Ecophysiological changes and spore formation: two strategies in response to low-temperature and high-light stress in Klebsormidium cf. flaccidum (Klebsormidiophyceae,Streptophyta)1

Members of the cosmopolitan streptophycean genus Klebsormidium live in various habitats, including sand dunes and polar/alpine environments. To survive in these harsh conditions they must possess an array of adaptive physiological and structural mechanisms, for example, to deal with chilling and photochilling stresses. Since these mechanisms have not been studied in detail, the objectives of this study were (i) to determine the physiological and biochemical responses of Klebsormidium cf. flaccidum (K. cf. flaccidum) to chilling (low temperature [LT]) and photochilling (LT in combination with high light [HL]) stresses; and (ii) to understand the cross-link between biochemical parameters and cellular ultrastructural changes. The results indicated that 5°C is a temperature threshold (i.e., at 5°C) but not at higher temperatures, physiological changes were observed (F_v/F_m and ETR decreased and energy-partitioning distribution changed, with an increase in Y[NPQ] under LT and an increase in Y[NO] under HL-LT). Also, pigment contents changed significantly, with increased concentrations of photoprotective pigments such as antheraxanthin, zeaxanthin, and total carotenes. All of these responses occurred under LT and, to a greater extent, under LT-HL, indicating that the two stresses (temperature and light) are additive. The cold treatment applied here induced the formation of spores under both LL and HL. The degree of photoinhibition was higher in spores than in vegetative cells, indicating that spores are less susceptible to photodamage. This study demonstrated a broad acclimation potential in different developmental stages of K. cf. flaccidum, which helps to explain the ecological success of this genus.     

黑玉米中黑色素的提取工艺及组分研究

以黑玉米为原料，对黑玉米中的黑色素的提取工艺进行了研究，通过正交实验得出了提取黑玉米中黑色素的最佳提取条件：95％的乙醇溶液、料液比1：30、pH=1、浸提时间45min；并利用液质联用技术（LC—MS）对山东和山西两种黑玉米中黑色素的种类进行了探讨。结果表明，山东中主要含有两种花青素，分别是矢车菊和天竺葵花色素；山西中主要含有三种花青素，分别是矢车菊、天竺葵和芍药花色素。     

Growth Inhibition of Various Organisms by a Violet Pigment,Nostocine A,Produced by Nostoc spongiaeforme

A freshwater filamentous cyanobacterium, Nostoc spongiaeforme TISTR 8169, produced and excreted a violet pigment, named nostocine A, in the culture medium. Nostocine A inhibited the growth of some typical strains of microorganisms, algae, cultured plants, and established animal cell lines.     

Extracellular vesicle-mediated long-range communication in stressed retinal pigment epithelial cell monolayers

Retinal pigment epithelium (RPE) alterations in age-related macular degeneration occur in patches, potentially involving long-distance communication between damaged and healthy areas. Communication along the epithelium might be mediated by extracellular vesicles (EVs). To test this hypothesis, EVs were collected from supernatants of polarized ARPE-19 and primary porcine RPE monolayers for functional and biochemical assays. EVs from oxidatively stressed donor cells reduced barrier function in recipient RPE monolayers when compared to control EVs. The effect on barrier function was dependent on EV uptake, which occurred rapidly with EVs from oxidatively stressed donor cells. Mass spectrometry-based proteomic analysis of EVs identified HDAC6, which is known to reduce tight junction stability. Activity assays confirmed the presence of HDAC6 in EVs, and EV transfer assays using HDAC6 inhibitors confirmed its effect in monolayers. These findings demonstrate that EVs can communicate stress messages to healthy RPE cells, potentially contributing to RPE dysfunction.     

Mutation of bacterium Vibrio gazogenes for selective preparation of colorants

A novel marine bacterium strain effectively produced prodiginine type pigments. These colorants could dye wool, silk and synthetic fabrics such as polyester and polyacrylic and also show antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria on the dyed products. Methyl nitrosoguanidine was used as a mutation agent to increase the genetic diversity and the production yield of the bacteria of the family of Vibrio gazogenes. The analysis of the mutated samples showed that two new main colorants as well as three previously found ones were produced. Liquid chromatography electro spray ionization mass spectrometry (LC‐ESI‐MS) and nuclear magnetic resonance (NMR) spectroscopic techniques were used to elucidate the structures of the newly produced colorants. Mass measurements revealed that the colorants C1, C2, C3, C4 have molecular masses of 321, 323, 351, and 295 Da. One unstable colorant C5 with molecular mass of 309 Da was detected as well. The mutated bacteria strains increased the yield of pigment production by about 81% and produced prodigiosin in 97% purity. The antibiotic activities of pure colorants are discussed as well. Based on their bio‐activity and excellent dyeing capabilities, these colorants could be employed in cosmetic and textile industries. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Utilization of hydroxypropyl cellulose and poly(acrylic acid)-hydroxypropyl cellulose composite as thickeners for textile printing

Trials were carried out to partially replace kerosene oil with hydroxypropyl cellulose (HPC), poly(acrylic acid)-hydroxypropyl cellulose composite (poly (AA)-HPC) and their mixture in pigment printing paste. Partial replacement was carried out under a variety of conditions. Variables studied include type and concentration of the aqueous thickening agent and type of pigment dyes. In addition to that, poly (AA)-HPC composite was tried to replace sodium alginate in reactive printing. The fastness properties, color strength and stiffness were measured for the reactive and pigment printed samples.     

