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1.
Yuan Wu  Li Guo  Wentao Li  Xihong Cui  Jin Chen 《Plant and Soil》2014,380(1-2):441-444

Introduction

In a recent paper, Tanikawa et al. Plant Soil 373:317–327, (2013) reported a considerable impact of root orientation on the accuracy of root detection and root diameter estimation by ground-penetrating radar (GPR).

Methods

In Tanikawa et al. Plant Soil 373:317–327, (2013), buried root samples in a sand box were scanned from multiple cross angles between root orientation and GPR transecting line under controlled conditions. Changes in radar waveform parameter of roots to different cross angles were investigated.

Results

Tanikawa et al. Plant Soil 373:317–327, (2013) clarified that 1) the variation in amplitude area (a signal strength related waveform parameter) to different cross angles fitted a sinusoidal waveform; and 2) the impact of root orientation on root diameter estimation by GPR could be mathematically corrected by applying a grid transect survey. However, we found that the quantitative relationship established in Tanikawa et al. Plant Soil 373:317–327, (2013) between amplitude area and cross angle was incorrect, and the application of a grid transect survey still underestimated root diameter.

Conclusion

The change in amplitude area to cross angle between transecting line and root orientation fits a sinusoidal waveform but different to that reported in Tanikawa et al. Plant Soil 373:317–327, (2013). The polarization of GPR wave may explain such sinusoidal variation in amplitude area to cross angle. The effect of root orientation on GPR-based root diameter estimation remains to be calibrated.  相似文献   

2.
MYH9 has been proposed as a major genetic risk locus for a spectrum of nondiabetic end stage kidney disease (ESKD). We use recently released sequences from the 1000 Genomes Project to identify two western African-specific missense mutations (S342G and I384M) in the neighboring APOL1 gene, and demonstrate that these are more strongly associated with ESKD than previously reported MYH9 variants. The APOL1 gene product, apolipoprotein L-1, has been studied for its roles in trypanosomal lysis, autophagic cell death, lipid metabolism, as well as vascular and other biological activities. We also show that the distribution of these newly identified APOL1 risk variants in African populations is consistent with the pattern of African ancestry ESKD risk previously attributed to MYH9. Mapping by admixture linkage disequilibrium (MALD) localized an interval on chromosome 22, in a region that includes the MYH9 gene, which was shown to contain African ancestry risk variants associated with certain forms of ESKD (Kao et al. 2008; Kopp et al. 2008). MYH9 encodes nonmuscle myosin heavy chain IIa, a major cytoskeletal nanomotor protein expressed in many cell types, including podocyte cells of the renal glomerulus. Moreover, 39 different coding region mutations in MYH9 have been identified in patients with a group of rare syndromes, collectively termed the Giant Platelet Syndromes, with clear autosomal dominant inheritance, and various clinical manifestations, sometimes also including glomerular pathology and chronic kidney disease (Kopp 2010; Sekine et al. 2010). Accordingly, MYH9 was further explored in these studies as the leading candidate gene responsible for the MALD signal. Dense mapping of MYH9 identified individual single nucleotide polymorphisms (SNPs) and sets of such SNPs grouped as haplotypes that were found to be highly associated with a large and important group of ESKD risk phenotypes, which as a consequence were designated as MYH9-associated nephropathies (Bostrom and Freedman 2010). These included HIV-associated nephropathy (HIVAN), primary nonmonogenic forms of focal segmental glomerulosclerosis, and hypertension affiliated chronic kidney disease not attributed to other etiologies (Bostrom and Freedman 2010). The MYH9 SNP and haplotype associations observed with these forms of ESKD yielded the largest odds ratios (OR) reported to date for the association of common variants with common disease risk (Winkler et al. 2010). Two specific MYH9 variants (rs5750250 of S-haplotype and rs11912763 of F-haplotype) were designated as most strongly predictive on the basis of Receiver Operating Characteristic analysis (Nelson et al. 2010). These MYH9 association studies were then also extended to earlier stage and related kidney disease phenotypes and to population groups with varying degrees of recent African ancestry admixture (Behar et al. 2010; Freedman et al. 2009a, b; Nelson et al. 2010), and led to the expectation of finding a functional African ancestry causative variant within MYH9. However, despite intensive efforts including re-sequencing of the MYH9 gene no suggested functional mutation has been identified (Nelson et al. 2010; Winkler et al. 2010). This led us to re-examine the interval surrounding MYH9 and to the detection of novel missense mutations with predicted functional effects in the neighboring APOL1 gene, which are significantly more associated with ESKD than all previously reported SNPs in MYH9.  相似文献   

