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PubMed2006

Coactivator as a target gene specificity determinant for histone H3 lysine 4 methyltransferases.

Activating signal cointegrator-2 (ASC-2), a coactivator of multiple transcription factors that include retinoic acid receptor (RAR), associates with histone H3-K4 methyltranferases (H3K4MTs) MLL3 and MLL4 in mixed-lineage leukemia. Here, we show that mice expressing a SET domain mutant of MLL3 share phenotypes with isogenic ASC2+/- mice and that expression and H3-K4 trimethylation of RAR target gene RAR-beta2 are impaired in ASC-2-null mouse embryo fibroblasts (MEFs) or in MEFs expressing siRNAs against both MLL3 and MLL4. We also show that MLL3 and MLL4 are found in distinct ASC-2-containing complexes rather than in a common ASC-2 complex, and they are recruited to RAR-beta2 by ASC-2. In contrast, RAR-beta2 expression is intact in MEFs devoid of menin, a component of MLL1 and MLL2 H3K4MT complexes. These results suggest that ASC-2 confers target gene specificity to MLL3 and MLL4 H3K4MT complexes and that recruitment of H3K4MTs to their target genes generally involves interactions between integral components of H3K4MT complexes and transcription factors.

Animals↗

PubMed2003

Interactions between activating signal cointegrator-2 and the tumor suppressor retinoblastoma in androgen receptor transactivation.

Activating signal cointegrator-2 (ASC-2), a cancer-amplified transcription coactivator of nuclear receptors and numerous other transcription factors, was previously shown to contain two LXXLL motifs, each of which interacts with a distinct set of nuclear receptors. In this work, we showed that ASC-2 has an indirect, separate binding site for androgen receptor (AR). Interestingly, this region overlapped with the direct interaction interfaces with the tumor suppressor retinoblastoma (Rb). Although ASC-2 alone stimulated AR transactivation in cotransfections of HeLa cells, ectopic expression of Rb effected ASC-2 to act as a transcription coactivator of AR in Rb-null Saos2 cells. These results, along with the previous report in which AR was shown to directly interact with Rb (Yeh, S., Miyamoto, H., Nishimura, K., Kang, H., Ludlow, J., Hsiao, P., Wang, C., Su, C., and Chang C. (1998) Biochem. Biophys. Res. Commun. 248, 361-367), suggest that the AR-ASC-2 interactions in vivo may involve Rb. Thus, ASC-2 appears to contain at least three distinct nuclear receptor interaction domains.

Amino Acid Motifs↗

PubMed2006

Preventive effects of phosphorylated ascorbate on ultraviolet-B induced apoptotic cell death and DNA strand cleavage through enrichment of intracellular vitamin C in skin epidermal keratinocytes.

Mortality of mouse keratinocytes Pam212 that were irradiated with ultraviolet-B (UVB) was shown to be repressed by pre-irradiated administration with L-ascorbic acid (Asc) or more markedly with Asc-2-O-phosphate (Asc2P), but not with dehydroascorbic acid (DehAsc) or Asc-2-O-alpha-glucoside (Asc2G), although not repressed by post-irradiated administration. The cytoprotection by Asc2P was restricted against UVB below 5-20 mJ/cm2, and exhibited markedly by administration for a period over 2 h, which may be caused by intracellular Asc that was accumulated via dephosphorylation of Asc2P and was increased, 6-24 h after, to levels above twice as abundant as those of Asc-administration. Pre-irradiated Asc2P-administration slightly repressed a DNA ladder-like electrophoretic pattern for UVB-irradiated keratinocytes, containing the histone-bound DNA fragments as shown by ELISA assay, and appreciably repressed the DNA-3'OH cleavage terminals as shown by terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) stain. Thus, prevention of UVB-induced cell death by Asc2P was shown to occur concurrently with inhibition of DNA cleavages and enrichment of intracellular Asc.

Animals↗

PubMed2005

Early appearance of germinal center-derived memory B cells and plasma cells in blood after primary immunization.

