Cytokinins: Metabolism and Biological Activity of N6-(Δ2-Isopentenyl)adenosine and N6-(Δ2-Isopentenyl)adenine in Tobacco Cells and Callus

Two known metabolites of N6-(Δ2-isopentenyl)adenosine, namely N6-(Δ2-isopentenyl)adenine and N6-(3-hydroxy-3-methylbutyl)adenine, have been shown to be oxidized by xanthine oxidase. On the basis of ultraviolet absorption and mass spectral data, the oxidation products, in each case, have been tentatively identified as the 8-hydroxy and 2,8-dihydroxy derivatives.

Download Full-text

N6-(Δ2-isopentenyl)adenosine: hydrolysis by a nucleosidase isolated from Lactobacillus acidophilus cells

Canadian Journal of Microbiology ◽

10.1139/m75-091 ◽

1975 ◽

Vol 21 (5) ◽

pp. 633-638 ◽

Cited By ~ 1

Author(s):

J. Hordern ◽

R. H. Johnson ◽

B. D. McLennan

Keyword(s):

Substrate Specificity ◽

Lactobacillus Acidophilus ◽

Purine Nucleoside ◽

Bacterial Enzyme ◽

Electrophoretic Behavior ◽

Isopentenyl Adenine ◽

Isopentenyl Adenosine ◽

Rapid Conversion

A nucleosidase activity has been isolated from Lactobacillus acidophilus which rapidly hydrolyses N6-(Δ2-isopentenyl)adenosine to its corresponding base, N6-(Δ2-isopentenyl)adenine. The activity can be distinguished from the spleen exzyme (EC. 2.4.2.1), a purine nucleoside transferase, on the basis of its substrate specificity, electrophoretic behavior, and non-dependence on phosphate. The bacterial enzyme hydrolyzes both inosine and isopentenyl adenosine, giving Km values of 63.3 μM and 177 μM respectively. The presence of this enzyme in bacteria accounts for the rapid conversion of the parent nucleoside to isopentenyl adenine, which has been observed in these cells. The enzyme thus assumes importance as one of the catabolic activities available to the cell for metabolizing the cytokinin, N6-(Δ2-isopentenyl)adenosine.

Download Full-text

Cytokinin production by the fungi Taphrina cerasi and T. deformans

Canadian Journal of Botany ◽

10.1139/b74-207 ◽

1974 ◽

Vol 52 (7) ◽

pp. 1583-1589 ◽

Cited By ~ 26

Author(s):

James C. Johnston ◽

Edward J. Trione

Keyword(s):

Culture Medium ◽

Callus Tissue ◽

Zeatin Riboside ◽

Cytokinin Activity ◽

Liquid Media ◽

Migration Patterns ◽

Soybean Callus ◽

Isopentenyl Adenine ◽

Isopentenyl Adenosine ◽

Solvent Systems

Cytokinins were released into chemically defined liquid media by cultures of Taphrina cerasi and T. deformans. The presence of the cell-division factors was demonstrated with the soybean callus tissue assay, which is specific for the detection of cytokinins. Paper chromatography in four solvent systems, in conjunction with bioassays, revealed that T. cerasi produced compounds that have migration patterns similar to those of zeatin, zeatin riboside, N6-(Δ2-isopentenyl) adenine, and N6-(Δ2-isopentenyl)adenosine. T. deformans produced compounds with chromatographic properties similar to those of zeatin, zeatin riboside, and a substance(s) the migration of which is correlated with the Rf interval that included the positions of N6-(Δ2-isopentenyl) adenine and its riboside. A third type of cytokinin, the mobility of which differs from those of the cytokinin standards used, was also produced by T. deformans. The total cytokinin activity in cultures of T. cerasi was calculated to be about 2 μg kinetin-equivalents per liter of culture medium, and the amount released by T. deformans was about 4 μg kinetin-equivalents per liter of medium.

Download Full-text

Sexual and Apogamous Species of Woodferns Show Different Protein and Phytohormone Profiles

Frontiers in Plant Science ◽

10.3389/fpls.2021.718932 ◽

2021 ◽

Vol 12 ◽

Author(s):

Helena Fernández ◽

Jonas Grossmann ◽

Valeria Gagliardini ◽

Isabel Feito ◽

Alejandro Rivera ◽

...

