Effect of temperature and preconditioning on photoperiodic response of pharbitis nil.
Temperature and preconditioning effect on photoperiodic response of Pharbitis nil, strain Violet short-day plant
BIOLOGICAL RHYTHM↗
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The control of apical dominance: localization of the growth region of the Pharbitis nil shoot
The growing region of the upright Pharbitis nil shoot extends over a distance 13 cm basipetal to the shoot apex. When the shoot is inverted, ethylene production in this region is greatly enhanced whereas stem elongation is significantly inhibited. This growth region is ethylene-sensitive and the restriction of its growth by shoot inversion-induced ethylene may mediate the release of apical dominance.
NASA Discipline Plant Biology↗
Shoot inversion inhibition of stem elongation in Pharbitis nil: a possible role for ethylene-induced glycoprotein and lignin
Inversion of the upper shoot of Pharbitis nil results in the inhibition of elongation in the inverted stem. The objective of the present study was to determine how shoot inversion-induced gravity stress inhibited elongation and to elucidate the possible role of ethylene-induced glycoprotein and lignin in this process. Determinations of hydroxyproline, peroxidase, phenylalanine ammonia-lyase (PAL), phenol, and lignin content/activity were carried out by appropriate spectrophotometric methods. It was found that inversion and Ethrel treatments of upright shoots caused significant increases in hydroxyproline content, peroxidase, and PAL activity in 12 hours and in phenol and lignin contents in 24 hours. All of these increases except for that of cytoplasmic peroxidase activity were partially reversed by AgNO3, the ethylene action inhibitor. It is concluded that possible cross-linking associated with the accumulation of the ethylene-induced hydroxyproline-rich glycoprotein and lignin may be responsible for the later stages of cessation of elongation in the inverted Pharbitis shoot.
NASA Program Space Biology↗
Shoot inversion-induced ethylene in Pharbitis nil induces the release of apical dominance by restricting shoot elongation
Shoot inversion induces outgrowth of the highest lateral bud (HLB) adjacent to the bend in the stem in Pharbitis nil. In order to determine whether or not ethylene produced by shoot inversion plays a direct role in promoting or inhibiting bud outgrowth, comparisons were made of endogenous levels of ethylene in the HLB and HLB node of plants with and without inverted shoots. That no changes were found suggests that the control of apical dominance does not involve the direction action of ethylene. This conclusion is further supported by evidence that the direct application of ethylene inhibitors or ethrel to inactive or induced lateral buds has no significant effect on bud outgrowth. The hypothesis that ethylene evolved during shoot inversion indirectly promotes the outgrowth of the highest lateral bud (HLB) in restricting terminal bud (TB) growth is found to be supported by the following observations: (1) the restriction of TB growth appears to occur before the beginning of HLB outgrowth; (2) the treatment of the inverted portion of the shoot with AgNO3, an inhibitor of ethylene action, dramatically eliminates both the restriction of TB growth and the promotion of HLB outgrowth which usually accompany shoot inversion; and (3) the treatment of the upper shoot of an upright plant with ethrel mimics shoot inversion by retarding upper shoot growth and inducing outgrowth of the lateral bud basipetal to the treated region.
NASA Discipline Plant Biology↗
Kinetics of shoot inversion-induced ethylene production in Pharbitis nil
Shoot inversion promotes a significant increase in ethylene production in the inverted part of the Pharbitis nil main shoot. The latent period for shoot inversion-induced ethylene production is ca. 2.75 h. Our results indicate that the shoot-inversion ethylene response is not persistent and can be terminated and rapidly reinitiated by appropriate alteration of the orientation of the main shoot regardless of prolonged previous exposures of the shoot to various orientations. The time course of the production of ACC (1-aminocyclopropane-1-carboxylic acid), the immediate precursor of ethylene, follows a pattern similar to that of ethylene during the various alterations of shoot orientation. Excised stem segments and intact stems are capable of induction, inhibition, and reinduction of ethylene evolution. Ethylene production reported here for shoot inversion does not result from segmenting (wounding) of the tissue.
NASA Discipline Number 40-10↗
Gibberellin-enhanced elongation of inverted Pharbitis nil shoot prevents the release of apical dominance
Ethylene evolution resulting from the gravity stress of shoot inversion appears to induce the release of apical dominance in Pharbitis nil (L.) by inhibiting elongation of the inverted shoot. It has been previously demonstrated that this shoot inversion release of apical dominance can be prevented by promoting elongation in the inverted shoot via interference with ethylene synthesis or action. In the present study it was shown that apical dominance release can also be prevented by promoting elongation of the inverted shoot via treatment with gibberellic acid (GA3). A synergistic effect was observed when AgNO3, the ethylene action inhibitor, was applied with GA3. Both GA3 and AgNO3 increased ethylene production in the inverted shoot. These results are consistent with the view that it is ethylene-induced inhibition of elongation and not any direct effect of ethylene per se which is responsible for the outgrowth of the highest lateral bud.
