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SLC15A4/PHT1 is an endolysosome-resident carrier of oligopeptides and histidine recently come into view as a key path marker of immune/autoimmune/inflammatory pathways in immune cells. Yet, its emerging role in inflammatory processes directly targeting the gastrointestinal epithelial layer, as in the multifactorial pathophysiology of inflammatory bowel disease (IBD), is poorly investigated. Here, the first identification of SLC15A4/PHT1 gene products in human colonic epithelium of ulcerative colitis (UC) patients is reported, showing protein primarily localized in intracellular vesicle-like compartments. Qualitative and quantitative immunohistochemical analyses of colon biopsies revealed overexpression of SLC15A4/PHT1 protein product in the epithelial layer of UC patients. Results were successfully mirrored in vitro, in spontaneously differentiated enterocyte-like monolayers of Caco-2 cells specifically exposed to DSS (dextran sodium sulphate) to mimic IBD inflammatory onsets. SLC15A4/PHT1 expression and cellular localization were characterized confirming its (dys)regulation traits in inflamed vs. healthy epithelia, strongly hinting the hypothesis of SLC15A4/PHT1 increased function associated with epithelial inflammation in IBD patients.

SLC15A4/PHT1 is an endolysosome-resident carrier of oligopeptides and histidine recently come into view as a key path marker of immune/autoimmune/inflammatory pathways in immune cells. Yet, its emerging role in inflammatory processes directly targeting the gastrointestinal epithelial layer, as in the multifactorial pathophysiology of inflammatory bowel disease (IBD), is poorly investigated. Here, the first identification of

Type I collagen is the most abundant protein of the human body. Due to its favourable properties, collagen extracted from animal tissues is adopted to manufacture a wide range of devices for biomedical applications. Compared to bovine and porcine collagens, which are the most largely used, equine collagen is free from the risk of zoonosis, has no reported immune reactions, and has not religious constraints. In this work, a recently available type I collagen extracted from horse tendon was evaluated and compared with a commercially available collagen isoform derived from the same species and tissue. Detailed physical, chemical and biological investigations were performed, in agreement with the requirements of the current standard for the characterization of type I collagen to be used for the manufacture of Tissue Engineering Medical Products. To the best of our knowledge, this is the first report on the complete primary structure of the investigated collagen.

Abstract Winnie, a mouse carrying a missense mutation in the MUC2 mucin gene, is a valuable model for inflammatory bowel disease (IBD) with signs and symptoms that have multiple similarities with those observed in patients with ulcerative colitis. MUC2 mucin is present in Winnie, but is not firmly compacted in a tight inner layer. Indeed, these mice develop chronic intestinal inflammation due to the primary epithelial defect with signs of mucosal damage, including thickening of muscle and mucosal layers, goblet cell loss, increased intestinal permeability, enhanced susceptibility to luminal inflammation-inducing toxins, and alteration of innervation in the distal colon. In this study, we show that the intestinal environment of the Winnie mouse, genetically determined by MUC2 mutation, selects an intestinal microbial community characterized by specific pro-inflammatory, genotoxic, and metabolic features that could imply a direct involvement in the pathogenesis of chronic intestinal inflammation. We report results obtained by using a variety of in vitro approaches for fecal microbiota functional characterization. These approaches include Caco-2 cell cultures and Caco-2/THP-1 cell co-culture models for evaluation of geno-cytotoxic and pro-inflammatory properties using a panel of 43 marker RNAs assayed by RT-qPCR, and cell-based phenotypic testing for metabolic profiling of the intestinal microbial communities by Biolog EcoPlates. While adding a further step towards understanding the etiopathogenetic mechanisms underlying IBD, the results of this study provide a reliable method for phenotyping gut microbial communities, which can complement their structural characterization by providing novel functional information.

