Phycomyces: An Increase in Mechanical Extensibility during the Avoidance Growth Response

The sporangiophore of Phycomyces shows a transient response to a double barrier, the avoidance growth response. Tensile tests conducted on the stage IV sporangiophore demonstrate that an increase in mechanical extensibility occurs about a minute after a double barrier stimulus. This change in mechanical extensibility is similar to the one that occurs after a light stimulus. We have concluded that the avoidance stimulus occurs somewhere on the same pathway between the photoreceptor mechanism and the final growth response.     

Roles of Extensibility and Turgor in Gibberellin- and Dark-stimulated Growth

The elongation response elicited by incubating excised hypocotyl sections of lettuce (Lactuca sativa L.) in light in gibberellin (GA) can be enhanced by the addition of Cl(-), Br(-), and NO(3) (-) salts of K(+) and Na(+). Sections incubated in light in the absence of GA do not elongate in response to the addition of salts. In contrast, excised hypocotyls incubated in darkness elongate equally in both GA and water, and their elongation can also be enhanced by KCl treatment. Growth stimulation by the salts of K(+) and Na(+) occurs optimally at 10 mm and the magnitude of the response is proportional to the duration of salt treatment. Although the growth of sections incubated in light in the absence of GA is not enhanced by various salts of K(+) and Na(+), the concentration of these cations exceeds that in GA-treated sections. In dark-grown tissue, uptake of K(+) also occurs in both GA- and H(2)O-treated sections incubated in 10 mm KCl. Since increased osmotic potential resulting from cation uptake does not correlate with growth stimulation resulting from salt treatments, we conclude that increased cell turgor is not the principal driving force for growth in hypocotyl sections. Changes in the extensibility of GA-treated, light-grown tissue and dark-grown tissue incubated with and without GA correlate with the increased growth rate of these sections. Incubation of sections in KCl results only in changes in water potential of sections without having a significant effect on extensibility. When changes in water potential are accompanied by increased extensibility, however, a marked increase in growth rate is observed.     

Proteome Changes in Thai Indigenous Chicken Muscle during Growth Period

Proteomic profiling of the pectoralis muscle of Thai indigenous chickens during growth period was analyzed using two-dimensional gel electrophoresis (2-DE) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF/MS). A total of 259, 161, 120 and 107 protein spots were found to be expressed in the chicken pectoralis muscles at 0, 3, 6 and 18 weeks of age, respectively. From these expressed proteins, five distinct protein spots were significantly associated with chicken age. These protein spots were characterized and showed homology with phosphoglycerate mutase 1 (PGAM1), apolipoprotein A1 (APOA1), triosephosphate isomerase 1 (TPI1), heat shock protein 25 kDa (HSP25) and fatty acid binding protein 3 (FABP3). These five protein spots were categorized as follows: (i) the expression levels of PGAM1 and TPI1 proteins were positively correlated with chicken aging (p<0.05), (ii) the expression levels of APOA1 and FABP3 proteins were negatively correlated with chicken aging (p<0.05) and (iii) the expression levels of the HSP25 protein were up- and down-regulated during growth period. Moreover, the mRNA expression levels of the FABP3 and HSP25 genes were significantly decreased in muscle during the growth period (p<0.05), whereas no significant changes of the PGAM1, TPI1 and APOA1 gene expression from the chicken muscle was observed. The identified proteins were classified as metabolic and stress proteins. This demonstrates a difference in energy metabolism and stress proteins between age groups and shows that proteomics is a useful tool to uncover the molecular basis of physiological differences in muscle during the growth period.     

