Cause Of Growth Inhibition Research Articles

Antibacterial mechanism of CO2 combined with low temperature against Shewanella putrefaciens by biochemical and metabolomics analysis

To further reveal the inhibition mechanism of carbon dioxide (CO2) on Shewanella putrefaciens (S. putrefaciens), influence on metabolic function was studied by biochemical and metabolomics analysis. Accordingly, reduction of intracellular pH (pHi), depolarization of cell membrane and accumulation of reactive oxygen species (ROS) indicated that CO2 changed the membrane permeability of S. putrefaciens. Besides, adenosine triphosphate (ATP), ATPase, nicotinamide adenine dinucleotide (NAD+/NADH) and ratios of NADH/NAD+ were detected, indicating a role of CO2 in repressing respiratory pathway and electron transport. According to metabolomics results, CO2 induced differential expressions of metabolites, disordered respiratory chain and weakened energy metabolism of S. putrefaciens. Inhibition of respiratory rate-limiting enzymes also revealed that electron transfer of respiratory chain was blocked, cell respiration was weakened, and thus energy supply was insufficient under CO2 stress. These results revealed that CO2 caused disruption of metabolic function, which might be the main cause of growth inhibition for S. putrefaciens.

Toxic effects and mechanisms of chronic cadmium exposure on Litopenaeus vannamei growth performance based on combined microbiome and metabolome analysis

Cadmium (Cd) pollution seriously affects marine organisms' health and poses a threat to food safety. Although Cd pollution has attracted widespread attention in aquaculture, little is known about the toxic mechanisms of chronic Cd exposure on shrimp growth performance. The study investigated the combined effects of chronic exposure to Cd of different concentrations including 0, 75, 150, and 300 μg/L for 30 days on the growth performance, tissue bioaccumulation, intestinal microbiology, and metabolic responses of Litopenaeus vannamei. The results revealed that the growth was significantly inhibited under exposure to 150 and 300 μg/L Cd2+. The bioaccumulation in gills and intestines respectively showed an increasing and inverted "U" shaped trend with increasing Cd2+ concentration. Chronic Cd altered the intestinal microflora with a significant decrease in microbial richness and increasing trends in the abundances of the potentially pathogenic bacteria Vibrio and Maribacter at exposure to 75 and 150 μg/L Cd2+, and Maribacter at 300 μg/L. In addition, chronic Cd interfered with intestinal metabolic processes. The expressions of certain metabolites associated with growth promotion and enhanced antioxidant power, including N-methyl-D-aspartic acid, L-malic acid, guanidoacetic acid, betaine, and gluconic acid were significantly down-regulated, especially at exposure to 150 and 300 μg/L Cd2+, and were negatively correlated with Vibrio and Maribacter abundance levels. In summary, chronic Cd exposure resulted in severe growth inhibition and increased Cd accumulation in shrimp tissues. Increased levels of intestinal pathogenic bacteria and decreased levels of growth-promoting metabolites may be the key causes of growth inhibition. Harmful bacteria Vibrio and Maribacter may be associated with the inhibition of growth-promoting metabolite expression and may be involved in disrupting intestinal metabolic functions, ultimately impairing shrimp growth potential. This study sheds light on the potential toxicological mechanisms of chronic Cd inhibition on shrimp growth performance, offering new insights into Cd toxicity studies in aquaculture.

Inhibition of O-acetylserine (thiol) lyase as a promising new mechanism of action for herbicides

Enzymes of the sulfur assimilation pathway of plants have been identified as potential targets for herbicide development, given their crucial role in synthesizing amino acids, coenzymes, and various sulfated compounds. In this pathway, O-acetylserine (thiol) lyase (OAS-TL; EC 2.5.1.47) catalyzes the synthesis of L-cysteine through the incorporation of sulfate into O-acetylserine (OAS). This study used an in silico approach to select seven inhibitors for OAS-TL. The in silico experiments revealed that S-benzyl-L-cysteine (SBC) had a better docking score (−7.0 kcal mol−1) than the substrate OAS (−6.6 kcal mol−1), indicating its suitable interaction with the active site of the enzyme. In vitro experiments showed that SBC is a non-competitive inhibitor of OAS-TL from Arabidopsis thaliana expressed heterologously in Escherichia coli, with a Kic of 4.29 mM and a Kiu of 5.12 mM. When added to the nutrient solution, SBC inhibited the growth of maize and morning glory weed plants due to the reduction of L-cysteine synthesis. Remarkably, morning glory was more sensitive than maize. As proof of its mechanism of action, L-cysteine supplementation to the nutrient solution mitigated the inhibitory effect of SBC on the growth of morning glory. Taken together, our data suggest that reduced L-cysteine synthesis is the primary cause of growth inhibition in maize and morning glory plants exposed to SBC. Furthermore, our findings indicate that inhibiting OAS-TL could potentially be a novel approach for herbicidal action.

