Down-regulated expression of OPCML predicts an unfavorable prognosis and promotes disease progression in human gastric cancer.

BACKGROUND: OPCML belongs to the IgLON family of Ig domain-containing GPI-anchored cell adhesion molecules and was recently found to be involved in carcinogenesis, while its role in gastric cancer remains unclear. METHODS: We assessed expression and biological behavior of OPCML in gastric cancer. RESULTS: OPCML expression was markedly reduced in tumor tissues and cancer cell lines. Decreased OPCML expression had a significant association with unfavorable tumor stage (p = 0.007) and grading (p < 0.001). Furthermore, the results revealed that OPCML was an independent prognostic factor for overall survival in gastric cancer (p = 0.002). In addition, ectopic expression of OPCML in cancer cells significantly inhibited cell viability (p < 0.01) and colony formation (p < 0.001), arrest cell cycle in G0/G1 phase and induced apoptosis, and suppressed tumor formation in nude mice. The alterations of phosphorylation status of AKT and its substrate GSK3ß, up-regulation of pro-apoptotic regulators including caspase-3, caspase-9 and PARP, and up-regulation of cell cycle regulator p27, were implicated in the biological activity of OPCML in cancer cells. CONCLUSION: Down-regulated OPCML expression might serve as an independent predictor for unfavorable prognosis of patients, and the biological behavior supports its role as a tumor suppressor in gastric cancer.

Energy status of ripening and postharvest senescent fruit of litchi (Litchi chinensis Sonn.).

BACKGROUND: Recent studies have demonstrated that cellular energy is a key factor switching on ripening and senescence of fruit. However, the factors that influence fruit energy status remain largely unknown. RESULTS: HPLC profiling showed that ATP abundance increased significantly in developing preharvest litchi fruit and was strongly correlated with fruit fresh weight. In contrast, ATP levels declined significantly during postharvest fruit senescence and were correlated with the decrease in the proportion of edible fruit. The five gene transcripts isolated from the litchi fruit pericarp were highly expressed in vegetative tissues and peaked at 70 days after flowering (DAF) consistent with fruit ADP concentrations, except for uncoupling mitochondrial protein 1 (UCP1), which was predominantly expressed in the root, and ATP synthase beta subunit (AtpB), which was up-regulated significantly before harvest and peaked 2 days after storage. These results indicated that the color-breaker stage at 70 DAF and 2 days after storage may be key turning points in fruit energy metabolism. Transcript abundance of alternative oxidase 1 (AOX1) increased after 2 days of storage to significantly higher levels than those of LcAtpB, and was down-regulated significantly by exogenous ATP. ATP supplementation had no significant effect on transcript abundance of ADP/ATP carrier 1 (AAC1) and slowed the changes in sucrose non-fermenting-1-related kinase 2 (SnRK2) expression, but maintained ATP and energy charge levels, which were correlated with delayed senescence. CONCLUSIONS: Our results suggest that senescence of litchi fruit is closely related with energy. A surge of LcAtpB expression marked the beginning of fruit senescence. The findings may provide a new strategy to extend fruit shelf life by regulating its energy level.

[Molecular mechanism of AtGA3OX1 and AtGA3OX2 genes affecting secondary wall thickening in stems in Arabidopsis].

Bioactive gibberellins (GAs) are a type of important plant growth regulators, which play the key roles in multiple processes, such as seed germination, leaf expansion, flowering, fruit bearing, and stem development. Its biosynthesis is regulated by a variety of enzymes including gibberellin 3-oxidase that is a key rate-limiting enzyme. In Arabidopsis, gibberellin 3-oxidase consists of four members, of which AtGA3OX1 and AtGA3OX2 are highly expressed in stems, suggesting the potential roles in the stem development played by the two genes. To date, there are few studies on AtGA3OX1 and AtGA3OX2 regulating secondary wall thickening in stems. In this study, we used the atga3ox1atga3ox2 double mutant as the materials to study the effects of AtGA3OX1 and AtGA3OX2 genes on secondary wall thickening in stems. The results indicated that simulations repression of AtGA3OX1 and AtGA3OX2 genes resulted in significantly reduction of secondary wall thickening of fiber cells, but not that of vessel cells. Three main components (cellulose, hemicelluloses, and lignin) were also dramatically suppressed in the double mutants. qRT-PCR analysis demonstrated that the expressions of secondary wall biosynthetic genes and the associated transcription factors were obviously affected in AtGA3OX1 and AtGA3OX2 double mutant. Therefore, we presume that Arabidopsis AtGA3OX1 and AtGA3OX2 genes might activate the expression of these transcription factors, thus regulate secondary wall thickening in stems. Together, our results provide a theoretical basis for enhancing the lodging resistance of food crops and improving the biomass of energy plants by genetically engineering Arabidopsis AtGA3OX homologs.

[Genetic analysis and molecular mapping of a high-tillering mutant (ht1) in rice.].

