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1.
Behav Sci (Basel) ; 14(1)2024 Jan 05.
Article in English | MEDLINE | ID: mdl-38247688

ABSTRACT

Implicit learning refers to the process of unconsciously learning complex knowledge through feedback. Previous studies investigated the influences of different types of feedback (e.g., social and non-social feedback) on implicit learning. This study focused on the social information presented in the learning situation and tried to explore the effects of different social feedback on implicit rule learning. We assigned participants randomly into an encouraging facial feedback group (happy expression for correct answer, neutral but not negative expression for incorrect answer) and a discouraging facial feedback group (neutral but not happy expression for correct answer, negative expression for incorrect answer). The implicit learning task included four difficulty levels, and social feedback was presented in the learning phase but not the testing phase in two experiments. The only difference between the two experiments was that the sad face used as negative feedback in Experiment 1 was replaced with an angry face in Experiment 2 to enhance the ecological validity of the discouraging facial feedback group. These two experiments yielded consistent results: the performances in the encouraging facial feedback group were more accurate in both the learning and the testing phases at all difficulty levels. These findings indicated that the influence of encouraging social feedback for a better implicit learning achievement was stable and established a new groundwork for future research on incentive-based education, making it critical to investigate the impact of various forms of encouraging-based education on learning.

2.
Behav Sci (Basel) ; 13(12)2023 Nov 23.
Article in English | MEDLINE | ID: mdl-38131819

ABSTRACT

Implicit learning refers to the fact that people acquire new knowledge (structures or rules) without conscious awareness. Previous studies have shown that implicit learning is affected by feedback. However, few studies have investigated the role of social feedback in implicit learning concretely. Here, we conducted two experiments to explore how in-group and out-group facial feedback impact different difficulty levels of implicit rule learning. In Experiment 1, the Chinese participants in each group could only see one type of facial feedback, i.e., either in-group (East Asian) or out-group (Western) faces, and learned the implicit rule through happy and sad facial expressions. The only difference between Experiment 2 and Experiment 1 was that the participants saw both the in-group and out-group faces before group assignment to strengthen the contrast between the two group identities. The results showed that only in Experiment 2 but not Experiment 1 was there a significant interaction effect in the accuracy of tasks between the difficulty levels and groups. For the lowest difficulty level, the learning accuracy of the in-group facial feedback group was significantly higher than that of the out-group facial feedback group, whereas this did not happen at the two highest levels of difficulty. In conclusion, when the contrast of group identities was highlighted, out-group feedback reduced the accuracy of the least difficult task; on the contrary, there was no accuracy difference between out-group and in-group feedback conditions. These findings have extensively important implications for our understanding of implicit learning and improving teaching achievement in the context of educational internationalization.

3.
Sci Rep ; 13(1): 8592, 2023 05 26.
Article in English | MEDLINE | ID: mdl-37237089

ABSTRACT

Pangolin is a mysterious animal in the Family Pholidota, Mammalia. Malayan pangolin (Manis javanica) is one of eight existing species and is listed in Manis. With the number of wild pangolins (Manis spp.) rapidly decreasing, captive breeding has become an important way to protect them from extinction. The research on mating behavior of pangolins is an important content to understand its reproductive characteristics and develop breeding management. From 2016 to 2022, a total of 360 mating events were observed in six males and 24 females through closed circuit television (CCTV) surveillance. The results show that males do not engage in complex courtship behavior before mating. In addition, we found that male pangolins adopted a ventrolateral mating position. Once males selected the side (left/right) of the female pangolin from which to approach to mate, they usually remained on the same side for subsequent mating, suggesting that male pangolins may have a preference in mating position. Finally, all mating events were observed at 1.72 ± 1.47 (n = 83, Mean ± SD) days after cohabitation and adjustment time before mating (from the male touching the female to intromission) took 4.98 ± 3.86 mins (n = 323). During mating, males hugged females and remained still for 47.37 ± 10.08 seconds (n = 323), which is the ejaculation and post-ejaculation quiescent time. Remarkably, we observed for the first time two peak mating times, 19:00 to 22:00 and 1:00 to 3:00, suggesting that they may have a preference for mating times. This study provides new insight into the mating behavior of M. javanica and contributes to the development of scientific conservation measures to improve the reproductive capacity of M. javanica.


