ObjectivePreviously, we identified that transketolase (Tkt), an important enzyme in the pentose phosphate pathway, is highly expressed at 2 hours of spontaneous maturation in oocytes. Therefore, this study was performed to determine the function of Tkt in meiotic cell cycle regulation, especially at the point of germinal vesicle breakdown (GVBD).MethodsWe evaluated the loss-of-function of Tkt by microinjecting Tkt double-stranded RNAs (dsRNAs) into germinal vesicle-stage oocytes, and the oocytes were cultured in vitro to evaluate phenotypic changes during oocyte maturation. In addition to maturation rates, meiotic spindle and chromosome rearrangements, and changes in expression of other enzymes in the pentose phosphate pathway were determined after Tkt RNA interference (RNAi).ResultsDespite the complete and specific knockdown of Tkt expression, GVBD occurred and meiosis was arrested at the metaphase I (MI) stage. The arrested oocytes exhibited spindle loss, chromosomal aggregation, and declined maturation promoting factor and mitogen-activated protein kinase activities. The modified expression of two enzymes in the pentose phosphate pathway, Prps1 and Rbks, after Tkt RNAi and decreased maturation rates were amended when ribose-5-phosphate was supplemented in the culture medium, suggesting that the Tkt and pentose phosphate pathway are important for the maturation process.ConclusionWe concluded that Tkt and its associated pentose phosphate pathway play an important role in the MI-MII transition of the oocytes' meiotic cell cycle, but not in the process of GVBD.

The COP9 (constitutive photomorphogenic) signalosome (CSN), composed of eight subunits, is a highly conserved protein complex that regulates processes such as cell cycle progression and kinase signalling. Previously, we found the expression of the COP9 constitutive photomorphogenic homolog subunit 3 (CSN3) and subunit 5 (CSN5) changes as oocytes mature for the first time, and there is no report regarding roles of COP9 in the mammalian oocytes. Therefore, in the present study, we examined the effects of RNA interference (RNAi)-mediated transient knockdown of each subunit on the meiotic cell cycle in mice oocytes. Following knockdown of either CSN3 or CSN5, oocytes failed to complete meiosis I. These arrested oocytes exhibited a disrupted meiotic spindle and misarranged chromosomes. Moreover, down-regulation of each subunit disrupted the activity of maturation-promoting factor (MPF) and concurrently reduced degradation of the anaphase-promoting complex/cyclosome (APC/C) substrates Cyclin B1 and Securin. Our data suggest that the CSN3 and CSN5 are involved in oocyte meiosis by regulating degradation of Cyclin B1 and Securin via APC/C.

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New electroluminescent copolymers with BT units in the PCPP backbone, poly(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)-co-poly(2,1,3-benzothiadiazole) (PCPPBTs), have been synthesized by the Suzuki coupling reaction. The BT units were introduced on the PCPP backbone to affect a red-shifted color change and to increase the electron affinities of the copolymers. The PCPPBTs exhibited absorption spectra with maximum peaks at 330−431 nm in THF solution and at 337−445 nm in the solid film state. In the PL spectra were two emission peaks at around 400 and 530 nm in solution and at 510−535 nm in thin film. The PL characteristics of these copolymers could possibly be influenced by two competing effects: Förster energy transfer and the intramolecular charge transfer. The HOMO energy levels of the copolymers were approximately −5.89 to −5.96 eV, and the LUMO energy levels were about −3.33 to −3.50 eV. The polymer LEDs (ITO/PEDOT/polymer/Ca:Al) of PCPPBTs showed emissions with maximum peaks at 508−528 nm. By randomly copolymerizing the BT into the PCPP, the PL efficiency was improved. Among all the devices fabricated, the best device was the one with PCPPBT10, which showed the highest luminous efficiency of 1.25 cd/A and the highest brightness of 1170 cd/m2. The present study suggests that the introduction of BT units in PCPP can enhance the device performance to result in stable PL and EL spectra with high current density and brightness.

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