APUM23, a nucleolar Puf domain protein, is involved in pre-ribosomal RNA processing and normal growth patterning in Arabidopsis

Pumilio, an RNA-binding protein that contains tandemly repeated Puf domains, is known to repress translational activity in early embryogenesis and polarized cells of non-plant species. Although Pumilio proteins have been characterized in many eukaryotes, their role in plants is unknown. In the present study, we characterized an Arabidopsis Pumilio-encoding gene, APUM23. APUM23 is constitutively expressed, with higher levels in metabolically active tissues, and its expression is up-regulated in the presence of either glucose or sucrose. The T-DNA insertion mutants apum23-1 and apum23-2 showed slow growth, with serrated and scrunched leaves, an abnormal venation pattern, and distorted organization of the palisade parenchyma cells - a phenotype that is reminiscent of nucleolin and ribosomal protein gene mutants. Intracellular localization studies indicate that APUM23 predominantly localizes to the nucleolus. Based on this localization, rRNA processing was examined. In apum23, 35S pre-rRNA, and unprocessed 18S and 5.8S poly(A) rRNAs, accumulated without affecting the steady-state levels of mature rRNAs, indicating that APUM23 is involved in the processing and/or degradation of 35S pre-rRNA and rRNA maturation by-products. The apum23 mutant showed increased levels of 18S rRNA biogenesis-related U3 and U14 small nucleolar RNAs (snoRNAs) and accumulated RNAs within the nucleolus. Our data suggest that APUM23 plays an important role in plant development via rRNA processing.     

Enhanced growth and quality of St. John's wort (Hypericum perforatum l.) under photoautotrophic in vitro conditions

Summary Photomixotrophic (Pm) micropropagation systems (ones that use a sugar-containing medium) have been used by many rescarchers for transplant production of St. John's wort. However, these methods have not yet been adopted for commercial applications, probably due to the low percentage of regeneration in vitro, and a low growth rate after transplanting ex vitro. In contrast, it is well known that the use of a photoautotrophic (Pa) micropropagation system (one that uses sugar-free medium) can promote the growth and improve the quality of plantlets in vitro, and enhance the growth during acclimatization for many plant species. In the current study, leafy nodal cuttings were cultured under Pa conditions and the growth and quality were compared with those cultured under Pm conditions. After 21d of culture, Pa conditions enhanced the growth and quality of St. John's wort plantlets in vitro, and these plantlets showed faster growth after transplantaing ex vitro compared with those cultured under Pm conditions.     

Photoautotrophic culture of Coffea arabusta somatic embryos: photosynthetic ability and growth of different stage embryos

Coffea arabusta somatic embryos were cultured and development of stomata, rate of CO2 fixation or production, chlorophyll content and chlorophyll fluorescence were studied in embryos at different stages of development. Cotyledonary and germinated embryos have photosynthetic capacity, although pretreatment at a high photosynthetic photon flux (PPF) (100 micromol m(-2) s(-1)) for 14 d increased photosynthetic ability. Except in a very small number of cases, stomata did not develop fully in precotyledonary stage embryos and were absent in torpedo stage embryos. Low chlorophyll content (90-130 microg g(-1) fresh mass) was noted in torpedo and precotyledonary stage embryos compared with cotyledonary and germinated embryos (300-500 microg g(-1) fresh mass). Due to the absence of stomata and low chlorophyll content in the torpedo and precotyledonary stage embryos, the photosynthetic rate was low and, in some cases, CO2 production was observed. These data suggest that the cotyledonary stage is the earliest stage that can be cultured photoautotrophically to ensure plantlet development. When grown photoautotrophically (in a sugar-free medium with CO2 enrichment in the culture headspace and high photosynthetic photon flux), torpedo and precotyledonary stage embryos lost 20-25% of their initial dry mass after 60 d of culture. However, in cotyledonary and germinated embryos, the dry mass of each embryo increased by 10 and 50%, respectively. By using a porous supporting material, growth (especially root growth) was increased in cotyledonary stage embryos. In addition, photoautotrophic conditions, high PPF (100-150 micromol m(-2) s(-1)) and increased CO2 concentration (1100 micromol mol(-1)) were found to be necessary for the development of plantlets from cotyledonary stage embryos.     

Recent advancement in research on photoautotrophic micropropagation using large culture vessels with forced ventilation

Summary Successful fundamental or basic research, while being stimulated by applied studies, provides the development of new technologies for the benefit of mankind. Photoautotrophic micropropagation or micropropagation using sugar-free medium is no exception from this generalization. The concept of photoautotrophic micropropagation is derived from research that revealed the relatively high photosynthetic abilities of chlorophyllous cultures such as leafy explants and plantlets in vitro. To meet the ever-increasing demand for quality transplants, the scaling-up of photoautotrophic micropropagation systems, for commercialization, has become necessary. This article reviews the recent advancement in the development and utilization of large culture vessels for photoautotrophic micropropagation with special emphasis on the feasibility of the system for the commercial-scale propagation. The review also includes choices for supporting material, ventilation type, planting density, vessel volume, and vessel sterilization procedure, and problems and solutions to achieve uniform growth in a large culture vessel. A case study of the commercial application of a photoautotrophic micropropagation system using large culture vessles, which recently has been established in Kunming, China, is also presented in this article.     

