Green Discs Research Articles

Emergent Untrained Combined Functions in Equivalence Classes

Abstract Three experiments examined whether each of the functions controlled by different stimuli in an equivalence class would become integrated in a test for transfer of function. In Experiment 1, a paper-and-pencil protocol was used to establish two 3-member equivalence classes (A1, B1, C1 & A2, B2, C2). Nonsense syllables were used for all stimuli except for B1 and C1 which were pictures of blue and green discs, respectively. Participants then were presented with five boxes containing discs of five different colors, including blue and green. Participants were instructed to respond as they felt appropriate. Across all participants varying numbers of blue and green discs were placed on B1 and C1, respectively. Responding at A1 included combinations of blue and green discs by seven out of eight participants. These results were replicated after the classes were extended to include D and E stimuli. In Experiment 2, the overall procedure was repeated, however, there was a pretraining condition in which participants were instructed to select and place discs of their choosing on each of B1 and C1. In general, responding within both classes was consistent with results in Experiment 1. Two participants placed similar combinations of colored discs at A1, D1, and E1 but retained the single colors at B1 and C1. Experiment 3 changed the B1 and C1 stimuli to nonsense syllables and trained the function to placing colored discs at B1 and C1. It was found that results were similar to those found in both Experiments 1 and 2. Results are discussed in the context of procedures used to investigate the emergence of novel behavior.

Different spectral sensitivities of ON- and OFF-motion pathways enhance the detection of approaching color objects in Drosophila

Color and motion are used by many species to identify salient objects. They are processed largely independently, but color contributes to motion processing in humans, for example, enabling moving colored objects to be detected when their luminance matches the background. Here, we demonstrate an unexpected, additional contribution of color to motion vision in Drosophila. We show that behavioral ON-motion responses are more sensitive to UV than for OFF-motion, and we identify cellular pathways connecting UV-sensitive R7 photoreceptors to ON and OFF-motion-sensitive T4 and T5 cells, using neurogenetics and calcium imaging. Remarkably, this contribution of color circuitry to motion vision enhances the detection of approaching UV discs, but not green discs with the same chromatic contrast, and we show how this could generalize for systems with ON- and OFF-motion pathways. Our results provide a computational and circuit basis for how color enhances motion vision to favor the detection of saliently colored objects.

New Lichen Species and Records from the Chapada dos Guimarães, Mato Grosso, Brazil

Three species of lichens are described as new from the Chapada dos Guimarães in Mato Grosso (Brazil): Astrothelium muriconicum Aptroot & M.F.Souza, sp. nov. which is the first species in the core group of the genus, the A. conicum-group, with muriform ascospores; Gassicurtia lopesiana M.F.Souza & Aptroot, sp. nov. which is characterized by red apothecium margins and lichexanthone in the thallus; and G. pruinosa M.F.Souza & Aptroot, sp. nov. which has brown pruinose, UV+ green discs and less red pigmantation. A further 191 species are reported new to the state Mato Grosso, 14 of which are first reports from Brazil.

Broadened temperature range of high-performance in 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 ceramics prepared by pre-sintering (Ba0.7Ca0.3)TiO3 gel method

High-performance temperature range of the morphotropic phase boundary in the 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 series of ceramics is broadened by sintering the green ceramic discs formed from the mixture of pre-sintering (Ba0.7Ca0.3)TiO3 gel and Ba(Zr0.2Ti0.8)O3 gel. The morphotropic phase boundary occurring at room temperature with x = 0.5 is found out in the series of the (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 ceramics sintered at 1250Co by measuring ferroelectric properties and crystal structure. The optimum performance of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 is obtained by pre-sintering (Ba0.7Ca0.3)TiO3 gel at 300Co, and its high-performance temperature range from −77 to 40Co is about 1.7 times broader than that of the 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramic sintered directly at 1250Co. It is found that the contents of phase composition in the optimum sample are 63% for morphotropic phase boundary with x = 0.5, 18% for Rhombohedral phase, and 19% for Tetragonal phase. The pre-sintering approach not only maintains the excellent ferroelectric properties induced by the morphotropic phase boundary, but also broadens the applicable high-performance temperature range of the samples.

