Efficiency improvements on ninhydrin method for amino acid quantification

Injectable pH- and Ultrasound-Responsive Dual-Crosslinked Dextran/Chitosan/TiO2 Nanocomposite Hydrogels for Antibacterial Applications

Combining exogenous and endogenous antibacterial mechanisms has been demonstrated to enhance therapeutic efficacy significantly. This study constructs an innovative type of exogenous and endogenous antibacterial nanocomposite hydrogels with injectable dual-crosslinked networks and dual-stimuli responsiveness. The primary network establishes imine bonds between the functionalized dextran featuring norbornenes and aldehydes (NorAld-Dex) and the quaternized chitosan (QCS). The imine bonds provide self-healing, injectability, and pH-responsiveness to the hydrogel network. The secondary network is established by integrating thiolated mesoporous silica-coated titanium dioxide nanoparticles (TiO2@MS-SH) into the hydrogel network via an ultrasound-activated thiol-norbornene reaction with NorAld-Dex. The microstructures and properties of NorAld-Dex/QCS/TiO2@MS-SH hydrogels can be fine-tuned by adjusting the sonication time to increase the amount of thiol-norbornene crosslinks in the network. Effective antibacterial performance of NorAld-Dex/QCS/TiO2@MS-SH hydrogels at low pH has been demonstrated with the synergistic effect of the acid-induced dissociation of the hydrogel network, protonated QCS, and the reactive oxygen species (ROS) generated by TiO2@MS-SH nanoparticles under ultrasound irradiation. In summary, NorAld-Dex/QCS/TiO2@MS-SH nanocomposite hydrogel is an advanced dual stimuli-responsive antibacterial platform with customizable microstructures and properties, offering great potential for biomedical applications.

The Ninhydrin Reaction Revisited: Optimisation and Application for Quantification of Free Amino Acids

The ninhydrin reaction is commonly used for the detection of amino acids. However, in the literature, different conditions with respect to the buffer system, its pH and concentration, type of organic solvent, incubation time, and temperature, as well as the concentrations of the reagents, are described. To identify the most suitable conditions, colour development with reagents of varying compositions and different reaction temperatures and times were investigated using asparagine as a model amino acid. Asparagine was selected since it is one of the most abundant free amino acids in many types of samples. The optimal reaction mixture consisted of 0.8 mol L-1 potassium acetate, 1.6 mol L-1 acetic acid, 20 mg mL-1 ninhydrin and 0.8 mg mL-1 hydrindantin in DMSO/acetate buffer 40/60 (v/v) (final concentrations). The best reaction condition was heating the samples in 1.5 mL reaction tubes to 90 °C for 45 min. Afterwards, the samples were diluted with 2-propanol/water 50/50 (v/v) and the absorbance was measured at 570 nm. The proteinogenic amino acids showed a similar response except for cysteine and proline. The method was highly sensitive and showed excellent linearity as well as intra-day and inter-day reproducibility.

Unravelling the halophyte Suaeda maritima as an efficient candidate for phytostabilization of cadmium and lead: Implications from physiological, ionomic, and metabolomic responses

Cadmium (Cd) and lead (Pb) are among the most toxic heavy metals affecting human health and crop yield. Suaeda maritima (L.) Dumort is an obligate halophyte that is well adapted to saline soil. The inbuilt salinity tolerance mechanisms of halophytes help them to survive in heavy metal-contaminated rhizospheric soil. In the present study, growth and ionomic responses, reactive oxygen species (ROS) accumulation, modulations of phytochelatins, antioxidative defense, and metabolomic responses were studied in S. maritima imposed to Cd and Pb stresses with an aim to elucidate Cd and Pb tolerance mechanisms and phytoremediation potential of this halophyte. Our results showed a reduction of biomass in S. maritima, which may serve as an energy conservation strategy for survival under heavy metal stress. The increased accumulation of ROS with concomitant higher expression of various antioxidative enzymes suggests the efficient scavenging of ROS. The metabolite profiling revealed significant up-regulation of sugars, sugar alcohols, amino acids, polyphenols, and organic acids under Cd and Pb stresses suggesting their possible role in osmotic balance, ionic homeostasis, ROS scavenging, and signal transduction for stress tolerance. In S. maritima, the translocation factors (Tf) are <1 in both Cd and Pb treatments, which indicates that this halophyte has high phytostabilization potential for Cd and Pb in roots and through restricted translocation of heavy metal ions to the aboveground part. The findings of this study offer comprehensive information on Cd and Pb tolerance mechanisms in S. maritima and suggest that this halophyte can detoxify the HMs through physiological, ionic, antioxidative, and metabolic regulations.

Arbuscular mycorrhizal symbiosis modulates nitrogen uptake and assimilation to enhance drought tolerance of Populus cathayana

This study aims to investigate effects of arbuscular mycorrhizal fungi (AMF) inoculation on nitrogen (N) uptake and assimilation in Populus cathayana under drought stress (DS). Herein, we measured photosynthetic performance, antioxidant enzyme system, N level and N assimilation enzymes, proteins content and distribution, transcripts of genes associated with N uptake or transport in P. cathayana with AMF (AM) or without AMF (NM) under soil water limitation and adequate irrigation. Compared with NM-DS P. cathayana, the growth, gas exchange properties, antioxidant enzyme activities, total N content and the proportion of water-soluble and membrane-bound proteins in AM-DS P. cathayana were increased. Meanwhile, nitrate reductase (NR) activity, NO3- and NO2- concentrations in AM-DS P. cathayana were reduced, while NH4+ concentration, glutamine synthetase (GS) and glutamate synthetase (GOGAT) activities were elevated, indicating that AM symbiosis reduces NO3- assimilation while promoting NH4+ assimilation. Furthermore, the transcriptional levels of NH4+ transporter genes (PcAMT1-4 and PcAMT2-1) and NO3- transporter genes (PcNRT2-1 and PcNRT3-1) in AM-DS P. cathayana roots were significantly down-regulated, as well as NH4+ transporter genes (PcAMT1-6 and PcAMT4-3) in leaves. In AM P. cathayana roots, DS significantly up-regulated the transcriptional levels of RiCPSI and RiURE, the key N transport regulatory genes in AMF compared with adequate irrigation. These results indicated that AM N transport pathway play an essential role on N uptake and utilization in AM P. cathayana to cope with DS. Therefore, this research offers a novel perspective on how AM symbiosis enhances plant resilience to drought at aspect of N acquisition and assimilation.

Non-proteinogenic amino acids mitigate oxidative stress and enhance the resistance of common bean plants against Sclerotinia sclerotiorum

White mold, caused by the necrotrophic fungus Sclerotinia sclerotiorum, is a challenging disease to common bean cultivation worldwide. In the current study, two non-proteinogenic amino acids (NPAAs), γ-aminobutyric acid (GABA) and ß-alanine, were suggested as innovative environmentally acceptable alternatives for more sustainable management of white mold disease. In vitro, GABA and ß-alanine individually demonstrated potent dose-dependent fungistatic activity and effectively impeded the radial growth and development of S. sclerotiorum mycelium. Moreover, the application of GABA or ß-alanine as a seed treatment followed by three root drench applications efficiently decreased the disease severity, stimulated plant growth, and boosted the content of photosynthetic pigments of treated S. sclerotiorum-infected plants. Furthermore, although higher levels of hydrogen peroxide (H2O2), superoxide anion (O2 •-), and malondialdehyde (MDA) indicated that S. sclerotiorum infection had markedly triggered oxidative stress in infected bean plants, the exogenous application of both NPAAs significantly reduced the levels of the three studied oxidative stress indicators. Additionally, the application of GABA and ß-alanine increased the levels of both non-enzymatic (total soluble phenolics and flavonoids), as well as enzymatic (catalase [CAT], peroxidases [POX], and polyphenol oxidase [PPO]) antioxidants in the leaves of S. sclerotiorum-infected plants and improved their scavenging activity and antioxidant efficiency. Applications of GABA and ß-alanine also raised the proline and total amino acid content of infected bean plants. Lastly, the application of both NPAAs upregulated the three antioxidant-related genes PvCAT1, PvCuZnSOD1, and PvGR. Collectively, the fungistatic activity of NPAAs, coupled with their ability to alleviate oxidative stress, enhance antioxidant defenses, and stimulate plant growth, establishes them as promising eco-friendly alternatives for white mold disease management for sustainable bean production.

