Mode of spread to and within the central nervous system after oral infection of neonatal mice with the DA strain of Theiler's murine encephalomyelitis virus.

Theiler's murine encephalomyelitis virus is a neurotropic enterovirus known to cause biphasic neural disease after intracerebral inoculation into adult mice. The present study characterizes a neonatal mouse model with a high disease incidence for the study of the acute phase of the pathogenesis of the DA strain of Theiler's murine encephalomyelitis virus after oral infection. The route of viral spread to and within the central nervous system (CNS) was determined by examining the kinetics of viral replication in various organs and by performing histopathological analysis. Viral antigen was detected widely in the neonatal CNS, mainly in the gray matter, and it was asymmetrical and multifocal in its distribution, with considerable variation in lesion distribution from animal to animal. Necrotizing lesions appeared to expand by direct extension from infected cells to their close neighbors, with a general disregard of neuroanatomical boundaries. The diencephalon showed particular susceptibility to viral infection. Other areas of the CNS, including the cerebellum and dentate gyrus of the hippocampus, were consistently spared. Neurons with axons extending peripherally to other organs or receiving direct input from the peripheral nervous system were not preferentially affected. The kinetics of viral replication in the liver, spleen, and CNS and the histopathological findings indicate that viral entry to the CNS is via a direct hematogenous route in orally infected neonatal mice and that the disease then progresses within the CNS mainly by direct extension from initial foci.     

Identification and analysis of cold stress-inducible genes in Korean rapeseed varieties

The rapeseed plant (Brassica napus) is one of the top five oil-producing crops in the world. However, its potential for global cultivation is limited due to its sensitivity to cold. We selected five varieties of rapeseed popular in Korea and analyzed their sensitivity to cold stress. Three — ‘Naehan’, ‘Sandongchae’, and ‘Yudal’ — proved more tolerant than the other two — ‘Youngsan’ and ‘Tammi’. Because rapeseed is in the same family (Brassicacae) as Arabidopsis, one would expect that both share similar genes, with protein coding sequences that show >86% homology. We used a cDNA microarray enriched with Arabidopsis cold stress-related genes to examine the molecular background for differences in sensitivity among rapeseed varieties. Their hierarchical clustering patterns for expression were highly correlated with their cold-sensitive phenotypes. For example, expression patterns were similar between ‘Naehan’ and ‘Sandongchae’ as well as between ‘Yudal’ and our Arabidopsis samples. Using co-expression gene sets developed in this laboratory, we further analyzed expression patterns for three cultivars. Three distinct gene sets were commonly enriched in ‘Naehan’ against ‘Youngsan’ and ‘Tammi’, indicating that they could be the core gene sets that confer a high degree of cold tolerance in ‘Naehan’. Knockout plants with down-regulated expression of GSTF2, TRXh5, LTI30, and LACS4 were highly cold-sensitive whereas overexpression of those four genes led to a reversal of this sensitivity. In fact, overexpression of GSTF2 and LTI30 enhanced tolerance, with plants that over-expressed GSTF2 having extremely high tolerance that enabled them to acclimate almost completely to freezing conditions. By comparison, only about 40% of the wild type demonstrated a similar acclimation. Therefore, the genes described here could be useful in furthering our knowledge about other stress responses in rapeseed, thereby facilitating the production of cold-tolerant plants.     

Ectopic expression of apple MbR7 gene induced enhanced resistance to transgenic Arabidopsis plant against a virulent pathogen

A disease resistance related gene, MbR7, was identified in the wild apple species, Malus baccata. The MbR7 gene has a single open reading frame (ORF) of 3,288 nucleotides potentially encoding a 1,095-amino acid protein. Its deduced amino acid sequence resembles the N protein of tobacco and the NL27 gene of potato and has several motifs characteristic of a TIR-NBS-LRR R gene subclass. Ectopic expression of MbR7 in Arabidopsis enhanced the resistance against a virulent pathogen, Pseudomonas syringae pv. tomato DC3000. Microarray analysis confirmed the induction of defense-related gene expression in 35S::MbR7 heterologous Arabidopsis plants, indicating that the MbR7 gene likely activates a downstream resistance pathway without interaction with pathogens. Our results suggest that MbR7 can be a potential target gene in developing a new disease-resistant apple variety.     

Analysis of gene expression profiles of gastric normal and cancer tissues by SAGE

In an attempt to understand the molecular bases of gastric cancer progression, we have analyzed the differentially expressed genes in gastric cancer by SAGE. Four SAGE cDNA tag libraries were constructed from two sets of gastric cancer and normal tissues and 241,127 tags were obtained. By comparing the tags from cancer and normal tissues, 414 differentially expressed tags, representing 383 genes, were identified in cancer tissues (p 相似文献