Intracellular Photomorphogenesis

Schöpfer, Peter; Apel, Klaus

doi:10.1007/978-3-642-68918-5_11

Cited by 24 publications

(31 citation statements)

References 162 publications

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“…The two population model (6,7) and the "enzyme synthesis changeover" model (14,15) postulate a breakdown of glyoxysomes and a de novo formation of leaf peroxisomes, whereas the one population model (18) assumes that glyoxysomes are transformed into leaf peroxisomes. In contrast to the two population model, both the enzyme synthesis changeover model and the one population model predict peroxisomes of intermediary character, i.e.…”

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Catalase Synthesis and Turnover during Peroxisome Transition in the Cotyledons of Helianthus annuus L.

Eising

Gerhardt²

1989

Plant Physiol.

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Based on measurements of total catalase hematin and the degradation constants of catalase hematin, zero order rate constants for the synthesis of catalase were determined during the development of sunflower cotyledons (Hellanthus annuus L.).Catalase synthesis reached a sharp maximum of about 400 picomoles hematin per day per cotyledon at day 1.5 during the elaboration of glyoxysomes in the dark. During the transition of glyoxysomes to leaf peroxisomes (greening cotyledons, day 2.5 to 5) catalase synthesis was constant at a level of about 30 to 40 picomoles hematin per day per cotyledon. In the cotyledons of seedlings kept in the dark (day 2.5 to 5) catalase synthesis did not exceed 10 picomoles hematin per day per cotyledon. During the peroxisome transition in the light, total catalase hematin was maintained at a high level, whereas total catalase activity rapidly decreased. In continuous darkness, total catalase hematin decreased considerably from a peak at day 2. The results show that both catalase synthesis and catalase degradation are regulated by light. The tumover characteristics of catalase are in accordance with the concept that glyoxysomes are transformed to leaf peroxisomes as described by the one population model and contradict the two population model and the enzyme synthesis changeover model which both postulate de novo formation of the leaf peroxisome population and degradation of the glyoxysome population.Studies on the transition of peroxisomes from glyoxysomal to leafperoxisomal function in greening oil storing cotyledons have given rise to three models (1). The two population model (6, 7) and the "enzyme synthesis changeover" model (14, 15) postulate a breakdown of glyoxysomes and a de novo formation of leaf peroxisomes, whereas the one population model (18) assumes that glyoxysomes are transformed into leaf peroxisomes. In contrast to the two population model, both the enzyme synthesis changeover model and the one population model predict peroxisomes of intermediary character, i.e. organelles containing both glyoxysomal and leaf peroxisomal enzymes during the transition stage. According to the enzyme synthesis changeover model, leaf-type peroxisomes are formed as a consequence of a turnover of the whole organelles, whereas in the one population model individual enzyme turnover within the same organelle leads to a gradual replacement of glyoxysomal by leaf peroxisomal enzymes. ' Supported by grants from the Deutsche Forschungsgemeinschaft and the Gesellschaft zur Forderung der Westfilischen WilhelmsUniversitat.The existence of peroxisomes of intermediary character has been demonstrated recently in immunocytochemical studies (10, 1 1, 17). These results provide strong evidence against the two population model which postulates two independent populations of peroxisomes functioning exclusively as either glyoxysomes or leaf peroxisomes. The question, however, whether individual enzyme turnover or organelle turnover accounts for the formation of the intermediary peroxisomes, could not be de...

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Catalase Synthesis and Turnover during Peroxisome Transition in the Cotyledons of Helianthus annuus L.

Eising

Gerhardt²

1989

Plant Physiol.

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“…The enzymes present in both types of peroxisomes such as malate dehydrogenase and catalase are expected to be preserved in the glyoxysomes changing over to leaf perox-isomes. The third model called the 'enzyme synthesis changeover model' (24) suggests that, due to a continuous turnover of peroxisomes as whole organelles, changes in the synthesis rates of glyoxysomal and leaf peroxisomal enzymes lead to a gradual replacement ofglyoxysomes by leafperoxisomes via peroxisomes of intermediary character, so-called 'glyoxyperoxisomes' (25).…”

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Catalase Degradation in Sunflower Cotyledons during Peroxisome Transition from Glyoxysomal to Leaf Peroxisomal Function

Eising¹,

Gerhardt²

1987

Plant Physiol.

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“…microbodies are often found appressed to chloroplasts (26). These spatial associations have been considered indicative of the functions performed by microbodies and therefore diagnostic of the enzyme complement of specific microbodies (i.e., a microbody adjacent to a lipid body would be presumed to contain glyoxysomal enzyme activities) (21,22,26).…”

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Investigation of the glyoxysome-peroxisome transition in germinating cucumber cotyledons using double-label immunoelectron microscopy.

Titus¹,

Becker²

1985

The Journal of Cell Biology

142

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Microbodies in the cotyledons of cucumber seedlings perform two successive metabolic functions during early postgerminative development. During the first 4 or 5 d, glyoxylate cycle enzymes accumulate in microbodies called glyoxysomes. Beginning at about day 3, light-induced activities of enzymes involved in photorespiratory glycolate metabolism accumulate rapidly in microbodies. As the cotyledonary microbodies undergo a functional transition from glyoxysomal to peroxisomal metabolism, both sets of enzymes are present at the same time, either within two distinct populations of microbodies with different functions or within a single population of microbodies with a dual function.We have used protein A-gold immunoelectron microscopy to detect two glyoxylate cycle enzymes, isocitrate lyase (ICL) and malate synthase, and two glycolate pathway enzymes, serine:glyoxylate aminotransferase (SGAT) and hydroxypyruvate reductase, in microbodies of transition-stage (day 4) cotyledons. Double-label immunoelectron microscopy was used to demonstrate directly the co-existence of ICL and SGAT within individual microbodies, thereby discrediting the two-population hypothesis. Quantitation of protein A-gold labeling density confirmed that labeling was specific for microbodies. Quantitation of immunolabeling for ICL or SGAT in microbodies adjacent to lipid bodies, to chloroplasts, or to both organelles revealed very similar labeling densities in these three categories, suggesting that concentrations of glyoxysomal and peroxisomal enzymes in transition-stage microbodies probably cannot be predicted based on the apparent associations of microbodies with other organelles.

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Intracellular Photomorphogenesis

Cited by 24 publications

References 162 publications

Catalase Synthesis and Turnover during Peroxisome Transition in the Cotyledons of Helianthus annuus L.

Catalase Synthesis and Turnover during Peroxisome Transition in the Cotyledons of Helianthus annuus L.

Catalase Degradation in Sunflower Cotyledons during Peroxisome Transition from Glyoxysomal to Leaf Peroxisomal Function

Investigation of the glyoxysome-peroxisome transition in germinating cucumber cotyledons using double-label immunoelectron microscopy.

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