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951.
Soil nutrient budgets following projected corn stover harvest for biofuel production in the conterminous United States
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Increasing demand for food and biofuel feedstocks may substantially affect soil nutrient budgets, especially in the United States where there is great potential for corn (Zea mays L) stover as a biofuel feedstock. This study was designed to evaluate impacts of projected stover harvest scenarios on budgets of soil nitrogen (N), phosphorus (P), and potassium (K) currently and in the future across the conterminous United States. The required and removed N, P, and K amounts under each scenario were estimated on the basis of both their average contents in grain and stover and from an empirical model. Our analyses indicate a small depletion of soil N (?4 ± 35 kg ha?1) and K (?6 ± 36 kg ha?1) and a moderate surplus of P (37 ± 21 kg ha?1) currently on the national average, but with a noticeable variation from state to state. After harvesting both grain and projected stover, the deficits of soil N, P, and K were estimated at 114–127, 26–27, and 36–53 kg ha?1 yr?1, respectively, in 2006–2010; 131–173, 29–32, and 41–96 kg ha?1 yr?1, respectively, in 2020; and 161–207, 35–39, and 51–111 kg ha?1 yr?1, respectively, in 2050. This study indicates that the harvestable stover amount derived from the minimum stover requirement for maintaining soil organic carbon level scenarios under current fertilization rates can be sustainable for soil nutrient supply and corn production at present, but the deficit of P and K at the national scale would become larger in the future. 相似文献
952.
A novel and highly sensitive chemiluminescence (CL) method for the determination of ethanol was developed based on the CdS quantum dots (QDs)–permanganate system. It was found that KMnO4 could directly oxidize CdS QDs in acidic media resulting in relatively high CL emission. A possible mechanism was proposed for this reaction based on UV/Vis absorption, fluorescence and the generated CL emission spectra. However, it was observed that ethanol had a remarkable inhibition effect on this system. This effect was exploited in the determination of ethanol within the concentration range 12–300 µg/L, with detection at 4.3 µg/L. In order to evaluate the capability of presented method, it was satisfactorily utilized in the determination of alcohol in real samples. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
953.
Yao-An Shen Chia-Yu Wang Yi-Tao Hsieh Yann-Jang Chen Yau-Huei Wei 《Cell cycle (Georgetown, Tex.)》2015,14(1):86-98
Cancer stem cells (CSCs) represent a subpopulation of tumor cells endowed with
self-renewal capacity and are considered as an underlying cause of tumor recurrence and
metastasis. The metabolic signatures of CSCs and the mechanisms involved in the regulation
of their stem cell-like properties still remain elusive. We utilized nasopharyngeal
carcinoma (NPC) CSCs as a model to dissect their metabolic signatures and found that CSCs
underwent metabolic shift and mitochondrial resetting distinguished from their
differentiated counterparts. In metabolic shift, CSCs showed a greater reliance on
glycolysis for energy supply compared with the parental cells. In mitochondrial resetting,
the quantity and function of mitochondria of CSCs were modulated by the biogenesis of the
organelles, and the round-shaped mitochondria were distributed in a peri-nuclear manner
similar to those seen in the stem cells. In addition, we blocked the glycolytic pathway,
increased the ROS levels, and depolarized mitochondrial membranes of CSCs, respectively,
and examined the effects of these metabolic factors on CSC properties. Intriguingly, the
properties of CSCs were curbed when we redirected the quintessential metabolic
reprogramming, which indicates that the plasticity of energy metabolism regulated the
balance between acquisition and loss of the stemness status. Taken together, we suggest
that metabolic reprogramming is critical for CSCs to sustain self-renewal, deter from
differentiation and enhance the antioxidant defense mechanism. Characterization of
metabolic reprogramming governing CSC properties is paramount to the design of novel
therapeutic strategies through metabolic intervention of CSCs. 相似文献
954.
