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• The levels of the important plant growth regulator indole-3-acetic acid (IAA) are tightly controlled within plant tissues to spatiotemporally orchestrate concentration gradients that drive plant growth and development. Metabolic inactivation of bioactive IAA is known to participate in the modulation of IAA maxima and minima. • IAA can be irreversibly inactivated by oxidation and conjugation to aspartate and glutamate. Usually overlooked because of its reversible nature, the most abundant inactive IAA form is the IAA-glucose (IAA-glc) conjugate. • Glycosylation of IAA in Arabidopsis thaliana is reported to be carried out by UDP-glycosyltransferase 84B1 (UGT84B1), while UGT74D1 has been implicated in the glycosylation of the irreversibly formed IAA catabolite oxIAA. • Here we demonstrated that both UGT84B1 and UGT74D1 modulate IAA levels throughout plant development by dual IAA and oxIAA glycosylation. Moreover, we identified a novel UGT subfamily whose members redundantly mediate the glycosylation of oxIAA and modulate skotomorphogenic growth.

PurposeThe outbreak of the Coronavirus (COVID-19) pandemic and its preventative social distancing measures have led to a dramatic increase in subscriptions to paid streaming services. Online users are increasingly accessing live broadcasts, as well as recorded video content and digital music services through internet and mobile devices. In this context, this study aims to explore the individuals’ uses and gratifications from online streaming technologies during COVID-19.Design/methodology/approachThis research has adapted key measures from the “technology acceptance model” (TAM) and from the “uses and gratifications theory” (UGT) to better understand the individuals’ intentions to use online streaming technologies. A structural equations partial least squares’ confirmatory composite approach was used to analyze the gathered data.FindingsThe individuals’ perceived usefulness and ease of use of online streaming services were significant antecedents of their intentions to use the mentioned technologies. Moreover, this study suggests that the research participants sought emotional gratifications from online streaming technologies, as they allowed them to distract themselves into a better mood and to relax in their leisure time. Evidently, they were using them to satisfy their needs for information and entertainment.Research limitations/implicationsThis study contributes to the academic literature by generating new knowledge about the individuals’ perceptions, motivations and intentions to use online streaming technologies to watch recorded movies, series and live broadcasts.Practical implicationsThe findings imply that there is scope for the providers of online streaming services to improve their customer-centric marketing by refining the quality and content of their recorded programs and through regular interactions with subscribers and personalized recommender systems.Originality/valueThis study integrates the TAM and UGT frameworks to better understand the effects of the users’ perceptions, ritualized and instrumental motivations on their intentions to continue watching movies, series and broadcasts through online streaming technologies, during COVID-19.

Through the nexus of event attendance motives, event experience, eventscape, and the Uses and Gratifications Theory to inform the conceptual framework of this study, this paper sheds light on the motives and experience in attending virtual and physical music events. It adopts a qualitative case study approach to explore the motives and experiences of virtual events based on 55 interviews who attended both types of concerts. This research contributes to the literature in music event motivation by connecting the motives and outcomes of attending virtual and physical music concerts, which are similar but manifested differently. Participants of virtual concerts were able to interact with others and enjoy the event atmosphere. The convenience element of eventscape plays an important role in participants’ experience, specifically on cost and accessibility. Technology also plays a pivotal role in inducing positive emotions and reaffirming fan identity. Practical implications for staging virtual events are discussed.

• The diversity of cytokinin (CK) metabolites suggests their interconversions are the predominant regulatory mechanism of CK action. Nevertheless, little is known about their directionality and kinetics in planta. • CK metabolite levels were measured in 2-wk-old Arabidopsis thaliana plants at several time points up to 100 min following exogenous application of selected CKs. The data were then evaluated qualitatively and by mathematical modeling. • Apart from elevated levels of trans-zeatin (tZ) metabolites upon application of N⁶-(Δ²-isopentenyl)adenine (iP), we observed no conversions between the individual CK-types – iP, tZ, dihydrozeatin (DHZ) and cis-zeatin (cZ). In particular, there was no sign of isomerization between tZ and cZ families. Also, no increase of DHZ-type CKs was observed after application of tZ, suggesting low baseline activity of zeatin reductase. Among N-glucosides, those of iP were not converted back to iP while tZ N-glucosides were cleaved to tZ bases, thus affecting the whole metabolic spectrum. • We present the first large-scale study of short-term CK metabolism kinetics and show that tZ N7- and N9-glucosides are metabolized in vivo. We thus refute the generally accepted hypothesis that N-glucosylation irreversibly inactivates CKs. The subsequently constructed mathematical model provides estimates of the metabolic conversion rates.