Subject(s)
Pangolins , Plant Breeding , Animals , Female , Male , Mammals , Reproduction , Ejaculation
4.
PLoS One ; 17(9): e0272020, 2022.
Article in English | MEDLINE | ID: mdl-36103487

ABSTRACT

This study tracked and recorded the weight changes of 13 captive Sunda pangolin cubs from lactation to maturity to explored the appropriate weaning time and reveal the rules of its weight growth. SPSS 25.0 was used to build a cubic equation model to fit the body weight change rules of 4 individuals who nonvoluntarily ingested artificial feed (NIAF) at 127 days after birth and 5 individuals who voluntarily ingested artificial feed (VIAF) at 86-108 days after birth. The body weight of NIAF cubs aged 0-120 days and VIAF cubs aged 0-150 days were estimated according to the fitting model. An independent sample T-test was performed on the mean body weight of the two groups during the late lactation period. The results showed that at 105 days after birth, the body weight of the VIAF group was significantly higher than that of the NIAF group (P = 0.049), and the body weight of the VIAF group was extremely significantly higher than that of the NIAF group at 114 days (P = 0.008); The peak cumulative body weight of the NIAF cubs during lactation appeared around 130 days of age (n = 3); The mortality rate was 66.7% (n = 3) after about 150 days if the feed was continuously consumed nonvoluntarily. It was concluded that the milk secretion period of the mother is about 0-5 months after giving birth; the weaning period of the cubs should be 4-5 months after birth. If the cubs don't follow the mother to eat artificial feed for 3 months after birth, it can start be induced with artificial diet which adds termites, and the time point cannot be later than 130 days, otherwise it is not conducive to the survival of the cubs; When sexually mature, the body length and body weight of female cubs account for about 84% and 60% of the adult, respectively; the body maturity and body weight of female cubs tend to be stable about 15.3 months and 16.4 months, respectively. Finally, a special needle-shaped nipples and nursing patterns of female Sunda pangolins were also recorded in this study. These findings play an important role in guiding the nursing of captive Sunda pangolin cubs and other pangolin cubs. It is expected to improve the survival rate of the cubs by exploring the appropriate weaning time and the rules of weight growth. By scientifically planning the reproductive cycle of the female Sunda pangolins, our goal is to expand the population size and eventually release to the wild, meanwhile improving knowledge of this critically endangered species.


Subject(s)
Endangered Species , Pangolins , Animals , Body Weight , Female , Humans , Lactation , Pregnancy , Weaning
5.
PLoS One ; 17(8): e0271322, 2022.
Article in English | MEDLINE | ID: mdl-36037226

ABSTRACT

Most image content modelling methods are designed for English description which is different form Chinese in syntax structure. The few existing Chinese image description models do not fully integrate the global features and the local features of an image, limiting the capability of the models to represent the details of the image. In this paper, an encoder-decoder architecture based on the fusion of global and local features is used to describe the Chinese image content. In the encoding stage, the global and local features of the image are extracted by the Convolutional Neural Network (CNN) and the target detection network, and fed to the feature fusion module. In the decoding stage, an image feature attention mechanism is used to calculate the weights of word vectors, and a new gating mechanism is added to the traditional Long Short-Term Memory (LSTM) network to emphasize the fused image features, and the corresponding word vectors. In the description generation stage, the beam search algorithm is used to optimize the word vector generation process. The integration of global and local features of the image is strengthened to allow the model to fully understand the details of the image through the above three stages. The experimental results show that the model improves the quality of Chinese description of image content. Compared with the baseline model, the score of CIDEr evaluation index improves by 20.07%, and other evaluation indices also improve significantly.


Subject(s)
Algorithms , Neural Networks, Computer , China , Gene Fusion
6.
Commun Biol ; 4(1): 1212, 2021 10 21.
Article in English | MEDLINE | ID: mdl-34675353

ABSTRACT

Pangolins are threatened placental mammals distributed in Africa and Asia. Many efforts have been undertaken in the last century to maintain pangolins in captivity, but only a few of them succeeded in maintaining and keeping this species in a controlled environment. This study reports the first systematic breeding of the Critically Endangered Malayan pangolin (Manis javanica) in captivity. Our captive breeding approach successfully improved the reproductive rate for both wild and captive-born female pangolins. From 2016 to 2020, we had 33 wild pangolins and produced 49 captive-born offspring spanning three filial generations. The female offspring further bred 18 offspring, of which 14 (78%) were conceived during the first time of cohabitation with males, and four offspring were conceived during the second cohabitation event, suggesting that they may practice copulation-induced ovulation. We observed that captive-born female pangolins could reach sexual maturity at 7-9 months (n = 4), and male pangolins could mate and successfully fertilise females at nine months age (n = 1). We also observed a female pangolin conceiving on the eighth day after parturition (the fifth day after the death of its pup). Our captive pangolins had a female-biased sex ratio of 1:0.5 at birth, unlike other known captive-born mammals. Also, captive-born pangolins were generally more viable after successful weaning and had a similar gestation length (~185 days) to wild pangolins. Most importantly, we report the first self-sustaining captive population of Malayan pangolins, and this species has an efficient reproduction strategy. These advances provide more comprehensive information for people to understand pangolins, and have implications for conserving endangered Malayan pangolins and providing scientific guidance to the management of other pangolin species.


