Development of a stable genetic transformation system in Erigeron breviscapus: a case study with EbYUC2 in relation to leaf number and flowering time.

MAIN CONCLUSION: A stable genetic transformation system for Erigeron breviscapus was developed. We cloned the EbYUC2 gene and genetically transformed it into Arabidopsis thaliana and E. breviscapus. The leaf number, YUC2 gene expression, and the endogenous auxin content in transgenic plants were significantly increased. Erigeron breviscapus is a prescription drug for the clinical treatment of cardiovascular and cerebrovascular diseases. The rosette leaves have the highest content of the major active compound scutellarin and are an important component in the yield of E. breviscapus. However, little is known about the genes related to the leaf number and flowering time of E. breviscapus. In our previous study, we identified three candidate genes related to the leaf number and flowering of E. breviscapus by combining resequencing data and genome-wide association study (GWAS). However, their specific functions remain to be characterized. In this study, we cloned and transformed the previously identified full-length EbYUC2 gene into Arabidopsis thaliana, developed the first stable genetic transformation system for E. breviscapus, and obtained the transgenic plants overexpressing EbYUC2. Compared with wild-type plants, the transgenic plants showed a significant increase in the number of leaves, which was correlated with the increased expression of EbYUC2. Consistently, the endogenous auxin content, particularly indole-3-acetic acid, in transgenic plants was also significantly increased. These results suggest that EbYUC2 may control the leaf number by regulating auxin biosynthesis, thereby laying a foundation for revealing the molecular mechanism governing the leaf number and flowering time of E. breviscapus.

Genome-wide identification and expression analysis of the C2H2-zinc finger transcription factor gene family and screening of candidate genes involved in floral development in Coptis teeta Wall. (Ranunculaceae).

Background: C2H2-zinc finger transcription factors comprise one of the largest and most diverse gene superfamilies and are involved in the transcriptional regulation of flowering. Although a large number of C2H2 zinc-finger proteins (C2H2-ZFPs) have been well characterized in a number of model plant species, little is known about their expression and function in Coptis teeta. C. teeta displays two floral phenotypes (herkogamy phenotypes). It has been proposed that the C2H2-zinc finger transcription factor family may play a crucial role in the formation of floral development and herkogamy observed in C. teeta. As such, we performed a genome-wide analysis of the C2H2-ZFP gene family in C. teeta. Results: The complexity and diversity of C. teeta C2H2 zinc finger proteins were established by evaluation of their physicochemical properties, phylogenetic relationships, exon-intron structure, and conserved motifs. Chromosome localization showed that 95 members of the C2H2 zinc-finger genes were unevenly distributed across the nine chromosomes of C. teeta, and that these genes were replicated in tandem and segmentally and had undergone purifying selection. Analysis of cis-acting regulatory elements revealed a possible involvement of C2H2 zinc-finger proteins in the regulation of phytohormones. Transcriptome data was then used to compare the expression levels of these genes during the growth and development of the two floral phenotypes (F-type and M-type). These data demonstrate that in groups A and B, the expression levels of 23 genes were higher in F-type flowers, while 15 genes showed higher expressions in M-type flowers. qRT-PCR analysis further revealed that the relative expression was highly consistent with the transcriptome data. Conclusion: These data provide a solid basis for further in-depth studies of the C2H2 zinc finger transcription factor gene family in this species and provide preliminary information on which to base further research into the role of the C2H2 ZFPs gene family in floral development in C. teeta.

Biosynthetic pathway of prescription bergenin from Bergenia purpurascens and Ardisia japonica.

Bergenin is a typical carbon glycoside and the primary active ingredient in antitussive drugs widely prescribed for central cough inhibition in China. The bergenin extraction industry relies on the medicinal plant species Bergenia purpurascens and Ardisia japonica as their resources. However, the bergenin biosynthetic pathway in plants remains elusive. In this study, we functionally characterized a shikimate dehydrogenase (SDH), two O-methyltransferases (OMTs), and a C-glycosyltransferase (CGT) involved in bergenin synthesis through bioinformatics analysis, heterologous expression, and enzymatic characterization. We found that BpSDH2 catalyzes the two-step dehydrogenation process of shikimic acid to form gallic acid (GA). BpOMT1 and AjOMT1 facilitate the methylation reaction at the 4-OH position of GA, resulting in the formation of 4-O-methyl gallic acid (4-O-Me-GA). AjCGT1 transfers a glucose moiety to C-2 to generate 2-Glucosyl-4-O-methyl gallic acid (2-Glucosyl-4-O-Me-GA). Bergenin production ultimately occurs in acidic conditions or via dehydration catalyzed by plant dehydratases following a ring-closure reaction. This study for the first time uncovered the biosynthetic pathway of bergenin, paving the way to rational production of bergenin in cell factories via synthetic biology strategies.