NASA Discipline Number 40-10↗
Effects of shoot inversion on stem structure in Pharbitis nil
The effects of shoot inversion on stem structure over 72 hr were investigated in Pharbitis nil by analyzing cell number, cell length, and the cross sectional areas of cells, tissues, and regions. An increase in stem diameter can be attributed to an increase in both cell number and cross sectional area of pith (primarily) and vascular tissue (secondarily). Qualitative observations of cell wall thickness in the light microscope did not reveal any significant effects of shoot inversion on this parameter. The inhibition of shoot elongation was accompanied by a significant decrease in cell length in the pith. The results are generally consistent with an ethylene effect on cell dimensions, especially in the pith.
Non-NASA Center↗
Timing of growth inhibition following shoot inversion in Pharbitis nil
Shoot inversion in Pharbitis nil results in the enhancement of ethylene production and in the inhibition of elongation in the growth zone of the inverted shoot. The initial increase in ethylene production previously was detected within 2 to 2.75 hours after inversion. In the present study, the initial inhibition of shoot elongation was detected within 1.5 to 4 hours with a weighted mean of 2.4 hours. Ethylene treatment of upright shoots inhibited elongation in 1.5 hours. A cause and effect relationship between shoot inversion-enhanced ethylene production and inhibition of elongation cannot be excluded.
Non-NASA Center↗
Mechanical perturbation-induced ethylene releases apical dominance in Pharbitis nil by restricting shoot growth
Mechanical perturbation (MP, rubbing) or internodes of Pharbitis nil shoots initiates release of lateral buds (LB) from apical dominance within 48 h. Evidence is presented which suggests that MP promotion of LB outgrowth is mediated by ethylene-induced restriction of main shoot growth. Ethylene production in the internodes is stimulated by MP within 2 h. Effects of MP are mimicked by treatments with 1-aminocyclopropane-1-carboxylic acid (ACC) and are negated by the inhibitors of ethylene production or action, aminoethoxy vinylglycine (AVG) and AgNO3. The fact that effects of MP, ACC, and ethylene inhibitors are observed to occur on main shoot growth at least 24 h before they are observed to occur on LB growth suggests a possible cause and effect relationship. MP also causes an increase in internode diameter. MP stimulation of ethylene production appears to be mediated by ACC synthase. The results of this study and our previous studies suggest that apical dominance may be released by any mechanism which induces ethylene restriction of main shoot growth.
Amino Acids, Cyclic↗
Welding of nickel-base superalloys having a nil-ductility range
An article made of a nickel-base superalloy having a nil-ductility range from the solidus temperature of the alloy to about 600.degree. F. below the solidus temperature is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, adjusting the temperature of the article to a welding temperature of from about 1800.degree. F. to about 2100.degree. F., welding a preselected area in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected area so as to locally melt the alloy in the preselected area, providing a filler metal having the same composition as the nickel-based superalloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.
Smashey, Russell W.↗
An Indirect Role for Ethylene in Shoot-inversion Release of Apical Dominance in Pharbitis Nil
Evidence is presented which indicated that ethylene does not play a direct role in promoting or inhibiting bud outgrowth as a gravity response. It is concluded that the treatment of inactive or induced lateral buds with ethylene inhibitors or ethrel has no significant effect on bud outgrowth and that no changes occur in ethylene emanation in the Highest Lateral Bud (HLB) or HLB node following shoot inversion. Possible mechanisms by which ethylene released by shoot inversion may indirectly promote outgrowth of the HLB is presented.
Cline, M. G.↗
Efferent projections of the ectostriatum in the pigeon (Columba livia)
The ectostriatum is a major visual component of the avian telencephalon. The core region of the ectostriatum (Ec) receives visual input from the optic tectum through thalamic nuclei. In the present study, the efferent projections of the ectostriatum were investigated by using the anterograde tracers Phaseolus vulgaris leucoagglutinin and biotinylated dextran amine. Projection patterns resulting from these tracers were confirmed by the retrograde tracer cholera toxin subunit B. When anterograde tracers were injected in Ec, primary projections were seen traveling dorsolaterally to the belt region of the ectostriatum (Ep) and the neostriatal area immediately surrounding Ep (Ep2). Neurons in Ep sent projections primarily to the overlying Ep2. The efferents of Ep2 traveled dorsolaterally to terminate in three telencephalic regions, from anterior to posterior: (1) neostriatum frontale, pars lateralis (NFL), (2) area temporo-parieto-occipitalis (TPO), and (3) neostriatum intermedium, pars lateralis (NIL). A part of the archistriatum intermedium and the lateral part of the neostriatum caudale also received somewhat minor projections. In addition, some neurons in Ec were also the source of direct, but minor, projections to the NFL, TPO, NIL, and archistriatum intermedium. The topographical relationship among the primary (Ec), secondary (Ep and Ep2), and tertiary (NFL, TPO, NIL) areas indicate that the neural populations for visual processing are organized along the rostral-caudal axis. Thus, the anterior Ec sent efferents to the anterior Ep, which in turn sent projections to anterior Ep2. Neurons in the anterior Ep2 sent projections to NFL and the anterior TPO. Similarly, the intermediate and posterior Ec sent projections to corresponding parts of Ep, whose efferents projected to intermediate and posterior Ep2, respectively. The intermediate Ep2 gave rise to major projections to TPO, whereas posterior Ep2 neurons sent efferents primarily to NIL. The organization of this neural circuit is compared with those of other sensory circuits in the avian telencephalon, as well as the laminar arrangement of the mammalian isocortex.
