VAR Fabric Modification: Inducing Antibacterial Properties, Altering Wettability/Water Repellence, and Understanding Reactivity at the Molecular Level.

The present work focuses on the surface coating of VAR technical fibers, consisting of 64% viscose (cellulose), 24% Kevlar, 10% other types of polyamides, and 2% antistatic polymers. Kevlar is an aramid material exhibiting excellent mechanical properties, while cellulose is a natural linear polymer composed of repeating ß-d-glucose units, having several applications in the materials industry. Herein, we synthesized novel, tailor-designed organic molecules possessing functional groups able to anchor on VAR fabrics and cellulose materials, thus altering their properties on demand. To this end, we utilized methyl-α-d-glucopyranose as a model compound, both to optimize the reaction conditions, before applying them to the material and to understand the chemical behavior of the material at the molecular level. The efficient coating of the VAR fabric with the tailor-made compounds was then implemented. Thorough characterization studies using Raman and IR spectroscopies as well as SEM imaging and thermogravimetric analysis were also carried out. The wettability and water repellency and antibacterial properties of the modified VAR fabrics were also investigated in detail. To the best of our knowledge, such an approach has not been previously explored, among other factors regarding the understanding of the anchoring mechanism at the molecular level. The proposed modification protocol holds the potential to improve the properties of various cellulose-based materials beyond VAR fabrics.

Kevlar®, Nomex®, and VAR Modification by Small Organic Molecules Anchoring: Transfusing Antibacterial Properties and Improving Water Repellency.

The surface modification of fabrics composed of Kevlar®, Nomex®, or VAR was extensively investigated. Kevlar® and Nomex® are widely-utilized aramid materials, whereas VAR is a technical fabric comprising 64% viscose, 24% para-aramid (Kevlar®), 10% polyamide, and 2% antistatic fibers. Both aramid materials and cellulose/viscose exhibit exceptional mechanical properties that render them valuable in a wide range of applications. For the herein studied modification of Kevlar®, Nomex®, and VAR, we used small organic molecules 3-allyl-5,5-dimethylhydantoin (ADMH) and 3-(acrylamidopropyl)trimethylammonium chloride (APTAC), which were anchored onto the materials under study via graft polymerization. By doing so, excellent antibacterial properties were induced in the three studied fabrics. Their water repellency was improved in most cases as well. Extensive characterization studies were conducted to probe the properties of the modified materials, employing Raman and FTIR spectroscopies, Scanning Electron Microscopy (SEM), and thermogravimetric analysis (TGA).

Gene-Specific Intron Retention Serves as Molecular Signature that Distinguishes Melanoma from Non-Melanoma Cancer Cells in Greek Patients.

BACKGROUND: Skin cancer represents the most common human malignancy, and it includes BCC, SCC, and melanoma. Since melanoma is one of the most aggressive types of cancer, we have herein attempted to develop a gene-specific intron retention signature that can distinguish BCC and SCC from melanoma biopsy tumors. METHODS: Intron retention events were examined through RT-sqPCR protocols, using total RNA preparations derived from BCC, SCC, and melanoma Greek biopsy specimens. Intron-hosted miRNA species and their target transcripts were predicted via the miRbase and miRDB bioinformatics platforms, respectively. Ιntronic ORFs were recognized through the ORF Finder application. Generation and visualization of protein interactomes were achieved by the IntAct and Cytoscape softwares, while tertiary protein structures were produced by using the I-TASSER online server. RESULTS: c-MYC and Sestrin-1 genes proved to undergo intron retention specifically in melanoma. Interaction maps of proteins encoded by genes being potentially targeted by retained intron-accommodated miRNAs were generated and SRPX2 was additionally delivered to our melanoma-specific signature. Novel ORFs were identified in MCT4 and Sestrin-1 introns, with potentially critical roles in melanoma development. CONCLUSIONS: The property of c-MYC, Sestrin-1, and SRPX2 genes to retain specific introns could be clinically used to molecularly differentiate non-melanoma from melanoma tumors.