Interaction of Gibberellin A3 and Ancymidol in the Growth and Cell-Wall Extensibility of Dwarf Pea Roots

Effects of ancymidol (Anc) and gibberellin A₃ (GA₃) on rootgrowth, osmotic concentration and cell-wall extensibility ofthe root were investigated in the gibberellin-sensitive cultivarof dwarf pea, Little Marvel. Anc strongly suppressed elongationof both shoots and roots in darkness. Although the elongationof shoots of this dwarf cultivar was severely retarded in thelight, it was repressed still further by Anc. GA₃ promoted elongationof shoots both in the presence and in the absence of Anc, whereasit reversed suppression of root elongation by Anc. The concentrationof GA₃ required for the recovery of root elongation was lowerthan that required for the promotion of shoot elongation. Treatmentwith Anc led to increased thickening of roots with increasednumbers of cells per cross section and lateral expansion ofcells in the cortex. GA₃ had little effect on the osmotic concentration of cell sapobtained from root segments. Anc-treated roots did not respondto acid solutions by elongation, whereas GA₃-treated roots respondednormally to such solutions. Anc suppressed but GA₃ enhancedthe cell-wall extensibility of roots as measured in vivo andin vitro. These results indicate that a low concentration of gibberellinplays a role in normal elongation of roots by maintaining theextensibility of the cell wall in this gibberellin-sensitivedwarf pea. (Received January 17, 1994; Accepted July 15, 1994)     

Longevity Determined by Paternal Ancestors' Nutrition during Their Slow Growth Period

Social circumstances often impinge on later generations in a socio-economic manner, giving children an uneven start in life. Overfeeding and overeating might not be an exception. The pathways might be complex but one direct mechanism could be genomic imprinting and loss of imprinting. An intergenerational "feedforward" control loop has been proposed, that links grandparental nutrition with the grandchild's growth. The mechanism has been speculated to be a specific response, e.g. to their nutritional state, directly modifying the setting of the gametic imprint on one or more genes. This study raises the question: Can overnutrition during a child's slow growth period trigger such direct mechanisms and partly determine mortality? Data were collected by following-up a cohort born in 1905 in Överkalix parish, northernmost Sweden. The probands were characterised by their parents' or grandparents' access to food during their own slow growth period. Availability of food in the area was defined by referring to historical data on harvests and food prices, records of local community meetings and general historical facts. If there was a surfeit of food in the environment when the paternal grandfather was a 9–12 year old boy a shortening of the proband survival could be demonstrated. The influence of parents', maternal grandparents' and paternal grandmothers' access to food during their slow growth period was discounted in a multivariable analysis. The results are indicative of very early programming mechanisms in human adaptation to the social environment.     

Stem Diameter Growth of Scots Pine Trees after Increased Mechanical Load in the Crown during Dormancy and (or) Growth

A field experiment with a 2 x2 factorial block design (W_xS_x)was conducted in northern Sweden where the mechanical loadsin the crowns of sixteen 2.5m high Scots pine (Pinus sylvestrisL.)trees were increased during one winter (W₁, dormant period)and (or) summer (S₁, growth period). Trees treated were loadedwith five 2kg bags hung over mid-crown branches close to thestem, i.e. 10kg per tree. After treatment, all trees were leftto grow untreated for one additional year. Trees were then cutat ground level and annual ring widths for the last 5 yearswere measured on stem discs taken at 1, 5, 10, 15, 20, 30 and50% of tree height. Differences between treatments were analysedwith two-way factorial ANOVA. Accumulated treatment responsewas positive for winter loading (W₁S_x) at all levels, and statisticallysignificant at 1, 15 and 20% of tree height. Summer loading(W_xS₁) had positive effects at the lowest and middle parts ofthe stem, and negative in between. No statistically significanttwo-way interaction (W xS) was observed. Results support thehypothesis that Scots pine trees can retain information aboutmechanical forces acting on their stems during winter, and respondto this during the following growth period. The results alsosuggest that stem form of trees in boreal forests may be stronglyaffected by winter conditions. Stem form; mechanical perturbation; Scots pine; Pinus sylvestris; dendrometer; diameter; growth; dormancy; thigmomorphogenesis; wind; sway     

Light-stimulated incorporation of L-leucine into the gibberellin of Gibberella fujikuroi

Cultures of Gibberella fujikuroi grown under continuous illuminationof 1800 lux incorporated over 60% more leucine into the gibberellinsthan dark controls. In the dark at a C/N ratio of 37.6 Ca⁺⁺increased the incorporations of leucine into A₃ to essentiallythe same level as the light-stimulated incorporation. The failureof Ca⁺⁺ to increase gibberellin synthesis in the dark at a C/Nratio of 9.4 suggested that light and Ca⁺⁺ were exerting theirregulatory roles at different sites. (Received October 15, 1969; )     