Environmentally relevant concentrations of Mn2+ disrupts the endocrine regulation of growth in juvenile Yunlong groupers (Epinephelus moara♀×Epinephelus lanceolatus♂)

Even though manganese is a bioelement essential for metabolism, excessive manganese levels in water can be detrimental to fish development and growth. Therefore, the aim of this study was to evaluate the effects of Mn2+ (0, 0.5,1, 2, and 4 mg·L−1) exposure for 30 d on the growth performance, growth hormone/insulin-like growth factor (GH/IGF) axis, hypothalamic-pituitary-thyroid (HPT) axis, and monoaminergic neurotransmitters of Epinephelus moara♀×Epinephelus lanceolatus♂(Yunlong grouper). Compared with the control and low Mn2+concentration groups of (0.5 and 1 mg·L−1), the high concentration of Mn2+ (4 mg·L−1) significantly reduced body weight (BW), body length (BL), weight gain rate (WGR), and specific growth rate (SGR), increased the feed coefficient rate (FCR) and mortality of Yunlong groupers (P < 0.05). Further, the levels of GH and IGF, along with the expression of ghra and ghrb were significantly reduced after exposure to 2 and 4 mg·L−1 Mn2+for 30 d, whereas the expression of sst5 was significantly up-regulated after exposure to 2 and 4 mg·L−1 Mn2+for 20 and 30 days. Moreover, Mn2+exposure increased thyroid hormone (T3) and thyroid stimulating hormone (TSH) contents, accompanied by increased mRNA levels of dio1 and dio2, however, the T4 level was decreased. Finally, dopamine (DA) and serotonin (5-HT) levels significantly decreased after long-term exposure to higher concentrations of Mn2+, and the levels their metabolites changed as well, suggesting that the synthesis and metabolism of DA and 5-HT were affected. Accordingly, changes in the GH/IGF and HPT axes-related parameters may be the cause of growth inhibition in juvenile groupers under Mn2+ exposure, indicating that the relationship between endocrine disorder and growth inhibition should not be ignored.

Silencing the novel gene CsARR-9 increases photosynthetic efficiency and alleviates autotoxicity in cucumber

Autotoxicity is a principal cause of growth inhibition in monocultures. Autotoxicity in monocropped cucumber limits plant growth, which causes an obvious reduction in yield and quality in cucurbit crops. Cinnamic acid is a major autotoxin that has been used to mimic autotoxicity in cucumber. The long hairpin RNA (lhRNA) library of Arabidopsis was screened in cinnamic acid (CA) mimicked autotoxicity to obtain autotoxicity-resistant mutant lines. We found that a new gene, At5g16610, whose function is unknown, was silenced in the resistant mutant line HCA350–597, and the homologous gene of Arabidopsis At5g16610 (NM_203062.2), whose function is also unknown, was cloned in cucumber and named CsARR-9 (Cucumis sativus Autotoxicity Resistance Related). Here, we silenced the CsARR-9 gene using an established tobacco rattle virus (TRV) mediated virus-induced gene silencing (VIGS) system, and the CsARR-9 gene was also silenced by RNA interference in cucumber. We found that this silencing resulted in decreased CsARR-9 expression in both leaves and roots enhanced tolerance to autotoxicity mimicked by CA. Resistance to CA-mimicked autotoxicity was achieved by reductions in the CA concentrations in roots, stems and leaves, which maintained the structural integrity of cells and tissue within an organ system, promoted cell vigor, enhanced thylakoid stacking and increased the storage of photosynthetic products in chloroplasts, and these effects promote the growth of CsARR-9-silenced cucumber plants. These findings provide a valuable genetic resource for research regarding continuous cropping obstacles, especially in monocultures, and insights on the related molecular mechanism, and have important practical significance for prolonging the planting years and the efficient use of facility agriculture.