Inflammatory bowel disease (IBD) implies the chronic inflammation of the gastrointestinal tract, combined with systemic vascular manifestations. In IBD, the incidence of cardiovascular disease appears to be related to an increase of oxidative stress and endothelial dysfunction. Grape pomace contains high levels of anti-oxidant polyphenols that are able to counteract chronic inflammatory symptoms. The aim of this study was to determine whether grape pomace polyphenolic extract (GPE) was able to mitigate the overwhelming inflammatory response in enterocyte-like cells and to improve vascular function. Intestinal epithelial Caco-2 cells, grown in monolayers or in co-culture with endothelial cells (Caco-2/HMEC-1), were treated with different concentrations of GPE (1, 5, 10 µg/mL gallic acid equivalents) for 2 h and then stimulated with lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-α for 16 h. Through multiple assays, the expression of intestinal and endothelial inflammatory mediators, intracellular reactive oxygen species (ROS) levels and NF-κB activation, as well as endothelial-leukocyte adhesion, were evaluated. The results showed that GPE supplementation prevented, in a concentration-dependent manner, the intestinal expression and release of interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, and matrix metalloproteinases (MMP)-9 and MMP-2. In Caco-2 cells, GPE also suppressed the gene expression of several pro-inflammatory markers, such as IL-1β, TNF-α, macrophage colony-stimulating factor (M-CSF), C-X-C motif ligand (CXCL)-10, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, and cyclooxygenase (COX)-2. The GPE anti-inflammatory effect was mediated by the inhibition of NF-κB activity and reduced intracellular ROS levels. Furthermore, transepithelial GPE suppressed the endothelial expression of IL-6, MCP-1, VCAM-1, and ICAM-1 and the subsequent adhesion of leukocytes to the endothelial cells under pro-inflammatory conditions. In conclusion, our findings suggest grape pomace as a natural source of polyphenols with multiple health-promoting properties that could contribute to the mitigation of gut chronic inflammatory diseases and improve vascular endothelial function.

The high-affinity/low-capacity system Slc15a2 (PepT2) is responsible for the reuptake of di/tripeptides from the renal proximal tubule, but it also operates in many other tissues/organs. Information regarding PepT2 in teleost fish is limited and to date functional data are available from the zebrafish (Danio rerio) only. Here, we report the identification of two slc15a2 genes in the Atlantic salmon (Salmo salar) genome, namely slc15a2a and slc15a2b. The two encoded PepT2 proteins share 87% identity and resemble both structurally and functionally to the canonical vertebrate PepT2 system. The mRNA tissue distribution analyses reveal a widespread distribution of slc15a2a transcripts, being more abundant in the brain and gills, while slc15a2b transcripts are mainly expressed in kidney and distal part of gastrointestinal tract. The function of the two transporters was investigated by heterologous expression in Xenopus laevis oocytes and two- electrode voltage-clamp recordings of transport and presteady-state currents. Both PepT2a and PepT2b in the presence of Gly-Gln elicit pH-dependent and Na+ independent inward currents. The biophysical and kinetic analysis of the recorded currents defined the transport properties, confirming that the two Atlantic salmon PepT2 proteins behave as high-affinity/low-capacity transporters. The recent structures and the previous kinetic schemes of rat and human PepT2 qualitatively account for the characteristics of the two Atlantic salmon proteins. This study is the first to report on the functional expression of two PepT2-type transporters that operate in the same vertebrate organism as a result of (a) gene duplication process(es).Key points summaryTwo slc15a2-type genes, slc15a2a and slc15a2b coding for PepT2-type peptide transporters were found in the Atlantic salmon.slc15a2a transcripts, widely distributed in the fish tissues, are abundant in brain and gills, while slc15a2b transcripts are mainly expressed in kidney and distal gastrointestinal tract.Amino acids involved in vertebrate Slc15 transport function are conserved in PepT2a and PepT2b proteins.Detailed kinetic analysis indicates that both PepT2a and PepT2b operate as high-affinity transporters.The kinetic schemes and structures proposed for the mammalian models of PepT2 are suitable to explain the function of the two Atlantic salmon transporters.

