Hyperbolic Interaction Model For Hierarchical Multi-Label Classification

Different from the traditional classification tasks which assume mutual exclusion of labels, hierarchical multi-label classification (HMLC) aims to assign multiple labels to every instance with the labels organized under hierarchical relations. Besides the labels, since linguistic ontologies are intrinsic hierarchies, the conceptual relations between words can also form hierarchical structures. Thus it can be a challenge to learn mappings from word hierarchies to label hierarchies. We propose to model the word and label hierarchies by embedding them jointly in the hyperbolic space. The main reason is that the tree-likeness of the hyperbolic space matches the complexity of symbolic data with hierarchical structures. A new Hyperbolic Interaction Model (HyperIM) is designed to learn the label-aware document representations and make predictions for HMLC. Extensive experiments are conducted on three benchmark datasets. The results have demonstrated that the new model can realistically capture the complex data structures and further improve the performance for HMLC comparing with the state-of-the-art methods. To facilitate future research, our code is publicly available

Mechanism of Thioesterase-Catalyzed Chain Release in the Biosynthesis of the Polyether Antibiotic Nanchangmycin

SummaryThe polyketide backbone of the polyether ionophore antibiotic nanchangmycin (1) is assembled by a modular polyketide synthase in Streptomyces nanchangensis NS3226. The ACP-bound polyketide is thought to undergo a cascade of oxidative cyclizations to generate the characteristic polyether. Deletion of the glycosyl transferase gene nanG5 resulted in accumulation of the corresponding nanchangmycin aglycone (6). The discrete thioesterase NanE exhibited a nearly 17-fold preference for hydrolysis of 4, the N-acetylcysteamine (SNAC) thioester of nanchangmycin, over 7, the corresponding SNAC derivative of the aglycone, consistent with NanE-catalyzed hydrolysis of ACP-bound nanchangmycin being the final step in the biosynthetic pathway. Site-directed mutagenesis established that Ser96, His261, and Asp120, the proposed components of the NanE catalytic triad, were all essential for thioesterase activity, while Trp97 was shown to influence the preference for polyether over polyketide substrates

Catechol siderophores framed on 2,3-dihydroxybenzoyl-L-serine from Streptomyces varsoviensis

Enterobactin is an archetypical catecholate siderophore that plays a key role in the acquisition of ferric iron by microorganisms. Catechol moieties have been shown to be promising siderophore cores. Variants of the conserved 2,3-dihydroxybenzoate (DHB) moiety with structural modifications expand the bioactivity. Streptomyces are characterized by metabolites with diverse structures. The genomic sequence of Streptomyces varsoviensis indicated that it possessed a biosynthetic gene cluster for DHB containing siderophores and metabolic profiling revealed metabolites correlated with catechol-type natural products. Here, we report the discovery of a series of catecholate siderophores produced by S. varsoviensis and a scale-up fermentation was performed to purify these compounds for structural elucidation. A biosynthetic route for the catecholate siderophores is also proposed. These new structural features enrich the structural diversity of the enterobactin family compounds. One of the new linear enterobactin congeners shows moderate activity against a food-borne pathogen Listeria monocytogenes. This work demonstrated that changing culture conditions is still a promising approach to explore unexplored chemical diversity. The availability of the biosynthetic machinery will enrich the genetic toolbox of catechol siderophores and facilitate such engineering efforts

Xylitol production from xylose mother liquor: a novel strategy that combines the use of recombinant Bacillus subtilis and Candida maltosa

