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41.
42.
Upendra M. Sainju Harry H. Schomberg Bharat P. Singh Wayne F. Whitehead P. Glynn Tillman Sharon L. Lachnicht-Weyers 《Soil & Tillage Research》2007,96(1-2):205-218
Cover crops may influence soil carbon (C) sequestration and microbial biomass and activities by providing additional residue C to soil. We examined the influence of legume [crimson clover (Trifolium incarnatum L.)], nonlegume [rye (Secale cereale L.)], blend [a mixture of legumes containing balansa clover (Trifolium michelianum Savi), hairy vetch (Vicia villosa Roth), and crimson clover], and rye + blend mixture cover crops on soil C fractions at the 0–150 mm depth from 2001 to 2003. Active fractions of soil C included potential C mineralization (PCM) and microbial biomass C (MBC) and slow fraction as soil organic C (SOC). Experiments were conducted in Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Kandiudults) under dryland cotton (Gossypium hirsutum L.) in central Georgia and in Tifton loamy sand (fine-loamy, siliceous, thermic, Plinthic Kandiudults) under irrigated cotton in southern Georgia, USA. Both dryland and irrigated cotton were planted in strip tillage system where planting rows were tilled, thereby leaving the areas between rows untilled. Total aboveground cover crop and cotton C in dryland and irrigated conditions were 0.72–2.90 Mg C ha−1 greater in rye + blend than in other cover crops in 2001 but was 1.15–2.24 Mg C ha−1 greater in rye than in blend and rye + blend in 2002. In dryland cotton, PCM at 50–150 mm was greater in June 2001 and 2002 than in January 2003 but MBC at 0–150 mm was greater in January 2003 than in June 2001. In irrigated cotton, SOC at 0–150 mm was greater with rye + blend than with crimson clover and at 0–50 mm was greater in March than in December 2002. The PCM at 0–50 and 0–150 mm was greater with blend and crimson clover than with rye in April 2001 and was greater with crimson clover than with rye and rye + blend in March 2002. The MBC at 0–50 mm was greater with rye than with blend and crimson clover in April 2001 and was greater with rye, blend, and rye + blend than with crimson clover in March 2002. As a result, PCM decreased by 21–24 g CO2–C ha−1 d−1 but MBC increased by 90–224 g CO2–C ha−1 d−1 from June 2001 to January 2003 in dryland cotton. In irrigated cotton, SOC decreased by 0.1–1.1 kg C ha−1 d−1, and PCM decreased by 10 g CO2–C ha−1 d−1 with rye to 79 g CO2–C ha−1 d−1 with blend, but MBC increased by 13 g CO2–C ha−1 d−1 with blend to 120 g CO2–C ha−1 d−1 with crimson clover from April 2001 to December 2002. Soil active C fractions varied between seasons due to differences in temperature, water content, and substrate availability in dryland cotton, regardless of cover crops. In irrigated cotton, increase in crop C input with legume + nonlegume treatment increased soil C storage and microbial biomass but lower C/N ratio of legume cover crops increased C mineralization and microbial activities in the spring. 相似文献
43.
Saturation in milk and meat fats 总被引:1,自引:0,他引:1
Meat and milk products from ruminants (cows, goats, sheep, and beef animals) contribute 35 to 40 percent of the fat in the average American diet. Such fat is highly saturated, containing less than about 4 percent polyunsaturated fatty acids. The unsaturated plant lipids (fats) ordinarily consumed by the ruminant are hydrogenated (saturated) in the rumen. Transport and incorporation of this hydrogenated fat into meat and milk follows. Rumen hydrogenation does not take place until the fat is broken down to free fatty acids, thus establishing the fact that lipolysis is an essential feature of the process. Circumvention of this lipolysis may lead to more-unsaturated meat and milk fat. 相似文献
44.
45.
S Patton P T Chandler E B Kalan A R Loeblich G Fuller A A Benson 《Science (New York, N.Y.)》1967,158(802):789-790
Two harvests of ocean-growing red tide, comprised mainly of Gonyaulax polyedra, were evaluated in limited trials of rat feeding. The protein of red tide (25 to 30 percent, dry basis) supported growth satisfactorily. The essential amino acid composition of the protein closely resembles that of casein, the major protein of milk. As a marine resource, plankton represents a challenge for research. 相似文献
46.
Hafezparast M Klocke R Ruhrberg C Marquardt A Ahmad-Annuar A Bowen S Lalli G Witherden AS Hummerich H Nicholson S Morgan PJ Oozageer R Priestley JV Averill S King VR Ball S Peters J Toda T Yamamoto A Hiraoka Y Augustin M Korthaus D Wattler S Wabnitz P Dickneite C Lampel S Boehme F Peraus G Popp A Rudelius M Schlegel J Fuchs H Hrabe de Angelis M Schiavo G Shima DT Russ AP Stumm G Martin JE Fisher EM 《Science (New York, N.Y.)》2003,300(5620):808-812
Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein. 相似文献
47.
48.
W H Patton 《Science (New York, N.Y.)》1965,150(697):767-769
Eimeria tenella, an intracellular protozoan parasite of the cecal epithelium of chickens, developed asexually in monolayer cultures of mammalian fibroblasts, mammalian epithelial cells, and avian fibroblasts mintained under various mediums at 41 degrees C. Sexual stages of the parasite were not seen. Established cell lines and secondary cell cultures were equally suitable for cultivation of the parasite. 相似文献
49.
Structure of a legume lectin with an ordered N-linked carbohydrate in complex with lactose 总被引:13,自引:0,他引:13
The three-dimensional structure of the lactose complex of the Erythrina corallodendron lectin (EcorL), a dimer of N-glycosylated subunits, was determined crystallographically and refined at 2.0 angstrom resolution to an R value of 0.19. The tertiary structure of the subunit is similar to that of other legume lectins, but interference by the bulky N-linked heptasaccharide, which is exceptionally well ordered in the crystal, forces the EcorL dimer into a drastically different quaternary structure. Only the galactose moiety of the lactose ligand resides within the combining site. The galactose moiety is oriented differently from ligands in the mannose-glucose specific legume lectins and is held by hydrophobic interactions with Ala88, Tyr106, Phe131, and Ala218 and by seven hydrogen bonds, four of which are to the conserved Asp89, Asn133, and NH of Gly107. The specificity of legume lectins toward the different C-4 epimers appears to be associated with extensive variations in the outline of the variable parts of the binding sites. 相似文献
50.
Uhlmann WR Bennett R Botkin JR Botstein D Boughman JA Chakravarti A Clayton EW Kahn J Koenig B Murray TH Olson MV Rowley J Terry S Valle D 《Science (New York, N.Y.)》2003,299(5612):1515; author reply 1515