Terms Of Growth Inhibition Research Articles

Effect of Arsenic on Fluoride Tolerance in Microbacterium paraoxydans Strain IR-1.

Fluoride (F) and arsenic (As) are two major contaminants of water and soil systems around the globe, causing potential toxicity to humans, plants, animals, and microbes. These contaminated soil systems can be restored by microorganisms that can tolerate toxic stress and provide rapid mineralization of soil, organic matter, and contaminants, using various tolerance mechanisms. Thus, the present study was undertaken with the arsenic hyper-tolerant bacterium Microbacterium paraoxydans strain IR-1 to determine its tolerance and toxicity to increasing doses of fluoride, either individually or in combination with arsenic, in terms of growth inhibition using a toxicity unit model. The minimum inhibitory concentration (MIC)and half maximal inhibitory concentration (IC50) values for fluoride increased, from 9 g/L to 11 g/L and from 5.91 ± 0.1 g/L to 6.32 ± 0.028 g/L, respectively, in the combination (F + As) group. The statistical comparison of observed and expected additive toxicities, with respect to toxicity unit (TU difference), using Student's t-test, was found to be highly significant (p < 0.001). This suggests the antagonistic effect of arsenic on fluoride toxicity to the strain IR-1. The unique stress tolerance of IR-1 ensures its survival as well as preponderance in fluoride and arsenic co-contaminated sites, thus paving the way for its possible application in the natural or artificial remediation of toxicant-exposed degraded soil systems.

Analysis of the antibacterial potentials of the leaf extracts of selected medicinal plants against pathogenic bacterial strains

Medicinal plants render herbal remedies for human ailments and hence prevail over traditional healthcare practices. This study has analysed the antibacterial potential of the leaf extracts of four selected medicinal plants namely, Azadirachta indica, Ocimum tenuiflorum, Biophytum sensitivum, and Mimosa pudica, using Kirby-Bauer’s disc diffusion method. Six bacterial species, namely Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Bacillus megaterium, Bacillus subtilis, and Brevibacillus choshinensis were used to assess the growth inhibitory potentials of the aqueous and ethanolic extracts of the selected plant leaves. The study revealed that the leaf extract of B. sensitivum had the most pronounced antibacterial potential, followed by A. indica and O. tenuiflorum. The least inhibitory potential was showed by the extracts of M. pudica. The findings of the investigation state that the aqueous extract had more consistent antibacterial activity than the ethanolic extracts, confirming that the antibacterial agents present in these leaf extracts are hydrophilic in nature. In terms of growth inhibition, the susceptibility of the pathogenic, virulent strains of bacteria toward these extracts was found comparatively lower than that of the non-virulent, environmental bacteria. With the aqueous extracts, A. baumannii was found to be the most susceptible bacterial species while E. coli was the most resistant. With the ethanolic extracts, E. coli was found to be the most susceptible and B. subtilis the least. The current study supports the usage of the screened medicinal plants in alternative medical practices, as a measure to avoid opportunistic infections by environmental bacteria.

Preclinical characterization of WB737, a potent and selective STAT3 inhibitor, in natural killer/T-cell lymphoma.

Natural killer/T-cell lymphoma (NKTL) is an uncommon malignancy with poor prognosis and limited therapeutic options. Activating mutations of signal transducer and activator of transcription 3 (STAT3) are frequently found in patients with NKTL, suggesting that targeted inhibition of STAT3 is a potential therapeutic option for this disease. Here, we have developed a small molecule drug WB737 as a novel and potent STAT3 inhibitor that directly binds to the STAT3-Src homology 2 domain with high affinity. In addition, the binding affinity of WB737 to STAT3 is 250-fold higher than STAT1 and STAT2. Interestingly, WB737 is more selective for NKTL with STAT3-activating mutations in terms of growth inhibition and apoptotic induction when compared with Stattic. Mechanistically, WB737 inhibits both canonical and noncanonical STAT3 signaling via suppression of STAT3 phosphorylation at Tyr705 and Ser727, respectively, thereby inhibiting the expression of c-Myc and mitochondria-related genes. Moreover, WB737 inhibited STAT3 more potently than Stattic, resulting in a significant antitumor effect with undetectable toxicity, followed by almost complete tumor regression in an NKTL xenograft model harboring a STAT3-activating mutation. Taken together, these findings provide preclinical proof-of-concept for WB737 as a novel therapeutic strategy for the treatment of NKTL patients with STAT3-activating mutations.