Lucia Polletta Enza Vernucci Ilaria Carnevale Tania Arcangeli Dante Rotili Silvia Palmerio Clemens Steegborn Theresa Nowak Mike Schutkowski Laura Pellegrini Luigi Sansone Lidia Villanova Alessandra Runci Bruna Pucci Emanuela Morgante Massimo Fini Antonello Mai Matteo A Russo Marco Tafani 《Autophagy》2015,11(2):253-270
In liver the mitochondrial sirtuin, SIRT5, controls ammonia detoxification by regulating CPS1, the first enzyme of the urea cycle. However, while SIRT5 is ubiquitously expressed, urea cycle and CPS1 are only present in the liver and, to a minor extent, in the kidney. To address the possibility that SIRT5 is involved in ammonia production also in nonliver cells, clones of human breast cancer cell lines MDA-MB-231 and mouse myoblast C2C12, overexpressing or silenced for SIRT5 were produced. Our results show that ammonia production increased in SIRT5-silenced and decreased in SIRT5-overexpressing cells. We also obtained the same ammonia increase when using a new specific inhibitor of SIRT5 called MC3482. SIRT5 regulates ammonia production by controlling glutamine metabolism. In fact, in the mitochondria, glutamine is transformed in glutamate by the enzyme glutaminase, a reaction producing ammonia. We found that SIRT5 and glutaminase coimmunoprecipitated and that SIRT5 inhibition resulted in an increased succinylation of glutaminase. We next determined that autophagy and mitophagy were increased by ammonia by measuring autophagic proteolysis of long-lived proteins, increase of autophagy markers MAP1LC3B, GABARAP, and GABARAPL2, mitophagy markers BNIP3 and the PINK1-PARK2 system as well as mitochondrial morphology and dynamics. We observed that autophagy and mitophagy increased in SIRT5-silenced cells and in WT cells treated with MC3482 and decreased in SIRT5-overexpressing cells. Moreover, glutaminase inhibition or glutamine withdrawal completely prevented autophagy. In conclusion we propose that the role of SIRT5 in nonliver cells is to regulate ammonia production and ammonia-induced autophagy by regulating glutamine metabolism. 相似文献
955.
956.
The kinetics and nonequilibrium thermodynamics of open state and inactive state drug binding mechanisms have been studied here using different voltage protocols in sodium ion channel. We have found that for constant voltage protocol, open state block is more efficient in blocking ionic current than inactive state block. Kinetic effect comes through peak current for mexiletine as an open state blocker and in the tail part for lidocaine as an inactive state blocker. Although the inactivation of sodium channel is a free energy driven process, however, the two different kinds of drug affect the inactivation process in a different way as seen from thermodynamic analysis. In presence of open state drug block, the process initially for a long time remains entropy driven and then becomes free energy driven. However in presence of inactive state block, the process remains entirely entropy driven until the equilibrium is attained. For oscillating voltage protocol, the inactive state blocking is more efficient in damping the oscillation of ionic current. From the pulse train analysis it is found that inactive state blocking is less effective in restoring normal repolarisation and blocks peak ionic current. Pulse train protocol also shows that all the inactive states behave differently as one inactive state responds instantly to the test pulse in an opposite manner from the other two states. 相似文献
957.
The delivery of Ca2+ into cells by CaV channels provides the trigger for many cellular actions, such as cardiac muscle contraction and neurotransmitter release. Thus, a full understanding of Ca2+ permeation through these channels is critical. Using whole-cell voltage-clamp recordings, we recently demonstrated that voltage modulates the apparent affinity of N-type (CaV2.2) channels for permeating Ca2+ and Ba2+ ions. While we took many steps to ensure the high fidelity of our recordings, problems can occur when CaV currents become large and fast, or when currents run down. Thus, we use here single channel recordings to further test the hypothesis that permeating ions interact with N-type channels in a voltage-dependent manner. We also examined L-type (CaV1.2) channels to determine if these channels also exhibit voltage-dependent permeation. Like our whole-cell data, we find that voltage modulates N-channel affinity for Ba2+ at voltages > 0 mV, but has little or no effect at voltages < 0 mV. Furthermore, we demonstrate that permeation through L-channel is also modulated by voltage. Thus, voltage-dependence may be a common feature of divalent cation permeation through CaV1 and CaV2 channels (i.e. high-voltage activated CaV channels). The voltage dependence of CaV1 channel permeation is likely a mechanism mediating sustained Ca2+ influx during the plateau phase of the cardiac action potential. 相似文献
958.
