Biomedical subjects

Y Shen

Publications and source records attributed to Y Shen.

At least 217 records · Page 12Linked to original sources

PubMed2000

[The regulation of vitamin D3 and 9-cis-retinoic acid and their receptors on human hsp90 beta gene].

OBJECTIVE: To study the effects of vitamin D3(VD3), 9-cis-retinoic acid (9-cis-RA) and their receptors on the regulation of human hsp90 beta gene. METHODS: We first transfected Jurkat cells with "full length" (-1,039 bp/+1,531 bp) hsp90 beta reporter plasmid beta 1.11, then the transfected cells were treated with VD3 or/and 9-cis-RA; or beta 1.11 was cotransfected with wild type vitamin D3 receptor (VDR) or/and retinoid X receptor (RXR) expression construction and the reporter activities were assayed. Western blot was carried out to detect the protein level of hsp90 beta in the Jurkat cells that were transfected by VDR cDNA or treated with VD3 or/and 9-cis-RA. By electrophoresis mobility shift assay (EMSA), we evaluated the DNA binding activity of VDR and RXR in Jurkat cell nuclear extracts. RESULTS: With VD3 or/and 9-cis-RA treatment, the expression of hsp90 beta gene was slightly increased. The induction became prominent when both of the ligands were present. The unliganded VDR or RXR alpha all slightly repressed the constitutive expression of hsp90 beta gene, while overexpression of VDR and RXR alpha further inhibited the gene. In addition, EMSA results showed that unliganded VDR and RXR simultaneously bound to the vitamin D3 response element (VDRE) of hsp90 beta gene. CONCLUSIONS: These results suggest that VD3/VDR and 9-cis-RA/RXR co-participate in the regulation of hsp90 beta gene in Jurkat cells.

Cholecalciferol↗

PubMed2000

[The role of MAPK pathways in hsp90 genes expression].

OBJECTIVE: To study the effect of mitogen-activated protein kinase (MAPK) pathways on hsp90 genes expression in Jurkat cells. METHODS: Firstly, the phosphorylation of extracellular signal-regulated protein kinase (ERK), p38 kinase and c-Jun in Jurkat cells were detected by using Western blotting-enhanced chemically lightening (ECL) system. Secondly, Jurkat cells were transfected transiently with c-Jun N-terminal kinase (JNK) dominant negative plasmid, DN-JNK1, p38 cDNA antisense plasmid, anti-p38, respectively or incubated in the present of PD98059, specific inhibitor of ERK kinase. Then the constitutive and heat-induced mRNA levels of hsp90 alpha and hsp90 beta in these cells were determined quantitatively by competitive RT-PCR. The relative mRNA level of hsp90 was compared with those in the cells transfected with mock vector (pCDNA3) or untreated cells respectively. RESULTS: In the Jurkat cells treated at 45 degrees C for 15 min, the phosphorylation of c-Jun and p38 kinase enhanced obviously, whereas the phosphorylation of ERK increased at certain degree as compared with control. Both constitutive and heat-induced expression of hsp90 genes decreased in the Jurkat cells transfected with DN-JNK1, especially for the heat-induced expression of hsp90 alpha gene which reduced to 68% of that of control. After transfected with anti-p38, the constitutive expression of hsp90 alpha gene and the heat-induced expression of hsp90 beta gene increased by 26% and 22% over the control. The constitutive expression of hsp90 alpha and hsp90 beta genes in the Jurkat cells treated with PD98059, increased to 46% and 16% of the control respectively, whereas the heat-induced expression of hsp90 genes did not change. CONCLUSIONS: Evidences showed that ERK signal pathway inhibited the constitutive expression of hsp90 genes in Jurkat cell. JNK pathway promoted both constitutive and heat-induced expression of hsp90 genes, whereas p38 pathway may not play an important role in the hsp90 genes expression.

Gene Expression↗

PubMed2000

[Studies on the stable integration and expression of IL-2R alpha gene in CHO cells and it's applications].

