Effects Of Low Concentrations Research Articles

Abstract C021: Fucoxanthin anti-tumor effects on the proliferation, angiogenesis, apoptosis, and migration of triple-negative breast cancer cells

Abstract Breast cancer is the most commonly occurring cancer in women worldwide and is the second most common cancer among women in the United States. Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer and accounts for about 10-15% of all breast cancers. TNBC is mainly found in Caucasian and African American women. The tumor microenvironment promotes tumor initiation and progression, preceding invasive metastasis, increased cell growth, and angiogenesis. Therefore, the inhibition of these processes may reduce breast cancer development. Several dietary natural products show the ability to ameliorate the aggressiveness of breast cancer, leading to the inhibition of proliferation and angiogenesis, induction of apoptosis, and reduction of breast cancer progression and tumor development. PURPOSE: In the current study, the pharmacological effect of the natural compound fucoxanthin, a xanthophyll subset of carotenoids in brown macroalgae, is investigated in genetically different MDA-MB-231 (Caucasian) and MDA-MB-468 (African American) TNBC cell lines. METHODS: Cytotoxic and cell growth assays, angiogenic arrays, RT-PCR, apoptotic, and migration assays were performed. RESULTS: Fucoxanthin (1.56 - 300 µM) decreased cell viability in a dose and time-response manner in both cell lines, showing a higher potency in MDA-MB-468 cells. Fucoxanthin presented anti-proliferative effects in lower concentrations in MDA-MB-468 compared to MDA-MB-231 cells after 48 h and 72 h. Angiogenesis studies showed that fucoxanthin (6.25 µM) downregulates VEGF-A and VEGF-C expression in TNF-α-stimulated (50 ng/ml) MDA-MB-231 cells, but not in MDA-MB-468 cells in the transcription and protein levels. Fucoxanthin induced apoptosis in MDA-MB-231 cells but did not affect MDA-MB-468 cells. Additionally, fucoxanthin inhibited migration and invasion in both cell lines, showing a higher percentage of the inhibition of migrated cells in MDA-MB-468 cells after 72 h. CONCLUSION: Fucoxanthin may be a promising candidate for breast cancer therapy by targeting VEGF-A, and VEGF-C, decreasing cell proliferation, inducing apoptosis, and inhibiting cell migration and invasion. Citation Format: Shade' Ahmed, Patricia Mendonca, Samia Messeha, Ramesh Badisa, Karam F. Soliman. Fucoxanthin anti-tumor effects on the proliferation, angiogenesis, apoptosis, and migration of triple-negative breast cancer cells [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C021.

СРАВНИТЕЛЬНАЯ ЭФФЕКТИВНОСТЬ КОНСЕРВАНТОВ ДЛЯ ЖИДКИХ ВИТАМИННО-МИНЕРАЛЬНЫХ КОРМОВЫХ ДОБАВОК ACTIVE MIX VMG 500/600 И ACTIVE MIX VM 10/20

The article discusses the effectiveness of the use of potassium sorbate and a mixture of formic and propionic acids as preservatives for liquid vitamin and mineral feed additives. Preservatives must meet the following requirements: 1) do not cause the formation of insoluble products when interacting with other components of feed additives; 2) be soluble at the pH values that the feed additive has; 3) effectively suppress the growth of microorganisms and ensure long-term storage of the feed additive. Liquid feed additives Active Mix VMG-500, Active Mix VMG-600, Active Mix VM 10 and Active Mix VM 20 were used, to which these preservatives were added in concentrations from 0.05 % to 0.8 %. When adding a mixture of formic and propionic acids, the pH was adjusted (by adding NaOH) to the desired values (for Active Mix VMG-500 and VM 10, pH = 6.2, and for Active Mix VMG-600 and VM 20, pH = 3.2). At the same time, their salts were formed. It was found that potassium sorbate is incompatible with Active Mix VMG-600 and VM 20, but can be applied to Active Mix VMG-500 and VM 10. A mixture of formic and propionic acids (or rather, their salts) turned out to be chemically compatible with all of these feed additives. The effect of these preservatives on laboratory strains of St. aureus, B. subtilis and E. coli was studied. It was found that a mixture of formic and propionic acids has a bacteriostatic and bactericidal effect in lower concentrations compared to potassium sorbate. The storage periods of feed additives in non-sterile containers at room temperature and at +37 °C and the addition of a mixture of formic and propionic acids in concentrations from 0.2 to 0.7 % were estimated. At a concentration of 0.5 %, there were no signs of microbial growth during the year.