Morphotypes of the common beadlet anemone Actinia equina (L.) are genetically distinct

Anemones of the genus Actinia are ecologically important and familiar organisms on many rocky shores. However, this genus is taxonomically problematical and prior evidence suggests that the North Atlantic beadlet anemone, Actinia equina, may actually consist of a number of cryptic species. Previous genetic work has been largely limited to allozyme electrophoresis and there remains a dearth of genetic resources with which to study this genus. Mitochondrial DNA sequencing may help to clarify the taxonomy of Actinia. Here, the complete mitochondrial genome of the beadlet anemone Actinia equina (Cnidaria: Anthozoa: Actinaria: Actiniidae) is shown to be 20,690 bp in length and to contain the standard complement of Cnidarian features including 13 protein coding genes, two rRNA genes, two tRNAs and two Group I introns, one with an in-frame truncated homing endonuclease gene open reading frame. However, amplification and sequencing of the standard mtDNA barcoding region of the cytochrome oxidase I gene revealed only two haplotypes, differing by a single base pair, in widely geographically separated A. equina and its congener A. prasina. COI barcoding shows that whilst A. equina and A. prasina share the common mtDNA haplotype, haplotype frequency differed significantly between A. equina with red/orange pedal discs and those with green pedal discs, consistent with the hypothesis that these morphotypes represent incipient species.

Influence of steam condensation on vitamin C retention in green turnip undergoing low pressure superheated steam drying

AbstractIn this article, green turnip discs were dried in low pressure superheated steam for high vitamin C retention. Drying kinetics and vitamin C variation in green turnip was studied at 95 mbar in superheated steam from 75 to 90 °C, considering the influence of steam condensation on the retention of vitamin C. It was found that an amount of vitamin C was transferred in the condensate water during drying process, especially in the constant evaporation period. Due to steam condensation and assistant electrical heating, the material surface temperature was higher than the water boiling point temperature at corresponding environment pressure when superheated steam stopped condensing. The condensate occurred in material surface could enhance the loss of vitamin C in green turnip. Vacuum preheating could reduce the amount of steam condensation and material temperature rise, and hence the vitamin C retention in green turnip was higher than that in continuous superheated steam drying.Practical applicationsGreen turnip is a nutritional, economical and healthy plant, which contains various nutrients such as carotene, ascorbic acid, protein, etc. Dried green turnip has been used as a resource of food seasoning and pickled foods. Fresh green turnip having relatively high moisture contents is very sensitive to microbial spoilage. Drying is one of the most common methods used for green turnip preservation. LPSSD is an innovative technology and which has been applied for dehydration of biological materials due to high nutrients retention, better product appearance, and energy efficiency. Low pressure superheated steam drying process has an initial steam condensation period, transferring an amount of latent heat to the material. It has been demonstrated that steam condensation on sample surface have some influence on material quality. Understanding the effect of condensation on vitamin C retention in green turnip is helpful for improving the quality of dried green turnip slices.

Effect of powder metallurgy synthesis parameters for pure aluminium on resultant mechanical properties

In this work, pure aluminium powders of different average particle size were compacted, sintered into discs and tested for mechanical strength at different strain rates. The effects of average particle size (15, 19, and 35 μm), sintering rate (5 and 20 °C/min) and sample indentation test speed (0.5, 0.7, and 1.0 mm/min) were examined. A compaction pressure of 332 MPa with a holding time of six minutes was used to produce the green compacted discs. The consolidated green specimens were sintered with a holding time of 4 h, a temperature of 600 °C in an argon atmosphere. The resulting sintered samples contained higher than 85% density. The mechanical properties and microstructure were characterized using indentation strength measurement tests and SEM analysis respectively. After sintering, the aluminium grain structure was observed to be of uniform size within the fractured samples. The indentation test measurements showed that for the same sintering rate, the 35 μm powder particle size provided the highest radial and tangential strength while the 15 μm powder provided the lowest strengths. Another important finding from this work was the increase in sintered sample strength which was achieved using the lower sinter heating rate, 5 °C/min. This resulted in a tangential stress value of 365 MPa which was significantly higher than achieved, 244 MPa, using the faster sintering heating rate, 20 °C/min.

