Natural variation of main biochemical components,morphological and yield traits among a panel of 87 tea [Camellia sinensis(L.) O. Kuntze] cultivars

Many attentions have been previously focused to identify the multiple biochemical components related to tea quality and health benefits,however, the natural variation of biochemical components present in tea germplasm has not been adequately evaluated. In this study, the main biochemical components, leaf morphological and yield characteristics were evaluated for four rounds of tea leaves in a panel of 87 elite tea cultivars suitable for black, green, or oolong tea. Significant variations were observed among the tea cultivars, as well as seasonal differences in the levels of the free amino acid(FAA), caffeine(CAF), tea polyphenols(TP), water extract(WE) and TP to FAA ratio(TP/FAA). Results showed that the average levels of FAA showed a seasonal change, with the highest level of 4.0% in the 1st spring tea in the cultivars suitable for green tea and the lowest of 3.2% in summer tea in the cultivars suitable for black tea. The average CAF content was highest 3.2% in the cultivars suitable for oolong tea in the 1st spring and the lowest 2.5% in the cultivars suitable for green tea in summer. Limited seasonal and varietal variations were noticed in the average levels of WE among the three categories of tea. In addition, significant natural variation of the morphological characteristics, bud length varying from 2.5 cm to 8.7 cm, bud density from 190.3 buds · m-2to 1 730.3 buds · m-2, mature leaves biomass from 128.4 kg · hm-2to 2 888.4 kg · hm-2, and yield component traits of 100 buds(one bud with two leaves) dry weight from 3.7 g to37.7 g, tea yield/round from 444.6 kg · hm-2to 905.3 kg · hm-2, were observed. The aim of our evaluation was not only to identify the advantages of seasonal and clonal variations but also to provide a new viewpoint for their further application. Representative accessions were selected from the germplasm to promote the establishment of an inherent biochemical constituent expressing the quality of black, green, and oolong tea. The findings might be utilized to establish early selection criteria to enhance the tea breeding and production program.

Analysis of Differences in Biochemical Components Between Yunnan and Kenya Tea Tree Varieties

With 16 Yunnan tea tree varieties and 5 Kenya tea tree varieties as test materials,the differences in biochemical components between Yunnan and Kenya tea tree varieties were compared and analyzed.The results showed that the coefficients of variation of tea polyphenols,amino acids,caffeine,water extract,gallic acid(GA),catechin(C),epicatechin(EC),epicatechin gallate(ECG),epigallocatechin(EGC),epigallocatechin gallate(EGCG)and total catechins in Yunnan tea tree varieties were greater than those in Kenyan tea trees.The contents of tea polyphenols,amino acids,caffeine,water extract,C,EC,EGC,EGCG and total catechins in Yunnan tea tree varieties had no significant differences from those in Kenyan tea trees varieties(P>0.05),while there were significant differences in the contents of GA and ECG between Yunnan tea tree varieties and Kenya tea tree varieties(P<0.05).Therefore,it could be predicted that GA and ECG might be one of the main characteristics of the differences in biochemical components between Yunnan tea tree varieties and Kenyan tea tree varieties.The cluster analysis results showed that when the genetic distance was 15,the 21 tested tea varieties could be divided into three groups with obvious biochemical differences.

Changes of Serum Trace Elements, AFP, CEA, SF, T3, T4 and IGF-Ⅱ in Different Periods of Rat Liver Cancer