Anticancer effects of the Xanthophyll Fucoxanthin on Genetically Different Triple‐Negative Breast Cancer Cells

Breast cancer is the second most diagnosed cause of death in women worldwide compared to other cancer types. Triple‐negative breast cancer (TNBC) is the most aggressive subtype, constituting 15% of diagnosed breast cancers and predominantly found in African American and Caucasian Women. The tumor microenvironment is associated with increased angiogenesis, cell growth, invasive metastasis, and tumor growth progression. Many natural products have been reported to inhibit angiogenesis and slow breast cancer progression. The cytotoxic effect of the natural compound fucoxanthin, a xanthophyll found in the chloroplasts of brown macroalgae, is investigated. Fucoxanthin has been shown to induce G1 cell‐cycle arrest and apoptosis in various cancer cell lines. Here we show that fucoxanthin affects proliferation and angiogenesis in MDA‐MB‐231 (Caucasian) and MDA‐MB‐468 (African American) TNBC cell lines, which are genetically different. The results demonstrate that fucoxanthin induces a decrease in cell viability (concentration range: 1.56 ‐ 300 µM) in a dose‐response manner in MDA‐MB‐231 and MDA‐MB‐468 cells, showing a higher potency in MDA‐MB‐468 cells compared to MDA‐MB‐231 cells after 24h. Fucoxanthin also showed anti‐proliferative effects in lower concentrations in MDA‐MB‐468 cells compared to MDA‐MB‐231 cells after 48h and 72h. Moreover, angiogenesis studies showed that fucoxanthin (6.25 µM) downregulates the expression of VEGF‐A and VEGF‐C in TNF‐α‐stimulated (50 ng/ml) MDA‐MB‐231 cells, but not in MDA‐MB‐468 cells. The findings show that fucoxanthin may be a promising candidate for breast cancer therapy by targeting VEGF‐A, VEGF‐C, and reducing cell proliferation. Also, the data obtained provide evidence that genetically different cells may respond differently to fucoxanthin treatment.

The inhibitory effects of butein on cell proliferation and TNF-α-induced CCL2 release in racially different triple negative breast cancer cells.

Drug resistance is the leading cause of breast cancer-related mortality in women, and triple negative breast cancer (TNBC) is the most aggressive subtype, affecting African American women more aggressively compared to Caucasians women. Of all cancer-related deaths, 15 to 20% are associated with inflammation, where proinflammatory cytokines have been implicated in the tumorigenesis process. The current study investigated the effects of the polyphenolic compound butein (2′,3,4,4′-tetrahydroxychalcone) on cell proliferation and survival, as well as its modulatory effect on the release of proinflammatory cytokines in MDA-MB-231 (Caucasian) and MDA-MB-468 (African American) TNBC cell. The results obtained showed that butein decreased cell viability in a time and dose-dependent manner, and after 72-h of treatment, the cell proliferation rate was reduced in both cell lines. In addition, butein was found to have higher potency in MDA-MB-468, exhibiting anti-proliferative effects in lower concentrations. Apoptosis assays demonstrated that butein (50 μM) increased apoptotic cells in MDA MB-468, showing 60% of the analyzed cells in the apoptotic phase, compared to 20% in MDA-MB-231 cells. Additionally, butein downregulated both protein and mRNA expression of the proinflammatory cytokine, CCL2, and IKBKE in TNFα-activated Caucasian cells, but not in African Americans. This study demonstrates butein potential in cancer cell suppression showing a higher cytotoxic, anti-proliferative, and apoptotic effects in African Americans, compared to Caucasians TNBC cells. It also reveals the butein inhibitory effect on CCL2 expression with a possible association with IKBKE downregulation in MDA-MB-231 cells only, indicating that Caucasians and African Americans TNBC cells respond differently to butein treatment. The obtained findings may provide an explanation regarding the poor therapeutic response in African American patients with advanced TNBC.

