Low sink demand caused net photosynthetic rate decrease is closely related to the irrecoverable damage of oxygen-releasing complex and electron receptor in peach trees.

Source sink balance is one of the major determinants of carbon partitioning in plants. However, its effects on photosynthesis in fruit trees are largely unknown. In this work, the effects of low sink demand on net photosynthetic rate (Pn) and chlorophyll fluorescence after fruit removal (-fruit) in peach (Prunus persica (L.) Batsch cv. 'Zaojiubao') trees were investigated. The stepwise energy flow through photosystem II (PSII) at the reaction center (RC) was analyzed with quantitative analyses of fluorescence transient, also called JIP-test. We found that Pn was significantly lower and closely correlated to the leaf stomatal conductance (Gs) of -fruit trees than that of fruit retained (+fruit) trees. Leaf temperature (Tleaf) of -fruit trees was remarkably higher than that of +fruit trees. Day-time-period assays of chlorophyll (Chl) fluorescence revealed that, in the leaves of -fruit trees, the fluorescence parameters, such as NPQ (non-photochemical quenching coefficient) and ΦD0 (maximum quantum yield of non-photochemical de-excitation), decreased in the morning and recovered to the normal level in the afternoon, whereas other parameters, such as ΦE0 (quantum yield for electron transport at t = 0), Ψ0 (probability that a trapped exciton moves an electron to QA pool), F0 (minimum fluorescence, when all PSII RCs are open) and Wk (relative variable fluorescence at 300 µs of the chlorophyll fluorescence transient), did not. These results suggest that OEC complex and QA pool were irreversibly affected by low sink demand, whereas light harvest antenna and PSII potential efficiency retained a strong ability to recover.

[Investigation of entecavir treatment in patients with LAM-refractory chronic hepatitis B].

OBJECTIVE: To evaluate the efficacy and safety of entecavir (ETV) as a long-term treatment in patients with lamivudine (LAM)-refractory chronic hepatitis B (CHB). METHODS: In this phase II study of ETV-056, 32 CHB patients with resistance to LAM monotherapy were administered ETV at 1.0 mg/day and monitored over a period of 8 years. The virologic, serologic and biochemical responses were measured throughout the treatment course. Outcomes analysis was conducted according to intention-to-treat principles. RESULTS: At baseline and treatment weeks 8, 12, 24, 48, 96, 144, 192, 240, and 420, the proportion of patients with HBV DNA less than 300 copies/ml was 0, 6.3% (2/32), 9.4% (3/32), 18.8% (6/32), 18.8%(6/32), 46.9% (15/32), 43.8% (14/32), 50.0% (16/32), 50.0% (16/32), and 62.5% (20/32). At treatment weeks 48, 96, 168, 192, 240, and 420, the proportion of patients experiencing virological breakthrough was 6.1% (2/32), 9.4% (3/32), 12.5% (4/32), 18.8%(6/32), 25.0%(8/32), and 28.1% (9/32). In the 8 year study period, 32.3% (10/31) of patients achieved HBs seroconversion and four patients achieved HBe seroconversion. CONCLUSION: While treatment with 1.0 mg/day ETV for up to 8 years resulted in mild HBV DNA suppression and increase of HBeAg seroconversion, the safety profile of this therapy was good but the economic cost was high and virological breakthrough rates were high.

Microfilament-binding properties of N-terminal extension of the isoform of smooth muscle long myosin light chain kinase.

Myosin light chain kinases (MLCK) phosphorylate the regulatory light chain of myosin II in thick filaments and bind to F-actin-containing thin filaments with high affinity. The ability of short myosin light chain kinase (S-MLCK) to bind F-actin is structurally attributed to the DFRXXL regions in its N-terminus. The long myosin light chain kinase (L-MLCK) has two additional DFRXXL motifs and six Ig-like modules in its N-terminal extension. The six Ig-like modules are capable of binding to stress fibers independently. Our results from the imaging analysis demonstrated that the first two intact Ig-like modules (2Ig) in N-terminal extension of L-MLCK is the minimal binding module required for microfilament binding. Binding assay confirmed that F-actin was able to bind 2Ig. Stoichiometries of 2Ig peptide were similar for myofilament or pure F-actin. The binding affinities were slightly lower than 5DFRXXL peptide as reported previously. Similar to DFRXXL peptides, the 2Ig peptide also caused efficient F-actin bundle formation in vitro. In the living cell, over-expression of 2Ig fragment increased "spike"-like protrusion formation with over-bundled F-actin. Our results suggest that L-MLCK may act as a potent F-actin bundling protein via its DFRXXL region and the 2Ig region, implying that L-MLCK plays a role in cytoskeleton organization.