Oligodendrocyte wars

Oligodendrocyte precursors first arise in a restricted ventral part of the embryonic spinal cord and migrate laterally and dorsally from there. Later, secondary sources develop in the dorsal cord. Normally, the ventrally-derived precursors compete with and suppress their dorsal counterparts. There are also ventral and dorsal sources in the forebrain, but here the more dorsal precursors prevail and the ventral-most lineage is eliminated during postnatal life. How do the different populations compete and what is the outcome of the competition? Do different embryonic origins signify different functional subgroups of oligodendrocyte?     

Cell wars fought with nanoweapons

We consider examples of the recently demonstrated means of attack and defense in the host versus cancer combat at the cellular level that involve interactions between widespread multifunctional proteins Tag7/PGRP-S, Hsp70, and Mts1/S100A4.     

Interactions between tobacco mosaic virus and the tobacco N gene

The interaction between tobacco mosaic virus (TMV) and tobacco harbouring the N gene is a classical system for studying gene-for-gene interactions in disease resistance. The N gene confers resistance to TMV by mediating defence responses that function to limit viral replication and movement. We isolated the N gene and determined that N belongs to the nucleotide-binding-site-leucine-rich-repeat (NBS-LRR) class of plant disease resistance genes, and encodes both full-length and truncated proteins. Sequence homologies and mutagenesis studies indicated a signalling role for the N protein similar to that seen for proteins involved in defence responses in insects and mammals. The N gene confers resistance to TMV in transgenic tomato, demonstrating the use of the NBS-LRR class of disease resistance genes in engineering crop resistance. From the pathogen side of this interaction, the TMV 126 kDa replicase protein has been implicated as the avirulence factor that triggers N-mediated defence responses. We employed Agrobacterium-mediated expression strategies to demonstrate that expression of the putative helicase region of the replicase protein is sufficient to elicit N-mediated defences. The thermosensitivity of the N-mediated response to TMV is retained when induced by expression of this replicase fragment. Thus, both components of this gene-for-gene interaction are now available for studies that address the molecular mechanisms involved in N-mediated TMV resistance.     

Tobacco wars: the bloody battle between good health and good politics

A battle to introduce new antitobacco legislation in Canada has caused political battles within the Liberal Party. While one side is worried about the need to protect people''s health, another is worried about the potential loss of jobs within the tobacco industry--many of which are located in politically volatile Quebec. Charlotte Gray writes about the machinations that led to the introduction of new smoking legislation in the House of Commons in November.