Leaf expansion of four sunflower (Helianthus annuus L.) cultivars in relation to water deficits. II. Diurnal patterns during stress and recovery

Abstract. Leaf expansion of four sunflower cultivars ( Helianthus annuus L. cvs. Hysun 31, Havasupai, Hopi and Seneca) was monitored continuously in a growth cabinet through the final stages of a drying cycle and then throughout the first 2 days after rewatering in order to study the responses of leaf expansion to water deficits. Comparable plants were also measured throughout a diurnal cycle in a glasshouse.
In the cabinet, leaf extension was faster in the dark than in the light, but an extended dark period suppressed leaf extension. At similar leaf water potentials, the rate of leaf extension was greater in the light than in the dark, but as the osmotic potential was lower in the light than in the dark, the relationship between turgor pressure and leaf extension rate was similar in both environments. Throughout the drying and recovery cycles turgor and leaf extension rate was positively correlated: no significant differences among cultivars were observed.
In the plants grown and measured in the glasshouse, leaf expansion occurred at lower leaf water potentials in stressed than in unstressed plants, but the relationship between leaf expansion and turgor was similar in both stressed and unstressed plants as a result of a lowering of the osmotic potential in the former. Diurnal turgor maintenance resulting from osmotic adjustment was almost half that occurring during a complete drying cycle. During the day, the leaf expansion rate increased linearly with turgor pressure in all cultivars: the expansion rate per unit turgor pressure was greater in the glasshouse than in the growth cabinet. Nocturnal leaf expansion in the stressed and unstressed plants was not, however, correlated with turgor pressure.     

On the Chemical Composition and Developmental Role of the Mesoglea of Hydra

Two aspects of the chemistry and function of the mesoglea ofhydra were studied, (i) Chemical composition: Its componentneutral sugars and amino acids were analyzed to determine ifthis structure contains collagen, (ii) Role in morphogenesis:Hydra were exposed to the lathyrogen 3-aminopropionitrile, aninhibitor of collagen crosslinking, to discover if new cross-linkedmesoglea is required for normal regeneration to occur. Large amounts of the neutral sugars glucose and galactose andsmall amounts of fucose and rhamnose were found, as was theamino sugar glucosamine. Evidence that the major protein componentof the mesoglea is collagen was revealed by the detection ofhydroxylysine, hydroxyproline, and proline, and of large amountsof glycine. The glucose and galactose are joined as a dimerby an alkali-stable bond to the polypeptide backbone of thecollagen. The lathyrogen 3-aminopropionitrile, known to block the assemblyof newly synthesized collagen into fibers, causes abnormal headregeneration in hydra. The drug has its maximum effect between24 and 48 hr after the previous head is removed.     

Effect of Type of Carbohydrate on Growth and Protein Synthesis by Tetrahymena pyriformis

SYNOPSIS. In chemically defined media at carbohydrate concentrations ≧ 0.5% (w/v) Tetrahymena pyriformis W multiplied more rapidly, developed larger cells, and achieved greater growth as measured by optical density when carbohydrate was provided as dextrin rather than glucose. In media containing 0.3 mg/ml of amino acid nitrogen, growth increased with glucose concentration from 0.1 to 1%, did not change significantly to 3%, and was sharply inhibited at higher glucose levels. With dextrin, maximum growth paralleled carbohydrate concentration from 0.1 to 3%. At higher N levels the inhibitory concentration of glucose was lowered, but growth in dextrin media was not affected except at N concentrations that were inhibitory independent of carbohydrate source. At 1% carbohydrate levels, total cell protein per ml of culture was 60% greater, protein per cell approximately 50% greater, and cells were 1.5 to 2 times larger in media with dextrin than with glucose. Comparable differences in protein synthesis were observed at 2% carbohydrate levels and efficiency of conversion of substrate-N to protein-N was greater in the medium with dextrin than glucose.
Growth as measured by optical density in media with 0.3 mg/ml of N and 1 or 2% (w/v) of dextrin was not significantly reduced by the simultaneous presence of 1 or 2% glucose. This observation appeared to negate osmotic pressure as an explanation of reduced growth in the presence of glucose. At higher osmolar concentrations osmotic pressure appeared to be a major determinant of overall growth but not of cell size.     