3.
Joseph G. Meert 《Evolution》2012,5(4):547-554
During the voyage of the H.M.S. Beagle, Charles Darwin quickly realized that geographic isolation led to significant changes in the adaptation of local flora and fauna (Darwin 1859). Genetic isolation is one of the well-known mechanisms by which adaptation (allopatric speciation) can occur (Palumbi, Annu Rev Ecol Syst 25:547?C72, 1994; Ricklefs, J Avian Biol 33:207?C11, 2002; Burns et al., Evolution 56:1240?C52, 2002; Hendry et al., Science 290:516?C8, 2009). Evolutionary changes can also occur when landmasses converge or are ??bridged.?? An important and relatively recent (Pliocene Epoch) example known as the ??Great American Biotic Interchange?? allowed for the migration of previously isolated species into new ecological niches between North and South America (Webb 1985, Ann Mo Bot Gard 93:245?C57, 2006; Kirby and MacFadden, Palaeogeogr Palaeoclimatol Palaeoecol 228:193?C202, 2005). Geographic isolation (vicariance) or geographic merging (geodispersal) can occur for a variety of reasons (sea level rise, splitting of continents, mountain building). In addition, the growth of a large supercontinent (or breakup) may change the climatic zonation on the globe and form a different type of barrier for species migration. This short review paper focuses on changing paleogeography throughout the Phanerozoic and the close ties between paleogeography and the evolutionary history of life on Earth.  相似文献   

4.
Legionella pneumophila is the primary cause of the legionellosis diseases (90 %) (Yu et al. in J Infect Dis 186:127–128, 2002; Doleans et al. in J Clin Microbiol 42:458–460, 2004; Den Boer et al. in Clin Microbiol Infect 14:459–466, 2008). In this study, methodologies based on molecular biology were developed in order to provide a quick diagnosis of the bacterial presence in water samples of Spain. Multiplex real-time polymerase chain reaction assays were realized to target the 16S rRNA and macrophage infectivity potentiator (mip) genes of, respectively, Legionella spp. and L. pneumophila including in the design of an internal control. The results obtained by the culture and the gene amplification methods agreed in 94.44 % for the 16S rRNA gene, and a concordance of 66.67 % of the cases was obtained for the mip gene.  相似文献   

5.
6.
Following a strategy similar to that used in baker’s yeast (Herrgård et al. Nat Biotechnol 26:1155–1160, 2008). A consensus yeast metabolic network obtained from a community approach to systems biology (Herrgård et al. 2008; Dobson et al. BMC Syst Biol 4:145, 2010). Further developments towards a genome-scale metabolic model of yeast (Dobson et al. 2010; Heavner et al. BMC Syst Biol 6:55, 2012). Yeast 5—an expanded reconstruction of the Saccharomyces cerevisiae metabolic network (Heavner et al. 2012) and in Salmonella typhimurium (Thiele et al. BMC Syst Biol 5:8, 2011). A community effort towards a knowledge-base and mathematical model of the human pathogen Salmonella typhimurium LT2 (Thiele et al. 2011), a recent paper (Thiele et al. Nat Biotechnol 31:419–425, 2013). A community-driven global reconstruction of human metabolism (Thiele et al. 2013) described a much improved ‘community consensus’ reconstruction of the human metabolic network, called Recon 2, and the authors (that include the present ones) have made it freely available via a database at http://humanmetabolism.org/ and in SBML format at Biomodels (http://identifiers.org/biomodels.db/MODEL1109130000). This short analysis summarises the main findings, and suggests some approaches that will be able to exploit the availability of this model to advantage.  相似文献   

7.