Crude Tieguanyin oolong tea polysaccharides regulate intestinal immune and gut microflora in dextran sulfate sodium-induced mice colitis

BACKGROUND

The global incidence and prevalence of inflammatory bowel diseases (IBDs) have been increasing. Epidemiological studies, clinical trials, and animal experiments have indicated a negative association between the consumption of tea and IBD. This study aims to investigate the protective effects of crude Tieguanyin oolong tea polysaccharides (CTPS) on experimental colitis, while also exploring the underlying mechanisms.

RESULTS

The administration of CTPS significantly alleviated IBD in the mouse model, and was found to regulate T-cell mediated immune responses in the colon by modulating cytokine production associated with T cells. Furthermore, CTPS demonstrated a positive impact on the gut microbiota, reversing the increase in pathogenic Helicobacter and enhancing the relative abundances of beneficial bacteria such as Akkermansia, Lachnospiraceae, and Odoribacter. Oral administration of CTPS also led to an improvement in intestinal metabolism, specifically by increasing the levels of short-chain fatty acids.

CONCLUSION

This study provides the first in vivo evidence of the protective effects of CTPS on colitis in mice. The effects are likely facilitated through the regulation of T cell-mediated responses and modulation of the gut microbiota, suggesting that CTPS may be a potential preventive and therapeutic approach for IBD. © 2023 Society of Chemical Industry.

Biochemical and Transcriptome Analyses Reveal a Stronger Capacity for Photosynthate Accumulation in Low-Tillering Rice Varieties

Moderate control of rice tillering and the development of rice varieties with large panicles are important topics for future high-yield rice breeding. Herein, we found that low-tillering rice varieties stopped tillering earlier and had a larger leaf area of the sixth leaf. Notably, at 28 days after sowing, the rice seedlings of the low-tillering group had an average single-culm above-ground biomass of 0.84 g, significantly higher than that of the multi-tillering group by 56.26%, and their NSC (non-structural carbohydrate) and starch contents in sheaths were increased by 43.34% and 97.75%, respectively. These results indicated that the low-tillering group of rice varieties had a stronger ability to store photosynthetic products in the form of starch in their sheaths, which was thus more beneficial for their large panicle development. The results of carbon and nitrogen metabolism analyses showed that the low-tillering group had a relatively strong carbon metabolism activity, which was more favorable for the accumulation of photosynthesis products and the following development of large panicles, while the multi-tillering group showed relatively strong nitrogen metabolism activity, which was more beneficial for the development and formation of new organs, such as tillers. Accordingly, in the low-tillering rice varieties, the up-regulated genes were enriched in the pathways mainly related to the synthesis of carbohydrates, while the down-regulated genes were mainly enriched in the nitrogen metabolism pathways. This study provides new insights into the mechanism of rice tillering regulation and promotes the development of new varieties with ideal plant types.

Stimulating extracellular polymeric substances production in integrated fixed-film activated sludge reactor for advanced nitrogen removal from mature landfill leachate via one-stage double anammox

Introducing carbon sources to achieve nitrogen removal from mature landfill leachate not only increases the costs and carbon emissions but also inhibits the activity of autotrophic bacteria. Thus, this study constructed a double anammox system that combines partial nitrification-anammox (PNA) and endogenous partial denitrification-anammox (EPDA) within an integrated fixed-film activated sludge (IFAS) reactor. In this system, PNA primarily contributes to nitrogen removal pathways, achieving a nitrite accumulation rate of 98.23%. The production of extracellular polymer substances (EPS) in the IFAS reactor is stimulated by introducing co-fermentation liquid. Through the utilization of EPS, the system effectively achieves EPDA with the nitrite transformation rate of 97.20%. Under the intermittent aeration operation strategy, EPDA combined with PNA and anammox in the oxic and anoxic stages enhanced the nitrogen removal efficiency of the system to 99.70 ± 0.12%. The functional genus Candidatus kuenenia became enriched in biofilm sludge, while Thauera and Nitrosomonas predominated in floc sludge.

Engineering pH-sensitive erodible chitosan hydrogel composite containing bacteriophage: An interplay between hydrogel and bacteriophage against Staphylococcus aureus

Encapsulation of phages represents a key approach for improving phage stability and controlling phage delivery dosage. The hydrogel made from positively charged quaternized chitosan (QCS) and multivalent crosslinker, aldehyde-modified poly(xylitol sebacate)-co-poly(ethylene glycol) (APP) was introduced for the first time for drug (phage 44AHJD) delivery. The freeze-thawing (FT) treatment enhanced the porous structure and the stress resistance of native hydrogel with increased compression stress (stiffness) from 10 to 20 kPa. The stiffness of the phage-loaded hydrogel (FTP) was suitable for the proper release of phage particles and polymer chains, both working synergistically against bacterial growth. The FTP followed the Korsmeyer-Peppas model's anomalous diffusion of phage particles at different temperatures (30-45 °C) and pH (6.6-8.5) conditions. FTP was sensitive to pH, which released more phage particles at pH-neutral conditions, while the release under acidic and alkaline conditions was more based on gel degradation. The high biocompatibility of FTP hydrogel at its working concentration of 30 mg mL-1 was demonstrated through a hemolysis ratio of <2 %. Sixty percent of the total encapsulated phages and 6 mg mL-1 of hydrogel debris were released after 10 h of hydrogel submerge treatment, which can fight the growing bacteria and the emergence of phage-resistant bacteria.

A Novel Methacryloyl Chitosan Hydrogel Microneedles Patch with Sustainable Drug Release Property for Effective Treatment of Psoriasis

Psoriasis is a chronic and recurrent skin disease that often requires long-term treatment, and topical transdermal drug delivery can reduce systemic side effects. However, it is still a challenge in efficient transdermal drug delivery for psoriasis treatment due to low penetration efficiency of most drugs and the abnormal skin conditions of psoriasis patients. Here, a safe and effective methacryloyl chitosan hydrogel microneedles (CSMA hMNs) patch is developed and served as a sustained drug release platform for the treatment of psoriasis. By systematically optimizing the CSMA preparation, CSMA hMNs with excellent morphological characteristics and strong mechanical properties (0.7 N needle-1 ) are prepared with a concentration of only 3% (w/v) CSMA. As a proof-of-concept, methotrexate (MTX) and nicotinamide (NIC) are loaded into CSMA hMNs patch, which can produce a sustained drug release of 80% within 24 h in vitro. In vivo experiments demonstrated that the CSMA hMNs patch can effectively inhibit the skin thickening and spleen enlargement of psoriatic mice and has a good biosafety profile at sufficient therapeutic doses. This study provides a new idea for the preparation of hMN systems using modified CS or other biocompatible materials and offers an effective therapeutic option for psoriasis treatment.