<p>Abstract</p> <p>Background</p> <p>Xylose mother liquor has high concentrations of xylose (35%-40%) as well as other sugars such as L-arabinose (10%-15%), galactose (8%-10%), glucose (8%-10%), and other minor sugars. Due to the complexity of this mother liquor, further isolation of xylose by simple method is not possible. In China, more than 50,000 metric tons of xylose mother liquor was produced in 2009, and the management of sugars like xylose that present in the low-cost liquor is a problem.</p> <p>Results</p> <p>We designed a novel strategy in which <it>Bacillus subtilis </it>and <it>Candida maltosa </it>were combined and used to convert xylose in this mother liquor to xylitol, a product of higher value. First, the xylose mother liquor was detoxified with the yeast <it>C. maltosa </it>to remove furfural and 5-hydromethylfurfural (HMF), which are inhibitors of <it>B. subtilis </it>growth. The glucose present in the mother liquor was also depleted by this yeast, which was an added advantage because glucose causes carbon catabolite repression in <it>B. subtilis</it>. This detoxification treatment resulted in an inhibitor-free mother liquor, and the <it>C. maltosa </it>cells could be reused as biocatalysts at a later stage to reduce xylose to xylitol. In the second step, a recombinant <it>B. subtilis </it>strain with a disrupted xylose isomerase gene was constructed. The detoxified xylose mother liquor was used as the medium for recombinant <it>B. subtilis </it>cultivation, and this led to L-arabinose depletion and xylose enrichment of the medium. In the third step, the xylose was further reduced to xylitol by <it>C. maltosa </it>cells, and crystallized xylitol was obtained from this yeast transformation medium. <it>C. maltosa </it>transformation of the xylose-enriched medium resulted in xylitol with 4.25 g L^-1·h^-1volumetric productivity and 0.85 g xylitol/g xylose specific productivity.</p> <p>Conclusion</p> <p>In this study, we developed a biological method for the purification of xylose from xylose mother liquor and subsequent preparation of xylitol by <it>C. maltosa</it>-mediated biohydrogenation of xylose.</p

“Cultural and Creative IP” Empowerment Model for Red Culture under the New Media Environment

Boasting exemplary national qualities and high educational value, Red Culture is a unique spiritual wealth that make the Chinese nation stand out from the rest nations. Under the new media environment, however, the collision between the disparate characteristics of Red Culture and new media has given rise to the predicament plaguing the communication of Red Culture. With the advent of the 100th anniversary of the founding of the Communist Party of China, both tangible and intangible cultural heritage and resources are being valued, tapped and cultivated across the country. With the cultural and creative industry in the ascendant, the concept of intellectual property (“IP”) has seeped into all aspects of our everyday lives. Against that backdrop, this study attempts to explore novel ways to link up the Red Culture resources scattered across China, to combine education with cultural tourism through the “4+5+2” cultural and creative IP empowerment model, and to pass on and spread Red Culture and add new value to the industry on the strength of influential IPs

Crystal Structure of the Cysteine Desulfurase DndA from Streptomyces lividans Which Is Involved in DNA Phosphorothioation

DNA phosphorothioation is widespread among prokaryotes, and might function to restrict gene transfer among different kinds of bacteria. There has been little investigation into the structural mechanism of the DNA phosphorothioation process. DndA is a cysteine desulfurase which is involved in the first step of DNA phosphorothioation. In this study, we determined the crystal structure of Streptomyces lividans DndA in complex with its covalently bound cofactor PLP, to a resolution of 2.4 Å. Our structure reveals the molecular mechanism that DndA employs to recognize its cofactor PLP, and suggests the potential binding site for the substrate L-cysteine on DndA. In contrast to previously determined structures of cysteine desulfurases, the catalytic cysteine of DndA was found to reside on a β strand. This catalytic cysteine is very far away from the presumable location of the substrate, suggesting that a conformational change of DndA is required during the catalysis process to bring the catalytic cysteine close to the substrate cysteine. Moreover, our in vitro enzymatic assay results suggested that this conformational change is unlikely to be a simple result of random thermal motion, since moving the catalytic cysteine two residues forward or backward in the primary sequence completely disabled the cysteine desulfurase activity of DndA

Study on the influencing factors of digital transformation of construction enterprises from the perspective of dual effects—a hybrid approach based on PLS-SEM and fsQCA

