Flower color polymorphism of a wild Iris on the Qinghai-Tibet plateau.

BACKGROUND: Flower color plays a crucial role in attracting pollinators and facilitating environmental adaptation. Investigating the causes of flower color polymorphism and understanding their potential effects on both ecology and genetics can enhance our understanding of flower color polymorphism in wild plant. RESULTS: In this study, we examined the differences of potential male and female fitness between purple- and yellow- flower individuals in Iris potaninii on the Qinghai-Tibet Plateau, and screened key genes and positively selective genes involved in flower color change. Our results showed that yellow flower exhibited a higher pollen-to-ovule ratio. Yellow flowers were derived from purple flowers due to the loss of anthocyanins, and F3H could be an essential gene affecting flower color variation though expression regulation and sequence polymorphism in this species. Furthermore, our findings suggest that genes positively selected in yellow-flowered I. potaninii might be involved in nucleotide excision repair and plant-pathogen interactions. CONCLUSIONS: These results suggest that F3H induces the flower color variation of Iris potaninii, and the subsequent ecological and additive positive selection on yellow flowers may further enhance plant adaptations to alpine environments.

Glutathione-responsive PROTAC for targeted degradation of ERα in breast cancer cells.

ERα (estrogen receptor-α)-targeting PROTACs (PROteolysis TArgeting Chimeras) have emerged as a novel and promising modality for breast cancer therapeutics. However, ERα PROTACs-induced degradation in normal tissues raises concerns about potential off-tissue toxicity. Tumor microenvironment-responsive strategy provides potential for specific control of the PROTAC's on-target degradation activity. The glutathione (GSH) level has been reported to be significantly increased in tumor cells. Here, we designed a GSH-responsive ERα PROTAC, which is generated by conjugating an o-nitrobenzenesulfonyl group to the hydroxyl group of VHL-based ERα PROTAC through a nucleophilic substitution reaction. The o-nitrobenzenesulfonyl group as a protecting group blocks the bioactivity of ERα PROTAC (ER-P1), and that can be specifically recognized and removed by highly abundant GSH in cancer cells. Consequently, the GSH-responsive ERα PROTAC (GSH-ER-P1) exhibits significantly enhanced degradation of ERα in cancer cells compared to that in normal cells, leading to a remarkable inhibition of breast cancer cell proliferation and less toxic effects on normal cells. This study provides a potentially valuable strategy for breast cancer treatment using tumor microenvironment-responsive PROTACs.

Selective degradation of BRD4 suppresses lung cancer cell proliferation using GSH-responsive PROTAC precursors.

BRD4,as a transcriptional and epigenetic regulator to mediate cellular functions, plays an important role in cancer development.Targeting BRD4 with conventional inhibitors in cancer therapy requires high doses, which often leads to off-target and adverse effects. BRD4-targeted proteolysis-targeting chimeras (PROTACs) can catalytically degrade BRD4 utilizing the endogenous proteasome system, and exhibit promising anti-tumor activity. However, most of the developed PROTACs are non-cancer specific and relatively toxic towards normal cells, limiting their practical applications in cancer treatment. By taking advantage of higher glutathione (GSH) levels in cancer cells than that in normal cells, we developed several GSH-responsive PROTAC precursors 1a-c via the attachment of a GSH-trigger unit on the hydroxyl group of the VHL (von Hippel-Lindau) ligand for the recruitment of E3 ligase. Among the precursors, 1a can be efficiently activated by the innately higher concentrations of GSH in lung cancer cells (A549 and H1299) to release active PROTAC 1, degrading intracellular BRD4 and resulting in cytotoxicity, which is confirmed by mechanistic investigation. On the other hand, 1a cannot be efficiently triggered in normal lung cells (WI38 and HULEC-5a) containing lower levels of GSH, therefore reducing the adverse effects on normal cells. This work provides an alternative proof of concept approach for developing stimuli-responsive PROTAC precursors, and affords a novel insight to improve the selectivity and minimize the adverse effects of current PROTACs, hence enhancing their clinical potential.

Hydrogen Peroxide-Inducible PROTACs for Targeted Protein Degradation in Cancer Cells.