An amperometric method for the determination of cystine in urine samples and pharmaceutical tablets using screen-printed silver electrodes

Elevated urinary cystine levels are closely associated with the development of cystine stone. Therefore, the ability to rapidly and efficiently determine urinary cystine levels is crucial for physicians to manage patients with cystinuria or those undergoing cystine medication. In this study, an amperometric method employing a commercial screen-printed silver electrode was successfully established. The resulting calibration curve indicated a detection limit of 0.65 mg/dL. Satisfactory recoveries ranging from 89% to 109% were obtained for urine samples. The method was also effective for the quality control analysis of cystine in pharmaceutical tablets. The recovery of cystine from pharmaceutical tablets ranged from 98% to 101% using the developed method. This method enables the rapid and accurate determination of cystine in both urine samples and pharmaceutical tablets and provides valuable information for clinical diagnosis and pharmaceutical quality control.

Construction of co-immobilized multienzyme systems using DNA-directed immobilization technology and multifunctionalized nanoparticles

The multienzyme co-immobilization systems with high cascade catalytic efficiency and selectivity have attracted considerable attention. In this study, through DNA-directed immobilization (DDI) technology, two model enzymes, glucose oxidase (GOD) and horseradish peroxide (HRP) were co-immobilized on the multifunctional silica nanoparticles (DDI enzyme). In addition to the directional distribution promoted by DNA complementary chains, the multienzyme system allowed the control of the stoichiometric ratio of the enzymes by adjusting the ratio of amino/carboxyl groups. The optimal mole ratio of GOD/HRP was 1:2, while the protein loading amount could reach 8.06 mg·g-1. Compared with the conventional direct adsorption, the catalytic activity of the DDI enzyme was 2.49 times higher. Moreover, with the enhancement of thermal and mechanical stability, the DDI enzyme could still retain at least 50% of its initial activity after 12 cycles. Accompanied by an excellent response and good selectivity, the constructed multienzyme systems simultaneously showed the potential as a glucose detector. Therefore, based on the DDI technology, the highly efficient multienzyme co-immobilization system could be further extended for a wider range of research fields.

Salt priming induces low-temperature tolerance in sugar beet via xanthine metabolism

To understand the physiological mechanisms involved in xanthine metabolism during salt priming for improving low-temperature tolerance, salt priming (SP), xanthine dehydrogenase inhibitor (XOI), exogenous allantoin (EA), and back-supplemented EA (XOI + EA) treatments were given and the low-temperature tolerance of sugar beet was tested. Under low-temperature stress, salt priming promoted the growth of sugar beet leaves and increased the maximum quantum efficiency of PS II (Fv/Fm). However, during salt priming, either XOI or EA treatment alone increased the content of reactive oxygen species (ROS), such as superoxide anion and hydrogen peroxide, in the leaves under low-temperature stress. XOI treatment increased allantoinase activity with its gene (BvallB) expression under low-temperature stress. Compared to the XOI treatment, the EA treatment alone and the XOI + EA treatment increased the activities of antioxidant enzymes. At low temperatures, the sucrose content and the activity of key carbohydrate enzymes (AGPase, Cylnv, and FK) were significantly reduced by XOI compared to the changes under salt priming. XOI also stimulated the expression of protein phosphatase 2C and sucrose non-fermenting1-related protein kinase (BvSNRK2). The results of a correlation network analysis showed that BvallB was positively correlated with malondialdehyde, D-Fructose-6-phosphate, and D-Glucose-6-phosphate, and negatively correlated with BvPOX42, BvSNRK2, dehydroascorbate reductase, and catalase. These results suggested that salt-induced xanthine metabolism modulated ROS metabolism, photosynthetic carbon assimilation, and carbohydrate metabolism, thus enhancing low-temperature tolerance in sugar beet. Additionally, xanthine and allantoin were found to play key roles in plant stress resistance.

Biodegradable and switchable near-infrared fluorescent probes for hypoxia detection

Aims: Among solid tumors, hypoxia is a common characteristic and responsible for chemotherapeutic resistance. Hypoxia-sensitive imaging probes are therefore essential for early tumor detection, growth monitoring and drug-response evaluation. Despite significant efforts, detecting hypoxic oxygen levels remains challenging. Materials & methods: This paper demonstrates the use of an amine-rich carbon dot probe functionalized with an imidazole group that exhibits reversible fluorescence switching in normoxic and hypoxic environments. Results & conclusion: We demonstrate the ability to emit near-infrared light only under hypoxic conditions. The probes are found to be biodegradable in the presence of human digestive enzymes such as lipase. Ex vivo tissue imaging experiments revealed promising near-infrared signals even at a depth of 5 mm for the probe under ex vivo imaging conditions.

A cleaner leather chemical from feather waste for reducing ammonia-nitrogen pollution and improving biological treatment efficiency of tannery wastewater

Feather waste is produced in millions of tons globally every year, resulting in a waste of biomass resources and even environmental pollution. A sustainable strategy for utilizing feather waste was proposed by preparing a clean deliming agent for ammonia-nitrogen (NH₃-N) reduction in leather manufacture and biological treatment efficiency improvement of tannery wastewater. Briefly, chicken feather wastes were deeply hydrolyzed with sulfuric acid, and the optimized keratin hydrolysate (KH_opt) that contained 53.6% crude protein and 41.2% amino acids, such as glutamic acid, serine, proline, leucine, phenylalanine, glycine, valine, and arginine, was obtained and used to delime limed cattle hides. The appropriate ratio of amino acids in KH_opt gave KH_opt a great pH-buffering capacity and maintained a stable float pH of approximately 9 throughout the deliming process. The isoelectric points of KH_opt (3.8) and the limed hide (6.3) were both lower than the float pH, thereby bringing about an electrostatic repulsion between the KH_opt and the hide surface, which is helpful for KH_opt to penetrate and deswell the limed hide rapidly. Moreover, the KH_opt deliming effectively removed calcium from the limed hide and achieved leather comparable to conventional leather for commercial applications. KH_opt reduced the NH₃-N concentrations of deliming effluent and tannery wastewater by 91.1% and 80.6%, respectively, compared with the conventional deliming agent (ammonium sulfate), and dramatically increased the biological treatment efficiency of tannery wastewater. The results showed that efficient and high-value use of feather waste was made by preparing KH_opt for sustainable leather manufacturing.

Within leaf nitrogen allocation regulates the photosynthetic behavior of xerophytes in response to increased soil rock fragment content

There is limited information on how plant functional traits vary with soil rock fragment content (RFC), especially for xerophytes growing in stony soils. We examined leaf functional traits of three xerophytes (Sophora davidii; Cotinus szechuanensi; and Artemisia vestita) grown under an RFC gradient in a heavy loamy soil. Our results show that photosynthetic capacity increased linearly with RFC in S. davidii, whereas unimodal patterns were observed for the other two species. The RFC that maximized photosynthetic capacity (A_sat) and photosynthetic N use efficiency (PNUE) were achieved by allocating more N to photosynthetic apparatus at the expense of cell walls. For C. szechuanensis, the increased fraction of photosynthetic N allocated to carboxylation (P_C) bioenergetics (P_B), and thylakoid light-harvesting components (P_L) together contributed to the higher A_sat and PNUE values. As for S. davidii, both P_C and P_B mainly contributed to higher A_sat and PNUE, whereas for A. vestita only P_B was the main contributor. Our results suggest that increased non-capillary porosity of high RFC soil conditions through promoting the root growth of S. davidii and C. szechuanensis ensures sufficient water and N supply for photosynthetic capacity. In shallow-rooted species A. vestita, low RFC soil maintained higher nitrate N in the topsoil, enhancing leaf photosynthetic capacity. We conclude that rock fragments promoted leaf photosynthetic capacity in the studied loamy soil system, but the promoting effect was species-specific. The results highlight the relevance of consideration of soil rock fraction in evaluation of photosynthetic behavior of xerophytes in heterogeneous rocky soils.

