Photoinduced affinity labeling of the Escherichia coli ribosome puromycin site.

The photoincorporation of puromycin into Escherichia coli ribosomes has been studied in detail. Incorporation into protein L23 as a function of puromycin concentration follows a simple saturation curve and is specifically blocked by structural and functional analogues of puromycin, thus demonstrating that such incorporation proceeds via an affinity labeling process. Incorporation into L23 becomes more specific as the light fluence is reduced, indicating that such incorporation takes place from a native rather than light-denatured puromycin site. L23 remains the major labeled protein using ribosomes prepared by several procedures, suggesting the conservative nature of the site. In addition evidence is presented for affinity labeling of S14 and of a site in the RNA fraction of the 50S particle. Specific incorporation appears to proceed with an anomalously high quantum yield. The detailed photochemical mechanism is not understood, although 8-alkylation of purine moiety has been excluded. Incorporation is largely inhibited in the presence of thiol reagents.     

Chinese chestnut production in the United States: Practice,problems, and possible solutions

There are fewer than 162 ha of commercial Chinese chestnut orchards in the United States, with approximately half of these in the Southeast. Large numbers of Chinese chestnut seedlings are planted annually in the United States for home and game food production; however, knowledge about chestnut propagation, fertilization, pests, harvest, storage and marketing is not adequate. There is little commercial marketing of U.S.-grown Chinese chestnuts through roadside markets and local farmers’ markets as the supply is low and unpredictable. However, we yearly import 4.5 mill kg of European chestnuts to satisfy the U.S. market. Successful chestnut orchards will require vegetatively propagated selections, intensive management, mechanical harvesting, and control of insect and disease pests.     

Hemolytic properties of lytic peptides active against the sporozoites of Cryptosporidium parvum.

Cryptosporidium parvum is a protozoan parasite that causes mildto-severe diarrheal disease in animals and humans. There are currently no effective chemotherapeutic agents available for the treatment of cryptosporidiosis. Recently, small, naturally occurring antimicrobial lytic peptides with anti-protozoal activities have been described. In the present study, we compare the in vitro anti-cryptosporidial activities of synthetic lytic peptides and their corresponding hemolytic activities after a 30 min incubation at 37 degrees C. Sporozoite viability was assessed microscopically by the uptake of the vital dyes fluorescein diacetate (FDA) and propidium iodide (PI). Hemolysis was assessed spectrophotometrically by the release of soluble hemoglobulin. The most active peptide, Hecate-1, reduced sporozoite viability by 85.5% with a corresponding hemolytic activity of 21.5% at a concentration of 10 microM.