Analysis of drought and heat stress response genes in rice using co-expression network and differentially expressed gene analyses.

Studies on Oryza sativa (rice) are crucial for improving agricultural productivity and ensuring global sustenance security, especially considering the increasing drought and heat stress caused by extreme climate change. Currently, the genes and mechanisms underlying drought and heat resistance in rice are not fully understood, and the scope for enhancing the development of new strains remains considerable. To accurately identify the key genes related to drought and heat stress responses in rice, multiple datasets from the Gene Expression Omnibus (GEO) database were integrated in this study. A co-expression network was constructed using a Weighted Correlation Network Analysis (WGCNA) algorithm. We further distinguished the core network and intersected it with differentially expressed genes and multiple expression datasets for screening. Differences in gene expression levels were verified using quantitative real-time polymerase chain reaction (PCR). OsDjC53, MBF1C, BAG6, HSP23.2, and HSP21.9 were found to be associated with the heat stress response, and it is also possible that UGT83A1 and OsCPn60a1, although not directly related, are affected by drought stress. This study offers significant insights into the molecular mechanisms underlying stress responses in rice, which could promote the development of stress-tolerant rice breeds.

Silk fibroin films with embedded magnetic nanoparticles: evaluation of the magneto-mechanical stimulation effect on osteogenic differentiation of stem cells.

We report about a biomaterial in the form of film ∼10 µm thick, consisting of a silk fibroin matrix with embedded iron oxide superparamagnetic nanoparticles, for prospective applications as bioactive coating in regenerative medicine. Films with different load of magnetic nanoparticles are produced (nanoparticles/silk fibroin nominal ratio = 5, 0.5 and 0 wt%) and the structural, mechanical and magnetic properties are studied. The nanoparticles form aggregates in the silk fibroin matrix and the film stiffness, as tested by nanoindentation, is spatially inhomogeneous, but the protein structure is not altered. In vitro biological tests are carried out on human bone marrow-derived mesenchymal stem cells cultured on the films up to 21 days, with and without an applied static uniform magnetic field. The sample with the highest nanoparticles/silk fibroin ratio shows the best performance in terms of cell proliferation and adhesion. Moreover, it promotes a faster and better osteogenic differentiation, particularly under magnetic field, as indicated by the gene expression level of typical osteogenic markers. These findings are explained in light of the results of the physical characterization, combined with numerical calculations. It is established that the applied magnetic field triggers a virtuous magneto-mechanical mechanism in which dipolar magnetic forces between the nanoparticle aggregates give rise to a spatial distribution of mechanical stresses in the silk fibroin matrix. The film with the largest nanoparticle load, under cell culture conditions (i.e. in aqueous environment), undergoes matrix deformations large enough to be sensed by the seeded cells as mechanical stimuli favoring the osteogenic differentiation.

Powder 3D Printing of Bone Scaffolds with Uniform and Gradient Pore Sizes Using Cuttlebone-Derived Calcium Phosphate and Glass-Ceramic.

The pore geometry of bone scaffolds has a major impact on their cellular response; for this reason, 3D printing is an attractive technology for bone tissue engineering, as it allows for the full control and design of the porosity. Calcium phosphate materials synthesized from natural sources have recently attracted a certain interest because of their similarity to natural bone, and they were found to show better bioactivity than synthetic compounds. Nevertheless, these materials are very challenging to be processed by 3D printing due to technological issues related to their nanometric size. In this work, bone scaffolds with different pore geometries, with a uniform size or with a size gradient, were fabricated by binder jetting 3D printing using a biphasic calcium phosphate (BCP) nanopowder derived from cuttlebones. To do so, the nanopowder was mixed with a glass-ceramic powder with a larger particle size (45-100 µm) in 1:10 weight proportions. Pure AP40mod scaffolds were also printed. The sintered scaffolds were shown to be composed mainly by hydroxyapatite (HA) and wollastonite, with the amount of HA being larger when the nanopowder was added because BCP transforms into HA during sintering at 1150 °C. The addition of bio-derived powder increases the porosity from 60% to 70%, with this indicating that the nanoparticles slow down the glass-ceramic densification. Human mesenchymal stem cells were seeded on the scaffolds to test the bioactivity in vitro. The cells' number and metabolic activity were analyzed after 3, 5 and 10 days of culturing. The cellular behavior was found to be very similar for samples with different pore geometries and compositions. However, while the cell number was constantly increasing, the metabolic activity on the scaffolds with gradient pores and cuttlebone-derived powder decreased over time, which might be a sign of cell differentiation. Generally, all scaffolds promoted fast cell adhesion and proliferation, which were found to penetrate and colonize the 3D porous structure.