Antifungal Activity and Mechanism of Electron Beam Irradiation Against Rhizopus oryzae

Electron beam irradiation is a physical fungicidal technique that has emerged as a potential application in China. However, its antifungal activity and mechanism against Rhizopus oryzae have not been reported. Thus, this study aimed to investigate the antifungal activity and mechanism of electron beam irradiation of R. oryzae. The antifungal activity analysis showed that the D10 value and complete elimination dose of R. oryzae irradiated by electron beam were 1.73 kGy and 8.08 kGy, respectively. Electron beam irradiation has a strong inhibitory effect on the filamentous biomass of R. oryzae. To reveal the antifungal mechanism of electron beam against R. oryzae, this study analyzed the dynamic changes in the cell wall, cell membrane, and oxidative stress induced by different irradiation doses. The results showed that electron beam irradiation destroyed the cell wall structure of R. oryzae, increasing chitinase activity and decreasing chitin content. Cell membrane integrity is disrupted, increasing relative conductivity, decreasing pH values, and decreasing soluble protein content. Electron beam irradiation causes oxidative stress in cells, increasing H2O2 content, decreasing antisuperoxide anion activity, decreasing DPPH free radical scavenging activity, and inhibiting defense enzyme (CAT and SOD) activity. This phenomenon indicates that electron beams can cause structural damage to and metabolic dysfunction of cells and disorders of redox homeostasis, which may be the main cause of growth inhibition and cell death in R. oryzae.

Toxic effects of long-term dual or single exposure to oxytetracycline and arsenic on Xenopus tropicalis living in duck wastewater

Direct discharge of aquaculture wastewater may have toxic effects, due to the presence of heavy metals, antibiotics, and even resistant pathogens, but little attention has been given. Here, tanks simulating a wild ecosystem were built to study the effects of long-term exposure to duck wastewater containing oxytetracycline (OTC) and/or arsenic (As) on the growth, physiological function, and gut microbiota evolution of Xenopus tropicalis. The results showed that duck wastewater had no apparent impact on X. tropicalis, but the impact increased significantly (P < 0.05) with exposure to OTC and/or As, especially the impact on body weight and growth rate. Biochemical indicators revealed varying degrees of oxidative stress damage, hepatotoxicity (inflammation, necrosis, and sinusoids), and collagen fibrosis of X. tropicalis in all treated groups after 72 days of exposure, which indirectly inhibited X. tropicalis growth. Moreover, 16S rDNA amplicon sequencing results showed that the gut microbiota structure and metabolic function were perturbed after chronic exposure, which might be the leading cause of growth inhibition. Interestingly, the abundance of intestinal resistance genes (RGs) increased with exposure time owing to the combined direct and indirect effects of stress factors in duck wastewater. Moreover, once the RGs were expressed, the resistance persisted for at least 24 days, especially that conferred by tetA. These results provide evidence of the toxic effects of DW containing OTC (0.1–4.0 mg/L) and/or As (0.3–3.5 µg/L) on amphibians and indicate that it is vital to limit the usage of heavy metals and antibiotics on farms to control the biotoxicity of wastewater.

Reversible Hydrogenase Activity Confers Flexibility to Balance Intracellular Redox in Moorella thermoacetica.

Hydrogen (H2) converted to reducing equivalents is used by acetogens to fix and metabolize carbon dioxide (CO2) to acetate. The utilization of H2 enables not only autotrophic growth, but also mixotrophic metabolism in acetogens, enhancing carbon utilization. This feature seems useful, especially when the carbon utilization efficiency of organic carbon sources is lowered by metabolic engineering to produce reduced chemicals, such as ethanol. The potential advantage was tested using engineered strains of Moorella thermoacetica that produce ethanol. By adding H2 to the fructose-supplied culture, the engineered strains produced increased levels of acetate, and a slight increase in ethanol was observed. The utilization of a knockout strain of the major acetate production pathway, aimed at increasing the carbon flux to ethanol, was unexpectedly hindered by H2-mediated growth inhibition in a dose-dependent manner. Metabolomic analysis showed a significant increase in intracellular NADH levels due to H2 in the ethanol-producing strain. Higher NADH level was shown to be the cause of growth inhibition because the decrease in NADH level by dimethyl sulfoxide (DMSO) reduction recovered the growth. When H2 was not supplemented, the intracellular NADH level was balanced by the reversible electron transfer from NADH oxidation to H2 production in the ethanol-producing strain. Therefore, reversible hydrogenase activity confers the ability and flexibility to balance the intracellular redox state of M. thermoacetica. Tuning of the redox balance is required in order to benefit from H2-supplemented mixotrophy, which was confirmed by engineering to produce acetone.

