Assisting developing countries toward food self-reliance

Per capita food availability in the developing world has increased by 20% since the early 1960s, according to the Food and Agriculture Organization, and today the world has twice as many people but 150 million fewer hungry people than in 1960. The world agricultural system has not done too bad a job over the past 35 years. It is likely that global agricultural production will continue to at least match growth in food demand over the next decade, assuming no major weather anomalies. Continued support of the Consultative Group for International Agricultural Research and programs involving U.S. universities is important to sharing knowledge about agriculture with colleagues in the developing world. This paper explores the reasons for providing agricultural development assistance, the benefits to the United States that come from doing so, and the special challenges facing the world over the next few decades.

Purification and Characterization of a Low-Molecular-Weight Phospholipase A2 from Developing Seeds of Elm1

Phospholipase A2 (PLA2) was purified about 180,000 times compared with the starting soluble-protein extract from developing elm (Ulmus glabra) seeds. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis the purified fraction showed a single protein band with a mobility that corresponded to 15 kD, from which activity could be recovered. When analyzed by matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry, the enzyme had a deduced mass of 13,900 D. A 53-amino acid-long N-terminal sequence was determined and aligned with other sequences, giving 62% identity to the deduced amino acid sequence of some rice (Oryza sativa) expressed sequence tag clones. The purified enzyme had an alkaline pH optimum and required Ca2+ for activity. It was unusually stable with regard to heat, acidity, and organic solvents but was sensitive to disulfide bond-reducing agents. The enzyme is a true PLA2, neither hydrolyzing the sn-1 position of phosphatidylcholine nor having any activity toward lysophosphatidylcholine or diacylglycerol. The biochemical data and amino acid sequence alignments indicate that the enzyme is related to the well-characterized family of animal secretory PLA2s and, to our knowledge, is the first plant enzyme of this type to be described.