Evolution of two-pore domain potassium channels and their gene expression in zebrafish embryos.

BACKGROUND: The two-pore domain potassium (K2P) channels are a major type of potassium channels that maintain the cell membrane potential by conducting passive potassium leak currents independent of voltage change. They play prominent roles in multiple physiological processes, including neuromodulation, perception of pain, breathing and mood control, and response to volatile anesthetics. Mutations in K2P channels have been linked to many human diseases, such as neuronal and cardiovascular disorders and cancers. Significant progress has been made to understand their protein structures, physiological functions, and pharmacological modifiers. However, their expression and function during embryonic development remain largely unknown. RESULTS: We employed the zebrafish model and identified 23 k2p genes using BLAST search and gene cloning. We first analyzed vertebrate K2P channel evolution by phylogenetic and syntenic analyses. Our data revealed that the six subtypes of the K2P genes have already evolved in invertebrates long before the emergence of vertebrates. Moreover, the vertebrate K2P gene number increased, most likely due to two whole-genome duplications. Furthermore, we examined zebrafish k2p gene expression during early embryogenesis by in situ hybridization. Each subgroup's genes showed similar but distinct gene expression domains with some exceptions. Most of them were expressed in neural tissues consistent with their known function of neural excitability regulation. However, a few k2p genes were expressed temporarily in specific tissues or organs, suggesting that these K2P channels may be needed for embryonic development. CONCLUSIONS: Our phylogenetic and developmental analyses of K2P channels shed light on their evolutionary history and potential roles during embryogenesis related to their physiological functions and human channelopathies.

Matrix Metalloproteinase and Aortic Aneurysm: A Two-sample Mendelian Randomization Study.

BACKGROUND: Studies have linked matrix metalloproteinases (MMPs) to both thoracic aortic aneurysm and abdominal aortic aneurysm (TAA and AAA). The precise MMPs entailed in this procedure, however, were still unknown. This study used a two-sample Mendelian randomization (MR) analysis to look into the causal relationship between MMPs and the risk of TAA and AAA. METHODS: Eight MMPs, including MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-12, and MMP-13, were found among people of European ancestry with accessible Genome-Wide Association Studies (GWAS). We employed the findings from Genome-Wide Association Studies (GWAS) for 8 MMPs, and TAA and AAA from the FinnGen consortiums (3,201 cases and 317,899 controls, respectively) were used in a two-sample MR analysis. The primary method of analysis for MR was the inverse variance weighted (IVW) method, along with analyses of heterogeneity and horizontal pleiotropy. 31 single-nucleotide polymorphisms connected to MMP were retrieved. RESULTS: IVW demonstrated a negative causal association between TAA and AAA and serum MMP-12 levels. The incidence of TAA decreased by 1.031% for every 1 ng/mL increase in serum MMP-12 [odds ratio (OR) = 0.897, 95% confidence interval (CI): 0.831-0.968, P = 0.005]. The incidence of AAA fell by 1.653% (OR = 0.835, 95% CI: 0.752-0.926, P = 0.001) for every 1 ng/mL increase in serum MMP-12. There was no horizontal pleiotropy or heterogeneity in the MR data (P > 0.05). CONCLUSIONS: The levels of TAA and AAA and serum MMP-12 are causally related. MMP-12 is a factor that reduces the risk of AAA and TTA. Our study suggested that MMP-12 level is causally associated with a decreased risk of TAA and AAA.

A robust and flexible CRISPR/Cas9-based system for neutrophil-specific gene inactivation in zebrafish.

