Combining spectral and texture feature of UAV image with plant height to improve LAI estimation of winter wheat at jointing stage

IntroductionLeaf area index (LAI) is a critical physiological and biochemical parameter that profoundly affects vegetation growth. Accurately estimating the LAI for winter wheat during jointing stage is particularly important for monitoring wheat growth status and optimizing variable fertilization decisions. Recently, unmanned aerial vehicle (UAV) data and machine/depth learning methods are widely used in crop growth parameter estimation. In traditional methods, vegetation indices (VI) and texture are usually to estimate LAI. Plant Height (PH) unlike them, contains information about the vertical structure of plants, which should be consider.MethodsTaking Xixingdian Township, Cangzhou City, Hebei Province, China as the research area in this paper, and four machine learning algorithms, namely, support vector machine(SVM), back propagation neural network (BPNN), random forest (RF), extreme gradient boosting (XGBoost), and two deep learning algorithms, namely, convolutional neural network (CNN) and long short-term memory neural network (LSTM), were applied to estimate LAI of winter wheat at jointing stage by integrating the spectral and texture features as well as the plant height information from UAV multispectral images. Initially, Digital Surface Model (DSM) and Digital Orthophoto Map (DOM) were generated. Subsequently, the PH, VI and texture features were extracted, and the texture indices (TI) was further constructed. The measured LAI on the ground were collected for the same period and calculated its Pearson correlation coefficient with PH, VI and TI to pick the feature variables with high correlation. The VI, TI, PH and fusion were considered as the independent features, and the sample set partitioning based on joint x-y distance (SPXY) method was used to divide the calibration set and validation set of samples.ResultsThe ability of different inputs and algorithms to estimate winter wheat LAI were evaluated. The results showed that (1) The addition of PH as a feature variable significantly improved the accuracy of the LAI estimation, indicating that wheat plant height played a vital role as a supplementary parameter for LAI inversion modeling based on traditional indices; (2) The combination of texture features, including normalized difference texture indices (NDTI), difference texture indices (DTI), and ratio texture indices (RTI), substantially improved the correlation between texture features and LAI; Furthermore, multi-feature combinations of VI, TI, and PH exhibited superior capability in estimating LAI for winter wheat; (3) Six regression algorithms have achieved high accuracy in estimating LAI, among which the XGBoost algorithm estimated winter wheat LAI with the highest overall accuracy and best results, achieving the highest R2 (R2 = 0.88), the lowest RMSE (RMSE=0.69), and an RPD greater than 2 (RPD=2.54).DiscussionThis study provided compelling evidence that utilizing XGBoost and integrating spectral, texture, and plant height information extracted from UAV data can accurately monitor LAI during the jointing stage of winter wheat. The research results will provide a new perspective for accurate monitoring of crop parameters through remote sensing

In Vivo Delivery of Gremlin siRNA Plasmid Reveals Therapeutic Potential against Diabetic Nephropathy by Recovering Bone Morphogenetic Protein-7

Diabetic nephropathy is a complex and poorly understood disease process, and our current treatment options are limited. It remains critical, then, to identify novel therapeutic targets. Recently, a developmental protein and one of the bone morphogenetic protein antagonists, Gremlin, has emerged as a novel modulator of diabetic nephropathy. The high expression and strong co-localization with transforming growth factor- β1 in diabetic kidneys suggests a role for Gremlin in the pathogenesis of diabetic nephropathy. We have constructed a gremlin siRNA plasmid and have examined the effect of Gremlin inhibition on the progression of diabetic nephropathy in a mouse model. CD-1 mice underwent uninephrectomy and STZ treatment prior to receiving weekly injections of the plasmid. Inhibition of Gremlin alleviated proteinuria and renal collagen IV accumulation 12 weeks after the STZ injection and inhibited renal cell proliferation and apoptosis. In vitro experiments, using mouse mesangial cells, revealed that the transfect ion of gremlin siRNA plasmid reversed high glucose induced abnormalities, such as increased cell proliferation and apoptosis and increased collagen IV production. The decreased matrix metalloprotease level was partially normalized by transfection with gremlin siRNA plasmid. Additionally, we observed recovery of bone morphogenetic protein-7 signaling activity, evidenced by increases in phosphorylated Smad 5 protein levels. We conclude that inhibition of Gremlin exerts beneficial effects on the diabetic kidney mainly through maintenance of BMP-7 activity and that Gremlin may serve as a novel therapeutic target in the management of diabetic nephropathy

A Fast Hole-Filling Method for Triangular Mesh in Additive Repair

In the triangular meshes obtained in additive repair, it is a challenge to find one single hole-filling method to close all holes and make the filling patches assort with surrounding meshes well with low time complexity, which is mainly caused by the shape complexity and size difference of the various holes, especially in the fields of intelligent manufacturing, 3D measurement, and reverse engineering. Therefore, it is reasonable to adopt different algorithms to fill different types of holes. In this research, a fast hole-filling method for triangular mesh is proposed based on the hole size. First, a group of basic concepts is defined to make them uniform throughout the whole text, followed by the descriptions of hole detection and boundary cleaning. Second, three different algorithms are developed to fill the small-sized, middle-sized, and large-sized holes classified by hole size respectively, which can fill all the detected holes in a fast and proper manner. Finally, two experiments are carried out to verify the efficiency, robustness, and ability to recover the shape of our method. Compared to two state-of-the-art hole-filling methods in the first experiment, the quantitative evaluation results demonstrate that our proposed method is much faster than them with the ability to guarantee the regularity of most filling triangles. The second experiment proves that our method can produce satisfactory filling results by making the filling patches be compatible with surrounding meshes well

Collagen type IVand TGF-βexpression and MMP-2 activity in mouse mesangial cells cultured under high glucose conditions.

