Search results for "Chloroplast"
showing 10 items of 145 documents
Death of mitochondria during programmed cell death of leaf mesophyll cells
2005
The role of plant mitochondria in the programmed cell death (PCD) is widely discussed. However, spectrum and sequence of mitochondrial structural changes during different types of PCD in leaves are poorly described. Pea, cucumber and rye plants were grown under controlled growing conditions. A part of them were sprinkled with ethylene releaser to accelerate cell death. During yellowing the palisade parenchyma mitochondria were attracted to nuclear envelope. Mitochondrial matrix became electron translucent. Mitochondria entered vacuole by invagination of tonoplast and formed multivesicular bodies. Ethephon treatment increased the frequency of sticking of mitochondria to the nuclear envelope …
A Rapid Method for Amplification of Plastome DNA-Fragments from Spinacia oleracea by PCR
1993
Summary Polymerase Chain Reaction (PCR) was used as a very powerful technique to amplify DNA-fragments. Isolated chloroplasts and a crude suspension of small leaf pieces of Spinacia oleracea were osmotically shocked and subsequently heated. Aliquots of the resulting homogenate including the organelle DNA were directly added to basic reaction mixtures to carry out PCR without additional isolation- or purification steps. A 180 by DNA-fragment from the psbA-gene was amplified in both cases. In parallel, plasmid-DNA (pHT1) bearing the psbA-gene was subjected to PCR retaining unchanged reaction conditions. Identical DNA-fragments were obtained, as the following sequencing revealed. With the meth…
Messenger RNA degradation is initiated at the 5′ end and follows sequence- and condition-dependent modes in chloroplasts
2011
Using reporter gene constructs, consisting of the bacterial uidA (GUS) coding region flanked by the 5' and 3' regions of the Chlamydomonas rbcL and psaB genes, respectively, we studied the degradation of mRNAs in the chloroplast of Chlamydomonas reinhardtii in vivo. Extending the 5' terminus of transcripts of the reporter gene by more than 6 nucleotides triggered rapid degradation. Placing a poly(G) tract, known to pause exoribonucleases, in various positions downstream of the 5' terminus blocked rapid degradation of the transcripts. In all these cases the 5' ends of the accumulating GUS transcripts were found to be trimmed to the 5' end of the poly(G) tracts indicating that a 5' → 3' exori…
Disassembling Papaver: a restriction site analysis of chloroplast DNA
1992
The results from a chloroplast DNA restriction site analysis of the genera Papaver and Roemeria of subf. Papaveroideae (Papaveraceae) and five outgroup taxa are presented. Papaver is represented by 14 species of eight of the 11 sections recognized, Roemeria by two of its three species. Hunnemannia fumariifolia (subf. Eschscholzioideae), Chelidonium majus (subf. Chelidonioideae), Romneya coulteri, Argemone munita and Stylomecon heterophyllum (all subf. Papaveroideae) were chosen as outgroups. DNAs were digested with 24 restriction enzymes. The major results from this analysis are: 1. Papaver, Roemeria and Stylomecon form a monophyletic group supported by at least 17 restriction site mutation…
Control of the ribulose 1,5-bisphosphate carboxylase/oxygenase activity by the chloroplastic glutathione pool.
2014
The CO2-fixing activity of ribulose 1,5-bisphosphate carboxylase/oxygenase depends on the redox state of its cysteines. Disulfides like cystamine or 5,5'-dithio-bis(2-nitrobenzoic acid), but not oxidized glutathione, switch the enzyme to the inactive oxidized form. Conversely, thiols like cysteamine, cysteine, dithiotreitol or 2-mercaptoethanol, but not reduced glutathione, recover enzymatic activity after a previous oxidation. Direct regulation of the carboxylase activity by the chloroplastic glutathione pool is hindered by kinetic barriers impeding access to the critical residues. However, reduced glutathione can drive the recovery of activity by means of minute amounts of smaller interme…
The Synapse-Like Interaction between Chloroplast, dictyosome, and Other Cell Compartments during Increased Ethylene Production in Leaves of Rye (Seca…
2000
Rye (Secale cereale L.) plants were treated with an ethylene releaser ethephon (2-chloroethylphosphonic acid) in concentration of 4×10−2 M. We studied electron microscopically, if and how chloroplasts interact with well-documented sites of ethylene production/binding, i.e., with endoplasmic reticulum, dictyosomes, mitochondria, plasma membrane, and tonoplast. During the sharp increase of ethylene synthesis in mesophyll cells of rye leaves, the direct local continguity of chloroplast envelope or envelope protrusions with the above mentioned cell compartments was typical. Moreover, a large number and diversity of versatile chloroplast-dictyosome associations were conspicuous, in which both th…
Relationships between suspended and sediment organic matter in a semi- enclosed marine system: The Stagnone di Marsala sound (Western Sicily)
1997
To gather information on the interactions between the sediment and suspended organic matter pools in the Stagnone di Marsala, water and sediment samples were collected, on a monthly basis, at 11 stations. Water temperature and salinity showed a clear seasonality whilst particulate and sediment organic matter did not show any clear seasonal pattern. Relative abundances of suspended and sediment organic matter, on the other hand, appeared to be site-dependent and controlled mainly by the dynamic balance between resuspension and sedimentation. High quantities of both suspended and sediment total organic matter were present, while very low algal biomasses (in terms of chlorophyll-a concentratio…
Do island plant populations really have lower genetic variation than mainland populations? Effects of selection and distribution range on genetic div…
2015
Ecological and evolutionary studies largely assume that island populations display low levels of neutral genetic variation. However, this notion has only been formally tested in a few cases involving plant taxa, and the confounding effect of selection on genetic diversity (GD) estimates based on putatively neutral markers has typically been overlooked. Here, we generated nuclear microsatellite and plastid DNA sequence data in Periploca laevigata, a plant taxon with an island–mainland distribution area, to (i) investigate whether selection affects GD estimates of populations across contrasting habitats; and (ii) test the long-standing idea that island populations have lower GD than their mai…
The evolutionary history of the Arabidopsis arenosa complex: diverse tetraploids mask the Western Carpathian center of species and genetic diversity.
2012
The Arabidopsis arenosa complex is closely related to the model plant Arabidopsis thaliana. Species and subspecies in the complex are mainly biennial, predominantly outcrossing, herbaceous, and with a distribution range covering most parts of latitudes and the eastern reaches of Europe. In this study we present the first comprehensive evolutionary history of the A. arenosa species complex, covering its natural range, by using chromosome counts, nuclear AFLP data, and a maternally inherited marker from the chloroplast genome [trnL intron (trnL) and trnL/F intergenic spacer (trnL/F-IGS) of tRNA(Leu) and tRNA(Phe), respectively]. We unravel the broad-scale cytogeographic and phylogeographic pa…
Light-induced proton slip and proton leak at the thylakoid membrane
2005
A treatment of leaves of Spinacia oleracea L. with light or with the thiol reagent dithiothreitol in the dark led to partly uncoupled thylakoids. After induction in intact leaves, the partial uncoupling was irreversible at the level of isolated thylakoids. We distinguish between uncoupling by proton slip, which means a decrease of the H+/e(-) -ratio due to less efficient proton pumping, and proton leak as defined by enhanced kinetics of proton efflux. Proton slip and proton leak made about equal contributions to the total uncoupling. The enhanced proton efflux kinetics corresponded to reduction of subunit CF1-gamma of the ATP synthase as shown by fluorescence labeling of thylakoid proteins …