Morphology of Co-Cr-Mo dental alloy surfaces polished by three different mechanical procedures

The present study aims at characterizing the three-dimensional (3-D) morphology of a Co-Cr-Mo dental alloy surface as a result of three different procedures used for polishing it. The sample surface morphology of the sampled surface was examined employing atomic force microscopy (AFM), statistical surface roughness parameters, and fractal analysis. An extra-hard dental alloy of cobalt-chromium-molybdenum (Co-Cr-Mo) (Wironit(®) , from BEGO, Bremen, Germany) was prepared and moulded. Different polishing treatments were carried out on three groups of six samples each--a total of 18 samples. The first group contained six electropolished (EP) samples. The second group containing six samples went through a mechanical polishing process employing green rubber discs and a high shine polishing paste applied by a rotating black brush (BB). The third group comprising six samples as well went through a mechanical polishing process by means of green rubber discs, high shine polishing paste, and a rotating deer leather brush (DL). Fractal analysis on the basis of a computational algorithm applied to the AFM data was employed for the 3-D quantitative characterization of the morphology of the sampled surfaces. The fractal dimension D (average ± standard deviation) of 3-D surfaces for BB samples (2.19 ± 0.07) is lower than that of the DL samples (2.24 ± 0.08), which is still lower than that of the EP samples (2.27 ± 0.09). The results indicated the BB samples as presenting the lowest values of statistical surface roughness parameters, thus the best surface finish, while the EP samples yielded the highest values.

Advance information modulates the global effect even without instruction on where to look

When observers are asked to make an eye movement to a visual target in the presence of a near distractor, their eyes tend to land on a position in between the target and the distractor, an effect known as the global effect. While it was initially believed that the global effect is a mandatory eye movement strategy, recent studies have shown that explicit instructions to make an eye movement to a certain part of the scene can overrule the effect. We here investigate whether such top-down influences are also found when people are not actively involved in an explicit eye movement task, but instead, make eye movements in the service of another task. Participants were presented with arrays of yellow and green discs, each containing a letter, and were asked to identify a target letter. Because the discs were presented away from fixation, participants made an eye movement to the array of discs on most of the trials. An analysis of the landing sites of these eye movements revealed that, even without an explicit instruction, observers take the advance information about the colour of the disc containing the target into account before moving their eyes. Moreover, when asking participants to maintain fixation for intervals of different durations, it was found that the implicit top-down influences operated on a very similar time-scale as previously observed for explicit eye movement instructions.

Impact of lower- vs. upper-hemifield presentation on automatic colour-deviance detection: A visual mismatch negativity study

The automatic processing of deviances from the temporal context of the visual environment has become an important topic in visual cognitive sciences, which is often investigated using the visual mismatch negativity (vMMN). This event-related potential (ERP) component is elicited by an irregular stimulus (e.g., a red disc) presented in a series of stimuli (e.g., green discs) comprising a temporal regularity (e.g., colour repetition). We determined the influence of lower- vs. upper-hemifield presentation of the irregular stimulus on the vMMN while using whole-field stimulus displays controlling for sustained shifts in spatial attention. Deviances presented in the lower hemifield elicited a larger vMMN than the ones presented in the upper hemifield at a latency of 200–280ms. However, this asymmetry was preceded by deviance-related hemifield effects already emerging at an earlier latency (110–150ms), where upper-hemifield deviances elicited a positive potential but lower-hemifield deviances did not. With variable resolution electromagnetic tomography (VARETA) early deviance-related activity was localised to retinotopically organised regions of the visual cortex (BA 17/18) and vMMN-sources were localised to the middle/superior occipital gyrus, to higher areas along the temporal visual stream, but also to BA 17/18. We argue that the upper/lower-hemifield vMMN asymmetry relies at least partially on the hemifield-dependent differential sensitivity of early deviance-related activity generated in retinotopically organised regions of the visual cortex. However, a superior automatic processing of deviances presented in the lower visual hemifield may also contribute to the effect.

Pyridine 2,4-Dicarboxylate Downregulates Ethylene Production in Response to Mechanical Wounding in Excised Mature Green Tomato Pericarp Discs

