Three heteroarotinoids containing a nitrogen atom in the first ring and a C-O linking group between the two aryl rings were synthesized and evaluated for RAR and RXR retinoid receptor transactivation, tumor cell growth inhibition, and transglutaminase (TGase) induction. Ethyl 4-(N,4,4-trimethyl-1,2,3,4-tetrahydroquinolinyl)benzoate (1) contained an N-CH(3) group and activated all retinoid receptors except for RARgamma. Inceasing the hydrophobicity around the rings with analogues ethyl 4-(N,4,4,7-tetramethyl-1,2,3, 4-tetrahydroquinolin-6-oyloxy)benzoate (2) [7-methyl group added] and ethyl 4-(4,4-dimethyl-N-isopropyl-1,2,3, 4-tetrahydroquinolin-6-oyloxy)benzoate (3) [NCH(CH(3))(2) group at C-4] increased the potency and specificity for RARalpha, RARbeta, and RXRalpha, compared to 1, but had little effect on RXRbeta and RXRgamma activation. Although 1 and 3 were unable to activate RARgamma, 2 did activate this receptor with efficacy and high potency equal to that of 9-cis-retinoic acid (9-c-RA). All three heteroarotinoids exhibited 5-8-fold greater specificities for RARbeta over RARalpha. In addition, esters 1-3 inhibited the growth of two cell lines each derived from cervix, vulvar, ovarian, and head/neck tumors with similar efficiencies to that of 9-c-RA through a mechanism independent of apoptosis. The vulvar cell lines were the most sensitive, and the ovarian lines were the least sensitive. Ester 2 was similar to 1 and 3 except that 2 was a much more potent growth inhibitor of the two vulvar cell lines, which is consistent with strong RARgamma activation by 2 (but not by 1 and 3) and the high levels of RARgamma expression in skin. All three heteroarotinoids induced production of TGase, a marker of retinoid activity in human erythroleukemic cells. Esters 2 and 3 were the more potent TGase activators than 1, in agreement with the stronger activation of the RAR receptors by 2 and 3. The biological activities of these agents, and the RARgamma potency of 2 in particular, demonstrate the promise of these compounds as pharmaceutics for cancer and skin disorders.
Application of relatively low nitrogen doses results in high yield and high quality of Marandu grass under continuous stock. The herbage, forage accumulation rate, and nutritive value increased linearly with nitrogen application rate. Our data are applicable to that of tropical areas with Oxisol, seasonal rainfall (wet summer), Marandu palisade-grass, and Nellore cattle during the rearing phase.
The apparent nitrogen recovery was inversely proportional to the nitrogen application rates. The critical N increased with increasing nitrogen level and the NNI showed that the N application was enough to supply the critical N level for Marandu grass nutrition.
In this study, our aim was to explore variation in carbon and nitrogen isotope values within and between feathers of individual birds, and the factors that contribute to such variation. We examined isotopic variation in feathers collected from adults of two small congeneric petrel species, the broad-billed prion Pachyptila vittata and Antarctic prion P. desolata. Broad-billed prions are dietary specialists that feed predominantly on large copepods, and Antarctic prions feed on a wider range of small zooplankton taxa (Brooke 2004). Both species are vulnerable to predation by skuas Stercorarius spp. that breed near to prion colonies (Furness 1987), providing the remains of recently killed birds for sampling. These two species were considered to be ideal for our study, as narrow diet breadth should limit the degree of variation in feather isotope values related to individual diet specialisation. In addition, prions undergo a complete moult of primary feathers during the nonbreeding period (Bridge 2006), allowing us to examine changes in isotope values within and between feathers of individuals.
Differences in feather isotope values between samples were examined by fitting isotope value as the response variable in a linear mixed-effects model with sample type included as a two-level (rachis/vane) or four-level (rachis/mid-rachis/mid-vane/vane) fixed effect. We fitted separate models for carbon and nitrogen isotopes, and for each species. As models for broad-billed prions included two samples per feather, and four feathers per bird, we fitted feather type and bird identity as nested random intercepts. Models for Antarctic prions included data from four samples per feather, but only one feather per bird. In this case, we fitted bird identity as a random intercept.
Studies have shown that various environmental factors such as pH, light, nutrients, temperature, and dissolved oxygen affect the production of MCs [16,17,18]. Phosphorus (P) availability is generally assumed to be an important limiter of cyanobacterial blooms and the production of MCs because some cyanobacteria can fix nitrogen (N) under N-limited conditions via N2 fixation . Conversely, the importance of N availability has also been shown in some studies [1,20]. Contradictory results for the impact of N:P ratios on cyanobacterial bloom and the production of MCs have also been widely reported [21,22]. The knowledge of how N and P interact to limit the cyanobacterial growth is essential in the eutrophication control and management . Therefore, the objectives of this study are to investigate the effect of N availability, P availability, and N:P ratios on M. aeruginosa growth and the production of MCs. These results will be helpful to elucidate the influence of nutrients on cyanobacterial bloom and the production of MCs, which are essential in the MC removal and eutrophication control.