In vitro cytotoxic and genotoxic effects of newly synthesised boron ionic liquids

In this study, new molecules containing boron were added to the family of ionic organic compounds, in particular, ionic liquids with a cationic center. This study aimed to determine the cytotoxic and genetic effects of a total of four newly synthesised borenium and borinium compounds on human peripheral lymphocytes in vitro. Human peripheral lymphocytes were obtained from heparinised blood samples collected from healthy females aged between 29 and 32 years, with no history of exposure to toxic agents. The cytotoxicity was assayed via the MTT (3-(4.5-dimethylthiazole- 2-yl)-2.5-diphenyltetrazolium-bromide) and LDH (lactate dehydrogenase) tests; the genotoxicity and cytotoxicity, via the micronucleus (MN) and sister chromatid exchange (SCE) tests. The results showed that the borenium compounds did not exhibit cytotoxic activity in the MTT and LDH tests even in high concentrations, the borinium compound did not exhibit cytotoxic effects in lower concentrations in vitro. The borenium compounds did not show genotoxic effects in SCE and MN tests. However, at a high concentration, borinium increased the micronucleus rate in comparison to the negative control group. The obtained results suggest that these newly synthesised cationic boron compounds can be used reliably in health, cosmetics or other industries, taking into consideration their types and concentrations.

Using the Apolipoprotein E Knock-Out Mouse Model to Define Atherosclerotic Plaque Changes Induced by Low Dose Arsenic.

Arsenic exposure increases the risk of atherosclerosis, the gradual occlusion of the large arteries with fibro-fatty plaque. While epidemiologic data provide convincing evidence this is true at higher exposures, it is unclear whether this may occur at low arsenic exposures, near the maximum contaminant level of 10 ppb. We have previously shown that 200 ppb arsenite in the drinking water increased the atherosclerosis in apolipoprotein E knock-out (apoE-/-) mice after 13 weeks, but the effects of lower concentrations were unknown. Therefore, here, we analyzed the effects of oral exposure to arsenite from 10 to 200 ppb after 13 weeks. Importantly, we found that even at the lowest concentration of arsenite, there was a significant increase in atherosclerotic plaque size. In our previous studies, we found that arsenite exposure resulted in decreased smooth muscle cells (SMCs) and collagen within the plaque. This change is indicative of a less stable phenotype that could increase the risk of rupture and subsequently, myocardial infarct or stroke in humans. In addition, we observed that lipid increased within the plaque without concomitant increase in macrophage content, suggesting that the macrophages were retaining more lipid intracellularly. We also assessed these plaque components in apoE-/- mice exposed to 10-200 ppb arsenite. Interestingly, we observed that macrophage lipid accumulation occurred at lower concentrations than the decreased SMC/collagen content. Together these data suggest that in the apoE-/- model, low arsenite concentrations are pro-atherogenic and that macrophage lipid homeostasis is more sensitive to arsenite-induced perturbation than the SMCs.

Thermoelectric properties of lower concentration K-doped Ca3Co4O9 ceramics**Project supported by the National Key R&D Program of China (Grant No. 2016YFB0601101) and the National Natural Science Foundation of China (Grant No. 51476173).

