The crotonylated and succinylated proteins of jujube involved in phytoplasma-stress responses.

BACKGROUND: Protein posttranslational modifications (PTMs) are fast and early responses to environmental changes, including pathogen infection. Jujube witches' broom (JWB) is a phytoplasma disease causing great economic loss in jujube production. After phytoplasma infection, the transcriptional, translational, and metabolic levels in jujube were activated, enabling it to survive during phytoplasma invasion. However, no study has yet reported on PTMs in jujube. Lysine crotonylation (Kcr) and lysine succinylation (Ksu) have been popular studies in recent years and their function in plant phytoplasma-stress responses remains unclear. RESULTS: Here, 1656 crotonylated and 282 succinylated jujube proteins were first identified under phytoplasma-stress, of which 198 were simultaneously crotonylated and succinylated. Comparative analysis revealed that 656 proteins, 137 crotonylated and 43 succinylated proteins in jujube were regulated by phytoplasma infection, suggesting that Kcr was more universal than Ksu. Kcr differentially expressed proteins (DEPs) were related to ribosomes, photosynthetic and carbon metabolism, while Ksu DEPs were mainly involved in carbon metabolism, the TCA cycle and secondary metabolite biosynthesis. The crosstalk network among proteome, crotonylome and succinylome showed that DEPs related to ribosomal, peroxidases and glutathione redox were enriched. Among them, ZjPOD51 and ZjPHGPX2 significantly increased at the protein and Kcr level under phytoplasma-stress. Notably, 7 Kcr sites were identified in ZjPHGPX2, a unique antioxidant enzyme. After inhibitor nicotinamide (NAM) treatment, GPX enzyme activity in jujube seedlings was reduced. Further, site-directed mutagenesis of key Kcr modification sites K130 and/or K135 in ZjPHGPX2 significantly reduced its activity. CONCLUSIONS: This study firstly provided large-scale datasets of Kcr and Ksu in phytoplasma-infected jujube and revealed that Kcr modification in ZjPHGPX2 positively regulates its activity.

Recent developments in the enzymatic modifications of steroid scaffolds.

Steroids are an important family of bioactive compounds. Steroid drugs are renowned for their multifaceted pharmacological activities and are the second-largest category in the global pharmaceutical market. Recent developments in biocatalysis and biosynthesis have led to the increased use of enzymes to enhance the selectivity, efficiency, and sustainability for diverse modifications of steroids. This review discusses the advancements achieved over the past five years in the enzymatic modifications of steroid scaffolds, focusing on enzymatic hydroxylation, reduction, dehydrogenation, cascade reactions, and other modifications for future research on the synthesis of novel steroid compounds and related drugs, and new therapeutic possibilities.

The genome of Candidatus phytoplasma ziziphi provides insights into their biological characteristics.

Phytoplasmas are obligate cell wall-less prokaryotic bacteria that primarily multiply in plant phloem tissue. Jujube witches' broom (JWB) associated with phytoplasma is a destructive disease of jujube (Ziziphus jujuba Mill.). Here we report the complete 'Candidatus Phytoplasma ziziphi' chromosome of strain Hebei-2018, which is a circular genome of 764,108-base pairs with 735 predicted CDS. Notably, extra 19,825 bp (from 621,995 to 641,819 bp) compared to the previously reported one complements the genes involved in glycolysis, such as pdhA, pdhB, pdhC, pdhD, ackA, pduL and LDH. The synonymous codon usage bias (CUB) patterns by using comparative genomics analysis among the 9 phytoplasmas were similar for most codons. The ENc-GC3s analysis among the 9 phytoplasmas showed a greater effect under the selection on the CUBs of phytoplasmas genes than mutation and other factors. The genome exhibited a strongly reduced ability in metabolic synthesis, while the genes encoding transporter systems were well developed. The genes involved in sec-dependent protein translocation system were also identified.The expressions of nine FtsHs encoding membrane associated ATP-dependent Zn proteases and Mn-SodA with redox capacity in the Ca. P. ziziphi was positively correlated with the phytoplasma concentration. Taken together, the genome will not only expand the number of phytoplasma species and provide some new information about Ca. P. ziziphi, but also contribute to exploring its pathogenic mechanism.