OBJECTIVES: To establish a novel bioassay method for quantitative analysis of human IL-2 based on the specific binding of Interleukin-2 receptor alpha subunit (IL-2R alpha) with IL-2. METHODS: Southern blot hybridization was first used to detect the stability of integration of recombinant secretive IL-2R alpha (rsIL-2R alpha) gene into the genome of highly expressed cell line reported elsewhere; the apparent Mr of the rsIL-2R alpha was then determined by using Western blotting; finally, a receptor-antibody sandwich ELISA method has been established for quantitative analysis of IL-2. RESULTS: (1) Stable integration of rsIL-2R alpha gene into the genome of #17 CHO cell line has been identified; (2) the apparent Mr of rsIL-2R alpha was approximately 40,000; (3) linear range of the standard curve obtained from the receptor-based ELISA fell between 31.25-500 U of IL-2 (r = 0.9995). The slop of the standard curve decreased significantly when IL-2 was pre-incubated with goat anti-IL-2 antibody IgG (P < 0.01). CONCLUSIONS: An IL-2R alpha-based IL-2 ELISA has been established for laboratory and clinical use with advantages of accuracy, specificity and simplicity over other conventional bioassays for IL-2 detection.

Animals↗

PubMed2000

[Study on the formation mechanism of soluble complexes containing bovine serum albumin and calcium hydroxyapatite and calcium carbonate].

Fourier transform infrared spectroscopy was used to study the composition and microstructure of soluble complexes produced by different initial mole ratios of bovine serum albumin(BSA) and calcium hydroxyapatite [Ca10(OH)2(PO4)6] and calcium carbonate (CaCO3) in aqueous solution. The band shifts and intensity variations suggested that calcium complexes with multiple ligands such as BSA, apatite, carbonate as well as the hydrogen bond network formed in titled system. The interactions increased the solubility of Ca10 (OH)2(PO4)6 and CaCO3 and the composition of soluble complexes is nonstoichiometric. The results provided an ideal model to investigated biomineralization process.

Calcium Carbonate↗

PubMed1999

High-resolution capillary isoelectric focusing of complex protein mixtures from lysates of microorganisms.

High-resolution capillary isoelectric focusing separations of complex protein mixtures have been obtained for cellular lysates of Saccharomyces cerevisiae, Eschericia coli, and Deinococcus radiodurans. High quality separations are shown to be achievable for total protein concentrations of < 0.1 mg/mL. The separation reproducibility was examined, and the influence of the capillary inner wall coating on resolution investigated using fusedsilica capillaries coated with various hydrophilic polymers including hydroxypropyl cellulose, poly(vinyl alcohol), and linear polyacrylamide. Proteins having an isoelectric point (pI) difference of 0.004 are shown to be separated using a linear carrier ampholyte (linear pH gradient between two electrodes) of 3-10. Approximately 45 discrete peaks in the pI range of 5-7 were obtained for S. cerevisiae, approximately 80 peaks in the pI range of 4.5-8.5 for E. coli, and approximately 210 peaks in the pI range of 3-8.8 for D. radiodurans.

Bacterial Proteins↗

PubMed1999

Direct evidence that the rifamycin polyketide synthase assembles polyketide chains processively.

The assembly of the polyketide backbone of rifamycin B on the type I rifamycin polyketide synthase (PKS), encoded by the rifA-rifE genes, is terminated by the product of the rifF gene, an amide synthase that releases the completed undecaketide as its macrocyclic lactam. Inactivation of rifF gives a rifamycin B nonproducing mutant that still accumulates a series of linear polyketides ranging from the tetra- to a decaketide, also detected in the wild type, demonstrating that the PKS operates in a processive manner. Disruptions of the rifD module 8 and rifE module 9 and module 10 genes also result in accumulation of such linear polyketides as a consequence of premature termination of polyketide assembly. Whereas the tetraketide carries an unmodified aromatic chromophore, the penta- through decaketides have undergone oxidative cyclization to the naphthoquinone, suggesting that this modification occurs during, not after, PKS assembly. The structure of one of the accumulated compounds together with (18)O experiments suggests that this oxidative cyclization produces an 8-hydroxy-7, 8-dihydronaphthoquinone structure that, after the stage of proansamycin X, is dehydrogenated to an 8-hydroxynaphthoquinone.

Actinomycetales↗

PubMed1999

Antibiotic treatment of gastric lymphoma of mucosa-associated lymphoid tissue. An uncontrolled trial.