Ion-Based Metal/Graphene Antibacterial Agents Comprising Mono-Ionic and Bi-Ionic Silver and Copper Species.

Design of novel and more efficient antibacterial agents is a continuous and dynamic process due to the appearance of new pathogenic strains and inherent resistance development to existing antimicrobial treatments. Metallic nanoparticles (NPs) are highly investigated, yet the role of released ions is crucial in the antibacterial activity of the NP-based systems. We developed herein ion-based, metal/graphene hybrid structures comprising surface-bound Ag and Cu mono-ionic and Ag/Cu bi-ionic species on functionalized graphene, without involvement of NPs. The antibacterial performance of the resulting systems was evaluated against Escherichia coli cells using a series of parametrization experiments of varying metal ion types and concentrations and compared with that of the respective NP-based systems. It was found that the bi-ionic Ag/Cu-graphene materials exhibited superior performance compared to that of the mono-ionic analogues owing to the synergistic action of the combination of the two different metal ions on the surface and the enhancing role of the graphene support, whereas all ion-based systems performed superiorly compared to their NP-based counterparts of the same metal type and concentration. In addition, the materials exhibited sustained action, as their activity was maintained after reuse in repeated cycles employing fresh bacteria in each cycle. The systems developed herein may open new prospects toward the development of novel, efficient, and tunable antibacterial agents by properly supporting and configuring metals in ionic form.

Investigation of the Phaseolus vulgaris circadian clock and the repressive role of the PvTOC1 factor by a newly established in vitro system.

The circadian clock is crucial for the synchronization of an organism's physiology and metabolism with the geophysical time. In plants, previous work on the common bean (Phaseolus vulgaris) has identified various differing aspects of clock function compared to the widely studied Arabidopsis thaliana clock. However, transformation of legumes for the study of the circadian clock regulatory mechanisms is extremely laborious. In the present work, we describe an easy-to-follow and rapid method of preparing bean leaf protoplasts with high transformation potential and a functional circadian clock. In this system, we show that application of trichostatin A differentially changes the expression levels of several clock genes. More importantly, we investigate the effect of the clock protein PvTOC1 (Phaseolus vulgaris TIMING OF CAB EXPRESSION 1) on the activity of bean circadian promoters. We present new evidence on the function of PvTOC1 as a repressor of the promoter activity of its own gene, mediated by its conserved CCT (CONSTANS, CO-LIKE and TOC1) domain. Using our protoplast system we were able to uncover functions of the bean circadian clock and to identify an additional target of the PvTOC1clock transcription factor, not previously reported.

Ag and Cu Monometallic and Ag/Cu Bimetallic Nanoparticle-Graphene Composites with Enhanced Antibacterial Performance.

Increased proliferation of antimicrobial resistance and new strains of bacterial pathogens severely impact current health, environmental, and technological developments, demanding design of novel, highly efficient antibacterial agents. Ag, Cu monometallic and Ag/Cu bimetallic nanoparticles (NPs) were in situ grown on the surface of graphene, which was produced by chemical vapor deposition using ferrocene as precursor and further functionalized to introduce oxygen-containing surface groups. The antibacterial performance of the resulting hybrids was evaluated against Escherichia coli cells and compared through a series of parametrization experiments of varying metal type and concentration. It was found that both Ag- and Cu-based monometallic graphene composites significantly suppress bacterial growth, yet the Ag-based ones exhibit higher activity compared to that of their Cu-based counterparts. Compared with well-dispersed colloidal Ag NPs of the same metal concentration, Ag- and Cu-based graphene hybrids display weaker antibacterial activity. However, the bimetallic Ag/CuNP-graphene hybrids exhibit superior performance compared to that of all other materials tested, i.e., both the monometallic graphene structures as well as the colloidal NPs, achieving complete bacterial growth inhibition at all metal concentrations tested. This striking performance is attributed to the synergistic action of the combination of the two different metals that coexist on the surface as well as the enhancing role of the graphene support.

c-MYC targets the central oscillator gene Per1 and is regulated by the circadian clock at the post-transcriptional level.