Pyridine 2,4-dicarboxylate (PDCA) is a structural analog of 2-oxoglutarate and a potent inhibitor of 2-oxoacid-dependent dioxygenases (2-ODDs), such as prolyl 4-hydroxylases (P4Hs). It has been reported that PDCA inhibited the in vitro activity of P4Hs in cut carnation flowers and delayed petal senescence due to suppression of climacteric ethylene production. In this study, the effect of PDCA on ethylene evolution in response to mechanical wounding due to excision of mature green tomato pericarp discs was investigated. Ethylene evolution was induced within 1 h of mechanical wounding in control discs and gradually increased throughout 24 h, whereas it was partially suppressed in PDCA-treated discs during the first 12 h of a 24-h experimental period. This transient, partial suppression of ethylene production can be attributed to the lack of induction and the downregulation of ethylene biosynthetic genes within 1 h and after 12 h of wounding, respectively. However, it cannot be attributed to the suppression of ACC oxidase, a well-known 2-ODD, because no significant change in enzymatic activity was observed in PDCA-treated discs. In addition, the transcript abundance of wound-induced and ethylene-regulated PIN1, PIN2, and E4 genes was also partially suppressed in PDCA-treated discs. PDCA was also shown to be involved in ethylene evolution and color development of mature green and turning fruit discs. Overall, these results indicate that PDCA downregulates ethylene production in response to mechanical wounding and during ripening of preclimacteric and climacteric tomato fruit discs.

Assessing Spiral Grain Angle by Light Transmission: – Proof of Concept –

Spiral grain measurements are subject to a high degree of variation and interpretation, depending on the assessment method used. A new measurement approach was tested whereby light was directed through disc samples on a flatbed scanner and the deviation along the grain assessed by means of a template to allow the mapping of grain angle variation radially and tangentially within discs. Initial results showed that the approach was valid for green discs up to 35 mm thick and small enough to fit on an A4 scanner. Comparisons with traditional scribing and cleaving methods were favourable, indicating that the light transmission approach could allow much faster and more accurate data acquisition. The possibility of using larger discs would enhance the ability to assess spatial variation in grain angle and minimise the effects of sample reference geometry with respect to the tree axis (disc tilt and parallax). Further work may also be required to ensure that reliable spiral grain values are obtained from both sapwood and heartwood. The ultimate goal is to develop an automated system for reconstructing stem characteristics from measurements on large fresh green discs to enable the 3-dimensional mapping of individual stem variations in key wood properties and modelling the impacts of silviculture and genetics on wood products.

Fabrication of Sr- and Co-doped lanthanum chromite interconnectors for SOFC

Many studies have been performed dealing with the processing conditions of electrodes and electrolytes in solid oxide fuel cells (SOFCs). However, the processing of the interconnector material has received less attention. Lanthanum chromite (LaCrO 3) is probably the most studied material as SOFCs interconnector. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La 0.80Sr 0.20Cr 0.92Co 0.08O 3 was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA) as dispersant and tetramethylammonium hydroxide (TMAH) to assure a basic pH and providing stabilization. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.% of PAA and TMAH, respectively, yielded the best conditions for successful slip casting. Sintering of the green discs was performed in air at 1600 °C for 4 h leading to relatively dense materials.

Layer‐by‐Layer Films of Graphene and Ionic Liquids for Highly Selective Gas Sensing

The best of both worlds: Graphene/ionic liquid (G–IL) layered films were obtained by direct reduction of graphene oxide in the presence of ionic liquids, followed by reassembly through electrostatic layer-by-layer (LbL) adsorption (see picture). The layer spacing of the graphene sheets is regularly expanded upon insertion of ionic liquid molecules (green discs). Selective sensing of aromatic compounds (red spheres) by using the G–IL LbL films was also achieved. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Effect of Different Finishing and Polishing Agents on the Surface Roughness of Cast Pure Titanium

The aim of this study was to evaluate the effect of finishing and polishing agents on surface roughness of cast commercially pure titanium using scanning electron microscope (SEM) analysis. A standardized square steel die measuring 10 x 10 mm with a thickness of 2 mm was machine cut. An impression of this die was used to create wax patterns for casting. Sixty specimens were cast in commercially pure titanium. These were divided into three groups (A, B, and C) of 20 specimens each. Group A specimens were polished with black, brown, and green rubber discs followed by green polishing compound with buff. Group B specimens were polished with black, brown, and green rubber cones, buffed with yellow polishing cake designed for gold alloy. Group C specimens were polished with silicium carbide cones and buffed with orange polishing cake. Surface roughness of the test specimens was measured in microns with a perthometer. Data were analyzed with ANOVA and Tukey's honest significant difference (HSD) multiple comparison tests among the different groups. Qualitative analysis was done by SEM photomicrographs. Surface roughness values R(a) for Groups A, B, and C were 0.68 microm, 0.78 microm, and 0.27 microm, respectively. SEM photomicrographs and the statistical analysis revealed that the finishing and polishing were better with Group C test specimens with lower surface roughness values compared with groups A and B. Tests showed that Group C was statistically smoother (p< or = 0.01). Within the limitations of this study, surface roughness was less on cast CpTi specimens that were finished and polished from the cutters designed specifically for titanium.