BACKGROUND: Gastric lymphoma of mucosa-associated lymphoid tissue (MALT) is related to Helicobacter pylori infection and may depend on this infection for growth. OBJECTIVE: To determine the response of gastric MALT lymphoma to antibiotic treatment. DESIGN: Prospective, uncontrolled treatment trial. SETTING: University hospital referral center and three collaborating university and community hospitals. PATIENTS: 34 patients with stage I or stage II N1 gastric MALT lymphoma. INTERVENTION: Two of three oral antibiotic regimens--1) amoxicillin, 750 mg three times daily, and clarithromycin, 500 mg three times daily; 2)tetracycline, 500 mg four times daily, and clarithromycin, 500 mg three times daily; or 3) tetracycline, 500 mg four times daily, and metronidazole, 500 mg three times daily--were administered sequentially (usually in the order written) for 21 days at baseline and at 8 weeks, along with a proton-pump inhibitor (lansoprazole or omeprazole) and bismuth subsalicylate. MEASUREMENTS: Complete remission was defined as the absence of histopathologic evidence of lymphoma on endoscopic biopsy. Partial remission was defined as a reduction in endoscopic tumor stage or 50% reduction in the size of large tumors. RESULTS: 34 patients were followed for a mean (+/-SD) of 41 +/- 16 months (range, 18 to 70 months) after antibiotic treatment. Of 28 H. pylori-positive patients, 14 (50% [95% CI, 31% to 69%]) achieved complete remission, 8 (29%) achieved partial remission (treatment eventually failed in 4 of the 8), and 10 (36% [CI, 19% to 56%]) did not respond to treatment. Treatment failed in all 6 (100% [CI, 54% to 100%]) H. pylori-negative patients. Patients with endoscopic appearance of gastritis (stage I T1 disease) were most likely to achieve complete remission within 18 months. Tumors in the distal stomach were associated with more favorable response than tumors in the proximal stomach. CONCLUSIONS: A subset of H. pylori-positive gastric MALT lymphomas, including infiltrative tumors, may respond to antibiotics. The likelihood of early complete remission seems to be greatest for superficial and distal tumors.

Anti-Bacterial Agents↗

PubMed1999

In vivo polysaccharide-specific IgG isotype responses to intact Streptococcus pneumoniae are T cell dependent and require CD40- and B7-ligand interactions.

In vivo Ig responses to soluble, haptenated polysaccharide (PS) Ags are T cell independent and do not require CD40 ligand (CD40L). However, little is known regarding the regulation of in vivo PS-specific Ig responses to intact bacteria. We immunized mice with a nonencapsulated, type 2 Streptococcus pneumoniae (R36A) and compared the parameters that regulated in vivo Ig isotype responses to the bacterial cell wall C-PS determinant, phosphorylcholine (PC), relative to Ig responses to the cell wall protein, pneumococcal surface protein A. Consistent with previous reports using soluble PS and protein Ags, the anti-PC and anti-pneumococcal surface protein A responses differed in that the anti-PC response was induced more rapidly, had a distinctive Ig isotype profile, and failed to demonstrate boosting upon secondary challenge with R36A. However, in contrast to previous studies, the IgG anti-PC response was TCR-alphabeta+ T cell dependent, required CD40L, and was blocked by administration of CTLA4 Ig. The nature of the T cell help for the anti-PC response had distinct features in that it was only partially blocked by CTLA4 Ig and was dependent upon both CD4+ and CD8+ T cells. Surprisingly, whereas the IgM anti-PC response was largely T cell independent, a strong requirement for CD40L was still observed, suggesting the possibility of an in vivo T cell-independent source for CD40L-dependent help. These data suggest that the regulatory parameters that govern in vivo Ig responses to purified, soluble PS Ags may not adequately account for PS-specific Ig responses to intact bacteria.

Animals↗

PubMed1999

Frequency of the fragile X syndrome in Chinese mentally retarded populations is similar to that in Caucasians.

Fragile X syndrome is recognized as the most common inherited cause of mental retardation in western countries. The prevalence of the fragile X syndrome in Asian populations is uncertain. We report a multi-institutional collaborative study of molecular screening for the fragile X syndrome from 1,127 Chinese mentally retarded (MR) individuals. We found that 2.8% of the Chinese MR population screened by DNA analysis had the fragile X full mutation. Our screening indicated that the fragile X syndrome prevalence was very close to that of Caucasian subjects. In addition, we found that 62.5% of fragile X chromosomes had a single haplotype for DXS548-FRAXAC1 (21-18 repeats) which was present in only 9.7% of controls. This unique distribution of microsatellite markers flanking the FMR1 CGG repeats suggests that the fragile X syndrome in Chinese populations, as in the Caucasian, may also be derived from founder chromosomes.

