Key umami taste contributors in Longjing green tea uncovered by integrated means of sensory quantitative descriptive analysis, metabolomics, quantification analysis and taste addition experiments.

Umami taste is a key criteria of green tea quality evaluation. The aim of this study was to comprehensively explore the key umami taste contributors in Longjing tea. The taste and molecular profiles of 36 Longjing green tea infusions were characterized by sensory quantitative descriptive analysis and LC-MS based metabolomics, respectively. By uni-/multi-variate statistical analysis, 84 differential compounds were screened among tea infusions with varied umami perceptions. Among them, 17 substances were identified as candidate umami-enhancing compounds, which showed significant positive correlations with umami intensities. Their natural concentrations were accurately quantified, and their umami taste-modifying effects were further investigated by taste addition into glutamic acid solution. Glutamic acid, aspartic acid, glutamine, theanine, phenylalanine, histidine, theogallin, galloylglucose, 1,2,6-trigalloylglucose significantly enhanced the umami taste. This study uncovered for the first time of some bitter amino acids and galloylglucose homologous series as important umami-enhancers, which provided a novel perspective into the tea taste.

The FLIP-FIGNL1 complex regulates the dissociation of RAD51/DMC1 in homologous recombination and replication fork restart.

Recruitment of RAD51 and/or DMC1 recombinases to single-strand DNA is indispensable for homology search and strand invasion in homologous recombination (HR) and for protection of nascent DNA strands at stalled replication forks. Thereafter RAD51/DMC1 dissociate, actively or passively, from these joint molecules upon DNA repair or releasing from replication stress. However, the mechanism that regulates RAD51/DMC1 dissociation and its physiological importance remain elusive. Here, we show that a FLIP-FIGNL1 complex regulates RAD51 and DMC1 dissociation to promote meiotic recombination and replication fork restart in mammals. Mice lacking FLIP are embryonic lethal, while germline-specific deletion of FLIP leads to infertility in both males and females. FLIP-null meiocytes are arrested at a zygotene-like stage with massive RAD51 and DMC1 foci, which frequently co-localize with SHOC1 and TEX11. Furthermore, FLIP interacts with FIGNL1. Depletion of FLIP or FIGNL1 in cell lines destabilizes each other and impairs RAD51 dissociation. Thus, the active dissociation of RAD51/DMC1 by the FLIP-FIGNL1 complex is a crucial step required for HR and replication fork restart, and represents a conserved mechanism in somatic cells and germ cells.

BBOF1 is required for sperm motility and male fertility by stabilizing the flagellar axoneme in mice.

The sperm flagellum is a specialized type of motile cilium composed of a typical "9 + 2" axonemal structure with peri-axonemal structures, such as outer dense fibers (ODFs). This flagellar arrangement is crucial for sperm movement and fertilization. However, the association of axonemal integrity with ODFs remains poorly understood. Here, we demonstrate that mouse BBOF1 could interact with both MNS1, an axonemal component, and ODF2, an ODF protein, and is required for sperm flagellar axoneme maintenance and male fertility. BBOF1 is expressed exclusively in male germ cells from the pachytene stage onwards and is detected in sperm axoneme fraction. Spermatozoa derived from Bbof1-knockout mice exhibit a normal morphology, however, reduced motility due to the absence of certain microtubule doublets, resulting in the failure to fertilize mature oocytes. Furthermore, BBOF1 is found to interact with ODF2 and MNS1 and is also required for their stability. Our findings in mice suggest that Bbof1 could also be essential for human sperm motility and male fertility, thus is a novel potential candidate gene for asthenozoospermia diagnosis.

Effects of exercise in treating patients with venous leg ulcers: A systematic review and meta-analysis.

To determine the effects of exercise on VLU healing and exercise adherence, and to provide evidence for clinical practice and scientific investigation. PubMed, Embase and Scopus were searched from inception to 31st March, 2022. Pooled relative risks (RRs), standardised mean differences (SMDs), adherence rate with respective 95% confidence intervals (CIs) were calculated. Quality assessment of included studies were performed using the Cochrane Collaboration risk of bias evaluation. Heterogeneity between enrolled studies was evaluated. We identified eight randomised control studies (RCTs) that met the inclusion criteria. The pooled RR for healing rate was 1.38 (95% CI: 1.14 to 1.66; P = 0.0008) with no significant heterogeneity between component studies (I2  = 0%, P = 0.96). SMD for differences of total range of ankle joint motion (ROAM) at the end and at the initiation of follow-up in the intervention and control groups was 0.87 (95% CI: 0.22, 1.52; P = 0.0091), no significant heterogeneity was detected (I2  = 59%, P = 0.0622). Pooled adherence rate was 64% (95% CI: 53%, 75%) with no significant heterogeneity. Exercise manifested positive effects on VLU healing, range of ankle mobility compared with the control group. Patients' adherence to the exercise regimens was favourable.