Toxic responses of freshwater microalgae Chlorella sorokiniana due to exposure of flame retardants

Flame retardants, such as Tetrabromobisphenol A (TBBPA), Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tributyl phosphate (TBP), are frequently detected in surface water. However, the effects of FRs exposure on aquatic organisms especially freshwater microalgae are still unclear. In this study, the toxicities of TBBPA, TDCPP and TBP to microalgae Chlorella sorokiniana, in terms of growth inhibition, photosynthetic activity inhibition and oxidative damage, were investigated, and according ecological risks were assessed. The results showed that TBBPA, TDCPP and TBP had inhibitory effects on C. sorokiniana, with 96 h EC50 (concentration for 50% of maximal effect) values of 7.606, 41.794 and 49.996 mg/L, respectively. Fv/Fm decreased as the increase of exposure time under 15 mg/L TBBPA. Under 50 mg/L TDCPP and 80 mg/L TBP exposure, Fv/Fm decreased significantly after 24 h. However, Fv/Fm rose after 96 h, indicating that the damaged photosynthetic activity was reversible. The content of chlorophyll a decreased, as the increase of TBBPA concentration from 3 to 15 mg/L. However, chlorophyll a increased first and then decreased, as the increase of TDCPP and TBP concentrations from 0 to 50 mg/L and 0–80 mg/L, respectively. Results indicated that C. sorokiniana could use the phosphorus of TDCPP and TBP to ensure the production of chlorophyll a. The risen content of reactive oxygen species, malondialdehyde as well as superoxide dismutase activity indicated that exposure to FRs induced oxidative stress. Additionally, the risk quotients showed that tested FRs had ecological risks in natural waters or wastewaters. This study provides insights into the toxicological mechanisms of different FRs toward freshwater microalgae for better understanding of according environmental risks.

In vitro and in vivo evaluation of kinase and protease inhibitors against Trypanosoma evansi.

Trypanosoma evansi is a causative agent of chronic wasting and fatal disease of livestock and wild animals known as surra. In this study, repurposing approach based on drug target was used to investigate the efficacy of kinase inhibitors (Barasertib-HQPA, BAR and Palbociclib isethionate, PAL) and protease inhibitors (Z-pro-prolinal, Z-PRO and Leupeptin hemisulphate, LEU) against T. evansi in HMI-9 medium. BAR, PAL and Z-PRO exhibited IC50 values of 13.52µM, 0.6375µM and 63.20µM against T. evansi in terms of growth inhibition, in the contrary, LEU failed to exhibit a significant growth inhibition at any time interval. Furthermore, oligopeptidase B and aurora kinase genes of T. evansi were targeted to determine the effect of these drugs on quantitative mRNA expression, which showed significant (p < 0.01) up-regulation of both genes in the BAR and PAL-exposed population at 12h of exposure, whereas, Z-PRO showed only significant (p < 0.05) up-regulation of aurora kinase gene at 12h interval. In cytotoxicity assay, BAR exhibited 52% and 41% cytotoxicity at 50μM concentration (about five folds the IC50 value) on equine PBMC's and Vero cell line, respectively. Similarly, the cytotoxicity of 25% and 24% were recorded at 10μM concentration (about ten folds to the IC50 value) of PAL inequine PBMC's and Vero cell line, respectively. Of these, BAR and PAL, which were found effective under in vitro trials, raised the longevity of mice at higher doses during in vivo trials. Data generated showed that kinase inhibitors have higher potential to explore therapeutic molecules against surra organism.

How chrysanthemum (Chrysanthemum × grandiflorum) 'Palisade White' deals with long-term salt stress.