PanaxGDB: A Comprehensive Platform for Panax.

The genus Panax is a valuable natural medicinal source used worldwide that contains high levels of triterpenoid saponins with extensive pharmacological activities. In past decades, molecular biotechnology and breeding techniques have been respectively used to generate omics data and information on cultivars primarily from Panax ginseng (ginseng), Panax quinquefolium (American ginseng), and Panax notoginseng (Sanqi) to biosynthesize valuable saponins, improve product quality, and conduct cost-controlled cultivation. Although much data have been produced, there are concerns that redundant data might be generated and that relatively scattered data might be overlooked. Therefore, many scientists desire a reliable, comprehensive omics database of the Panax genus that could save time and promote integrated analysis. Therefore, to provide all-inclusive, reliable, and valuable information on the Panax genus, PanaxGDB, an open comprehensive database that integrates data on omics and information on varieties, was established. The database contains information on nearly 600 compounds from 12 Panax species, draft genomic sequences with annotations and gene expression levels, single nucleotide polymorphisms, genome-wide association analysis based on agronomic traits, globally collected germplasm information, summaries, omics data of the Panax genus, and online versatile analytic tools. The Panax genus database will be updated when new data are released to continue serving as a central portal to boost research on the biology and functions of Panax. PanaxGDB is available at: http://panaxGDB.ynau.edu.cn.

[Identification and expression profiling of R2R3-MYB transcription factors in Erigeron breviscapus].

R2 R3-MYB transcription factors are ubiquitous in plants, playing a role in the regulation of plant growth, development, and secondary metabolism. In this paper, the R2 R3-MYB transcription factors were identified by bioinformatics analysis of the genomic data of Erigeron breviscapus, and their gene sequences, structures, physical and chemical properties were analyzed. The functions of R2 R3-MYB transcription factors were predicted by cluster analysis. Meanwhile, the expression patterns of R2 R3-MYB transcription factors in response to hormone treatments were analyzed. A total of 108 R2 R3-MYB transcription factors, named EbMYB1-EbMYB108, were identified from the genome of E. breviscapus. Most of the R2 R3-MYB genes carried 2-4 exons. The phylogenetic tree of MYBs in E. breviscapus and Arabidopsis thaliala was constructed, which classified 234 MYBs into 30 subfamilies. The MYBs in the five MYB subfamilies of A.thaliala were clustered into independent clades, and those in E. breviscapus were clustered into four clades. The transcriptome data showed that MYB genes were differentially expressed in different tissues of E. breviscapus and in response to the treatments with exogenous hormones such as ABA, SA, and GA for different time. The transcription of 13 R2 R3-MYB genes did not change significantly, and the expression patterns of some genes were up-regulated or down-regulated with the extension of hormone treatment time. This study provides a theoretical basis for revealing the mechanisms of R2 R3-MYB transcription factors in regulating the growth and development, stress(hormone) response, and active ingredient accumulation in E. breviscapus.

Identification of two UDP-glycosyltransferases involved in the main oleanane-type ginsenosides in Panax japonicus var. major.

MAIN CONCLUSION: Two UDP-glycosyltransferases from Panax japonicus var. major were identified, and the biosynthetic pathways of three oleanane-type ginsenosides (chikusetsusaponin IVa, ginsenoside Ro, zingibroside R1) were elucidated. Chikusetsusaponin IVa and ginsenoside Ro are primary active components formed by stepwise glycosylation of oleanolic acid in five medicinal plants of the genus Panax. However, the key UDP-glycosyltransferases (UGTs) in the biosynthetic pathway of chikusetsusaponin IVa and ginsenoside Ro are still unclear. In this study, two UGTs (PjmUGT1 and PjmUGT2) from Panax japonicus var. major involved in the biosynthesis of chikusetsusaponin IVa and ginsenoside Ro were identified based on bioinformatics analysis, heterologous expression and enzyme assays. The results show that PjmUGT1 can transfer a glucose moiety to the C-28 carboxyl groups of oleanolic acid 3-O-ß-D-glucuronide and zingibroside R1 to form chikusetsusaponin IVa and ginsenoside Ro, respectively. Meanwhile, PjmUGT2 can transfer a glucose moiety to oleanolic acid 3-O-ß-D-glucuronide and chikusetsusaponin IVa to form zingibroside R1 and ginsenoside Ro. This work uncovered the biosynthetic mechanism of chikusetsusaponin IVa and ginsenoside Ro, providing the rational production of valuable saponins through synthetic biology strategy.

