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341.
Cyril Goudet AnneAliénor Véry MarieLouise Milat Michèle Ildefonse JeanBaptiste Thibaud Hervé Sentenac JeanPierre Blein 《The Plant journal : for cell and molecular biology》1998,14(3):359-364
Beticolins are toxins produced by the fungus Cercospora beticola. Using beticolin 0 (B0), we have produced a strong and Mg2+-dependent increase in the membrane conductance of Arabidopsis protoplasts and Xenopus oocytes. In protein-free artificial bilayers, discrete deflexions of current were observed (12 pS unitary conductance in symmetrical 100 mM KCl) in the presence of B0 (approximately 10 μM) and in the presence of nominal Mg2+. Addition of 50 μM Mg2+ induced a macroscopic current which could be reversed to single channel current by chelating Mg2+ with EDTA. Both unitary and macroscopic currents were ohmic. The increase in conductance of biological membranes triggered by B0 is therefore likely to originate from the ability of this toxin to organize itself into transmembrane pores in the presence of Mg2+. The pore is poorly selective, displaying permeability ratios PCl/PK, PNa/PK and PCa/PK close to 0.3, 0.65 and 0.4, respectively. Such channel-like activity could be involved in the deleterious biological activity of the toxin, by causing the collapse of ionic and electrical gradients through biological membranes together with Ca2+ influx and scrambling of cellular signals. 相似文献
342.
Daniel C Hatton Qi Yue Justin Chapman Hong Xue Jacqueline Dierickx Chantal Roullet Sarah Coste Jean Baptiste Roullet David A McCarron 《Journal of applied physiology》2002,92(1):13-17
Ground studies indicate that spaceflight may diminish vascular contraction. To examine that possibility, vascular function was measured in spontaneously hypertensive rats immediately after an 18-day shuttle flight. Isolated mesenteric resistance arterial responses to cumulative additions of norepinephrine, acetylcholine, and sodium nitroprusside were measured using wire myography within 17 h of landing. After flight, maximal contraction to norepinephrine was attenuated (P < 0.001) as was relaxation to acetylcholine (P < 0.001) and sodium nitroprusside (P < 0.05). At high concentrations, acetylcholine caused vascular contraction in vessels from flight animals but not in vessels from vivarium control animals (P < 0.05). The results are consistent with data from ground studies and indicate that spaceflight causes both endothelial-dependent and endothelial-independent alterations in vascular function. The resulting decrement in vascular function may contribute to orthostatic intolerance after spaceflight. 相似文献
343.
Two endocrinologically active octapeptide analogues (BIM-23014 C and BIM-23034) of somatostatin (SRIF) containing either an N- or C-terminal 3-(2-naphthyl)-D-Ala residue were examined for their ability to inhibit the in vitro receptor binding, clonal growth, and vasoactive intestinal peptide (VIP)-stimulated cyclic AMP formation in human small cell lung cancer cell (SCLC) line NCI-H345. Both SRIF peptides inhibited [125I]SRIF(Tyr11)-14 binding with IC50 values in the low nM range. Colony formation in the in vitro SCLC growth assay was also inhibited in the same concentration range, as was VIP-stimulated cyclic AMP formation. Therefore, octapeptide analogues of SRIF function as SCLC SRIF receptor agonists. 相似文献
344.
Jacqueline Gunther Baptiste Jayet Adam Jacobs Ray Burke Jana M. Kainerstorfer Stefan Andersson-Engels 《Journal of biophotonics》2021,14(9):e202000486
About a third of babies are delivered by Cesarean section. There has been an increase in maternal deaths during labor due to complications with subsequent births after a C-section. Therefore, there is a clinical motivation to reduce the C-section rate. Current techniques are, however, inefficient at determining fetal distress leading to a high false positive rate for complications and ultimately a C-section. For the current study, Monte Carlo simulations were used to calculate the amount of signal received on a model of a pregnant mother, as well as, the percent of the signal that comes from the fetal layer. Models with and without a 1 mm amniotic fluid were compared and showed differing trends. 相似文献
345.
We have investigated the release of protons from thrombin-stimulated platelets. Addition of thrombin to suspensions of washed platelets resulted in fast liberation of H+. In the presence of 0.1 mM amiloride, a potent inhibitor of the Na+/H+ transport system, the amount of protons liberated was decreased by about 50%, and was further reduced to about 15% by 1 mM amiloride. Similar inhibition of H+ release was observed after Na+ in the incubating medium had been replaced by choline. We conclude that one of the earliest events in thrombin-stimulated platelets consists of the activation of an Na+/H+ countertransport, which leads to an increase in intracellular pH. 相似文献
346.
JeanBaptiste Juhel Virginie Marques Andrea Polanco Fernndez Giomar H. BorreroPrez Maria Mutis Martinezguerra Alice Valentini Tony Dejean Stphanie Manel Nicolas Loiseau Laure Velez Rgis Hocd Tom B. Letessier Eilísh Richards Florine Hadjadj Sandra Bessudo Felipe Ladino Camille Albouy David Mouillot Loïc Pellissier 《Ecology and evolution》2021,11(7):2956
- Monitoring large marine mammals is challenging due to their low abundances in general, an ability to move over large distances and wide geographical range sizes.
- The distribution of the pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales is informed by relatively rare sightings, which does not permit accurate estimates of their distribution ranges. Hence, their conservation status has long remained Data Deficient (DD) in the Red list of the International Union for Conservation of Nature (IUCN), which prevent appropriate conservation measures.
- Environmental DNA (eDNA) metabarcoding uses DNA traces left by organisms in their environments to detect the presence of targeted taxon, and is here proved to be useful to increase our knowledge on the distribution of rare but emblematic megafauna.
- Retrieving eDNA from filtered surface water provides the first detection of the Dwarf sperm whale (Kogia sima) around the remote Malpelo island (Colombia).
- Environmental DNA collected during oceanic missions can generate better knowledge on rare but emblematic animals even in regions that are generally well sampled for other taxa.
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