Subject(s)
Breeding , Conservation of Natural Resources , Endangered Species , Pangolins , Animals , Female , Male
7.
J Healthc Eng ; 2021: 6095676, 2021.
Article in English | MEDLINE | ID: mdl-34354808

ABSTRACT

The impulse noise in CT image was removed based on edge-preserving median filter algorithm. The sparse nonlocal regularization algorithm weighted coding was used to remove the impulse noise and Gaussian noise in the mixed noise, and the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) were calculated to evaluate the quality of the denoised CT image. It was found that in nine different proportions of Gaussian noise and salt-and-pepper noise in Shepp-Logan image and CT image processing, the PSNR and SSIM values of the proposed denoising algorithm based on edge-preserving median filter (EP median filter) and weighted encoding with sparse nonlocal regularization (WESNR) were significantly higher than those of using EP median filter and WESNR alone. It was shown that the weighted coding algorithm based on edge-preserving median filtering and sparse nonlocal regularization had potential application value in low-dose CT image denoising.


Subject(s)
Algorithms , Image Processing, Computer-Assisted , Humans , Normal Distribution , Signal-To-Noise Ratio , Tomography, X-Ray Computed
8.
Curr Microbiol ; 78(3): 1017-1025, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33537884

ABSTRACT

Pangolins (scaly anteaters, Pholidota) are among those mammals that are most affected by the international, illegal wildlife trade. Recently, wildlife rescue centers in China became dedicated to rehabilitate confiscated pangolins and prepare them for reintroduction to the wild. Chronic stress is thought to be the main reason for a disturbed microbiota community and a higher mortality rate of pangolin in captivity. In this study, we compared the cortisol levels and the fecal microbiome of Malayan pangolin (Manis javanica) born and reared in captivity (PCB; n = 7) with those rescued from the wildlife trade (PCT; n = 16). Results show that the level of cortisol in PCT was significantly lower than that observed in PCB. There were also significant differences in the composition of the fecal microflora between the two groups, and the diversity of intestinal microbiota was higher in PCB than in PCT. At the phylum level, the bacteria with significant difference between the two groups included Firmicutes and Bacteroides. At the genus level, bacteria such as Bacteroides, Parabacterides, and Clostridium showed significant differences between the two groups. This study proves that chronic stress has a considerable effect on the diversity and composition of fecal microbiota in Malayan pangolin.


Subject(s)
Animals, Wild , Microbiota , Animals , China , Mammals , Pangolins
9.
Hum Vaccin Immunother ; 14(10): 2510-2515, 2018.
Article in English | MEDLINE | ID: mdl-30047819

ABSTRACT

BACKGROUND: At present, the biomarkers which can predict the clinical efficacy of allergen immunotherapy (AIT) are still much debated. IgE levels are often related to allergic severity. Therefore, this study aimed at relating total IgE (tIgE) levels with the efficacy of AIT assessed by symptoms and drug score and skin prick test (SPT) response. METHODS: We evaluated 81 allergic children who had received house-dust mite (HDM) subcutaneous immunotherapy for three years. According to the tIgE levels before treatment, all children were divided into high value, medium value and low value group. Each group according to sIgE/tIgE ratio was divided into subgroups. The efficacy of AIT is assessed by symptoms and drug score. By comparing changes in the grade of SPT in each group, the response of AIT are evaluated. RESULTS: The SPT grade changes to determine efficacy had a high degree of consistency with symptoms and drug score judgment (sensitivity 89.7%, specificity 78.3%, Kappa = 0.670, P < 0.001). Compared to ineffective cases, the effective cases had lower tIgE (P < 0.001) and higher ratio of sIgE/tIgE (P < 0.001). The grades of SPT declined the most in the low value group (low value group vs. medium value group, P < 0.05; low value group vs. high value group, P < 0.001; medium value group vs. high value group, P < 0.05). CONCLUSIONS: The SPT grade change can be used for efficacy evaluation. Children with lower level of tIgE and higher ratio of sIgE/tIgE that obtain a more satisfactory effect.