Efficient synthesis of an apremilast precursor and chiral ß-hydroxy sulfones via ketoreductase-catalyzed asymmetric reduction.

Ketoreductase (KRED)-catalyzed asymmetric reduction of prochiral ketones is an attractive method to synthesize chiral alcohols. Herein, two KREDs LfSDR1-V186A/E141I and CgKR1-F92I with complementary stereopreference were identified towards reduction of apremilast prochiral ketone intermediate 1a. LfSDR1-V186A/E141I exhibited >99% conversion and 99.2% ee yielding an apremilast chiral alcohol intermediate ((R)-2a) at 50 g L-1 substrate loading. Furthermore, we investigated the substrate scope of ß-keto sulfones by using LfSDR1-V186A/E141I and CgKR1-F92I to produce both enantiomers of the corresponding ß-hydroxy sulfones, with good-to-excellent conversion (up to >99%) and enantioselectivity (up to 99.9% ee) being obtained in most cases. Finally, the gram-scale synthesis of (R)-2a was performed by employing the crude enzyme of LfSDR1-V186A/E141I and BsGDH to afford the desired enantiomer with >99% conversion, 85.9% isolated yield and 99.2% ee. This study presents a biocatalytic strategy to synthesize chiral ß-hydroxy sulfones.

A base-mediated aerobic oxidative synthesis of cyclopent-2-enol derivatives from doubly activated cyclopropanes and substituted acetonitriles.

We report here that polysubstituted cyclopent-2-enols can be constructed by the one-pot reaction of doubly activated cyclopropanes and α-EWG substituted acetonitriles under mild basic conditions via a domino-ring-opening-cyclization/deacylation/oxidation sequence. Moreover, the synthetic applications of these cyclopent-2-enols have been demonstrated in the late-stage derivatization into functionalized cyclopentapyrimidin-4-ones and 2-hydroxy cyclopentanones with good yields.

Underwater image enhancement based on color correction and complementary dual image multi-scale fusion.

Underwater images often suffer from color cast, poor contrast, and detail loss owing to the scattering and absorption of light in water. To solve these problems, we propose what we believe to be a novel underwater image enhancement method based on color correction and dual image multi-scale fusion. We first use the color correction method to solve the problem of color cast, and we compensate the other two-color channels with the highest mean value color channel; further, all the color channels are dynamically stretched. Next, a complementary dual image multi-scale fusion method is used to improve the contrast, pairs of complementary adaptive gamma correction with weighted distribution enhanced images are used as the two inputs of multi-scale fusion, and appropriate weight maps are selected. Then, a multi-scale detail-sharpening method is used to enhance the image details. Qualitative and quantitative evaluations prove that the proposed method can produce high-quality underwater images. Moreover, the proposed method has relatively high evaluator values compared to the state-of-the-art methods.

Downstream of GA4, PbCYP78A6 participates in regulating cell cycle-related genes and parthenogenesis in pear (Pyrus bretshneideri Rehd.).

BACKGROUND: Parthenocarpy results in traits attractive to both consumers and breeders, and it overcomes the obstacle of self-incompatibility in the fruit set of horticultural crops, including pear (Pyrus bretshneider). However, there is limited knowledge regarding the genetic and molecular mechanisms that regulate parthenogenesis. RESULTS: Here, in a transcriptional comparison between pollination-dependent fruit and GA4-induced parthenocarpy, PbCYP78A6 was identified and proposed as a candidate gene involved in parthenocarpy. PbCYP78A6 is similar to Arabidopsis thaliana CYP78A6 and highly expressed in pear hypanthia. The increased PbCYP78A6 expression, as assessed by RT-qPCR, was induced by pollination and GA4 exposure. The ectopic overexpression of PbCYP78A6 contributed to parthenocarpic fruit production in tomato. The PbCYP78A6 expression coincided with fertilized and parthenocarpic fruitlets development and the expression of fruit development-related genes as assessed by cytological observations and RT-qPCR, respectively. PbCYP78A6 RNA interference and overexpression in pear calli revealed that the gene is an upstream regulator of specific fruit development-related genes in pear. CONCLUSIONS: Our findings indicate that PbCYP78A6 plays a critical role in fruit formation and provide insights into controlling parthenocarpy.