Background

Our recent publication (Warren et al., Plant Soil 366:683–693, 2013) described how pulses of deuterium oxide (D2O) or H2O combined with neutron radiography can be used to indicate root water uptake and hydraulic redistribution in maize. This technique depends on the large inherent differences in neutron cross-section between D and H atoms resulting in strong image contrast.

Scope and Conclusions

However, as illustrated by Carminati and Zarebanadkouki (2013) there can be a change in total water content without a change in contrast simply by a change in the relative proportions of D2O and H2O. We agree with their premise and detailed calculations (Zarebanadkouki at al. 2012, 2013), and present further evidence that mixing of D2O and H2O did not confound evidence of hydraulic redistribution in our study.  相似文献   

8.
Alignment is a spontaneous behavioral preference of particular body orientation that may be seen in various vertebrate or invertebrate taxa. Animals often optimize their positions according to diverse directional environmental factors such as wind, stream, slope, sun radiation, etc. Magnetic alignment represents the simplest directional response to the geomagnetic field and a growing body of evidence of animals aligning their body positions according to geomagnetic lines whether at rest or during feedings is accumulating. Recently, with the aid of Google Earth application, evidence of prevailing North–South (N–S) body orientation of cattle on pastures was published (Begall et al. PNAS 105:13451–13455, 2008; Burda et al. PNAS 106:5708–5713, 2009). Nonetheless, a subsequent study from a different laboratory did not confirm this phenomenon (Hert et al. J Comp Physiol A 197:677–682, 2011). The aim of our study was to enlarge the pool of independently gained data on this remarkable animal behavior. By satellite snapshots analysis and using blinded protocol we scored positions of 2,235 individuals in 74 herds. Our results are in line with the original findings of prevailing N–S orientation of grazing cattle. In addition, we found that mutual distances between individual animals within herds (herd density) affect their N–S preference—a new phenomenon giving some insight into biological significance of alignment.  相似文献   

9.
Parotid glands of experimental animals fed a liquid diet are reported to show atrophy (Hall and Schneyer 1964; Wilborn and Schneyer 1970; Hand and Ho 1981; Scott et al. 1990; Scott and Gunn 1991). To clarify whether apoptosis and proliferation of acinar cells participate in atrophy of rat parotid glands induced by liquid diet, rats were fed a liquid diet and compared to pellet-fed controls. Parotid glands were removed at 3, 7, 14 or 21?days, weighed, and examined using transmission electron microscopy (TEM), and studied immunohistochemically for cleaved-caspase-3 (Casp-3), a marker of apoptotic cells, and 5-bromo-2′-deoxyuridine (BrdU), a marker for proliferating cells. Body weights of experimental rats fed liquid diets were not significantly different from controls fed pellet diets; however weights of experimental parotid glands were smaller than those of controls. In the experimental parotid glands, structures like apoptotic bodies were histologically observed in acini at each time point; more Casp-3-positive acinar cells were identified in experimental parotid glands than in the controls on days 3, 7, and 14. Experimental glands showed fewer BrdU-positive acinar cells at each time point. TEM confirmed typical apoptotic acinar cells in the atrophic glands. These findings suggest that increased acinar cell apoptosis and reduced acinar cell proliferation occur in atrophic parotid glands of rats fed a liquid diet.  相似文献   