The Curtius rearrangement (or Curtius reaction or Curtius degradation), first defined by Theodor Curtius in 1885, is the thermal decomposition of an acyl azide to an isocyanate with loss of nitrogen gas. The isocyanate then undergoes attack by a variety of nucleophiles such as water, alcohols and amines, to yield a primary amine, carbamate or urea derivative respectively. Several reviews have been published.
The acyl azide is usually made from the reaction of acid chlorides or anydrides with sodium azide or trimethylsilyl azide. Acyl azides are also obtained from treating acylhydrazines with nitrous acid. Alternatively, the acyl azide can be formed by the direct reaction of a carboxylic acid with diphenylphosphoryl azide (DPPA).
It was believed that the Curtius rearrangement was a two-step processes, with the loss of nitrogen gas forming an acyl nitrene, followed by migration of the R-group to give the isocyanate. However, recent research has indicated that the thermal decomposition is a concerted process, with both steps happening together, due to the absence of any nitrene insertion or addition byproducts observed or isolated in the reaction. Thermodynamic calculations also support a concerted mechanism.
In one variation called the Darapsky degradation, or Darapsky synthesis, a Curtius rearrangement takes place as one of the steps in the conversion of an α-cyanoester to an amino acid. Hydrazine is used to convert the ester to an acylhydrazine, which is reacted with nitrous acid to give the acyl azide. Heating the azide in ethanol yields the ethyl carbamate via the Curtius rearrangement. Acid hydrolysis yields the amine from the carbamate and the carboxylic acid from the nitrile simultaneously, giving the product amino acid.
By using liquid nitrogen cooling and bypassing the card's voltage limits, Kingpin dialed the clock speeds of his 2080 Ti all the way up from 1545Mhz to 2415Mhz and its memory speeds from 7000Mhz to 8683Mhz. He paired it with a liquid nitrogen cooled i9-7980XE running at around 5.7Ghz, and subsequently broke every record he attempted in 3DMark.
While Kingpin managed to increase the performance by 20%, you don't need liquid nitrogen to see serious gains by overclocking an RTX 2080 Ti as YouTuber JayzTwoCents proved when he climbed to number 15 on the Time Spy Extreme ladder at only 2175Mhz.
As part of this process, the less reactive nitric oxide is regenerated at beneficial physiological concentrations.In contrast, α-tocopherol can react with NO2 to form a reactive nitrosating agent, and it does not effectivelyreduce NO2 to NO in the absence of light.
Evidence suggests that the biological activities of β-, γ- and δ-tocopherols do not reflect their behaviour as chemical antioxidants, but anti-inflammatory, antineoplastic and natriuretic actions have been reported.Some non-antioxidant effects of γ-tocopherol in tissues in relation to reactive nitrogen oxide species have been observed, but the specificity of these in vivo is not yet certain. In addition, anti-inflammatory properties have been described that have been attributed to a chain-shortened metabolite.Beneficial effects against cancer cells in vitro have been observed that have been ascribed to scavenging of reactive nitrogen species, since such effects are not seen with α-tocopherol.While α-tocopherol has no effect on cancer, there is some evidence that its isomers may influence tumour cells by activating the mitogen-activated protein kinase (MAPK) signalling pathway.
Agriculture and land use change are some of the most important sources of greenhouse gases, accounting for about one-fourth of the global gaseous emissions ( IPCC, 2014Intergovernmental Panel on Climate Change - IPCC. Climate change 2014: synthesis report. Contribution of Working Groups I, II and III to the fifth assessment Report of the intergovernmental panel on climate change. Cambridge: Cambridge University Press; 2014. ). In Brazil, this source accounts for the more significant fraction of about two-thirds of the overall emissions, and more remarkably for 92 % of nitrous oxide (N2O) and 78 % of methane (CH4) emissions ( MCTI, 2014Ministério da Ciência, Tecnologia e Inovação - MCTI. Estimativas anuais de emissões de gases de efeito estufa no Brasil. 2. ed. Brasília, DF: MCTI; 2014. ; Azevedo, 2016Azevedo TR. Análise das emissões de GEE Brasil (1970-2014) e suas implicações para políticas públicas e a contribuição brasileira para o Acordo de Paris. Brasil: Observatório do Clima / SEEG; 2016. Available from: -content/uploads/2016/09/wip-16-09-02-relatoriosseeg-sintese-1.pdf -content/u... ). Therefore, it is worth seeking strategies to mitigate emissions related to agriculture and land use change. 041b061a72