Alleles↗

PubMed1999

Ectopic expression of the minimal whiE polyketide synthase generates a library of aromatic polyketides of diverse sizes and shapes.

The single recombinant expressing the Streptomyces coelicolor minimal whiE (spore pigment) polyketide synthase (PKS) is uniquely capable of generating a large array of well more than 30 polyketides, many of which, so far, are novel to this recombinant. The characterized polyketides represent a diverse set of molecules that differ in size (chain length) and shape (cyclization pattern). This combinatorial biosynthetic library is, by far, the largest and most complex of its kind described to date and indicates that the minimal whiE PKS does not independently control polyketide chain length nor dictate the first cyclization event. Rather, the minimal PKS enzyme complex must rely on the stabilizing effects of additional subunits (i.e., the cyclase whiE-ORFVI) to ensure that the chain reaches the full 24 carbons and cyclizes correctly. This dramatic loss of control implies that the growing polyketide chain does not remain enzyme bound, resulting in the spontaneous cyclization of the methyl terminus. Among the six characterized dodecaketides, four different first-ring cyclization regiochemistries are represented, including C7/C12, C8/C13, C10/C15, and C13/C15. The dodecaketide TW93h possesses a unique 2,4-dioxaadamantane ring system and represents a new structural class of polyketides with no related structures isolated from natural or engineered organisms, thus supporting the claim that engineered biosynthesis is capable of producing novel chemotypes.

Ketones↗

PubMed1999

[The protective effects of total flavonoids from Lycium Barbarum L. on lipid peroxidation of liver mitochondria and red blood cell in rats].

The protective effects of total flavonoids from Lycium Barbarum L. (TFL) on lipid peroxidation in mitochondria and red blood cells (RBC) induced by oxygen radicals produced by Fe2+ cysteine system were investigated. The mitochondria lipid peroxidation (measured as malondialdehyde, MDA) was significantly inhibited by TFL with a dose-response relation between the concentrations of 0.025 and 2.0 mg/ml, and the fluidity of mitochondria membrane was also protected effectively. It was observed by scan electron microscope, that the shape of RBC in the Fe2+ system was damaged significantly. The shape of RBC was remained with the addition of TFL.

Animals↗

PubMed1999

The p65 subunit of NF-kappa B is redundant with p50 during B cell proliferative responses, and is required for germline CH transcription and class switching to IgG3.

B cells lacking individual NF-kappa B/Rel family members exhibit defects in activation programs. We generated small resting B cells lacking p65 or p50 alone, or lacking both p50 and p65, then evaluated the ability of these cells to proliferate, secrete Ig, and undergo Ig class switching. B cells lacking p65 proliferated well in response to all stimuli tested. However, these cells demonstrated an isolated defect in switching to IgG3, which was associated with a decrease in gamma 3 germline CH gene expression. Whereas, previously reported, B cells lacking p50 alone had a severe proliferative defect in response to LPS, a moderate defect in response to CD40 ligand (CD40L), and normal proliferation to Ag receptor cross-linking using dextran-conjugated anti-IgD Abs (alpha delta-dex), B cells lacking both p50 and p65 exhibited severely impaired proliferation in response to LPS, alpha delta-dex, and CD40L. This defect could be overcome by simultaneous administration of alpha delta-dex and CD40L. In response to this latter combination of stimuli, B cells lacking both p50 and p65 secreted Ig and underwent isotype switching to IgG1 as efficiently as B cells lacking p50 alone. These data demonstrate a role for the p65 subunit of NF-kappa B in germline CH gene expression as well as functional redundancy between p50 and p65 during proliferative responses.

Animals↗

PubMed1999

Mycobacterium bovis bacille Calmette-Guérin enhances pathogenicity of simian immunodeficiency virus infection and accelerates progression to AIDS in macaques: a role of persistent T cell activation in AIDS pathogenesis.

