Radiative trigger thresholds of foliar photoprotective pigment regulation for global vegetation.

Adjustments in foliar photoprotective pigments are crucial for plant adaptation to harsh environments, serving as indicators of environmental stress. However, understanding when and where these adjustments occur across diverse biomes remains unclear due to challenges in large-scale observation. Here, we propose a novel approach to assess dynamics in photoprotective pigments at the canopy level using a new index derived from space-borne optical sensors. This approach generates a global map depicting the daily mean shortwave radiation threshold at which adjustments typically occur under prevailing climatic conditions. The global average of this threshold is 262 ± 50 W m⁻2, with lower values at high latitudes and peaks near 40° in both hemispheres. Temperature exerts a stronger influence on this latitudinal pattern than humidity. Future projections suggest a decrease in this threshold over northern high latitudes, implying exacerbated vulnerability under identical radiation levels due to negative warming responses. Based on this threshold, a high-stress zone around 60°N is identified and is predicted to shift southward in the future. These findings bridge critical gaps in photoprotection research and offer a new perspective on understanding the biogeochemical cycles of global ecosystems. This framework can also enhance our ability to predict the fate of diverse ecosystems under future climate.

Resveratrol shields against cisplatin-induced ototoxicity through epigenetic lncRNA GAS5 modulation of miR-455-5p/PTEN pathway.

BACKGROUND: Our previous research demonstrated that resveratrol counters DDP-induced ototoxicity by upregulating miR-455-5p, which targets PTEN. This study aimed to elucidate the underlying mechanisms involving GAS5 and DNA methyltransferase 1 (DNMT1) in resveratrol's protective action. METHODS: A luciferase reporter assay and RNA immunoprecipitation (RIP) assay were employed to study the binding between GAS5 and miR-455-5p, as well as between miR-455-5p and PTEN. HEI-OC1 cells treated with DDP were transfected with vectors for GAS5, si-GAS5, DNMT1, si-DNMT1, and miR-455-5p mimics, as well as PTEN. Subsequently, they were treated with resveratrol and exposed to DDP, both separately and in combination. The distribution of CpG islands in the GAS5 promoter was identified using MethyPrimer, and methylation-specific PCR (MSP) was conducted to determine the methylation levels of GAS5. Chromatin immunoprecipitation (ChIP) was utilized to examine the interaction between DNMT1 and GAS5. The viability of HEI-OC1 cells, catalase (CAT) activity, apoptosis, and ROS levels were assessed using the CCK-8 assay, CAT assay, TUNEL staining, and flow cytometry, respectively. An in vivo mouse model was developed to measure auditory brainstem response (ABR) thresholds, while RT-qPCR and Western blot analysis were employed to evaluate molecular levels. RESULTS: Our study discovered that GAS5 acts as a sponge for miR-455-5p, thereby increasing PTEN expression in DDP-treated HEI-OC1 cells. This process was reversed upon treatment with resveratrol. Importantly, DNMT1 promoted the methylation of the GAS5 promoter, leading to the suppression of GAS5 expression. This suppression enhanced the effectiveness of resveratrol in combating DDP-induced apoptosis and ROS in HEI-OC1 cells and amplified its protective effect against DDP's ototoxicity in vivo. CONCLUSIONS: Our research emphasizes the significance of the DNMT1/GAS5/miR-455-5p/PTEN axis as a promising new route to boost resveratrol's effectiveness against DDP-induced ototoxicity.

Effect of light treatmeat on oxidation and flavour of dry-cured Wuchang fish.

Lighting conditions are an important factor affecting dry-cured products. This study investigated the effects of treatments with different light intensities (0 lx, 1000 lx, 25000 lx) and different light sources including red light, blue light, UV-light on oxidation leve and flavor change in dry-cured Wuchang fish. The results showed that dry-cured Wuchang fish exhibited an attractive brown-yellow color, the highest oxidation degree of myoglobin (Mb), the highest fat oxidation under the light conditions of 25000 lx light intensity and UV-light irradiation. This phenomenon was observed that the degree of Mb oxidation was increased, while the degree of fat oxidation was increased. At 25000 lx light intensity and UV-light irradiation, dry-cured Wuchang fish showed an ignificantly decreased fatty acid conten (especially oleic acid and linoleic acid), significantly increased characteristic volatile compound contents (22 for 25,000 lx light intensity and 27 for UV-light irradiation), which contributed to the improvement of quality stability of dry-cured Wuchang fish. Our findings provide theoretical support for the industrial application of exogenous light in dry-cured Wuchang fish.