Proteolysis-targeting chimeras (PROTACs) provide a powerful technique to degrade targeted proteins utilizing the cellular ubiquitin-proteasome system. The major concern is the host toxicity resulting from their poor selectivity. Inducible PROTACs responding to exogenous stimulus, such as light, improve their specificity, but it is difficult for photo-activation in deep tissues. Herein, we develop H2 O2 -inducible PROTAC precursors 2/5, which can be activated by endogenous H2 O2 in cancer cells to release the active PROTACs 1/4 to effectively degrade targeted proteins. This results in the intended cytotoxicity towards cancer cells while targeted protein in normal cells remains almost unaffected. The higher Bromodomain-containing protein 4 (BRD4) degradation activity and cytotoxicity of 2 towards cancer cells is mainly due to the higher endogenous concentration of H2 O2 in cancer cells (A549 and H1299), characterized by H2 O2 -responsive fluorescence probe 3. Western blot assays and cytotoxicity experiments demonstrate that 2 degrades BRD4 more effectively and is more cytotoxic in H2 O2 -rich cancer cells than in H2 O2 -deficient normal cells. This method is also extended to estrogen receptor (ER)-PROTAC precursor 5, showing H2 O2 -dependent ER degradation ability. Thus, we establish a novel strategy to induce targeted protein degradation in a H2 O2 -dependent way, which has the potential to improve the selectivity of PROTACs.

Sequential Order-Aware Coding-Based Robust Subspace Clustering for Human Action Recognition in Untrimmed Videos.

Human action recognition (HAR) is one of most important tasks in video analysis. Since video clips distributed on networks are usually untrimmed, it is required to accurately segment a given untrimmed video into a set of action segments for HAR. As an unsupervised temporal segmentation technology, subspace clustering learns the codes from each video to construct an affinity graph, and then cuts the affinity graph to cluster the video into a set of action segments. However, most of the existing subspace clustering schemes not only ignore the sequential information of frames in code learning, but also the negative effects of noises when cutting the affinity graph, which lead to inferior performance. To address these issues, we propose a sequential order-aware coding-based robust subspace clustering (SOAC-RSC) scheme for HAR. By feeding the motion features of video frames into multi-layer neural networks, two expressive code matrices are learned in a sequential order-aware manner from unconstrained and constrained videos, respectively, to construct the corresponding affinity graphs. Then, with the consideration of the existence of noise effects, a simple yet robust cutting algorithm is proposed to cut the constructed affinity graphs to accurately obtain the action segments for HAR. The extensive experiments demonstrate the proposed SOAC-RSC scheme achieves the state-of-the-art performance on the datasets of Keck Gesture and Weizmann, and provides competitive performance on the other 6 public datasets such as UCF101 and URADL for HAR task, compared to the recent related approaches.

Differences in pseudogene evolution contributed to the contrasting flavors of turnip and Chiifu, two Brassica rapa subspecies.

Pseudogenes are important resources for investigation of genome evolution and genomic diversity because they are nonfunctional but have regulatory effects that influence plant adaptation and diversification. However, few systematic comparative analyses of pseudogenes in closely related species have been conducted. Here, we present a turnip (Brassica rapa ssp. rapa) genome sequence and characterize pseudogenes among diploid Brassica species/subspecies. The results revealed that the number of pseudogenes was greatest in Brassica oleracea (CC genome), followed by B. rapa (AA genome) and then Brassica nigra (BB genome), implying that pseudogene differences emerged after species differentiation. In Brassica AA genomes, pseudogenes were distributed asymmetrically on chromosomes because of numerous chromosomal insertions/rearrangements, which contributed to the diversity among subspecies. Pseudogene differences among subspecies were reflected in the flavor-related glucosinolate (GSL) pathway. Specifically, turnip had the highest content of pungent substances, probably because of expansion of the methylthioalkylmalate synthase-encoding gene family in turnips; these genes were converted into pseudogenes in B. rapa ssp. pekinensis (Chiifu). RNA interference-based silencing of the gene encoding 2-oxoglutarate-dependent dioxygenase 2, which is also associated with flavor and anticancer substances in the GSL pathway, resulted in increased abundance of anticancer compounds and decreased pungency of turnip and Chiifu. These findings revealed that pseudogene differences between turnip and Chiifu influenced the evolution of flavor-associated GSL metabolism-related genes, ultimately resulting in the different flavors of turnip and Chiifu.