It has recently been proposed that Mycobacterium tuberculosis may enhance the pathogenicity of HIV infections and accelerate the course of HIV disease. This hypothesis has been tested in the present study using a simian immunodeficiency virus of macaques (SIVmac)/Mycobacterium bovis bacille Calmette-Guérin (BCG)-coinfected macaque model. Naive and chronically SIVmac-infected monkeys were evaluated. Following BCG inoculation, the SIVmac-infected monkeys exhibited the dominant responses of TCR-beta complementarity-determining region 3-restricted T cell subpopulations. This BCG-driven T cell activation correlated with a marked increase in viral loads in SIVmac-infected monkeys. Moreover, the prolonged T cell activation coincided with the enhanced decline of CD4+ PBL counts and the accelerated progression to clinical AIDS in the coinfected monkeys, suggesting that Mycobacterium-driven T cell activation may be the mechanism underlying the enhanced pathogenicity of AIDS virus infection in the coinfected individuals. Within 2 to 7 mo after BCG coinfection, all chronically SIVmac-infected monkeys died from SIV-induced AIDS including tuberculosis-like disease. Surprisingly, the naive monkeys manifested a T cell activation-related toxic shock syndrome and a profound depletion of CD4+ lymphocytes 2 wk after simultaneous SIVmac/BCG inoculation. These naive animals died 2 mo after SIVmac/BCG inoculation, with the evidence of the persistent SIV p27 antigenemia and SIVmac-induced disease. In contrast, the normal monkeys not infected with SIVmac survived BCG infection; the control SIVmac-infected animals showed a natural course of chronic SIV infection. Thus, results from this SIV/BCG coinfection model strongly support the hypothesis that active coinfection with HIV and Mycobacterium can impact remarkably on the AIDS virus-induced disease.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Capillary electrophoresis using diol-bonded fused-silica capillaries.

In this paper, 3-glycidoxypropyltrimethoxysilane was used to produce diol-bonded capillaries at room temperature for capillary electrophoresis (CE). A variety of standard reference compounds and authentic biological samples including ribonucleotides, peptides and proteins were used to test the columns. It was found that greatly suppressed electroosmotic flow was measured over a pH range of 3-10. Lower than 1.6% relative standard deviation (> 10 runs) in migration time was observed for the analysis of test proteins. For real samples of ribonucleotides in tumor cell extracts, approximately 1 million theoretical plates and excellent peak shapes were obtained. The high column efficiency and symmetrical peaks allowed the separation of samples with only 0.6% maximum difference in migration times. The diol-bonded fused-silica capillary columns were stable when used in a pH range of 2-8 under typical CE conditions. The column preparation method involved a simple dynamic coating procedure at room temperature, greatly simplifying the more typical static coating methods that require vacuum pumps and ovens.

Amino Acid Sequence↗

PubMed1999

Zinc modulation of AMPA receptors may be relevant to splice variants in carp retina.

With the use of the whole-cell patch clamp technique, we examined effects of zinc on AMPA receptors of isolated carp retinal horizontal cells, predominantly consisting of flop splice variants. We found that zinc ranging from 30 microM to 1 mM failed to modulate glutamate-induced currents of these cells, which is clearly distinct from the results previously obtained in superior colliculus neurons and Xenopus ooctyes. Furthermore, glutamate responses remained unchanged when zinc was co-applied with PEPA, a flop variant-preferential AMPA receptor potentiator. With the co-application of cyclothiazide, a flip variant-preferential AMPA receptor potentiator, however, a dual effect could be observed: zinc potentiated glutamate responses at low concentrations, but inhibited them at higher concentrations. These results suggest that the action of zinc on AMPA receptors may be splice variant-relevant.

Animals↗

PubMed1999

Cobalt chloride-induced signaling in endothelium leading to the augmented adherence of sickle red blood cells and transendothelial migration of monocyte-like HL-60 cells is blocked by PAF-receptor antagonist.

