Integration of chemokine signaling with non-coding RNAs in tumor microenvironment and heterogeneity in different cancers.

Chemokines are small secreted proteins that regulate the immune system by signaling through chemokine receptors to induce immune cell migration, motility, and infiltration into the tissue. Altered chemokine/receptor expression is associated with numerous inflammatory diseases, and more recently in non-immune cell diseases like cancer. Emerging new studies demonstrate that chemokines can directly modulate the tumor microenvironment (TME) to assist tumorigenesis by regulating proinflammatory signaling, immune cell infiltration,and metastasis. However, the diversity and complexity in the regulation of chemokine expression and how chemokine receptor signaling influences TME needs comprehensive understanding. One mechanistic pathway that has shown promising early results in targeting tumor progression is the non-coding RNAs (ncRNAs). These are widely expressed and designated as prime gene regulatory factors in tumors and the immune system. Notably, ncRNAs have been implicated in regulating chromatin stability, translation of cytoplasmic mRNAs, and the functional regulation of membrane-less nuclear bodies, which are significant pathways implicated in tumorigenesis. Tissue-specific patterns of expression of ncRNAs have suggested their role as potential cancer biomarkers, providing a suitable rationale for targeting them clinically. In this review, we discuss the recent findings which demonstrate the role of differential expression of chemokines and ncRNA in modulating TME during tumor progression. We also discuss the communication between tumor and immune effector cells via chemokine/ncRNAs and identify their potential as novel therapeutic targets.

Optimized culture conditions facilitate the estrone biodegradation ability and laccase activity of Spirulina CPCC-695.

Endocrine disrupting compounds (EDCs) are emerging contaminants that persist and contaminate the environment. They mimic hormones, block hormones, or modulate their synthesis, metabolism, transport, and action, affecting living organisms and their progeny. Steroid hormones from exogenous sources like water bodies are important EDCs. Their biodegradation is an urgent global need. The present study is a preliminary work to maximize the estrone degradation potential of Spirulina CPCC-695 and study the effect of optimized conditions on its laccase activity. It was observed that the exponential phase culture at pH 10.0, 30 ℃, and 200 rpm of agitation speed resulted in the maximum growth, estrone degradation efficiency (93.12%), and highest laccase activity (74%) of Spirulina CPCC-695.

Recent advances in the synthesis, characterization and biomedical applications of zinc oxide nanoparticles.

Zinc oxide nanoparticles (ZnONPs) have become the widely used metal oxide nanoparticles and drawn the interest of global researchers due to their biocompatibility, low toxicity, sustainability and cost-effective properties. Due to their unique optical and chemical properties, it emerges as a potential candidate in the fields of optical, electrical, food packaging and biomedical applications. Biological methods using green or natural routes are more environmentally friendly, simple and less use of hazardous techniques than chemical and/or physical methods in the long run. In addition, ZnONPs are less harmful and biodegradable while having the ability to greatly boost pharmacophore bioactivity. They play an important role in cell apoptosis because they enhance the generation of reactive oxygen species (ROS) and release zinc ions (Zn2+), causing cell death. Furthermore, these ZnONPs work well in conjunction with components that aid in wound healing and biosensing to track minute amounts of biomarkers connected to a variety of illnesses. Overall, the present review discusses the synthesis and most recent developments of ZnONPs from green sources including leaves, stems, bark, roots, fruits, flowers, bacteria, fungi, algae and protein, as well as put lights on their biomedical applications such as antimicrobial, antioxidant, antidiabetic, anticancer, anti-inflammatory, antiviral, wound healing, and drug delivery, and modes of action associated. Finally, the future perspectives of biosynthesized ZnONPs in research and biomedical applications are discussed.

Biosynthesis, characterization and biomedical potential of Arthrospira indica SOSA-4 mediated SeNPs.