Comparative Analysis of the Alkaline Proteolytic Enzymes of Yarrowia Clade Species and Their Putative Applications

Proteolytic enzymes are commercially valuable and have multiple applications in various industrial sectors. The most studied proteolytic enzymes produced by Yarrowia lipolytica, extracellular alkaline protease (Aep) and extracellular acid protease (Axp), were shown to be good candidates for different biotechnological applications. In this study, we performed a comprehensive analysis of the alkaline proteolytic enzymes of Yarrowia clade species, including phylogenetic studies, synteny analysis, and protease production and application. Using a combination of comparative genomics approaches based on sequence similarity, synteny conservation, and phylogeny, we reconstructed the evolutionary scenario of the XPR2 gene for species of the Yarrowia clade. Furthermore, except for the proteolytic activity of the analyzed Yarrowia clade strains, the brewers’ spent grain (BSG) was used as a substrate to obtain protein hydrolysates with antioxidant activity. For each culture, the degree of hydrolysis was calculated. The most efficient protein hydrolysis was observed in the cultures of Y. lipolytica, Y. galli, and Y. alimentaria. In contrast, the best results obtained using the 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) method were observed for the culture medium after the growth of Y. divulgata, Y. galli, and Y. lipolytica on BSG.

Differential responses of contrasting low phosphorus tolerant cotton genotypes under low phosphorus and drought stress

BACKGROUND

Drought is one of the main reasons for low phosphorus (P) solubility and availability.

AIMS

The use of low P tolerant cotton genotypes might be a possible option to grow in drought conditions.

METHODS

This study investigates the tolerance to drought stress in contrasting low P-tolerant cotton genotypes (Jimian169; strong tolerant to low P and DES926; weak tolerant to low P). In hydroponic culture, the drought was artificially induced with 10% PEG in both cotton genotypes followed by low (0.01 mM KH₂PO₄) and normal (1 mM KH₂PO₄) P application.

RESULTS

The results showed that under low P, PEG-induced drought greatly inhibited growth, dry matter production, photosynthesis, P use efficiency, and led to oxidative stress from excessive malondialdehyde (MDA) and higher accumulation of reactive oxygen species (ROS), and these effects were more in DES926 than Jimian169. Moreover, Jimian169 alleviated oxidative damage by improving the antioxidant system, photosynthetic activities, and an increase in the levels of osmoprotectants like free amino acids, total soluble proteins, total soluble sugars, and proline.

CONCLUSIONS

The present study suggests that the low P-tolerant cotton genotype can tolerate drought conditions through high photosynthesis, antioxidant capacity, and osmotic adjustment.

Sustained release of alpha-methylacyl-CoA racemase (AMACR) antibody-conjugated and free doxorubicin from silica nanoparticles for prostate cancer cell growth inhibition

This article presents silica nanoparticles for the sustained release of AMACR antibody-conjugated and free doxorubicin (DOX) for the inhibition of prostate cancer cell growth. Inorganic MCM-41 silica nanoparticles were synthesized, functionalized with phenylboronic acid groups (MCM-B), and capped with dextran (MCM-B-D). The nanoparticles were then characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, zeta potential analysis, nitrogen sorption, X-ray diffraction, and thermogravimetric analysis, before exploring their potential for drug loading and controlled drug release. This was done using a model prostate cancer drug, DOX, and a targeted prostate cancer drug, α-Methyl Acyl-CoA racemase (AMACR) antibody-conjugated DOX, which attaches specifically to AMACR proteins that are overexpressed on the surfaces of prostate cancer cells. The kinetics of sustained drug release over 30 days was then studied using zeroth order, first order, second order, Higuchi, and the Korsmeyer-Peppas models, while the thermodynamics of drug release was elucidated by determining the entropy and enthalpy changes. The flux of the released DOX was also simulated using the COMSOL Multiphysics software package. Generally, the AMACR antibody-conjugated DOX drug-loaded nanoparticles were more effective than the free DOX drug-loaded formulations in inhibiting the growth of prostate cancer cells in vitro over a 96 h period. The implications of the results are then discussed for the development of drug-eluting structures for the localized and targeted treatment of prostate cancer.

Physiological, epigenetic, and proteomic responses in Pfaffia glomerata growth in vitro under salt stress and 5-azacytidine

Plants adjust their complex molecular, biochemical, and metabolic processes to overcome salt stress. Here, we investigated the proteomic and epigenetic alterations involved in the morphophysiological responses of Pfaffia glomerata, a medicinal plant, to salt stress and the demethylating agent 5-azacytidine (5-azaC). Moreover, we investigated how these changes affected the biosynthesis of 20-hydroxyecdysone (20-E), a pharmacologically important specialized metabolite. Plants were cultivated in vitro for 40 days in Murashige and Skoog medium supplemented with NaCl (50 mM), 5-azaC (25 μM), and NaCl + 5-azaC. Compared with the control (medium only), the treatments reduced growth, photosynthetic rates, and photosynthetic pigment content, with increase in sucrose, total amino acids, and proline contents, but a reduction in starch and protein. Comparative proteomic analysis revealed 282 common differentially accumulated proteins involved in 87 metabolic pathways, most of them related to amino acid and carbohydrate metabolism, and specialized metabolism. 5-azaC and NaCl + 5-azaC lowered global DNA methylation levels and 20-E content, suggesting that 20-E biosynthesis may be regulated by epigenetic mechanisms. Moreover, downregulation of a key protein in jasmonate biosynthesis indicates the fundamental role of this hormone in the 20-E biosynthesis. Taken together, our results highlight possible regulatory proteins and epigenetic changes related to salt stress tolerance and 20-E biosynthesis in P. glomerata, paving the way for future studies of the mechanisms involved in this regulation.

Sensitivity Intensified Ninhydrin-Based Chromogenic System by Ethanol-Ethyl Acetate: Application to Relative Quantitation of GABA

Gamma-aminobutyric acid (GABA) is a functional metabolite in various organisms. Herein, a sensitivity intensified ninhydrin-based chromogenic system (SINICS), achieved by ethanol and ethyl acetate, is described for the reliable relative quantitation of GABA. A 2.9 mL SINICS kit comprises 1% ninhydrin, 40% ethanol, 25% ethyl acetate, and 35 μL 0.2 M sodium acetate buffer (pH 5.0). In practice, following the addition of a 0.1 mL sample to the kit, the chromogenic reaction is completed by heating at 70 °C for 30 min. The kit increased the color development sensitivity of L-glutamic acid and GABA, with the detection limits being reduced from 20 mM and 200 mM to 5 mM and 20 mM, respectively. The chromophore was stable for at least 2 h at room temperature, which was sufficient for a routine colorimetric analysis. The absorbance at 570 nm with the deduction of background directly represents the content of amino acid. For a proof-of-concept, the SINICS was adopted to optimize the GABA fermentation process of Levilactobacillus brevis CD0817. The results demonstrated that SINICS is an attractive alternative to the available ninhydrin-based colorimetric methods.