A Novel Method for the Preparation of Poly (Acrylamide-co-Acrylonitrile) Upper Critical Solution Temperature Thermosensitive Hydrogel by the Partial Dehydration of Acrylamide Grafted Polypropylene Sheets.

In an attempt to find a potential application of cell culture harvesting, a novel method for the preparation of an upper critical solution temperature (UCST) thermosensitive hydrogel was studied. An electron accelerator was used as the electron beam (EB) radiation source, and acrylamide (AAm) was first grafted onto the pre-irradiated polypropylene (PP) sheet. Then, the grafting layer of poly (acrylamide-co-acrylonitrile) (P (AAm-co-AN)) was obtained by the partial dehydration of the acylamino group into the cyano group in the solution mixture of sulfoxide chloride (SOCl2) and dimethyl formamide (DMF). The effects of the absorbed dose, AAm concentration, reaction time, and temperature on the degree of grafting were studied, respectively. The effect of the SOCl2 concentration on the conversion degree of the cyano group from the acylamino group was studied, followed by the temperature of the UCST. The UCST properties of the grafted samples with P (AAm-co-AN) were studied by quartz crystal microbalance (QCM) and atomic force microscope (AFM), respectively. The cytotoxicities of the hydrogels against cells were verified by CCK-8 studies.

Biomedical applications of silk and its role for intervertebral disc repair.

Intervertebral disc (IVD) degeneration (IDD) is the main contributor to chronic low back pain. To date, the present therapies mainly focus on treating the symptoms caused by IDD rather than addressing the problem itself. For this reason, researchers have searched for a suitable biomaterial to repair and/or regenerate the IVD. A promising candidate to fill this gap is silk, which has already been used as a biomaterial for many years. Therefore, this review aims first to elaborate on the different origins from which silk is harvested, the individual composition, and the characteristics of each silk type. Another goal is to enlighten why silk is so suitable as a biomaterial, discuss its functionalization, and how it could be used for tissue engineering purposes. The second part of this review aims to provide an overview of preclinical studies using silk-based biomaterials to repair the inner region of the IVD, the nucleus pulposus (NP), and the IVD's outer area, the annulus fibrosus (AF). Since the NP and the AF differ fundamentally in their structure, different therapeutic approaches are required. Consequently, silk-containing hydrogels have been used mainly to repair the NP, and silk-based scaffolds have been used for the AF. Although most preclinical studies have shown promising results in IVD-related repair and regeneration, their clinical transition is yet to come.

3D Printed SiOC(N) Ceramic Scaffolds for Bone Tissue Regeneration: Improved Osteogenic Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells.

Bone tissue engineering has developed significantly in recent years as there has been increasing demand for bone substitutes due to trauma, cancer, arthritis, and infections. The scaffolds for bone regeneration need to be mechanically stable and have a 3D architecture with interconnected pores. With the advances in additive manufacturing technology, these requirements can be fulfilled by 3D printing scaffolds with controlled geometry and porosity using a low-cost multistep process. The scaffolds, however, must also be bioactive to promote the environment for the cells to regenerate into bone tissue. To determine if a low-cost 3D printing method for bespoke SiOC(N) porous structures can regenerate bone, these structures were tested for osteointegration potential by using human mesenchymal stem cells (hMSCs). This includes checking the general biocompatibilities under the osteogenic differentiation environment (cell proliferation and metabolism). Moreover, cell morphology was observed by confocal microscopy, and gene expressions on typical osteogenic markers at different stages for bone formation were determined by real-time PCR. The results of the study showed the pore size of the scaffolds had a significant impact on differentiation. A certain range of pore size could stimulate osteogenic differentiation, thus promoting bone regrowth and regeneration.

Effects of norfloxacin on decomposition and nutrient release in leaves of the submerged macrophyte Vallisneria natans (Lour.) Hara.

