Structural Alteration of the Membrane of Erythrocytes Infected with Plasmodium falciparum1

Human erythrocytes infected with five strains of Plasmodium falciparum and Aotus erythrocytes infected with three strains of P. falciparum were studied by thin-section and freeze-fracture electron microscopy. All strains of P. falciparum we studied induced electron-dense conical knobs, measuring 30–40 nm in height and 90–100 nm in diameter on erythrocyte membranes. Freeze-fracture demonstrated that the knobs were distributed over the membrane of both human and Aotus erythrocytes. A distinct difference was seen between the intramembrane particle (IMP) distribution over the knobs of human and Aotus erythrocyte membranes. There was no change in IMP distribution in infected human erythrocyte membranes, but infected Aotus erythrocytes showed an aggregation of IMP over the P face of the knobs with a clear zone at the base. This difference in IMP distribution was related only to the host species and not to parasite strains. Biochemical analysis demonstrated that a higher proportion of band 3 was bound to the cytoskeleton of uninfected Aotus erythrocytes than uninfected human erythrocytes after Triton X-100 extraction. This may account for the different effects of P. falciparum infection on IMP distribution in the two different cell types.     

Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems

• 1 The genus Castor comprises two species: the Eurasian beaver Castor fiber, and the North American beaver Castor canadensis. Both species suffered from overexploitation, but have seen a revival since the 1920s due to increased protection and reintroduction programmes. Increases in the populations and distributions of species that are able to modify ecosystems have generated much scientific interest. Here we review the available literature concerning the possible ecological impact of beaver species in the Old and New World.
• 2 Beavers, being ecosystem engineers, are among the few species besides humans that can significantly change the geomorphology, and consequently the hydrological characteristics and biotic properties of the landscape. In so doing, beavers increase heterogeneity, and habitat and species diversity at the landscape scale. Beaver foraging also has a considerable impact on the course of ecological succession, species composition and structure of plant communities, making them a good example of ecologically dominant species (e.g. keystone species).
• 3 Nevertheless, the strength of beavers’ impact varies from site to site, depending on the geographical location, relief and the impounded habitat type. Consequently, they may not be significant controlling agents of the ecosystem in all parts of their distribution, but have strong interactions only under certain circumstances. We suggest that beavers can create important management opportunities in the Holarctic, and this review will help land managers determine the likely outcome of beaver activity.

     

SENSORY DIRECTIONALS FOR PIZZA: A DEEPER ANALYSIS

This paper presents a set of analyses on sensory directional attributes used to rate experimentally designed pizza products. Consumers may or may not know the 'optimal' sensory level of attributes for pizza, so that the usefulness of the sensory directional varies by attribute. Furthermore, the sensory magnitude of each sensory directional attribute varies, as shown by the slope (B) relating the two attributes (Sensory Magnitude = A + B (Directional Rating)). The study incorporated sensory directionals into evaluation of products varied according to an experimental design. The optimal product emerging from the design does not necessarily exhibit a sensory directional profile where all attributes are 'on target', nor does a product whose sensory attributes are all on 'target' exhibit the highest level of liking.     

FOUNDING A NEW SCIENCE: MIND GENOMICS

We present in this article our vision for a new science, modeled on the emerging science of genomics and the technology of informatics. Our goal in this new science is to better understand how people react to ideas in a formal and structured way, using the principles of stimulus–response (from experimental psychology), conjoint analysis (from consumer research and statistics), Internet‐based testing (from marketing research) and multiple tests to identify patterns of mind‐sets (patterned after genomics). We show how this formal approach can then be used to construct new, innovative ideas in business. We demonstrate the approach using the development of new ideas for an electronic color palette for cosmetic products to be used by consumers.     

The effects on a population of potato-root eelworm (Heterodera rostochiensis) of growing potatoes resistant to pathotype B

The effects on a potato-root eelworm (Heterodera rostochiensis Woll.) population of growing potatoes resistant to pathotype B of the eelworm were investigated. The eelworm population, which was originally nearly entirely pathotype A, had been changed into a mixture of pathotypes A, B and C before 1961, when the experiments described in this paper began, by growing potatoes resistant only to pathotype A. The resistant potatoes grown in the years 1961 and 1962 were certain clones of the hybrid triploid species Solarium xjuzepczukii Buk., clones bred from S. multidissectum Hawkes with the gene H₂ and clones bred from S. vernei Bitt. et Wittm. In the years 1963-65 the clone used was D 40 which has both the gene H₂ from Andigena and the gene H₂ from 5. multidissectum and is resistant to both pathotypes A and B of the eelworm. The only potatoes which caused a reduction in the egg population were those bred from S. vernei. The clone D 40, although it had little effect on the egg population, appeared to have more resistance than could be accounted for from possessing genes H₁ and H₂.     

PHYSIOLOGICAL RACES OF PHYTOPHTHORA INFESTANS: A COMPARISON OF THE DIFFERENTIAL HOSTS AT THE PLANT BREEDING INSTITUTE, CAMBRIDGE, WITH THOSE OF THE SCOTTISH SOCIETY FOR RESEARCH IN PLANT BREEDING

At the Plant Breeding Institute, Cambridge, there have been recognized three physiological races of blight ( Phytophthora infestans ), A, B and C ; and at the Scottish Society for Research in Plant Breeding, Edinburgh, there have been used five races, A, B ¹, B ², C and D , obtained in the British Isles.
It is shown that the two Cambridge types of differential hosts, AbC and ABc (where A = resistant to race A, a = susceptible to race A , etc.), are Ab ¹ b ² CD and AB ¹ B ² cD respectively on the Scottish scheme, and that the Cambridge races A, B and C correspond to the Scottish races A, B ¹ and C respectively.
A number of blight isolates were tested on both the Cambridge and Scottish differential hosts. Isolates of race types A, B ¹, B ¹, C and D were found.
The identification and origin of physiological races of blight, and the breeding of blight-resistant potatoes, are discussed.