Salinity is a serious problem in the cultivation of ornamental plants. Chrysanthemum (Chrysanthemum × grandiflorum) ‘Palisade White’ was evaluated in order to examine its responses to long-term salt stress. Plants were grown in substrate supplemented with NaCl doses (g dm−3 of substrate) 0, 0.44, 0.96, 1.47, 1.98, 2.48 and 2.99. The initial electrical conductivity (EC) of the substrates was 0.3, 0.9, 1.4, 1.9, 2.6, 3.1 and 3.9 dS m−1, respectively. Plant growth, relative water content (RWC), Na, Cl, K, N and P concentrations, membrane injury (MI), chlorophyll and proline levels, as well as gas exchange parameters in leaves of chrysanthemum were determined. A dose-dependent significant reduction of growth and minor decrease of leaf RWC were observed. Foliar Na and Cl concentrations increased with the highest NaCl dose up to 6-fold. However, the concentration of K increased by about 14 %, N by about 5 % but P decreased by about 23 %. Membrane injury was rather low (11 %) even at the highest NaCl dose. Statistically significant decreases of stomatal conductance (20 %), transpiration rate (32 %) and photosynthesis (25 %) were already observed at the lowest NaCl dose and about 40 % decrease of all these parameters with the highest dose. A significant reduction in the intercellular CO2 concentration occurred at the lower NaCl doses and no changes with the highest dose. These results show that in plants grown with the highest NaCl dose, non-stomatal limitation of photosynthesis may occur. According to Maas and Hoffman tolerance assessment (1977) chrysanthemum ‘Palisade White’ may be considered as moderately sensitive to salt stress in terms of growth inhibition. However, it is able to cope with long-term salt stress without any signs of damage, such as chlorophyll depletion, leaf browning or necrotic spots probably due to maintenance of K homeostasis and proline accumulation, which alleviate the toxic effect of chloride.

Inactivation of Aspergillus species in real water matrices using medium pressure mercury lamps.

The aim of this work is to understand the inactivation efficiency of medium pressure mercury lamps, measured in terms of growth inhibition as well as cell death, damage and response, using three strains from three different Aspergillus species (A. fumigatus, A. niger and, A. terreus) spiked in filtered surface water. A complete characterization of the effect of the treatment on each strain of the fungal species was assessed considering spores' morphology, cell wall integrity and enzymatic activity, the formation of pyrimidine dimers in the DNA and proteome analysis. Results showed that, when subjected to medium pressure mercury lamps, A. niger is the most resistant to inactivation, that both A. fumigatus and A. niger suffer more morphological changes and present a higher number of damaged spores and A. terreus presented more dead spores. DNA damages detected in A. niger were able to be repaired to some extent, under both light and dark conditions. Finally, proteome analysis showed that the UV radiation treatment triggered different types of stress response, including cell wall reorganization and DNA repair in A. fumigatus and A. terreus, and oxidative stress responses like the increase in production of citric acid and itaconic acid in A. niger and A. terreus, respectively.

The phytotoxicities of agricultural soil samples from a coal gangue stacking area to several maize cultivars (Zea mays L.).

In Shanxi, a major energy province in China, environmental pollution caused by coal gangue accumulation is becoming an increasingly serious problem. In addition, crops are the first trophic level in the human food chain, and the security and production of crops are closely related to human well-being. The objective of this study was to estimate the phytotoxicities of agricultural soil samples contaminated by coal gangue accumulation using maize (Zea mays L.) as a model organism. Finally, a tolerant maize cultivar was screened for coal gangue stacking areas. Seven cultivars of maize seeds were treated with agricultural soil leachate around the coal gangue stacking area at various concentrations of 0, 1:27, 1:9, 1:3, and 1:1. The results revealed that the agricultural soil leachate treatment could inhibit seed germination and the growth of roots and shoots and that the soil leachate-induced phytotoxicities were cultivar-dependent. At the same exposure concentration, tolerant maize cultivar displayed lower toxicity symptoms than sensitive maize cultivar in terms of growth inhibition, oxidative damage, and DNA damage. Stronger activities of antioxidant enzymes were observed in the tolerant maize cultivar than in the sensitive maize cultivar, indicating that the difference between cultivars in antioxidant capacity is one reason for the difference in plant tolerance. Our study provides experimental evidence for the ecological risk assessment of soil and the selection of maize cultivars with high environmental pollutant tolerance for use in coal gangue stacking areas.

