Restriction endonuclease analysis for the identification of baculovirus pesticides.

Gel electrophoresis of deoxyribonucleic acid (DNA) fragments generated by digesting the DNA genomes of nuclear polyhedrosis viruses (NPV) with restriction endonucleases provides DNA fragment patterns that may be used to identify different viruses of this group. Characteristic fragment patterns were obtained for three NPVs, which are important as biological pesticides (Autographa californica NPV, Orgyia pseudotsugata NPV, and Heliothis zea NPV). The DNA fragment patterns of the A. californica NPV genoms did not change with passage through the alternate insect host, Trichoplusia ni. Heterogeneity in one preparation of O. pseudotsugata NPV was observed. The identification procedure is direct and precise. Applications of this procedure include quality control of commercial preparations of viral pesticides and screening for genetic alterations in the viruses.     

Experimental evaluation of the relationship between lethal or non-lethal virulence and transmission success in malaria parasite infections

Background

Theoretical studies suggest that direct and indirect selection have the potential to cause substantial evolutionary change in female mate choice. Similarly, sexual selection is considered a strong force in the evolution of male attractiveness and the exaggeration of secondary sexual traits. Few studies have, however, directly tested how female mate choice and male attractiveness respond to selection. Here we report the results of a selection experiment in which we selected directly on female mating preference for attractive males and, independently, on male attractiveness in the guppy, Poecilia reticulata. We measured the direct and correlated responses of female mate choice and male attractiveness to selection and the correlated responses of male ornamental traits, female fecundity and adult male and female survival.

Results

Surprisingly, neither female mate choice nor male attractiveness responded significantly to direct or to indirect selection. Fecundity did differ significantly among lines in a way that suggests a possible sexually-antagonistic cost to male attractiveness.

Conclusions

The opportunity for evolutionary change in female mate choice and male attractiveness may be much smaller than predicted by current theory, and may thus have important consequences for how we understand the evolution of female mate choice and male attractiveness. We discuss a number of factors that may have constrained the response of female choice and male attractiveness to selection, including low heritabilities, low levels of genetic (co)variation in the multivariate direction of selection, sexually-antagonistic constraint on sexual selection and the "environmental covariance hypothesis".

     

Aged mother cells of Saccharomyces cerevisiae show markers of oxidative stress and apoptosis

Recently, we and others have shown that genetic and environmental changes that increase the load of yeast cells with reactive oxygen species (ROS) lead to a shortening of the life span of yeast mother cells. Deletions of yeast genes coding for the superoxide dismutases or the catalases, as well as changes in atmospheric oxygen concentration, considerably shortened the life span. The presence of the physiological antioxidant glutathione, on the other hand, increased the life span of yeast cells. Taken together, these results pointed to a role for oxygen in the yeast ageing process. Here, we show by staining with dihydrorhodamine that old yeast mother cells isolated by elutriation, but not young cells, contain ROS that are localized in the mitochondria. A relatively large proportion of the old mother cells shows phenotypic markers of yeast apoptosis, i.e. TUNEL (TdT-mediated dUTP nick end labelling) and annexin V staining. Although it has been shown previously that apoptosis in yeast can be induced by a cdc48 allele, by expressing pro-apoptotic human cDNAs or by stressing the cells with hydrogen peroxide, we are now showing a physiological role for apoptosis in unstressed but aged wild-type yeast mother cells.     

Cell wall structure of the agarophytes Gracilaria tikvahiae and G. cornea (Rhodophyta) and penetration by the epiphyte Ulva lactuca (Chlorophyta)

Use of light, transmission, and scanning electronmicroscopes revealed that the epidermal cell wall ofthe red algal agarophytes Gracilaria tikvahiaeMcLachlan and G. cornea J. Agardh consists of adecklamelle and outer and inner wall layers. The twospecies differed, with G. cornea having asignificantly thicker outer wall and a more diffusedecklamelle. After induction, the zooids of Ulvalactuca would attach to glass slides and the twospecies of Gracilaria via an adhesion pad. Within a few days, 3–5 celled germlings penetrated thedecklamelle and outer wall layer of both basiphytes. By the time the epiphyte germlings reached the 15celled stage, they had penetrated the inner walllayer. The differences in epidermal cell wallconstruction between the two basiphytes may play arole in the ability of zooids of U. lactuca toattach in nature where epiphytization of G.cornea is infrequent.