Activité néformatrice d'acides ribonucléiques extraits de tumeurs végétales

RNAs extracted from crown-gall tumors, induced by Agrobacterium tumefaciens (strain B6) on stems of Datura stramonium L., have been isolated by the phenol method and purified through Biogel P 60 columns. These RNAs have been transformed into complexes with l -amino acids by incubation in a medium containing: Tris HCI buffer, pH 7.6, ATP, MgCl₂, a mixture of l -amino acids and a polypeptide synthetase purified from Alcaligenes faecalis. The inoculation of stems of Datura plants with these complexes induces the development of nodular outgrowths, whereas other complexes made from RNAs isolated from healthy Datura plants, from Agrobacterium tumefaciens, Escherichia coli and Alcaligenes faecalis do not cause any hyperplasia under our experimental conditions. The analysis of the results obtained, supported by histological studies of the outgrowths, suggests that these neoformations should be of tumoral nature.     

Studies on the Conditions Required for Optimum Recovery of Tetrahymena pyriformis Strain S (Phenoset A) after Freezing to and Thawing from –196 C

The toxicity of several cryoprotective agents was tested at room temperature (23 C) against Tetrahymena pyriformis strain S (Phenoset A) at different stages of the growth cycle. Polyvinylpyrrolidone (PVP-40) at 10% (v/v) concentration was without effect at any stage in the growth cycle, while 1.2 M glycerol immobilized the cells which were disrupted very shortly afterwards. The toxicity of 0.25 M glucose was largely independent of the position of the cells in the growth cycle, but the toxicity of 0.25 M sucrose and 1.4 M dimethylsulfoxide (DMSO) was most marked in late log- and stationary-phase cells. After log-phase cells had been equilibrated with 1.4 M DMSO for 1 hr, the number of cells surviving cooling at defined rates from 0.45 to 12 C/min decreased as the final temperature decreased from –30 to –60 C. A temperature of –53 C was found to be the optimum from which cells cooled at a given rate could be cooled rapidly to –196 C. Nevertheless, when cells were cooled at defined rates to –35, –45, or –53 C and then rapidly to –196 C the optimum rate of cooling to these temperatures was found to be 1 C/min. The optimum rate of cooling to –60 C prior to plunging into liquid nitrogen was found to be 2.7 C/min.     

Effect of Light on Deamination and Oxidation of Adenylic Compounds in Cotyledons of Pharbitis nil

Since labelling of ureides from adenine-8-¹⁴C is higher in dark than in light, the influence of light on the deamination and the oxidation of adenylic compounds by cotyledon discs of Pharbitis nit was investigated. Among the three possible adenylic precursors for the deaminative step, adenine was found to be the best compound for the study of the deaminative rate, adenosine being easily hydrolyzed into adenine, and AMP undergoing an apparent complete hydrolysis before entering the cells. By analysis of adenine-8-¹⁴C metabolism for brief periods, it was determined that the rate of deamination of adenylic compounds was faster in light than in dark. In contrast, the activity of xanthine dehydrogenase was much higher in the dark than in light. The level of the activity of uricase was the same in both light and dark.     

Benthic ecology of a spring-fed river of interior Alaska

1. A massive aquifer between the Gerstle, Tanana and Delta rivers in interior Alaska receives water from them and from smaller streams that flow from the Granite Mountains in the Alaska Range, Groundwater from the aquifer intersects the surface in a mid-sized (20m³s^?1× 10%) spring-fed stream, Clearwater Creek. 2. Mean annual air temperature is about -2.6°C. However, even in winter when air temperature often reaches —40°C, the stream does not form a complete ice cover. Water temperature ranges from 0 to 7.8°C. Specific conductance and the concentrations of major ions vary little throughout the year, and summed ionic salinity exceeds 250 mg1-^?1. 3. Benthic algal standing crop (as chlorophyll a) was at least an order of magnitude higher than that in a nearby surface-water stream, the upper Chena River, Standing crop peaked in spring and autumn (about 20mgm^?2) and averaged about half this value, although biomass of an early spring bloom of Hydrurus foetid us was underestimated. 4. Algal standing crop was inversely related to the concentrations of inorganic nitrogen and orrhophosphate-phosphorus in the water column. The ratio of total nitrogen to total phosphorus (as mass concentrations) was always about 30. Measurements of primary production made in Clearwater Creek were among the highest reported for streams in subarctic Alaska. 5. Macroinvertebrate diversity in Clearwater Creek was low. Numbers of ‘morpho-species’ in monthly Surber samples (0.09m²) averaged nine, and ranged from three to fourteen. However, benthos and drift densities were similar to those reported from other Alaskan streams. In early spring and autumn, drifting macroinvertebrates were primarily Ephemeroptera, Plecoptera and Trichoptera, but in summer, Diptera dominated the drift. The low diversity of macroinvertebrates is hypothesized to be a consequence of the small annual range in water temperature and the relatively constant discharge of Clearwater Creek.     

