Mining genomic regions associated with agronomic and biochemical traits in quinoa through GWAS.

Quinoa (Chenopodium quinoa Willd.), an Andean crop, is a facultative halophyte food crop recognized globally for its high nutritional value and plasticity to adapt to harsh conditions. We conducted a genome-wide association study on a diverse set of quinoa germplasm accessions. These accessions were evaluated for the following agronomic and biochemical traits: days to 50% flowering (DTF), plant height (PH), panicle length (PL), stem diameter (SD), seed yield (SY), grain diameter (GD), and thousand-grain weight (TGW). These accessions underwent genotyping-by-sequencing using the DNBSeq-G400R platform. Among all evaluated traits, TGW represented maximum broad-sense heritability. Our study revealed average SNP density of ≈ 3.11 SNPs/10 kb for the whole genome, with the lowest and highest on chromosomes Cq1B and Cq9A, respectively. Principal component analysis clustered the quinoa population in three main clusters, one clearly representing lowland Chilean accessions, whereas the other two groups corresponded to germplasm from the highlands of Peru and Bolivia. In our germplasm set, we estimated linkage disequilibrium decay to be ≈ 118.5 kb. Marker-trait analyses revealed major and consistent effect associations for DTF on chromosomes 3A, 4B, 5B, 6A, 7A, 7B and 8B, with phenotypic variance explained (PVE) as high as 19.15%. Nine associations across eight chromosomes were also found for saponin content with 20% PVE by qSPN5A.1. More QTLs were identified for PL and TGW on multiple chromosomal locations. We identified putative candidate genes in the genomic regions associated with DTF and saponin content. The consistent and major-effect genomic associations can be used in fast-tracking quinoa breeding for wider adaptation across marginal environments.

Predictive Value of Combined HbA1c and Neutrophil-to-Lymphocyte Ratio for Diabetic Peripheral Neuropathy in Type 2 Diabetes.

BACKGROUND Diabetic peripheral neuropathy (DPN) is a prevalent complication affecting over 60% of type 2 diabetes patients. Early diagnosis is challenging, leading to irreversible impacts on quality of life. This study explores the predictive value of combining HbA1c and Neutrophil-to-Lymphocyte Ratio (NLR) for early DPN detection. MATERIAL AND METHODS An observational study was conducted at the First People's Hospital of Linping District, Hangzhou spanning from May 2019 to July 2020. Data on sex, age, biochemical measurements were collected from electronic medical records and analyzed. Employing multivariate logistic regression analysis, we sought to comprehend the factors influencing the development of DPN. To assess the predictive value of individual and combined testing for DPN, a receiver operating characteristic (ROC) curve was plotted. The data analysis was executed using R software (Version: 4.1.0). RESULTS The univariate and multivariate logistic regression analysis identified the level of glycated hemoglobin (HbA1C) (OR=1.94, 95% CI: 1.27-3.14) and neutrophil-to-lymphocyte ratio (NLR) (OR=4.60, 95% CI: 1.15-22.62, P=0.04) as significant risk factors for the development of DPN. Receiver operating characteristic (ROC) curve analysis demonstrated that HbA1c, NLR, and their combined detection exhibited high sensitivity in predicting the development of DPN (71.60%, 90.00%, and 97.2%, respectively), with moderate specificity (63.8%, 45.00%, and 50.00%, respectively). The area under the curve (AUC) for these predictors was 0.703, 0.661, and 0.733, respectively. CONCLUSIONS HbA1c and NLR emerge as noteworthy risk indicators associated with the manifestation of DPN in patients with type 2 diabetes. The combined detection of HbA1c and NLR exhibits a heightened predictive value for the development of DPN.

Therapeutic Effects of Lifei Decoction in a Murine Model of COPD Induced by LPS and Cigarette Smoke.

