Excised leaves

Plant. In corn seedlings and excised leaves of corn, sorghum, sugarcane, and barley, propachlor was metabolized to at least three water-soluble products. Two of these metabolites were identified... 

The third metabolic pathway discovered for degradation of triazine herbicides in plants was first reported by Shimabukuro et al. (1970) and involved conjugation of atrazine with glutathione in corn nutrient uptake, excised leaves, and leaf disc experiments. This new degradation mechanism was postulated to be the primary factor in the... 

The primary inhibitory effect of cadmium on photosynthesis of excised leaves was proposed to be metal-induced stomatal closure (Bazzaz et al., 1974 Lamoreaux and Chaney, 1978). In epidermal peels floating on a metal-containing solution, stomatal closure was reported (Bazzaz et al., 1974). Inhibition of transpiration by several metals, especially by cadmium, is well documented (Poschenrieder et al., 1989), but is not necessarily at the stomatal level. Metal-induced stomatal closure can indirectly be responsible for a decrease of photosynthetic C02 fixation indeed. However, several enzymes of the Calvin cycle are directly affected by metals. 

Citrus sp. (excised leaves disks) Altemaria citri Infectivity phytotoxin host range33... 

Triticum aestivum (wheat, excised leaves) Pucdnia recondita Infectivity (visual)28... 

Insulin is synthesized as proinsulin. After synthesis and folding, a section of the molecule (the C peptide) is excised, leaving the A and B peptides connected via disulfide bridges. Thus, native insulin, lacking the C peptide, lacks some of the information necessary to direct the folding process. 

Solutions (250 ppm) of Triton X-100, a commercial ethoxylated nonionic surfactant, were administered to excised barley leaves. Partial inhibition of photosynthetic oxygen evolution occurred In tissue segments taken from the leaves after 5 h of exposure, but there was a partial recovery of activity by the excised leaves during the next 18 h. In contrast, treatments with 2 ppm atra-zine caused nearly complete and irreversible inhibition ( ). 

Surfactant concentrations within the excised leaves ranged from 4-80 ppm (fresh weight basis). 

Metabolite Profiles. Preliminary trials with tOPh 6EO yielded surfactant metabolism rates similar to those for barley in excised leaves of a variety of monocot species (9.) although there were qualitative and quantitative differences in the metabolites found. Under equivalent conditions, however, metabolism of the parent surfactant was slower in excised rice leaves. Table II compares the metabolic fate of C-WPh 6E0 in excised leaves of barley and two rice cultivars. Recoveries of were high with barley tissues and only limited quantities occurred as methanol-insoluble metabolites or as volatiles. The recoveries from rice were lower and up to 20 was present as methanol-insoluble residues (combusted to C02). Exhaustive methanol extraction decreased the amount of insoluble to about 155t (9). 

Perez-Lorens, J. L., and NieU, F. X. (1995). Short-term phosphate uptake kinetics in Zostera noltii Homem A comparison between excised leaves and sediment-rooted plants. Hydrobiologia 297, 17-27. 

Unfike the benign adenoma patient, patients with adrenal carcinoma have an unpredictable and unfavorable outcome with surgical resection. Often the complete tumor cannot be excised, leaving the patients with some degree of symptomatology and extra-adrenal involvement. Irradiation can be used if metastases are discovered. In the patient with adrenal carcinoma who is not a surgical candidate, the focus of treatment is on palliative pharmacologic intervention (e.g., mitotane). 

Herbert and Kirby found that [2- C]mevalonate fed through the cut stem of excised leaves of D. datum was not significantly incorporated into delpheline. 

Fig. 4.3 An essential part of the gene (white box) is flanked by short, directed loxP sequences (triangles) which are inserted in intronic or non-coding regions in order not to disturb normal expression of the gene. The Cre recombinase will bind to the loxP sites, the Cre enzymes will interact forming a DNA loop, and the DNA in between the loxP sites will be excised leaving a single loxP site behind. Expression of Cre, therefore, determines in which cells the deletion occurs.

Viart, P. and M. Bensoussan Automatic determination of alkaloids in cigarette smoke condensate Ann. Dir. Emdes Equipement, SEITA 9(Sect. 1) (1971) 123-134. Vickery, H.B. and 1. Zelitch The metabolism of the organic acids of tobacco leaves. XVll. Effect of culture of excised leaves in solutions of potassium pyruvate J. Biol. Chem. 235 (1960) 1871-1875. 

Indications that the mitochondria regulate nitrate reduction in a direct manner are obtained from the observations that oxygen inhibits nitrite accumulation (Ferrari and Varner, 1970 Radin, 1973) and that uncouplers of the electron transport system permit nitrite accumulation under aerobic conditions (Ferrari and Varner, 1970). Canvin and Atkins (1974) and Atkins and Canvin (1975) reported that excised leaves under a dark aerobic gaseous environment do not assimilate into amino acids and that vac-... 

Because rotenone does not block mitochondrial ATP site II (site of entry of cytoplasmic NADH) these data infer that the nitrite rather than nitrate reduction is affected. Nitrite accumulated in excised leaves (gaseous milieu) under nitrogen is rapidly lost upon transfer to air (Jones and Sheard, 1978). When only the base of excised leaves are placed in a small amount of water or water containing DNF or FCCP (carbonyl-chlorideptri-fluoromethoxyphenylhydrazone) nitrite accumulation is unaffected by the treatments, under anaerobic conditions. Upon transfer to air, leaves treated with DNP or FCCP show relatively small amounts of loss of nitrite in comparison with controls (Hageman et al., 1980b). 

Mevinolin was hydrolyzed according to [13] to give the K-salt, and fed via the petioles to excised leaves prior to stress. The concentrations were estimated on the basis of amount taken up and water content of leaves. 

Growth is a most complicated phenomenon. Much work has been done to determine a primary effect of kinetin. In these investigations some ideas of Chibnall played a role. This author assumed already in 1939 that a hormone arising from the roots stimulates protein synthesis. Later on he showed that excised leaves yellowed more slowly when they were rooted. The important role of rooting the leaves for continued protein synthesis. 

In summary, purines, kinetin and its artificial analogues, benzimidazole, indoleacetic acid, triiodobenzoic acid, 2,4-dichlorophenoxyacetic acid and a hypothetical root substance show ceitain common effects. However, they do not manifest themselves in all the investigated materials in the same way, possibly because some are quickly decomposed or translocated. One of the most general effects is the retardation of yellowing of excised leaves or leaf parts. For some of these substances, especially kinetin, other effects have been observed, but it is not known whether they are characteristic for the other substances. Among these effects are active transport, accumulation... 

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