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Background Computer-aided diagnosis (CAD) in the medical field has received more and more attention in recent years. One important CAD application is to detect and classify breast lesions in ultrasound images. Traditionally, the process of CAD for breast lesions classification is mainly composed of two separated steps: i) locate the lesion region of interests (ROI); ii) classify the located region of interests (ROI) to see if they are benign or not. However, due to the complex structure of breast and the existence of noise in the ultrasound images, traditional handcrafted feature based methods usually can not achieve satisfactory result. Methods With the recent advance of deep learning, the performance of object detection and classification has been boosted to a great extent. In this paper, we aim to systematically evaluate the performance of several existing state-of-the-art object detection and classification methods for breast lesions CAD. To achieve that, we have collected a new dataset consisting of 579 benign and 464 malignant lesion cases with the corresponding ultrasound images manually annotated by experienced clinicians. We evaluate different deep learning architectures and conduct comprehensive experiments on our newly collected dataset. Results For the lesion regions detecting task, Single Shot MultiBox Detector with the input size as 300×300 (SSD300) achieves the best performance in terms of average precision rate (APR), average recall rate (ARR) and F 1 score. For the classification task, DenseNet is more suitable for our problems. Conclusions Our experiments reveal that better and more efficient detection and convolutional neural network (CNN) frameworks is one important factor for better performance of detecting and classification task of the breast lesion. Another significant factor for improving the performance of detecting and classification task, which is transfer learning from the large-scale annotated ImageNet to classify breast lesion.

The impact of different vegetation types on soil organic carbon (SOC) is a key focus in global warming research. Bryophytes, commonly found in karst urban forests, significantly contribute to carbon accumulation in surface soil. However, the changes in soil organic carbon fractions under moss and the influencing factors remain unclear. To address this knowledge gap, the study examined the organic carbon content, soil physicochemical properties, and associated environmental factors in both moss-covered soil and bare soil under six different forest species within an urban park. The results showed that the SOC contents under moss cover in evergreen coniferous forest (127.28 g/kg), bamboo forest (144.70 g/kg), deciduous broad-leaved forest (87.63 g/kg), and evergreen shrub (109.28 g/kg) were significantly higher compared to bare soil. Moss cover also had a significant impact on soil readily oxidizable carbon (ROC), particulate organic carbon (POC), mineral-associated organic carbon (MOC), and heavy fraction organic carbon (HFOC) (P  < 0.01). The soil under moss had a higher content of stable organic carbon fraction, which is conducive to the stability of the soil organic carbon pool. The interaction between moss cover and stand type had the most significant effect on soil organic carbon, especially in bamboo forests. Canopy density, moss biomass, and soil moisture were the main environmental factors affecting the content of soil organic carbon and its fractions, while soil organic carbon content was mainly affected by soil nitrogen and phosphorus. This study establishes a theoretical framework for investigating the carbon cycle in karst urban underforest ecosystems, offering a scientific basis for the management and preservation of urban green space ecosystems. Future studies should include bryophytes in the assessment of dynamic factors affecting the soil carbon pool under forest cover and further explore the function and ecological significance of bryophytes in understory ecosystems.

In flowering plants, the pollen coat protects the released male germ cells from desiccation and damage during pollination. However, we know little about the mechanism by which the chemical composition of the pollen coat prevents dehydration of pollen grains. Here we report that deficiency of a grass conserved triterpene synthase, OsOSC12/OsPTS1, in rice leads to failure of pollen coat formation. The mutant plants are male sterile at low relative humidity (RH < 60%), but fully male fertile at high relative humidity (>80%). The lack of three major fatty acids in the pollen coat results in rapid dehydration of pollen grains. We show that applying mixtures of linolenic acid and palmitic acid or stearic acid are able to prevent over-dehydration of mutant pollen grains. We propose that humidity-sensitive genic male sterility (HGMS) could be a desirable trait for hybrid breeding in rice, wheat, maize, and other crops. In flowering plants, the pollen coat surrounds the male germ cells and protects against dehydration, damage and pathogen attack. Here, the authors show that a deficiency in terpenoid synthesis results in rice pollen over-dehydration and leads to a humidity-sensitive conditional male sterile phenotype.