Philanthropic sales in live-streaming shopping: The impact of online interaction on consumer impulse buying.

As philanthropic sales via live-streaming shopping have played an important role in alleviating the huge backlog of agricultural products during the outbreak of the COVID-19 pandemic, this paper aims to study how online interaction in philanthropic marketing exerts influence on consumer impulse buying behaviors. We empirically explore four major dimensions of online interactions in philanthropic live-streaming sales, i.e., the live streamers' image, the herd effect of consumers, the responsiveness of sellers, and the mutual trust between consumers. The results reveal that the herd effect of consumers and the responsiveness of sellers could promote consumers' empathy ability toward the growers of the products sold lively, whereas the live streamers' image and the mutual trust between consumers have little effect on empathy promotions. Meanwhile, both the consumers' empathy ability and the live streamers' image positively affect consumers' impulse buying behavior, which suggests a partial moderating role of consumers' empathy ability. Lastly, by taking both social and business perspectives, we provide managerial implications for improving the effectiveness and efficiency of philanthropic live-streaming sales to alleviate social and economic pressure in emergencies.

Skin/muscle incision and retraction regulates the persistent postoperative pain in rats by the Epac1/PKC-ßII pathway.

Persistent postoperative pain causes influence the life quality of many patients. The Epac/PKC pathway has been indicated to regulate mechanical hyperalgesia. The present study used skin/muscle incision and retraction (SMIR) to induce postoperative pain in rats and evaluated the Epac/PKC pathway in postoperative pain. Mechanical allodynia was assessed by paw withdrawal threshold before and after incision. The levels of Epac, PKC, proinflammatory cytokines, and blood-nerve barrier-related proteins were assessed using Western blotting. We found that SMIR induced the activation of the Epac/PKC pathway, mechanical allodynia, and upregulation of Glut1, VEGF, and PGP9.5 proteins in dorsal root ganglia. Under the influence of agonists of Epac/PKC, normal rats showed mechanical allodynia and increased Glut1, VEGF, and PGP9.5 proteins. After inhibition of Epac1 in rats with SMIR, mechanical allodynia was alleviated, and proinflammatory cytokines and Glut1, VEGF, and PGP9.5 proteins were decreased. Moreover, dorsal root ganglia neurons showed abnormal proliferation under the activation of the Epac/PKC pathway. Using Captopril to protect vascular endothelial cells after SMIR had a positive effect on postoperative pain. In conclusion, SMIR regulates the persistent postoperative pain in rats by the Epac/PKC pathway.

C-terminal glutamine acts as a C-degron targeted by E3 ubiquitin ligase TRIM7.

The exposed N-terminal or C-terminal residues of proteins can act, in cognate sequence contexts, as degradation signals (degrons) that are targeted by specific E3 ubiquitin ligases for proteasome-dependent degradation by N-degron or C-degron pathways. Here, we discovered a distinct C-degron pathway, termed the Gln/C-degron pathway, in which the B30.2 domain of E3 ubiquitin ligase TRIM7 (TRIM7B30.2) mediates the recognition of proteins bearing a C-terminal glutamine. By determining crystal structures of TRIM7B30.2 in complexes with various peptides, we show that TRIM7B30.2 forms a positively charged binding pocket to engage the "U"-shaped Gln/C-degron. The four C-terminal residues of a substrate play an important role in C-degron recognition, with C-terminal glutamine as the principal determinant. In vitro biochemical and cellular experiments were used to further analyze the substrate specificity and selective degradation of the Gln/C-degron by TRIM7.

Multiple lines of evidence supports the two varieties of Halenia elliptica (Gentianaceae) as two species.