Keyword(s):

Ribosome Biogenesis ◽

Experimental System ◽

Plant Reproduction ◽

Ultra Performance Liquid Chromatography ◽

Zeatin Riboside ◽

Fern Gametophyte ◽

Isopentenyl Adenine ◽

Physiological Approach ◽

Isopentenyl Adenosine ◽

Peculiar Case

The gametophyte of ferns reproduces either by sexual or asexual means. In the latter, apogamy represents a peculiar case of apomixis, in which an embryo is formed from somatic cells. A proteomic and physiological approach was applied to the apogamous fern Dryopteris affinis ssp. affinis and its sexual relative D. oreades. The proteomic analysis compared apogamous vs. female gametophytes, whereas the phytohormone study included, in addition to females, three apogamous stages (filamentous, spatulate, and cordate). The proteomic profiles revealed a total of 879 proteins and, after annotation, different regulation was found in 206 proteins of D. affinis and 166 of its sexual counterpart. The proteins upregulated in D. affinis are mostly associated to protein metabolism (including folding, transport, and proteolysis), ribosome biogenesis, gene expression and translation, while in the sexual counterpart, they account largely for starch and sucrose metabolism, generation of energy and photosynthesis. Likewise, ultra-performance liquid chromatography-tandem spectrometry (UHPLC-MS/MS) was used to assess the levels of indol-3-acetic acid (IAA); the cytokinins: 6-benzylaminopurine (BA), trans-Zeatine (Z), trans-Zeatin riboside (ZR), dyhidrozeatine (DHZ), dyhidrozeatin riboside (DHZR), isopentenyl adenine (iP), isopentenyl adenosine (iPR), abscisic acid (ABA), the gibberellins GA3 and GA4, salicylic acid (SA), and the brassinosteroids: brassinolide (BL) and castasterone (CS). IAA, the cytokinins Z, ZR, iPR, the gibberellin GA4, the brassinosteoids castasterone, and ABA accumulated more in the sexual gametophyte than in the apogamous one. When comparing the three apogamous stages, BA and SA peaked in filamentous, GA3 and BL in spatulate and DHRZ in cordate gametophytes. The results point to the existence of large metabolic differences between apogamous and sexual gametophytes, and invite to consider the fern gametophyte as a good experimental system to deepen our understanding of plant reproduction.

Download Full-text

Induction of in vitro flowering in Dendrobium Madame Thong-In (Orchidaceae) seedlings is associated with increase in endogenous N6-(Δ2-isopentenyl)-adenine (iP) and N6-(Δ2-isopentenyl)-adenosine (iPA) levels

Plant Cell Reports ◽

10.1007/s00299-008-0551-8 ◽

2008 ◽

Vol 27 (8) ◽

pp. 1281-1289 ◽

Cited By ~ 13

Author(s):

Guek Eng Sim ◽

Chong Jin Goh ◽

Chiang Shiong Loh

Keyword(s):

In Vitro Flowering ◽

Isopentenyl Adenine ◽

Isopentenyl Adenosine

Download Full-text

Virus-Like Particles in a Human Breast Cancer: Structural Similarity to Previously Reported Particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072332 ◽

1973 ◽

Vol 31 ◽

pp. 378-379

Author(s):

G. Kasnic ◽

S. E. Stewart ◽

C. Urbanski

Keyword(s):

Breast Cancer ◽

Biological Activity ◽

Human Breast Cancer ◽

Osteogenic Sarcoma ◽

Human Tumor ◽

Structural Similarity ◽

Cell Tumor ◽

Human Breast ◽

Human Tumor Cell ◽

Type Particle

We have reported the maturation of an intracisternal A-type particle in murine plasma cell tumor cultures and three human tumor cell cultures (rhabdomyosarcoma, lung adenocarcinoma, and osteogenic sarcoma) after IUDR-DMSO activation. In all of these studies the A-type particle seems to develop into a form with an electron dense nucleoid, presumably mature, which is also intracisternal. A similar intracisternal A-type particle has been described in leukemic guinea pigs. Although no biological activity has yet been demonstrated for these particles, on morphologic grounds, and by the manner in which they develop within the cell, they may represent members of the same family of viruses.

Download Full-text

Effects of Vincristine on Endothelial Microtubules in the Spinal Cord

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100090270 ◽

1976 ◽

Vol 34 ◽

pp. 58-59

Author(s):

John L. Beggs ◽

John D. Waggener ◽

Wanda Miller

Keyword(s):

Spinal Cord ◽

Biological Activity ◽

Horseradish Peroxidase ◽

Transport Mechanism ◽

Vasogenic Edema ◽

Vesicular Transport ◽

Close Proximity

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.

Download Full-text