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions of the gastrointestinal tract, also associated with systemic vascular manifestations. In IBD, the incidence of cardiovascular disease appears related to an increase of oxidative stress and endothelial dysfunction. Grape pomace contains high levels of anti-oxidant polyphenols, which are able to counteract chronic inflammatory disease. The aim of this study was to determine whether grape pomace polyphenolic extract (GPE) was able to mitigate the overwhelming inflammatory response in enterocyte-like cells and to improve vascular function. The intestinal epithelial Caco-2 cells, grown in monolayers or in co-culture with endothelial cells (Caco-2/HMEC-1), were treated with different concentra-tions of GPE (1, 5, 10 µg GAEs/mL) for 2h and then stimulated with lipopolysaccharide(LPS) and tumor necrosis factor(TNF)-? for 16h. Through multiple assays, the expression of intestinal and endothelial inflammatory mediators, intracellular ROS levels, NF-?B activity as well as the en-dothelial-leukocyte adhesion were analyzed. The results showed that GPE supplementation prevented, in a concentration-dependent manner, the expression and release of interleukin(IL)-6, monocyte chemoattractant protein(MCP)-1 and matrix metalloproteinases(MMP)-9 and MMP-2 in Caco-2 cells. GPE also suppressed the intestinal gene expression of several pro-inflammatory mediators, such as IL-1?, TNF-?, macrophage colony-stimulating factor(M-CSF), C-X-C motif ligand(CXCL)-10, intercellular adhesion molecule(ICAM)-1, vascular cell adhesion mole-cule(VCAM)-1 and cyclooxygenase(COX)-2. The GPE anti-inflammatory effect was related to the inhibition of NF-?B activity and intracellular ROS levels. Furthermore, transepithelial GPE in-hibited the endothelial expression of IL-6, MCP-1, VCAM-1 and ICAM-1 and the subsequent ad-hesion of leukocyte to the endothelial cells under pro-inflammatory conditions. In conclusion, our findings suggest grape pomace as a natural source of polyphenols, with multiple healthy pro-moting properties, which could contribute to mitigate gut chronic inflammatory diseases and improve vascular endothelial function.

Nucleos(t)ide analogues (NA) belong to a family of compounds widely used in anticancer/antiviral treatments. They generally exhibit a cell toxicity limited by cellular uptake levels and the resulting nucleos(t)ides metabolism modifications, interfering with the cell machinery for nucleic acids synthesis. We previously synthesized purine nucleos(t)ide analogues N7-coordinated to a platinum centre with unaltered sugar moieties of the type: [Pt(dien)(N7-dGuo)]2+ (1; dien = diethylenetriamine; dGuo = 2'-deoxy-guanosine), [Pt(dien)(N7-dGMP)] (2; dGMP = 5'-(2'-deoxy)-guanosine monophosphate), and [Pt(dien)(N7-dGTP)]2- (3; dGTP = 5'-(2'-deoxy)-guanosine triphosphate), where the indicated electric charge is calculated at physiological pH (7.4). In this work, we specifically investigated the uptake of these complexes (1-3) at the plasma membrane level. Specific experiments on HeLa cervical cancer cells indicated a relevant cellular uptake of the model platinated deoxynucleos(t)ide 1 and 3 while complex 2 appeared unable to cross the cell plasma membrane. Obtained data buttress an uptake mechanism involving Na+-dependent concentrative transporters localized at the plasma membrane level. Consistently, 1 and 3 showed higher cytotoxicity with respect to complex 2 also suggesting selective possible applications as antiviral/antitumor drugs among the used model compounds.

The reduced availability of dissolved oxygen is a common stressor in aquatic habitats that affects the ability of the heart to ensure tissue oxygen supply. Among key signalling molecules activated during cardiac hypoxic stress, nitric oxide (NO) has emerged as a central player involved in the related adaptive responses. Here, we outline the role of the nitrergic control in modulating tolerance and adaptation of teleost heart to hypoxia, as well as major molecular players that participate in the complex NO network. The purpose is to provide a framework in which to depict how the heart deals with limitations in oxygen supply. In this perspective, defining the relational interplay between the multiple (sets of) proteins that, due to the gene duplication events that occurred during the teleost fish evolutive radiation, do operate in parallel with similar functions in the (different) heart (districts) and other body districts under low levels of oxygen supply, represents a next goal of the comparative research in teleost fish cardiac physiology.

