Isolation of CHS Gene from Brunfelsia acuminata Flowers and Its Regulation in Anthocyanin Biosysthesis.

Chalcone synthase gene (BaCHS) from Brunfelsia acuminata flowers was isolated using RT-PCR and RACE. The coding region of the gene is 1425-bp with an open reading frame of 1170-bp, 73-bp 5'UTR, and 172-bp 3'UTR. Its deduced protein does not have a signal peptide but does contain a cond_enzyme superfamily domain, and consists of 389 amino acids with a predicted molecular mass of 42,699 Da and a pI of 6.57. The deduced amino acid sequence of BaCHS shares 90%, 88%, 85%, 84% and 79% identity with CHS from Petunia hybrida, Nicotiana tabacum, Solanum lycopersicum, Capsicum annuum and Camellia sinensis, respectively. The striking color change from dark purple to light purple and ultimately lead to pure white resulted from a decline in anthocyanin content of the petals and was preceded by a decrease in the expression of BaCHS. Its gene expression was positively correlated with the contents of anthocyanin (p ≤ 0.01).

Specific lignin accumulation in granulated juice sacs of Citrus maxima.

Juice sac granulation occurring in pummelo fruits [Citrus maxima (Burm.) Merr.] is an undesirable trait, and the underlying mechanism remains unresolved. Previous studies have shown that lignin metabolism is closely associated with the process of juice sac granulation. Here, a method suitable for lignin isolation from pummelo tissues is established. Acetylated lignins from different pummelo tissues and cultivars were analyzed by HSQC NMR. The results showed that lignins in granulated juice sacs were characterized by an extremely high abundance of guaiacyl units (91.13-96.82%), in contrast to lignins from other tissues, including leaves, stems, and segment membranes. The abnormally accumulated lignins in granulated juice sacs were specific and mainly polymerized from coniferyl alcohol. No significant difference was found in lignin types among various cultivars. These findings indicated that the mechanism of juice sac granulation might be similar among various cultivars, although very different degrees of juice sac granulation can be observed.

[Mammalian target of rapamycin regulates androgen receptor and Akt phosphorylation in prostate cancer 22RV1 cells].

OBJECTIVE: To investigate the roles of the mammalian target of rapamycin-1 and -2 (mTORC1 and TORC2) in the proliferation and apoptosis of prostate cancer 22RV1 cells. METHODS: After silencing mTORC1 and TORC2, we examined the proliferation and apoptosis of prostate cancer 22RV1 cells by methylthiazol tetrazolium (MTT) assay and flow cytometry, respectively, and detected the expressions of the androgen receptor (AR) and Akt phosphorylation in the prostate cancer 22RV1 cells by Western blot after transfecting Raptor-siRNA and Rictor-siRNA to the 22RV1 cells. RESULTS: MTT showed that the prostate cancer 22RV1 cells had no significant change in the growth rate after mTORC1 silence (P > 0.05), but their proliferation was markedly inhibited after mTORC2 silence (P < 0.01). Flow cytometry revealed a dramatic increase in the apoptosis of the 22RV1 cells after mTORC1 silence (P < 0.01), but no obvious change after mTORC2 silence (P > 0.05). Western blot exhibited that mTORC1 silence significantly increased the expression of AR and Akt phosphorylation (P < 0.05), while mTORC2 silence markedly decreased them (P < 0.05). CONCLUSION: mTORC2 is not only required for the survival of prostate cancer 22RV1 cells, but also a promising therapeutic target of prostate cancer.

Cloning of NAD-SDH cDNA from plum fruit and its expression and characterization.

A full-length cDNA consisting of 1444 bp for NAD dependent sorbitol dehydrogenase (NAD-SDH) was cloned from fruit of plum (Prunus salicina var. cordata cv. Younai) by means of RT-PCR and RACE. The cDNA containing an open reading frame (ORF) of 1101 bp encoded a polypeptide of 367 amino acid residues. The maltose binding protein fusion SDH (MBP-SDH) was expressed and partially purified from Escherichia coli cells, and biochemical properties of MBP-SDH and SDH cleaved from the fusion protein by factor Xa were characterized. The MBP-SDH had the specific affinity for NAD and was able to oxidize sorbitol, xylitol, l-ribitol and mannitol but not ethyl alcohol, arabitol and other polyols. The optimum pH for the oxidation of sorbitol and the reduction of fructose was 9.0 and 7.0, respectively; the maximum reaction rate occurred when temperature increased up to 50 °C in the presence of sorbitol. The MBP-SDH with a subunit of 80 kDa appears to be a hexamer. Its molecular weight was 478.6 kDa estimated by gel filtration and 493.2 kDa estimated using native linear gradient PAGE. The K(m) values for sorbitol, NAD, fructose and NADH were 95.86 mM, 0.31 mM, 1.04 M and 0.038 mM, respectively. However, when MBP was cleaved from the fusion enzyme, the SDH exists as a homotetramer with the native molecular weight of 164.8 kDa estimated by gel filtration. The K(m) values were 111.8 mM, 0.35 mM, 1.25 M and 0.048 mM for sorbitol, NAD, fructose and NADH, respectively. The MBP-SDH and the SDH were similar with respect to their kinetic characteristics despite their difference in quaternary structures.