ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Partitioning of respiratory electrons in the dark in leaves of transgenic tobacco with modified levels of alternative oxidase (2005)

Guy, Robert D. ; Vanlerberghe, Greg C.

Oxford, UK; Malden, USA : Munksgaard International Publishers

Physiologia plantarum 125 (2005), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: This study examined tobacco (Nicotiana tabacum cv. Petit Havana SR1) leaf respiration in the dark, utilizing both wild-type plants and transgenic plants with increased or decreased levels of alternative oxidase (AOX) protein. AOX represents a non-energy-conserving branch in mitochondrial electron transport. Inhibitor studies showed that the maximum possible flux of electrons to AOX (AOX capacity) correlated with the level of AOX protein present in the different plant lines. A comparison of the plants using online 18O isotope discrimination was done to determine whether AOX protein level would impact the actual steady-state partitioning of electrons to AOX (AOX engagement). Under a range of pretreatment and measurement conditions, there was little if any effect of AOX protein level on the degree of engagement. This suggests that the metabolic conditions inherent to a particular growth condition and/or the biochemical regulatory properties of AOX itself are the critical factors that control partitioning. Interestingly, we found that measurement temperature and water status are parameters that may have some influence over AOX engagement.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.2005.00557.x

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2

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A comparative kinetic analysis of nitrate and ammonium influx in two early-successional tree species of temperate and boreal forest ecosystems (2000)

Min, Xiangjia ; Siddiqi, M. Yaeesh ; Guy, Robert D. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Plant, cell & environment 23 (2000), S. 0

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ISSN: 1365-3040

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Root NO3− and NH4+ influx systems of two early-successional species of temperate (trembling aspen: Populus tremuloides Michx.) and boreal (lodgepole pine: Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forest ecosystems were characterized. NO3− and NH4+ influxes were biphasic, consisting of saturable high-affinity (HATS) and constitutive non-saturable low-affinity transport systems (LATS) that were evident at low and relatively high N concentrations, respectively. NO3− influx via HATS was inducible (IHATS); nitrate pre-treatment resulted in 8–10-fold increases in the Vmax for influx in both species. By contrast, HATS for NH4+ were entirely constitutive. In both species, Vmax values for NH4+ influx were higher than those for NO3− uptake; the differences were larger in pine (6-fold) than aspen (1·8-fold). In aspen, the Km for NH4+ influx by HATS was approximately 3-fold higher than for IHATS NO3− influx, while in pine the Km for IHATS NO3− influx was approximately 3-fold higher than for NH4+ influx. The aspen IHATS for NO3− influx appeared to be more efficient than that of pine (Vmax values for aspen being approximately 10-fold higher and Km values being approximately 13-fold lower than for pine). By contrast, only small differences in values for the NH4+ HATS were evident between the two species. The kinetic parameters observed here probably result from adaptations to the N availabilities in their respective natural habitats; these may contribute to the distribution and niche separation of these species.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00546.x

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3

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Cytochrome and alternative pathway respiration in white spruce (Picea glauca) roots. Effects of growth and measurement temperature (1991)

Weger, Harold G. ; Guy, Robert D.

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 83 (1991), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Interactions between growth temperature and measurement temperature were examined for their effects on white spruce [Picea glauca (Moench) Voss] root respiration. Total dark respiration rates increased with measurement temperature and were unaffected by growth temperature. Partitioning of respiratory electron flow between the cytochrome and alternative pathways was also unaffected by growth temperature. The proportion of respiration mediated by the alternative pathway was constant at measurement temperatures between 4°C and 18°C, but was increased at higher temperatures. Changes in alternative pathway activity were paralleled by changes in capacity, and the alternative pathway was almost fully engaged at all temperatures. Roots grown at low temperature displayed higher carbohydrate levels than roots grown at higher temperatures, but respiration rate was unaffected. Spruce root respiration did not appear to acclimate to growth temperature, and the alternative pathway was not preferentially engaged at low temperature.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02486.x

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4

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Glycinebetaine content of halophytes: Improved analysis by liquid chromatography and interpretations of results (1984)

Guy, Robert D. ; Warne, Patricia G. ; Reid, David M.

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 61 (1984), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The glycinebetaine content of plants can be determined by simple isocratic high performance liquid chromatography. The method is applicable to extracts from a wide range of species and, in most cases, is suitably rapid and specific to be preferable to other methods of analysis. The chromatographic system employed permits accurate and sensitive ultraviolet detection, free of most interferences. Because the principle plant carbohydrates elute well before glycine betaine, preparative ion exchange procedures can be simplified. Twenty-seven species, mostly inland halophytes, were screened by these methods and 13 were found to be glycinebetaine accumulators. On a dry weight basis, the glycinebetaine content of Salicornia europaea L. actually declined with exposure to progressively higher levels of NaCl. When expressed as a proportion of plant organic matter, however, patterns were more typical (up to 7.7% at higher salt concentrations).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1984.tb05896.x

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5

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Shifts in carbon isotope ratios of two C3 halophytes under natural and artificial conditions (1980)