Cucurbitacins are triterpenoids that confer a bitter taste in cucurbits such as cucumber, melon, watermelon, squash, and pumpkin. These compounds discourage most pests on the plant and have also been shown to have antitumor properties. With genomics and biochemistry, we identified nine cucumber genes in the pathway for biosynthesis of cucurbitacin C and elucidated four catalytic steps. We discovered transcription factors Bl (Bitter leaf) and Bt (Bitter fruit) that regulate this pathway in leaves and fruits, respectively. Traces in genomic signatures indicated that selection imposed on Bt during domestication led to derivation of nonbitter cucurbits from their bitter ancestors.

Ecosystem stability arises from the interplay of species diversity, environmental conditions, and external disturbances. Understanding the structure of plant communities, interspecific relationships, and community stability in urban ecosystems is fundamental to ecological restoration and community development. This study utilized the karst city of Guiyang as a case study and employed the α diversity index, variance ratio method (VR), χ2‐test, Pearson correlation test, Spearman rank correlation test, M. Godron stability, and canonical correspondence analysis (CCA). The research focused on analyzing the species diversity, interspecific associations, community stability, and environmental factors of lithophytic moss at various elevations (989–1398 m). The findings revealed the presence of 58 species belonging to 27 genera and 13 families of lithophytic moss in the study area. Notably, the Brachytheciaceae and Pottiaceae emerged as dominant, exhibiting a broad ecological range and adaptation mechanisms, thereby playing a crucial role in the ecological environment of rocky desertification. The study observed that the highest species richness and dominance values of lithophytic moss were recorded at the N4 (1296–1398 m) elevation gradient, while the highest species diversity and uniformity values were observed at the N3 (1194–1295 m) elevation gradient, indicating a significant impact of altitude on lithobryophyte species diversity, particularly at middle and high altitudes. The analysis of interspecific associations and stability indicated a predominantly negative overall association within the lithophytic moss community, suggesting an early stage of succession, with weak interspecific associations and correlations among dominant pairs, tending towards relative independence. Only the communities at N2 (1092–1193 m) elevation exhibited stability, while the other communities were in an unstable stage, showing no significant correlation with species diversity. Furthermore, light intensity (182–129300 lux) exerted the greatest influence on community stability. Additionally, air humidity (36.5–52.3%) and altitude (998–1327 m) emerged as the primary environmental factors influencing community distribution, with a close and positive correlation between the two. These results hold significant reference value for promoting the succession and steady development of vegetation in rocky desertification areas and enhancing the conservation and restoration of vegetation community diversity in karst urban ecosystems. The study on the interspecific relationship, community stability, and environmental factors of lithophytic moss at different elevations in karst cities can improve the conservation and restoration of vegetation community diversity in karst urban ecosystems.

N-Heterocyclic carbene (NHC)-based cages have emerged as a prominent and dynamic research area within the research field of chemistry. Leveraging the distinctive electronic and steric properties of NHC ligands, the design, synthesis, and application of these corresponding cages have garnered substantial scholarly interest. In recent years, we have witnessed the successful fabrication of diverse NHC-based cages through a range of synthetic methodologies, which hold significant potential for applications in molecular recognition and catalysis. In this review, we delve into the foundational synthetic strategies that underlie the creation of NHC-based cages, employing approaches encompassing metal–NHC chelation, coordination assembly, and covalent bonding. Additionally, we compile the diverse applications of these cages within catalytic processes and molecular recognition. Lastly, we shed light on the current limitations of synthesis and outline future trends in the development of NHC-based cages.

Ent-kaurene diterpenoids are the largest group of known Isodon diterpenoids. Among them, oridonin is accumulated in the leaves, and is the most frequently studied compound because of its antitumor and antibacterial activities. We have identified five copalyl diphosphate synthase (CPS) and six kaurene synthase-like (KSL) genes by transcriptome profiling of Isodon rubescens leaves. An in vitro assay assigns ten of them to five different diterpene biosynthesis pathways, except IrCPS3 that has a mutation in the catalytic motif. The Lamiaceae-specific clade genes (IrCPS1 and IrCPS2) synthesize the intermediate copalyl diphosphate (normal-CPP), while IrCPS4 and IrCPS5 synthesize the intermediate ent-copalyl diphosphate (ent-CPP). IrKSL2, IrKSL4, and IrKSL5 react with ent-CPP to produce an ent-isopimaradiene-like compound, ent-atiserene and ent-kaurene, respectively. Correspondingly, the Lamiaceae-specific clade genes IrKSL1 or IrKSL3 combined with normal-CPP led to the formation of miltiradiene. The compound then underwent aromatization and oxidization with a cytochrome P450 forming two related compounds, abietatriene and ferruginol, which were detected in the root bark. IrKSL6 reacts with normal-CPP to produce isopimaradiene. IrKSL3 and IrKSL6 have the 𝛾𝛽𝛼 tridomain structure, as these proteins tend to possess the bidomain structure of IrKSL1, highlighting the evolutionary history of KSL gene domain loss and further elucidating chemical diversity evolution from a macroevolutionary stance in Lamiaceae.

