Organic aerosol formation downwind from the Deepwater Horizon oil spill     

de Gouw JA  Middlebrook AM  Warneke C  Ahmadov R  Atlas EL  Bahreini R  Blake DR  Brock CA  Brioude J  Fahey DW  Fehsenfeld FC  Holloway JS  Le Henaff M  Lueb RA  McKeen SA  Meagher JF  Murphy DM  Paris C  Parrish DD  Perring AE  Pollack IB  Ravishankara AR  Robinson AL  Ryerson TB  Schwarz JP  Spackman JR  Srinivasan A  Watts LA 《Science (New York, N.Y.)》2011,331(6022):1295-1299

A large fraction of atmospheric aerosols are derived from organic compounds with various volatilities. A National Oceanic and Atmospheric Administration (NOAA) WP-3D research aircraft made airborne measurements of the gaseous and aerosol composition of air over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico that occurred from April to August 2010. A narrow plume of hydrocarbons was observed downwind of DWH that is attributed to the evaporation of fresh oil on the sea surface. A much wider plume with high concentrations of organic aerosol (>25 micrograms per cubic meter) was attributed to the formation of secondary organic aerosol (SOA) from unmeasured, less volatile hydrocarbons that were emitted from a wider area around DWH. These observations provide direct and compelling evidence for the importance of formation of SOA from less volatile hydrocarbons.  相似文献   

The crystallization age of eucrite zircon     

Srinivasan G  Whitehouse MJ  Weber I  Yamaguchi A 《Science (New York, N.Y.)》2007,317(5836):345-347

Eucrites are a group of meteorites that represent the first planetary igneous activity following metal-silicate differentiation on an early planetesimal, similar to Asteroid 4 Vesta, and, thus, help date geophysical processes occurring on such bodies in the early solar system. Using the short-lived radionuclide (182)Hf as a relative chronometer, we demonstrate that eucrite zircon crystallized quickly within 6.8 million years of metal-silicate differentiation. This implies that mantle differentiation on the eucrite parent body occurred during a period when internal heat from the decay of (26)Al and (60)Fe was still available. Later metamorphism of eucrites took place at least 8.9 million years after the zircons crystallized and was likely caused by heating from impacts, or by burial under hot material excavated by impacts, rather than from lava flows. Thus, the timing of eucrite formation and of mantle differentiation is constrained.  相似文献   

Identification and classification of aromatic rices based on DNA fingerprinting   总被引：5，自引：0，他引：5  

P. Ray Choudhury  S. Kohli  K. Srinivasan  T. Mohapatra  R.P. Sharma 《Euphytica》2001,118(3):243-251

Aromatic rices are preferred by the consumers all over the world due to its flavour and palatability. Although a large number of these collections are available, little systematic analysis of genetic diversity has been carried out. With the objective of identification and classification of aromatic rice genotypes, RAPD profiling was employed using 58 random decamer primers. Most of these primers (96.5%) detected polymorphism among the genotypes. Of the 465 amplified bands, 314 were polymorphic. Cluster analysis based on Jaccard's similarity coefficient using UPGMA grouped all the traditional tall, photosensitive, low yielding, long grained ‘basmati’ aromatics together. The short grained aromatic cultivars, formed a different cluster with high level of average similarity among themselves. The dendrogram based on 58 primers was highly similar to that based on 10 and 15 primers with matrix correlation (r) of 0.88 and 0.91, respectively. This suggested that a set of 10 primers can be employed for an initial assessment of genetic diversity in a large number of collections. All the rice genotypes included in the study could be distinguished from each other at the level of 19 to 186 polymorphic bands between individuals in pair wise comparison over all the 58 primers. Probability of identical profiles by chance suggested that about 10⁴¹ genotypes can be unambiguously differentiated by RAPD fingerprints obtained by 58 primers. A diagrammatic mode of presentation of DNA fingerprints of the aromatic rices based on 10 of the informative primers was developed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Allelic relationships of flowering time genes in chickpea     

Pooran M. Gaur  Srinivasan Samineni  Shailesh Tripathi  Rajeev K. Varshney  C. L. Laxmipathi Gowda 《Euphytica》2015,203(2):295-308

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Presence of maturation-promoting factor in 17α,20β-dihydroxy-4-pregnen-3-one-induced oocytes of catfish,Clarias batrachus     

