Effects of fruit thinning on ascorbate–glutathione cycle metabolism in black currants(Ribes nigrum L.)

To elucidate mechanisms regulating ascorbic acid (AsA) biosynthesis and accumulation in the fruit and leaves of black currants, AsA and the activities of key enzymes in the ascorbate-glutathione (AsA-GSH) cycle were measured from fruit set to fruit ripening during fruit thinning treatments of three common commercial black currant cultivars that differed in their AsA levels: 'Risager' (low), 'Brodtrop' (medium) and 'Adelinia' (high). Treatments were 50% fruit reduction (50% of total fruit set) by hand, control was no thinning. Fruit thinning treatment significantly increased AsA content in fruit of all three cultivars from weeks 2 to 8, significantly decreased AsA content in leaves from weeks 3 to 8. Dehydroascorbate reductase and monodehydroascorbate reductase activities in fruit and leaves had a similar pattern, increasing during week 2, rose until they peaked in week 4. Ascorbate peroxidase activity in fruit in the thinning treatment was slightly lower than in the control. Fruit thinning was shown to be a good model to test AsA biosynthesis regulation and accumulation in black currants. The results from our study provided strong evidence that AsA-GSH cycle involved in AsA synthesis and accumulation in fruit.

Effects of GA3 and ABA on the respiratory pathways during the secondary bud burst in black currants

The effects of exogenous gibberellic acid (GA(3)) and abscisic acid (ABA) on the total respiratory rate, percentages of total respiratory rate contributed by respiratory pathways [Embden-Meyerhof- Parnas Pathway (EMP), Pentose Phosphate Pathway (PPP), and Tricarboxylic Acid Cycle (TCA)], and conversion of starch to soluble sugars in the buds of black currants during secondary bud burst were investigated to determine the relationship between respiratory rates and secondary bud burst. 'Adelinia', a black currant cultivar that is prone to secondary bud burst after the first harvest, was used in this study. Mature bushes of Adelinia were sprayed with 30 mg/L GA(3) and 50 mg/L ABA to manipulate bud burst. The results showed that exogenous applications of GA(3) and ABA had opposite effects on bud respiratory rate. Generally, GA(3) treatment increased the total respiratory rate and respiratory rate of the TCA and PPP, and the respiratory rates after GA(3) treatment were higher than those of control. While ABA treatment mostly decreased the total respiratory rate and the respiratory rate of TCA and PPP in buds in comparison to control. In terms of the percentage of the three respiratory rates in comparison to the total respiratory rate, GA(3) treatment significantly increased the percentage of TCA and PPP respiratory rate in comparison to the control (P < 0.01), whereas ABA decreased the rates. GA(3) significantly increased the content of soluble sugars and decreased the starch content, while the starch content in buds after ABA treatment was significantly higher than that of the control. All results showed that PPP is a critical process for the second bud burst in black currants. While the EMP-TCA pathway is still dominant in bud respiration, provides a series of basic materials and energy (ATP). The conversion of starch to soluble sugars is essential for bud burst. Thus, we conclude that an energy shortage is a main contributor in ABA inhibition of the secondary bud burst of black currants.

Studies on the Flavonoids and Antioxidant Activities in Leaves of Black Currant

The fresh leaves and oven dried leaves from three varieties of black currant (Brodtrop,liangye,Risager)were analysed for the total contents of flavonoids by spectrophotometric methods in terms of rutin equivalent.In addition,antioxidant activities of different addition amounts of extracts of black currant (Brodtrop)leaves in lard were measured by the Oven-Storage Test,and compared with the synthetic antioxidants.The results showed the contents of the flavonoids were very rich in the leaves of three varieties from black currant.Among them the leaves of Brodtrop had the highest contents of flavonoids followed by liangye and Risager.The total contents of flavonoids in fresh leaves reach 231 70 mg/100 g,170 01 mg/100 g and 78 07 mg/100 g respectively.In the same circumstance the oven dried leaves were 397 82 mg/100 g,275 89 mg/100 g and 169 73 mg/100 g.The extracts of the leaves from Brodtrop exhibited strong antioxidant activities on lard,which increased with the addition amount of the flavonoid extracts.The antioxidant activities decreased in the order of 0 02% quercetin >0 02% BHT(butylated hydroxy toluene)>0 40% extracts>0 20% extracts>0 10% extracts>0 05% extracts>0 02% extracts>control.

