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Morphological changes and damage degrees of PPS can be tracked and detected by fluorescence during service. However, the functionalization of the main chain of PPS is limited. To explore its luminescent properties for fluorescence tracking, 1,6-dibromopyrene and 1,3,6,8-tetrabromopyrene were employed to construct Dbp-PPS (Dibromopyrene-PPS) and Tbp-PPS (Tetrabromopyrene-PPS) with fluorescence tracking, respectively. These two sets of copolymers were systematically designed, synthesized, and characterized by Uv–Vis, PL, FT-IR, TGA, DSC, and XRD. To sum up, both Dbp-PPS and Tbp-PPS displayed visible fluorescence. UV–vis spectra showed an absorption maximum at λabs = 262–411 nm. PL spectra demonstrated emission maximum at λem = 450–545 nm. Particularly, 0.25%Dbp-PPS emitted the most intense blue fluorescence with the emission maximum at 450 nm and the absolute quantum yield of Φf = 0.08. The fluorescence decay lifetime of 0.25%Dbp-PPS comprised two components with lifetimes of 0.43 and 1.17 ns, implying the formation of excimer. The IR and XRD spectra of Dbp-PPS and Tbp-PPS were in line with those of PPS. TGA measurements illustrated that introducing pyrene into PPS is favorable for improving thermal stability. The DSC analysis indicated their melting temperature ranged from 260.9 to 280.4 °C and Dbp-PPS exhibited a little better melting point (279.4–280.4 °C) than neat-PPS (278.4 °C). Meanwhile, the resultant copolymers possessed a flexural strength of 31.0–101.5 MPa and tensile strength of 69.2–96.7 MPa. Both the flexural and tensile strengths of only 0.25%Dbp-PPS (101.5 and 86.8 Mpa) were higher than that of neat-PPS (95.1 and 84.3 Mpa). Imparting the pyrene unit into the PPS backbone is an effective method to give the PPS fluorescence tracking function for inspecting or tracking the polymer during their application and keep the original high performance of the PPS. Importantly, the systematic studies for pyrene-containing PPS in the current work provide a practical polymer tracking strategy suitable for other aromatic polymers such as poly (ether ether ketone), poly (ether sulfone).

Ripening of banana ( Musa acuminate L.) fruit is concomitant with weakening of disease resistance. The aim of this research was to determine the patterns of expression of PR1 and chitinase genes during banana ripening. Northern blots show that the MaPR1 did not have expression in peel of young growing banana fruit, nor in harvested bananas until the onset of ripening. The chitinase gene ( MaChit ) had constitutive expression in bananas during development and after harvest. MaChit expression increased with time after harvest and reached the highest level at the onset of ripening when MaPR1 transcripts began to give detectable signals. Infection of the banana pathogen Colletotrichum musae did not induce MaPR1 but increased MaChit expression. The ethylene producer ethephon immediately induced MaPR1 , but benzothiadiazole (BTH) and methyl jasmonate (MeJA), when applied alone, did not. The combination of ethephon and BTH or MeJA treatment increased intensity of PR1 signals 12 h after treatment compared with ethephon alone, and in the combination treatments, the inoculation-related lesions were significantly ( P MaPR1 and MaChit transcripts decreased in distal uninfected areas, but in a combination treatment, it did not decrease. The triple combination of ethephon, BTH and diphenylene iodonium (DPI) reduced MaPR1 and MaChit expression compared with a double combination of ethephon and BTH, whereas when MeJA replaced BTH in the triple treatment, the expression of the two genes increased compared with the double treatment. This research suggests that MaPR1 could be involved in defense mechanisms of ripe bananas, while MaChit could more be involved in banana resistance to disease before ripening. The results also suggest that BTH and MeJA-induced systemic defense in banana fruit is ethylene-dependent, and H 2 O 2 might be necessary in BTH-induced SAR, but not in MeJA-induced systemic resistance. In the banana industry, MaPR1 could be used as a molecular indicator for monitoring banana ripening.