The use of aqueous cyanobacterial extracts for selenium nanoparticle (SeNP) synthesis is considered green, cost-effective, and eco-friendly technology that is more advanced than physical and chemical methods. In the current study, an aqueous extract of Arthrospira indica SOSA-4 was used as a reducing and stabilizing agent for the green synthesis of SeNPs. The UV-Visible absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-Ray diffraction, Raman spectroscopy, Atomic force microscopy (AFM), Scanning electron microscopy-Energy Dispersive X-Ray spectroscopy(SEM-EDX), and Transmission electron microscopy (TEM) were performed to characterize the biosynthesized SeNPs. Gas chromatography-Mass spectrometry (GC-MS) was also performed to know the composition of the cyanobacterial extract. SEM, TEM, and AFM showed the average size of SeNPs to be 8.5 nm, 9 nm, and 8.7 nm respectively. FT-IR analysis demonstrated the presence of functional groups on the SeNPs that acted as stabilizing agents. XRD pattern and Raman spectroscopy showed the amorphous nature of SeNPs. Synthesized SeNPs showed significant antioxidant activity in DPPH, FRAP, SOR, and ABTS assay. SeNPs showed good anti-microbial activity against Staphylococcus aureus, Escherichia coli, Candida albicans, Candida glabrata, and Candida tropicalis and good anti-cancer activity in MTT assay, Trypan assay, and Flow cytometry analysis against MCF-7, SiHa, and SW480 cell lines. Non-toxicity of SeNPs against normal cell line (HEK-293) was an additional property that affirmed its potential as a bio-compatible nanomaterial.

Biofabrication and characterization of cyanobacteria derived ZnO NPs for their bioactivity comparison with commercial chemically synthesized nanoparticles.

Due to unique properties of the nanoparticles (NPs) with biocompatibility, their application as drug in drug delievery and diagnostics, the recent scientific branch nanotechnology has emerged as hope in modern medicine. Zinc oxide nanoparticles (ZnO NPs) have gained tremendous interest due to their potential use as chemotherapeutic and antimicrobial agents. They are included in the category of "generally recognized as safe (GRAS) metal oxide". There is an urgent need for developing additional sources of ZnO NPs. Therefore, in the present study 30 cyanobacterial extracts were screened for ZnO NPs synthesis.. The color change of the reaction mixture from blue to pale white indicated the synthesis of ZnO NPs. It was further confirmed by UV-Visible spectroscopy that showed the absorption peak at 372 nm. The SEM analysis during screening revealed that Oscillatoria sp. synthesized smallest ZnO NPs (~40 nm) that were further optimized for their higher yield by altering reaction conditions (pH, temperature, reaction time, concentration of extract and metal precursor). Best conditions for ZnO NPs synthesis are (0.02 M zinc nitrate, 10 ml of extract volume, pH 8, at 80 °C for 3 h). The NPs were purified through calcination at 350°C and characterized by UV-Vis, FTIR, XRD, SEM-EDAX, TEM, Zeta potential and DLS analysis. The comparative analysis of purified biogenic ZnO NPs with commercial chemically synthesized ZnO NPs (CS), exhibited their superior nature as antioxidant and anti-bacterial agent against both gram-positive and gram-negative bacteria. Synergistic effects of biogenic ZnO NPs and streptomycin additionally favored for their future use as a potential biomedical agent.

Facile green bio-fabricated silver nanoparticles from Microchaete infer dose-dependent antioxidant and anti-proliferative activity to mediate cellular apoptosis.

With the rapid development of nanotechnology, much has been anticipated with silver nanoparticles (AgNPs) due to their extensive industrial and commercial applications. However, it has raised concerns over environmental safety and human health effects. In this study, AgNPs were bio-fabricated using aqueous extract of Microchaete and their medical applications like antioxidant, anti-proliferative, and apoptosis were done. The biosynthesis of AgNPs was continuously followed by UV-vis spectrophotometric analysis. The physiochemical properties like shape, size, crystallinity, and polydispersity of the nanoparticles were determined by Scanning Electron Microscopy (SEM) along with EDX, Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), dynamic light scattering (DLS), and X-Ray Diffraction (XRD). Biosynthesized 7.0 nm sized AgNPs with the crystalline structure (crystalline size 4.8 nm) having a hydrodynamic diameter of 38.74 ± 2.6 nm was achieved due to the involvement of reducing agents present in the cyanobacterial extract. The IC50 values of the AgNPs were evaluated as 75 µg/ml and 79.41 µg/ml with HepG2 and MCF-7 cell lines. Different in-vitro cellular assays investigated in the present study exhibited antioxidant, anti-proliferative, and apoptotic activities. Probably delayed apoptosis in HepG2 and MCF-7 is due to better antioxidant activities of Microchaete based AgNPs.

Fabrication of metal incorporated polymer composite: An excellent antibacterial agent.