A note on social dominance and learning ability in the domestic chicken ( Gallus gallus)

Relatively little is known about the relationship between social behavior and specific cognitive abilities of the chicken. It is uncertain whether dominant birds have a cognitive advantage over subordinate birds that might facilitate their superior position in the social hierarchy. Likewise, it is unknown whether subordinate birds compete successfully with higher ranking birds because their cognitive capacities compensate for physical deficits. In this study, the relationship between the chicken's position in the dominance hierarchy and its performance on a cognitive task was explored. Ten pairs of New Hampshire domestic roosters ( Gallus gallus) were observed to determine dominance or subordinance within dyads. All birds were then trained and tested on a visual discrimination learning task. Discriminative stimuli were orange and green plastic discs. Correct stimuli (orange or green) were randomly assigned to birds. Placement of the discs (left or right of center) was also randomly assigned and counterbalanced to avoid a side bias. Birds were rewarded with food for pecking at the correct disc. Criterion for task completion was 80% correct responses on three consecutive test sessions or 86% correct on two consecutive sessions. All subjects met the test criterion. The number of trials to criterion was compared between dominant and subordinate birds using a paired t-test. No difference was found in performance between dominant and subordinate birds ( p > 0.05) suggesting that in chickens, ability to learn a novel visual discrimination task is not well correlated with rank. Additional studies, particularly using different learning paradigms, are needed to confirm these results.

Induction and Control of Chromoplast-specific Carotenoid Genes by Oxidative Stress

The differentiation of chloroplasts into chromoplasts involves a series of biochemical changes that culminate with the intense accumulation of long chain chromophore carotenoids such as lycopene, rhodoxanthin, astaxanthin, anhydroeschsoltzxanthin, capsanthin, and capsorubin. The signal pathways mediating these transformations are unknown. Chromoplast carotenoids are known to accumulate in green tissues experiencing stress conditions, and studies indicate that they provide efficient protection against oxidative stress. We tested the role of reactive oxygen species (ROS) as regulators of chromoplast carotenoid biosynthesis in vivo. The addition of ROS progenitors, such as menadione, tert-butylhydroperoxide, or paraquat and prooxidants such as diamide or buthionine sulfoximine to green pericarp discs of pepper fruits rapidly and dramatically induce the simultaneous expression of multiple carotenogenic gene mRNAS that give rise to capsanthin. Similarly, down-regulation of catalase by amitrole induces expression of carotenogenic gene mRNAs leading to the synthesis of capsanthin in excised green pericarp discs. ROS signals from plastids and mitochondria also contribute significantly to this process. Analysis of the capsanthin-capsorubin synthase promoter in combination with a beta-glucuronidase reporter gene reveals strong activation in transformed pepper protoplasts challenged with the above ROS. Collectively these data demonstrate that ROS act as a novel class of second messengers that mediate intense carotenoid synthesis during chromoplast differentiation.

Decarboxylative metabolism of [1′-14C]indole-3-acetic acid by tomato pericarp discs during ripening

The rate of decarboxylation of [1′-14C]indole-3-acetic acid (IAA) infiltrated into tomato (Lycopersicon esculentum Mill.) pericarp discs was much more rapid in green than in breaker and pink tissues. Studies were carried out in order to determine whether the decarboxylative catabolism occurring in the green pericarp discs was associated with ripening or was a consequence of wound-induced peroxidase activity and/or ethylene production. After a 2-h lag, the decarboxylative capacity of the green pericarp discs increased exponentially during a 24-h incubation period. This increase was accompanied by increases in IAA-oxidase activity in cell-free preparations from the intercellular space and cut surface of the discs. Although higher IAA-oxidase activity was detected in extracts from the tissue residue, which comprises mainly intracellular peroxidases, this activity did not increase during the 24-h incubation period. Analysis of the cell-free preparations by isoelectric focusing revealed the major component in all samples was a highly anionic peroxidase (pI=3.5) the levels of which did not increase during incubation. However, the intercellular and cut-surface preparations contained additional anionic and cationic peroxidases which increased in parallel with the increases in both the IAA-oxidase activity of the preparations and the decarboxylative capacity of the green pericarp discs from which they were derived. Treatment of green discs with the ethylene-biosynthesis inhibitors aminooxyacetic acid and CoCl2, inhibited the development of an enhanced capacity to decarboxylate [1′-14C]IAA but the inhibition was not counteracted by exogenous ethylene. Another ethylene-biosynthesis inhibitor, aminoethoxyvinyl glycine, also reduced ethylene levels but did not affect IAA decarboxylation, indicating that the decarboxylation was not a consequence of wound-induced ethylene production. The data obtained thus demonstrate that the enhanced capacity to decarboxylate [1′-14C]IAA that develops in green tomato pericarp discs following excision is not associated with ripening but instead is attributable to a wound-induced increase in anionic and cationic peroxidase activity in the intercellular fluid and at the cut surface of the excised tissues.