Oligonucleotide probes on the sensor surface can be hybridized with single-strand DNA (ssDNA) that is formed from PCR products in ice bath after degeneration. Thus, detection of PCR products by piezoelectric sensors requires the participation of ssDNA PCR products in ice bath. When PCR products in ice bath are added into the buffer of the sensor well at room temperature, there will be a temperature change process during mixing. However, it still remains unclear whether the temperature change affects the frequency baseline stability of the sensor and the result judgment, which is the basic condition for detecting hybridization of nucleic acid. In this study, we detected the hybridization of HPV PCR products during temperature change process by a self-designed adjustable metal-clamping piezoelectric sensor. The study mainly involves sensor adjustment, probe immobilization and ice bath sample addition (at different concentrations and different volumes). The response curve of basic frequency in temperature change process showed three stages, i.e., increase, decrease to baseline, and continuous decrease to stability. The early increase of frequency and duration of the time can reach 55+/-7.4 Hz and 39 min when 40 microL sample (0-1 degrees C) was added into 110 microL buffer (25 degrees C). The frequency increase effect caused by temperature difference at early stage depends on the volume ratio of two liquids and on the temperature difference. The results indicate that we should pay more attention to possibly small volume of PCR products in ice bath and minor temperature difference of two liquids in operation.

Xenopus oocyte death is partly controlled by the apoptotic initiator, caspase-2. We reported previously that oocyte nutrient depletion activates caspase-2 upstream of mitochondrial cytochrome c release. Conversely, nutrient-replete oocytes inhibit caspase-2 via S135 phosphorylation catalyzed by calcium/calmodulin-dependent protein kinase II. We now show that caspase-2 phosphorylated at S135 binds 14-3-3ζ, thus preventing caspase-2 dephosphorylation. Moreover, we determined that S135 dephosphorylation is catalyzed by protein phosphatase-1, which directly binds caspase-2. Although caspase-2 dephosphorylation is responsive to metabolism, neither PP1 activity nor binding is metabolically regulated. Rather, release of 14-3-3ζ from caspase-2 is controlled by metabolism and allows for caspase-2 dephosphorylation. Accordingly, a caspase-2 mutant unable to bind 14-3-3ζ is highly susceptible to dephosphorylation. Although this mechanism was initially established in Xenopus, we now demonstrate similar control of murine caspase-2 by phosphorylation and 14-3-3 binding in mouse eggs. These findings provide an unexpected evolutionary link between 14-3-3 and metabolism in oocyte death.

Summary Background Vertebrate oocytes are arrested in metaphase II of meiosis prior to fertilization by cytostatic factor (CSF). CSF enforces a cell-cycle arrest by inhibiting the anaphase-promoting complex (APC), an E3 ubiquitin ligase that targets Cyclin B for degradation. Although Cyclin B synthesis is ongoing during CSF arrest, constant Cyclin B levels are maintained. To achieve this, oocytes allow continuous slow Cyclin B degradation, without eliminating the bulk of Cyclin B, which would induce release from CSF arrest. However, the mechanism that controls this continuous degradation is not understood. Results We report here the molecular details of a negative feedback loop wherein Cyclin B promotes its own destruction through Cdc2/Cyclin B-mediated phosphorylation and inhibition of the APC inhibitor Emi2. Emi2 bound to the core APC, and this binding was disrupted by Cdc2/Cyclin B, without affecting Emi2 protein stability. Cdc2-mediated phosphorylation of Emi2 was antagonized by PP2A, which could bind to Emi2 and promote Emi2-APC interactions. Conclusions Constant Cyclin B levels are maintained during a CSF arrest through the regulation of Emi2 activity. A balance between Cdc2 and PP2A controls Emi2 phosphorylation, which in turn controls the ability of Emi2 to bind to and inhibit the APC. This balance allows proper maintenance of Cyclin B levels and Cdc2 kinase activity during CSF arrest.