Subject(s)
Allergens/immunology , Asthma/therapy , Desensitization, Immunologic/methods , Drug Monitoring/methods , Mites/immunology , Rhinitis/therapy , Skin Tests/methods , Animals , Asthma/pathology , Child , China , Female , Humans , Male , Retrospective Studies , Rhinitis/pathology , Sensitivity and Specificity
10.
J Healthc Eng ; 2017: 6506049, 2017.
Article in English | MEDLINE | ID: mdl-29201332

ABSTRACT

Random walk (RW) method has been widely used to segment the organ in the volumetric medical image. However, it leads to a very large-scale graph due to a number of nodes equal to a voxel number and inaccurate segmentation because of the unavailability of appropriate initial seed point setting. In addition, the classical RW algorithm was designed for a user to mark a few pixels with an arbitrary number of labels, regardless of the intensity and shape information of the organ. Hence, we propose a prior knowledge-based Bayes random walk framework to segment the volumetric medical image in a slice-by-slice manner. Our strategy is to employ the previous segmented slice to obtain the shape and intensity knowledge of the target organ for the adjacent slice. According to the prior knowledge, the object/background seed points can be dynamically updated for the adjacent slice by combining the narrow band threshold (NBT) method and the organ model with a Gaussian process. Finally, a high-quality image segmentation result can be automatically achieved using Bayes RW algorithm. Comparing our method with conventional RW and state-of-the-art interactive segmentation methods, our results show an improvement in the accuracy for liver segmentation (p < 0.001).


Subject(s)
Bayes Theorem , Cone-Beam Computed Tomography/methods , Pattern Recognition, Automated/methods , Algorithms , Sensitivity and Specificity
11.
Medicine (Baltimore) ; 96(35): e7848, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28858095

ABSTRACT

Asthma is a chronic inflammatory disease that requires adherence to both preventative and therapeutic interventions in disease management. Children with asthma are likely to discontinue inhaled corticosteroids (ICS), especially when symptoms are under control. We aimed to investigate the impact of ICS adherence in children whose symptoms were under control.The study is cohort study; 35 children with controlled asthma that had undergone 3 years of follow-up were included. Serum eosinophil count, serum total IgE (tIgE), and lung function (FEV1, FEV1/FVC, PEF, FEF20-75%, and PC20) were evaluated at the beginning and end of the follow-up.At baseline, patients in both the adherent and nonadherent groups were similar. After 3 years, the nonadherent group who had discontinued ICS had a decrease in FEV1 (P < .05), FEV1/FVC (P < .05), PEF (P < .05), and FEF20-75% (P < .05). The nonadherent group had no significant improvement in PC20 compared with their values at the beginning of the follow-up, whereas the adherent group had improvement in PC20. Furthermore, there was an increase in serum eosinophil (P < .001) and tIgE (P < .05) in the nonadherent compared with the adherent group.Despite good asthma control, airway hyperresponsiveness (AHR) was detected in a large proportion of children with asthma. ICS discontinuation affected lung function, serum eosinophil count, tIgE, and AHR. Adequate adherence is important in asthma management. The benefits of ICS and the influence of drug discontinuation despite good asthma control may encourage better adherence from patients.


Subject(s)
Adrenal Cortex Hormones/administration & dosage , Asthma/drug therapy , Medication Adherence , Administration, Inhalation , Asthma/blood , Asthma/physiopathology , Child , Cohort Studies , Drug Administration Schedule , Female , Humans , Immunoglobulin E/blood , Leukocyte Count , Male , Respiratory Function Tests , Retrospective Studies
12.
J Struct Biol ; 185(3): 267-77, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24382495

ABSTRACT

In cases where ultra-flat cryo-preparations of well-ordered two-dimensional (2D) crystals are available, electron crystallography is a powerful method for the determination of the high-resolution structures of membrane and soluble proteins. However, crystal unbending and Fourier-filtering methods in electron crystallography three-dimensional (3D) image processing are generally limited in their performance for 2D crystals that are badly ordered or non-flat. Here we present a single particle image processing approach, which is implemented as an extension of the 2D crystallographic pipeline realized in the 2dx software package, for the determination of high-resolution 3D structures of membrane proteins. The algorithm presented, addresses the low single-to-noise ratio (SNR) of 2D crystal images by exploiting neighborhood correlation between adjacent proteins in the 2D crystal. Compared with conventional single particle processing for randomly oriented particles, the computational costs are greatly reduced due to the crystal-induced limited search space, which allows a much finer search space compared to classical single particle processing. To reduce the considerable computational costs, our software features a hybrid parallelization scheme for multi-CPU clusters and computer with high-end graphic processing units (GPUs). We successfully apply the new refinement method to the structure of the potassium channel MloK1. The calculated 3D reconstruction shows more structural details and contains less noise than the map obtained by conventional Fourier-filtering based processing of the same 2D crystal images.