10.
An efficient semi-automated strategy called PFBD (i.e. Protein Fold from Backbone Data only) has been presented for rapid backbone fold determination of small proteins. It makes use of NMR parameters involving backbone atoms only. These include chemical shifts, amide?Camide NOEs and H-bonds. The backbone chemical shifts are obtained in an automated manner from the orthogonal 2D projections of variants of HNN and HN(C)N experiments (Kumar et al., in Magn Reson Chem 50(5):357?C363, 2012) using AUTOBA (Borkar et al. in J Biomol NMR 50(3):285?C297, 2011); backbone H-bonds are manually derived from constant time long-range 2D-HnCO spectrum (Cordier and Grzesiek in J Am Chem Soc 121:1601?C1602, 1999); and amide?Camide NOEs are derived from 3D HNCO NOESY experiment which provides NOEs along the direct 1H dimension that has maximum resolution (Lohr and Ruterjans in J Biomol NMR 9(1):371?C388, 1997). All the experiments needed for the execution of PFBD can be recorded and analyzed in about 24?C48?h depending upon the concentration of the protein and dispersion of amide cross-peaks in the 1H?C15N correlation spectrum. Thus, we believe that the strategy, because of its speed and simplicity will be very valuable in Biomolecular NMR community for high-throughput structural proteomics of small folded proteins of MW?<?10?C12?kDa, the regime where NMR is generally preferred over X-ray crystallography. The strategy has been validated and demonstrated here on two small globular proteins: human ubiquitin (76 aa) and chicken SH3 domain (62 aa).  相似文献   

11.
Strigolactones have recently been identified as the long sought-after signal required to inhibit shoot branching (Gomez-Roldan et al. 2008; Umehara et al. 2008; reviewed in Dun et al. 2009). Here we briefly describe the evidence for strigolactone inhibition of shoot branching and, more extensively, the broader context of this action. We address the central question of why strigolactone mutants exhibit a varied branching phenotype across a wide range of experimental conditions. Where knowledge is available, we highlight the role of other hormones in dictating these phenotypes and describe those instances where our knowledge of known plant hormones and their interactions falls considerably short of explaining the phenotypes. This review will focus on bud outgrowth in herbaceous species because knowledge on the role of strigolactones in shoot branching to date barely extends beyond this group of plants.  相似文献   

12.
Invasive species can have complex invasion histories, harbor cryptic levels of diversity, and pose taxonomic problems for pest management authorities. Roof rats, Rattus rattus sensu lato, are common invasive pests of the San Francisco Bay Area in California, USA. They are a significant health risk and pest management efforts impose a large financial investment from public institutions and private individuals. Recent molecular genetic and taxonomic studies of black rats in their native range in Asia have shown that the species is a complex of two karyotypic forms and four mitochondrial genetic lineages that may represent four distinct species. We used mtDNA sequences and nuclear microsatellite variation to identify which mitochondrial lineages of the R. rattus group are present in the San Francisco Bay Area and to test for gene flow among them. We recovered specimens with mtDNA sequences representing two of the major mtDNA lineages of the R. rattus group. Microsatellite variation, however, was not structured in concordance with mtDNA lineages, suggesting a more complex history involving hybridization and introgression between these lineages. Although Aplin et al. (2011) and Lack et al. (2012) reported R. rattus Lineage II in North America, this is the first detailed examination of possible gene flow amongst lineages in this region.  相似文献   

13.
Displaced starburst amacrine cells (SACs) are retinal interneurons that exhibit GABA A receptor-mediated and Cl ? cotransporter-mediated, directionally selective (DS) light responses in the rabbit retina. They depolarize to stimuli that move centrifugally through the receptive field surround and hyperpolarize to stimuli that move centripetally through the surround (Gavrikov et al, PNAS 100(26):16047–16052, 2003, PNAS 103(49):18793–18798, 2006). They also play a key role in the activity of DS ganglion cells (DS GC; Amthor et al, Vis Neurosci 19:495–509 2002; Euler et al, Nature 418:845–852, 2002; Fried et al, Nature 420:411– 414, 2002; Gavrikov et al, PNAS 100(26):16047–16052, 2003, PNAS 103(49):18793–18798, 2006; Lee and Zhou, Neuron 51:787–799 2006; Yoshida et al, Neuron 30:771–780, 2001). In this paper we present a model of strong DS behavior of SACs which relies on the GABA-mediated communication within a tightly interconnected network of these cells and on the glutamate signal that the SACs receive from bipolar cells (a presynaptic cell that receives input from cones). We describe how a moving light stimulus can produce a large, sustained depolarization of the SAC dendritic tips that point in the direction that the stimulus moves (i.e., centrifugal motion), but produce a minimal depolarization of the dendritic tips that point in the opposite direction (i.e., centripetal motion). This DS behavior, which is quantified based on the relative size and duration of the depolarizations evoked by stimulus motion at dendritic tips pointing in opposite directions, is robust to changes of many different parameter values and consistent with experimental data. In addition, the DS behavior is strengthened under the assumptions that the Cl? cotransporters Na?+?-K?+?-Cl?? and K?+?-Cl?? are located in different regions of the SAC dendritic tree (Gavrikov et al, PNAS 103(49):18793–18798, 2006) and that GABA evokes a long-lasting response (Gavrikov et al, PNAS 100(26):16047–16052, 2003, PNAS 103(49):18793–18798, 2006; Lee and Zhou, Neuron 51:787–799, 2006). A possible mechanism is discussed based on the generation of waves of local glutamate and GABA secretion, and their postsynaptic interplay as the waves travel between cell compartments.  相似文献   