Immunization with a T cell-dependent antigen elicits production of specific memory B cells and antibody-secreting cells (ASCs). The kinetic and developmental relationships between these populations and the phenotypic forms they and their precursors may take remain unclear. Therefore, we examined the early stages of a primary immune response, focusing on the appearance of antigen-specific B cells in blood. Within 1 wk, antigen-specific B cells appear in the blood with either a memory phenotype or as immunoglobulin (Ig)G1 ASCs expressing blimp-1. The memory cells have mutated V(H) genes; respond to the chemokine CXCL13 but not CXCL12, suggesting recirculation to secondary lymphoid organs; uniformly express B220; show limited differentiation potential unless stimulated by antigen; and develop independently of blimp-1 expression. The antigen-specific IgG1 ASCs in blood show affinity maturation paralleling that of bone marrow ASCs, raising the possibility that this compartment is established directly by blood-borne ASCs. We find no evidence for a blimp-1-expressing preplasma memory compartment, suggesting germinal center output is restricted to ASCs and B220(+) memory B cells, and this is sufficient to account for the process of affinity maturation.

Adoptive Transfer↗

PubMed2006

Plasma cell S1P1 expression determines secondary lymphoid organ retention versus bone marrow tropism.

After induction in secondary lymphoid organs, a subset of antibody-secreting cells (ASCs) homes to the bone marrow (BM) and contributes to long-term antibody production. The factors determining secondary lymphoid organ residence versus BM tropism have been unclear. Here we demonstrate that in mice treated with FTY720 or that lack sphingosine-1-phosphate (S1P) receptor-1 (S1P1) in B cells, IgG ASCs are induced and localize normally in secondary lymphoid organs but they are reduced in numbers in blood and BM. Many IgG ASCs home to BM on day 3 of the secondary response and day 3 splenic ASCs exhibit S1P responsiveness, whereas the cells remaining at day 5 are unable to respond. S1P1 mRNA abundance is higher in ASCs isolated from blood compared to spleen, whereas CXCR4 expression is lower. Blood ASCs also express higher amounts of Kruppel-like factor (KLF)2, a regulator of S1P1 gene expression. These findings establish an essential role for S1P1 in IgG plasma cell homing and they suggest that differential regulation of S1P1 expression in differentiating plasma cells may determine whether they remain in secondary lymphoid organs or home to BM.

Animals↗

PubMed1997

Ascorbic acid in human seminal plasma is protected from iron-mediated oxidation, but is potentially exposed to copper-induced damage.

The aim of this study was to assess the interaction of endogenous ascorbate with iron and copper ions in aerobic seminal plasma. The rate of ascorbate consumption was measured by high-performance liquid chromatography and by the concentration of its primary oxidation product, ascorbyl radical (Asc.-) detected by electron spin resonance spectroscopy. The modification in the levels of Asc.- was used to investigate non-invasively and in real time whether metal ions, either present in this fluid or exogenously added, were catalytically active. The Asc.- was detected in seminal plasma as well as in whole semen of all subjects and was unaffected by superoxide dismutase, catalase or metal chelators. These findings and the rapid decrease of Asc.- under nitrogen suggest that Asc.- is probably a result of non-metal-catalysed air auto-oxidation, a reaction generating low levels of reactive oxygen species. Loading of seminal plasma with either Fe2+ or Fe3+ up to a concentration of 50 microM did not increase, or increased only slightly, the rate of ascorbate oxidation. Taking into consideration the concentrations of iron-binding proteins in this fluid, these results suggest that seminal plasma possesses a 'physiological ligand(s)' able to maintain iron ions in a catalytically inactive form. Our results indicate that citrate, which is present in seminal plasma at very high concentrations (10-25 mM), is responsible for the inhibition of iron-dependent catalysis. On the contrary, the loss of ascorbate and the levels of Asc.- were significantly increased by the addition of physiologically relevant concentrations (1 microM) of copper ions (Cu2+ but especially Cu+). We suggest that seminal plasma is potentially exposed to copper-mediated oxidation, a finding that could be of importance in situations of increased copper-loading such as in some pathological conditions or in smoking subjects.

Ascorbic Acid↗

PubMed2000

Validation of thiosulfate for neutralization of acidified sodium chlorite in microbiological testing.