US Food and Drug Administration (FDA) allowed for direct addition of castor oil for human consumption as food and most recently FDA approved castor oil as over-the-counter (OTC) for laxative drug. The present article highlights the green route phosphorylation of castor oil (COL) via condensation polymerization. Further, the incorporation of metal ions Cu (II)) and Zn (II) into the polymer matrix have been carried out at elevated temperature using catalyst p-toluene sulphonic acid (PTSA). The modification of the said material has been confirmed by FT-IR, UV-VIS, and 1H and 31P-NMR spectroscopy. Further, the in vitro antibacterial activities of the metal incorporated-COL has been performed by standard methods against B. cereus (MCC2243) (gram-positive) and E. coli (MCC2412) (gram-negative) bacteria. The results revealed that the incorporation of metal ions into the polymer matrix increases the antibacterial activity largely. This may be governed by the electrostatic interaction between metal ions and microbes, also the generation of free active oxygen hinders the normal activity of bacteria. These results suggest that the synthesized material may act a potential candidate for low cost, environment friendly antibacterial agents and may find their application in clinical fields. Herein we are also proposing mechanism of antibacterial activity.

A consensus-guided approach yields a heat-stable alkane-producing enzyme and identifies residues promoting thermostability.

Aldehyde-deformylating oxygenase (ADO) is an essential enzyme for production of long-chain alkanes as drop-in biofuels, which are compatible with existing fuel systems. The most active ADOs are present in mesophilic cyanobacteria, especially Nostoc punctiforme Given the potential applications of thermostable enzymes in biorefineries, here we generated a thermostable (Cts)-ADO based on a consensus of ADO sequences from several thermophilic cyanobacterial strains. Using an in silico design pipeline and a metagenome library containing 41 hot-spring microbial communities, we created Cts-ADO. Cts-ADO displayed a 3.8-fold increase in pentadecane production on raising the temperature from 30 to 42 °C, whereas ADO from N. punctiforme (Np-ADO) exhibited a 1.7-fold decline. 3D structure modeling and molecular dynamics simulations of Cts- and Np-ADO at different temperatures revealed differences between the two enzymes in residues clustered on exposed loops of these variants, which affected the conformation of helices involved in forming the ADO catalytic core. In Cts-ADO, this conformational change promoted ligand binding to its preferred iron, Fe2, in the di-iron cluster at higher temperature, but the reverse was observed in Np-ADO. Detailed mapping of residues conferring Cts-ADO thermostability identified four amino acids, which we substituted individually and together in Np-ADO. Among these substitution variants, A161E was remarkably similar to Cts-ADO in terms of activity optima, kinetic parameters, and structure at higher temperature. A161E was located in loop L6, which connects helices H5 and H6, and supported ligand binding to Fe2 at higher temperatures, thereby promoting optimal activity at these temperatures and explaining the increased thermostability of Cts-ADO.

Study on the interaction of antidiabetic drug Pioglitazone with calf thymus DNA using spectroscopic techniques.

Pioglitazone is an antidiabetic drug used to treat type 2 diabetes mellitus. Interaction of Pioglitazone with calf thymus DNA was investigated using multispectroscopic techniques and molecular docking study. Quenching and binding constant was calculated at 3 different temperatures. The binding constant of Pioglitazone with calf thymus DNA was calculated to be 6.49 × 103 M-1 at 293 K. The quenching mechanism was found to be a static process, and thermodynamic parameters revealed van der Waals interactions and hydrogen bonds to be the major force working in Pioglitazone-DNA interaction. Pioglitazone follows the nonintercalative mode of binding and was involved in complex formation with DNA through minor groove binding and electrostatic interactions. Experiments like KI quenching studies, dye displacement assays, Circular Dichroism (CD) spectroscopy, DNA melting study, and viscosity measurements studies supported the nonintercalative mode of binding. This was further corroborated by molecular docking studies.

Interaction of procarbazine with calf thymus DNA-a biophysical and molecular docking study.

Interaction of procarbazine (PCZ) with calf thymus DNA was studied using biophysical and molecular docking studies. Procarbazine was to interact with DNA with a binding constant of 6.52 × 103  M-1 as calculated using ultraviolet-visible spectroscopy. To find out the binding mode, molecular docking was performed that predicted PCZ to interact with DNA through groove binding mode with binding affinity of -6.7 kcal/mole. To confirm the groove binding nature, different experiments were performed. Dye displacement assays confirmed the non-intercalative binding mode. Procarbazine displaced Hoechst dye from the minor groove of DNA while it was unable to displace intercalating dyes. There was no increase in the viscosity of DNA solution in presence of PCZ. Also, negligible change in the secondary structure of DNA was observed in presence of PCZ as evident by circular dichroism spectra. Procarbazine caused decrease in the melting temperature of DNA possibly because of decrease in the stability of DNA caused by groove binding interaction of PCZ with DNA.