Principal Component Analysis to Assess the Changes of Yield and Quality in Pinellia ternata at Different Stages after Brassinolide Treatments

Brassinolide (BR) is the "sixth class" plant hormone, which plays an important role in various physiological and biochemical processes of plants. The wide variety of functions of Pinellia ternata means that there is huge demand for it and thus it is in short supply. This paper mainly assessed the changes of yield and quality in P. ternata at different stages after BR treatments by principal component analysis, in order to improve the yield and quality of P. ternata and at the same time determine the best harvest time. The results showed that the tuber yield of P. ternata was significantly increased by BR treatments at different stages (except for the 15th day). After the 15th, 45th, 60th, 75th, 90th, and 105th day of treatments, the tuber yield of P. ternata reached peak values at 0.10 (0.65 g), 0.50 (1.97 g), 0.50 (1.98 g), 1.00 (2.37 g), 1.00 (2.84 g), and 2.00 mg/L (3.76 g) BR treatment, respectively. The optimal harvest time was the 75th day after 0.10, 0.50, and 1.00 mg/L BR treatments, which not only significantly improved the yield of P. ternata, but also retained high level of total alkaloids in the tubers (20.89, 5.37, and 13.44%) and bulbils (9.74, 20.42, and 13.62%), high total flavone content in the tubers (17.66, 16.26, and 12.74%) and bulbils (52.63, 12.79, and 38.69%), and high β-sitosterol content in the tubers (25.26, 16.65, and 0.62%) of P. ternata, compared with the control, respectively.

Biodegradation of Pine Processionary Caterpillar Silk Is Mediated by Elastase- and Subtilisin-like Proteases

Pine processionary caterpillar nests are made from raw silk. Fibroin protein is the main component of silk which, in the case of pine processionary caterpillar, has some unusual properties such as a higher resistance to chemical hydrolysis. Isolation of microorganisms naturally present in silk nests led to identification of Bacillus licheniformis and Pseudomonas aeruginosa strains that in a defined minimal medium were able to carry out extensive silk biodegradation. A LasB elastase-like protein from P. aeruginosa was shown to be involved in silk biodegradation. A recombinant form of this protein expressed in Escherichia coli and purified by affinity chromatography was able to efficiently degrade silk in an in vitro assay. However, silk biodegradation by B. licheniformis strain was mediated by a SubC subtilisin-like protease. Homologous expression of a subtilisin Carlsberg encoding gene (subC) allowed faster degradation compared to the biodegradation kinetics of a wildtype B. licheniformis strain. This work led to the identification of new enzymes involved in biodegradation of silk materials, a finding which could lead to possible applications for controlling this pest and perhaps have importance from sanitary and biotechnological points of view.

Enhancement of Antioxidant Property of N-Carboxymethyl Chitosan and Its Application in Strawberry Preservation

Bio-enzymatic grafting phenolic acid to chitosan derivative is an efficient and environmentally friendly molecular synthesis technology. In the present study, N-carboxymethyl chitosan (CMCS) was grafted with gallic acid (GA) using recombinant bacterial laccase from Streptomyces coelicolor as a catalyst. GA and CMCS were successfully grafted as determined by measuring amino acid content, Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-Vis) spectroscopy. Then, the effect of GA-g-CMCS coating on the freshness of strawberries at 20 ± 2 °C was explored. The physiological and biochemical quality indicators of strawberries during storage were monitored. The 1.5% GA-g-CMCS coating helped to protect the antioxidant properties and nutrients of strawberries and extend the shelf life. Specifically, it reduced the weight loss of strawberries during preservation (originally 12.7%) to 8.4%, maintained titratable acidity content (TA) residuals above 60% and reduced decay rate from 36.7% to 8.9%. As a bioactive compound, GA-g-CMCS has the potential to become an emerging food packing method. These results provide a theoretical basis and reference method for the subsequent synthesis and application of CMCS derivatives.

Volatile organic compounds from Lysinibacillus macroides regulating the seedling growth of Arabidopsis thaliana

Volatile organic compounds (VOCs) have the characteristics of long distance propagation, low concentration, perception, and indirect contact between organisms. In this experiment, Lysinibacillus macroides Xi9 was isolated from cassava residue, and the VOCs produced by this strain were analyzed by the SPME-GC-MS method, mainly including alcohols, esters, and alkanes. By inoculation of L. macroides Xi9, VOCs can promote the growth and change the root-system architecture of Arabidopsis seedlings. The results showed that the number of lateral roots, root density, and fresh weight of Arabidopsis seedlings were significantly higher (p ≤ 0.01), and the number of roots hair was also increased after exposure to strain Xi9. Compared with the control group, the transcriptome analysis of Arabidopsis seedlings treated with strain Xi9 for 5 days revealed a total of 508 genes differentially expressed (p < 0.05). After Gene Ontology enrichment analysis, it was found that genes encoding nitrate transport and assimilation, and the lateral root-related gene ANR1 were up-regulated. The content of NO3 - and amino acid in Arabidopsis seedlings were significantly higher from control group (p ≤ 0.01). Plant cell wall-related EXPA family genes and pectin lyase gene were up-regulated, resulting cell elongation of leaf. SAUR41 and up-regulation of its subfamily members, as well as the down-regulation of auxin efflux carrier protein PILS5 and auxin response factor 20 (ARF20) led to the accumulation of auxin. These results indicated that VOCs of strain Xi9 promote Arabidopsis seedlings growth and development by promoting nitrogen uptake, regulating auxin synthesis, and improving cell wall modification.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-022-01268-3.

Adsorption Behavior of the L-Theanine onto Cation Exchange Resin ZGSPC106Na and D001SD

Adsorption is an important technology for the separation of different tea components. The adsorption behavior of L-theanine onto adsorbents was comprehensively studied in this paper. Among tested adsorbents, cation exchange resin ZGSPC106Na and D001SD were suitable for separating L-theanine, PVPP and PA-6 for catechins and macroporous resin HPD-400 for caffeine. Adsorption of L-theanine onto the cation resins was significantly influenced by the acidity, contact time and temperature. The adsorption behavior could be described by the pseudo-second-order rate equation and fitted to Langmuir and Freundlich models. ZGSPC106Na exhibited higher adsorption capacity, while D001SD showed higher adsorption selectivity. These might be attributed to the distinctive structure of the two resins and different ionization of the adsorbates. A method for simultaneous preparation of decaffeinated polyphenols, caffeine-enriched extract and decaffeinated L-theanine was established through successive separation on the columns fulfilled with PA-6, HPD-400 and D001SD, respectively.

Development of alginate-spermidine micro/nanogels as potential antioxidant and anti-inflammatory tool in peripheral nerve injuries. Formulation studies and physico-chemical characterization

The development of a successful strategy to ensure a full recovery in patients affected by peripheral nerve injury (PNI), one of the most debilitating pathologies, is, still today, a major clinical challenge. Herein, spermidine (SP), an endogenous polyamine, is employed with a dual role: as cross-linking agent for alginate (ALG) and as antioxidant and anti-inflammatory compound. In particular, micro/nanogels based on the ionic interaction between ALG and SP were obtained via ionotropic gelation. Different ALG concentrations and viscosity grades and different SP concentrations were considered. The influence of such variables on micro/nanogels size was investigated by means of a Design of Experiments (DoE) approach (full factorial design). The formation of micro/nanogels was proved by Scanning Electron Microscope (SEM) analysis and by rheological and profilometry measurements. Fourier Transform Infrared (FTIR) measurements performed on nanogels of optimal composition confirmed SP-ALG interaction. The addition of trehalose as cryoprotectant agent to nanogel dispersion was considered in view of the employment of freeze-drying process to obtain a stable product. Moreover, in vitro studies on Schwann cells proved the ability of SP of expressing antioxidant and anti-inflammatory properties, even if involved in the formation of nanogels.

