O2 supports 3-phosphoglycerate-dependent O2 evolution in chloroplasts from spinach leaves

We tested the hypothesis that the Mehler-ascorbate peroxidase (MAP) pathway supports 3-phosphoglycerate (PGA)-dependent oxygen (O₂) evolution using intact chloroplasts. Lowering O₂ concentration (<1?µM) suppressed PGA-dependent O₂ evolution rate. High O₂ concentration (about 250?µM) enhanced the electron fluxes in Photosystem II (PSII). Also, high O₂ concentration oxidized both Q_A in PSII and Cyt f in thylakoid membranes. These results indicated that the MAP pathway stimulated photosynthetic electron transport. Furthermore, electrochromic shift signal was also increased at high O₂ concentration, compared to low O₂ concentration. Non-photochemical quenching of chlorophyll fluorescence was also enhanced at high O₂ concentration. These data support our hypothesis that the MAP pathway functioned in intact chloroplasts and accelerated PGA-dependent O₂ evolution by inducing ΔpH formation to produce and supply adenosine triphosphate (ATP) to the conversion reaction of PGA to glyceraldehyde 3-phosphate through 1,3-diphosphoglycerate in chloroplasts.     

Effects of heating and illumination on trans-cis isomerization and degradation of beta-carotene and lutein in isolated spinach chloroplasts

The influence of thermal treatment and light exposure on degradation and isomerization of the predominant carotenoids (lutein and beta-carotene) occurring in green leafy vegetables was assessed. The effect of lipid addition on carotenoid stability was also evaluated. For the first time, the stabilities of pure carotenoids and chloroplast-bound carotenoids were compared. Besides degradation, heating caused carotenoid isomerization in all samples. Whereas pure carotenoids favor 13-cis isomers, in native chloroplasts and heated chloroplasts 9-cis isomers were predominant. Illumination of freshly prepared chloroplast isolates caused an initial increase in the level of lutein (9.6%) and beta-carotene (29.8%), while pure carotenoids exhibited time-dependent degradation. The addition of lipids to chloroplast preparations had the reverse effects on the retention of both carotenoids after heating; isomerization was not significantly affected. It was demonstrated that carotenoid stability has to be evaluated for every individual pigment in its genuine environment. Stability data based on model systems (e.g., pure carotenoids) may not be transferred to complex food matrices without intensive investigation.     

Triterpenoids isolated from Zizyphus jujuba inhibit foam cell formation in macrophages

Because foam cell formation in macrophages is believed to play an essential role in the progression of early atherosclerotic lesions in vivo, prevention of foam cell formation is considered to be one of the major targets for the treatment of atherosclerosis. The present study examined the inhibitory effect of 50 crude plant extracts on foam cell formation. Among those crude extracts, Zizyphi Fructus (ZF) and Zizyphi Semen (ZS) extracts significantly inhibited the foam cell formation induced by acetylated LDL. Furthermore, triterpenoids such as oleanonic acid, pomolic acid, and pomonic acid were the major active compounds, and triterpenoids containing a carboxylic acid at C-28 play an important role in the inhibitory effect on foam cell formation in human macrophages. These data suggest that triterpenoids in Zizyphus jujuba , the plant source of ZF and ZS, may therefore be useful for the prevention of atherosclerosis.     

Further evidence for the integrity of rice chloroplasts isolated in glutaraldehyde medium

Morphological aspects of rice chloroplasts isolated in glutaraldehyde and sucrose media were studied using the electron microscope. Chloroplasts in glutaraldehyde medium contained compact lamellae and densely stained stroma. On the other hand, chloroplasts in sucrose medium lacked stroma and consisted mostly of lamellae systems.     