Selective Effect of Pesticides on Plant--A Review.

This review represents systematic and integrated picture of pesticide exposure to plant and its effect on growth and metabolism. Decades ago, agrochemicals were introduced aiming at enhancing crop yields and protecting crops from pests. Due to adaptation and resistance developed by pests to chemicals, every year higher amounts and new chemical compounds are used to protect crops, causing undesired side effects and raising the costs of food production. Biological chemical free agriculture is gaining also more and more support but it is still not able to respond to the need for producing massive amounts of food. The use of agrochemicals, including pesticides, remains a common practice especially in tropical regions and South countries. Cheap compounds, such as DDT, HCH, and Lindane, that are environmentally persistent, are today banned from agriculture use in developed countries, but remain popular in developing countries. As a consequence, persistent residues of these chemicals contaminate food and disperse in the environment. Therefore, the thrust of this paper was to review the application of pesticides effect early from germination to growth of the plant, leading to alteration in biochemical, physiological and different enzymatic and non-enzymatic antioxidants which ultimately affect the yield and resulted in residues in plant, vegetables, and fruits.

Facile Algae-Derived Route to Biogenic Silver Nanoparticles: Synthesis, Antibacterial, and Photocatalytic Properties.

Biogenic synthesis of metal nanoparticles is of considerable interest, as it affords clean, biocompatible, nontoxic, and cost-effective fabrication. Driven by their ability to withstand variable extremes of environmental conditions, several microorganisms, notably bacteria and fungi, have been investigated in the never-ending search for optimal nanomaterial production platforms. Here, we present a hitherto unexplored algal platform featuring Chlorella pyrenoidosa, which offers a high degree of consistency in morphology of synthesized silver nanoparticles. Using a suite of characterization methods, we reveal the intrinsic crystallinity of the algae-derived nanoparticles and the functional moieties associated with its surface stabilization. Significantly, we demonstrate the antibacterial and photocatalytic properties of these silver nanoparticles and discuss the potential mechanisms that drive these critical processes. The blend of photocatalytic and antibacterial properties coupled with their intrinsic biocompatibility and eco-friendliness make these nanoparticles particularly attractive for wastewater treatment.

Screening of cyanobacterial extracts for synthesis of silver nanoparticles.

Improvement of reliable and eco-friendly process for synthesis of metallic nanoparticles is a significant step in the field of application nanotechnology. One approach that shows vast potential is based on the biosynthesis of nanoparticles using micro-organisms. In this study, biosynthesis of silver nanoparticles (AgNP) using 30 cyanobacteria were investigated. Cyanobacterial aqueous extracts were subjected to AgNP synthesis at 30 °C. Scanning of these aqueous extracts containing AgNP in UV-Visible range showed single peak. The λ max for different extracts varied and ranged between 440 and 490 nm that correspond to the "plasmon absorbance" of AgNP. Micrographs from scanning electron microscope of AgNP from cyanobacterial extracts showed that though synthesis of nanoparticles occurred in all strains but their reaction time, shape and size varied. Majority of the nanoparticles were spherical. Time taken for induction of nanoparticles synthesis by cyanobacterial extracts ranged from 30 to 360 h and their size from 38 to 88 nm. In terms of size Cylindrospermum stagnale NCCU-104 was the best organism with 38 and 40 nm. But in terms of time Microcheate sp. NCCU-342 was the best organism as it took 30 h for AgNP synthesis.

Antiangiogenic and antiproliferative assessment of cyanobacteria.

Biologically active compounds with different modes of action, such as antiproliferative, antioxidant, antimicrotubule, have been isolated from algae and cyanobacteria. The present study was designed to evaluate antiangiogenic and antiproliferative potential of dichloromethane and methanol (2:1) extracts of different cyanobacteria. Further fingerprinting of the activity possessing extracts were carried out using ESI-LC-MS/MS. Extracts (25, 50 and 100 microg) were screened in the vascular endothelial growth factor (VEGF) induced angiogenesis in inovo chick chorioallontoic membrane assay (CAM) at various concentrations using thalidomide and normal saline as positive and untreated control groups respectively. The extracts were also evaluated for their antiproliferative activity by MTT assay using HeLa cancer cell line. The results obtained from the various algal extracts did not show any significant antiangiogenic activity as compared to VEGF control. Oscillatoria sp. and Lyngbya officinalis exhibited significant anti-proliferative activity at IC50 values of 220 and 260 microg/mL respectively. ESI-LC-MS/MS of L. officinalis showed the presence of lyngbyatoxin-A and that of Oscillatoria sp. reveals the presence of malyngamide-J suggesting the possibility of antiproliferative activity.