Light-stimulated phosphorylation of proteins in cell-free extracts from Trichoderma viride

When illuminated by visible light, cell-free extracts from the fungus Trichoderma viride catalysed the phosphorylation of at least two proteins with molecular masses of 18 and 114 kDa which were practically absent when the phosphorylation was performed in the dark. The effect of light could be substituted by 3mM cyclic AMP, not only in the cell-free extract, but also in the separated cytosol. It is concluded that the process of photoinduced conidiation in Trichoderma involves phosphorylation of conidiation-specific proteins by (a) cyclic AMP-dependent protein kinase(s) present in the cytosol.     

Light-stimulated protein movement in rod photoreceptor cells of the rat retina

We examined the intracellular distribution of three proteins involved in the cyclic GMP cascade of visual transduction; cGMP phosphodiesterase, the alpha-subunit of G-protein and arrestin. In adult rats, light-induced changes in the amounts of G and arrestin in the photoreceptor cell outer segments were observed both by polyacrylamide gel analysis of purified ROS and by immunocytochemical localization on retinal sections. In dark conditions, G was concentrated in the outer segments of photoreceptor cells while in the light G alpha was seen in the inner segments and the outer nuclear layer. Arrestin had the opposite distribution, appearing in the inner segments and outer nuclear layer under dark conditions and in the ROS under light conditions. In contrast, PDE, the enzyme which is activated by G and inhibited by arrestin showed no light-stimulated movement. In both light- and dark-adapted retinas, PDE was localized primarily in the outer segments of the photoreceptor cells.     

Increase in cardiac contractility during puberty

Pubertal growth of heart was analyzed. Growth rates of "diastolic variables" of heart size were compared with that of 'systolic', and both with growth intensities of some body structures and functions that are related to cardiac growth. Longitudinal echocardiographic, ergometric and anthropometric measurements were performed in 84 healthy boys, aged 11.5 years at the beginning and 14.5 at the end of study. Diastolic thickness of left ventricular walls increased by a mean rate of 15% and systolic by 36% (p < 0.001). As a result, percent systolic wall thickening increased from 20% to 41% during the 3 years (p < 0.001). Other measures of cardiac contractility increased in the same manner. Increase in measures of cardiac preload and afterload corresponds to the increase in heart "diastolic" and "systolic" variables, respectively. The study gave evidences for an increase in cardiac contractility during puberty. Coexistence of two simultaneous growth models for pubertal heart: diastolic and systolic, is suggested.     

Involvement of Cell Wall-Bound Diferulic Acid in Light-Induced Decrease in Growth Rate and Cell Wall Extensibility of Oryza Coleoptiles

Irradiation of white fluorescent light (5 W m^–2) inhibitedthe growth of Oryza coleoptiles. Light irradiation increasedstress-relaxation parameters of coleoptile cell walls, minimumstressrelaxationtime and relaxation rate, and decreased cellwall extensibility (strain/load). Under light conditions, thecontents of ferulic and diferulic acids ester-linked to thehemicellulosic arabinose residue in cell walls increased andcorrelated with the modification of the cell wall mechanicalproperties. These results suggest that light irradiation enhancesthe formation of diferulic acid bridges in hemicelluloses, makingcell walls mechanically rigid and thus inhibits cell elongationin rice coleoptiles. Also, irrespective of coleoptile age orthe presence of light, the ratio of diferulic acid to ferulicacid was almost constant, suggesting that the rate limitingstep in the formation of diferulic acid bridges in Oryza cellwalls is in the step of feruloylation. (Received September 24, 1991; Accepted December 3, 1991)     

An Analysis of the Increase in Lung Cancer in Canada

Lung cancer mortality in Canada over the period 1936-1964 is reviewed and a forecast is presented of future trends in the death rates, based on cohort analyses. Since 1936 the annual increases in mortality have been greater among individuals over 65 years of age, but in this group no single five-year age-group has contributed the major part to the general increase. Cohort analyses show (a) that the rate of increase of lung cancer has been much slower in generations born after 1906, (b) that the actual death rate will rise more slowly in the future, and (c) that the death rate may become stable within 15 years.