CRISPR/Cas9-based tissue-specific knockout techniques are essential for probing the functions of genes in embryonic development and disease using zebrafish. However, the lack of capacity to perform gene-specific rescue or live imaging in the tissue-specific knockout background has limited the utility of this approach. Here, we report a robust and flexible gateway system for tissue-specific gene inactivation in neutrophils. Using a transgenic fish line with neutrophil-restricted expression of Cas9 and ubiquitous expression of single guide (sg)RNAs targeting rac2, specific disruption of the rac2 gene in neutrophils is achieved. Transient expression of sgRNAs targeting rac2 or cdk2 in the neutrophil-restricted Cas9 line also results in significantly decreased cell motility. Re-expressing sgRNA-resistant rac2 or cdk2 genes restores neutrophil motility in the corresponding knockout background. Moreover, active Rac and force-bearing F-actins localize to both the cell front and the contracting tail during neutrophil interstitial migration in an oscillating fashion that is disrupted when rac2 is knocked out. Together, our work provides a potent tool that can be used to advance the utility of zebrafish in identifying and characterizing gene functions in a tissue-specific manner.

Evolution of inwardly rectifying potassium channels and their gene expression in zebrafish embryos.

BACKGROUND: Inwardly rectifying potassium channels are essential for normal potassium homeostasis, maintaining the cellular resting membrane potential, and regulating electrolyte transportation. Mutations in Kir channels have been known to cause debilitating diseases ranging from neurological abnormalities to renal and cardiac failures. Many efforts have been made to understand their protein structures, physiological functions, and pharmacological modifiers. However, their expression and functions during embryonic development remain largely unknown. RESULTS: Using zebrafish as a model, we identified and renamed 31 kir genes. We also analyzed Kir gene evolution by phylogenetic and syntenic analyses. Our data indicated that the four subtypes of the Kir genes might have already evolved out in chordates. These vertebrate Kir genes most likely resulted from both whole-genome duplications and tandem duplications. In addition, we examined zebrafish kir gene expression during early embryogenesis. Each subgroup's genes showed similar but distinct gene expression domains. The gene expression of ohnologous genes from teleost-specific whole-genome duplication indicated subfunctionalization. Varied temporal gene expression domains suggest that Kir channels may be needed for embryonic patterning or regulation. CONCLUSIONS: Our phylogenetic and developmental analyses of Kir channels shed light on their evolutionary history and potential functions during embryogenesis related to congenital diseases and human channelopathies.

The genetic program for cartilage development has deep homology within Bilateria.

The evolution of novel cell types led to the emergence of new tissues and organs during the diversification of animals. The origin of the chondrocyte, the cell type that synthesizes cartilage matrix, was central to the evolution of the vertebrate endoskeleton. Cartilage-like tissues also exist outside the vertebrates, although their relationship to vertebrate cartilage is enigmatic. Here we show that protostome and deuterostome cartilage share structural and chemical properties, and that the mechanisms of cartilage development are extensively conserved--from induction of chondroprogenitor cells by Hedgehog and ß-catenin signalling, to chondrocyte differentiation and matrix synthesis by SoxE and SoxD regulation of clade A fibrillar collagen (ColA) genes--suggesting that the chondrogenic gene regulatory network evolved in the common ancestor of Bilateria. These results reveal deep homology of the genetic program for cartilage development in Bilateria and suggest that activation of this ancient core chondrogenic network underlies the parallel evolution of cartilage tissues in Ecdysozoa, Lophotrochozoa and Deuterostomia.

Ribosomal protein gene RPL9 variants can differentially impair ribosome function and cellular metabolism.

Variants in ribosomal protein (RP) genes drive Diamond-Blackfan anemia (DBA), a bone marrow failure syndrome that can also predispose individuals to cancer. Inherited and sporadic RP gene variants are also linked to a variety of phenotypes, including malignancy, in individuals with no anemia. Here we report an individual diagnosed with DBA carrying a variant in the 5'UTR of RPL9 (uL6). Additionally, we report two individuals from a family with multiple cancer incidences carrying a RPL9 missense variant. Analysis of cells from these individuals reveals that despite the variants both driving pre-rRNA processing defects and 80S monosome reduction, the downstream effects are remarkably different. Cells carrying the 5'UTR variant stabilize TP53 and impair the growth and differentiation of erythroid cells. In contrast, ribosomes incorporating the missense variant erroneously read through UAG and UGA stop codons of mRNAs. Metabolic profiles of cells carrying the 5'UTR variant reveal an increased metabolism of amino acids and a switch from glycolysis to gluconeogenesis while those of cells carrying the missense variant reveal a depletion of nucleotide pools. These findings indicate that variants in the same RP gene can drive similar ribosome biogenesis defects yet still have markedly different downstream consequences and clinical impacts.