To the SLC6 family belong 20 human transporters that utilize the sodium electrochemical gradient to move biogenic amines, osmolytes, amino acids and related compounds into cells. They are classified into two functional groups, the Neurotransmitter transporters (NTT) and Nutrient amino acid transporters (NAT). Here we summarize how since their first cloning in 1998, the insect (Lepidopteran) Orthologs of the SLC6 family transporters have represented very important tools for investigating functional–structural relationships, mechanism of transport, ion and pH dependence and substate interaction of the mammalian (and human) counterparts. Supplementary Information The online version contains supplementary material available at 10.1007/s11064-021-03410-1.

Coccoid cyanobacteria produce a great variety of secondary metabolites, which may have useful properties, such as antibacterial, antiviral, anticoagulant or anticancer activities. These cyanobacterial metabolites have high ecological significance, and they could be considered responsible for the widespread occurrence of these microorganisms. Considering the great benefit derived from the identification of competent cyanobacteria for the extraction of bioactive compounds, two strains of picocyanobacteria (coccoid cyanobacteria &lt, 3 µm) (Cyanobium sp. ITAC108 and Synechococcus sp. ITAC107) isolated from the Mediterranean sponge Petrosia ficiformis were analyzed. The biological effects of organic and aqueous extracts from these picocyanobacteria toward the nauplii of Artemia&nbsp, salina, sea urchin embryos and human cancer lines (HeLa cells) were evaluated. Methanolic and aqueous extracts from the two strains strongly inhibited larval development, on the contrary, in ethyl acetate and hexane extracts, the percentage of anomalous embryos was low. Moreover, all the extracts of the two strains inhibited HeLa cell proliferation, but methanol extracts exerted the highest activity. Gas chromatography–mass spectrometry analysis evidenced for the first time the presence of β-N-methylamino-l-alanine and microcystin in these picocyanobacteria. The strong cytotoxic activity observed for aqueous and methanolic extracts of these two cyanobacteria laid the foundation for the production of bioactive compounds of pharmacological interest.

An immunoencapsulation strategy for pancreatic islets aimed to reduce the risk of rejection in transplanted patients due to the immune response of the host organism is proposed. In this sense, a polyethylene glycol (PEG) hydrogel functionalized with an immunosuppressive antibody (Ab), such as Cytotoxic T-lymphocyte antigen-4 Ig (CTLA4-Ig), would act as both passive and active barrier to the host immune response. To demonstrate the feasibility of this approach, a photopolymerizable-PEG was conjugated to the selected antibody and the PEG-Ab complex was used to coat the islets. Moreover, to preserve the antigen-recognition site of the antibody during the conjugation process, a controlled immobilization method was setup through the attachment of the His-tagged antigen to a solid support. In detail, a gold-coated silicon wafer functionalized with 11-Mercaptoundecanoic acid was used as a substrate for further modification, leading to a nickel(II)-terminated ligand surface. Then, the immobilized antigen was recognized by the corresponding antibody that was conjugated to the PEG. The antibody-PEG complex was detached from the support prior to be photopolymerized around the islets. First, this immobilization method has been demonstrated for the green fluorescent protein (GFP)&ndash, anti-green fluorescent protein (Anti-GFP) antigen-antibody pair, as proof of principle. Then, the approach was extended to the immunorelevant B7-1 CTLA-4-Ig antigen-antibody pair, followed by the binding of Acryl-PEG to the immobilized constant region of the antibody. In both cases, after using an elution protocol, only a partial recovery of the antibody-PEG complex was obtained. Nevertheless, the viability and the functional activity of the encapsulated islets, as determined by the glucose-stimulated insulin secretion (GSIS) assay, showed the good compatibility of this approach.

