scholarly journals Inflorescence Initiation In Lolium Temulentum l. VIII. Histochemical Changes At the Shoot Apex During Induction

1966 ◽  
Vol 19 (2) ◽  
pp. 233 ◽  
Author(s):  
RB Knox ◽  
IT Evans
Keyword(s):  
Silver Nitrate ◽  
Shoot Apex ◽  
Nuclear Proteins ◽  
Bromophenol Blue ◽  
Fast Green ◽  
Dna And Rna ◽  
Long Day ◽  
Orange Fluorescence ◽  
Histochemical Changes ◽  
Ammoniacal Silver

Shoot apices of Lotium temulentum plants exposed to 1 long day were harvested at the beginning of the long day, and on each of the five following days. Longitudinal sections were stained for DNA (Feulgen), DNA and RNA (methyl greenpyronin or acridine orange fluorescence), or basic nuclear proteins (ammoniacal silver nitrate, fast green, or bromophenol blue, with or without acetylation or deamination).

HISTOCHEMICAL CHANGES IN THE SHOOT TIP OF CAULIFLOWER DURING FLORAL INDUCTION

1967 ◽  
Vol 45 (7) ◽  
pp. 955-959 ◽  
Author(s):  
Sidki Sadik ◽  
J. L. Ozbun
Keyword(s):  
Shoot Apex ◽  
Dna Content ◽  
Deoxyribonucleic Acid ◽  
Floral Induction ◽  
Fold Increase ◽  
Bromophenol Blue ◽  
Shoot Apices ◽  
Fast Green ◽  
Floral Primordia ◽  
Histochemical Changes

Cauliflower plants were induced to flower after being grown at 42 °F for varying periods of time, depending on the cultivar. Some of the histochemical changes in the shoot apex at the beginning of, during, and after floral induction were studied. During floral induction there is about a 20-fold increase in the volume of nucleoli and about a 3-fold increase in volume of nuclei. Apices of vegetative plants stained with bromophenol blue at pH 2.3, show small and dense nucleoli, dense and granular nuclei, and a small amount of weakly staining cytoplasm. In contrast, cells of apices of induced plants stained with bromophenol blue at pH 2.3, show large and dense nucleoli, large and weakly staining nuclei; however, these cells contain more and denser cytoplasm. Sections of vegetative and induced apices stained with alkaline fast green stained differently from those stained with bromophenol blue. Nucleoli did not stain and cytoplasm stained faintly with fast green while chromosomes stained strongly. Deoxyribonucleic acid (DNA) content of vegetative and induced apices are similar. Shoot apices of vegetative plants contained little or no starch. However, shoot apices of plants grown at 42 °F accumulate large amounts of starch. Floral primordia which develop into functional flowers are glutted with starch, while floral primordia which abort are void of starch.

scholarly journals ANTIGEN-INDUCED CHANGES IN LYMPHOID CELL HISTONES

1965 ◽  
Vol 26 (1) ◽  
pp. 201-208 ◽  
Author(s):  
Maurice M. Black ◽  
Hudson R. Ansley
Keyword(s):  
Dna Content ◽  
Renal Cell ◽  
Acute Effect ◽  
Nuclear Proteins ◽  
Renal Cells ◽  
Cell Nuclei ◽  
Feulgen Staining ◽  
Fast Green ◽  
Induced Changes ◽  
Ammoniacal Silver

An acute effect of antigens on the nuclear histones of mouse thymocytes was investigated by means of cytophotometric measurements of thymocytes stained with ammoniacal-silver (A-S) and with fast green (FG). In addition, the DNA content was measured in terms of Feulgen staining. In terms of such staining it appeared that nuclei of control thymocytes contain a greater amount of nuclear histones and a higher histone/DNA ratio than do renal cell nuclei from the same animal. Within 1 hour after the injection of antigen the thymocyte nuclei appear to lose approximately 32 per cent and 20 per cent, respectively, of A-S and FG stainable nuclear proteins, while the Feulgen staining remains unchanged. Since the renal cell nuclei show no antigen-induced change in histone staining, the histone staining and histone/DNA ratios were found to be similar in the thymocytes and renal cells of the antigen-injected mice. The antigen-induced loss of thymocyte histones was also found to be associated with a change in the color of the A-S staining, from yellowish brown to black. This and other findings suggest that thymocyte nuclei contain an antigen-labile, lysine-rich histone. The implication of these observations in regard to the phenomenon of immunological competence is discussed and the need for continued investigation indicated.