Phylogenetic and developmental analyses indicate complex functions of calcium-activated potassium channels in zebrafish embryonic development.

BACKGROUND: Calcium-activated potassium channels (KCa) are a specific type of potassium channel activated by intracellular calcium concentration changes. This group of potassium channels plays fundamental roles ranging from regulating neuronal excitability to immune cell activation. Many human diseases such as schizophrenia, hypertension, epilepsy, and cancers have been linked to mutations in this group of potassium channels. Although the KCa channels have been extensively studied electrophysiologically and pharmacologically, their spatiotemporal gene expression during embryogenesis remains mostly unknown. RESULTS: Using zebrafish as a model, we identified and renamed 14 KCa genes. We further performed phylogenetic and syntenic analyses on vertebrate KCa genes. Our data revealed that the number of KCa genes in zebrafish was increased, most likely due to teleost-specific whole-genome duplication. Moreover, we examined zebrafish KCa gene expression during early embryogenesis. The duplicated ohnologous genes show distinct and overlapped gene expression. Furthermore, we found that zebrafish KCa genes are expressed in various tissues and organs (somites, fins, olfactory regions, eye, kidney, and so on) and neuronal tissues, suggesting that they may play important roles during zebrafish embryogenesis. CONCLUSIONS: Our phylogenetic and developmental analyses shed light on the potential functions of the KCa genes during embryogenesis related to congenital diseases and human channelopathies.

Loss of smarcad1a accelerates tumorigenesis of malignant peripheral nerve sheath tumors in zebrafish.

Malignant peripheral nerve sheath tumors (MPNSTs) are a type of sarcoma that generally originates from Schwann cells. The prognosis for this type of malignancy is relatively poor due to complicated genetic alterations and the lack of specific targeted therapy. Chromosome fragment 4q22-23 is frequently deleted in MPNSTs and other human tumors, suggesting tumor suppressor genes may reside in this region. Here, we provide evidence that SMARCAD1, a known chromatin remodeler, is a novel tumor suppressor gene located in 4q22-23. We identified two human homologous smarcad1 genes (smarcad1a and smarcad1b) in zebrafish, and both genes share overlapping expression patterns during embryonic development. We demonstrated that two smarcad1a loss-of-function mutants, sa1299 and p403, can accelerate MPNST tumorigenesis in the tp53 mutant background, suggesting smarcad1a is a bona fide tumor suppressor gene for MPNSTs. Moreover, we found that DNA double-strand break (DSB) repair might be compromised in both mutants compared to wildtype zebrafish, as indicated by pH2AX, a DNA DSB marker. In addition, both SMARCAD1 gene knockdown and overexpression in human cells were able to inhibit tumor growth and displayed similar DSB repair responses, suggesting proper SMARCAD1 gene expression level or gene dosage is critical for cell growth. Given that mutations of SMARCAD1 sensitize cells to poly ADP ribose polymerase inhibitors in yeast and the human U2OS osteosarcoma cell line, the identification of SMARCAD1 as a novel tumor suppressor gene might contribute to the development of new cancer therapies for MPNSTs.

Online stereo vision measurement based on correction of sensor structural parameters.