Proposed protocol for rate-limiting step determination during anaerobic digestion of complex substrates

Anaerobic digestion is a complex process, involving various microorganism groups and, consequently, several reactions. An easy-to-use protocol for the rate-limiting step determination of the process is proposed. The hydrogen production, acetate production, and acetate consumption rates can be calculated, according to a structured algorithm. During the rate limiting step determination, several compounds (biopolymer and monomer representatives, as well as sodium acetate) were used, combined or not with the substrate, to draw the corresponding conclusions. Three substrates were tested, characterized by specific organic compound groups (carbohydrates, proteins, and fats). All three substrates followed the acetate-consuming pathway for the organic matter conversion to methane. In this study, the rate-limiting step for the pathway of acetate consumption was acetate production. Determining the rate-limiting step through the proposed protocol can point to the appropriate actions needed to boost methane production, like substrate pretreatment, using an acidogenic reactor, or checking for the presence of inhibitors.

Dual Dynamic Covalently Crosslinked Alginate Hydrogels with Tunable Properties and Multiple Stimuli-Responsiveness

Alginate is a biopolymer that can be crosslinked with calcium ions to fabricate cytocompatible hydrogels. However, using calcium ions to crosslink alginate provides limited properties and functions to alginate hydrogels, restricting their biomedical applications. Here, phenylboronic acid-functionalized polyethyleneimine (PBA-PEI) was developed to introduce two orthogonal dynamic covalent crosslinks in the alginate hydrogels, where PBA-PEI was used to crosslink alginate dialdehyde (ADA) through imine bonds and boronate ester bonds. The grafting degree of PBA in the PEI structure was applied to fine-tune the properties of PBA-PEI/ADA hydrogels, including the rheological property, mechanical strength, swelling behavior, and antibacterial activity. In particular, the highly sensitive boronate ester bonds in the network enabled PBA-PEI/ADA hydrogels to be responsive to several stimuli, such as glucose, fructose, and hydrogen peroxide. Taken together, PBA-PEI/ADA hydrogels with tunable properties and multiple stimuli-responsiveness have been demonstrated as smart biomaterials for advanced biomedical applications.

A convenient ninhydrin assay in 96-well format for amino acid-releasing enzymes using an air-stable reagent

An improved and convenient ninhydrin assay for aminoacylase activity measurements was developed using the commercial EZ Nin™ reagent. Alternative reagents from literature were also evaluated and compared. The addition of DMSO to the reagent enhanced the solubility of Ruhemann's purple (RP). Furthermore, we found that the use of a basic, aqueous buffer enhances stability of RP. An acidic protocol for the quantification of lysine was developed by addition of glacial acetic acid. The assay allows for parallel processing in a 96-well format with measurements microtiter plates.

Protein Quality Evaluation of Some Commonly Consumed Bird Egg Varieties Using Amino Acid Scores

Objective

Food proteins provide amino acids (AAs) and serve as building blocks of all vital organs, muscles, hormones, and biological fluids such as blood. Eggs are known as a good source of protein. This study compared the protein quality of bird eggs (raw and boiled), using their AA scores since some individuals consume raw eggs for various reasons. Research Methods. Eggs studied were exotic chicken, local chicken, turkey, quail, and guinea fowl eggs. The eggs were shelled and their contents (boiled and raw) lyophilized. The standard AOAC method (Kjeldahl) was used to determine protein content, while the amino acid composition was measured using an AA analyzer. The total AA scores were calculated based on the whole hen's egg AA profiles. Statistical significance was accepted at p < 0.05.

Results

The Guinea fowl egg had the highest total amino acid score (TAAS) of 0.92. The other scores ranged as follows: 0.82 (quail) >0.81 (turkey) >0.75 (exotic chicken), and the lowest score was 0.65 (local chicken). The least scores were phenylalanine: 0.34 (exotic chicken), phenylalanine and serine: 0.36 (local chicken), leucine and aspartic acid: 0.41 (turkey), methionine: 0.31 (quail), and glutamic acid: 0.33 (guinea fowl). Also, guinea fowl egg had the highest total essential amino acid (TEAA) (49.6 g/100 g protein), i.e., % TEAA (55.1%), while exotic chicken egg had the lowest (41.1%), but the highest % NEAA (58.9%).

Conclusion

Guinea fowl eggs had the highest EAA and TAA content. Its consumption should particularly be encouraged for children as this can significantly reduce the risk of protein-energy malnutrition and prevent protein deficiencies.

Globule and fiber formation with elastin-like polypeptides: a balance of coacervation and crosslinking

Elastic fiber assembly is a complex process that requires the coacervation and cross-linking of the protein building block tropoelastin. To date, the order, timing, and interplay of coacervation and crosslinking is not completely understood, despite a great number of advances into understanding the molecular structure and functions of the many proteins involved in elastic fiber assembly. With a simple in vitro model using elastin-like polypeptides and the natural chemical crosslinker genipin, we demonstrate the strong influence of the timing and kinetics of crosslinking reaction on the coacervation, crosslinking extent, and resulting morphology of elastin. We also outline a method for analyzing elastin droplet network formation as a heuristic for measuring the propensity for elastic fiber formation. From this we show that adding crosslinker during peak coacervation dramatically increases the propensity for droplet network formation.

Enhanced stability of complex coacervate core micelles following different core-crosslinking strategies

Complex coacervate core micelles (C3Ms) are formed by mixing aqueous solutions of a charged (bio)macromolecule with an oppositely charged-neutral hydrophilic diblock copolymer. The stability of these structures is dependent on the ionic strength of the solution; above a critical ionic strength, the micelles will completely disintegrate. This instability at high ionic strengths is the main drawback for their application in, e.g., drug delivery systems or protein protection. In addition, the stability of C3Ms composed of weak polyelectrolytes is pH-dependent as well. The aim of this study is to assess the effectiveness of covalent crosslinking of the complex coacervate core to improve the stability of C3Ms. We studied the formation of C3Ms using a quaternized and amine-functionalized cationic-neutral diblock copolymer, poly(2-vinylpyridine)-block-poly(ethylene oxide) (QP2VP-b-PEO), and an anionic homopolymer, poly(acrylic acid) (PAA). Two different core-crosslinking strategies were employed that resulted in crosslinks between both types of polyelectrolyte chains in the core (i.e., between QP2VP and PAA) or in crosslinks between polyelectrolyte chains of the same type only (i.e., QP2VP). For these two strategies we used the crosslinkers 1-ethyl-3-(3'-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and dimethyl-3,3'-dithiopropionimidate dihydrochloride (DTBP), respectively. EDC provides permanent crosslinks, while DTBP crosslinks can be broken by a reducing agent. Dynamic light scattering showed that both approaches significantly improved the stability of C3Ms against salt and pH changes. Furthermore, reduction of the disulphide bridges in the DTBP core-crosslinked micelles largely restored the original salt-stability profile. Therefore, this feature provides an excellent starting point for the application of C3Ms in controlled release formulations.

