Somaclonal variation does not preclude the use of rice transformants for genetic screening.

Rice (Oryza sativa) is one of the world's most important crops. Rice researchers make extensive use of insertional mutants for the study of gene function. Approximately half a million flanking sequence tags from rice insertional mutant libraries are publicly available. However, the relationship between genotype and phenotype is very weak. Transgenic plant assays have been used frequently for complementation, overexpression or antisense analysis, but sequence changes caused by callus growth, Agrobacterium incubation medium, virulence genes, transformation and selection conditions are unknown. We used high-throughput sequencing of DNA from rice lines derived from Tainung 67 to analyze non-transformed and transgenic rice plants for mutations caused by these parameters. For comparison, we also analyzed sequence changes for two additional rice varieties and four T-DNA tagged transformants from the Taiwan Rice Insertional Mutant resource. We identified single-nucleotide polymorphisms, small indels, large deletions, chromosome doubling and chromosome translocations in these lines. Using standard rice regeneration/transformation procedures, the mutation rates of regenerants and transformants were relatively low, with no significant differences among eight tested treatments in the Tainung 67 background and in the cultivars Taikeng 9 and IR64. Thus, we could not conclusively detect sequence changes resulting from Agrobacterium-mediated transformation in addition to those caused by tissue culture-induced somaclonal variation. However, the mutation frequencies within the two publically available tagged mutant populations, including TRIM transformants or Tos17 lines, were about 10-fold higher than the frequency of standard transformants, probably because mass production of embryogenic calli and longer callus growth periods were required to generate these large libraries.

Inflammatory mediators of cerebrospinal fluid from patients with spinal cord injury.

BACKGROUND: The guidelines of MP treatment for acute SCI are still under debate. We examined the inflammatory mediators of CSF in patients with SCI and assessed the effect of MP treatment. METHODS: We studied 7 patients with acute SCI at the cervical level and examined the mediators of CSF in patients by cytokine antibody array, ELISA and gelatin zymography. RESULTS: We found that levels of IL-6, IL-8, monocyte chemoattractant protein-1, neutrophil-activating peptide 2, intracellular adhesion molecule-1, soluble Fas, tissue inhibitors of metalloproteinase 1, and matrix metalloproteinases-2 and -9 were upregulated in patients with complete SCI without MP treatment as compared to patients with MP treatments, incomplete SCI, or controls. Nerve growth factor was upregulated in patients with MP treatment. CONCLUSIONS: We suggest that a neuroinflammatory CSF profile after complete SCI could be suppressed with MP treatment via downregulating the expression of various cytokines.

Both Hd1 and Ehd1 are important for artificial selection of flowering time in cultivated rice.

Rice is a facultative short-day plant, and it requires a photoperiod shorter than the critical day length to get flowering. Sensitivity to photoperiod has been suggested as a major selection target in cultivated or weedy rice. The modern rice varieties in Taiwan may be cultivated twice a year. These varieties contain loss-of-function of two important flowering-time related genes, Heading date 1 (Hd1) and Early heading date 1 (Ehd1), and are mainly from a mega variety, Taichung 65. However, the parental lines of this variety were sensitive to photoperiod, thus, how Taichung 65 loss its sensitivity is a mystery. In this study, we used accession-specific single nucleotide polymorphism analysis to reveal the gene flow that occurred between different rice accessions decades ago and demonstrate that two landraces introgressed during the breeding process, which led to the loss of photoperiod sensitivity. Both Hd1 and Ehd1 may be important during artificial selection for flowering time, especially in a subtropical region such as Taiwan. This is a good example of introgression playing important roles during rice domestication.