A rice (Oryza sativa L.) mutant with a high-tillering capacity, designated as ht1, was found from a japonica rice variety Xindao18. This high-tillering mutant phenotype was stably expressed through successive five self-crossed generations, and the number of tillers in mutants was three times more than that in wild-type rice. Genetic analysis showed that the phenotype of ht1was controlled by a single dominant nuclear gene, temporarily designated as HT1. By means of molecular marker technique, the HT1 gene was mapped to an interval between two SSR markers RM25435 and RM25552 on chro-mosome 10. Through high-resolution linkage analysis, the HT1 gene was further restricted to a 0.1 cM region flanked by two SSR markers RM25523 and RM25532. The physical distance between these two markers is about 130kb.

[Blocking p38MAPK pathway inhibits the proliferation of OT-II cells mediated by splenic dendritic cells].

OBJECTIVE: To investigate the effect of blocking p38 mitogen-activated protein kinase (p38MAPK) pathway on the proliferation of OT-II cells mediated by splenic dendritic cells (DCs). METHODS: Splenic DCs of C57BL/6 mice were purified with anti-CD11c immunomagnetic beads, and OT-II cells were isolated from the splenic of CD4(+)-ovalbumin transgenic mice (OT-IItransgenic mice) by mouse CD4 T cell isolation kits. After being pretreated with SB203580, an inhibitor of p38MAPK, DCs were stimulated with lipopolysaccharides (LPS). Then the expression levels of co-stimulatory molecules (CD80, CD86) and MHCII in DCs, and antigen-presenting ability of DCs treated with the 52-68 fragment of the E alpha-chain of I-E class II molecules (Eα52-68 peptide) were detected by flow cytometry. The protein levels of tumor necrosis factor α (TNF-α), interleukin 1α (IL-1α), interleukin 6 (IL-6) and transforming growth factor ß (TGF-ß) in the culture supernatants were measured by ELISA. The proliferation of OT-II cells which were co-cultured with OVA323-339-treated DCs was analyzed by flow cytometry. RESULTS: The purity of both DCs and OT-II cells reached over 90% after isolation. SB203580 downregulated the expressions of CD80, CD86 and MHC II, and suppressed the antigen-presenting ability of DCs. The expressions of TNF-α, IL-1α and IL-6 were downregulated, while the expression of TGF-ß was raised. Finally, SB203580 inhibited DCs-mediated proliferation of OT-II cells. CONCLUSION: Blocking p38MAPK pathway with SB203580 could inhibit DCs-mediated proliferation of OT-II cells, which might be involved in modulating the expressions of CD80, CD86 and MHC II, the antigen-presenting ability, as well as the expressions of pro-inflammatory and anti-inflammatory cytokines.

[Progresses of study on the DNA locus related to cytoplasmic male sterility and restorer gene for fertility in rapeseed].

CMS in rapeseed is of tremendous importance in its commercial application in hybrid seed production. This review focuses on the progresses of study on CMS in rapeseed from four aspects: (1) the mitochondrial DNA locus found to be associated with CMS, (2) the effects of restorer gene for fertility on the expression of the locus associated with CMS, (3) the mapping with molecular marker and (4) cloning of restorer genes of fertility of the CMS in rapeseed. The prospects of further studies on this subject are discussed.

[Molecular strategies for decreasing the gene flow of transgenic plants].

Transgenic plants can transfer foreign genes through pollen or seed to related plant species. This may cause potential harm to ecological environment. How to decrease the gene flow is drawing a growing public attention. The approaches for decreasing the gene flow include chloroplast transformation, pollen sterility, seed sterility, cleistogamy, apomixis, temporal control, and transgenic mitigation. The theoretical basis, advantages and disadvantages, and usage status of these approaches are presented in this review.

[The application of chloroplast genome transformation in higher plant].

The chloroplast genome transformation of higher plant has become the research hotspot of plant genetic engineering with several advantages over nuclear genetic engineering, and it has become into a powerful approach for both basic and applied research. This paper presents a brief summary for the principle and methods of chloroplast genome transformation in higher plant. The particular emphasis was placed on its application in the basic and applied research. These applications include the studies of rearrangement of Rubisco and the structure, transcription, translation and RNA editing of genes in chloroplast; the producing of antibodies, vaccines, poly-beta-hydroxybutyrate and bio-elastic protein using chloroplast as bioreactor; the generating of transgenic plants with resistance to insect, disease, herbicide and drought; and the decreasing the gene flow of transgenic plants.

[Genetic mechanism and molecular basis of apomixis in plant].

Apomixis allows the establishment of genetically stable seed propagating clones of crops, which can perpetuate themselves across countless sporophytic generations. This asexual mode of reproduction, which naturally occurs in some angiosperms,may prove to be an unrivalled tool to improve crop yields. The current state of knowledge on the molecular and genetic basis of apomixis is reviewed.