[Phosphorus Storage Capacity and Loss Risk in Coastal Reed Wetland Surrounding Bohai Sea].

Coastal wetland, at the intersection of land and sea, is considered as a "sink", "source", and "transformer" of phosphorus (P). Coastal wetland plays an important role in the global P cycle, and its ability to retain excessive P in water receives increasing attention. In this study, the coastal reed wetland sediments surrounding the Bohai Sea were sampled to investigate P adsorption capacity and loss risk by conducting batch experiments. Results show that the maximum P adsorption capacity (Qmax) was 693.7-2117.2 mg·kg-1, with an average of 1468.6 mg·kg-1. The Qmax decreased in the order of Qilihai Wetland > Beidagang Wetland > Nandagang Wetland > Liaohe Delta Wetland > Shouguang Coastal Wetland > Yellow River Delta Wetland. The P adsorption capacity was related to the contents of Ca, Mg, and TOC. The degree of P adsorption saturation (DPS) and loss risk index (ERI) of the coastal wetland were 0.28%-4.50% and 0.53%-10.10%, respectively. The ERI suggested that the P loss risk was relatively low for coastal reed wetland surrounding the Bohai Sea except for the moderate loss risk for Shouguang coastal wetland. In summary, the reed coastal wetland around Bohai Sea demonstrated significantly P storage capacity and served as a P sink for water P. We recommend to fully utilize the coastal wetland to reduce point or non-point source pollution (e.g., P) during the remediation or recovery of the polluted Bohai Sea.

Comparative transcriptome and metabolome analyses provide new insights into the molecular mechanisms underlying taproot thickening in Panax notoginseng.

BACKGROUND: Taproot thickening is a complex biological process that is dependent on the coordinated expression of genes controlled by both environmental and developmental factors. Panax notoginseng is an important Chinese medicinal herb that is characterized by an enlarged taproot as the main organ of saponin accumulation. However, the molecular mechanisms of taproot enlargement are poorly understood. RESULTS: A total of 29,957 differentially expressed genes (DEGs) were identified during the thickening process in the taproots of P. notoginseng. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment revealed that DEGs associated with "plant hormone signal transduction," "starch and sucrose metabolism," and "phenylpropanoid biosynthesis" were predominantly enriched. Further analysis identified some critical genes (e.g., RNase-like major storage protein, DA1-related protein, and Starch branching enzyme I) and metabolites (e.g., sucrose, glucose, fructose, malate, and arginine) that potentially control taproot thickening. Several aspects including hormone crosstalk, transcriptional regulation, homeostatic regulation between sugar and starch, and cell wall metabolism, were identified as important for the thickening process in the taproot of P. notoginseng. CONCLUSION: The results provide a molecular regulatory network of taproot thickening in P. notoginseng and facilitate the further characterization of the genes responsible for taproot formation in root medicinal plants or crops.

[Spatial-temporal distributions of dissolved inorganic carbon and its affecting factors in the Yellow River estuary].

Estuary is an important area contributing to the global carbon cycle. In order to analyze the spatial-temporal distribution characteristics of the dissolved inorganic carbon (DIC) in the surface water of Yellow River estuary. Samples were collected in spring, summer, fall, winter of 2013, and discussed the correlation between the content of DIC and environmental factors. The results show that, the DIC concentration of the surface water in Yellow River estuary is in a range of 26.34-39.43 mg x L(-1), and the DIC concentration in freshwater side is higher than that in the sea side. In some areas where the salinity is less than 15 per thousand, the DIC concentration appears significant losses-the maximum loss is 20.46%. Seasonal distribution of performance in descending order is spring, fall, winter, summer. Through principal component analysis, it shows that water temperature, suspended solids, salinity and chlorophyll a are the main factors affecting the variation of the DIC concentration in surface water, their contribution rate is as high as 83% , and alkalinity, pH, dissolved organic carbon, dissolved oxygen and other factors can not be ignored. The loss of DIC in the low area is due to the calcium carbonate sedimentation. DIC presents a gradually increasing trend, which is mainly due to the effects of water retention time, temperature, outside input and environmental conditions.