It is well known that antibiotic residuals affect the composition and structure of microbial communities. However, the consequences of these biological changes in terms of ecosystem function remain poorly understood, particularly in aquatic ecosystems. Here, we investigated the impacts of norfloxacin (NOR, 0, 0.5, and 8 mg L-1), a widely used antibiotic, on the microbial community structure on leaf surfaces of the submerged macrophyte Vallisneria natans, and the corresponding variations in litter decomposition, litter nutrient release, and water properties. Results showed that after 40 days of exposure, bacterial richness consistently decreased with increasing NOR concentration, and that richness of fungi was significantly lower in treatments adding NOR than in the control treatment. Moreover, NOR shifted the community toward NOR resistant phyla and genera, especially in the bacteria community. These community shifts resulted in the inhibition of litter decomposition and nutrient release from leaf litter to system water, accompanied by increases in dissolved oxygen concentration and pH of system water. Our results indicate that, by affecting microbial communities, NOR had significant effects on litter decomposition, litter nutrient release, and water properties, highlighting the potential harmful effects of NOR on aquatic ecosystem function.

Natural Fibrous Protein for Advanced Tissue Engineering Applications: Focusing on Silk Fibroin and Keratin.

As one of the important branches of natural biopolymer, natural fibrous protein has a lot of advantages including good mechanical properties, excellent biocompatibility, controllable biodegradability, renewability, abundant sources, and so on. Moreover, natural fibrous protein is also a protein that could only be used for structure supporting without any bioactivities, which attracts a lot of attentions in the field of tissue engineering scaffold. This chapter is taking silk fibroin and keratin as model materials of natural fibrous protein, focusing on their protein structure, chemical compositions, processing and extraction methods, chemical modification methods, and their applications in tissue engineering through advanced manufacturing.

Pollutant removal from agricultural drainage water using a novel double-layer ditch with biofilm carriers.

Agricultural drainage ditches can prevent flooding and mitigate agricultural pollution; however, the performance is unsatisfactory in plateau areas like the Dianchi Lake basin. Thus, a novel double-layer ditch system (DDS) with a fibrous packing as biofilm carriers was developed to form the carrier-attached biofilms and enhance the pollutant removal. The results indicated the DDS performed better than a single-layer ditch system, and annual average removal efficiencies of TN, NO3--N, NH4+-N, TP, COD and SS were 18.61%, 17.13%, 7.74%, 11.90%, 11.95% and 23.71%, respectively. High amount and carbon, nitrogen and phosphorus contents of biofilms are favourable to pollutant removal by DDS. Although bacterial diversity of biofilms remained relatively stable throughout the year, the relative abundance of dominant assemblages varied greatly. Denitrifying microorganisms affiliated with Bacteroidetes might contribute to effective NO3--N reduction. This study demonstrates DDS performed well and provides a novel method for application of biofilm carriers in drainage ditches.

Spider (Linothele megatheloides) and silkworm (Bombyx mori) silks: Comparative physical and biological evaluation.

Silks, in particular silkworm silks, have been studied for decades as possible candidate materials for biomedical applications. Recently, great attentions have been paid to spider silks, mainly due to their unique and remarkable mechanical properties. Both materials express singular interactions with cells through specific biorecognition moieties on the core proteins making up the two silks. In this work, the silk from a Colombian spider, Linothele megatheloides (LM), which produces a single type of silk in a relatively large amount, was studied in comparison with silk from Bombyx mori silkworm, before and after degumming, with the evaluation of their chemical, mechanical and biological properties. Unexpected biological features in cell culture tests were found for the LM silk already at very early stage, so suggesting further investigation to explore its use for tailored biomedical applications.

Fibroin and Polyvinyl Alcohol Hydrogel Wound Dressing Containing Silk Sericin Prepared Using High-Pressure Carbon Dioxide.

Objective: To fabricate and investigate the properties of fibroin and polyvinyl alcohol (PVA) hydrogels containing sericin prepared using high-pressure carbon dioxide (CO2). Approach: In this study, fibroin/PVA hydrogels with and without sericin were prepared using the high-pressure CO2 method. The physical and mechanical properties of the hydrogels were investigated using field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry, and the swelling, water retention, and compressive properties were assessed. Results: The hydrogels obtained from the combination of fibroin and PVA presented a compositional gradient along the hydrogel thickness and structure. The upper layer of the hydrogel consisted of a fibroin-based hydrogel blended with PVA, whereas the lower layer contained only fibroin. The mechanical properties regarding compression of the fibroin/PVA hydrogel were significantly better than those of the pure fibroin hydrogel, for hydrogels with and without sericin. Moreover, the mechanical properties of the hydrogels with sericin were significantly better than those without sericin. The water contents of all samples were >90%. Innovation: This study assessed a new combination of a wound healing agent and a biomaterial dressing. Moreover, this hydrogel production technique used a clean method without the need for a chemical crosslinking agent. Conclusion: The combination of the fibroin and PVA hydrogel and sericin prepared using the high-pressure CO2 method led to good physical properties. This material may be a candidate for medical applications.