Guy, Robert D. ; Reid, David M. ; Krouse, H. Roy

Springer

Oecologia 44 (1980), S. 241-247

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ISSN: 1432-1939

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The total carbon δ13C values of two C3 halophytes,Salicornia europaea L. ssp.rubra (Nels.) Breitung andPuccinellia muttalliana (Schultes) Hitch., native to inland saline areas of Alberta, Canada, were determined for plants grown under controlled conditions of supplied NaCl in the nutrient solution, and for plants found growing in the field. Field specimens were collected along line transects which ran from areas of high salinity to areas of low salinity across the pattern of species zonation. The δ13C value of the two species seemed to reflect the water potential of the soil (ψ w soil ) as measured arbitrarily at a depth of 10 cm, becoming less negative as the ψ w soil decreased. Over a linear distance of 5.55 m,S. europaea spp.rubra showed a shift of +5.3‰ as the ψ w soil went from-25x102 kPa to a minimum of-73x102 kPa. ForP. nuttalliana, the δ13C values differed by 3.4‰ over a distance of 7.45 m where the maximum difference in ψ w soil was 12.7x102 kPa. However, δ13C values ofP. nuttalliana only roughly reflected the spatial trends in ψ w soil at the time of collection. In the growth chamber, the δ13C value ofS. europaea ssp.rubra changed by a maximum of +8.0‰ when the solute potential of the nutrient solution (ψ w soil ) was dropped from-0.25x102 kPa to-64.25x102 kPa; while the δ13C value ofP. nuttalliana changed by a maximum of +10.8‰ when the ψ w soil was dropped from-0.25x102 kPa to-40.25x102 kPa. Linear regression analyses indicated that the δ13C values of both species were strongly correlated (P〈0.2%) with ψ w soil . The observed shifts in δ12C may represent changes in the mode of photosynthetic CO2 fixation. However, a number of other explanations, some of which are discussed in the text, are also possible. A proper ecophysiological interpretation of such shifts in δ13C values of C3 plants awaits a better understanding of the isotope fractionation mechanisms involved.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00572686

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6

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Differential fractionation of oxygen isotopes by cyanide-resistant and cyanide-sensitive respiration in plants (1989)

Guy, Robert D. ; Berry, Joseph A. ; Fogel, Marilyn L. ; [et al.]

Springer

Planta 177 (1989), S. 483-491

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ISSN: 1432-2048

Keywords: Alternative respiration ; Cytochrome oxidase ; Isotopes, stable ; Mitochondrion ; Oxidase, alternative ; Oxygen ; Respiration

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Stable-isotope discrimination factors (D) for the uptake of oxygen during respiration by a variety of plant materials were determined by measuring 18O enrichment in a closed system. Baker's yeast (Saccharomyces cerevisiae Meyer) and mitochondrial preparations from baker's yeast and from castor bean (Ricinus communis L.) endosperm, all of which are fully sensitive to cyanide, discriminated againt 18O by about 16–18‰. Whole Medicago sativa L. seedlings, isolated intact Asparagus sprengeri Regel mesophyll cells, and spadix mitochondria of Eastern skunk cabbage (Symplocarpus foetidus L.) had higher Ds of about 20–22‰. These materials all had some capacity for the cyanide-resistant alternative respiration pathway and in the presence of cyanide discriminated by about 24–26‰. When treated with salicylhydroxamic acid or tetraethylthiuram disulfide, which inhibit the alternative pathway, discrimination was about 17–19‰. Where respiration was limited by oxygen diffusion (slices of thermogenic tissues from S. foetidus and Sauromatum gutfatum Schott), fractionation was much reduced and the difference between the two respiratory pathways was masked. Isotope discrimination by soybean lipoxygenase (EC 1.13.11.12) supplied with linoleic acid was much lower than by respiration. Where diffusion is not a problem, the D value obtained in the absence of inhibitor can be used to estimate the partitioning of electron transport between the two pathways at steady-state by linear interpolation between the Ds characteristic of cyanide-resistant and cyanide-sensitive respiration.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00392616

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7

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Physiological recovery of freezer-stored white and Engelmann spruce seedlings planted following different thawing regimes (1995)

Camm, Edith L. ; Guy, Robert D. ; Kubien, David S. ; [et al.]

Springer

New forests 10 (1995), S. 55-77

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ISSN: 1573-5095

Keywords: Key words ; Water relations ; photosynthesis ; chlorophyll a fluorescence ; artificial forest regeneration ; cold storage ; frost hardiness

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Logistic problems of large-scale reforestation necessitate freezer-storage of conifer seedlings. Frozen stock is typically thawed slowly at low temperatures for up to several weeks before shipping to the plantation site, but the necessity of this practice is questionable. Experiments were conducted to study effects of different thawing regimes on photosynthetic recovery, frost hardiness, water relations and growth initiation in “interior spruce” (white spruce (Picea glauca (Moench) Voss) and Engelmann spruce (Picea engelmannii Parry) hybrid complex). One year-old container-grown seedlings were planted after 9 days post-storage thawing at 5–15 °C or still frozen, directly from the freezer. During a 29 day observation period after planting, both groups showed changes in xylem water potential (Ψw), carbon fixation (A), stomatal conductance (g s ), chlorophyll a fluorescence and xanthophyll cycle pigments. Treatment differences in fluorescence and pigments peaked within one hour after planting. All differences in Ψw, A, g s , ratio of internal to external CO2 concentration (Ci/Ca), fluorescence, pigments and root number disappeared after 5 to 8 days. Terminal bud burst occurred 2.6 days earlier in the pre-thawed seedlings. When seedlings were rapidly thawed in the dark at 21 °C they achieved maximum Ψw (−0.2 MPa) in 3–4 hour. When evaluated 45 min after planting, A, g s , Ci/Ca and fluorescence values of rapidly thawed seedlings were intermediate between those for seedlings planted frozen or after 9 days slow thawing, showing that the recovery process was well underway a few hours after removal from the freezer. These results suggested that a suitable on-site operational protocol for rapid thawing might be to lay frozen bundles on the ground at ambient temperature overnight. In field trials of this method, rapidly thawed seedlings broke bud 3.3 days later than slowly thawed stock and also had greater frost hardiness at time of planting. Height, shoot and root mass did not differ after 3 months growth.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00034176

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