scholarly journals Two Modes of Nanoleakage Expression in Single-step Adhesives

2002 ◽  
Vol 81 (7) ◽  
pp. 472-476 ◽  
Author(s):  
F.R. Tay ◽  
D.H. Pashley ◽  
M. Yoshiyama
Keyword(s):  
Silver Nitrate ◽  
Silver Ions ◽  
Single Step ◽  
Mineral Dissolution ◽  
Resin Infiltration ◽  
Transmission Electron ◽  
Hybrid Layers ◽  
Self Etch ◽  
Ammoniacal Silver ◽  
Spotted Pattern

Self-etch adhesives that etch, prime, and bond simultaneously should not exhibit incomplete resin infiltration within hybrid layers. We hypothesized that nanoleakage patterns in these systems are artifacts caused by mineral dissolution in mildly acidic silver nitrate. Resin-dentin interfaces bonded with four single-step, self-etch adhesives were examined for nanoleakage by conventional (pH 4.2) and basic ammoniacal (pH 9.5) silver nitrate and prepared for transmission electron microscopy. All adhesives exhibited a reticular mode of nanoleakage within hybrid layers when conventional silver nitrate was used. With ammoniacal silver nitrate, an additional spotted pattern of nanoleakage was observed within adhesive and hybrid layers. The reticular mode of nanoleakage in self-etch adhesives probably represents sites of incomplete water removal that leads to regional suboptimal polymerization. The spotted pattern identified with the use of ammoniacal silver nitrate probably represents potentially permeable regions in the adhesive and hybrid layers that result from the interaction of the basic diamine silver ions with acidic/hydrophilic resin components.

The Acceleration of Primordium Initiation as a Component of Floral Evocation in Lolium temulentum L

1996 ◽  
Vol 23 (5) ◽  
pp. 569 ◽  
Author(s):  
LT Evans ◽  
C Blundell
Keyword(s):  
Shoot Apex ◽  
Floral Development ◽  
Growth Retardant ◽  
Leaf Primordium ◽  
Essential Component ◽  
Lolium Temulentum ◽  
Long Day ◽  
External Sign ◽  
Floral Evocation

An acceleration of leaf primordium initiation by the shoot apex frequently follows floral evocation, but after varying intervals. The purpose of the experiments reported here was to define more closely the relation between this reduction of the plastochron and floral evocation, using the long day (LD) plant Lolium temulentum grown under closely controlled conditions.The acceleration begins at floral evocation, on the day after the first LD exposure, and increases after exposure to additional LDs. However, plants too young to be florally evoked by one LD nevertheless manifested an acceleration of primordium initiation, so the acceleration alone is not sufficient for evocation. Single applications of highly florigenic gibberellins (GAs), such as GA5, also accelerate the initiation of primordia and floral development, more so than does the weakly florigenic GA1. By contrast, single applications of the growth retardant Trinexapac-ethyl (CGA 163'935) to plants given one LD largely prevented the acceleration of primordium initiation but without inhibiting floral development. Thus, although the acceleration of primordium initiation by LD or by GA application is the first external sign of floral evocation in L. temulentum, it is neither a sufficient nor an essential component of it.

scholarly journals VARIABILITY OF THE SHAPE AND ARGENTAFFINITY OF THE GRANULES IN THE ENTEROENDOCRINE CELLS OF THE MOUSE DUODENUM

1974 ◽  
Vol 22 (10) ◽  
pp. 929-944 ◽  
Author(s):  
DAVID B. NICHOLS ◽  
HAZEL CHENG ◽  
C. P. LEBLOND
Keyword(s):  
Electron Microscope ◽  
Silver Nitrate ◽  
Wide Spectrum ◽  
Uranyl Acetate ◽  
Enteroendocrine Cells ◽  
Lead Citrate ◽  
A Cell ◽  
The Mean ◽  
Electron Microscopes ◽  
Ammoniacal Silver