The tuning of electron and phonon by ion doping is an effective method of improving the performances of thermoelectric materials. A series of lower concentration K-doped Ca3−xKxCo4O9 (x = 0, 0.05, 0.10, 0.15) polycrystalline ceramic samples are prepared by combining citrate acid sol-gel method with cold-pressing sintering method. The single-phase compositions and plate-like grain morphologies of all samples are confirmed by x-ray diffraction and field emission scanning electron microscope. The effects of lower concentration K doping on the thermoelectric properties of the material are evaluated systematically at high temperatures (300–1026 K). Low concentration K doping causes electrical conductivity to increase up to 23% with little effect on the Seebeck coefficient. Simultaneously, the thermal conductivity of K-doped sample is lower than that of the undoped sample, and the total thermal conductivity reaches a minimum value of approximately , which may be suppressed mainly by the phonon thermal conduction confinement. The dimensionless figure-of-merit ZT of Ca2.95K0.05Co4O9 is close to 0.22 at 1026 K, representing an improvement of about 36% compared with that of Ca3Co4O9, suggesting that lower concentration K-doped Ca3Co4O9 series materials are promising thermoelectric oxides for high-temperature applications.

Experimental and theoretical investigation on the effects of lower concentration CeO2/water nanofluid in flat-plate solar collector

Heat transfer characteristics of solar flat-plate collectors are improved by applying various nanofluids as the heat transfer media nowadays. In the present work, the theoretical and experimental analysis was performed for a flat-plate solar collector operating with water and CeO2/water nanofluid as the working fluids. The flat-plate solar water heater with 100 L per day capacity along with ladder-type heat exchanger having collector area of 2 m2 is fabricated for the experimental study. The average particle size and volume fraction of nanofluids were considered as 25 nm and 0.01%, respectively. The flow rate of water and nanofluid was varied from 1 to 3 lpm, and the efficiency was calculated as per ASHRAE standards. Due to the enhanced thermophysical properties of the nanofluid, it gives better performance and results showing that the maximum efficiency of solar water heater with CeO2/water nanofluid is 78.2%, which is 21.5% higher when compared with the water as base fluid. Also a correlation was developed for predicting the outlet temperature of a flat-plate collector. The maximum collector efficiency of nanofluid was obtained at the optimum mass flow rate of 2 lpm in experimental study. The developed mathematical model was reasonably matching the experimental results with the error of ± 7.5%.

Antiparasitic activity of 1,3-dioxolanes containing tellurium in Trichomonas vaginalis

The increased prevalence of metronidazole-resistant infections has resulted in a search for alternative drugs for the treatment of trichomoniasis. In the present study, we report the preparation and in vitro activity of three 1,3-dioxolanes that contain tellurium (PTeDOX 01, PTeDOX 02, and PTeDOX 03) against Trichomonas vaginalis. Six concentrations of these compounds were analyzed for in vitro activity against ATCC 30236 isolate of T. vaginalis. PTeDOX 01 reported a cytotoxic effect against 100% of T. vaginalis trophozoites at a final concentration of 90μM with an IC50 of 60μM. The kinetic growth curve of trophozoites indicated that PTeDOX 01 reduced the growth by 22% at a concentration of 90μM after an exposure of 12h, and induced complete parasite death at 24h. It induced cytotoxicity of 44% at 90μM concentration but and had no effect in lower concentrations in a culture of CHO-K1 cells. These results confirmed that PTeDOX 01 is an important drug for the treatment of T. vaginalis, and should be evaluated in other infectious agents as well.

Encapsulation of curcumin in polyelectrolyte nanocapsules and their neuroprotective activity