Introduction: The Lifei Decoction (LD) is a commonly utilized Chinese medicine for the treatment of sepsis and bronchial inflammation. However, its therapeutic potential in chronic obstructive pulmonary disease (COPD) remains unknown. Therefore, the objective of this study was to investigate the therapeutic efficacy and underlying mechanism of LD in a mouse model of COPD induced by cigarette smoke (CS) combined with lipopolysaccharide (LPS). Methods: Hematoxylin-eosin (H&E) staining was employed to observe the pathological alterations in lung tissue, while ELISA was utilized for the detection of levels of inflammatory factors in both lung tissue and bronchoalveolar lavage fluid (BALF). Additionally, Western blot analysis was conducted to assess the expression of p-NF-κB, GDF11, ZO-1, and Occludin-1 proteins. The changes in intestinal flora were evaluated using the viable bacteria count method. Results: The administration of LD demonstrates significant efficacy in mitigating pulmonary tissue damage in a murine model, while concurrently inhibiting the activation of the inflammatory pathway NF-κB to attenuate the levels of pro-inflammatory factors. Moreover, LD exhibits the capacity to enhance the expression of intestinal functional proteins ZO-1 and Occludin-1, thereby rectifying dysbiosis within the gut microbiota. Conclusion: The LD shows great promise as a potential treatment for COPD.

Activity-based protein profiling technology reveals malate dehydrogenase as the target protein of cinnamaldehyde against Aspergillus niger.

Cinnamaldehyde displays strong antifungal activity against fungi such as Aspergillus niger, but its precise molecular mechanisms of antifungal action remain inadequately understood. In this investigation, we applied chemoproteomics and bioinformatic analysis to unveil the target proteins of cinnamaldehyde in Aspergillus niger cells. Additionally, our study encompassed the examination of cinnamaldehyde's effects on cell membranes, mitochondrial malate dehydrogenase activity, and intracellular ATP levels in Aspergillus niger cells. Our findings suggest that malate dehydrogenase could potentially serve as an inhibitory target of cinnamaldehyde in Aspergillus niger cells. By disrupting the activity of malate dehydrogenase, cinnamaldehyde interferes with the mitochondrial tricarboxylic acid (TCA) cycle, leading to a significant decrease in intracellular ATP levels. Following treatment with cinnamaldehyde at a concentration of 1 MIC, the inhibition rate of MDH activity was 74.90 %, accompanied by an 84.5 % decrease in intracellular ATP content. Furthermore, cinnamaldehyde disrupts cell membrane integrity, resulting in the release of cellular contents and subsequent cell demise. This study endeavors to unveil the molecular-level antifungal mechanism of cinnamaldehyde via a chemoproteomics approach, thereby offering valuable insights for further development and utilization of cinnamaldehyde in preventing and mitigating food spoilage.

Synthesis, Characterization and Biosafety Evaluation of Hollow Gold Nanospheres.

OBJECTIVES: In order to assess the biosafety of HAuNS using zebrafish models and the cancer cell lines HepG2, HEK293, and A549, this study prepared HAuNS in a variety of sizes and alterations. METHODS: By oxidizing cobalt nanoparticles encased in gold shells, HAuNS were created. In the meantime, PEG- and PEI-coated HAuNS were created. The diameters of the HAuNS that were produced were 30~40 nm, 50~60 nm, and 70~80 nm. MTT assay was used to assess the toxicity of HAuNS on HepG2, HEK293, and A549 cells. For the investigation of their toxicities, HAuNS (50~60 nm) of various concentrations were incubated with zebrafish embryos. Then, cell death was determined using acridine orange staining. RESULTS: In a cell line model, it was demonstrated that purified HAuNS exhibit lower toxicity than unpurified HAuNS. Meanwhile, it was discovered that surface-modified HAuNS was less hazardous than unmodified HAuNS. Unpurified HAuNS (50.60 nm) exposure to embryos caused deformity and increased mortality. Moreover, embryos exposed to HAuNS displayed an increase in cell death, showing that HAuNS can put zebrafish under physiological stress. CONCLUSION: The possible toxicity of HAuNS is now more understood thanks to this investigation. The details could improve our comprehension of the nanotoxicity of medication delivery systems. Comparing HAuNS (50~60 nm) to the other two particle sizes, its toxicity was quite low. Compared to unpurified HAuNS, purified HAuNS displayed less toxicity. Comparing PEI-HAuNS and HAuNS to PEG-HAuNS, cytotoxicity was found to be lower. Our data support the use of pure HAuNS, HAuNS-PEG, and HAuNS (50~60 nm) as possible photothermal conductors when seen as a whole.

A comprehensive lettuce variation map reveals the impact of structural variations in agronomic traits.

