Chloroplast proteins without cleavable transit peptides: rare exceptions or a major constituent of the chloroplast proteome?

Most chloroplast proteins (cp proteins) are nucleus-encoded, synthesized on cytosolic ribosomes as precursor proteins containing a presequence (cTP), and post-translationally imported via the Tic/Toc complex into the organelle, where the cTP is removed. Only a few unambiguous instances of cp proteins that do not require cTPs (non-canonical cp proteins) have been reported so far. However, the survey of data from large-scale proteomic studies presented here suggests that the fraction of such proteins in the total cp proteome might be as large as approximately 30%.

A Survey of Chloroplast Protein Kinases and Phosphatases in Arabidopsis thaliana.

Protein phosphorylation is a major mode of regulation of metabolism, gene expression and cell architecture. In chloroplasts, reversible phosphorylation of proteins is known to regulate a number of prominent processes, for instance photosynthesis, gene expression and starch metabolism. The complements of the involved chloroplast protein kinases (cpPKs) and phosphatases (cpPPs) are largely unknown, except 6 proteins (4 cpPKs and 2 cpPPs) which have been experimentally identified so far.

Retrograde plastid redox signals in the expression of nuclear genes for chloroplast proteins of Arabidopsis thaliana.

Excitation imbalances between photosystem I and II generate redox signals in the thylakoid membrane of higher plants which induce acclimatory changes in the structure of the photosynthetic apparatus. They affect the accumulation of reaction center and light-harvesting proteins as well as chlorophylls a and b. In Arabidopsis thaliana the re-adjustment of photosystem stoichiometry is mainly mediated by changes in the number of photosystem I complexes, which are accompanied by corresponding changes in transcripts for plastid reaction center genes.

Nanomolar concentrations of epothilone D inhibit the proliferation of glioma cells and severely affect their tubulin cytoskeleton.

The purpose of this study was to investigate the potential effects of epothilones (EPOs), a new class of microtubule stabilizing cytotoxic drugs, on glioma cells in vitro. The effects of 1, 10 and 100 nM concentrations of EPO D in four malignant human glioma cell lines were measured using a microtiter-tetrazolium assay. Besides the cell lines U87MG, U138MG and LN405, one cell line was used, which had been derived from a recurrent and therapy-resistant glioblastoma in our laboratory.

Cytoplasmic N-terminal protein acetylation is required for efficient photosynthesis in Arabidopsis.

The Arabidopsis atmak3-1 mutant was identified on the basis of a decreased effective quantum yield of photosystem II. In atmak3-1, the synthesis of the plastome-encoded photosystem II core proteins D1 and CP47 is affected, resulting in a decrease in the abundance of thylakoid multiprotein complexes. DNA array-based mRNA analysis indicated that extraplastid functions also are altered.

Covariations in the nuclear chloroplast transcriptome reveal a regulatory master-switch.

The evolution of the endosymbiotic progenitor into the chloroplast organelle was associated with the transfer of numerous chloroplast genes into the nucleus. Hence, inter-organellar signalling, and the co-ordinated expression of sets of nuclear genes, was set up to control the metabolic and developmental status of the chloroplast. Here, we show by the differential-expression analysis of 3,292 genes, that most of the 35 environmental and genetic conditions tested, including plastid signalling mutations, elicit only three main classes of response from the nuclear chloroplast transcriptome.

Phase II trial of gemcitabine in patients with pretreated advanced soft tissue sarcomas.

Because of the low number of active cytotoxic drugs and their limited activity, the evaluation of new anti-cancer agents for their activity in soft tissue sarcomas is a continuing need. The objectives of this prospective phase II trial of gemcitabine were to estimate the response rate and to define the toxicities of prolonged infusions of low-dose gemcitabine in patients with pretreated advanced soft tissue sarcomas. Patients were eligible if they had a histologic diagnosis of unresectable, recurrent or metastatic, progressive soft tissue sarcoma, and if they had been treated with at least one prior chemotherapy consisting of an anthracycline- and/or ifosfamide-containing regimen.

Subacute encephalopathy after combination chemotherapy including moderate-dose methotrexate in a patient with gastric cancer.

An episode of subacute encephalopathy after the infusion of a moderate dose of methotrexate (1500 mg/m2) (MTX) is reported in a young adult with metastastic gastric cancer. Weakness of the right arm, focal seizures, lethargy and confusion appeared on day 10. High signal intensity in periventricular white matter was observed on T2-weighted magnetic resonance imaging.

[Intensification of chemotherapy dosage in metastatic breast carcinoma?].

During the last decades, improvements in the median survival time in patients with metastasized carcinoma of the mamma were hardly achieved. There ist still a lack of evidence that the increase in the rate of remissions due to conventional chemotherapy leads to an improvement in survival time. In 450 female patients with metastasized carcinoma of the mamma, the survival time was analyzed with the begin of the metastatic spread in relation to the treatment success of the first palliative chemotherapy.