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Summary The regeneration of plants of the red alga Griffithsia pacifica from single, isolated cells is described. Regeneration can start from any cell and is triggered by the removal of an abutting cell. An isolated, single shoot cell forms a shoot and a rhizoidal cell within one day. The shoot then adds new cells by apical division at the rate of 1–2 cells/day; branches are formed at predictable but not fixed locations by budding of subapical cells. Each shoot cell enlarges for 6–8 days. The resulting plant consists of uniseriate, pseudodichotomously-branched shoot filaments with multicellular rhizoidal filaments at their base. The predictability and rapidity of this development combined with the large size of these cells (1.0×0.2 mm) facilitate developmental studies on this organism. 相似文献
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Calcium crosslinks are load-bearing bonds in soybean (Glycine max (L.) Merr.) hypocotyl cell walls, but they are not the same load-bearing bonds that are broken during acid-mediated cell
elongation. This conclusion is reached by studying the relationship between wall calcium, pH and the facilitated creep of
frozenthawed soybean hypocotyl sections. Supporting data include the following observations: 1) 2-[(2-bis-[carboxy-methyl]amino-5-methylphenoxy)methyl]-6-methoxy-8-bis[carboxymethyl]aminoquinoline
(Quin 2) and ethylene glycol-bis(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) caused only limited facilitated creep
as compared with acid, despite removal of comparable or larger amounts of wall calcium; 2) the pH-response curves for calcium
removal and acid-facilitated creep were different; 3) reversible acid-extension occurred even after removal of almost all
wall calcium with Quin 2; and 4) growth of abraded sections did not involve a proportional loss of wall calcium. Removal of
wall calcium, however, increased the capacity of the walls to undergo acid-facilitated creep. These data indicate that breakage
of calcium crosslinks is not a major mechanism of cell-wall loosening in soybean hypocotyl tissues.
This research was supported by Department of Energy grant DE-FG06-88ER13830 and NASA grant NAGW 1394. The authors are grateful
to Dr. David Rayle (San Diego State University, Cal.) for stimulating discussions and comments during the course of this work. 相似文献
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M J James L G Cleland R A Gibson J S Hawkes 《Prostaglandins, leukotrienes, and essential fatty acids》1991,44(2):123-126
While both animal and human studies have shown that fish oil can exert antiinflammatory actions, the effects are modest and require large doses. The effects may be amplified by modifying the intake of other dietary fats and by making use of favourable interactions between fish oil and drugs. 相似文献