Export, Mobilization, and Respiration of Assimilates in Uniculm Barley during Light and Darkness

The respiratory losses and the pattern of carbon supply froma leaf of unicuim barley were examined during a complete diurnalperiod using a steady state ¹⁴C-labelling technique. After a delay of c. 1 h a portion of the ¹⁴C exported from acontinuously assimilating leaf was lost in respiration in thelight. This respiratory loss amounted to c. 20% of the total¹⁴C fixed. A further 28% of the total ¹⁴C fixed was respiredduring the dark period. In the light, carbon was fixed at a rate of c. 8·9 mgC dm^{–2 h–1} and exported from the leaf at ^c. 5·3mg C dm^{–2 h–1}. Dark export averaged ^c. 31% of theday-time rate. Carbohydrate was stored in the leaf during the day and was almostcompletely remobilized during the dark. Sucrose, the major reservecarbohydrate, was exported first whilst the starch level remainedconstant. After some 9 h of darkness, sucrose declined to alow level and starch remobilization began.     

Irrigation and Community in the Central Peruvian Highlands

Irrigation in Quinua is an adaptation of high altitude agriculture, and its regulation and celebration are significant aspects of the political and ritual life of the community. Comparative data suggest that similar relationships are widespread in Peru. The information from Quinua is used to illuminate the water needs of Huari, an important archaeological site located in the community. The significance of the data for the hydraulic hypothesis of Wittfogel and Steward is discussed.     

Protein Synthesis and Differentiation During Pulmonate Development

An analysis of the changing patterns of protein synthesis duringearly development of Lymnaea palustris has been undertaken.An examination of the ingestion of capsule fluid protein suggeststhat after gastrulation 30 to 65% of the total embryo proteinis undigested food protein. Starch gel electrophoresis revealsa sudden increase in the number of hydrolases from four to twenty-siximmediately following the trochophore stage with the latterbeing present also in adult organs. Studies reported here andelsewhere demonstrate rhythmic changes in uridine incorporationduring early cleavage which peaks at the trochophore stage.Continuous treatment of embryos with 50 to 100µ.g of actinomycin-D(AMD) starting at the 2-cell stage slowed development throughthe trochophore stage but did not prevent normal larval organdevelopment. This AMD application reduced ³H uridine incorporationmore than 90% but did not appreciably alter the pattern of totalor ¹⁴C leucine pulse labeled peptides on sodium dodecyl sulfate(SDS) ultrathin slab electrophoresis gels. However, pronouncedand numerous changes in the patterns of both labeled and unlabeledpeptides were observed during development through 4 days withthe most notable alterations occurring at the 2.5 post-gastrulastage. This was true in normal and continuously treated AMDembryos. The morphological and biochemical data suggest Lymnaeaearly development is controlled by stable maternal messengerRNA.