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Mokkonen M Kokko H Koskela E Lehtonen J Mappes T Martiskainen H Mills SC 《Science (New York, N.Y.)》2011,334(6058):972-974
Sexually antagonistic genetic variation, where optimal values of traits are sex-dependent, is known to slow the loss of genetic variance associated with directional selection on fitness-related traits. However, sexual antagonism alone is not sufficient to maintain variation indefinitely. Selection of rare forms within the sexes can help to conserve genotypic diversity. We combined theoretical models and a field experiment with Myodes glareolus to show that negative frequency-dependent selection on male dominance maintains variation in sexually antagonistic alleles. In our experiment, high-dominance male bank voles were found to have low-fecundity sisters, and vice versa. These results show that investigations of sexually antagonistic traits should take into account the effects of social interactions on the interplay between ecology and evolution, and that investigations of genetic variation should not be conducted solely under laboratory conditions. 相似文献
114.
Karpova NN Pickenhagen A Lindholm J Tiraboschi E Kulesskaya N Agústsdóttir A Antila H Popova D Akamine Y Bahi A Sullivan R Hen R Drew LJ Castrén E 《Science (New York, N.Y.)》2011,334(6063):1731-1734
Antidepressant drugs and psychotherapy combined are more effective in treating mood disorders than either treatment alone, but the neurobiological basis of this interaction is unknown. To investigate how antidepressants influence the response of mood-related systems to behavioral experience, we used a fear-conditioning and extinction paradigm in mice. Combining extinction training with chronic fluoxetine, but neither treatment alone, induced an enduring loss of conditioned fear memory in adult animals. Fluoxetine treatment increased synaptic plasticity, converted the fear memory circuitry to a more immature state, and acted through local brain-derived neurotrophic factor. Fluoxetine-induced plasticity may allow fear erasure by extinction-guided remodeling of the memory circuitry. Thus, the pharmacological effects of antidepressants need to be combined with psychological rehabilitation to reorganize networks rendered more plastic by the drug treatment. 相似文献
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Tainor Tisotti Alexander Valverde Ashley Hopkins M. Lynne O’Sullivan Brad Hanna Luis Arroyo 《Veterinary anaesthesia and analgesia》2021,48(2):174-186
ObjectiveTo assess cardiopulmonary function in sedated and anesthetized dogs administered intravenous (IV) dexmedetomidine and subsequently administered IV lidocaine to treat dexmedetomidine-induced bradycardia.Study designProspective, randomized, crossover experimental trial.AnimalsA total of six purpose-bred female Beagle dogs, weighing 9.1 ± 0.6 kg (mean ± standard deviation).MethodsDogs were randomly assigned to one of three treatments: dexmedetomidine (10 μg kg–1 IV) administered to conscious (treatments SED1 and SED2) or isoflurane-anesthetized dogs (end-tidal isoflurane concentration 1.19 ± 0.04%; treatment ISO). After 30 minutes, a lidocaine bolus (2 mg kg–1) IV was administered in treatments SED1 and ISO, followed 20 minutes later by a second bolus (2 mg kg–1) and a 30 minute lidocaine constant rate infusion (L-CRI) at 50 (SED1) or 100 μg kg–1 minute–1 (ISO). In SED2, lidocaine bolus and L-CRI (50 μg kg–1 minute–1) were administered 5 minutes after dexmedetomidine. Cardiopulmonary measurements were obtained after dexmedetomidine, after lidocaine bolus, during L-CRI and 30 minutes after discontinuing L-CRI. A mixed linear model was used for comparisons within treatments (p < 0.05).ResultsWhen administered after a bolus of dexmedetomidine, lidocaine bolus and L-CRI significantly increased heart rate and cardiac index, decreased mean blood pressure, systemic vascular resistance index and oxygen extraction ratio, and did not affect stroke volume index in all treatments.Conclusion and clinical relevanceLidocaine was an effective treatment for dexmedetomidine-induced bradycardia in healthy research dogs. 相似文献
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Pine Kraft-AQ pulp was bleached with hydrogen peroxide catalyzed by [LMn(IV)(2) (mu-O)(3)](ClO(4))(2) at 80 degrees C for 120 min under optimum reaction conditions. The resulting bleached pulp was hydrolyzed with cellulase to obtain insoluble and soluble residual lignins. The alkaline effluent from the bleaching was acidified to precipitate alkaline soluble lignin. These lignin preparations were purified, and then analyzed by 2D HMQC NMR spectroscopic techniques. The results showed that biphenyl (5-5) and stilbene structures are preferentially degraded in the bleaching process, while beta-O-4, beta-5, and beta-beta structures undergo degradation only to a lesser extent. This implies that hydrogen peroxide bleaching using the catalyst is more effective in delignification of softwood pulps than hardwood pulps. The possible reaction mechanisms for the delignification of residual lignin in the pine Kraft-AQ pulp in the bleaching process are discussed on the basis of the 2D HMQC NMR spectroscopic data and the model compound experiments. 相似文献
118.
G M Hanna C A Lau-Cam 《Journal of the Association of Official Analytical Chemists》1989,72(4):552-555
Optimum experimental conditions were developed for determination of the optical purity of samples of tranylcypromine sulfate by proton magnetic resonance spectroscopy after complexation with the chiral lanthanide chelate Eu(hfc)3. At a substrate concentration of 0.25M (0.125M as sulfate) in CDCl3 and an Eu(hfc)3 to substrate molar ratio of 1, the methine proton geminal to the amino group in the cyclopropane ring showed the largest induced shift and largest enantiomeric induced shift difference. From the relative intensities of the resolved (+)-CH-NH2 protons (15.77 ppm) and (-)-CH-NH2 proton (16.04 ppm), the enantiomeric purity and percentage compositions were readily calculated. The mean +/- SD recovery of (+)-tranylcypromine sulfate from synthetic enantiomeric mixtures was 101.02 +/- 2.59 (n = 6). 相似文献
119.
John.W.Peterson PE 《中国水土保持》2002,(7)
对美国土壤侵蚀的历史及其后果的研究十分有意义。自美国殖民时期和 1 8世纪建国开始 ,有许多文献表明 ,最早期的殖民者已明了由于人们耕种土地产生的土壤侵蚀所引发的问题 ,也有意做点什么来减少土壤侵蚀。 1 86 1年各州之间发生战争 ,有记录表明 ,河流被来自管理不善的农田的泥沙淤塞。由于认为土地资源取之不尽 ,当时的农民常常是当农地变得无法耕种时 ,就打起行装向西部新的土地转移。然而很快当全国从东海岸到西海岸都居住有人后 ,这种做法就行不通了。2 0世纪 30年代的大平原“沙尘暴”及随之而来的美国经济大萧条 ,为罗斯福政府创造… 相似文献
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Hanna Jaworska Halina Dąbkowska-Naskręt Mirosław Kobierski 《Journal of Soils and Sediments》2016,16(2):396-404