Metabolomics, volatolomics, and bioinformatics analyses of the effects of ultra-high pressure pretreatment on taste and flavour parameters of cured Culter alburnus.

The effects of ultra-high pressure (UHP) pretreatment (50-250 MPa) on the fish curing were studied. UHP increased the overall volatile compound concentration of cured fish. Among 50-250 MPa five treatment groups, 150 MPa UHP group exhibited the highest total free amino acid content (294.34 mg/100 g) with that of the control group being 92.39 mg/100 g. The activity of cathepsin L was increased under 50-200 MPa UHP treatment (62.28-58.15 U/L), compared with that in the control group (53.80 U/L). UHP treatment resulted in a significant increase in small molecule compounds, especially the amino acid dipeptides and ATP metabolic products. Under UHP treatments, the bacterial phyla Actinobacteriota (1.04-5.25 %), Bacteroidota (0.20-4.47 %), and Deinococcota (0.00-0.05 %) exhibited an increased abundance, and they promoted taste and flavor formation. Our results indicated that UHP is a promising pretreatment method to improve taste and flavour in cured fish by affecting the microorganisms, cathepsin, and proteins.

Differential fluorescence features and recovery speeds of different scorpion exoskeleton parts during the molting process.

Scorpion fluorescence under ultraviolet light is a well-known phenomenon, but its features under excitation in the UVA, UVB and UVC bands have not been characterized. Systematic fluorescence characterization revealed indistinguishable fluorescence spectra with a peak wavelength of 475 nm for whole exuviae from second-, third- and fifth-instar scorpions under different ultraviolet light ranges. In-depth investigations of the chelae, mesosoma, metasoma and telson of adult scorpions further indicated heterogeneity in the typical fluorescence spectrum within the visible light range and in the newly reported fluorescence spectrum with a peak wavelength of 320 nm within the ultraviolet light range, which both showed excitation wavelength-independent features. Dynamic fluorescence changes during the molting process of third-instar scorpions revealed the fluorescence heterogeneity-dependent recovery speed of scorpion exoskeletons. The typical fluorescence spectra of the molted chelae and telson rapidly recovered approximately 6 h after ecdysis under UVA light and approximately 36 h after ecdysis under UVB and UVC light. However, it took approximately 12 h and 24 h to obtain the typical fluorescence spectra of the molted metasoma and mesosoma, respectively, under UVA irradiation and 72 h to obtain the typical fluorescence spectra under UVB and UVC irradiation. The fluorescence heterogeneity-dependent fluorescence recovery of the scorpion exoskeleton was further confirmed by tissue section analysis of different segments from molting third-instar scorpions. These findings reveal novel scorpion fluorescence features and provide potential clues on the biological function of scorpion fluorescence.

Inhibition mechanism of crude lipopeptide from Bacillus subtilis against Aeromonas veronii growth, biofilm formation, and spoilage of channel catfish flesh.

Aeromonas veronii is associated with food spoilage and some human diseases, such as diarrhea, gastroenteritis, hemorrhagic septicemia or asymptomatic and even death. This research investigated the mechanism of the growth, biofilm formation, virulence, stress resistance, and spoilage potential of Bacillus subtilis lipopeptide against Aeromonas veronii. Lipopeptides suppressed the transmembrane transport of Aeromonas veronii by changing the cell membrane's permeability, the structure of membrane proteins, and Na+/K+-ATPase. Lipopeptide significantly reduced the activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) by 86.03% and 56.12%, respectively, ultimately slowing Aeromonas veronii growth. Lipopeptides also restrained biofilm formation by inhibiting Aeromonas veronii motivation and extracellular polysaccharide secretion. Lipopeptides downregulated gene transcriptional levels related to the virulence and stress tolerance of Aeromonas veronii. Furthermore, lipopeptides treatment resulted in a considerable decrease in the extracellular protease activity of Aeromonas veronii, which restrained the decomposing of channel catfish flesh. This research provides new insights into lipopeptides for controlling Aeromonas veronii and improving food safety.

A Low Dose of Rapamycin Promotes Hair Cell Differentiation by Enriching SOX2+ Progenitors in the Neonatal Mouse Inner Ear Organoids.