Quantitative Studies on the Growth of Allogromia laticollaris (Foraminifera)

SYNOPSIS. The growth and reproduction of Allogromia laticollaris was studied. More schizozoites were generally produced in mixtures of food organisms than on single algal foods. In the presence of moderate numbers of bacteria, cultures with Phaeodactylum tricornutum, Chlorococcum sp., Nannochloris sp., and an unidentified chlorophyte (BL-1), added singly, were also highly productive. Schizogony was the dominant asexual form of reproduction. Binary fission and cytotomy also occurred in bacterized otherwise unfed controls. ³⁵S and ³²P are convenient labels for measuring growth of A. laticollaris when introduced into the system in the range of 1 × 10⁴ - 1 × 10⁵ dpm/ml (³²P specific activity ～ 2.03 MCi/g; ³⁵S specific activity ～ 95 μCi/g). Small allogromiids grew faster than did larger ones. By means of the Taylor series modification of the classical least-squares method, a continuous life-cycle representation was calculated for A. laticollaris for the conditions of the experiment. Four points of cell volume growth were maxima for reproduction: 1.0 × 10⁷μ per organism for curve I; 2.2 × 10⁷μ³ and 1.2 × 10⁷μ³ for curve II; and 6.7 × 10⁷μ³ for curve III.     

THE EARLY JURASSIC AMMONITE BADOUXIA FROM BRITISH COLUMBIA, CANADA

Abstract:  Most species of the Lower Jurassic ammonite genus Badouxia are restricted to the eastern Pacific where they are of fundamental importance to the Hettangian/Sinemurian ammonite zonation of North America. The fauna from the type area for the genus has been restudied and four species and two transitional forms are now recognized. Badouxia forticostata and Badouxia castlensis are new. Badouxia occidentalis (Frebold) and Badouxia oregonensis Taylor are placed in synonymy with Badouxia canadensis (Frebold). These major taxonomic changes and subsequent modification to the range of B . canadensis require revisions to the current zonation for the Western Cordillera of North America. The Oregonensis Zone is re-named the Mineralense Zone. The Canadensis Zone is abandoned and its previously defined Rursicostatum and Columbiae subzones are elevated to the level of full zones. Large samples indicate that most species of Badouxia display a remarkable range of continuously variable morphology. In addition, the genus shows some of the best-documented evidence of sexual dimorphism in Early Jurassic ammonites. Badouxia spans the Hettangian/Sinemurian boundary and based on the range of different species, five stratigraphic intervals are recognized. Intervals 1–3 correlate with the north-west European Angulata Zone. The majority of interval 4 and the whole of interval 5 correlate with the north-west European Bucklandi Zone. The age of the base of interval 4 is uncertain.     

Meiotic drive at the Om locus in wild-derived inbred mouse strains

Meiotic drive is an evolutionary force in which natural selection is uncoupled from organismal fitness. Recently, it has been proposed that meiotic drive and genetic drift represent major forces in the evolution of the mammalian karyotype. Meiotic drive involves two types of genetic elements, Responders and Distorters , the latter being required to induce transmission ratio distortion at the former. We have previously described the Om meiotic drive system in mouse chromosome 11. To investigate the natural history of this drive system we have characterized the alleles present at the distorter in wild-derived inbred strains. Our analysis of transmission of maternal alleles in both classical and wild-derived inbred strains indicated that driving alleles are found at high frequency in natural populations and that the existence of driving alleles predates the split between the Mus spicilegus and M. musculus lineages.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 487–492.     

PSYCHOPHYSICAL THINKING IN BUSINESS: PRODUCTS AND CONCEPTS

Psychophysical thinking informs both concept development and product design. With products, the researcher systematically varies ingredients/processes and measures consumer reactions such as acceptance and sensory impressions. The product data generate a model showing how the formulations drive ratings. With concepts (and package designs), the researcher systematically varies the presence/absence of elements/pictures and measures consumer reactions such as acceptance or appropriateness. The concept data generate a model showing how the elements drive reactions. Concept and product research look for relations among variables, at once to understand and also to engineer consumer‐acceptable products and messaging.     

NEXT GENERATION HEALTHY SOUP: AN EXPLORATION USING CONJOINT ANALYSIS

This paper presents results on consumer attitudes towards healthy soup, using conjoint analysis, executed on the Internet. The results show moderate interest in new ideas for the total panel, but reveal three concept-response segments. The first segment responds to nutrition and functional ingredients. The second segment responds to packaging and convenience. The third segment responds to taste and ingredients. Statistical analysis confirms the idea that they represent different 'mind-sets'. The segmentation based on psychographic variables is a useful tool to identify the features of the next generation "healthy soups" and to design custom products on the basis of consumer requirements.