Novel synthesis of fused spiro piperidone-cyclopropanes from cyclopropyl amides and electron-deficient alkenes.

We report here that a series of bridged O,O-ketal fused spiro piperidone-cyclopropane derivatives 3 can be constructed with excellent yields and good diastereoselectivity by the one-pot reaction of 1-acylcyclopropanecarboxamides 1 with electron-deficient alkene 2a (EWG = CHO) via the domino process involving [4 + 2] annulation/intermolecular electrophilic addition/intramolecular cyclization. Furthermore, reactions of 1 with 2b/2c (EWG = CN, COOMe), leading to spiro piperidone-cyclopropane derivatives 4 or 5 by base catalyst selection, were also presented.

Rational design of selective HDAC2 inhibitors for liver cancer treatment: computational insights into the selectivity mechanism through molecular dynamics simulations and QM/MM calculations.

The rational design of selective histone deacetylase 2 (HDAC2) inhibitors is beneficial for the therapeutic treatment of liver cancer, though HDAC2 is highly homologous to HDAC8, which may lead to undesired side effects due to the pan-inhibition towards HDAC2 and HDAC8. To clarify the structural basis of selective inhibition towards HDAC2 over HDAC8, we utilized multiple in silico strategies, including sequence alignment, structural comparison, molecular docking, molecular dynamics simulations, free energy calculations, alanine scanning mutagenesis, pharmacophore modeling, protein contacts atlas analysis and QM/MM calculations to study the binding patterns of HDAC2/8 selective inhibitors. Through the whole process described above, it is found that although HDAC2 has conserved GLY154 and PHE210 that also exist within HDAC8, namely GLY151 and PHE208, the two isoforms exhibit diverse binding modes towards their inhibitors. Typically, HDAC2 inhibitors interact with the Zn2+ ions through the core chelate group, while HDAC8 inhibitors adopt a bent conformation within the HDAC8 pocket that inclines to be in contact with the Zn2+ ions through the terminal hydroxamic acid group. In summary, our data comprehensively elucidate the selectivity mechanism towards HDAC2 over HDAC8, which would guide the rational design of selective HDAC2 inhibitors for liver cancer treatment.

A Study on Seizure Detection of EEG Signals Represented in 2D.

A seizure is a neurological disorder caused by abnormal neuronal discharges in the brain, which severely reduces the quality of life of patients and often endangers their lives. Automatic seizure detection is an important research area in the treatment of seizure and is a prerequisite for seizure intervention. Deep learning has been widely used for automatic detection of seizures, and many related research works decomposed the electroencephalogram (EEG) raw signal with a time window to obtain EEG signal slices, then performed feature extraction on the slices, and represented the obtained features as input data for neural networks. There are various methods for EEG signal decomposition, feature extraction, and representation, and most of the studies have been based on fixed hardware resources for the design of the scheme, which reduces the adaptability of the scheme in different application scenarios and makes it difficult to optimize the algorithms in the scheme. To address the above issues, this paper proposes a deep learning-based model for seizure detection, mainly characterized by the two-dimensional representation of EEG features and the scalability of neural networks. The model modularizes the main steps of seizure detection and improves the adaptability of the model to different hardware resource constraints, in order to increase the convenience of the algorithm optimization or the replacement of each module. The proposed model consists of five parts, and the model was tested using two epilepsy datasets separately. The experimental results showed that the proposed model has strong generality and good classification accuracy for seizure detection.

Jasmonic Acid and Ethylene Participate in the Gibberellin-Induced Ovule Programmed Cell Death Process in Seedless Pear '1913' (Pyrus hybrid).