Cell proliferation in mammals follows a circadian rhythm while disruption of clock gene expression has been linked to tumorigenesis. Expression of the c-Myc oncogene is frequently deregulated in tumors, facilitating aberrant cell proliferation. c-MYC protein levels display circadian rhythmicity, which is compatible with an in vitro repressive role of the clock-activating complex BMAL1/CLOCK on its promoter. In this report, we provide evidence for the in vivo binding of the core circadian factor BMAL1 on the human c-Myc promoter. In addition, analysis of protein synthesis and degradation rates, as well as post-translational acetylation, demonstrate that the clock tightly controls cellular MYC levels. The oncoprotein itself is a transcription factor that by responding to mitogenic signals regulates the expression of several hundred genes. c-MYC-driven transcription is generally exerted upon dimerization with MAX and binding to E-box elements, a sequence that is also recognized by the circadian heterodimer. Our reporter assays reveal that the MYC/MAX dimer cannot affect transcription of the circadian gene Per1. However, when overexpressed, c-MYC is able to repress Per1 transactivation by BMAL1/CLOCK via targeting selective E-box sequences. Importantly, upon serum stimulation, MYC was detected in BMAL1 protein complexes. Together, these data demonstrate a novel interaction between MYC and circadian transactivators resulting in reduced clock-driven transcription. Perturbation of Per1 expression by MYC constitutes a plausible alternative explanation for the deregulated expression of clock genes observed in many types of cancer.

Light at night resynchronizes the evening-phased rhythms of TOC1 and ELF4 in Phaseolus vulgaris.

Circadian clocks regulate the adaptation of the organisms' physiology to the environmental light-dark cycles. Photic resetting of the clock differs among plant species. In Arabidopsis thaliana, morning-phased genes are not responsive to light signals at night, while in Phaseolus vulgaris, morning-phased genes are responsive to light at trough phases that are reached during the night. In order to explore this further, in this work we investigated the light-responsiveness at night of two P. vulgaris evening phased genes, the orthologs of TOC1 and ELF4. Our results demonstrate that the oscillation of their expression is symphasic under all applied photic conditions. Thus, under photoperiod peak phases are obtained in the evening (LD 12:12) or early at night (LD 6:18). Light application at the beginning of the night under LD 6:18 results in a phase shift of the PvTOC1 and PvELF4 oscillation, while at the end of the night the phase remains unchanged. Moreover, when light is applied at the narrow time window of the peak phase, a significant transient increase in the expression of both PvTOC1 and PvELF4 is caused. These results indicate that, depending on the plant species, evening-phased genes may also participate in the resetting of the circadian clock machinery by light.

The circadian expression of c-MYC is modulated by the histone deacetylase inhibitor trichostatin A in synchronized murine neuroblastoma cells.

