Identification of the 12-oxophytoeienoic acid reductase (OPR) gene family in pepper (Capsicum annuum L.) and functional characterization of CaOPR6 in pepper fruit development and stress response.

The 12-oxophytoeienoic acid reductase (OPR) is a kind of enzyme in the octadecanoid biosynthesis pathway that determines the biosynthesis of jasmonic acid. Although the roles of OPRs have been extensively studied in several crop plants, little is known about the biological functions of OPR-encoding genes in Capsicum annuum plants. In this study, seven OPR family genes (CaOPR1-7) were identified from the C. annuum genome. The physical and chemical properties of CaOPR1-7 were further analyzed, including gene expression patterns, promoter elements, and chromosomal locations. The results showed that the seven CaOPR homologues could be divided into two subgroups, and CaOPR6 was highly similar to AtOPR3 in Arabidopsis. The expression of CaOPR6 was significantly induced by various stresses such as cold, salt, and pathogen infection, indicating that CaOPR6 plays important roles in response to abiotic and biotic stresses. Overall, these findings improve the understanding of the biological functions of CaOPR6 in the development of pepper fruit and stress response of pepper plants, and facilitate further studies on the molecular biology of OPR proteins in Solanaceae vegetables.

G protein coupled receptor kinase 5 modifies the nucleolar stress response activated by actinomycin D.

G protein coupled receptor kinase 5 (GRK5) is localized within the nucleus and moderates functions such as DNA transcription, in addition to its localization at the plasma membrane. In this report, we show that GRK5 modifies the nucleolar stress response activated by the DNA polymerase inhibitor, actinomycin D (ActD). We show an increased sensitivity to the apoptotic effects of ActD on cervical HeLa cells and the breast cancer cell line MDA MB 231 with reduced protein expression of GRK5. We also tested two types of breast cancer cells (MDA MB 231 and MCF7 cells) and found that the rate of response to ActD varied between them because they have innate differences in the protein expression of GRK5. We also found that GRK5 phosphorylates nucleophosmin (NPM1) at T199 before and during the early stages of ActD treatment. Phosphorylation at T199 increases the ability of NPM1 to interact with p14ARF in vitro, which may affect the protein expression levels of p14ARF. We found that the expression levels of p14ARF were lower in the cells transfected with the control shRNA, but higher in cells transfected with GRK5 shRNA. Collectively, this suggests that GRK5 modifies the nucleolar stress response associated with ActD.

Unveiling the acid stress response of clinical genotype Vibrio vulnificus isolated from the marine environments of Mangaluru coast, India.

Gastric acidity is one of the earliest host defences faced by ingested organisms, and successful pathogens need to overcome this hurdle. The objective of this study was the systematic assessment of acid-stress response of Vibrio vulnificus isolated from coastal regions of Mangaluru. Acid-shock experiments were carried out at pH 4.0 and pH 4.5, with different experimental conditions expected to produce a varied acid response. Exposure to mild acid before the acid shock was favourable to the bacteria but was dependent on cell population and pH of the media and was independent of the strains tested. Lysine-dependent acid response was demonstrated with reference to the previously identified lysine decarboxylase system. Additionally, the results showed that inoculation into oysters provided some level of protection against acid stress. Increased expression of lysine/cadaverine genes was observed upon the addition of ground oyster and was confirmed by quantitative real-time PCR. The potential role of ornithine was analyzed with regard to acid stress, but no change in the survival pattern was observed. These findings highlight the physiology of bacteria in acid stress.

Structural changes in the cell envelope of Yarrowia lipolytica yeast under stress conditions.

Ultrastructural changes in the cell envelope of the yeast Yarrowia lipolytica as a stress response were examined using electron microscopy. The formation of new cellular surface structures, including membrane vesicles, pore channels, and wall surface globules, were shown for the first time under conditions of oxidative (endogenous and exogenous) or thermal stress. This demonstrates once again that under stress conditions the microorganisms reveal properties previously unknown for them. Particularly noteworthy is the accumulation of silicon in the surface globules, which was revealed by X-ray microanalysis of the elemental composition of thin sections of cells. A multilayered plasmalemma instead of a 3-layered one is also characteristic for stressed cells. The envelope modifications above were observed only as a stress response and were not detected in stationary-growth-phase yeast cells that assume different physiological states. A decrease in the intracellular level of cAMP allows us to assume that a common factor activates defensive mechanisms thus explaining the similarity of the response under different stress conditions. The data presented not only enable visualization of the yeast stress response and add to our awareness of the diversity of adaptive reactions, but they also raise questions about the interrelations of the stress phenomena and their functional necessity in the cell.

Ethanol-induced stress response of Staphylococcus aureus.

Transcriptional profiles of 2 unrelated clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates were analyzed following 10% (v/v) ethanol challenge (15 min), which arrested growth but did not reduce viability. Ethanol-induced stress (EIS) resulted in differential gene expression of 1091 genes, 600 common to both strains, of which 291 were upregulated. With the exception of the downregulation of genes involved with osmotic stress functions, EIS resulted in the upregulation of genes that contribute to stress response networks, notably those altered by oxidative stress, protein quality control in general, and heat shock in particular. In addition, genes involved with transcription, translation, and nucleotide biosynthesis were downregulated. relP, which encodes a small alarmone synthetase (RelP), was highly upregulated in both MRSA strains following ethanol challenge, and relP inactivation experiments indicated that this gene contributed to EIS growth arrest. A number of persistence-associated genes were also upregulated during EIS, including those that encode toxin-antitoxin systems. Overall, transcriptional profiling indicated that the MRSA investigated responded to EIS by entering a state of dormancy and by altering the expression of elements from cross protective stress response systems in an effort to protect preexisting proteins.

Insights into thermoadaptation and the evolution of mesophily from the bacterial phylum Thermotogae.

Thermophiles are extremophiles that grow optimally at temperatures >45 °C. To survive and maintain function of their biological molecules, they have a suite of characteristics not found in organisms that grow at moderate temperature (mesophiles). At the cellular level, thermophiles have mechanisms for maintaining their membranes, nucleic acids, and other cellular structures. At the protein level, each of their proteins remains stable and retains activity at temperatures that would denature their mesophilic homologs. Conversely, cellular structures and proteins from thermophiles may not function optimally at moderate temperatures. These differences between thermophiles and mesophiles presumably present a barrier for evolutionary transitioning between the 2 lifestyles. Therefore, studying closely related thermophiles and mesophiles can help us determine how such lifestyle transitions may happen. The bacterial phylum Thermotogae contains hyperthermophiles, thermophiles, mesophiles, and organisms with temperature ranges wide enough to span both thermophilic and mesophilic temperatures. Genomic, proteomic, and physiological differences noted between other bacterial thermophiles and mesophiles are evident within the Thermotogae. We argue that the Thermotogae is an ideal group of organisms for understanding of the response to fluctuating temperature and of long-term evolutionary adaptation to a different growth temperature range.