Disturbed phospholipid metabolism by three polycyclic aromatic hydrocarbons in Oryza sativa

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in soils that can be readily absorbed by crops, affecting growth and development. Phospholipids (PLs) are essential components of cell membrane and can indicate cellular responses to various organic pollutants. However, the detailed molecular mechanism of phospholipid metabolism based regulation employed by crops in response to PAHs stresses remains elusive. This study characterized the accumulation patterns of representative PAHs, namely phenanthrene (PHEN), pyrene (PY), and benzo[a]pyrene (BaP) in rice (Oryza sativa). Crop’s responses to PAHs via the regulation of phospholipid metabolism were also explored. PHEN exhibited the highest accumulation in both roots and shoots, followed by PY and BaP, despite PY exhibited much greater phytotoxicity than the other two PAHs. The exposure to 10–500 μg/L PY resulted in downregulations of the phospholipase A2 genes PLA2-3, PLA2-4, and PLA2-6 (to 19% of the control without exposure) and phospholipase C genes PLC-1, PLC-2, and PLC-4 (to 50% of the control), consistent with the changes in phospholipase activity. The contents of typical PLs, including phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and phosphatidic acid also decreased to a greater extent than those in the PHEN- and BaP-exposed groups. These were the major reasons for the relatively high phytotoxicity of PY, in terms of growth inhibition and cell membrane damage. These findings provide a more comprehensive understanding of crop responses to PAHs and provide insights into risk assessment of soil PAH contamination, which hold potentials in improving food safety and quality worldwide.

Enhanced antibacterial activity of decahedral silver nanoparticles

The size and shape of silver nanoparticles (AgNPs) can potentially influence their antibacterial activity. In this study, a photochemical approach was adopted for the synthesis of decahedral AgNPs and their antibacterial activity was tested and compared against that of spherical AgNPs of similar size synthesized using the chemical reduction approach. The UV–vis spectra indicated the synthesis of decahedral AgNPs with a localized surface plasmon resonance (LSPR) peak at 502 nm. The spherical AgNPs exhibited the LSPR peak at 416 nm. Analysis of field emission gun-transmission electron microscopy (FEG-TEM) micrographs demonstrated the average diameter of decahedral silver nanoparticles as 52.1 ± 5.7 nm with side length as 33.2 ± 3.1 nm. In contrast, the average size of spherical AgNPs was 44.2 ± 6.3 nm. The decahedral AgNPs demonstrated ten times higher bactericidal activity as compared to the spherical AgNPs across all the bacterial strains tested. The minimum inhibitory concentration (MIC) for decahedral AgNPs was in the range of 4–8 μg/ml for all the four bacterial strains tested, whereas, for spherical nanoparticles of comparable size, the MIC was in the range of 40–80 μg/ml. The minimum bactericidal concentration (MBC) for decahedral AgNPs was in the range of 6–10 μg/ml. At the same time, spherical AgNPs of comparable size exhibited MBC in the range of 60–100 μg/ml for the four bacterial strains. In terms of bactericidal effect, Escherichia coli MTCC 443 was found as the most sensitive strain, while in terms of growth inhibition, Bacillus subtilis was the most sensitive strain. Staphylococcus aureus NCIM 5021 was the most resistant among the tested bacterial strains.

In vitro synergy of 5-nitrofurans, vancomycin and sodium deoxycholate against Gram-negative pathogens.

Introduction There is an urgent need for effective therapies against bacterial infections, especially those caused by antibiotic-resistant Gram-negative pathogens.HypothesisSynergistic combinations of existing antimicrobials show promise due to their enhanced efficacies and reduced dosages which can mitigate adverse effects, and therefore can be used as potential antibacterial therapy.Aim In this study, we sought to characterize the in vitro interaction of 5-nitrofurans, vancomycin and sodium deoxycholate (NVD) against pathogenic bacteria.Methodology The synergy of the NVD combination was investigated in terms of growth inhibition and bacterial killing using checkerboard and time-kill assays, respectively.Results Using a three-dimensional checkerboard assay, we showed that 5-nitrofurans, sodium deoxycholate and vancomycin interact synergistically in the growth inhibition of 15 out of 20 Gram-negative strains tested, including clinically significant pathogens such as carbapenemase-producing Escherichia coli , Klebsiella pneumoniae and Acinetobacter baumannii , and interact indifferently against the Gram-positive strains tested. The time-kill assay further confirmed that the triple combination was bactericidal in a synergistic manner.Conclusion This study demonstrates the synergistic effect of 5-nitrofurans, sodium deoxycholate and vancomycin against Gram-negative pathogens and highlights the potential of the combination as a treatment for Gram-negative and Gram-positive infections.