Circadian clocks govern the mammalian physiology in a day/night-dependent manner. The circadian oscillator of peripheral organs is composed of the same elements as the central pacemaker at the suprachiasmatic nucleus (SCN). The interaction between the circadian clock and several cell cycle components has been established in recent years, since many key regulators of cell cycle and growth control were proved to be rhythmically expressed. In particular, the proto-oncogene c-Myc has been documented to be under circadian regulation. Given that it is overexpressed in many malignancies, the study of c-Myc mRNA and c-MYC protein regulation by the circadian clock is of great interest. Thus, the aim of this work was to: (a) analyze in detail the circadian oscillations of c-Myc steady-state mRNA levels and to investigate whether c-MYC protein levels display any oscillating pattern, and (b) ascertain whether circadian time is important for reducing c-MYC levels after drug application. For this purpose, we selected trichostatin A (TSA), since it is known that long (>or=12 h) treatment durations negatively influence the expression levels of c-Myc and short 2 h treatments up regulate the expression of the central oscillator gene Per1 resulting in the resetting of its rhythm. TSA is a specific inhibitor of histone deacetylases (HDACs), and its application results in increased acetylation levels of histone and non-histone proteins. Our results, using the murine neuroblastoma cell line N2A, show that Per1 and c-Myc steady-state mRNA levels oscillate with the same phase. Moreover, a short 2 h TSA treatment causes a phase-dependent decrease of oscillating c-Myc transcript levels only when applied at the trough of its mRNA rhythm, where a general decrease of c-MYC protein levels is also observed. At the peak of its rhythm, no apparent changes can be observed. These experiments demonstrate for the first time that a significant decrease in c-Myc transcript and protein levels can be achieved after a short TSA treatment applied only at specific circadian times. This is also followed by a reduction in the proliferation rate of the cell population.

Synergy between the light-induced acute response and the circadian cycle: a new mechanism for the synchronization of the Phaseolus vulgaris clock to light.

PvLHY and Lhcb expression has been studied in primary bean leaves after exposure of etiolated leaves to two or three white light-pulses and under different photoperiods. Under the tested photoperiods, the steady-state mRNA levels exhibit diurnal oscillations with zenith in the morning between ZT21 and 4 for PvLHY and between ZT4 and 6 for Lhcb. Nadir is in the evening between ZT12 and 18 for PvLHY and ZT18 and 24 for Lhcb. Light-pulses to etiolated seedlings induce a differentiated acute response that is reciprocally correlated with the amplitude of the following circadian cycle. In addition, the clock modulates the duration of the acute response (descending part of the curve included), which according to the phase of the rhythm at light application extends from 7 to 18 h. This constitutes the response dynamics of the Phaseolus clock to light. Similarly, the waveform of PvLHY and Lhcb expression during the day of different photoperiods resembles in induction capability (accomplishment of peak after lights-on) and duration (from lights-on phase to trough) the phase-dependent progression of acute response in etiolated seedlings. Consequently, the peak of Lhcb (all tested photoperiods) and PvLHY (in LD 18:6) attained in the photophase corresponds to the acute response peak, while the peak of PvLHY during the scotophase (in LD 12:12 and 6:18) corresponds to the circadian peak. Thus, the effect of the response dynamics in the photoperiod determines the coincidence of the peak with the photo- or scotophase, respectively. This represents a new model mechanism for the adaptation of the Phaseolus clock to light.

Light and circadian regulation in the expression of LHY and Lhcb genes in Phaseolus vulgaris.

In order to understand some aspects of the circadian clock function in Phaseolus vulgaris, we analyzed the temporal transcript profile of Lhcb genes, typical clock reporters in plants, and that of PvLHY, an orthologue of Arabidopsis thaliana LHY which is a putative transcription factor of Lhcb genes. Under different light regimes, Lhcb and PvLHY exhibit a clear circadian pattern of expression. Moreover, the rhythm of Lhcb genes appears to be tightly coupled to that of PvLHY with the latter having a slightly earlier phase. This supports the idea that the oscillating capacity of PvLHY may be one of the causes of the rhythmic expression of Lhcb genes in bean. In addition to their circadian regulation, Lhcb and PvLHY are induced by light with similar and relatively slow induction kinetics. Moreover, this light induction is gated by the circadian oscillator: minimal responses occur at times around peaks of the pre-existing rhythm, while maximal ones occur at troughs of the pre-existing rhythm. This pattern of gating is opposite to that observed in Arabidopsis. The failure to block the light induction pathways at pre-existing troughs appears to have a detrimental effect to the subsequent circadian rhythmicity. Briefly, the overall regulation of PvLHY and Lhcb genes by light and the circadian clock reveals different strategies between Phaseolus and Arabidopsis in the adaptation to photoperiodic conditions.