Disruption of metabolic function and redox homeostasis as antibacterial mechanism of Lindera glauca fruit essential oil against Shigella flexneri

Current trend in food safety and public health is focusing on the use of natural antimicrobials. The Lindera glauca fruit with rich resource and essential oil has emerged as potential application in China. This work aimed to detect chemical compounds of L. glauca fruit essential oil (LGFEO) and to evaluate antimicrobial activity and mechanism of LGFEO for develop natural antimicrobials. A total of 70 volatile compounds were identified, and the major groups were monoterpene (56.62%) and sesquiterpene (39.71%). The analysis of antimicrobial activity indicated that LGFEO could effectively inhibit the growth of all tested 13 food-borne pathogens, of which Shigella flexneri had the highest inhibition zone diameter (DIZ, 25.45 nm), and the lowest minimum inhibitory concentration (MIC, 0.156 μg/mL) and bactericidal concentration (MBC, 0.312 μg/mL). To unravel antibacterial mechanism of LGFEO on S. flexneri , the dynamic changes for bacterial growth curve, material release, and the levels of intracellular mallondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), and ROS-detoxifying enzymes were analyzed in S. flexneri cells exposed to LGFEO at different concentrations (1/2 × MIC, 1 × MIC and 2 × MIC) and times (0–24 h), revealing that LGFEO could cause cell material leakage, antioxidant enzyme inactivation, H 2 O 2 and MDA accumulation, and bacterial growth inhibition. Also, antibacterial action of LGFEO was conducted on key enzymes of respiratory metabolic (glycolysis, oxidative pentose phosphate pathway, tricarboxylic acid cycle, and respiratory chain), and the levels of intracellular ATP, ADP, nicotinamide adenine dinucleotide (NAD + and NADH), nicotinamide adenine dinucleotide phosphate (NADP + and NADPH), and oxidized and reduced glutathione (GSSG and GSH) in LGFEO-treated S. flexneri cells, indicating a role of LGFEO in repressing respiratory pathway and electron transport with low redox potential. All these revealed that LGFEO could effectively induce H 2 O 2 accumulation and lipid peroxidation, resulting in cell membrane damage and metabolic function disruption, giving rise to a disturbance of redox homeostasis, which may be the main cause of growth inhibition or cell death for S. flexneri . • Essential oil contains 70 volatile compounds with good antimicrobial activity. • The first time for antibacterial mechanism from energy and respiratory metabolism. • Antibacterial action of essential oil involves in H2O2-mediated oxidative stress. •Essential oil-induced disruption of redox homeostasis as main antibacterial action.

Selenofolate inhibits the proliferation of IGROV1 cancer cells independently from folate receptor alpha

Cancer is one of the main causes of human mortality worldwide and novel chemotherapeutics are required due to the limitations of conventional cancer therapies. For example, using redox selenium compounds as novel chemotherapeutics seem to be very promising. The objective of this study was to explore if folate could be used as a carrier to deliver a newly synthesised selenium derivative selenofolate into cancer cells. Particularly, the cytotoxic effects of this selenofolate compound were investigated in a variety of cancer cell types including lung, liver, and cervical cancers and specifically IGROV1 cells. Our results showed that selenofolate inhibits the growth of cancer cells in-vitro. However, despite the expectations, folate receptor alpha (FRα) was not involved in the transportation of selenofolate compound into the cells i.e. growth inhibition was independent of FRα, suggesting that multiple transporters (e.g. reduced folate carrier-1) are possibly involved in the delivery and internalisation of folate in IGROV1 cells. Additionally, selenofolate did not exert cell death through apoptosis. Instead, anti-proliferative activity showed to be the main cause of growth inhibition of selenolofate in the IGROV1 cell line. In conclusion, selenofolate inhibits the growth of cancer cells and thus, may be explored further as a potential chemotherapeutic agent.

Transcription factor BnaA9.WRKY47 contributes to the adaptation of Brassica napus to low boron stress by up-regulating the boric acid channel gene BnaA3.NIP5;1.

SummaryBoron (B) deficiency is one of the major causes of growth inhibition and yield reduction in Brassica napus (B. napus). However, the molecular mechanisms of low B adaptation in B. napus are largely unknown. Here, fifty‐one BnaWRKY transcription factors were identified as responsive to B deficiency in B. napus, in which BnaAn.WRKY26, BnaA9.WRKY47, BnaA1.WKRY53 and BnaCn.WRKY57 were tested in yeast one‐hybrid assays and showed strong binding activity with conserved sequences containing a W box in the promoters of the B transport‐related genes BnaNIP5;1s and BnaBOR1s. Green fluorescent protein fused to the target protein demonstrated the nuclear localization of BnaA9.WRKY47. CRISPR/Cas9‐mediated knockout lines of BnaA9.WRKY47 in B. napus had increased sensitivity to low B and lower contents of B than wild‐type plants. In contrast, overexpression of BnaA9.WRKY47 enhanced the adaptation to low B with higher B contents in tissues than in wild‐type plants. Consistent with the phenotypic response and B accumulation in these transgenic lines, the transcription activity of BnaA3.NIP5;1, a B efficiency candidate gene, was decreased in the knockout lines but was significantly increased in the overexpressing lines under low B conditions. Electrophoretic mobility shift assays, transient expression experiments in tobacco and in situ hybridizations showed that BnaA9.WRKY47 directly activated BnaA3.NIP5;1 expression through binding to the specific cis‐element. Taken together, our findings support BnaWRKYs as new participants in response to low B, and BnaA9.WRKY47 contributes to the adaptation of B. napus to B deficiency through up‐regulating BnaA3.NIP5;1 expression to facilitate efficient B uptake.