Dye-cored polylysine dendrimer as luminescent nanoplatform for imaging-guided anticancer drug delivery.

Dendrimers have numerous applications in imaging and drug delivery. Designing a dendrimer diagnostic platform with a well-defined structure and controlled drug delivery is a formidable challenge. Here, we design dendritic polymer-platinum conjugates (G5-PEG-Pt) as pH-responsive nanovesicles for imaging-guided platinum drug delivery. The G5-PEG-Pt have a well-defined structure, intrinsically bright fluorescence, and acid-responsive drug release. The pH-responsive G5-PEG-Pt could rapidly release the platinum drug at acidic pH (5.0) than neutral pH (7.4). The G5-PEG-Pt could enter SKOV-3 human ovarian cancer cells by the endocytosis pathway and exhibited comparative cytotoxicity to free cisplatin. By virtue of the prolonged blood circulation time and the enhanced permeability and retention (EPR) effect, a 4.4-fold higher tumor platinum uptake than that of free cisplatin was achieved, potentially enhancing the therapeutic indexes of the platinum drug. Therefore, these pH-responsive platinum and fluorescent dendrimer conjugates are expected to be potent in vivo cancer optical imaging and therapy platforms.

Investigating the effect of three phenolic fractions on the volatility of floral, fruity, and aged aromas by HS-SPME-GC-MS and NMR in model wine.

In this study, the volatility of three typical wine aromas in model wine was investigated by HS-SPME-GC-MS, NMR, and sensory evaluation as influenced by different concentrations and structural properties of phenolics. Results showed that three phenolic fractions (phenolic acids, monomeric/oligomeric and polymeric procyanidins) exhibited different matrix effects on floral, fruity, and aged aromas perception. Physico-chemical and sensory analyses together indicated that all fractions reduced the perceived intensity of fruity and aged aroma attributes, and displayed stronger retention effects on fruity aromas at higher mDP and concentrations. Monomeric/oligomeric and polymeric procyanidins promoted highly hydrophobic floral aromas release, whereas inhibiting the volatility of low hydrophobic fruity aromas. NMR confirmed that the reduction in the volatility of rose oxide, ethyl butanoate and whiskey lactone was attributed to interactions with epicatechin. This study aims to provide new thoughts and theoretical support for wine aroma regulation during winemaking by reconstructing the phenolic composition in wine.

Ubiquitin-Proteasome System-Regulated Protein Degradation in Spermatogenesis.

Spermatogenesis is a prolonged and highly ordered physiological process that produces haploid male germ cells through more than 40 steps and experiences dramatic morphological and cellular transformations. The ubiquitin proteasome system (UPS) plays central roles in the precise control of protein homeostasis to ensure the effectiveness of certain protein groups at a given stage and the inactivation of them after this stage. Many UPS components have been demonstrated to regulate the progression of spermatogenesis at different levels. Especially in recent years, novel testis-specific proteasome isoforms have been identified to be essential and unique for spermatogenesis. In this review, we set out to discuss our current knowledge in functions of diverse USP components in mammalian spermatogenesis through: (1) the composition of proteasome isoforms at each stage of spermatogenesis; (2) the specificity of each proteasome isoform and the associated degradation events; (3) the E3 ubiquitin ligases mediating protein ubiquitination in male germ cells; and (4) the deubiquitinases involved in spermatogenesis and male fertility. Exploring the functions of UPS machineries in spermatogenesis provides a global picture of the proteome dynamics during male germ cell production and shed light on the etiology and pathogenesis of human male infertility.

Wine polysaccharides modulating astringency through the interference on interaction of flavan-3-ols and BSA in model wine.

Polysaccharides and flavan-3-ols from Cabernet Sauvignon wine were isolated and then characterized by high performance liquid chromatography coupled with diode array detector (HPLC-DAD), high performance size exclusion chromatography (HPSEC) and HPLC-MS. The influence of purified polysaccharides on the aggregation of flavan-3-ols-proteins were investigated using fluorescence spectroscopy, circular dichroism (CD) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to evaluate the co-effect of polysaccharides on wine astringency. The results indicated that mannoproteins (MPs) and rhamnogalacturonans II (RG II) were the major polysaccharides to significantly alter the interaction of flavan-3-ols with bovine serum albumin (BSA). The interaction of polysaccharides-flavan-3-ols-BSA was enhanced with the concentration (from 0.2 to 0.6 g/L) of the studied polysaccharides. Furthermore, the reaction of BSA-flavan-3-ols was strengthened in the absence of polysaccharides when percentage of galloylation (%G) was higher (11.29). When mean degree of polymerization (mDP) of flavan-3-ols was from 5.14 to 6.88, the secondary structure of proteins was changed from mainly α-helix to random curl and the formation of protein precipitation increased. This work pointed out that the important property of polysaccharides and different structural characteristic flavan-3-ols are able to modulate wine astringency perception.