Biochemical Characterization of Laccase from Spirulina CPCC-695 and Their Role in Estrone Degradation.

The addition of exogenous endocrine disrupting compounds (EDCs) like estrone, in the food chain through the aquatic system, disrupts steroid biosynthesis and metabolism by altering either the genomic or non-genomic pathway that eventually results in various diseases. Thus, bioremediation of these compounds is urgently required to prevent their addition and persistence in the environment. Enzymatic degradation has proven to be a knight in shining armour as it is safe and generates no toxic products. The multicopper oxidases (E.C. 1.10.3.2 benzenediol: oxygen oxidoreductase), laccase with the potential to degrade both phenolic and non-phenolic substrates has recently gained attention. In this study, the laccase was purified, characterized, and used to study estrone degradation. The culture filtrate (crude laccase) was concentrated and precipitated using cold-acetone and dialyzed against tris buffer (50 mM) giving a four-fold partially purified form, with 45.56% yield and 204.14 U/mg as specific activity and a single peak at 250-300 nm. The partially purified laccase was approximately 80 kDa as estimated by SDS-PAGE preferred ABTS as substrate. Both crude and partially purified laccase showed maximum activity at pH 3.0, 40 °C, and 4 mM ABTS. Kinetic constants (Km, Vmax) of crude and partially purified laccase were found to be 0.83 mM; 494.31 mM/min, and 0.58 mM; 480.54 mM/min respectively. Iron sulphate and sodium azide inhibited laccase maximally. Crude and partially purified laccase degradation efficiency was 87.55 and 91.35% respectively. Spirulina CPCC-695 laccase with efficient estrone degradation ability renders them promising candidates for EDCs bioremediation.

Exogenous osmolytes suppresses the toxic effects of malathion on Anabaena variabilis.

Role of osmolytes is though well established for salt, drought and chilling stress, but their role in pesticide stress is yet to be explored thoroughly. The sporadic information covers our previous studies on proline with respect to endosulfan and carbaryl pesticides in cyanobacteria. Therefore, during the present investigation importance of osmolytes (exogenous and endogenous) is studied in cyanobacterial biofertilizer Anabaena variabilis in the presence of 25, 50, 75 and 100 µg mL(-1) malathion pesticide. Present investigation has two parts. In the first part we showed that malathion exert its toxic effect on growth (biomass) via. malondialdehyde (MDA) and hydrogen peroxide (H2O2). This was associated with quantitative enhancement of endogenous osmolytes (proline, sucrose, mannitol, trehalose and glycogen). In the second part effort was made to corelate effect of exogenous addition of osmolytes (which were detected in the first part of this study) on growth and antioxidant enzymes [like superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX)] of A. variabilis in the presence of 100 µg mL(-1) malathion. Surprisingly it was observed that exogenous osmolytes gave additional protection to the organism. The order of protection provided by osmolytes was as trehalose>glycogen>sucrose>mannitol>proline in A. variabilis.

Exogenous salicylic acid mediated herbicide (Paraquat) resistance in cyanobacterial biofertilizer Microchaete sp. NCCU-342.

Paddy field farming remains the dominant form of growing rice in modern times as the rice is the staple food for over half the world's population and is closely associated with food security and political stability of many countries. Record increase in rice production have been observed since the start of the Green Revolution. India is one of the largest paddy producer and exporter in the world. However, constant use of chemical herbicide like paraquat had shown adverse impact on the rice yield. Non-target organisms of the habitat including cyanobacterial paddy biofertilizer face the herbicide toxicity and are unable to perform efficiently their role as biofertilizer. Therefore, in the present study, an attempt has been made to enhance the paraquat resistance in rice biofertilizer (Microchaete sp. NCCU-342) by exogenous addition of salicylic acid. Paraquat showed toxicity in Microchaete sp. NCCU-342 in a dose-dependent manner. Concentration of paraquat >1.0 µM exhibited lethal effect since the beginning. Through successive narrow range experiment, LD50 value of paraquat was obtained as 0.6 µM. Biomass exposed to paraquat (LD50 value) and salicylic acid (0.3 mM) showed mitigation in free radical production (2.20 % MDA and 1.69 % H2O2) and enhancement in the activity of the antioxidant enzymes activity, i.e. SOD, CAT, APX (137.76 %, 87.45 %, 118 %, respectively) and osmolytes (3.8 % proline and 21.51% sucrose). Thus, for sustainable agricultural practice, especially for paddy field cyanobacterial biofertilizer, application of salicylic acid or organism with higher salicylic acid production ability may be an alternative to overcome the paraquat toxicity.