Chloroquine inhibits human retina pigmented epithelial cell growth and microtubule nucleation by downregulating p150glued

Chloroquine (CQ) is an antimalaria drug that has been used in clinical practice for several decades. One serious complication of CQ treatment is the macular retinopathy caused by the disruption of the retinal pigmented epithelium, leading to vision loss. Little is known about how CQ affects retinal pigmented epithelium. In this study, we found that cell proliferation was reduced by CQ treatment in time and dose-dependent manners. No obvious cell death was detected; however, what was observed instead was G0/G1 arrest during which primary cilium started to grow in the presence of CQ. Pharmacological inhibition of primary cilium formation led to a reduction of cell viability suggesting that CQ-induced primary cilium protected cells from death. In addition to cell growth, with the CQ treatment the retina pigmented epithelium (RPE) cells less flattened with the spindle-like protrusion. When checking the microtubule networks, the microtubule nucleation activity was disrupted in the presence of CQ. The level of p150 ^glued, the largest subunit of dynactin, was reduced in CQ-treated RPE1 cells, and depletion of p150 ^glued resulted in a phenotype reminiscent of CQ-treated cells. Thus, CQ treatment reduced the expression of p150 ^glued, leading to reduced S phase entry and defective microtubule nucleation.     

Retinal pigment epithelium-derived transforming growth factor-β2 inhibits the angiogenic response of endothelial cells by decreasing vascular endothelial growth factor receptor-2 expression

Transforming growth factor-β (TGF-β) is a multifunctional cytokine that is known to modulate various aspects of endothelial cell (EC) biology. Retinal pigment epithelium (RPE) is important for regulating angiogenesis of choriocapillaris and one of the main cell sources of TGF-β secretion, particularly TGF-β2. However, it is largely unclear whether and how TGF-β2 affects angiogenic responses of ECs. In the current study, we demonstrated that TGF-β2 reduces vascular endothelial growth factor receptor-2 (VEGFR-2) expression in ECs and thereby inhibits vascular endothelial growth factor (VEGF) signaling and VEGF-induced angiogenic responses such as EC migration and tube formation. We also demonstrated that the reduction of VEGFR-2 expression by TGF-β2 is due to the suppression of JNK signaling. In coculture of RPE cells and ECs, RPE cells decreased VEGFR-2 levels in ECs and EC migration. In addition, we showed that TGF-β2 derived from RPE cells is involved in the reduction of VEGFR-2 expression and inhibition of EC migration. These results suggest that TGF-β2 plays an important role in inhibiting the angiogenic responses of ECs during the interaction between RPE cells and ECs and that angiogenic responses of ECs may be amplified by a decrease in TGF-β2 expression in RPE cells under pathologic conditions.     

RPE-secreted factors: influence differentiation in human retinal cell line in dose- and density-dependent manner

Retinal pigment epithelial (RPE) cells play an important role in normal functioning of retina and photoreceptors, and some retinal degenerations arise due to malfunctioning RPE. Retinal pigment epithelium transplantation is being explored as a strategy to rescue degenerating photoreceptors in diseases such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP). Additionally, RPE-secreted factors could rescue degenerating photoreceptors by prolonging survival or by their ability to differentiate and give rise to photoreceptors by transdifferentiation. In this study, we have explored what role cell density could play in differentiation induced in a human retinal progenitor cell line, in response to RPE-secreted growth factors. Retinal progenitors plated at low (1 × 10⁴ cells/cm²), medium (2–4 × 10⁴ cells/cm²), and high (1 × 10⁵ cells/cm²) cell density were exposed to various dilutions of RPE-conditioned medium (secreted factors) under conditions of defined medium culture. Progenitor cell differentiation was monitored phenotypically (morphological, biochemical analysis, and immunophenotyping, and western blot analysis were performed). Our data show that differentiation in response to RPE-secreted factors is modulated by cell density and dilutions of conditioned medium. We conclude that before embarking on RPE transplantation as a modality for treatment of RP and AMD, one will have to determine the role that cell density and inhibitory and stimulatory neurotrophins secreted by RPE could play in the efficacy of survival of transplants. We report that RPE-conditioned medium enhances neuronal phenotype (photoreceptors, bipolars) at the lowest cell density in the absence of cell–cell contact. Eighty percent to 90% of progenitor cells differentiate into photoreceptors and bipolars at 50% concentration of conditioned medium, while exposure to 100% conditioned medium might increase multipolar neurons (ganglionic and amacrine phenotypes) to a small degree. However, no clear-cut pattern of differentiation in response to RPE-secreted factors is noted at higher cell densities.     

暗盘孢属YM421黑色素稳定性及其抗氧化活性

对暗盘菌Plectania sp.YM421菌株所产黑色素的稳定性及其抗氧化活性进行了研究。结果表明:该黑色素易溶于氢氧化钠溶液和二甲亚砜,微溶于蒸馏水,不溶于盐酸、无水乙醇、乙酸乙酯、氯仿、二甲苯、丙酮和乙醚;该黑色素在pH≥6时稳定,pH≤5时产生沉淀;对室光、日光、紫外光、亚硫酸钠、Na+和K+稳定;添加苯甲酸钠、柠檬酸钠、蔗糖、葡萄糖、乳糖、麦芽糖对黑色素有增色或护色作用;而双氧水、柠檬酸、VitC、Mg2+、Cu2+、Zn2+、Ca2+、Fe3+、Al3+降低其稳定性;该黑色素与VitC还原能力的EC50值(吸光度为0.5时的浓度)分别为169.6μg/mL和31.88μg/mL,对羟基清除作用的IC50值(清除率为50%时的浓度)分别为360.4μg/mL和183μg/mL。作为一种新型的天然色素,YM421黑色素有望应用于食品、化妆品以及医药等行业。