Role of β1 Integrins in Cell Spreading and Migration of Human Nevomelanocytes and Dysplastic Nevi Cells on Collagen Type IV and Laminin

We characterized β1 integrin subunit expression on three different cultures of benign human nevomelanocytes (NMC) and on four different cell cultures of human dysplastic nevus (DN) cells by flow cytometry analysis and examined their role in mediating cell spreading and migration on collagen type IV (CN IV) and laminin (LN) coated substrates by using a quantitative video image analysis system. The seven human NMC and DNC cultures expressed heterogeneous levels of β1, α2, α3 and α6 integrin subunits. Image analysis showed that a significant increase (P<0.001) in cell spreading and migration of the DN cells was induced on increasing coating concentrations of CN IV and LN. However, the NMC did not show an increase in cell spreading or migration on these substrates when compared to the substrates coated with denatured BSA only. The CN IV-induced cell spreading of the DN cells was significantly inhibited by anti-β1 mAb (AIIB2), anti-α2 mAb (P1E6), or anti-α3 mAb (P1B5), but not by mAb against α6 integrin subunit (GoH3). The DN cell spreading on LN was not significantly inhibited by these mAbs. In contrast, the migration of the DN on CN IV and LN was significantly inhibited by anti-β1 mAb, anti-α2 mAb, anti-α3 mAb and anti-α6 mAb. These data suggest that the α2 and α3 subunit are important for cell spreading of the DN on CN IV, although they are less important in cell spreading on the extracellular matrix component LN. The α2, α3 and α6 integrin subunits are important for the migration of DN cells on both CN IV and LN.     

USING HIGH-LEVEL CONSUMER-RESEARCH METHODS TO CREATE A TOOL-DRIVEN GUIDEBOOK AND DATABASE FOR PRODUCT DEVELOPMENT AND MARKETING

We present aspects and data for a tool‐driven database for marketing and product development, which are publicly accessible. The objective is to create a method whereby knowledge of concepts and products can be archived using overviews of a specific product category. The first phase of the database comprises systematic analysis of product concepts, which contain elements dealing both with features and emotions. The concept phase provides an idea about responses to statements about product features, along with responses to emotional elements and brands. The second phase comprises an analysis of the competitive frame of products, even before systematic product development is initiated. This second phase identifies expected and thus reasonable ranges of product‐sensory features, levels of acceptance of typical products, relations between liking and sensory attributes and segmentation of sensory preferences. Together, the two phases provide a guide to product developers new in a category, archive current knowledge and provide a sourcebook for marketers and developers alike, which is accessible using research tools. The two phases allow product development to become more scientific, more based on common experience rather than individual expertise and thus more efficient, without compromising corporate knowledge of specific ingredients, processes or business opportunities.     

Molecular evidence for the hybrid origin of a new endemic species of Stylosanthes Sw. (Fabaceae) from the Mexican Yucatán Peninsula

Stylosanthes aff. calcicola is a formally undescribed tetraploid species from the Mexican Yucatán Peninsula, showing morphological similarities to the diploid species S. calcicola , but distinct in a number of characters. We used uni- and biparentally inherited molecular markers to infer the hybrid origin of this species in relation to known diploid species of Stylosanthes . Molecular characterization was based on length and/or DNA sequence variation of nuclear sequence-tagged site (STS) markers, the internal transcribed spacer (ITS) region of nuclear rDNA and the trnL intron of chloroplast DNA (cpDNA). Stylosanthes aff. calcicola contains a distinct cpDNA haplotype and nuclear DNA fragment, with closest relationship to the diploid species S. calcicola . In contrast, the DNA sequences of two nuclear loci reveal a closer relationship to the diploid species S. angustifolia , S. hispida , S. humilis , S. leiocarpa and S. viscosa . The majority of the STS markers showed additivity of PCR fragments in S. aff. calcicola , representing the combination of two genetically different genomes. We postulate that S. aff. calcicola is a distinct species of allotetraploid origin that appears to have originated once from hybridization between two divergent genomes, of which the maternal and paternal parent are closely related to, or derived from, a member of the lineages represented by S. calcicola and S. viscosa , respectively.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 140 , 1–13.