Subject(s)
Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Membrane Proteins/metabolism , Software , Membrane Proteins/chemistry
13.
Methods Mol Biol ; 955: 171-94, 2013.
Article in English | MEDLINE | ID: mdl-23132061

ABSTRACT

Electron crystallography of membrane proteins uses cryo-transmission electron microscopy to image frozen-hydrated 2D crystals. The processing of recorded images exploits the periodic arrangement of the structures in the images to extract the amplitudes and phases of diffraction spots in Fourier space. However, image imperfections require a crystal unbending procedure to be applied to the image before evaluation in Fourier space. We here describe the process of 2D crystal image unbending, using the 2dx software system.


Subject(s)
Crystallography/methods , Image Processing, Computer-Assisted/methods , Algorithms , Fourier Analysis , Membrane Proteins/chemistry , Software
14.
Methods Mol Biol ; 955: 313-30, 2013.
Article in English | MEDLINE | ID: mdl-23132069

ABSTRACT

Electron crystallography of membrane proteins records images and diffraction patterns of frozen-hydrated two-dimensional (2D) crystals. To reconstruct the high-resolution three-dimensional (3D) structure of a membrane protein, a multitude of images of 2D crystals have to be processed. Certain processing steps are thereby similar for batches of images that were recorded under similar conditions. Here we describe how the 2dx software package can be used to automate the processing of 2D crystal images, and how the 2D and 3D merging results can be used to iteratively reprocess the images. While the processing of 2D crystal images has been fully automated, the merging process is still semi-manual.


Subject(s)
Automation , Image Processing, Computer-Assisted/methods , Membrane Proteins/chemistry , Software , Computational Biology/methods , Cryoelectron Microscopy , Crystallography , Internet
15.
Methods Enzymol ; 482: 101-29, 2010.
Article in English | MEDLINE | ID: mdl-20888959

ABSTRACT

Electron crystallography of 2D protein crystals can determine the structure of membrane embedded proteins at high resolution. Images or electron diffraction patterns are recorded with the electron microscope of the frozen hydrated samples, and the 3D structure of the proteins is then determined by computer data processing. Here we introduce the image-processing algorithms for crystallographic Fourier space based methods using the Medical Research Council (MRC) programs, and illustrate the usage of the software packages 2dx, XDP, and IPLT.


Subject(s)
Crystallography/methods , Imaging, Three-Dimensional/methods , Microscopy, Electron/methods , Algorithms , Software
16.
J Struct Biol ; 160(3): 375-84, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17967545

ABSTRACT

Electron crystallography of membrane proteins determines the structure of membrane-reconstituted and two-dimensionally (2D) crystallized membrane proteins by low-dose imaging with the transmission electron microscope, and computer image processing. We have previously presented the software system 2dx, for user-friendly image processing of 2D crystal images. Its central component 2dx_image is based on the MRC program suite, and allows the optionally fully automatic processing of one 2D crystal image. We present here the program 2dx_merge, which assists the user in the management of a 2D crystal image processing project, and facilitates the merging of the data from multiple images. The merged dataset can be used as a reference to re-process all images, which usually improves the resolution of the final reconstruction. Image processing and merging can be applied iteratively, until convergence is reached. 2dx is available under the GNU General Public License at http://2dx.org.