Sesquiterpenoids isolated from the flower buds of Tussilago farfara L. inhibit diacylglycerol acyltransferase

Inhibition of acyl CoA:diacylglycerol acyltransferase (DGAT), which is a key enzyme in triglyceride synthesis in eukaryotic organisms, has been proposed as one of the drug targets for treating obesity, type II diabetes mellitus, and metabolic syndrome. Bioassay-guided fractionation of EtOH extract of the flower buds of Tussilago farfara , using an in vitro DGAT enzyme assay, resulted in the isolation of four known sesquiterpenoids, tussilagonone (1), tussilagone (2), 7beta-(3-ethyl-cis-crotonoyloxy)-1alpha-(2-methylbutyryloxy)-3,14-dehydro-Z-notonipetranone (3), and 8-angeloylxy-3,4-epoxy-bisabola-7(14),10-dien-2-one (4). DGAT1 inhibitory activity was studied by in vitro DGAT assay using rat liver microsomes and HepG2 cell microsomes. They showed DGAT1 inhibition with IC(50) values of 99.2 (1), 18.8 (2), 47.0 (3), and 211.1 (4) microM (for rat liver microsomes) and >1 mM (1), 49.1 (2), 160.7 (3), and 294.4 (4) microM (for HepG2 cell microsomes), respectively. Compound 2 showed the most potent inhibition against microsomal DGAT1 derived from rat liver and human hepatocellular carcinoma HepG2 cells and also significantly inhibited triglyceride synthesis by suppressing incorporation of [(14)C]acetate or [(14)C]glycerol into triglycerides in HepG2 cells. These findings suggest that tussilagone is a potential lead compound in the treatment of obesity and type 2 diabetes.     

Biflavonoids from Caper (Capparis spinosa L.) fruits and their effects in inhibiting NF-kappa B activation

Caper (Capparis spinosa L.) fruits have been widely used as food and folk medicine in the Mediterranean basin and in central and west Asia. In this study, two biflavonoids, isoginkgetin, and ginkgetin, together with three other flavonoids, were isolated from caper fruits. Their chemical structures were elucidated by spectroscopic analyses and comparison with literature. To our knowledge, isoginkgetin, ginkgetin and sakuranetin were identified in caper for the first time. Notably, it is also the first time that biflavonoids have ever been found in the Capparidaceae. Concentrations of the two biflavonoids were measured in caper fruits collected from four major growing areas in northwest China. The anti-inflammatory effects of the flavonoids from caper fruits were evaluated by secreted placental alkaline phosphatase (SEAP) reporter assay, which was designed to measure nuclear factor-kappa B (NF-κB) activation. Isoginkgetin and ginkgetin showed inhibitory effects in initial screen at 20 μM, while the effect of ginkgetin was much greater than that of isoginkgetin. In a dose-response experiment, the IC(50) value of ginkgetin was estimated at 7.5 μM, suggesting it could be a strong NF-κB inhibitor and worthy of study in vivo.     

Resveratrol oligomers isolated from Carex species inhibit growth of human colon tumorigenic cells mediated by cell cycle arrest

Research has shown that members of the Carex genus produce biologically active stilbenoids including resveratrol oligomers. This is of great interest to the nutraceutical industry given that resveratrol, a constituent of grape and red wine, has attracted immense research attention due to its potential human health benefits. In the current study, five resveratrol oligomers (isolated from Carex folliculata and Carex gynandra ), along with resveratrol, were evaluated for antiproliferative effects against human colon cancer (HCT-116, HT-29, Caco-2) and normal human colon (CCD-18Co) cells. The resveratrol oligomers included one dimer, two trimers, and two tetramers: pallidol (1); α-viniferin (2) and trans-miyabenol C (3); and kobophenols A (4) and B (5), respectively. Although not cytotoxic, the resveratrol oligomers (1-5), as well as resveratrol, inhibited growth of the human colon cancer cells. Among the six stilbenoids, α-viniferin (2) was most active against the colon cancer cells with IC(50) values of 6-32 μM (>2-fold compared to normal colon cells). Moreover, α-viniferin (at 20 μM) did not induce apoptosis but arrested cell cycle (in the S-phase) for the colon cancer but not the normal colon cells. This study adds to the growing body of knowledge supporting the anticancer effects of resveratrol and its oligomers. Furthermore, Carex species should be investigated for their nutraceutical potential given that they produce biologically active stilbenoids such as α-viniferin.     