Diesel Exhaust Particle Exposure In Vitro Alters Monocyte Differentiation and Function

Air pollution by diesel exhaust particles is associated with elevated mortality and increased hospital admissions in individuals with respiratory diseases such as asthma and chronic obstructive pulmonary disease. During active inflammation monocytes are recruited to the airways and can replace resident alveolar macrophages. We therefore investigated whether chronic fourteen day exposure to low concentrations of diesel exhaust particles can alter the phenotype and function of monocytes from healthy individuals and those with chronic obstructive pulmonary disease. Monocytes were purified from the blood of healthy individuals and people with a diagnosis of chronic obstructive pulmonary disease. Monocyte-derived macrophages were generated in the presence or absence of diesel exhaust particles and their phenotypes studied through investigation of their lifespan, cytokine generation in response to Toll like receptor agonists and heat killed bacteria, and expression of surface markers. Chronic fourteen day exposure of monocyte-derived macrophages to concentrations of diesel exhaust particles >10 µg/ml caused mitochondrial and lysosomal dysfunction, and a gradual loss of cells over time both in healthy and chronic obstructive pulmonary disease individuals. Chronic exposure to lower concentrations of diesel exhaust particles impaired CXCL8 cytokine responses to lipopolysaccharide and heat killed E. coli, and this phenotype was associated with a reduction in CD14 and CD11b expression. Chronic diesel exhaust particle exposure may therefore alter both numbers and function of lung macrophages differentiating from locally recruited monocytes in the lungs of healthy people and patients with chronic obstructive pulmonary disease.     

Interaction pattern for the complex of B-DNA Fullerene compounds with a set of known replication proteins using docking study

Fullerenes have attracted considerable attention due to their unique chemical structure and potential applications which has opened wide venues for possible human exposure to various fullerene types. Therefore, in depth knowledge of how fullerene may interfere with various cellular processes becomes quite imperative. The present study was designed to investigate how the presence of fullerene affect the binding of DNA with different enzymes involved in replication process. Different fullerenes were first docked with DNA and then binding scores of different enzymes was analyzed with fullerene docked DNA. C30, C40 & C50 once docked with DNA, reduced the binding score of primase, whereas no significant change in the binding score was observed with the helicase, ssb protein, dna pol δ, dna pol ε, ligase, DNA clamp, and topoisomerases. On the contrast, the binding score of RPA14 decreases in fluctuating manner while interacting with increasing molecular weight of fullerene bound single-stranded DNA complex. The study revealed the affect of fullerene family interacting with DNA on the binding pattern of enzymes involved in replication process. Study suggests that the presence of most of fullerenes may not affect the activity of these enzymes necessary for replication process whereas C30, C40 & C50 may disrupt the activity of primase, (strating point for DNA polymerase) its docking score decreases from 13820 to 10702.     

RNA deadenylation and decay in plants

In eukaryotic cells, RNA levels are tightly regulated in a spatio-temporal manner to maintain the protein levels necessary for cell growth, differentiation and division. To cope with developmental and rapid environmental changes, RNAs that are no longer required by the cell undergo degradation via the mRNA decay process. A number of players involved in RNA degradation pathways have been identified for the last two decades. A wealth of information about the process of mRNA deadenylation and decay in yeast and other model organisms is currently available; however, very limited information is available in plants, including Arabidopsis. Nevertheless, the efforts of various plant research groups are continuously extending our understanding of this complicated process. Here, we summarize our current knowledge of RNA decay in yeast and compare this information with the progress from Arabidopsis. This review will especially focus on the structure and function of the deadenylation complex, 5′ to 3′ exoribonuclease (XRN)-mediated decay pathways and the exosome-mediated 3′ to 5′ decay pathway in plants.     

Evaluation of the Antitumor Activity of Dacomitinib in Models of Human Bladder Cancer

Members of the human epidermal growth factor receptor (HER) family play a significant role in bladder cancer progression and may underlie the development of chemotherapy resistance. Dacomitinib is an irreversible tyrosine kinase inhibitor with structural specificity for the catalytic domains of epidermal growth factor receptor (EGFR), HER2 and HER4 that has exhibited vigorous efficacy against other solid tumors. We evaluated the antitumor activity of dacomitinib in human bladder cancer cell lines expressing varying levels of HER family receptors. These cell lines also were established as bladder cancer xenografts in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice to assess dacomitinib activity in vivo. Significant cytotoxic and cytostatic effects were noted in cells expressing elevated levels of the dacomitinib target receptors with apoptosis and cell cycle arrest being the predominant mechanisms of antitumor activity. Cells expressing lower levels of HER receptors were much less sensitive to dacomitinib. Interestingly, dacomitinib was more active than either trastuzumab or cetuximab in vitro, and exhibited increased growth inhibition of bladder tumor xenografts compared with lapatinib. Pharmacodynamic effects of dacomitinib included decreased E-cadherin (E-cad) expression, reduction of EGFR and extracellular signal-regulated kinase (ERK) phosphorylation and reduced mitotic count. Dacomitinib also inhibited tumor growth in a chemotherapy-resistant xenograft and, when combined with chemotherapy in a sensitive xenograft, exhibited superior antitumor effects compared with individual treatments. Evaluation in xenograft-bearing mice revealed that this combination was broadly feasible and well tolerated. In conclusion, dacomitinib exhibited pronounced activity both as a single agent and when combined with chemotherapy in human bladder cancer models. Further investigation of dacomitinib in the preclinical and clinical trial settings is being pursued.