Comparison of Ripening Processes in Intact Tomato Fruit and Excised Pericarp Discs

Physiological processes characteristic of ripening in tissues of intact tomato fruit (Lycopersicon esculentum Mill.) were examined in excised pericarp discs. Pericarp discs were prepared from mature-green tomato fruit and stored in 24-well culture plates, in which individual discs could be monitored for color change, ethylene biosynthesis, and respiration, and selected for cell wall analysis. Within the context of these preparation and handling procedures, most whole fruit ripening processes were maintained in pericarp discs. Pericarp discs and matched intact fruit passed through the same skin color stages at similar rates, as expressed in the L(*)a(*)b(*) color space, changing from green (a(*) < -5) to red (a(*) > 15) in about 6 days. Individual tissues of the pericarp discs changed color in the same sequence seen in intact fruit (exocarp, endocarp, then vascular parenchyma). Discs from different areas changed in the same spatial sequence seen in intact fruit (bottom, middle, top). Pericarp discs exhibited climacteric increases in ethylene biosynthesis and CO(2) production comparable with those seen in intact fruit, but these were more tightly linked to rate of color change, reaching a peak around a(*) = 5. Tomato pericarp discs decreased in firmness as color changed. Cell wall carbohydrate composition changed with color as in intact fruit: the quantity of water-soluble pectin eluted from the starch-free alcohol insoluble substances steadily increased and more tightly bound, water-insoluble, pectin decreased in inverse relationship. The cell wall content of the neutral sugars arabinose, rhamnose, and galactose steadily decreased as color changed. The extractable activity of specific cell wall hydrolases changed as in intact fruit: polygalacturonase activity, not detectable in green discs (a(*) = -5), appeared as discs turned yellow-red (a(*) = 5), and increased another eight-fold as discs became full red (a(*) value +20). Carboxymethyl-cellulase activity, low in extracts from green discs, increased about six-fold as discs changed from yellow (a(*) = 0) to red.

Carbohydrate Metabolism in Photosynthetic and Nonphotosynthetic Tissues of Variegated Leaves of Coleus blumei Benth.

Mature, variegated leaves of Coleus blumei Benth. contained stachyose and other raffinose series sugars in both green, photosynthetic and white, nonphotosynthetic tissues. However, unlike the green tissues, white tissues had no detectable level of galactinol synthase activity and a low level of sucrose phosphate synthase indicating that stachyose and possibly sucrose present in white tissues may have originated in green tissues. Uptake of exogenously supplied [(14)C]stachyose or [(14)C]sucrose into either tissue type showed conventional kinetic profiles indicating combined operation of linear first-order and saturable systems. Autoradiographs of white discs showed no detectable minor vein labelling with [(14)C]stachyose, but some degree of vein labeling with [(14)C]sucrose. Autoradiographs of green discs showed substantial vein loading with either sugar. In both tissues, p-chloromercuribenzenesulfonic acid had no effect on the linear component of sucrose or stachyose uptake but inhibited the saturable component. Both tissues contained high levels of invertase, sucrose synthase and alpha-galactosidase and extensively metabolized exogenously supplied (14)C-sugars. In green tissues, label from exogenous sugars was recovered as raffinose-series sugars. In white tissues, exogenous sugars were hydrolysed and converted to amino acids and organic acids. The results indicate that variegated Coleus leaves may be useful for studies on both phloem loading and phloem unloading processes in stachyose-transporting species.