BACKGROUND: As an important vegetable crop, cultivated lettuce is grown worldwide and a great variety of agronomic traits have been preserved within germplasm collections. The mechanisms underlying these phenotypic variations remain to be elucidated in association with sequence variations. Compared with single nucleotide polymorphisms, structural variations (SVs) that have more impacts on gene functions remain largely uncharacterized in the lettuce genome. RESULTS: Here, we produced a comprehensive SV set for 333 wild and cultivated lettuce accessions. Comparison of SV frequencies showed that the SVs prevalent in L. sativa affected the genes enriched in carbohydrate derivative catabolic and secondary metabolic processes. Genome-wide association analysis of seven agronomic traits uncovered potentially causal SVs associated with seed coat color and leaf anthocyanin content. CONCLUSION: Our work characterized a great abundance of SVs in the lettuce genome, and provides a valuable genomic resource for future lettuce breeding.

Sjogren's Syndrome Complicated With Aldosterone-Producing Adenoma: A Case Report.

Hypokalemia may be present in some patients with Sjogren's syndrome. When a patient with Sjogren's syndrome presents with hypokalemia, we would first consider it to be a result of the renal involvement of Sjogren's syndrome. However, in this case report, we present a young woman with Sjogren's syndrome who presented with hypokalemia that was not caused by renal tubular acidosis but by the presence of a coexisting aldosterone-producing adenoma. Cases of Sjogren's syndrome coexisting with aldosterone-producing adenoma are extremely rare. This finding underscores the need for more careful differential diagnosis in patients with Sjogren's syndrome who also have hypokalemia.

Dynamics of microbial community composition during degradation of silks in burial environment.

The silk residues in the soil formed the unique niche, termed "silksphere." Here, we proposed a hypothesis that silksphere microbiota have great potential as a biomarker for unraveling the degradation of the ancient silk textiles with great archaeological and conservation values. To test our hypothesis, in this study, we monitored the dynamics of microbial community composition during silk degradation via both indoor soil microcosmos model and outdoor environment with amplicon sequencing against 16S and ITS gene. Microbial community divergence was evaluated with Welch two sample t-test, PCoA, negative binomial generalized log-linear model and clustering, etc. Community assembly mechanisms differences between silksphere and bulk soil microbiota were compared with dissimilarity-overlap curve (DOC) model, Neutral model and Null model. A well-established machine learning algorithm, random forest, was also applied to the screening of potential biomarkers of silk degradation. The results illustrated the ecological and microbial variability during the microbial degradation of silk. Vast majority of microbes populating the silksphere microbiota strongly diverged from those in bulk soil. Certain microbial flora can serve as an indicator of silk degradation, which would lead to a novel perspective to perform identification of archaeological silk residues in the field. To sum up, this study provides a new perspective to perform the identification of archaeological silk residue through the dynamics of microbial communities.

Microbiome Diversity and Cellulose Decomposition Processes by Microorganisms on the Ancient Wooden Seawall of Qiantang River of Hangzhou, China.

Archaeological wood, also known as wooden cultural relics, refers to ancient wood that has been worked by humans. Further insights into the decomposition mechanism of archaeological wood are needed for its preventive conservation. In this study, we assessed the microbiome diversity and cellulose decomposition processes on a 200-year-old ancient wooden seawall - the Qiantang River of Hangzhou, China. We used high-throughput sequencing (HTS) to deduce the metagenomic functions, particularly the cellulose-decomposing pathway of the microbial communities, through bioinformatical approaches. The predominant cellulose-decomposing microorganisms were then verified with traditional isolation, culture, and identification method. The results showed that the excavation of archaeological wood significantly altered the environment, accelerating the deterioration process of the archaeological wood through the carbohydrate metabolism and the xenobiotic biodegradation and metabolism pathways, under the comprehensive metabolism of complex ecosystem formed by bacteria, archaea, fungi, microfauna, plants, and algae. Bacteroidetes, Proteobacteria, Firmicutes, and Actinobacteria were found to be the predominant source of bacterial cellulose-decomposing enzymes. Accordingly, we suggest relocating the wooden seawall to an indoor environment with controllable conditions to better preserve it. In addition, these results provide further evidence for our viewpoints that HTS techniques, combined with rational bioinformatical data interpretation approaches, can serve as powerful tools for the preventive protection of cultural heritage.

