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 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).

Ontogenetical and experimental studies of the floral apex of Portulaca grandiflora. 1. Histology of transformation of the shoot apex into the floral apex

1969 ◽  
Vol 47 (1) ◽  
pp. 133-140 ◽  
Author(s):  
Siti Raswati Soetiarto ◽  
Ernest Ball
Keyword(s):  
Shoot Apex ◽  
Experimental Studies ◽  
Floral Meristem ◽  
Vegetative Shoot ◽  
Floral Organs ◽  
Mature Flower ◽  
Floral Apex ◽  
Portulaca Grandiflora ◽  
Floral Primordia ◽  
Vegetative Shoot Apex

The vegetative apex was a low dome consisting of two layers of tunica surmounting a very small corpus. Foliar primordia originated as periclines in the flanks of T2. The transition apex became first a steep cone and then a hemisphere. All floral primordia—the two bracts, the two sepals, the several whorls of petals, the several whorls of stamens, and the carpels—originated in the manner of leaves, as periclines in T2 on the flanks of the apex. All appendages, including carpels, were therefore lateral. In the early transition, the apex had a brief stage in which there were three tunica layers, but the inner one was lost with the onset of the sepals. The bracts and the first sepal continued the normal positions of primordia for the vegetative phyllotaxy of 3/8, but with the second sepal, this phyllotaxy was lost, and petals, stamens, and carpels were produced in whorls. While leaves, bracts, sepals, and petals were produced in acropetal sequence, stamens were produced in basipetal sequence, and carpels appeared simultaneously. After carpels were formed, the rest of the floral apex underwent a brief period of expansion growth, achieving a diameter comparable to that of a shoot apex, but its substance was eventually incorporated into the carpel margins, which later produced the ovules. This agrees with the determinate nature of the floral apex. During the development of the first series of floral organs, the floral apex underwent continued increase in area, finally achieving a diameter several times that of the vegetative shoot apex. Its size and form were such that they were compared to those of some inflorescence apices. After development of the first series of floral organs, the subjacent tissues to the floral meristem underwent divisions and elongation at right angles to the axis, causing at first a flattening of the meristem, and eventually a cup-shaped form, with the carpels attached in the bottom of a bowl. The mature flower was thus perigynous, but this development arose quite differently from the perigyny as it is known from ontogenetic studies in the Rosaceae.

Analytical studies on the shoot apex of Helianthus annuus

1969 ◽  
Vol 47 (9) ◽  
pp. 1367-1375 ◽  
Author(s):  
T. A. Steeves ◽  
M. Anne Hicks ◽  
J. M. Naylor ◽  
Patricia Rennie
Keyword(s):  
Helianthus Annuus ◽  
Shoot Apex ◽  
Culture Medium ◽  
Deoxyribonucleic Acid ◽  
Vegetative State ◽  
Central Zone ◽  
Apical Region ◽  
Cell Nuclei ◽  
Liquid Culture Medium ◽  
Vegetative Shoot Apex

The vegetative shoot apex of Helianthus annuus contains a central zone in which the cell nuclei are relatively large and stain faintly in the Feulgen reaction. Excised apices in the vegetative state were supplied with thymidine-H3 through their sterile, liquid culture medium. Autoradiography after 24 or 48 hours of feeding revealed no significant incorporation of the labeled precursor into central zone nuclei, but extensive incorporation in peripheral regions of the apex. It is concluded that during vegetative growth deoxyribonucleic acid (DNA) synthesis and mitosis are arrested in the central zone or reduced to an extremely slow rate. Microspectrophotometry, however, indicates that the central zone nuclei are not held at the 2C level. With the onset of flowering, cytological zonation disappears in the apex and the incorporation of thymidine-H3 is uniformly heavy throughout the apical region.

scholarly journals The riddle of phyllotaxis: exquisite control of divergence angle

2016 ◽  
Vol 85 (4) ◽  
Author(s):  
Takuya Okabe
Keyword(s):  
Plant Species ◽  
Shoot Apex ◽  
Evidence Base ◽  
Divergence Angle ◽  
Shoot Apices ◽  
Essential Point

Phyllotaxis studies published in German in the 1930s have reported intriguing regularity in the arrangement of incipient leaves on shoot apices of a wide variety of plant species. However, these studies have received little attention today, even though they provide a crucial evidence base for understanding this mathematical phenomena. Here I recapitulate the essential point by means of illustrative examples. It is emphasized that accurate control of apical divergence angle is at the heart of the numerical riddle of spiral phyllotaxis. The accurate patterning at the shoot apex has an unexpected evolutionary benefit of being optimally adaptive in the subsequent events of phyllotactic change to occur on an elongating shoot.

scholarly journals Regulation of tropomyosin gene expression during myogenesis.