昼间亚高温处理时期对日光温室番茄光合作用与产量的影响

在日光温室番茄第1花序第1花开花当天(处理1)及开花后10 d时(处理2)分别对植株进行昼间35℃亚高温处理,研究不同的35℃亚高温处理时期对番茄光合作用及产量的影响.结果表明:无论是处理1、处理2还是对照,番茄叶片净光合速率(Pn)的日变化均呈双峰曲线,即Pn均存在"午休"现象;但亚高温处理的植株午前和午后Pn的峰值均明显降低.处理1与处理2经5 d亚高温处理后,叶片Pn均明显降低;此后表现为亚高温处理的时期越早,Pn值越低,尤其是上部叶片.不同时期开始亚高温处理,叶片气孔导度(Gs)增大、气孔限制值(Ls)减小,处理时期早的,各指标与对照差异越明显.认为番茄叶片Pn的降低主要是由非气孔限制因素引起的.亚高温处理番茄光合作用降低,同化产物供应不足,处理1与处理2的坐果率均明显降低,最终产量分别下降65.43%、42.31%.认为番茄植株叶光合作用的减弱与产量降低有直接关系.     

Enzymatic and mechanistic studies on the formation of N-phenylglycolohydroxamic acid from nitrosobenzene and pyruvate in spinach leaf homogenate

The biotransformation mechanism of an unknown metabolite formed enzymatically from nitrosobenzene (NOB) and pyruvate in spinach (Spinacea oleracea L.) was investigated using spinach leaf homogenate. The unknown metabolite was identified as N-phenylglycolohydroxamic acid (PGA). The activity of PGA formation was decreased by l-alanine, increased by l-serine, and completely inhibited by aminooxyacetic acid, an inhibitor of transaminases. These results indicate that the transaminase participates in PGA formation. Indeed, hydroxypyruvate and alanine were produced in the transamination between pyruvate and serine. Hydroxypyruvate served as a direct-acting glycoloyl donor for PGA formation. A good correlation between the activities of the 200 g supernatant of spinach homogenate and commercial yeast transketolase for PGA formation from several glycoloyl donors was obtained. These results suggest the following mechanism for PGA formation from NOB and pyruvate: transamination of l-serine into hydroxypyruvate, which serves as a glycoloyl donor to NOB.     

菊花不同部位及根际土壤水浸液处理对光合作用的自毒作用研究

菊花[Dendranthema morifolium(Ramat)Tzvel.]的自毒作用是菊花连作障碍发生机理研究的重要内容之一.本文研究了连作障碍比较明显的菊花栽培种"高压太子"不同部位(枯落物、叶、茎和根系)及根际土壤水浸液处理对盆栽同种菊花光合作用的影响,结果表明:不同部位和根际土壤水浸液处理对叶片叶绿素含量、净光合速率及气孔导度均表现出抑制趋势,而暗呼吸速率却受到促进,尤以地上部水浸液的抑制作用为显著.说明降低自身叶绿素含量、净光合速率及气孔导度,即抑制自身的光合作用,同时促进自身暗呼吸是菊花自毒作用的机制之一.     

Procyanidin trimers to pentamers fractionated from apple inhibit melanogenesis in B16 mouse melanoma cells

The effects of apple polyphenols on melanogenesis in B16 mouse melanoma cells were investigated. The inhibitory effect of apple polyphenols was stronger than that of arbutin or kojic acid. Three polyphenol fractions (phenolic acid derivatives, procyanidins and other flavonoids) were isolated, and the procyanidins were fractionated according to the degree of polymerization using normal-phase chromatography. The procyanidin trimer-to-pentamer fractions were found to have the most pronounced effect on melanogenesis. Furthermore, each procyanidin fraction inhibited mushroom tyrosinase. No correlation between the degree of procyanidin polymerization and tyrosinase inhibitory activity was observed. Nevertheless, these observations suggest that procyanidins are effective inhibitors of tyrosinase.     