Vibration can easily affect the structure of long baseline binocular vision sensors, resulting in changes in the external parameters of the binocular calibration model and the failure of measurement method. This paper presents an online stereo vision measurement based on correction of sensor structural parameters. The flexible structure model based on calibration model and iterative gradient descent nonlinear optimization model based on 3D redundant information are established. The optimal estimation of external parameters and object position measurement are realized according to multi-information constraints. Experiments show that this method can effectively solve the measurement failure caused by vibration in stereo vision measurement.

Evaluation of Lipoprotein-Associated Phospholipase A2 as a Prognostic Biomarker in Chronic Kidney Disease.

BACKGROUND: The leading cause of death in patients with chronic kidney disease (CKD) is atherosclerosis (AS). Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a biomarker of atherosclerotic plaque stability. The aim of our study was to analyze the association of Lp-PLA2 with CKD complicated with carotid atherosclerotic stenosis (CAS). METHODS: Serum specimens were collected from 77 CKD patients and 39 healthy controls. Laboratory examination results including glucose, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and Lp-PLA2 were measured. Receiver operating characteristic (ROC) was drawn and the area under the curve (AUC) was calculated. RESULTS: Multivariate logistic regression analysis showed that age, gender, glucose, and Lp-PLA2 were considered as risks for CKD-CAS with odds ratios (OR) of 1.111 (95% CI: 1.055, 1.170), 5.123 (95% CI: 1.482, 17.714), 1.679 (95% CI: 1.123, 2.512), and 1.023 (95% CI: 1.008, 1.037), respectively. The AUC for Lp-PLA2 and glucose was 0.618 (p = 0.014) and 0.592 (p = 0.057), respectively. The best diagnostic value was archived by Lp-PLA2 with the cutoff value of 201.06 ng/mL. CONCLUSIONS: Lp-PLA2 is a potential prognostic and diagnostic biomarker for CKD-CAS.

Parameter optimization of a single-FOV-double-region celestial navigation system.

A single field of view (FOV) celestial navigation system (SFCNS) is a navigation system that uses only one camera to observe stars. This system not only requires nonrefracted stars for attitude measurement but also refracted stars via the atmosphere for position measurement. Different from traditional star sensors, the ability of SFCNS to observe a sufficient number of nonrefracted stars and refracted stars is not only related to the camera parameters used by the system but also to the observation attitude of the system. Moreover, its measurement accuracy depends on these parameters. For the SFCNS, both a reasonable distribution of the area ratio of the refraction and nonrefraction regions in the image and a proper design of camera parameters are important. Thus, a single-FOV-double-region global parameter optimization model is established to describe the relationship between the observation attitude, camera parameters, union star detection probability, and measurement error. The smallest measurement error and the maximum union star detection probability are set as the optimization objects. Through optimization, an optimal design scheme is provided. Eventually, a simulation experiment is conducted, proving that the proposed optimal design scheme has a union detection probability of 61%, an attitude measurement error of 0.57'', and an orbit height measurement error below 100 m.

A Line Matching Method Based on Multiple Intensity Ordering with Uniformly Spaced Sampling.

This paper presents a line matching method based on multiple intensity ordering with uniformly spaced sampling. Line segments are extracted from the image pyramid, with the aim of adapting scale changes and addressing fragmentation problem. The neighborhood of line segments was divided into sub-regions adaptively according to intensity order to overcome the difficulty brought by various line lengths. An intensity-based local feature descriptor was introduced by constructing multiple concentric ring-shaped structures. The dimension of the descriptor was reduced significantly by uniformly spaced sampling and dividing sample points into several point sets while improving the discriminability. The performance of the proposed method was tested on public datasets which cover various scenarios and compared with another two well-known line matching algorithms. The experimental results show that our method achieves superior performance dealing with various image deformations, especially scale changes and large illumination changes, and provides much more reliable correspondences.

Quantitative analysis of eco-economic benefits of reclaimed water for controlling urban dust.

