猪前脂肪细胞诱导分化过程中PPARγ、DECR1和ECHS1基因表达模式

采用胶原酶消化法分离猪皮下前脂肪细胞,以含50 nmol/L胰岛素、100 nmol/L地塞米松、0.25 mmol/L 3-异丁基-1-甲基黄嘌呤、100 nmol/L罗格列酮的分化培养液对前脂肪细胞进行诱导分化,借助实时定量RT-PCR方法检测了PPARγ、DECR1和ECHS1 3基因的表达模式,结果发现:PPARγ、DECR1和ECHS1 3基因均于诱导分化后48 h达到表达高峰,此时的表达量分别是诱导前的93.0,5.4和7.8倍;PPARγ同DECR1和ECHS1两基因表达量变化趋势间的相关系数分别为0.92和0.97,DECR1同ECHS1的相关系数为0.94,均达到极显著相关(P<0.01)。实验结果表明:前脂肪细胞在分化过程中细胞内脂肪酸生物合成和脂肪酸β-氧化同时发生,以维持细胞的稳态。     

New clues concerning pigment biosynthesis in green colored fiber provided by proteomics-based analysis

To separate the proteins related to pigment synthesis in green colored fiber (GCF), we performed a comparative proteomic analysis to identify the differentially expressed proteins between green cotton fiber and a white near-isogenic line (NIL). One differential spot identified as phenylocumaran benzylic ether redutase-like protein (PCBER) was expressed only in GCF, but was not found in white colored fiber (WCF) at any time points. Since PCBER was a key enzyme in lignans biosynthesis, total lignans were extracted from GCF and WCF and their content was determined by using a chromotropic acid spectrophotometric method. The results showed that total lignans content in GCF was significantly higher than that in WCF. The qPCR analysis for two PLR genes associated with lignans biosynthesis showed that the expression level of two genes was much higher in GCF than that in WCF at 24 and 27 days post anthesis (DPA), which may be responsible for the higher lignans content in GCF. Our study suggested that PCBER and lignans may be responsible for the color difference between GCF and WCF. Additionally, p-dimethylaminocinnamaldehyde (DMACA) staining demonstrated that the pigment in GCF was not proanthocyanidins, and was different from that in brown colored fiber (BCF). This study provided new clues for uncovering the molecular mechanisms related to pigment biosynthesis in GCF.     

Antioxidant lignans sesamin and sesamolin in sesame (Sesamum indicum L.): A comprehensive review and future prospects

Sesame(Sesamum indicum L.) is a significantly lucrative cash crop for millions of small-holder farmers. Its seeds are an important source of a highly appreciated vegetable oil globally and two clinically essential antioxidant lignans, sesamin and sesamolin. Accordingly, many countries import millions of tons of sesame seed every year. The demand for lignan-rich sesame seeds has been increasing in recent years due to the continuous discovery of several pharmacological attributes of sesamin and se...     

太阳散射光对紫外分光光度法测定咖啡碱的影响

应用朗伯--比耳定律,利用排除法,确定太阳散射光对紫外分光光度法测定咖啡碱的影响.     

Chemical Composition of Green Tea (<Emphasis Type="Italic">Camellia sinensis</Emphasis>) Infusions Commercialized in Portugal

To evaluate the potential benefits and risks associated with tea consumption it is important to identify the constituents of this beverage. Levels of some minerals, caffeine and catechins in green tea samples commercialized in Portugal were evaluated. Potassium is the metal present in larger amount (92–151 mg/l). The content of sodium, calcium, fluoride, aluminium, manganese and iron were 35–69, 1.9–3.5, 0.80–2.0, 1.0–2.2, 0.52–1.9, 0.020–0.128 mg/l, respectively. Chromium and selenium were not detected. The resulting data showed considerable variability in catechins content. The levels of epigallocatechin gallate (EGCG) ranged from 117 to 442 mg/l, epicatechin 3-gallate (EGC) from 203 to 471 mg/l, epigallocatechin (ECG) from 16.9 to 150 mg/l, epicatechin (EC) from 25 to 81 mg/l and catechin (C) from 9.03 to 115 mg/l. Caffeine contents in the green tea infusions studied were between 141–338 mg/l. Green tea infusions provide significant amounts of catechins and could be an important source of some minerals.     