Predictive Values of Blood Type I and Type II Interferon Production for Disease Activity and Clinical Response to TNF-α Blocking Therapy in Patients with Ankylosing Spondylitis.

Tumor necrosis factor-α (TNF-α) blocking therapy is recommended to treat ankylosing spondylitis for patients who fail to respond to nonsteroidal anti-inflammatory drugs (NSAIDs). Herein, we attempt to dissect whether blood type I and II interferon (IFN) production can be predictive of ankylosing spondylitis progression and treatment response to the tumor necrosis factor inhibitor (TNFi). A total of 50 ankylosing spondylitis patients receiving originator TNFi with a 6-month period were retrospectively analyzed. The patients who reached the Assessment of SpondyloArthritis international Society 40 (ASAS40) response at the 6-month interval were classified as responders (n = 29) to TNFi treatment, otherwise as non-responders (n = 21). The serum type I IFN activity, and the serum levels of IFN-α and IFN-γ in the patients at baseline were notably greater than the healthy controls. Pearson correlation analysis showed positive correlations in the patients between the serum type I IFN activity or the serum levels of IFN-α and IFN-γ, and BASDAI scores, ASDASCRP or pro-inflammatory factor production. The responders were demonstrated with reduced serum type I IFN activity concomitant with lower serum levels of IFN-α and IFN-γ compared to the non-responders after anti-TNF treatment. The serum type I IFN activity, and the serum levels of IFN-α and IFN-γ used as a test to predict responders and non-responders to anti-TNF treatment produced an area under the curve (AUC) of 0.837, 0.814, and 0.787, respectively. In conclusion, the study demonstrates that blood type I and II IFN production may be correlated with disease activity, inflammatory cytokine production, and indicative of unsatisfying response to TNFi treatment in ankylosing spondylitis patients.

A transcription factor WRKY36 interacts with AFP2 to break primary seed dormancy by progressively silencing DOG1 in Arabidopsis.

The phytohormones abscisic acid (ABA) and gibberellic acid (GA) antagonistically control the shift between seed dormancy and its alleviation. DELAY OF GERMINATION1 (DOG1) is a critical regulator that determines the intensity of primary seed dormancy, but its underlying regulatory mechanism is unclear. In this study, we combined physiological, biochemical, and genetic approaches to reveal that a bHLH transcriptional factor WRKY36 progressively silenced DOG1 expression to break seed dormancy through ABI5-BINDING PROTEIN 2 (AFP2) as the negative regulator of ABA signal. AFP2 interacted with WRKY36, which recognizes the W-BOX in the DOG1 promoter to suppress its expression; Overexpressing WRKY36 broke primary seed dormancy, whereas wrky36 mutants showed strong primary seed dormancy. In addition, AFP2 recruited the transcriptional corepressor TOPLESS-RELATED PROTEIN2 (TPR2) to reduce histone acetylation at the DOG1 locus, ultimately mediating WRKY36-dependent inhibition of DOG1 expression to break primary seed dormancy. Our result proposes that the WRKY36-AFP2-TPR2 module progressively silences DOG1 expression epigenetically, thereby fine-tuning primary seed dormancy.

Phytochrome B enhances seed germination tolerance to high temperature by reducing S-nitrosylation of HFR1.

Light and ambient high temperature (HT) have opposite effects on seed germination. Light induces seed germination through activating the photoreceptor phytochrome B (phyB), resulting in the stabilization of the transcription factor HFR1, which in turn sequesters the suppressor PIF1. HT suppresses seed germination and triggers protein S-nitrosylation. Here, we find that HT suppresses seed germination by inducing the S-nitrosylation of HFR1 at C164, resulting in its degradation, the release of PIF1, and the activation of PIF1-targeted SOMNUS (SOM) expression to alter gibberellin (GA) and abscisic acid (ABA) metabolism. Active phyB (phyBY276H ) antagonizes HFR1 S-nitrosylation and degradation by increasing S-nitrosoglutathione reductase (GSNOR) activity. In line with this, substituting cysteine-164 of HFR1 with serine (HFR1C164S ) abolishes the S-nitrosylation of HFR1 and decreases the HT-induced degradation of HFR1. Taken together, our study suggests that HT and phyB antagonistically modulate the S-nitrosylation level of HFR1 to coordinate seed germination, and provides the possibility to enhance seed thermotolerance through gene-editing of HFR1.