The digital transformation of Chinese construction enterprises is crucial for achieving sustainable and high-quality development in the construction industry. However, there is still a lack of in-depth research on the impact mechanism of digital transformation in construction enterprises. The purpose of this study is to explore the multiple influencing factors and complex causal relationships of digital transformation in construction enterprises and promote the deep integration of digitalization and construction enterprises. To this end, based on the dual-effect perspective (net effect perspective of a single influencing factor and configuration effect perspective of multiple influencing factors), using the “technology–organization–environment” framework (TOE framework) to construct a research model of influencing factors for digital transformation in construction enterprises. A sample of 236 construction enterprise managers was surveyed, and partial least squares structural equation modeling (PLS-SEM) and fuzzy set qualitative comparative analysis (fsQCA) methods were used to empirically analyze the dual effects of influencing factors for digital transformation in construction enterprises. The results show that: (1) from the net effect perspective, there are seven factors that significantly impact digital transformation in construction enterprises; (2) from the configuration effect perspective, there are three paths that can achieve high-level digital transformation in construction enterprises, and one path that leads to low-level digital transformation; (3) from the dual-effect perspective, top management support and policy support are key factors for digital transformation in Chinese construction enterprises. The research results enrich the relevant research on digital transformation in construction enterprises and provide a reference basis for promoting digital transformation in construction enterprises

Upconversion NIR-II fluorophores for mitochondria-targeted cancer imaging and photothermal therapy

Acknowledgements: The work was supported by the National Key R&D Program of China (2020YFA0908800), NSFC (81773674, 81573383), Shenzhen Science and Technology Research Grant (JCYJ20190808152019182), Hubei Province Scientific and Technical Innovation Key Project, National Natural Science Foundation of Hubei Province (2017CFA024, 2017CFB711), the Applied Basic Research Program of Wuhan Municipal Bureau of Science and Technology (2019020701011429), Tibet Autonomous Region Science and Technology Plan Project Key Project (XZ201901-GB-11), the Local Development Funds of Science and Technology Department of Tibet (XZ202001YD0028C), Project First-Class Disciplines Development Supported by Chengdu University of Traditional Chinese Medicine (CZYJC1903), Health Commission of Hubei Province Scientific Research Project (WJ2019M177, WJ2019M178), the China Scholarship Council, and the Fundamental Research Funds for the Central Universities.Peer reviewedPublisher PD

Simple transanal total mesorectal resection versus laparoscopic transabdominal total mesorectal resection for the treatment of low rectal cancer: a single-center retrospective case-control study

AimTo evaluate the efficacy and safety of simple TaTNE in the treatment of low rectal cancer compared with laparoscopic transabdominal TME.MethodsWe collected patients with low rectal cancer admitted to our hospital between January 2019 and November 2021 who received simple TaTME or laparoscopic transabdominal TME. The main outcome was the integrity of the TME specimen. Secondary outcomes were the number of lymph nodes dissected, intraoperative blood loss, operative time, surgical conversion rate, Specimen resection length, circumferential margin (CRM), and distal resection margin (DRM), complication rate. In addition, the Wexner score and LARS score of fecal incontinence were performed in postoperative follow-up.ResultsPathological tissues were successfully resected in all patients. all circumferential margins of the specimen were negative. Specimen resection length was not statistically significant (9.94 ± 2.85 vs. 8.90 ± 2.49, P &gt; 0.05). The incidence of postoperative complications in group A (n = 0) was significantly lower than that in group B (n = 3) (P &gt; 0.05). There was no significant difference in operation time between group A and group B (296 ± 60.36 vs. 305 ± 58.28, P &gt; 0.05). Among the patients with follow-up time less than 1 year, there was no significant difference in Wexner score and LARS score between group A and group B (P &gt; 0.05). However, in patients who were followed up for more than 1 year, the Wexner score in group A (9.25 ± 2.73) was significantly lower than that in group B (17.36 ± 10.95) and was statistically significant (P &lt; 0.05).ConclusionFor radical resection of low rectal cancer, Simple TaTME resection may be as safe and effective as laparoscopic transabdominal TME, and the long-term prognosis may be better