Toxicological assessment of Phormidium sp. derived copper oxide nanoparticles for its biomedical and environmental applications.

Driven by the need to biosynthesized alternate biomedical agents to prevent and treat infection, copper oxide nanoparticles (CuONPs) have surfaced as a promising avenue. Cyanobacteria-derived synthesis of CuONPs is of substantive interest as it offers an eco-friendly, cost-effective, and biocompatible route. In the present study biosynthesized CuONPs were characterized and investigated regarding their toxicity. Morphological analysis using TEM, SEM and AFM showed the spherical particle size of 20.7 nm with 96% copper that confirmed the purity of CuONPs. Biogenic CuONPs with IC50 value of 64.6 µg ml-1 showed 90% scavenging of free radicals in superoxide radical scavenging assay. CuONPs showed enhanced anti-inflammatory activity by 86% of protein denaturation with IC50 value of 89.9 µg ml-1. Biogenic CuONPs exhibited significant toxicity against bacterial strains with lowest MIC value of 62.5 µg ml-1 for B. cereus and fungal strain with a MIC value of 125 µg ml-1 for C. albicans. In addition CuONPs demonstrated a high degree of synergistic interaction when combined with standard drugs. CuONPs exhibited significant cytotoxicity against non-small cell lung cancer with an IC50 value of 100.8 µg ml-1 for A549 and 88.3 µg ml-1 for the H1299 cell line with apoptotic activities. Furthermore, biogenic CuONPs was evaluated for their photocatalytic degradation potential against methylene blue dye and were able to removed 94% dye in 90 min. Free radical scavenging analysis suggested that CuONPs assisted dye degradation was mainly induced by hydroxide radicals. Biogenic CuONPs appears as an eco-friendly and cost effective photocatalyst for the treatment of wastewater contaminated with synthetic dyes that poses threat to aquatic biota and human health. The present study highlighted the blend of biomedical and photocatalytic potential of Phormidium derived CuONPs as an attractive approach for future applications in nanomedicine and bioremediation.

Chromium (VI) induced oxidative stress in Hapalosiphon fontinalis.

Heavy metals in air, soil, and water are great threat to the environment. Effluents from paint, tannery, electroplating industries contaminate irrigation water, which in turn exhibit toxic response to many crops and microorganisms including cyanobacterial biofertilizers. In aquatic system Cr exist in many forms, whereas, Cr(VI) is most toxic. In the present study metabolic alteration were studied in a cyanobacterial biofertilizer (Hapalosiphon fontinalis) in response to chromium (VI) with special reference to oxidative stress. Maximum growth inhibition was observed at 0.5 mM Cr at 20th day. Lipid peroxidation as TBARS increased with the increase in chromium concentration and suggested free radical mediated toxicity. Elevated levels of ß- carotene, astaxanthin, superoxide dismutase, catalase and ascorbate peroxidase indicated their role in survival strategy of the test organism.

Monitoring stress responses in cyanobacterial scytonemin--screening and characterization.

Scytonemin is believed to protect a variety of organisms against the negative effects of ultraviolet radiation. Cyanobacteria have evolved different strategies to minimize the potential damage caused by solar ultraviolet radiation. This includes the synthesis of the UV-absorbing compound scytonemin, which acts as a sunscreen. During the present study scytonemin was found in 9 out of 19 studied cyanobacterial strains. Aulosira fertilissima showed the maximum amount of scytonemin. The effect of environmental factors, including temperature, light intensity, UV-light and salt was studied on scytonemin synthesis of A. fertilissima. A remarkable change in scytonemin synthesis was observed under salt stress and UV-light stress. Scytonemin increased under all stress conditions but it increased maximally under yellow-light stress.