Poor water solubility and low bioavailability of lipophilic drugs can be potentially improved with the use of delivery systems. In this study, encapsulation of nanoemulsion droplets was utilized to prepare curcumin nanocarriers. Nanosize droplets containing the drug were encapsulated in polyelectrolyte shells formed by the layer-by-layer (LbL) adsorption of biocompatible polyelectrolytes: poly-L-lysine (PLL) and poly-L-glutamic acid (PGA). The size of synthesized nanocapsules was around 100 nm. Their biocompatibility and neuroprotective effects were evaluated on the SH-SY5Y human neuroblastoma cell line using cell viability/toxicity assays (MTT reduction, LDH release). Statistically significant toxic effect was clearly observed for PLL coated nanocapsules (reduction in cell viability about 20%–60%), while nanocapsules with PLL/PGA coating did not evoke any detrimental effects on SH-SY5Y cells. Curcumin encapsulated in PLL/PGA showed similar neuroprotective activity against hydrogen peroxide (H2O2)-induced cell damage, as did 5 μM curcumin pre-dissolved in DMSO (about 16% of protection). Determination of concentration of curcumin in cell lysate confirmed that curcumin in nanocapsules has cell protective effect in lower concentrations (at least 20 times) than when given alone. Intracellular mechanisms of encapsulated curcumin-mediated protection engaged the prevention of the H2O2-induced decrease in mitochondrial membrane potential (MMP) but did not attenuate Reactive Oxygen Species (ROS) formation. The obtained results indicate the utility of PLL/PGA shell nanocapsules as a promising, alternative way of curcumin delivery for neuroprotective purposes with improved efficiency and reduced toxicity.

Effects of seed and vegetative stage cysteine treatments on oxidative stress response molecules and enzymes in Ocimum basilicum L. under cobalt stress

Abstract In this research, the effects of seed and vegetative stage cysteine treatments on the oxidative stress response of molecules and enzymes in Ocimum basilicum L. under cobalt stress were studied. Parameters such as proline content, lipid peroxidation, leaf protein content, ascorbate peroxidase, catalase, phenylalanine ammonia-lyase and polyphenoloxidase activity were measured. Research was conducted in two separate trials including seed treatment and the treatment of plant at vegetative stage. In both cases, cobalt treatment was done in vegetative stage. Concentrations of 0, 0.5 and 2.5 mM cysteine and 0, 100 and 500 µM cobalt were used. Higher concentrations of cobalt increased MDA, other aldehydes, proline content and activity of CAT, APX, and PPO compared with the control (without cobalt and cysteine). Cobalt stress decreased leaf protein content compared with the control. Seed treatment with cysteine reduced the MDA, other aldehydes, proline, leaf protein content and APX activity of plants compared to plant treated with cobalt and without cysteine. Plant treatment with cysteine at vegetative stage caused an increase in leaf protein and a decrease in MDA, other aldehydes, proline, content and activity of CAT, APX and PPO. The results showed that seed treatment with cysteine could alleviate cobalt stress effects in lower concentrations while cysteine applied in vegetative stage was more effective at higher concentrations of cobalt. Based on these results probably cysteine due to protection of membrane decreased oxidative stress created by cobalt treatment.

Evaluation of Putative Anti-cryptosporidial Drugs in an in vitro Culture System

Cryptosporidium species are major pathogens severely affecting the health of neonate animals, in particular calves, but also cause life-threatening infection of immunocompromised humans. Currently, only halofuginone is approved for prophylactic and metaphylactic treatment of calves but this drug suffers from its limited safety margins. For treatment of immunodeficient human patients, only nitazoxanide and paramomycin are used but data regarding their efficacy are controversial. Aim of the present study was to test a substituted benzimidazole (BAY-AF76184) and a heterocyclic substituted 1,2,4-triazin (BAY-AB24992), both drugs with known anti-protozoal activity, for their potential ability to interfere with Cryptosporidium parvum development in vitro. Development of C. parvum in HCT-8 cells treated with these compounds was compared to negative controls and parasites treated with paromomycin or halofuginone using real-time PCR targeting the 18S rDNAs of parasites and host cells as template. Potential cytotoxic and anti-proliferative effects of drugs were analysed using a lactate dehydrogenase and a WST-1 assay, respectively. BAY-AF76184 and paromomycin dose-dependently inhibited development of C. parvum with EC50 values of 2.37 μM and 69.5 μM, respectively. Although high concentrations of halofuginone and BAY-AB24992 also significantly inhibited parasite development, effects of lower concentrations were very heterogeneous preventing calculation of EC50 values. Halofuginone and BAY-AF76184 dose-dependently interfered with host cell proliferation (EC50 values of 0.35 μM and 9.07 μM, respectively) and the latter also had direct cytotoxic effects (EC50=48.78 μM). However, drug concentrations required for cytopathic were higher than those for effects against C. parvum. Therefore, both BAY-AB24992 and BAY-AF76184 should be considered for further evaluation, e.g. using in vivo models.