Glycosylflavonoids are a class of natural products with multiple pharmacological activities and a lot of glycosyltransferases from various plant species have been reported that they were involved in the biosynthesis of these phytochemicals. However, no corresponding glycosyltransferase has been identified from the famous horticultural and medicinal plant Iris tectorum Maxim. Here, UGT73CD1, a novel glycosyltransferase, was identified from I. tectorum. based on transcriptome analysis and functional identification. Phylogenetic analysis revealed that UGT73CD1 grouped into the clade of flavonoid 7-OH OGTs. Biochemical analysis showed that UGT73CD1 was able to glycosylate tectorigenin at 7-OH to produce tectoridin, and thus assigned as a 7-O-glycosyltransferase. In addition, it also possessed robust catalytic promiscuity toward 12 structurally diverse flavonoid scaffolds and 3, 4-dichloroaniline, resulting in forming O- and N-glycosides. This work will provide insights into efficient biosynthesis of structurally diverse flavonoid glycosides for drug discovery.

Differentiation of secondary metabolite profiles in closely related plant species provides clues for unravelling biosynthetic pathways and regulatory circuits, an area that is still underinvestigated. Cucurbitacins, a group of bitter and highly oxygenated tetracyclic triterpenes, are mainly produced by the plant family Cucurbitaceae. These compounds have similar structures, but differ in their antitumour activities and ecophysiological roles. By comparative analyses of the genomes of cucumber, melon and watermelon, we uncovered conserved syntenic loci encoding metabolic genes for distinct cucurbitacins. Characterization of the cytochrome P450s (CYPs) identified from these loci enabled us to unveil a novel multi-oxidation CYP for the tailoring of the cucurbitacin core skeleton as well as two other CYPs responsible for the key structural variations among cucurbitacins C, B and E. We also discovered a syntenic gene cluster of transcription factors that regulates the tissue-specific biosynthesis of cucurbitacins and may confer the loss of bitterness phenotypes associated with convergent domestication of wild cucurbits. This study illustrates the potential to exploit comparative genomics to identify enzymes and transcription factors that control the biosynthesis of structurally related yet unique natural products. Different cucurbits produce cucurbitacins with varied structures and activities. A comparative genomic study illustrates the genetic basis of cucurbitacin differentiation and tissue-specific cucurbitacin synthesis.

Triterpenes are one of the largest classes of plant metabolites and have important functions. A diverse array of triterpenoid skeletons are synthesized via the isoprenoid pathway by enzymatic cyclization of 2,3-oxidosqualene. The genomes of the lower plants Chlamydomonas reinhardtii and moss (Physcomitrella patens) contain just one oxidosqualene cyclase (OSC) gene (for sterol biosynthesis), whereas the genomes of higher plants contain nine to 16 OSC genes. Here we carry out functional analysis of rice OSCs and rigorous phylogenetic analysis of 96 OSCs from higher plants, including Arabidopsis thaliana, Oryza sativa, Sorghum bicolor and Brachypodium distachyon. The functional analysis identified an amino acid sequence for isoarborinol synthase (OsIAS) (encoded by Os11g35710/OsOSC11) in rice. Our phylogenetic analysis suggests that expansion of OSC members in higher plants has occurred mainly through tandem duplication followed by positive selection and diversifying evolution, and consolidated the previous suggestion that dicot triterpene synthases have been derived from an ancestral lanosterol synthase instead of directly from their cycloartenol synthases. The phylogenetic trees are consistent with the reaction mechanisms of the protosteryl and dammarenyl cations which parent a wide variety of triterpene skeletal types, allowing us to predict the functions of the uncharacterized OSCs.