Seedless fruit is a feature appreciated by consumers. The ovule abortion process is highly orchestrated and controlled by numerous environmental and endogenous signals. However, the mechanisms underlying ovule abortion in pear remain obscure. Here, we found that gibberellins (GAs) have diverse functions during ovules development between seedless pear '1913' and seeded pear, and that GA4+7 activates a potential programmed cell death process in '1913' ovules. After hormone analyses, strong correlations were determined among jasmonic acid (JA), ethylene and salicylic acid (SA) in seedless and seeded cultivars, and GA4+7 treatments altered the hormone accumulation levels in ovules, resulting in significant correlations between GA and both JA and ethylene. Additionally, SA contributed to ovule abortion in '1913'. Exogenously supplying JA, SA or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid promoted 'Bartlett' seed death. The regulatory mechanism in which ethylene controls ovule death has been demonstrated; therefore, JA's role in regulating '1913' ovule abortion was investigated. A further study identified that the JA signaling receptor MYC2 bound the SENESCENCE-ASSOCIATED 39 promoter and triggered its expression to regulate ovule abortion. Thus, we established ovule abortion-related relationships between GA and the hormones JA, ethylene and SA, and we determined their synergistic functions in regulating ovule death.

Semi-synthesis and biological evaluation of flavone hybrids as multifunctional agents for the potential treatment of Alzheimer's disease.

7-O-galloyltricetiflavan (GTF), a natural flavonoid, is known to exert anti-oxidation and neuroprotective activity, which are related to the prevention of Alzheimer's disease (AD). In this study, three series of GTF hybrids have been designed, synthesized and evaluated as multifunctional agents for treatment AD. The biological assays indicated that most of them showed strong inhibitory effect on self-induced ß-amyloid (Aß) aggregation, and a significant ability to inhibit ChEs. Among them, compound A15 exhibited best inhibition of Aß aggregation (78.81% at 20 µM), potent AChE inhibitory potencies (IC50, 0.56 µM), and compound C4 presented the highest ability to inhibit BuChE (IC50, 5.77 µM). Furthermore, kinetic, molecular modeling and molecular dynamics studies revealed that A15 and C4 could interact with the catalytic active site of AChE and BuChE, respectively. In addition, compounds A15 and C4 could cross the blood-brain barrier in vitro. More importantly, A15 and C4 also showed excellent neuroprotective activities against H2O2-induced human neuroblastoma SH-SY5Y cells damage and nearly no toxicity on SH-SY5Y cells. All of these outstanding in vitro results indicated A15 and C4 as the leading structure worthy of further investigation.

Old yellow enzymes: structures and structure-guided engineering for stereocomplementary bioreduction.

Since the first discovery of old yellow enzyme 1 (OYE1) from Saccharomyces pastorianus in 1932, biocatalytic asymmetric reduction of activated alkenes by OYEs has become a valuable reaction in organic synthesis. To access stereocomplementary C=C-bond bioreduction, the mining of novel OYEs and especially the protein engineering of existing OYEs have been performed, which successfully achieved the stereocomplementary reduction in several cases and further raise the potential of applications. In this review, we analyzed the structures, active sites, and substrate recognition of OYEs, which are the bases for their substrate specificity and stereospecificity. Sequence similarity network of OYEs superfamily was also constructed to investigate the scope of characterized OYEs. The structure-guided engineering to switch the stereoselectivity of OYEs and thus access stereocomplementary bioreduction over the last decade (2009-2020) was then reviewed and discussed, which might give new insights into the mining and engineering of related biocatalysts. KEY POINTS: • The sequence similarity network of OYEs superfamily was constructed and annotated. • The structures and active sites of OYEs from different classes were compared. • "Left/right" binding mode was used to explain the stereopreferences of OYEs. • Structure-guided engineering of OYEs to switch their stereoselectivity was reviewed.

2,4-D-induced parthenocarpy in pear is mediated by enhancement of GA4 biosynthesis.