The Reason for Growth Inhibition of Ulmus pumila ‘Jinye’: Lower Resistance and Abnormal Development of Chloroplasts Slow Down the Accumulation of Energy

Ulmus pumila ‘Jinye’, the colorful leaf mutant of Ulmus pumila L., is widely used in landscaping. In common with most leaf color mutants, U. pumila ‘Jinye’ exhibits growth inhibition. In this study, U. pumila L. and U. pumila ‘Jinye’ were used to elucidate the reasons for growth inhibition at the physiological, cellular microstructural, and transcriptional levels. The results showed that the pigment (chlorophyll a, chlorophyll b, and carotenoids) content of U. pumila L. was higher than that of U. pumila ‘Jinye’, whereas U. pumila ‘Jinye’ had a higher proportion of carotenoids, which may be the cause of the yellow leaves. Examination of the cell microstructure and RNA sequencing analysis showed that the leaf color and growth inhibition were mainly due to the following reasons: first, there were differences in the structure of the thylakoid grana layer. U. pumila L. has a normal chloroplast structure and clear thylakoid grana slice layer structure, with ordered and compact thylakoids. However, U. pumila ‘Jinye’ exhibited the grana lamella stacking failures and fewer thylakoid grana slice layers. As the pigment carrier and the key location for photosynthesis, the close stacking of thylakoid grana could combine more chlorophyll and promote efficient electron transfer promoting the photosynthesis reaction. In addition, U. pumila ‘Jinye’ had a lower capacity for light energy absorption, transformation, and transportation, carbon dioxide (CO2) fixation, lipopolysaccharide biosynthesis, auxin synthesis, and protein transport. The genes related to respiration and starch consumption were higher than those of U. pumila L., which indicated less energy accumulation caused the growth inhibition of U. pumila ‘Jinye’. Finally, compared with U. pumila ‘Jinye’, the transcription of genes related to stress resistance all showed an upward trend in U. pumila L. That is to say, U. pumila L. had a greater ability to resist adversity, which could maintain the stability of the intracellular environment and maintain normal progress of physiological metabolism. However, U. pumila ‘Jinye’ was more susceptible to changes in the external environment, which affected normal physiological metabolism. This study provides evidence for the main cause of growth inhibition in U. pumila ‘Jinye’, information for future cultivation, and information on the mutation mechanism for the breeding of colored leaf trees.

Unique Responses of Hepatocellular Carcinoma and Cholangiocarcinoma Cell Lines toward Cantharidin and Norcantharidin.

The present study aimed to investigate whether cell lines from human gastric and liver cancers respond differently toward cantharidin (CTD) and norcantharidin (NCTD) than other types of cancer cells. We first established the half maximal inhibitory concentrations (IC50s) of CTD for a large panel of cancer cell lines representing the 12 major types of human cancers and the mode of cell death induced by the two compounds. We next compared the growth inhibitory effects as well as the corresponding modes of action of CTD and NCTD. The IncuCyte ZOOM system was used as a semi-high throughput means to define IC50s and 90% inhibitory doses (IC90s) as a reference for the maximal tolerable doses (MTDs) for the two compounds in 72 cancer cell lines. Classical clonogenic survival assay was used to assess the anti-proliferative effect of CTD on selected cell lines of interest. In addition, DNA content-based flow was used to interrogate the modes of cell death following CTD or NCTD exposure. The results of these experiments led to several findings. 1). Cell lines representing hepatocellular carcinomas (HCCs) and cholangiocarcinomas (CCs) were among the most sensitive toward CTD, consistent with the previous clinical study of this compound and its source of origin, Mylabris. 2). Among the individual cell lines of a given cancer types, the sensitivity trends for CTD and NCTD did not exhibit a good correlation. 3) CTD and NCTD caused distinctive cytotoxic effects on HepG2 cells. Specifically, while a cytostatic effect is the primary cause of growth inhibition of CTD, cytotoxic effect is the main contributing factor for the growth inhibition of NTCD. These results indicate that liver cancer cell lines are among the most sensitive to CTD and that CTD and NCTD exhibit their effects through distinct mechanisms.

