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1.
M. A. L. Smith L. Art Spomer M. J. Meyer M. T. McClelland 《Plant Cell, Tissue and Organ Culture》1989,19(2):91-102
Microcomputerized video image analysis was adapted for rapid, objective, and non-intrusive quantification of shoot growth and development for plants growing in vitro. Custom-developed staging arrangements were essential to insure accurate viewing and representation of the plants in each of three standard culture vessels. Shoot length measurements from digitized culture images were strongly correlated with length measured manually ex vitro. Image analysis weighted density measurements of proliferating microcultures (even with irregular growth habits) provided a reliable indicator of shoot culture fresh weight. Non-destructive time course evaluations of growth rate and quality were demonstrated.Abbreviations FW
fresh weight
- WD
weighted density 相似文献
2.
Two properties of phytotropins, their ability to bind to 1-N-naphthylphthalamic acid (NPA) receptors located on microsomal vesicles isolated from Cucurbita pepo L. hypocotyls, and to stimulate auxin (indol-3-yl acetic acid, IAA) accumulation into such vesicles by blocking its efflux from them, were assessed in double labelling experiments using [2,3,4,5-3H]1-N-naphthylphthalamic acid and 3-indolyl-[2-14C]acetic acid. Two sites of differing affinities and activities on IAA accumulation were found. 1-N-Naphthylphthalamic acid was found to have high affinity (KD at 10-8mol·l-1) for one site and low affinity (KD at 10-6 mol·l-1) for the other, whereas 2-(1-pyrenoyl)benzoic acid displaced NPA with high efficiency (KD below 10-8 mol·l-1) from both sites. Other phytotropins had intermediate affinities for either site. Occupation of the site with low affinity for NPA stimulated auxin accumulation, while occupation of the high-affinity site with a phytotropin did not interfere with auxin accumulation into vesicles.Abbreviations IAA
Indol-3-yl acetic acid
- NPA
1-N-naphthylphthalamic acid
- PBA
2-(1-pyrenoyl)benzoic acid
- TIBA
2,3,5-triiodobenzoic acid
W.M. was supported in part by an allowance from CSIRO and in part by a fellowship of the Deutsche Forschungsgemeinschaft; he acknowledges the friendly hospitality of the CSIRO Division of Plant Industry. The authors thank R. Hertel (Freiburg) for valuable discussion. 相似文献
3.
4.
A combination of enclosure nutrient enrichment experiments and historical data analysis was used to identify the factors controlling
seasonal dynamics and competition of the phytoplankton community in the Curonian lagoon (Southeast Baltic Sea). Experiments
using different nutrient (N, P and Si) manipulations were performed in 10-l enclosures for 48 h. Changes in chlorophyll a concentrations, inorganic nutrient concentrations, and plankton cell density were monitored. Results revealed that phytoplankton
development in the lagoon is strongly affected by ambient physical factors (wind, temperature). Nutrient limitation, however,
also plays an important role in seasonal succession mechanisms showing quite distinct seasonal development patterns. Based
on the data, available phytoplankton seasonal succession in the Curonian lagoon could be described as composed by three phases
corresponding to different domination and regulatory mechanisms. 相似文献
5.
An evolutionary-network model reveals stratified interactions in the V3 loop of the HIV-1 envelope
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The third variable loop (V3) of the human immunodeficiency virus type 1 (HIV-1) envelope is a principal determinant of antibody neutralization and progression to AIDS. Although it is undoubtedly an important target for vaccine research, extensive genetic variation in V3 remains an obstacle to the development of an effective vaccine. Comparative methods that exploit the abundance of sequence data can detect interactions between residues of rapidly evolving proteins such as the HIV-1 envelope, revealing biological constraints on their variability. However, previous studies have relied implicitly on two biologically unrealistic assumptions: (1) that founder effects in the evolutionary history of the sequences can be ignored, and; (2) that statistical associations between residues occur exclusively in pairs. We show that comparative methods that neglect the evolutionary history of extant sequences are susceptible to a high rate of false positives (20%–40%). Therefore, we propose a new method to detect interactions that relaxes both of these assumptions. First, we reconstruct the evolutionary history of extant sequences by maximum likelihood, shifting focus from extant sequence variation to the underlying substitution events. Second, we analyze the joint distribution of substitution events among positions in the sequence as a Bayesian graphical model, in which each branch in the phylogeny is a unit of observation. We perform extensive validation of our models using both simulations and a control case of known interactions in HIV-1 protease, and apply this method to detect interactions within V3 from a sample of 1,154 HIV-1 envelope sequences. Our method greatly reduces the number of false positives due to founder effects, while capturing several higher-order interactions among V3 residues. By mapping these interactions to a structural model of the V3 loop, we find that the loop is stratified into distinct evolutionary clusters. We extend our model to detect interactions between the V3 and C4 domains of the HIV-1 envelope, and account for the uncertainty in mapping substitutions to the tree with a parametric bootstrap. 相似文献
6.
Seo-Jung Han Jae Eun Jung Do Hee Oh Minsup Kim Jae-Min Kim Kyung-Sook Chung Hee-Soo Han Jeong-Hun Lee Kyung-Tae Lee Hee Jin Jeong In Ho Park Eunkyeong Jeon Jeon-Soo Shin Dongkeun Hwang Art E. Cho Duck-Hyung Lee Taebo Sim 《Journal of enzyme inhibition and medicinal chemistry》2022,37(1):1257
Identification of highly selective type II kinase inhibitors is described. Two different chiral peptidomimetic scaffolds were introduced on the tail region of non-selective type II kinase inhibitor GNF-7 to enhance the selectivity. Kinome-wide selectivity profiling analysis showed that type II kinase inhibitor 7a potently inhibited Lck kinase with great selectivity (IC50 of 23.0 nM). It was found that 7a and its derivatives possessed high selectivity for Lck over even structurally conserved all Src family kinases. We also observed that 7a inhibited Lck activation in Jurkat T cells. Moreover, 7a was found to alleviate clinical symptoms in DSS-induced colitis mice. This study provides a novel insight into the design of selective type II kinase inhibitors by adopting chiral peptidomimetic moieties on the tail region. 相似文献
7.