Glucuronidation and sulfation are the most typical phase II metabolic reactions of drugs. The resulting glucuronide and sulfate conjugates are generally considered inactive and safe. They may, however, be the most prominent drug-related material in the circulation and excreta of humans. The glucuronide and sulfate metabolites of drugs typically have limited cell membrane permeability and subsequently, their distribution and excretion from the human body requires transport proteins. Uptake transporters, such as organic anion transporters (OATs and OATPs), mediate the uptake of conjugates into the liver and kidney, while efflux transporters, such as multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP), mediate expulsion of conjugates into bile, urine and the intestinal lumen. Understanding the active transport of conjugated drug metabolites is important for predicting the fate of a drug in the body and its safety and efficacy. The aim of this review is to compile the understanding of transporter-mediated disposition of phase II conjugates. We review the literature on hepatic, intestinal and renal uptake transporters participating in the transport of glucuronide and sulfate metabolites of drugs, other xenobiotics and endobiotics. In addition, we provide an update on the involvement of efflux transporters in the disposition of glucuronide and sulfate metabolites. Finally, we discuss the interplay between uptake and efflux transport in the intestine, liver and kidneys as well as the role of transporters in glucuronide and sulfate conjugate toxicity, drug interactions, pharmacogenetics and species differences.

UDP‐glucuronosyltransferases (UGTs) are phase II drug metabolizing enzymes that play important roles in the detoxification of endogenous and exogenous substrates. The 22 human UGTs belong to four families (UGT1, UGT2, UGT3, and UGT8) and differ in their expression, substrate specificity, UDP‐sugar preference, and physiological functions. Differential expression/activity of the UGTs contributes to interperson variability in drug responses and toxicity, hormone homeostasis, and disease/cancer risks. However, in normal tissues, the tissue‐specific expression profiles and transcriptional regulation of the UGTs are still not fully understood. In this study, we comprehensively analyzed the transcriptome of 22 UGTs in 54 human tissues/regions using RNAseq data from GTEx. We then validated the findings in the liver and small intestine samples using real‐time PCR. Our results showed large interindividual variability across tissues in the expression of each UGT and the overall composition of UGT pools, consisting of different UGTs and their splice isoforms. Our results also revealed coexpression of the UGTs, Cytochrome P450s, and many transcription factors in the liver, suggesting potential coregulation or functional coordination. Our results provide the groundwork for future studies to detail further the regulation of the expression and activity of the UGTs. The expression of the UDP‐glucuronosyltransferases in different human tissues and regions.

Cytokinin (CK) N -glucosides are the most abundant group of CK metabolites in many species; however, their physiological role in planta was for a long time perceived as irreversible storage CK forms only. Recently, a comprehensive screen showed that only vascular plants form CK N -glucosides in contrast to mosses, algae, and fungi. The formation of CK N -glucosides as biologically inactive CK conjugates thus represents an evolutionarily young mechanism for deactivation of CK bases. Even though CK N -glucosides are not biologically active themselves due to their inability to activate the CK perception system, new data on CK N -glucoside metabolism show that trans -zeatin (tZ) N7- and N9-glucosides are metabolized in vivo , efficiently releasing free CK bases that are most probably responsible for the biological activities observed in a number of bioassays. Moreover, CK N -glucosides’ subcellular localization as well as their abundance in xylem both point to their possible plasma membrane transport and indicate a role also as CK transport forms. Identification of the enzyme(s) responsible for the hydrolysis of tZ N7- and N9-glucosides, as well as the discovery of putative CK N -glucoside plasma membrane transporter, would unveil important parts of the overall picture of CK metabolic interconversions and their physiological importance.