Differential responses of hydrogen peroxide, lipid peroxidation and antioxidant enzymes in Azolla microphylla exposed to paraquat and nitric oxide

The present investigation was carried out to decipher the interplay between paraquat (PQ) and exogenously applied nitric oxide (NO) in Azolla microphylla. The addition of PQ (8 μM) increased the activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) by 1.7, 2.7, 3.9 and 1.9 folds respectively than that control in the fronds of Azolla. The amount of H2O2 was also enhanced by 2.7 times in the PQ treated plants than that of control. The supplementation of sodium nitroprusside (SNP) from 8–100 μM along with PQ, suppressed the activities of antioxidative enzymes and the amount of H2O2 compared to PQ alone. The drop in the activity of antioxidative enzymes — SOD, GPX, CAT and APX was highest (39.9%, 48.4%, 41.6% and 41.3% respectively) on the supplementation of 100 μM SNP with PQ treated fronds compared to PQ alone. The addition of NO scavengers along with NO donor in PQ treated fronds neutralized the effect of exogenously supplied NO. This indicates that NO can effectively protect Azolla against PQ toxicity by quenching reactive oxygen species. However, 200 μM of SNP reversed the protective effect of lower concentration of NO donor against herbicide toxicity. Our study clearly suggests that (i) SNP released NO can work both as cytoprotective and cytotoxic in concentration dependent manner and (ii) involvement of NO in protecting Azolla against PQ toxicity.

Anticancer Effects of the Nitric Oxide-Modified Saquinavir Derivative Saquinavir-NO against Multidrug-Resistant Cancer Cells

The human immunodeficiency virus (HIV) protease inhibitor saquinavir shows anticancer activity. Although its nitric oxide-modified derivative saquinavir-NO (saq-NO) was less toxic to normal cells, it exerted stronger inhibition of B16 melanoma growth in syngeneic C57BL/6 mice than saquinavir did. Saq-NO has been shown to block proliferation, upregulate p53 expression, and promote differentiation of C6 glioma and B16 cells. The anticancer activity of substances is frequently hampered by cancer cell chemoresistance mechanisms. Therefore, we here investigated the roles of p53 and the ATP-binding cassette (ABC) transporters P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), and breast cancer resistance protein 1 (BCRP1) in cancer cell sensitivity to saq-NO to get more information about the potential of saq-NO as anticancer drug. Saq-NO exerted anticancer effects in lower concentrations than saquinavir in a panel of human cancer cell lines. Neither p53 mutation or depletion nor expression of P-gp, MRP1, or BCRP1 affected anticancer activity of saq-NO or saquinavir. Moreover, saq-NO sensitized P-gp-, MRP1-, or BCRP1-expressing cancer cells to chemotherapy. Saq-NO induced enhanced sensitization of P-gp- or MRP1-expressing cancer cells to chemotherapy compared with saquinavir, whereas both substances similarly sensitized BCRP1-expressing cells. Washout kinetics and ABC transporter ATPase activities demonstrated that saq-NO is a substrate of P-gp as well as of MRP1. These data support the further investigation of saq-NO as an anticancer drug, especially in multidrug-resistant tumors.