At low pH, acidified sodium chlorite (ASC) has antimicrobial activity against a variety of foodborne contaminants. To evaluate the antimicrobial efficacy of ASC at specific time points posttreatment, it is necessary to halt the action of the disinfectant by removing residual chlorite or by increasing the pH. In this study, thiosulfate was investigated at varying concentrations for its effect on microbial survival and was investigated at a concentration of 0.1% in the presence of ASC for its effect on the antimicrobial and chemical activity of the test solution. Additionally, sodium thiosulfate was tested in two buffering systems, buffered peptone water (BPW) and Butterfield's phopshate buffer (BPB), for its ability to inactivate ASC chemistry. The results of this study show that, at a concentration of 0.1%, sodium thiosulfate has no deleterious effect on Escherichia coli survival and is effective in halting the antimicrobial action of ASC by eliminating the production of residual chlorite. The BPW alone and BPB in combination with thiosulfate were found to be effective inactivators of ASC chemistry.

Bacteria↗

PubMed1993

Intestinal antibody responses to oral vaccination in HIV-infected individuals.

OBJECTIVE: To examine whether and at what stage mucosal immune responsiveness is impaired during HIV-1 infection. DESIGN: Intestinal and systemic antibody-secreting cell (ASC) responses were examined in eight HIV-1-infected volunteers and 10 seronegative control subjects after oral cholera and parenteral tetanus vaccinations. METHODS: ASC numbers were determined before and after booster vaccinations by the enzyme-linked immunospot (ELISPOT) technique. This technique was performed on cell suspensions obtained from enzymatically dispersed duodenal biopsies and from peripheral blood. RESULTS: Oral cholera vaccination evoked ASC responses in the intestinal mucosa of six out of eight HIV-1-infected volunteers, including patients with advanced disease and very low levels of circulating CD4+ T cells. The intestinal cholera ASC responses in HIV-infected volunteers were comparable to those in uninfected controls with regard to both magnitude and distribution of antibody classes. Most HIV-infected volunteers with only moderately reduced CD4+ T-cell counts also responded with vaccine-specific ASC in the blood, whereas none of the patients with < 200 x 10(6)/l CD4+ T cells per litre blood had detectable circulating ASC. CONCLUSION: These findings indicate that mucosal humoral immune responsiveness to a T-cell dependent antigen is maintained in HIV-infected individuals, despite concomitant systemic humoral hyporesponsiveness.

Administration, Oral↗

PubMed1993

Ascorbic acid and proliferation of cultured rabbit keratocytes.

The effect of ascorbate and L-ascorbic acid 2-phosphate (P-Asc), a stable derivative of ascorbate, on the growth of cultured rabbit keratocytes was examined. In a 12-day culture, P-Asc (0.05-0.1 mM) and ascorbate (0.05 mM) enhanced the growth of the cells, whereas 0.1-1.0 mM ascorbate was cytotoxic to the cells. An increase in the concentration of P-Asc up to 1.0 mM resulted in no further change in the cell growth. The effect of 0.1 mM P-Asc was observed after the confluency had been achieved in the culture. The lower toxicity of P-Asc may be due to its stability. The presence of both 0.1 mM P-Asc and mouse epidermal growth factor in the medium stimulated cell growth to a higher degree than each factor alone. The results suggested that these two factors enhance the growth of keratocytes in a different manner.

Animals↗

PubMed1999

Ascorbate and dehydroascorbate modulate nitric oxide-induced vasodilations of rat coronary arteries.

Soluble guanylyl cyclase (GC) is a heme-containing protein that is a predominant target of nitric oxide (NO). This study examined whether the reductant, ascorbate (ASC), the oxidant, dehydroascorbate (DHAA), or other redox agents modulated the sensitivity of isolated rat coronary arteries to NO-induced vasodilations. Based on NO measurements with a NO-sensitive electrode, NO dilated the arteries with a pEC50 of 8.24 +/- 0.05. The potency of NO was significantly enhanced in the presence of ASC (pEC50 = 8.70 +/- 0.02) but was diminished in the presence of DHAA (pEC50 = 7.91 +/- 0.15). The potency of NO was not affected by other redox agents including dithiothreitol, beta-mercaptoethanol, diamide, 1-chloro-2,4-dinitrobenzene, ferricyanide, or ferrocyanide. Experiments involving the cyclic guanosine monophosphate (cGMP) analog, 8-Br-cGMP, and the phosphodiesterase inhibitor, isobutyl-methylxanthine, indicated that neither ASC nor DHAA has an effect on the degradation or potency of cGMP. ASC and DHAA also failed to affect vasodilations induced by diltiazem or forskolin. However, ASC and DHAA affected the potency of NO in human mesenteric arteries. The results are consistent with other evidence that ASC and DHAA affect the redox state of GC, and through this modulate arterial sensitivity to NO. This suggests that the regulation of the redox state of GC may be an additional site of modulation of the NO/cGMP pathway.

