A system for convenient combustion preparation of tritiated biological samples for scintillation analysis

Peterson, John I.; Wagner, Frank R.; Siegel, Sidney; Nixon, Wilbert E.

doi:10.1016/0003-2697(69)90257-7

Cited by 79 publications

(10 citation statements)

References 19 publications

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“…In the experiments on the uptake of ABA by lettuce seed, external liquid was removed by washing with water and the washed seed dried overnight at 120°C. The seeds were then subject to total combustion in an Oxymat sample oxidizer (Peterson 1969, Peterson et al 1969). The residue from the extracted seeds was also analysed by total combustion to determine the nonextractable radioactivity when ABA metabolism was examined.…”

Section: Methodsmentioning

confidence: 99%

Abscisic Acid and the Germination of Thermodormant Lettuce Fruits (Lactuca sativa cv. Grand Rapids). The Fate of Isotopically Labelled Abscisic Acid

Robertson¹,

Berrie²

1977

Physiologia Plantarum

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ABA inhibits the germination of Grand Rapids lettuce seeds at a temperature at which photoblastism is not observed. This ABA inhibition can be overcome by GA, or cytokinin, or red light acting alone or in concert. At high levels of ABA the ameliorative effects of GA, cytokinin or red light are not manifest and it is suggested that lettuce seeds' response to a given level of ABA is temperature dependent, and any interaction which may be observed between ABA and other regulators, or red light, likewise is temperature dependent. Seeds only actively metabolize ABA after germination is complete though ABA does influence the germination process proper. Some radioactivity, originally applied as 14C ABA, cannot be extracted from 14C ABA treated seeds by methanol, and this “fixed” ABA can constitute more than 50% of the activity taken up by the seeds. High levels of “fixed” ABA are found in seeds which do not germinate. As well as this “fixed” ABA two labelled metabolites arise in seeds treated with 14C ABA. The levels of these rise in seed extracts as the level of extractable ABA decreases. Whilst ABA can affect germination our results do not allow us to assign a specific regulatory role to ABA in seed germination.

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Section: Methodsmentioning

confidence: 99%

Abscisic Acid and the Germination of Thermodormant Lettuce Fruits (Lactuca sativa cv. Grand Rapids). The Fate of Isotopically Labelled Abscisic Acid

Robertson¹,

Berrie²

1977

Physiologia Plantarum

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“…Thus, Hill (1972), andPeveling andHill (1974) have suggested that in P. polydactyla the alga releases a glucan which is subsequently hydrolysed extracellularly by the mycobiont to glucose. This glucose is finally taken up by the fungus and converted to mannitol.…”

Section: Discussionmentioning

confidence: 99%

Physiological‐environmental Interactions in Lichens

Macfarlane

Kershaw

1982

New Phytologist

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SUMMARYThe potential control by temperature and moisture of the movement of glucose from the phycobiont in Collema furfuraceum, Peltigera polydactyla and Peltigera rtifescens is examined. The ratio of labelled mannitol to labelled glucose after exposure to "CO.^ is used as a measure ofthe amount of glucose transported and converted to mannitol in the lichen thallus over a range of experimental temperatures and levels of thallus hydration. The results show that temperature has little effect on the proportion of the total lahel appearing in mannitol except at 5 °C. This is interpreted as a minimum temperature requirement for the conversion of glucose to mannitol within the mycobiont. The effect of thallus hydration, however, shows that in Peltigera polydactyla the major movement of fixed carbon from the phycobiont to the fungal partner occurs at, or close to, full thallus saturation. Below 300 "o thallus moisture by weight the amount of label appearing in mannitol declines sharply. Conversely, in Collema furfuraeeum and Peltigera rufescens, transport of glucose continues at a constant rate down to very low levels of thallus hydration.These results are discussed in relation to our previous findings using Peltigera praetextata, and in relation to the balance of total photosynthate between the lichen symbionts during a drying cycle. It is evident that the rate of transport of glucose is closely controlled by the level of thallus hydration which in turn correlates with the xeric or mesic preference of each species. Alternate -wetting and drying cycles effectively ensure that each biont obtains an adequate supply of the fixed carbon resources, thus maintaining the integrity of the lichen.

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“…To determine the cellular content of radiolabeled compounds triplicate cell samples were blotted dry, weighed, and transferred to polycarbonate capsules. The samples were dried at room temperature overnight and combusted in a Peterson machine (Oxymat, Intertechnique, Plaisir, France) (Peterson et al, 1969). Tritiated and 14C-labeled isotopes were captured as 3H,0 and 14C02, respectively.…”

Section: Measurements Of Uptake and Content Of Radioactive Compoundsmentioning

confidence: 99%

Temperature-Sensitive Plant Cells with Shunted Indole-3-Acetic Acid Conjugation

Oetiker

Aeschbacher

1997

Plant Physiology

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~ ~Cells of henbane (Hyoscyamus muticus L.) grow indefinitely i n culture without exogenous auxin. Cells of its temperature-sensitive variant XIlB2 grow like the wild type at 26OC but die rapidly at 33°C unless auxin is added to the medium. Despite this temperaturesensitive auxin auxotrophy, XllB2 produces wild-type amounts of indole-3-acetic acid (IAA). IAA i s the predominant auxin and is important for plant growth and development. Since the IAA production of the variant is functional, we investigated whether the synthesis or degradation of IAA metabolites, possibly active auxins themselves, is altered. The IAA metabolites were IAA-aspartate (IAAsp) and IAA-glucose. The wild type converted IAA mainly to IAAsp, whereas the variant produced mainly IAA-glucose. Exogenous auxin corrected the shunted IAA metaholism of the variant.The half-life of labeled IAAsp i n the variant was reduced 21-fold, hut in the presence of exogenous auxin it was not different from the wild type. The temperature sensitivity of XllB2 was also corrected by supplying IAAsp. Pulse-chase experiments revealed that henhane rapidly metabolizes IAAsp to compounds not identical to IAA. The data show that the variant XIlB2 is a useful tool to study the function of IAA conjugates to challenge the popular hypothesis that IAA conjugates are merely slow-release storage forms of IAA.

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A system for convenient combustion preparation of tritiated biological samples for scintillation analysis

Cited by 79 publications

References 19 publications

Abscisic Acid and the Germination of Thermodormant Lettuce Fruits (Lactuca sativa cv. Grand Rapids). The Fate of Isotopically Labelled Abscisic Acid

Abscisic Acid and the Germination of Thermodormant Lettuce Fruits (Lactuca sativa cv. Grand Rapids). The Fate of Isotopically Labelled Abscisic Acid

Physiological‐environmental Interactions in Lichens

Temperature-Sensitive Plant Cells with Shunted Indole-3-Acetic Acid Conjugation

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