Delimiting species requires multiple sources of evidence. Here, we delimited two varieties of Halenia elliptica (Gentianaceae) using several lines of evidence, including morphological traits and mating system in a sympatric population, phylogenetic relationships based on nrITS and cpDNA (rpl16) data, and complete chloroplast genome sequences. Comparative analysis of 21 morphological traits clearly separates the two varieties of H. elliptica. Examination of the flowering process and pollination treatments indicate that H. elliptica var. grandiflora produces seeds via outcrossing, whereas H. elliptica var. elliptica produces seeds via mixed mating. Furthermore, hand-pollinated hybridization of the two varieties produced no seeds. Observations of pollinators showed that when bees began a pollination bout on H. elliptica var. grandiflora they preferred to continue pollinating this variety; however, when they began a pollination bout on H. elliptica var. elliptica, they showed no preference for either variety. Phylogenetic analysis confirmed the monophyly of H. elliptica, which was further divided into two monophyletic clades corresponding to the two varieties. A large number of variants from the chloroplast genomes reflected remarkable genetic dissimilarities between the two varieties of H. elliptica. We recommend that the two varieties of H. elliptica should be revised as two species (H. elliptica and H. grandiflora). Our findings indicate that H. elliptica varieties may have split into two separate species due to a shift in mating system, changes in flowering phenology and/or post-pollination reproductive isolation.

A statistical approach to secure health care services from DDoS attacks during COVID-19 pandemic.

Over the course of this year, more than a billion people have been afflicted by the COVID-19 outbreak. As long as individuals maintain their social distance, they should all be secure at this period. Because of this, there has been a rise in the usage of different online technologies, but at the same time, there has also been a rise in the likelihood of different cyber-attacks. A DDoS assault, the most prevalent and deadly of them all, impairs an online resource for its users. Thus, in this paper, we have proposed a filtering approach that can work efficiently in the COVID-19 scenario and detect the DDoS attack. We base our proposed approach on statistical methods like packet score and entropy variation for the identification of DDoS attack traffic. We have implemented our proposed approach on Omnet++ and for testing its efficiency we have checked it with different test cases. Our proposed approach detects the DDoS attack traffic with 96% accuracy and can also clearly have differentiated the DDoS attack traffic from the flash crowd.

Molecular basis for recognition of Gly/N-degrons by CRL2ZYG11B and CRL2ZER1.

N-degron pathways are a set of proteolytic systems that target the N-terminal destabilizing residues of substrates for proteasomal degradation. Recently, the Gly/N-degron pathway has been identified as a new branch of the N-degron pathway. The N-terminal glycine degron (Gly/N-degron) is recognized by ZYG11B and ZER1, the substrate receptors of the Cullin 2-RING E3 ubiquitin ligase (CRL2). Here we present the crystal structures of ZYG11B and ZER1 bound to various Gly/N-degrons. The structures reveal that ZYG11B and ZER1 utilize their armadillo (ARM) repeats forming a deep and narrow cavity to engage mainly the first four residues of Gly/N-degrons. The α-amino group of the Gly/N-degron is accommodated in an acidic pocket by five conserved hydrogen bonds. These structures, together with biochemical studies, decipher the molecular basis for the specific recognition of the Gly/N-degron by ZYG11B and ZER1, providing key information for future structure-based chemical probe design.

Uncovering the role of a positive selection site of wax ester synthase/diacylglycerol acyltransferase in two closely related Stipa species in wax ester synthesis under drought stress.

Natural selection drives local adaptations of species to biotic or abiotic environmental stresses. As a result, adaptive phenotypic divergence can evolve among related species living in different habitats. However, the genetic foundation of this divergence process remains largely unknown. Two closely related alpine grass species, Stipa capillacea and Stipa purpurea, are distributed in different rainfall regions of northern Tibet. Here, we analyzed the drought tolerance of these two closely related Stipa species, and found that S. purpurea was more resistance to drought stress than S. capillacea. To further understand the genetic diversity behind their adaptation to drought environments, a comprehensive gene repertoire was generated using PacBio isoform and Illumina RNA sequencing technologies. Bioinformatics analyses revealed that differential transcripts were mainly enriched in the wax synthetic pathway, and a threonine residue at position 239 of WSD1 was identified as having undergone positive selection in S. purpurea. Using heterologous expression in the Saccharomyces cerevisiae mutant H1246, site-directed mutagenesis studies demonstrated that a positive selection site results in changes to the wax esters profile. This difference may play an important role in S. purpurea in response to drought conditions, indicating that S. purpurea has evolved specific strategies involving its wax biosynthetic pathway as part of its long-term adaptation to the Qinghai-Tibet Plateau.