Parthenocarpy, the productions of seedless fruit without pollination or fertilization, is a potentially desirable trait in many commercially grown fruits, especially in pear, which is self-incompatible. Phytohormones play important roles in fruit set, a process crucial for parthenocarpy. In this study, 2,4-dichlorophenoxyacetic acid (2,4-D), an artificially synthesized plant growth regulator with functions similar to auxin, was found to induce parthenocarpy in pear. Histological observations revealed that 2,4-D promoted cell division and expansion, which increased cortex thickness, but the effect was weakened by paclobutrazol (PAC), a gibberellin (GA) biosynthesis inhibitor. Phenotypic differences in pear may therefore be due to different GA contents. Hormone testing indicated that 2,4-D mainly induced the production of bioactive GA4 , rather than GA3. Three key oxidase genes function in the GA biosynthetic pathway: GA20ox, GA3ox and GA2ox. In a pear group treated with only 2,4-D, PbGA20ox2-like and PbGA3ox-1 were significantly upregulated. When treated with 2,4-D supplemented with PAC, however, expression levels of these genes were significantly downregulated. Additionally, PbGA2ox1-like and PbGA2ox2-like expression levels were significantly downregulated in pear treated with either 2,4-D only or 2,4-D supplemented with PAC. We thus hypothesize that 2,4-D can induce parthenocarpy by enhancing GA4 biosynthesis.

Association of apolipoprotein E genotypes with epilepsy risk: A systematic review and meta-analysis.

OBJECTIVE: The objective of this study was to identify the association between certain genotypes or alleles of the APOE (Apolipoprotein E) gene and the epilepsy risk. METHODS: All studies on human APOE genotypes associated with epilepsy were included. Separate meta-analyses were conducted between the patients with epilepsy and the control group from the following three aspects: ε4 carriers or ε2 carriers vs ε3/ε3 (the ε2/ε4 genotype was excluded), ε4 carriers vs ε2 carriers, and five genotypes vs ε3/ε3. The subgroup analysis was conducted on the ethnicity, the control group was healthy or not, and type of epilepsy. RESULTS: Nine studies with 2210 individuals were included. Compared with ε3/ε3 genotype, ε4 carriers increased the epilepsy risk (odds ratios [ORs]: 1.27; 95% confidence intervals [CI]: 1.01 to 1.59; P = 0.042), while ε2 carriers had no association with epilepsy risk (OR: 0.88; 95% CI: 0.66 to 1.18; P = 0.184). The risk of epilepsy was 1.45 times greater in ε4 carriers compared with ε2 carriers (OR: 1.45; 95% CI: 1.02 to 2.04; P = 0.037). When the number of APOE ε4 allele increased, the ORs increased progressively (no ε4 alleles, OR: 0.88, 95% CI: 0.66 to 1.18; one ε4 allele, OR: 1.25, 95% CI: 0.99 to 1.57; two ε4 alleles, OR: 1.84, 95% CI: 0.83 to 4.10). Apolipoprotein E ε4 carriers had a higher epilepsy risk in the population without primary diseases (OR: 1.43; 95% CI: 1.09 to 1.88), and a higher risk in Asian populations (OR: 1.67; 95% CI: 1.12 to 2.49). CONCLUSIONS: Apolipoprotein E ε4 allele genotype was associated with an increased epilepsy risk, which was more prominent in the Asian and the population without primary diseases. These findings may be used to guide the directions of prevention and treatment on epilepsy. Larger clinical studies are needed.

Visual Measurement of Water Level under Complex Illumination Conditions.

Image-based water level measurement is a visual-sensing technique which automatically inspects the reading of the water line via image processing instead of the human eye. It can be realized easily on an existing video surveillance system and has advantages like low cost, non-contact, as well as results that are verifiable. It has the potential to be widely used in flood and waterlogging monitoring, while facing the challenge that water-line detection under complex natural or artificial illumination conditions is quite difficult in field applications. To handle this problem, a method is proposed assuming that the water line is generally located on the row with the largest local change of gray or edge features in the image of the water gauge. The water line is determined by coarse-to-fine detection of the position of the maximum mean difference (MMD) of the horizontal projections of gray and edge images. Image-based flow-level measurement systems were developed at two measurement sites. In situ comparative experiments were conducted with the float-type stage gauge and other image-based methods. The results show that the fusion of gray and edge features can overcome the shortcomings of single feature methods under complex illumination conditions such as dim light, glares, shadows and artificial night lighting. A coarse-to-fine strategy utilizes the periodicity of the surface pattern distribution of the standard bicolor water gauge, which improves the reliability of water-line detection. The resolution and accuracy of water-level measurement are 1 mm and 1 cm, respectively. In particular, the MMD value is efficient at identifying extremely unfavorable conditions and reducing gross errors.