14.
Block (Trends Cogn Sci 7:285–286, 2003) and Prinz (PSYCHE 12:1–19, 2006) have defended the idea that SSD perception remains in the substituting modality (auditory or tactile). Hurley and Noë (Biol Philos 18:131–168, 2003) instead argued that after substantial training with the device, the perceptual experience that the SSD user enjoys undergoes a change, switching from tactile/auditory to visual. This debate has unfolded in something like a stalemate where, I will argue, it has become difficult to determine whether the perception acquired through the coupling with an SSD remains in the substituting or the substituted modality. Within this puzzling deadlock two new approaches have been recently suggested. Ward and Meijer (Conscious Cogn 19:492–500, 2010) describe SSD perception as visual-like but characterize it as a kind of artificially induced synaesthesia. Auvray et al. (Perception 36:416–430, 2007) and Auvray and Myin (Cogn Sci 33:1036–1058, 2009) suggest that SSDs let their users experience a new kind of perception. Deroy and Auvray (forthcoming) refine this position, and argue that this new kind of perception depends on pre-existing senses without entirely aligning with any of them. So, they have talked about perceptual experience in SSDs as going "beyond vision". In a similar vein, MacPherson (Oxford University Press, New York, 2011a) claims that “if the subjects (SSD users) have experiences with both vision-like and touch-like representational characteristics then perhaps they have a sense that ordinary humans do not” (MacPherson in Oxford University Press, New York, 2011a, p. 139).  相似文献   

15.
Since the publication of our first paper on the microwave-accelerated metal-enhanced fluorescence (MAMEF) bioassay platform technology in 2005 (Aslan and Geddes, Anal Chem 77:8057–8067, 2005), we have been repeatedly asked to comment on the advantages of “microwave heating” with plasmonic nanostructures over conventional heating for bioassays by many of our colleagues in the community. We note that one can find a couple of review articles, one by Mingos (Gabriel et al., Chem Soc Rev 27:213–223, 1998) and another by Thostenson and Chou (Manufacturing 30:1055–1071, 1999), summarizing the fundamentals and several applications of microwave processing of chemical compounds and composite materials, respectively. These review articles also present a direct comparison of microwave heating with conventional heating with respect to the processing of materials and microwave-assisted synthesis of chemical compounds. In this review article, we seek to remind the reader of the fundamentals of microwave heating and the interactions of microwaves with chemical and biological materials relevant to our recent work on bioassays, rather than repeating the information provided in the above-mentioned very informative reviews. We also summarize our work on MAMEF-based bioassays where we use plasmonic nanostructures to additionally plasmon-enhance fluorescence signatures.  相似文献   