PURPOSE: To investigate the impact of rapamycin on the differentiation of hair cells. METHODS: Murine cochlear organoids were derived from cochlear progenitor cells. Different concentrations of rapamycin were added into the culture medium at different proliferation and differentiation stages. RESULTS: Rapamycin exhibited a concentration-dependent reduction in the proliferation of these inner ear organoids. Nevertheless, organoids subjected to a 10-nM dose of rapamycin demonstrated a markedly increased proportion of hair cells. Furthermore, rapamycin significantly upregulated the expression of markers associated with both hair cells and supporting cells, including ATOH1, MYO7A, and SOX2. Mechanistic studies revealed that rapamycin preferentially suppressed cells without Sox2 expression during the initial proliferation stage, thereby augmenting and refining the population of SOX2+ progenitors. These enriched progenitors were predisposed to differentiate into hair cells during the later stages of organoid development. Conversely, the use of the mTOR activator MHY 1485 demonstrated opposing effects. CONCLUSION: Our findings underscore a practical strategy for enhancing the generation of inner ear organoids with a low dose of rapamycin, achieved by enriching SOX2+ progenitors in an in vitro setting.

Difference in muscle metabolism caused by metabolism disorder of rainbow trout liver exposed to ammonia stress.

Ammonia pollution is an important environmental stress factors in water eutrophication. The intrinsic effects of ammonia stress on liver toxicity and muscle quality of rainbow trout were still unclear. In this study, we focused on investigating difference in muscle metabolism caused by metabolism disorder of rainbow trout liver at exposure times of 0, 3, 6, 9 h at 30 mg/L concentrations. Liver transcriptomic analysis revealed that short-term (3 h) ammonia stress inhibited carbohydrate metabolism and glycerophospholipid production but long-term (9 h) ammonia stress inhibited the biosynthesis and degradation of fatty acids, activated pyrimidine metabolism and mismatch repair, lead to DNA strand breakage and cell death, and ultimately caused liver damage. Metabolomic analysis of muscle revealed that ammonia stress promoted the reaction of glutamic acid and ammonia to synthesize glutamine to alleviate ammonia toxicity, and long-term (9 h) ammonia stress inhibited urea cycle, hindering the alleviation of ammonia toxicity. Moreover, it accelerated the consumption of flavor amino acids such as arginine and aspartic acid, and increased the accumulation of bitter substances (xanthine) and odorous substances (histamine). These findings provide valuable insights into the potential risks and hazards of ammonia in eutrophic water bodies subject to rainbow trout.

A unified view on enzyme catalysis by cryo-EM study of a DNA topoisomerase.

The theories for substrate recognition in enzyme catalysis have evolved from lock-key to induced fit, then conformational selection, and conformational selection followed by induced fit. However, the prevalence and consensus of these theories require further examination. Here we use cryogenic electron microscopy and African swine fever virus type 2 topoisomerase (AsfvTop2) to demonstrate substrate binding theories in a joint and ordered manner: catalytic selection by the enzyme, conformational selection by the substrates, then induced fit. The apo-AsfvTop2 pre-exists in six conformers that comply with the two-gate mechanism directing DNA passage and release in the Top2 catalytic cycle. The structures of AsfvTop2-DNA-inhibitor complexes show that substantial induced-fit changes occur locally from the closed apo-conformer that however is too far-fetched for the open apo-conformer. Furthermore, the ATPase domain of AsfvTop2 in the MgAMP-PNP-bound crystal structures coexist in reduced and oxidized forms involving a disulfide bond, which can regulate the AsfvTop2 function.

Visualizing the DNA repair process by a photolyase at atomic resolution.

Photolyases, a ubiquitous class of flavoproteins, use blue light to repair DNA photolesions. In this work, we determined the structural mechanism of the photolyase-catalyzed repair of a cyclobutane pyrimidine dimer (CPD) lesion using time-resolved serial femtosecond crystallography (TR-SFX). We obtained 18 snapshots that show time-dependent changes in four reaction loci. We used these results to create a movie that depicts the repair of CPD lesions in the picosecond-to-nanosecond range, followed by the recovery of the enzymatic moieties involved in catalysis, completing the formation of the fully reduced enzyme-product complex at 500 nanoseconds. Finally, back-flip intermediates of the thymine bases to reanneal the DNA were captured at 25 to 200 microseconds. Our data cover the complete molecular mechanism of a photolyase and, importantly, its chemistry and enzymatic catalysis at work across a wide timescale and at atomic resolution.

Clinical characteristics and prognosis of sudden sensorineural hearing loss in single-sided deafness patients.