Real-Time Water Surface Object Detection Based on Improved Faster R-CNN.

In this paper, we consider water surface object detection in natural scenes. Generally, background subtraction and image segmentation are the classical object detection methods. The former is highly susceptible to variable scenes, so its accuracy will be greatly reduced when detecting water surface objects due to the changing of the sunlight and waves. The latter is more sensitive to the selection of object features, which will lead to poor generalization as a result, so it cannot be applied widely. Consequently, methods based on deep learning have recently been proposed. The River Chief System has been implemented in China recently, and one of the important requirements is to detect and deal with the water surface floats in a timely fashion. In response to this case, we propose a real-time water surface object detection method in this paper which is based on the Faster R-CNN. The proposed network model includes two modules and integrates low-level features with high-level features to improve detection accuracy. Moreover, we propose to set the different scales and aspect ratios of anchors by analyzing the distribution of object scales in our dataset, so our method has good robustness and high detection accuracy for multi-scale objects in complex natural scenes. We utilized the proposed method to detect the floats on the water surface via a three-day video surveillance stream of the North Canal in Beijing, and validated its performance. The experiments show that the mean average precision (MAP) of the proposed method was 83.7%, and the detection speed was 13 frames per second. Therefore, our method can be applied in complex natural scenes and mostly meets the requirements of accuracy and speed of water surface object detection online.

Domain Adaptation and Adaptive Information Fusion for Object Detection on Foggy Days.

Foggy days pose many difficulties for outdoor camera surveillance systems. On foggy days, the optical attenuation and scattering effects of the medium significantly distort and degenerate the scene radiation, making it noisy and indistinguishable. Aiming to solve this problem, in this paper we propose a novel object detection method that has the ability to exploit the information in the color and depth domains. To prevent the error propagation problem, we clean the depth information before the training process and remove false samples from the database. A domain adaptation strategy is employed to adaptively fuse the decisions obtained in the color and depth domains. In the experiments, we evaluate the contribution of the depth information for object detection on foggy days. Moreover, the advantages of the multiple-domain adaptation strategy are experimentally demonstrated via comparison with other methods.

Underwater Object Segmentation Based on Optical Features.

Underwater optical environments are seriously affected by various optical inputs, such as artificial light, sky light, and ambient scattered light. The latter two can block underwater object segmentation tasks, since they inhibit the emergence of objects of interest and distort image information, while artificial light can contribute to segmentation. Artificial light often focuses on the object of interest, and, therefore, we can initially identify the region of target objects if the collimation of artificial light is recognized. Based on this concept, we propose an optical feature extraction, calculation, and decision method to identify the collimated region of artificial light as a candidate object region. Then, the second phase employs a level set method to segment the objects of interest within the candidate region. This two-phase structure largely removes background noise and highlights the outline of underwater objects. We test the performance of the method with diverse underwater datasets, demonstrating that it outperforms previous methods.

Total Synthesis of Lycopodium Alkaloids Palhinine A and Palhinine D.

The first total syntheses of Lycopodium alkaloids palhinine A, palhinine D, and their C3-epimers have been divergently achieved through the use of a connective transform to access a pivotal hexacyclic isoxazolidine precursor. A microwave-assisted regio- and stereoselective intramolecular nitrone-alkene cycloaddition was tactically orchestrated as a key step to install the crucial 10-oxa-1-azabicyclo[5.2.1]decane moiety embedded in the conformationally rigid isotwistane framework, demonstrating the feasibility of constructing the highly strained medium-sized ring by introduction of an oxygen bridging linker to relieve the transannular strain in the polycyclic scaffold. Subsequent N-O bond cleavage provided the synthetically challenging nine-membered azonane ring system bearing the requisite C3 hydroxyl group. Late-stage transformations featuring a chemo- and stereoselective reduction of the pentacyclic ß-diketone secured the availability of our target molecules.