Development of Microsatellite Markers for a Dioecious Herpetospermum pedunculosum (Cucurbitaceae).

Understanding the evolution of flower diversity is a central topic in plant evolutionary ecology, and natural selection on floral traits via male fitness could be estimated quantitatively using microsatellites. Here, based on RNA sequencing, we developed simple sequence repeat primers and verified polymorphisms in 2 wild populations of Herpetospermum pedunculosum (Cucurbitaceae), a dioecious annual plants native to the Himalaya Mountains. A total of 131 paired primers were designed; 15 paired primers were found to be polymorphic, with the expected heterozygosity varying between 0.280 and 0.767. We also identified 58 genotypes in 20 plants from the 2 populations. Conclusively, these primers could be effective in examining male fitness and population genetic structure of H pedunculosum in future studies.

A Splice Variant of BrrWSD1 in Turnip (Brassica rapa var. rapa) and Its Possible Role in Wax Ester Synthesis under Drought Stress.

Cuticular wax accumulation in plants contributes to drought tolerance. Here, we compared the drought levels on two varieties with different genotypes in turnip (Brassica rapa var. rapa) and found that the drought tolerance was higher in the waxy KTRG-B48a than in the wax-free KTRG-B48b. A combination of PacBio and Illumina sequencing analyses revealed that differential transcripts were mainly enriched in the wax synthesis pathway, and a splice variant (BrrWSD1-X2) was identified in the waxy KTRG-B48a. BrrWSD1-X2 had a stronger ability to synthesize wax esters than BrrWSD1-X1 using heterologous expression in yeast (Saccharomyces cerevisiae) mutant H1246a. Then, we speculated that the T to C transversion of the third intron and the higher number of TA repeats in the third intron of BrrWSD1 DNA in the waxy KTRG-B48a may result in a lower efficiency of splicing recognition of the third intron, resulting in the emergence of BrrWSD1-X2 in waxy varieties.

A machine learning model to classify aortic dissection patients in the early diagnosis phase.

Aortic dissection is one of the most clinical-challenging and life-threatening cardiovascular diseases associated with high morbidity and mortality. Aortic dissection requires fast diagnosis and timely therapy. Any delay or misdiagnosis can cause severe consequence to aortic dissection patients with even higher mortality. To better help physicians identify the potential dissection within the scope of all misdiagnosed patients, this paper describes a method which is developed with data mining methods for aortic dissection patient classification and prediction in the phase of early diagnosis. Various machine learning algorithms were used to build the models which were all trained and tested on the patient dataset with cross validation. Among them, Bayesian Network model achieved the best performance by predicting at a precision rate of 84.55% with Area Under the Curve (AUC) value of 0.857. On this basis, the Bayesian Network model can help physicians better with early diagnosis of aortic dissection in clinical practice. Beyond this study, more data from diverse regions and the internal pathology can be crucial to further build a universal model with broader predictive power.

Cell number explains the intraspecific spur-length variation in an Aquilegia species.

Variations of nectar spur length allow pollinators to utilize resources in novel ways, leading to the different selective pressures on spurs and allowing taxa to diversify. However, the mechanisms underlying spur length variation remain unclear. Interspecific comparisons of spur length suggest that both cell division and anisotropic expansion could explain the changes of spur length, and that hormone-related genes contribute to the process of spur formation. In contrast, little is known about intraspecific spur length variation. In Aquilegia rockii, spur length varies strikingly, ranging from 1 mm to 18 mm. To examine the potential mechanisms underlying spur length variation in A. rockii, we observed cell morphology and analyzed RNA-seq of short- and long-spurred flowers. Scanning electron microscopy revealed that at two positions on spurs there were no differences in either cell density or cell anisotropy between short- and long-spurred flowers, suggesting that in A. rockii changes in cell number may explain variations in spur length. In addition, we screened transcriptomes of short- and long-spurred flowers for differentially expressed genes; this screen identified several genes linked to cell division (e.g., F-box, CDKB2-2, and LST8), a finding which is consistent with our analysis of the cellular morphology of spurs. However, we did not find any highly expressed genes involved in the hormone pathway in long-spurred flowers. In contrast to previous hypotheses that anisotropic cell expansion leads to interspecific spur variation in Aquilegia, our results suggest that cell number changes and related genes are mainly responsible for spur length variations of A. rockii. Furthermore, the underlying mechanisms of similar floral traits in morphology may be quite different, enriching our understanding of the mechanisms of flower diversity in angiosperms.