This paper presents a conceptual framework that looks at photovoltaic systems in synergy with ecosystem services. The focus is to connect business success with social and ecological progress based on the operative concept of multifunctional land use. Such an approach attempts to harmonise the needs of the industrial processes of photovoltaic systems and the ecological and social needs of the landscape context. Different from the usual design of ground photovoltaic systems in farmlands or brownfields, a new framework is proposed, combining photovoltaic panels and vegetation. A case study is considered, applying the framework to existing photovoltaic systems in the Apulia region (southern Italy). The analysis shows how the framework has, among others, the major functions of increasing solar energy production, recycling wastewater, creating raw material for biofuel, as well as providing animal habitat and mitigating air temperature. The latter is preliminarily evaluated by means of modelling simulations performed with a computational fluid dynamics and microclimate model, ENVI-met. This approach opens up a new vision of the infrastructure design of photovoltaic systems which can produce new social and economic income.

Peptide transporter 1 (PepT1,Here, we describe a novel di/tripeptide transporter in the zebrafish (We show that the zebrafish PepT1a-type transporter is functional and co-expressed with

Peptide transporter 1 (PepT1) mediates the uptake of dietary di-/tripeptides in vertebrates. However, in teleost fish gut, more than one PepT1-type transporter might operate, because of teleost-specific whole gen(om)e duplication event(s) that occurred during evolution. Here, we describe a novel teleost di-/tripeptide transporter, i.e., the Atlantic salmon ( Salmo salar) peptide transporter 1a [PepT1a; or solute carrier family 15 member 1a (Slc15a1a)], which is a paralog (77% similarity and 64% identity at the amino acid level) of the well-described Atlantic salmon peptide transporter 1b [PepT1b, alias PepT1; or solute carrier family 15 member 1b (Slc15a1b)]. Comparative analysis and evolutionary relationships of gene/protein sequences were conducted after ad hoc database mining. Tissue mRNA expression analysis was performed by quantitative real-time PCR, whereas transport function analysis was accomplished by heterologous expression in Xenopus laevis oocytes and two-electrode voltage-clamp measurements. Atlantic salmon pept1a is highly expressed in the proximal intestine (pyloric ceca ≈ anterior midgut > midgut >> posterior midgut), in the same gut regions as pept1b but notably ~5-fold less abundant. Like PepT1b, Atlantic salmon PepT1a is a low‐affinity/high‐capacity system. Functional analysis showed electrogenic, Na+-independent/pH-dependent transport and apparent substrate affinity ( K0.5) values for Gly-Gln of 1.593 mmol/L at pH 7.6 and 0.076 mmol/L at pH 6.5. In summary, we show that a piscine PepT1a-type transporter is functional. Defining the role of Atlantic salmon PepT1a in the gut will help to understand the evolutionary and functional relationships among peptide transporters. Its functional characterization will contribute to elucidate the relevance of peptide transporters in Atlantic salmon nutritional physiology.