With the acceleration of urbanization and industrialization, urban air pollution, especially dust pollution, has become a global problem. The traditional method to control dust problem is to spray roads with tap water. However, this method will inevitably lead to a huge waste of water resources. Using reclaimed water instead of tap water for dust control can not only achieve the same effect of reducing dust and haze, but also save water resources. In addition, the saved tap water can be used for production and life, thereby obtaining additional benefits. In order to quantify the eco-economic benefits of sprinkling water for dust control, a quantitative method was proposed based on the emergy theory of ecological economics. It was used to calculate the cost of different water resources, the cooling and humidifying benefit, the dust control and haze reduction benefit, and the other use benefit. Taking the 2017 data of Zhengzhou as an example, the results indicated that the cost of using reclaimed water to control dust was reduced by 54%. The total benefit of using reclaimed water was about 1.30-1.80 times that of using tap water, and the net benefit was 4.65-7.17 times. Therefore, the use of reclaimed water instead of tap water for road dust control has advantages of low cost and high eco-economic benefits. The method proposed in this paper can provide quantitative basis for the popularization of using reclaimed water to dust control in cities with serious air pollution and water resource shortage.

Observation angular distance error modeling and matching threshold optimization for terrestrial star tracker.

Observation angular distance error, as the difference between the actual observation angular distance and the reference angular distance, is an important parameter that affects the identification success rate, attitude measurement accuracy, and real-time performance of a terrestrial star tracker. It is the criterion to determine whether stars are identified in star identification but is still unclarified to date. To resolve the problem, the observation angular error model is presented in this work. This model determines the variation range of the observation angular distance error by analyzing the factors of astrometric transformations. Then, the optimal angular distance matching threshold expression for a terrestrial star tracker is presented on the basis of the proposed model for the optimal efficiency in star identification. Numerical simulations and a night sky experiment demonstrate that the differences between the theoretical model, simulation and actual experiment results are less than 0.5'' and thereby validate the reliability of our conclusions.

Extrinsic parameters calibration of multi-camera with non-overlapping fields of view using laser scanning.

An extrinsic parameters calibration method of multi-cameras with non-overlapping fields of view (FOV) using laser scanning is presented. Firstly, two lasers are mounted on a multi-degree-of-freedom manipulator and can scan objects freely by the projected line-structured light. Then, controlling the movement of the manipulator, the line-structured light is projected into the field of view of one of the multi-cameras, and the light plane equation in the camera coordinate frame is calibrated by the target. The manipulator is moved several times in small amplitude to change the position of structured light in the field of vision of the camera and to continue to calibrate the light plane. The light plane equation of line-structured light in the manipulator coordinate frame are solved by the hand-eye calibration method. Secondly, with the help of the light planes, projected into the field of vision of other cameras to be calibrated, the light plane equation in the camera coordinate frame is calibrated, and the external parameters between the camera coordinate frame and the manipulator coordinate frame are calculated, so that the calibration of the external parameters of multiple cameras can be realized. The proposed method connects the non-overlapping multi-cameras by the laser scanning. It can effectively solve the problem of multi-camera extrinsic parameter calibration under the conditions of long working distance and complex environment light.

Optical Parameters Optimization for All-Time Star Sensor.

As an important development direction of star sensor technology, the All-Time star sensor technology can expand the application of star sensors to flight platforms inside the atmosphere. Due to intense atmospheric background radiation during the daytime, the commonly used star sensors operating in the visible wavelength range are significantly limited in their ability to detect stars, and hence the All-Time star sensor technology which is based on the shortwave infrared (SWIR) imaging system has become an effective research direction. All-Time star sensor detection capability is significantly affected by observation conditions and, therefore, an optimized selection of optical parameters, which mainly includes the field of view (FOV) and the detection wavelength band, can effectively improve the detection performance of All-Time star sensors under harsh observation conditions. This paper uses the model simulation method to analyze and optimize the optical parameters under various observation conditions in a high-altitude environment. A main parameter among those discussed is the analysis of detection band optimization based on the SWIR band. Due to the huge cost constraints of high-altitude experiments, we conducted experiments near the ground to verify the effectiveness of the detection band selection and the correctness of the SWIR star sensor detection model, which thereby proved that the optimization of the optical parameters for high altitudes was effective and could be used as a reference.

