1,221 research outputs found
Tandem and segmental gene duplication and recombination in the evolution of plant disease resistance genes
Relations among perspective taking, egocentrism, and self-esteem in late adolescents
This study examined the relations among perspective taking, egocentrism, and self-esteem in a sample of 113 undergraduate college students. Self-report measures of the the three constructs were used. Subjects in different levels of perspective taking did not differ significantly from one another in either egocentrism or self-esteem. Pearson correlations revealed that egocentrism was not related to self-esteem in level 2 perspective takers, but that these two constructs were negatively related in 3 perspective takers. Additionally, when subjects were in level 2 perspective taking, feedback did not alter their perceptions of themselves. However, when in level 3, feedback did affect subjects\u27 self-esteem, dependent upon whether the feedback was congruent or incongruent with the subjects\u27 self-esteem. The theoretical importance of the results was discussed
An improved prediction of chloroplast proteins reveals diversities and commonalities in the chloroplast proteomes of Arabidopsis and rice
Photosystem I lacking the PSI-G subunit has a higher affinity for plastocyanin and is sensitive to photodamage
Perspectives on Systematic Analyses of Gene Function in Arabidopsis thaliana: New Tools, Topics and Trends
Since the sequencing of the nuclear genome of Arabidopsis thaliana ten years ago, various large-scale analyses of gene function have been performed in this model species. In particular, the availability of collections of lines harbouring random T-DNA or transposon insertions, which include mutants for almost all of the ~27,000 A. thaliana genes, has been crucial for the success of forward and reverse genetic approaches. In the foreseeable future, genome-wide phenotypic data from mutant analyses will become available for Arabidopsis, and will stimulate a flood of novel in-depth gene-function analyses. In this review, we consider the present status of resources and concepts for systematic studies of gene function in A. thaliana. Current perspectives on the utility of loss-of-function and gain-of-function mutants will be discussed in light of the genetic and functional redundancy of many A. thaliana genes
Analysis of 101 nuclear transcriptomes reveals 23 distinct regulons and their relationship to metabolism, chromosomal gene distribution and co-ordination of nuclear and plastid gene expression
Post-endosymbiotic evolution of the proto-chloroplast was characterized by gene transfer to the nucleus. Hence, most chloroplast proteins are nuclear-encoded and the regulation of chloroplast functions includes nuclear transcriptional control. The expression profiles of 3292 nuclear Arabidopsis genes, most of them encoding chloroplast proteins, were determined from 101 different conditions and have been deposited at the GEO database (http://www.ncbi.nlm.nih.gov/geo/) under GSE1160-GSE1260. The 1590 most-regulated genes fell into 23 distinct groups of co-regulated genes (regulons). Genes of some regulons are not evenly distributed among the five Arabidopsis chromosomes and pairs of adjacent, co-expressed genes exist. Except regulons 1 and 2, regulons are heterogeneous and consist of genes coding for proteins with different subcellular locations or contributing to several biochemical functions. This implies that different organelles and/or metabolic pathways are co-ordinated at the nuclear transcriptional level, and a prototype for this is regulon 12 which contains genes with functions in amino acid and carbohydrate metabolism, as well as genes associated with transport or transcription. The co-expression of nuclear genes coding for subunits of the photosystems or encoding proteins involved in the transcription/translation of plastome genes (particularly ribosome polypeptides) (regulons 1 and 2, respectively) implies the existence of a novel mechanism that co-ordinates plastid and nuclear gene expression and involves nuclear control of plastid ribosome abundance. The co-regulation of genes for photosystem and plastid ribosome proteins escapes a previously described general control of nuclear chloroplast proteins imposed by a transcriptional master switch, highlighting a mode of transcriptional regulation of photosynthesis which is different compared to other chloroplast functions. From the evolutionary standpoint, the results provided indicate that functional integration of the proto-chloroplast into the eukaryotic cell was associated with the establishment of different layers of nuclear transcriptional control
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. We employed combinations of programs predicting N-terminal chloroplast transit peptides (cTPs) to identify 45 tentative cpPKs and 21 tentative cpPPs. However, test sets of 9 tentative cpPKs and 13 tentative cpPPs contain only 2 and 7 genuine cpPKs and cpPPs, respectively, based on experimental subcellular localization of their N-termini fused to the reporter protein RFP. Taken together, the set of enzymes known to be involved in the reversible phosphorylation of chloroplast proteins in A. thaliana comprises altogether now 6 cpPKs and 9 cpPPs, the function of which needs to be determined in future by functional genomics approaches. This includes the calcium-regulated PK CIPK13 which we found to be located in the chloroplast, indicating that calcium-dependent signal transduction pathways also operate in this organelle
Photosystem II core phosphorylation and photosynthetic acclimation require two different protein kinases
Illumination changes elicit modifications of thylakoid proteins
and reorganization of the photosynthetic machinery. This involves, in the short term, phosphorylation of photosystem II
(PSII) and light-harvesting (LHCII) proteins. PSII phosphorylation
is thought to be relevant for PSII turnover1,2, whereas LHCII
phosphorylation is associated with the relocation of LHCII and
the redistribution of excitation energy (state transitions) between
photosystems3,4. In the long term, imbalances in energy distribution
between photosystems are counteracted by adjusting
photosystem stoichiometry5,6. In the green alga Chlamydomonas
and the plant Arabidopsis, state transitions require the orthologous
protein kinases STT7 and STN7, respectively7,8. Here we
show that in Arabidopsis a second protein kinase, STN8, is
required for the quantitative phosphorylation of PSII core proteins.
However, PSII activity under high-intensity light is affected
only slightly in stn8 mutants, and D1 turnover is indistinguishable
from the wild type, implying that reversible protein phosphorylation
is not essential for PSII repair. Acclimation to changes in
light quality is defective in stn7 but not in stn8 mutants, indicating
that short-term and long-term photosynthetic adaptations are
coupled. Therefore the phosphorylation of LHCII, or of an
unknown substrate of STN7, is also crucial for the control of
photosynthetic gene expressio
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