scholarly journals NUCLEOSIDE DIPHOSPHATASE IN THE ONION ROOT TIP I. EFFECTS OF FIXATION AND LEAD ON ENZYME ACTIVITY

1974 ◽  
Vol 22 (10) ◽  
pp. 945-951 ◽  
Author(s):  
C. W. GOFF ◽  
W. D. KLOHS
Keyword(s):  
Enzyme Activity ◽  
Root Tip ◽  
Fixation Time ◽  
Onion Root ◽  
Nucleoside Diphosphatase

The terminal 0.2—0.5 mm of 3-day onion roots grown from bulbs were excised and fixed for 1½ hr in various concentrations of cacodylate-buffered glutaraldehyde, formaldehyde or combinations of these. Alternatively, the fixative concentration was held constant while fixation time was varied. Control roots were run in buffer lacking fixative. The roots were then homogenized and in most cases aliquots of the entire homogenate were used to assay for total nucleoside diphosphatase (NDPase). Parallel assays were usually run after treating the homogenate with deoxycholate. Both glutaraldehyde and formaldehyde inhibited NDPase activity, the extent of this inhibition depending upon fixation time, fixative concentration and the particular aldehyde used, although with both fixatives inhibition did not increase beyond a certain level even with further increase in fixation time or fixative concentration. With glutaraldehyde and glutaraldehyde-containing fixatives, this level was normally about 74% inhibition while with formaldehyde it was about the level of non-activated NDPase activity and inhibition could be detected only after deoxycholate treatment. Lead did not appear to inhibit the "fixed" NDPase.

A CHARACTERIZATION OF NUCLEOSIDE DIPHOSPHATASE IN THE ONION ROOT TIP

1973 ◽  
Vol 21 (5) ◽  
pp. 417-425 ◽  
Author(s):  
W. D. KLOHS ◽  
C. W. GOFF
Keyword(s):  
Enzyme Activity ◽  
Lead Nitrate ◽  
Maximal Activity ◽  
Root Tip ◽  
Uridine Diphosphate ◽  
Onion Root ◽  
Guanosine Diphosphate ◽  
Inosine Diphosphatase ◽  
Triton X ◽  
Nucleoside Diphosphatase

Inosine diphosphatase of a Golgi-enriched fraction of the onion root tip was characterized. Peak enzyme activity occurred at pH 4.8 and 7.0, although considerable activity was present between the peaks. The activity at neutral pH approximately doubled during a 4-day cold storage; no such increase of the pH 4.8 activity occurred under similar conditions. Treatment with deoxycholate or Triton X-l00 also activated the pH 7.0 enzyme. Although magnesium, manganese and calcium all supported inosine diphosphatase activity, 2 mM manganese supported maximal activity. Uridine diphosphate, guanosine diphosphate and inosine diphosphate were hydrolyzed much more rapidly than the other substrates tested. Sodium fluoride, uranyl nitrate, potassium chloride and heat all partially inhibited the enzyme. Glutaraldehyde and lead nitrate, two reagents to which nucleoside diphosphatase is exposed when studied cytochemically, greatly reduced enzyme activity.

Glycosyltransferases in plant and animal tissues effects of fixation and lead on enzyme activity.

1978 ◽  
Vol 26 (10) ◽  
pp. 772-781 ◽  
Author(s):  
W D Klohs ◽  
C W Goff ◽  
R J Bernacki
Keyword(s):  
Enzyme Activity ◽  
Lead Nitrate ◽  
Initial Step ◽  
Lead Ions ◽  
Fixation Time ◽  
Animal Tissues ◽  
Root Tips ◽  
Cytochemical Localization ◽  
Onion Root ◽  
L1210 Cells

As the initial step toward the cytochemical localization of glycosyl-transferases in situ, biochemical determinations of these enzyme activities from onion root tips and L1210 cells were performed before and after fixation as well as in the presence of lead ions. Glycosyltransferase activity from roots fixed in buffered formaldehyde or glutaraldehyde before homogenization decreased as the concentration of the fixative or fixation time was increased. Formaldehyde fixation was less inhibitory than glutaraldehyde; 35% of the glycosyltransferase activity was retained after 30 min fixation in 2% formaldehyde while 25% of the enzyme activity remained after a similar fixation in glutaraldehyde. Substantially higher levels of L1210 cell glycosyltransferase activity were retained after a 30 min 2% formaldehyde fixation (60% sialyltransferase; 82% galactosyltransferase), but inhibition by glutaraldehyde was similar to that observed for onion root galactosyltransferase. Glycosyltransferase from formaldehyde-fixed roots was inhbited 35% by lead nitrate, but sialytransferase from formaldehyde-fixed L1210 cells was unaffected by lead ions. These findings are encouraging for further studies aimed at the development of cytochemical technique to localize glycosyltransferase in plant and animal tissues.