Non-NASA Center↗
First Detections of the [NII] 122 Micrometer Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe
We report the first detections of the [NIl] 122 {\mu} m line from a high redshift galaxy. The line was strongly (> 6{\sigma}) detected from SMMJ02399-0136, and HI413+ 117 (the Cloverleaf QSO) using the Redshift(z) and Early Universe Spectrometer (ZEUS) on the CSO. The lines from both sources are quite bright with line-to-FIR continuum luminosity ratios that are approx.7.0x10(exp -4) (Cloverleaf) and 2.1x10(exp -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line-to-continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8 to 17% of the molecular gas mass. The [OIII]/[NII] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an AGN. Using our previous detection of the [01II] 88 {\mu}m line, the [OIII]/ [NIl] line ratio for SMMJ02399-0136 indicates the dominant source of the line emission is either stellar HII regions ionized by 09.5 stars, or the NLR of the AGN with ionization parameter 10g(U) = -3.3 to -4.0. A composite system, where 30 to 50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82like starbursts accounting for all of the FIR emission and 43% of the [NIl] line. The remainder may come from the NLR. This work demonstrates the utility of the [NIl] and [OIII] lines in constraining properties of the ionized medium.
Ferkinhoff, Carl↗
The role of gravity in apical dominance: effects of clinostating on shoot inversion-induced ethylene production, shoot elongation and lateral bud growth
Shoot inversion-induced release of apical dominance in Pharbitis nil is inhibited by rotating the plant at 0.42 revolutions per minute in a vertical plane perpendicular to the axis of rotation of a horizontal clinostat. Clinostating prevented lateral bud outgrowth, apparently by negating the restriction of the shoot elongation via reduction of ethylene production in the inverted shoot. Radial stem expansion was also decreased. Data from experiments with intact tissue and isolated segments indicated that shoot-inversion stimulates ethylene production by increasing the activity of 1-aminocyclopropane-1-carboxylic acid synthase. The results support the hypothesis that shoot inversion-induced release of apical dominance in Pharbitis nil is due to gravity stress and is mediated by ethylene-induced retardation of the elongation of the inverted shoot.
NASA Discipline Plant Biology↗
A prototype high power portable lamp
Portable lighting system serves the combined work and photographic needs of manned spacecraft efforts. This system enables the lamps to be momentarily brightened while the camera shutter is opened. The brightness is adequate for black and white or color photography and yet the increased heat load is nil.
Sammis, J. C.↗
Correlation of irradiation data using activation fluences and irradiation temperature.
Nil-ductility transition temperature data for A302-B ferritic steel were analyzed by using multiple regression. Four independent variables were used - i.e., specimen temperature during irradiation, and time-integrated specific activations (activation fluences) of fast-, intermediate-, and thermal-neutron detectors. The results of these analyses were predictive equations having the increase in transition temperature as the dependent variable. For a reference point, a similar analysis was also performed using the flux integral above 1 MeV and the irradiation temperature as independent variables. Also, the effect of excluding irradiation temperature from these analyses was studied. The results of the analyses showed that excellent correlation was achieved by using activation fluences and irradiation temperature as the independent variables. Irradiation temperature was found to account for from 29 to 46% of the data variability depending on the model used.
Lynch, J. H.↗
Correlation of irradiation data using activation fluences and irradiation temperature.
A new method of correlating radiation damage data is tested using actual measured data taken from the open literature. This method, the activation fluence method, was found to be as accurate as other contemporary models with which it was compared. The new method also has several advantages over the other methods. The method employs a new entity, the activation fluence (time-integrated specific activation rate), as the independent variables in a regression model. Temperature at which the irradiation takes place is also a variable. Although the method was tested for a specific type of damage (change in nil-ductility transition temperature for A302-B steel) it has no inherent restrictions and is limited only by the imagination of the user.
Lynch, J. H.↗
Irradiation effects on 17-7 PH stainless steel, A-201 carbon steel, and titanium-6-percent-aluminum-4-percent-vanadium alloy
Irradiation effects on three materials from the NASA Plum Brook Reactor Surveillance Program were determined. An increase of 105 K in the nil-ductility temperature for A-201 steel was observed at a fluence of approximately 3.1 x 10 to the 18th power neutrons/sq cm (neutron energy E sub n greater than 1.0 MeV). Only minor changes in the mechanical properties of 17-7 PH stainless steel were observed up to a fluence of 2 x 10 to the 21st power neutrons/sq cm (E sub n greater than 1.0 MeV). The titanium-6-percent-aluminum-4-percent-vanadium alloy maintained its notch toughness up to a fluence of 1 x 10 to the 21st power neutrons/sq cm (E sub n greater than 1.0 MeV).
Hasse, R. A.↗