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931.
Roland Bilang Shibo Zhang Nathalie Leduc Victor A. Iglesias reas Gisel John Simmonds Ingo Potrykus Christof Sautter 《The Plant journal : for cell and molecular biology》1993,4(4):735-744
A method has been established that allows the targeted delivery of DNA-carrying gold particles to vegetative shoot apical meristems of cereal species. Meristems of 8- to 10-day-old seedlings of wheat ( Triticum aestivum ), rice ( Oryza sativa ) and sorghum ( Sorghum bicolor ) were manually exposed by removal of the coleoptile and the first three to four leaves. Using ballistic microtargeting, equal-sized gold particles of different diameters ranging from 1.0 to 2.0 µm were propelled to meristems by pulses of compressed nitrogen ranging from 9 to 13 MPa. When accelerated by 13 MPa, particles of 1.4 µm or larger penetrated to cells of L2 in 80% of the bombarded wheat meristems. Expression vectors containing either the gene for β-glucuronidase ( gusA ) or genes regulating the anthocyanin biosynthesis ( Bperu and C1 from maize) were delivered to wheat meristems. The level of transient gene expression was dependent on the osmotic pressure of the MS-based medium that was used to mount the explants for shooting: an increase of the sucrose concentration from 2 to 10% in the medium resulted in an increase of transient gene expression from 5 to 25% of the bombarded meristems. Although particles of 1.4 µm were efficiently delivered to L1 and L2, transient gene expression occurred predominantly in the L1 layer. In contrast, up to 10% of the bombarded meristems had expressing cells in L2 when particles of 2.0 µm were used. Ten days after bombardment, GUS-positive sectors in meristems and in leaf primordia were observed. When destructive GUS detection was omitted, between 80 and 90% of the bombarded ex-plants recovered in vitro on basal MS medium and then regenerated to fertile plants in the greenhouse. 相似文献
932.
N Fellmann A Labbe A M Gachon J Coudert 《European journal of applied physiology and occupational physiology》1985,54(5):511-516
We attempt to determine whether the decrease in Na+ reabsorption and the increase in K+ secretion in sweat of cystic fibrosis patients (CF) were associated with changes in glandular anaerobic metabolism evaluated by forehead sweat lactate excretion rate. 6 CF and 11 normal (C) children, 5 months to 14 years old, were exposed to external thermal load (45 degrees C). The data showed that: 1) Na+, K+ and Cl- concentrations in CF are constant at any flow rate (Qsw); 2) In both groups the excretion rates of Na+, K+ and Cl- increased linearly with Qsw but the slopes in CF were significantly higher than in C (p less than 0.001); 3) Lactate excretion rate increased with Qsw as in CF and C with the same slope. We suggest that an increase in energy expenditure of Na+ - K+ exchange and an active secretion of K+ by the duct could explain the normal energy metabolism that we observed in CF sweat glands. 相似文献
933.
P F Devaux A Zachowski E Favre P Fellmann S Cribier D Geldwerth P Hervé M Seigneuret 《Biochimie》1986,68(3):383-393
In this review, we show how the stability of the asymmetric transverse distribution of phospholipids and the physiological role of the asymmetric distribution can be explained. Experiments with paramagnetic or fluorescent lipids enabled us to show that in fresh red blood cells, i.e. containing ATP, and in resealed ghosts containing ATP (1 mM) the amino derivatives (phosphatidylserine and phosphatidylethanolamine) are selectively transported from the outer monolayer to the inner monolayer of the membranes. On the other hand, phosphatidylcholine and sphingomyelin are not carried and diffuse spontaneously with a very long characteristic time. The ATP-dependent carrier mechanism can be inhibited by protein reacting groups (N-ethyl maleimide and ortho-vanadate), which very probably implies a transmembrane protein specific for amino phospholipids. The affinity for phosphatidylserine seems slightly higher than that for phosphatidylethanolamine. In addition we show the close parallel between the transverse distribution of phospholipids and cell shape. This leads us to suggest that the phospholipid translocation would be used to maintain the natural discoid shape of red blood cells. A possible generalisation of this mechanism to other cells and its implications for endocytosis are discussed. 相似文献
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937.
J Verstegen D Fellmann J F Beckers 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1985,301(2):41-46
The immunocytochemical study of the bovine placenta has demonstrated the presence of cells containing alphamelanotropic hormones, in the decidual epithelium, since the 4th month of pregnancy. The number and the staining intensity of those cells grow up with the placental development. Since the 6th month, we observed the immunoreactional presence of cells in the foetal chorionic epithelium. 相似文献
938.
Andrea Weghofer Katharina Klein Maria Stammler-Safar Christof Worda David H Barad Peter Husslein Norbert Gleicher 《Reproductive biology and endocrinology : RB&E》2010,8(1):57
Background
Impact of fetal gender on prematurity has been primarily investigated in singleton pregnancies. In an attempt to understand better how fetal gender may affect gestational length in twin gestations after in vitro fertilization, same-sex twins and opposite twins were compared for pregnancy duration. 相似文献939.
J L Bresson M C Clavequin D Fellmann C Bugnon 《Comptes rendus des séances de la Société de biologie et de ses filiales》1983,177(4):455-463
An hypothalamo-infundibular neuroglandular system stained by an anti-hpGRF 44 serum is described in human brain. Perikarya are located in the infundibular nucleus, and their fibres end in posterior and lateral territories of the zona externa of the Median Eminence . Somatostatin fibres, morphologically different, also end in the same areas. Fibres giving intra- eminential terminals, so as hypothalamic perikarya are revealed as early as the 18 th week of fetal life. 相似文献
940.