Meiosis I progression in spermatogenesis requires a type of testis-specific 20S core proteasome.

Spermatogenesis is tightly regulated by ubiquitination and proteasomal degradation, especially during spermiogenesis, in which histones are replaced by protamine. However, the functions of proteasomal activity in meiosis I and II remain elusive. Here, we show that PSMA8-associated proteasomes are essential for the degradation of meiotic proteins and the progression of meiosis I during spermatogenesis. PSMA8 is expressed in spermatocytes from the pachytene stage, and assembles a type of testis-specific core proteasome. Deletion of PSMA8 decreases the abundance of proteasome in testes. Meiotic proteins that are normally degraded at late prophase I, such as RAD51 and RPA1, remain stable in PSMA8-deleted spermatocytes. Moreover, PSMA8-null spermatocytes exhibit delayed M-phase entry and are finally arrested at this stage, resulting in male infertility. However, PSMA8 is neither expressed nor required for female meiotic progression. Thus, meiosis I progression in spermatogenesis, particularly entry into and exit from M-phase, requires the proteasomal activity of PSMA8-associated proteasomes.

SPO16 binds SHOC1 to promote homologous recombination and crossing-over in meiotic prophase I.

Segregation of homologous chromosomes in meiosis I is tightly regulated by their physical links, or crossovers (COs), generated from DNA double-strand breaks (DSBs) through meiotic homologous recombination. In budding yeast, three ZMM (Zip1/2/3/4, Mer3, Msh4/5) proteins, Zip2, Zip4, and Spo16, form a "ZZS" complex, functioning to promote meiotic recombination via a DSB repair pathway. Here, we identified the mammalian ortholog of Spo16, termed SPO16, which interacts with the mammalian ortholog of Zip2 (SHOC1/MZIP2), and whose functions are evolutionarily conserved to promote the formation of COs. SPO16 localizes to the recombination nodules, as SHOC1 and TEX11 do. SPO16 is required for stabilization of SHOC1 and proper localization of other ZMM proteins. The DSBs formed in SPO16-deleted meiocytes were repaired without COs formation, although synapsis is less affected. Therefore, formation of SPO16-SHOC1 complex-associated recombination intermediates is a key step facilitating meiotic recombination that produces COs from yeast to mammals.

ALK phosphorylates SMAD4 on tyrosine to disable TGF-ß tumour suppressor functions.

Loss of TGF-ß tumour suppressive response is a hallmark of human cancers. As a central player in TGF-ß signal transduction, SMAD4 (also known as DPC4) is frequently mutated or deleted in gastrointestinal and pancreatic cancer. However, such genetic alterations are rare in most cancer types and the underlying mechanism for TGF-ß resistance is not understood. Here we describe a mechanism of TGF-ß resistance in ALK-positive tumours, including lymphoma, lung cancer and neuroblastoma. We demonstrate that, in ALK-positive tumours, ALK directly phosphorylates SMAD4 at Tyr 95. Phosphorylated SMAD4 is unable to bind to DNA and fails to elicit TGF-ß gene responses and tumour suppressing responses. Chemical or genetic interference of the oncogenic ALK restores TGF-ß responses in ALK-positive tumour cells. These findings reveal that SMAD4 is tyrosine-phosphorylated by an oncogenic tyrosine kinase during tumorigenesis. This suggests a mechanism by which SMAD4 is inactivated in cancers and provides guidance for targeted therapies in ALK-positive cancers.

Evolutionarily-conserved MZIP2 is essential for crossover formation in mammalian meiosis.

During meiosis, formation of crossovers-the physical links that ensure the segregation of homologous chromosomes-requires a group of evolutionarily conserved ZMM proteins. In budding yeast, three ZMM proteins, Zip2, Spo16, and Zip4, form a trimeric complex to bind recombination intermediates and promote crossover formation. Here, we show that MZIP2 is the mammalian ortholog of Zip2. Complete ablation of MZIP2 in mice caused sterility in both males and females, as well as defects in repairing meiotic DNA double-strand breaks. MZIP2 forms discrete foci on chromosomes axes, and is required for the localization of TEX11 (mammalian Zip4 ortholog) and another ZMM protein, MSH4, to form crossover-prone recombination intermediates. As a consequence, formation of crossovers is abolished and formation of synaptonemal complex is incomplete in MZIP2-null meiocytes, resulting in meiosis arrest at a zygotene-like stage. Our results suggest that the processing of early recombination intermediates toward mature crossovers is dependent on MZIP2.