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81.
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Su Jung Park Kyung Jin Kwak Hyun Ju Jung Hwa Jung Lee Hunseung Kang 《Phytochemistry》2010,71(5-6):543-547
Among the four cold shock domain proteins (CSDPs) identified in Arabidopsis thaliana, it has recently been shown that CSDP1 harboring seven CCHC-type zinc fingers, but not CSDP2 harboring two CCHC-type zinc fingers, function as a RNA chaperone during cold adaptation. However, the structural features relevant to this differing RNA chaperone activity between CSDP1 and CSDP2 remain largely unknown. To determine which structural features are necessary for the RNA chaperone activity of the CSDPs, the importance of the N-terminal cold shock domain (CSD) and the C-terminal zinc finger glycine-rich domains of CSDP1 and CSDP2 were assessed. The results of sequence motif-swapping and deletion experiments showed that, although the CSD itself harbored RNA chaperone activity, the number and length of the zinc finger glycine-rich domains of CSDPs were crucial to the full activity of the RNA chaperones. The C-terminal domain itself of CSDP1, harboring seven CCHC-type zinc fingers, also has RNA chaperone activity. The RNA chaperone activity and nuclei acid-binding property of the native and chimeric proteins were closely correlated with each other. Collectively, these results indicate that a specific modular arrangement of the CSD and the zinc finger domain determines both the RNA chaperone activity and nucleic acid-binding property of CSDPs; this, in turn, contributes to enhanced cold tolerance in plants as well as in bacteria. 相似文献
83.
Stable isotopes can be used to elucidate ecological relationships in community and trophic studies. Findings are calibrated
against baselines, e.g. from a producer or primary consumer, assumed to act as a reference to the isotopic context created
by spatio-temporal attributes such as geography, climate, nutrient, and energy sources. The ability of an organism to accurately
represent a community base depends on how, and over what time-scale, it assimilates ambient materials. Freshwater mussels
have served as references for trophic studies of freshwater communities and as indicators of change in nutrient pollution
load or source. Their suitability as reference animals has not yet been fully explored, however. We conducted a series of
studies examining the suitability of freshwater mussels as isotopic baselines, using their ability to reflect variation in
ambient nutrient loads as a case scenario. (1) We analyzed bivalve foot tissue δ15N and δ13C from 22 stream reaches in the Piedmont region of North Carolina, USA to show that compositions varied substantially among
locations. Site mean bivalve δ13C values correlated with site ambient particulate organic matter (POM) δ13C values, and site mean bivalve δ15N values correlated with site ambient water dissolved δ15N-NO3 values. (2) Similarity of results among sample types demonstrated that the minimally invasive hemolymph sample is a suitable
substitute for foot tissue in δ15N analyses, and that small sample sizes generate means representative of a larger population. Both findings can help minimize
the impact of sampling on imperiled freshwater mussel populations. (3) In a bivalve transplantation study we showed that hemolymph
δ15N compositions responded to a shift in ambient dissolved δ15N-NO3, although slowly. The tissue turnover time for bivalve hemolymph was 113 days. We conclude that bivalves serve best as biomonitors
of chronic, rather than acute, fluctuations in stream nutrient loads, and provide initial evidence of their suitability as
time-integrated isotopic baselines for community studies. 相似文献
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85.
Yu HN Song EK Yoo SM Lee YR Han MK Yim CY Kwak JY Kim JS 《Biochemical and biophysical research communications》2007,354(3):764-768
The ADP-ribose (ADPR) pyrophosphatase (ADPRase) NUDT5, a member of a superfamily of Nudix hydrolases, hydrolyzes ADP-ribose (ADPR) to AMP and ribose 5'-phosphate. Nitric oxide (NO) enhances nonenzymatic ADP-ribosylation of proteins such as beta-actin and glyceraldehydes 3-phosphate dehydrogenase in the presence of free ADPR, suggesting a possibility that NUDT5 could also be ADP-ribosylated by its substrate, ADPR. Here, we show that NO stimulates nonenzymatic ADP-ribosylation of NUDT5 using ADP-ribose and consequently activates its ADPRase activity. We found that ADPRase activity in J774 macrophage cells is increased by the treatment with SNP, an exogenous NO generator or TNF-alpha/IFN-gamma, endogenous NO inducers. Anti-NUDT5 antibody pulled down most of the ADPRase activity increased by NO, indicating that the ADPRase regulated by NO is NUDT5. Using recombinant human NUDT5, we also demonstrated that the increase of ADPRase activity is mediated via ADP-ribosylation at cysteine residue(s) in the presence of reductant. This result suggests that NO activates NUDT5 through ADP-ribosylation at cysteine residues of the enzyme in macrophages. 相似文献
86.