Objective: Based on liver cancer model built in SD rats, the contents of trace elements (Cu, Fe, Zn, Ca and Mg), AFP, CEA, SF, TH and IGF-II in serum were measured at different stages to explore the molecular changes during the rat liver cancer development. Methods: The SD rat liver cancer model was built by using diethylnitrosamine (DENA) as the mutagen. During 16 weeks of DENA gavage, blood samples were taken in the 14th, 28th, 56th, 77th, 105th and 112th days respectively after the first day of gavage with DENA, then the contents of five trace elements (Cu, Fe, Zn, Ca and Mg), T3, T4, IGF-II, AFP, CEA and SF in serum were determined. Results: During the development of the rat liver cancer, in the test group, the Cu content significantly increased in serum, while the contents of Fe, Zn and Ca significantly decreased. The content of Mg showed no significant change. AFP and CEA of the test group showed same expression level with the control group; while the content of SF was lower than that of the control group when cancerization appeared. T3 and T4 increased at the first stage and then went down, and the content of IGF-II was always high. Conclusion: Cu, Fe, Zn, Ca, T3, T4, SF and IGF-II are closely related to the development of liver cancer. The changes of their contents in the development of cancer could enlighten the researches on cancer pathogenesis and prevention.

Effects of nutrient limitations on the sinking velocity of Thalassiosira weissflogii

The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,we measured the sinking velocity(SV) of Thalassiosira weissflogii using a new phytoplankton video observation instrument and analyzed major biochemical components under varying nutrient conditions.Our results showed that the SV of T.weissflogii under different nutrient limitation conditions varied substantially.The highest SV of(1.77±0.02) m/d was obtained under nitrate limitation,signific antly surpassing that under phosphate limitation at(0.98±0.13) m/d.As the nutrient limitation was released,the SV steadily decreased to(0.32±0.03) m/d and(0.15±0.05) m/d,respectively.Notably;under conditions with limited nitrate and phosphate concentrations,the SV values of T.weissflogii significantly positively correlated with the lipid content(P <0.001),with R^(2) values of 0.86 and 0.69,respectively.The change of the phytoplankton SV was primarily related to the intracellular compo sition,which is controlled by nutrient conditions but did not significantly correlate with transparent extracellular polymer and biosilica contents.The results of this study help to understand the regulation of the vertical sinking process of diatoms by nutrient restriction and provide new insights into phytoplankton dynamics and their relationship with the marine nutrient structure.

Evaluation and salivary biochemistry associations of sour-salty taste interaction

Taste interaction is a well-known phenomenon in sensory stodies,but how to quantify the magnitode of the effect of one tastant on other taste attribute(s)is still largely unsolved,let alone further explorations from a salivary biochemistry perspective.Upon acquiring the individual taste threshold and evaluating the just noticeable difference(JND).this stody firstly established a quantitative method to assess the magnitude of taste interaction in a binary taste mixture by evaluating the concentration difference upon psychologically-comparable stimulation.The change of salty taste intensity(CSI)was therefore defined as the subtraction of JND using sour-salty taste stimulant from JND using pure salty taste stimulant,with a dimension of concentration in mmol/L.CSI was then used to demonstrate how citric acid affected salty taste perception in a salty-sour binary taste mixture in 16 young and healthy participants.Concentrations of citric acid used in the binary taste mixtore were 0.05.0.09.0.14.0.24 and 0.40 mmolL,respectively.and results showed that salty taste perception was enhanced(average CSI of 0.93 mmolL)when the citric acid concentration was low(at 0.05 and 0.09 mmolL).but with an increasing concentration of citric acid ranging from 0.14 to 0.40 mmol/L,this effect gradually turned from enhancement to suppression of salty taste perception(correspondingly a continoously decreasing CSI all the way down to an average of-2.94 mumol/L).It was also found that cystatin SN concentration in participants'unstimulated saliva samples was significantly negatively correlated with salty taste threshold(with and without the presence of citric acid),and it was one of the most significant factors affecting CSI,s shown in multiple regression analysis.Carbonic anhydrase VI concentration in participants'unstimulated saliva sanples was also found to be significantly negatively correlated with salty taste recognition(with and without presence of citric acid).but it did not pose significant effect on CSI.From these results,this study had not only demonstrated a citric acid concentration-dependent salty taste perception phenomenon based on a proposed methodology to quantitively assess the taste interaction in binary taste mixtures.but also showed how salivary biochemical properties(cystatin SN and carbonic snhydrase VI)might have been assciated with salty taste perception during food oral processing.