Effects of Adlay Hull and Testa Ethanolic Extracts on the Growth of Uterine Leiomyoma Cells

Uterine leiomyoma has become a significant health concern affecting one in forth women in reproductive age in Taiwan, according to the Ministry of Health and Welfare. The associated symptoms can lead to reduced life quality and women ultimately seeking for surgical intervention. Adlay extract possesses anti-tumor activity and has shown to inhibit sarcoma cell proliferation and tumor progression. In present study, viability of ELT3 cells was tested to screen for different fractions of adlay extracts, as well as various phenolic compounds and flavonoids. The active adlay fractions and compounds were then tested on primary human leiomyoma cells. Cell cycle profiles of ELT3 cells were analyzed in order to determine the possible cause of growth-inhibition. Results showed that AHE-EA, ATE-Hex, and ATE-EA were able to inhibit the proliferation of ELT3 and primary leiomyoma cells. Among the tested compounds, Quercetin, nobiletin and eriodictyol, significantly decreased the viability of ELT3 and primary leiomyoma cells. Quercetin induced cell cycle arrest of ELT3 cells at Sub-G1 and G2/M phases. Adlay extracts exhibit growth-inhibitory effects on uterine leiomyoma cells. These effects may result from to the combined actions of different compounds, indicating a possibility of matrix effect from the compounds in adlay extract. Therefore, adlay extracts may be considered a feasible alternative therapeutic agent for leiomyoma.

Growth inhibition of fungus Phycomyces blakesleeanus by anion channel inhibitors anthracene-9-carboxylic and niflumic acid attained through decrease in cellular respiration and energy metabolites.

Increasing resistance of fungal strains to known fungicides has prompted identification of new candidates for fungicides among substances previously used for other purposes. We have tested the effects of known anion channel inhibitors anthracene-9-carboxylic acid (A9C) and niflumic acid (NFA) on growth, energy metabolism and anionic current of mycelium of fungus Phycomyces blakesleeanus. Both inhibitors significantly decreased growth and respiration of mycelium, but complete inhibition was only achieved by 100 and 500 µM NFA for growth and respiration, respectively. A9C had no effect on respiration of human NCI-H460 cell line and very little effect on cucumber root sprout clippings, which nominates this inhibitor for further investigation as a potential new fungicide. Effects of A9C and NFA on respiration of isolated mitochondria of P. blakesleeanus were significantly smaller, which indicates that their inhibitory effect on respiration of mycelium is indirect. NMR spectroscopy showed that both A9C and NFA decrease the levels of ATP and polyphosphates in the mycelium of P. blakesleeanus, but only A9C caused intracellular acidification. Outwardly rectifying, fast inactivating instantaneous anionic current (ORIC) was also reduced to 33±5 and 21±3 % of its pre-treatment size by A9C and NFA, respectively, but only in the absence of ATP. It can be assumed from our results that the regulation of ORIC is tightly linked to cellular energy metabolism in P. blakesleeanus, and the decrease in ATP and polyphosphate levels could be a direct cause of growth inhibition.

Biodeterioration of Premium Motor Spirit and Automotive Gas Oil by Bacterial and Fungal Deteriogens

The study of Biodeterioration of Premium Motor Spirit and Automotive Gas Oil by bacterial and fungal deteriogens was conducted to ascertain the level of spoilage on petroleum samples obtained from African Petroleum and Oando Filling Stations, Port Harcourt. The Spread plate technique was employed for the enumeration of the microorganisms. The samples were cultured on petri-dishes containing nutrient media and potato dextrose agar and were incubated at temperature of 28–31°C for 48 hours and 72 hours for bacterial and fungal growth respectively. The bacterial and fungal isolates were further tested for hydrocarbon utilization potential with a modified mineral salt agar at room temperature for 48 hours and 168 hours respectively. Results showed a high range of total viable counts of Bacterial and Fungal species in samples collected from the stations. Bacillus spp., Pseudomonas spp., Aspergillus spp., Penicillium spp. were isolated from Diesel samples; while Pseudomonas spp., Bacillus spp., yeast spp. and Aspergillus spp. were isolated from Petrol. The Petrol and Diesel distributed by the African Petroleum to customers is of a higher quality than that of Oando Filling Station. There was abundance of microbial growth at Diesel substrates and was least supported by Petrol. This may be as a result of heavy contamination of the samples when in the storage tanks underground. The lead, anti-knock additive (tetra-ethyl lead) in Petrol may be the cause of growth inhibition. It is therefore recommended that adequate control-spoilage measures should be taken in order to prevent bioattack of the petroleum products.