Simple Summary Current research on nanocomposite materials with tailored physical–chemical properties is increasingly advancing in biomedical applications for bone regeneration. In this study, occurrence of differential responsiveness to dextran-grafted iron oxide (DM) nanoparticles and to their hybrid nano-hydroxyapatite (DM/n-HA) counterpart was investigated in human-derived, osteoblast-like cells. Sensitivity of cells in the presence of DMs or DM/n-HAs was evaluated in terms of cytoskeletal dynamics. Remarkably, it was shown that effects triggered by the DM are no more retained when DM is embedded onto DM/n-HA nanocomposites. In parallel, analyses on the expression of genes involved in (a) intracellular signaling pathways triggered by ligands or cell interactions with elements of the extracellular matrix, (b) modulation of processes such as cell cycle arrest, apoptosis, senescence, DNA repair, metabolism changes, and (c) iron homeostasis and absorption through cell membranes, indicated that the DM/n-HA-treated cells retain tracts of physiological responsiveness unlike DM-treated cells. Overall, a shielding effect by the n-HA was assumed (masking the DM’s cytotoxicity), and a modular biomimicry of the DM/n-HA nanocomposites. On these bases, the biocompatibility of n-HA associated to DM’s magnetic responsiveness offer a combination of structural/functional features of these nano-tools for bone tissue engineering, for finely acting within physiological ranges. Abstract The development of nanocomposites with tailored physical–chemical properties, such as nanoparticles containing magnetic iron oxides for manipulating cellular events at distance, implies exciting prospects in biomedical applications for bone tissue regeneration. In this context, this study aims to emphasize the occurrence of differential responsiveness in osteoblast-like cells to different nanocomposites with diverse features: dextran-grafted iron oxide (DM) nanoparticles and their hybrid nano-hydroxyapatite (DM/n-HA) counterpart. Here, responsiveness of cells in the presence of DMs or DM/n-HAs was evaluated in terms of cytoskeletal features. We observed that effects triggered by the DM are no more retained when DM is embedded onto the DM/n-HA nanocomposites. Also, analysis of mRNA level variations of the focal adhesion kinase (FAK), P53 and SLC11A2/DMT1 human genes showed that the DM/n-HA-treated cells retain tracts of physiological responsiveness compared to the DM-treated cells. Overall, a shielding effect by the n-HA component can be assumed, masking the DM’s cytotoxic potential, also hinting a modular biomimicry of the nanocomposites respect to the physiological responses of osteoblast-like cells. In this view, the biocompatibility of n-HA together with the magnetic responsiveness of DMs represent an optimized combination of structural with functional features of the DM/n-HA nano-tools for bone tissue engineering, for finely acting within physiological ranges.

In this work, zebrafish (Danio rerio) embryos were subjected to different physical stresses, consisting of a static and two low frequency magnetic fields, and two radio frequencies. Specifically, embryos were exposed to static (Bo, 0 Hz), very low frequency (VLF, 0.2 Hz), low frequency (LF, 270 kHz), very high frequency (VHF, 100 MHz) and ultra-high frequency (UHF, 900 MHz) magnetic field irradiations for up to 5 days. The field intensities were 40 mT, 40 mT, 470 μT, 240 nT and 240 nT, respectively. Untreated embryos were used as control (n = 10 for each condition).

Peripheral nerve injuries may lead to a significant function loss, which deeply affect patient’s quality of life. In this context, tissue engineered collagen-based nerve guides are a promising alternative to autografts. To enhance the regeneration of the injured nerve tract, several bioactive molecules can be adopted as further components of the collagen-based conduits. Herein, sericin (Ser), a waste product of textile industry, was combined with type I collagen (Col), for the development of a bioactive substrate potentially able to support and enhance the regeneration of the peripheral nervous system. In particular, in order to identify an optimal substrate composition in terms of physicochemical and biological properties, thin Ser-Col films with different Ser:Col ratios were produced by air-drying and subsequently crosslinked through two different crosslinking methods. Then, Ser:Col films were characterized from a physicochemical point of view by examining secondary protein structure modifications via FTIR spectroscopy, swelling ratios, degradation rates and Ser release kinetics. Moreover, Ser:Col films ability to promote adhesion and proliferation of Schwann cells was evaluated in vitro. The results obtained in this study, although preliminary, suggest that Ser:Col blends could represent a promising strategy to enhance the repair of damaged peripheral nerves, by providing a sustained release of Ser from collagen-based nerve substrates.

The feasibility to obtain highly porous collagen-based scaffolds (SCs) integrated with uniformly dispersed poly (lactide-co-glycolide)(PLGA) microparticles (MPs) was evaluated. PLGA-MPs were prepared by double emulsion technique and SCs with different amounts of MPs (SC/PLGA-MPs) were produced. Results showed that SC/PLGA-MPs could be successfully manufactured, the PLGA-MPs being physically retained in the SCs, without affecting the porous structure. PLGA-MPs also increased the SC hydrophilicity, acted as a mechanical reinforcement and retarded the degradation rate. In addition, the interactions between MPs and Caco-2 cells did not interfere with the correct morphological, adhesion and proliferation pathways.

