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Apple snails from the family Ampullariidae have become economically important due to several species mainly from the genus Pomacea being invasive. The heat shock proteins (HSPs), which are important molecular chaperones for species responding to various stresses, have been proved to play critical roles in adapting harsh environments in the invasive apple snails. The recent release of the genomes of Pomacea canaliculata , Pomacea maculata , Lanistes nyassanus , and Marisa cornuarietis has opened the opportunity for a comprehensive analysis of HSP superfamily in the ampullariids. We identified the number of HSP from P. canaliculata (PcaHSPs) was greater than that from the other three species. A total of 42 PcaHSPs were distributed on 12 chromosomes and were classified into the families of HSP90, HSP70, HSP60, HSP40, HSP20, and HSP10. Each family formed a monophyletic clade on the phylogenetic tree with strong support values, except for the HSP90 and HSP70 families. The RNA-seq data shows that most the PcaHSPs were of tissue-specific expression levels. Moreover, we identified more HSP genes with stronger transcription levels in response to heat than cold stress. Our findings are informative for future studies on stress adaptation and developing effective management strategies focusing on HSPs in invasive apple snails. [ABSTRACT FROM AUTHOR]

Collagen, the most abundant and widely distributed functional protein in mammals, typically assembles into collagen fibrils through side-by-side packing. The purpose of this study was to comparatively investigate the fate of sea cucumber collagen fibrils in the gastrointestinal tract when interacting with different anionic polysaccharides (fucoidan (FUC), Kappa-carrageenan (K-car), sodium alginate (SA)). Results revealed that the gel properties and viscosity values of collagen fibrils were notably enhanced, and the rate of structural alteration in collagen fibrils was reduced when K-car and SA were introduced. Conversely, in the presence of FUC, collagen fibril viscosity decreased, and the secondary structure of collagen fibrils underwent changes. FUC was found to diminish the structural stability of collagen fibrils and accelerate the gastric digestion rate, which was further exacerbated by thermal treatment. All these anionic polysaccharides were observed to facilitate the formation of collagen peptide aggregates by binding to polysaccharides during intestinal digestion. This study bridged the knowledge gap regarding the impact of anionic polysaccharides on the gastrointestinal digestion of collagen fibrils, potentially paving the way for broader applications of collagen in the food industry. • The structure and digestion fate of sea cucumber collagens was investigated. • The presence of anionic polysaccharides inconsistently regulated collagen fibrils. • The presence of fucoidan (FUC) improved gastrointestinal digestion rate of fibrils. • Heat treatment increased the effect of FUC on digestion rate of collagen fibrils. • The presence of Kappa-carrageenan and sodium alginate reduced the digestion rate. [ABSTRACT FROM AUTHOR]

Collagen, the most abundant and widely distributed functional protein in mammals, typically assembles into collagen fibrils through side-by-side packing. The purpose of this study was to comparatively investigate the fate of sea cucumber collagen fibrils in the gastrointestinal tract when interacting with different anionic polysaccharides (fucoidan (FUC), Kappa-carrageenan (K-car), sodium alginate (SA)). Results revealed that the gel properties and viscosity values of collagen fibrils were notably enhanced, and the rate of structural alteration in collagen fibrils was reduced when K-car and SA were introduced. Conversely, in the presence of FUC, collagen fibril viscosity decreased, and the secondary structure of collagen fibrils underwent changes. FUC was found to diminish the structural stability of collagen fibrils and accelerate the gastric digestion rate, which was further exacerbated by thermal treatment. All these anionic polysaccharides were observed to facilitate the formation of collagen peptide aggregates by binding to polysaccharides during intestinal digestion. This study bridged the knowledge gap regarding the impact of anionic polysaccharides on the gastrointestinal digestion of collagen fibrils, potentially paving the way for broader applications of collagen in the food industry. • The structure and digestion fate of sea cucumber collagens was investigated. • The presence of anionic polysaccharides inconsistently regulated collagen fibrils. • The presence of fucoidan (FUC) improved gastrointestinal digestion rate of fibrils. • Heat treatment increased the effect of FUC on digestion rate of collagen fibrils. • The presence of Kappa-carrageenan and sodium alginate reduced the digestion rate. [ABSTRACT FROM AUTHOR]