Studies on Optimal Extraction Conditions of Flavonoid in Leaves of Black Currnt

Employing the orthogonal design,the optimal extraction conditions for flavonoid in leaves of black currant were determined by colorimetric estimation,which were extraction agent of 75% EtOH-H 2O,the material ratio(ratio of weight of fresh leaves to volume of the solvent)of 1:16,the temperature of 35℃,the time of 1 h and times of three.A total extraction rate of over 97% and the flavonoid contents of 179 33 mg/100 g were obtained under the optimal extraction conditions.

Physiological Effects of Rare Earths on Black Currant Plants

Various concentrations of ''Nongle'' rare earth were applied on 'Xinbin'' cultivar of black currant plants. The results indicated that leaf chlorophyll contents, photosynthetic rate, stomatal conductance, photon flux density and leaf transpiration rate of black currant plants were influenced significantly by rare earth applied on leaves. Foliage application of 300 to 800 mg/L rare earth two times in the growing season was better than those applied once.

Formulating etoposide in a nanoemulsion containing polyunsaturated fatty acids potentiates its anti-proliferation and anti-invasion activities against the ovarian cancer cells

Inorporation of etoposide(ETP)into nanoemulsion(NE)containing polyunsaturated faty adids(PUFAS)may potentially augment its antiproliferation efet on the cancer cll The current study aimed to examine the in vitro antitumor activity of a novel formulation(ETP-BC/EP-NE)produced by combining the anticancer drug(ETP)with NE(BCEP-NE)consisting of the blasck currant seed and organic ewening primrose oils.The produced formulas were physically charaterized using 2etasizer measurements.Thelr ceytotoxkc efect was testfied at concentrations ranges from 0.0001 to 5μM using CCK-8.Apoptotic and ant-invasion efects were evaluated using the assays of mitochondrtal membrane potental,annexin V-FITC double staining.DNA fragmentation,and collagen-based cell invasion.According to the zetasizer charaterization,the nano-suspensions of ETP-BC/EP-NE have z-average diameters of 87.63土3.30 nm with an average surface zeta potential of-0.605土0.003 mV.A reduction of 50%in the growth of SK-OV-3 cells was found at a distinetly lower concentration of ETP-BCEP-NE(IlCso=0.04土0.2μM)than that of ETP(ICsu=4.75土0.1μM).Resuts indicated that FTP-BCIEP-NE had a greater apoptotic ffect than FTP on SK-OV-3 cllsl which was attibuted to the larger amount of late apoptotic cells(41.9土1.05%)higher loss of mitochondrial membrane potential,and more intensive fragmented DNA The ETP-BC/EP-NE treatment suppressed the cllular invasion by 55%,whereas EIP impeded the ellular invasion by only 3%,Formulting ETP with PUFAs in NE had ameliorated the efcacy of ETP.

Dormancy Interferes with Flowering in Perennial Plants with Short Day Regulation of Both Processes:A Mini-Review

In many perennial woody plants growing in the temperate and cold regions, regulation of seasonal growth cessation and floral initiation are closely integrated, both taking place in photoperiods shorter than a critical length. In the temperate shrub black currant (Ribes nigrum L.), the two processes proceed harmoniously in parallel under naturally decreasing autumn photoperiods, whereas an abrupt shift to photoperiods well below the critical length results in an immediate growth cessation and premature dormancy. As a result, floral initiation is suppressed and arrested. Other perennial plants such as hop (Humulus lupulus), which have the same dual short day responses, behave in the same way. In such plants, optimal flowering takes place at near-critical photoperiods, which are short enough to induce flowering and still long enough to prevent premature dormancy. These responses deviate from the situation in annual plants, which have predominated in studies on photoperiodic control of flowering. Another example of linkage between flowering and dormancy responses is the well-known dual effects of chilling temperature on vernalization and its relation to dormancy. Elucidation and disentangling of these networks of integrated processes are now awaiting joint research efforts in the areas of molecular genetics and experimental plant physiology.