Zongyun Chen Youtian Hu Bin Wang Zhijian Cao Wenxin Li Yingliang Wu 《Biochemistry and Biophysics Reports》2015
Although many studies concerning the sensitivity mechanism of scorpion toxin-potassium channel interactions have been reported, few have explored the biochemical insensitivity mechanisms of potassium channel receptors toward natural scorpion toxin peptides, such as the KCNQ1 channel. Here, by sequence alignment analyses of the human KCNQ1 channel and scorpion potassium channel MmKv2, which is completely insensitive to scorpion toxins, we proposed that the insensitivity mechanism of KCNQ1 toward natural scorpion toxins might involve two functional regions, the turret and filter regions. Based on this observation, a series of KCNQ1 mutants were constructed to study molecular mechanisms of the KCNQ1 channel insensitivity toward natural scorpion toxins. Electrophysiological studies of chimera channels showed that the channel filter region controls KCNQ1 insensitivity toward the classical scorpion toxin ChTX. Interestingly, further residue mutant experiments showed that a single basic residue in the filter region determined the insensitivity of KCNQ1 channels toward scorpion toxins. Our present work showed that amino acid residue diversification at common sites controls the sensitivity and insensitivity of potassium channels toward scorpion toxins. The unique insensitivity mechanism of KCNQ1 toward natural scorpion toxins will accelerate the rational design of potent peptide inhibitors toward this channel. 相似文献
959.
Mengting Ke Guangzhen He Huawei Wang Siyuan Cheng Yancheng Xu 《Experimental biology and medicine (Maywood, N.J.)》2021,246(13):1491
Sigma-1 receptor (Sig-1R) is located in the endoplasmic reticulum (ER) and clustered on the mitochondria related endoplasmic membranes, which are involved in the regulation of nervous system disease. Here, we designed Sig-1R silence MIN6 cells and studied the influence of Sig-1R silence on beta cells. We showed Sig-1R inactivation in MIN6 cells could not only decrease cell proliferation but also inhibit cell cycle, and this inhibitory effect on cell cycle might be achieved by regulating the FoxM1/Plk1/Cenpa pathway. Moreover, Sig-1R deficiency increased MIN6 cells sensitivity to lipotoxicity, exaggerated palmitate (PA)-induced apoptosis, and impaired insulin secretion. On the other hand, ER chaperone GRP78 and ER proapoptotic molecules CHOP increased in Sig-1R knockdown MIN6 cells. The ATP level decreased and reactive oxygen species (ROS) increased in this kind of cells. Furthermore not only GRP78 and CHOP levels, but also ATP and ROS levels changed more in Sig-1R silence cells after cultured with PA. Therefore, Sig-1R deficiency exaggerated PA induced beta cells apoptosis by aggravating ER stress and mitochondrial dysfunction. Together, our study showed that Sig-1R might influence the proliferation, apoptosis, and function of beta cells. 相似文献
960.
David Glenn Smith Jillian Ng Debra George Jessica Satkoski Trask Paul Houghton Balbir Singh Jason Villano Sreetharan Kanthaswamy 《American journal of physical anthropology》2014,155(1):136-148
Two subspecies of cynomolgus macaques (Macaca fascicularis) are alleged to co‐exist in the Philippines, M. f. philippensis in the north and M. f. fascicularis in the south. However, genetic differences between the cynomolgus macaques in the two regions have never been studied to document the propriety of their subspecies status. We genotyped samples of cynomolgus macaques from Batangas in southwestern Luzon and Zamboanga in southwestern Mindanao for 15 short tandem repeat (STR) loci and sequenced an 835 bp fragment of the mtDNA of these animals. The STR genotypes were compared with those of cynomolgus macaques from southern Sumatra, Singapore, Mauritius and Cambodia, and the mtDNA sequences of both Philippine populations were compared with those of cynomolgus macaques from southern Sumatra, Indonesia and Sarawak, Malaysia. We conducted STRUCTURE and PCA analyses based on the STRs and constructed a median joining network based on the mtDNA sequences. The Philippine population from Batangas exhibited much less genetic diversity and greater genetic divergence from all other populations, including the Philippine population from Zamboanga. Sequences from both Batangas and Zamboanga were most closely related to two different mtDNA haplotypes from Sarawak from which they are apparently derived. Those from Zamboanga were more recently derived than those from Batangas, consistent with their later arrival in the Philippines. However, clustering analyses do not support a sufficient genetic distinction of cynomolgus macaques from Batangas from other regional populations assigned to subspecies M. f. fascicularis to warrant the subspecies distinction M. f. philippensis. Am J Phys Anthropol 155:136–148, 2014. © 2014 Wiley Periodicals, Inc. 相似文献