16.
Sensory neurons in vertebrates are derived from two embryonic transient cell sources: neural crest (NC) and ectodermal placodes. The placodes are thickenings of ectodermal tissue that are responsible for the formation of cranial ganglia as well as complex sensory organs that include the lens, inner ear, and olfactory epithelium. The NC cells have been indicated to arise at the edges of the neural plate/dorsal neural tube, from both the neural plate and the epidermis in response to reciprocal interactions Moury and Jacobson (Dev Biol 141:243?C253, 1990). NC cells migrate throughout the organism and give rise to a multitude of cell types that include melanocytes, cartilage and connective tissue of the head, components of the cranial nerves, the dorsal root ganglia, and Schwann cells. The embryonic definition of these two transient populations and their relative contribution to the formation of sensory organs has been investigated and debated for several decades (Basch and Bronner-Fraser, Adv Exp Med Biol 589:24?C31, 2006; Basch et al., Nature 441:218?C222, 2006) review (Baker and Bronner-Fraser, Dev Biol 232:1?C61, 2001). Historically, all placodes have been described as exclusively derived from non-neural ectodermal progenitors. Recent genetic fate-mapping studies suggested a NC contribution to the olfactory placodes (OP) as well as the otic (auditory) placodes in rodents (Murdoch and Roskams, J Neurosci Off J Soc Neurosci 28:4271?C4282, 2008; Murdoch et al., J Neurosci 30:9523?C9532, 2010; Forni et al., J Neurosci Off J Soc Neurosci 31:6915?C6927, 2011b; Freyer et al., Development 138:5403?C5414, 2011; Katoh et al., Mol Brain 4:34, 2011). This review analyzes and discusses some recent developmental studies on the OP, placodal derivatives, and olfactory system.  相似文献   

17.
This is an article on the peroxydicarbonic acid (PODCA) hypothesis of photosynthetic water oxidation, which follows our first article in this general area (Castelfranco et al., Photosynth Res 94:235–246, 2007). In this article I have expanded on the idea of a protein-bound intermediate containing inorganic carbon in some chemically bound form. PODCA is conceived in this article as constituting a bridge between two proteins of the oxygen-evolving complex (OEC) that are essential for the evolution of O2. Presumably, these are two proteins which have been shown to possess Mn-dependent carbonic anhydrase activity (Lu et al., Plant Cell Physiol 46:1944–1953, 2005; Shitov et al., Biochemistry (Moscow) 74:509–517, 2009). One of these proteins may be the DI of the OEC core and the other may be the PsbO extrinsic protein. I attempt to relate briefly the PODCA hypothesis to the role of two cofactors for O2 evolution: Ca2+ and inorganic carbon. In this scheme, inorganic carbon (HCO3 ?) mediates the oxidation of peroxide to dioxygen, thus avoiding the homolytic cleavage of the peroxide into two free radicals. I visualize the role of Ca2+ in the binding of PODCA to two essential photosystem II proteins. I propose that PODCA alternates between two Phases. In Phase 1, PODCA is broken down with the production of O2. In Phase 2, PODCA is regenerated.  相似文献   

18.

Purpose

This article discusses the choice of stakeholder categories and the integration of stakeholders into participatory processes to define impact categories and select indicators.

Methods

We undertook a literature review concerning the roles and the importance of stakeholders in participatory processes, and the use of such processes in environmental and social LCAs (Biswas et al. Int J Life Cycle Assess 3(4):184-190, 1998; Sonnemann et al. Int J Life Cycle Assess 6(6):325-333, 2001; Baldo Int J Life Cycle Assess 7(5):269-275, 2002; James et al. Int J Life Cycle Assess 7(3):151-157, 2002; Bras-Kapwijk Int J Life Cycle Assess 8(5):266-272, 2003; Mettier et al. Int J Life Cycle Assess 11(6):468-476, 2006). As part of the French National Research Agency Piscenlit project, we adapted the Principle, Criteria, Indicator (PCI) method (Rey-Valette et al. 2008), which is an assessment method of sustainable development, as a way to integrate the participatory approach into Social Life Cycle Assessment (SLCA) methodology, mainly at the impact definition stage.