S. Haider  K. Balamurugan 《Fish physiology and biochemistry》1995,14(6):501-508

Full-grown immature Clarias batrachus oocytes respond in vitro to exogenous 17,20-dihydroxy-4-preg-nen-3-one ( 17,20-DP) by undergoing germinal vesicle breakdown (GVBD). Cytosolic extract (CE) prepared from 17,20-DP-induced oocytes has been shown to produce similar effect when microinjected into unstimulated immature oocytes of the same fish. A dose of 50 nl is enough to cause 100% GVBD after 4 h. Maturation-promoting factor was investigated from 17,20-DP-induced, immature and cycloheximide treated oocytes incubated in presence of [³⁵S] methionine. When the proteins were extracted and analyzed on SDS-PAGE, two prominent bands corresponding to molecular weight 34- and 46-kDa were detected in the CE of mature oocytes. However, labelling of [³⁵S] methionine was observed mainly in the region of 46 kDa protein band indicating de novo synthesis of this particular protein during l7,20-DP-induction. Further, immunoblotting study by using rabbit anti-cyclin B₁ antibody has clearly demonstrated that the protein which is newly synthesized is highly homologous to Xenopus cyclin B₁ and goldfish cyclin B.  相似文献   

Phenotypic and genotypic antimicrobial resistance patterns of Escherichia coli isolated from dairy cows with mastitis     

Srinivasan V  Gillespie BE  Lewis MJ  Nguyen LT  Headrick SI  Schukken YH  Oliver SP 《Veterinary microbiology》2007,124(3-4):319-328

Pulsed field gel electrophoresis (PFGE) patterns, susceptibility to 26 antimicrobial agents used in veterinary and human medicine, and prevalence of antimicrobial resistance genes of Escherichia coli isolated from cows with mastitis were evaluated. Among 135 E. coli isolates, PFGE analysis revealed 85 different genetic patterns. All E. coli were resistant to two or more antimicrobials in different combinations. Most E. coli were resistant to antimicrobials used in veterinary medicine including ampicillin (98.4%, >or=32 microg/ml) and many E. coli were resistant to streptomycin (40.3%, >or=64 microg/ml), sulfisoxazole (34.1%, >or=512 microg/ml), and tetracycline (24.8%, >or=16 microg/ml). Most E. coli were resistant to antimicrobials used in human medicine including aztreonam (97.7%, >or=32 microg/ml) and cefaclor (89.9%, >or=32 microg/ml). Some E. coli were resistant to nitrofurantoin (38%, >or=128 microg/ml), cefuroxime (22.5%, >or=32 microg/ml), fosfomycin (17.8%, >or=256 microg/ml). All E. coli were susceptible to ciprofloxacin and cinoxacin. Almost 97% (123 of 127) of ampicillin-resistant isolates carried ampC. Eleven of 52 (21.2%) streptomycin-resistant isolates carried strA, strB and aadA together and 29 streptomycin-resistant isolates (55.8%) carried aadA alone. Among 44 sulfisoxazole-resistant E. coli, 1 isolate (2.3%) carried both sulI and sulII, 12 (27.3%) carried sulI and 10 (22.7%) isolates carried sulII. Among 32 tetracycline-resistant isolates, 14 (43.8%) carried both tetA and tetC and 14 (43.8%) carried tetC. Results of this study demonstrated that E. coli from cows with mastitis were genotypically different, multidrug resistant and carried multiple resistance genes. These bacteria can be a reservoir for antimicrobial resistance genes and can play a role in the dissemination of antimicrobial resistance genes to other pathogenic and commensal bacteria in the dairy farm environment.  相似文献   

A role for thrombin receptor signaling in endothelial cells during embryonic development     

Griffin CT  Srinivasan Y  Zheng YW  Huang W  Coughlin SR 《Science (New York, N.Y.)》2001,293(5535):1666-1670

The coagulation protease thrombin triggers fibrin formation, platelet activation, and other cellular responses at sites of tissue injury. We report a role for PAR1, a protease-activated G protein-coupled receptor for thrombin, in embryonic development. Approximately half of Par1-/- mouse embryos died at midgestation with bleeding from multiple sites. PAR1 is expressed in endothelial cells, and a PAR1 transgene driven by an endothelial-specific promoter prevented death of Par1-/- embryos. Our results suggest that the coagulation cascade and PAR1 modulate endothelial cell function in developing blood vessels and that thrombin's actions on endothelial cells-rather than on platelets, mesenchymal cells, or fibrinogen-contribute to vascular development and hemostasis in the mouse embryo.  相似文献   

Tolerance to excess moisture in maize (Zea mays L.): susceptible crop stages and identification of tolerant genotypes     

Pervez H. Zaidi  S. Rafique  P. K. Rai  N. N. Singh  G. Srinivasan 《Field Crops Research》2004,90(2-3):189-202