NADPH oxidase 4 (Nox4) deletion accelerates liver regeneration in mice

Liver is a unique organ in displaying a reparative and regenerative response after acute/chronic damage or partial hepatectomy, when all the cell types must proliferate to re-establish the liver mass. The NADPH oxidase NOX4 mediates Transforming Growth Factor-beta (TGF-β) actions, including apoptosis in hepatocytes and activation of stellate cells to myofibroblasts. Aim of this work was to analyze the impact of NOX4 in liver regeneration by using two mouse models where Nox4 was deleted: 1) general deletion of Nox4 (NOX4−/−) and 2) hepatocyte-specific deletion of Nox4 (NOX4hepKO). Liver regeneration was analyzed after 2/3 partial hepatectomy (PH). Results indicated an earlier recovery of the liver-to-body weight ratio in both NOX4−/− and NOX4hepKO mice and an increased survival, when compared to corresponding WT mice. The regenerative hepatocellular fat accumulation and the parenchyma organization recovered faster in NOX4 deleted livers. Hepatocyte proliferation, analyzed by Ki67 and phospho-Histone3 immunohistochemistry, was accelerated and increased in NOX4 deleted mice, coincident with an earlier and increased Myc expression. Primary hepatocytes isolated from NOX4 deleted mice showed higher proliferative capacity and increased expression of Myc and different cyclins in response to serum. Transcriptomic analysis through RNA-seq revealed significant changes after PH in NOX4−/− mice and support a relevant role for Myc in a node of regulation of proliferation-related genes. Interestingly, RNA-seq also revealed changes in the expression of genes related to activation of the TGF-β pathway. In fact, levels of active TGF-β1, phosphorylation of Smads and levels of its target p21 were lower at 24 h in NOX4 deleted mice. Nox4 did not appear to be essential for the termination of liver regeneration in vivo, neither for the in vitro hepatocyte response to TGF-β1 in terms of growth inhibition, which suggest its potential as therapeutic target to improve liver regeneration, without adverse effects.

Double Gamers-Can Modified Natural Regulators of Higher Plants Act as Antagonists against Phytopathogens? The Case of Jasmonic Acid Derivatives.

As key players in biotic stress response of plants, jasmonic acid (JA) and its derivatives cover a specific and prominent role in pathogens-mediated signaling and hence are promising candidates for a sustainable management of phytopathogenic fungi. Recently, JA directed antimicrobial effects on plant pathogens has been suggested, supporting the theory of oxylipins as double gamers in plant-pathogen interaction. Based on these premises, six derivatives (dihydrojasmone and cis-jasmone, two thiosemicarbazonic derivatives and their corresponding complexes with copper) have been evaluated against 13 fungal species affecting various economically important herbaceous and woody crops, such as cereals, grapes and horticultural crops: Phaeoacremonium minimum, Neofusicoccum parvum, Phaeomoniella chlamydospora, Fomitiporia mediterranea, Fusarium poae, F. culmorum, F. graminearum, F. oxysporum f. sp. lactucae, F. sporotrichioides, Aspergillus flavus, Rhizoctonia solani, Sclerotinia spp. and Verticillium dahliae. The biological activity of these compounds was assessed in terms of growth inhibition and, for the two mycotoxigenic species A. flavus and F. sporotrichioides, also in terms of toxin containment. As expected, the inhibitory effect of molecules greatly varied amongst both genera and species; cis-jasmone thiosemicarbazone in particular has shown the wider range of effectiveness. However, our results show that thiosemicarbazones derivatives are more effective than the parent ketones in limiting fungal growth and mycotoxins production, supporting possible applications for the control of pathogenic fungi.