Reevaluating reference ranges of oxygen saturation for healthy full-term neonates using pulse oximetry.

BACKGROUND: We compared our clinical experience with currently available reference oxygen saturation level (SpO(2)) values from the American Academy of Pediatrics/American Heart Association (AAP/AHA) neonatal resuscitation program guidelines. METHODS: We enrolled 145 healthy full-term neonates; infants showing respiratory distress and those with serious congenital anomalies were excluded. SpO(2) values at every 1 minute until 10 minutes after birth were measured and recorded. Infants were classified into the cesarean section (CS) and normal spontaneous delivery (NSD) groups for evaluating differences. The 10(th) percentiles of SpO(2) at each minute were used as the lower limits of normal oxygen saturation, and these were compared with the lowest target values recommended in the AAP/AHA guidelines. RESULTS: Overall, 130 vigorous full-term neonates (median gestational age: 38 5/7 weeks; body weight at birth: 2405-3960 g) were analyzed. The median SpO(2) were 67% and 89% at the 1(st) and 4(th) minute, respectively. On average, SpO(2) values reached >90% at the 5(th) minute. No statistical differences were noted in the SpO(2) values between the CS and NSD groups after 5 minutes; however, a trend of higher SpO(2) was observed in the NSD group. We noted a gradually increasing trend for SpO(2) values over time, similar to that noted in the AAP/AHA guidelines. However, SpO(2) values at the 10(th) percentiles of each minute within the first 5 minutes in our study were equal to or significantly lower than those in the AAP/AHA guidelines; moreover, at the 10(th) minute, SpO(2) values at the 10(th) percentiles were significantly higher than those in the guidelines. CONCLUSION: The delivery modes did not affect the SpO(2) values of full-term healthy neonates. Discrepancies in SpO(2) changes in full-term neonates not requiring resuscitation between this study and the AAP/AHA guidelines were significant. SpO(2) ranges for each time point within the first 10 minutes after birth should therefore be reevaluated locally.

[Using in-situ reflectance to monitor the chlorophyll concentration in the surface layer of tidal flat].

An optical monitoring method is proposed for the rapid, non destructive measurements of chlorophyll concentration (Chl-a) in the surface sediments of emerged tidal flat, and it can be further applied in remote sensing work. Hyperspectral reflectance of intertidal sediments were measured in day time at the tidal flats of the Sishili Bay, the Northern Yellow Sea, and surface sediments (3 mm) were sampled for the in-door measurements of Chl-a. On the basis of the reflectance at 650, 675 and 700 nm, the indices of normalized difference index of microbenthos (NDI-MPB) and trough depth (T-depth) were proposed for the measurements of microphytobenthos biomass. T-depth can be used to remove the linear background spectral noises and indicate the existence of microphytobenthos; Good linear relationship was observed between NDI-MPB and Chl-a content in sediments (2.22-49.36 mg x m(-2), r > 0.99), which may be used to monitor the biomass of microphy to benthos.

Effective radiotherapy cured cauda equina syndrome caused by remitted intracranial germinoma depositing.

Cauda equina syndrome (CES) in children is very rare and can permanently disable. A remitted intracranial germinoma depositing on the spinal cord, leading to CES, has never been reported. We discuss the case of a 10-year-old girl who presented with sudden ataxia, low back pain, sensory deficits of the left lower extremity, and difficulty urinating and defecating 7 months after totally remitted intracranial germinoma postintracranial surgery and cranial irradiation. Magnetic resonance imaging (MRI) of the brain and spine showed multiple intradural extramedullary homogeneous masses from the cervical to lumbar levels, compressing the conus medullaris and cauda equina. After emergent craniospinal irradiation, the patient's neurologic symptoms dramatically subsided. A remitted intracranial germinoma depositing on her spinal cord could be the cause of CES. Early identification and a proper craniospinal irradiation may halt the progression of symptoms.

Scarlet fever caused by community-associated methicillin-resistant Staphylococcus aureus.