1981 ◽  
Vol 1 (3) ◽  
pp. 289-301 ◽  
Author(s):  
M Moss ◽  
R Schwartz
Keyword(s):  
Gene Expression ◽  
Nucleic Acid ◽  
Messenger Rna ◽  
Deoxyribonucleic Acid ◽  
Critical Role ◽  
Fold Increase ◽  
Nucleic Acid Content ◽  
Total Nucleic Acid ◽  
Synthetic Capacity ◽  
Rna Levels

In skeletal muscle, tropomyosin has a critical role in transduction of calcium-induced contraction. Presently, little is known about the regulation of tropomyosin gene expression during myogenesis. In the present study, qualitative and quantitative changes in the nucleic acid populations of differentiating chicken embryo muscle cells in culture have been examined. Total nucleic acid content per nucleus increased about fivefold in fully developed myotubes as compared to mononucleated myoblasts. The contribution of deoxyribonucleic acid to the total nucleic acid population decreased from 24% in myoblasts to 5% of total nucleic acid in myotubes. Concomitant with the decrement in deoxyribonucleic acid contribution to total nucleic acid was an increase in polyadenylated ribonucleic acid (RNA) content per cell which reached levels in myotubes that were 17-fold higher than those of myoblasts. Specific changes in the RNA population during myogenesis were further investigated by quantitation of the synthetic capacity (messenger RNA levels) per cell for alpha- and beta-tropomyosin. Cell-free translation and immunoprecipitation demonstrated an approximately 40-fold increase in messenger RNA levels per nucleus for alpha- and beta-tropomyosin after fusion in the terminally differentiated myotubes. Indirect immunofluorescence with affinity-purified tropomyosin antibodies demonstrated the presence of tropomyosin-containing filaments in cells throughout myogenesis. Thus, the tropomyosin genes are constitutively expressed during muscle differentiation through the production of tropomyosin messenger RNA and translation into tropomyosin protein.

Growth hormone and mammary gland lobule-alveolar development

1961 ◽  
Vol 201 (2) ◽  
pp. 259-263 ◽  
Author(s):  
Richard C. Moon
Keyword(s):  
Growth Hormone ◽  
Mammary Gland ◽  
Dna Content ◽  
Deoxyribonucleic Acid ◽  
Cellular Proliferation ◽  
Estradiol Benzoate ◽  
The Mean ◽  
Alveolar Formation ◽  
Inguinal Glands ◽  
Range Of Values

The effect of growth hormone on mammary gland lobule-alveolar growth in the ovariectomized rat was studied using deoxyribonucleic acid (DNA) of the abdominal-inguinal glands as an index of the degree of cellular proliferation. The administration of 1 mg growth hormone in combination with 2 µg estradiol benzoate for 19 days resulted in alveolar formation and an increase in mammary DNA content above that resulting from injections of either hormone alone. The mean DNA concentration of glands of rats treated with 2 µg estradiol, 6 mg progesterone, 3 µg/100 g l-thyroxine, and 0.5, 1.0, 1.5, and 2.0 mg growth hormone was significantly greater than that of animals receiving only the estradiol, progesterone, and thyroxine. The increase in the mean DNA content was due to a shift in the range of values to a higher plane and did not result from an elevated DNA in only a few animals. It is suggested that the administration of growth hormone during the growth phase of the mammary gland may have a beneficial effect on the subsequent lactation.

The behavior of shoot apices of Tulipa in relation to floral induction

1971 ◽  
Vol 25 (2) ◽  
pp. 310-335 ◽  
Author(s):  
F.C. Steward ◽  
J.T. Barber ◽  
E.F. Bleichert ◽  
W.M. Roca
Keyword(s):  
Floral Induction ◽  
Shoot Apices

scholarly journals MICROCHEMICAL DEOXYRIBONUCLEIC ACID DETERMINATION IN INDIVIDUAL CELLS

1961 ◽  
Vol 9 (3) ◽  
pp. 619-626 ◽  
Author(s):  
Jan-Erik Edström ◽  
Jerzy Kawiak
Keyword(s):  
Dna Content ◽  
Mitotic Cycle ◽  
Deoxyribonucleic Acid ◽  
Test Material ◽  
Cell Nuclei ◽  
Fixed Tissue ◽  
Dna Contents ◽  
Two Factors ◽  
Good Agreement

A method for the quantitative determination of DNA in the 50 to 500 µµg. range is presented. Cells or cell nuclei are isolated individually from fixed tissue by means of micromanipulation. The tissue units in question are extracted in an oil chamber with deoxyribonuclease solution. The extracts are evaporated to dryness and redissolved to lens-shaped drops, the DNA contents of which are determined by a photographic-photometric procedure in ultraviolet light. Determinations on calf thymocytes and rat spermatids show a relatively good agreement with biochemical data. The present method tends, however, to give some. what higher values than those reported earlier. The coefficient of variation for analytical values from test material is about ± 10 per cent. The method has been applied to cells from the axolotl, adults as well as tadpoles. Germ cells (spermatids and spermatocytes) do not show any evidence of a biological variation in DNA content. Cells from proliferating tissues give an increased spread of the DNA values. It could be shown, for epithelial cells, that there are at least two factors determining the DNA content of these cells. One is the fact that the cells are investigated at different phases of the mitotic cycle; the other is the fact that the DNA synthesis cycle occupies different ranges for different cells.

Sign in / Sign up

Export Citation Format

Share Document