Background: Sudden sensorineural hearing loss (SSNHL) in patients with single-sided deafness (SSD) is rare. The prognosis of the sole serviceable hearing ear is very important for these patients. However, the clinical characteristics and prognosis of SSNHL in SSD patients are not well-documented. Objective: This study aimed to investigate the clinical features and treatment outcomes of SSNHL in SSD patients. Methods: Clinical data of 36 SSD patients and 116 non-SSD patients with unilateral SSNHL from January 2013 to December 2022 were retrospectively investigated. The clinical characteristics of the SSD patients were analyzed. All SSD patients were treated with intratympanic steroids plus intravenous steroids. Pure-tone average (PTA) and word recognition score (WRS) before and after treatment were recorded. The hearing recovery of SSNHL in SSD patients in comparison with non-SSD patients was explored. Auditory outcomes in SSD patients with different etiologies were also compared. Results: Initial hearing threshold showed no significant differences between the SSD group and the non-SSD group (66.41 ± 24.64 dB HL vs. 69.21 ± 31.48 dB HL, p = 0.625). The SSD group had a higher post-treatment hearing threshold (median (interquartile range, IQR) 53.13(36.56) dB HL) than the non-SSD group (median 32.50(47.5) dB HL, p < 0.01). Hearing gains (median 8.75(13.00) dB) and the rate of significant recovery (13.89%) were lower in the SSD group than in the non-SSD group (median 23.75(34.69) dB, 45.69%). The etiology of SSD was classified as SSNHL, special types of infection, chronic otitis media, and unknown causes. SSNHL accounted for the maximum proportion (38.9%) of causes of SSD in the SSD group. Hearing gains were lower in the SSNHL-SSD group than in other causes of the SSD group. A binary logistic regression analysis demonstrated that SSD serves as an indicator of unfavorable hearing recovery outcomes (OR = 5.264, p < 0.01). Conclusion: The prognosis of SSNHL in SSD patients is unsatisfactory. SSNHL accounts for the maximum proportion of causes of SSD in this group of patients. For SSD patients caused by SSNHL, less hearing improvement after treatment was expected when SSNHL occurred in the contralateral ear in comparison with SSD patients with other causes.

Enhancing activity of food protein-derived peptides: An overview of pretreatment, preparation, and modification methods.

Food protein-derived peptides have garnered considerable attention due to their potential bioactivities and functional properties. However, the limited activity poses a challenge in effective utilization aspects. To overcome this hurdle, various methods have been explored to enhance the activity of these peptides. This comprehensive review offers an extensive overview of pretreatment, preparation methods, and modification strategies employed to augment the activity of food protein-derived peptides. Additionally, it encompasses a discussion on the current status and future prospects of bioactive peptide applications. The review also addresses the standardization of mass production processes and safety considerations for bioactive peptides while examining the future challenges and opportunities associated with these compounds. This comprehensive review serves as a valuable guide for researchers in the food industry, offering insights and recommendations to optimize the production process of bioactive peptides.

Delayed Antarctic melt season reduces albedo feedback.

Antarctica's response to climate change varies greatly both spatially and temporally. Surface melting impacts mass balance and also lowers surface albedo. We use a 43-year record (from 1978 to 2020) of Antarctic snow melt seasons from space-borne microwave radiometers with a machine-learning algorithm to show that both the onset and the end of the melt season are being delayed. Granger-causality analysis shows that melt end is delayed due to increased heat flux from the ocean to the atmosphere at minimum sea-ice extent from warming oceans. Melt onset is Granger-caused primarily by the turbulent heat flux from ocean to atmosphere that is in turn driven by sea-ice variability. Delayed snowmelt season leads to a net decrease in the absorption of solar irradiance, as a delayed summer means that higher albedo occurs after the period of maximum solar radiation, which changes Antarctica's radiation balance more than sea-ice cover.

Preparation of polysaccharide-based nanoparticles by chitosan and flaxseed gum polyelectrolyte complexation as carriers for bighead carp (Aristichthys nobilis) peptide delivery.

Polysaccharide-based nanoparticles formed by the polyelectrolyte complexation between chitosan (CS) and flaxseed gum (FG) was developed in this work, and it was further used as a carrier for bighead carp peptide (BCP) delivery. The CS molecular weight (MW) of 50 kDa and CS/FG mass ratio of 1:2 at pH 3.5 were optimal conditions for the NP preparation, with the minimum particle size (∼155.1 nm) and the maximum BCP encapsulation efficiency (60.3 %). The BCP-loaded CS/FG NPs exhibited the smallest particle size (175.8 nm). Both CS/FG NPs and CS/FG-BCP NPs exhibited roughly uniform spherical shape. FT-IR spectra confirmed the existence of hydrogen bonds and electrostatic interactions in the nanoparticles. The BCP-loaded NPs displayed a higher thermal stability than BCP. Moreover, the release of BCP was controllable and dose-dependent, following a first-order kinetics model. These findings suggested that our CS/FG NPs are a promising carrier for bioactive peptide delivery.