We describe a previously healthy 2.5-year-old boy with staphylococcal scarlet fever associated with acute suppurative otitis media due to community-associated methicillin-resistant Staphylococcus aureus. The patient was successfully treated by spontaneous drainage in combination with trimethoprim-sulfamethoxazole therapy.

Concomitant use of acyclovir and intravenous immunoglobulin rescues an immunocompromised child with disseminated varicella caused multiple organ failure.

Varicella is a common and mild disease in healthy children. However, when patients are in immunocompromised conditions, such as receiving chemotherapy for cancer treatment, they are highly vulnerable and it can even prove lethal. Herein, we report a 14-year-old boy with acute lymphoblastic leukemia who was receiving chemotherapy for induction with vincristine, idarubicin, L-asparaginase, and prednisolone, presented with typical varicella skin lesions and varicella-zoster virus was detected in his serum by real-time polymerase chain reaction (PCR). His condition was advanced to multiple organs failure, including fulminant hepatitis, disseminated intravascular coagulation, and myocarditis despite acyclovir administration. After a combined therapy with intravenous acyclovir and high-dose intravenous immunoglobulin, his condition was dramatically improved. We suggest that IVIG may be used immediately with acyclovir when immunocompromised patients with varicella advanced to dissemination are identified.

[Temporal and spatial variations of greenhouse gases concentrations in soils in Karst Stone Desertification Areas in central part of Guizhou Province].

Concentrations of CO2, N2O and CH4 of soil profile in Karst Stone Desertification Areas were measured monthly from June of 2006 to May of 2007. The results indicated that the concentrations of CO2, N2O and CH4 varied from 530.2 to 31512.6, 0.27 to 0.67 and 0.1 to 3.5 microL x L(-1). On the whole, with the increase of soil depth, the concentrations of CO2 and N2O increased, while CH4 decreased. However, in the cold and wet October, November and January, the concentrations of CO2 and N2O decreased with the depth below 15 cm. In contrast, CHR4 had the inverse trend. Soil temperature and moisture were the main factors which had impacts on the temporal and spatial variations of C2O, N2O and CH4 concentrations in soil profile, but the influence impacts were different. The correlation analysis showed that there was positive correlation between CO2 and N2O (r 0.780-0.894, p < 0.05-0.01), while correlation degree was controlled by environmental factors in different months. CH4 concentrations in soil had significantly negative correlation with CO2 concentrations (r = 330, p < 0.01), but correlated with N2O concentrations just in moisture months (r - 0.829- - 0.956, p < 0.05-0.01).

Knockdown endogenous CypA with siRNA in U2OS cells results in disruption of F-actin structure and alters tumor phenotype.

Cyclophilin A (CypA) was originally identified as a cytosolic protein possessing peptidyl-prolyl isomerase activity. CypA has been shown to play a pivotal role in the immune response, but little is known about other molecular mechanisms of CypA-mediated biologic events. In our present study, we demonstrate that knockdown CypA expression using RNAi in U2OS cells resulted in disruption of the F-actin structure, as well as decreased anchorage-independent growth, proliferation, and migration. Wild-type U2OS cells treated with cyclosporine A (CsA), a peptidyl-prolyl isomerase inhibitor, displayed the same phenotype as knockdown CypA cells, suggesting that the isomerase activity of CypA is required to maintain a normal phenotype. In vitro and in vivo binding assays revealed that CypA binds to N-WASP, which functions in the nucleation of actin via the Arp2/3 complex. Pulse-chase labeling study indicated an enhanced degradation of N-WASP in cell lacking CypA, suggesting that CypA is required for stabilizing N-WASP to form a N-WASP/Arp2/3 complex for the nucleation/initiation of F-actin polymerization.

[Soil N2O flux and its affecting factors under different vegetations in central Guizhou Province].

