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Jinzhu Zheng Yulia Polyakova Kyung Ho Row 《Biotechnology and Bioprocess Engineering》2006,11(6):477-483
Ionic liquids in the form of organic salts are being widely used as new solvent media. In this paper three positional isomers,o-amino benzoic acid,m-amino benzoic acid, andp-amino benzoic acids were separated with four different ionic liquids as mobile phase additives using high performance liquid
chromatography (HPLC). The following ionic liquids were used: 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm][BF4]), 1-ethyl-3-methylimidazolium methylsulfate ([EMIm][MS]), and 1-octyl-3-methylimidazolium methylsulfate ([OMIm][MS]). The
effects of the alkyl group length on the imidazolium ring and its counterion, and the concentrations of the ionic liquids
on the retention factors and resolutions of amino benzoic acid isomers were tested. The results of the separations with ionic
liquids as the eluents were better than those without ionic liquids. Excellent separations of the three isomers were achieved
using 2.0≈8.0 mM/L [OMIm][MS] and 1.0≈8.0 mM/L [EMIm][MS] as the eluent modifiers. 相似文献
64.
Aim The goal of our study was to investigate the effects of a fragmented landscape on the genetic population structure of two sympatric snake species that differ in habitat preference. The eastern garter snake (Thamnophis sirtalis sirtalis) is a common, habitat generalist, whereas the endangered eastern foxsnake (Mintonius [Elaphe] gloydi) is rarer, geographically restricted, and a marsh‐specialist. We were most interested in comparing the genetic population structure of both species and identifying any natural and human‐created features of the landscape that overlap with genetic disjunctions. Location Southwestern Ontario, Canada, surveying over half of the remaining range of the eastern foxsnake. Methods We utilized DNA microsatellite markers to examine genetic population structure of both species. The number of genetically distinct clusters for each species was determined using both Bayesian spatial assignment and spatial principal component analyses (sPCA). Genetic clusters were overlaid onto a habitat map to deduce possible physiognomic barriers to gene flow. Results Spatial assignment revealed three genetic clusters for garter snakes and five for foxsnakes. Each individual garter snake had a near equal probability of membership to two or more clusters with no cluster mapping onto a discrete geographic region, indicating that garter snakes comprise a single genetic population. The identified foxsnake clusters correspond to geographically circumscribed locations on the landscape, roughly coincident with isolated patches of suitable habitat. sPCAs revealed significant global allelic structure for foxsnakes, but not for garter snakes. No significant local structure was found for either species. Main Conclusions Our results imply that foxsnakes and garter snakes are differentially impacted by the same landscape or have dramatically different effective population sizes. Unsuitable intervening habitat such as agricultural tracts and roads between existing populations of foxsnakes appears to act as barriers to gene flow, while garter snake movement appears unrestricted by these features. Our findings have important implications for the management of eastern foxsnakes. 相似文献
65.
Introduction – Liquiritin and glycyrrhizin are valuable components of licorice. An effective separation and determination procedure is needed to separate the liquiritin and glycyrrhizin from the licorice extract. Methodology – A polymer‐confined, ionic liquid sorbent was developed using a process involving polymerisation and modification. The obtained porous particles were used as a sorbent in a solid‐phase extraction process to isolate liquiritin and glycyrrhizin from licorice with different washing and elution solvents. The porous alkyl‐pyridinium polymer sorbent was compared with the C18 sorbent. Results – A simple and convenient method was established to the selectively separate and determinate of liquiritin and glycyrrhizin using a porous ionic liquid‐based polymer coupled with HPLC. Additionally, this study evaluated the application of this sorbent for the detection of these two compounds in commercial medicines. Conclusion – This method was a viable tool that was compatible with the existing HPLC methods and was used to separate and analyse the content of liquiritin and glycyrrhizin in licorice. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
66.
New statistical techniques and software have improved our ability to quantify fine-scale population structure. We isolated 11 microsatellite markers for eastern foxsnakes (Elaphe gloydi) and surveyed the variability of each using 115-136 individuals from one population in southwestern Ontario. We determined that all loci were variable and conformed to Hardy-Weinberg expectations and that no locus demonstrated linkage disequilibrium. We are using these markers to quantify the scale of gene flow, and to assess the effect of variable landscapes on connectivity and genetic diversity of three disjunct regional populations in the northern portion of the species' range. 相似文献
67.