Phosphonium-based ionic liquids as antifungal agents for conservation of heritage sandstone.

With a view to preventing fungal deterioration of historical stone artworks, we report the use of phosphonium-based ionic liquids (ILs) as potent antifungal agents against dematiaceous fungi commonly found on heritage stones. Three ILs: tributyldodecylphosphonium polyoxometalate [P44412][POM], tributyltetradecylphosphonium polyoxometalate [P44414][POM], and trihexyltetradecylphosphonium polyoxometalate [P66614][POM] were prepared and their thermal stabilities and in vitro antifungal activities were evaluated. From the ramped temperature thermogravimetric analysis and antifungal experiments it can be clearly observed that the alkyl chain length of the tetraalkylphosponium cation has a significant influence on the thermal and antifungal properties. The thermal stability and antifungal activity decreased as the number of carbon atoms of the alkyl substituents increased and, thus, followed the order [P44412][POM] > [P44414][POM] > [P66614][POM]. In addition, inoculation of four fungal species on IL-coated sandstone surfaces showed significant inhibition of fungal growth, endowing the materials with potential applications in heritage sandstone conservation.

From surviving to thriving, the assembly processes of microbial communities in stone biodeterioration: A case study of the West Lake UNESCO World Heritage area in China.

Serious concerns regarding stone biodeterioration have been raised due to the loss of aesthetic value and hidden dangers in stone cultural heritages and buildings. Stone biodeterioration involves a complex ecological interplay among organisms, however, the ecological mechanisms (deterministic or stochastic processes) that determine the microbial community on stone remain poorly understood. Here, using both amplicon and shotgun metagenomic sequencing approaches, we comprehensively investigated the biodiversity, assembly, and function of communities (including prokaryotes, fungi, microfauna, and plants) on various types of deteriorating limestone across different habitats in Feilaifeng. By generalizing classic ecological models to stone habitats, we further uncovered and quantified the mechanisms underlying microbial community assembly processes and microbial interactions within the biodeteriorated limestone. Community profiling revealed stable ecosystem functional potential despite high taxonomic variation across different biodeterioration types, suggesting non-random community assembly. Increased niche differentiation occurred in prokaryotes and fungi but not in microfauna and plant during biodeterioration. Certain microbial groups such as nitrifying archaea and bacteria showed wider niche breadth and likely contributing to the initiation, succession and expansion of stone biodeterioration. Consistently, prokaryotes were more strongly structured by selection-based deterministic processes, while micro-eukaryotes were more influenced by dispersal and drift-based stochastic processes. Importantly, microbial coexistence maintains network robustness within stone microbiotas, highlighting mutual cooperation among functional microorganisms. These results provide new insights into microbial community assembly mechanisms in stone ecosystems and may aid in the sustainable conservation of stone materials of interest.

Polyoxometalate-Ionic Liquids (ILs) and Polyvinyl Alcohol/Chitosan/ILs Hydrogels for Inhibiting Bacteria Colonising Wall Paintings.

Historical monuments are increasingly being threatened by unexpected microbial colonizers, leading to their subsequent deterioration. Here, two tetraalkylphosphonium polyoxometalate ionic liquids (Q14-IL and Q16-IL) were successfully synthesized, which showed excellent antibacterial activity against four bacteria colonising wall paintings. Notably, Q14-IL exhibited superior antibacterial efficacy compared to longer alkyl Q16-IL. Additionally, polyvinyl alcohol/chitosan (PVA-CS) hydrogels containing two ILs were prepared, and the morphology, thermal stability, swelling ratio and antibacterial activity were systematically evaluated. The results suggest that higher CS content resulted in more uniform micropores and increased the swelling ratio. However, fewer antibacterial ILs were released and diffused over time from the matrix. Hydrogels with 5% CS content exhibited the highest antibacterial activity, which was mainly attributed to the synergetic antibacterial activity of positively charged ammonium (-NH3+) groups of CS and quaternary phosphonium cation of ILs. This study may provide an alternative strategy for fighting against bacterial communities colonising ancient artworks.