Multiple toxic effects of tetraconazole in Allium cepa L. meristematic cells.

The application of pesticides to get more agricultural products is increasing day by day. The use of a huge amount of pesticides raises public concerns about safety. Tetraconazole is a widely used and successful fungicide. Possible toxic, cytotoxic, and genotoxic effects of different doses of tetraconazole (1.00mg/L, 5.00mg/L, and 10.00mg/L) were evaluated on the meristematic cells of Allium cepa L. root tips by means of physiological, cytogenetic, biochemical, and anatomical parameters. EC50 value for tetraconazole in terms of growth inhibition was calculated as 6.7mg/L. Increasing doses of tetraconazole resulted in reduced germination ratio, root length, and weight gain. Total activities of superoxide dismutase (SOD) and catalase (CAT) enzymes as well as malondialdehyde (MDA) content were increased as a result of oxidative stress. As an evidence of genotoxicity, mitotic index (MI) level decreased, while scores for micronucleus (MN) and chromosomal aberrations (CAs) rose. In addition, various meristematic cell damages were detected in root tips of tetraconazole applied bulbs. As a result, the multiple toxic, cytotoxic, and genotoxic effects of tetraconazole fungicide were demonstrated through a wide range of parameters on A. cepa, which was found to be a versatile tool for testing hazardous pesticides.

Acute and chronic toxicity of nickel on freshwater and marine tropical aquatic organisms

Water quality guidelines and ecological risk assessment of chemical substances like nickel (Ni) in tropical regions such as South East Asia and Melanesia are often based on temperate information as a result of fewer Ni ecotoxicity data available for tropical species. This leaves an unknown margin of uncertainty in the risk assessment in the tropics. In order to fill this data gap, this study was designed to conduct standard toxicity tests on Ni with two freshwater species (acute tests) and three marine species (acute and chronic tests) originated from tropical Hong Kong. All tests were carried out using measured concentrations of Ni with control mortality below 15%. The median lethal concentrations (LC50s) were determined as 2520 (95% confidence interval: 2210, 2860) and 426 (351, 515) μg Ni L−1 for the freshwater gastropods Pomacea lineata (48 h) and Sulcospira hainanensis (96 h), respectively, while 96 h LC50s of 4300 (3610, 5090), 18,200 (6470, 51,200), 62,400 (56,800, 68,500), and 71,700 (68,200, 75,400) μg Ni L−1 were derived for the marine copepod Tigriopus japonicus, the gastropod Monodonta labio, juvenile and adult of the marine fish Oryzias melastigma, respectively. The chronic effect concentration of 10% (EC10) based on the intrinsic rate of increase of the population of T. japonicus was 29 (12, 69) μg Ni L−1. In terms of growth inhibition, the chronic EC10 for M. labio was 34 (17, 67) μg Ni L−1. The results also indicated that T. japonicus in maturation stage (LC10: 484 (349, 919) μg Ni L−1) was less sensitive than its nauplii stage (LC10: 44 (27, 72) μg Ni L−1). This study represents an important addition of high-quality toxicity data to the tropical Ni toxicity database which can be used for future ecological risk assessment of Ni and derivation of its water quality guidelines in tropical regions.

Effect of allelochemicals on photosynthetic and antioxidant defense system of Ulva prolifera

Ulva prolifera is a macroalgae that forms massive blooms, negatively impacting natural communities, aquaculture operations and recreation. The effects of the natural products, eugenol, β-myrcene, citral and nonanoic acid on the growth rate, antioxidative defense system and photosynthesis of Ulva prolifera were investigated as a possible control strategy for this harmful taxon. Negative effects on growth were observed with all four chemicals, due to the excessive production of reactive oxygen species and oxidative damage to the thalli. However, the response of U. prolifera under the four chemicals stress was different at the cellular level. β-myrcene, the most effective compound in terms of growth inhibition, induced oxidative stress as shown by the damage of total antioxidant capacity (T-AOC) and the downregulation of the glutathione-ascorbate (GSH-ASA) cycle which inhibited the antioxidative system. This chemical also inhibited photosynthesis and photoprotection mechanisms in U. prolifera, resulting in growth limitation. In contrast, U. prolifera was less affected by the second tested chemical, eugenol, and showed no significant change on photosynthetic efficiency in the presence of the chemical. The inhibition effects of the third and fourth tested chemicals, nonanoic acid and citralon, on growth and on the antioxidant defense system in U. prolifera were inferior. These results provide a potential avenue for controlling green tides in the future.