1-Methyl-3-isobutylxanthine↗

PubMed2003

L-ascorbic acid stimulates expression of smooth muscle-specific markers in smooth muscle cells both in vitro and in vivo.

The dedifferentiation of vascular smooth muscle cells (VSMCs) plays a critical role in the progression of atherosclerosis and restenosis after angioplasty. Thus, factors that stimulate smooth muscle cell differentiation should be useful for therapy for these diseases. Previously, we found that l-ascorbic acid (L-Asc) induces the expression of smooth muscle-specific genes in a pluripotent bone marrow stromal cell line, TBR-B. This finding suggests that l-Asc stimulates the differentiation of smooth muscle cells. In the present study, we investigated the effects of l-Asc and its derivatives on the differentiation state of VSMCs in vitro and in vivo. l-Asc and its long-lasting derivatives stimulated the production of smooth muscle-specific myosin heavy chain-1 (SM1) and calponin 1 in a dose-dependent manner in rat cultured VSMCs, and the elevated production of SM1 and calponin 1 was maintained for at least 2 weeks. Moreover, oral administration of 3 g/kg of l-Asc to the balloon-injured rats induced a higher expression of SM1 and calponin 1 in the injured arteries compared with that from administration of the delivery vehicle alone. These data demonstrated new biologic activity, such as the stimulation of VSMC differentiation, of l-Asc and its long-lasting derivatives. In addition, these compounds may serve as useful tools for analysis of the differentiation of VSMCs and for therapy for vascular diseases.

Animals↗

PubMed1998

A tacrolimus-related immunosuppressant with biochemical properties distinct from those of tacrolimus.

BACKGROUND: Tacrolimus (FK506) is an immunosuppressive drug 50-100 times more potent than cyclosporine (CsA), the current mainstay of organ transplant rejection therapy. Despite being chemically unrelated, CsA and tacrolimus exert their immunosuppressive effects through the inhibition of calcineurin (CaN), a critical signaling molecule during T-lymphocyte activation. Although numerous clinical studies have proven the therapeutic efficacy of drugs within this class, tacrolimus and CsA also have a strikingly similar profile of unwanted side effects. METHOD: Our objective has been to identify a less toxic immunosuppressant through the modification of ascomycin (FK520). Quantitative in vitro immunosuppression and toxicity assays have demonstrated (see the accompanying article, p. 18) that we achieved our goal with L-732,531 (indolyl-ascomycin; indolyl-ASC), a 32-O-(1-hydroxyethylindol-5-yl) ascomycin derivative with an improved therapeutic index relative to tacrolimus. RESULTS: We report that the attributes of indolyl-ASC may result from its distinctive biochemical properties. In contrast to tacrolimus, indolyl-ASC binds poorly to FK506 binding protein 12 (FKBP12), the major cytosolic receptor for tacrolimus and related compounds. However, the stability of the interaction between the FKBP12-indolyl-ASC complex and CaN is much greater than that of the FKBP12-tacrolimus complex. These distinguishing properties of indolyl-ASC result in the potent inhibition of CaN within T lymphocytes but may lower the accumulation of the drug at sites of toxicity. CONCLUSIONS: Indolyl-ASC may define those properties needed to increase the therapeutic efficacy of a macrolactam immunoregulant for treating both human autoimmune disease and organ transplant rejection.

Base Sequence↗

PubMed2004

Effects of antioxidants on coronary microvascular spasm induced by epicardial coronary artery endothelial injury in pigs.