Green Synthesis of Gold and Silver Nanoparticles Using Leaf Extract of Capsicum chinense Plant

So far, several studies have focused on the synthesis of metallic nanoparticles making use of extracts from the fruit of the plants from the genus Capsicum. However, as the fruit is the edible, and highly commercial, part of the plant, in this work we focused on the leaves, a part of the plant that is considered agro-industrial waste. The biological synthesis of gold (AuNPs) and silver (AgNPs) nanoparticles using aqueous extracts of root, stem and leaf of Capsicum chinense was evaluated, obtaining the best results with the leaf extract. Gold and silver nanoparticles synthesized using leaf extract (AuNPs-leaf and AgNPs-leaf, respectively) were characterized by UV-visible spectrophotometry (UV-Vis), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR-ATR), X-ray Photoelectron Spectroscopy (XPS), Ultra Hight Resolution Scanning Electron Microscopy coupled to Energy-Dispersive X-ray spectroscopy (UHR-SEM-EDX) and Transmission Electron Microscopy (TEM), and tested for their antioxidant and antimicrobial activities. In addition, different metabolites involved in the synthesis of nanoparticles were analyzed. We found that by the use of extracts derived from the leaf, we could generate stable and easy to synthesize AuNPs and AgNPs. The AuNPs-leaf were synthesized using microwave radiation, while the AgNPs-leaf were synthesized using UV light radiation. The antioxidant activity of the extract, determined by ABTS, showed a decrease of 44.7% and 60.7% after the synthesis of the AuNPs-leaf and AgNPs-leaf, respectively. After the AgNPs-leaf synthesis, the concentration of polyphenols, reducing sugars and amino acids decreased by 15.4%, 38.7% and 46.8% in the leaf extract, respectively, while after the AuNPs-leaf synthesis only reducing sugars decreased by 67.7%. These results suggest that these groups of molecules are implicated in the reduction/stabilization of the nanoparticles. Although the contribution of these compounds in the synthesis of the AuNPs-leaf and the AgNPs-leaf was different. Finally, the AgNPs-leaf inhibited the growth of S. aureus, E. coli, S. marcescens and E. faecalis. All of them are bacterial strains of clinical importance due to their fast antibiotic resistance development.

Calcium peroxide significantly enhances volatile solids destruction in aerobic sludge digestion through improving sludge biodegradability

This work put up a novel strategy of applying calcium peroxide (CaO₂) in aerobic sludge digestion and provided insights into such system. The degradation percentage of sludge and total inorganic nitrogen production in the digesters with CaO₂ at 0.02 g/g-VS-WAS increased by 25.8% and 18.8% of control. CaO₂ addition allowed various key microbes related to organics degradation to accumulate in the system. Moreover, the modelling and chemical (i.e., excitation emission matrix (EEM) fluorescence and fourier transformation spectroscopy (FTIR)) analyses revealed that CaO₂ addition enhanced sludge biodegradability with more release of biodegradable organics and increased degradation of recalcitrant organics, which can be transformed into biodegradable organics with the action of CaO₂. Subsequent transformation test indicated that CaO₂ enabled to promote hydrolysis and catabolism of biodegradable substrates in sludge. Further investigations on function mechanism suggested that CaO₂ carried on positive action for sludge aerobic digestion mainly through the enhancement by ·OH.

Seed bulb size influences the effects of exogenous brassinolide on yield and quality of Pinellia ternata

In recent years, natural Pinellia ternata populations of have gradually been exhausted, while the cultivated yield has been limited due to lack of research and uncertain climate condition. Therefore, it is necessary to explore methods of improving yield and quality in P. ternata using brassinolide (BR) treatments and choice of a suitable seed bulb size. This article reports the effects of BR and two seed bulb sizes (diameter: 0.5-1.0 cm and 1.0-1.5 cm) on active and nutrient components and antioxidant activity in P. ternata. The experiment included six levels of BR (0, 0.05, 0.10, 0.50, 1.00 and 2.00 mg l^-1 ). The tuber yield of the two seed bulb sizes and bulbil yield of small seed bulbs increased 5.67%, 22.66% and 69.23% by day 105 after 0.50 mg l^-1 BR treatment, compared with the control. On day 105, only 0.05 mg l^-1 BR increased scores in principal components analysis (PCA) in tubers of small seed bulbs by 167.29%, and 0.05 and 0.50 mg l^-1 BR increased PCA score in bulbils of large seed bulbs by 145.66% and 252.97%, respectively, compared with the control. Significant BR × seed bulb size interactions were found on yield and quality of P. ternata. The results indicate that BR effects on yield and quality of tubers and bulbils of P. ternata are not only related to BR concentration but also to seed bulb size.

ipa1 improves rice drought tolerance at seedling stage mainly through activating abscisic acid pathway

KEY MESSAGE: ipa1 enhances rice drought tolerance mainly through activating the ABA pathway. It endows rice seedlings with a more developed root system, smaller leaf stomata aperture, and enhanced carbon metabolism. Drought is a major abiotic stress to crop production. IPA1 (IDEAL PLANT ARCHITECTURE 1)/OsSPL14 encodes a transcription factor and has been reported to function in both rice ideal plant architecture and biotic resistance. Here, with a pair of IPA1 and ipa1-NILs (Near Iso-genic Lines), we found that ipa1 could significantly improve rice drought tolerance at seedling stage. The ipa1 plants had a better-developed root system and smaller leaf stomatal aperture. Analysis of carbon-nitrogen metabolism-associated enzyme activity, gene expression, and metabolic profile indicated that ipa1 could tip the carbon-nitrogen metabolism balance towards an increased carbon metabolism pattern. In both the control and PEG-treated conditions, ABA content in the ipa1 seedlings was significantly higher than that in the IPA1 seedlings. Expression of the ABA biosynthesis genes was detected to be up-regulated, whereas the expression of ABA catabolism genes was down-regulated in the ipa1 seedlings. In addition, based on yeast one-hybrid assay and dual-luciferase assay, IPA1 was found to directly activate the promoter activity of OsHOX12, a transcription factor promoting ABA biosynthesis, and OsNAC52, a positive regulator of the ABA pathway. The expression of OsHOX12 and OsNAC52 was significantly up-regulated in the ipa1 plants. Combined with the previous studies, our results suggested that ipa1 could improve rice seedling drought tolerance mainly through activating the ABA pathway and that regulation of the ipa1-mediated ABA pathway will be an important strategy for improving drought resistance of rice.

Enhanced γ-aminobutyric acid and sialic acid in fermented deer antler velvet and immune promoting effects

Deer antler velvet is widely used in traditional medicine for its anti-aging, antioxidant, and immunity-enhancing effects. However, few studies have reported on the discovery of probiotic strains for deer antler fermentation to increase functional ingredient absorption. This study evaluated the ability of probiotic lactic acid bacteria to enhance the concentrations of bioactive molecules (e.g., sialic acid and gamma-aminobutyric acid [GABA]) in extracts of deer antler velvet. Seventeen strains of Lactobacillus spp. that were isolated from kimchi and infant feces, including L. sakei, L. rhamnosus, L. brevis, and L. plantarum, and those that improved the life span of Caenorhabditis elegans were selected for evaluation. Of the 17 strains, 2 (L. rhamnosus LFR20-004 and L. sakei LFR20-007) were selected based on data showing that these strains increased both the sialic acid and GABA contents of deer antler extract after fermentation for 2 d and significantly improved the life span of C. elegans. Co-fermentation with both strains further increased the concentrations of sialic acid, GABA, and metabolites such as short-chain fatty acids and amino acids. We evaluated the biological effects of the fermented antler velvet (FAV) on the antibacterial immune response in C. elegans by assessing worm survival after pathogen infection. The survival of the C. elegans conditioned with FAV for 24 h was significantly higher compared with that of the control worm group fed only normal feed (non-pathogenic E. coli OP50) exposed to E. coli O157:H7, Salmonella typhi, and Listeria monocytogenes. To evaluate the protective effects of FAV on immune response, cyclophosphamide (Cy), an immune-suppressing agent was treated to in vitro and in vivo. We found that FAV significantly restored viability of mice splenocytes and immune promoting-related cytokines (interleukin [IL]-6, IL-10, inducible nitric oxide synthase [iNOS], interferon [IFN]-γ, and tumor necrosis factor [TNF]-α) were activated compared to non-fermented deer antlers. This finding indicated the protective effect of FAV against Cy-induced cell death and immunosuppressed mice. Taken together, our study suggests that immune-promoting antler velvet can be produced through fermentation using L. rhamnosus LFR20-004 and L. sakei LFR20-007.