Effect of PEG-induced drought stress on germination of ten chickpea (Cicer arietinum L.) genotypes

Chickpea (Cicer arietinum L.) is one of the most important legume crops worldwide, with its importance mainly relying on its high protein content. Chickpea productivity is strictly threatened by abiotic stresses, of which drought exerts the most crucial role in terms of growth inhibition and yield losses encountered. Given that germination is a critical stage that is negatively affected by drought, the aim of this study was to estimate the genotypic variability among ten chickpea genotypes and to determine the seed germination and seedling growth ability under drought stress conditions. Seeds were subjected to water stress by polyethylene glycol (PEG-6000) at five stress levels (0, 5, 10, 20, 30 and 50% PEG). Germination percentage, seed water content, seed water absorbance, root and shoot development and seedling vigour index were evaluated. The analyses revealed significant genetic variability in relation to genotypic performance under drought stress. Drought significantly affected germination as well as all other associated traits, with the effects of stress being analogous to the stress level applied. Findings point to the fact that seedling vigour index is a suitable selection criterion for drought tolerance as it allowed the classification of genotypes as tolerant, moderately tolerant, moderately susceptible and susceptible. Taken together, the commercial varieties ‘Thiva’, ‘Keryneia’ and ‘Gavdos’ as well as the landrace ‘Lemnos’ showed an increased drought tolerance at high stress level, indicating their possible exploitation as valuable genetic material for breeding programs or for commercial use.

Abstract 3871: A novel TACC3 inhibitor as an anti-cancer agent in breast cancer

Abstract Transforming Acidic Coiled-Coil Containing Protein 3 (TACC3) is a microtubule-associated protein that is localized on mitotic spindles and ensures proper chromosomal segregation and microtubule stability. TACC3 is frequently amplified or mutated, and was demonstrated to be a prognostic factor in a broad spectrum of cancers which makes it a highly attractive therapeutic target. TACC3 knockdown was demonstrated to cause mitotic spindle defects and prevent proper mitotic progression causing apoptotic cell death. Inhibition of TACC3 with the currently available small molecule inhibitors, KHS101 and SPL-B, has been shown to reduce the growth of glioblastoma xenografts, and suppress tumor growth in ovarian cancer xenografts, respectively. However, none of these TACC3 inhibitors is being tested in clinics potentially due to low systemic stability or high IC50 (inhibitory concentration 50) values. Here, by combining rational drug design and screening approaches, we aimed to identify a novel and more potent TACC3 inhibitor that is effective in in vitro and in vivo systems and that can be used as a mitotic blocker in breast cancer (BC). A library of test compounds was generated by replacing certain functional groups of already available TACC3 inhibitors with their isosteric equivalents to improve potency and drug-like properties. Then, the generated compounds were tested in vitro in terms of growth inhibition in a panel of breast cancer cell lines of different breast cancer subtypes. The compounds were also compared based on their effect on the cellular processes that TACC3 is involved in, and were further compared with genomic TACC3 inhibition by siRNAs. Finally, the most promising agent was tested in vivo in terms of its anti-tumorigenic effects. BO-264 was identified as the most potent TACC3 inhibitor that effectively kills breast cancer cells of different subtypes when administered at nanomolar dose. Moreover, it demonstrated superior inhibitory effects on mitotic progression, DNA repair, and cellular viability as compared to currently available inhibitors. Oral administration of BO-264 suppressed tumor growth in breast cancer xenografts at a dose that caused no apparent toxicity. Specificity of BO-264 to TACC3 protein was tested by kinome profiling and further validated by state-of-art binding assays. Currently, we are testing the pharmacokinetics and pharmacodynamics properties and organ toxicity of our inhibitor and performing the detailed molecular characterization of BO-264-mediated anti-tumor effects. Overall, our preclinical findings suggest that our novel compound (BO-264) is potentially a specific TACC3 inhibitor, causing growth inhibition in breast cancer cell lines and xenograft models by inducing mitotic arrest, DNA damage and apoptosis. Considering the critical importance of TACC3 as a cancer biomarker and driver of disease progression, BO-264 has great potential to be used as a novel therapeutic strategy in BC. Citation Format: Ozge Akbulut, Deniz Lengerli, Ozge Saatci, Elif Duman, Urartu Seker, Burcu Caliskan, Erden Banoglu, Ozgur Sahin. A novel TACC3 inhibitor as an anti-cancer agent in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3871.