Influence of preculture treatment and types of explants on shoot growth and in vitro flowering of feathered amaranth (Celosia argentea var. plumose)

The shoots developed from both the shoot tip and nodal explants of feathered amaranth (Celosia argentea var. plumosa—feathered cockscomb or plumed cockscomb) after 8 weeks of culture in the presence of either paclobutrazol or benzyladenine (BA) were shorter than those developed on basal Murashige and Skoog (MS) medium (Physiol Plant, 15:473–497, 1962) alone. However, this retarding effect was more pronounced in the nodal explant culture. Shoot tip explants from 2-week-old seedlings were more adversely affected by 0.85 or 1.7 μM paclobutrazol than those from older seedlings. In contrast, regardless of preculture duration investigated nodal explants did not exhibit different response to three different concentrations of paclobutazol. The response to 2.2 or 4.4 μM BA appeared to be largely independent of the age of the shoot tip explants or preculture treatment of nodal explants. Shoots developed from nodal explants produced a higher number of terminal inflorescence than those from shoot tip explants. Moreover, only lateral shoots from nodal explant culture formed inflorescence. Increased preculture duration on basal MS medium could generally lessen the inhibitory effect of lower concentrations of paclobutazol or BA on terminal or lateral inflorescence formation in nodal explant culture.

Screening botanical herbicide for invasive plant <I>Ipomoea cairica</I>

摘要: 本文报道了具有化感作用或潜在抑草活性的17种植物叶片水浸液对华南地区入侵杂草五爪金龙幼苗生长的化感作用，以期获得对五爪金龙有较强抑制作用的植物种类，为植物源除草剂的开发奠定基础。结果显示，17种供体植物中有12种能够抑制五爪金龙幼苗生长，抑制强度依次为假臭草〉飞机草〉黄帚橐吾〉艾蒿〉披针叶黄华〉微甘菊〉马缨丹〉鸡矢藤〉牧荆〉南美蟛蜞菊〉胜红蓟〉隆缘桉。且假臭草、艾蒿、飞机草、黄帚橐吾和披针叶黄华5种供体植物对五爪金龙的4项生长指标均产生显著或极显著影响，其中假臭草、飞机草、黄帚橐吾作用浓度较低，且资源丰富，可成为天然除草剂主要的资源植物。 关键词: 化感作用 / 入侵植物 / 五爪金龙 / 植物源除草剂

Physiological–biochemical properties of blue mussel Mytilus edulis adaptation to oil contamination

Bivalves have a known ability to accumulate different contaminants from ambient water and can therefore serve as bioindicators. The paper analyses certain biochemical and physiological parameters of blue mussels in response to varying oil product concentrations. The heart rate (HR) of blue mussels from the sublittoral zone exposed to different levels of oil products was investigated in a long-term experiment using non-invasive monitoring. A sharp rise in HR was observed at oil concentrations of 8.0 and 38.0 mg/l. A decreasing in mussel HR under the effect of lower concentrations (0.4 and 1.9 mg/l) was significant on the fourth day. Strong fluctuations of the cardiac activity were noted under all concentrations. After 6 days of oil treatment, tissues of the mussels were sampled to determine the total lipid composition. Low concentrations of oil products produced no reliable changes in the lipid composition whereas high concentrations induced significant changes in the ratio of lipid components (cholesterol and phospholipids).

Cooperative activity of multiple upper layer proteins for thalamocortical axon growth

During development, sensory thalamocortical (TC) axons grow into the neocortex and terminate primarily in layer 4. To study the molecular mechanism that underlies lamina-specific TC axon termination, we investigated the responsiveness of TC axons to ephrin-A5, semaphorin-7A (Sema7A) and kit ligand (KL), which are expressed in the upper layers of the developing cortex. Dissociated cells of the dorsal thalamus from embryonic rat brain were cultured on dishes that were coated with preclustered Fc-tagged extracellular domains of these molecules. Each protein was found to promote TC axon growth in a dose-dependent fashion of a bell-shaped curve. Any combination of the three proteins showed a cooperative effect in lower concentrations but not in higher concentrations, suggesting that their growth-promoting activities act in a common pathway. The effect of spatial distributions of these proteins was further tested on a filter membrane, in which these proteins were printed at a size that recapitulates the scale of laminar thickness in vivo, using a novel protein-printing technique, Simple-To-mAke Micropore Protein-Printing (STAMP2) method. The results demonstrated that TC axons grew massively on the laminin-coated region but were prevented from invading the adjacent ephrin-A5-printed region, suggesting that TC axons detect relative differences in the growth effect between these regions. Moreover, the inhibitory action of ephrin-A5 was enhanced by copresence with KL and Sema7A. Together, these results suggest that the lamina-specific TC axon targeting mechanism involves growth-inhibitory activity by multiple molecules in the upper layers and detection in the molecular environments between the upper and deep layers.

