Phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) and catechins (flavan-3-ols) accumulation in tea

Phenylalanine ammonia-lyase and cinnamate 4-hydroxylase are important enzymes in allocating significant amounts of carbon from phenylalanine into the biosynthesis of several important secondary metabolites. Tea is an important crop of commerce known for its beverage and medicinally important flavonoid compounds, mainly catechins. As metabolic flux for the operation of the flavonoid pathway is maintained through the activities of PAL and C4H, thus, catechins biosynthesis in tea is critically dependent on the products of these enzymes. We examined the expression of PAL and C4H. Sequence encoding CsPAL was isolated from tea by polymerase chain reaction using sequence information available at the NCBI GenBank. Sequence encoding C4H was isolated from tea by using differential display of mRNA and rapid amplification of cDNA ends technology. CsC4H (AY641731) comprised of 1,352 bp full-length cDNA with open reading frame of 1,173 bp encoding 390 amino acids. Catechin contents decreased in response to drought stress (DS), abscisic acid (ABA), and gibberellic acid (GA₃) treatments but increased in response to wounding. The expression of CsPAL and CsC4H showed the same behavior under the above treatments and was also in accordance with the catechin contents. A positive correlation between catechin contents and gene expression suggested a critical role of the enzymes in catechins biosynthesis and a crosstalk between phenylpropanoid and flavonoid pathways.     

Antioxidant actions of flavonoids: Thermodynamic and kinetic analysis

The benefits of flavonoids on human health are very often ascribed to their potential ability to act diminishing free radical steady state concentration in biological systems providing antioxidant protection. This is an assumption based on the chemical structures of flavonoids that support their capacity to scavenge free radicals and chelate redox-active metals. In this paper we will use thermodynamic and kinetic approaches to analyze the interactions of flavonoids with biological material and from there, extrapolate the physiological relevance of their antioxidant actions. Thermodynamic analysis predicts that both, scavenging of oxygen-derived radicals and the sequestration of redox-active metals are energetically favored. Nevertheless, the actual concentrations reached by flavonoids in most animal and human tissues following dietary ingestion are incompatible with the kinetic requirements necessary to reach reaction rates of physiological relevance. This incompatibility becomes evident when compared to other antioxidant compounds, e.g. α-tocopherol (vitamin E), ascorbate (vitamin C), and glutathione. Alternatively, lipid-flavonoid and protein-flavonoid interactions can indirectly mediate a decrease in oxidant (free radical) production and/or oxidative damage to both cell and extracellular components. The final mechanisms mediating the antioxidant actions of flavonoid will be determined by their actual concentration in the tissue under consideration.     

Influences of crude extract of tea leaves,Camellia sinensis,on streptozotocin diabetic male albino mice

Natural remedies from medicinal plants are considered to be effective and safe alternative treatment for diabetes mellitus. The aim of the present study was to investigate the hypoglycemic activity of the crude tea leaves extract on streptozotocin (STZ)-induced diabetic mice. The average body weight of animals with diabetes and their percentage changes of body weight gain after 15 and 30 days were significantly lower than that of the normal control mice. In diabetic mice, supplementation with tea leaves extract decreased the loss of body weight. After 15 and 30 days, significant increases in the levels of serum glucose, triglycerides, cholesterol, creatinine, urea, uric acid, glutamic pyruvic acid transaminase (GPT) and glutamic oxaloacetic acid transaminase (GOT) were noted in STZ-diabetic mice fed with normal diet. Also, the values of total protein in this group were statistically declined after 15 and 30 days. The levels of serum glucose and GPT were significantly elevated after 15 and 30 days in diabetic mice supplemented with tea leaves extract. Moreover, the level of serum GOT was notably increased after 30 days. Insignificant alterations were observed in the levels of serum triglycerides, cholesterol, total protein, creatinine, urea and uric acid in diabetic mice supplemented with tea leaves extract. Thus, the present results have shown that tea leaves extract has the antihyperglycemic, antihyperlipidemic, and antihyperproteinemic effects and consequently may alleviate liver and kidney damage associated with STZ-induced diabetes in mice.     

Is decreased generalized immunity a cost of Bt resistance in cabbage loopers Trichoplusia ni?

We studied the immune response to Bacillus thuringiensis kurstaki (Btk) in susceptible (Bt-RS) and resistant (Bt-R) Trichoplusia ni after exposure to low doses of Btk and injection with Escherichia coli. We measured the levels of resistance, the expression profiles of hemolymph proteins, the phenoloxidase (PO) activity, and the differential number of circulating hemocytes in resistant and susceptible individuals. Individuals from the Bt-RS line became more resistant following a previous exposure to sub lethal concentrations of Btk, but the resistance to Btk of the Bt-R line did not change significantly. Similarly the Bt-R strain showed no significant changes in any of the potential immune responses, hemolymph protein levels or PO activity. The number of circulating hemocytes was significantly lower in the Bt-R strain than in the Bt-RS strain. Exposure to Btk decreased the hemocyte counts and reduced PO activity of Bt-RS larvae. Hemolymph protein concentrations also declined significantly in the susceptible larvae continually exposed to Btk. Seven peptides with antibacterial activity were identified in the hemolymph of Bt-RS larvae after exposure to Btk and five were found in the Bt-R larvae. When exposed to a low level Bt challenge the susceptible strain increases in tolerance and there are concomitant reductions in hemolymph protein concentrations, PO activity and the number of circulating hemocytes.     