The enteroendocrine cells of the mouse duodenum were examined in the light and electron microscopes by comparing Epon sections stained by Gomori's silver methenamine with adjacent sections stained by Masson's ammoniacal silver nitrate, iron hematoxylin or uranyl acetate and lead citrate. Furthermore, the granules present in the enteroendocrine cells stained with silver methenamine were investigated in the electron microscope: their shape was defined as either spherical or nonspherical and, in either case, their density was measured by cytophotometry. The comparison of adjacent sections of mouse duodenum by different techniques indicates that the granules of all enteroendocrine cells are stained by iron hematoxylin, whereas those of about 94% of the cells are stained by silver methenamine. Since silver methenamine stains exactly the same cells as ammoniacal silver nitrate, it may be used as a test of argentaffinity. It is concluded that about 94% of the enteroendocrine cells are argentaffin and about 6% are nonargentaffin. The argentaffin cells display a wide spectrum of granule shape. Nearly all of the granules of a cell may be spherical or nearly all nonspherical or, more commonly, there is a fair number of both kinds. In the few cells which are not argentaffin, over 70% of the granules are spherical. After silver methenamine staining, the mean density of spherical and nonspherical granules is statistically equal within any given cell. Yet, when cells are compared to one another, the mean density of the granules, and therefore the argentaffinity, increases with the proportion of nonspherical granules. It is concluded that, in the mouse duodenun, argentaffinity is most pronounced in the cells with irregular nonspherical granules, but it is by no means confined to such cells. Moreover, the argentaffinity as well as the shape of the granules varies within wide limits.

scholarly journals Inflorescence Initiation in Lolium Temulentum L. X. Changes in 32p Incorporation into Nucleic Acids of the Shoot Apex at Induction

1967 ◽  
Vol 20 (1) ◽  
pp. 13 ◽  
Author(s):  
AHGC Rijven ◽  
LT Evans
Keyword(s):  
Nucleic Acids ◽  
Shoot Apex ◽  
Floral Induction ◽  
Transient Increase ◽  
Lolium Temulentum ◽  
Long Day ◽  
32P Incorporation ◽  
Summit Region

Previous studies have shown an increase in RNA at the shoot apex of L. temulentum following floral induction, detectable chemically 2 days after induction, and by histochemical means after 1 day. Here, a transient increase in the incorporation of 32P, applied to leaves, into nucleic acids at the apex is shown to occur at about the time when the long-day stimulus is estimated to reach the shoot apex. The increased 32p incorporation due to the long-day exposure occurs throughout the apex, and is not confined to the summit region. Most of the 32p was incorporated into RNA.

Early increased expression of a cyclin-dependant protein kinase (LtCDKA1;1) during inflorescence initiation of the long day grass Lolium temulentum

2013 ◽  
Vol 40 (10) ◽  
pp. 986 ◽  
Author(s):  
Greg F. W. Gocal ◽  
Rod W. King
Keyword(s):  
Cell Division ◽  
Shoot Apex ◽  
Target Cells ◽  
Serine Threonine Kinase ◽  
Lolium Temulentum ◽  
Apical Dome ◽  
Long Day ◽  
Vegetative Shoot Apex ◽  
Weak Expression

Knowing where and when different genes express at the shoot apex during the transition to flowering will help in understanding this developmental switch. The CDKA family of serine/threonine kinase genes are appropriate candidates for such developmental switching as they are involved in the regulation of the G1/S and G2/M boundaries of the cell cycle (see review by Dudits et al. 2007) and so could regulate increases of cell division associated with flowering. Furthermore, in rice stems the gibberellin (GA) class of plant growth regulators rapidly upregulate CDKA expression and cell division. Thus, CDKA expression might be linked to the florigenic action of GA as a photoperiodically-generated, signal. For the grass Lolium temulentum L., we have isolated an LtCDKA1;1 gene, which is upregulated in shoot apices collected soon after the start of a single florally inductive long day (LD). In contrast to weak expression of LtCDKA1;1 in the vegetative shoot apex, in situ and PCR-based mRNA assays and immunological studies of its protein show very rapid increases in the apical dome at the time that florigenic signals arrive at the apex (<6 h after the end of the LD). By ~54 h LtCDKA1;1 mRNA is localised to the floral target cells, the spikelet primordia. Later both LtCDKA1;1 mRNA and protein are most evident in floret meristems. Only ~10% of cells within the apical dome are dividing at any time but the LD increase in LtCDKA1;1 may reflect an early transient increase in the mitotic index (Jacqmard et al. 1993) as well as a later increase when spikelet primordia form. Increased expression of an AP1-like gene (LtMADS2) follows that of LtCDKA1;1. Overall, LtCDKA1;1 is a useful marker of both early florigenic signalling and of later morphological/developmental aspects of the floral transition.

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