DNA-methyltransferase-3B (DNMT3b) plays an important role in the generation of aberrant methylation in carcinogenesis. DNMT3b SNP has been associated with susceptibility to lung, head, neck, and breast cancer, but its association with the development
of colon cancer has not been reported. We investigated the relationship between the 39179GT polymorphism in the DNMT3b gene, which is involved in de novo methylation and is associated with the risk of adenocarcinoma of the colon in Koreans.
The DNMT3b 39179GT genotypes were determined by a PCR-RFLP method in 248 adenocarcinomas of colon cancer patients and in 248 healthy
controls matched as to age and sex. When stratified by sex and age, a significantly reduced risk of the combined GT and GG
genotypes was observed in younger patients (<59, adjusted OR = 0.255, 95% CI = 0.133–0.489) and in male patients (adjusted
OR = 0.383, 95% CI = 0.225–0.652). The DNMT3b 39179GT polymorphism may be a genetic determinant of adenocarcinoma of the colon, especially in younger Korean men. 相似文献
87.
Lee Y Kim YW Jeon BW Park KY Suh SJ Seo J Kwak JM Martinoia E Hwang I Lee Y 《The Plant journal : for cell and molecular biology》2007,52(5):803-816
Previously, we demonstrated that a protein that binds phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] inhibits both light-induced stomatal opening and ABA-induced stomatal closing. The latter effect is due to a reduction in free PtdIns(4,5)P(2), decreasing production of inositol 1,4,5-trisphosphate and phosphatidic acid by phospholipases C and D. However, it is less clear how PtdIns(4,5)P(2) modulates stomatal opening. We found that in response to white light irradiation, the PtdIns(4,5)P(2)-binding domain GFP:PLCdelta1PH translocated from the cytosol into the plasma membrane. This suggests that the level of PtdIns(4,5)P(2) increases at the plasma membrane upon illumination. Exogenously administered PtdIns(4,5)P(2) substituted for light stimuli, inducing stomatal opening and swelling of guard cell protoplasts. To identify PtdIns(4,5)P(2) targets we performed patch-clamp experiments, and found that anion channel activity was inhibited by PtdIns(4,5)P(2). Genetic analyses using an Arabidopsis PIP5K4 mutant further supported the role of PtdIns(4,5)P(2) in stomatal opening. The reduced stomatal opening movements exhibited by a mutant of Arabidopsis PIP5K4 (At3g56960) was countered by exogenous application of PtdIns(4,5)P(2). The phenotype of reduced stomatal opening in the pip5k4 mutant was recovered in lines complemented with the full-length PIP5K4. Together, these data suggest that PIP5K4 produces PtdIns(4,5)P(2) in irradiated guard cells, inhibiting anion channels to allow full stomatal opening. 相似文献
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90.
Jin Il Kwak 《人类与生态风险评估》2015,21(6):1566-1575
The concern regarding the ecotoxicological effects of nanomaterials in the terrestrial environment is increasing. Against this background, several studies have investigated the effects of different nanomaterials on various earthworm species. Since the earthworm is a representative invertebrate present in soil and occupies an important trophic level, many studies have focused on earthworms. Understanding how and why nanoparticles are toxic to organisms is important to nanotoxicologists and ecotoxicologists. We have collated information from studies on the toxicity of metal- and carbon-based nanomaterials to earthworms in the soil matrix, and trends in the adverse effects of nanomaterials on earthworms were analyzed. Most studies showed that the survival and growth of adult earthworms are negligibly affected by nanomaterials in the soil. However, many studies reported that nanomaterials may result in a reduction in the reproductive activity. This study presents an intensive overall view of the ecotoxicological impact of nanomaterials on earthworms at the organism, cellular, and molecular levels. 相似文献