Mosquito-killing water molds isolated from soil samples collected in Taiwan

Mosquito-killing water molds were isolated from soils collected from various parts in Taiwan. The first-instar larvae of Aedes aegypti and Aedes albopictus were used as baits. A total of 453 soil samples were collected from Taipei, Ilan, Hualien, Taoyuan, Hsinchu, Miaoli, Taichung, Tainan, Nantou, Chiayi, Yunlin and Pintung. Four mosquito-killing Pythium spp. and one Saprolegnia sp. were isolated from the soil samples. Using zoospores of the Pythium spp. as inoculum to infect the first-instar larvae, scanning electron micrographs showed that most zoospores attached in the anal gill and a few attached between head and thorax. Thus, Pythium spp. is a potential biocontrol agent against first-instar larvae of A. aegypti and A. albopictus.     

Differentiation of rhizobia isolated from native legume trees in Uruguay

Legume trees are symbiotically associated with rhizobia and mycorrhizal fungi, microorganisms that improve their growth. The objective of this work was to characterize 61 rhizobial isolates from eight species of native legume trees: Acacia caven, Inga urugüensis, Lonchocarpus nitidus, Prosopis nigra, Sesbania virgata, Peltophorum dubium, Enterolobium contortisiliquum and Erythrina crista-galli. The strains were isolated from nodules with high nitrogenase activity and their growth rate, antibiotic, salinity and acidity resistances were determined. Their relationships were analyzed building a matrix with the resistance characteristics. Most of the isolates were fast growers and acid-producing with high level of exopolysaccharides. In general, isolates were erythromycin resistant but sensitive to rifampicin. All the isolates grew well at pH 5.5 while 75% did so at pH 4.4. More than 60% of the isolates grew in 2% of NaCl but this declined to 21% of the isolates in 3% NaCl. This population showed high antibiotic, salinity and pH resistance, suggesting adaptability to major ecological environment stresses, and great saprohytic competence within soil environments. Isolates from the same host showed high homology between them.     

Effect of cations on the growth of fluorescent pseudomonad isolates from spinach roots grown in soils with different salinity levels

Abstract

Effect of Inorganic ion concentrations in culture solution on the growth of Pseudomonas putida and P. fluorescens Isolates from spinach roots grown in soils with high-salinity (H-soil) and low-salinity (L-soil) levels was investigated. Both H- and L-soils were taken from the topsoil of a greenhouse for spinach cultivation and a nearby fallow field, respectively. In the H-soil inorganic ions had accumulated due to the high rates of application of fertilizer. Among the ions, the concentrations of Ca²⁺, NO₃ ^-, and SO₄ ^2- in the H-soil were significantly higher than those in the L-soil. Among the inorganic ions tested (K⁺, Na⁺, Ca²⁺, Mg²⁺, Cl^-, NO₃ ^-, and SO₄ ^2-), Ca²⁺ was found to be the most inhibitory on the growth of isolates. In addition, the isolates from the H-soil were more Ca²⁺-tolerant than those from the L-soil.

Consequents the growth tolerance to Ca²⁺ stress of the total 80 isolates, 40 each from the H-soil and L-soil, was compared at 150 mM Ca²⁺. Most isolates from the H-soil showed a significantly higher tolerance. The higher tolerance to Ca²⁺ of the isolates from the H-soil may have been acquired through selection under increasing Ca²⁺ stress in the field. The Ca²⁺ tolerance of the fluorescent pseudomonad strains may account for their survival and root-colonizing activity in soils with Ca²⁺ accumulation.     

Occurrence of 12-methyltridecanal in microorganisms and physiological samples isolated from beef

12-Methyltridecanal (MT) smelling tallowy, beef-like was formed from plasmalogens when beef was boiled. To clarify the origin of MT, its concentration was determined by a stable isotope dilution assay in bacteria and protozoa isolated from the rumen of bovine animals as well as in the plasma, erythrocytes, and other physiological samples. The highest amounts of MT were found in bacteria followed by protozoa. The MT content of the erythrocytes was small. The results support the hypothesis that microorganisms are the main source of MT of which a small amount is resorbed by the animal and transported to the muscular tissue where MT is incorporated into plasmalogens.     