Developing approaches for linear mixed modeling in landscape genetics through landscape‐directed dispersal simulations 下载免费PDF全文
Jeffrey R. Row Steven T. Knick Sara J. Oyler‐McCance Stephen C. Lougheed Bradley C. Fedy 《Ecology and evolution》2017,7(11):3751-3761
Dispersal can impact population dynamics and geographic variation, and thus, genetic approaches that can establish which landscape factors influence population connectivity have ecological and evolutionary importance. Mixed models that account for the error structure of pairwise datasets are increasingly used to compare models relating genetic differentiation to pairwise measures of landscape resistance. A model selection framework based on information criteria metrics or explained variance may help disentangle the ecological and landscape factors influencing genetic structure, yet there are currently no consensus for the best protocols. Here, we develop landscape‐directed simulations and test a series of replicates that emulate independent empirical datasets of two species with different life history characteristics (greater sage‐grouse; eastern foxsnake). We determined that in our simulated scenarios, AIC and BIC were the best model selection indices and that marginal R2 values were biased toward more complex models. The model coefficients for landscape variables generally reflected the underlying dispersal model with confidence intervals that did not overlap with zero across the entire model set. When we controlled for geographic distance, variables not in the underlying dispersal models (i.e., nontrue) typically overlapped zero. Our study helps establish methods for using linear mixed models to identify the features underlying patterns of dispersal across a variety of landscapes. 相似文献
68.
The identification and demographic assessment of biologically meaningful populations is fundamental to species’ ecology and management. Although genetic tools are used frequently to identify populations, studies often do not incorporate demographic data to understand their respective population trends. We used genetic data to define subpopulations in a continuously distributed species. We assessed demographic independence and variation in population trends across the distribution. Additionally, we identified potential barriers to gene flow among subpopulations. We sampled greater sage-grouse (Centrocercus urophasianus) leks from across their range (≈175,000 Km2) in Wyoming and amplified DNA at 14 microsatellite loci for 1761 samples. Subsequently, we assessed population structure in unrelated individuals (n = 872) by integrating results from multiple Bayesian clustering approaches and used the boundaries to inform our assessment of long-term population trends and lek activity over the period of 1995–2013. We identified four genetic clusters of which two northern ones showed demographic independence from the others. Trends in population size for the northwest subpopulation were statistically different from the other three genetic clusters and the northeast and southwest subpopulations demonstrated a general trend of increasing proportion of inactive leks over time. Population change from 1996 to 2012 suggested population growth in the southern subpopulations and decline, or neutral, change in the northern subpopulations. We suggest that sage-grouse subpopulations in northern Wyoming are at greater risk of extirpation than the southern subpopulations due to smaller census and effective population sizes and higher variability within subpopulations. Our research is an example of incorporating genetic and demographic data and provides guidance on the identification of subpopulations of conservation concern. 相似文献
69.
Molecular components of a cell death pathway activated by endoplasmic reticulum stress 总被引:9,自引:0,他引:9
Rao RV Poksay KS Castro-Obregon S Schilling B Row RH del Rio G Gibson BW Ellerby HM Bredesen DE 《The Journal of biological chemistry》2004,279(1):177-187
Alterations in Ca2+ homeostasis and accumulation of misfolded proteins in the endoplasmic reticulum (ER) cause ER stress that ultimately leads to programmed cell death. Recent studies have shown that ER stress triggers programmed cell death via an alternative intrinsic pathway of apoptosis that, unlike the intrinsic pathway described previously, is independent of Apaf-1 and cytochrome c. In the present work, we have used a set of complementary approaches, including two-dimensional gel electrophoresis coupled with matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and nano-liquid chromatography-electrospray ionization mass spectrometry with tandem mass spectrometry, RNA interference, co-immunoprecipitation, immunodepletion of candidate proteins, and reconstitution studies, to identify mediators of the ER stress-induced cell death pathway. Our data identify two molecules, valosin-containing protein and apoptosis-linked gene-2 (ALG-2), that appear to play a role in mediating ER stress-induced cell death. 相似文献
70.
Increased susceptibility to intermittent hypoxia in aging rats: changes in proteasomal activity,neuronal apoptosis and spatial function 总被引:7,自引:0,他引:7
Gozal D Row BW Kheirandish L Liu R Guo SZ Qiang F Brittian KR 《Journal of neurochemistry》2003,86(6):1545-1552
Obstructive sleep apnea (OSA) is a frequent medical condition characterized by intermittent hypoxia (IH) during sleep, and is associated with neurodegenerative changes in several brain regions along with learning deficits. We hypothesized that aging rats exposed to IH during sleep would be particularly susceptible. Young (3-4 months) and aging (20-22 months) Sprague-Dawley rats were therefore exposed to either room air or IH for 14 days. Learning and memory was assessed with a standard place-training version of the Morris water maze. Aging rats exposed to room air (RA) or IH displayed significant spatial learning impairments compared with similarly exposed young rats; furthermore, the decrements in performance between RA and IH were markedly greater in aging compared with young rats (p < 0.01), and coincided with the magnitude of IH-induced decreases in cyclic AMP response element binding (CREB) phosphorylation. Furthermore, decreases in proteasomal activity occurred in both young and aging rats exposed to IH, but were substantially greater in the latter (p < 0.001). Neuronal apoptosis, as shown by cleaved caspase 3 expression, was particularly increased in aging rats exposed to IH (p < 0.01 versus young rats exposed to IH). Collectively, these findings indicate unique vulnerability of the aging rodent brain to IH, which is reflected at least in part, by the more prominent decreases in CREB phosphorylation and a marked inability of the ubiquitin-proteasomal pathway to adequately clear degraded proteins. 相似文献