Microscopic, Biochemical and Physiological Assessment of the Effect of Methylene Bisthiocyanate on the Sapstain Fungus Ophiostoma floccosum

In vitro effects of methylene bisthiocyanate (MBT) on hyphal morphology and ultra-structure of Ophiostoma floccosum were examined using differential interference contrast, epifluorescence and transmission electron microscopy (TEM). To understand the mode of action of MBT, experiments were undertaken to measure potassium ion (K+) leakage from cells, oxygen consumption, glucose and ATP levels. Differential interference contrast microscopy indicated that MBT caused rapid changes in O. floccosum hyphae resulting in extensive vaculoation and accumulation of granular materials within the cytoplasm. Epifluorescence microscopy provided evidence that MBT treatment causes a loss in the permeability properties of the plasma membrane. TEM showed retraction of the plasma membrane from the cell wall, aggregation of cytoplasmic contents, vesiculation of membranous components, a dramatic increase in vacuolation, and eventually a complete loss in the integrity of organelles. There was a rapid efflux of intracellular K+ ions from cells, a substantial loss in K+ ions occurring within the first 5 min of MBT treatment. The rate of K+ leakage was MBT concentration treatment-time dependent. The study also showed that the effect of lower concentrations of MBT (0.01 and 0.1 mM) on respiratory activity was negligible. However, at the same concentrations, glucose consumption and ATP production were affected. Taken together, these observations suggest that the target site of MBT in O. floccosum alters membrane properties and uncouples oxidative phosphorylation from the respiratory chain.

Cardiac effects of oxytocin: Is there a role for this peptide in cardiovascular homeostasis?

Oxytocin is well known for its role in reproduction. However, evidence has emerged suggesting a role in cardiovascular and hydroelectrolytic homeostasis. Although its renal effects have been characterized, the cardiac ones have not been much studied. Therefore, we aimed to investigate the cardiac effects of oxytocin both in vivo and in vitro. In unanesthetized rats ( n = 6) intravenous oxytocin (1 μg) decreased d P / d t max by 15% ( P < 0.05) and heart rate by 20% ( P < 0.001), at the first minute after injection. d P / d t max was still lower in OT-treated rats than in controls ( n = 8) after 15 min ( P < 0.05), while heart rate returned to control values after 5 min. In isolated hearts, oxytocin was able to promote negative inotropic and chronotropic effects. Perfusion with 10 − 5 , 10 − 6 and 10 − 7 M oxytocin resulted in approximately 60% ( P < 0.01), 25% ( P < 0.01) and 10% ( P < 0.05) reduction of left ventricle developed pressure, without effect in lower concentrations (10 − 10 to 10 − 8 M). Also, d P / d t max was reduced by 45 and 20% (10 − 5 e 10 − 6 M; P < 0.01), while diastolic pressure raised and heart rate fell only with 10 - 5 M oxytocin ( P < 0.05). Intravenous oxytocin (1 μg; n = 6) increased arterial pressure by 22% at the first minute (+ 23 ± 3 mm Hg; P < 0.001), returning to control value thereafter. Thus, oxytocin is able to promote directly negative inotropic and chronotropic effects, but its in vivo effect also involves a reflex mechanism, originated from its pressor effect.