Two different approaches are proposed in this study to enhance the bioactivity of hydroxyapatite-based scaffolds for bone tissue regeneration. The first method consists in a structural modification of Hydroxyapatite (HA) through doping it with Magnesium (1,3% wt) while the second one in using HA in combination with a calcium silicate, i.e. Wollastonite (WS), to form a composite bioceramic. Scaffolds with high and strongly interconnected porosity (pores ranging from 300 to 800 µm) were produced throughout both procedures. Higher mechanical properties in compression were obtained when the composite Ws/HA bioceramic was adopted. That one showed a weight loss after 6 months in physiological solution seven times higher than doped HA. Preliminary in vitro tests highlighted that both kinds of scaffold allowed the adhesion of MG63, without significant differences in terms of vitality, indicating a good biocompatibility of both used biomaterials.

Background Peptide transporter 1 (PepT1, alias Slc15a1) mediates the uptake of dietary di/tripeptides in all vertebrates. However, in teleost fish, more than one PepT1-type transporter might function, due to specific whole genome duplication event(s) that occurred during their evolution leading to a more complex paralogue gene repertoire than in higher vertebrates (tetrapods). Results Here, we describe a novel di/tripeptide transporter in the zebrafish (Danio rerio), i.e., the zebrafish peptide transporter 1a (PepT1a; also known as Solute carrier family 15 member a1, Slc15a1a), which is a paralogue (78% similarity, 62% identity at the amino acid level) of the previously described zebrafish peptide transporter 1b (PepT1b, alias PepT1; also known as Solute carrier family 15 member 1b, Slc15a1b). Also, we report a basic analysis of the pept1a (slc15a1a) mRNA expression levels in zebrafish adult tissues/organs and embryonic/early larval developmental stages. As assessed by expression in Xenopus laevis oocytes and two-electrode voltage clamp measurements, zebrafish PepT1a, as PepT1b, is electrogenic, Na+-independent, and pH-dependent and functions as a low-affinity system, with K0.5 values for Gly-Gln at − 60 mV of 6.92 mmol/L at pH 7.6 and 0.24 mmol/L at pH 6.5 and at − 120 mV of 3.61 mmol/L at pH 7.6 and 0.45 mmol/L at pH 6.5. Zebrafish pept1a mRNA is highly expressed in the intestine and ovary of the adult fish, while its expression in early development undergoes a complex trend over time, with pept1a mRNA being detected 1 and 2 days post-fertilization (dpf), possibly due to its occurrence in the RNA maternal pool, decreasing at 3 dpf (~ 0.5-fold) and increasing above the 1–2 dpf levels at 4 to 7 dpf, with a peak (~ 7-fold) at 6 dpf. Conclusions We show that the zebrafish PepT1a-type transporter is functional and co-expressed with pept1b (slc15a1b) in the adult fish intestine. Its expression is also confirmed during the early phases of development when the yolk syncytial layer is present and yolk protein resorption processes are active. While completing the missing information on PepT1-type transporters function in the zebrafish, these results open to future investigations on the similar/differential role(s) of PepT1a/PepT1b in zebrafish and teleost fish physiology.

The development of biomimetic scaffolds is a challenging aim in the field of bone repair for fabrication of osteoconductive and osteoinductive scaffolds. Biogenic hydroxyapatite (HA) is not stoichiometric but is substituted by several ions. An approach to improve synthetic scaffolds biomimetism can be the doping with osteoinductive ions. To this aim, herein thermally stable magnesium-strontium hydroxyapatite (HAMgSr) nanocrystals were synthesized and used for the fabrication of sintered highly porous scaffolds. The chemical and physical properties of the obtained scaffolds were analyzed by X-ray diffraction, scanning electron microscopy, mechanical testing. Three different substituting ions percentage were analyzed and among these, the copresence of Mg and Sr at 0.5 wt% has shown the best results in terms of thermal stability and mechanical properties. The potential utilization of these materials for bone regeneration purposes was preliminarily evaluated in vitro, by assaying proliferation of viable osteoblast-like cells; the experimental evidences suggest that the scaffolds can be exploited as bone-mimicking substrates suitable to support cell growth and proliferation. These observations underline the importance of the presence of Mg and Sr in scaffolds for bone remodeling as well as the good potential of the newly developed scaffolds for clinical use in tissue engineering.