OBJECTIVES: The effect of oxidative stress on coronary microvascular disease is unknown. We investigated whether chronic administration of ascorbic acid (ASC) or glutathione (GSH) prevents microvascular dysfunction and remodeling induced by upstream repeated coronary artery endothelial injury. METHODS: Balloon endothelial injury was repeated at the left anterior descending coronary artery (LAD), just distal to an implanted flow meter, every 2 weeks for 6 weeks in pigs. Changes in LAD blood flow induced by acetylcholine (ACh) and 5-hydroxytryptamine were assessed before each endothelial injury and at 8 weeks after the first endothelial injury in pigs without treatment (endothelial injury group, n = 12) and in pigs treated with oral ASC (3 g/day) (ASC group, n = 12) and ASC (3 g/day) plus GSH (1 g/day) (ASC + GSH group, n = 12). RESULTS: In the endothelial injury group, reduced blood flow in response to ACh was augmented from a decrease of 18 +/- 17% to a decrease of 100% (that is, zero flow, 8 weeks, P < 0.01), accompanied by an increase of ascorbyl free radicals (AFRs) in coronary sinus blood. In contrast, in the ASC + GSH group, blood flow response to ACh was altered to a decrease of 45 +/- 17% (8 weeks, P < 0.01 compared with the endothelial injury group), coronary sinus blood AFRs did not change (8 weeks, 21.4 +/- 12.5 signal intensities, P < 0.01 compared with the endothelial injury group) and the rate of platelet aggregation induced by adenosine diphosphate was small (8 weeks, 56 +/- 17%, P < 0.01 compared with the endothelial injury group). CONCLUSIONS: Chronic administration of antioxidants suppressed microvascular hypercontraction, suggesting that it may be a promising therapeutic strategy for treating coronary microvessel disorders, including microvascular angina.

6-Ketoprostaglandin F1 alpha↗

PubMed2004

Atypical squamous cells of undetermined significance in girls and women.

OBJECTIVE: To estimate the outcome of adolescents with atypical squamous cells of undetermined significance (ASC-US) on cytology. METHODS: A review of ASC-US cytology in girls and women aged 10-19 years between 1995 and 1999 was performed. The cytologic and histologic follow-up of each patient was evaluated. The outcome was recorded as the most significant (highest grade) subsequent cervical smear or biopsy. RESULTS: Overall, 535 of 7897 (6.8%) cervical cytologic specimens were reported as ASC-US. The study group consisted of 398 patients for whom pathologic follow-up was available. The mean duration of follow-up was 19 months. Follow-up consisted of repeat cytology in 251 (63%) patients and colposcopy with cervical biopsies and/or endocervical curettage in 147 (37%) of the adolescents. Two hundred fifty-three (64%) adolescents had no pathologic abnormalities on follow-up. Persistent ASC-US was identified in 65 (16%), low-grade squamous intraepithelial lesions/cervical intraepithelial neoplasia (CIN) 1 was found in 44 (11%) and high-grade squamous intraepithelial lesions/CIN 2 or 3 occurred in 36 (9%) of the adolescents. No cases of invasive carcinoma were found. CONCLUSIONS: Among adolescents with ASC-US, the rate of squamous intraepithelial lesions/CIN is similar to that of adults. Although the optimal management of ASC-US in adolescents is unknown, these patients warrant close follow-up. LEVEL OF EVIDENCE: III

Adolescent↗

PubMed2005

Adherence to guidelines for follow-up of low-grade cytologic abnormalities among medically underserved women.

OBJECTIVE: To determine whether women in the National Breast and Cervical Cancer Early Detection Program (NBCCEDP) who had findings on a Papanicolaou (Pap) test of atypical squamous cells of undetermined significance (ASC-US) or low-grade squamous intraepithelial lesions (LSIL) were followed up in accordance with the interim guidelines for management of abnormal cervical cytology. METHODS: For this study period, the guidelines for a Pap result of ASC-US or LSIL specified follow-up by Pap tests repeated every 4 to 6 months for 2 years. If a second report of ASC-US or LSIL was made, the patient was to have colposcopy. We analyzed data from 10,004 women who had a result of ASC-US or LSIL followed by a second ASC-US or LSIL from 1991-2000. RESULTS: As judged by the guidelines, 44% of women who had 2 low-grade abnormalities were followed up appropriately with colposcopy. Among women with 2 ASC-US results, those aged less than 30 years were more likely to receive colposcopy than the other age groups, while women who were aged 60 years and older were more likely to be followed up with a third Pap test. For each of the 4 result groups, American Indian or Alaska Native women had the highest percentages of a third Pap test, whereas Black or African-American women had a higher percentage of no follow-up. CONCLUSION: More than one half of the women studied were not followed up in accordance with the established guidelines for managing abnormal cervical cytology. Factors such as age and race or ethnicity influence whether women with cytologic abnormalities receive appropriate follow-up.

Adult↗

PubMed2005

A clinicopathologic study of primary adenosquamous carcinoma of the liver.