In response to hypoxia, sickle red blood cells (SS RBC) and leukocytes exhibit increased adherence to the vascular endothelium, while diapedesis of leukocytes through the blood vessel increases. However, the cellular signaling pathway(s) caused by hypoxia is poorly understood. We utilized CoCl2 as a mimetic molecule for hypoxia to study cellular signaling pathways. We found that in human umbilical vein endothelial cells (HUVEC), CoCl2 at 2 mM concentration induced the surface expression of a subset of CAMs (VCAM-1) and activation of transcription factor NF-kappaB in the nuclear extracts of HUVEC. Furthermore, CoCl2 also caused time-dependent tyrosine phosphorylation of mitogen-activated protein (MAP) kinase isoform ERK2 without significantly affecting ERK1, indicating ERK2 is the preferred substrate for upstream kinase of the MAPK pathway. Inhibitors of MAP kinase (PD98059) or platelet-activating factor (PAF)- receptor antagonist (CV3988) inhibited the CoCl2-induced NF-kappaB activation and VCAM-1 expression. Augmented expression of VCAM-1 led to increased SS RBC adhesion, inhibitable by a VCAM-1 antibody. Additionally, CoCl2 caused a two- to threefold increase in the rate of transendothelial migration of monocyte-like HL-60 cells and a twentyfold increase in phosphorylation of platelet endothelial cell adhesion molecules (PECAM-1). The transendothelial migration of monocytes was inhibited by an antibody to PECAM-1. Both phosphorylation of PECAM-1 and transendothelial migration of monocytes in response to CoCl2 were inhibited by protein kinase inhibitor (GF109203X) and augmented by protein phosphatase inhibitor (Calyculin A). Our data suggests that CoCl2-induced cellular signals directing increased expression of VCAM-1 in HUVEC involve downstream activation of MAP kinase and NF-kappaB, while the phosphorylation of PECAM-1 occurs as a result of activation of PKC. We conclude that PAF-receptor antagonist inhibits the CoCl2- or hypoxia-induced increase in the adhesion of SS RBC, PECAM-1 phosphorylation, and the concomitant transendothelial migration of monocytes.

Adult↗

PubMed1999

Application of capillary nongel sieving electrophoresis for gene analysis.

Capillary electrophoresis (CE) has proved to be a strong tool for DNA analysis and has found abundant applications in the fields of restriction fragment sizing, mutation screening, polymerase chain reaction (PCR) product characterizing and forensic identifying. CE may be the main alternative to slab gel electrophoresis. Capillary nongel electrophoresis is the most favorable mode when aiming for this purpose because of its advantages of long lifetime, easy operation, good reproducibility, and low expense. In this paper, a new kind of sieving matrix, with mannitol as the additive for capillary electrophoresis, as well as related methods and their application for gene analysis were reported. Nine DNA fragments amplified by multiplex PCR from a normal dystrophin gene were well separated by this system. Three different deletions were found in Duchenne muscular dystrophy (DMD) patients. Three to four copies of the sex-determination region of the Y chromosome (SRY) gene, as well as the phenylalanine hydroxylase (PAH) gene, could be detected in mixed samples. The frequencies of short tandem repeats (STR) in PAH genes was analyzed in 61 normal Chinese individuals and 6 phenylketonuria families. One case of prenatal gene diagnosis was performed. By using this matrix, CE coupled with reverse transcription PCR (RT-PCR), the analysis of the alternative splicing expression pattern of the fragile X mental retardation 1 (FMR1) gene in adult lung tissue was achieved.

Adult↗

PubMed1999

Expression of a higher-plant chloroplast psbD promoter in a cyanobacterium (Synechococcus sp. strain PCC7942) reveals a conserved cis-element, designated PGT, that differentially interacts with sequence-specific binding factors during leaf development.

The chloroplast psbD gene, which encodes the D2 subunit of photosystem II, is regulated by a blue light-responsive promoter (BLRP). We tested the ability of different regions of the barley (Hordeum vulagare) BLRP to drive transcription of the lacZ reporter gene in genomic transformants of Synechococcus sp. strain PCC7942. The barley BLRP was transcribed in Synechococcus from the same initiation sites that are used in plant chloroplasts in vivo. A region of the BLRP, residing between -83 and -112 bp upstream from the transcription initiation sites, functioned as a negative element in Synechococcus. Nucleotide sequences within this region are conserved among the psbD genes of several monocots and dicots, and with the nuclear negative regulatory element GT. Thus this new cis-element was designated Plastid GT, PGT. Proteins from chloroplasts of barley and Arabidopsis thaliana interacted with PGT in a sequence-specific and developmental-dependent manner. The DNA-protein complexes from Arabidopsis chloroplasts are composed of 60- and 38-kDa polypeptides. We postulate that GT and PGT have evolved in the nucleus and chloroplast, respectively, from a common ancestral regulatory element.

Arabidopsis↗