Previous electron-microscopic imaging has shown high RNA polymerase occupation densities in the 16S and 23S encoding regions and low occupation densities in the noncoding leader, spacer, and trailer regions of the rRNA (rrn) operons in E. coli. This indicates slower transcript elongation within the coding regions and faster elongation within the noncoding regions of the operon. Inactivation of ...

Hu and Schmidhalter (2008) conducted a study with wheat seedlings growing in saline and non-stressed (control) conditions with the aim of identifying and quantifying the cellular basis for the reduction in leaf growth. We applaud their goals as salinity is an important issue for plant ecology and food production; however, we have concerns about the methodology used and the subsequent conclusion...

To understand how auxin regulates root growth, we quantified cell division and elemental elongation, and examined actin organization in the primary root of Arabidopsis thaliana. In treatments for 48 h that inhibited root elongation rate by 50%, we find that auxins and auxin-transport inhibitors can be divided into two classes based on their effects on cell division, elongation and actin organiz...

The effects of gibberellic acid on the longevity and elongation of variously aged, debladed petioles of Coleus blumei were studied, with particular reference to the hypotheses 1) that auxin increases longevity by increasing growth, and 2) that gibberellic acid acts by increasing the endogenous levels of auxin.Gibberellic acid, substituted for the leaf blades, significantly decreased longevity o...

Heart cell-conditioned medium supports extensive neurite outgrowth from dissociated parasympathetic neurons of the chicken embryo ciliary ganglion. We have shown previously that neurite outgrowth in this system depends on the deposition of a substratum-conditioning factor from conditioned medium onto the polyornithine culture substratum. However, in the presence of only the substratum-bound mat...

The formulation and numerical solution of a continuum (PDE) model of neurite elongation is presented. This model describes elongation as a function of the production, transport and (dis)assembly of tubulin into microtubules in a single growing neurite. It provides an important extension to previous ordinary di4erential equation models of neurite elongation by allowing the incorporation of prote...

T-2 toxin, a mycotoxin produced by Fusarium tricinctum, inhibited elongation of excised hypocotyl sections of Glycine max var. Hawkeye 63. Auxin-promoted elongation was inhibited more severely than was control elongation, and a 1 hour preincubation of 5 mum toxin prevented the induction of a faster rate of elongation by auxin. While the inhibition of elongation by cytokinin was similar to that ...

Hu and Schmidhalter (2008) conducted a study with wheat seedlings growing in saline and non-stressed (control) conditions with the aim of identifying and quantifying the cellular basis for the reduction in leaf growth. We applaud their goals as salinity is an important issue for plant ecology and food production; however, we have concerns about the methodology used and the subsequent conclusion...

Myxococcus xanthus tgl mutants lack social motility and type IV pili but can be transiently stimulated to swarm and to make pili by contacting tgl+ cells. The absence of pili in tgl mutants is shown not to be due to the absence of pilin. The rate of pilus elongation after Tgl stimulation is shown to be similar to the rate of pilus elongation in wild-type cells, using a new more rapid assay for ...