Lyso-phosphatidylcholine is a signal in the arbuscular mycorrhizal symbiosis

The arbuscular mycorrhizal (AM) symbiosis represents the most widely distributed mutualistic root symbiosis. We report that root extracts of mycorrhizal plants contain a lipophilic signal capable of inducing the phosphate transporter genes StPT3 and StPT4 of potato (Solanum tuberosum L.), genes that are specifically induced in roots colonized by AM fungi. The same signal caused rapid extracellular alkalinization in suspension-cultured tomato (Solanum lycopersicum L.) cells and induction of the mycorrhiza-specific phosphate transporter gene LePT4 in these cells. The active principle was characterized as the lysolipid lyso-phosphatidylcholine (LPC) via a combination of gene expression studies, alkalinization assays in cell cultures, and chromatographic and mass spectrometric analyses. Our results highlight the importance of lysophospholipids as signals in plants and in particular in the AM symbiosis.     

EVALUATION OF SOLID PHASE RADIOLABELS OF DOG FOOD FOR GASTRIC EMPTYING

99mTc-Pertechnetate, 99mTc-mebrofenin, 99mTc-disofenin, 99mTc-sulfur colloid, and 99mTc-Dowex resin beads were evaluated for in vitro stability as a label for both dry extruded, and canned dog food for gastric emptying scintigraphy. A sample of each radiolabeled diet was added to water, gastric juice, intestinal juice, or gastric juice followed by intestinal juice for in vitro digestion. After a 3-hour digestion period, tubes were centrifuged and percentage solid phase retention (%SPR) was calculated. The experiment was repeated three times over a 14-day period to minimize day-to-day variation. For dry dog food, 99mTc-mebrofenin and 99mTc-disofenin had similar %SPR in water (96 and 93%, respectively) and gastric juice (>95% each) and were significantly higher than other labels. For canned dog food, mebrofenin had a 91% SPR for the water or gastric juice digestions, and 99mTc-Dowex had a %SPR of >99%. 99mTc-mebrofenin and 99mTc-Dowex were also tested in vivo, where 99mTc-Dowex had poor stability, and 99mTc-Mebrofenin had excellent stability. 99mTc-Mebrofenin is a suitable label for dog food for gastric emptying scintigraphy.     

Der Einfluß verschiedener Bodenbearbeitungsmethoden auf den Wasserhaushalt und die Nährstoffverhältnisse in Boden und Pflanze

The response of 25 strains of Ethiopian mustard (Brassica carinata) to drought stress was assessed in a pot experiment under glasshouse conditions. Four‐ week old plants of all the lines were subjected to 0 or 2 cycles of drought (twice wilting and rewatering). The drought stress caused a significant reduction in shoot fresh and dry masses in all lines. However, five strains, C90–1191, C90–1203, C90–1210, 77–1271 and P48–3 were superior to the remaining lines in production of shoot fresh and dry masses under drought conditions. Only two lines, C90 ‐1205 and 4007‐A, were categorized as moderately resistant on the basis of their performance in the two growth variables. The remaining all lines were placed under the drought sensitive category. Osmotic adjustment and water retention capability did not prove to be successful selection criteria for discriminating strains since drought resistant, moderately drought‐resistant or drought sensitive lines had almost similar values of osmotic adjustment or water retention capability.

The great amount of intna‐specific variation for drought resistance in this set of germplasm of B. carinata is of considerable value for the improvement of drought resistance in this crop through selection and breeding.