Subject(s)
Crystallization , Crystallography/methods , Image Processing, Computer-Assisted/methods , Microscopy, Electron, Transmission/methods , Molecular Structure , Software , Computer Graphics , Likelihood Functions , User-Computer Interface
17.
J Struct Biol ; 160(3): 362-74, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17964808

ABSTRACT

Maximum likelihood (ML) processing of transmission electron microscopy images of protein particles can produce reconstructions of superior resolution due to a reduced reference bias. We have investigated a ML processing approach to images centered on the unit cells of two-dimensional (2D) crystal images. The implemented software makes use of the predictive lattice node tracking in the MRC software, which is used to window particle stacks. These are then noise-whitened and subjected to ML processing. Resulting ML maps are translated into amplitudes and phases for further processing within the 2dx software package. Compared with ML processing for randomly oriented single particles, the required computational costs are greatly reduced as the 2D crystals restrict the parameter search space. The software was applied to images of negatively stained or frozen hydrated 2D crystals of different crystal order. We find that the ML algorithm is not free from reference bias, even though its sensitivity to noise correlation is lower than for pure cross-correlation alignment. Compared with crystallographic processing, the newly developed software yields better resolution for 2D crystal images of lower crystal quality, and it performs equally well for well-ordered crystal images.


Subject(s)
Algorithms , Crystallization , Crystallography/methods , Image Processing, Computer-Assisted/statistics & numerical data , Microscopy, Electron, Transmission/methods , Proteins/ultrastructure , Software , Cryoelectron Microscopy/methods , Fourier Analysis , Image Processing, Computer-Assisted/methods , Likelihood Functions , Negative Staining , Protein Conformation , Proteins/chemistry
18.
J Struct Biol ; 160(3): 353-61, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17904383

ABSTRACT

Electron crystallography determines the structure of membrane proteins and other periodic samples by recording either images or diffraction patterns. Computer processing of recorded images requires the determination of the reciprocal lattice parameters in the Fourier transform of the image. We have developed a set of three programs 2dx_peaksearch, 2dx_findlat and 2dx_getlat, which can determine the reciprocal lattice from a Fourier transformation of a 2D crystal image automatically. 2dx_peaksearch determines a list of Fourier peak coordinates from a processed calculated diffraction pattern. These coordinates are evaluated by 2dx_findlat to determine one or more lattices, using a-priori knowledge of the real-space crystal unit cell dimensions, and the sample tilt geometry. If these are unknown, then the program 2dx_getlat can be used to obtain a guess for the unit cell dimensions. These programs are available as part of the 2dx software package for the image processing of 2D crystal images at http://2dx.org.


Subject(s)
Algorithms , Crystallization , Crystallography/methods , Image Processing, Computer-Assisted/methods , Membrane Proteins/ultrastructure , Microscopy, Electron, Transmission/methods , Software , Fourier Analysis , Membrane Proteins/chemistry
19.
Structure ; 15(9): 1053-64, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17850745

ABSTRACT

The gating ring of cyclic nucleotide-modulated channels is proposed to be either a two-fold symmetric dimer of dimers or a four-fold symmetric tetramer based on high-resolution structure data of soluble cyclic nucleotide-binding domains and functional data on intact channels. We addressed this controversy by obtaining structural data on an intact, full-length, cyclic nucleotide-modulated potassium channel, MloK1, from Mesorhizobium loti, which also features a putative voltage-sensor. We present here the 3D single-particle structure by transmission electron microscopy and the projection map of membrane-reconstituted 2D crystals of MloK1 in the presence of cAMP. Our data show a four-fold symmetric arrangement of the CNBDs, separated by discrete gaps. A homology model for full-length MloK1 suggests a vertical orientation for the CNBDs. The 2D crystal packing in the membrane-embedded state is compatible with the S1-S4 domains in the vertical "up" state.


Subject(s)
Cyclic AMP/metabolism , Potassium Channels/chemistry , Rhizobium/chemistry , Amino Acid Sequence , Crystallography , Microscopy, Electron, Transmission , Models, Molecular , Molecular Sequence Data , Protein Conformation , Sequence Homology, Amino Acid
20.
J Struct Biol ; 157(1): 64-72, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17055742

ABSTRACT

Electron crystallography determines the structure of two-dimensional (2D) membrane protein crystals and other 2D crystal systems. Cryo-transmission electron microscopy records high-resolution electron micrographs, which require computer processing for three-dimensional structure reconstruction. We present a new software system 2dx, which is designed as a user-friendly, platform-independent software package for electron crystallography. 2dx assists in the management of an image-processing project, guides the user through the processing of 2D crystal images, and provides transparence for processing tasks and results. Algorithms are implemented in the form of script templates reminiscent of c-shell scripts. These templates can be easily modified or replaced by the user and can also execute modular stand-alone programs from the MRC software or from other image processing software packages. 2dx is available under the GNU General Public License at 2dx.org.


Subject(s)
Crystallography, X-Ray/methods , Image Processing, Computer-Assisted/methods , Models, Molecular , Software , Algorithms , Membrane Proteins/chemistry , Software Design
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