Abdullah Mahboob Serguei Vassiliev Prashanth K. Poddutoori Art van der Est Doug Bruce 《PloS one》2013,8(7)
Photosystem II (PSII) of photosynthesis has the unique ability to photochemically oxidize water. Recently an engineered bacterioferritin photochemical ‘reaction centre’ (BFR-RC) using a zinc chlorin pigment (ZnCe6) in place of its native heme has been shown to photo-oxidize bound manganese ions through a tyrosine residue, thus mimicking two of the key reactions on the electron donor side of PSII. To understand the mechanism of tyrosine oxidation in BFR-RCs, and explore the possibility of water oxidation in such a system we have built an atomic-level model of the BFR-RC using ONIOM methodology. We studied the influence of axial ligands and carboxyl groups on the oxidation potential of ZnCe6 using DFT theory, and finally calculated the shift of the redox potential of ZnCe6 in the BFR-RC protein using the multi-conformational molecular mechanics–Poisson-Boltzmann approach. According to our calculations, the redox potential for the first oxidation of ZnCe6 in the BRF-RC protein is only 0.57 V, too low to oxidize tyrosine. We suggest that the observed tyrosine oxidation in BRF-RC could be driven by the ZnCe6 di-cation. In order to increase the efficiency of tyrosine oxidation, and ultimately oxidize water, the first potential of ZnCe6 would have to attain a value in excess of 0.8 V. We discuss the possibilities for modifying the BFR-RC to achieve this goal. 相似文献
8.
Ying L. Chen Vanessa M. Dunbabin Johannes A. Postma Art J. Diggle Kadambot H. M. Siddique Zed Rengel 《Plant and Soil》2013,372(1-2):319-337
Background & Aims
Searching for root traits underpinning efficient nutrient acquisition has received increased attention in modern breeding programs aimed at improved crop productivity. Root models provide an opportunity to investigate root-soil interactions through representing the relationships between rooting traits and the non-uniform supply of soil resources. This study used simulation modelling to predict and identify phenotypic plasticity, root growth responses and phosphorus (P) use efficiency of contrasting Lupinus angustifolius genotypes to localised soil P in a glasshouse.Methods
Two L. angustifolius genotypes with contrasting root systems were grown in cylindrical columns containing uniform soil with three P treatments (nil and 20 mg P kg?1 either top-dressed or banded) in the glasshouse. Computer simulations were carried out with root architecture model ROOTMAP which was parameterized with root architectural data from an earlier published hydroponic phenotyping study.Results
The experimental and simulated results showed that plants supplied with banded P had the largest root system and the greatest P-uptake efficiency. The P addition significantly stimulated root branching in the topsoil, whereas plants with nil P had relatively deeper roots. Genotype-dependent root growth plasticity in response to P supply was shown, with the greatest response to banded P.Conclusions
Both experimental and simulation outcomes demonstrated that 1) root hairs and root proliferation increased plant P acquisition and were more beneficial in the localised P fertilisation scenario, 2) placing P deeper in the soil might be a more effective fertilisation method with greater P uptake than top dressing, and 3) the combination of P foraging strategies (including root architecture, root hairs and root growth plasticity) is important for efficient P acquisition from a localised source of fertiliser P. 相似文献9.
Cytherella maremensis sp. n., a new ostracod from the Sea of Marmara (Turkey) (Crustacea: Ostracoda)
Cytherella maremensis sp. n., belonging to the family Cytherellidae, is described as new from a hydrothermal vent, located in the west of Marmara Island on the North Anatolian Fault crossing the Sea of Marmara. It was collected from a sediment core 55 m below sea level. Cytherella maremensis sp. n. is clearly separated from closely related species by its shape, length-height ratio and ornamentation. 相似文献
10.
Mariano Avino Garway T. Ng Yiying He Mathias S. Renaud Bradley R. Jones Art F. Y. Poon 《Ecology and evolution》2019,9(12):6756-6771
Cophylogeny is the congruence of phylogenetic relationships between two different groups of organisms due to their long‐term interaction. We investigated the use of tree shape distance measures to quantify the degree of cophylogeny. We implemented a reverse‐time simulation model of pathogen phylogenies within a fixed host tree, given cospeciation probability, host switching, and pathogen speciation rates. We used this model to evaluate 18 distance measures between host and pathogen trees including two kernel distances that we developed for labeled and unlabeled trees, which use branch lengths and accommodate different size trees. Finally, we used these measures to revisit published cophylogenetic studies, where authors described the observed associations as representing a high or low degree of cophylogeny. Our simulations demonstrated that some measures are more informative than others with respect to specific coevolution parameters especially when these did not assume extreme values. For real datasets, trees’ associations projection revealed clustering of high concordance studies suggesting that investigators are describing it in a consistent way. Our results support the hypothesis that measures can be useful for quantifying cophylogeny. This motivates their usage in the field of coevolution and supports the development of simulation‐based methods, i.e., approximate Bayesian computation, to estimate the underlying coevolutionary parameters. 相似文献