广西茶树资源生化成份多样性分析

对国家种质杭州茶树圃保存的来源于广西的98份茶树资源主要生化成分进行了评价鉴定和遗传多样性分析。结果发现,广西地方茶树资源的生化成分存在丰富的多样性和变异,平均遗传多样性指数达到1.90,平均变异系数达到25.8%。通过多变量的主成分分析,前7个主成分代表了茶树生化成分多样性的86.75%的信息。基于生化成分,把98份资源聚类划分为3个类群。第1类群大部分为红绿茶兼制的资源,第2类群大部分为适制红茶的资源,第3类群大部分为适制绿茶的资源。并从中筛选出一批生化成分特异的资源。     

Spatial and temporal changes in genetic structure of greenhouse and field populations of cabbage looper,Trichoplusia ni

Trichoplusia ni is a subtropical moth that migrates annually from southern California to southern British Columbia, Canada where it invades vegetable greenhouses and field crops. The heated greenhouse environment has altered the natural extinction–recolonization dynamics of T. ni populations, and allows year‐round persistence in some locations. In addition, the extensive use of the biopesticide, Bacillus thuringiensis subspecies kurstaki (Bt) in some greenhouses has selected for resistance. Here we investigated the genetic structure of T. ni populations in British Columbia greenhouses and in field populations in California and British Columbia using amplified fragment length polymorphisms (AFLP) as related to patterns of Bt resistance. The majority of British Columbia field populations were similar to the California field populations, the potential source of migrants. However populations in two geographic areas with high concentrations of greenhouses showed local genetic differentiation. Some of these populations experienced severe bottlenecks over‐winter and following Bt sprays. Greenhouse populations showed a pattern of isolation by distance and a strong positive relationship between genetic differentiation and levels of Bt resistance. These patterns indicate that greenhouses that sometimes support year‐round populations of T. ni and the ensuing strong bottlenecking effects following winter cleanups and Bt application cause genetic differentiation of T. ni populations. Long distance migrants to field populations contribute to genetic homogeneity of these.     

Diversity Analysis of Chlorophyll,Flavonoid, Anthocyanin,and Nitrogen Balance Index of Tea Based on Dualex

The chemical compositions of tea (Camellia sinensis) are affected by numerous factors, such as cultivar, climate, leaf position, and cultivation pattern. However, under the same conditions, the chemical compositions are mainly determined by varieties. Therefore, we investigated the genetic diversity of chemical compositions of tea tree resources in China to screen excellent germplasm resources. Three chemical compositions index (including chlorophyll index, flavonoid index, and anthocyanin index) and the nitrogen balance index of tea leaves were measured in 102 tea germplasms planted in Chinese Tea Plants Improved Variety Germplasm Resources Nursery (CTPIVGRN) by Dualex on April 15 2019. Results showed that the chlorophyll, flavonoid, and anthocyanin contents and the nitrogen balance index significantly differed between the 102 tea germplasms. The genetic diversity index values were 2.005, 2.246, 1.599, and 1.838, and the average genetic diversity was 1.922. The 102 tea germplasms can be divided into four categories by cluster analysis under the genetic distance threshold of 11. These results suggest that the genetic diversity of tea germplasm resources in China is rich. This study’s results can serve as a basis for the diversified development and utilization of tea plant.     

Black Tea Represents a Major Source of Dietary Phenolics Among Regular Tea Drinkers

The phenolic composition and antioxidant activities [TEAC, ORAC, FRAP] of consumer brews (1 tea bag in 230 ml for 1 min) of seven different brands of black tea from the British market were investigated. The main phenolic compounds identified were epigallocatechin gallate, four theaflavins, as well as epicatechin gallate, theogallin (tentative assignment), quercetin-3-rutinoside and 4-caffeoyl quinic acid. Thearubigins represented an estimated 75-82% of the total phenolics. Further, polyphenol fractions were in decreasing order theaflavins, flavan-3-ols, flavonols, gallic acids and hydroxycinnamates. On average, a cup of a consumer brew of black tea is providing polyphenols at the level of 262 mg GAE/serving, of which 65 mg were assigned to individual polyphenols. The antioxidant activity of black tea preparations is higher than that of most reported dietary agents on a daily basis. Correlations were observed between the antioxidant activities and the sum of all quantified polyphenols by HPLC analysis as well as with the total phenolics. Treatment of the black tea brew with simulated gastric juice resulted in a significant increase of the identified theaflavins implying a partial cleavage of thearubigins in the environment of the gastric lumen. Therefore, black tea can be considered to be a rich source of polyphenols and/or antioxidants.     

印度小圆胸小蠹的一种新寄主植物

自然条件下印度小圆胸小蠹Euwallacea fornicatus(Eichhoff,1868)在茶树枝条虫瘿内取食,是茶的重要害虫之一,以茶蛀虫著称.2010年5-8月,在印度Muga Eri研究中心3号农场(Lahdoigarh,Jorhat-Assam)的黄心树Persea bombycina Kost.(樟科)...