The Antitumor Effect of Gene-Engineered Exosomes in the Treatment of Brain Metastasis of Breast Cancer.

Strategies for treating brain metastases of breast cancer have demonstrated limited efficacy due to the blood-brain barrier (BBB). Gene therapy could improve the efficacy of chemotherapeutic drugs. Exosomes derived from the mesenchymal stem cells (MSCs) are small membrane-based gene vectors that can pass through the BBB. CXCR4 is the most commonly found chemokine receptor in human cancer cells. Furthermore, the SDF-1/CXCR4 axis plays an important role in the homing of MSCs for tumor cell diffusion and metastasis. TRAIL can selectively induce apoptosis in transformed cells without significant toxic side effects in normal tissues. In this study, exosomes were isolated from MSCCXCR4+TRAIL transduced with CXCR4 and TRAIL using a lentiviral vector. Synergistic antitumor study showed that exosomeCXCR4+TRAIL exerted significant activity as a cooperative agent with carboplatin in an MDA-MB-231Br SCID mouse model, potentially engendering a novel strategy for advancing the treatment of brain metastases of breast cancer. Based on this study, further investigation of the effect of the vector on BBB and inducing apoptosis of brain tumors is warranted. In addition, the safety of the vector in animals during the treatment needs to be evaluated.

miR-193b regulates tumorigenesis in liposarcoma cells via PDGFR, TGFß, and Wnt signaling.

Liposarcoma is the most common soft tissue sarcoma. Molecularly targeted therapeutics have had limited efficacy in liposarcomas, in part because of inadequate knowledge of the complex molecular alterations in these tumors. Our recent study revealed the tumor suppressive function of miR-193b in liposarcoma. Considering the biological and clinical heterogeneity of liposarcoma, here, we confirmed the under-expression of miR-193b in additional patient liposarcoma samples and cell lines. Based on STRING analysis of protein-protein interactions among the reported putative miR-193b targets, we validated three: PDGFRß, SMAD4, and YAP1, belonging to strongly interacting pathways (focal adhesion, TGFß, and Hippo, respectively). We show that all three are directly targeted by miR-193b in liposarcoma. Inhibition of PDGFRß reduces liposarcoma cell viability and increases adipogenesis. Knockdown of SMAD4 promotes adipogenic differentiation. miR-193b targeting of the Hippo signaling effector YAP1 indirectly inhibits Wnt/ß-catenin signaling. Both a PDGFR inhibitor (CP-673451) and a Wnt/ ß-catenin inhibitor (ICG-001) had potent inhibitory effects on liposarcoma cells, suggesting their potential application in liposarcoma treatment. In summary, we demonstrate that miR-193b controls cell growth and differentiation in liposarcoma by targeting multiple key components (PDGFRß, SMAD4, and YAP1) in several oncogenic signaling pathways.

Neural Stem Cells Transfected with Reactive Oxygen Species-Responsive Polyplexes for Effective Treatment of Ischemic Stroke.

Neural stem cells (NSCs), capable of ischemia-homing, regeneration, and differentiation, exert strong therapeutic potentials in treating ischemic stroke, but the curative effect is limited in the harsh microenvironment of ischemic regions rich in reactive oxygen species (ROS). Gene transfection to make NSCs overexpress brain-derived neurotrophic factor (BDNF) can enhance their therapeutic efficacy; however, viral vectors must be used because current nonviral vectors are unable to efficiently transfect NSCs. The first polymeric vector, ROS-responsive charge-reversal poly[(2-acryloyl)ethyl(p-boronic acid benzyl)diethylammonium bromide] (B-PDEA), is shown here, that mediates efficient gene transfection of NSCs and greatly enhances their therapeutics in ischemic stroke treatment. The cationic B-PDEA/DNA polyplexes can effectively transfect NSCs; in the cytosol, the B-PDEA is oxidized by intracellular ROS into negatively charged polyacrylic acid, quickly releasing the BDNF plasmids for efficient transcription and secreting a high level of BDNF. After i.v. injection in ischemic stroke mice, the transfected NSCs (BDNF-NSCs) can home to ischemic regions as efficiently as the pristine NSCs but more efficiently produce BDNF, leading to significantly augmented BDNF levels, which in turn enhances the mouse survival rate to 60%, from 0% (nontreated mice) or ≈20% (NSC-treated mice), and enables more rapid and superior functional reconstruction.