<p>Mouse mesangial cells were cultured in RPMI 1640 and transfected with pBAsi mU6 Neo or pBAsi mU6 Neo gremlin siRNA plasmid as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011709#s4" target="_blank">methods</a>. Culture medium was collected for measurement of collagen type IV concentration by radio-immunoassay, and cells were subjected to Western blot analysis to determine MMP-2 and TGF-βexpression levels 48 hours after glucose stimulation. (<b>A</b>) Increased collagen type IV accumulation is observed in the HG group, and gremlin siRNA plasmid transfection significantly inhibits collagen type IV secretion. (<b>B</b>) Compared to the normal glucose control group (NG), TGF-β expression is significantly increased under high glucose conditions, and the HG stimulated TGF-β expression remains the same after gremlin siRNA transfection. (<b>C</b>) Compared with the NG group, MMP-2 activity in culture medium is significantly decreased in the HG and HG+V groups, and this is prevented by transfection with gremlin siRNA plasmid. (* p<0.05, ** p<0.01). Six independent experiments were repeated.</p

BMP-7 activity in mouse mesangial cells transfected with gremlin siRNA plasmid.

<p>Mouse mesangial cells were transfected with pBAsi mU6 Neo or pBAsi mU6 Neo gremlin siRNA plasmid and stimulated with NG and HG. Cells were collected 48 hours after HG stimulation and subjected to RT-PCR and Western blot. BMP-7 mRNA level was found decreased after gremlin siRNA transfection (<b>A & B</b>). The protein levels of BMP-7 and Phos-Smad-5/Smad-5 decreased after 48 hours incubation with high glucose. Transfection with gremlin siRNA plasmid significantly increased the Phos-Smad-5/Smad-5 level (* p<0.01), whereas levels of BMP-7 and Smad-5 remained similar (<b>C, D, E, F, and G</b>). Six independent experiments were repeated.</p

BMP-7 expression in diabetic kidneys assessed by Western blotting.

<p>Compared with non-diabetic control mice (N), mice in the STZ group display similar BMP-7 kidney expression levels at week-1 and week-2. The BMP-7 expression in the STZ group gradually decreased to a significantly lower level at week-12. No significant effect is seen on the expression of BMP-7 in diabetic kidneys by the treatment with gremlin siRNA plasmid. (* p<0.05). N = 6 mice per group.</p

Delivery of gremlin siRNA plasmid into diabetic CD-1 mice post-uninephrectomy.

<p>(<b>A</b>) Gremlin protein expression by western blotting in whole-kidney homogenates at different time points after injection of pBAsi mU6 Neo control vector or pBAsi mU6 Neo gremlin siRNA plasmid, respectively. Compared to those treated with pBAsi mU6 Neo plasmid (STZ group), animals administered pBAsi mU6 Neo gremlin siRNA plasmid (Gremlin siRNA group) show low expression of Gremlin in the kidneys. (<b>B</b>) Immunostaining of kidney sections shows the localization of Gremlin protein after the delivery of plasmids. Marked Gremlin expression is observed in both glomeruli and tubules in the STZ group, which is significantly inhibited by the delivery of gremlin siRNA plasmid. (* p<0.01 vs. non-diabetic control group; #p<0.05 vs. STZ group). Scale bars, 100 µm. N = 6 mice per group.</p

Cell proliferation and apoptosis in diabetic mouse kidneys.

<p>(<b>A</b>) Detection of proliferating cell nuclear antigen (PCNA) by immunoperoxidase staining, in the kidneys of non-diabetic control mice (N), streptozotocin-induced diabetic mice treated with pBAsi mU6 Neo control plasmid (STZ) or pBAsi mU6 Neo gremlin siRNA plasmid (Gremlin siRNA). (<b>B</b> and <b>C</b>) PCNA positive cells in kidneys from the STZ group dramatically increase at week-1 and -2, and pBAsi mU6 Neo gremlin siRNA plasmid treatment significantly reduces PCNA positive cells both in glomeruli and tubules. Proliferating cells are barely seen in all three groups at week 12. (<b>D</b>) Co-immunostaining of diabetic kidney sections with antibodies against PCNA and Gremlin. Intensive Gremlin expression is often seen in the cells with PCNA positive signal. (<b>E, F</b>) <i>In situ</i> TUNEL assay. Apoptotic cells are observed predominantly in tubules in the STZ group at week-12. The number of apoptotic cells is significantly reduced by pBAsi mU6 Neo gremlin siRNA plasmid treatment. (* p<0.01 vs. non-diabetic control group, # p<0.01 vs. STZ group). Scale bars, 100 µm (<b>A, B</b> and <b>E</b>), and 10 µm (<b>D</b>). N = 6 mice per group.</p