P0121 Inhibitory effect of adlay hull and testa ethanolic extracts on uterine leiomyoma cell proliferation

Background Uterine leiomyoma is a significant health problem. The associated symptoms can lead to reduced quality of life and women ultimately seek surgical intervention. Methods Adlay extract possesses anti-tumour activity and has shown to inhibit sarcoma cell proliferation and tumour progression. In the present study, viability of ELT3 cells was tested to screen for the different fractions of adlay extracts, as well as various phenolic compounds, flavonoids, phytosterols, and fatty acids. The active adlay fractions and compounds were then tested on primary human leiomyoma and myometrial smooth muscle cells. Cell cycle profiles of ELT3 cells were analysed to determine the possible cause of growth inhibition. Findings Results showed that AHE-EA, ATE-Hex, and ATE-EA were able to inhibit the proliferation of ELT3 and primary leiomyoma cells. Quercetin, nobiletin, eriodictyol, sitosterol, stigmasterol, and stigmastanol were among the tested compounds that significantly decreased the viability of ELT3 and primary leiomyoma cells, while linoleic acid only impeded primary leiomyoma cell growth. Eriodictyol and quercetin induced cell cycle arrest of ELT3 cells at sub-G1 and G2/M phases. Interpretation Adlay extract exhibits time-dependent and concentration-dependent growth-inhibitory effects on uterine leiomyoma cells. These effects could be caused by the combined actions of the different compounds, indicating the possibility of a matrix effect from the compounds in the adlay extract.

Intracellular nitrite accumulation: The cause of growth inhibition of Microcystis aeruginosa exposure to high nitrite level

SummaryThe aim of the present study is to test the role of intracellular nitrite in external nitrite suppressing algal growth. We examined the growth of Microcystis aeruginosa at different nitrite levels under high nitrate conditions and without nitrate conditions. There were higher intracellular nitrite and lower Pmchla, Rd chla, αchl, maximum cell density and specific growth rate in high nitrate group than nitrate absence group at 5 mg NO2−‐N L−1. At 10 and 15 mg NO2−‐N L−1, Pmchla, Rd chla, αchl, maximum cell densities and specific growth rates in the high nitrate group became higher than those of the nitrate absence group, while a lower intracellular nitrite in the high nitrate group than nitrate absence group was observed. In addition, the intracellular nitrite and the growth of M. aeruginosa in the high nitrate group did not change from 5 to 10 mg NO2−‐N L−1. In the nitrite uptake experiment, with nitrite concentration increasing from 5 to 15 mg NO2−‐N L−1, maximum nitrite uptake rate of alga increased, and half‐saturation constant of alga decreased. These results indicate that external nitrite inhibited algal growth through stimulating intracellular nitrite rise, which resulted from overexpression of nitrite transporter.

Targeting the Wnt/β-Catenin Signaling Pathway in Multiple Myeloma: A Possible New Therapeutic Approach to Overcome Bortezomib-Resistance