Results and discussion

Different views of participation were found in the literature; there is no consensual normative approach for the implication of stakeholders in LCA development. Some attempts have been made to integrate stakeholders into environmental LCAs but these attempts have not been generalized. However, they strongly emphasize the interrelationship between research on the growing integration of stakeholders and on the choice of stakeholders. We then propose criteria from stakeholder theory (Freeman 1984; Mitchell et al. Acad Manage Rev 22(4):853-886, 1997; Geibler et al. Bus Strat Environ 15:334-346, 2006) in order to identify relevant stakeholders for SLCA participatory approach. The adaptation of the PCI method to Principles, Impacts, and Indicators (PII) enables stakeholders to express themselves and hence leads to definitions of relevant social indicators that they can appropriate. The paper presents results regarding the selection of stakeholders but no specific results regarding the choice of impact categories and indicators.

Conclusions and recommendations

Integrating a participatory approach into SLCAs is of interest at several levels. It enables various factors to be taken into account: plurality of stakeholder interests, local knowledge, and impact categories that make sense for stakeholders in different contexts. It also promotes dialogue and simplifies the search for indicators. However, it requires a multidisciplinary approach and the integration of new knowledge and skills for the SLCA practitioners.  相似文献   

19.
Cyclophilins catalyze the reversible peptidyl-prolyl isomerization of their substrates and are present across all kingdoms of life from humans to bacteria. Although numerous biological roles have now been discovered for cyclophilins, their function was initially ascribed to their chaperone-like activity in protein folding where they catalyze the often rate-limiting step of proline isomerization. This chaperone-like activity may be especially important under extreme conditions where cyclophilins are often over expressed, such as in tumors for human cyclophilins (Lee Archiv Pharm Res 33(2): 181–187, 2010), but also in organisms that thrive under extreme conditions, such as theromophilic bacteria. Moreover, the reversible nature of the peptidyl-prolyl isomerization reaction catalyzed by cyclophilins has allowed these enzymes to serve as model systems for probing the role of conformational changes during catalytic turnover (Eisenmesser et al. Science 295(5559): 1520–1523, 2002; Eisenmesser et al. Nature 438(7064): 117–121, 2005). Thus, we present here the resonance assignments of a thermophilic cyclophilin from Geobacillus kaustophilus derived from deep-sea sediment (Takami et al. Extremophiles 8(5): 351–356, 2004). This thermophilic cyclophilin may now be studied at a variety of temperatures to provide insight into the comparative structure, dynamics, and catalytic mechanism of cyclophilins.  相似文献   

20.
The development of new anti-neoplastic drugs is a key issue for cancer chemotherapy due to the reality that, most likely, certain cancer cells are resistant to current chemotherapy. The past two decades have witnessed tremendous advances in our understanding of the pathogenesis of cancer. These advances have allowed identification new targets as oncogenes, tumor supressor genes and the possible implication of the mitochondria (Fulda et al. Nat Rev Drug Discov 9:447–464, 2010). Annonaceous Acetogenins (ACGs) have been described as the most potent inhibitors of the respiratory chain because of their interaction with mitochondrial Complex I (Degli Esposti and Ghelli Biochim Biophys Acta 1187:116–120, 1994; Zafra-Polo et al. Phytochemistry 42:253–271, 1996; Miyoshi et al. Biochim Biophys Acta 1365:443–452, 1998; Tormo et al. Arch Biochem Biophys 369:119–126, 1999; Motoyama et al. Bioorg Med Chem Lett 12:2089–2092, 2002). To explore a possible application of natural products from Annonaceous plants to cancer treatment, we have selected four bis-tetrahydrofuranic ACGs, three from Annona cherimolia (cherimolin-1, motrilin and laherradurin) and one from Rollinia mucosa (rollinianstatin-1) in order to fully describe their mechanisms responsible within the cell (Fig. 1). In this study, using a hepato-carcinoma cell line (HepG2) as a model, we showed that the bis-THF ACGs caused cell death through the induction of the apoptotic mitochondrial pathway. Their potency and behavior were compared with the classical mitochondrial respiratory chain Complex I inhibitor rotenone in every apoptotic pathway step.
Fig. 1
ACGs structures  相似文献   

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