Amino acids and small peptides in the form of di/tripeptides are key nutrients in animal diets and essential contributors to growth. In mammals, di/tripeptides represent a highly significant fraction of dietary protein after digestion and are transported across the brush‐border membrane of the intestinal epithelium via a single transport protein, the Peptide Transporter 1 (PepT1), a member of the Solute Carrier 15 (Slc15) family. PepT1 is a low‐affinity/high‐capacity transporter that uses an inwardly‐directed proton electrochemical gradient to drive the uptake of di/tripeptides, and peptidomimetics, across the cell membrane. However, in teleost fishes two pept1 genes, namely pept1b and pept1a, have been identified. PepT1b has been studied in many teleost species, including the Atlantic (A.) salmon (Salmo salar L.), whereas PepT1a remain unexplored. The aim of our study was to characterize, the A. salmon PepT1a vs. PepT1b in terms of tissue/organ distribution and function, and possibly extrapolate their physiological role(s). Despite the extra (4th) whole genome duplication (WGD) in the Actinopterygian lineage, A. salmon has only two pept1 genes (namely pept1a and pept1b), like in other telosts that didn't undergo the extra WGD, e.g., the zebrafish (Danio rerio). At the amino acid level, the two paralogues share 77% similarity, 64% identity. Tissue distribution and relative abundance of A. salmon pept1a and pept1b revealed that both transcripts have a similar expression profile. A. salmon pept1a is highly expressed in the proximal intestine (pyloric caeca ≈ anterior midgut > midgut >> posterior midgut), but ~5‐fold less than pept1b, which is expressed in the same gut regions. No expression signals were detected in the anterior and posterior stomach or the anterior and posterior hindgut. As assessed by heterologous expression in Xenopus laevis oocytes and Two‐Electrode Voltage Clamp measurements, A. salmon PepT1a is, like PepT1b, a low‐affinity/high‐capacity system, able to sustain an electrogenic, sodium‐independent and pH‐dependent transport of di/tripeptides. Transport associated currents show that the protein exhibits a K0.5 value for the reference dipeptide Gly‐Gln of 0.5 mM at pH 7.6 and of 0.07 mM at pH 6.5. The pre‐steady state and steady‐state transport currents analysis indicate important functional differences between A. salmon PepT1a and PepT1b transporters. The difference in expression levels and a significantly dissimilar substrate specificity for certain di/tripeptides, such as lysine‐containing peptides, supports the idea of distinct roles in peptide recognition and transport for PepT1a and PepT1b. Support or Funding Information Funded by RFFV; 247978 SalmoFeedPlus and Cargill

Over the past years, fundamentals of magnetism opened a wide research area of interest, in the field of tissue engineering and regenerative medicine. The integration of magnetic nanoarchitectures into synthetic/natural scaffold formulations allowed obtaining "on demand" responsive structures able to guide the regeneration process. The aim of this work was the design and characterization of three-dimensional (3D) chitosan-based scaffolds containing dextran-grafted maghemite nanoarchitectures (DM) and functionalized with l-arginine (l-Arg) amino acid as bioactive agent. A homogeneous pore distribution and a high degree of interconnection were obtained for all the structures with DMs, which resulted well distributed inside the polymer matrix. All the results suggest that the simultaneous presence of DMs and l-Arg conferred interesting mechano-structural and bioactive properties toward osteoblast-like and human mesenchymal stem cells, differentially stimulating their proliferation both in the absence and in the presence of a time-dependent magnetic field. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1244-1252, 2019.