Ribonucleases and Ribonucleic Acid Breakdown

Farkas, G. L.

doi:10.1007/978-3-642-68347-3_8

Cited by 31 publications

(47 citation statements)

References 151 publications

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“…After 5 h of anoxia there is a significant increase in vacuolar pH from approximately 5.6 to 5.9 (Roberts et al, 1984a). Farkas (1982) suggested that small differences in pH optima of RNases are not of biological significance. Contrary to this view, we propose that slight differences in the pH optima of RNases located in the cytoplasm or vacuole may be of biological importance in response to O, deprivation.…”

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

“…The induction of RNase activity in response to phosphate starvation and senescence may allow for remobilization of phosphate to other tissues. There is also evidence that increased activity of certain RNases is involved in programmed cell death processes, such as xylem formation and endosperm utilization, during germination (Farkas, 1982;Green, 1994). In contrast, a reduction in activity of a 27-kD RNase of wheat leaves occurs in response to heat shock, concomitantly with a change in electrophoretic mobility that is possibly due to dephosphorylation (Chang and Gallie, 1997).…”

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confidence: 99%

“…Early work by Trewavas (1970) provided direct evidence that cytoplasmic rRNA levels in Lemna minor fronds are reduced in response to nutrient deficiency, as a result of decreased rRNA synthesis and increased rRNA degradation. However, numerous biochemical analyses of RNases have failed to reveal a relationship between total cellular RNase activity and RNA content (for review, see Farkas, 1982). At this time, the identities of RNases specifically involved in degradation of rRNA and ribosomes are unknown.…”

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RNase Activities Are Reduced Concomitantly with Conservation of Total Cellular RNA and Ribosomes in O2-Deprived Seedling Roots of Maize

1997

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RNase activities are modulated during plant development and in response to certain abiotic and biotic cues and are expected to play a role in the regulation of RNA levels and turnover (for reviews, see Wilson, 1975;Farkas, 1982;Green, 1994). The electrophoretic and biochemical nature of a number of individual plant RNases and nucleases have been described, and knowledge of the function of specific RNases is slowly accumulating. The best-characterized plant RNases are the extracellular S-RNases and S-like RNases. The S-RNases are glycoproteins of the floral stigma that play a role in the gametophytic self-incompatibility mechanism in several solanaceous species. Two RNases with biochemical characteristics of S-RNases are active in developing tomato (Lycopersicon esculentum L.) fruit (McKeon et al., 1991). Phylogenetic analysis confirmed that the S-like RNases of Arabidopsis (RNS1, RNS2, and RNS3) are evolutionarily related to S-RNases, but that these enzymes do not play a role in

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Section: Discussionmentioning

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RNase Activities Are Reduced Concomitantly with Conservation of Total Cellular RNA and Ribosomes in O2-Deprived Seedling Roots of Maize

1997

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“…In an attempt to elucidate the hypothesized (12,31) role of plant vacuoles in cellular RNA breakdown, we have shown in previous studies that isolated vacuoles (13,14) from suspension-cultured tomato cells (28) contain the bulk (60-80%) of the intracellular RNA-degrading activity (1). The vacuolar ribonucleolytic enzyme has been purified (2), extensively characterized (2, 3), and classified as RNase I according to the classification of Wilson (31).…”

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Evidence for RNA-Oligonucleotides in Plant Vacuoles Isolated from Cultured Tomato Cells

Abel

Blume²,

Glund³

1990

Plant Physiol.

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We have shown that highly purified vacuoles of suspensioncultured tomato (Lycoperskon esculentum) cells contain RNAoligonucleotides, using two different approaches to label and detect RNA: (a) in vivo labeling of cellular RNA with [5-3H]uridine, followed by preparation of vacuoles from protoplasts and by quantification of radioactively labeled material; and (b) in vitro labeling and analysis on sequencing gels of nucleic acids prepared from tomato vacuoles and their identification as RNA. The intravacuolar location of the RNA found in vacuolar preparations was concluded from analyzing for RNA intact organelles after repeated flotation steps as well as ribonuclease A treatment.About 3% of the RNA in protoplasts was localized within vacuoles, exceeding by severalfold the contribution made by contamination with unlysed protoplasts and subcellular organelles. Investigation of the size distribution of vacuolar RNA revealed an oligonucleotide pattern strikingly different from that which would arise from contaminating protoplasts; vacuolar RNA fragments are considerably shorter than 80 nucleotides. Characterization of these oligoribonucleotides (3'-phosphorylated termini; relatively rich in pyrimidines) as possible products of tomato vacuolar ribonuclease I action, and, in addition, enzymatic hydrolysis of vacuolar RNA by inherent enzyme activities in lysed vacuole preparations support the hypothesis that plant vacuoles are involved in cellular nucleolytic processes.Involvement in degradative pathways of the cellular turnover of macromolecules is thought to be one of the most prominent functions of vacuoles in plants (for a review, see refs. 5 and 6). This has mainly been concluded from the occurrence of a broad spectrum of acid hydrolases in plant vacuoles (24), rendering this organelle homologous to the lysosomes in animal cells (6).Until now, proteolysis is the best-characterized lytic process in that plant vacuoles have been found to participate. In most cases, intracellular proteases have been found to be located in the vacuole (see ref. 6). This organelle was shown to be directly involved in the breakdown of storage proteins during germination in seeds (22) and to be able to acquire and degrade intracellular proteins in suspension-cultured sycamore cells (8,9).In contrast to these studies, which support the role of vacuolar proteases in the continuous turnover of cellular proteins, little is as yet known about a possible nucleolytic function of plant vacuoles. Although vacuoles contain a set of potentially nucleolytically acting enzymes [nuclease, ribonuclease, acid phosphatase (24)], which could completely digest nucleic acid substrates down to nucleosides and phosphate, the biological significance of the individual vacuolar enzymes and of the vacuolar compartment per se in intracellular nucleolytic events remains to be proven.In

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Self-incompatibility and pollen rejection in angiosperms

McCubbin¹,

Kao²

1996

In Vitro Haploid Production in Higher Plants

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Ribonucleases and Ribonucleic Acid Breakdown

Cited by 31 publications

References 151 publications

RNase Activities Are Reduced Concomitantly with Conservation of Total Cellular RNA and Ribosomes in O2-Deprived Seedling Roots of Maize

RNase Activities Are Reduced Concomitantly with Conservation of Total Cellular RNA and Ribosomes in O2-Deprived Seedling Roots of Maize

Evidence for RNA-Oligonucleotides in Plant Vacuoles Isolated from Cultured Tomato Cells

Self-incompatibility and pollen rejection in angiosperms

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