Regenerated silk fibroin membranes as separators for transparent microbial fuel cells.

In recent years novel applications of bioelectrochemical systems are exemplified by phototrophic biocathodes, biocompatible enzymatic fuel cells and biodegradable microbial fuel cells (MFCs). Herein, transparent silk fibroin membranes (SFM) with various fibroin content (2%, 4% and 8%) were synthesised and employed as separators in MFCs and compared with standard cation exchange membranes (CEM) as a control. The highest real-time power performance of thin-film SFM was reached by 2%-SFM separators: 25.7 ±â€¯7.4 µW, which corresponds to 68% of the performance of the CEM separators (37.7 ±â€¯3.1 µW). Similarly, 2%-SFM revealed the highest coulombic efficiency of 6.65 ±â€¯1.90%, 74% of the CEM efficiency. Current for 2%-SFM reached 0.25 ±â€¯0.03 mA (86% of CEM control). Decrease of power output was observed after 23 days for 8% and 4% and was a consequence of deterioration of SFMs, determined by physical, chemical and biological studies. This is the first time that economical and transparent silk fibroin polymers were successfully employed in MFCs.

Sodium oleate induced rapid gelation of silk fibroin.

Silk fibroin has acquired increasing interest in the last years for application in medicine and namely in tissue engineering. Several methods have been developed to process fibroin and for the fabrication of nets, sponges, films and gels. This paper deals with the fabrication and characterization of fibroin hydrogels obtained by using sodium oleate as gelation agent. Gels have been prepared by mixing Silk fibroin (SF) and Sodium oleate (SO) water solutions in different concentrations, and a quite wide frame of compositions have been explored. Rheological tests have been performed to determine the gelation times, scanning electron microscopies have been made to evaluate morphologies, FTIR analysis has been done to determine the conformation of the starting materials and of the resulting gels, water content has been measured and cytotoxicity tests have been performed to validate the potential biomedical use of the hydrogels. Depending on the SF and SO different gelation times have been obtained thanks to the formation of intermolecular bonds between the fibroin chains. The obtained fastest gelation of about 80 s could make this specific formulation compatible with in situ gelation. By changing composition, gels with different morphologies, rheological properties and water contents have been prepared.

Synthesis and Postpolymerization Modification of Fluorine-End-Labeled Poly(Pentafluorophenyl Methacrylate) Obtained via RAFT Polymerization.

Chain-end-labeled polymers are interesting for a range of applications. In polymer nanomedicine, chain-end-labeled polymers are useful to study and help understand cellular internalization and intracellular trafficking processes. The recent advent of fluorescent label-free techniques, such as nanoscale secondary ion mass spectrometry (NanoSIMS), provides access to high-resolution intracellular mapping that can complement information obtained using fluorescent-labeled materials and confocal microscopy and flow cytometry. Using poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) as a prototypical polymer nanomedicine, this paper presents a synthetic strategy to polymers that contain trace element labels, such as fluorine, which can be used for NanoSIMS analysis. The strategy presented in this paper is based on reversible addition fragmentation chain transfer (RAFT) polymerization of pentafluorophenyl methacrylate (PFMA) mediated by two novel chain-transfer agents (CTAs), which contain either one (α) or two (α,ω) fluorine labels. In the first part of this study, via a number of polymerization experiments, the polymerization properties of the fluorinated RAFT CTAs were established. 19F NMR spectroscopy revealed that these fluorinated RAFT agents possess unique spectral signatures, which allow to directly monitor RAFT agent conversion and measure end-group fidelity. Comparison with 4-cyanopentanoic acid dithiobenzoate, which is a standard CTA for the RAFT polymerization of PFMA, revealed that the introduction of one or two fluorine labels does not significantly affect the polymerization properties of the CTA. In the last part of this paper, a proof-of-concept study is presented that demonstrates the feasibility of the fluorine-labeled poly(pentafluorophenyl methacrylate) polymers as platforms for the postpolymerization modification to generate PHPMA-based polymer nanomedicines.