Multiple myeloma (MM) is a neoplasm of plasma cells that is often fatal, despite the use of high dose chemotherapy and hematopoietic stem cell transplantation. Although new therapeutic approaches, including novel agents such as thalidomide, lenalidomide, and bortezomib (a proteasome inhibitor), are now used clinically and have improved the outcome of patients with MM, most patients eventually relapse, and it remains an incurable disease.Wnt/β-catenin signaling plays a critical role in both cell proliferation and differentiation in normal tissue. β-catenin, a key player and downstream effector in canonical Wnt signaling, is involved in the regulation of cell fate, proliferation, and self renewal of stem cells. The activation of Wnt signaling is aberrantduring the pathogenesis of various malignant neoplasms, and it has been suggested that Wnt/β-catenin signaling is involved in the regulation of cancer stem cells. When the Wnt signaling pathway is activated, stabilized β-catenin translocates to the nucleus, where it interacts with T-cell factor, followed by transcription of target genes such as c-myc, cyclin D1 and survivin. Nuclear β-catenin also recruits the co-activator, cyclic AMP response element-binding protein (CBP), which is essential for hematopoietic cell proliferation and hematopoietic stem cell self renewal, or its related homolog p300, which is involved in hematopoietic cell differentiation. Recent studies have shown that CBP and p300 have distinct functions in the regulation of β-catenin expression: CBP promotes β-catenin expression, whereas p300 inhibits β-catenin expression. In the context of hematological malignancies, β-catenin is overexpressed in myeloma-derived cell lines and primary myeloma cells, whereas expression is very low in normal plasma cells. Myeloma cells are maintained by several growth factors and cytokines, including Wnt ligands secreted by stromal cells in the bone marrow. These data suggest that Wnt/β-catenin signaling contributes to the pathogenesis of MM and thus might be a promising target for the treatment of this incurable hematological malignancy. Moreover, it has been reported that CBP, rather than p300, plays an important role in the expression of apurinic endonuclease/redox factor-1, an important regulator of multidrug resistance, in retinoic acid-induced chemo-resistant myeloma cells, suggesting that CBP is involved in the acquisition of drug resistance. Taken together with the previous data, Wnt/β-catenin signaling, especially CBP, might be an attractive target for new therapeutic agents against MM. ICG-001, small-molecule inhibitor of the canonical Wnt signaling pathway, specifically binds to CBP, thereby disrupting CBP/β-catenin interaction. In the present study, we investigated the role of Wnt/β-catenin signaling in myeloma cells using ICG-001. MTS and trypan blue dye exclusion assays showed that ICG-001 inhibits the proliferation of U266, RPMI8226, and KMS myeloma cell lines in a dose- (0-15 μM) and time- (0-72 h) dependent manner. Assays for apoptotic cell death were performed to determine the cause of growth inhibition by ICG-001 and demonstrated that ICG-001 induced both early and late apoptosis in myeloma cells. To investigate the molecular mechanisms of ICG-001-induced cell death in myeloma cells, the expression of various cell-death associated proteins and down-stream molecules of Wnt/β-catenin signaling was examined. Western blotting analysis showed that ICG-001 arrested cell growth and induced apoptotic cell death in myeloma cells by reducing the expression of three β-catenin target molecules: survivin, cyclin D1, and c-Myc. We next examined the effects of ICG-001 on bortezomib (BTZ)-resistant MM cells. BTZ resistance is an urgent issue in clinics, and therapeutic approaches for overcoming BTZ resistance are important. Interestingly, ICG-001 inhibited the proliferation of both BTZ-sensitive wild-type KMS and BTZ-resistant KMS cells, suggesting that targeting CBP may overcome BTZ-resistance. Furthermore, when combined with cyclosporine, which inhibits non-canonical Wnt/β-catenin signaling, ICG-001 synergistically induced the growth arrest of myeloma cells by inducing apoptotic cell death. These results indicate that inhibition of Wnt/β-catenin signaling may be an attractive therapeutic option both for patients with newly diagnosed MM and for those in a refractory or relapsed state. DisclosuresNo relevant conflicts of interest to declare.

GROWTH INHIBITION CAUSED BY REUSED DRAINAGE WATER; QUEST FOR CAUSE AND MEASURING METHOD

Growth inhibition is often a reason for growers to refresh the recirculation water and to discharge the excess water. The cause of growth inhibition other than a high concentration of sodium or a disease is usually unclear. Objectives of the study were the determination of the cause of growth inhibition and the development of methods to determine growth inhibition in an early stage in the crop in situ without the use of more indirect bioassays. Potential growth inhibitory components in drain water of a rose cultivation have been investigated by means of stepped analysis in the crop, the substrate and in water. The course of the oxygen concentration in the root environment was monitored. The efficiency of photosynthetic light utilization had been measured with the aid of chlorophyll fluorescence on plant leaves in the crop. All the measurements were intended to determine a possible relationship between growth inhibition, photosynthesis and oxygen stress. The main results were: Water disinfec¬tion methods eliminated growth inhibition. Drainwater was filtered with filters of 0.2 and 0.45 µm. This resulted in a relative growth in the bioassay compared to untreated of 122% and 104%. Growth inhibition in water in the rose crop is probably caused by a microbiological factor with a bacterial origin. A mix of pesticides as used on com¬mercial nurseries has been tested with bioassays on cress seed. A 1, 10 and 100-fold concentration compared to the practical situation were tested. Pesticides in the drainage water in concentrations as used on commercial nurseries did not inhibit growth in the bioassays. Monitoring of the oxygen concentration in the water and root environment and the measurements of the light use efficiency showed no relationships with demonstrated growth inhibition. The value of these methods could not be assessed because growth inhibition was only found in conducted bioassays with drainage water and not in the crop.