Aluminum Tolerance in Wheat (Triticum aestivum L.) (I. Uptake and Distribution of Aluminum in Root Apices).

We investigated the uptake and distribution of Al in root apices of near-isogenic wheat (Triticum aestivum L.) lines differing in Al tolerance at a single locus (Alt1: aluminum tolerance). Seedlings were grown in nutrient solution that contained 100 [mu]M Al, and the roots were subsequently stained with hematoxylin, a compound that binds Al in vitro to form a colored complex. Root apices of Al-sensitive genotypes stained after short exposures to Al (10 min and 1 h), whereas apices of Al-tolerant seedlings showed less intense staining after equivalent exposures. Differential staining preceded differences observed in either root elongation or total Al concentrations of root apices (terminal 2-3 mm of root). After 4 h of exposure to 100 [mu]M Al in nutrient solution, Al-sensitive genotypes accumulated more total Al in root apices than Al-tolerant genotypes, and the differences became more marked with time. Analysis of freeze-dried root apices by x-ray microanalysis showed that Al entered root apices of Al-sensitive plants and accumulated in the epidermal layer and in the cortical layer immediately below the epidermis. Long-term exposure of sensitive apices to Al (24 h) resulted in a distribution of Al coinciding with the absence of K. Quantitation of Al in the cortical layer showed that sensitive apices accumulated 5- to 10-fold more Al than tolerant apices exposed to Al solutions for equivalent times. These data are consistent with the hypothesis that Alt1 encodes a mechanism that excludes Al from root apices.

An entomopoxvirus from Oncopera alboguttata (Lepidoptera: Hepialidae) in Australia.

A new entomopoxvirus has been isolated from field-collected larvae of Oncopera alboguttata at Ebor, New South Wales, Australia. The ovoid proteinaceous virus-containing bodies measured about 8 x 6 microns and contained up to about 17 centrally-embedded virus-free spindles and up to about 180 occluded virus particles. The virus particle had a beaded outer membrane and measured about 390 x 270 x 230 nm. The particle contained a single lateral body and a unilaterally concave core which in longitudinal section measured 320 x 80 nm. Dissolution of inclusion body and spindle protein to release virus particles occurred in carbonate/thioglycollate buffer at pH greater than 12.0. It is postulated that this virus has recently evolved from similar viruses in soil inhabiting coleopteran larvae.

Comparative ultrastructural studies of insect granulosis and nuclear polyhedrosis viruses.

Optical diffraction studies indicated that the periodic lattice structure in electron micrographs of the capsids of two granulosis and two nuclear polyhedrosis viruses were indistinguishable. The capsid is composed of stacked rings spaced 4-5 nm apart. Comparison of the intracellular forms of Bombyx mori nuclear polyhedrosis virus with negatively stained virus particles leads to encourage the more general use of the term 'capsid' instead of 'intimate membrane' and the term 'virus membrane' in place of 'developmental membrane'. These terms are consistent with those currently used for most animal and plant viruses.

Electron microscopy of the lysis of Staphylococcus aureus cell walls by Aeromonas lytic factor.

Isolated and purified cell walls of Staphylococcus aureus were treated with a purified fraction of the culture supernatant fluid of a species of Aeromonas. The course of lysis of the cell walls was followed over a period of time by examination of samples under an electron microscope. The undifferentiated cell wall was rapidly digested, but the equatorial rings were more resistant. The undifferentiated cell wall became a very thin sheet before completely dissolving, leaving a series of equatorial rings of various widths. As digestion proceeded, solubilization of the entire cell wall occurred. Analogous findings were obtained with purified S. aureus mucopeptide. It is concluded that the Aeromonas lytic principle is an enzyme, and that susceptible bonds are more concentrated in the undifferentiated cell wall mucopeptide.