An Exception Handling Approach for Privacy-Preserving Service Recommendation Failure in a Cloud Environment.

Service recommendation has become an effective way to quickly extract insightful information from massive data. However, in the cloud environment, the quality of service (QoS) data used to make recommendation decisions are often monitored by distributed sensors and stored in different cloud platforms. In this situation, integrating these distributed data (monitored by remote sensors) across different platforms while guaranteeing user privacy is an important but challenging task, for the successful service recommendation in the cloud environment. Locality-Sensitive Hashing (LSH) is a promising way to achieve the abovementioned data integration and privacy-preservation goals, while current LSH-based recommendation studies seldom consider the possible recommendation failures and hence reduce the robustness of recommender systems significantly. In view of this challenge, we develop a new LSH variant, named converse LSH, and then suggest an exception handling approach for recommendation failures based on the converse LSH technique. Finally, we conduct several simulated experiments based on the well-known dataset, i.e., Movielens to prove the effectiveness and efficiency of our approach.

Network Community Detection Based on the Physarum-Inspired Computational Framework.

Community detection is a crucial and essential problem in the structure analytics of complex networks, which can help us understand and predict the characteristics and functions of complex networks. Many methods, ranging from the optimization-based algorithms to the heuristic-based algorithms, have been proposed for solving such a problem. Due to the inherent complexity of identifying network structure, how to design an effective algorithm with a higher accuracy and a lower computational cost still remains an open problem. Inspired by the computational capability and positive feedback mechanism in the wake of foraging process of Physarum, a kind of slime, a general Physarum-based computational framework for community detection is proposed in this paper. Based on the proposed framework, the inter-community edges can be identified from the intra-community edges in a network and the positive feedback of solving process in an algorithm can be further enhanced, which are used to improve the efficiency of original optimization-based and heuristic-based community detection algorithms, respectively. Some typical algorithms (e.g., genetic algorithm, ant colony optimization algorithm, and Markov clustering algorithm) and real-world datasets have been used to estimate the efficiency of our proposed computational framework. Experiments show that the algorithms optimized by Physarum-inspired computational framework perform better than the original ones, in terms of accuracy and computational cost.

Constructing Repairable Meta-Structures of Ultra-Broad-Band Electromagnetic Absorption from Three-Dimensional Printed Patterned Shells.

Ultra-broad-band electromagnetic absorption materials and structures are increasingly attractive for their critical role in competing with the advanced broad-band electromagnetic detection systems. Mechanically soft and weak wax-based materials composites are known to be insufficient to serve in practical electromagnetic absorption applications. To break through such barriers, here we developed an innovative strategy to enable the wax-based composites to be robust and repairable meta-structures by employing a three-dimensional (3D) printed polymeric patterned shell. Because of the integrated merits from both the dielectric loss wax-based composites and mechanically robust 3D printed shells, the as-fabricated meta-structures enable bear mechanical collision and compression, coupled with ultra-broad-band absorption (7-40 and 75-110 GHz, reflection loss  smaller than -10 dB) approaching state-of-the-art electromagnetic absorption materials. With the assistance of experiment and simulation methods, the design advantages and mechanism of employing such 3D printed shells for substantially promoting the electromagnetic absorption performance have been demonstrated. Therefore, such universal strategy that could be widely extended to other categories of wax-based composites highlights a smart stage on which high-performance practical multifunction meta-structures with ultra-broad-band electromagnetic absorption could be envisaged.