By using close chamber-GC method, the N2O fluxes in de-farming grassland, bush land, Pinus massoniana forestland, and broadleaved forestland in central Guizhou were measured in situ in 2006 and 2007 to investigate the seasonal change patterns of soil N2 O flux under different vegetations in karst region of southwest China. The results indicated that in a whole year round, the soils in all test sites played the source of atmospheric N2O, only acting as a N2O sink in exceptional months. The soil type and the vegetation had obvious effets on the N2O flux from soil. Yellow soil had a smaller N2O flux than calcareous soil, except for broadleaved forestland. The N2O fluxes from de-farming grassland and bush land were higher in spring and lower in autumn and winter, and varied within the range of -20.7 - 103.09 microg N x m(-2) x h(-1) and -33.0-67.3 microg N x m(-2) x h(-1), respectively; while those from P. massoniana forestland and broadleaved forestland were the highest in spring but had no definite change patterns in other seasons, and varied within the range of -5.3 - 35.0 microg N x m(-2) x h(-1) and -14.4 - 152.8 microg N x m(-2) x h(-1), respectively. The correlation analysis showed that there existed a negative correlation between soil moisture content and N2O flux, suggesting that soil moisture was the main factor driving the seasonal change of N2O flux. Temperature indirectly affected the soil N2O flux through affecting soil moisture.

[Seasonal variability of p(CO2) in the two Karst reservoirs, Hongfeng and Baihua Lakes in Guizhou Province, China].

The partial pressure of carbon dioxide p(CO2) in the surface water of the two karst eutrophic reservoirs, Hongfeng and Baihua Lakes near Guiyang city, Ghuizhou Province, China has been studied for one year. The factors regulating the seasonal variability of p(CO2) in the two reservoirs have been analyzed. Unlike the reservoirs in boreal temperate regions, the p (CO2) in the two reservoirs has significant seasonal changes: CO2 was unsaturated during summer, but supersaturated at other seasons. According to the correlation analysis, there is a negative relationship between p (CO2) and Chla in the two reservoirs, due to the production of the phytoplankton and the respiration of the organic matter by the bacteria, which are also the main factors regulating the p(CO2). The negative relationship between temperature and p(CO2) is considered to be due to the effect of temperature on the growth of the phytoplankton. Precipitation leads to the input of the nutriments into the reservoirs, and hence precipitation is negatively related to p(CO2). The relationships between NO3-, NO2- and p(CO2) are ascribed to the absorption of phytoplankton, and the degradation of the organic matter nitrification. The relationship between SiO3(2-) and p(CO2) is due to the absorption of phytoplankton and the precipitation. The differences of the relationship between p(CO2) and DOC in the studied two lakes possibly lie in the variations of their sources.

Cyclophilin a protects Peg3 from hypermethylation and inactive histone modification.

Imprinted genes are expressed from only one of the parental alleles and are marked epigenetically by DNA methylation and histone modifications. Disruption of normal imprinting leads to abnormal embryogenesis, certain inherited diseases, and is associated with various cancers. In the context of screening for the gene(s) responsible for the alteration of phenotype in cyclophilin A knockdown (CypA-KD) P19 cells, we observed a silent paternally expressed gene, Peg3. Treatment of CypA-KD P19 cells with the DNA demethylating agent 5-aza-dC reversed the silencing of Peg3 biallelically. Genomic bisulfite sequencing and methylation-specific PCR revealed DNA hypermethylation in CypA-KD P19 cells, as the normally unmethylated paternal allele acquired methylation that resulted in biallelic methylation of Peg3. Chromatin immunoprecipitation assays indicated a loss of acetylation and a gain of lysine 9 trimethylation in histone 3, as well as enhanced DNA methyltransferase 1 and MBD2 binding on the cytosine-guanine dinucleotide (CpG) islands of Peg3. Our results indicate that DNA hypermethylation on the paternal allele and allele-specific acquisition of histone methylation leads to silencing of Peg3 in CypA-KD P19 cells. This study is the first demonstration of the epigenetic function of CypA in protecting the paternal allele of Peg3 from DNA methylation and inactive histone modifications.

Cyclophilin A is required for retinoic acid-induced neuronal differentiation in p19 cells.

Stable transfectants with expression of small interfering RNA for targeting cyclophilin A (CypA) in p19 cells lose their potential for retinoic acid (RA)-induced neuronal differentiation but not Me(2)SO-induced mesodermal differentiation. This difference suggests that CypA is specifically required for the RA-induced neuronal pathway. In addition to the loss of RA-induced RA receptor beta expression and retinoic acid response element (RARE)-binding activity, a dramatic reduction in RA-induced RARE-mediated luciferase activity in the CypA knockdown cell line suggests that CypA affects RARE-mediated regulation of gene expression. Silent mutation of target sequences confirms the specificity of RNA interference in p19 embryonal carcinoma cells. Collectively, our data reveal that a novel function of CypA is required in the processing of RA-induced neuronal differentiation in p19 embryonal carcinoma cells.