OsHemA gene,encoding glutamyl-tRNA reductase(GluTR) is essential for chlorophyll biosynthesis in rice(Oryza sativa)

Chlorophyll(Chl) biosynthesis is essential for photosynthesis and plant growth. Glutamyl-tRNA reductase(GluTR) catalyzes glutamyl-tRNA into glutamate-1-semialdehyde(GSA) and initiates the chlorophyll biosynthesis. Even though the main role of GluTR has been established, the effects caused by natural variations in its corresponding gene remain largely unknown. Here, we characterized a spontaneous mutant in paddy field with Chl biosynthesis deficiency, designated as cbd1. With intact thylakoid lamellar structure, the cbd1 plant showed light green leaves and reduced Chl and carotenoids(Cars) content significantly compared to the wild type. By map-based gene cloning, the mutation was restricted within a 57-kb region on chromosome 10, in which an mPingA miniature inverted-repeat transposable element(MITE) inserted in the promoter region of OsHemA gene. Both leaf color and the pigment contents in cbd1 were recovered in a complementation test, confirming OsHemA was responsible for the mutant phenotype. OsHemA was uniquely predicted to encode GluTR and its expression level was dramatically repressed in cbd1. Transient transformation in protoplasts demonstrated that GluTR localized in chloroplasts and a signal peptide exists in its N-terminus. A majority of Chl biosynthesis genes, except for POR and CHLG, were down-regulated synchronously by the repression of OsHemA, suggesting that an attenuation occurred in the Chl biosynthesis pathway. Interestingly, we found major agronomic traits involved in rice yield were statistically unaffected, except for the number of full grains per panicle was increased in cbd1. Collectively, OsHemA plays an essential role in Chl biosynthesis in rice and its weak allele can adjust leaf color and Chls content without compromise to rice yield.     

Recent advances in caffeine and theobromine toxicities: a review

Caffeine and theobromine are purine alkaloids widely consumed as stimulants and snacks in coffee and cocoa based foods and most often as part of ingredients in drugs. Man has enjoyed a long history of consumption of caffeine and theobromine. Recent interest in these two alkoloids, however, is centered on their potential reproductive toxicities. Caffeine and theobromine are now known to cross the placental and blood brain barrier thus potentially inducing fetal malformation by affecting the expression of genes vital in development. The developing fetus may not have developed enzymes for detoxification of these methylxanthine alkaloids via demethylation. There is a need, therefore, to protect the conceptus against insults from teratogens of this nature. Apart from its reproductive toxicity, the presence of caffeine and theobromine in cocoa could limit its potentials as a nourishing food. This is an issue that needs to be addressed by nutritionists and the food industry at large. This paper discusses the natural sources, consumption and uses, toxicity and the major advances in the reproductive toxicology of caffeine and theobromine. The biosynthesis of these compounds in plants, metabolism in mammalian systems and the involvement of cytochrome P450 are reviewed and summarized. Evidence in favor of the toxicity of these compounds in experimental animals is presented with emphasis on the implications of these findings in humans. The paper concludes with a call for caution in the use of caffeine and theobromine pending further and more elaborate investigations.     

Production of Avaroferrin and Putrebactin by Heterologous Expression of a Deep-Sea Metagenomic DNA

The siderophore avaroferrin (1), an inhibitor of Vibrio swarming that was recently identified in Shewanella algae B516, was produced by heterologous expression of the biosynthetic gene cluster cloned from a deep-sea sediment metagenomic DNA, together with two analogues, bisucaberin (2) and putrebactin (3). Avaroferrin (1) is a macrocyclic heterodimer of N-hydroxy-N-succinyl cadaverine (4) and N-hydroxy-N-succinyl-putrescine (5), whereas analogues 2 and 3 are homodimers of 4 and 5, respectively. Heterologous expression of two other related genes from culturable marine bacteria resulted in production of compounds 1–3, but in quite different proportions compared with production through expression of the metagenomic DNA.     

Radiation effect on ascorbic acid and riboflavin biosynthesis in germinating soybean

The influence of irradiation on biosynthesis of ascorbic acid and riboflavin in germinating soybean seeds in tap and distilled water at ambient (25–35°C) conditions was investigated. Ascorbic acid was not detectable in the original seeds and the initial level of riboflavin was 3.3 g/g. The rate of synthesis of these vitamins increased with increasing germination time up to 72–96hr followed by a decreasing pattern depending upon the treatment. The effect of irradiation and germination on the synthesis of these vitamins was statistically significant (P<0.01). Maximum amounts of ascrobic acid 16.2 and 15.0 mg/ 100 g (fresh weight basis) were found in the 0.10 kGy sample after 72 hr of germination in tap and distilled water, respectively. However, a radiation dose of 0.20 kGy resulted in the development of maximum values of riboflavin, 30.0 and 27.0 g/g (dry weight basis) on germination in tap and distilled water respectively.     

橡胶草可作为产胶研究的模式植物

以尾细桉9个无性系叶片为外植体进行叶片离体培养和植株再生研究。结果表明,TDZ对尾细桉的再生诱导起着明显的促进作用,9个尾细桉无性系都获得了植株诱导再生,再生过程中不同的无性系呈现出不同的TDZ响应浓度,TDZ浓度在0.005～0.010 mg/L时获得较高的再生效率。不同无性系之间的再生率呈现出明显的差异,其中无性系YL2获得了最高达69.2%的植株再生效率,且每个外植体平均芽数超过10个。TDZ浓度对YL2的再生起到显著性影响,0.050 mg/L时再生效率最高,可以进行下一步的遗传转化研究。