Green butyryl-coenzyme A dehydrogenase. An enzyme–acyl-coenzyme A complex

1. Butyryl-CoA dehydrogenase from Peptostreptococcus elsdenii forms very tightly bound complexes with various acyl-CoA compounds. Spectra in some cases merely show resolution of the 450nm band, but those with acetoacetyl-, pent-2-enoyl- and 4-methylpent-2-enoyl-CoA show long-wavelength bands similar to the 710nm band of native enzyme. These complexes are formed instantaneously by the yellow form of the enzyme and much more slowly by the green form. 2. An acid extract of the green enzyme reconverts the yellow into the green form. 3. Hydroxylamine makes irreversible the otherwise reversible conversion of the green enzyme into the yellow form by phenylmercuric acetate. 4. Amino acid analysis for taurine and beta-alanine shows approx. 1mol of CoA/mol of flavin in green enzyme. Anaerobic dialysis of reduced enzyme removes the CoA. On acid precipitation of green enzyme the CoA is found only in the supernatant. 5. It is concluded that native green enzyme is probably complexed with unsaturated acyl-CoA. This is shown to be consistent with findings of other workers. Catalytic activity requires displacement of the acyl-CoA, which is therefore likely to be a potent inhibitor. 6. An explanation is offered for the irreversible conversion of green into yellow enzyme by sodium dithionite. 7. The enzyme displays a feeble, previously undetected, activity towards beta-hydroxybutyryl-CoA. 8. The product of oxidation of pent-4-enoyl-CoA forms a complex with reduced enzyme and strongly inhibits reoxidation of the FAD. This may contribute to inhibition of fatty acid oxidation by pent-4-enoic acid in mammals.     

Predator-prey relationships in the southeastern Ozarks–A.D. 1300

Archeological findings provide the basis for analyzing the exploitation of deer by Powers Phase Indian hunters in the southeastern Ozarks circaA.D. 1300. Predatory patterns of wolves have been documented. It is hypothesized that men and wolves were complementary, noncompetitive predators and that their predation functioned to keep the deer population within the carrying capacity of the southeastern Ozarks. A model is developed to illustrate the predator-prey relationships in the area.Powers Phase Research Project is financed by National Science Foundation Grant GS-3215 to James B. Griffin, University of Michigan.The term Powers Phase has been applied to a pre-Columbian American Indian population of Middle Mississippian cultural affiliation which occupied an area in southeast Missouri for a relatively short period of timecirca A.D. 1300.     

A New Antibiotic K–52A,Produced by Streptoverticillium roseoverticillatum subsp. albosporum,Strain No. K–52

Streptoverticillium sp., strain No. K–52, isolated from a soil sample collected in Kumamoto City, was found to produce a new antibiotic, K–52A. From the results of taxonomic studies, strain No. K–52 was identified as a strain of Streptoverticillium roseoverticillatum subsp. albosporum (Thirumalachar) Locci, Baldacci and Petrolini Baldam 1969.

Antibiotic K–52A produced by this strain was thought to be a saccharide, and inhibited the growth of Gram-positive and Gram-negative bacteria, including Pseudomonas aeruginosa on a chemically defined medium. The growth inhibition was, however, reversed by l-glutamic acid, l-glutamine, l-asparatic acid or l-asparagine.     

Raoul Combes (1883–1964) et la S.I.G.M.A.

Sans résumé     

A.A.Khan教授将来华讲学

美国康乃尔大学种子生理学家A.A.Khan教授,将于今年十月中旬来华,到广州及杭州访问,并在广州举办讲习班,做以下五方面的报告:①应用种子预措施改善幼苗生长与产     

Preference and Performance in Plant–Herbivore Interactions across Latitude–A Study in U.S. Atlantic Salt Marshes

High-latitude plants are often more palatable to herbivores than low-latitude conspecifics. Does increased plant palatability lead to better herbivore performance? Our field and laboratory work investigated (A) whether high-latitude plants have traits indicating that they should be higher-quality foods for herbivores; (B) whether geographic differences in plant quality are more important than local adaptation of herbivores. We studied 3 plant species and 6 invertebrate herbivores in U.S. Atlantic Coast. Past studies had shown high-latitude individuals of these plants are more palatable than low-latitude conspecifics. We documented plant traits and herbivore performance (body size) in the field across latitude. We collected individuals from different latitudes for factorial (plant region x herbivore region) laboratory experiments, examining how herbivore performance was affected by plant region, herbivore region, and their interaction (i.e., local adaptation). Field surveys suggested high-latitude plants were likely of higher quality to herbivores. Leaf nitrogen content in all plant species increased toward high latitudes, consistent with lower leaf C/N and higher leaf chlorophyll content at high latitudes. Furthermore, leaf toughness decreased toward higher latitudes in 1 species. The body size of 4 herbivore species increased with latitude, consistent with high-latitude leaves being of higher quality, while 2 grasshopper species showed the opposite pattern, likely due to life-history constraints. In the laboratory, high-latitude plants supported better performance in 4 herbivore species (marginal in the 5th). The geographic region where herbivores were collected affected herbivore performance in all 6 species; however, the pattern was mixed, indicating a lack of local adaptation by herbivores to plants from their own geographic region. Our results suggest that more-palatable plants at high latitudes support better herbivore growth. Given that geographic origin of either plants or herbivores can affect herbivore performance, the nature of plant-herbivore interactions is likely to change if climate change “reshuffles” plant and herbivore populations across latitude.     

Gentamicin resistance among salmonellae. A ten-year study, 1973–1982

A total of 8579 Salmonella strains received during 1973–1982 were tested for their antibiogram patterns against nine routinely used antibiotics including gentamicin. Of these, 380 strains (4.4%) showed resistance to gentamicin at levels of 10 g/ml and above. A high degree of resistance to gentamicin was recorded in 1979 (18.7%) and 1980 (9.4%). M.I.C. levels of strains received during 1982 were determined and it was found that some strains had levels as high as 160 g/ml. The comparative results of gentamicin resistance from 1973 to 1982 are presented and the public health significance of the alarming increase in two years (1979–1980) is discussed.