Studying the noncovalent interactions between proteins and polysaccharides is quite important mainly due to the wide number of applications such as developing pH-responsive complexes. Scallop Patinopecten yessoensis male gonad hydrolysates‑sodium alginate (SMGHs-SA) was investigated as noncovalent complexes at pH from 1 to 10. The critical pH values pH C (around 6) and pHφ (around 4) were independent of the SMGHs-SA ratio, indicating the formation of soluble and insoluble complexes. The pH response of SMGHs-SA complexes was evaluated by investigating the rheological behavior, moisture distribution, functional group change and microstructure. Compared to the co-soluble and soluble complexes phases, the SMGHs-SA complexes had a higher storage modulus and viscosity as well as a lower relaxation time (T 23) in the insoluble complexes phase (pHφ>3). Additionally, the amide I band and COO− stretching vibration peaks were redshifted and the amide A band vibration peaks were blueshifted by acidification. Electrostatic interactions and intermolecular/intramolecular hydrogen bonding led to SMGHs-SA agglomeration at pH 3, forming a uniform and dense gel network structure with strong gel strength and water-retention capacity. This study provides a theoretical and methodological basis for the design of novel pH-responsive complexes by studying SMGHs-SA complex coacervation. • Scallop gonad hydrolysates (SMGHs) and sodium alginate (SA) could coacervate. • Acidification promoted the formation of SMGHs-SA coacervations. • Electrostatic interactions were the main force for the SMGHs-SA complex at pH 3. • Hydrogen bonding also drove the interaction of SMGHs and SA. [ABSTRACT FROM AUTHOR]

Studying the noncovalent interactions between proteins and polysaccharides is quite important mainly due to the wide number of applications such as developing pH-responsive complexes. Scallop Patinopecten yessoensis male gonad hydrolysates‑sodium alginate (SMGHs-SA) was investigated as noncovalent complexes at pH from 1 to 10. The critical pH values pH C (around 6) and pHφ (around 4) were independent of the SMGHs-SA ratio, indicating the formation of soluble and insoluble complexes. The pH response of SMGHs-SA complexes was evaluated by investigating the rheological behavior, moisture distribution, functional group change and microstructure. Compared to the co-soluble and soluble complexes phases, the SMGHs-SA complexes had a higher storage modulus and viscosity as well as a lower relaxation time (T 23) in the insoluble complexes phase (pHφ>3). Additionally, the amide I band and COO− stretching vibration peaks were redshifted and the amide A band vibration peaks were blueshifted by acidification. Electrostatic interactions and intermolecular/intramolecular hydrogen bonding led to SMGHs-SA agglomeration at pH 3, forming a uniform and dense gel network structure with strong gel strength and water-retention capacity. This study provides a theoretical and methodological basis for the design of novel pH-responsive complexes by studying SMGHs-SA complex coacervation. • Scallop gonad hydrolysates (SMGHs) and sodium alginate (SA) could coacervate. • Acidification promoted the formation of SMGHs-SA coacervations. • Electrostatic interactions were the main force for the SMGHs-SA complex at pH 3. • Hydrogen bonding also drove the interaction of SMGHs and SA. [ABSTRACT FROM AUTHOR]

As iron supplement, the antioxidant activities of APS-iron (III) complex were comprehensively evaluated by 5-axe cobweb charts, which indicated the APS-iron (III) complex had a certain antioxidant activity and been weaker than that of APS. The results of immunological activity experiments indicated the stimulation index increased with APS-iron (III) complex concentration increase. When the concentration of the APS-iron (III) complex was 50 μg/mL, the lymphocytes proliferation increased by 35.7% compared with APS. APS-iron (III) complex also had better complement fixing activity than APS, 0.589 mg/mL of which achieved 50% complement fixing activities. Through the iron supplement experiments on iron-deficiency anemia mouse model, we found the APS-iron (III) complex faster increased hemoglobin concentration, SOD, CAT and faster decreased MDA to the normal level than Niferex and ferrous sulfate. Histological results revealed that the tissue sections were clear without obvious pathological changes and bone marrow had most hematopoietic cells from APS-iron (III) complex rat group, which also proved the APS-iron (III) complex had no significant side effects. Therefore, APS-iron (III) complex may be developed as a multifunctional iron supplement for clinical application. In this study, the APS-iron (III) complex was further characterized. Due to iron (III) introduction, the XRD diffraction peaks of APS-iron (III) complex had a remarkable change. APS-iron (III) complex had better immune protection response and higher complement fixing activity than APS. The results indicated the stimulation index increased with APS-iron (III) complex concentration increase. When the concentration of the APS-iron (III) complex was 50 μg/mL, the lymphocytes proliferation increased by 35.7% compared with APS. APS-iron (III) complex also had better complement fixing activity than APS, 0.589 mg/mL of which achieved 50% complement fixing activities. Through the iron supplement experiments on iron-deficiency anemia mouse model, we found the APS-iron (III) complex had faster iron-supplying effect, faster SOD and CAT increase and faster MDA decrease to the normal level than Niferex and ferrous sulfate. Histological analysis indicated the tissue sections of liver, bone and spleen from APS-iron (III) complex group, were clear without obvious pathological changes, which also proved the APS-iron (III) complex had no significant side effects. Therefore, APS-iron (III) complex may be developed as a multifunctional iron supplement for clinical application. Unlabelled Image • As iron supplement APS-iron (III) was further comprehensively evaluated. • Through the mouse model, APS-iron (III) complex had a faster iron supplement effect. • Histological studies showed that the tissue textures of APS-iron (III) complex treated groups were clear and bone marrow had most hematopoietic cells. [ABSTRACT FROM AUTHOR]