Global field-of-view imaging model and parameter optimization for high dynamic star tracker.

With the expansion of applications, star trackers break through the domain of traditional applications and operate under high dynamic environments. These new applications require high maneuverability and render the analyses and conclusions of previous traditional star trackers unsuitable. In order to resolve the limitation of the previous studies, we focus on the global field-of-view (GFOV) imaging performance of a high dynamic star tracker (HDST) in this paper. A GFOV imaging trajectory model is derived to correctly describe the different motions of stars imaged at different positions of focal plane. A comprehensive positional accuracy expression is obtained by analyzing the centroiding errors of stars in GFOV. On the basis of the proposed trajectory model and positional accuracy expression, a solution of GFOV optimal parameters is presented for the best performance in centroid estimation. Finally, comparative evaluations, numerical simulations, and a night sky experiment support the conclusions.

Reliable and Accurate Wheel Size Measurement under Highly Reflective Conditions.

Structured-light vision sensor, as an important tool for obtaining 3D data, is widely used in fields of online high-precision measurement. However, the captured stripe images can show high-dynamic characteristics of low signal-to-noise ratio and uneven brightness due to the complexity of the onsite environment. These conditions seriously affect measurement reliability and accuracy. In this study, a wheel size measurement framework based on a structured-light vision sensor, which has high precision and reliability and is suitable for highly reflective conditions, is proposed. Initially, the quality evaluation criterion of stripe images is established, and the entire stripe is distinguished into high- and low-quality segments. In addition, the multi-scale Retinex theory is adopted to enhance stripe brightness, which improves the reliability of subsequent stripe center extraction. Experiments verify that this approach can remarkably improve measurement reliability and accuracy and has important practical value.

Star Centroiding Based on Fast Gaussian Fitting for Star Sensors.

The most accurate star centroiding method for star sensors is the Gaussian fitting (GF) algorithm, because the intensity distribution of a star spot conforms to the Gaussian function, but the computational complexity of GF is too high for real-time applications. In this paper, we develop the fast Gaussian fitting method (FGF), which approximates the solution of the GF in a closed-form, thus significantly speeding up the GF algorithm. Based on the fast Gaussian fitting method, a novel star centroiding algorithm is proposed, which sequentially performs the FGF twice to calculate the star centroid: the first FGF step roughly calculates the Gaussian parameters of a star spot and the noise intensity of each pixel; subsequently the second FGF accurately calculates the star centroid utilizing the noise intensity provided in the first step. In this way, the proposed algorithm achieves both high accuracy and high efficiency. Both simulated star images and star sensor images are used to verify the performance of the algorithm. Experimental results show that the accuracy of the proposed algorithm is almost the same as the GF algorithm, higher than most existing centroiding algorithms, meanwhile, the proposed algorithm is about 15 times faster than the GF algorithm, making it suitable for real-time applications.

Flexible method of refraction correction in vision measurement systems with multiple glass ports.

Many vision measurement systems, especially in outdoor engineering, usually utilize glass ports to protect sensors against environmental influences. The refraction caused by glass ports lead to measurement errors in traditional single viewpoint model. Most existing methods only deal with the refraction that happens once, and the glass ports are required to be perpendicular to cameras or the orientations of glass ports are obtained by auxiliary equipment. This paper proposes a corrected 3D reconstruction model based on refraction geometry, which can be used for any number of glass ports with any orientations. The orientation of each glass port is obtained only using refracted and unrefracted images of the same scene, which doesn't need any auxiliary equipment. A series of validation experiments are performed. An existing image rectification method is used to make a comparison. The proposed method is also employed in a train wheelset profile measurement application, which proves that the method is effective in actual applications.