South Carolina's challenge to civil rights: The case of South Carolina State College, 1945–1954     

William C. Hine 《Agriculture and Human Values》1992,9(1):38-50

South Carolina State College was founded in 1896. As one of the Black institutions taking advantage of the Second Morrill Act of 1890, a large portion of the college's limited financial resources, its energies, and its programs were devoted to training students in agriculture, home economics, vocational trades, and in the education of teachers. These curriculums were considered appropriate for young Black men and women in the late nineteenth and early twentieth centuries.When the civil rights movement began to challenge segregation in education in South Carolina in the late 1940s and early 1950s, the state's white leaders responded quickly and effectively by creating graduate and law programs at State College. To preserve the racial status quo and segregation in education, Governor James F. Byrnes subsequently raised funds, including one-half million dollars from the Rockefeller sponsored General Education Board, to improve long neglected facilities at State College. A sizable portion of the funds were devoted to the agricultural program.  相似文献   

Potential Cuban agricultural export profile under open trade between the U. S. and Cuba     

Jose Alvarez  William A. Messina Jr. 《Agriculture and Human Values》1993,10(3):61-74

The sweeping changes that have taken place in the Eastern European countries and the former Soviet Union have detrimentally impacted an already weak Cuban economy. The establishment of the Special Period (1990-) embodies increasing austerity, especially in the inputs market. Recent economic liberalization policies in Cuba may lead to a more market-oriented economy, the lifting of the U. S. embargo, and commercial relations between the two countries. There is concern on the potential impact that resumption of trade may have on the U. S. and Florida's agricultural economy. This study implies potential costs for the citrus, sugar, horticultural, and seafood industries in Florida, while potential Florida exports unveil trade opportunities of a large magnitude. Further research is needed to quantify potential benefits and costs. Of special importance is the fate of Cuba's recent program on low-input sustainable agriculture once large amounts of inputs become available.  相似文献   

High-resolution crystal structure of an engineered human beta2-adrenergic G protein-coupled receptor     

Cherezov V  Rosenbaum DM  Hanson MA  Rasmussen SG  Thian FS  Kobilka TS  Choi HJ  Kuhn P  Weis WI  Kobilka BK  Stevens RC 《Science (New York, N.Y.)》2007,318(5854):1258-1265

Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors constitute the largest family of eukaryotic signal transduction proteins that communicate across the membrane. We report the crystal structure of a human beta2-adrenergic receptor-T4 lysozyme fusion protein bound to the partial inverse agonist carazolol at 2.4 angstrom resolution. The structure provides a high-resolution view of a human G protein-coupled receptor bound to a diffusible ligand. Ligand-binding site accessibility is enabled by the second extracellular loop, which is held out of the binding cavity by a pair of closely spaced disulfide bridges and a short helical segment within the loop. Cholesterol, a necessary component for crystallization, mediates an intriguing parallel association of receptor molecules in the crystal lattice. Although the location of carazolol in the beta2-adrenergic receptor is very similar to that of retinal in rhodopsin, structural differences in the ligand-binding site and other regions highlight the challenges in using rhodopsin as a template model for this large receptor family.  相似文献   

Spider Mite Detection and Canopy Component Mapping in Cotton Using Hyperspectral Imagery and Spectral Mixture Analysis   总被引：2，自引：1，他引：2  

Fitzgerald  Glenn J.  Maas  Stephan J.  Detar  William R. 《Precision Agriculture》2004,5(3):275-289

Spectral mixture analysis and hyperspectral remote sensing are analytical and hardware tools new to precision agriculture. They can allow detection and identification of various crop stresses and other plant and canopy characteristics through analysis of their spectral signatures. One stressor in cotton, the strawberry spider mite (Tetranychus turkestani U.N.), feeds on plants causing leaf puckering and reddish discoloration in early stages of infestation and leaf drop later. To determine the feasibility of detecting the damage caused by this pest at the field level, AVIRIS imagery was collected from USDA-ARS cotton research fields at Shafter, CA on 4 dates in 1999. Additionally, cotton plants and soil were imaged in situ in 10 nm increments from 450 to 1050 nm with a liquid-crystal tunable-filter camera system. Mite-damaged areas on leaves, healthy leaves, tilled shaded soil, and tilled sunlit soil were chosen as reference endmembers and used in a constrained linear spectral mixture analysis to unmix the AVIRIS data producing fractional abundance maps. The procedure successfully distinguished between adjacent mite-free and mite-infested cotton fields although shading due to sun angle differences between dates was a complicating factor. The resulting healthy plant, soil, mite-damaged, and shade fraction maps showed the distribution and relative abundance of these endmembers in the fields. These hardware and software technologies can identify the location, spatial extent, and severity of crop stresses for use in precision agriculture.  相似文献   

Genetic dissection of complex traits with chromosome substitution strains of mice     

Singer JB  Hill AE  Burrage LC  Olszens KR  Song J  Justice M  O'Brien WE  Conti DV  Witte JS  Lander ES  Nadeau JH 《Science (New York, N.Y.)》2004,304(5669):445-448

Chromosome substitution strains (CSSs) have been proposed as a simple and powerful way to identify quantitative trait loci (QTLs) affecting developmental, physiological, and behavioral processes. Here, we report the construction of a complete CSS panel for a vertebrate species. The CSS panel consists of 22 mouse strains, each of which carries a single chromosome substituted from a donor strain (A/J) onto a common host background (C57BL/6J). A survey of 53 traits revealed evidence for 150 QTLs affecting serum levels of sterols and amino acids, diet-induced obesity, and anxiety. These results demonstrate that CSSs greatly facilitate the detection and identification of genes that control the wide diversity of naturally occurring phenotypic variation in the A/J and C57BL/6J inbred strains.  相似文献   

