neurons, while the content of astroglial cells was reduced in hVMbcl-xL cell cultures compared with control. We conclude that Bcl-xL and lowered oxygen tension act in concert to enhance dopaminergic differentiation and survival of human neural stem cells. 相似文献
36.
Recent studies point to a significant role of vasodilator‐stimulated phosphoprotein (VASP) in the maintenance of endothelial barrier functions in vivo and in vitro. Moreover, it has been reported that VASP is required for activation of the small GTPase Rac 1. However, little is known whether VASP is involved in the regulation of cell adhesion molecules that are critical for maintenance of the endothelial barrier. Here we demonstrate that impaired barrier properties in VASP‐deficient (VASP?/?) microvascular myocardial endothelial cells (MyEnd) correlated with both impaired integrin‐mediated adhesion as revealed by laser tweezer trapping and reduced integrin‐dependent cell migration. This was paralleled by reduction of focal adhesions at the cell periphery as well as of β1‐integrin and VE‐cadherin cytoskeletal anchorage. Incubation of MyEnd VASP wt with RGD peptide to block interaction of integrins with extracellular matrix (ECM) reduced barrier properties and Rac 1 activity in wt endothelial monolayers mimicking the situation in VASP (?/?) cells under resting conditions. Moreover, cAMP‐mediated Rac 1 activation was reduced under conditions of impaired integrin‐mediated adhesion in wt cells and cAMP‐induced increase in VE‐cadherin cytoskeletal anchorage was abolished in VASP (?/?) endothelium. In summary, these data indicate that VASP is required for integrin‐mediated adhesion which stabilizes endothelial barrier properties at least in part by facilitating Rac 1 activation. J. Cell. Physiol. 220: 357–366, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
37.
Hansen JB Westergaard M Thrue CA Giwercman B Oerum H 《Nucleosides, nucleotides & nucleic acids》2003,22(5-8):1607-1609
Full-length and 4 nucleotides truncated Locked Nucleic Acid (LNA) modifications of ISIS 3521 were compared for antisense properties in a cellular assay. ISIS 3521 is a 20-mer phosphorothioate designed to hybridise to human protein kinase C-alpha (PKC-alpha) mRNA and is currently submitted to clinical trials against cancer. We report that LNA can potentate this antisense oligo and retain the antisense potential with shorter oligos. 相似文献
38.
39.
Freshwater mussels of the order Unionoida have life cycles that include larval attachment to and later metamorphosis on suitable host fishes. Information on the trophic relationship between unionoid larvae and their host fishes is scarce. We investigated the trophic interaction between fish hosts and encysted larvae of two species of freshwater mussels, Margaritifera margaritifera and Unio crassus, using stable isotope analyses of larvae and juvenile mussels as well as of host fish gill and muscle tissues before and after infestation. Due to different life histories and durations of host‐encystment, mass and size increase in M. margaritifera during the host‐dependent phase were greater than those of U. crassus. δ13C and δ15N signatures of juvenile mussels approached isotopic signatures of fish tissues, indicating a parasitic relationship between mussels and their hosts. Shifts were more pronounced for M. margaritifera, which had a five‐fold longer host‐dependent phase than U. crassus. The results of this study suggest that stable isotope analyses are a valuable tool for characterizing trophic relationships and life history strategies in host–parasite systems. In the case of unionoid mussels, stable isotopic shifts of the larvae are indicative of the nutritional versus phoretic importance of the host. 相似文献
40.
Jens A. Hammerl Claudia J?ckel Thomas Alter Pawel Janzcyk Kerstin Stingl Marie Theres Knüver Stefan Hertwig 《PloS one》2014,9(12)