Excess moisture (water-logging) during the summer–rainy season is one of the major production constraints for maize (Zea mays L.) in a large area of Southeast Asia. Identification and development of genotypes capable of withstanding the stress conditions could be an ideal and affordable approach suitable for resource poor maize-growing farmers of such areas. We attempted to identify the most susceptible/critical crop stage(s) of maize for excess moisture stress, and to develop a screening technique and selection strategies for identification of germplasm tolerant to excess moisture stress. Among the four crop stages, i.e. early seedling (V2), knee-high (V7), tasseling (VT) and milk stage (R1), V2 was found to be highly susceptible, followed by the V7 stage. A screening technique (cup method) was developed/standardized, and was found to be an efficient technique for large-scale screening of maize genotypes against excess soil moisture stress. Germplasm was screened using this technique followed by field evaluation at the V7 growth stage (seventh leaf visible). Excess soil moisture stress severely affected various growth and biochemical parameters, impaired anthesis and silking, and eventually resulted in poor kernel development and yield. However, remarkable variability was found among the genotypes studied. Genotypes with good carbohydrate accumulation in stem tissues, moderate stomatal conductance, <5 days ASI, high root porosity, and early brace root development ability have been found to have good tolerance against the hypoxia/anoxia caused by excess soil moisture conditions.  相似文献   

Impact of Bran Addition on Water Properties and Gluten Secondary Structure in Wheat Flour Doughs Studied by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy     

Jayne E. Bock  Robin K. Connelly  Srinivasan Damodaran 《Cereal Chemistry》2013,90(4):377-386

The aim of this work was to elucidate the underlying physical mechanism(s) by which bran influences whole grain dough properties by monitoring the state of water and gluten secondary structure in wheat flour and bran doughs containing 35–50% moisture and 0–10% added bran. The system was studied with attenuated total reflectance (ATR) FTIR spectroscopy. Comparison of the OH stretch band of water in flour dough with that in H₂O‐D₂O mixtures having the same water content revealed the formation of two distinct water populations in flour dough corresponding to IR absorption frequencies at 3,600 and 3,200 cm^–1. The band intensity at 3,200 cm^–1, which is related to water bound to the dough matrix, decreased and shifted to lower frequencies with increasing moisture content of the dough. Addition of bran to the dough caused redistribution of water in the flour and bran dough system, as evidenced by shifts in OH stretch frequency in the 3,200 cm^–1 region to higher frequencies and a reduction in monomeric water (free water). This water redistribution affected the secondary structure of gluten in the dough, as evidenced by changes in the second‐derivative ATR‐FTIR difference spectra in the amide I region. Bran addition caused an increase in β‐sheet content and a decrease in β‐turn (β‐spiral) content. However, this bran‐induced transconformational change in gluten was more significant in the 2137 flour dough than in Overley flour dough. This study revealed that when bran is added to flour dough, water redistribution among dough components promotes partial dehydration of gluten and collapse of β‐spirals into β‐sheet structures. This transconformational change may be the physical basis for the poor quality of bread containing added bran.  相似文献   

Potentiation of Hypolipidemic and Weight-Reducing Influence of Dietary Tender Cluster Bean ( Cyamopsis tetragonoloba ) When Combined with Capsaicin in High-Fat-Fed Rats     

S Pande  K Srinivasan 《Journal of agricultural and food chemistry》2012,60(33):8155-8162

Soluble fiber-rich tender cluster bean pod ( Cyamopsis tetragonoloba ) (CB) and a combination of CB and capsaicin, a thermogenic spice compound, were evaluated for weight-reducing effect in high-fat-fed Wistar rats. Freeze-dried CB and capsaicin were included at 15 and 0.015%, respectively, in the high-fat (30%) diet for 8 weeks. Excretion of dietary fat, fat deposition in adipose, and activities of enzymes involved in lipolysis and lipogenesis were examined. CB and capsaicin additively decreased weight gain in high-fat-fed rats, without affecting feed intake. The antiobesity potential of CB was through impeding fat accumulation in adipose and enhancing fat excretion. Decrease in adipose triglyceride by the combination was higher than their individual effects and was accompanied by enhanced activity of hormone-sensitive lipase-facilitating mobilization of depot fat. Increased fecal excretion of triglycerides by the combination of CB and capsaicin was additive. Whereas the hypolipidemic effect of the combination was higher than their individual effects, the decrease in hepatic cholesterol and triglycerides produced by the combination was additve. Thus, dietary CB significantly checked weight gain and adverse changes in lipid profile in high-fat-fed condition amounting to a cardioprotective effect. These beneficial effects were potentiated by coadministration of capsaicin.  相似文献