Fabrication of Multiresponsive Magnetic Nanocomposite Double-Network Hydrogels for Controlled Release Applications

Nanocomposite double-network hydrogels (ncDN hydrogels) have been demonstrated as promising biomaterials to present several desired properties (e.g., high mechanical strength, stimuli-responsiveness, and local therapy) for biomedicine. Here, a new type of ncDN hydrogels featuring definable microstructures and properties as well as multistimuli responsiveness for controlled release applications is developed. Amine-functionalized iron oxide nanoparticles (IOPs_NH₂ ) are used as nanoparticle cross-linkers to simultaneously connect the dual networks of gelatin (Gel) and polydextran aldehyde (PDA) through hydrogen bonding, electrostatic interactions, and dynamic imine bonds. The pH- and temperature-responsive Gel/PDA/IOP_NH₂ ncDN hydrogels present a fast release profile of proteins at acidic pH and high temperature. Besides, IOP_NH₂ also contributes the magnetic-responsiveness to the ncDN hydrogels, allowing the use of magnetic field to generate heat to facilitate the structural change of hydrogels and the subsequent applications. Taken together, a versatile ncDN hydrogel platform capable of multistimuli responsiveness and local heating for controlled release is developed for advanced biomedical applications.

Genomic characterization and production of antimicrobial lipopeptides by Bacillus velezensis P45 growing on feather by-products

AIMS

To investigate the potential of novel Bacillus velezensis P45 as an eco-friendly alternative for bioprocessing poultry by-products into valuable antimicrobial products.

METHODS AND RESULTS

The complete genome of B. velezensis P45 was sequenced using the Illumina MiSeq platform, showing 4455 protein and 98 RNA coding sequences according to the annotation on the RAST server. Moreover, the genome contains eight gene clusters for the production of antimicrobial secondary metabolites and 25 putative protease-related genes, which can be related to feather-degrading activity. Then, in vitro tests were performed to determine the production of antimicrobial compounds using feather, feather meal and brain-heart infusion (BHI) cultures. Antimicrobial activity was observed in feather meal and BHI media, reaching 800 and 3200 AU ml^-1 against Listeria monocytogenes respectively. Mass spectrometry analysis indicates the production of antimicrobial lipopeptides surfactin, fengycin and iturin.

CONCLUSIONS

The biotechnological potential of B. velezensis P45 was deciphered through genome analysis and in vitro studies. This strain produced antimicrobial lipopeptides growing on feather meal, a low-cost substrate.

SIGNIFICANCE AND IMPACT OF STUDY

The production of antimicrobial peptides by this keratinolytic strain may represent a sustainable alternative for recycling by-products from poultry industry. Furthermore, whole B. velezensis P45 genome sequence was obtained and deposited.

A γ-PGA/KGM-based injectable hydrogel as immunoactive and antibacterial wound dressing for skin wound repair

Injectable hydrogels, of which the cover area and volume can be flexibly adjusted according to the shape and depth of the wound, are considered to be an ideal material for wound dressing. Konjac glucomannan (KGM) is a natural polysaccharide with immunomodulatory capability, while γ-polyglutamic acid (γ-PGA) is a single chain polyamino acid with moisturizing, water-retention and antibacterial properties. This work intended to combine the advantages of the two materials to prepare an injectable hydrogel (P-OK) by mixing the adipic acid dihydrazide (ADH) modified γ-PGA with oxidized KGM. The chemical structures, the physical and chemical properties, and the biological properties of the P-OK hydrogel were evaluated. The optimal conditions to form the P-OK hydrogel were fixed, and the cytotoxicity, qPCR, antibacterial and animal experiments were performed. Results showed that the P-OK hydrogel had a fast gelation time, good water-retention rate, little cytotoxicity, good immunomodulating and antibacterial capabilities, and could shorten the healing period in the rat full-thickness defect model, which makes it a potential candidate for wound repair dressing.

A Novel Chitosan Nanosponge as a Vehicle for Transepidermal Drug Delivery

Transepidermal drug delivery achieves high drug concentrations at the action site and ensures continuous drug delivery and better patient compliance with fewer adverse effects. However, drug delivery through topical application is still limited in terms of drug penetration. Chitosan is a promising enhancer to overcome this constraint, as it can enhance drug diffusion by opening the tight junctions of the stratum corneum. Therefore, here, we developed a novel chitosan nanosponge (CNS) with an optimal ratio and molecular weight of chitosan to improve drug penetration through skin. To prepare the CNS, two types of chitosan (3 and 10 kDa) were each conjugated with poloxamer 407 using para-nitrophenyl chloroformate, and the products were mixed with poloxamer 407 at ratios of 5:5, 8:2, and 10:0. The resulting mixtures were molded to produce flexible soft nanosponges by simple nanoprecipitation. The CNSs were highly stable in biological buffer for four weeks and showed no toxicity in human dermal fibroblasts. The CNSs increased drug permeability through human cadaver skin in a Franz-type diffusion cell, with substantially higher permeability with 3 kDa chitosan at a ratio of 8:2. This suggests the applicability of the novel CNS as a promising carrier for efficient transepidermal drug delivery.

Structural modification of whey protein isolate by cinnamaldehyde and stabilization effect on β-carotene-loaded emulsions and emulsion gels

The effect of cinnamaldehyde (CA) on the structure and properties of whey protein isolate (WPI) was investigated. The resultant WPI/CA complex was used as stabilizer to form emulsions and emulsion gels, which were used for the delivery and protection of β-carotene. The particle size and hydrophobicity of WPI solution increased and then decreased with the addition of CA. Circular dichroism showed that CA mainly changed the secondary structure of WPI, with increasing β-fold content from 47.2% to 72.9%. The fluorescence spectra showed that both tryptophan and tyrosine in WPI were involved in the interaction with CA. WPI/CA complex as the stabilizer could form the stable emulsions and emulsion gels, which showed better protection effect on β-carotene, and helped enhance its bioaccessibility. The knowledge provides insights into the development of new multifunctional food ingredients and the enhancement of protein modification in food system.

Matcha green tea prevents obesity-induced hypothalamic inflammation via suppressing the JAK2/STAT3 signaling pathway

Obesity is an increasingly severe global health problem, leading to chronic inflammation and metabolic disorders in both peripheral tissues and the central nervous system. Matcha is a powdered green tea, and it is very popular in recent years as a beverage and food additive. Matcha green tea has been reported to have outstanding potential in regulating obesity-related metabolic syndrome. However, there are few studies on the regulation mechanism of matcha green tea on the central nervous system. In this study, we established a high-fat diet-induced obese mouse model. The results showed that dietary supplementation with matcha could effectively inhibit the weight gain, fat accumulation, glycemia and lipidemia increase, and excessive activation of microglia in the arcuate nucleus of the hypothalamus. Furthermore, we used different concentrations (100%, 80%, 60%, 40%, and 20%, v/v) of ethanol solution to prepare matcha ethanol extracts, and investigated their effects on palmitic acid-induced inflammation of microglial BV-2 cells. The results showed that matcha ethanol extracts could significantly reduce the release of inflammatory cytokines and the expression and phosphorylation of JAK2 and STAT3.