Lower-Molecular-Weight Chitosan-Treated Polyethyleneimine: a Practical Strategy For Gene Delivery to Mesenchymal Stem Cells.

BACKGROUND/AIMS: Genetic modification of mesenchymal stem cells (MSCs) is an essential requirement for their use as a delivery vehicle. To achieve higher transfection efficiency and better reproducibility than previously synthesized chitosan (100 kDa)-polyethylenimine (PEI; 1200 Da), we synthesized a low molecular weight PEI (1200 Da)-grafted chitosan (50 kDa) (CP). METHODS: Safety of CP/DNA or PEI (25 kDa)/DNA was evaluated by an MTT assay using A549 cells or MSCs and a zebrafish embryo model. Effects of CP/DNA on the characteristics of MSCs were evaluated using flow cytometry. Additionally, a pGL3 plasmid was used to investigate the transfection efficiency of PEI (25 kDa), chitosan (100 kDa)-PEI (1200 Da), and CP with different N/P mass ratios on A549 cells and MSCs. Furthermore, CP/pGL3 was used to investigate the effect of serum on transfection, and intracellular transport was assessed by observing the intracellular location of DNA using laser scanning confocal microscopy. In addition, the effect of endocytosis on transfection efficiency was evaluated using A549 cells pre-treated with different inhibitors. Investigations related to analysis of transfection efficiency were all performed using the BCA protein assay to standardize the data. Furthermore, TGF-ß1-and CXCR4-expressing plasmids were applied to evaluate the gene transfer efficiency of CP, including its effects on the osteogenic differentiation and migratory ability of MSCs. RESULTS: The safety evaluation demonstrated that CP/DNA had significantly lower toxicity than PEI (25 kDa)/DNA. Additionally, DNA entered MSCs transfected by CP without changing their properties, while the examination of intracellular transport demonstrated that CP/pGL3 was internalized rapidly into MSCs. Furthermore, studies of the internalization mechanism showed that CP/pGL3 complexes entered the cells through caveolae-mediated endocytosis, thereby suggesting that the CP coating helped DNA enter A549 cells without the requirement for receptors. Compared to PEI (25 kDa), the interference of serum on transfection was reduced significantly with the use of CP in both A549 cells and MSCs. To evaluate the effects of gene delivery using the constructed CP complex and the possibility of obtaining gene-engineered MSCs, TGF-ß1- and CXCR4-expressing plasmids were successfully delivered into MSCs, confirming their ability to induce osteogenesis and change the migratory ability of MSCs, respectively. CONCLUSION: These results demonstrated that CP could be used to deliver genes into MSCs and could potentially be used in gene therapy based on MSCs.

Biomineralization Induced by Colletotrichum acutatum: A Potential Strategy for Cultural Relic Bioprotection.

Colletotrichum acutatum is a fungus capable of biomineralization reported in our previous study. In this paper, we compared the ability of this fungus to induce mineralization under different calcium sources, pH levels, and differing carbon availability. Here we found that organic acids, the alkalinity of the environment, and low carbon conditions were major factors influencing calcium carbonate precipitation. High performance liquid chromatography showed that citric acid was a metabolite produced by C. acutatum, and that other organic acids including formic, propionic, α-ketoglutaric, lactic, and succinic acids can be used by this fungus to promote CaCO3 formation. Based on these findings, the mechanism of the biomineralization induced by C. acutatum should be divided into three processes: secreting organic acid to dissolve limestone, utilizing the acid to increase the alkalinity of the microenvironment, and chelating free calcium ions with extracellular polymeric substances or the cell surface to provide a nucleation site. Interestingly, we found that hydroxyapatite rather than calcium carbonate could be produced by this fungus in the presence of phosphate. We also found that the presence of acetic acid could inhibit the transformation of vaterite to calcite. Further, we evaluated whether the proliferation of C. acutatum could influence the deterioration of stone relics. We found that low carbon conditions protected calcium carbonate from dissolution, indicating that the risk of degradation of limestone substrates caused by C. acutatum could be controlled if the fungi were used to consolidate or restore stone monuments. These results suggest that C. acutatum-induced biomineralization may be a useful treatment for deteriorated stone relics.