BACKGROUND: Adenosquamous carcinoma (ASC) is a rare tumor of the liver, which carries a poor prognosis. In this study, we reviewed reported cases of ASC and examined their clinicopathologic features. MATERIALS AND METHODS: A computer MEDLINE search found 65 histologically defined primary ASC cases reported in the literature from 1975 to 2003, including our case. Of these, detailed data were obtained for 42 cases, and these were subsequently investigated clinicopathologically. RESULTS: Among the 42 cases, 34 were reported to have died of ASC and 5 cases were alive at the time of the study. The mean survival of these 34 cases was 8.7 months. Multivariate analysis revealed that lymph node metastasis and the elevation of total bilirubin were associated with poor survival after surgery, and lymph node metastasis, intrahepatic metastasis, location of tumor in the right lobe, and the pathologic stage were significant factors for all cases. CONCLUSION: The current study highlights the prognostic factors of ASC of the liver, showing that the prognosis for patients with ASC is poor.

Carcinoma, Adenosquamous↗

PubMed2003

Drought-induced changes in the redox state of alpha-tocopherol, ascorbate, and the diterpene carnosic acid in chloroplasts of Labiatae species differing in carnosic acid contents.

To assess antioxidative protection by carnosic acid (CA) in combination with that of other low-molecular weight (M(r)) antioxidants (alpha-tocopherol [alpha-T] and ascorbate [Asc]) in chloroplasts, we measured endogenous concentrations of these antioxidants, their redox states, and other indicators of oxidative stress in chloroplasts of three Labiatae species, differing in their CA contents, exposed to drought stress in the field. Damage to the photosynthetic apparatus was observed neither in CA-containing species (rosemary [Rosmarinus officinalis]) and sage [Salvia officinalis]) nor in CA-free species (lemon balm [Melissa officinalis]) at relative leaf water contents between 86% and 58%, as indicated by constant maximum efficiency of photosystem II photochemistry ratios and malondialdehyde levels in chloroplasts. The three species showed significant increases in alpha-T, a shift of the redox state of alpha-T toward its reduced state, and increased Asc levels in chloroplasts under stress. Lemon balm showed the highest increases in alpha-T and Asc in chloroplasts under stress, which might compensate for the lack of CA. Besides, whereas in rosemary and sage, the redox state of CA was shifted toward its oxidized state and the redox state of Asc was kept constant, lemon balm displayed a shift of the redox state of Asc toward its oxidized state under stress. In vitro experiments showed that both CA and Asc protect alpha-T and photosynthetic membranes against oxidative damage. These results are consistent with the contention that CA, in combination with other low-M(r) antioxidants, helps to prevent oxidative damage in chloroplasts of water-stressed plants, and they show functional interdependence among different low-M(r) antioxidants in chloroplasts.

Abietanes↗

PubMed2003

Dehydroascorbate uptake activity correlates with cell growth and cell division of tobacco bright yellow-2 cell cultures.

Recently, ascorbate (ASC) concentration and the activity of a number of enzymes from the ASC metabolism have been proven to correlate with differences in growth or cell cycle progression. Here, a possible correlation between growth and the activity of a plasma membrane dehydroascorbate (DHA) transporter was investigated. Protoplasts were isolated from a tobacco (Nicotiana tabacum) Bright Yellow-2 cell culture at different intervals after inoculation and the activity of DHA transport was tested with (14)C-labeled ASC. Ferricyanide (1 mM) or dithiothreitol (1 mM) was included in the test to keep the external (14)C-ASC in its oxidized respectively reduced form. Differential uptake activity was observed, correlating with growth phases of the cell culture. Uptake of DHA in cells showed a peak in exponential growth phase, whereas uptake in the presence of dithiothreitol did not. The enhanced DHA uptake was not due to higher endogenous ASC levels that are normally present in exponential phase because preloading of protoplasts of different ages did not affect DHA uptake. Preloading was achieved by incubating cells before protoplastation for 4 h in a medium supplemented with 1 mM DHA. In addition to testing cells at different growth phases, uptake of DHA into the cells was also followed during the cell cycle. An increase in uptake activity was observed during M phase and the M/G1 transition. These experiments are the first to show that DHA transport activity into plant cells differs with cell growth. The relevance of the data to the action of DHA and ASC in cell growth will be discussed.

Ascorbic Acid↗