A multi-treatment experimental system to examine photosynthetic differentiation in the maize leaf.

BACKGROUND: The establishment of C4 photosynthesis in maize is associated with differential accumulation of gene transcripts and proteins between bundle sheath and mesophyll photosynthetic cell types. We have physically separated photosynthetic cell types in the leaf blade to characterize differences in gene expression by microarray analysis. Additional control treatments were used to account for transcriptional changes induced by cell preparation treatments. To analyse these data, we have developed a statistical model to compare gene expression values derived from multiple, partially confounded, treatment groups. RESULTS: Differential gene expression in the leaves of wild-type maize seedlings was characterized using the latest release of a maize long-oligonucleotide microarray produced by the Maize Array Project consortium. The complete data set is available through the project web site. Data is also available at the NCBI GEO website, series record GSE3890. Data was analysed with and without consideration of cell preparation associated stress. CONCLUSION: Empirical comparison of the two analyses suggested that consideration of stress helped to reduce the false identification of stress responsive transcripts as cell-type enriched. Using our model including a stress term, we identified 8% of features as differentially expressed between bundle sheath and mesophyll cell types under control of false discovery rate of 5%. An estimate of the overall proportion of differentially accumulating transcripts (1-pi0) suggested that as many as 18% of the genes may be differentially expressed between B and M. The analytical model presented here is generally applicable to gene expression data and demonstrates the use of statistical elimination of confounding effects such as stress in the context of microarray analysis. We discuss the implications of the high degree of differential transcript accumulation observed with regard to both the establishment and engineering of the C4 syndrome.

Effects of moxibustion on cellular immunocompetence of gamma-irradiated mice.

The effects of moxibustion on cellular immunocompetence of gamma-irradiated mice were investigated in this study. A total of 240 male young mice (ICR strain), 6-8 weeks of age, were chosen and divided into three groups. Group A was the normal control. Group B, the experimental control, was treated with 400 rad whole body gamma-irradiation. Group C, the experimental group, was treated with moxibustion (MT) after being exposed to gamma-irradiation. Six to eight mice from each group were sacrificed on days 1, 5, 12, 19, 26 and 33 post-irradiation. The body and splenic weights of mice in each group were measured. The cellular immunocompetence was measured by 3H-thymidine uptake in each experimental mouse. The results revealed that 400 rad of gamma-ray irradiation inhibited the increase of body and splenic weights, and exerted a pronounced inhibitory effect on the incorporative rates of 3H-thymidine after being stimulated by mitogens such as PHA, PWM, Con A and LPS in the splenic lymphoid cells. MT seemed to help the recovery of the cellular immunocompetence in the gamma-ray irradiated mice.