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Heat treatment results in a loss of transgene-encoded activities in several tobacco lines. 总被引:1,自引:0,他引:1 下载免费PDF全文
Heat treatment (37 degrees C) of transgenic tobacco (Nicotiana tabacum) plants led to a reversible reduction or complete loss of transgene-encoded activities in about 40% of 10 independent transformants carrying the luciferase-coding region fused to the 355 cauliflower mosaic virus or the soybean small subunit promoter and the nopaline synthase promoter driving the neomycin phosphotransferase gene, whereas the other lines had temperature-tolerant activities. Temperature sensitivity or tolerance of transgene-encoded activities was heritable. In some of the lines, temperature sensitivity of the transgene-encoded activities depended on the stage of development, occurring in either seedlings (40% luciferase and 50% neomycin phosphotransferase) or adult plants (both 40%). The phenomenon did not correlate with copy numbers or the homo- or hemizygous state of the transgenes. In lines harboring a temperature-sensitive luciferase activity, reduction of bioluminescence was observed after 2 to 3 h at 37 degrees C. Activity was regained after 2 h of subsequent cultivation at 25 degrees C. Irrespective of the reaction to the heat treatment, the level of luciferase RNA was slightly increased at 37 degrees C. Only in lines showing temperature sensitivity of transgene-encoded activities was the amount of luciferase and neomycin phosphotransferase strongly reduced. In sterile culture, heat treatment for 15 d did not cause visible damage or changes in plant morphology. In all plants tested a slight induction of the heat-shock response was observed at 37 degrees C. 相似文献
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Eberhard Gischler 《Facies》2010,56(2):173-177
Shallow fore-reef areas worldwide are usually characterized by spurs and grooves. A comparison of examples from the three
world oceans suggests that Indo-Pacific spurs and grooves are shaped predominantly by erosion, whereas western Atlantic spur
and groove systems are largely a product of constructive processes. I propose that this difference is caused by regional differences
in Holocene sea-level change, which controlled exposure to waves and currents, and reef-accretion rates. The transgressive–regressive
sea-level curve in the Indo-Pacific realm, i.e., the Mid-to-Late Holocene sea-level fall in these areas has maintained high-energy
conditions in the shallow fore reef. Higher exposure to waves and currents favors erosion and leads to a dominance of crustose
coralline algae that have relatively slow growth rates. In the western Atlantic, the transgressive Holocene sea level has
caused Mid-to-Late Holocene deepening and has maintained accommodation space for reef accretion. Fast-growing acroporid corals
thrive under lower exposure and are more common than coralline algae. The fossil record of the spur and groove system is rather
poor, which is probably a consequence of the need of excellent, three-dimensional outcrops for identification. 相似文献
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The enlarged inhalant siphon of Fungiacava eilatensis opens into the coelenteron of species of fungiid corals with which it lives in commensal association. Material consisting of mucus, zooxanthellae, nematocysts, plankton and inorganic matter, is taken exclusively from the coelenteron. The very mobile foot possibly assists in food collection and in the removal of pseudofaeces; but, with large ctenidia, the bivalve is a typical ciliary feeder. Experiments with labelled zooxanthellae reveal that these are taken into the gut of Fungiacava with subsequent metabolic incorporation of products derived from them. The other prime source of food must be phytoplankton carried in with the feeding currents of the coral, itself carnivorous so that there is no competition for food between commensal and host. The Fungia zooxanthella– Fungiacava association operates as a "Troika" the productivity of which is autoregulated in proportion to the number of bivalves present. The inorganic wastes of the bivalve (as well as those of the coral) are utilized by the zooxanthellae, resultant increase in the algal component becoming available as food to the bivalve. Losses in the cycle are balanced by intake of exogenous food. 相似文献
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A Safran R Sagi-Eisenberg D Neumann S Fuchs 《The Journal of biological chemistry》1987,262(22):10506-10510
Purified acetylcholine receptor is rapidly and specifically phosphorylated by partially purified protein kinase C, the Ca2+/phospholipid-dependent enzyme. The receptor delta subunit is the major target for phosphorylation and is phosphorylated on serine residues to a final stoichiometry of 0.4 mol of phosphate/mol of subunit. Phosphorylation is dose-dependent with a Km value of 0.2 microM. Proteolytic digestion of the delta subunit phosphorylated by either protein kinase C or the cAMP-dependent protein kinase yielded a similar pattern of phosphorylated fragments. The amino acids phosphorylated by either kinase co-localized within a 15-kDa proteolytic fragment of the delta subunit. This fragment was visualized by immunoblotting with antibodies against a synthetic peptide corresponding to residues 354-367 of the receptor delta subunit. This sequence, which contains 3 consecutive serine residues, was recently shown to include the cAMP-dependent protein kinase phosphorylation site (Souroujon, M. C., Neumann, D., Pizzighella, S., Fridkin, M., and Fuchs, S. (1986) EMBO J. 5, 543-546). Concomitantly, the synthetic peptide 354-367 was specifically phosphorylated in a Ca2+- and phospholipid-dependent manner by protein kinase C. Furthermore, antibodies directed against this peptide inhibited phosphorylation of the intact receptor by protein kinase C. We thus conclude that both the cAMP-dependent protein kinase and protein kinase C phosphorylation sites reside in very close proximity within the 3 adjacent serine residues at positions 360, 361, and 362 of the delta subunit of the acetylcholine receptor. 相似文献