Dynamics of proteins in Golgi membranes: comparisons between mammalian and plant cells highlighted by photobleaching techniques

In less than a decade the green fluorescent protein (GFP) has become one of the most popular tools for cell biologists for the study of dynamic processes in vivo. GFP has revolutionised the scientific approach for the study of vital organelles, such as the Golgi apparatus. As Golgi proteins can be tagged with GFP, in most cases without altering their targeting and function, it is a great substitute to conventional dyes used in the past to highlight this compartment. In this review, we cover the application of GFP and its spectral derivatives in the study of Golgi dynamics in mammalian and plant cells. In particular, we focus on the technique of selective photobleaching known as fluorescence recovery after photobleaching, which has successfully shed light on essential differences in the biology of the Golgi apparatus in mammalian and plant cells.     

The turnover of F-actin-bound ADP in vivo.

A procedure for estimating the rate of turnover of F-actin-bound ADP in vivo is described. A turnover rate of 0.88 h-1 was determined for mouse muscle F-actin. The validity of the method when used to estimate the turnover rate of F-actin per se is discussed in relation to the possible exchange of F-actin-bound ADP.     

Microfabrication technology: organized assembly of carbon nanotubes

Nanoscale structures need to be arranged into well-defined configurations in order to build integrated systems. Here we use a chemical-vapour deposition method with gas-phase catalyst delivery to direct the assembly of carbon nanotubes in a variety of predetermined orientations onto silicon/silica substrates, building them into one-, two- and three-dimensional arrangements. The preference of nanotubes to grow selectively on and normal to silica surfaces forces them to inherit the lithographically machined template topography of their substrates, allowing the sites of nucleation and the direction of growth to be controlled.     

Linkage disequilibrium in the human genome

With the availability of a dense genome-wide map of single nucleotide polymorphisms (SNPs), a central issue in human genetics is whether it is now possible to use linkage disequilibrium (LD) to map genes that cause disease. LD refers to correlations among neighbouring alleles, reflecting 'haplotypes' descended from single, ancestral chromosomes. The size of LD blocks has been the subject of considerable debate. Computer simulations and empirical data have suggested that LD extends only a few kilobases (kb) around common SNPs, whereas other data have suggested that it can extend much further, in some cases greater than 100 kb. It has been difficult to obtain a systematic picture of LD because past studies have been based on only a few (1-3) loci and different populations. Here, we report a large-scale experiment using a uniform protocol to examine 19 randomly selected genomic regions. LD in a United States population of north-European descent typically extends 60 kb from common alleles, implying that LD mapping is likely to be practical in this population. By contrast, LD in a Nigerian population extends markedly less far. The results illuminate human history, suggesting that LD in northern Europeans is shaped by a marked demographic event about 27,000-53,000 years ago.