Forms of phosphorus in bacteria and fungi isolated from two Australian soils

To understand the origin of organic and condensed forms of phosphorus (P) in soils, detailed information about P forms in microorganisms is required. We isolated 7 bacteria and 8 fungi from two Australian soils and analyzed the P forms in their pure cultures by extraction with NaOH-EDTA followed by ³¹P solution nuclear magnetic (NMR) spectroscopy. The bacteria belonged to the actinobacteria and the fungi to the ascomycota, as determined by rDNA sequencing. The proportions of broad forms of P were significantly different between the bacterial and fungal isolates (analysis of similarities, p = 0.001). Ortho-, pyro- and polyphosphate were present in higher proportions in fungi, while monoester and diester P were present in higher proportions in bacteria. Spectral deconvolution of the monoester region revealed 15 distinct resonances. The three major ones, which were identified by spiking experiments as glycerol 1-phosphate, glycerol 2-phosphate and adenosine-5′-monophosphate (AMP), comprised 56–74% of P in the monoester region. Ordination by principal component analysis and testing for treatment effects using analysis of similarities showed significant separation of P distribution in the monoester region between bacterial and fungal isolates (p = 0.007). However, neither group of microorganisms had a specific single P form which might be considered characteristic. As such, it may be difficult to distinguish soil P from bacterial or fungal origins, with the possible exception of a predominantly fungal origin of pyro- and polyphosphate. The identification of three major resonances in the monoester region of microorganisms is important, since the same resonances are found in ³¹P NMR spectra of soil extracts.     

Detection of R-plasmids in Salmonella isolated from clams and marine waters of Kuwait

A total of 24 strains of Salmonella isolated from clams and marine waters of Kuwait were speciated and investigated for drug resistance. Six of these were resistant to antibiotics. Their resistance patterns were ACT (4 isolates) and ACKST (2 isolates). These were examined for the transferability of their resistance. They had autotransferable R-plasmids and 25% of the transconjugants had an enbloc transfer at high frequency. The co-relation between Salmonella isolates from marine environment and clinical cases was established.     

Diversity and symbiotic effectiveness of rhizobia isolated from field-grown soybean nodules in Paraguay

Soybean was introduced in Paraguay in the 1920s and commercial crops have been grown since the 1970s. Root nodulation occurs at the majority of the producing sites, although inoculation has been practiced in only 15-20% of the cropping areas. The diversity and symbiotic effectiveness of soybean rhizobia was studied using 78 isolates obtained from root nodules of field-grown plants at 16 sites located in the two main producing states. The rhizobial isolates were characterized in relation to several parameters in vitro (colony morphology, tolerance to high temperature and salinity, intrinsic resistance to antibiotics, synthesis of indole acetic acid, profiles of proteins and lipopolysaccharides) and in vivo (nodulation, plant growth and total N accumulated in shoots). Fifty-eight isolates had slow growth rates and alkaline reaction in medium containing mannitol as the carbon source, whereas 20 had fast growth rates and an acid reaction. Most isolates did not tolerate acidity (pH 4.5) or high temperature (40°C). Very few isolates shared similar protein and lipopolysaccharide profiles; therefore a high level of diversity was detected, with most of the isolates representing unique strains. Some of the isolates with an outstanding symbiotic performance were identified, and will now be tested under field conditions in a search for efficient and competitive strains for use in commercial inoculants in Paraguay.     

Mesquite rhizobia isolated from the Sonoran Desert: Competitiveness and survival in soil

The competitiveness of a mesquite Rhizobium (AZ-M1) and its ability to survive in desert soils was compared to a selected commercial strain (31A5). In a greenhouse study, the native isolate out-competed strain 31A5 in nodule occupancy, when applied as a mixed inoculant to seed germinated and grown in sand culture, and irrigated with N-free nutrients. A high incidence of nodule double occupancy was found when double strain inoculants were used. The survival rate of the two strains was tested in three desert soils in a controlled laboratory study. The desert strain AZ-M1 grew and survived in all the soils for 1 month. The commercial strain 31A5, did not grow, and the population decreased in 14 days from 10⁸ cells g^?1 dry soil to below 10⁴ cells g^?1. Both strains survived to a lesser extent in a saline-sodic soil. A significant morphological change from a rod to a coccus was observed 2 days after strain 31A5 had been introduced into the desert soils.