The mycotoxin deoxynivalenol (DON), formed by Fusarium species, is one of the most abundant mycotoxins contaminating food and feed worldwide. Upon ingestion, the majority of the toxin is excreted by humans and animal species as glucuronide conjugate. First in vitro data indicated that DON phase II metabolism is strongly species dependent. However, kinetic data on the in vitro metabolism as well as investigations on the specific enzymes responsible for DON glucuronidation in human are lacking. In the present study, the DON metabolism was investigated using human microsomal fractions and uridine-diphosphoglucuronyltransferases (UGTs) as well as liver microsomes from five animal species. Only two of the twelve tested human recombinant UGTs led to the formation of DON glucuronides with a different regiospecificity. UGT2B4 predominantly catalyzed the formation of DON-15- O -glucuronide (DON-15GlcA), while for UGT2B7 the DON-3- O -glucuronide (DON-3GlcA) metabolite prevailed. For human UGTs, liver, and intestinal microsomes, the glucuronidation activities were low. The estimated apparent intrinsic clearance (Cl app,int ) for all human UGT as well as tissue homogenates was <1 mL/min mg protein. For the animal liver microsomes, moderate Cl app,int between 1.5 and 10 mL/min mg protein were calculated for carp, trout, and porcine liver. An elevated glucuronidation activity was detected for rat and bovine liver microsomes leading to Cl app,int between 20 and 80 mL/min mg protein. The obtained in vitro data points out that none of the animal models is suitable for estimating the human DON metabolism with respect to the metabolite pattern and formation rate.

Glycosylation was catalyzed by UDP-glycosyltransferase (UGT) and was important for enriching diversity of flavonoids. Chinese bayberry ( Morella rubra ) has significant nutritional and medical values because of diverse natural flavonoid glycosides. However, information of UGT gene family was quite limited in M. rubra . In the present study, a total of 152 MrUGT genes clustered into 13 groups were identified in M. rubra genome. Among them, 139 MrUGT genes were marked on eight chromosomes and 13 members located on unmapped scaffolds. Gene duplication analysis indicated that expansion of MrUGT gene family was mainly forced by tandem and proximal duplication events. Gene expression patterns in different tissues and under UV-B treatment were analyzed by transcriptome. Cyanidin 3- O -glucoside (C3Glc) and quercetin 3- O -glucoside (Q3Glc) were two main flavonoid glucosides accumulated in M. rubra . UV-B treatment significantly induced C3Glc and Q3Glc accumulation in fruit. Based on comprehensively analysis of transcriptomic data and phylogenetic homology together with flavonoid accumulation patterns, MrUFGT (MrUGT78A26) and MrUGT72B67 were identified as UDP-glucosyltransferases. MrUFGT was mainly involved in C3Glc and Q3Glc accumulation in fruit, while MrUGT72B67 was mainly involved in Q3Glc accumulation in leaves and flowers. Gln375 and Gln391 were identified as important amino acids for glucosyl transfer activity of MrUFGT and MrUGT72B67 by site-directed mutagenesis, respectively. Transient expression in Nicotiana benthamiana tested the function of MrUFGT and MrUGT72B67 as glucosyltransferases. The present study provided valuable source for identification of functional UGTs involved in secondary metabolites biosynthesis in M. rubra .

With the increasing application of digital twin technology in various fields, many museums are starting to use this technology to build online platforms, and initial success has been achieved. During online tours, visitors’ emotional and cognitive experiences are shaped by many different factors, which further influence their appreciation of the exhibits. Based on this, the paper analyzes visitors’ experiences and feelings during online tours of the Palace Museum’s Ceramic Gallery from the perspective of Uses and Gratifications Theory (UGT). The research results show that both hedonic gratification and social gratification during the tour contribute to building positive emotional experiences for visitors, thereby increasing their appreciation of the exhibits. Similarly, utilitarian gratification and technological gratification can enhance cognitive experiences, which also lead to a greater appreciation of the exhibits. Among all research variables selected in this study, only Enjoyment and Self-Presentation did not show significant effects, while the impacts of other variables were very prominent.