Antimicrobial Photodynamic Therapy Protocols on Streptococcus mutans with Different Combinations of Wavelengths and Photosensitizing Dyes.

The aim of the study is to test the application of different laser wavelengths, with and without different photosensitizing dyes on different types of cultures. Laser irradiation was realized on Streptococcus mutans in both solid and liquid culture media in continuous mode at three different fluences (10, 20, and 30 J/cm2) with a red diode (650 nm) with toluidine blue dye, a blue-violet diode (405 nm) with curcumin dye, and a green diode (532 nm) with erythrosine dye. Without a photosensitizer, no growth inhibition was obtained with the red diode at any fluence value. Inhibition rates of 40.7% and 40.2% were obtained with the blue diode and green diode. The blue diode laser used with curcumin obtained results in terms of growth inhibition up to 99.26% at a fluence of 30 J/cm2. The red diode laser used with toluidine blue obtained results in terms of growth inhibition up to 100% at fluences of 20 and 30 J/cm2. The KTP (potassium-titanyl-phosphate) laser used with erythrosine was able to determine a complete growth inhibition (100%) at the different fluence values. The combination of a laser and its proper color may dramatically change the results in terms of bactericidal effect. It will be interesting to confirm these data by further in vivo studies.

Fluorescent Pseudomonas -FAP2 and Bacillus licheniformis interact positively in biofilm mode enhancing plant growth and photosynthetic attributes

Compatible interaction between commonly used plant growth promoting rhizobacteria (PGPR) in biofilm mode in vitro and in the rhizosphere is expected to provide better understanding for the development of effective consortium. With the above hypothesis, the present study evaluated two characterized PGPR (Pseudomonas fluorescens FAP2 and Bacillus licheniformis B642) for their biofilm-related functions using standard protocols. The interaction between the FAP2 and B642 in planktonic mode was studied by plate spot/overlay method and competitive growth assessment. Biofilm development on a microtitre plate and a glass surface was studied by standard methods. Biofilm formation was characterized by SEM. Rhizosphere and rhizoplane colonization of wheat seedlings by both isolates individually and by co-inoculation was studied by determining CFU/g of soil/root samples. Biofilm development on the root surface was further analyzed by SEM. Both isolates demonstrated multiple plant growth promoting (PGP) traits (production of IAA, siderophore, and ammonia; phosphate solubilization) and biofilm-related functions such as production of EPS, alginate, cell surface hydrophobicity and swarming motility. Both strains formed strong biofilms on a glass cover slip in vitro. Interaction between the two strains under the planktonic mode revealed no antagonism in terms of growth inhibition and competitive growth kinetics. Similarly, FAP2 and B642 strains formed a mixed biofilm on a glass cover slip as well as on seedling roots. Wheat rhizosphere and rhizoplane were colonized by both isolates as evidenced from their viable counts in single and co-inoculation. The effect of single and co inoculation revealed the significant enhancement of vegetative growth and photosynthetic parameters such as chlorophyll content, transpiration rate (E), internal CO2 concentration (Ci), stomatal conductance (gs), and net photosynthetic rate (PN) and leaf water potential (LWP) as compared to uninoculated control. Indigenous Pseudomonas fluorescens FAP2 strain and Bacillus licheniformis B642 are compatible PGPR in both planktonic and biofilm modes of growth and threfore could be developed effective consortium of PGPR. Further indepth investigation is required to understand molecular mechanism of the interaction in biofilm mode of growth under natural condition.