Labeling pulse

Fig. 3. Protein synthesis in a maize primary root during ( ) one hr pulse labelling with [ HJleucine under aerobic conditions (b)-(e) pulse labelling with [ HJIeucine during the specified times under anaerobic conditions. The arrow labelled TPs indicates the position of the transition polypeptides. The unlabelled arrow indicates the position of alcohol dehydrogenase 1 (ADHl). From Sachs et al. (1980).

J. Swinnen, J. A. Van Veen, and R. Merckx, Root decay and turnover of rhizodepos-its in field-grown winter wheat and spring barley estimated by C pulse labelling. Soil Biology and Biochemistry 27 211 (1995). 

B. Jensen, Rhizodeposition by C pulse labelled spring barley grown in small field plots on sandy loam. Soil Biology ami Biochemistry 25 1553 (1993). 

Several authors have applied in situ pulse labeling of plants (grasses and crops) with C-CO2 under field conditions with the objective of quantifying the gross annual fluxes of carbon (net assimilation, shoot and root turnover, and decomposition) in production grasslands and so assess the net input of carbon (total input minus root respiration minus microbial respiration on the basis of rhizodeposition and soil organic matter) and carbon fixation in soil under ambient climatic conditions in the field. 

Recently, pulse labeling has frequently been applied to determine the fate of carbon in crops such as barley and wheat and the losses from roots and subsequent microbial transformations. In general, the results indicate that 15-25% of the net " C assimilation is transferred to the roots and that there are seasonal differences in the distribution of assimilated carbon. Meharg and Killham (25) measured the C distribution in perennial ryegrass (L perenne). At 8 days after the pulse with... 

A. A. Meharg and K. Killham, Compari.son of carbon flow from pre-labelled and pulse-labelled plants. Plant Soil 112 225 (1988). 

B. Jensen, Distribution of C in pulse-labelled spring barley effect of light intensity and length of photoperiod before labelling. Acta Agric. Scand. Sect. B Soil Plant Sci. 44 214 (1994). 

J. Swinnen. J. A. van Veen, and R. Merckx, C Pulse-labelling of field-grown... 

P. J. Gregory and B. J. Atwell, The fate of carbon in pulse-labelled crops of barley and wheat. Planl Soil /.J6 205 (1991). 

Plants grown for longer periods in solid supports such as sand or soil repre-.sent the next level of complexity and, although other techniques are available, carbon flow is most frequently estimated using C labeling experiments. In the laboratory, COt can be supplied to shoots either as a short pulse or continuously, and the carbon flow can be monitored. In the field, due to technical limitations, only COi pulse labeling procedures are possible. A final approach, termed crop studies, involves the measurement of components of crop growth from which... 

Other sand-based systems using COi pulse-chase procedures have been used to produce carbon budgets for Festuca ovina and Plantago lanceolata seedlings (30) and white lupin (Lupimis albiis) (31). Significantly, CO2 pulse labeling of proteoid roots of white lupin under phosphate-deficient conditions showed that high levels of dark fixation of COi by the roots took place and that 66% of this root-fixed carbon was exuded from the roots (31). Clearly, dark fixation of CO2 by roots and subsequent rhizodeposition is an area that deserves further study in the future. 

Pulse labeling—laboratory Anaerobiosis Perennial ryegrass (Lolium perenne) 39... 

Pulse labeling—field Growth stage or plant age Barley (Hordeum vidgare) 49... 

T. Shepherd and H. V. Davies, Carbon loss from the roots of forage rape (Brassica napus L.) seedlings following pulse-labelling with CO, Ann. Boi. 72 155 (1993). 

J. A. Palta and P. J. Gregory. Drought affects the fluxes of carbon to roots and soil in C pulse-labelled plants of wheat. Soil Biol. Biochem. 29 1395 (1997). 

In favorable systems, the coherent movement of neuro-filaments and microtubule proteins provides strong evidence for the structural hypothesis. Striking evidence was provided by pulse-labeling experiments in which NF proteins moved over periods of weeks as a bell-shaped wave with little or no trailing of NF protein. Similarly, coordinated transport of tubulin and MAPs makes sense only if MTs are being moved, since MAPs do not interact with unpolymerized tubulin [31]. 

Using BrdU pulse labelling was evident that at equivalent Gfio, compounds produced a delay in the S phase followed by an accumulation in G2/M, as is expected for mechanism of action of topi inhibitor. Antiproliferative activities was also found after shorter treatments as previously reported, when the duration of drug treatment was limited to 1 hour (Figure 6), at doses from 30 to 300 nM. 

BrdU Pulse Labeling and Chase of for Separating Cell Cycle Phases and Their Fates... 

Pulse labelling and chase of cells with BrdU for the final 15 minutes of duration of 1-h drug treatment (Figure 6) enabled the distinction of those cells that were synthesizing DNA (S-Phase) during treatment from those that were not (Gi and G2/M) following of their behaviours during the release up to 72 hours and their capabilities to move inside cell cycle. 

Figure 8. Cell cycle profiles of BrdU negative cells in pulse and chase experiment gated based on BrdU/DNA content dot plot. Cells in the S phase were labelled with BrdU and left in a drug-free medium. Data analysis of BrdU negative cells normalized by cell counting of pulse-labelling experiment was displayed and grey and white area indicated treated or untreated groups by different time point.

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