Resistance to cucumber mosaic virus in potato

Reactions to two subgroup I isolates (Fny-CMV and Pf-CMV) and two subgroup II isolates (A9-CMV and LS-CMV) of cucumber mosaic virus (CMV) were studied in three non tuber-bearing wild potato species (Solanum spp.) of the series Etuberosa, and in two tuber-bearing interspecific potato hybrids and four potato cultivars using graft-inoculation. Three classes of phenotypic reactions (susceptible, hypersensitive, extreme resistance) were observed in the tuber-bearing genotypes. Susceptible genotypes developed mosaic or severe mosaic with leaf malformation and had high CMV titres. Hypersensitive genotypes developed either top necrosis or vein necrosis and/or necrotic spots on apical leaves, and had low CMV titres. Extremely resistant genotypes had no symptoms and no CMV was detected. The hybrid 87HW13.7 (S. tuberosum×S. multidissectum) developed top necrosis specific to infection with Fny-CMV. The hybrid ‘A6’ (S. demissum×S. tuberosum cv. Aquila) was hypersensitive to all CMV isolates tested. Extreme resistance was not functional against all CMV isolates. Neither hypersensitivity nor extreme resistance were related to the CMV subgroup.     

THE RELATIONSHIP BETWEEN CELL-SUBSTRATE ADHESIVENESS AND CELL GROWTH: A STUDY ON CHONDROCYTES CULTURED IN VITRO WITH CONDITIONED MEDIUM

Sparsely cultured chondrocytes from the sternae of 14-day chick embryos grew vigorously with a liquid medium using Falcon tissue culture dishes, when the conditioned medium (CM) prepared from the high-density cultures of neural retinae was used as a growth medium. In CM most cells adhered to the culture substrate, while in the fresh medium, in which cell growth was very slow, many viable cells remained unattached to the substrate. Enhancement of cell growth by CM was much less marked in cultures of chondrocytes suspended in agarose. The main effect of CM in enhancing cell growth is thus considered to be related to the increase of cell adhesiveness to the substrate. The main active factor in CM is non-dialyzable and heat-stable.     

Turnover of cell wall polysaccharides of a Vinca rosea suspension culture

Three-day-cultured cells of Vinca rosea L. (in the cell division phase) and 5-day-cultured cells (in the cell expansion phase) prelabelled with d -[U-¹⁴C] glucose were incubated in a medium containing unlabelled glucose. After various periods of chase, extra-cellular polysaccharides (ECP) and cell walls were isolated, and cell walls were fractionated into pectic substances, hemicellulose, and cellulose fractions. After acid hydrolysis, the radioactive constituents in the pectic substances and hemicellulose fractions were analyzed. Active turnover was observed in arabinose and galactose in the hemicellulose fraction of cell walls, while the constituents of the pectic substances, and xylose and glucose in the hemicellulose fraction did not undergo active turnover. The proportion of radioactivities of arabinose and galactose in total radioactivity of ECP increased markedly after chasing. These results indicate that arabinogalactan was synthesized, deposited in the cell wall, degraded rapidly, and made soluble in the medium as a part of ECP.     

Effects of Glutaraldehyde and Osmium Tetroxide on Hypotrichous Ciliates, and Determination of the Most Satisfactory Fixation Methods for Electron Microscopy

SYNOPSIS. In electron microscope studies on hyppotrichous ciliates, cytolysis and/or body deformation–resulting from insufficient contact with glutaraldehyde and poor infiltration of Epon 812, particularly into the buccal cavity, usually were observed. Fixation experiments were carried out to examine the effects of some fixatives on Euplotes eurystomus, Oxytricha bifaria and Stylonychia mytilus to establish the best fixation technic applicable to all species of hypotrichous ciliates. Although the effects of fixation varied considerably with the species, 2 fully satisfactory fixation methods were developed by using OsO₄ and glutaraldehyde. In one, a mixture of both fixatives was employed; in the other a very short application of OsO₄ was followed by glutaraldehyde. The problem of infiltration was solved by using Spurr's low-viscosity embedding medium in place of Epon 812.     

IMMUNOCHEMICAL STUDY ON THE SPECIES SPECIFICITY OF SPERM-BINDING PROTEIN FROM THE SURFACE OF THE SEA URCHIN EGG*

Immunological species specificity of sperm-binding protein from eggs of the 4 sea urchin species, Hemicentrotus pulcherrimus, Pseudocentrotus depressus, Anthocidaris crassispina and Temnopleurus toreumaticus, was examined by means of double immuno-diffusion technique in agar. Ca-soluble fraction of sperm-binding protein which is considered to be responsible for initial sperm-egg bonding at fertilization, has species-specific antigenic component. Correlations in antigenic constituents among the 4 species are described.     

Minor carotenoid components in the chloroplasts of higher plants

One-dimensional thin layer chromatography with microcrystallinecellulose was used for the separation of minor carotenoid componentsin spinach, parsley and Brassicachloroplasts. It was revealedthat chloroplasts of these plants contain two minor xanthophyllcomponents besides carotenes, lutein, violaxanthin and neoxanthin.These minor components, designated as xanthophyll–443and –439, were different in spectral properties from antheraxanthinand zeaxanthin which are known to be present in the chloroplastsof some higher plants, and evidence was obtained showing thatxanthophyll–439 has an epoxy group. Spectral propertiesof these xanthophylls in benzene, ethanol, H-hexane and carbondisulfide, as well as their contents relative to other carotenoids,are presented in this paper. ¹Postal address