Localization of nucleoside diphosphatase in the onion root tip

PROTOPLASMA ◽  
1973 ◽  
Vol 78 (4) ◽  
pp. 397-416 ◽  
Author(s):  
Charles W. Goff
Keyword(s):  
Root Tip ◽  
Onion Root ◽  
Nucleoside Diphosphatase

scholarly journals Nucleoside diphosphatase in the onion root tip. II. The effect of inhibitors on isoenzymes.

1977 ◽  
Vol 25 (11) ◽  
pp. 1247-1253 ◽  
Author(s):  
G D Troyer ◽  
C W Goff ◽  
W D Klohs
Keyword(s):  
Adenosine Diphosphate ◽  
Guanosine Monophosphate ◽  
Thiamine Pyrophosphate ◽  
Root Tip ◽  
Root Extract ◽  
Uridine Diphosphate ◽  
Electrophoretic Study ◽  
Onion Root ◽  
Cytidine Diphosphate ◽  
Nucleoside Diphosphatase

An electrophoretic study was performed to determine the number of isoenzymes of nucleoside diphosphatase in onion root extract. Five bands exhibiting nucleoside diphosphatase activity were detected when gels were incubated with inosine diphosphate, uridine diphosphate, guanosine diphosphate or cytidine diphosphate as substrates. These consisted of a single fast migrating band (band one), a group of three intermediate migrating bands (bands two, three and four) and a single slow migrating band (band five). Gels incubated with adenosine diphosphate, thiamine pyrophosphate, inosine monophosphate, guanosine monophosphate and cytidine monophosphate showed only two bands (bands one and five). Inhibitor studies showed that sodium fluoride inhibited bands one and five but not bands two, three and four. Conversely, 1% (v/v) glutaraldehyde inhibited bands two, three and four but did not inhibit bands one and five. These results suggest that two separate groups of onion nucleoside diphosphatase isoenzymes occur which have different substrate specificities and are selected against by certain inhibitors.

scholarly journals Effects of Maytenus ilicifolia Mart. and Bauhinia candicans Benth infusions on onion root-tip and rat bone-marrow cells

2002 ◽  
Vol 25 (1) ◽  
pp. 85-89 ◽  
Author(s):  
Marjori Leiva Camparoto ◽  
Rosangela de Oliveira Teixeira ◽  
Mário Sérgio Mantovani ◽  
Veronica Elisa Pimenta Vicentini
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Root Tip ◽  
Onion Root ◽  
Maytenus Ilicifolia ◽  
Rat Bone ◽  
Marrow Cells

An experimental system for studying interrelationships between the embryo and megagametophyte of Pinus strobus during seed germination

1987 ◽  
Vol 65 (6) ◽  
pp. 1212-1217 ◽  
Author(s):  
Christopher A. Tabor ◽  
Neal M. Barnett
Keyword(s):  
Enzyme Activity ◽  
Nitrate Reductase ◽  
Reductase Activity ◽  
Morphological Characteristics ◽  
Pinus Strobus ◽  
Seedling Development ◽  
Direct Access ◽  
Root Tip ◽  
Early Seedling ◽  
Early Seedling Development

An experimental culture system was devised that provided a reliable means for conducting quantitative studies on interrelationships between embryos and megagametophytes of Pinus strobus L. during germination and early seedling development. By controlling imbibition rates, it was possible to synchronize germination of intact megagametophytes and obtain cultures with uniform morphological characteristics for use in biochemical studies. Early seedling development was affected by time of removal of the megamametophytes from the embryos; organs were larger if magagametophytes were left intact for longer periods of time. By using a nitrate reductase semimicro assay, enzyme activity was detected in embryos and shoots of intact megagametophytes, but activity declined as the seedlings aged. Activity within roots increased as seedlings matured and may be localized in the root tip. Nitrate was produced within the megagametophyte; however enzyme activity was dependent upon sustained, direct access to the inducing substrate, nitrate, in the culture medium. When megagametophytes remained intact for the initial 8 days of germination, seedlings developed epicotyls, and nitrate reductase activity within the roots was significantly greater than in 6-day cultures; in essence, by 8 days these seedlings appeared to have passed a threshold and were autotrophic.

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