Integrins regulate Rac targeting by internalization of membrane domains     

del Pozo MA  Alderson NB  Kiosses WB  Chiang HH  Anderson RG  Schwartz MA 《Science (New York, N.Y.)》2004,303(5659):839-842

Translocation of the small GTP-binding protein Rac1 to the cell plasma membrane is essential for activating downstream effectors and requires integrin-mediated adhesion of cells to extracellular matrix. We report that active Rac1 binds preferentially to low-density, cholesterol-rich membranes, and specificity is determined at least in part by membrane lipids. Cell detachment triggered internalization of plasma membrane cholesterol and lipid raft markers. Preventing internalization maintained Rac1 membrane targeting and effector activation in nonadherent cells. Regulation of lipid rafts by integrin signals may regulate the location of membrane domains such as lipid rafts and thereby control domain-specific signaling events in anchorage-dependent cells.  相似文献   

Regulated cycling of mitochondrial Hsp70 at the protein import channel     

Liu Q  D'Silva P  Walter W  Marszalek J  Craig EA 《Science (New York, N.Y.)》2003,300(5616):139-141

Hsp70 of the mitochondrial matrix (mtHsp70) provides a critical driving force for the import of proteins into mitochondria. Tim44, a peripheral inner-membrane protein, tethers it to the import channel. Here, regulated interactions were found to maximize occupancy of the active, adenosine 5'-triphosphate (ATP)-bound mtHsp70 at the channel through its intrinsic high affinity for Tim44, as well as through release of adenosine diphosphate (ADP)-bound mtHsp70 from Tim44 by the cofactor Mge1. A model peptide substrate rapidly released mtHsp70 from Tim44, even in the absence of ATP hydrolysis. In vivo, the analogous interaction of translocating polypeptide would release mtHsp70 from the channel. Consistent with the ratchet model of translocation, subsequent hydrolysis of ATP would trap the polypeptide, driving import by preventing its movement back toward the cytosol.  相似文献   

Carbon in Amazon forests: unexpected seasonal fluxes and disturbance-induced losses   总被引：1，自引：0，他引：1  

Saleska SR  Miller SD  Matross DM  Goulden ML  Wofsy SC  da Rocha HR  de Camargo PB  Crill P  Daube BC  de Freitas HC  Hutyra L  Keller M  Kirchhoff V  Menton M  Munger JW  Pyle EH  Rice AH  Silva H 《Science (New York, N.Y.)》2003,302(5650):1554-1557

The net ecosystem exchange of carbon dioxide was measured by eddy covariance methods for 3 years in two old-growth forest sites near Santarém, Brazil. Carbon was lost in the wet season and gained in the dry season, which was opposite to the seasonal cycles of both tree growth and model predictions. The 3-year average carbon loss was 1.3 (confidence interval: 0.0 to 2.0) megagrams of carbon per hectare per year. Biometric observations confirmed the net loss but imply that it is a transient effect of recent disturbance superimposed on long-term balance. Given that episodic disturbances are characteristic of old-growth forests, it is likely that carbon sequestration is lower than has been inferred from recent eddy covariance studies at undisturbed sites.  相似文献   

Integrase inhibitors and cellular immunity suppress retroviral replication in rhesus macaques     

Hazuda DJ  Young SD  Guare JP  Anthony NJ  Gomez RP  Wai JS  Vacca JP  Handt L  Motzel SL  Klein HJ  Dornadula G  Danovich RM  Witmer MV  Wilson KA  Tussey L  Schleif WA  Gabryelski LS  Jin L  Miller MD  Casimiro DR  Emini EA  Shiver JW 《Science (New York, N.Y.)》2004,305(5683):528-532

We describe the efficacy of L-870812, an inhibitor of HIV-1 and SIV integrase, in rhesus macaques infected with the simian-human immunodeficiency virus (SHIV) 89.6P. When initiated before CD4 cell depletion, L-870812 therapy mediated a sustained suppression of viremia, preserving CD4 levels and permitting the induction of virus-specific cellular immunity. L-870812 was also active in chronic infection; however, the magnitude and durability of the effect varied in conjunction with the pretreatment immune response and viral load. These studies demonstrate integrase inhibitor activity in vivo and suggest that cellular immunity facilitates chemotherapeutic efficacy in retroviral infections.  相似文献   

Human sperm binding is mediated by the sialyl-Lewis(x) oligosaccharide on the zona pellucida     

Pang PC  Chiu PC  Lee CL  Chang LY  Panico M  Morris HR  Haslam SM  Khoo KH  Clark GF  Yeung WS  Dell A 《Science (New York, N.Y.)》2011,333(6050):1761-1764

Human fertilization begins when spermatozoa bind to the extracellular matrix coating of the oocyte, known as the zona pellucida (ZP). One spermatozoan then penetrates this matrix and fuses with the egg cell, generating a zygote. Although carbohydrate sequences on the ZP have been implicated in sperm binding, the nature of the ligand was unknown. Here, ultrasensitive mass spectrometric analyses revealed that the sialyl-Lewis(x) sequence [NeuAcα2-3Galβ1-4(Fucα1-3)GlcNAc], a well-known selectin ligand, is the most abundant terminal sequence on the N- and O-glycans of human ZP. Sperm-ZP binding was largely inhibited by glycoconjugates terminated with sialyl-Lewis(x) sequences or by antibodies directed against this sequence. Thus, the sialyl-Lewis(x) sequence represents the major carbohydrate ligand for human sperm-egg binding.  相似文献