Thermally Reversible Cross-Linking of Recyclable Polyamide Materials Based on Schiff Base and Diels-Alder Reactions.

Recyclability of cross-link polymer materials is essential to alleviate environmental pollution caused by discarded or damaged polymers. Herein, a facile method for producing recyclable polyamide materials is developed. Linear polymer chains are constructed by Schiff base reaction between glutaraldehyde (GD) and furandiamine (FD). The linear polymer chains are crosslinked by bismaleimide (BM) to give rise to polyamide material, named GF-BMs. The resulting GF-BMs polyamide material possesses strong tensile strength (78 MPa) and good solvent resistance from room temperature to 135 °C. Especially, the thermally reversible Diels-Alder covalent bonds and dynamic imine bonds in the polymer network have a synergistic effect on fast-reprocessing, self-healing, and recyclability, which provides a new idea for recyclable materials.

An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria.

Regulation of CO2 fixation in cyanobacteria is important both for the organism and global carbon balance. Here we show that phosphoketolase in Synechococcus elongatus PCC7942 (SeXPK) possesses a distinct ATP-sensing mechanism, where a drop in ATP level allows SeXPK to divert precursors of the RuBisCO substrate away from the Calvin-Benson-Bassham cycle. Deleting the SeXPK gene increased CO2 fixation particularly during light-dark transitions. In high-density cultures, the Δxpk strain showed a 60% increase in carbon fixation and unexpectedly resulted in sucrose secretion without any pathway engineering. Using cryo-EM analysis, we discovered that these functions were enabled by a unique allosteric regulatory site involving two subunits jointly binding two ATP, which constantly suppresses the activity of SeXPK until the ATP level drops. This magnesium-independent ATP allosteric site is present in many species across all three domains of life, where it may also play important regulatory functions.

Mutational and biophysical analyses reveal a TFIIIC binding region in the TFIIF-related Rpc53 subunit of RNA polymerase III.

The TFIIF-like Rpc53/Rpc37 heterodimer of RNA polymerase (pol) III is involved in various stages of transcription. The C-terminal region of Rpc53 dimerizes with Rpc37 to anchor on the lobe domain of the pol III cleft. However, structural and functional features of the Rpc53 N-terminal region had not been characterized previously. Here, we conducted site-directed alanine replacement mutagenesis on the Rpc53 N-terminus, generating yeast strains that exhibited a cold-sensitive growth defect and severely compromised pol III transcriptional activity. Circular dichroism and NMR spectroscopy revealed a highly disordered 57-amino acid polypeptide in the Rpc53 N-terminus. This polypeptide is a versatile protein-binding module displaying nanomolar-level binding affinities for Rpc37 and the Tfc4 subunit of the transcription initiation factor TFIIIC. Accordingly, we denote this Rpc53 N-terminus polypeptide as the TFIIIC-binding region or CBR. Alanine replacements in the CBR significantly reduced its binding affinity for Tfc4, highlighting its functional importance to cell growth and transcription in vitro. Our study reveals the functional basis for Rpc53's CBR in assembly of the pol III transcription initiation complex.

Effects of ultrasound treatment on muscle structure, volatile compounds, and small molecule metabolites of salted Culter alburnus fish.

This study investigated the effects of ultrasound treatment on the quality of salted Culter alburnus fish. The results showed that with the increasing ultrasound power, the structural degradation of muscle fibers was intensified, and the conformation of myofibrillar protein was significantly changed. The high-power ultrasound treatment group (300 W) had relatively higher thiobarbiturate reactive substance content (0.37 mg malondialdehyde eq/kg) and peroxidation value (0.63 mmol/kg). A total of 66 volatile compounds were identified with obvious differences among groups. The 200 W ultrasound group exhibited fewer fishy substances (Hexanal, 1-Pentene-3-ol, and 1-Octane-3-ol). Compared with control group, ultrasound groups (200, 300 W) contained more umami taste-related amino peptides such as γ-Glu-Met, γ-Glu-Ala, and Asn-pro. In the ultrasound treatment group, L-isoleucine and L-methionine, which may be used as flavor precursors, were significantly down-regulated, while carbohydrates and its metabolites were up-regulated. Amino acid, carbohydrate, and FA (fatty acyls) metabolism products in salted fish were enriched by ultrasound treatment, and those products might ultimately be related to the taste and flavor of salted fish.