Gel properties of hydrogel-forming by Ala-Lys dipeptide (AK) and iota-carrageenan (ι-C) were investigated by rheological behavior, fourier transform infrared analysis, cryo-scanning electron microscopy, low field-NMR relaxometry and magnetic resonance imaging. Iota-carrageenan was changed from a liquid to a gel with the addition of AK, and the existence of AK significantly increased the storage modulus (G') of ι-C from 590.4 to 1077.8 Pa. In the ι-C/AK gel, the blue-shift of O H stretching and water deformation were observed, meanwhile, the presence of amide I band at 1682 cm−1 was observed. The network of ι-C/AK gel showed a dense honeycomb structure with flocculating continuous phase and rough entanglement morphology. After adding AK, the water free in the pores of ι-C entered the ι-C/AK gel matrix, and the binding capacity of bound water was enhanced. These scenarios proved that the AK as the cationic dipeptide could control the conversion of negatively charged ι-C from an original random structure to a helical structure due to electrostatic interactions and hydrogen bonds. This study provides a new opportunity for the peptides into carbohydrate-based gel matrices, which could provide insights for the further application of ι-C/AK gels in the fields of food industry, tissue engineering and drug delivery. • AK dipeptide enhanced the gel properties of iota-carrageenan. • Electrostatic interactions was the main force in AK/ ι-C gel. • The hydrogen bond stabilized the AK/ι-C gel structure. • AK induced regular and homogenous network structure in the ι-C gel. [ABSTRACT FROM AUTHOR]

Calcium β-hydroxy-β-methylbutyrate (CaHMB), a functional calcium salt, is used to maintain and improve muscle health. Here, a new hydrogel material prepared from alginate (ALG) with three M/G ratios (1:1, 2:1, and 1:2) and CaHMB (0–2 mg/mL) was investigated. CaHMB regulates the formation and properties of ALG hydrogels through chelation and hydrogen bonding. When the M/G ratio was 2:1, the anionic groups of CaHMB containing carboxyl and hydroxyl groups formed hydrogen bonds with the polysaccharide chains, hindering the capture of Ca2+ by the G-residue fragments of ALG, which in turn retarded the gelation process. The noncalcium cross-linked polysaccharide chain structure of ALG and the anionic group of CaHMB also affected the water distribution in the hydrogel, especially when M residue content ≥G residue content. Lower M/G ratios and higher CaHMB concentrations could increase the number of "egg box" crosslinking junctions of calcium alginate, and the microstructure was denser in the gel pores, resulting in a stronger gel strength and more free water bound in the gel matrix. This study provides a theoretical and methodological basis for the design of novel hydrogels by studying the crosslinking features of ALG/CaHMB. • Alginate and calcium β-hydroxy-β-methylbutyrate (ALG/CaHMB) successfully form gels. • Hydrogen bonds between anionic groups of CaHMB and ALG delay the gel formation. • More guluronate residues enhance the crosslinking density forming denser networks. • Higher CaHMB concentrations promote the formation of more "egg box" structures. [ABSTRACT FROM AUTHOR]

Circular RNA (circRNA) has been implicated in liver fibrosis and modulated by multiple elusive molecular mechanisms, while the effects of N6-methyladenosine (m6A) modification on circRNA are still elusive. Herein, we identify circIRF2 from our circRNA sequencing data, which decreased in liver fibrogenesis stage and restored in resolution stage, indicating that dysregulated circIRF2 may be closely associated with liver fibrosis. Gain/loss-of-function analysis was performed to evaluate the effects of circIRF2 on liver fibrosis at both the fibrogenesis and resolution in vivo. Ectopic expression of circIRF2 attenuated liver fibrogenesis and HSCs activation at the fibrogenesis stage, whereas downregulation of circIRF2 impaired mouse liver injury repair and inflammation resolution. Mechanistically, YTHDF2 recognized m6A-modified circIRF2 and diminished circIRF2 stability, partly accounting for the decreased circIRF2 in liver fibrosis. Microarray was applied to investigate miRNAs regulated by circIRF2, our data elucidate cytoplasmic circIRF2 may directly harbor miR-29b-1-5p and competitively relieve its inhibitory effect on FOXO3, inducing FOXO3 nuclear translocation and accumulation. Clinically, circIRF2 downregulation was prevalent in liver fibrosis patients compared with healthy individuals. In summary, our findings offer a novel insight into m6A modification-mediated regulation of circRNA and suggest that circIRF2 may be an exploitable prognostic marker and/or therapeutic target for liver fibrosis. [Display omitted] • Dysregulated circIRF2 closely associated with liver fibrosis both fibrogenesis and resolution stages • YTHDF2 identified m6A-modified circIRF2 and diminished circIRF2 stability. • circIRF2 sponges miR-29b-1-5p and promotes FOXO3 nuclear translocation. [ABSTRACT FROM AUTHOR]